Synthetic insulation material with improved flexibility

Abstract

The present invention provides a nonwoven comprising from 20% to 80% by weight of meltblown fibers and from 20% to 80% by weight of staple fibers, based on the total weight of the nonwoven. The melt-blown fibers comprise polyethylene, or a mixture of polyethylene and polypropylene, wherein the polyethylene has a melt index (I2) between 200 g / 10 min and 1000 g / 10 min. The nonwoven can be used as a thermal and / or acoustic insulation material with improved flexibility.

Description

Technical Field

[0001] The present disclosure generally relates to composite materials useful as thermal and / or acoustic insulation materials having improved softness. Background Art

[0002] There are many natural and synthetic products that can be used as thermal and / or acoustic insulation. Natural down or silk is widely used due to its light weight and soft nature as well as its good insulating properties. However, as a natural animal-based product, once natural down or silk becomes wet, for example after washing, it becomes compacted and loses its insulating properties. Natural down or silk can also produce an unpleasant odor, especially when wet. Finally, the cost of natural down has increased significantly over the past few years.

[0003] Therefore, a great deal of research has been conducted to develop alternative solutions that have comparable insulating properties, can be washed, and have more competitive costs. Currently, meltblown polypropylene mixed with polyester staple fibers is widely used in the apparel, home, healthcare, and automotive industries as thermal or acoustic insulation. However, these products are not as soft as natural down or silk. Therefore, there is a need for softer synthetic insulation materials that maintain the exemplary insulating properties. Summary of the invention

[0004] A nonwoven is disclosed, the nonwoven comprising 20 wt % to 80 wt % of meltblown fibers comprising a mixture of polyethylene or polyethylene and polypropylene, based on the total weight of the nonwoven, and 20 wt % to 80 wt % of staple fibers, based on the total weight of the nonwoven. The polyethylene has a melt index (MI) between 200 g / 10 min and 1000 g / 10 min. 2 ). BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1 Schematic depiction of the drape test.

[0006] Figure 2 The sound absorption coefficients of CE-3, IE-1 and IE-2 at different frequencies obtained by the standing wave method are shown.

[0007] Figure 3 The sound absorption coefficients of CE-5 and IE-3 at different frequencies obtained by the standing wave method are shown.

[0008] Figure 4 The sound absorption coefficients of CE-5 and IE-3 at different frequencies obtained by the reverberation chamber method are shown. DETAILED DESCRIPTION

[0009] As used in this disclosure, meltblowing means formed by extruding molten material through a plurality of orifices to form filaments while contacting the filaments with air or other attenuating fluid to attenuate the filaments into fibers, and thereafter collecting a layer of attenuated fibers.

[0010] As used in this disclosure, meltblown fibers refer to fibers produced by a meltblowing process.

[0011] When used with respect to fibers in this disclosure, diameter 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 constructed across the width of the fiber.

[0012] As used in this disclosure, the glass transition temperature (or T g ) is the temperature at which an amorphous polymer changes from a hard and relatively brittle or glassy state to a viscous or rubbery state as the temperature is increased.

[0013] As used in this disclosure, polypropylene or propylene-based polymer means a polymer comprising greater than 50% by mole of units derived from propylene monomers. This includes propylene-based homopolymers or copolymers.

[0014] As used in this disclosure, polyethylene or ethylene-based polymer means a polymer comprising greater than 50% by mole of units derived from ethylene monomers. This includes ethylene-based homopolymers or copolymers.

[0015] As used in this disclosure, nonwoven means a web or fabric having a structure of individual fibers or threads that are randomly inserted rather than in an identifiable pattern as in a knitted fabric.

[0016] Staple fibers refer to natural fibers or lengths cut from, for example, manufactured filaments. Staple fibers include natural materials 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.

[0017] Nonwovens

[0018] The nonwoven can comprise 20 wt % to 80 wt % of meltblown fibers based on the total weight of the nonwoven. All individual values ​​and subranges of 20 wt % to 80 wt % are disclosed and included herein. The nonwoven can comprise 40 wt % to 60 wt % of meltblown fibers based on the total weight of the nonwoven. The nonwoven can comprise 30 wt % to 70 wt % of meltblown fibers based on the total weight of the nonwoven. The nonwoven can comprise 50 wt % to 70 wt % of meltblown fibers based on the total weight of the nonwoven.

