Acoustics – Sound-modifying means – Sound absorbing panels
Reexamination Certificate
2000-01-27
2001-04-24
Dang, Khanh (Department: 2837)
Acoustics
Sound-modifying means
Sound absorbing panels
C181S292000, C181S294000
Reexamination Certificate
active
06220388
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
An acoustical insulation panel to absorb and attenuate sound energy.
2. Description of the Prior Art
Various materials and structure have been developed to reduce sound transfer. The sound absorption characteristics of porous insulation materials is a function of the acoustic impedance of the material. Acoustic impedance consists of frequency dependart components acoustic resistance and acoustic reactance. Acoustic reactance depends largely by the thickness of the product and material to a lesser extent by the mass per unit area of an air permeable facing or film which may be applied over the surface of the porous insulation material. On the other hand, acoustic resistance depends on the air flow resistance of the porous insulation material.
U.S. Pat. No. 5,824,973 discloses porous insulation materials such as thermoplastic glass or polymeric fiber blankets and polymeric foams are used in many applications to enhance the sound absorbtion performance of various products and systems.
U.S. Pat. No. 5,804,512 shows a nonwoven laminate fabric comprising first and second nonwoven webs formed of spunbonded continuous filaments and a nonwoven web of meltblown microfibers having a basis weight between about one and twenty grams per square meter sandwiched between and bonded to the first and second nonwoven webs to form a composite nonwoven fabric.
U.S. Pat. No. 5,589,258 relates to a nonwoven material comprising a web of spunbond polymer filaments in combination with at least one other spunbond or meltblown nonwoven layer impregnated with a stabilizing agent.
U.S. Pat. No. 4,766,029 teaches a house wrap consists of a three-layer, semi-permeable, nonwoven laminate. The two exterior layers are spunbond polypropylene having a melt flow of 35 grams per ten minutes at 230° C. The interior layer is a two-component melt-blown layer of polyethylene and polypropylene.
U.S. Pat. No. 5,733,822 describes a composite nonwoven fabric comprising a web of thermoplastic filaments laminated to at least one other web. Preferably, the filaments are spunbonded continuous polyolefin filaments which have an oxidatively degraded outer sheath portion to promote better interfilamentary bonding and improved fabric laminate strength.
U.S. Pat. No. 5,733,635 shows a laminated non-woven fabric of a multi-layer structure comprising a layer of a composite, spun bond non-woven fabric composed of long fibers containing a low melting point resin component and a high melting point resin component, and a layer of a non-woven fabric of melt-blow ultrafine mixed fibers comprising low melting point ultrafine fibers and high melting point ultrafine fibers both of the fibers have an average fiber diameter of 10 um or less, both of the layers are laminated, and fibers in each of the non-woven fabrics and both of the layers are heat-melt adhered with each other.
U.S. Pat. No. 4,828,910 discloses a laminate structure comprising a core of resilient fibrous batt sandwiched between two facing sheets of reinforcing fibrous mat bonded together by a thermoset bonder into a unitary structure.
U.S. Pat. No. 5,824,973 shows a sound absorption laminate comprising a porous insulation substrate, such as, a glass, polymeric or natural fiber blanket or a foamed polymeric resin sheet and a facing sheet with a high air flow resistance. The facing sheet is superimposed upon a surface of the insulation substrate to augment the acoustical properties of the substrate. With the facing sheet the air flow resistance of the laminate is greater than the air flow resistance of the substrate and the laminate exhibits a higher sound absorption coefficient than the sound absorption coefficient of the substrate.
U.S. Pat. No. 5,536,556 discloses an insulating laminate, which is particularly suitable for a sound attenuating barrier including a finish lamina, which may be preferably cloth-like, and a substrate which is preferably structurally stable and self supporting and which may be adapted to absorb sound primarily at predetermined higher frequencies. In one preferred embodiment, a thin flexible film is located between the finish lamina and the substrate which is adapted to absorb sound primarily at relative lower predetermined frequencies. The film may include a pattern of openings or holes designed to absorb sound primarily at predetermined lower frequencies. In the disclosed embodiment, the substrate includes a porous fiber mat, preferably including fibers having a range of thicknesses to improve sound attenuation at higher frequencies, a structural foam lamina and a reinforcing scrim, preferably comprising spunbonded polyester filaments.
U.S. Pat. No. 4,948,660 shows a heat and sound insulating panel comprising an insulating layer of mineral fibers bonded by a synthetic resin and surfacing layer consisting of a sheet of glass fibers. Between these two layers is a heat-sealing film such as polyethylene, having a low level of steam permeability and an aluminum film of a thickness less than or equal to 9 microns glued to the glass sheet.
U.S. Pat. No. 4,898,783 teaches a thermal insulating and sound absorbing structure comprising a batting of resilient, elongatable, non-flammable non-linear carbonaceous fibers having a reversible deflection ratio of greater than 1.2:1, an aspect ratio greater than 10:1 and an LOI value greater than 40.
U.S. Pat. No. 5,298,694 shows a method for attenuating sound waves passing from a source area to a receiving area comprising the steps of providing a nonwoven acoustical insulation web including thermoplastic fibers. (The web has an average effective fiber diameter of less than about 15 microns, a density of less than about 50 kg/m3, and an air pressure drop across the web of at least about 1 mm water at a flow rate of about 32 liters/min) and positioning the web between the source area and the receiving area such that a major face of the web intercepts and thereby attenuates sound waves passing from the source area to the receiving area. In addition a laminate may be applied to the inner panel and a second layer, such as a scrim, nonwoven fabric, film, or foil, laminated thereto.
U.S. Pat. No. 5,554,831 relates to a sound absorbing member comprising a fiber assembly consisting essentially of short fibers and having a thickness of not less than 5 mm, in which new and/or recycled polyester fibers are used as the short fiber and not less than 30% by weight of the polyester fiber used have a fiber-size of not more than 4 denier.
U.S. Pat. No. 5,683,794 shows a multilayered nonwoven composite web particularly useful as a substitute for a woven web such as a textile web, and having improved liquid wicking and retention properties comprising a first layer of fibrous material selected from the group consisting of thermoplastic meltblown man-made fibers, thermoplastic spunbonded man-made fibers, thermoplastic man-made staple fibers and combinations thereof, this first layer being light weight, and a second layer of cellulosic-based fibers, preferably cotton fibers, the first and second layers being thermally bonded together over about 5 to 75% of the surface area of the web to form a coherent web having an air permeability of between about 25 and about 37 ft3/min/ft3 (0.127 and 0.188 m3/sec/m2). In a preferred embodiment, the composite web includes at least a third layer of thermoplastic man-made fibers and the layer of cellulose-based fibers is sandwiched between the two layers of thermoplastic man-made fibers.
U.S. Pat. No. 5,773,375 describes a polypropylene melt-blown microfiber acoustical insulation web which has a resistance to thermal degradation at a temperature of 135° C. for at least 10 days. The polypropylene has a thermal stabilizer uniformly distributed within the melt-blown microfiber polymer which polymer when produced is subject to thermal and/or catalytic degradation in the absence of significant levels of thermal stabilizer or antioxidant.
U.S. Pat. No. 5,817,408 teaches a sound insulating structure including low-density and high-density layers. The low-density
Dang Khanh
Fisher, III A. W.
Strandtek International, Inc.
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