Synthetic insulator having improved flexibility

Abstract

The nonwoven fabric contains 20 to 80% by weight of meltblown fibers and 20 to 80% by weight of staple fibers based on the total weight of the nonwoven fabric. The meltblown fibers include polyethylene or a mixture of polyethylene and polypropylene, and the polyethylene has a melt index (I2) of 200 to 1000 g / 10 min. The nonwoven fabric may be useful as a thermal insulator and / or an acoustic insulator having improved flexibility.

Description

Technical Field

[0001] The present disclosure generally relates to synthetic materials useful as thermal and / or acoustic insulators having improved flexibility.

Background Art

[0002] There are numerous natural and synthetic products that are useful as thermal and / or acoustic insulators. Natural down or silk is widely used for its good insulating properties as well as its lightweight and soft nature. However, in addition to being natural animal-based products, natural down feathers or silk are compressed, for example, when wet after washing, and thus lose their insulating properties. Natural down or silk may also produce an unpleasant odor, especially when wet. Finally, the cost of natural down has increased dramatically over the past few years.

[0003] Accordingly, much research has been done to develop alternative solutions that have equivalent insulating performance that can be washed and have a more competitive cost. Currently, melt-blown polypropylene mixed with polyester staple fibers is widely used as a thermal or acoustic insulator in the clothing, home, medical, and automotive industries. However, these products are not as soft as natural down feathers or silk. Accordingly, there is a need for a softer synthetic insulator that retains exemplary insulating properties.

Summary of the Invention

[0004] Disclosed is a nonwoven fabric comprising, based on the total weight of the nonwoven fabric, 20 to 80% by weight of melt-blown fibers comprising polyethylene or a mixture of polyethylene and polypropylene, and 20 to 80% by weight of staple fibers based on the total weight of the nonwoven fabric. The polyethylene has a melt index (I2) of 200 to 1000 g / 10 min.

Brief Description of the Drawings

[0005]

Figure 1

Figure 2

Figure 3

Figure 4

Mode for Carrying Out the Invention

[0006] The meltblown used in the present disclosure means that while extruding a molten material through a plurality of orifices to form filaments, the filaments are brought into contact with air or other thinning fluids to thin the filaments into fibers, and then a layer of the thinned fibers is collected.

[0007] Meltblown fibers, when used in the present disclosure, mean fibers prepared by the meltblown process.

[0008] Diameter, when used in the present disclosure with respect to fibers, means the diameter of a fiber having a circular cross-section, or in the case of a non-circular fiber, the length of the longest cross-sectional chord that can be configured across the width of the fiber.

[0009] The glass transition temperature (or T g ) of the polymer used in the present disclosure refers to the temperature at which, as the temperature rises, an amorphous polymer changes from being hard and relatively brittle or glassy to viscous or rubbery.

[0010] The polypropylene or propylene-based polymer used in the present disclosure means a polymer containing more than 50 mol% of units derived from propylene monomers. This includes propylene-based homopolymers or copolymers.

[0011] The polyethylene or ethylene-based polymer used in the present disclosure means a polymer containing more than 50 mol% of units derived from ethylene monomers. This includes ethylene-based homopolymers or copolymers.

[0012] The nonwoven fabric used in the present disclosure means a web or fabric having a structure of randomly inserted individual fibers or yarns, in contrast to a distinguishable pattern as in the case of a knitted fabric.

[0013] Staple fibers mean natural fibers or lengths cut from, for example, manufactured filaments. Staple fibers include natural and synthetic materials. Natural materials include cellulose fibers and textile fibers such as cotton and rayon. Synthetic materials include non-absorbent synthetic polymer fibers such as polyolefins, polyesters, polyacrylics, and polyamides.

[0014] Nonwoven fabric The nonwoven fabric may contain 20 to 80% by weight of meltblown fibers based on the total weight of the nonwoven fabric. All individual values and subranges of 20 to 80% by weight are disclosed and included herein. The nonwoven fabric may contain 40 to 60% by weight of meltblown fibers based on the total weight of the nonwoven fabric. The nonwoven fabric may contain 30 to 70% by weight of meltblown fibers based on the total weight of the nonwoven fabric. The nonwoven fabric may contain 50 to 70% by weight of meltblown fibers based on the total weight of the nonwoven fabric.