[0019] The staple fibers are intertwined with the meltblown fibers. The nonwoven can include 20% to 80% staple fibers based on the total weight of the nonwoven. All individual values ​​and subranges of 20% to 80% by weight are disclosed and included herein. For example, the nonwoven can include 30% to 70% staple fibers based on the total weight of the nonwoven. The nonwoven can include 40% to 60% staple fibers based on the total weight of the nonwoven. The nonwoven can include 30% to 50% staple fibers based on the total weight of the nonwoven.

[0020] For a basis weight of 100 grams per square meter (gsm), the thickness of the nonwoven can be between 1mm and 5mm. All individual values ​​and subranges of 1mm to 5mm are included and disclosed. For a basis weight of 100gsm, the nonwoven can be 2mm to 3mm. The nonwoven can have a bulk density of 20g / l to 100g / l. All individual values ​​and subranges of 20g / l to 100g / l are included and disclosed. The nonwoven can have a bulk density of 20g / l to 40g / l or 30g / l to 40g / l.

[0021] The nonwoven can have a basis weight of 50 gsm to 350 gsm. All individual values ​​and subranges of 50 gsm to 350 gsm are included and disclosed. For example, the nonwoven can have a basis weight between 50 gsm to 100 gsm, 50 gsm to 70 gsm, 250 gsm to 325 gsm, or 290 gsm to 325 gsm.

[0022] The nonwoven may have a basis weight of greater than or equal to 0.200 (m 2 The nonwoven fabric may have a thermal resistance of greater than or equal to 0.210 (m K) / W at a basis weight between 60 gsm and 67 gsm. 2 The nonwoven fabric may have a thermal resistance of 0.200 (m 2 K) / W to 0.300(m 2 All individual values ​​and subranges are included and disclosed. For example, a nonwoven may have a thermal resistance of 0.200 (m2) at a basis weight between 60 gsm and 67 gsm. 2 K) / W to 0.250(m 2 K) / W thermal resistance.

[0023] The nonwoven may have a basis weight of greater than or equal to 0.900 (m 2 The nonwoven fabric may have a thermal resistance of greater than or equal to 0.950 (m K) / W at a basis weight of 300 gsm. 2The nonwoven fabric may have a thermal resistance of 0.900 (m K) / W at a basis weight of 300 gsm. 2 K) / W to 1.500(m 2 K) / W thermal resistance. All individual values ​​and subranges are included and disclosed. For example, a nonwoven at a basis weight of 300 gsm may have a thermal resistance of 0.900 (m 2 K) / W to 1.000(m 2 K) / W thermal resistance.

[0024] Meltblown fibers made from polyethylene or a blend of polyethylene and polypropylene

[0025] Meltblown fibers can be produced by extruding a fiber-forming material through a die orifice into a gas stream, as described in more detail below. Typically, meltblown fibers are very long and have an indefinite length when compared to staple fibers. Meltblown fibers may have a diameter of less than 10 μm.

[0026] The meltblown fibers may comprise 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 catalyzed linear low density, including linear and substantially linear low density resins (m-LLDPE); medium density polyethylene (MDPE); and high density polyethylene (HDPE).

[0027] Additionally, as used herein, the term LDPE may also be referred to as high pressure ethylene polymer or highly branched polyethylene, and is defined to mean a polymer that 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, e.g., U.S. Pat. No. 4,599,392). LDPE resins typically have a molecular weight of 0.91 g / cm 3 Up to 0.94g / cm 3 density within the range of .

