A method for preparing a multilayer spacer continuous gradient structure liquid filtration material

Abstract

The application relates to the technical field of filter materials, and discloses a preparation method of a multilayer interval type continuous gradient structure liquid filter material, and provides the preparation method of the multilayer interval type continuous gradient structure liquid filter material. In the method, the fibers of the dust-containing layer adopt a skin-core structure with PP resin as a core layer and PE resin as a skin layer. The method uses cross-laying, puncture hot baking and multi-roller stretching to composite the filter monomers made of the dust-containing layer into the multilayer interval type continuous gradient structure liquid filter material. In the puncture hot baking, the fibers of the dust-containing layer of the filter monomers can enter the dust-containing layer of the adjacent filter monomers to form fiber entanglement points. The hot baking can make the PE resin of the skin layer melt and form a bonding reinforced fiber entanglement point at the fiber entanglement point, so that the composite strength of the material is significantly increased. The cross-laying and the multi-roller stretching can flatten the puncture holes caused by the puncture to improve the flatness of the surface of the material and ensure that the material will not be significantly deformed.

Description

Technical Field

[0001] This invention relates to the field of filter material technology, and in particular to a method for preparing a multi-layered, continuously graded liquid filter material. Background Technology

[0002] Traditional filter materials mainly consist of a single-layer filter membrane. However, in actual filtration environments, the filter medium contains a large number of solid particles. These solid particles are intercepted on the filter membrane, and their accumulation leads to low filtration performance. Furthermore, the solid particles cause friction on the filter membrane, resulting in wear. Therefore, to address these issues, existing technologies add a pre-filtration layer to the filter membrane to intercept solid particles. Currently, the pre-filtration layer mainly consists of a three-dimensional dust-holding layer, commonly made of non-woven fabric from polyester fibers. Because non-woven fabric is relatively soft, a reinforcing layer is needed to maintain its shape under filtration pressure, ensuring sufficient space for solid particles.

[0003] The amount of solid particles that nonwoven fabric can hold is greatly affected by the diameter of the polyester fibers inside the nonwoven fabric. The smaller the fiber diameter, the larger the dust holding space per unit volume. However, the smaller the fiber diameter, the looser the structure of the nonwoven fabric, and the thinner the layered structure it can form. Therefore, to achieve a certain dust holding capacity, multiple layers of nonwoven fabric need to be stacked to make its thickness meet the application standards. For example, CN111876905A discloses a multilayer meltblown nonwoven fabric and its preparation method. This material uses multiple layers of nonwoven fabric with different fiber diameters stacked together, so that the filter material can filter particles of different sizes in batches, thereby increasing the dust holding capacity of the filter material.

[0004] Currently, existing technologies for laminating multilayer nonwoven fabrics typically employ processes such as spot welding, adhesive bonding, needle punching, and hydroentangling. Spot welding causes the fibers at the weld points of the dust-holding layer to fuse together, disrupting the internal space of the weld layer and reducing its dust-holding capacity. Adhesive bonding alters the fiber diameter of the composite surface, reducing the size of filterable solid particles. Needle punching uses solid needles to penetrate the fibers of the dust-holding layer into the interior of adjacent nonwoven fabrics, creating fiber entanglement points. Hydroentangling uses high-pressure water jets to penetrate the fibers into the interior of adjacent nonwoven fabrics, creating fiber entanglement points. Currently, spunlace and needle punching do not significantly damage the internal space of nonwoven fabrics and do not significantly reduce the dust holding capacity of nonwoven fabrics. Therefore, needle punching and spunlace are more important than point welding and adhesives in the dust holding layer composite process. However, the composite strength of needle punching and spunlace is lower than that of point welding and adhesives. In addition, needle punching and spunlace will produce puncture holes on the material surface. These puncture holes will reduce the flatness of the material surface and make it easier for larger particles to accumulate at the puncture holes. This will cause the material surface to form a dirt accumulation layer faster, and the dirt accumulation on the material surface will be faster than that inside the material, leading to the failure of the entire material. Summary of the Invention

