TWI532899B - Low density non-woven material useful with acoustic ceiling tile products and methods for forming acoustic ceiling tiles - Google Patents

Description

Low density non-woven material suitable for soundproof ceiling tile products and method of forming soundproof ceiling tiles

This field relates to a nonwoven material and, in particular, to a low density nonwoven fabric material effective to provide insulation and sound insulation suitable for use as a soundproof ceiling tile.

Conventional acoustical ceiling tiles are non-woven structures that include the core of matrix fibers, fillers, and adhesives that are combined into a ceiling tile structure. The matrix fibers are typically mineral wool or fiberglass. The filler may be perlite, clay, calcium carbonate, cellulose fibers, and the like. The binder is typically cellulosic fibers, starch, latex and the like. After drying, the binder forms a bond with the matrix fibers and filler to form a fibrous web that provides a porous structure in which the tile structure is rigid and forms a sound absorbing structure. For use as a typical ceiling tile, the nonwoven structure or substrate mat should be substantially flat and self-supporting for suspension in a typical ceiling tile grid or similar structure.

For non-woven structures suitable for soundproof ceiling tile applications, the non-woven structure also meets various industry standards and building codes for noise reduction and fire rating. For example, industry standards require ceiling tiles to have a Class A fire rating according to ASTM E84, which typically requires a flame spread index of less than 25 and a smoke development index of less than 50. Regarding noise reduction, industry standards typically require soundproof ceiling tiles having a noise reduction coefficient (NRC) of at least about 0.55 in accordance with ASTM C423.

Sound-insulating ceiling tiles are typically formed via a wet-laid process that uses an aqueous medium to transport the tile components and shape them into the desired structure. The basic process involves first blending various tile components into an aqueous slurry, delivering the slurry to a high head box forming station, and dispensing the slurry to a desired size and thickness via a moving porous screen. Uniform pad. The water is removed and the pad is then dried. The dried mat can be trimmed to a ceiling tile structure by grooving, stamping, coating, and/or laminating the surface to the tile. In a wet lay-up process, water acts as a transport medium for various tile components. However, while facilitating high manufacturing speeds and the ability to use low cost materials (eg, recycled newsprint fibers, recycled corrugated paper, waste polyester fibers, cotton linters, waste fabrics, and the like), the use of water to make soundproof ceilings Tiles also present a number of disadvantages that make the process and the resulting product less desirable.

The wet cloth process uses a large amount of water to transport the components and shape them into a ceiling tile structure. Ultimately, a large amount of water must be removed from the product. Thus, most wet processes provide for water removal by one or more of free or gravity drainage, high vacuum and low vacuum, compression, and evaporation. Unfortunately, these process steps require greater energy requirements to transport and remove water. Thus, disposal of large amounts of water to form tiles and subsequent removal and evaporation of water can provide a typical wet-laid process that is relatively expensive due to high equipment and operating costs.

It is also difficult to form a soundproof ceiling tile having a high sound absorbing property using a wet cloth process. In a wet layup process, the resulting ceiling tile tends to have a sealed surface due to the nature of the ingredients in the wet laydown formulation. Ceiling tiles with a sealed surface typically have a less effective sound barrier because of the lower porosity of the tiles, which makes the tiles less able to absorb sound. The sealed tile surface can actually reflect sound, which is an undesirable feature of the acoustic ceiling tile.

It is believed that these undesirable sound-insulating features are caused by the hydrophilicity of the tile components typically used in wet-laid processes. Cellulosic fibers (such as recycled newsprint), often used as low cost binders and fillers in ceiling tiles, are highly hydrophilic and absorb large amounts of water. Partly due to the hydrophilic components, the wet cloth tile typically has a high initial moisture content of from about 65% to about 75% (i.e., the moisture content of the plate just prior to entering the drying or drying chamber). It will increase the need for evaporation during drying. Therefore, during drying, high surface tension is generated on the tile composition due to the removal of water from the hydrophilic components. Water is a polar molecule that imparts surface tension to other components. This surface tension typically causes the tile surface to be sealed by a less porous structure. In the process, the surface tension pulls the components in the tile closer together, thereby making the structure dense and closing the tile pores. Therefore, wet tile-made ceiling tiles require further processing to perforate the tiles to achieve acceptable noise reduction. Thus, while wet lay-up processes may be acceptable due to increased manufacturing speed and the ability to use low cost materials, the use of water as the transport medium makes the process and the resulting product cost effective when the sound-damping feature is required for the product. Lower.