[0028] As used herein, the term LLDPE may include resins made using a Ziegler-Natta catalyst system, as well as resins made using single-site catalysts, including but not limited to bis-metallocene catalysts (sometimes referred to as m-LLDPE), phosphinimines, and constrained geometry catalysts; and resins made using post-metallocene, molecular catalysts, including but not limited to bis(biphenylphenoxy) catalysts (also referred to as polyvalent aryloxyether catalysts). LLDPE includes linear, substantially linear, or heterogeneous ethylene-based copolymers or homopolymers. LLDPE contains less long chain branching than LDPE, and includes substantially linear ethylene polymers (which are further defined in U.S. Pat. Nos. 5,272,236; 5,278,272; 5,582,923; and 5,733,155); homogeneously branched ethylene polymers (such as those described in U.S. Pat. No. 3,645,992); heterogeneously 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 may be prepared 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 may be prepared via gas phase, solution phase, or slurry polymerization, and any combination thereof, using any type of reactor or reactor configuration known in the art.

[0029] Additionally, as used herein, the term HDPE refers to a polyethylene having a hardness of about 0.940 g / cm 3 or higher density polyethylenes, which are usually prepared using Ziegler-Natta catalysts, chromium catalysts or even metallocene catalysts.

[0030] The meltblown fibers may have a fiber diameter of less than 10 μm. The meltblown fibers may have a fiber diameter of less than 5 μm. The meltblown fibers may have a fiber diameter of 1 μm to 10 μm. All individual values ​​and subranges from 1 μm to 10 μm are included and disclosed. For example, the meltblown fibers may have a fiber diameter of 2 μm to 5 μm.

[0031] The meltblown fibers may comprise polyethylene or a mixture of polyethylene and polypropylene. The meltblown fibers may comprise 40% to 60% by weight polypropylene, based on the total weight of the meltblown fibers. All individual values ​​and subranges from 40% to 60% by weight polypropylene are included and disclosed. For example, the meltblown fibers may comprise 45% to 55% by weight polypropylene, based on the total weight of the meltblown fibers. The meltblown fibers may comprise 50% by weight polypropylene, based on the total weight of the meltblown fibers.

[0032] The meltblown fibers may comprise polyethylene in an amount of 20% to 100% by weight based on the total weight of the meltblown fibers. For example, the meltblown fibers may comprise polyethylene in an amount of 20%, 25%, 30%, 40%, 45%, 50%, 55%, 60%, 75%, 80%, 90%, 95%, or 99% to an amount of 100%, 99%, 95%, 90%, 80%, 75%, 60%, 55%, 40%, 35%, 30%, or 25% by weight based on the weight of the meltblown fibers.

[0033] Meltblown fibers may include a melt index (I 2 ) can be polyethylene between 200 g / 10 min and 1000 g / 10 min. All individual values ​​and subranges from 200 g / 10 min to 1000 g / 10 min are disclosed and included herein. The meltblown fiber may comprise a melt index (I 2 ) Polyethylene between 200 g / 10 min to 700 g / 10 min or 200 g / 10 min to 500 g / 10 min.

[0034] Short Fiber

[0035] Staple fibers can be added as solids that have been cut into predetermined lengths by a machine. Staple fibers can have a fiber diameter equal to or greater than 10 μm. Staple fibers can have a diameter between 10 μm and 50 μm. All individual values ​​and subranges of 10 μm to 50 μm are disclosed and included herein. Staple fibers can have a diameter between 10 μm and 25 μm or between 25 μm and 50 μm. The length of the staple fibers can be between 30 mm and 60 mm. All lengths between 30 mm and 60 mm are included herein. Staple fibers can be between 35 mm and 55 mm, between 40 mm and 50 mm, or between 35 mm and 45 mm. Fiber thickness can also be defined by denier. Denier defines the mass density of the fibers from which the fabric is made and indicates the fineness of the fibers. Denier is equal to the mass (in grams) of every 9,000 meters of thread. Staple fibers generally have a denier equal to or greater than 3 g / 9,000 m (3D), or equal to or greater than 4 g / 9,000 m (4D). Denier is generally less than 10 g / 9,000 m (10D).

