High-strength breathable film and preparation method thereof

Abstract

The invention discloses a high-strength breathable film and a preparation method thereof, a first polymer of the breathable film is a non-woven fabric with random orientation of single fibers and fiber bundles, and a second polymer is perpendicular to the thickness direction of the non-woven fabric, intersects with the interior and the surface of the first polymer fiber and forms a hot melting welding point. The preparation method of the high-strength gas-permeable membrane comprises the following steps: 1, adding a first polymer material into a feed port of a first extruder and forming a net through a lapper, and 2, preheating a second extruder and a shunting needle plate of a needle machine, adding a second polymer material into a feed port of the second extruder, needling the shunting plate by the needle machine to do circulating reciprocating motion, and carrying out extrusion molding to obtain the high-strength gas-permeable membrane. Thirdly, a traction roller and a hot-pressing device are started, after hot-pressing stretching is conducted, the breathable film with the high-strength air permeability is obtained, and finally the breathable film is collected by a collecting roller. The two polymers are needled and injected to form a three-dimensional fiber network structure, and hot-press fusion welding is adopted, so that the membrane has more excellent mechanical property and ventilation effect.

Description

Technical Field

[0001] The invention relates to a high-strength breathable film and a preparation method thereof, and belongs to the field of polymer material textile processing. Background Art

[0002] Breathable film is a thin film that can be permeated by air and water vapor but not by liquid. High-strength breathable film materials have excellent properties such as waterproof and breathable, strong and tear-resistant, light and puncture-resistant, and low dust. They are widely used in medical packaging, protective clothing, surgical clothing, and construction due to their excellent protective performance. my country has a large demand for high-strength breathable film products, but the industry is developing slowly.

[0003] The traditional gluing process not only makes the air permeability of the non-woven film worse, but also does not significantly improve its strength. Chinese patent CN108000997B discloses a high-strength polyester spunbond non-woven quicklime desiccant packaging film and its production method. The packaging film is composed of a spunbond non-woven fabric and a breathable film, but the two materials of the packaging film are connected by an adhesive, which reduces the air permeability of the film. Chinese patent CN105966016A discloses a high-strength water-blocking and breathable non-woven fabric. The breathable non-woven fabric is composed of two layers of non-woven fabric, a reinforced waterproof and breathable layer, air holes and a reinforced fiber mesh, but the air permeability of the high-strength water-blocking and breathable film is only maintained by the reinforced waterproof and breathable layer and the air holes. Therefore, the air permeability of the high-strength water-blocking and breathable film is poor and the strength of the high-strength water-blocking and breathable film needs to be supported by the reinforced fiber mesh.

[0004] For the preparation of high-strength breathable membranes by traditional gluing methods such as gluing, dispensing, and dipping, the glue will block the breathable structure between the non-woven fibers and the surface, the breathability of the breathable membrane will be greatly reduced, and the improvement of mechanical properties is not outstanding. Compared with the traditional method of applying fiber micelles inside the non-woven fibers, it can not only ensure the three-dimensional mesh structure inside the non-woven fabric and ensure its breathability, but also improve its puncture resistance and tear resistance. The micelle fibers are hot-melt bonded to the non-woven fibers to form a high-strength fiber cross-linking network.

[0005] In order to meet the needs of domestic related industries for high-performance non-woven film materials, this patent proposes a high-strength breathable film and a preparation method thereof. Summary of the invention

[0006] The present invention combines acupuncture technology, microporous injection technology, hot pressing technology and breathable membrane, and proposes a new preparation method of high-strength breathable membrane and its preparation method, which avoids the reduction of air permeability caused by directly using adhesives or surface coating, and at the same time makes the micelles and non-woven fabrics form a three-dimensional network structure, thereby enhancing the strength of the breathable membrane, and hot pressing and welding the network micelle non-woven fabric after needle entanglement, thereby greatly improving the mechanical properties and interlayer peeling strength of the breathable membrane.

