359 results about "Wood fibre" patented technology

A set of panels including a locking device for locking a first edge portion of a first panel to a second edge portion of a second panel. The locking device includes a horizontal locking device and a vertical locking device. The vertical locking device includes a separate tongue arranged in an insertion groove of the first edge portion and a tongue groove provided in the second edge portion. In a vertically locked state of the first and second edge portions, an abutment member provided at a longitudinal end portion of the separate tongue cooperates with a stop surface of the second edge portion, and a locking portion of the separate tongue cooperates with the tongue groove at a locking surface arranged in a wood-based body layer including wood fibres mainly oriented along a first fibre direction.

Systems and methods for providing compostable food containers, which preserve the quality of a food product for an extended duration of time, and which optionally, allow for cooking of the food product therein. In some implementations, the food containers are sturdy, stackable, insulating, and require minimal or no manual labor to assemble. In some implementations, the food container includes a base and a cover, which cooperate to form a closed chamber for supporting, protecting, insulating and optionally cooking a food product, such as a pizza. The base and cover may each be formed of a single layer of material including, but not limited to, molded sugarcane fiber (“bagasse”), molded wood fiber, molded bamboo fiber, molded paper or plastic.

Systems and methods for providing compostable food containers, which preserve the quality of a food product for an extended duration of time, and which optionally, allow for cooking of the food product therein. In some implementations, the food containers are sturdy, stackable, insulating, and require minimal or no manual labor to assemble. In some implementations, the food container includes a base and a cover, which cooperate to form a closed chamber for supporting, protecting, insulating and optionally cooking a food product, such as a pizza. The base and cover may each be formed of a single layer of material including, but not limited to, molded sugarcane fiber (“bagasse”), molded wood fiber, molded bamboo fiber, molded paper or plastic.

The invention belongs to the technical field of corrugated paperboards, and is characterized in that wood fibers and modified bamboo fibers prepared by reaction of allyl bamboo fibers, 1, 4-butanediol di (mercaptoacetate) and magnolol are pulped, a biodegradable water-resistant auxiliary agent is added for hydrophobic modification, papermaking and shaping are carried out to prepare water-resistant base paper, and the water-resistant base paper is prepared by the following steps: pulping the modified bamboo fibers and the biodegradable water-resistant auxiliary agent. And finally, preparing a surface paper layer, a corrugated medium paper layer and an inner paper layer from the water-resistant raw paper, and bonding and pressing to obtain the corrugated board. Magnolol groups grafted on the surfaces of the modified bamboo fibers can improve the water absorption performance of the fibers, and the hydrophobicity of the corrugated board is improved through the synergistic effect of the magnolol groups and the biodegradable water-resistant auxiliaries; the surface of the biodegradable water-resistant auxiliary agent is embedded with a carboxylated nano-cellulose structure, so that the biodegradable water-resistant auxiliary agent has deformation resistance; the epoxidized soybean oil is used as a core part and has excellent hydrophobicity; through combination of a polyphenol structure of tannic acid and hydrogen bonds of water-resistant base paper fibers, the mechanical properties of the corrugated board are improved, and the corrugated board has excellent biodegradability, hydrophobicity and mechanical strength.

The invention provides a high-performance wood-based metal electric heating material and a preparation method thereof. The wood-based metal electric heating material has excellent electric heating capability and relatively high tensile strength and can be molded and processed. The method comprises the following steps: immersing fibers obtained by dispersing and crushing thin wood chips into a sodium chlorite solution to decompose lignin, cleaning with distilled water, and drying to obtain wood fibers; the preparation method comprises the following steps: blending multi-walled carbon nanotubes and graphene in a mass ratio of (3-5): (4-7), adding 10wt% of the mixture into distilled water, adding 1-3wt% of a dispersant, and performing ultrasonic treatment to obtain carbon nano slurry; wood fibers are soaked in the carbon nano slurry, taken out and dried, then soaked in a silane coupling agent solution, taken out and drained; blending the powdery tin-bismuth alloy and thermoplastic high-molecular polymer powder according to a mass ratio of 1: 8-1: 12 to obtain low-melting-point alloy / polymer mixed powder; and the low-melting-point alloy / polymer mixed powder and wood fibers are blended according to the mass ratio of (1-3): 1, and high-temperature melt extrusion is performed.

