Preparation method of multilayer liquid filtering framework material

Abstract

The invention relates to the technical field of filter materials, and discloses a preparation method of a multilayer liquid filter framework material, the multilayer liquid filter framework material in the method is prepared by needling, hot drying and compounding multilayer filter monomers, and each filter monomer is prepared by cold pressing and compounding a dust containing layer and a framework layer melt-blown on the dust containing layer. Fibers of the melt-blown layer are of a skin-core structure composed of a PE resin skin layer and a PP resin core layer, and during cold pressing treatment, the cold pressing temperature is controlled, so that the PE resin surface layer of the fibers of the dust containing layer is melted and is bonded and compounded with the framework layer; during needling and hot drying treatment, dust containing layer fibers of the filtering monomers can penetrate through the framework layer to enter the dust containing layers of the adjacent filtering monomers and form entanglement points, then the PE resin surface layer of the melt-blown layer is melted through hot drying, bonding is formed at the entanglement points, entanglement is reinforced, and the composite strength of the material is remarkably improved; according to the method, the internal space structure of the dust containing layer cannot be obviously changed, and the dust containing capacity of the dust containing layer cannot be obviously reduced.

Description

Technical Field

[0001] The invention relates to the technical field of filter materials, and in particular to a method for preparing a multi-layer liquid filter skeleton material. Background Art

[0002] The main filtering structure of the filter material is the filter membrane, but in some environments the filter medium contains a large amount of solid particles, which will affect the filtering efficiency of the filter membrane. Therefore, in order to reduce the impact of solid particles on the filter membrane, a dust holding layer is provided at the front end of the filter membrane in the prior art. The dust in the filter medium is intercepted by the dust holding layer, thereby improving the filtering efficiency of the filter membrane.

[0003] At present, the dust holding layer is made of polyester fiber that can form a three-dimensional layered structure, and its internal space can accommodate dust particles in the filter medium, such as a high-efficiency and low-resistance filtering structure disclosed in publication number CN215742350U. In this scheme, a skeleton layer, a nanofiber layer, a melt-blown layer, a dust holding layer and a protective layer are arranged in sequence from the outside to the inside; the dust holding capacity of the dust holding layer is related to its internal porosity. The smaller the wire diameter of the polyester fiber per unit volume, the larger the dust holding capacity of the dust holding layer. However, if the fiber wire diameter is too small, the stiffness of the dust holding layer will be reduced. The dust holding layer with low stiffness will deform under pressure during use, and the dust holding efficiency will be significantly reduced. Therefore, when increasing the dust holding capacity by changing the fiber wire diameter, it is necessary to ensure the stiffness of the dust holding layer. At present, the method for increasing the stiffness of the dust holding layer is mainly to set a skeleton material on the dust holding layer. The dust holding layer in the existing technology is usually a single-layer structure. Since the single-layer structure needs to maintain a certain stiffness, the structure of the dust holding layer is relatively tight, so the dust holding capacity of the dust holding layer has certain limitations.

[0004] At present, theoretically, the looser the structure of the dust holding layer, the greater its dust holding capacity. However, in actual application, the stiffness of the loosely structured dust holding layer is low and the loosely structured dust holding layer is thin. Therefore, it is necessary to strengthen the stiffness of the dust holding layer, and it is necessary to overlap multiple loosely structured dust holding layers to obtain a dust holding layer thickness that meets the application. However, the current process for compounding multi-layer dust holding layers is mainly point welding and adhesives. After point welding and adhesive compounding, the internal spatial structure of the dust holding layer will be destroyed, resulting in the dust holding layer being unable to significantly exert its advantage of large dust holding capacity. In addition, when the multi-layer dust holding layer is compounded, the skeleton layers and composite interfaces on the multiple dust holding layers occupy a large space, resulting in the multi-layer dust holding material. Compared with a single-layer dust holding layer of the same volume, the actual dust holding space is not significantly increased, and the cost is higher, and the actual application value is lower. Summary of the invention

[0005] The present invention aims to solve the problem in the prior art that the dust holding capacity of a loose multi-layer dust holding layer is significantly reduced after point-of-use welding and adhesive compounding. The present invention provides a method for preparing a multi-layer liquid filter skeleton material. The multi-layer liquid filter skeleton material in the method is made of multi-layer filter monomers through needle punching and hot baking compounding. The filter monomer is composed of a dust holding layer and a skeleton layer melt-blown on the dust holding layer through cold pressing compounding. The method will not significantly change the internal fiber structure of the filter skeleton material, and will not significantly reduce the dust holding capacity of the filter skeleton material. The dust holding capacity of the liquid filter skeleton material prepared by the method is significantly higher than that of the filter skeleton material compounded with point-of-use welding and adhesive.