In some cases, latex adhesives can also be used in acoustical ceiling tiles and are often preferred in wet-laid processes using mineral wool as a matrix fiber. However, latex is often the most expensive ingredient used in ceiling tile formulations; therefore, it is desirable to limit the use of this relatively high cost component. Other binders commonly used in ceiling tiles are starch and cellulosic fibers as described above. However, starch and cellulose are hydrophilic and tend to absorb water during processing and create the aforementioned high surface tension problems.

A common disadvantage of sound-insulating ceiling tiles made using a wet lay-up process is that the tiles formed are typically resulting in higher densities via the mechanisms described above. High density often results in high airflow resistance, which can impair sound absorption. Typically, tiles made in conventional formulations have a density of from about 12 lbs/ft ³ to about 20 lbs/ft ³ , depending on the composition. It also has a noise reduction factor (NRC) of from about 0.55 to about 0.80, depending on the particular composition. For matrix mats having similar compositions, lower densities typically result in lower airflow resistance or higher porosity, thereby improving sound absorption. However, if the composition is different, the correlation between density and porosity is not necessarily as described above.

Alternative adhesive fibers have been developed, but such replacement fibers are still made using hydrophilic components and will therefore exhibit the same disadvantages as seen in existing ceiling tile compositions. For example, U.S. Patent Nos. 6,818,295 and 6,946,506, and U.S. Pat. The inventors of these references indicate that microfibrils mechanically reinforce nonwoven materials to provide improved tensile strength. However, the fibers in these references still consist of a starch matrix that provides a natural polymer to bind the components together. In such cases, it is important because the starch makes any of the materials formed biodegradable. However, if the starch described in these references is used to form a ceiling tile, the resulting tile will exhibit the same disadvantages as seen in wet tile tiles due to the hydrophilicity of the starch. That is, as described above, it is contemplated that the starch matrix will form a high surface tension during water removal and tend to form a sealing surface, thereby reducing the ability of the tile to absorb sound. These references further indicate that the starch matrix can be removed from the fibrous structure and only microfibrils are used. However, in this case, if only the individual microfibrils are used in the ceiling tile without taking advantage of the matrix fiber structure, the microfibrils do not provide an adhesive matrix and strength sufficient to serve as an effective binder in the ceiling tile structure. .

Accordingly, there is a need for a low density nonwoven structure having minimal hydrophilic components that is flat, self-supporting, and that is suitable for use in industrial standards for soundproof ceiling tiles that meet the user's desire for manual cuttability (ie, Thermal properties and acoustic properties).

In general, a low density nonwoven material comprising an inorganic matrix fiber and a synthetic heat bonding fiber is provided. By one method, the low density nonwoven material can be formed into a core or matrix mat having a predetermined basis weight and a low density sufficient to provide a substantially flat, rigid and self-supporting material, the substantially flat, rigid and self-supporting material It is capable of providing thermal and acoustic features sufficient for use as a soundproof ceiling tile. The term flat or flatness as used herein means the degree of deflection in the middle when a 2 ft long panel is placed on a grid. For example, a substantially flat panel can have a degree of deflection of about 0.25 吋 or less. As used herein, "low density" generally refers to about 10 lbs/ft ³ (pcf) or less, and typically ranges from about 7 pcf to about 13 pcf. Again, as discussed in the present invention, "porosity" is quantified by airflow resistance and can be tested in accordance with ASTM C423 and C386. In addition, the present invention contemplates that the preferred thickness of the tile produced using the processes described herein will generally be in the range of from about 0.5 Torr to about 1.0 Torr.

For example, the nonwoven material can form a substantially flat, self-supporting, sagging-resistant core that exhibits a noise reduction factor of at least about 0.55 and a Class A fire rating according to ASTM C423, which has a flame spread index of about ASTM E84. 25 or less and the smoke generation index is about 50 or less. Even with a low density, the core preferably exhibits high flexural strength, but can still be manually cut, such as using a conventional utility knife to cut with a slight or minimal pressure.