The invention relates to the technical field of cables, and particularly discloses a seawater corrosion resistant cable and a preparation method thereof. The seawater corrosion resistant cable comprises a cable core, an insulating layer and a sheath layer which are arranged in sequence, and the sheath layer comprises the following substances in parts by weight: 100 parts of PE; 20 to 30 parts of filler; 5-10 parts of an auxiliary agent; the filler comprises eucalyptus fibers, wollastonite and medical stone powder. The preparation method comprises the following steps: S1, preparing the sheath material; and S2, preparing the cable. The cable can be used in ocean or beach sightseeing tourism, and has the advantages of high strength, high corrosion resistance and high pressure resistance.

The invention belongs to the technical field of fiber felts, and particularly relates to a preparation method of a bamboo / wood / PP fiber felt for automotive interiors and a composite material of the bamboo / wood / PP fiber felt.The bamboo / wood / PP fiber felt is formed by opening, scattering, fully mixing and carding mixed fibers composed of wood fibers and modified bamboo fibers and PP fibers to form a fiber net, and then the fiber net is needled to form a dense felt material; wherein the modified bamboo fiber is prepared by the following steps: mixing 3, 5-di-tert-butyl-4-hydroxybenzaldehyde, methyl undecyl ketone, a sodium hydroxide solution and ethanol for reaction to obtain a hindered phenol material; mixing and reacting the hindered phenol material, chloroplatinic acid and tetrahydrofuran to obtain a long-chain alkyl hindered phenol grafted material; bamboo fibers, an ethanol solution and the long-chain alkyl hindered phenol grafting material are mixed and react, and modified bamboo fibers are obtained; the ultraviolet light stability of the bamboo / wood / PP fiber felt for the automotive trim is improved, and the tensile property of the bamboo / wood / PP fiber felt for the automotive trim can be greatly enhanced.

The invention discloses a degradable high-strength plastic bag and a preparation method thereof, and relates to the technical field of plastic bag preparation. The degradable high-strength plastic bag at least comprises the following raw materials in parts by mass: 40-60 parts of polylactic acid, 20-35 parts of poly (adipic acid) / butylene terephthalate, 5-15 parts of modified nano calcium carbonate, 3-8 parts of modified wood fibers, 6-8 parts of chitosan grafted polyglycidyl methacrylate nanoparticles, 0.5-2 parts of a lubricant, 0.3-1 part of an antioxidant and 2-5 parts of a degradation accelerator. And 0.5 to 1.5 parts of an ultraviolet stabilizer. According to the degradable high-strength plastic bag prepared by the preparation method disclosed by the invention, the polylactic acid and the poly (butylene adipate-co-terephthalate) are used as base materials, the modified nano calcium carbonate and the modified fibers are used as fillers, and the chitosan grafted polyglycidyl methacrylate nanoparticles are used as a compatilizer, so that the balance of high strength and degradability is realized; the prepared degradable high-strength plastic bag can be used as a high-performance flexible packaging material.

The invention provides a seepage-preventing and water-retaining structure for ecological restoration of an arid mining area in the Yellow River basin and a construction method. The seepage-preventing and water-retaining structure comprises a seepage-preventing layer, a water-retaining layer and an evaporation-preventing layer. The seepage prevention layer is composed of Yellow River silt, bentonite, a base material aggregate agent and an organic material and is laid on the surface of the mine slope; the water retention layer is composed of Yellow River silt, coal gangue, an organic material, an organic fertilizer, a plant growth regulator and a base material composite water retention agent, and is laid on the surface of the permeation prevention layer; the anti-evaporation layer is composed of Yellow River silt, wood fibers, a base material adhesive, a base material composite water-retaining agent and plant seeds and is laid on the surface of the water-retaining layer. The seepage-preventing and water-retaining structure designed by the invention effectively combines three key functions: the seepage-preventing layer effectively prevents water from infiltrating too fast, the water-retaining layer has excellent water-storing and moisture-retaining capabilities, and the evaporation-preventing layer remarkably inhibits water evaporation.

The punching flank 303 on the shaping press 30 makes a second angle γ with the grain of the wood fibers. In order to allow a wider variety of shapes to be pressed into the workpiece and facilitate the demolding of the object from the press after pressing, this angle may vary between 0° and 5°. Thus, the profile of the shaping press on its punching flank may be slightly tapered as illustrated in FIG. 6. This second angle γ additionally makes it possible to obtain a higher quality finish on the internal surface of the wood object.