[0036] The staple fibers may include synthetic polymer materials. The staple fibers may include polyethylene terephthalate, polyester, polyethylene, polypropylene, copolyester, polyamide, PAN, cellulose or mixtures thereof. Staple fibers that can be melt bonded to each other and / or melt bonded to meltblown fibers may be selected. Staple fibers that cannot be melt bonded to each other and / or melt bonded to meltblown fibers may be selected. Staple fibers may be curled. Curled staple fibers may have a continuous, wavy, curled or thorny profile along their length. Stabilizing fibers may have 8 to 14 curls per inch of staple fibers.

[0037] Nonwoven Additives

[0038] The nonwoven fabric may contain additives that improve mechanical properties, aging characteristics, coloring, surface properties, or other features of interest. Suitable additives include fillers, nucleating agents, charge enhancement additives, light stabilizers, hardeners, surfactants, and surface treatment agents. Those skilled in the art will be familiar with the amounts of various additives to be added and other types that may be included.

[0039] Method for producing nonwoven fabrics

[0040] Meltblown fibers can be extruded through a die having closely spaced orifices and attenuated by converging streams of high velocity hot air to form fine fibers. The fibers can then be collected on a surface. The meltblown fibers should be continuous.

[0041] The flow stream of thermoplastic polymer can be fed into the manifold. The flow stream can then be fed into the die. Air slots arranged on either side of the die orifice through which the thermoplastic polymer leaves the die guide uniformly heated air to the extruded melt stream at high speed. The hot high-speed air stretches and thins the extruded thermoplastic polymer material, which solidifies after traveling a short distance from the spinneret. The high-speed air can become turbulent between the spinneret and the collector surface, thereby causing the meltblown fibers in the air stream to mix.

[0042] Fibers of a blend of polyethylene and polypropylene can be produced by pre-blending the two pellets and then feeding them together into an extruder from separate hoppers or from the same hopper and spinning the two pellets together from a die.

[0043] The polymer material can be fed from a hopper and an extruder through an inlet to a meltblowing die head and then flow through a die cavity. The polymer material can leave the die cavity through a row of larger and smaller sized orifices that are arranged in a row at the front end of the die cavity. The airborne flow of the high-speed heated air can make the filaments thinner. The orifice can include a row of larger and smaller orifices. As will be understood by those skilled in the art, fibers of larger diameter can be extruded from larger sized orifices, while fibers of smaller diameter can be extruded from smaller diameter orifices.

[0044] Staple fiber filaments can be fed from a hopper and an extruder to a large die cavity. The airborne stream of high-speed heated air can thin the staple fiber filaments and mix the staple fiber filaments with the meltblown filaments leaving the die cavity, which can be oriented perpendicular to the staple fiber die cavity. It is obvious to those skilled in the art that the level of entanglement of the meltblown fibers and the stabilizing fibers can be changed by adjusting the orientation of the meltblown die cavity and the stabilizing die cavity to each other. If the staple fibers leave the staple fiber die cavity in a horizontal manner, the meltblown fibers will need to leave the meltblown die cavity in a vertical manner.

[0045] Uses of nonwovens

[0046] The disclosed nonwoven can be used in several thermal applications and acoustic applications. The disclosed nonwoven can be used in, for example, battery compartments, engine compartments, automotive doors and ceilings, rail vehicle insulation applications, automotive trunks, automotive hoods, building and utility equipment packaging, furniture interior decoration, HVAC systems and jacket linings or fillers. The nonwoven can be used as a single layer. The single layer can be surrounded by a cavity wall. The outer layer can be wrapped around the nonwoven so that the nonwoven is completely encapsulated. An adhesive layer can be applied to one or more surfaces of the nonwoven. A release liner can be attached to one or more adhesive layers. The adhesive layer can be pressure-sensitive, curable or hardenable. The adhesive layer can be composed of a binder.

[0047] Test Method

[0048] density

[0049] Density is measured according to ASTM D-792 and is reported in grams per cubic centimeter (g / cc).

[0050] Melt Index and Melt Flow Rate (MFR)

[0051] Melt index (I 2 ) is measured according to ASTM D-1238 at 190°C under 2.16 kg. Values ​​are reported in g / 10 min, which corresponds to the number of grams eluted per 10 minutes. The melt flow rate of polypropylene or propylene-based polymers is measured and is measured at 230°C under 2.16 kg.