[0007] The invention discloses a high-strength breathable film, which is composed of a first polymer and a second polymer. The first polymer fibers constitute the main body of a non-woven fabric, which is a non-woven fabric with randomly oriented single fibers and fiber bundles. The second polymer fibers are perpendicular to the thickness direction of the non-woven fabric, cross with the inside and surface of the first polymer fibers, and form hot-melt welding points. The high-strength breathable film is usually 0.1-0.3 mm thick, has a water contact angle range of 130°-150°, an air permeability greater than 1 μm / (Pa·s), a longitudinal tensile strength greater than 6 kN / m, and a transverse tensile strength greater than 5 kN / m.

[0008] The polymer fibers or fiber bundles are characterized in that the first polymer fibers or fiber bundles have a fineness range of 1 to 30 microns, preferably 5 to 20 microns, and the second polymer fibers or fiber bundles have a fineness range of 10 to 50 microns, preferably 15 to 35 microns.

[0009] The invention discloses a high-strength breathable film, comprising a first polymer material for preparing a non-woven fabric and a second polymer material for acupuncture injection, wherein the first polymer comprises a main raw material for preparing the non-woven fabric and auxiliary raw materials such as the required solvent, and the second polymer is a thermoplastic material.

[0010] The invention discloses a high-strength breathable film, wherein a first polymer and a second polymer are the same or different, wherein the first polymer can be at least one of polyethylenes of different molecular weights, i.e., HDPE, LDPE, LLDPE or multi-component polyethylene PE blends, polypropylene PP, polyamide PA, polyethylene terephthalate PET, etc.; and the second polymer can be at least one of acrylic hot-melt adhesive particles, EVA hot-melt adhesive particles, water-based polyurethane APU, ethylene ethyl acrylate EEA, ethylene butyl acrylate EBA, polyamide PA, polyether sulfone PES, etc.

[0011] The first polymer material may be in the form of strips, rods or particles. Of course, the first polymer material of the present invention may also be in other shapes, such as continuous filaments. In the present invention, the first polymer material in the form of strips, rods or particles may be cut from continuous filaments. The second polymer material may be in the form of strips, rods or particles. In addition, the second polymer material of the present invention may be in a liquid state and may be prepared from strips, rods, particles or the like.

[0012] The invention discloses a method for preparing a high-strength breathable film. The method uses a first polymer and a second polymer as raw materials, uses a first extruder, a spinning system and a web-forming machine to prepare a first polymer non-woven fabric with a structure of single fibers and fiber bundles randomly oriented, and vertically punctures the first polymer non-woven fabric through the reciprocating motion of a needle-punched diverter plate. The array hollow needles penetrate the first polymer non-woven fabric, and the side barbs of the needles drive the surface layer of the fiber net, so that the fibers are relatively displaced and entangled together, and are squeezed together at the same time. At the same time, a second extruder injects the second polymer into the hollow flow channel of the needle along a hot runner, and during the needle-punching process, the second polymer material is uniformly injected into the internal fiber layer of the non-woven fabric perpendicular to the thickness direction of the non-woven fabric, so as to form an intersection with the inside and surface of the first polymer fiber, and form a hot melt welding point, so as to apply three-dimensional fiber micelles to the non-woven fabric inside. Finally, a traction roller transports the needle-punched and glued non-woven fabric to a hot pressing device to perform multi-layer melt welding and pressing on the non-woven fabric to obtain a high-performance non-woven fabric.

[0013] The application of the second polymer can be combined with the existing technology and the needling machine, including but not limited to: using the second extruder to connect the pressing pump through the hot runner, combining the pressing pump with the needling diverter plate, and when the needling diverter plate moves through the connecting rod mechanism, the pressing pump is pressed, so that the second polymer is applied at the same frequency as the needling; combining the hot runner with the piezoelectric injection valve, realizing accurate and rapid colloid injection through the pulse signal, and uniform injection through the hollow needle.

