EP4551746A1

EP4551746A1 - Synthethic insulation with improved softness

Info

Publication number: EP4551746A1
Application number: EP22952485.5A
Authority: EP
Inventors: Haiyang Yu; Jingya Li; Xin Huang
Original assignee: Dow Global Technologies LLC
Current assignee: Dow Global Technologies LLC
Priority date: 2022-07-29
Filing date: 2022-07-29
Publication date: 2025-05-14
Also published as: WO2024021038A1; EP4551746A4; KR20250041142A; CN119487249A; JP2025524791A; WO2024021038A8

Abstract

A nonwoven includes 20 to 80 wt. % meltblown fiber and 20 to 80 wt. % staple fiber, based on the total weight of the nonwoven. The meltblown fiber includes polyethylene, or a mixture of polyethylene and polypropylene, wherein the polyethylene has a melt index (I ₂) between 200 to 1000 g/10 min. The nonwoven can be useful as thermal and/or acoustic insulation with improved softness.

Description

SYNTHETHIC INSULATION WITH IMPROVED SOFTNESS

TECHNICAL FIELD

The present disclosure generally relates to synthetic material useful as thermal and/or acoustic insulation with improved softness.

BACKGROUND

A multitude of natural and synthetic products exist that are useful as thermal and/or acoustic insulation. Natural down or silk has been widely used due to its lightweight and soft nature along with its good insulation properties. However, along with being a natural animal-based product, natural down feather or silk will compact once it becomes wet, after washing for example, and thus lose its insulating properties. Natural down or silk can also generate an unpleasant odor especially when wet. Finally, the cost of natural down has increased dramatically over the past several years.
Thus, significant research has gone into developing alternative solutions with comparable insulation performance capable of being washed and with a more competitive cost. Currently, meltblown polypropylene mixed with polyester staple fiber is widely used in the apparel, household, medical care, and auto industries as thermal or acoustic insulation. However, these products are not as soft as natural down feathers or silk. Thus, a need exists for softer synthetic insulation that retains exemplary insulation properties.
SUMMARY OF DISCLOSURE
A nonwoven comprising 20 to 80 wt. %, based on the total weight of the nonwoven, meltblown fiber comprising polyethylene, or a mixture of polyethylene and polypropylene, and 20 to 80 wt. %, based on the total weight of the nonwoven, staple fiber is disclosed. The polyethylene has a melt index (I ₂) between 200 to 1000 g/10min.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 schematically depicts the drapability test.
Figure 2 shows the sound absorbing coefficient at different frequencies of CE-3, IE-1, and IE-2 by the standing wave method.
Figure 3 shows the sound absorbing coefficient at different frequencies of CE-5 and IE-3 by the standing wave method.
Figure 4 shows the sound absorbing coefficient at different frequencies of CE-5 and IE-3 by the reverberation chamber method.