[0006] The specific technical scheme of the present invention is: Compared with the prior art, this application has the following technical effects: A method for preparing a multilayer liquid filtration skeleton material comprises the following steps: The first resin is spunbonded to form a dust-holding layer, the second resin is melt-blown and arranged on the surface of the dust-holding layer to form a skeleton layer, the skeleton layer and the dust-holding layer arranged on the surface of the dust-holding layer are cold-pressed to form a filter monomer, and a plurality of filter monomers are needle-punched and hot-baked to form a multi-layer liquid filter skeleton material, wherein the gram weight of the dust-holding layer is 5 to 15 g / cm 2 The fiber diameter of the dust-holding layer is 2-20 μm, and the fiber of the dust-holding layer is a PP resin core layer and a PE resin skin layer; The cold pressing treatment conditions include: point pressing, a pressing point area of ​​3 to 20%, and a cold pressing temperature of 100 to 110°C.

[0007] The present invention provides a method for preparing a multi-layer liquid filtration skeleton material. The multi-layer liquid filtration skeleton material in the method is made by compounding multiple layers of filtration monomers through needle-punching and hot-drying. The needle-punching treatment enables the fibers of one layer to be pierced into another layer and entangled with the fibers of another layer under the action of the needle, so that entanglement anchor points are formed between the layers, thereby completing the compounding of the multiple layers of filtration monomers.

[0008] The filter monomer of the present invention is composed of a loose dust holding layer made by a spunbond method and a skeleton layer melt-blown on the surface of the dust holding layer and processed by cold pressing. The skeleton layer improves the stiffness of the dust holding layer and maintains the three-dimensional structure of the dust holding layer. The fiber diameter of the dust holding layer is 2-20 μm and the gram weight is 5-15 g / cm 2The structure is loose and the dust holding capacity is high. The fiber of the dust holding layer is a skin-core structure composed of PP resin and PE resin. PP resin is the core layer and PE resin is the skin layer. The fiber of the dust holding layer plays an important role in the cold pressing treatment and needle punching hot baking treatment, and can improve the composite strength of the material. The melting point of PP resin is usually higher than 160℃, and the melting point of PE resin is between 110 and 140℃. Therefore, when the fiber with PP resin as the core layer and PE resin as the skin layer is heated, the PE resin skin layer of the fiber can be melted by controlling the heating temperature, while the core layer of PP resin will not melt. In the cold pressing stage, the cold pressing temperature is controlled to melt the PE skin layer and bond with the skeleton layer under pressure, so that the skeleton layer and the dust holding layer are compounded. The cold pressing direction is from the skeleton layer to the dust holding layer, and after heating, the heat is transferred from the skeleton layer to the surface of the dust holding layer. Only the fibers on the surface of the dust holding layer are melted and bonded to the skeleton layer. In this way, the spatial structure inside the skeleton layer and the dust holding layer will not change significantly, ensuring that the dust holding capacity of the dust holding layer will not change significantly. In the needling hot drying stage, due to the extremely thin skeleton layer set on the surface of the dust holding layer during needling, the gram weight of the layer is estimated to be only 2-5g / cm 2 Therefore, after the multi-layer filter monomers are stacked, the dust holding layer fibers of the adjacent filter monomers will be directly pierced into the dust holding layer of the adjacent filter monomers under the action of acupuncture and form entanglement. At this time, the PE skin fiber is melted by heat baking, so that bonding is carried out at the entanglement points, and the entanglement points formed by reinforcement are strengthened, so that the composite strength of the multi-layer filter monomers is significantly improved. In addition, the internal structure of the dust holding layer after composite does not change significantly, and the dust holding capacity of the dust holding layer does not decrease significantly. Compared with the adhesive and point welding composite method, the dust holding capacity is significantly improved, and compared with the single acupuncture process, the bonding strength is significantly improved.

[0009] Preferably, the spunbond process comprises the following steps: injecting the first resin into a melt mixing device to form a molten resin, and injecting the molten resin into a spinning device for spinning, drawing and web forming to form a dust holding layer.

[0010] Preferably, the first resin comprises 65 to 75 parts by mass of PP resin and 25 to 35 parts by mass of PE resin.

