High-stiffness PE / PET double-component non-woven fabric and application thereof

Abstract

The invention discloses a high-stiffness PE (Polyethylene) / PET (Polyethylene Terephthalate) double-component non-woven fabric and application thereof. The high-stiffness PE / PET double-component non-woven fabric is prepared from modified PE / PET double-component fibers; the modified PE / PET double-group fiber comprises a skin layer and a core layer, the skin layer comprises LDPE and modified PE, and the core layer comprises PET; the modified PE is obtained by grafting metallocene PE with maleic anhydride and then respectively grafting the maleic anhydride with styrene and POE (Polyolefin Elastomer). Styrene and POE are grafted to metallocene PE through maleic anhydride, then the metallocene PE is mixed with LDPE to obtain mixed PE, the mixed PE and polyester chips are fused through double die heads, and the modified PE / PET double-group fiber is prepared. The non-woven fabric prepared from the modified PE / PET double-group fibers is good in cohesiveness, free of blockage, high in stiffness and not prone to deformation after being folded, and the strength and supporting performance of a filter material can be improved when the non-woven fabric is used for the filter material of the flat plate filter.

Description

Technical Field

[0001] The present invention relates to the technical field of filtration, and particularly relates to a high-stiffness PE / PET bicomponent non-woven fabric and its application. Background Art

[0002] The flat panel filter has a simple structure and a low price. It is a device used for the pre-filter of air conditioning systems and comfort air conditioning systems with low purification requirements, and is used to filter dust particles larger than 5μm. The flat panel filter generally consists of an outer frame, a filter medium, and a protective net. The outer frame includes a paper frame, an aluminum frame, and a galvanized iron frame. The filter medium includes non-woven fabric, nylon mesh, activated carbon filter material, metal hole mesh, etc. The protective net includes a double-sided plastic-sprayed iron wire mesh and a double-sided galvanized iron wire mesh. Among them, the filter medium is mainly non-woven fabric, and the non-woven fabric here is basically composed of a multi-layer structure. For example, both the upper and lower layers are PE non-woven fabrics, and the middle layer is a PTFE non-woven fabric. The three-layer non-woven fabric is folded, and the filter medium is formed by folding. The purpose of folding is not only to increase the filtration area, but also to play a certain supporting role.

[0003] The two-component PE / PET non-woven fabric is a high-performance material that tightly combines two different fiber materials. This non-woven fabric has good air permeability and moisture absorption, as well as excellent tensile and tear resistance. Therefore, the two-component PE / PET non-woven fabric has gradually replaced the PE non-woven fabric for filter media. However, the two-component PE / PET non-woven fabric is prepared from the two-component bonded fibers of PE / PET, and after being made into a filter medium, it has the same problem as the PE non-woven fabric, that is, the material is not stiff enough, and it is difficult for the non-woven fabric to maintain a good folded state after being folded. Therefore, it is necessary to increase the content of PET in the two-component PE / PET fiber to improve the stiffness. However, when the PET content increases, the content of PE will decrease, and the non-woven fabric cannot be well bonded together during thermal lamination, thus affecting the porosity of the non-woven fabric. For example, Patent CN1705782A discloses a non-woven fabric composed of core-sheath composite fibers and its preparation method. The skin component is obtained by mixing the first polyethylene obtained by a metallocene catalyst and the second polyethylene obtained by a Ziegler-Natta catalyst, and the skin thickness varies unevenly and randomly in the fiber axial direction and the fiber circumferential direction. The non-woven fabric made of this core-sheath composite fiber is relatively soft and not suitable as a folded filter material. Patent CN1042385A discloses a two-component bonded fiber of PE / PET, and its skin layer is composed of an ethylene / vinyl acetate copolymer monomer or an ethylene / acrylic ester system. Only when the skin component in the fiber accounts for a relatively large proportion can a better bonding effect be achieved, so that the pore diameter of the fiber is bonded or blocked by the low-melting-point PE component during the thermal lamination processing of the final non-woven fabric. Therefore, these two-component fibers of PE / PET disclosed in the prior art are not suitable for manufacturing the filter media of flat filters. There is a need for a high-stiffness two-component PE / PET non-woven fabric that can improve the stiffness of the non-woven fabric without reducing the PE content and can better maintain the folded state after being folded as the filter media of flat filters. Summary of the Invention

[0004] In view of the above prior art, the object of the present invention is to provide a high-stiffness two-component PE / PET non-woven fabric and its application. The present invention grafts styrene and POE onto metallocene PE through maleic anhydride, and then mixes it with LDPE to obtain a mixed PE. The mixed PE and polyester chips are melted through a dual die head to prepare modified PE / PET double-component fibers. The non-woven fabric prepared from the modified PE / PET double-component fibers not only has good adhesion and no blockage, but also has high stiffness and is not easily deformed after being folded. It can be used as the filter media of flat filters to improve the strength and support of the filter media.