[0052] Basis Weight

[0053] Cut the sample into 100 cm 2 The sample is weighed on a balance. The weight is then multiplied by 100 to convert the measurement to grams per square meter (gsm).

[0054] Thermal insulation performance

[0055] Measure thermal insulation performance according to GB / T11048-2018. Record thermal resistivity, CLO value, insulation rate and thermal conductivity.

[0056] Sound Acoustic Performance

[0057] The acoustic performance of sound was measured according to GB / T18696.1-2004, with a frequency range of 100Hz to 6300Hz. The sound absorption coefficient was measured according to both the standing wave tube method and the reverberation chamber method.

[0058] Softness (Drapability) Performance

[0059] Examples of drape testing can be found in Figure 1 The sample of 16cm width is placed on the edge of the table, extending 5cm on the edge of the table. The horizontal distance (L) between the overhanging end of the sample and the table and the vertical distance between the edge of the table and the end of the imaginary line L from the overhanging edge to the table are measured. The angle (a) between the nonwoven and the vertical surface of the table is calculated. Smaller angles indicate better drapability.

[0060] Example

[0061] The following examples are provided to further illustrate the specification and claims. They should not be construed as limiting the present disclosure. The raw materials used are listed in Table 1 below.

[0062] Table 1: Materials

[0063]

[0064] EMBR-1 production

[0065] Experimental Ethylene / α-olefin interpolymer meltblown fiber resin 1 (EMBR-1) was produced in a single reactor configuration with ethylene, 1-octene, and a narrow boiling range high purity isoparaffin solvent purified with molecular sieves. Hydrogen was supplied under pressure in high purity grades without further purification. The reactor monomer feed stream was pressurized to greater than the reaction pressure via a mechanical compressor. The solvent and comonomer feeds were pressurized to greater than the reaction pressure via a pump. Each catalyst component was manually diluted in batches with purified solvent to the specified component concentration and pressurized to greater than the reaction pressure. All reaction feed streams were measured with mass flow meters and independently controlled with a computer automated valve control system.

[0066] The continuous solution polymerization reactor is composed of a non-adiabatic isothermal circulating loop reactor full of liquid that simulates a continuous stirred tank reactor (CSTR) with heat removal. All fresh solvents, monomers, comonomers, hydrogen and catalyst component feeds can be controlled independently. The temperature of the total fresh feed stream (solvent, monomer, comonomer and hydrogen) entering the reactor is controlled by making the feed stream pass through a heat exchanger. The total fresh feed to the polymerization reactor is injected into the reactor at two locations, wherein the reactor volume between each injection position is roughly equal. The fresh feed is controlled by receiving half of the total fresh feed mass flow with each injector.

[0067] The mass flow ratio of the feed solvent to ethylene in the first reactor was 3.8. The mass flow ratio of the feed comonomer to ethylene in the first reactor was 0.20. The mass flow ratio of the feed hydrogen to ethylene in the first reactor was 3.0×10 -4 The temperature of the first reactor was 155° C., and the pressure of the first reactor was 34 bar, and the ethylene conversion percentage of the first reactor was 86.1.

[0068] The catalyst components are injected into the polymerization reactor through a specially designed injection plug. The computer controls the main catalyst component feed to maintain the reactor monomer conversion under a specified target. The co-catalyst component is fed based on the calculated specified molar ratio with the main catalyst component. Immediately after each reactor feed injection position, the feed stream is mixed with the circulating polymerization reactor contents with a static mixing element. The contents of the reactor are continuously circulated through a heat exchanger, which is responsible for removing a large amount of reaction heat, and the temperature of the coolant side is responsible for maintaining the isothermal reaction environment at a specified temperature. The circulation around the reactor loop is provided by a pump.