[0011] Preferably, the skeleton layer has a gram weight of 2 to 5 g / cm 2 .

[0012] Preferably, the melt-blowing process comprises the following steps: injecting the second resin into a screw extruder to form a molten second resin, and injecting the molten second resin into a melt-blowing device for spinning to form a skeleton layer.

[0013] Preferably, the second resin is PP resin, and the melt index of the second resin is 400-600 g / min.

[0014] Preferably, the needling method includes: using the material surface as a plane, first inserting the needle vertically once and then inserting the needle at an angle. The inclined needling method can form lateral entanglement anchor points on the fibers, and lateral anchor point connections are formed between the fibers, which can increase the strength of the needling composite.

[0015] Preferably, the conditions for the heat drying include: a temperature of 100-110°C.

[0016] Preferably, the acupuncture speed is 30-50 m / min.

[0017] Preferably, the mass ratio of the PP resin core layer to the PE resin skin layer is 5 to 7:1.

[0018] Compared with the prior art, this application has the following technical effects: The invention provides a preparation method of a multi-layer liquid filter skeleton material. The multi-layer liquid filter skeleton material in the method is prepared by compounding multi-layer filter monomers through needle punching and hot baking. The filter monomer is composed of a dust holding layer and a skeleton layer melt-blown on the dust holding layer through cold pressing. The fiber of the melt-blown layer is a skin-core structure composed of a PE resin skin layer and a PP resin core layer. During the cold pressing treatment, the cold pressing temperature is controlled to melt the PE resin surface layer of the dust holding layer fiber and bond with the skeleton layer. During the needle punching and hot baking treatment, the dust holding layer fiber of the filter monomer can penetrate the skeleton layer into the dust holding layer of the filter monomer adjacent thereto and form entanglement points. Then, the PE resin surface layer of the melt-blown layer is melted by hot baking and bonded and entangled at the entanglement points are formed, so that the composite strength of the material is significantly increased. The method does not significantly change the internal space structure of the dust holding layer, and does not significantly reduce the dust holding capacity of the dust holding layer. Compared with a bonding agent and point welding composite method, the dust holding capacity is significantly improved, and compared with a single needle punching process, the bonding firmness is significantly improved. DETAILED DESCRIPTION

[0019] The present invention will be further described below in conjunction with the embodiments.

[0020] Embodiment 1: A method for preparing a multilayer liquid filtration skeleton material, characterized in that it comprises the following steps: Step 1: Inject 70 parts of PP resin into a screw extruder to make molten PP resin at an extrusion temperature of 165°C, inject 30 parts of PE resin into a screw extruder to make molten PE resin at an extrusion temperature of 120°C, inject the molten PP resin and the molten PE resin into the spinning box respectively, and then extrude the melt through the spinneret for melt spinning. The melt spinning enters the air and is blown, stretched and cooled to form filaments. The filaments are formed into a dust-holding layer on a web-forming machine through a swing device. The skin layer of the dust-holding layer fiber is PE resin and the core layer is PP resin. The mass ratio of the skin layer to the core layer is 1:6, the fiber diameter is 2-20μm, and the weight of the dust-holding layer is 10g / cm 2 ; Step 2: inject the second resin (PP resin with a melt index of 400-600 g / min) into a screw extruder to form a molten second resin, the extrusion temperature is 165°C, the molten second resin is injected into the melt-blown device and the dust-holding layer surface melt-blown skeleton layer obtained in step 1 is made into a preform, the melt-blown die temperature is 165°C, the hot air temperature is 165°C, and the skeleton layer has a gram weight of 3 g / cm 2 ; Step 3: cold-pressing the preform obtained in step 2 to form a filter unit, the temperature of the cold-pressing roller is 105° C., the cold-pressing direction is from the skeleton layer to the dust-holding layer, the cold-pressing method is point pressing, the pressing point area is 8%, and the roller speed is 4 m / min. The first resin is spunbonded to form a dust-holding layer, and the second resin is melt-blown to form a skeleton layer on the surface of the dust-holding layer. The skeleton layer and the dust-holding layer on the surface of the dust-holding layer are cold-pressed to form a filter unit; Step 4: Stack 5 layers of the filter monomers prepared in step 3, and then perform heat needling after stacking. The needling method is to insert the needle vertically once with the material surface as the plane, and insert the needle from top to bottom and from bottom to top once each when vertically inserting the needle. Then, with the material surface as the plane, the needling angle is 45°, and the needle is inserted from top to bottom and from bottom to top once each. After the needling is completed, place it in a heat drying device at 105°C, heat bake for 5 minutes, and then cool it to form a multi-layer liquid filtration skeleton material.