[0005] To achieve the above object, the present invention adopts the following technical solutions: In the first aspect of the present invention, there is provided a high-stiffness two-component PE / PET non-woven fabric, and the high-stiffness two-component PE / PET non-woven fabric is prepared from modified PE / PET double-component fibers; The modified PE / PET bicomponent fiber comprises a skin layer and a core layer. The skin layer comprises LDPE and modified PE, and the core layer comprises PET. The modified PE is obtained by grafting maleic anhydride onto metallocene PE, and then grafting styrene and POE onto maleic anhydride respectively.

[0006] Preferably, the mass ratio of LDPE to modified PE is 1:1 - 5; the mass proportion of the skin layer in the modified PE / PET bicomponent fiber is 20 - 60%.

[0007] Preferably, the modified PE is prepared by the following method: Pre-mix metallocene PE, maleic anhydride, styrene, POE and an initiator uniformly, and then conduct melt grafting using a single-screw extruder. After extrusion, pelletize and dry to obtain modified PE pellets.

[0008] Preferably, the mass ratio of metallocene PE, maleic anhydride, styrene and POE is 100:1 - 5:1 - 3:0.1 - 0.5; the initiator is DCP, and the dosage of the initiator accounts for 0.1 - 0.3% of the total mass of metallocene PE.

[0009] Preferably, the temperature of the PE extruder is 180 - 275 °C, and the temperature of the PET extruder is 255 - 300 °C.

[0010] Preferably, the high-stiffness PE / PET bicomponent non-woven fabric is prepared by the following method: (1) Mix LDPE and modified PE uniformly to obtain mixed PE. Melt the mixed PE and polyester chips using a dual die head, and conduct negative pressure drawing on the drawn fibers to obtain modified PE / PET bicomponent fibers; (2) Subject the modified PE / PET bicomponent fibers to air laying, then hot rolling, and finally winding and slitting to obtain the high-stiffness PE / PET bicomponent non-woven fabric.

[0011] Preferably, the side blowing air mixing ratio required for drawing is 80 - 95%, and the air temperature is 25 - 50 °C.

[0012] Preferably, the temperature of hot rolling is 125 - 145 °C, and the pressure of hot rolling is 35 - 100 N / mm.

[0013] In the second aspect of the present invention, there is provided the application of the high-stiffness PE / PET bicomponent non-woven fabric in improving the stiffness of the filter material of a flat filter and maintaining the pleated morphology.

[0014] In the third aspect of the present invention, there is provided a filter material for a flat filter. The upper layer and the lower layer of the filter material are high-stiffness PE / PET bicomponent non-woven fabrics, and the middle layer is a PTFE non-woven fabric.

[0015] Advantages of the present invention: (1) The high-stiffness PE / PET bicomponent non-woven fabric of the present invention has a higher porosity under the same areal density, and there are no blocked points in the non-woven fabric. As the filter material of a flat filter, the filtering effect can be improved.

[0016] (2) The high-stiffness PE / PET bicomponent non-woven fabric of the present invention has high stiffness and tensile strength. As the filter material of a flat filter, it is not easily deformed after being folded and has good support.

[0017] (3) The preparation method of the present invention is simple. Compared with PE non-woven fabric, it only has one more modification step, and the melt modification preparation method is simple and easy to operate. Description of the Drawings

[0018] Figure 1 : Photos of the non-woven fabrics prepared in Example 2 and Comparative Examples 1-5 after being folded for 15 days. Detailed Embodiments

[0019] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0020] As introduced in the background art section, PE is relatively soft, and the prepared non-woven fabric cannot maintain the wrinkled shape for a long time. If the stiffness of the non-woven fabric is to be improved, the stiffness of the PE non-woven fabric needs to be increased. The content of PET in the bicomponent PE / PET fiber can improve the stiffness of the non-woven fabric, but when the PET content increases, the content of PE decreases, and the non-woven fabrics cannot be well bonded together during thermal lamination, thus affecting the porosity of the non-woven fabric and further affecting the filtering effect of the non-woven fabric.

