Rotational forming glass fiber

Abstract

A method for forming spin fibers (e.g., glass fibers) having a more uniform or restricted fiber diameter and / or length distribution is disclosed. Spin fibers having improved characteristic distribution(s) across the volume of the fibers facilitate the formation of improved nonwoven fibrous mats and products formed from the mats.

Description

Technology Field

[0001] Cross-reference regarding related applications

[0002] This application claims priority and all benefits to International Patent Application PCT / US2023 / 084218 filed on December 15, 2023, the contents of which are incorporated herein by reference in their entirety.

[0003] Technology field

[0004] The general concept of the present invention relates to an apparatus and method for fiberizing mineral fibers, such as glass fibers, from molten mineral materials using a spinning process, as well as to the fibers themselves and articles comprising the fibers. Background Technology

[0005] The production of mineral fibers, such as glass fibers, by a spinning process is well known. For example, reference is made to U.S. Patents No. 5,582,841; No. 7,856,853; No. 8,087,265; and No. 8,250,884, each of which is incorporated herein by reference in its entirety. In such a process, molten glass is fed into a metal spinner rotating at a high rotational speed at a high temperature. The spinner has a peripheral wall containing a plurality of orifices. The molten glass flows through the orifices by centrifugal force and forms a stream of molten glass of a small diameter. The stream is directed downward toward a collection surface by an annular blower surrounding the spinner. The flow generated by the blower elongates the molten glass stream to a finer diameter, and the stream is cooled to form glass fibers. An annular burner is also positioned around the spinner, and combustion gases and heat from the burner are directed downward, providing a fiber-thinning environment suitable for tensile the initial stream of glass to a desired final diameter. The downward annular flow of high-temperature gas enables the tensile of the molten mineral material stream into mineral fibers by the blower and also maintains the spinner at a temperature suitable for fiberization.

[0006] As an example, as illustrated in FIG. 1, a fiber manufacturing device or fiberizer (10) comprises a centrifuge or spinner (12) fixed to a rotatable hollow shaft or spindle (14). In particular, the spinner (12) is fixed to the hub (54) of a quill (64) at the lower end of the rotatable shaft or spindle (14). It is known in the art to rotate the spinner (12) by rotating the spindle (14). The spinner (12) comprises a base (16) extending from the hub (54) to a peripheral wall (18). A plurality of orifices (20) are arranged around the outer periphery of the peripheral wall (18) for centrifuging a molten material, for example, fibers (22) of glass.

[0007] A stream (78) of molten glass is supplied to the spinner (12). Conventional supply equipment (82) may be used to supply the stream (78) of molten glass. Such molten glass supply equipment is well known in the art and, therefore, will not be discussed in detail in this specification. The glass in the stream (78) falls into the chamber (42) of the spinner (12), is directed toward the peripheral wall (18) by centripetal force, and flows outward to form a glass accumulation or head (90). Subsequently, the glass flows through the orifice (20) to form a primary fiber (22), which is heated and stretched by a burner (24) and an annular blower (28).

[0008] The rotation of the spinner (12) (as illustrated by the circular arrow (a) in FIG. 1) centrifuges the molten glass through the orifice (20) within the spinner's main wall (18) to form primary fibers (22). The primary fibers (22) are maintained in a soft, achievable state by the heat of the annular burner (24). An annular blower (28) uses air induced through the passage (30) to pull the primary fibers (22) and further slender them into secondary fibers (32) suitable for use in products such as wool insulating material. The secondary fibers (32) are collected on a conveyor (not shown) to form a product such as a glass wool pack.

[0009] The hollow quill (64) is press-fitted into a borehole formed through the center of the hub (54) and secured in place by three circumferentially spaced fixing pins (66). The upper end of the quill (64) is screwed into the lower end of a hollow drawbar (68). The quill (64) is preferably further cooled by water circulating through an annular cooling jacket (70) placed around the spindle (14) and the quill (64) and over the hub (54). The quill (64) and the hub (54) are preferably made of a low thermal expansion alloy to minimize differential thermal expansion between them.

[0010] The radiation shield (52) may comprise a plurality of individual plates (52a, 52b, 52c). The plates may be connected to the hub (54) of the quill (64). The plates suppress convection from the base of the spinner, suppress infrared energy from escaping from the base of the spinner (12), reduce the thermal gradient along the height of the peripheral sidewall (18), thereby suppressing devitrification within the glass head (90) and controlling the temperature of the glass when the glass passes through the orifice (20) at the lower edge of the peripheral sidewall (18). The upper shield (52a) is preferably truncated to follow the base wall (16) of the spinner (12). The lower shields (52b, 52c) may be truncated or flat to allow space between the shields. The shield (52) may be formed of stainless steel or a refractory metal, such as HASTELLOY alloy, transition metal nickel-based high-temperature alloy. One material particularly suitable for the shield is HASTELLOY X alloy, available from Haines International, Cocomo, Indiana, USA. HASTELLOY X alloy comprises 47 wt% Ni, 22 wt% Cr, 18 wt% Fe, 9 wt% Mo, 1.5 wt% W, 0.1 wt% C, 1 wt% Mn (max), 1 wt% Si (max), and 0.008 wt% B (max).

[0011] The spinner (12) is clamped to the hub (54) on the quill (64) by a clamping ring (55) (at the lower end of the spindle (14)). A quill pan (67) can be positioned below the radiation shield (52) to provide a stable flow pattern for an air stream containing elongated fibers. In this way, a more stable "veil" (i.e., an annular flow of fibers and air downward away from the spinner (12)) is maintained. The quill pan (67) can have any shape sufficient to cover a significant portion of the radiation shield (52) and the bottom of the spinner (12). Like the spinner (12), the quill pan (67) can be mounted on the hub (54).

[0012] Despite these (and other) developments in spinner techniques, there are still problems in reliably and consistently forming glass fibers with desired fiber diameter and / or fiber length by a spin forming process. As an example, the fiber diameter distributions of various conventional spin-formed glass fibers are shown in FIGS. 2a to 2d.

[0013] FIG. 2a shows a graph (210) of the fiber diameter distribution for commercially available unbonded loosefill (ULF) glass fiber materials. ULF fibers are typically spin-forming fibers that are not held together by a binder. ULF fibers are generally used in building insulation applications.

[0014] Referring to graph (210), various characteristics of this first ULF material are shown in Table 1.

[0015] [Table 1]

[0016]

[0017] In Table 1, "Peak Index" refers to the peak identifier from left to right—where the peak is shown as a dashed line—; "Peak Type" refers to the type of model used to fit the data; "Area Intg" refers to the integrated area of ​​the fitted peak; "Area IntgP" refers to the percentage of the total integrated area for each fitted peak; "Center Gravity" refers to the center of the fitted peak; "Max Height" refers to the maximum value of the fitted peak; and "FWHM" refers to the width of the peak at half the maximum height of the peak.

[0018] In the graph (210) of FIG. 2a, rotary fibers were generated with a target diameter of approximately 3.1 μm when measured using a known air flow method. The graph (210) shows the fiber diameter distribution when measured using an ISO 13322-2 compliant method and plotted as fiber volume %. Data measured according to the ISO 13322-2 compliant approach (Camsizer) were analyzed using the Peak Deconvolution App (v2.00) of OriginPro 2023, data analysis software sold by OriginLab Corp., Northampton, Massachusetts, USA (constant baseline; fitting until converged to obtain the displayed results).

[0019] Ideally, 100% of the generated fibers would have a fiber diameter of approximately 3.1 μm. However, spin fiber generation is a complex process involving many variables, some of which can only be controlled. Consequently, the fiber diameter distribution (i.e., the area under the graph) shows that a large amount of fibers have a diameter greater than 3.1 μm, and some fibers have a diameter approaching 25 μm. For a target fiber diameter of 3.1 μm, this wide dispersion of fiber diameters (e.g., from approximately 1 μm to approximately 25 μm), where most fibers have a diameter greater than 6 μm, is not ideal. In other words, for many applications, reducing the dispersion of fiber diameters relative to the target fiber diameter and / or increasing the amount of fibers with diameters closer to the target fiber diameter can improve the products or applications using the fibers.

[0020] FIG. 2b shows a graph (220) of the fiber diameter distribution for other commercially available unbonded loose-fill (ULF) glass fiber materials. ULF fibers are typically spin-forming fibers that are not held together by a binder. ULF fibers are generally used in building insulation applications.

[0021] Referring to graph (220), various characteristics of this second ULF material are shown in Table 2.

[0022] [Table 2]

[0023]

[0024] In Table 2, "Peak Index" refers to the peak identifier from left to right—where the peak is shown as a dashed line—; "Peak Type" refers to the type of model used to fit the data; "Area Intg" refers to the integrated area of ​​the fitted peak; "Area IntgP" refers to the percentage of the total integrated area for each fitted peak; "Center Gravity" refers to the center of the fitted peak; "Max Height" refers to the maximum value of the fitted peak; and "FWHM" refers to the width of the peak at half the maximum height of the peak.

[0025] In the graph (220) of FIG. 2b, the spinning fiber was measured to have an effective fiber diameter of 2.8 μm to 3 μm when measured using a known air flow method. The graph (220) shows the fiber diameter distribution when measured using an ISO 13322-2 compliant method and plotted as fiber volume %. Data measured according to the ISO 13322-2 compliant approach (Camsizer) were analyzed using the Peak Deconvolution App (v2.00) of OriginPro 2023, data analysis software sold by OriginLab Corp., Northampton, Massachusetts, USA (constant baseline; fitting until converged to obtain the displayed results).

[0026] Ideally, 100% of the generated fibers would have fiber diameters within this effective range. However, spin fiber generation is a complex process involving many variables, some of which can only be controlled. Consequently, the fiber diameter distribution (i.e., the area under the graph) shows that a large amount of fibers have diameters exceeding this range (i.e., exceeding 3 μm), and some fibers are measured to have diameters approaching 24 μm. For a target fiber diameter of 2.9 μm (i.e., 2.8 μm to 3 μm), this wide dispersion of fiber diameters (e.g., about 1 μm to about 24 μm), where most fibers have diameters exceeding 6 μm, is not ideal. In other words, for many applications, reducing the dispersion of fiber diameters relative to the target fiber diameter and / or increasing the amount of fibers with diameters closer to the target fiber diameter can improve the products / applications using the fibers.

[0027] FIG. 2c shows a graph (230) of the fiber diameter distribution for other commercially available unbonded loose-fill (ULF) glass fiber materials. ULF fibers are typically spin-forming fibers that are not held together by a binder. ULF fibers are generally used in building insulation applications.

[0028] Referring to graph (230), various characteristics of this third ULF material are shown in Table 3.

[0029] [Table 3]

[0030]

[0031] In Table 3, "Peak Index" refers to the peak identifier from left to right—where the peak is shown as a dashed line—; "Peak Type" refers to the type of model used to fit the data; "Area Intg" refers to the integrated area of ​​the fitted peak; "Area IntgP" refers to the percentage of the total integrated area for each fitted peak; "Center Gravity" refers to the center of the fitted peak; "Max Height" refers to the maximum value of the fitted peak; and "FWHM" refers to the width of the peak at half the maximum height of the peak.

[0032] In the graph (230) of FIG. 2c, the spinning fiber was measured to have an effective fiber diameter of 2.8 μm to 3 μm when measured using a known air flow method. The graph (230) shows the fiber diameter distribution when measured using an ISO 13322-2 compliant method and plotted as fiber volume %. Data measured according to the ISO 13322-2 compliant approach (Camsizer) were analyzed using the Peak Deconvolution App (v2.00) of OriginPro 2023, data analysis software sold by OriginLab Corp., Northampton, Massachusetts, USA (constant baseline; fitting until converged to obtain the displayed results).

[0033] Ideally, 100% of the generated fibers would have fiber diameters within this effective range. However, spin fiber generation is a complex process involving many variables, some of which can only be controlled. Consequently, the fiber diameter distribution (i.e., the area under the graph) shows that a large amount of fibers have diameters exceeding this range (i.e., exceeding 3 μm), and some fibers are measured to have diameters greater than 25 μm. For a target fiber diameter of 2.9 μm (i.e., 2.8 μm to 3 μm), this wide dispersion of fiber diameters (e.g., about 1 μm to about 25 μm), where most fibers have diameters greater than 6 μm, is not ideal. In other words, for many applications, reducing the dispersion of fiber diameters relative to the target fiber diameter and / or increasing the amount of fibers with diameters closer to the target fiber diameter can improve the products / applications using the fibers.