DETAILED DESCRIPTION

Meltblown, as used in this disclosure, means formed by extruding a 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.
Meltblown fibers, as used in this disclosure, means fibers prepared by the meltblown process.
Diameter, when used with respect to a fiber in this disclosure, means the diameter of a fiber having a circular cross section, or, in the case of a noncircular fiber, the length of the longest cross-sectional chord that may be constructed across the width of the fiber.
Glass transition temperature (or T _g) of a polymer, as used in this disclosure, refers to a temperature at which the amorphous polymer changes from hard and relatively brittle or glassy to viscous or rubbery as the temperature is increased.
Polypropylene or a propylene-based polymer, as used in this disclosure, means polymers comprising greater than 50%by mole of units derived from propylene monomer. This includes propylene-based homopolymers or copolymers.
Polyethylene or an ethylene-based polymer, as used in this disclosure, means polymers comprising greater than 50%by mole of units derived from ethylene monomer. This includes ethylene-based homopolymers or copolymers.
Nonwoven, as used in this disclosure, means a web or fabric having a structure of individual fibers or threads which are randomly interlaid as opposed to an identifiable manner as is the case for a knitted fabric.
Staple fiber means a natural fiber, or a length cut from, for example, a manufactured filament. Staple fibers include natural and synthetic materials. Natural materials include cellulosic fibers and textile fibers such as cotton and rayon. Synthetic materials include nonabsorbent synthetic polymeric fibers, e.g., polyolefins, polyesters, polyacrylics, and polyamides.
Nonwoven
The nonwoven may comprise 20 to 80 wt. %, based on the total weight of the nonwoven, meltblown fiber. All individual values and subranges of 20 to 80 wt. %are disclosed and incorporated herein. The nonwoven may comprise 40 to 60 wt. %, based on the total weight of the nonwoven, meltblown fiber. The nonwoven may comprise 30 to 70 wt%, based on the total weight of the nonwoven, meltblown fiber. The nonwoven may comprise 50 to 70 wt%, based on the total weight of the nonwoven, meltblown fiber.
Staple fibers are intermingled with the meltblown fibers. The nonwoven may comprise 20 to 80 wt. %, based on the total weight of the nonwoven, staple fiber. All individual values and subranges of 20 to 80 wt. %are disclosed and incorporated herein. For example, the nonwoven may comprise 30 to 70 wt. %staple fiber based on the total weight of the nonwoven. The nonwoven may comprise 40 to 60 wt. %staple fiber based on the total weight of the nonwoven. The nonwoven may comprise 30 to 50 wt. %staple fiber based on the total weight of the nonwoven.
The thickness of the nonwoven may be between 1 mm to 5 mm for a basis weight of 100 gram per square meter (gsm) . All individual values and subranges of 1 mm to 5 mm are included and disclosed. The nonwoven may be 2 mm to 3 mm for a basis weight of 100 gsm. The nonwoven may have a bulk density of 20 to 100 g/l. All individual values and subranges of 20 to 100 g/l are included and disclosed. The nonwoven may have a bulk density of 20 to 40 g/l or 30 to 40 g/l.
The nonwoven may have a basis weight of 50 to 350 gsm. All individual values and subranges of 50 to 350 gsm are included and disclosed. For example, the nonwoven may have a basis weight of between 50 to 100 gsm, 50 to 70 gsm, 250 to 325 gsm, or 290 to 325 gsm.
The nonwoven may have a thermal resistance greater than or equal to 0.200 (m ²K) /W at a basis weight between 60 to 67 gsm. The nonwoven may have a thermal resistance greater than or equal to 0.210 (m ²K) /W at a basis weight between 60 to 67 gsm. The nonwoven may have a thermal resistance from 0.200 to 0.300 (m ²K) /W at a basis weight between 60 to 67 gsm. All individual values and subranges are incorporated and disclosed. For example, the nonwoven may have a thermal resistance from 0.200 to 0.250 (m ²K) /W at a basis weight between 60 to 67 gsm.
The nonwoven may have a thermal resistance greater than or equal to 0.900 (m ²K) /W at a basis weight of 300 gsm. The nonwoven may have a thermal resistance greater than or equal to 0.950 (m ²K) /W at a basis weight of 300 gsm. The nonwoven may have a thermal resistance from 0.900 to 1.500 (m ²K) /W at a basis weight of 300 gsm. All individual values and subranges are incorporated and disclosed. For example, the nonwoven may have a thermal resistance from 0.900 to 1.000 (m ²K) /W at a basis weight of 300 gsm.
Meltblown fiber made from polyethylene or a mixture of polyethylene and polypropylene
Meltblown fibers can be generated by extruding a fiber forming material through a die orifice into a gaseous stream as described in more detail below. Typically, when compared to staple fibers, meltblown fibers are very long and have an indeterminate length. The meltblown fiber may have a diameter less than 10μm.
The meltblown fiber may comprise a polyethylene or a mixture of a polyethylene and a 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 both linear and substantially linear low density resins (m-LLDPE) ; medium density polyethylene (MDPE) ; and high density polyethylene (HDPE) .
Additionally, as described 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 partly or entirely homopolymerized or copolymerized in an autoclave or a tubular reactor at pressures above 14, 500 psi (100 MPa) with the use of free-radical initiators, such as peroxides (see, e.g., U.S. Patent No. 4, 599, 392) . LDPE resins typically have a density in the range of 0.91 g/cm ³ to 0.94 g/cm ³.
