Melt-blown heat-shrinkable fiber paper and method for producing the same

Abstract

The application discloses a melt-blown heat-shrinkable fiber paper and a preparation method thereof. The method is used for preparing superfine fiber heat-shrinkable material by adopting a melt-blown technology. The material has fine fibers, and has the filtering and low-resistance performance which conventional fibers do not have. Meanwhile, the material has the strength and toughness which ordinary melt-blown fibers do not have, and is not easy to generate fluff like ordinary polypropylene melt-blown fibers. Through the research on different raw materials and production processes, heat-shrinkable materials with different styles are prepared. The materials can be made into filtering, packaging and connecting materials through different post-processing processes. In the product application process, the materials do not need to be coated and compounded with other materials, have the environment-friendly and recyclable performance in the preparation process, and meet the development direction of circular low carbon.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of high-performance fiber materials and manufacturing technology, and relates to a preparation method of melt-blown heat-shrinkable fiber paper. BACKGROUND

[0002] The current heat-shrinking technology is mainly applied to heat-shrinkable film, heat-shrinkable tube, heat-shrinkable tape and heat-shrinkable fiber leather base cloth and the like products. The heat-shrinkable film is mainly used in product packaging and the like fields due to its good transparency and adhesion; the heat-shrinkable tube and the heat-shrinkable tape are mainly used for connection, insulation or product protection and the like; the leather base cloth product is mainly used for making imitation leather products by using the texture and waterproof and breathable performance of the superfine high-shrinkage fiber. The existing filter material is formed by fiber dispersion, adhesion enhancement and compounding and the like processes to form a filter product with certain filtering efficiency and low resistance. Part of the fiber is compounded by needling and weaving and the like methods, the fiber diameter is large, and the filtering performance is poor; melt-blown cloth produced by using the melt-blown method is also used for filtering, the filtering performance is good, but there are also disadvantages such as low tensile strength and easy fuzzing; the ultra-fine filter uses a film or nanometer fiber with a fibril structure to make a more efficient filter product, but the product needs to be compounded with a supporting material with strength, which brings the problem of using an adhesive in the compounding process, increases the resistance of the product, and is not conducive to recycling. SUMMARY

[0003] The application provides a preparation method of melt-blown heat-shrinkable fiber paper, and specifically breaks the original multi-step preparation process of heat-shrinkable fiber products, directly uses a melt-blown method to produce superfine fiber webbing, and forms a fiber paper structure after heat treatment on the basis of improving the process of heat-shrinkable materials and melt-blown. The purpose is to make the fiber paper have high efficiency, low resistance, high barrier property of melt-blown fiber, higher strength, higher toughness and less fuzzing than ordinary melt-blown non-woven fabric, and can be used for preparing filter materials, packaging materials and connection materials.

[0004] The purpose of the application can be achieved by the following technical scheme.

[0005] The melt-blown heat-shrinkable fiber paper has a unit area mass of 75-85 g / m 2 , a particulate filtering efficiency of 78-82%, an air resistance of 28-32 Pa, a longitudinal tensile force of 38-42 N and a transverse tensile force of 40-50 N.

[0006] In the technical scheme of the application, the base material of the fiber paper is polyethylene terephthalate (PET) resin.

[0007] In the technical scheme of the application, the preparation method is to melt-blown high-shrinkage melt-blown base material to form a high-shrinkage superfine melt-blown cloth web, and the fiber paper product is made by heat setting.

[0008] In the technical scheme of the present application, the high-shrinkage melt-blown base material is polyethylene terephthalate (PET) resin.

[0009] In the technical scheme of the present application, the melt-blown method is that the melt-blown base material is dried and then sent into a screw extruder through a slicing conveying system, extruded and melted into a high-temperature melt, then the melt is metered by a metering pump and sent into a spinning system, extruded from a spinneret hole under the action of pressure, and the melt stream is drawn and attenuated under the clamping of high-temperature stretching air flow on both sides of the spinneret hole, so as to become superfine fibers; the obtained fibers are collected on a negative pressure screen curtain or a negative pressure perforated roller, and are bonded into a cloth by self-heating and negative pressure.

[0010] In the technical scheme of the present application, the heat setting machine is a tension heat setting machine, an oven heat setting machine or a hot air setting machine; the setting temperature is 50-130 DEG C, and the setting time is 3-150 seconds.