The invention provides a processing method of a bamboo-wood fiber diatom ooze environment-friendly decorative plate, belongs to the technical field of decorative plate processing, and solves the technical problems that the physical property of the decorative plate is affected and the structural strength of the decorative plate is reduced due to the fact that the phenomenon that air is wrapped in an interlayer easily occurs in an existing multi-layer plate stacking mode. A processing method of a bamboo-wood fiber diatom ooze environment-friendly decorative plate comprises the following steps that waste wood and bamboo processed products are put into a crusher to be crushed into blocks, then blocky waste materials are crushed multiple times till the waste materials are powdered, bamboo-wood powder is obtained, then the bamboo-wood powder is screened through a 60-mesh screen, and the bamboo-wood fiber diatom ooze environment-friendly decorative plate is obtained. Impurities and particles in the bamboo powder are separated out, and a part of screened bamboo fibers are taken out to serve as standby materials. The decorative plate has the advantages that the decorative plate is compact in structure and high in structural strength, and the situation that the edge of the decorative plate adheres to the mold groove is prevented.

The present disclosure relates to a method for making fiberboard with a system comprising a plug flow screw, a cooker, a refiner, a blowline, and a press. The method comprises a), introducing woodchips to the plug flow screw; b). passing the woodchips through the plug flow screw to the cooker, c). adding a soy component having a protein dispersibility index (PDI) less than 50 to the cooker, d). passing the woodchips from step c) through the refiner to produce glued refiner wood fibers, e). passing the glued refiner wood fibers from d) through the blowhne to produce pressable wood fibers, f). optionally adding a water retardant, and g). pressing the pressable wood fibers under heat and pressure to form the fiberboard.

The invention discloses a novel birch juice collector, and belongs to the technical field of birch juice collection. The problems that in the prior art, damage to trees is large, collecting cost is high, efficiency is low, and environment friendliness is not achieved are solved. According to the technical scheme, a juice collector body is of a long and thin needle-tube-shaped structure and is hollow, a needle tip is sharp, a needle tail is in a steel nail cap shape, three arc-shaped grooves are formed in the surface of the needle tip, three longitudinal grooves are formed along the surface of a needle body, rectangular seepage holes are formed in the longitudinal grooves, and the arc-shaped grooves of the needle tip are connected with transverse grooves of the needle body. The position, 10 mm away from the tail end, of the last rectangular seepage hole extends downwards by 95 degrees to be connected with a flow guide pipe; the needle tip can enter a tree body in an extrusion mode, tree fibers cannot be cut off, juice collection and bag hanging are integrated, secondary damage to the tree is avoided, and sustainable collection of birch resources is achieved; tree juice flows out from the outer walls of the needle holes, pollution and external dust are prevented from entering, the purity of the tree juice is guaranteed, and the resource utilization rate is increased.

A building stud for forming a framework for mounting wall panels can include a first and a second flange portions and a web portion interconnecting the flange portions. The flange portions can include a planar, elongated wood fibre member, and the web portion can include a polymer based and / or cellulose fibre based sheet member. The web portion can include a first and a second rectilinear line of weakness. The lines of weakness can be parallel and along which the sheet member is foldable to enable folding the building stud from a retracted storage position to an expanded mounting position.

The invention belongs to the technical field of deodorants, and relates to a poplar fiber board deodorant, which is prepared from the following ingredients in parts by mass: 22 to 28 parts of multi-ion water, 22 to 28 parts of amino formaldehyde catching agents, 4 to 6 parts of nanometer TiO2, 8 to 12 parts of beta-cyclodextrin, 12 to 18 parts of porous adsorbents, 4 to 6 parts of surfactants and 12 to 18 parts of plant essential oil emulsion. The invention further discloses a preparation method and application of the poplar fiber board deodorant. The deodorant disclosed by the invention has a multi-mechanism synergistic deodorization effect of chemical decomposition, physical adsorption and biological bacteriostasis, can effectively remove peculiar smell of wood and peculiar smell problems caused by an adhesive, a waterproof agent and the like added in a plate processing process, reduces smell release of a poplar fiber plate, and improves indoor air quality.