The term LLDPE, as described herein, may include resins made using Ziegler Natta catalyst systems as well as resins made using single-site catalysts, including, but not limited to, bis-metallocene catalysts (sometimes referred to as m-LLDPE) , phosphinimine, and constrained geometry catalysts; and resin 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. LLDPEs contain less long chain branching than LDPEs and include the substantially linear ethylene polymers, which are further defined in U.S. Patent No. 5,272,236, 5,278,272, 5,582,923, and 5,733,155; the homogeneously branched ethylene polymers such as those described in U.S. Patent No. 3,645,992; the heterogeneously branched ethylene polymers such as those prepared according to the process disclosed in U.S. Patent No. 4,076,698; and blends thereof (such as those disclosed in U.S. Patent No. 3,914,342 or U.S. Patent No. 5,854,045) . The LLDPE resins may be made via gas-phase, solution-phase, or slurry polymerization as well as any combination thereof using any type of reactor or reactor configuration known in the art. The LLDPE resins may be made via gas-phase, solution-phase, or slurry polymerization as well as any combination thereof, using any type of reactor or reactor configuration known in the art.
Additionally, as described herein, the term HDPE refers to polyethylenes having densities of about 0.940 g/cm ³ or greater, which are generally prepared with Ziegler-Natta catalysts, chrome catalysts or even metallocene catalysts.
The meltblown fiber may have a fiber diameter of less than 10 μm. The meltblown fiber may have a fiber diameter of less than 5 μm. The meltblown fiber may have a fiber diameter of from 1 μm to 10 μm. All individual values and subranges of from 1 μm to 10 μm are incorporated and disclosed. For example, the meltblown fiber may have a fiber diameter from 2 to 5 μm.
The meltblown fiber may comprise polyethylene or a polyethylene and polypropylene mixture. The meltblown fiber may comprise, based on the total weight of the meltblown fiber, 40 to 60 wt. %polypropylene. All individual values and subranges of 40 to 60 wt. %polypropylene are incorporated and disclosed. For example, the meltblown fiber may comprise 45 to 55 wt. %, based on the total weight of the meltblown fiber, polypropylene. The meltblown fiber may comprise 50 wt. %, based on the total weight of the meltblown fiber, polypropylene.
The meltblown fiber may comprise, based on the total weight of the meltblown fiber, 20 to 100 wt. %polyethylene. For example, the meltblown fiber may comprise from a lower limit of 20, 25, 30, 40, 45, 50, 55, 60, 75, 80, 90, 95 or 99 wt%to an upper limit of 100, 99, 95, 90, 80, 75, 60, 55, 40, 35, 30, or 25 wt. %polyethylene based on the weight of the meltblown fiber.
The meltblown fiber may comprise polyethylene that may have a melt index (I ₂) between 200 to 1000 g/10min. All values and subranges of 200 to 1000 g/10min are disclosed and incorporated herein. The meltblown fiber may comprise polyethylene that may have a melt index (I ₂) between 200 to 700, or 200 to 500 g/10min.
Staple fiber
The staple fiber may be added as a solid that has been machine cut to a predetermined length. The staple fiber may have a fiber diameter of equal to or greater than 10 μm. The staple fiber may have a diameter between 10 to 50 μm. All individual values and subranges of 10 to 50 μm are disclosed and included herein. The staple fiber may have a diameter between 10 to 25 μm or between 25 to 50 μm. The length of the staple fiber may be between 30 mm to 60 mm. All lengths between 30 mm to 60 mm are included herein. The staple fiber may be between 35 to 55 mm, between 40 to 50 mm, or between 35 to 45 mm. The fiber thickness could be defined by Denier as well. Denier defines the mass density of the fibers that the fabric is made of and indicates the fineness of the fiber. A denier is equal to the mass in grams per 9,000 meters of thread. The staple fiber generally has a denier of equal to or greater than 3g/9,000m (3D) , or equal to or greater than 4g/9,000m (4D) . The denier is typically less than 10g/9,000m (10D) .
The staple fiber may comprise synthetic polymeric material. The staple fiber may comprise polyethylene terephthalate, polyester, polyethylene, polypropylene, copolyester, polyamide, PAN, cellulose or mixtures thereof. Staple fiber may be chosen that can be melt-bonded to each other and/or to the meltblown fiber. Staple fiber may be chosen that cannot be melt-bonded to each other and/or to the meltblown fiber. The staple fiber may be crimped. Crimped staple fiber may have a continuous, wavy, curly, or jabbed profile along their length. The stable fiber may have 8 to 14 crimps per inch of staple fiber.
Nonwoven additive
The nonwoven may contain additives that improve mechanical properties, aging properties, coloration, surface properties, or other characteristics of interest. Suitable additives include fillers, nucleating agents, electric charging enhancement additives, light stabilizers, stiffening agents, surface active agents, and surface treatments. Those of skill in the art will be familiar with the amounts of various additives to be added as well as other types that may be included.
Process for making the nonwoven
The meltblown fiber may be extruded through a die with closely arranged orifices and attenuated by convergent streams of hot air at high velocities such that fine fiber is formed. This fiber may then be collected on a surface. The meltblown fiber should be continuous.