[0014] The present invention discloses a high-strength breathable membrane, and the preparation method thereof is as follows:

[0015] The first step: heating the first extruder and the spinning system, and keeping the temperature for a certain period of time after the first extruder and the spinning die head reach the predetermined temperature. Add the first polymer material into the feed port of the first extruder, and the material enters the spinning die head after being melted and plasticized by the single screw extruder, and the web forming machine is turned on, and the melt is stretched into filaments at the tip of the die head and formed into a web by the web forming machine.

[0016] Step 2: Preheat the second extruder and the needle punching machine diverter plate, and keep it warm for a certain period of time after the extruder temperature reaches the preset temperature. Add the second polymer material to the feed port of the second extruder, and melt and extrude it to the needle punching diverter plate through the hot runner. During the conveying process of the non-woven fabric in the needle punching machine, the needle punching diverter plate of the needle punching machine performs a cyclic reciprocating motion to needle the non-woven fabric. At the same time, the diverter plate heats and keeps the second polymer warm and injects it into the inner layer of the non-woven fabric through a hollow needle. The needle punching frequency of the needle punching machine is 100 to 3000 times / min, the cloth needle density is 1000 to 6000 pieces / square meter, the needle size is 3 to 15cm, and the conveying speed of the non-woven fabric is 4 to 20m / min.

[0017] Step 3: Start the traction roller and hot pressing device. After the non-woven fabric is collected by the mesh belt, it passes through the traction roller and enters the horizontal hot pressing state. The gap between the rollers in the hot pressing area is set to about 5 to 30 mm, the temperature is 100℃ to 300℃, and a certain speed difference can be adjusted between the two-stage hot pressing rollers. The roller speed is 400 to 2000mm / min. After hot pressing and stretching, a breathable film with high-strength breathability is obtained, and finally collected by the collection roller.

[0018] The high-strength breathable film of the present invention can be applied to the fields of medical breathable film packaging, protective clothing, construction, radiation refrigeration and filtration.

[0019] The high-strength breathable membrane and the preparation method thereof of the present invention have the following main advantages:

[0020] (1) The needle puncture device is combined with the micropore injection device, which has a simple structure, safety, environmental protection and strong operability.

[0021] (2) The polymer does not require the use of auxiliary solvents, and the preparation process is green and environmentally friendly, without pollution or harm.

[0022] (3) The two polymer raw materials are needle-punched and injected to form a two-component polymer film with a three-dimensional fiber network structure, which improves the strength of the polymer film and avoids the reduction in air permeability caused by traditional glue coating.

[0023] (4) The needle punching process improves the flexible entanglement between the fibers of the non-woven fabric material, and has better dimensional stability and strength.

[0024] (5) The hot-pressing fusion welding technology is used to weld and cross-link the non-woven fabric after vertical puncture and gluing. Compared with the processes of gluing, surface coating, and dipping, it has better mechanical properties and breathability.

[0025] (5) The fiber composite process is highly efficient, the nonwoven fabric has high strength and low porosity. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings are used to further understand the present invention and constitute a part of the specification, and together with the following specific embodiments, are used to explain the present invention. The equipment and process in the accompanying drawings are only specific examples of one of the processes in the description and do not constitute a limitation of the present invention.

[0027] Figure 1 This is a structural diagram of a spray-spun nonwoven fabric with a high-strength breathable membrane according to the present invention.

[0028] Figure 2 This is a schematic diagram of the structure of a needle-punched injection nonwoven fabric with a high-strength breathable membrane according to the present invention.