[0005] This invention addresses the problems of low bonding strength and puncture holes in existing technologies for composite multi-layer dust-collecting layers using puncture techniques. It provides a method for preparing a multi-layer, continuously gradient structured liquid filter material. In this method, the dust-collecting layer fibers utilize a core-shell structure with PP resin as the core and PE resin as the sheath. The method employs cross-laying, puncture-heat drying, and multi-roller stretching to composite the filter monomers made from the dust-collecting layer into a multi-layer, continuously gradient structured liquid filter material. The puncture-heat drying process allows the dust-collecting layer fibers of the filter monomers to enter the dust-collecting layers of adjacent filter monomers, forming fiber entanglement points. The heat drying process melts the PE resin sheath and forms adhesive reinforcement at the fiber entanglement points, significantly increasing the composite strength of the material. The cross-laying and multi-roller stretching process flattens the puncture holes generated by puncture, improving the surface smoothness of the material and ensuring that the material does not deform significantly.

[0006] The specific technical solution of this invention is as follows:

[0007] A method for preparing a multi-layered, continuously gradient structured liquid filter material includes the following steps: PP resin and PE resin are spunbonded to form a dust-holding layer; PP resin is melt-blown onto the surface of the dust-holding layer to form a skeleton layer; the skeleton layer and the dust-holding layer on the surface of the dust-holding layer are cold-pressed to form filter monomers; and several filter monomers are sequentially cross-laid, punctured, heat-dried, and multi-roller stretched to form a multi-layered liquid filter skeleton material.

[0008] The dust-collecting layer consists of a PP resin core layer and a PE resin outer layer.

[0009] The cross-laying method involves stacking adjacent filter cells at a staggered angle of 30° to 60°.

[0010] The tensile strength of the multi-roller drawing is 3~8 N / m.

[0011] This invention provides a method for preparing a multi-layered, continuously gradient structure liquid filter material. The method uses cross-laying, puncture heating, and multi-roller stretching to composite multiple layers of filter monomers made of dust-holding layers to form a multi-layered, continuously gradient structure liquid filter material. The puncture heating in this method does not significantly change the dust-holding capacity of the dust-holding layer and can significantly improve the bonding strength of the material. Cross-laying and multi-roller stretching can flatten the puncture holes formed by puncture and improve the flatness of the material, without causing excessive deformation of the material.

[0012] The dust-collecting layer of this invention has a core-sheath structure, with a core layer of PP resin and a sheath layer of PE resin. When the dust-collecting layer fiber of this structure is punctured and heated, the puncture will insert the fiber of the dust-collecting layer of the filter monomer into the dust-collecting layer of the adjacent filter monomer and form fiber entanglement points. The heating can melt the PE resin sheath layer of the dust-collecting layer fiber, while the internal PP resin core layer will not deform. The molten PE resin will form a bond at the fiber entanglement points, thereby reinforcing the fiber entanglement points and significantly improving the bonding strength of the material after puncture and bonding.

[0013] Because the puncture process used in this invention creates puncture holes on the surface of the material, these holes reduce the surface smoothness, making it easier for dirt to accumulate and causing the surface to fail faster than the interior. Therefore, this invention proposes multi-roller stretching after puncture to flatten the puncture holes and improve surface smoothness. However, in practice, this invention found that stacking filter units in the same direction during multi-roller stretching resulted in different circumferential structural stresses. Stretching along the material's extension direction caused significant deformation, while stretching at an angle to the extension direction prevented deformation. Based on these characteristics, this invention proposes a cross-laying method where adjacent filter units are stacked at a 30-60° staggered angle. This results in uniform structural stress in the composite material, allowing the puncture holes to be flattened without significantly altering the material's deformation during multi-roller stretching.

[0014] Preferably, in the spunbond process, the mass fraction of PP resin is 65-75 parts and the mass fraction of PE resin is 25-35 parts.

[0015] Preferably, in the meltblown process, the melt flow index of the PP resin is 400~600 g / min.