In various embodiments, the inorganic matrix fibers are preferably mineral wool, slag wool, asbestos or mixtures thereof, preferably having a slag content of up to about 60% by weight and most preferably from about 10% to about 45% by weight. As used herein, mineral wool slag balls generally refer to by-products of the mineral wool manufacturing process comprising non-fibrous mineral particles having a diameter ranging from about 50 microns to about 500 microns. Suitable inorganic matrix fibers are Thermafiber FRF brand fibers (USG Interiors, Inc., Chicago, Illinois); however, other inorganic matrix fibers such as glass fibers and the like can also be used. Preferably, the inorganic fibers have an average length of from about 0.1 mm to about 4 mm and an average diameter of from about 1 micron to about 15 microns. By one method, the core of the nonwoven material comprises from about 30% to about 95% by weight of asbestos or slag wool.

In various embodiments, the synthetic heat-bonded fibers are preferably one-component or two-component synthetic fibers that, when heated to a suitable temperature, melt or adhere to the surrounding material. Preferably, the nonwoven composite material comprises from about 0.1% to about 50% by weight, and most preferably from about 1% to about 25%, by weight of the synthetic one-component or bicomponent fibers. As used herein, "synthetic" refers to fibers made using components of non-natural origin. For example, the synthetic heat-bonded fiber is preferably composed of a polyacrylic acid, ethylene vinyl acetate, polyester, polyolefin, polyamine, phenol-formaldehyde, polyvinyl alcohol, polyvinyl chloride or a mixture thereof. The melting point of such materials is typically from about 100 °C to about 250 °C. Some of the synthetic heat-bondable fibers that can be used are composed of a polyolefin resin and at least one component exhibits a melting point of from about 125 ° C to about 136 ° C. Fibers composed of materials other than polyolefin resins can also be used and such fibers can provide good properties such as strength, but can be relatively expensive.

By one method, the preferred synthetic heat-bonded fibers are generally non-biodegradable and substantially free of starch, protein, and other naturally occurring polymers, most of which are hydrophilic and will result in what is seen in prior art fibers. Undesired surface tension properties. As discussed further below, the synthetic heat-bonded fibers herein generally retain hydrophobicity even when treated to have a hydrophilic surface to improve dispersion stability.

Preferred synthetic heat bonded fibers have a high surface area associated with fiber length and diameter to provide a high bond surface area. For example, preferred synthetic binder fibers have an average length of less than 3 mm (preferably from about 0.1 mm to about 3 mm), an average diameter of less than 50 microns (preferably from about 5 microns to about 30 microns), but greater than about A large surface area of between 0.5 square meters per gram and preferably between about 1 square meter per gram and about 12 square meters per gram. The surface area is on the order of one to two orders of magnitude greater than the commercially available one-component or two-component heat-bonded fibers, which typically have from 1 to 6 denier fibers. A surface area of from about 0.1 square meters per gram to about 0.4 square meters per gram.

Table 1 below shows a range of surface areas of standard commercially available unfibrillated fibers in denier and densitometer. For example, as shown in the graph, if the fiber has 3 denier filaments and the density is 0.95 g/cm ³ , the surface area of the standard unfibrillated synthetic fiber will be 0.199 m ² /g.

To achieve this high surface area associated with fiber length and diameter, the fibers herein preferably define an elongated fibrous matrix or body and a plurality of microbranches or microfibrils extending outwardly from the outer surface of the elongated fibrous substrate, or microfibril clusters. . For example, a single fiber can define a plurality of microfibrils each having a diameter of from about 0.1 microns to about 10 microns. Suitable high surface area fibrillated fibers are available from Mitsui Chemicals America (Rye Brook, New York) or Minifibers (Johnson City, Tennessee).

In a preferred embodiment, the synthetic heat-bonded fibers are preferably hydrophobic, and thus generally do not result in an increase in surface tension during drying as seen in ceiling tiles of prior art wet-laid formations. The synthetic heat-bonded fibers of the preferred embodiment form a generally porous and bulky structure that provides the desired sound-reducing features at low densities. One reason for the higher porosity of the structure obtained by the salty letter is that there are fewer hydrogen bonds when there is a highly hydrophobic heat-bonding fiber than a structure having more cellulose. On the other hand, the high surface area of the fibrillated synthetic fibers increases the bonding sites, thereby improving the strength without impairing the cuttability.