[0015] The staple fibers are mixed with the meltblown fibers. The nonwoven fabric may contain 20 to 80% by weight of staple fibers based on the total weight of the nonwoven fabric. All individual values and subranges of 20 to 80% by weight are disclosed and included herein. For example, the nonwoven fabric may contain 30 to 70% by weight of staple fibers based on the total weight of the nonwoven fabric. The nonwoven fabric may contain 40 to 60% by weight of staple fibers based on the total weight of the nonwoven fabric. The nonwoven fabric may contain 30 to 50% by weight of staple fibers based on the total weight of the nonwoven fabric.

[0016] The thickness of the non-woven fabric may be 1 mm to 5 mm for a basis weight of 100 grams per square meter (gsm). All individual values and sub-ranges from 1 mm to 5 mm are included and disclosed herein. The non-woven fabric may be 2 mm to 3 mm for a basis weight of 100 gsm. The non-woven fabric may have a bulk density of 20 to 100 g / l. All individual values and sub-ranges from 20 to 100 g / l are included and disclosed herein. The non-woven fabric may have a bulk density of 20 to 40 g / l or 30 to 40 g / l.

[0017] The non-woven fabric may have a basis weight of 50 to 350 gsm. All individual values and sub-ranges from 50 to 350 gsm are included and disclosed herein. For example, the non-woven fabric may have a basis weight of 50 to 100 gsm, 50 to 70 gsm, 250 to 325 gsm, or 290 to 325 gsm.

[0018] The non-woven fabric may have a basis weight of 60 to 67 gsm and a thermal resistance of 0.200 (m 2 K) / W or more. The non-woven fabric may have a basis weight of 60 to 67 gsm and a thermal resistance of 0.210 (m 2 K) / W or more. The non-woven fabric may have a basis weight of 60 to 67 gsm and a thermal resistance of 0.200 to 0.300 (m 2 K) / W. All individual values and sub-ranges are incorporated and disclosed. For example, the non-woven fabric may have a basis weight of 60 to 67 gsm and a thermal resistance of 0.200 to 0.250 (m 2 K) / W.

[0019] The non-woven fabric may have a basis weight of 300 gsm and a thermal resistance of 0.900 (m 2 K) / W or more. The non-woven fabric may have a basis weight of 300 gsm and a thermal resistance of 0.950 (m 2 K) / W or more. The non-woven fabric may have a basis weight of 300 gsm and a thermal resistance of 0.900 to 1.500 (m 2 K) / W. All individual values and sub-ranges are incorporated and disclosed. For example, the non-woven fabric may have a basis weight of 300 gsm and a thermal resistance of 0.900 to 1.000 (m 2It may have a heat resistance of K) / W.

[0020] Melt-blown fibers made from polyethylene or a mixture of polyethylene and polypropylene Melt-blown fibers can be produced by extruding a fiber-forming material through a die orifice into a gas stream, as will be described in more detail below. Typically, compared to staple fibers, melt-blown fibers are very long and have an indefinite length. Melt-blown fibers may have a diameter of less than 10 μm.

[0021] Melt-blown fibers may include polyethylene or a mixture of polyethylene and polypropylene. Common forms of polyethylene known in the art include, but are not limited to, low density polyethylene (LDPE), linear low density polyethylene (LLDPE), ultra low density polyethylene (ULDPE), very low density polyethylene (VLDPE), single-site catalyst linear low density (m-LLDPE) including both linear and substantially linear low density resins, medium density polyethylene (MDPE), and high density polyethylene (HDPE).

[0022] Additionally, as used herein, the term LDPE may also be referred to as a high-pressure ethylene polymer or highly branched polyethylene, and is defined to mean that the polymer is partially or completely homopolymerized or copolymerized in an autoclave or tubular reactor at a pressure above 14,500 psi (100 MPa) using a free radical initiator such as a peroxide (see, for example, U.S. Patent No. 4,599,392). LDPE resins typically have a density of 0.91 g / cm 3 ~0.94 g / cm3 has a density within the range of.