The invention relates to a method for producing a wood fiber material (32), comprising the steps of providing fiber material (30), burning a fuel (24) in a furnace (16) so that exhaust gas (27) is produced, drying fiber material (30) in a dryer (28) using the exhaust gas (27) so that dried fiber material (32) and vapors (34) are produced, and discharging vapors (34) into the environment (44), comprising the step of returning a portion of the vapors (34) to the furnace (16) so that volatile organic substances contained in the returned vapors (34) are burned.

This invention relates to the field of board production technology, specifically to a raw material pretreatment device and method for moisture-controlled board production. The device includes a crushing cylinder, a top cover, and a base. A bracket is installed at the bottom of the base, and a motor is installed at the bottom end of the base. A rotating shaft is installed at the output end of the motor, extending through the base into the interior of the crushing cylinder. A support frame is fixed at the top of the crushing cylinder, and the rotating shaft is rotatably mounted in the support frame. A crushing rod is installed on the rotating shaft. The base has a cavity structure, including an inclined body, a first ring body, and a protruding post. The top ends of the first ring body and the protruding post are fixedly connected to the bottom end of the inclined body, and there is a ring channel between the protruding post and the first ring body. Pressed bamboo and wood fiber rods or blocks are crushed and then enter the crushing cylinder, and after being crushed by the crushing cylinder, they enter the hollow cavity of the base. The generated powder rotates on a turntable, and a magnetic metal separation component separates the powder rotating on the turntable. Finally, the separated magnetic metal is placed in a storage tank to ensure the performance of the electromagnet.

A process for producing a fiberboard from wood fibers and / or other lignocellulosic fibers using a wet process, in which water (9) is added to the fibers (7) to form a suspension (10) with a fiber content of 10 wt.% or less, in which the suspension (10) is pumped onto a long screen (11) and dewatered by gravity to form a fiber fleece cake (13), characterized in that the fiber fleece cake (13) is fed to a squeezer (14) and mechanically dewatered to a residual moisture content of less than 20 wt.% to form a fiber fleece (16), and the fiber fleece (16) is then transferred to a continuously operating hot press (18) and pressed there to form a fiberboard (19) under heat input.

The invention discloses an antibacterial and bacteriostatic bamboo-wood fiber-based food material packaging box and a preparation method thereof, and relates to the technical field of packaging materials. The packaging box is composed of a paper base layer and an antibacterial coating on the surface of the paper base layer. Wherein the paper base layer is made of mixed paper pulp; the antibacterial coating is obtained by coating the surface of the paper base layer with an antibacterial coating; the antibacterial coating is prepared from the following raw materials in parts by mass: 30 to 40 parts of deionized water, 2 to 2.4 parts of polyvinyl alcohol, 1.2 to 1.5 parts of glycerol, 6.7 to 7.3 parts of antibacterial particles, 0.1 to 0.4 part of rosmarinic acid and 0.5 to 0.8 part of modified silicon dioxide; the antibacterial particles are formed by mesoporous carrier materials loaded with wormwood essential oil. Due to the introduction of components such as the antibacterial particles and the modified silicon dioxide, the long-acting antibacterial, waterproof and fresh-keeping capacities of the bamboo-wood fiber-based food material packaging box are effectively improved. Therefore, the method has a wide application prospect.

A roofing material is provided having an asphalt-coated mat or felt made up of or in combinations of fiberglass, polyester, nylon, cotton, cellulosic fibers or materials, polyethylene, polypropylene, co-polymers, melamine, phenolic, acrylics, polycarbonate, carbon fiber, clay, metallic in woven, non-woven, strands or sheets, styrene compounds, rubber, silk, leather, or wool in a woven, non-woven, or solid form. The surfacing materials can be made up of or in combination minerals, plastic particles or film, metal particles or film, cement particles, clay particles, paints, coatings, glass, ceramics, wood, wood fiber, or composite materials.