[0029] In the figure: 1 - first polymer fiber; 2 - second polymer fiber. DETAILED DESCRIPTION

[0030] To make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0031] The present invention discloses a high-strength breathable film, the breathable film is composed of a first polymer and a second polymer, the first polymer fiber 1 constitutes a non-woven fabric body, such as Figure 1 As shown, it is a non-woven fabric with randomly oriented single fibers and fiber bundles. The second polymer fiber 2 is perpendicular to the thickness direction of the non-woven fabric, crosses with the inside and surface of the first polymer fiber 1, and forms a hot melt welding point, such as Figure 2 The thickness of high-strength breathable membrane is usually 0.1-0.3mm, the water contact angle range is 130°-150°, the air permeability is greater than 1μm / (Pa·s), the longitudinal tensile strength is greater than 6kN / m, and the transverse tensile strength is greater than 5kN / m.

[0032] The present invention provides a method for preparing a high-strength breathable membrane:

[0033] The first step: heating the extruder and the spinning die head, and keeping them warm for a certain period of time after the extruder and the die head reach the predetermined temperature. Add the first material into the feed port, and the material enters the spinning die head after being melted and plasticized by the single screw extruder.

[0034] Step 2: Turn on the web forming machine, the melt is stretched into filaments at the tip of the die and deposited onto the receiving mesh belt.

[0035] Step 2: Preheat the precision extruder and start the needle punching machine. After the temperature of the precision extruder reaches the preset temperature, keep it warm for a certain period of time. Add the second material to the injection machine feed port. The material is melted and extruded through the hot runner to the needle punching manifold, and then injected into the inner layer of the non-woven fabric through the hollow needle.

[0036] Step 3: Start the traction roller, hot pressing roller and collecting roller. After the non-woven fabric is collected by the mesh belt, it passes through the traction roller and enters the horizontal hot pressing state. The gap between the rollers in the hot pressing area is set to about 5 to 30 mm, the temperature is 100℃ to 300℃, and a certain speed difference can be adjusted between the hot pressing rollers. The roller speed is 400 to 2000mm / min. After hot pressing and stretching, a breathable film with high-strength breathability is obtained, which is finally collected by the collecting roller.

[0037] The temperature of the extruder is set at 180-300°C, the temperature of the spinning die head is 200-400°C, the temperature of the precision extruder is 150-300°C, the frequency of the needle punching machine is 100-3000 times / min, the density of the needles is 1000-6000 pieces / m2, the temperature of the hot pressing roller group is set at 80-150°C, the pressure is 3-7MPa, and the gap between the rollers is 0.05mm-0.3mm. The roller speed draft ratio is 1:1.1-1:1.6.

[0038] The examples and comparative examples of the present invention use the following raw materials, but are not limited to these raw materials:

[0039] High-density polyethylene M691, LG Co., South Korea;

[0040] Low-density polyethylene MG6000, Shanghai Petrochemical Co., Ltd.;

[0041] Polyethylene wax (PEW), Mitsui Chemicals, Ltd., Japan;

[0042] Polyamide (PA) 8620M hot melt adhesive pellets, Guangdong Suning New Materials Co., Ltd.

[0043] Embodiment 1:

[0044] The temperature of the extruder was set at 235°C; the temperature of the spinning die was set at 240°C; the air pressure of the hot air inlet of the web forming machine was 0.4Mpa, and the temperature was set at 265°C; the temperature of the precision extruder was set at 200°C; the frequency of the needle punching machine was 1000 times / min; the temperature of the hot pressing roller group was set at 85°C, the pressure of the rollers was 5MPa, and the gap between the rollers was 0.1mm. The roller speed draft ratio was 1:1.2.

[0045] Preheat the extruder, web-forming machine and spinning die head, and after the temperature stabilizes, add 100 parts of high-density polyethylene M691 from the barrel into the extruder, spin through the spinning die head and form a web by the web-forming machine to obtain the following: Figure 1 Nonwoven fabric shown.

[0046] Preheat the precision extruder, keep it warm for about half an hour after reaching the set temperature, add the PA hot melt rubber pellets from the barrel into the extruder, start the needle punching machine, and the nonwoven fabric is drawn into the needle punching machine for needle punching injection. The schematic diagram is shown in Figure 2 shown.