[0023] As used herein, the term LLDPE includes resins made using Ziegler-Natta catalyst systems, as well as resins made using single-site catalysts such as, but not limited to, bis-metallocene catalysts, phosphine imines, and geometrically constrained catalysts (sometimes referred to as "m-LLDPE"), and resins made using post-metallocene molecular catalysts such as, but not limited to, bis(biphenylphenoxy) catalysts (also referred to as polyvalent aryloxy ether catalysts). LLDPE includes linear, substantially linear, or heterogeneous ethylene copolymers or homopolymers. LLDPE contains fewer long-chain branches than LDPE and includes substantially linear ethylene polymers further defined in U.S. Pat. Nos. 5,272,236, 5,278,272, 5,582,923, and 5,733,155, homogeneous branched ethylene polymers such as those described in U.S. Pat. No. 3,645,992, heterogeneous branched ethylene polymers such as those prepared according to the process disclosed in U.S. Pat. No. 4,076,698, and blends thereof (such as those disclosed in U.S. Pat. No. 3,914,342 or U.S. Pat. No. 5,854,045). LLDPE resins can be made via gas phase, solution phase, or slurry polymerization, and any combination thereof, using any type of reactor or reactor configuration known in the art. LLDPE resins can be made via gas phase, solution phase, or slurry polymerization, and any combination thereof, using any type of reactor or reactor configuration known in the art.

[0024] Additionally, as used herein, the term HDPE generally refers to polyethylene having a density of about 0.940 g / cm 3 or greater.

[0025] Meltblown fibers may have a fiber diameter of less than 10 μm. Meltblown fibers may have a fiber diameter of less than 5 μm. Meltblown fibers may have a fiber diameter of 1 μm to 10 μm. All individual values and subranges of 1 μm to 10 μm are incorporated and disclosed. For example, meltblown fibers may have a fiber diameter of 2 to 5 μm.

[0026] Meltblown fibers may contain polyethylene or a mixture of polyethylene and polypropylene. Meltblown fibers may contain 40 to 60% by weight of polypropylene, based on the total weight of the meltblown fibers. All individual values and subranges of 40 to 60% by weight of polypropylene are incorporated and disclosed. For example, meltblown fibers may contain 45 to 55% by weight of polypropylene, based on the total weight of the meltblown fibers. Meltblown fibers may contain 50% by weight of polypropylene, based on the total weight of the meltblown fibers.

[0027] Meltblown fibers may contain 20 to 100% by weight of polyethylene, based on the total weight of the meltblown fibers. For example, meltblown fibers may contain from 20, 25, 30, 40, 45, 50, 55, 60, 75, 80, 90, 95, or 99% by weight as a lower limit to 100, 99, 95, 90, 80, 75, 60, 55, 40, 35, 30, or 25% by weight as an upper limit of polyethylene, based on the weight of the meltblown fibers.

[0028] Meltblown fibers may contain polyethylene having a melt index (I2) of 200 to 1000 g / 10 min. All individual values and subranges of 200 to 1000 g / 10 min are disclosed and incorporated herein. Meltblown fibers may contain polyethylene having a melt index (I2) of 200 to 700 g / 10 min, or 200 to 500 g / 10 min.

[0029] Staple fibers The staple fibers may be added as solids that are mechanically cut to a predetermined length. The staple fibers may have a fiber diameter of 10 μm or more. The staple fibers may have a diameter of 10 to 50 μm. All individual values and sub-ranges of 10 to 50 μm are disclosed and included herein. The staple fibers may have a diameter of 10 to 25 μm or 25 to 50 μm. The length of the staple fibers may be 30 mm to 60 mm. All lengths of 30 mm to 60 mm are included herein. The staple fibers may be 35 to 55 mm, 40 to 50 mm, or 35 to 45 mm. The thickness of the fiber can also be defined by denier. Denier defines the mass density of the fiber from which the fabric is made and indicates the fineness of the fiber. Denier is equal to the mass in grams per 9000 meters of yarn. The staple fibers generally have a denier of 3 g / 9000m (3D) or more, or 4 g / 9000m (4D) or more. The denier is typically less than 10 g / 9000m (10D).