[0016] Preferably, the conditions for the meltblown process include: the temperature of the screw extrusion unit is 160~170 ℃.

[0017] Preferably, the conditions for the meltblown process also include: meltblown die head temperature of 160~170 ℃, hot air temperature of 160~170 ℃, and air pressure of 0.1~0.5 MPa.

[0018] Preferably, the temperature of the screw extrusion device is 160~170 ℃.

[0019] Preferably, the spinning conditions include: meltblown die temperature 160~170 ℃, hot air temperature 160~170 ℃, air pressure 0.1~0.5 MPa, and the basis weight of the skeleton layer is 2~5 g / cm³. 2 The basis weight of the dust-holding layer is 5~15 g / cm³. 2 The fiber diameter of the dust-collecting layer is 2~20 μm.

[0020] Preferably, the puncture is one or both of needle puncture and hydroentangling, and the puncture direction is to insert the needle once perpendicular to the material surface as the plane.

[0021] Preferably, the multi-roller drafting includes circumferential drafting, which includes circumferential six-part drafting, circumferential eight-part drafting, and circumferential twelve-part drafting.

[0022] Preferably, the baking temperature is 100~110 ℃.

[0023] Compared with the prior art, this application has the following technical effects:

[0024] This invention provides a method for preparing a multi-layered, continuously graded liquid filter material. The method uses a core-skin structure with PP resin as the core layer and PE resin as the sheath layer for the dust-holding layer fibers. The method employs cross-laying, puncture-heat drying, and multi-roller stretching to composite the filter monomers made from the dust-holding layer into a multi-layered, continuously graded liquid filter material. During puncture-heat drying, the dust-holding layer fibers of the filter monomers can enter the dust-holding layers of adjacent filter monomers to form fiber entanglement points. Heat drying melts the PE resin in the sheath layer and forms adhesive reinforcement at the fiber entanglement points, significantly increasing the composite strength of the material. Cross-laying and multi-roller stretching flatten the puncture holes produced by puncture, improving the surface smoothness of the material and ensuring that the material does not deform significantly. Detailed Implementation

[0025] The present invention will be further described below with reference to embodiments.

[0026] Example 1:

[0027] A multi-layered, continuously graded liquid filter material, characterized by comprising the following steps:

[0028] Step 1: 70 parts of PP resin are injected into a screw extruder (operating temperature 165℃) to form molten PP resin. 30 parts of PE resin are injected into a screw extruder (operating temperature 120℃) to form molten PE resin. The molten PP and molten PE resins are then fed separately into a spinning box and extruded through a core-sheath structure spinneret to form a core-sheath structure (PE resin sheath, PP resin core, with a mass ratio of sheath to core of 1:6). After being blown and cooled, the melt-spun filaments are formed. These filaments are then passed through a gyratory device on a web forming machine to form a dust-collecting layer (fiber diameter 2~20 μm, basis weight 10 g / cm³). 2 The second resin (PP resin with a melt index of 400~600 g / min) is injected into a screw extruder (operating temperature of 165℃) to form molten second resin. This molten second resin is then injected into a melt-blowing device, and a skeleton layer (with a basis weight of 3 g / cm³) is melt-blown onto the surface of the dust-collecting layer. 2 The preform is made under the following melt-blowing conditions: melt-blowing die head temperature is 165 ℃, and hot air temperature is 165 ℃.

[0029] Step 2: The preform obtained in Step 1 is cold-pressed through a cold press roller (cold press roller temperature is 105 ℃) (point pressing, pressing point area is 8%, roller pressing speed is 4 m / min, and the pressure direction is from the skeleton layer to the dust holding layer) to make a filter unit.

[0030] Step 3: Cross-lay the 10 layers of filter monomers obtained in Step 2. The cross-laying method is to overlap adjacent filter monomers at a 45° staggered angle. After overlapping, perform puncture and heat drying. Puncture is done by needle punching. The needle punching direction is with the material surface as the plane. First, the needle is inserted vertically from top to bottom once, and then from bottom to top once. After the needle punching is completed, place it in a heat drying device with a working temperature of 105℃ for 5 minutes. After heat drying, cool it to 70℃ and then perform multi-roll stretching. The stretching direction is circumferential eight-part stretching, and the stretching strength is 5 N / m. After multi-roll stretching, cool it to room temperature to form a multi-layered, intermittent, continuously gradient structure liquid filter material.