[0011] In the technical scheme of the present application, the melt flow index (MFI) of the high-shrinkage melt-blown base material melt is 150-800 g / 10 min, and the melting point range is 150-250 DEG C; the base material drying temperature is 110-130 DEG C, and the drying time is 4-8 hours.

[0012] In the technical scheme of the present application, the screw extruder is a single screw extruder, the screw length-diameter ratio is 22-30, and the screw temperature control is 200-290 DEG C; the melt temperature is 290-320 DEG C; the high-temperature air flow pressure is 0.07-0.12 MPa, and the air flow temperature is 290-320 DEG C.

[0013] In the technical scheme of the present application, the number of revolutions of the metering pump is 5-12 revolutions per minute, and the spinning system pressure is 0.5-3.5 MPa; the spinneret hole diameter is 0.2-0.4 mm, and the length-diameter ratio is 5-15:1.

[0014] In the technical scheme of the present application, the melt stream stretching area is 5-20 cm away from the spinneret hole; the negative pressure air volume is 1000-3500 m 3 / h; and the bonded cloth structure is a multi-layer disordered structure.

[0015] The mechanism of the present application is that the present application utilizes the relatively slow crystallization speed of PET polyester material, spins the high-shrinkage PET base material by using a melt-blown production mode, instantaneously stretches and attenuates the fiber under the stretching of high-temperature hot air flow, obtains a low-crystallization and high-orientation supermolecular structure, and bonds into a non-woven fabric under rapid cooling; when the non-woven fabric is heated at a certain temperature, the original macromolecules are disoriented, high shrinkage is triggered, and the entanglement force between fibers is enhanced, so as to improve the compactness and strength of the product; different style products can be made under the control of different external tension in the shrinkage process.

[0016] In the technical solution of the present application, the pressure is gauge pressure unless otherwise specified.

[0017] Advantages of the present application:

[0018] 1. The product has a fiber diameter ranging from 0.5 to 6 microns, which is 3 to 10 times thinner than the fiber spun by conventional spinning methods, and has a better air permeability and hydrophobicity due to the web structure. 2 When the flow rate is 32 L / min, the filtration efficiency of particles greater than 0.3 microns is 65 to 99%, and the product resistance is 10 to 100 Pa. At the same filtration efficiency, the product is thinner and has lower filtration resistance.

[0019] 2. When the product has a grammage of 40 to 60 g / m 2 The longitudinal breaking strength of the product is 40 to 60 N, and the transverse breaking strength is 40 to 60 N. The product has a strength that is 3 to 4 times higher than that of ordinary melt-blown products, solving the problem of low strength of melt-blown products. The product has high stiffness, good foldability, and no fluff, similar to paper, and better folding resistance than paper.

[0020] 3. The shrinkage temperature of the non-woven fabric is 50 to 90℃, the product has a transverse shrinkage rate (CD) of 35 to 55%, and a longitudinal shrinkage rate (MD) of 40 to 55%, and has good bidirectional shrinkage capability, which can be well attached to the surface of the product as a packaging shrinkage material. The product has a delicate texture and a soft feel, and after proper setting and curing, the surface is smooth and can be written and printed, and has good ornamental properties.

[0021] 4. The product does not need to be coated with glue or compounded with other materials during production, and has environmental protection and recyclable performance during preparation, which meets the development direction of low-carbon recycling. At the same time, the raw materials used can be localized and mass-produced, and the product cost is low, which has a competitive advantage. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The fiber electron microscope picture of the product of Example 1.

[0023] Figure 2 The product effect picture of Example 1.

[0024] Figure 3 The filter core product after winding and setting of Example 2. DETAILED DESCRIPTION

[0025] The present application will be further described below in conjunction with examples, but the scope of protection of the present application is not limited thereto:

[0026] Example 1

[0027] A preparation method of melt-blown heat-shrinkable fiber paper, comprising the following steps: drying melt-blown base polyethylene terephthalate (PET) and then feeding into a screw extruder through a slicing conveying system, extruding and melting into a high-temperature melt; then metering the melt through a metering pump and feeding into a spinning system, extruding from a spinneret hole under the action of pressure, and drawing and thinning the melt stream under the clamping of high-temperature stretching air flow on both sides of the spinneret hole to form superfine fibers; and collecting the obtained fibers on a negative pressure screen curtain or a negative pressure perforated roller, and bonding into a cloth by self-heating and negative pressure. The cloth screen is introduced into a five-roller heat setting machine for setting to form a fiber paper product.

