Non-woven fabric

Abstract

The invention discloses a non-woven fabric, the periphery of fibers forming the non-woven fabric is coated with a hardening agent, and the area ratio of the hardening agent on the section of the non-woven fabric is 35-65%. The hot wind deformation-resistant non-woven fabric has the characteristics of high hardness, high ventilation and deformation resistance, can be applied to the field of air filtration, and is mainly applied to filters for automobile air conditioners.

Description

Technical Field

[0001] The present invention relates to a nonwoven fabric. Background Art

[0002] The car air conditioning filter is installed in the air conditioner and can filter out dust, pollen, bacteria, fungi and other tiny organisms in the external air, thereby delivering clean air into the car interior.

[0003] Currently, plant fibers or organic synthetic fibers are used as raw materials to make paper-based or thermally bonded nonwovens. These are then pleated and assembled into filter elements for use in automotive air conditioners. However, because paper-based nonwovens are made from short fibers less than 20 mm in length, they have low tensile strength. Thermally bonded nonwovens, on the other hand, are mechanically formed and have a low hardness. During use, especially in the hot summer, temperatures around car engines can reach around 80°C. This high temperature causes the solidified hot melt adhesive or hot melt fibers in the thermally bonded nonwoven to soften and melt again, reducing interfiber adhesion. This can cause the filter material to distort, increase wind resistance, and reduce the filter element's filtration efficiency.

[0004] For example, Chinese patent CN103120872A discloses a filter material for filter element, its production method and use. The filter material is made of sheath-core composite fiber and flame-retardant fiber by thermal bonding. Since the sheath-core composite fiber will soften or even melt when heated, the prepared filter material is easy to soften and deform, and the wind resistance increases, resulting in a decrease in filtration efficiency.

[0005] For example, Chinese patent publication CN1456384A discloses a fiber composite filter material for engines and its preparation method. This patent utilizes a variety of fibers, including plant fibers, organic synthetic fibers, and inorganic fibers, to form a nonwoven fabric. The filter material is then coated or impregnated with a resin and post-cured to produce the filter material. Because the fibers rely solely on the resin for bonding, and lack any inherent bonding, the filter material exhibits low hardness and, in particular, poor resistance to deformation from hot winds. Summary of the Invention

[0006] The object of the present invention is to provide a non-woven fabric with high hardness, high air permeability and deformation resistance.

[0007] The technical solution of the present invention is as follows: the fibers constituting the nonwoven fabric of the present invention are coated with a hardener, and the area of ​​the hardener on the cross section of the nonwoven fabric accounts for 35 to 65%.

[0008] Beneficial effects of the present invention: The non-woven fabric of the present invention has the characteristics of high hardness, high air permeability and deformation resistance, and can be used in the field of air filtration, mainly in filters for automobile air conditioners. DETAILED DESCRIPTION

[0009] The fibers constituting the non-woven fabric of the present invention are coated with a hardener, and the area of ​​the hardener on the cross-section of the non-woven fabric accounts for 35 to 65%. The fibers constituting the non-woven fabric of the present invention are core-sheath PET fibers and conventional PET fibers with different melting points, wherein the core-sheath PET fibers are core-sheath fibers with a core melting point of 240°C to 255°C and a skin melting point of 100 to 115°C. The hardener not only coats the molten fibers to protect them from the effects of high-temperature softening, but also plays a reinforcing role, increasing the hardness of the non-woven fabric. If the area ratio of the hardener is less than 35%, the fibers coated with the hardener are less, and the hardness of the resulting non-woven fabric is low. In a high-temperature environment, the thermally bonded fibers are easily melted, causing the non-woven fabric to soften and deform. If the area ratio of the hardener is higher than 65%, too much hardener coats the non-woven fabric, which will block the pores of the non-woven fabric, resulting in a decrease in the air permeability of the non-woven fabric and an increase in resistance. Considering the high hardness and low filtration resistance of the nonwoven fabric, the area ratio of the hardener on the cross section of the nonwoven fabric is preferably 40 to 60%.