[0034] FIG. 2d shows a graph (240) of the fiber diameter distribution for a commercially available special material in the form of chopped glass microfibers. These special glass fibers are spin-forming fibers that are chopped to shorten their length. The special glass fibers are not held together by a binder. These special glass fibers can be used as reinforcing or filler materials.

[0035] Referring to graph (240), various characteristics of special glass fiber materials are shown in Table 4.

[0036] [Table 4]

[0037]

[0038] In Table 4, "Peak Index" refers to the peak identifier from left to right—where the peak is shown as a dashed line—; "Peak Type" refers to the type of model used to fit the data; "Area Intg" refers to the integrated area of ​​the fitted peak; "Area IntgP" refers to the percentage of the total integrated area for each fitted peak; "Center Gravity" refers to the center of the fitted peak; "Max Height" refers to the maximum value of the fitted peak; and "FWHM" refers to the width of the peak at half the maximum height of the peak.

[0039] In the graph (240) of FIG. 2d, the spin fiber was commercially available with an effective fiber diameter of approximately 3.2 μm. The graph (240) shows the fiber diameter distribution when measured using an ISO 13322-2 compliant method and plotted as fiber volume %. Data measured according to the ISO 13322-2 compliant approach (Camsizer) were analyzed using the Peak Deconvolution App (v2.00) of OriginPro 2023, data analysis software sold by OriginLab Corp., Northampton, Massachusetts, USA (constant baseline; fitting until converged to obtain the displayed results).

[0040] Ideally, 100% of the generated fibers would have a fiber diameter of approximately 3.2 μm. However, spin fiber generation is a complex process involving many variables, some of which can only be controlled. Consequently, the fiber diameter distribution (i.e., the area under the graph) shows that a large amount of fibers have a diameter greater than 3.2 μm, and some fibers have a diameter approaching 24 μm. For a target fiber diameter of 3.2 μm, this wide dispersion of fiber diameters (e.g., from approximately 1 μm to approximately 24 μm), where most fibers have a diameter greater than 5 μm, is not ideal. In other words, for many applications, reducing the dispersion of fiber diameters relative to the target fiber diameter and / or increasing the amount of fibers with diameters closer to the target fiber diameter can improve the products or applications using the fibers.

[0041] In light of the above, there is an unmet need for a spinning fiber generating process capable of producing glass fibers with improved fiber diameter and / or length distribution, for the collection of fibers with improved distribution, and for products / applications using said fibers.

[0042] In the above regard, modifications to the spin fiber forming process enable the production of fibers having a more uniform fiber diameter and / or length distribution. An alternative concept of the present invention includes this new method for producing spin fibers, the new spin fibers themselves, a sizing formulation suitable for use with the new spin fibers, a package of spin fibers (e.g., having an improved fiber distribution), a nonwoven mat made of the new spin fibers, and downstream applications for the mats (e.g., a surface material for ceiling tiles).

[0043] In an exemplary embodiment, a method for manufacturing mineral fibers is disclosed. The method comprises the steps of: rotating a spinner having a peripheral wall comprising a plurality of orifices; feeding molten mineral material to the rotating spinner to centrifuge a stream of molten mineral material through the orifices; mixing combustion air and combustion gas and feeding the mixture to an annular burner located around the spinner; creating an annular flow of air induced in a passage located between the annular burner and an annular blower; directing the hot gas from the annular burner and the annular flow of air induced toward the spinner and the stream of molten mineral material to heat the spinner and elongate the stream of molten mineral material into a plurality of mineral fibers; and directing a source of cooling air to a quill fan located below the spinner through a hollow quill extending through the spinner, wherein the cooling air is delivered to the quill fan at a flow rate of about 30 cubic feet / min to about 60 cubic feet / min.

[0044] In some exemplary embodiments, the quill fan is cooled to a temperature of less than 750℉.

[0045] In some exemplary embodiments, the method further comprises the step of controlling the spinner to rotate at a speed of about 900 rpm (revolutions per minute) to about 2,400 rpm. In some exemplary embodiments, the method further comprises the step of controlling the spinner to rotate at a speed of about 1,800 rpm to about 2,400 rpm.

[0046] In some exemplary embodiments, hot gas from an annular burner is directed toward a stream of spinner and molten mineral material at a flow rate of about 240 cubic feet / min to about 300 cubic feet / min.

[0047] In some exemplary embodiments, an annular blower outputs about 410 cubic feet / min of air to create an annular flow of induced air.

[0048] In some exemplary embodiments, the mineral fiber is a glass fiber.

[0049] In some exemplary embodiments, the mineral fiber has an average diameter of less than 6 μm. In some exemplary embodiments, the mineral fiber has an average diameter of less than 5 μm. In some exemplary embodiments, the mineral fiber has an average diameter of less than 4 μm. In some exemplary embodiments, the mineral fiber has an average diameter of less than 3 μm.

[0050] In some exemplary embodiments, the mineral fiber comprises at least 10,000 distinct fibers; the mineral fiber has an average fiber diameter x; and x is less than the median fiber diameter of the mineral fiber.

[0051] In some exemplary embodiments, the mineral fiber comprises at least 10,000 distinct fibers; the mineral fiber has a target generated fiber diameter y; the mineral fiber has an average fiber diameter x; and y < 2x.

[0052] In some exemplary embodiments, the mineral fiber comprises at least 10,000 distinct fibers; the mineral fiber has a target generated fiber diameter of less than 6.5 μm; the mineral fiber has an average fiber diameter x; and the standard deviation from x is less than 3.5 μm.

[0053] In some exemplary embodiments, the standard deviation from x is less than 3.0 μm. In some exemplary embodiments, the standard deviation from x is less than 2.5 μm.

[0054] In some exemplary embodiments, the mineral fiber comprises at least 10,000 distinct fibers; the mineral fiber has a fiber diameter distribution having two Gaussian peaks; the two Gaussian peaks represent ≥ 85% of the volume of the mineral fiber; and ≥ 40% of the volume of the mineral fiber is represented by a Gaussian peak corresponding to the minimum diameter of the mineral fiber.

[0055] In some exemplary embodiments, the mineral fibers do not contain any fibers with a diameter greater than 22 μm. In some exemplary embodiments, the mineral fibers do not contain any fibers with a diameter greater than 20 μm. In some exemplary embodiments, the mineral fibers do not contain any fibers with a diameter greater than 16 μm. In some exemplary embodiments, the mineral fibers do not contain any fibers with a diameter greater than 15 μm. In some exemplary embodiments, the mineral fibers do not contain any fibers with a diameter greater than 14 μm.

[0056] In some exemplary embodiments, the mineral fiber has an average formed (i.e., undone) length greater than 50.8 mm (2 inches). In some exemplary embodiments, the mineral fiber has an average formed length in the range of about 76.2 mm (3 inches) to about 304.8 mm (12 inches). In some exemplary embodiments, the mineral fiber has an average formed length in the range of more than 50.8 mm (2 inches) and less than or equal to 152.4 mm (6 inches).

[0057] In an exemplary embodiment, a package of spin-forming fibers is disclosed. The package comprises at least 10,000 distinct fibers, and the fibers have an average fiber diameter x; the fiber diameter distribution of the fibers has a standard deviation from x of less than 3.5 μm.

[0058] In some exemplary embodiments, the standard deviation from x is less than 3.0 μm. In some exemplary embodiments, the standard deviation from x is less than 2.5 μm.

[0059] In some exemplary embodiments, the fiber has an average diameter of less than 5 μm. In some exemplary embodiments, the fiber has an average diameter of less than 4 μm. In some exemplary embodiments, the fiber has an average diameter of less than 3 μm.

[0060] In some exemplary embodiments, the mineral fiber has an average formed (i.e., undone) length greater than 50.8 mm (2 inches). In some exemplary embodiments, the mineral fiber has an average formed length in the range of about 76.2 mm (3 inches) to about 304.8 mm (12 inches). In some exemplary embodiments, the mineral fiber has an average formed length in the range of more than 50.8 mm (2 inches) and less than or equal to 152.4 mm (6 inches).

[0061] In some exemplary embodiments, the average aspect ratio of the fibers is in the range of 850 to 5,000. In some exemplary embodiments, the average aspect ratio of the fibers is in the range of 850 to 2,000.

[0062] In some exemplary embodiments, x is less than the median fiber diameter of the fiber.

[0063] In some exemplary embodiments, 90% of the fibers have a diameter ≤ 1.525x.

[0064] In some exemplary embodiments, the fiber has a curvature greater than 0.043.

[0065] In some exemplary embodiments, the fiber has a curvature of at least 0.055.

[0066] In some exemplary embodiments, the fiber has a curvature in the range of 0.050 to 0.060.

[0067] In some exemplary embodiments, the fiber is a glass fiber.

[0068] In some exemplary embodiments, the mineral fiber comprises at least 10,000 distinct fibers; the mineral fiber has a fiber diameter distribution having a first Gaussian peak and a second Gaussian peak; and the first Gaussian peak and the second Gaussian peak represent ≥ 85% of the volume of the mineral fiber.

[0069] In some exemplary embodiments, ≥ 40% of the volume of the mineral fiber is represented by a first Gaussian peak corresponding to the minimum diameter of the mineral fiber.

[0070] In some exemplary embodiments, the fiber comprises a sizing composition applied to the surface of the fiber; the sizing composition is an aqueous composition comprising water, a silane coupling agent, at least one organic acid, and a cationic surfactant.

[0071] In some exemplary embodiments, the fiber comprises a sizing composition applied to the surface of the fiber; the sizing composition is essentially an aqueous composition consisting of water, a silane coupling agent, at least one organic acid, and a cationic surfactant, or a composition consisting thereof.

[0072] In some exemplary embodiments, the sizing composition does not have a film-forming agent.

[0073] In some exemplary embodiments, the sizing composition has an active solid content of less than 5%.

[0074] In some exemplary embodiments, the sizing composition (applied to mineral fibers) is substantially colorless and has a ΔL* value of -5 to +5.

[0075] In some exemplary embodiments, at least one organic acid is selected from the group consisting of acetic acid, succinic acid, citric acid, and combinations thereof.

[0076] In some exemplary embodiments, the amount of the sizing composition applied to the fiber is about 0.05 weight% to about 2 weight% based on the total weight of the sized fiber.

[0077] In some exemplary embodiments, the amount of sizing composition applied to the fiber is 4 mg / cm² 2 It is less than.

[0078] In an exemplary embodiment, a package of spin-forming fibers is disclosed. The package comprises at least 10,000 distinct fibers, the fibers have an average fiber diameter x; the fiber diameter distribution of the fibers has a standard deviation from x of less than 3.5 μm; the mineral fibers have a fiber diameter distribution having a first Gaussian peak and a second Gaussian peak; the first Gaussian peak and the second Gaussian peak represent ≥ 85% of the volume of the mineral fibers.

[0079] In an exemplary embodiment, a package of spin-forming fibers is disclosed. The package comprises at least 10,000 distinct fibers, the fibers have an average fiber diameter x; the fiber diameter distribution of the fibers has a standard deviation from x of less than 3.5 μm; the mineral fibers have a fiber diameter distribution having a first Gaussian peak and a second Gaussian peak; the first Gaussian peak and the second Gaussian peak represent ≥ 85% of the volume of the mineral fibers; and ≥ 40% of the volume of the mineral fibers is represented by the first Gaussian peak corresponding to the minimum diameter of the mineral fibers.

[0080] In an exemplary embodiment, a sizing composition for application to a spin-formed glass fiber is disclosed. The sizing composition comprises water, a silane coupling agent, at least one organic acid, and a cationic surfactant, or is essentially composed of or is composed of water, a silane coupling agent, at least one organic acid, and a cationic surfactant.

[0081] In some exemplary embodiments, at least one organic acid is selected from the group consisting of acetic acid, succinic acid, citric acid, and combinations thereof.

[0082] In some exemplary embodiments, the sizing composition has a pH in the range of about 3.0 to about 7.5. In some exemplary embodiments, the sizing composition has a pH in the range of about 4.5 to about 5.5.

[0083] In some exemplary embodiments, the sizing composition has an active solid content of less than 5%.

[0084] In some exemplary embodiments, the cationic surfactant constitutes about 25% by weight to about 90% by weight of the dry solid of the sizing composition.