A flow stream of a thermoplastic polymer may be fed into a manifold. The flow stream may then be fed into a die. Air slots disposed on either side of the die orifices through which the thermoplastic polymer leaves the die direct uniform heated air at high velocities at the extruded melt stream. The hot, high velocity air draws and attenuates the extruded thermoplastic polymer material which solidifies after traveling a short distance from the spinneret. The high velocity air may become turbulent between the spinneret and the collector surface causing the meltblown fiber in the airstream to mix.
Polyethylene and polypropylene blended fibers may be produced by feeding both together from separate hoppers or from the same hopper, after pre-blending the two pellets, into one extruder and spinning out both from the die together.
Polymeric material may be fed from a hopper and extruder to a meltblowing die through an inlet and then flow through the die cavity. The polymeric material may exit the die cavity through a row of larger and smaller size orifices arranged in a line across a forward end of the die cavity. An airborne stream of high velocity heated air may attenuate the filaments. The orifices may comprise a row of larger and smaller orifices. As will be understood by those of skill in the art, larger diameter fiber may extrude from the larger sized orifices while smaller diameter fiber may extrude from the smaller diameter orifices.
Staple fiber filaments may be fed from a hopper and extruder to a large die cavity. An airborne stream of high velocity heated air may attenuate the staple fiber filaments and mix the staple fiber filaments with meltblown filaments exiting a die cavity that can be oriented perpendicular to the staple fiber die cavity. As would be obvious to those of skill in the art, the entanglement level of the meltblown and stable fibers can be modified by adjusting the orientation of the meltblown and stable die cavities to each other. If staple fiber exits the staple fiber die cavity horizontally, meltblown fiber would need to exit the meltblown die cavity vertically.
Use of the nonwoven
The disclosed nonwoven may be used in several thermal and acoustic applications. The disclosed nonwoven may be used, for example, in battery compartments, engine compartments, automotive vehicle doors and ceilings, railway car insulation applications, automotive trunks, automotive hoods, building and utility wraps, furniture upholstery, HVAC systems, and jacket linings or fillers. The nonwoven may be used as a monolithic layer. The monolithic layer may be enclosed by cavity walls. An outer layer may be wrapped around the nonwoven such that the nonwoven is fully encapsulated. An adhesive layer may be applied to one or multiple surfaces of the nonwoven. A release liner may be attached to the adhesive layer or layers. The adhesive layer may be pressure sensitive, curable, or hardenable. The adhesive layer may be comprised of binders.
TEST METHODS
Density
Density is measured in accordance with ASTM D-792 and expressed in grams/cubic centimeter (g/cc) .
Melt Index and Melt Flow Rate (MFR)
Melt index (I ₂) is measured in accordance with ASTM D-1238 at 190℃ at 2.16 kg. The values are reported in g/10 min, which corresponds to grams eluted per 10 minutes. Melt flow rate is measured for polypropylene or propylene-based polymers and is measured at 230℃ at 2.16 kg.
Basis Weight
The sample is cut into 100 cm ² samples and weighed on a balance. This weight is then multiplied by 100 to convert the measurement to grams per square meter (gsm) .
Thermal Insulation Performance
Thermal insulation performance is measured according to GB/T11048-2018. Thermal resistivity, CLO value, insulation rate, and thermal conductivity are recorded.
Sound Acoustic Performance
Sound acoustic performance is measured according to GB/T18696.1-2004 with a frequency range from 100 to 6300 Hz. The sound absorbing coefficient is measured in terms of both the standing wave tube method and the reverberation chamber method.
Softness (drapability) Performance
An example of a drapability test can be seen in Figure 1. Samples of 16 cm width are placed at the edge of a desk with 5 cm extending over the desk’s edge. The horizontal distance between the pendent end of the sample and the desk (L) is measured along with the vertical distance between the desk edge and the end of the imaginary line L from the pendent edge to the desk. The angle between the nonwoven and the vertical surface of the desk (a) is calculated. Smaller angles are indicative of better drapability.
EXAMPLES
The following examples are provided to further illustrate the description and claims. They should not be taken as limiting the disclosure. Raw materials used are listed below in Table 1.
Table 1: Materials
EMBR-1 Production
The experimental ethylene/alpha-olefin interpolymer meltblown fiber resin 1 (EMBR-1) is produced with ethylene, 1-octene, and a narrow boiling range high-purity isoparaffinic solvent purified with molecular sieves in a single reactor configuration. Hydrogen is supplied pressurized as a high purity grade and is not further purified. The reactor monomer feed stream is pressurized via a mechanical compressor to above reaction pressure. The solvent and comonomer feed is pressurized via a pump to above reaction pressure. The individual catalyst components are manually batch diluted to specified component concentrations with purified solvent and pressured to above reaction pressure. All reaction feed flows are measured with mass flow meters and independently controlled with computer automated valve control systems.