[0010] The fiber area percentage of the cross-section of the nonwoven fabric of the present invention is preferably 15-30%. If the percentage is too small, the number of fibers in the same area is small, the pores of the resulting nonwoven fabric are increased, and small particles such as dust can easily pass through, resulting in a decrease in the filtration efficiency of the nonwoven fabric. If the percentage is too large, the number of fibers in the same area is large, the pore area between the fibers is reduced, and the air permeability of the nonwoven fabric is reduced. Considering the high filtration efficiency and air permeability of the nonwoven fabric, the fiber area percentage of the cross-section of the nonwoven fabric is more preferably 20-25%.

[0011] The nonwoven fabric of the present invention preferably has a pore area percentage of 10-40% across its cross section. Fibers impart strength and porosity to the nonwoven fabric, while the pores impart breathability. If the percentage is too low, the nonwoven fabric will have fewer pores within a given area, increasing resistance to wind speed. If the percentage is too high, the nonwoven fabric will have larger and more numerous pores within a given area, allowing dust and other small particles to easily pass through the pores, resulting in a decrease in the fabric's filtration efficiency. Considering the high filtration efficiency and low filtration resistance of nonwoven fabrics, a pore area percentage of 20-40% is more preferable.

[0012] The sheath-core fibers in the nonwoven fabric of the present invention preferably account for 60-80%. After being heated, the sheath-core fibers bond and reinforce with other conventional fibers. If the sheath-core fibers account for too high a percentage, although the bonding is good, the stiffness of the nonwoven fabric decreases due to the reduction in conventional fibers. If the sheath-core fibers account for too low a percentage, the bonding effect is lost, resulting in a decrease in the strength of the nonwoven fabric. Considering the high stiffness and strength of the nonwoven fabric, the sheath-core fibers more preferably account for 70-80%.

[0013] The hardener is preferably one or more of polyacrylate, melamine, and vinyl acetate. Polyacrylate is more preferably the hardener because it has high melt fluidity and good heat resistance, is non-flammable, and is environmentally friendly.

[0014] The angle stiffness of the nonwoven fabric of the present invention at 80°C for 30 minutes is preferably 0-40°. The lower the angle stiffness, the better the nonwoven fabric's resistance to softening and deformation in a high-temperature environment.

[0015] Typically, cross-folded thermally bonded nonwovens have a longitudinal stiffness of 90-110 mN and a transverse stiffness of 110-150 mN. Adding a hardener can significantly increase the stiffness of the present invention's nonwoven fabric, preferably reaching 200-300 mN in the longitudinal direction and 230-350 mN in the transverse direction. If the stiffness is too high, the nonwoven fabric will break easily during pleating; if it is too low, pleats will be difficult to form and will soften and deform under the influence of hot air.

[0016] The longitudinal tensile strength of the nonwoven fabric of the present invention is preferably 100-130 N / 50 mm, and the transverse tensile strength is preferably 150-180 N / 50 mm. The nonwoven fabric is not easily broken by the tensile strength in both the warp and weft directions.

[0017] The air permeability of the nonwoven fabric of the present invention is preferably 170 to 220 cm 3 / cm 2 / s. The air permeability of non-woven fabrics is related to the resistance of the wind when passing through the non-woven fabric. If it is too low, the resistance of the wind when passing through the non-woven fabric is large, and the energy consumption is also correspondingly large; if it is too high, the resistance of the wind when passing through the non-woven fabric is small, and the energy consumption is also correspondingly small.

[0018] The present invention is further described by the following examples, but the protection scope of the present invention is not limited to the examples. The physical properties in the examples are measured by the following methods.

[0019] [Area ratio of hardener]

[0020] A scanning electron microscope was used to photograph the cross section of the nonwoven fabric sample at a magnification of 200 times. CAD software was used to outline the edges of all hardeners within a range of 640 μm × 420 μm on the image. The area of ​​the hardener was measured and recorded as S1. The area of ​​the entire image was recorded as S. The area ratio of the hardener, P1, was calculated as follows: Test 3 times and take the average value.