[0085] In some exemplary embodiments, the silane coupling agent constitutes about 15% to about 45% by weight of the solids of the sizing composition; the organic acid constitutes about 1% to about 20% by weight of the solids of the sizing composition; and the cationic surfactant constitutes about 35% to about 75% by weight of the solids of the sizing composition.

[0086] In some exemplary embodiments, water constitutes about 80% by weight to about 99.9% by weight of the sizing composition.

[0087] In an exemplary embodiment, a nonwoven mat is disclosed. The nonwoven mat comprises a plurality of first fibers; a plurality of second fibers; and a binder that holds the first fibers and the second fibers together in an interleaved arrangement; the first fibers have an average fiber diameter greater than about 7 μm; the second fibers have an average fiber diameter x less than about 6 μm; and the fiber diameter distribution of the second fibers has a standard deviation from x less than 3.5 μm.

[0088] In some exemplary embodiments, the standard deviation from x is less than 3.0 μm. In some exemplary embodiments, the standard deviation from x is less than 2.5 μm.

[0089] In some exemplary embodiments, the second fiber has an average diameter of less than 5 μm. In some exemplary embodiments, the second fiber has an average diameter of less than 4 μm. In some exemplary embodiments, the second fiber has an average diameter of less than 3 μm.

[0090] In some exemplary embodiments, the second fiber has an average formed length of more than 50.8 mm (2 inches).

[0091] In some exemplary embodiments, the second fiber has an average formed length ranging from about 76.2 mm (3 inches) to about 304.8 mm (12 inches).

[0092] In some exemplary embodiments, the second fiber has an average formed length in the range of 50.8 mm (2 inches) to 152.4 mm (6 inches).

[0093] In some exemplary embodiments, x is less than the median fiber diameter of the second fiber.

[0094] In some exemplary embodiments, 90% of the second fibers have a diameter ≤ 1.525x.

[0095] In some exemplary embodiments, the second fiber has a curvature greater than 0.043.

[0096] In some exemplary embodiments, the second fiber has a curvature of at least 0.055.

[0097] In some exemplary embodiments, the second fiber has a curvature in the range of 0.050 to 0.060.

[0098] In some exemplary embodiments, the first fiber is a glass fiber.

[0099] In some exemplary embodiments, the second fiber is a glass fiber.

[0100] In some exemplary embodiments, the second fiber is a spin-forming fiber.

[0101] In some exemplary embodiments, the nonwoven mat comprises at least 1 weight percent of a second fiber based on the weight of the nonwoven mat. In some exemplary embodiments, the nonwoven mat comprises at least 10 weight percent of a second fiber based on the weight of the nonwoven mat. In some exemplary embodiments, the nonwoven mat comprises at least 20 weight percent of a second fiber based on the weight of the nonwoven mat.

[0102] In some exemplary embodiments, the second fiber comprises a sizing composition applied to the surface of the second fiber; the sizing composition is an aqueous composition comprising, essentially consisting of, water, a silane coupling agent, at least one organic acid, and a cationic surfactant.

[0103] In some exemplary embodiments, the amount of the sizing composition applied to the second fiber is about 0.05 weight% to about 2 weight% based on the total weight of the sized second fiber.

[0104] In some exemplary embodiments, the amount of sizing composition applied to the second fiber is 4 mg / cm² 2 It is less than.

[0105] In some exemplary embodiments, the binder comprises polyvinyl alcohol.

[0106] In some exemplary embodiments, the nonwoven mat further comprises an inorganic filler.

[0107] In some exemplary embodiments, the average fiber diameter of the first fiber is in the range of about 10 μm to about 11 μm; and the average fiber diameter of the second fiber is in the range of about 3 μm to about 4 μm.

[0108] In some exemplary embodiments, the second fiber does not contain any fibers with a diameter greater than 22 μm. In some exemplary embodiments, the second fiber does not contain any fibers with a diameter greater than 20 μm. In some exemplary embodiments, the second fiber does not contain any fibers with a diameter greater than 16 μm. In some exemplary embodiments, the second fiber does not contain any fibers with a diameter greater than 15 μm. In some exemplary embodiments, the second fiber does not contain any fibers with a diameter greater than 14 μm.

[0109] In some exemplary embodiments, the nonwoven mat has a first surface and a second surface opposite to the first surface, and each surface is a nonwoven mat 1,000 m2 It contains fewer than about 100 flocs per unit. In some exemplary embodiments, each surface of the nonwoven mat is a nonwoven mat 1,000 m 2 It has fewer than about 50 flocks per unit. In some exemplary embodiments, each surface of the nonwoven mat is a nonwoven mat 1,000 m 2 It has fewer than about 25 flocks per layer. In some exemplary embodiments, each surface of the nonwoven mat is a nonwoven mat 1,000 m 2 Each has approximately 15 or fewer flocs.

[0110] In some exemplary embodiments, the average fiber diameter of the first fiber is in the range of about 8 μm to about 13 μm.

[0111] In some exemplary embodiments, the average fiber diameter of the second fiber is in the range of about 3 μm to about 3.5 μm.

[0112] In some exemplary embodiments, the first fiber comprises about 10% w / w to about 50% w / w of the total weight of the first fiber and the second fiber; and the second fiber comprises about 50% w / w to about 90% w / w of the total weight of the first fiber and the second fiber.

[0113] In some exemplary embodiments, the nonwoven mat comprises more first fibers than second fibers in weight percent based on the total weight of the first fibers and second fibers.

[0114] In an exemplary embodiment, the ceiling tile comprises a surface material on at least one main surface thereof, the surface material comprises a nonwoven mat, the nonwoven mat comprises a plurality of first fibers; a plurality of second fibers; and a binder that holds the first fibers and the second fibers together in an interleaved arrangement; the first fibers have an average fiber diameter greater than about 7 μm; the second fibers have an average fiber diameter x less than about 6 μm; and the fiber diameter distribution of the second fibers has a standard deviation from x less than 3.5 μm.

[0115] In an exemplary embodiment, a method for manufacturing a nonwoven fibrous mat is disclosed. The method comprises: (i) dispersing a plurality of first fibers in a first aqueous solution to form a first slurry; (ii) dispersing a plurality of second fibers in a second aqueous solution to form a second slurry; (iii) mixing the first slurry, the second slurry, and a water-soluble or water-dispersible binder to form a third slurry; (iv) depositing the third slurry to form a wet-laid web composed of the first fibers, the second fibers, and the binder; and (v) drying the wet-laid web to form a nonwoven fibrous mat, wherein the first fibers have an average fiber diameter in the range of about 6.5 μm to about 15 μm; the second fibers have an average fiber diameter x of less than 6.0 μm; and the fiber diameter distribution of the second fibers has a standard deviation from x of less than 3.5 μm; The nonwoven mat has a first surface and a second surface opposite to the first surface, wherein each surface is a nonwoven mat 1,000 m 2 Each has fewer than 100 flocs.

[0116] In some exemplary embodiments, a binder is added to the first slurry.

[0117] In some exemplary embodiments, a binder is added to the second slurry.

[0118] In an exemplary embodiment, a nonwoven mat for use as a surface material for ceiling tiles is disclosed. The nonwoven mat comprises a plurality of first fibers; a plurality of second fibers; and a binder that holds the first fibers and the second fibers together in an interleaved arrangement; the first fibers have an average fiber diameter greater than about 6 μm; the second fibers have an average fiber diameter x μm less than about 4 μm; the second fibers constitute y weight% of the mat; y / x < 10; and the mat has a cloudiness rating of 15 or less in the range of 19 mm to 42 mm when measured with a cloud runner device.

[0119] In an exemplary embodiment, the ceiling tile comprises a surface material on at least one main surface thereof, the surface material comprises a nonwoven mat, the nonwoven mat comprises a plurality of first fibers; a plurality of second fibers; and a binder that holds the first fibers and the second fibers together in an intermittent arrangement; the first fibers have an average fiber diameter greater than about 6 μm; the second fibers have an average fiber diameter x μm less than about 4 μm; the second fibers constitute y weight% of the mat; y / x < 10; and the mat has a turbidity grade of 15 or less in the range of 19 mm to 42 mm when measured with a cloud runner device.

[0120] In an exemplary embodiment (i.e., embodiment A), a package of rotationally formed mineral fibers comprises at least 10,000 distinct mineral fibers, wherein the mineral fibers have an average fiber diameter x; and the fiber diameter distribution of the fibers has a standard deviation from x of less than 3.5 μm.

[0121] In some embodiments of embodiment A, the standard deviation from x is less than 3.0 μm, and preferably less than 2.5 μm.

[0122] In some embodiments of embodiment A, the mineral fibers have an average diameter of less than 6 μm, preferably less than 5 μm, more preferably less than 4 μm, and even more preferably less than 3 μm.

[0123] In some embodiments of embodiment A, the mineral fibers have an average formed length of more than 50.8 mm, preferably in the range of about 76.2 mm to about 304.8 mm.

[0124] In some embodiments of embodiment A, x is less than the median fiber diameter of the mineral fiber.

[0125] In some embodiments of embodiment A, 90% of the mineral fibers have a fiber diameter ≤ 1.525x.

[0126] In some embodiments of embodiment A, the mineral fiber is a glass fiber.

[0127] In some embodiments of embodiment A, the mineral fiber has a fiber diameter distribution having a first Gaussian peak and a second Gaussian peak; the first Gaussian peak and the second Gaussian peak represent ≥ 85% of the volume of the mineral fiber. In some embodiments of embodiment A, ≥ 40% of the volume of the mineral fiber is represented by a first Gaussian peak corresponding to the minimum diameter of the mineral fiber.

[0128] In an exemplary embodiment (i.e., embodiment B), a method for manufacturing a package of mineral fibers (i.e., according to any aspect of embodiment A) comprises the steps of: rotating a spinner having a peripheral wall comprising a plurality of orifices; feeding molten mineral material to the rotating spinner to centrifuge a stream of molten mineral material through the orifices; mixing combustion air and combustion gas and feeding the mixture to an annular burner located around the spinner; generating an annular flow of air induced within a passage located between the annular burner and an annular blower; directing the hot gas from the annular burner and the annular flow of air induced toward the spinner and the stream of molten mineral material to heat the spinner and elongate the stream of molten mineral material into a package of mineral fibers; and directing a source of cooling air to a quill fan located below the spinner through a hollow quill extending through the spinner, wherein the cooling air is approximately 51 m 3 / h to about 102 m 3 It is delivered to the quill fan at a flow rate of / h.

[0129] In some embodiments of Embodiment B, the quill fan is cooled to a temperature of less than about 399°C.

[0130] In some embodiments of embodiment B, the method further includes the step of controlling the spinner to rotate at a speed of about 900 rpm to about 2,400 rpm.

[0131] In a partial embodiment of Embodiment B, the high-temperature gas from the annular burner is approximately 408 m 3 / h to about 510 m 3 It is directed toward the spinner and the stream of molten mineral material at a flow rate of / h.

[0132] In some embodiments of Embodiment B, the annular blower is approximately 697 m 3 It generates an induced annular flow of air by outputting air at / h.

[0133] In an exemplary embodiment (i.e., embodiment C), the nonwoven mat comprises a plurality of first fibers; a plurality of second fibers; and a binder that holds the first fibers and the second fibers together in an intermittent arrangement; the first fibers have an average fiber diameter greater than about 7 μm; and the plurality of second fibers are packages of mineral fibers according to any aspect of embodiment A.

[0134] In some embodiments of embodiment C, the first fiber is a mineral fiber, preferably a glass fiber.

[0135] In some embodiments of embodiment C, the nonwoven mat comprises at least 1 weight%, preferably at least 10 weight%, and more preferably at least 20 weight% of second fibers based on the weight of the nonwoven mat.

[0136] In some embodiments of Embodiment C, the binder comprises polyvinyl alcohol.

[0137] In some embodiments of Embodiment C, the nonwoven mat further comprises an inorganic filler.

[0138] In some embodiments of embodiment C, the average fiber diameter of the first fiber is in the range of about 8 μm to about 13 μm, and preferably about 10 μm to about 11 μm; and the average fiber diameter of the second fiber is in the range of about 3 μm to about 4 μm, and preferably about 3 μm to about 3.5 μm.

[0139] In some embodiments of embodiment C, the nonwoven mat has a first surface and a second surface opposite to the first surface, and each surface is a nonwoven mat 1,000 m 2 It contains about 100 or fewer flocs per day, preferably about 50 or fewer, more preferably about 25 or fewer, and most preferably about 15 or fewer.