[0021] Embodiment 2: A method for preparing a multilayer liquid filtration skeleton material, characterized in that it comprises the following steps: Step 1: Inject 65 parts of PP resin into a screw extruder to make a molten PP resin at an extrusion temperature of 165°C, inject 35 parts of PE resin into a screw extruder to make a molten PE resin at an extrusion temperature of 120°C, inject the molten PP resin and the molten PE resin into the spinning box respectively, and then extrude the melt through the spinneret for melt spinning. The melt spinning enters the air and is blown, stretched and cooled to form filaments. The filaments are formed into a dust-holding layer on a web-forming machine through a swing device. The skin layer of the dust-holding layer fiber is PE resin and the core layer is PP resin. The mass ratio of the skin layer to the core layer is 1:5, the fiber diameter is 2-20μm, and the gram weight of the dust-holding layer is 5g / cm2 ; Step 2: inject the second resin (PP resin with a melt index of 400-600 g / min) into a screw extruder to form a molten second resin, the extrusion temperature is 165°C, the molten second resin is injected into the melt-blown device and the dust-holding layer surface melt-blown skeleton layer obtained in step 1 is made into a preform, the melt-blown die temperature is 165°C, the hot air temperature is 165°C, and the skeleton layer has a gram weight of 2 g / cm 2 ; Step 3: cold-press the preform obtained in step 2 to form a filter unit, the temperature of the cold-pressing roller is 100°C, the cold-pressing direction is from the skeleton layer to the dust-holding layer, the cold-pressing method is point pressing, the pressure point area is 3%, and the roller speed is 3m / min. The first resin is spunbonded to form a dust-holding layer, and the second resin is melt-blown to form a skeleton layer on the surface of the dust-holding layer. The skeleton layer and the dust-holding layer on the surface of the dust-holding layer are cold-pressed to form a filter unit; Step 4: Stack 5 layers of the filter monomers prepared in step 3, and then perform heat needling after stacking. The needling method is to insert the needle vertically once with the material surface as the plane, and insert the needle from top to bottom and from bottom to top once each when vertically inserting the needle. Then, with the material surface as the plane, the needling angle is 45°, and the needle is inserted from top to bottom and from bottom to top once each. After the needling is completed, place it in a heat drying device at 100°C, heat bake for 5 minutes, and then cool it to form a multi-layer liquid filtration skeleton material.

[0022] Embodiment 3: A method for preparing a multilayer liquid filtration skeleton material, characterized in that it comprises the following steps: Step 1: Inject 75 parts of PP resin into a screw extruder to make molten PP resin at an extrusion temperature of 165°C, inject 25 parts of PE resin into a screw extruder to make molten PE resin at an extrusion temperature of 120°C, inject the molten PP resin and the molten PE resin into the spinning box respectively, and then extrude the melt through the spinneret for melt spinning. The melt spinning enters the air and is blown, stretched, and cooled to form filaments. The filaments are formed into a dust-holding layer on a web-forming machine through a swing device. The skin layer of the dust-holding layer fiber is PE resin and the core layer is PP resin. The mass ratio of the skin layer to the core layer is 1:7, the fiber diameter is 2-20μm, and the gram weight of the dust-holding layer is 15g / cm 2 ; Step 2: Inject the second resin (PP resin with a melt index of 400-600 g / min) into a screw extruder to form a molten second resin, the extrusion temperature is 165°C, the molten second resin is injected into the melt-blown device and the dust-holding layer surface melt-blown skeleton layer obtained in step 1 is made into a preform, the melt-blown die temperature is 165°C, the hot air temperature is 165°C, and the skeleton layer has a gram weight of 5 g / cm 2 ; Step 3: cold-pressing the preform obtained in step 2 to form a filter unit, the temperature of the cold-pressing roller is 110° C., the cold-pressing direction is from the skeleton layer to the dust-holding layer, the cold-pressing method is point pressing, the pressure point area is 20%, and the roller speed is 5 m / min. The first resin is spunbonded to form a dust-holding layer, and the second resin is melt-blown to form a skeleton layer on the surface of the dust-holding layer. The skeleton layer and the dust-holding layer on the surface of the dust-holding layer are cold-pressed to form a filter unit; Step 4: Stack 5 layers of the filter monomers prepared in step 3, and then perform heat needling after stacking. The needling method is to insert the needle vertically once with the material surface as the plane, and insert the needle from top to bottom and from bottom to top once each when vertically inserting the needle. Then, with the material surface as the plane, the needling angle is 45°, and the needle is inserted from top to bottom and from bottom to top once each. After the needling is completed, place it in a heat drying device at 110°C, heat bake for 5 minutes, and then cool it to form a multi-layer liquid filtration skeleton material.