In some cases, the hydrophobic nature of the synthetic fibers makes it difficult to disperse in the aqueous slurry. To improve dispersion stability, the synthetic heat-bonded fibers may also be surface treated such that one of the outer or outer surfaces is hydrophilic. To make the outer surface hydrophilic, fiber manufacturers introduce certain hydrophilic functional groups, such as carboxyl (-COOH) or hydroxyl (-OH), into the polymer used to form the fibers. In the case of a hydrophilic outer surface, the synthetic heat-bonded fibers are generally relatively stable in aqueous slurries.

The nonwoven material herein generally produces a desired noise reduction factor of at least 0.55 and greater. At least two mechanisms are responsible for the noise reduction characteristics at a core density of about 7 to 13 pcf. First, as described above, the preferred synthetic heat-bonded fibers are hydrophobic, which reduces the surface tension of the core during drying. Thus, hydrophobic fibers generally avoid pore closure in the surface and body of the core being formed, and this problem can occur in prior art hydrophilic fibers. In addition, it has also been observed that even if the fibers are treated to have a hydrophilic surface, the synthetic fibrillated heat-bonded fibers generally exhibit hydrophobic properties to reduce the surface tension after drying.

The hydrophilically treated fiber still exhibits a hydrophobic tendency during drying because the treated fiber has just enough hydrophilic functional groups attached to the hydrophobic polymer chain so that it can be suspended in water and together with other ingredients. dispersion. However, these fibers as a whole are still hydrophobic and have extremely low water absorption. When the polymer melts, it does not lose these groups and therefore retains a hydrophobic tendency.

Second, at least a portion of the synthetic heat-bonded fibers are set to melt at a predetermined temperature, wherein the matrix fibers are combined with other core components. In the case of fibrillated synthetic heat-bonded fibers, it is preferred that there is no bond between any of the core components prior to the predetermined melting temperature. Therefore, even with the wet-laid process, the inorganic matrix fibers and other components will generally exhibit a more natural/bulk configuration or form as seen in the air-laid process. In particular, in the case of inorganic matrix fibers using mineral wool, the mats formed generally become extremely bulky or bulky because the fibers are relatively hard and form a bulky structure. Therefore, once the core finally reaches the melting point of the synthetic binder fiber after drying, the binder will fuse the matrix of the hard mineral wool into the bulk structure. After cooling, the fibrillated synthetic binder fibers fix the tile components and impart rigidity to the tile while having a bulky structure. Because synthetic fibers do not exhibit the increased surface tension of prior art adhesives, the resulting bulky structure is typically left intact without densification due to surface tension caused by water evaporation.

The nonwoven core may include other components as appropriate. For example, the core may include other fillers as needed, such as cellulosic fibers (i.e., newsprint), calcium carbonate, perlite, glass beads, clay, granules, cork, and the like. Functional chemicals such as zeolites, activated carbon, and the like can also be added to the matrix mat to provide air purifying capabilities, if desired. In addition to inorganic matrix fibers and synthetic heat-bonded fibers, the core may also include other fibers as appropriate, such as natural fibers (linen, bamboo, cellulose, sisal and the like), glass fibers, other inorganic fibers, Organic fibers and mixtures thereof. If desired, the nonwoven material can also include a powdered, liquid or latex resin applied to one or more surfaces of the formed matrix mat or infiltrated into the formed mat to provide additional rigidity, bonding, Water barrier or other functional properties. For example, up to about 30% by weight of the resin can be applied to one or both surfaces of the substrate mat.

Additionally, the matrix mat formed can comprise one or more layers of nonwoven material. If multiple layers are formed, each layer may have similar or different properties to other layers as desired for a particular application, such as similar or different basis weights, densities, and compositions. The multilayer can be formed by laminating a plurality of matrix mats together or can be formed in-line using a multi-head molding machine.

Nonwoven materials comprising inorganic matrix fibers and synthetic heat bonding fibers can be formed into a core suitable for soundproof ceiling tiles wherein the nonwoven material is formed using any standard process such as a wet cloth layer, a dry cloth layer or an air cloth layer forming process. For example, if a wet lay-up process is used, the synthetic heat-bonded fibers are preferably first de-fibered using a hydraulic pulper, a high-frequency disintegrator, a refiner, or other suitable equipment. The defibrated synthetic fibers are then blended into an aqueous slurry. By one method, the solids content of the slurry is preferably from about 1% to about 15%. The slurry can then be used to form from about 0.1% to about 50% by weight of the synthetic heat-bonded fibers and from about 50% to about 95% by weight of the inorganic matrix fibers (such as ore) using a standard wet-laid high-level headbox. Non-woven core of cotton, slag wool and/or asbestos).