[0021] [Area ratio of fiber]

[0022] A scanning electron microscope was used to photograph the cross section of the nonwoven fabric sample at a magnification of 200 times. CAD software was used to outline the edges of all fiber cross sections within the range of 640 μm × 420 μm on the image. The area of ​​the fiber was measured and recorded as S2. The area of ​​the entire image was recorded as S. The calculation formula for the fiber area ratio P2 is: Test 3 times and take the average value.

[0023] [Area ratio of pores]

[0024] A scanning electron microscope was used to photograph the cross section of the nonwoven fabric sample at a magnification of 200 times. CAD software was used to outline the edges of all pores within a range of 640 μm × 420 μm on the image. The area of ​​the pores was measured and recorded as S3. The area of ​​the entire image was recorded as S. The calculation formula for the fiber area ratio P3 is: Test 3 times and take the average value.

[0025]

Ratio of the number of fibers with skin-core structure

[0026] Use a scanning electron microscope to photograph the cross-section of a nonwoven fabric sample at 200x magnification, covering an area of ​​640 μm x 420 μm. Fibers with concentric circular cross-sections are sheath-core fibers, while those with nearly circular cross-sections are conventional fibers. Count the number of fibers of each type and calculate the percentage of sheath-core fibers to the total number of fibers of both types. Perform the test three times and take the average value.

[0027]

Angle stiffness

[0028] Clamp the non-woven fabric sample horizontally on the fixed fixture of the stiffness tester, ensuring that the length direction is perpendicular to the fixture, the sample width is 50mm, and the distance h2 between the sample extension direction and the clamping point is 200mm±1mm, then lock the fixed fixture. Place the stiffness tester with the clamped sample horizontally in a constant temperature oven at 80°C for 30 minutes, then take it out and cool it at room temperature for more than 5 minutes. The angle α between the lowest sagging point of the test sample and the parallel clamping point and the horizontal line is the stiffness. Among them, the height of the lowest sagging point of the sample is h1, and the horizontal distance from the lowest sagging point of the sample to the fixed fixture is l. Test 3 times and take the average value. The angle stiffness is calculated as follows:

[0029]

Hardness

[0030] According to JIS L 1096, a nonwoven fabric sample measuring 38 mm x 25 mm is conditioned at 20°C and 65% RH for 24 hours. A Garlian stiffness-softness tester is used with appropriate range weights. The swing amplitude of the test rod is measured, and the corresponding stiffness-softness value is displayed on the display. Samples are taken from any five locations on the sample. Five tests are repeated, and the average value is calculated.

[0031]

Ventilation

[0032] According to JIS L 1096 standard, the nonwoven fabric sample was placed in the test port of the Fraser air permeability tester (area 38cm 2 The test is carried out below the circle, and the test unit is cm 3 / cm 2 / s, and the test pressure is 125 Pa. Samples are taken from any five locations of the nonwoven fabric of the present invention and measured to obtain an average value.

[0033]

Tensile strength

[0034] According to JIS L 1096, the size of the nonwoven fabric sample is 300 mm×50 mm, and the effective length is 200 mm. The test is performed using an Instron measuring device at a tensile speed of 100 mm / min.

[0035] Example 1

[0036] 80% by weight of polyester fibers with a sheath-core structure and 20% by weight of conventional polyester fibers were mixed, opened, and carded to produce a fiber web. The web was then heated at 205°C to produce a thermally bonded nonwoven fabric. The thermally bonded nonwoven fabric was then impregnated with a 50% polyacrylate hardener and then dried and cross-linked at high temperature to produce the nonwoven fabric of the present invention. The physical properties of the nonwoven fabric of the present invention are shown in Table 1.

[0037] The preparation processes of Examples 2 to 10 are the same as those of Example 1, and the specific formulations and physical properties are shown in Table 1.

[0038] Comparative Example 1

[0039] 80 wt% of polyester fibers with a core-sheath structure and 20 wt% of conventional polyester fibers were mixed, opened, and carded to produce a fiber web, which was then heated at 205°C to produce a thermally bonded nonwoven fabric. The physical properties of the nonwoven fabric are shown in Table 1.