[0047] The nonwoven fabric is subjected to heat pressing and differential stretching by means of a traction roller and a secondary hot pressing roller group, thereby forming a high-strength breathable film with high fiber density and strength. The high-strength breathable film is finally collected into a roll by a winding roller.

[0048] Embodiment 2:

[0049] The temperature of the extruder was set at 230°C; the temperature of the spinning die was set at 260°C; the air pressure of the hot air inlet of the web forming machine was 0.4Mpa, and the temperature was set at 265°C; the temperature of the precision extruder was set at 200°C; the frequency of the needle punching machine was 1000 times / min; the temperature of the hot pressing roller group was set at 85°C, the pressure of the rollers was 5MPa, and the gap between the rollers was 0.1mm. The roller speed draft ratio was 1:1.2.

[0050] Preheat the extruder, web-forming machine and spinning die head, and after the temperature stabilizes, add 70 parts by weight of low-density polyethylene and 30 parts by weight of PEW blended materials from the barrel into the extruder, spin through the spinning die head and form a web by the web-forming machine to obtain a nonwoven fabric.

[0051] Preheat the precision extruder, keep it warm for about half an hour after reaching the set temperature, add the PA hot melt rubber particles from the barrel into the extruder, start the needling machine, and the nonwoven fabric is drawn into the needling machine for needling injection.

[0052] The nonwoven fabric is subjected to heat pressing and differential stretching by means of a traction roller and a secondary hot pressing roller group, thereby forming a high-strength breathable film with high fiber density and strength. The high-strength breathable film is finally collected into a roll by a winding roller.

[0053] Comparative Example 1:

[0054] The temperature of the extruder was set at 235°C; the temperature of the spinning die was set at 240°C; the air pressure of the hot air inlet of the web forming machine was 0.4Mpa, and the temperature was set at 265°C; the temperature of the precision extruder was set at 200°C; the frequency of the needle punching machine was 1000 times / min; the temperature of the hot pressing roller group was set at 85°C, the pressure of the rollers was 5MPa, and the gap between the rollers was 0.1mm. The roller speed draft ratio was 1:1.2.

[0055] The extruder, web-forming machine and spinning die were preheated, and after the temperature was stabilized, 100 wt. % high-density polyethylene M691 was added into the extruder from the barrel, spun through the spinning die and formed into a web by the web-forming machine to obtain a nonwoven fabric.

[0056] The nonwoven fabric is subjected to heat pressing and differential stretching by means of a traction roller and a secondary heat pressing roller group to form a breathable film, which is finally collected into a roll by a winding roller.

[0057] Comparative Example 2:

[0058] The temperature of the extruder was set at 230°C; the temperature of the spinning die was set at 260°C; the air pressure of the hot air inlet of the web forming machine was 0.4Mpa, and the temperature was set at 265°C; the temperature of the precision extruder was set at 200°C; the frequency of the needle punching machine was 1000 times / min; the temperature of the hot pressing roller group was set at 85°C, the pressure of the rollers was 5MPa, and the gap between the rollers was 0.1mm. The roller speed draft ratio was 1:1.2.

[0059] The extruder, web-forming machine and spinning die are preheated, and after the temperature is stabilized, 70 parts by weight of low-density polyethylene and 30 parts by weight of PEW blended materials are added into the extruder through the barrel, spun through the spinning die and formed into a web by the web-forming machine.

[0060] The nonwoven fabric is subjected to heat pressing and differential stretching by means of a traction roller and a secondary heat pressing roller group to form a breathable film, which is finally collected into a roll by a winding roller.

[0061] The material performance test results are shown in Table 1.

[0062] Table 1 Material performance test results

[0063]

[0064] From the comparison of the experimental data of the embodiment and the comparative example in Table 1, it can be found that the present invention can effectively improve the mechanical properties of the non-woven fabric when preparing the non-woven fabric.

[0065] The preparation method of the present invention is simple to operate, can realize online continuous production, can ensure higher production capacity and lower energy consumption, and is suitable for industrial production and application.