[0023] Embodiment 4: A method for preparing a multilayer liquid filtration skeleton material, characterized in that it comprises the following steps: Step 1: Inject 70 parts of PP resin into a screw extruder to make molten PP resin at an extrusion temperature of 165°C, inject 30 parts of PE resin into a screw extruder to make molten PE resin at an extrusion temperature of 120°C, inject the molten PP resin and the molten PE resin into the spinning box respectively, and then extrude the melt through the spinneret for melt spinning. The melt spinning enters the air and is blown, stretched and cooled to form filaments. The filaments are formed into a dust-holding layer on a web-forming machine through a swinging device. The skin layer of the dust-holding layer fiber is PE resin and the core layer is PP resin. The mass ratio of the skin layer to the core layer is 1:6, the fiber diameter is 2-20μm, and the gram weight of the dust-holding layer is 8g / cm 2 ; Step 2: inject the second resin (PP resin with a melt index of 400-600 g / min) into a screw extruder to form a molten second resin, the extrusion temperature is 165°C, the molten second resin is injected into the melt-blown device and the dust-holding layer surface melt-blown skeleton layer obtained in step 1 is made into a preform, the melt-blown die temperature is 165°C, the hot air temperature is 165°C, and the skeleton layer has a gram weight of 3 g / cm 2 Step 3: cold press the preform obtained in step 2 to form a filter unit, the temperature of the cold pressing roller is 110°C, the cold pressing direction is from the skeleton layer to the dust holding layer, the cold pressing method is point pressing, the pressing point area is 5%, and the roller speed is 4m / min; The first resin is spunbonded to form a dust holding layer, the second resin is meltblown to form a skeleton layer on the surface of the dust holding layer, the skeleton layer and the dust holding layer on the surface of the dust holding layer are cold pressed to form a filter unit, Step 4: Stack 5 layers of the filter monomers prepared in step 3, and then perform heat needling after stacking. The needling method is to insert the needle vertically once with the material surface as the plane, and insert the needle from top to bottom and from bottom to top once each when vertically inserting the needle. Then, with the material surface as the plane, the needling is inclined at an angle of 45° from top to bottom and from bottom to top once each. After the needling is completed, place it in a heat drying device at 80-100°C, heat bake for 5 minutes, and then cool it to form a multi-layer liquid filtration skeleton material.

[0024] Embodiment 5: A method for preparing a multilayer liquid filtration skeleton material, characterized in that it comprises the following steps: Step 1: Inject 70 parts of PP resin into a screw extruder to make molten PP resin at an extrusion temperature of 165°C, inject 30 parts of PE resin into a screw extruder to make molten PE resin at an extrusion temperature of 120°C, inject the molten PP resin and the molten PE resin into the spinning box respectively, and then extrude the melt through the spinneret for melt spinning. The melt spinning enters the air and is blown, stretched and cooled to form filaments. The filaments are formed into a dust-holding layer on a web-forming machine through a swing device. The skin layer of the dust-holding layer fiber is PE resin and the core layer is PP resin. The mass ratio of the skin layer to the core layer is 1:6, the fiber diameter is 2-20μm, and the weight of the dust-holding layer is 10g / cm 2 ; Step 2: inject the second resin (PP resin with a melt index of 400-600 g / min) into a screw extruder to form a molten second resin, the extrusion temperature is 165°C, the molten second resin is injected into the melt-blown device and the dust-holding layer surface melt-blown skeleton layer obtained in step 1 is made into a preform, the melt-blown die temperature is 165°C, the hot air temperature is 165°C, and the skeleton layer has a gram weight of 4 g / cm 2 ; Step 3: cold-press the preform obtained in step 2 to form a filter unit, the temperature of the cold-pressing roller is 110°C, the cold-pressing direction is from the skeleton layer to the dust-holding layer, the cold-pressing method is point pressing, the pressure point area is 10%, and the roller speed is 5 m / min. The first resin is spunbonded to form a dust-holding layer, and the second resin is melt-blown to form a skeleton layer on the surface of the dust-holding layer. The skeleton layer and the dust-holding layer on the surface of the dust-holding layer are cold-pressed to form a filter unit; Step 4: Stack 5 layers of the filter monomers prepared in step 3, and then perform heat needling after stacking. The needling method is to insert the needle vertically once with the material surface as the plane, and insert the needle from top to bottom and from bottom to top once each when vertically inserting the needle. Then, with the material surface as the plane, the needling angle is 45°, and the needle is inserted from top to bottom and from bottom to top once each. After the needling is completed, place it in a heat drying device at 110°C, heat bake for 5 minutes, and then cool it to form a multi-layer liquid filtration skeleton material.