[0140] In some embodiments of embodiment C, the first fiber corresponds to about 10% w / w to about 50% w / w of the total weight of the first fiber and the second fiber; and the second fiber corresponds to about 50% w / w to about 90% w / w of the total weight of the first fiber and the second fiber.

[0141] In an exemplary embodiment (i.e., embodiment D), the use of a nonwoven mat (i.e., according to any aspect of embodiment C) is considered in a roof component (e.g., roofing board), in a ceiling tile, in a surface finishing bale for a composite application, in a building board, in a filtration medium, in a flooring application, in a wallpaper application, or in a battery separator application.

[0142] In an exemplary embodiment (i.e., embodiment E), a method for manufacturing a nonwoven fibrous mat (i.e., according to any aspect of embodiment C) comprises: (i) dispersing a plurality of first fibers in a first aqueous solution to form a first slurry; (ii) dispersing a plurality of second fibers in a second aqueous solution to form a second slurry; (iii) mixing the first slurry, the second slurry, and a water-soluble or water-dispersible binder to form a third slurry; (iv) depositing the third slurry to form a wet-laid web composed of the first fibers, the second fibers, and the binder; and (v) drying the wet-laid web to form a nonwoven fibrous mat, wherein the first fibers have an average fiber diameter in the range of about 6.5 μm to about 15 μm; and the plurality of second fibers are packages of mineral fibers according to any aspect of embodiment A.

[0143] In some embodiments of embodiment E, a binder is added to the first slurry.

[0144] In some embodiments of embodiment E, a binder is added to the second slurry.

[0145] Other aspects and features of the concept of the present invention will become more readily apparent to those skilled in the art when reviewing the following description of various exemplary embodiments together with the accompanying drawings. Brief explanation of the drawing

[0146] The alternative concept of the present invention, as well as embodiments and advantages thereof, are described in more detail below by way of example with reference to the drawings. FIG. 1 is a partial cross-sectional view of a rotating fiber forming device to illustrate various aspects of a conventional rotating fiber generating method. Figure 2a is a graph illustrating the fiber diameter distribution relative to the volume of glass fibers produced by one conventional spinning fiber production method. FIG. 2b is a graph illustrating the fiber diameter distribution relative to the volume of glass fibers produced by another conventional spinning fiber generation method. FIG. 2c is a graph illustrating the fiber diameter distribution relative to the volume of glass fibers produced by another conventional spinning fiber generation method. Figure 2d is a graph illustrating the fiber diameter distribution relative to the volume of glass fibers produced by other conventional spinning fiber generation methods. FIG. 3 is a partial cross-sectional view of a rotating fiber forming apparatus to illustrate various aspects of a rotating fiber generating method according to an exemplary embodiment. Figure 4 is a graph illustrating the fiber diameter distribution with respect to the volume of glass fibers produced by the rotating fiber generation method of Figure 3. Figure 5 is a graph illustrating the zeta potential (with respect to pH) of several glass-sizing formulations. Figure 6 is a diagram illustrating three different simulated viewing angles by a cloud runner device. Figure 7 is a graph illustrating cloud size measurements for ceiling tile surface materials containing different types and percentages of microfibers. Figure 8 is a graph illustrating cloud size measurements for ceiling tile surface materials containing micro-rotating fibers of different percentages and diameters. FIG. 9a is a graph illustrating cloud size measurements for ceiling tile surface materials comprising different 6.5 μm WUCS glass fibers and 3.5 μm spin glass fibers of the present invention. FIG. 9b is a graph illustrating cloud size measurements for ceiling tile surface materials including different 6.5 μm WUCS glass fibers and 6.5 μm spin glass fibers of the present invention. FIG. 10 is a drawing illustrating exemplary nonwoven mat sections with and without flocks. FIG. 11 is a graph showing the “transition value” between fiber diameter measurements of various WUCS fibers with different fiber diameters using an SEM microscope-based approach and an ISO 13322-2 compliant approach described herein. FIG. 12 is a drawing illustrating an exemplary processing of the spin fiber of the present invention before being mixed with other fibers in a wet-laid process. FIGS. 13a to 13c are scanning electron microscope (SEM) images of exemplary nonwoven mats made from fiber blends with measured fiber curvature. Specific details for implementing the invention

[0147] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention pertains. The term "approximately" used herein to modify any numerical value encompasses not only the specific numerical value without any modification, but also reasonable deviations such as those attributable to measurement methods or limits.

[0148] With the understanding that the present disclosure merely illustrates the general concept of the invention, some exemplary embodiments will be described in detail. Embodiments encompassing the general concept of the invention may take various forms, and the general concept of the invention is not intended to be limited to the specific embodiments described herein.

[0149] In the above regard, modifications to the spin fiber forming process enable the production of fibers having a more uniform fiber diameter and / or length distribution. An alternative concept of the present invention includes this new method for producing spin fibers, the new spin fibers themselves, a sizing formulation suitable for use with the new spin fibers, a package of spin fibers (e.g., having an improved fiber distribution), a nonwoven mat made of the new spin fibers, and downstream applications for the mats (e.g., a surface material for ceiling tiles).

[0150] Rotational forming process / system

[0151] It is known that nonwoven materials can be formed using glass fibers. For example, composite materials constituting reinforced glass fiber mats (known, e.g., veils, webs, and surface materials) are utilized in various applications.

[0152] One approach to forming glass fibers involves passing molten glass through an orifice at the bottom of a fixed bushing, where the stream of molten glass is elongated into fibers as it cools. See, for example, US 3,653,860; US 3,972,702; and US 4,207,086. Another approach to forming glass fibers involves passing molten glass through an orifice within the outer wall of a spinner (via centrifugal force), where the stream of molten glass is elongated into fibers as it cools. See, for example, US 5,582,841. In the case of spin-formed fibers, heated air may be used to draw the fibers downward, which aids in the elongation and collection of the fibers.

[0153] Bushing-forming glass fibers can be subsequently chopped to form wet-process chopped strand (WUCS) fibers having a relatively constant average fiber diameter and average fiber length. However, bushing-forming glass fibers are typically limited to a fiber diameter of 6.5 μm or greater due to health concerns regarding their non-biosoluble nature. Additionally, due to factors such as raw material costs and production (melting) costs, bushing-forming glass fibers can be relatively more expensive to produce compared to spin-forming glass fibers.

[0154] Consequently, for many applications, spin-formed glass fibers are used in place of or in addition to bushing-formed glass fibers. Spin-formed glass fibers can have fiber diameters much lower than 6.5 μm due to their biosoluble formulations. These so-called "microfibers" can provide improved properties at lower added weights compared to WUCS fibers. However, producing spin-formed glass fibers with a consistent average fiber diameter and / or average fiber length has proven difficult.

[0155] One approach for measuring the average fiber diameter, such as the average fiber diameter described herein, involves (1) applying heat to a sample sufficient to burn off any surface chemicals without affecting the underlying fiber shape; and (2) determining the average fiber diameter for a given quantity of fibers by measuring the airflow / pressure drop over the quantity of fibers, as is typically done in the insulation and fiber industries (e.g., micronaire). The instrument used to measure fiber diameter through airflow resistance is based on theories, in particular, from the literature [Darcy, Les Fontaines Publiques de la Ville de Dijon (1856)]; the literature [Kozeny, Über Kapillare Leitung des Wassers im Boden (1927)]; and the literature [Carman, Flow of Gases Through Porous Media (1956)]. The instrument operates by measuring the airflow resistance passing through a material of known mass; as the fiber diameter decreases, the specific surface area increases, which increases the resistance to the airflow. As airflow resistance increases, the effective fiber diameter corresponding to the fiber diameter expected to produce the same resistance when all fibers have the same diameter becomes smaller. This is the primary technique (referred to as the airflow resistance approach) for obtaining the effective fiber diameter values ​​presented herein (as estimates of the average fiber diameter), including the claims, unless otherwise noted.

[0156] However, the aforementioned airflow resistance approach is not suitable for determining the distribution of individual fibers (e.g., fibers with different diameters) from a large volume of fibers, or for determining values ​​calculated from the distribution (e.g., mean, median, standard deviation). Therefore, other approaches for measuring fiber diameter in the context of an overall fiber distribution, such as the fiber diameter distribution described herein, involve (1) applying heat to a sample sufficient to burn off any surface chemicals without affecting the underlying fiber shape; (2) dispersing plain fibers in water using a high-speed blender; (3) diluting the fibers dispersed in water to an acceptable concentration suitable for image analysis; and (4) measuring the fiber diameter distribution using image analysis (e.g., according to ISO 13322-2). Image analysis may be performed by a device in which particles (i.e., dispersed fibers) pass through the focal planes of two cameras, and the device has an image rate of 300 images per second and a resolution of 0.8 μm per pixel. The device used to obtain the data described herein is a Camsizer X2 with an X-Flow module, manufactured by Microtrac MRB in Osaka, Japan. The measured data can be filtered to remove non-fibrous particles (e.g., particles with an aspect ratio (L / D) of less than 5). Generally, at least 10,000 fibers are measured to ensure a suitable distribution assessment. The reported results are bucketed Martin minimum diameters for every 0.1 micrometer and are plotted based on volume (rather than count), where volume requires that both the average diameter and average length of each fiber be measured. This image processing-based approach, generally referred to herein as the ISO 13322-2 compliant approach, is the primary technique for obtaining the average fiber diameter values ​​presented herein, including the claims, unless otherwise noted.

[0157] As generally used herein, including in the claims, the term "average fiber diameter" includes both the effective fiber diameter and the average fiber diameter for a sample, unless the context otherwise indicates.

[0158] It should be noted that there are other approaches for identifying not only the average fiber diameter but also other distribution-related characteristics of a fiber collection, such as a count-based approach that examines individual fibers identified using a scanning electron microscope (SEM). Although these other approaches are not directly related to the values ​​presented herein, it was determined that measurements taken by one approach can be easily converted to the approach disclosed herein by multiplying such values ​​by a constant conversion value. For example, as shown in graph (1100) of FIG. 11, various samples consisting of non-rotating WUCS fibers with different fiber diameters were measured using both the SEM microscope-based approach and the ISO 13322-2 compliant approach described herein (referred to as Camsizer in graph (1100)). By calculating the "fitted line" between the various measurements, it was determined that the conversion between the value (α) by the SEM microscope-based approach and the value (β) by the ISO 13322-2 compliant approach can be calculated as α = 0.76 × β.

[0159] From the above perspective, modifications to the spin fiber forming process enable the production of fibers with a more uniform fiber diameter and / or length distribution. Consequently, the major disadvantages of spin-formed fibers are mitigated, and downstream processing of spin-formed fibers is improved.

[0160] A modified spin fiber forming process (300) will be described with reference to a conventional fiber manufacturing apparatus or fiberizer, such as the fiberizer (10) of FIG. 1 (although the disclosed radiation shield (52) is an optional component). As illustrated in FIG. 3, the spin fiber forming process (300) comprises a number of embodiments A through E that can be modified to produce fibers having a more uniform fiber diameter and / or length distribution. An alternative concept of the invention comprises a modified spin fiber forming process (300) using one or more of these embodiments A through E to obtain a large quantity of fibers (produced together) having a more uniform fiber diameter and / or length distribution. An alternative concept of the invention comprises any combination of these embodiments (e.g., A, A+B, A+C, A+B+C, A+D, A+B+D, A+B+C+D, A+E, etc.). Furthermore, the alternative concept of the present invention is not necessarily limited to these embodiments, and other features of the present invention, such as the sizing formulation(s) described herein, may also contribute to an improved fiber diameter and / or length distribution in some exemplary embodiments.

[0161] During conventional processing, the surface of the quill pan (67) of the fiberizer (10) can become hot enough to melt the fibers in contact with the quill pan (67). In one embodiment A of the modified rotary fiber forming process (300), the amount of cooling air introduced through the hollow quill (64) is increased, which reduces the temperature of the quill pan (67). For example, the conventional rotary fiber forming process lowers the temperature of the quill pan (67) to a temperature temp conv To cool to, an air flow rate of approximately 5 to 15 cubic feet / min (CFM) will be used. The rotary fiber forming process of the present invention (e.g., process (300)) cools the quill fan (67) to a temperature temp inv To cool, an air flow rate of approximately 30 to 60 CFM is used. Consequently, the temperature convAlthough it is typically much higher than 1,100℉ (e.g., ≥ 1,200℉), temp inv The temperature is kept below 1,100℉. As a result, the fibers formed that come into contact with the quill fan (67) are less likely to be fused with it (or with other fibers fused with it) in a way that could damage the fibers or lead to fiber aggregation (e.g., flocking) — both of which could distort the intended fiber diameter and / or length distribution.