The continuous solution polymerization reactor consists of a liquid full, non-adiabatic, isothermal, circulating, loop reactor which 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 total fresh feed stream to the reactor (solvent, monomer, comonomer, and hydrogen) is temperature controlled by passing the feed stream through a heat exchanger. The total fresh feed to the polymerization reactor is injected into the reactor at two locations with approximately equal reactor volumes between each injection location. The fresh feed is controlled with each injector receiving half of the total fresh feed mass flow.
The first reactor’s feed solvent to ethylene mass flow ratio is 3.8. The first reactor’s feed comonomer to ethylene mass flow ratio is 0.20. The first reactor’s feed hydrogen to ethylene mass flow ratio is 3.0 x 10 ^-4 The first reactor’s temperature is 155 ℃, and the first reactor’s pressure is 34 bar., while the first reactor’s ethylene conversion percent is 86.1.
The catalyst components are injected into the polymerization reactor through a specially designed injection stinger. The primary catalyst component feed is computer controlled to maintain the reactor monomer conversion at the specified target. The cocatalyst components are fed based on calculated specified molar ratios to the primary catalyst component. Immediately following each reactor feed injection location, the feed streams are mixed with the circulating polymerization reactor contents with static mixing elements. The contents of the reactor are continuously circulated through heat exchangers responsible for removing much of the heat of reaction and with the temperature of the coolant side responsible for maintaining an isothermal reaction environment at the specified temperature. Circulation around the reactor loop is provided by a pump.
The first reactor’s catalyst type 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-) -. kappa. N] [ (1, 2, 3, 4-. eta. ) -1, 3-pentadiene] -titanium. The first reactor’s co-catalyst-1 type is bis (hydrogenated tallow alkyl) methylammonium tetrakis (pentafluorophenyl) borate (1-) while the first reactor’s co-catlayst-2 type is aluminoxanes, iso-Bu Me, branched, cyclic and linear; modified methyl aluminoxane. The first reactor’s co-catalyst-1 to catalyst molar ratio is 1.2, while the first reactor’s co-catalyst-2 to scavenger molar ratio is 5.0. The first reactor’s residence time is 13.1 mins.
The final reactor effluent enters a zone where it is deactivated with the addition of and reaction with a suitable reagent (water) . At this same reactor exit location other additives are added for polymer stabilization. Conditions were chosen such that at least a 10 fold molar ratio of (hydrate) water vs active catalyst is available to stop the polymerization at the reactor effluent. This aspect is important in order to assure the polymer material has a narrow molecular weight distribution and the composition distribution is maintained narrowly.
Following catalyst deactivation and additive addition, the reactor effluent enters a devolatization 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, pg. 6, ll. 23-28, pg. 8, ll. 11-16, and pg. 11, ll. 3-25. The non-polymer stream passes through various pieces of equipment which separate most of the ethylene which is removed from the system. Most of the solvent and unreacted comonomer is recycled back to the reactor after passing through a purification system. A small amount of solvent and comonomer is purged from the process.
Nonwoven Production
Nonwovens CE-1 and CE-2 are prepared in a reicofil pilot line with a 0.6 m width. All other nonwovens are prepared in another melt blown production line with a 1.6 m width and a hole diameter of 0.3mm. The air temperature is set to 240 –270℃ depending on the melt index of the melt blown resins. The insulation cotton is produced in a 1.6m width meltblown machine. Polyethylene terephthalate staple fiber is incorporated through a side feeding unit at a rate of 15kg/hr. The extruder temperature is set at 170℃ in the first area, 180℃ in the second area, 200℃ in the third area, 210℃ in the fourth area, and 220℃ in the fifth area from the hopper to the nozzle. For polypropylene the melt pump temperature is set at 225℃ while for polyethylene the melt pump temperature is set to 220℃. The hot air temperature is set to 230℃ for polypropylene and to 220℃for polyethylene.
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 fiber. These samples proved not bulky enough for insulation cotton. This lack of bulk leads to inefficient sound and heat absorption. Comparative example 2 used a low melt index polyethylene product and had to be processed at 50%output when compared to CE-1. This led to a larger fiber size.
Table 2: PET Free Samples
Table 3 shows results for comparative and inventive samples. CE-3 and CE-5 (Comparative Examples 3 and 5) are examples of the prior art solution using polypropylene melt blown with polyethylene terephthalate staple fiber with different basis weights. CE-4 (Comparative Example 4) is a commercially sold silk quilt used as a reference. IE-1 and IE-3 (Inventive Example 1 and 3) are inventive examples in which the polyethylene melt blown was used instead of polypropylene with different basis weights so that improved comfort and softness could be achieved. IE-2 and IE-4 (Inventive Examples 2 and 4) are another pair of inventive examples with different basis weights in which both polyethylene and polypropylene melt blown are used so that strength and softness can be balanced.
Table 3: Inventive and Comparative Examples
Table 4 shows the angles calculated in the drapeability test described above. The polyethylene sample (IE-1) had the best drapability while polypropylene (CE-3) had the worst. The polyethylene polypropylene blend (IE-2) fell in-between these two extremes. Although CE-4 has comparable drapability with IE-1, IE-1 has better heat insulation performance as will be shown in the next section.
Table 4: Drapability Test