[0030] The staple fibers may contain a synthetic polymer material. The staple fibers may contain polyethylene terephthalate, polyester, polyethylene, polypropylene, copolyester, polyamide, PAN, cellulose, or mixtures thereof. Staple fibers that can be melt-bonded to each other and / or to the melt-blown fibers may be selected. Staple fibers that cannot be melt-bonded to each other and / or to the melt-blown fibers may be selected. The staple fibers may be crimped. The crimped staple fibers may have a continuous, wavy, curly, or zigzag profile along their length. The stable fibers may have 8 to 14 crimps per inch of staple fiber.

[0031] Nonwoven additive The nonwoven fabric may contain additives that improve mechanical properties, aging properties, coloring, surface properties, or other characteristics of interest. Suitable additives include fillers, nucleating agents, charge enhancing additives, light stabilizers, curing agents, surfactants, and surface treatment agents. Those skilled in the art will be familiar with the amounts of the various additives to be added and other types that may be included.

[0032] Process for producing nonwoven fabric Melt blown fibers may be extruded through a die having orifices disposed in proximity, and thinned by a converging stream of high temperature air at high speed so that fine fibers are formed. Then, these fibers may be collected on the surface. The melt blown fibers should be continuous.

[0033] The flow stream of the thermoplastic polymer may be supplied to a manifold. Then, the flow stream may be supplied to a die. Air slots disposed on either side of the die orifices through which the thermoplastic polymer passes as it exits the die direct a uniform stream of heated air at high speed towards the extruded melt stream. The hot high speed air draws and thins the extruded thermoplastic polymer material that solidifies after traveling a short distance from the spinneret. The high speed air becomes turbulent between the spinneret and the collector surface and can mix the melt blown fibers in the air stream.

[0034] Polyethylene and polypropylene blend fibers can be produced by pre-blending two pellets and then supplying both together from separate hoppers or from the same hopper to a single extruder and spinning both together from a die.

[0035] The polymer material is supplied from a hopper and an extruder through an inlet to a meltblown die and can then flow through the die cavity. The polymer material can exit the die cavity through a row of orifices of various sizes arranged in a row across the front end of the die cavity. An air stream of high-speed heated air can thin the filaments. The orifices may include a row of larger orifices and a row of smaller orifices. As will be understood by those skilled in the art, fibers of larger diameter may be extruded from orifices of larger size, and fibers of smaller diameter may be extruded from orifices of smaller diameter.

[0036] Staple fiber filaments can be supplied from a hopper and an extruder to a large die cavity. An air stream of high-speed heated air can thin the staple fiber filaments and mix them with meltblown filaments exiting the die cavity that can be oriented perpendicular to the staple fiber die cavity. As will be apparent to those skilled in the art, the level of entanglement of the meltblown and staple fibers can be varied by adjusting the orientation of the meltblown and staple die cavities relative to each other. When the staple fibers exit the staple fiber die cavity horizontally, the meltblown fibers need to exit the meltblown die cavity vertically.

[0037] Use of the nonwoven fabric The disclosed nonwoven fabric can be used in several thermal and acoustic applications. The disclosed nonwoven fabric can be used, for example, in battery compartments, engine compartments, automobile doors and ceilings, insulation applications in railway vehicles, automobile trunks, automobile hoods, building and utility wraps, interior decoration materials for furniture, HVAC systems, and linings or fillers for jackets. The nonwoven fabric may be used as a monolithic layer. The monolithic layer may be surrounded by a cavity wall. An outer layer may be wrapped around the nonwoven fabric so that the nonwoven fabric is completely enclosed. An adhesive layer may be applied to one or more surfaces of the nonwoven fabric. A release liner may be attached to one or more adhesive layers. The adhesive layer may be pressure-sensitive, curable, or solidifiable. The adhesive layer may be composed of a binder.