[0025] Embodiment 6: A method for preparing a multilayer liquid filtration skeleton material, characterized in that it comprises the following steps: Step 1: Inject 70 parts of PP resin into a screw extruder to make molten PP resin at an extrusion temperature of 165°C, inject 30 parts of PE resin into a screw extruder to make molten PE resin at an extrusion temperature of 120°C, inject the molten PP resin and the molten PE resin into the spinning box respectively, and then extrude the melt through the spinneret for melt spinning. The melt spinning enters the air and is blown, stretched and cooled to form filaments. The filaments are formed into a dust-holding layer on a web-forming machine through a swing device. The skin layer of the dust-holding layer fiber is PE resin and the core layer is PP resin. The mass ratio of the skin layer to the core layer is 1:6, the fiber diameter is 2-20μm, and the gram weight of the dust-holding layer is 12g / cm 2 ; Step 2: Inject the second resin (PP resin with a melt index of 400-600 g / min) into a screw extruder to form a molten second resin, the extrusion temperature is 165°C, the molten second resin is injected into the melt-blown device and the dust-holding layer surface melt-blown skeleton layer obtained in step 1 is made into a preform, the melt-blown die temperature is 165°C, the hot air temperature is 165°C, and the skeleton layer has a gram weight of 5 g / cm 2 , Step 3: cold-pressing the preform obtained in step 2 to form a filter unit, the temperature of the cold-pressing roller is 110° C., the cold-pressing direction is from the skeleton layer to the dust-holding layer, the cold-pressing method is point pressing, the pressing point area is 15%, and the roller speed is 4 m / min. The first resin is spunbonded to form a dust-holding layer, and the second resin is melt-blown to form a skeleton layer on the surface of the dust-holding layer. The skeleton layer and the dust-holding layer on the surface of the dust-holding layer are cold-pressed to form a filter unit; Step 4: Stack 5 layers of the filter monomers prepared in step 3, and then perform heat needling after stacking. The needling method is to insert the needle vertically once with the material surface as the plane, and insert the needle from top to bottom and from bottom to top once each when vertically inserting the needle. Then, with the material surface as the plane, the needling angle is 45°, and the needle is inserted from top to bottom and from bottom to top once each. After the needling is completed, place it in a heat drying device at 110°C, heat bake for 5 minutes, and then cool it to form a multi-layer liquid filtration skeleton material.

[0026] Comparative Example 1: Compared with Example 1, in Comparative Example 1, an infrared band hot pressing roller is used to compound the multi-layer filter monomer, and the other conditions are the same as those in Example 1.

[0028] Comparative Example 2: Compared with Example 1, in Comparative Example 2, polyolefin hot melt adhesive was used to compound the multi-layer filter monomer, and the other conditions were the same as those in Example 1.

[0029] Comparative Example 3: Compared with Example 1, in Comparative Example 3, the skeleton layer and the dust holding layer are compounded using an infrared band hot pressing roller, and the other conditions are the same as those in Example 1.

[0030] Comparative Example 4: Compared with Example 1, in Comparative Example 4, only needle-punching treatment was used without heat drying to compound the multi-layer filter monomer, and the other conditions were the same as those in Example 1.

[0031] Comparative Example 5: Compared with Example 1, the meltblown layer fiber in Comparative Example 5 is made of a blended resin of PP resin and PE resin, and the other conditions are the same as those of Example 1.

[0032] Comparative Example 6: Compared with Example 1, the cold pressing temperature of Comparative Example 6 is 160°C, and the other conditions are the same as those of Example 1.

[0033] Comparative Example 7: Compared with Example 1, the cold pressing temperature of Comparative Example 7 is 50° C., and the other conditions are the same as those of Example 1.