[0028] The melt-blown base has a melt flow index (MFI) of 170 g / 10 min and a melting point of 195℃.

[0029] The drying temperature of the base is 120℃, and the drying time is 6 hours.

[0030] The screw length-diameter ratio is 30, and the screw temperature is controlled at 200-290℃.

[0031] The melt temperature is 290-310℃.

[0032] The rotation speed of the metering pump is 6 r / min, and the spinning system pressure is 3.2 MPa.

[0033] The spinneret hole diameter is 0.32 mm, and the length-diameter ratio is 10:1.

[0034] The high-temperature air flow pressure is 0.08 MPa, and the air flow temperature is 310℃.

[0035] The melt stream stretching area is 12 cm away from the spinneret hole.

[0036] The negative pressure perforated roller air volume is 3000 m 3 / h.

[0037] The five-roller setting machine has a tension setting temperature of 85℃ and a setting time of 15 seconds.

[0038] The product has a grammage of 80.6 g / m 2 , and the tested product resistance is 30 Pa and the filtration efficiency is 80%.

[0039] The product has high caliper, tight fibers, a longitudinal breaking strength of 40 N, and a transverse breaking strength of 45 N.

[0040] The product has good foldability and shape retention performance, and can be made into a pleated filter paper for use in filtration materials.

[0041] Comparative Example 1

[0042] A method for preparing a melt-blown non-woven fabric, comprising the following steps: feeding the prepared PP base material into a screw extruder through a chip conveying system, melting the PP base material through extrusion, and feeding the polymer melt with stable flow and pressure into a spinning system through a metering pump. The melt stream is drawn and attenuated under the action of the pressure and the drawing air flow on both sides of the spinneret to form ultra-fine fibers. The fibers are collected on a suction porous roller and are bonded into a fabric by self-heating and negative pressure.

[0043] The PP base material has a melt flow index (MFI) of 1500 g / 10 min and a melting point of 165℃.

[0044] The screw temperature is controlled at 180-265℃.

[0045] The melt temperature is 265-270℃.

[0046] The rotation speed of the metering pump is 10 rpm, and the spinning system pressure is 0.6 MPa.

[0047] The length-diameter ratio of the spinneret is 12:1.

[0048] The high-temperature air flow pressure is 0.07 MPa, and the air flow temperature is 275℃.

[0049] The melt stream drawing area is 19 cm away from the spinneret.

[0050] The air volume of the negative pressure porous roller is 2700 m 3 / h.

[0051] The product has a grammage of 79.6 g / m 2 , and the resistance is 29 Pa, and the filtration efficiency is 82%.

[0052] The product is relatively soft, the surface is slightly fuzzy, the longitudinal breaking strength is 14 N, and the transverse breaking strength is 16 N.

[0053] The product is not foldable, cannot maintain shape, and does not meet the product requirements.

[0054] Comparative Example 2

[0055] A method for preparing a melt-blown heat-shrinkable non-woven fabric, the early steps of which are basically the same as those of Example 1, except that the melt-blown product is directly subjected to performance testing without heat setting.

[0056] The product has a grammage of 79.8 g / m 2 , and the resistance is 28 Pa, and the filtration efficiency is 81%.

[0057] The product surface is slightly fuzzy, the longitudinal breaking strength is 18 N, and the transverse breaking strength is 21 N.

[0058] It has certain folding property, poor shape retention ability after folding, and no product condition.

[0059] Comparative Example 3

[0060] A melt-blown heat-shrinkable fiber paper preparation method, the early steps are basically the same as example 1, during heat setting, the tension setting temperature is 85℃, the setting time is 15 seconds, the difference is that each roller is controlled by single frequency conversion, and the speed difference is 0.

[0061] The product has a grammage of 79.8g / m 2 , and the test shows that the resistance is 35Pa, and the filtration efficiency is 80%.

[0062] The product has high stiffness, tight fibers, a longitudinal breaking strength of 32N, and a transverse breaking strength of 39N.

[0063] The product has good foldability and shape retention performance, the product breaking strength is general, and it does not have performance advantages.