[0038] Test Method Density Density is measured in accordance with ASTM D-792 and expressed in grams per cubic centimeter (g / cc).

[0039] Melt Index and Melt Flow Rate (MFR) Measure the melt index (I2) according to ASTM D-1238 at 190 °C with 2.16 kg. Report the value in g / 10 min corresponding to the grams eluted per 10 minutes. The melt flow rate is measured for polypropylene or propylene-based polymers and measured at 230 °C with 2.16 kg.

[0040] Basis Weight Cut the sample into a sample of 100 cm 2 and weigh it on a balance. Then multiply this weight by 100 to convert the measured value to grams per square meter (gsm).

[0041] Thermal Insulation Performance Thermal insulation performance is measured in accordance with GB / T11048-2018. Record the thermal resistivity, CLO value, insulation rate, and thermal conductivity.

[0042] Sound acoustic performance The sound acoustic performance is measured in the frequency range of 100 to 6300 Hz in accordance with GB / T18696.1-2004. The sound absorption coefficient is measured for both the standing wave tube method and the reverberation chamber method.

[0043] Flexibility (drapability) performance An example of the drapability test can be seen in Figure 1. A 16 cm wide sample is placed on the edge of a table, with 5 cm extending over the edge of the table. The horizontal distance (L) between the pendent end of the sample and the table is measured together with the vertical distance between the edge of the table and the end of the virtual line L from the pendent end to the table. The angle (a) between the non-woven fabric and the vertical plane of the table is calculated. A smaller angle indicates better drapability.

Examples

[0044] The following examples are provided to further illustrate the description and claims. They should not be construed as limiting the present disclosure. The raw materials used are listed in Table 1 below.

[0045]

Table 1

[0046] EMBR-1 production The experimental ethylene / alpha-olefin interpolymer melt blown fiber resin 1 (EMBR-1) is produced in a single reactor configuration using ethylene, 1-octene, and a narrow boiling range high-purity isoparaffin solvent purified with molecular sieves. Hydrogen is supplied pressurized as a high-purity grade and is not further purified. The monomer feed stream to the reactor is pressurized by a mechanical compressor to a pressure higher than the reaction pressure. The solvent and comonomer feeds are pressurized by pumps to a pressure higher than the reaction pressure. The individual catalyst components are manually batch diluted to the specified component concentrations using the purified solvent and pressurized to a pressure higher than the reaction pressure. All reaction feed streams are measured using mass flow meters and are controlled independently by a computer-automated valve control system.

[0047] The continuous solution polymerization reactor consists of a liquid-filled non-insulated isothermal circulation loop reactor that mimics a continuously stirred tank reactor (CSTR) with heat removal. Independent control of all fresh solvent, monomer, comonomer, hydrogen, and catalyst component feeds is possible. The fresh feed streams (solvent, monomer, and hydrogen) to the reactor are temperature-controlled by passing the feed streams through a heat exchanger. All additional feeds to the polymerization reactor are injected into the reactor at two locations with approximately equal reactor volumes between each injection location. The fresh feeds are controlled such that each injector receives and controls half of the mass flow of the total fresh feed.

[0048] The mass flow ratio of the feed solvent to ethylene in the first reactor is 3.8. The mass flow ratio of the feed comonomer to ethylene in the first reactor is 0.20. The mass flow ratio of the feed hydrogen to ethylene in the first reactor is 3.0×10 -4 . The temperature of the first reactor is 155 °C, the pressure of the first reactor is 34 bar, and the ethylene conversion percentage of the first reactor is 86.1.

[0049] The catalyst components are injected into the polymerization reactor through specially designed injection needles. The main catalyst component feed is computer-controlled to maintain the reactor monomer conversion at a specific target value. The co-catalyst components are supplied based on a calculated specific molar ratio to the main catalyst component. Immediately after the injection point of each reactor feed, the feed stream is mixed with the contents of the circulating polymerization reactor having static mixing elements. The contents of the reactor are continuously circulated through a heat exchanger that serves to remove most of the reaction heat, at the coolant-side temperature that serves to maintain an isothermal reaction environment at a specified temperature. The circulation around the reactor loop is provided by a pump.