The application discloses a long-acting fragrance essential oil microcapsule veneer artificial board and a preparation method thereof, and comprises a core board, both sides of the core board are provided with surface layer single boards with holes, the surface of the surface layer single boards with holes is sequentially provided with a surface layer thin single board and an impregnated glue film paper; a plurality of waist-shaped through holes are arranged on the surface layer single boards with holes, and the waist-shaped through holes are filled with essential oil microcapsule composite fillers; the essential oil microcapsule composite fillers comprise essential oil microcapsules, putty powder, wood fibers and melamine urea-formaldehyde resin glue; and the essential oil microcapsules comprise single-layer coated microcapsules and double-layer coated microcapsules. The essential oil microcapsules are carried by means of the waist-shaped holes arranged on the surface layer single boards, so that the problem that the adding amount of the microcapsules cannot be improved is solved; and the single-layer and multi-layer microcapsules are simultaneously added, so that the damage of the temperature and pressure in the hot-pressing forming process to the microcapsules is avoided, the long-acting and slow-releasing effect of the fragrance can be realized, and the doped odor generated by the VOC release of the board itself is inhibited.

The utility model relates to a composite bamboo and wood fiber mould pressing tray and a mould pressing mould thereof, the composite bamboo and wood fiber mould pressing tray comprises a mould pressing fiberboard body made of fiber materials through mould pressing, and a dipping profiling layer is compounded on the upper surface and / or the lower surface of the mould pressing fiberboard body. The thickness of the dipping profiling layer is smaller than that of the mould pressing fiberboard body. The application has the advantages that the impregnated profiling layer is compounded on the upper surface and / or the lower surface of the molded fiberboard body by using the impregnated profiling layer and molded fiberboard body compounding technology, so that the wear resistance and durability of the surface of the tray can be improved, and the service life of the tray is prolonged; meanwhile, due to the arrangement of the dipping profiling layer, the surface roughness of the molded fiberboard body in the thickness direction is reduced, a manipulator can take out finished products more quickly, and the working efficiency is improved.

The invention provides one-way wood fiber paper. The one-way wood fiber paper is formed by shrinking a one-way wood veneer in at least one direction, wherein a part of substances are removed from the one-way wood veneer; the partial substances comprise lignin and hemicellulose; the thickness of the unidirectional wood fiber paper is less than or equal to 0.6 mm; the apparent thickness of the unidirectional wood fiber paper under the plane pressure of not more than 0.005 MPa is not more than 4 times of the average thickness of the unidirectional wood fiber paper. Compared with the prior art, the unidirectional wood fiber paper provided by the invention is thin in thickness, excellent in mechanical property and anisotropic, is made of 100% pure natural materials, has a compact effect in the thickness direction after being shrunk, and meanwhile, the transverse binding force and compactness of the unidirectional wood fiber paper are increased; and transverse cracking of the unidirectional wood fiber paper is reduced.

The invention relates to the technical field of fiber materials, and discloses a metal chelation-based glue-free glued fiberboard preparation method which comprises the following steps: carrying out oxidation treatment on wood fibers to obtain an intermediate; squeezing the intermediate, spraying a metal salt solution, uniformly stirring and mixing, spraying a gallic acid solution, stirring, drying, and regulating and controlling the water content to prepare chelate fibers; and pressing the chelated fiber into a plate blank, and carrying out hot pressing treatment to obtain the glue-free glued fiber plate. Metal salt ions and lignin hydroxyl are bonded and coordinated by adopting an activation method, then the metal salt ions and the lignin hydroxyl are chelated with gallic acid to form self-adhesion, fibers are formed after hot pressing and are tightly interwoven and stacked to form the glue-free glued fiberboard, the mechanical property, the water absorption expansion rate and the like can reach the national standard, the preparation method is simple and easy to implement, and the production cost is low. Raw materials are easy to obtain and suitable for mass production; zero formaldehyde release of the fiberboard is achieved, and the cost is lower.

To provide a woody fiber board composition exhibiting a high yield during preparation of subdivided products, together with a low generation rate of powder dust during the preparation of the subdivided products; and to provide a woody fiber board, a resin molded article, a pellet manufacturing method and a manufacturing method of the resin molded article thereof.SOLUTION: A woody fiber board composition comprises lignocellulose fiber, and an isocyanate compound. A content of the isocyanate compound to a total mass of the lignocellulose fiber and the isocyanate compound is 0.5 mass% or more and 6 mass% or less.SELECTED DRAWING: None

The present invention provides a system for continuously monitoring and extracting stickies from papermaking white water, and an application for extracting stickies. The system includes a mounting frame, a white water sampling system, a sample pretreatment system, a hot air separation system, a negative pressure extraction system, and an integrated isolation structure. The system uses a sampling port provided on the white water delivery pipeline and a cyclic rotation mechanism of a sampling pulp plate to continuously collect, separate, and extract stickies from the white water. Based on the differences in the physical properties of dissolved wood fiber and stickies, the two are separated using hot air drying and differential adsorption technology. The system is equipped with an intelligent control unit that can monitor changes in stickies content 24 hours a day. The application method includes four steps: continuous extraction, real-time analysis, dynamic feedback control, and adaptive production optimization. The monitoring data is converted into production control instructions to form a closed-loop control system. This effectively reduces the adverse effects of stickies on the papermaking system, and reduces equipment blockages and paper defects.