[0031] Example 2:

[0032] A multi-layered, continuously graded liquid filter material, characterized by comprising the following steps:

[0033] Step 1: 65 parts of PP resin are injected into a screw extruder (operating temperature 165℃) to form molten PP resin. 35 parts of PE resin are injected into a screw extruder (operating temperature 120℃) to form molten PE resin. The molten PP resin and molten PE resin are then fed into a spinning box and extruded through a core-sheath structure spinneret to form a core-sheath structure (PE resin sheath, PP resin core, with a mass ratio of sheath to core of 1:5). After being blown and cooled, the melt-spun filaments are formed. The filaments are then passed through a gyratory device on a web forming machine to form a dust-collecting layer (fiber diameter 2~20 μm, basis weight 5 g / cm³). 2 The second resin (PP resin with a melt index of 400~600 g / min) is injected into a screw extruder (operating temperature of 165℃) to form molten second resin. This molten second resin is then injected into a melt-blowing device, and a skeleton layer (with a basis weight of 2 g / cm³) is melt-blown onto the surface of the dust-collecting layer. 2 The preform is made under the following melt-blowing conditions: melt-blowing die head temperature is 165 ℃, and hot air temperature is 165 ℃.

[0034] Step 2: The preform obtained in Step 1 is cold-pressed through a cold press roller (cold press roller temperature is 100 ℃) (point pressing, pressing point area is 3%, roller pressing speed is 3 m / min, pressure direction is from the skeleton layer to the dust holding layer) to make filter unit;

[0035] Step 3: Cross-lay the 10 layers of filter monomers obtained in Step 2. The cross-laying method is to overlap adjacent filter monomers at a 30° staggered angle. After overlapping, perform puncture and heat drying. Puncture is done by needle punching. The needle punching direction is with the material surface as the plane. First, the needle is inserted vertically from top to bottom once, and then from bottom to top once. After the needle punching is completed, place it in a heat drying device with a working temperature of 100 ℃ for 5 min. After heat drying, cool to 80 ℃ and then perform multi-roll stretching. The stretching direction is circumferential twelve-part stretching, and the stretching strength is 3 N / m. After multi-roll stretching, cool to room temperature to form a multi-layered, intermittent, continuously gradient structure liquid filter material.

[0036] Example 3:

[0037] A multi-layered, continuously graded liquid filter material, characterized by comprising the following steps:

[0038] Step 1: 75 parts of PP resin are injected into a screw extruder (operating temperature 165℃) to form molten PP resin. 25 parts of PE resin are injected into a screw extruder (operating temperature 120℃) to form molten PE resin. The molten PP resin and molten PE resin are then fed into a spinning box and extruded through a core-sheath structure spinneret to form a core-sheath structure (PE resin sheath, PP resin core, with a mass ratio of sheath to core of 1:7). After being blown and cooled, the melt-spun filaments are formed. The filaments are then passed through a gyratory device on a web forming machine to form a dust-collecting layer (fiber diameter 2~20 μm, basis weight 15 g / cm³). 2 The second resin (PP resin with a melt index of 400~600 g / min) is injected into a screw extruder (operating temperature of 165℃) to form molten second resin. The molten second resin is then injected into a melt-blowing device, and a skeleton layer (with a basis weight of 5 g / cm³) is melt-blown onto the surface of the dust-collecting layer. 2 The preform is made under the following melt-blowing conditions: melt-blowing die head temperature is 165 ℃, and hot air temperature is 165 ℃.