[0050] The catalyst type of the first reactor is [N-(1,1-dimethylethyl)-1,1-dimethyl-1-[(1,2,3,4,5-eta)-2,3,4,5-tetramethyl-2,4-cyclopentadien-1-yl]silanaminato(2-)-kappaN][(1,2,3,4-eta)-1,3-pentadiene]-titanium. The co-catalyst-1 type of the first reactor is bis(hydrogenated tallow alkyl)methylammonium tetrakis(pentafluorophenyl)borate(1-), while the co-catalyst-2 type of the first reactor is branched, cyclic, and linear aluminoxanes, Iso-Bu Me; modified methylaluminoxane. The co-catalyst-1 to catalyst molar ratio of the first reactor is 1.2, and the co-catalyst-2 to scavenger molar ratio of the first reactor is 5.0. The residence time of the first reactor is 13.1 minutes.

[0051] The final reactor effluent enters a zone where the effluent is deactivated by the addition and reaction with a suitable reagent (water). At this same reactor outlet location, other additives are added for the stabilization of the polymer. At least a 10-fold molar ratio of (hydrating) water to active catalyst is available, and the conditions are selected to stop the polymerization in the reactor effluent. This aspect is important to ensure that the polymer material has a narrow molecular weight distribution and the compositional distribution is maintained narrow.

[0052] Following the deactivation of the catalyst and the addition of the additive, the reactor effluent enters a devolatilization system where the polymer is removed from the non-polymer stream. The isolated polymer melt is processed and pelletized according to the description provided in WO 2015 / 191066, page 6, lines 23 - 28, page 8, lines 11 - 16, and page 11, lines 3 - 25. The non-polymer stream passes through various equipment that separates most of the ethylene removed from the system. Most of the solvent and unreacted comonomer are recycled to the reactor after passing through the purification system. A small amount of solvent and comonomer are purged from the process.

[0053] Nonwoven production Nonwovens CE-1 and CE-2 are prepared on a Reicofil pilot line with a width of 0.6 m. All other nonwovens are prepared on another meltblown production line with a width of 1.6 m and a pore diameter of 0.3 mm. The air temperature is set between 240 - 270 °C depending on the melt index of the meltblown resin. Insulation cotton is produced on a 1.6 m wide meltblown machine. Polyethylene terephthalate staple fibers are incorporated through a side feed unit at a rate of 15 kg / hour. The extruder temperature is set at 170 °C in the first zone, 180 °C in the second zone, 200 °C in the third zone, 210 °C in the fourth zone, and 220 °C in the fifth zone from the hopper to the nozzle. For polypropylene, the melt pump temperature is set at 225 °C, and for polyethylene, the melt pump temperature is set at 220 °C. The hot air temperature is set at 230 °C for polypropylene and 220 °C for polyethylene.

[0054] Table 2 lists non-woven fabrics that do not contain polyethylene terephthalate. Both CE-1 (Comparative Example 1) and CE-2 (Comparative Example 2) are pure melt-blown non-woven fabrics that do not contain polyethylene terephthalate staple fibers. These samples were found to be not bulky enough as insulating cotton. This lack of bulk results in inefficient sound and heat absorption. Comparative Example 2 used a low melt index polyethylene product and had to be processed at 50% production rate when compared to CE-1. This resulted in a larger fiber size.

[0055]

Table 2

[0056] Table 3 shows the results for the comparative samples and the samples of the present invention. CE-3 and CE-5 (Comparative Examples 3 and 5) are examples of prior art solutions using polypropylene melt-blown with polyethylene terephthalate staple fibers having different basis weights. CE-4 (Comparative Example 4) is a commercially available silk quilt used as a reference. IE-1 and IE-3 (Inventive Examples 1 and 3 of the present invention) are examples of the present invention using polyethylene melt-blown instead of polypropylene having different basis weights so as to achieve improved comfort and flexibility. IE-2 and IE-4 (Inventive Examples 2 and 4 of the present invention) are another pair of examples of the present invention having different basis weights where both polyethylene and polypropylene melt-blown are used so as to balance strength and flexibility.