[0064] Comparative Example 4

[0065] A melt-blown heat-shrinkable fiber paper preparation method, the early steps are basically the same as example 1, during heat setting, the tension setting temperature is 85℃, the setting time is 15 seconds, the difference is that each roller is controlled by single frequency conversion, and the speed difference is 3‰.

[0066] The product has a grammage of 79.8g / m 2 , and the test shows that the resistance is 28Pa, and the filtration efficiency is 76%.

[0067] The product has high stiffness, tight fibers, a longitudinal breaking strength of 30N, and a transverse breaking strength of 39N.

[0068] The product has good foldability and shape retention performance, the product breaking strength is general, and it does not have performance advantages.

[0069] Comparative Example 5

[0070] A melt-blown fiber paper preparation method, the early steps are basically the same as comparative example 1, the difference is that the product of comparative example 1 is subjected to subsequent heat setting treatment.

[0071] The tension setting temperature is 85℃, and the setting time is 15 seconds.

[0072] Each roller is controlled by single frequency conversion, and the speed difference is 0.

[0073] The product has a grammage of 79.6g / m 2 , and the test shows that the product resistance is 25Pa, and the filtration efficiency is 82%.

[0074] The product is relatively soft, the surface is fuzzy, the longitudinal breaking strength is 14N, and the transverse breaking strength is 15N.

[0075] No folding, no shape retention, no product conditions.

[0076] Comparative Example 6

[0077] A melt-blown heat-shrinkable fiber paper preparation method, the melt-blown base material is the same as in Example 1, and is subjected to a drying process, and the metering pump rotation speed is 6 revolutions per minute. The difference is that the production conditions are the production process parameters and equipment of the conventional PP melt-blown of Comparative Example 1.

[0078] The screw temperature is controlled at 180-265°C, and the melt temperature is 265-270°C; the jet hole length-diameter ratio is 12:1, the high-temperature airflow pressure is 0.07 MPa, and the airflow temperature is 275°C; the melt stream stretching area is 19 cm away from the jet hole; the negative pressure porous roller air volume is 2700 m 3 / h.

[0079] The production conditions are that the jet plate can spray out the fiber bundle, the die detection pressure is 5.9 MPa, which exceeds the normal use pressure of <3.5 MPa, and the melt-blown equipment production conditions are not met.

[0080] The sprayed fiber bundle is in the form of cotton wool and cannot be bonded together, and the forming conditions are not met.

[0081] The cotton wool fiber bundle is tested, and the diameter is >10 μm, and the fiber diameter is large.

[0082] Comparative Example 7

[0083] A melt-blown heat-shrinkable fiber paper preparation method, the melt-blown base material is the same as in Comparative Example 1, and the difference is that the production conditions are the production process parameters and equipment of the high-shrinkage melt-blown base material of Example 1.

[0084] The screw temperature is controlled at 200-290°C. The melt temperature is 290-310°C. The metering pump rotation speed is 6 revolutions per minute. The jet hole diameter is 0.32 mm, and the jet hole length-diameter ratio is 10:1. The high-temperature airflow pressure is 0.08 MPa, and the airflow temperature is 310°C. The melt stream stretching area is 12 cm away from the jet hole. The negative pressure porous roller air volume is 3000 m 3 / h.

[0085] The production conditions are that the melt at the jet plate sprays out fine broken fibers, cannot become a fiber bundle, and forms flying particles around the equipment under the action of hot air, and cannot be produced.

[0086] Table 1 Comparison of main indicators of different implementation methods

[0087]

[0088] Comparing Example 1 with Comparative Example 2, it can be seen that the filtration efficiency of Comparative Example 2 is slightly lower than that of Example 1, the air resistance difference is not large, but the tensile force and elongation indexes have very obvious advantages, which can solve the problem of low strength of ordinary melt-blown products.

[0089] Further comparing Example 1 with Comparative Example 2, it can be seen that the tensile force of the product after the setting treatment is obviously improved, and the hand feeling and surface state of the product also change obviously, which indicates that the setting treatment plays an important role in improving the performance of the material.

[0090] Comparing Comparative Examples 3 and 4 with Example 1, it can be seen that controlling the speed difference of each roller in the setting has obvious influence on the setting effect, and a certain negative speed difference has positive contribution to the self-improvement and strength improvement of the product in the heating process. The positive speed difference has certain stretching effect on the cloth surface, which is not conducive to the fiber shrinkage and improvement, and also has influence on the filtration efficiency. Different process parameters have great influence on the performance difference of the prepared product, which determines the function of the product.