After the core is formed, the water is then removed by gravity drainage, vacuum, and/or heating as needed. The typical initial moisture content of the nonwoven material of the present invention (i.e., the moisture content of the sheet immediately before entering the drying or drying chamber) is about 60% when a vacuum of from about 7 Torr to about 10 Torr is applied. In contrast, boards made from standard materials typically have a moisture content of 70%. Since the synthetic fiber content is increased, the initial moisture is reduced. If desired, pressure can be used to provide a smooth surface to the pad and help control the final density. Preferably, the drying oven is operated at about 300 °F or at least about 5 °F to about 50 °F above the melting point of the synthetic bonded fibers to ensure adequate melting and bonding of the tile components. If desired, the core or pad can be cooled and/or enclosed in an air circulation system after heating.

In order to achieve a uniform distribution of the nonwoven mat, a fully dispersed synthetic heat-bonded fiber is preferred. It has been found that the optimum dispersion of synthetic fibers and inorganic matrix fibers can be achieved using a slurry temperature of about 50 ° C, but it has been shown to work well in the range of from about 30 ° C to about 70 ° C. It is important to believe that this temperature range is important because some commercially available fibrillated synthetic fibers are sold as wet laps, which require repulping when used. Higher temperatures help to reduce water reduction time and dispersion. Next, the slurry is mixed for about 10 minutes to about 30 minutes until the slurry is substantially homogeneous. Preferably, the synthetic heat-bonded fibers are also dispersed in water prior to the addition of other slurry components to ensure good dispersion quality. To verify dispersion, the glass or blue glass is used to inspect the slurry to ensure complete dispersion of the synthetic fibers.

One reason why it is important to ensure that sufficient time is spent on complete dispersion is that some of the commercially available fibrillated synthetic fibers, as just mentioned, are in the form of mats that need to be dispersed prior to use. Complete dispersion or repulping ensures that the fibers provide the greatest number of bonding sites, thus improving mechanical strength and porosity. If the dispersion is insufficient, the fibers may stick together and they may lose their effectiveness as a binder. On the other hand, some commercially available synthetic fibers are dry staple fibers and do not require a significant amount of time to achieve adequate dispersion.

Further, as described above, in order to improve the dispersion quality, the synthetic fiber may also be surface-treated to have hydrophilicity at least on the outer surface thereof. In the case of bicomponent fibers, mechanical pretreatment can make the fibers more suitable for making ceiling tiles. The pretreatment comprises drying the fibers, grinding the fibers and forming the fibrils. The dry milling process itself also produces sufficient force and shear to further fibrillate the fibers.

The advantages and specific examples of the nonwoven materials described herein are further illustrated by the following examples; however, the particular materials and amounts thereof recited in such embodiments, as well as other conditions and details, should not be construed as limiting the nonwoven material. All percentages mentioned above and below are by weight unless otherwise indicated.

Example

Example 1

Approximately 75 grams of E 380F dry staple polyvinyl syrup (Minifibers) was dispersed in water and then mixed with about 425 grams of mineral wool at about 5% consistency for about 4 minutes (about 15% polyethylene slurry on a dry solids basis). The slurry was poured into a 14 x 14 inch shaped box. The excess water was first drained by gravity and then further removed using a vacuum of about 7" Hg. The formed plates were placed in a dry box for about 3 hours at about 300 °F without pressing. The plate becomes relatively rigid. The resulting tile exhibits the following characteristics:

Example 2

Similar to Example 1, about 75.6 grams of E 380F fibers were dispersed in water and mixed with about 428.4 grams of mineral wool for 4 minutes at a consistency of 5% (about 15% E380F fiber). As in Example 1, the raw materials were poured into a molded case. Excess water was first drained and then further removed using a vacuum of about 8" Hg for about 30 seconds. The plate was then pressed to about 0.45" thick and dried in a 300 °F oven for 3 hours. After cooling, the plate becomes relatively rigid. The resulting board exhibits the following characteristics:

Example 3

Fybrel E790 (Mitsui Chemicals America) in the form of a wet lap was first dispersed in a hydraulic pulper at a consistency of about 4.8%. After mixing about 47.1 grams of Fybrel 790 with about 267 grams of mineral wool for 4 minutes, the slurry was poured into a 14" x 14" molded box (about 15% Fybrel). The excess water was first drained by gravity and then further removed using a vacuum of about 8" Hg for about 30 seconds. The plate was then pressed to about 0.295" thick and dried in a 300 °F oven for 3 hours. After cooling, the plate becomes relatively rigid. The board exhibits the following characteristics:

Comparative Example 4

About 47.1 grams of Fybrel E790 (Mitsui Chemicals America) was mixed with about 219.8 grams of mineral wool, about 47.1 grams of newsprint, and about 25 grams of calcium carbonate for about 4 minutes (about 13.8% Fybrel). Next, as in Example 1, the slurry was poured into a 14" x 14" molded case. Excess water was first drained by gravity, followed by further removal using a vacuum of about 11" Hg. The plate was then pressed to about 0.265" thick and dried in a 300 °F oven for about 3 hours. After cooling, the plate becomes relatively rigid. The board exhibits the following characteristics:

It should be noted that in Comparative Example 4, 13.5% cellulose fiber (newspaper) was used in the formulation. Hydrophilic cellulosic fibers produce high surface tension to densify the board during drying. Therefore, the density is high, the porosity is low, and the NRC is low.

Comparative Example 5

About 61.1 grams of SS 93510, a hydrophilic fibrillated PE fiber (Minifibers), was mixed with about 346 grams of mineral wool at a consistency of 4.5% for about 4 minutes (about 15% PE fiber). The slurry was then poured into a 12" x 12" molded box. The excess water is first drained by gravity and then further removed using a vacuum. The vacuum is then used to draw hot air through the mat. When the pad temperature reached 300 °F, the pad was heated for about 8 minutes. After cooling, the plate becomes relatively rigid.

The board exhibits the following characteristics:

It should be noted that in this Comparative Example 5, the high density achieved was the result of through-air drying. The pad is placed under vacuum to allow hot air to pass through the pad, thereby densifying the pad. This example also demonstrates that venting drying helps maintain porosity during drying, thereby maintaining a better NRC at similar densities.

Example 6

First, about 108 grams of ESS50F, a hydrophilic fibrillated PE fiber (Minifibers), was dispersed in water at a consistency of about 2%. The dispersed fibers were then mixed with about 403 grams of mineral wool for about 4 minutes (about 21% PE fibers). The slurry was then poured into a 14" x 14" molded box. The excess water was first drained by gravity, followed by further removal using a vacuum of about 6.8" Hg. The plate was then pressed to about 0.49 inches thick and dried in a 300 °F oven for about 3 hours. After cooling, the plate became relatively Rigid. The board exhibits the following characteristics:

Comparative Example 7

First, about 75.6 grams of E990 having a relatively long fiber length (2.1 mm), a fibrillated PE fiber (Minifibers), was dispersed in water. After mixing with about 428.4 grams of mineral wool for about 4 minutes, about 151 grams of swellable perlite (USG, Red Wing, MN) (about 11.5% PE fiber) was added at the end of the mixing. The slurry was then poured into a 14" x 14" molded box. The excess water was first drained by gravity, followed by further removal using a vacuum of about 6.8" Hg for about 30 seconds. After pressing to about 0.71 吋 thick, the plate was dried in a 300 °F oven for about 3 hours. After cooling, the plate was It becomes relatively rigid. The resulting board exhibits the following characteristics:

It should be noted that in this Example 7, it was shown that the addition of the lightweight filler tumbling perlite did not impair the sound absorbing effect. Generally, in a typical wet-laid process, the more perlite is added to the matrix mat, the lower the NRC. In this case, the high density is the result of the addition of the filler. This is important because perlite can be added to the ceiling tile composition to improve surface burning and strength characteristics.

It will be appreciated that those skilled in the art will be able to describe and describe the details, materials, and process conditions of the materials that are described herein in order to explain the nature of the non-woven material in the principles and scope as set forth in the appended claims. In addition, any references cited herein are also incorporated herein by reference in their entirety.