[0039] Step 2: The preform obtained in Step 1 is cold-pressed using a cold press roller (cold press roller temperature is 110 ℃) (point pressing, pressing point area is 20%, roller pressing speed is 5 m / min, pressure direction is from the skeleton layer to the dust holding layer) to make filter unit;

[0040] Step 3: Cross-lay the 10 layers of filter monomers obtained in Step 2. The cross-laying method is to overlap adjacent filter monomers at a 60° staggered angle. After overlapping, puncture and heat drying are performed. Puncture is done by needle punching. The needle punching direction is with the material surface as the plane. First, the needle is inserted vertically from top to bottom once, and then vertically from bottom to top once. After needle punching, the material is placed in a heat drying device with a working temperature of 110℃ for 5 minutes. After heat drying, the material is cooled to 80℃ and then subjected to multi-roller stretching. The stretching direction is circumferential six-part stretching with a stretching strength of 8 N / m. After multi-roller stretching, the material is cooled to room temperature to form a multi-layered, intermittent, continuously gradient structure liquid filter material.

[0041] Example 4:

[0042] A multi-layered, continuously graded liquid filter material, characterized by comprising the following steps:

[0043] Step 1: 70 parts of PP resin are injected into a screw extruder (operating temperature 165℃) to form molten PP resin. 30 parts of PE resin are injected into a screw extruder (operating temperature 120℃) to form molten PE resin. The molten PP and molten PE resins are then fed separately into a spinning box and extruded through a core-sheath structure spinneret to form a core-sheath structure (PE resin sheath, PP resin core, with a mass ratio of sheath to core of 1:6). After being blown and cooled, the melt-spun filaments are formed. These filaments are then passed through a gyratory device on a web forming machine to form a dust-collecting layer (fiber diameter 2~20 μm, basis weight 10 g / cm³). 2 The second resin (PP resin with a melt index of 400~600 g / min) is injected into a screw extruder (operating temperature of 165℃) to form molten second resin. This molten second resin is then injected into a melt-blowing device, and a skeleton layer (with a basis weight of 3 g / cm³) is melt-blown onto the surface of the dust-collecting layer. 2 The preform is made under the following melt-blowing conditions: melt-blowing die head temperature is 165 ℃, and hot air temperature is 165 ℃.

[0044] Step 2: The preform obtained in Step 1 is cold-pressed through a cold press roller (cold press roller temperature is 105 ℃) (point pressing, pressing point area is 8%, roller pressing speed is 4 m / min, and the pressure direction is from the skeleton layer to the dust holding layer) to make a filter unit.

[0045] Step 3: Cross-lay the 10 layers of filter monomers obtained in Step 2. The cross-laying method is to overlap adjacent filter monomers at a 45° staggered angle. After overlapping, perform piercing and hot drying. The piercing is done by hydroentangling. The hydroentangling direction is with the material surface as the plane. First, the high-pressure water jet is used to impact the material once from top to bottom, and then the high-pressure water jet is used to impact the material once from bottom to top. After hydroentangling, dry the material to room temperature, and then place it in a hot drying device with a working temperature of 105℃ for 5 minutes. After hot drying, cool the material to 70℃ and then perform multi-roll stretching. The stretching direction is circumferential eight-part stretching, and the stretching strength is 5 N / m. After multi-roll stretching, cool the material to room temperature to form a multi-layered, intermittent, continuously gradient structure liquid filter material.

[0046] Example 5:

[0047] A multi-layered, continuously graded liquid filter material, characterized by comprising the following steps:

[0048] Step 1: 70 parts of PP resin are injected into a screw extruder (operating temperature 165℃) to form molten PP resin. 30 parts of PE resin are injected into a screw extruder (operating temperature 120℃) to form molten PE resin. The molten PP and molten PE resins are then fed separately into a spinning box and extruded through a core-sheath structure spinneret to form a core-sheath structure (PE resin sheath, PP resin core, with a mass ratio of sheath to core of 1:6). After being blown and cooled, the melt-spun filaments are formed. These filaments are then passed through a gyratory device on a web forming machine to form a dust-collecting layer (fiber diameter 2~20 μm, basis weight 10 g / cm³). 2 The second resin (PP resin with a melt index of 400~600 g / min) is injected into a screw extruder (operating temperature of 165℃) to form molten second resin. This molten second resin is then injected into a melt-blowing device, and a skeleton layer (with a basis weight of 3 g / cm³) is melt-blown onto the surface of the dust-collecting layer. 2 The preform is made under the following melt-blowing conditions: melt-blowing die head temperature is 165 ℃, and hot air temperature is 165 ℃.