[0021] Based on this, the object of the present invention is to provide a high-stiffness PE / PET bicomponent non-woven fabric and its application. First, the PE / PET bicomponent fiber of the present invention needs to be modified. The skin layer of the PE / PET bicomponent fiber includes LDPE and modified PE, and the core layer is PET. The modified PE is obtained by grafting styrene and POE onto metallocene PE through maleic anhydride (MAH). Compared with traditional LDPE and LDPE, metallocene polyethylene (mPE) has a lower melting point and Vicat softening point. Short branches above ethyl with uniform and regular distribution are introduced into the molecular straight chain, and its branches do not participate in the crystallization process of polyethylene and are only distributed in the amorphous region. Under the action of an initiator, it is easier to generate tertiary carbon free radicals, which do not damage the polyethylene lattice structure and are easy to carry out grafting reactions. In addition, after mPE is grafted and modified with maleic anhydride, it can be used as a good matrix resin for polyolefin hot melt adhesives. Therefore, maleic anhydride is not only used to graft styrene and POE onto mPE, but also the single grafting of maleic anhydride on mPE can improve the thermal viscosity of mPE. However, only grafting MAH cannot improve the stiffness of the non-woven fabric. Although the stiffness of the non-woven fabric is improved after adding styrene, the maintenance of the wrinkled morphology after folding is unstable. Through continuous experiments by the inventors, it is found that after grafting a small amount of POE, the maintenance of the wrinkled morphology is more stable. And the above grafting occurs on the short branches of mPE, which does not affect the crystallization of polyethylene and the overall performance of PE is not damaged. The non-woven fabric prepared from the modified PE / PET bicomponent fiber has high strength, high stiffness, stable wrinkled shape, and high porosity, and is suitable for use as a filter material for flat filters.

[0022] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the technical solution of the present application will be described in detail below in conjunction with specific embodiments.

[0023] The test materials used in the embodiments of the present invention are all conventional test materials in the art and can be obtained through commercial channels.

[0024] Example 1: Preparation of Modified PE Mix 100 kg of metallocene PE (DuPont MVLDPE), 3 kg of maleic anhydride, 2 kg of styrene, 500 g of POE, and 300 g of initiator DCP evenly with a mixer. Mix quickly, control the time within 10 minutes, and control the temperature of the mixer below 90 °C. The mixed material is then melt-grafted with a single-screw extruder, the temperature of the extruder is 180 - 275 °C, and after extrusion, it is pelletized and dried to obtain modified PE particles.

[0025] Example 2: Preparation of High-Stiffness PE / PET Bicomponent Non-Woven Fabric First, 20 kg of LDPE particles (melting point 115 - 129 °C, density 0.955 g / cm 3)( ) is mixed evenly with the modified PE particles prepared in Example 1 with 80 kg to obtain the mixed PE. 50 kg of the mixed PE and 50 kg of PET (melting point 255 - 265 °C, viscosity 0.4 dl / g - 0.65 dl / g) slices are used to prepare the PE / PET bicomponent non-woven fabric by the spunbond process. Specifically: The mixed PE and PET slices are melted by a dual die head. The melting temperatures are 265 - 275 °C and 290 - 300 °C; negative pressure drawing: the side blowing humidity is 5 - 25%, the air temperature: 30 - 50 °C, the fiber fineness is 1 - 2.5 D; air laying; hot rolling reinforcement: the rolling mill temperature is 130 °C, the rolling mill pressure is 50 N / mm; winding and slitting; the single-hole discharge amount is 40 - 60 g / h / m, and the drawing air pressure is 0.24 - 0.27 MPa. After measurement, the thickness of the prepared PE / PET bicomponent non-woven fabric is 0.32 ± 0.05 mm, and the gram weight is about 50 ± 5 g / m 2 .

[0026] Comparative Example 1 The difference from Example 2 is that no modified PE is added, and all LDPE is used. Finally, the PE / PET bicomponent non-woven fabric is prepared with a thickness of 0.32 ± 0.05 mm and a gram weight of about 50 ± 5 g / m 2 .

[0027] Comparative Example 2 The difference from Example 2 is that the modified PE is replaced with an equal amount of metallocene PE (DuPont MVLDPE), that is, the mPE is not modified. Finally, the PE / PET bicomponent non-woven fabric is prepared with a thickness of 0.32 ± 0.05 mm and a gram weight of about 50 ± 5 g / m 2 .