[0091] Comparing Comparative Example 5 with Comparative Example 1, it can be seen that the conventional PP melt-blown does not have the fiber self-shrinkage and strength improvement process under the heat setting condition, and the filtration efficiency after the treatment has certain decline. It is indicated that there is essential difference between the performance of the conventional melt-blown material and the performance of the material prepared by the method.

[0092] Comparing Comparative Example 6 with Example 1, it can be seen that when the same new melt-blown raw material is used, the conventional melt-blown production process parameters and equipment are used, the working pressure of the equipment exceeds the use range, the prepared product has large fineness and cannot be bonded, and does not have the forming and production conditions.

[0093] Comparing Comparative Example 7 with Example 1, it can be seen that when the conventional same melt-blown raw material is used, the new product production process cannot realize the fiber forming and receiving of the cloth, and the production conditions have great difference.

[0094] Example 2

[0095] A preparation method of a melt-blown heat-shrinkable fiber paper, the steps of which are as follows: after drying, melt-blown base polyethylene terephthalate (PET) is sent into a screw extruder through a slicing conveying system, and is extruded and melted into a high-temperature melt; then the melt is metered by a metering pump and sent into a spinning system, and is extruded from a spinning hole under the action of pressure, and is drawn and attenuated by high-temperature drawing air flow on both sides of the spinning hole to become ultra-fine fibers; the obtained fibers are collected on a negative pressure screen curtain or a negative pressure perforated roller, and are bonded into a cloth by relying on self-heating and negative pressure. The cloth is wound according to requirements to form a wound filter core, and after heat setting in an oven, a filter core paper product is prepared.

[0096] The melt-blown base melt flow index (MFI) is 170 g / 10 min, and the melting point is 195℃.

[0097] The drying temperature of the base material is 120℃, and the drying time is 6 hours.

[0098] The screw length-diameter ratio is 30, and the screw temperature control is 200-290℃.

[0099] The melt temperature is 300-310℃.

[0100] The rotation speed of the metering pump is 6 revolutions per minute, and the spinning system pressure is 3.1MPa.

[0101] The spinneret hole diameter is 0.32mm, and the length-diameter ratio is 10:1.

[0102] The high-temperature gas flow pressure is 0.08MPa, and the gas flow temperature is 310℃.

[0103] The melt stream stretching area is 12cm away from the spinneret.

[0104] The negative pressure porous roller air volume is 3000m 3 / h.

[0105] The winding layer number is 10 layers, and the winding diameter is 4cm.

[0106] The oven heat setting is performed, the setting temperature is 85℃, and the setting time is 15 seconds.

[0107] The product weight is 210g / m 2 , and the product resistance is 110Pa, and the filtration efficiency is 95%.

[0108] The product has high stiffness, tight fit, longitudinal breaking strength of 170N, and transverse breaking strength of 163N.

[0109] The product has good shape retention and can be well matched with filter core accessories.

[0110] Example 3

[0111] A preparation method of a melt-blown heat-shrinkable cloth, the cloth forming process is the same as that of Example 2, after the cloth is formed, the cloth is cut into rolls according to requirements, the product is cut and heat set and shrunk after covering the product to be packaged, forming a packaging product.

[0112] The melt flow index (MFI) of the melt-blown base material is 235g / 10min, and the melting point is 205℃.

[0113] The drying temperature of the base material is 120℃, and the drying time is 6 hours.

[0114] The screw length-diameter ratio is 30, and the screw temperature control is 200-290℃.

[0115] The melt temperature is 305-310℃.

[0116] The metering pump rotation number was 6 revolutions per minute, and the spinning system pressure was 2.8 MPa.

[0117] The spinneret aperture was 0.32 mm, and the length-diameter ratio was 10:1.

[0118] The high-temperature gas flow pressure was 0.08 MPa, and the gas flow temperature was 315°C.

[0119] The melt stream stretching area was 12 cm away from the spinneret.

[0120] The negative pressure porous roller air volume was 3000 m 3 / h.

[0121] The test cloth roll transverse shrinkage (CD) was 41%, and the longitudinal shrinkage (MD) was 46%.

[0122] The oven heat setting was performed at a setting temperature of 85°C and a setting time of 10 seconds.