[0049] Step 2: The preform obtained in Step 1 is cold-pressed through a cold press roller (cold press roller temperature is 105 ℃) (point pressing, pressing point area is 8%, roller pressing speed is 4 m / min, and the pressure direction is from the skeleton layer to the dust holding layer) to make a filter unit.

[0050] Step 3: Cross-lay the 10 layers of filter monomers obtained in Step 2. The cross-laying method is to overlap adjacent filter monomers at a 45° staggered angle. After overlapping, puncture and heat drying are performed. Puncture is done by needle punching and hydroentangling. Using the material surface as a plane, the needle is first used to vertically puncture once from top to bottom. Then, 5 mm away from the line connecting the needle points, high-pressure water is used to vertically impact and puncture once from bottom to top. After puncture, dry to room temperature, and then place in a heat drying device with a working temperature of 105℃ for 5 minutes. After heat drying, cool to 70℃ and then perform multi-roll stretching. The stretching direction is circumferential eight-part stretching, and the stretching strength is 5 N / m. After multi-roll stretching, cool to room temperature to form a multi-layered, intermittent, continuously gradient structure liquid filter material.

[0051] Example 6:

[0052] A multi-layered, continuously graded liquid filter material, characterized by comprising the following steps:

[0053] Step 1: 70 parts of PP resin are injected into a screw extruder (operating temperature 165℃) to form molten PP resin. 30 parts of PE resin are injected into a screw extruder (operating temperature 120℃) to form molten PE resin. The molten PP and molten PE resins are then fed separately into a spinning box and extruded through a core-sheath structure spinneret to form a core-sheath structure (PE resin sheath, PP resin core, with a mass ratio of sheath to core of 1:6). After being blown and cooled, the melt-spun filaments are formed. These filaments are then passed through a gyratory device on a web forming machine to form a dust-collecting layer (fiber diameter 2~20 μm, basis weight 10 g / cm³). 2 The second resin (PP resin with a melt index of 400~600 g / min) is injected into a screw extruder (operating temperature of 165℃) to form molten second resin. This molten second resin is then injected into a melt-blowing device, and a skeleton layer (with a basis weight of 3 g / cm³) is melt-blown onto the surface of the dust-collecting layer. 2 The preform is made under the following melt-blowing conditions: melt-blowing die head temperature is 165 ℃, and hot air temperature is 165 ℃.

[0054] Step 2: The preform obtained in Step 1 is cold-pressed through a cold press roller (cold press roller temperature is 105 ℃) (point pressing, pressing point area is 8%, roller pressing speed is 4 m / min, and the pressure direction is from the skeleton layer to the dust holding layer) to make a filter unit.

[0055] Step 3: Cross-lay the 10 layers of filter monomers obtained in Step 2. The cross-laying method is to overlap adjacent filter monomers at a 45° staggered angle. After stacking, perform puncture and heat drying. The puncture method is needle punching-hydroentanglement-needle punching. Using the material surface as the plane, first use two rows of parallel puncture needles to vertically puncture once from top to bottom. At the interval between the parallel puncture holes, use high-pressure water jets to vertically impact and puncture once from bottom to top. After puncture, dry to room temperature, and then place in a heat drying device with a working temperature of 105℃ for 5 minutes. After heat drying, cool to 70℃ and then perform multi-roll stretching. The stretching direction is circumferential eight-part stretching, and the stretching strength is 5 N / m. After multi-roll stretching, cool to room temperature to form a multi-layered, intermittent, continuously gradient structure liquid filter material.

[0056] Comparative Example 1:

[0057] Compared with Example 1, Comparative Example 1 used an infrared band hot press roller to replace the puncture heat drying for compounding the multilayer filter monomers, and all other conditions were the same as in Example 1.