[0057]

Table 3

[0058] Table 4 shows the angles calculated in the above-mentioned drapeability test. The polyethylene sample (IE-1) had the best drapeability, while the polypropylene (CE-3) had the worst drapeability. The polyethylene polypropylene blend (IE-2) was between these two extremes. CE-4 had drapeability comparable to that of IE-1, but IE-1 had better thermal insulation performance, as shown in the next section.

[0059]

Table 4

[0060] The thermal insulation data is shown in Table 5. Along with a lower thermal conductivity, a higher thermal resistivity, CLO value, and insulation rate indicate better thermal insulation. The examples of the present invention (IE-1 / IE-2) showed better thermal insulation performance than CE-4, even though CE-4 had a higher basis weight, which demonstrates the advantage of better insulation efficiency for the examples of the present invention listed herein. CE-3 had higher insulation performance than IE-1 / IE-2 because it had a higher basis weight (along with much higher rigidity, as described above). Comparing the examples of IE-3 / IE-4 / CE-5 with the same basis weight (300 gsm), the examples of the present invention (IE-3 / IE-4) showed better or equivalent thermal insulation performance when compared to the comparative example (CE-5).

[0061]

Table 5

[0062] The acoustic performance is shown in Figures 2, 3, and 4. As seen in Figure 2, the acoustic coefficients of IE-1 and IE-2 were comparable to those of CE-3 at 100 - 10000 Hz when measured using the GB / T 18696.1-2004 standard. This is despite the basis weight of IE-1 and IE-2 being approximately 30 gsm less than that of CE-3.

[0063] Figure 3 shows that when IE-3 is compared with CE-5 using the standing wave method at the same basis weight, IE-3 has a higher sound absorption coefficient than CE-5 in the range of 100 to 7000 Hz, indicating that such advantages exist in the low frequency range. Figure 4 shows that the same applies to IE-3 when compared with CE-5 when the sound absorption coefficient is measured according to the reverberation room method.

Claims

1. A nonwoven fabric, a. 20 to 80 wt. % meltblown fibers, based on the total weight of the nonwoven fabric, wherein the meltblown fibers comprise polyethylene or a mixture of polyethylene and polypropylene, and the polyethylene has a melt index (I) of 200 to 1000 g / 10 min. ２ ) meltblown fibers; b) 20 to 80 weight percent staple fibers based on the total weight of the nonwoven fabric.

2. a. 30 to 70 weight percent meltblown fibers, based on the total weight of the nonwoven fabric; b. 30 to 70 weight percent staple fibers, based on the total weight of the nonwoven fabric.

3. a. 40 to 60 weight percent meltblown fibers, based on the total weight of the nonwoven fabric; b. 40 to 60 weight percent staple fibers, based on the total weight of the nonwoven fabric.

4. 4. The nonwoven fabric of claim 1, wherein the staple fibers comprise polyester, polypropylene, PAN, polyamide, cellulose, or a mixture thereof.

5. a. 50 to 70 weight percent meltblown fibers, based on the total weight of the nonwoven fabric, the meltblown fibers comprising 40 to 60 weight percent polyethylene and 40 to 60 weight percent polypropylene, based on the total weight of the meltblown fibers; b. 30 to 50 weight percent staple fibers, based on the total weight of the nonwoven fabric.

6. The thermal resistance of the nonwoven fabric is 0.200 (m ２ K) / W or 0.900 (m at a basis weight of 300 gsm ２ 6. The nonwoven fabric according to any one of claims 1 to 3 and 5, wherein the tensile strength is greater than 1 / 2 K / W.

7. 6. The nonwoven fabric of any one of claims 1 to 3 and 5, wherein the meltblown fibers have a fiber diameter of less than 10 μm.

8. 6. The nonwoven fabric according to any one of claims 1 to 3 and 5, wherein the staple fibers have a fiber diameter of 10 to 50 μm.

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