The invention relates to the field of composite material preparation methods, in particular to a preparation method of a wood composite material for a new energy automobile, which sequentially comprises the following steps of: a) synchronously winding a plurality of continuous fibers led out in parallel, continuously feeding wood fibers among the fibers in the synchronous winding process, the wood fibers are wound among filaments and on the surface of the multi-filament bundle; b) passing the multi-tow through an atomized adhesive chamber so as to at least enable the wood fibers entangled on the surface of the multi-tow to adsorb an adhesive; c) weaving the multi-tow subjected to glue application into a single layer; and d) carrying out hot-pressing curing on the at least one single layer to obtain the wood composite material, wherein the continuous fibers comprise continuous glass fibers. And the wood composite material meeting the requirements of light weight and multifunctional integration of new energy automobiles can be prepared.

The present invention provides a wooden honeycomb, comprising a white honeycomb and a first resin compounded on the surface of the white honeycomb. The white honeycomb comprises a plurality of pieces of wood fiber paper and a core strip adhesive; the plurality of pieces of wood fiber paper are bonded by means of the core strip adhesive; the plurality of pieces of wood fiber paper comprise unidirectional wood fiber paper and / or composite wood fiber paper; and the composite wood fiber paper comprises the unidirectional wood fiber paper and a second resin layer and / or a fiber reinforced layer compounded on the surface of the unidirectional wood fiber paper. Compared with the prior art, the core material i.e., wood fiber paper, of the wooden honeycomb provided in the present invention is a natural environment-friendly material, and has excellent mechanical properties in both directions parallel to and perpendicular to wood fibers, so that the obtained wooden honeycomb has excellent mechanical properties, light weight and low costs, and is green and environment-friendly.

This application relates to the field of natural materials technology, specifically to a flame-retardant wood-plastic composite material and its preparation method. The method includes: S1: drying natural wood fiber materials; S2: mixing the dried natural wood fiber materials with various raw materials to obtain a raw material mixture; S3: melt-extruding the raw material mixture in a twin-screw extruder to obtain flame-retardant wood-plastic composite material particles, wherein the proportional coefficient of the temperature control process for each barrel heating section is adjusted based on the temperature changes in each barrel heating section during the melt extrusion process; S4: cooling the flame-retardant wood-plastic composite material particles to obtain the flame-retardant wood-plastic composite material. This application solves the temperature lag and fluctuation problems by dynamically adjusting the proportional coefficient of each heating section of the extruder, thereby improving the mechanical properties and appearance quality of the flame-retardant wood-plastic composite material.

The utility model discloses a noise reduction type bamboo and wood fiber integrated wallboard, and relates to the technical field of integrated wallboards. The noise reduction board comprises a base material layer, a decoration layer and a protection layer, a noise reduction layer is arranged between the base material layer and the decoration layer, a plurality of honeycomb holes, a plurality of hemispherical grooves and a plurality of through holes are formed in the noise reduction layer, fixing cylinders are arranged in the through holes, two partition plates are arranged in each fixing cylinder, and the partition plates are connected with the base material layer. The interior of the fixing cylinder is divided into three cavities through the two partition plates, and an inlet pipe and a discharge pipe are arranged on the fixing cylinder. When the noise reduction device is used, primary noise reduction is achieved through the noise reduction performance of the noise reduction layer, secondary noise reduction is achieved through the multiple honeycomb holes, triple noise reduction is achieved through the multiple hemispherical grooves, triple noise reduction is achieved through the cooperation effect of the through hole, the fixing cylinder, the two partition plates, the three cavities, the inlet pipe, the discharge pipe, the connecting pipe and the multiple penetrating holes, and noise reduction is achieved. Therefore, multiple noise reduction is achieved, and stacking of multiple layers of sound absorbing materials is not needed.