[0034] Comparative Example 8: Compared with Example 1, the needling method in Comparative Example 8 is only vertical needling with the material surface as the plane, and no inclined needling is performed. The other conditions are the same as those in Example 1.

[0035] Test example: The peel strength of the filter monomers prepared in Examples 1 to 6 and Comparative Examples 1 to 8 and the peel strength of the multilayer liquid filter skeleton material and the dust holding capacity of the multilayer liquid filter skeleton material were tested; The stiffness test method refers to "JIS L1096 Gurley fabric stiffness method for determining the stiffness of non-woven fabrics in the MD direction", the test material size is 89mm*25mm, a suitable range weight is selected, the swing amplitude of the equipment test rod is used, and the corresponding stiffness size is displayed on the display screen, and samples are taken at any 5 places in the non-woven fabric of the present invention and tested to obtain the average value; The dust holding capacity test method refers to "ISO 16889:2008 Hydraulic transmission filters. Evaluation of filter performance using multiple pass method"; The peel strength test method refers to GB / T8808-1988 T-type peel strength test method for soft composite plastics. The instrument used for the peel test is XLW (PC) intelligent electronic tensile testing machine. The test results are shown in Table 1; Table 1 Test results As shown in Table 1, the peel strength of the multi-layer liquid filtration skeleton material prepared in Examples 1 to 6 is 8.1 to 8.7 N / M 2, stiffness is 105~110mg, dust holding capacity is 345~400g / m 2 , with high dust holding capacity and bonding strength.

[0036] In comparative example 1, an infrared band hot pressing roller was used to perform point welding and lamination of the multi-layer liquid filter skeleton material. The peel strength of the multi-layer liquid filter skeleton material in comparative example 1 was 8.9 N / M. 2 , dust holding capacity is 285g / m 2 Compared with Example 1, the composite strength of the material in Comparative Example 1 is not significantly different, but the dust holding capacity is significantly reduced; in Comparative Example 2, polyolefin hot melt adhesive is used as an adhesive to composite the multi-layer liquid filtration skeleton material, and the peel strength of the multi-layer liquid filtration skeleton material in Comparative Example 2 is 8.4N / M 2 , dust holding capacity 305g / m 2 Compared with Example 1, there is no significant difference in the composite strength of the material in Comparative Example 2, but the dust holding capacity is significantly reduced; from the results of Comparative Examples 1 to 2 and Example 1, it can be seen that the dust holding capacity of the multilayer liquid filtration skeleton material prepared by the method provided by the present application is significantly improved compared with the point welding and adhesive composite methods. In addition, by testing the dust holding capacity of the original multilayer liquid filtration skeleton material that has not been composited, it is found that the dust holding capacity of the multilayer liquid filtration skeleton material that has not been composited is 426g / m 2 The multi-layer liquid filtration skeleton material after compounding in Example 1 is not significantly reduced compared with the multi-layer liquid filtration skeleton material without compounding, which indicates that the method provided in the present application will not significantly change the internal structural space structure of the multi-layer liquid filtration skeleton, and will not significantly reduce the dust holding capacity of the dust holding layer.

[0037] In comparative example 3, an infrared band hot pressing roller was used to compound the filter monomer, and the peel strength of the filter monomer in comparative example 3 was increased to 8.2N / M 2 However, the dust holding capacity of the final multi-layer liquid filtration skeleton material is only 321g / m 2 Compared with Example 1, although the peel strength of the filter monomer in Comparative Example 3 is significantly improved, the dust holding capacity of the prepared multi-layer liquid filter skeleton material is significantly reduced. It can be seen from the results of Comparative Example 3 and Example 1 that the composite method of the filter monomer also has an important influence on the dust holding capacity of the multi-layer filter material. The point welding method will cause the internal space of the filter monomer to change significantly, thereby causing the dust holding capacity to be significantly reduced. The cold pressing treatment of the present application will not change the internal space structure of the filter monomer, and will not significantly reduce the dust holding capacity of the filter monomer. In addition, the filter monomer does not require a high composite strength, and it only needs to ensure that the skeleton layer and the dust holding layer can be effectively composited.