[0058] Comparative Example 2:

[0059] Compared with Example 1, Comparative Example 2 used polyolefin hot melt adhesive instead of puncture heat drying to composite the multilayer filter monomers, and all other conditions were the same as in Example 1.

[0060] Comparative Example 3:

[0061] Compared with Example 1, Comparative Example 3 did not use cross-laying, and all multilayer filter monomers were stacked along the material extension direction. All other conditions were the same as in Example 1.

[0062] Comparative Example 4:

[0063] Compared with Example 1, Comparative Example 4 did not involve multi-roller stretching, but all other conditions were the same as in Example 1.

[0064] Comparative Example 5:

[0065] Compared with Example 1, the meltblown layer fiber in Comparative Example 5 was made by blending PP resin and PE resin, and the other conditions were the same as in Example 1.

[0066] Example of detection:

[0067] The peel strength of the filter monomers prepared in Examples 1 to 6 and Comparative Examples 1 to 8, the peel strength of the multilayer liquid filter frame material, the dust holding life and the material deformation of the multilayer liquid filter frame material were tested.

[0068] The dust holding capacity test method refers to "ISO 16889:2008 Hydraulic filters - Evaluation of the filtration performance of filter elements by the multiple pass method";

[0069] The dust holding capacity service life test method refers to the time after the material reaches its maximum dust holding capacity, as specified in ISO 16889:2008 Hydraulic transmission filters - Evaluation of the filtration performance of filter elements by the multiple pass method.

[0070] The peel strength test method refers to "GB / T8808-1988 T-type peel strength test method for flexible composite plastics", and the instrument used for peel testing is XLW (PC) intelligent electronic tensile testing machine;

[0071] The material deformation test method measures the volume of the material without multi-roller drawing and records the measured value as V1. Then, it measures the volume of the material with multi-roller drawing and records the measured value as V2. The deformation is (V2-V1) / V1.

[0072] The test results are shown in Table 1;

[0073] Table 1 Test Results

[0074]

[0075] As shown in Table 1, the glass strength of the multi-layered, continuously tapered liquid filter materials provided in Examples 1 to 6 is 8.2~8.8 N / M. 2Dust holding capacity is 684~750 g / m³ 2 The dust-containing cycle is 816~980 min, and the material deformation is 2.34~2.85%.

[0076] Comparative Example 1 uses an infrared band hot press roller to replace the puncture heat drying process for compounding multi-layer filter monomers. The dust holding capacity of Comparative Example 1 is 431 g / m³. 2 The peel strength is 8.9 N / M. 2 Compared with Example 1, there was no significant difference in the peel strength of the material in Comparative Example 1, but the dust holding capacity was significantly reduced. The above results indicate that the peel strength of the filter material made by puncture heat drying of the multilayer filter monomers is comparable to that of the filter material made by point welding, but the dust holding capacity is significantly higher than that of the filter material made by point welding. In addition, analysis of the internal structure of the material revealed that the internal spatial structure of the filter material made by the method of this application does not change significantly. At the same time, the fiber entanglement points formed inside the material are bonded under the action of the PE resin surface, and the bonding strength of the fiber entanglement points is significantly improved, so that the peel strength of the material can reach the peel strength of the point welding composite.

[0077] Comparative Example 2 did not use polyolefin hot melt adhesive to replace puncture heat drying for compounding multilayer filter monomers. The dust holding capacity of Comparative Example 2 was 569 g / m³. 2 The peel strength is 8.1 N / M. 2 Compared with Example 1, Comparative Example 2 showed a reduced peel strength and a significantly lower dust holding capacity than Example 1. The above results indicate that the dust holding capacity and peel strength of the filter material prepared by the puncture and heat-drying process provided by the present invention are higher than those of the filter material prepared by adhesive composite. In particular, the dust holding capacity of the material prepared by puncture and heat-drying composite in this application is significantly higher than that of the filter material prepared by adhesive composite.