Sample	IE-1	IE-2	CE-3	CE-4
Pendent Angle	45°	67°	74°	48°

Thermal insulation data is shown in Table 5. Higher thermal resistivity, CLO value, and insulation rate along with lower thermal conductivity indicate better thermal insulation. The inventive examples (IE-1/IE-2) show better thermal insulation performance than comparative example 4 (CE-4) even though CE-4 has a higher basis weight, indicating the advantage of better insulation efficiency for the inventive examples listed here. CE-3 has a higher insulation performance than IE-1/IE-2 because it has a higher basis weight (along with a much higher rigidness as discussed before) . When we compare the examples of IE-3/IE-4/CE-5 which have the same basis weight (300 gsm) , the inventive examples (IE-3/IE-4) show better or comparable thermal insulation performance when compared with the comparative example (CE-5) .
Table 5: Thermal insulation performance of samples in this invention
Sound acoustic performance is shown in Figures 2, 3 and 4. As can be seen in Figure 2, the sound acoustic co-efficient for IE-1 and IE-2 is comparable to that of CE-3 from 100 to 10000 Hz when measured using the GB/T 18696.1-2004 standard. This is even though the basis weight for IE-1 and IE-2 is around 30 gsm less than that of CE-3.
Figure 3 shows that when IE-3 is compared to CE-5, using the standing wave method at the same basis weight, IE-3 has a higher sound absorbing coefficient than CE-5 from 100 to 7000 Hz and such advantages exist at low frequency range. Figure 4 shows that the same is true of IE-3 when compared to CE-5 when the sound absorbing coefficient is measured according to the reverberation chamber method.

Claims

A nonwoven comprising:

a. 20 to 80 wt. %, based on the total weight of the nonwoven, meltblown fiber wherein the meltblown fiber comprises polyethylene, or a mixture of polyethylene and polypropylene, wherein the polyethylene has a melt index (I ₂) between 200 to 1000 g/10 min and

b. 20 to 80 wt. %, based on the total weight of the nonwoven, staple fiber.
The nonwoven of claim 1 comprising:

a. 30 to 70 wt. %, based on the total weight of the nonwoven, meltblown fiber, and

b. 30 to 70 wt. %, based on the total weight of the nonwoven, staple fiber.
The nonwoven of claim 1 comprising:

a. 40 to 60 wt. %, based on the total weight of the nonwoven, meltblown fiber, and

b. 40 to 60 wt. %, based on the total weight of the nonwoven, staple fiber.
The nonwoven of any preceding claim, wherein the staple fiber comprises polyesters, polypropylene, PAN, polyamides, cellulose, or mixtures thereof.
The nonwoven of claim 1 comprising:

a. 50 to 70 wt. %, based on the total weight of the nonwoven, meltblown fiber wherein the meltblown fiber comprises 40 to 60 wt. %polyethylene and 40 to 60 wt. %polypropylene, based on total weight of the meltblown fiber, and

b. 30 to 50 wt. %staple fiber, based on the total weight of the nonwoven.
The nonwoven of any preceding claim, wherein the thermal resistance of the nonwoven is greater than 0.200 (m ²K) /W at a basis weight between 60 to 67 gsm or greater than 0.900 (m ²K) /W at a basis weight of 300 gsm.
The nonwoven of any preceding claim, wherein the meltblown fiber has a fiber diameter of less than 10 μm.
The nonwoven of claims 1 –6, wherein the staple fiber has a fiber diameter of 10 to 50 μm.