[0162] In another embodiment B of the modified rotary fiber forming process (300), the rotational speed of the spinner (12) (via the rotary spindle (14)) is reduced, which reduces the likelihood of the fiber coming into contact with the surface of the blower (28). For example, a conventional rotary fiber forming process would cause the spinner (12) to operate at 2,500 rpm to 3,000 rpm, whereas the rotary fiber forming process of the present invention (e.g., process (300)) would cause the same spinner (12) to operate at 1,800 rpm to 2,400 rpm. For spinners having different sizes / geometric shapes, these ranges may be shifted, but the reduction in rotational speed in the modified rotary fiber forming process compared to the conventional rotary fiber forming process will be maintained. As a result, the fibers formed are less likely to be fused with them (or with other fibers fused with them) in a manner that could lead to damage to the fibers or fiber aggregation (e.g., flocs)—both of which can distort the intended fiber diameter and / or length distribution.

[0163] In another embodiment C of the modified rotary fiber forming process (300), the amount of heated air generated by the burner (24) is reduced. For example, a conventional rotary fiber forming process would use a mixed gas flow rate of approximately 360 cubic feet / min (CFM), while the rotary fiber forming process of the present invention (e.g., process (300)) would use a mixed gas flow rate of approximately 240 to 300 CFM. Reducing the air flow in C helps to lower the temperature in process (300), but this must be balanced by the tendency for the fiber diameter to become larger as the temperature is lowered and the elongation is reduced. Consequently, in some exemplary embodiments, the modified rotary fiber forming process (300) may have a lower limit on its ability to produce fibers of smaller diameter and / or length. For example, the lower limit of the effective fiber diameter (using the air flow method) will be in the range of 2.5 μm to 3.0 μm, where this lower limit is limited by the ability to maintain a temperature sufficient to slender the molten glass into fibers.

[0164] In another embodiment D of the modified rotary fiber forming process (300), the amount of air induced through the passage (30) by the blower (28) is controlled to promote improved slendering of the primary fiber (22) into the secondary fiber (32). In some exemplary embodiments of the rotary fiber forming process of the present invention (e.g., process (300)), the blower (28) outputs approximately 410 cubic feet / min (CFM) of air, which subsequently leads to the “induced air” flowing through the passage (30). Here, “improved slendering” may be considered to achieve a reduction in the occurrence of fused fibers and other defects (e.g., shots, flocks), as described herein. Likewise, such improved slendering (and the resulting reduction of fused fibers) is demonstrated by an improved fiber diameter and / or length distribution, as illustrated in the graph (400) of FIG. 4.

[0165] The above embodiments A through D are particularly important in relation to embodiment E of the modified spin fiber forming process (300), which represents a "slendering zone" for the secondary fiber (32). The slendering zone (E) is an area around the fiberizer (10) where the temperature is high enough to fuse the fiber (32). The modified spin fiber forming process (300) is such that the fiber (32) reaches its glass transition temperature T g Attempts are made to minimize collisions between two separate fibers (32) and / or between a fiber (32) and a fiber forming device until they are cooled to a temperature below which there is less chance of them fusing accordingly. For example, in the case of glass fibers with a Tg in the range of 1,000°F to 1,250°F, the modified rotary fiber forming process (300) will attempt to minimize fiber collisions until the fibers are cooled to a temperature below 1,100°F.

[0166] In addition to producing a large quantity of fibers having a fiber diameter and / or length distribution closer to the target fiber diameter and / or length, by reducing the number of fibers that are fused or / or damaged during the production process, the modified spin fiber forming process (300) can produce a large quantity of fibers having improved overall quality (e.g., longer length) compared to conventional spin fibers.

[0167] Furthermore, fibers produced by the modified spin fiber forming process (300) may be further processed downstream of the process (300), for example, by milling / cutting / chopping the fibers to a length that is easier to process. For example, the fibers may be milled to have a reduced length ranging from 1 / 8 inch (3.25 mm) to 1 inch (25.4 mm), which facilitates the use of the fibers in a wet-laid process. Likewise, other applications / processes may benefit from fibers having longer lengths. Thus, because the fibers produced by the modified spin fiber forming process (300) have a longer initial (formed) length than conventional spin-formed fibers, the fibers are more likely to start at a length longer than the target length, which subsequently provides more flexibility in reducing the fibers to the target (processed) length and provides greater uniformity in products manufactured from such fibers.

[0168] In this way, a wider range of aspect ratios can be obtained from the processed fibers, wherein the processed fibers have a more uniform distribution with respect to the target aspect ratio. For example, the spun fibers of the present invention may be processed to have an average aspect ratio in the range of 850 to 5,000 or in the range of 850 to 2,000. When blended with non-spun fibers (e.g., WUCS fibers) having an aspect ratio of less than 2,000, the combined average aspect ratio of the fiber blend is about 1,000 or less. The combined average aspect ratio is calculated as Average Aspect Ratio = (Weight % of Fiber 1 * Aspect Ratio of Fiber 1) + (Weight % of Fiber 2 * Aspect Ratio of Fiber 2). Additionally, as described herein, when used to form a nonwoven mat, the average aspect ratio of the fibers will typically be lower (e.g., in the range of 150 to 500) due to breakage during the nonwoven forming process.

[0169] Improved rotational forming fiber

[0170] FIG. 4 illustrates a graph (400) of the fiber diameter distribution for a glass fiber material according to an exemplary embodiment. The glass fiber material comprises spin-forming fibers that are not held together by a binder. The glass fiber material is formed by a modified spin-forming fiber process (e.g., process (300)).

[0171] Referring to the graph (400), various characteristics of the glass fiber material of the present invention are shown in Table 5.

[0172] [Table 5]

[0173]

[0174] In Table 5, "Peak Index" refers to the peak identifier from left to right—where the peak is shown as a dashed line—; "Peak Type" refers to the type of model used to fit the data; "Area Intg" refers to the integrated area of ​​the fitted peak; "Area IntgP" refers to the percentage of the total integrated area for each fitted peak; "Center Gravity" refers to the center of the fitted peak; "Max Height" refers to the maximum value of the fitted peak; and "FWHM" refers to the width of the peak at half the maximum height of the peak.

[0175] In the graph (400) of Fig. 4, rotary fibers were generated with a target diameter of approximately 3.5 μm when measured using a known air flow method. The graph (400) shows the fiber diameter distribution when measured using an ISO 13322-2 compliant method and plotted as fiber volume %. Data measured according to the ISO 13322-2 compliant approach (Camsizer) were analyzed using the Peak Deconvolution App (v2.00) of OriginPro 2023, data analysis software sold by OriginLab Corp., Northampton, Massachusetts, USA (constant baseline; fitting until converged to obtain the displayed results).

[0176] Ideally, 100% of the generated fibers would have a fiber diameter of about 3.5 μm. However, spin fiber generation is a complex process involving many variables, some of which can be controlled. As described herein, a modified spin fiber forming process (e.g., process (300)) recognizes and controls one or more generation variables to achieve fibers having improved characteristics compared to conventional spin fibers.

[0177] The spin fibers shown in graph (400) have a more distinct bimodal distribution compared to the conventional spin fibers shown in the graphs of FIGS. 2a through 2d. In particular, graph (400) shows two distinct peaks, each having a peak higher than 15% / μm within the distribution. Additionally, the fiber diameter distribution (i.e., the area under the graph) shows that a larger amount of fibers are closer to the target fiber diameter (i.e., 3.5 μm), and fibers with a diameter greater than 14 μm are rarely measured. For a target fiber diameter of 3.5 μm, this narrower dispersion of fiber diameters (e.g., from about 1.5 μm to about 13.5 μm) is closer to the ideal than achieved by conventional spin fibers, with most fibers having a fiber diameter of less than 6 μm. In other words, because the dispersion of fiber diameters relative to the target fiber diameter is reduced and / or the volume of fibers closer to the target fiber diameter is increased, the spin fiber of the present invention can yield an improved product / application.

[0178] In Table 6, additional characteristics of the glass fiber material of the present invention (shown in graph (400)) are compared with various conventional fibrous materials (shown in graphs (210, 220, 230, 240)).

[0179] [Table 6]

[0180]

[0181] Here, d10 means that 10% of all particles in the sample are less than or equal to the d10 value; d50 means that 50% of all particles in the sample are less than or equal to the d50 value (also known as the median particle size); and d90 means that 90% of all particles in the sample are less than or equal to the d90 value. The sample mean refers to the average particle size for the sample; and the standard deviation refers to the standard deviation from the mean.

[0182] With respect to the values ​​shown in Table 6, although the spin-formed glass fiber of the present invention does not have a lower median fiber diameter (d50) than all sampled conventional spin-formed glass fibers, the spin-formed glass fiber of the present invention has a lower average value than all sampled conventional spin-formed glass fibers. This indicates that the amount of material with a larger diameter (i.e., a diameter larger than the target fiber diameter) is smaller for the spin-formed glass fiber of the present invention, which can be seen from the graphs in FIGS. 2a, 2b, 2c, 2d, and FIG. 4. The smaller standard deviation value also indicates that the spin-formed glass fiber of the present invention has a more uniform fiber diameter distribution, as described herein.

[0183] Additionally, the spin fiber of the present invention is produced with an increased fiber length compared to conventional spin fibers.

[0184] For example, while a conventional spin fiber forming process will produce spin fibers (from the fiberizer (10)) having a length of approximately 12.7 mm (0.5 inches) to 50.8 mm (2 inches), the spin fiber forming process of the present invention (e.g., process (300)) will produce spin fibers (from the fiberizer (10)) having a length of approximately 76.2 mm (3 inches) to 304.8 mm (12 inches). In some exemplary embodiments, the spin fiber forming process of the present invention will produce spin fibers with an average formed length in the range of greater than 50.8 mm (2 inches) and less than or equal to 152.4 mm (6 inches). The ability to produce longer fibers provides increased flexibility in downstream processing of the fibers as well as greater control over the characteristics of the final product.

[0185] Additionally, the spin fibers of the present invention contain fewer fused fibers, clumps (e.g., flocks), or strings, and accordingly, enable a more uniform dispersion of fibers when manufacturing nonwoven products as described herein. As used herein, the term “flock” refers to a loosely clumped mass of fibers visible to the naked eye. As illustrated in Figure 10 (1000), a sample portion (1010) of a nonwoven mat has substantially no flocks (1002) on one side (1012) and / or on the side opposite (1012) (not shown), whereas another sample portion (1020) of a nonwoven mat contains some flocks (1002) on one side (1022) and / or on the side opposite (1022) (not shown).

[0186] In some exemplary embodiments, the spin fiber has an average fiber diameter of less than 6.5 μm. In some exemplary embodiments, the spin fiber has an average fiber diameter of less than 5.5 μm. In some exemplary embodiments, the spin fiber has an average fiber diameter of less than 4.5 μm.

[0187] In some exemplary embodiments, the spin fiber has a fiber diameter distribution having one or two Gaussian peaks representing ≥ 85% of the fiber volume / mass, where ≥ 40% of the volume / mass is at the peak representing the minimum diameter fiber.

[0188] In some exemplary embodiments, the spinning fiber substantially does not contain any fibers with a diameter greater than 15 μm.

[0189] In some exemplary embodiments, at the time of its formation (e.g., when exiting the fiberizer (10)), the spinning fiber has substantially no or substantially reduced unfiberized or poorly fiberized material (generally referred to as “shot”), fused fibers, aggregated fibers (e.g., flock), and / or other types of defective fibers, which may contribute to the improved fiber diameter distribution described herein.

[0190] In some exemplary embodiments, the spinning fiber is made of a biosoluble composition.

[0191] Non-rotating fibers (e.g., WUCS fibers) are essentially straight when formed, whereas rotating fibers generally have curvature due to glass fibers cooling in a less controlled environment. This curvature can also provide advantages to products manufactured with the rotating fibers of the present invention, for example, by reducing visual defects in ceiling tiles (e.g., cloud / spot formation; orientation) due to more random light scattering and the inability of the fibers to align with one another.