[0069] The catalyst type of the first reactor was [N-(1,1-dimethylethyl)-1,1-dimethyl-1-[(1,2,3,4,5-η)-2,3,4,5-tetramethyl-2,4-cyclopentadien-1-yl]silanamido(2-)-.κ.N][(1,2,3,4-η)-1,3-pentadienyl]-titanium. The cocatalyst-1 type of the first reactor was bis(hydrogenated tallow alkyl)methylammonium tetra(pentafluorophenyl)borate (1-), and the cocatalyst-2 type of the first reactor was aluminoxane, iso-Bu Me, branched, cyclic and linear; modified methylaluminoxane. The molar ratio of the cocatalyst-1 to the catalyst of the first reactor was 1.2, and the molar ratio of the cocatalyst-2 to the scavenger of the first reactor was 5.0. The residence time of the first reactor was 13.1 minutes.

[0070] The final reactor effluent enters a zone where it is deactivated by adding and reacting with a suitable reagent (water). At this same reactor outlet location, other additives are added for polymer stabilization. Conditions are selected so that at least a 10-fold molar ratio of (hydration) water to active catalyst can be used to stop polymerization in the reactor effluent. This aspect is very important in order to ensure that the polymer material has a narrow molecular weight distribution and maintains a narrow composition distribution.

[0071] After catalyst deactivation and addition of additives, the reactor effluent enters a devolatilization system where polymer is removed from the non-polymer stream. The separated polymer melt is processed and pelletized according to the description provided in WO2015 / 191066, pages 6, 11.23-28, 8, 11.11-16, and 11.3-25. The non-polymer stream passes through various devices that separate most of the ethylene removed from the system. Most of the solvent and unreacted comonomer are recycled back to the reactor after passing through a purification system. Small amounts of solvent and comonomer are removed from the process.

[0072] Nonwovens production

[0073] Nonwovens CE-1 and CE-2 were prepared in a reicofil pilot line with a width of 0.6 m. All other nonwovens were prepared in another meltblown line with a width of 1.6 m and a pore size of 0.3 mm. The air temperature was set to 240°C-270°C according to the melt index of the meltblown resin. Insulation wool was produced in a 1.6 m wide meltblown machine. Polyethylene terephthalate staple fibers were introduced through a side feed unit at a rate of 15 kg / hour. From the hopper to the nozzle, the extruder temperature was set to 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. For polypropylene, the melt pump temperature was set to 225°C, and for polyethylene, the melt pump temperature was set to 220°C. The hot air temperature was set to 230°C for polypropylene and 220°C for polyethylene.

[0074] Table 2 lists nonwovens without polyethylene terephthalate. Both CE-1 (Comparative Example 1) and CE-2 (Comparative Example 2) are pure meltblown nonwovens without polyethylene terephthalate staple fibers. These samples proved to be insufficient in volume for insulating cotton. This lack of volume results in ineffective sound and heat absorption. Comparative Example 2 uses a low melt index polyethylene product and must be processed at 50% output when compared to CE-1. This results in larger fiber size.

[0075] Table 2: Samples without PET

[0076]

[0077] Table 3 shows the results of the comparative samples and the inventive samples. CE-3 and CE-5 (Comparative Example 3 and Comparative Example 5) are embodiments of prior art solutions using polypropylene meltblown together 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 Example 1 and Inventive Example 3) are inventive embodiments, in which meltblown polyethylene is used instead of polypropylene having different basis weights, thereby achieving improved comfort and softness. IE-2 and IE-4 (Inventive Example 2 and Inventive Example 4) are another pair of inventive embodiments with different basis weights, in which both polyethylene and meltblown polypropylene are used, thereby balancing strength and softness.

[0078] Table 3: Examples of the present invention and comparative examples

[0079] sample EMBR-1wt% PP MB weight% PET staple fiber weight% Basis Weight CE-3 0 70 30 93 CE-4 Commercially available silk quilt 106 CE-5 0 70 30 300 IE-1 70 0 30 63 IE-2 35 35 30 67 IE-3 70 0 30 300 IE-4 35 35 30 300

[0080] Table 4 shows the angles calculated in the above drape tests. The polyethylene sample (IE-1) has the best drape, while the polypropylene (CE-3) has the worst drape. The polyethylene polypropylene blend (IE-2) is between these two extremes. Although CE-4 has comparable drape to IE-1, IE-1 has better insulation properties, as shown in the next section.