[0066] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and scope of the equivalent elements of the claims be included in the invention. Any marking in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A high-strength breathable membrane, characterized in that: It is composed of a first polymer and a second polymer. The first polymer fibers constitute the main body of the non-woven fabric, which is a non-woven fabric with randomly oriented single fibers and fiber bundles. The second polymer fibers are perpendicular to the thickness direction of the non-woven fabric, cross with the inside and surface of the first polymer fibers, and form hot-melt welding points.

2. A high-strength breathable membrane according to claim 1, characterized in that: The high-strength breathable membrane has a thickness of 0.1 to 0.3 mm, a water contact angle range of 130°-150°, an air permeability greater than 1 μm / (Pa·s), a longitudinal tensile strength greater than 6 kN / m, and a transverse tensile strength greater than 5 kN / m.

3. A high-strength breathable membrane according to claim 1, characterized in that: The first polymer fiber or fiber bundle has a fineness ranging from 1 to 30 μm, and the second polymer fiber or fiber bundle has a fineness ranging from 10 to 50 μm.

4. A high-strength breathable membrane according to claim 3, characterized in that: The first polymer fiber or fiber bundle has a fineness ranging from 5 to 20 μm, and the second polymer fiber or fiber bundle has a fineness ranging from 15 to 35 μm.

5. A high-strength breathable membrane according to claim 1, characterized in that: The first polymer is at least one of polyethylenes of different molecular weights or multi-component polyethylene PE blends, polypropylene PP, polyamide PA, and polyethylene terephthalate PET; the second polymer is at least one of acrylic hot-melt adhesive particles, EVA hot-melt adhesive particles, water-based polyurethane APU, ethylene ethyl acrylate EEA, ethylene butyl acrylate EBA, polyamide PA, and polyether sulfone PES.

6. A high-strength breathable membrane according to claim 5, characterized in that: The first polymer raw material can be in the form of strips, rods, particles or continuous filaments; the strips, rods or particles of the first polymer material are cut from continuous filaments; the second polymer material is in the form of strips, rods, particles or liquid.

7. A method for preparing a high-strength breathable membrane, characterized in that: The first step: heating the first extruder and the spinning system, and keeping the temperature for a certain period of time after the first extruder and the spinning die head reach a predetermined temperature; adding the first polymer material to the feed port of the first extruder, and the material enters the spinning die head after being melted and plasticized by the single-screw extruder, and the web forming machine is turned on, and the melt is stretched into filaments at the tip of the die head and formed into a web by the web forming machine; Step 2: preheat the second extruder and the needle punching machine diverter plate, and keep the temperature for a certain period of time after the extruder temperature reaches the predetermined temperature; add the second polymer material to the feed port of the second extruder, and melt and extrude it to the needle punching diverter plate through the hot runner. During the conveying process of the non-woven fabric in the needle punching machine, the needle punching diverter plate of the needle punching machine performs a cyclic reciprocating motion to needle the non-woven fabric, and at the same time, the diverter plate heats and keeps the second polymer warm and injects it into the inner layer of the non-woven fabric through the hollow needle; The third step: start the traction roller and hot pressing device. After the non-woven fabric is collected by the laying belt, it passes through the traction roller and enters the horizontal hot pressing state; the roller gap in the hot pressing area is set to about 5 to 30 mm, the temperature is between 100℃ and 300℃, and a certain speed difference is adjusted between the two-stage hot pressing rollers. The roller speed is 400 to 2000mm / min; after hot pressing and stretching, a breathable film with high-strength breathable performance is obtained, and finally collected by the collecting roller.

8. A method for preparing a high-strength breathable membrane according to claim 7, characterized in that: The needle punching frequency of the needle loom is 100 to 3000 times / min, the needle density is 1000 to 6000 pieces / square meter, the needle size is 3 to 15 cm, and the conveying speed of the non-woven fabric is 4 to 20 m / min.

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