[0078] In Comparative Example 3, no cross-laying was used. From the material deformation results of Comparative Example 3 and Example 1, it can be seen that the deformation of Example 1 is only 2.34%, while the material deformation of Comparative Example 3 reaches 6.87%. Analysis of the actual operation process revealed that when the material without cross-laying is subjected to multi-roll drawing, the circumferential structural stress of the material is uneven. The direction with low stress is easily stretched to deform, while the direction with high stress does not deform easily. Therefore, if the puncture hole is to be flattened, there will be a problem of excessive deformation in the direction with low stress. However, the circumferential structural stress of the material after cross-laying is more uniform, and the puncture hole can be flattened without easily deforming during multi-roll drawing.

[0079] Comparative Example 4 did not involve multi-roller stretching. From the dust holding life and dust holding capacity results of Comparative Example 4 and Example 1, it can be seen that the dust holding capacity of the filter material without multi-roller stretching is reduced, and the dust holding life per use is also reduced. After analyzing the above results, it was found that solid particles easily accumulate in the puncture holes during filtration, causing the material surface to preferentially form a dirt covering layer quickly around the puncture holes, resulting in the material surface failing first, and thus the filter material's life and dust holding capacity are significantly reduced.

[0080] Comparative Example 5 did not use a core-sheath structure but instead used a blend of PP and PE resins. However, after the blended resin material was punctured and heated, the fibers underwent severe deformation, resulting in a significant reduction in the overall structure of the material. The fibers were extremely prone to breakage, and the material had low peel strength, making it unsuitable for application.

[0081] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method of making a multilayered, spaced, continuously graded structure liquid filtration material, characterized by, Includes the following steps: Step 1: A dust-binding layer is prepared using a spunbond process. The spunbond process includes: converting PP resin into molten PP resin, then converting PE resin into molten PE resin, extruding the molten PP resin and molten PE resin through a spinneret for melt spinning, and then cooling the melt-spun fibers to form filaments. The filaments are then formed into a dust-binding layer on a web forming machine using a swinging device. The fibers of the dust-binding layer have a core-sheath structure, with the core layer being PP resin and the sheath layer being PE resin. A skeleton layer is then prepared on the surface of the dust-binding layer using a meltblown process. The meltblown process includes: converting a second resin into molten second resin, injecting the molten second resin into a meltblown device, and then meltblowing the skeleton layer on the surface of the dust-binding layer. Step 2: The skeleton layer and dust-collecting layer are cold-pressed to form filter monomers; Step 3: Several filter monomers are sequentially cross-laid, punctured and heated, and stretched by multiple rollers to form a multi-layered, continuously gradient structure liquid filter material; the cross-laid method is that adjacent filter monomers are stacked at an alternating angle of 30~60°; the tensile strength of the multi-roll stretching is 3~8 N / m.

2. The preparation method according to claim 1, characterized in that, In the spunbond process, the mass fraction of PP resin is 65-75 parts, and the mass fraction of PE resin is 25-35 parts.

3. The preparation method according to claim 1, characterized in that, In the meltblown process: the second resin is PP resin with a melt index of 400~600 g / min.

4. The preparation method according to claim 1, characterized in that, The conditions for the meltblown process include: the temperature of the screw extrusion unit is 160~170 ℃.

5. The preparation method according to claim 1 or 4, characterized in that, The conditions for the meltblown process also include: meltblown die head temperature 160~170 ℃, hot air temperature 160~170 ℃, and air pressure 0.1~0.5 MPa.

6. The preparation method according to claim 1, characterized in that, The puncture is one or both of acupuncture and hydronephrosis.

7. The preparation method according to claim 1, characterized in that, The conditions for the puncture include: inserting the needle perpendicularly once with the material surface as the plane.

8. The preparation method according to claim 1, characterized in that, The multi-roller drafting includes circumferential drafting.

9. The preparation method according to claim 8, characterized in that, The circumferential drawing includes circumferential six-part drawing, circumferential eight-part drawing, and circumferential twelve-part drawing.

10. The preparation method according to claim 1, characterized in that, The baking temperature is 100~110℃.

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