[0081] Table 4: Drapability test

[0082] sample IE-1 IE-2 CE-3 CE-4 Overhang Angle 45° 67° 74° 48°

[0083] The insulation data is shown in Table 5. Higher thermal resistivity, CLO values, and insulation ratios and lower thermal conductivity indicate better insulation. Even though CE-4 has a higher basis weight, the inventive examples (IE-1 / IE-2) show better insulation performance than Comparative Example 4 (CE-4), which shows the advantage of better insulation efficiency for the inventive examples listed here. CE-3 has higher insulation performance than IE-1 / IE-2 because it has a higher basis weight (and much higher stiffness as discussed previously). When we compare the examples of IE-3 / IE-4 / CE-5 with the same basis weight (300 gsm), the inventive examples (IE-3 / IE-4) show better or comparable insulation performance when compared to the comparative example (CE-5).

[0084] Table 5: Thermal insulation properties of samples in the present invention

[0085] GB / T11048 Performance IE-1 IE-2 IE-3 IE-4 CE-3 CE-4 CE-5 Basis weight gsm 63 67 300 300 93 106 300 <![CDATA[Thermal resistance (m 2 k) / W]]> 0.207 0.221 0.952 0.910 0.269 0.145 0.914 CLO Value 1.335 1.426 6.140 5.870 1.735 0.935 5.900 Insulation rate % 75.4 76.6 91.5 91.2 79.9 68.9 91.2

[0086] Sound acoustic performance Figure 2 , Figure 3 and Figure 4 As shown in Figure 2 It can be seen that the sound acoustic coefficients of IE-1 and IE-2 are comparable to those of CE-3 from 100 Hz to 10,000 Hz when measured using the GB / T 18696.1-2004 standard, even though the basis weights of IE-1 and IE-2 are approximately 30 gsm lower than that of CE-3.

[0087] Figure 3 It is shown 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 from 100 Hz to 7000 Hz, and such advantage exists in the low frequency range. Figure 4 It is shown that when the sound absorption coefficient is measured according to the reverberation room method, the IE-3 also performs well when compared to the CE-5.

Claims

1. A nonwoven fabric, comprising: a. 20 wt % to 80 wt % of meltblown fibers, based on the total weight of the nonwoven, wherein the meltblown fibers comprise polyethylene, or a mixture of polyethylene and polypropylene, wherein the polyethylene has a melt index (I2) between 200 g / 10 min and 1000 g / 10 min, and b. 20 to 80 wt. % staple fibers, based on the total weight of the nonwoven.

2. The nonwoven fabric according to claim 1, comprising: a. 30 wt % to 70 wt % of meltblown fibers based on the total weight of the nonwoven, and b. 30 to 70 wt. % of staple fibers, based on the total weight of the nonwoven.

3. The nonwoven fabric according to claim 1, comprising: a. 40 wt % to 60 wt % of meltblown fibers based on the total weight of the nonwoven, and b. 40 to 60 wt. % staple fibers, based on the total weight of the nonwoven.

4. A nonwoven according to any preceding claim, wherein the staple fibers comprise polyester, polypropylene, PAN, polyamide, cellulose or mixtures thereof.

5. The nonwoven fabric according to claim 1, comprising: a. 50 wt % to 70 wt % of meltblown fibers, based on the total weight of the nonwoven, wherein the meltblown fibers comprise 40 wt % to 60 wt % of polyethylene and 40 wt % to 60 wt % of polypropylene, based on the total weight of the meltblown fibers, and b. 30 to 50 wt. % staple fibers, based on the total weight of the nonwoven.

6. A nonwoven according to any preceding claim, wherein the thermal resistance of the nonwoven is greater than 0.200 (m2) at a basis weight between 60 gsm and 67 gsm. 2 K) / W, or greater than 0.900(m K) / W at a basis weight of 300 gsm 2 K) / W.

7. The nonwoven according to any preceding claim, wherein the meltblown fibers have a fiber diameter of less than 10 μm. 8 . The nonwoven fabric according to claim 1 , wherein the short fibers have a fiber diameter of 10 μm to 50 μm.

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