[0038] Comparative Example 4 only uses needle punching without heat drying. The peel strength of the multilayer liquid filtration skeleton material prepared in Comparative Example 4 is 7.2 N / M2 Compared with Example 1, the composite strength of the multi-layer liquid filtration skeleton material obtained in Comparative Example 4 using only needle punching without heat baking will be reduced. The bonding effect formed at the entanglement points of the PE resin cortex after heat baking can further improve the composite strength of the needle punching entanglement points, making the bonding strength of the multi-layer liquid filtration skeleton material equivalent to the bonding strength after welding.

[0039] The dust holding layer fiber not used in Comparative Example 5 does not adopt a skin-core structure but is made of PP resin and PE resin blended and spunbonded. The peel strength of the filter monomer of Comparative Example 5 is 4.5N / M 2 The peel strength of the multi-layer liquid filtration skeleton material is only 5.8N / M 2 Compared with Example 1, the peel strength of the multi-layer liquid filtration skeleton material in Comparative Example 5 is significantly reduced. In actual operation, it is found that during the cold pressing and hot baking process of the blended PP / PE resin, the dust-holding layer fibers will partially melt and deform. The strength of the melted fiber filaments will be significantly reduced, causing the multi-layer filtration skeleton material to be easily damaged.

[0040] The temperature of the cold pressing treatment is investigated in Comparative Examples 6 and 7. When the temperature of Comparative Example 6 is too high, the PP resin core layer will also melt, and the dust holding layer and the skeleton layer will be welded into blocks during cold pressing, thereby significantly reducing the dust holding capacity. When the temperature of Comparative Example 7 is too low, cold pressing will not work.

[0041] In Comparative Example 8, the needle punching method was explored. In Comparative Example 8, the needle punching was not performed in a direction inclined to the material surface. The peel strength of the multilayer liquid filtration skeleton material in Comparative Example 8 was only 8.4 N / M. 2 Compared with Example 1, the peel strength of the material is reduced. The results of Comparative Example 8 and Example 1 show that adding a needle punching method in a direction inclined to the material surface can further improve the composite strength of the material.

[0042] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a multilayer liquid filtration skeleton material, characterized in that: The following steps are involved: The first resin is spunbonded to form a dust-holding layer, the second resin is melt-blown and arranged on the surface of the dust-holding layer to form a skeleton layer, the skeleton layer and the dust-holding layer arranged on the surface of the dust-holding layer are cold-pressed to form filter monomers, and a plurality of filter monomers are needle-punched and hot-baked to form a multi-layer liquid filter skeleton material. The dust holding layer has a gram weight of 5 to 15 g / cm 2 The fiber diameter of the dust holding layer is 2-20 μm, and the fiber of the dust holding layer is a PP resin core layer and a PE resin skin layer; The cold pressing treatment conditions include: point pressing, a pressing point area of ​​3-20%, and a cold pressing temperature of 100-110°C.

2. The method for preparing a multilayer liquid filtration skeleton material according to claim 1, characterized in that: The spunbond process comprises the following steps: injecting a first resin into a melt mixing device to form a molten first resin, and injecting the molten first resin into a spinning device to perform spinning, drawing and web forming to form a dust holding layer.

3. The method for preparing a multilayer liquid filtration skeleton material according to claim 1 or 2, characterized in that: The first resin comprises 65-75 parts of PP resin and 25-35 parts of PE resin by mass.

4. The method for preparing a multilayer liquid filtration skeleton material according to claim 1, characterized in that: The skeleton layer has a gram weight of 2-5 g / cm 2 .

5. The method for preparing a multilayer liquid filtration skeleton material according to claim 1, characterized in that: The melt-blowing process comprises the following steps: injecting the second resin into a screw extruder to form a molten second resin, and injecting the molten second resin into a melt-blowing device for spinning to form a skeleton layer.

6. The method for preparing a multilayer liquid filtration skeleton material according to claim 1 or 5, characterized in that: The second resin is PP resin, and the melt index of the second resin is 400-600 g / min.

7. The method for preparing a multilayer liquid filtration skeleton material according to claim 1, characterized in that: The acupuncture method includes: taking the surface of the material as a plane, first inserting the needle vertically once and then inserting the needle obliquely once.

8. The method for preparing a multi-layer liquid filtration skeleton material according to claim 1, characterized in that: The conditions for the heat drying include: a temperature of 100-110°C.

9. The method for preparing a multi-layer liquid filtration skeleton material according to claim 7, characterized in that: The acupuncture speed is 30-50 m / min.

10. The method for preparing a multi-layer liquid filtration skeleton material according to claim 1, characterized in that: The mass ratio of PP resin core layer and PE resin skin layer is 5~7:1.

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