[0192] As illustrated in FIGS. 13a to 13c, using a wet-laid process, several sample nonwoven mats were manufactured by combining a blend of fibers comprising: (i) a WUCS fiber with a diameter of 11 μm and a length of 6 mm as a first fiber (fiber 1); (ii) a blend of fibers comprising a WUCS fiber with a diameter of 6.5 μm and a length of 6 mm as a second fiber (fiber 2) as of FIG. 13a; (iii) a blend of fibers comprising a conventional ULF fiber illustrated in FIG. 2c as a second fiber (fiber 2) as of FIG. 13b; and (iii) a blend of fibers comprising a spin fiber of the present invention described herein and illustrated in FIG. 4 as a second fiber (fiber 2) as of FIG. 13c.

[0193] FIG. 13a includes an SEM image of a nonwoven mat (1300) manufactured by a wet-laid process using a combination of a first WUCS fiber (fiber 1) having an average fiber diameter of 11 μm at 85% and a processing length of 6 mm at 15% of the weight of the glass fiber, and a second WUCS fiber (fiber 2) having an average fiber diameter of 6.5 μm at 15% and a processing length of 6 mm. FIG. 13b includes an SEM image of a nonwoven mat (1302) manufactured by a wet-laid process using a combination of a first WUCS fiber (fiber 1) having an average fiber diameter of 11 μm at 85% and a processing length of 6 mm at 15% of the weight of the glass fiber, and a second ULF fiber (fiber 2) having an average fiber diameter in the range of 2.8 μm to 3 μm and a processing length in the range of 1 mm to 6 mm at 15% of the weight of the glass fiber. FIG. 13c includes an SEM image of a nonwoven mat (1304) manufactured by a wet-laid process using a combination of a first WUCS fiber (fiber 1) having an average fiber diameter of 11 μm and a processing length of 6 mm at 85% of the weight of the glass fiber, and a second spin fiber of the present invention (fiber 2) having an average fiber diameter of 3.5 μm and a processing length ranging from 1 mm to 6 mm.

[0194] The mats (1300, 1302, 1304) were imaged using a scanning electron microscope to generate the SEM images shown in FIGS. 13a to 13c, respectively. These SEM images were analyzed using ImageJ version 1.54f open-source software, and the curvature of the second fiber (fiber 2) of each mat (1300, 1302, 1304) was approximated using the Kappa curvature analysis plug-in (Gary Brouhard, 2016). The WUCS fiber (fiber 2) in the mat (1300) was found to have a curvature of 0.004. The ULF fiber (fiber 2) in the mat (1302) was found to have a curvature of approximately 0.043. The rotational fiber (fiber 2) of the present invention in the mat (1304) was found to have a curvature of approximately 0.055.

[0195] In some exemplary embodiments, spin fibers produced by one or more fiberizers having essentially the same operating parameters (and, possibly, essentially simultaneously) are packaged together. In some exemplary embodiments, the spin fibers may be processed prior to packaging (e.g., milled to reduce the length (to “processed length”)). The spin fibers within the package may contain a sizing composition applied thereto as described herein. The package of spin fibers will have an improved fiber diameter and / or length distribution as described herein.

[0196] Sizing formulation(s)

[0197] An aqueous sizing composition may be applied to the spinning fiber of the present invention when it is being formed or immediately thereafter. For example, the sizing composition may be sprayed onto the fiber using an annular ring in which a nozzle surrounding a curtain of fibers is directed downward. Surface chemicals imparted to the spinning fiber by the sizing composition may act to protect the fiber and facilitate its downstream processing.

[0198] In an exemplary embodiment, a sizing composition is provided. The sizing composition comprises water, a silane coupling agent, at least one organic acid, and a cationic surfactant, and the sizing composition has an active solid content of less than 5% and is substantially "colorless". Surprisingly, it has been found that the sizing composition, which contains a reduced number of components compared to conventional sizing compositions (e.g., conventional sizing compositions used with WUCS fibers), is particularly useful for the fibers of the present invention. In particular, various exemplary embodiments of the sizing composition disclosed herein are free of film-forming agents. In some embodiments, the reduced number of components produces a sizing composition that is more cationic than the conventional sizing composition, which provides improved dispersion of the sized fibers in a white-water solution during the formation of a mat made of the spin fibers of the present invention.

[0199] An exemplary sizing composition comprises, at least, a silane coupling agent, at least one organic acid, and a cationic surfactant. In any embodiment, the sizing composition may essentially consist of a silane coupling agent, at least one organic acid, and a cationic surfactant, or may consist of these.

[0200] Silane coupling agent

[0201] The silane coupling agent may be in a partially or completely hydrolyzed or unhydrolyzed state. The silane coupling agent may also be in the form of a monomer, oligomer, or polymer before, during, or after its use.

[0202] Suitable silane coupling agents used in the sizing compositions disclosed herein are organosilanes having silanol functional groups that bond well with glass (e.g., after hydrolysis of the alkoxy group). Silane coupling agents also function to aid processability, for example, by reducing the level of fiber filaments broken during subsequent processing.

[0203] Silane coupling agents that can be used in the sizing composition may be characterized by functional groups amino, methacrylate, epoxy, azido, vinyl, methacryloxy, ureido, and isocyanato. Preferably, the organosilane has a functional group connected to a silicon atom through a non-hydrolytic bond.

[0204] The organosilane for use in the sizing composition comprises a monosilane containing the structure Si(OR)3, where R is an organic group such as an alkyl group. Lower alkyl groups such as methyl, ethyl, and isopropyl are preferred. Examples of specific silane coupling agents suitable for use in sizing compositions include gamma-aminopropyltriethoxysilane (A-1100), gamma-ureidopropyltrimethoxysilane (A-1524), 3-aminopropyltriethoxysilane (KBE-903), γ-glycidoxypropyltrimethoxysilane (A-187), γ-methacryloxypropyltrimethoxysilane (A-174), n-β-aminoethyl-γ-aminopropyltrimethoxysilane (A-1120), methyl-trichlorosilane (A-154), methyltrimethoxysilane (A-163), γ-mercaptopropyl-trimethoxy-silane (A-189), γ-chloropropyl-trimethoxy-silane (A-143), vinyl-triethoxy-silane (A-151). Vinyl-tris-(2-methoxyethoxy)silane (A-2171), vinyl-triacetoxysilane (A-188), octyltriethoxysilane (A-137), methyltriethoxysilane (A-162), and methyltrimethoxysilane (A-1630) are included, but not limited thereto. All silane coupling agents listed herein are available for purchase as Silquest™ products from Momentive Performance Materials, Inc. (Waterford, New York, USA). In certain exemplary embodiments, the silane coupling agent is selected from the group consisting of gamma-aminopropyltriethoxysilane, gamma-ureidopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and combinations thereof.

[0205] In one exemplary embodiment, the sizing composition comprises Silquest® Y-9669, available from Momentive, which is N-phenyl-gamma-aminopropyltrimethoxysilane with a solid content of 82%, and Silquest® A-1120, which is N(beta-aminoethyl)gamma-aminopropyltrimethoxysilane with a solid content of 81%. An exemplary methacrylate-functional silane for use in the sizing composition disclosed herein is gamma-methacryloxypropyltrimethoxysilane (A-174), which is available for purchase from Momentive Performance Materials, Inc., Waterford, New York, USA. In another exemplary embodiment, the silane coupling agent component of the sizing composition of the disclosure comprises Silquest® Y-9669 and A-174.

[0206] In a predetermined exemplary embodiment, the sizing composition comprises a silane coupling agent in an amount such that the silane coupling agent constitutes 1% to 60% by weight of the solid content of the sizing composition. In a predetermined exemplary embodiment, the silane coupling agent constitutes 5% to 50% by weight of solids based on the total solid content of the sizing composition, which includes, for example, 15% to 45% by weight and also includes 25% to 35% by weight of solids. In a predetermined exemplary embodiment, the silane coupling agent has an active solid content of 25% to 80%, which includes 40% to 70% and 60% to 65%.

[0207] organic acids

[0208] As mentioned above, the exemplary sizing composition disclosed herein comprises at least one organic acid. The organic acid is used to adjust the pH to enable the hydrolysis of the silane coupling agent. The organic acid disclosed in the present invention comprises at least one weak acid. Examples of suitable weak acids that may be used in the sizing composition disclosed herein include, but are not limited to, acetic acid, succinic acid, citric acid, and combinations thereof. In some exemplary embodiments, the weak acid component comprises or consists of acetic acid. The sizing composition disclosed herein has a pH of about 3.0 to about 7.5, preferably about 4.5 to about 5.5.

[0209] In a given exemplary embodiment, the sizing composition comprises an organic acid in an amount such that the organic acid constitutes 0.01 wt% to 50 wt% of the solid content of the sizing composition. For example, the organic acid constitutes 0.05 wt% to 40 wt% of the solid content of the sizing composition based on the total solids of the sizing composition, and comprises 0.1 wt% to 30 wt%, 0.5 wt% to 25 wt%, 0.75 wt% to 22 wt%, 1.0 wt% to 20 wt%, 1.5 wt% to 18 wt%, and 2.0 wt% to 15 wt%. In a given exemplary embodiment, the organic acid has an active solid content of 25 to 99%, which comprises 40 to 90%, and 70 to 85%. In a given exemplary embodiment, the organic acid has an active solid content of about 80% + / - 3%.

[0210] cationic surfactants

[0211] The exemplary sizing composition disclosed herein further comprises a cationic surfactant. The cationic surfactant acts as a "wet lubricant" and serves to increase the dispersion of glass fibers in a white water solution during the formation of a mat made of the spinning fibers of the present invention.

[0212] Suitable examples of cationic surfactants include, but are not limited to, polyamides of imidazoline and alkyl imidazoline derivatives, aminoethyl imidazoline, stearic acid ethanolamide, such as acetic acid, C5-C9 carboxylic acids, and diethylenetriamine-ethyleneimine, available as Lubesize K-12 (Alpha / Owens Corning (Ontario, Canada)) and Katax® 6760L (Pulcra Chemicals). A preferred cationic emollient is an acetic acid salt of the reaction product of tetraethylenepentamine converted to about 91% imidazoline groups and stearic acid, available as Lubesize K-12.

[0213] Imidazolin is a thermally stable organic nitrogenous base. Lipophilic, unneutralized imidazoline is generally soluble in non-polar solvents and mineral oils, but tends to be dispersed only in aqueous systems. The cation-forming ability of imidazoline causes it to adsorb strongly onto negatively charged surfaces of metals, fibers, plastics, glass, and minerals, thereby converting these hydrophilic surfaces into hydrophobic ones. Imidazolin salts tend to be much more hydrophilic than their bases and function as acid-stable detergents with excellent wetting properties. The compatibility of imidazoline in aqueous systems can be improved through the use of suitable solubilizers.

[0214] In a predetermined exemplary embodiment, the sizing composition comprises a cationic surfactant in an amount such that the cationic surfactant constitutes 25% to 90% by weight of the total solid content of the sizing composition. In a predetermined exemplary embodiment, the cationic surfactant constitutes 30% to 80% by weight of solids based on the total solid content of the sizing composition, which includes, for example, 35% to 75% by weight, 37% to 72% by weight, and 40% to 70% by weight of solids, including all endpoints and sub-ranges between them. In a predetermined exemplary embodiment, the cationic surfactant has an active solid content of 0.5% to 20%, which includes 1% to 15% and 5% to 10%. In a predetermined exemplary embodiment, the cationic surfactant has an active solid content of about 9% + / - 3%.

[0215] As mentioned above, the sizing composition disclosed herein may be formed in the absence of a film-forming agent material, which may include polymer materials such as, for example, amide polymers, acrylic polymers, polyester polymers, epoxy polymers, etc. Traditionally, when a sizing composition containing a film-forming agent is dried, the film-forming agent combines to form a film on the fiber. The film-forming agent functions to protect the fiber from damage during processing and imparts compatibility between the fiber and other end-use materials. However, the sizing composition disclosed herein is formed using a reduced amount of chemicals and provides sufficient fiber protection without the use of a film-forming agent. Nevertheless, various embodiments of the exemplary sizing composition disclosed herein may optionally include a film-forming agent.