[0028] Comparative Example 3 (1) 100 kg of metallocene PE (DuPont MVLDPE), 3 kg of maleic anhydride and 300 g of initiator DCP are mixed evenly by a mixer. The rapid mixing time is controlled within 10 min, and the mixer temperature is controlled below 90 °C. The mixed material is then melt grafted by a single-screw extruder. The temperature of the extruder is 180 - 275 °C, and after extrusion, it is pelletized and dried to obtain the modified PE particles.

[0029] (2) The preparation of the PE / PET bicomponent non-woven fabric is the same as that in Example 2, except that the modified PE particles prepared in this comparative example are used instead of the modified PE prepared in Example 1. The thickness of the PE / PET bicomponent non-woven fabric is 0.32 ± 0.05 mm, and the gram weight is about 50 ± 5 g / m 2 .

[0030] Comparative Example 4 (1) Mix 100 kg of metallocene PE (DuPont MVLDPE), 3 kg of maleic anhydride, 2 kg of styrene, and 300 g of initiator DCP evenly with a mixer. Mix quickly, with the time controlled within 10 min and the temperature of the mixer controlled below 90°C. Then, melt-graft the mixed material with a single-screw extruder. The temperature of the extruder is 180 - 275°C. After extrusion, pelletize and dry to obtain modified PE pellets.

[0031] (2) The preparation of the PE / PET bicomponent non-woven fabric is the same as that in Example 2, except that the modified PE pellets prepared in this comparative example are used instead of the modified PE prepared in Example 1. The thickness of the PE / PET bicomponent non-woven fabric is 0.32 ± 0.05 mm, and the gram weight is about 50 ± 5 g / m 2 .

[0032] Comparative Example 5 (1) Mix 100 kg of metallocene PE (DuPont MVLDPE), 3 kg of maleic anhydride, 2 kg of styrene, and 300 g of initiator DCP evenly with a mixer. Mix quickly, with the time controlled within 10 min and the temperature of the mixer controlled below 90°C. Then, melt-graft the mixed material with a single-screw extruder. The temperature of the extruder is 180 - 275°C. After extrusion, pelletize and dry to obtain pellets, and then add 500 g of POE pellets and mix evenly to obtain modified PE pellets.

[0033] (2) The preparation of the PE / PET bicomponent non-woven fabric is the same as that in Example 2, except that the modified PE pellets prepared in this comparative example are used instead of the modified PE prepared in Example 1. The thickness of the PE / PET bicomponent non-woven fabric is 0.32 ± 0.05 mm, and the gram weight is about 50 ± 5 g / m 2 .

[0034] Test Example 1 Detect the stiffness, air permeability, tensile strength, and folding strength of the non-woven fabrics prepared in Example 2 and Comparative Examples 1 - 5 according to the test method disclosed in the patent with the application number JP2018119649 and the patent name "Spunbond non-woven fabric for filters and its manufacturing method". Among them, the stiffness is tested with a softness tester (Zhejiang Sangongjiang Instrument Co., Ltd., model SGJ197), the air permeability is tested with an air permeability tester (Guangzhou Runhu Instrument Co., Ltd., RH-TQZ500), the tensile strength is tested with a non-woven fabric tensile strength tester (Guangzhou Kehong Instrument Technology Co., Ltd., KH-8003A), and the folding strength is tested with a MIT folding endurance tester (Guangdong Inter-National Instrument Co., Ltd.). The obtained results are shown in Table 1.

[0035] Table 1 Stiffness, air permeability, tensile strength, and folding strength As can be seen from Table 1, compared with Comparative Examples 1-5, the non-woven fabric prepared in Example 2 has higher stiffness, strength and air permeability than Comparative Examples 1-5. It is worth noting that compared with Comparative Examples 2 and 3, although the stiffness of Comparative Example 4 is increased, the air permeability is decreased; it may be that the addition of styrene affects the adhesiveness of the non-woven fabric. In Comparative Example 5, POE is not grafted, and after POE is blended with PE, although the stiffness is increased, the air permeability is further decreased, indicating that adding POE without grafting will block the pores of the non-woven fabric, resulting in a decrease in air permeability. After adding a small amount of POE in Example 2, the adhesiveness of the non-woven fabric is improved, the problem of pore blockage is reduced, and the air permeability of the non-woven fabric is improved; and it can also slightly increase the stiffness of the non-woven fabric.