[0123] The product had a grammage of 30 g / m 2 , and the test results showed that the longitudinal breaking strength was 21 N, and the transverse breaking strength was 23 N.

[0124] The shrinkage was high, the product was tightly attached to the product, the packaging texture was good, and the product was waterproof and breathable.

[0125] Example 4

[0126] A preparation method of a melt-blown heat-shrinkable cloth, the cloth forming process was the same as that in Example 2, after the cloth was formed, the cloth was cut into rolls according to requirements, and the product was wrapped around the required connecting objects and then was set and shrunk, so as to wrap the objects and complete the connection.

[0127] The melt-blown base material had a melt flow index (MFI) of 165 g / 10 min and a melting point of 205°C.

[0128] The base material drying temperature was 120°C, and the drying time was 6 hours.

[0129] The screw length-diameter ratio was 30, and the screw temperature control was 200-290°C.

[0130] The melt temperature was 300-310°C.

[0131] The metering pump rotation number was 6 revolutions per minute, and the spinning system pressure was 3.2 MPa.

[0132] The spinneret aperture was 0.32 mm, and the length-diameter ratio was 10:1.

[0133] The high-temperature gas flow pressure was 0.08 MPa, and the gas flow temperature was 315°C.

[0134] The melt stream stretching area was 11 cm away from the spinneret.

[0135] The negative pressure porous roller has a wind volume of 3000m 3 / h.

[0136] The shrinkage of the test cloth roll in the cross direction (CD) is 37%, and in the longitudinal direction (MD) is 42%.

[0137] The winding layer is 60 layers.

[0138] The hot air heat setting is performed at a setting temperature of 87 DEG C for 20 seconds.

[0139] The product has a weight of 1270g / m 2 , a thickness of 10mm, high adhesion and close connection.

Claims

1. A method of making a melt-blown heat-shrinkable fibrous paper, characterized by: The preparation method is melt blowing by using high-shrinkage melt-blown base material to form high-shrinkage ultra-fine melt-blown cloth, and then shaping by a heat setting machine to make fiber paper products; The high-shrinkage melt-blown base material is polyethylene terephthalate (PET) resin; The melt blowing method is to send the dried melt-blown base material into a screw extruder through a slicing conveying system, extrude and melt into high-temperature melt, then send the melt into a spinning system through a metering pump, extrude from a spinneret under pressure, and stretch and thin the melt stream under the clamping of high-temperature stretching air flow on both sides of the spinneret to become ultra-fine fibers; the obtained fibers are collected on a negative pressure screen or a negative pressure porous roller, and are bonded into cloth by self-heating and negative pressure; The high-shrinkage melt-blown base material has a melt flow index (MFI) of 150-800 g / 10 min and a melting point range of 150-250℃; the base material drying temperature is 110-130℃, and the drying time is 4-8 hours; The screw extruder is a single screw extruder, the screw length-diameter ratio is 22-30, the screw temperature is controlled at 200-290℃, the melt temperature is 290-320℃, the high-temperature air flow pressure is 0.07-0.12 MPa, and the air flow temperature is 290-320℃.

2. The method of making a meltblown heat shrinkable fibrous paper according to claim 1, characterized in that: The heat setting machine is a tension heat setting machine, an oven heat setting machine or a hot air setting machine; the setting temperature is 50-130℃, and the setting time is 3-150 seconds.

3. The method of making a meltblown heat shrinkable fibrous paper according to claim 1, characterized in that: The metering pump rotation speed is 5-12 revolutions per minute, and the spinning system pressure is 0.5-3.5 MPa; the spinneret aperture is 0.2-0.4 mm, and the length-diameter ratio is 5-15:

1.

4. The method of making a meltblown heat shrinkable fibrous paper according to claim 1, characterized in that: The melt stream stretching area is 5-20 cm away from the spinneret; the negative pressure air volume is 1000-3500 m 3 / h; the adhesive cloth structure is a multi-layer disordered structure.

5. The melt-blown heat-shrinkable fibrous paper produced by the process of any one of claims 1 to 4, characterized in that: The unit area mass of the fiber paper is 75~85 g / m 2 The filtering efficiency of the granular is 78~82%, the air resistance is 28~32 Pa, the longitudinal tension is 38~42 N, and the lateral tension is 40~50 N.

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