[0216] The exemplary sizing composition disclosed herein also comprises water. The sizing composition contains an amount of water sufficient to dilute the solids of the sizing composition to a viscosity suitable for application to spinning fibers. According to a given exemplary embodiment, the sizing composition comprises an amount of water of 80% to 99.9% by weight based on the total weight of the sizing composition, which comprises, for example, 85% to 98% by weight, or 90% to 99.5% by weight. The total solid content of the sizing composition may be 0.5% by weight to about 20% by weight, which comprises 2% to 10% by weight. Preferably, the sizing composition has a total solid content of 3% to 6% by weight, and more preferably about 5% by weight.

[0217] In a given exemplary embodiment, the sizing composition comprises, substantially consists of, or is composed of, a silane coupling agent in an amount of 25% to 35% by weight of solids, an organic acid in an amount of about 2% to 20% by weight of solids, and a cationic surfactant in an amount of 50% to 70% by weight of solids, based on the total solids content of the sizing composition. In any exemplary embodiment, the sizing composition may comprise, substantially consist of, or is composed of, a γ-aminopropyltriethoxysilane coupling agent in an amount of 25% to 35% by weight of solids, an acetic acid in an amount of 2% to 20% by weight of solids, based on the total solids content of the sizing composition, and an imidazoline derivative coupling agent in an amount of 50% to 70% by weight of solids, based on the total solids content of the sizing composition.

[0218] The exemplary sizing compositions disclosed herein may also include other components commonly used in sizing compositions. For example, the sizing composition may optionally include wetting agents, surfactants, lubricants, antioxidants, dyes, oils, fillers, heat stabilizers, defoaming agents, dust suppressants, antimicrobial agents, antistatic agents, fungicides, biocides, film-forming agents, chopping aids, thickeners, and / or other conventional additives. The amount of the aforementioned optional components in the sizing composition may be in the range of 0% to 90% by weight based on the dry solid content of the sizing composition, which includes, for example, 0% to 50% by weight, or 0% to 30% by weight.

[0219] The exemplary sizing compositions disclosed herein may be prepared by combining their components according to any method known to those skilled in the art. In a given exemplary embodiment, the viscosity of white water at room temperature is preferably greater than 2.0 cps, more preferably 2.0 to 5 cps, and still more preferably about 3.0 to 3.5 cps.

[0220] A range of exemplary sizing compositions is provided in Table 7 below. It should be understood that any of the disclosed ranges of sizing compositions A through C in Table 7 may be used in combination with any other disclosed range of compositions in this specification and is not limited to any specific combination of the ranges provided in this specification.

[0221] [Table 7]

[0222]

[0223] In some exemplary embodiments, the sizing composition is substantially cationic. The charge of the sizing composition can be described in terms of its zeta potential over various pH values. Zeta potential is a charge that manifests at the interface between a solid surface (e.g., particulate matter) and its liquid medium. The sizing composition of the concept of the present invention has a zeta potential having an absolute value greater than 20 than the pH. In particular, the sizing composition has a zeta potential having an absolute value greater than 30 in the pH range of 2 to 4. The sizing composition has a zeta potential having an absolute value greater than 20 in the pH range of 2 to 6.

[0224] For illustrative purposes, a sizing formulation (IF) of the present invention, formed according to the concept of the present invention and with about 70 wt% solid cationic surfactant, was compared with a first conventional reference sizing formulation (RF-1) applied to an equivalent fiber and a second conventional reference sizing formulation (RF-2) applied to another equivalent fiber. Both RF-1 and RF-2 contained about 20 wt% to 40 wt% cationic lubricant. In each case, a specific sizing formulation was applied to a conventional WUCS fiber at the same or lower wt% using a roll coating technique. In FIG. 5, a graph (500) of the zeta potential of each formulation is plotted against pH. Generally, the larger the magnitude of the zeta potential, the more cationic the formulation.

[0225] As illustrated in graph (500), the larger zeta potential of IF at both high and low pH means that the sized fiber exhibits amphoteric behavior, which means it can act as an acid or a base. This characteristic indicates that the fiber sized with IF is well dispersed in both acidic and basic environments. To achieve suitable dispersion, it is generally desirable to have a zeta potential with an absolute value greater than 20 at a pH of 2 to 6.

[0226] Additionally, the total composition of the sizing chemical (e.g., IF) contains about 70 weight% solids, which is more cationic lubricant than traditional sizing chemicals (e.g., RF-1, RF-2), which typically range from 0 to 40 weight% solids.

[0227] The exemplary sizing compositions disclosed herein may be substantially “colorless” compared to traditional sizing compositions. In exemplary embodiments, the sizing compositions disclosed herein exhibit a ΔL* value of -5 to +5 on the fiber. In certain exemplary embodiments, the sizing compositions disclosed herein exhibit a ΔL* value of 0 to +2.5 on the fiber, including a ΔL* value of +2. In exemplary embodiments, the sizing compositions disclosed herein exhibit a Δa* value of -10 to +10 on the fiber. In certain exemplary embodiments, the sizing compositions disclosed herein exhibit a Δa* value of -8 to +2 on the fiber, including a Δa* value of about -6. In exemplary embodiments, the sizing compositions disclosed herein exhibit a Δb* value of -10 to +10 on the fiber. In a given exemplary embodiment, the sizing composition disclosed herein exhibits a Δb* value of -5 to +5, including a Δb* value of about 0 on the fiber.

[0228] The sizing composition may be applied to the fibers such that the sizing composition is present on the fibers in an amount of 0.05 wt% to 2 wt% based on the total weight of the sizing fibers. The amount of the sizing composition present on the fibers is also referred to as the “strand solid content.” In a given exemplary embodiment, the sizing composition is present in an amount of 0.08 wt% to 1.0 wt% based on the total weight of the sizing fibers, which includes 0.1 wt% to 0.8 wt%, 0.2 wt% to 0.6 wt%, and also includes 0.35 wt% to 0.55 wt% based on the total weight of the sizing fibers. This may be determined by the loss on ignition (LOI) of the sizing fibers, which is the weight reduction experienced by the sizing fibers after heating the sizing fibers to a temperature sufficient to burn or pyrolyze the sizing composition from the fibers.

[0229] The sizing composition of the present invention may be further applied at a lower level when evaluated based on the surface area of ​​the fiber. For example, the spin fiber of the present invention described herein is, for example, 0.5 mg / cm² 2 to 3.8 mg / cm² 2 , 0.75 mg / cm 2 to 3.4 mg / cm² 2 , 1 mg / cm 2 to 3 mg / cm² 2 , or 1.15 mg / cm² 2 to 2.5 mg / cm² 2 Including, approximately 4 mg / cm² 2 While less than strand solids can be applied thereon, traditional WUCS fibers have 4 to 24 mg / cm² 2 The strand solid can be applied on it.

[0230] In exemplary embodiments, the moisture content of the sized fibers includes less than 7%, less than 6%, and 5% or less, having a final moisture content of less than 10%. A reduction in the final moisture content (i.e., increased dryness of the fibers) can provide benefits such as reduced transportation costs while reducing / avoiding the need for antimicrobial agents in the sizing composition.

[0231] Non-woven fabric mat

[0232] The spun fibers of the present invention can be used to form other materials, such as nonwoven mats. Fiber mats can be formed by known processes, such as the wet-laid process. In the wet-laid process, discrete fibers are dispersed in a water slurry containing a surfactant, a thickener, an antifoaming agent, and / or other chemicals. The water and chemical components are often referred to as a "white water" solution. Subsequently, the slurry containing the fibers is stirred in a mixing tank so that the fibers are dispersed throughout the slurry. The slurry containing the dispersed fibers is deposited onto a transfer screen, where a significant amount of water is removed to form a web of randomly oriented fibers. A binder is applied to the collection of fibers, which then passes through an oven to dry the fibers (i.e., remove any residual water from the fibers) and cure the binder to form a mat. In addition to being applied in an aqueous form, the binder can also be applied in a dry (powder) form. For example, swelling polyvinyl alcohol (PVA) powder may be added to the fiber mixture, where the PVA binder effectively binds the fibers as they pass through an oven / dryer.

[0233] Generally, any binder suitable for forming conventional nonwoven fiber mats may be used. Exemplary binder compositions useful for producing nonwoven mats include formaldehyde-free (or formaldehyde-free ("NAF")) binders, such as carboxyl-based binder compositions, polyvinyl alcohol-based binder compositions, carbohydrate-based binder compositions, etc. Such binders are free of added formaldehyde, are environmentally friendly, and are "green." In some embodiments, the binder may include one or more bio-derived materials. However, in some exemplary embodiments, the binder composition may include a formaldehyde system, such as a urea-formaldehyde system.

[0234] The binder may include a thermosetting binder or a thermoplastic binder. For example, the binder may include a thermosetting binder having at least one polycarboxylic polymer as a thermosetting binder resin. The polycarboxylic polymer comprises an organic polymer or oligomer containing more than one pendant carboxyl group. The polycarboxylic polymer may be a homopolymer or copolymer prepared from one or more unsaturated carboxylic acids, including but not limited to acrylic acid, methacrylic acid, crotonic acid, isocrotonic acid, maleic acid, cinnamic acid, 2-methylmaleic acid, itaconic acid, 2-methylitaconic acid, α,β-methyleneglutaric acid, etc. Alternatively, the polycarboxylic polymer may be prepared from unsaturated anhydrides, including but not limited to maleic anhydride, itaconic anhydride, acrylic anhydride, methacrylic anhydride, etc., as well as mixtures thereof. The polymerization of these acids and anhydrides is considered to be within the capabilities of those skilled in the art.

[0235] In some exemplary embodiments, the binder composition comprises a thermosetting acrylic package comprising a blend of a thermosetting hydrophilic acrylic binder material and a hydrophobic acrylic binder material. The thermosetting acrylic package may comprise, but is not limited to, an acrylic emulsion, an acrylic solution, or a mixture thereof. The thermosetting nature of the acrylic package reduces the tackiness of the binder and thus reduces the binder from adhering to processing equipment during the manufacturing process. In some embodiments, the thermosetting acrylic package comprises a mixture of an acrylic homopolymer and a styrene-acrylic latex. The acrylic homopolymer may be present in an amount of about 50% by weight to about 80% by weight, or about 60% by weight to about 75% by weight, based on the total weight of the precursor binder solid. The styrene-acrylic latex may be present in an amount of about 20% by weight to about 45% by weight, or about 25% by weight to about 40% by weight, based on the total weight of the binder solid.

[0236] The binder composition may optionally further comprise an antifoaming agent. In some exemplary embodiments, the antifoaming agent comprises one or more of siloxanes, mineral oils, and polyoxalkylenes, but any antifoaming agent may be used alternatively. An exemplary antifoaming agent comprises a polyether siloxane, such as Tego® Foamex 1488 (available from Evonik). In some exemplary embodiments, the antifoaming agent is present in the binder composition in an amount of about 0.001% to about 1.0% by weight, including about 0.01% to about 0.25% by weight based on the total weight of the solids in the precursor binder composition.

[0237] In a predetermined embodiment, the binder composition may optionally contain at least one coupling agent. In a predetermined embodiment, the coupling agent is a silane coupling agent. The coupling agent may be present in the binder composition in an amount of 0.01% to 5% by weight (based on dry weight), 0.01% to 2.5% by weight (based on dry weight), 0.1% to 0.5% by weight (based on dry weight), or 0.15% to 0.25% by weight (based on dry weight).

[0238] Non-limiting examples of silane coupling agents that can be used in a coupling composition may be characterized by functional groups including, but not limited to, alkyl, aryl, amino, epoxy, vinyl, methacryloxy, ureido, isocyanato, and mercapto. In a given embodiment, the silane coupling agent comprises a silane containing one or more nitrogen atoms having one or more functional groups such as amines (primary, secondary, tertiary, and quaternary), amino, imino, amido, imido, ureido, or isocyanato. Specific and non-limiting examples of suitable silane coupling agents include, but are not limited to, aminosilanes (e.g., γ-aminopropyltriethoxysilane and γ-aminopropyl-trihydroxysilane), epoxytrialkoxysilanes (e.g., 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane), methacryltrialkoxysilanes (e.g., 3-methacryloxypropyltrimethoxysilane and 3-methacryloxypropyltriethoxysilane), hydrocarbon trialkoxysilanes, aminotrihydroxysilanes, epoxytrihydroxysilanes, methacryltrihydroxysilanes, and / or hydrocarbon trihydroxysilanes.