[0036] Test Example 2 The non-woven fabrics prepared in Example 2 and Comparative Examples 1-5 were cut according to the specifications of length×width of 1m×0.5m. In a clean room (25°C, humidity 50%), the cut non-woven fabrics were folded with a folding machine, the folding angle was set at 90°, and the folding side length was 2 cm. After folding, each non-woven fabric was placed on a flat table along the folding direction and left standing for 15 days. After 15 days, a protractor was used to measure the folding angle of each fold of the non-woven fabric, and the obtained results were averaged, as shown in Table 2 and Figure 1 .

[0037] Table 2 Angle change According to Table 2 and Figure 1 It can be seen that compared with Comparative Examples 1-5, the non-woven fabric prepared in Example 2 has the smallest angle change. After standing for 3 days, it can still maintain an angle close to vertical, while the angles of Comparative Examples 1-5 are all obtuse angles, indicating that the folding shape of the non-woven fabric is not well maintained. Comparing Example 2 and Comparative Example 4, it can be seen that after adding styrene, the ability to maintain the folding morphology is significantly improved, and after grafting POE, the degree of maintaining the folding morphology is further improved. In Comparative Example 5, POE is added by blending POE with PE. Compared with Comparative Example 4, the folding angle basically does not change, indicating that grafting POE has a better effect than adding POE alone in maintaining the folding morphology.

[0038] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A high stiffness PE / PET two-component non-woven fabric, characterized in that: The high stiffness PE / PET two-component non-woven fabric is prepared from modified PE / PET two-component fibers; The modified PE / PET double-group fiber comprises a skin layer and a core layer, wherein the skin layer comprises LDPE and modified PE, and the core layer comprises PET; The modified PE is obtained by grafting metallocene PE with maleic anhydride, and then grafting maleic anhydride with styrene and POE respectively.

2. The high stiffness PE / PET two-component non-woven fabric according to claim 1, characterized in that: The mass ratio of the LDPE to the modified PE is 1:1-5; the mass proportion of the cortex in the modified PE / PET double-group fiber is 20-60%.

3. The high stiffness PE / PET two-component non-woven fabric according to claim 1, characterized in that: The modified PE is prepared by the following method: The metallocene PE, maleic anhydride, styrene, POE and initiator are pre-mixed uniformly, and then melt-grafted by a single-screw extruder. After extrusion, granulation and drying are performed to obtain modified PE particles.

4. The high stiffness PE / PET two-component non-woven fabric according to claim 3, characterized in that: The mass ratio of the metallocene PE, maleic anhydride, styrene and POE is 100:1-5:1-3:0.1-0.5; the initiator is DCP, and the amount of the initiator accounts for 0.1-0.3% of the total mass of the metallocene PE.

5. The high stiffness PE / PET two-component non-woven fabric according to claim 3, characterized in that: The temperature of the PE extruder is 180-275°C, and the temperature of the PET extruder is 240-300°C.

6. The high stiffness PE / PET two-component nonwoven fabric according to claim 1, characterized in that: The high stiffness PE / PET two-component non-woven fabric is prepared by the following method: (1) LDPE and modified PE are uniformly mixed to obtain mixed PE, the mixed PE and polyester chips are melted by a double die head, and the drawn fibers are subjected to negative pressure drawing to obtain modified PE / PET double-group fibers; (2) The modified PE / PET two-component fibers are air laid, hot rolled, and finally wound and slit to obtain a high stiffness PE / PET two-component nonwoven fabric.

7. The high stiffness PE / PET two-component nonwoven fabric according to claim 6, characterized in that: The side blowing air mixing ratio required for the drafting is 80-95%, and the air temperature is 25-50°C.

8. The high stiffness PE / PET two-component nonwoven fabric according to claim 6, characterized in that: The hot rolling temperature is 125-145° C., and the hot rolling pressure is 35-100 N / mm.

9. Use of the high stiffness PE / PET bicomponent nonwoven fabric according to any one of claims 1 to 8 in improving the stiffness of flat filter media and maintaining the pleated morphology.

10. A flat filter material, characterized in that: The upper and lower layers of the filter material are the high-stiffness PE / PET two-component non-woven fabric as described in any one of claims 1 to 8, and the middle layer is a PTFE non-woven fabric.

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