[0040] Comparative Example 2

[0041] 80% by weight of sheath-core polyester fibers and 20% by weight of conventional polyester fibers were mixed, opened, and carded to produce a fiber web. This web was then heated at 205°C to produce a thermally bonded nonwoven fabric. The thermally bonded nonwoven fabric was then impregnated with an 80% polyacrylate hardener and then dried and cross-linked at high temperature to produce the final nonwoven fabric. The physical properties of this nonwoven fabric are shown in Table 1.

[0042] Table 1

[0043]

[0044] According to Table 1

[0045] (1) It can be seen from Example 1 and Example 2 that, under the same conditions, the area ratio of the hardener on the cross section of the non-woven fabric in the former is within the preferred range. Compared with the latter, the air permeability of the non-woven fabric in the former is high, that is, the filtration resistance is low.

[0046] (2) It can be seen from Example 3 and Example 4 that, under the same conditions, the area ratio of the fibers on the cross section of the non-woven fabric in the former is within a more preferred range. Compared with the latter, the non-woven fabric in the former has high rigidity and high tensile strength, and low angle stiffness, that is, it is resistant to deformation.

[0047] (3) It can be seen from Example 5 and Example 6 that, under the same conditions, the area ratio of the pores in the non-woven fabric in the former is within a more preferred range. Compared with the latter, the air permeability of the non-woven fabric in the former is high, that is, the filtration resistance is low.

[0048] (4) It can be seen from Example 1 and Example 8 that, under the same conditions, the area ratio of the fibers on the cross section of the non-woven fabric in the former is within the preferred range, while that in the latter is slightly lower. Compared with the latter, the air permeability of the non-woven fabric in the former is moderate, that is, the filtration resistance is good.

[0049] (5) It can be seen from Example 1 and Example 9 that, under the same conditions, the ratio of the number of core and skin fibers in the former is within a more preferred range. Compared with the latter, the non-woven fabric in the former has higher rigidity and tensile strength, lower angle stiffness, and is resistant to deformation.

[0050] (6) It can be seen from Example 1 and Example 10 that, under the same conditions, the ratio of the number of core and skin fibers in the former is within the preferred range. Compared with the latter, the non-woven fabric in the former has high rigidity and tensile strength, low angle stiffness, and is resistant to deformation.

[0051] (7) It can be seen from Example 1 and Comparative Example 1 that under the same conditions, the latter non-woven fabric does not contain a hardener. Compared with the former, the latter non-woven fabric has lower rigidity and tensile strength, higher angle stiffness, and is not resistant to deformation.

[0052] (8) It can be seen from Example 1 and Comparative Example 2 that, under the same conditions, the area ratio of the hardener in the latter is too high. Compared with the former, the air permeability of the non-woven fabric in the latter is low, that is, the air permeability is poor.

Claims

1. Non-woven fabric, characterized by: The fibers constituting the non-woven fabric are coated with a hardener, and the area of ​​the hardener on the cross section of the non-woven fabric accounts for 35 to 65%.

2. The nonwoven fabric according to claim 1, wherein: The area of ​​the fibers in the cross section of the nonwoven fabric accounts for 15 to 30%.

3. The nonwoven fabric according to claim 1, wherein: The area of ​​pores on the cross section of the non-woven fabric accounts for 10 to 40%.

4. The nonwoven fabric according to claim 1, wherein: The number of sheath-core structure fibers in the non-woven fabric accounts for 60-80%.

5. The nonwoven fabric according to claim 1, wherein The hardener is one or more of polyacrylate, melamine, and vinyl acetate.

6. The nonwoven fabric according to claim 1, wherein The non-woven fabric has an angle stiffness of 0 to 40 degrees under an environment of 80 degrees Celsius for 30 minutes.

7. The nonwoven fabric according to claim 1, wherein The longitudinal stiffness and softness of the non-woven fabric are 200-300 mN, and the transverse stiffness and softness are 230-350 mN.

8. The nonwoven fabric according to claim 1, wherein The non-woven fabric has a longitudinal tensile strength of 100-130 N / 50 mm and a transverse tensile strength of 150-180 N / 50 mm.

9. The nonwoven fabric according to claim 1, wherein The air permeability of the non-woven fabric is 170 to 220 cm 3 / cm 2 / s.

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