Claims (19)

A sound-insulating ceiling tile comprising: a substantially flat, self-supporting nonwoven core comprising inorganic matrix fibers and synthetic heat-bonded fibers; the synthetic heat-bonded fibers having an average fiber length of less than about 3 mm and an average fiber diameter being lower than About 30 microns and having a bonded surface area of from about 0.5 square meters per gram to about 15 square meters per gram; and the core has a density of from about 7 pcf to about 13 pcf; wherein the synthetic heat-bonded fiber has a body portion and a plurality of from the body Partially extending microfibrils, and wherein the combination of the body portion and the plurality of microfibrils provides the bonded surface area, and wherein the acoustical ceiling tile exhibits a noise reduction factor of at least about 0.55. The acoustical ceiling tile of claim 1, wherein the microfibrils have a diameter in the range of from about 0.1 micron to about 10 microns. The sound-insulating ceiling tile of claim 1, wherein the synthetic heat-bonding fiber comprises from about 0.1% by weight to about 50% by weight of the core. The sound-insulating ceiling tile of claim 1, wherein the synthetic heat-bonded fiber is formed of a material selected from the group consisting of polyacrylic acid, ethylene vinyl acetate, polyester, polyolefin, polyamine, phenol - Formaldehyde, melamine-formaldehyde, urea-formaldehyde, polyvinyl alcohol, polyvinyl chloride and mixtures thereof. A sound-insulating ceiling tile according to claim 1, wherein the synthetic heat-bonding fiber has a melting point in the range of from about 100 ° C to about 250 ° C. The sound-insulating ceiling tile of claim 1, wherein the synthetic heat-bonding fiber is a bicomponent fiber. A sound-insulating ceiling tile according to claim 6 wherein the one component of the bicomponent fiber has a melting point higher than the melting point of the other component. A sound-insulating ceiling tile according to claim 1, wherein the core has a Class A fire rating according to ASTM E84, a flame spread index of less than about 25 and a smoke development index of less than about 50. . A sound-insulating ceiling tile comprising: a substantially flat and self-supporting nonwoven core of an inorganic matrix fiber and a synthetic heat-bonding fiber; a plurality of micro-branches extending from the outer surface of the synthetic heat-bonded fibers to provide a similar size The unbonded fibers are associated with an increased bond surface area associated with their length and diameter; and the core has a density of from about 7 pcf to about 13 pcf; wherein the acoustical ceiling tile exhibits a noise reduction factor of at least about 0.55. A sound-insulating ceiling tile according to claim 9 wherein said synthetic heat-bonded fibers have an average fiber length of less than about 3 mm, an average fiber diameter of less than about 30 microns, and said bonded surface area of about 0.5 square meters. The gram is about 15 square meters / gram. A sound-insulating ceiling tile according to claim 10, wherein the synthetic heat-bonding fibers comprise from about 0.1% to about 50% by weight of the core. A sound-insulating ceiling tile according to claim 10, wherein the synthetic heat-bonding fibers are hydrophobic. A method of forming a sound-insulating ceiling tile, comprising: preparing an aqueous slurry comprising synthetic heat-bonded fibers and inorganic matrix fibers, the synthetic heat-bonded fibers having a plurality of micro-branches extending from an outer surface thereof to provide an adhesive surface area; The aqueous slurry is formed into a nonwoven material having a substantially flat and self-supporting core of up to about 7 pcf to about 13 pcf; and the core is formed into the acoustical ceiling tile to exhibit a noise reduction factor of at least about 0.55. The method of claim 13, wherein the aqueous slurry has a core solids content of from about 1% by weight to about 15% by weight. The method of claim 13, wherein the aqueous slurry is blended at a temperature of from about 30 ° C to about 70 ° C. The method of claim 13, wherein the synthetic thermal bonding fibers have an average fiber length of less than about 3 mm, an average fiber diameter of less than about 30 microns, and the bonding surface area of at least about 0.5 square meters per gram. Up to about 12 square meters / gram. The method of claim 13, wherein the synthetic heat-bonded fibers comprise hydrophobic heat-bonding fibers. The method of claim 17, wherein the hydrophobic heat-bonding fibers have a hydrophilic surface sufficient to allow dispersion in the aqueous slurry. The method of claim 16, wherein the synthetic heat-bonded fibers comprise a hydrophobic heat-bonding fiber.