[0239] The binder composition may also include one or more additional additives, such as extenders, catalysts, processing aids, dust inhibitors, viscosity modifiers, pH adjusters, crosslinking density enhancers, deodorizers, antioxidants, moisture-resistant agents, or combinations thereof. Optionally, the binder may include, without limitation, dyes, pigments, additional fillers, colorants, UV stabilizers, heat stabilizers, emulsifiers, preservatives (e.g., sodium benzoate), corrosion inhibitors, and mixtures thereof. Other additives may be added to the binder composition to improve process and product performance. Such additives include lubricants, wetting agents, antistatic agents, and / or water-repellent agents. Additives may be present in the precursor binder composition in trace amounts (e.g., about 0.1% or less based on the weight of the binder composition) up to about 10% based on the weight of the total solids in the binder composition.

[0240] In some exemplary embodiments, the binder may comprise a filled binder comprising one or more main fillers (e.g., mineral fillers). In this case, the main filler may be present in the filled binder composition at a maximum of about 50% based on the weight of the total solids in the filled binder composition.

[0241] The binder further comprises water to dissolve or disperse the active solid for application to the fiber. Water can be added in an amount sufficient to dilute the aqueous binder composition to a viscosity suitable for application to the fiber and to achieve the desired solid content on the fiber.

[0242] In some exemplary embodiments, the binder composition comprises about 15% to about 27% by weight and about 16% to about 25% by weight, and is included in the fiber mat in an amount of about 10% to about 30% by weight.

[0243] The uniformity of fiber arrangement within a nonwoven sheet-type mat contributes to the strength of the mat and the ultimate final product. Other benefits, such as improved aesthetics, can also be attributed to the increased uniformity of fiber arrangement. One challenge in manufacturing uniform fiber mats from aqueous dispersions is that fibers (e.g., glass fibers) do not disperse easily in the aqueous medium. This difficulty in fiber dispersion arises when fibers are initially added to the water. Dispersibility is further complicated by the tendency of fibers that are somewhat scattered within the aqueous medium to re-aggregate to some extent. Re-aggregated fibers are very difficult to redisperse. The lack of good fiber dispersion within the aqueous medium hinders the formation of a uniform mat and negatively affects the properties (e.g., strength, appearance) of the final product containing the mat or the resulting sheet-type mat. This dispersibility issue can be exacerbated when mixing fibers of smaller diameter (e.g., spun fibers) with fibers of larger diameter (e.g., non-spun fibers such as WUCS).

[0244] A suitable dispersion of the aqueous mixture can be obtained by any suitable means as long as a uniform or substantially uniform distribution of two (or more) groups of different glass fibers in the aqueous medium is produced. In some exemplary embodiments, a uniform distribution of two groups of different glass fibers is produced. In some exemplary embodiments, a substantially uniform distribution of two groups of glass fibers is produced. The dispersion can be obtained by a high-shear mixing device, such as a rotor / stator mixer. Without being bound by theory, the inventors believe that a high degree of dispersion and distribution mixing contributes to the production of a fibrous nonwoven mat in which the number of undispersed or partially dispersed fibers (e.g., flocks) per surface of the bonded nonwoven mat is substantially zero or small.

[0245] In some exemplary embodiments, a substantial portion (e.g., at least 10 weight%) of the fibers used to form the nonwoven mat, though not all, of the fibers is the spin fiber of the present invention as described herein. In some exemplary embodiments, the nonwoven mat is formed from a blend of a first fiber and a second fiber (i.e., the spin fiber of the present invention), wherein the first fiber has an average diameter > 6.5 μm and the second fiber has an average diameter < 6.5 μm. In some exemplary embodiments, the first fiber has an average diameter in the range of about 6.5 μm to about 15 μm. In some exemplary embodiments, the second fiber has an average diameter in the range of about 1 μm to about 6 μm. In some exemplary embodiments, both the first fiber and the second fiber are glass fibers. In some exemplary embodiments, the first fiber is not a spin-forming fiber.

[0246] In some exemplary embodiments, the spin fibers of the present invention undergo preprocessing before being introduced (along with other fibers) into a mixing tank of a wet-laid process. The preprocessing may serve to convert the fibers from a stored (e.g., compressed) form into a form more suitable for the wet-laid process, may serve to condition the fibers for wet-laid processing (e.g., to promote dispersibility), and may serve to evaluate the fibers for defects (e.g., to remove flocks or potential flocks).

[0247] For example, a preprocessing associated with the production of a nonwoven bale by a wet-laid process involving mixing the spin fibers of the present invention with wet-cut chopped strands of glass (WUCS) will be described with reference to the figure (1200) of FIG. 12. In this example, the spin fibers of the present invention are ultimately mixed with WUCS in a slurry, wherein the percentage of spin fibers in the total blend of glass fibers can vary from 1% to 99% w / w%. Before producing a nonwoven bale using this mixture of two glass-based fibers in a wet-laid process, the spin fibers are wetted and dispersed in a separate process before being mixed with WUCS.

[0248] In the first step (1202), a large amount of rotating fibers is loaded onto a conveyor and supplied into a mixing tank.

[0249] In the next step (1204), the spin fibers are fed into a mixing tank containing an aqueous solution of a surfactant, a viscosity modifier, a polymer binder, and other process chemical aids. The spin fibers are gradually added into the mixing tank so that individual fibers are sufficiently wetted in the aqueous solution. The shape of the tank and the agitator are designed to ensure appropriate shear energy input and volume displacement velocity, while also blocking any continuous vortices formed. Spin fibers with a large surface area-to-mass ratio are completely wetted in the aqueous solution. The single dose level of spin fibers in the mixing tank varies from 5 to 50 g / L.

[0250] In the next step (1206), after sufficient dispersion, the rotary fiber aqueous suspension is pumped through a screening unit to remove any possible large impurities in the raw material. The screening device may be changed according to the required fineness of the rotary fiber suspension.

[0251] The spun fiber raw material may contain fiber aggregates that are difficult to completely wet and disperse in the initial mixing process (step (1204)). These aggregates may manifest as defects (e.g., "flocs") in the nonwoven mat. Therefore, in the next (optional) step (1208), a device such as a high-shear mixer may be used to break these fiber flocks. In the high-shear mixer, the fiber suspension passes through a slotted rotor / stator system that homogenizes the fiber suspension, thereby helping to break the fiber flocks.

[0252] Finally, in step (1210), the pre-processed spin fiber is transferred to a mixing tank for the wet process, where the spin fiber can be more effectively dispersed in a white water solution together with other fibers.

[0253] In light of the above, in one method of the present invention for producing a nonwoven mat using a blend of fibers including the spin fibers of the present invention (wherein the percentage of spin fibers in the total blend of glass fibers may vary from 1% to 99% w / w%), the present invention comprises the steps of dispersing the spin fibers in a first white water solution and then adding the dispersed spin fibers to a second white water solution containing non-spin fibers. In some exemplary embodiments, the non-spin fibers are WUCS fibers. In some exemplary embodiments, the non-spin fibers have an average fiber diameter larger than that of the spin fibers.

[0254] In some exemplary embodiments, individual aqueous mixtures of glass fibers of the first and second groups are each prepared and then combined by stirring (e.g., high-intensity mixing) to provide a uniform or nearly uniform dispersion of the fiber blend.

[0255] In some exemplary embodiments, the glass fibers of the first group and the glass fibers of the second group are combined to form a dry mixture of glass fibers. The dry mixture is then formed into an aqueous mixture by stirring (e.g., high-intensity mixing) to provide a uniform or substantially uniform dispersion of the fiber blend.

[0256] Because the spin fiber of the present invention (manufactured by process (300) or a similar process) may substantially have no or substantially reduced non-fiberized or poorly fiberized material (generally referred to as "shot"), fused fibers, aggregated fibers (e.g., flock), and / or other forms of defective fibers as mentioned above, the nonwoven mat manufactured from the spin fiber of the present invention (e.g., a nonwoven mat comprising part (1010)) may likewise have fewer defects and, accordingly, have improved properties (e.g., surface smoothness, surface appearance).

[0257] For example, the nonwoven mat has a first surface (1012) and a second surface (not shown) opposite to the first surface (1012). In some exemplary embodiments, at least one surface of the nonwoven mat is a nonwoven mat 1,000 m 2 It has approximately fewer than 100 flocks per unit. In some exemplary embodiments, each surface of the nonwoven mat is a nonwoven mat 1,000 m 2 It has approximately 100 or fewer flocks per layer. In some exemplary embodiments, at least one surface of the nonwoven mat is a nonwoven mat 1,000 m 2 It has fewer than about 50 flocks per unit. In some exemplary embodiments, each surface of the nonwoven mat is a nonwoven mat 1,000 m 2 It has fewer than about 50 flocks per. In some exemplary embodiments, at least one surface of the nonwoven mat is a nonwoven mat 1,000 m 2It has fewer than about 25 flocks per layer. In some exemplary embodiments, each surface of the nonwoven mat is a nonwoven mat 1,000 m 2 It has fewer than about 25 flocks per layer. In some exemplary embodiments, at least one surface of the nonwoven mat is a nonwoven mat 1,000 m 2 It has fewer than about 15 flocks per layer. In some exemplary embodiments, each surface of the nonwoven mat is a nonwoven mat 1,000 m 2 Each has approximately 15 or fewer flocs.

[0258] In some exemplary embodiments, on at least one surface of the nonwoven mat, 1,000 m of the nonwoven mat 2 There is substantially no flock whatsoever. In some exemplary embodiments, 1,000 m of nonwoven mat is applied to each surface of the nonwoven fabric. 2 There is practically no floc.

[0259] One method to evaluate or otherwise estimate the number of flocks in a nonwoven mat is (1) about 500 m 2 Unwind a roll of nonwoven mat representing the total surface area, (2) manually count a loosely clumped mass of fibers visible to the naked eye under standard or ambient lighting, and (3) the result of the counting to a larger surface area (e.g., 1,000 m² 2 It involves converting (extrapolating) the value into the number of flocs. Other suitable methods for counting the number of flocs within a given surface area are also considered. For example, image processing techniques are used for a relatively large portion of a nonwoven mat (e.g., ≥ 500 m² 2 It can generate an image corresponding to ) and then automatically evaluate the image for the case of flocks within it. Generally, a smaller portion of the nonwoven mat material (e.g., < 500 m 2It has been found that evaluating ) yields less reliable estimates of the floc count because the floc is often distributed across a larger portion of the manufactured mat (roll).

[0260] Generally, nonwoven mats are designed to have sufficient strength to withstand the processing steps and speeds required to produce nonwoven mats for various end applications. Additionally, the strength of the nonwoven mat must be sufficient to allow the mat to be stored in any desirable form, possibly for a long period, without loss of its cohesive properties. The improved fiber diameter and / or fiber length distribution of the spin fibers of the present invention is expected to improve the structure and homogeneity or uniformity of the arrangement of glass fibers within the nonwoven mat, which will lead to more consistent and distinct strength characteristics for the mat.

[0261] Exemplary application examples

[0262] There are many applications for nonwoven fibrous mats produced using the spin fibers of the present invention as described herein. Generally, any conventional nonwoven mat can be replaced with the nonwoven mat(s) of the present invention, which provide improved properties (e.g., surface smoothness, mechanical strength). Examples of potential uses include, but are not limited to, roofing materials (e.g., roofing sheaths), surface finishing bales for composites, ceiling tiles, building boards, filtration media, flooring applications, wallpaper, and battery separators.

[0263] One such application is as a surface finishing material ("surface material") for ceiling tiles. The surface material is intended to be bonded to a core substrate (e.g., gypsum board, polyisoboard, mineral wool insulation board) or otherwise to form an interface with it. Further processing of the surface finishing substrate (e.g., by painting) forms the ceiling tile.

[0264] Typically, a nonwoven mat (as a “base mat”) will be impregnated with an inorganic filler (e.g., calcium carbonate (CaCO3), alumina trihydrate (ATH), kaolin) and a secondary binder to form an “impregnated mat.” The selection and application of the filler are controlled to achieve desired aesthetic properties (e.g., color, smoothness) while still maintaining the necessary sound insulation properties (e.g., porosity).

[0265] In various exemplary embodiments, the base mat and / or impregnated mat is formed using the spin fibers of the present invention as described herein. In some exemplary embodiments, a blend of WUCS glass fiber (as a first fiber) and spin glass fiber (as a second fiber) is used to form the base mat and / or impregnated mat.

[0266] Generally, the average diameter of the second fiber is smaller than the average diameter of the first fiber, and the average (processed, e.g., milled) length of the second fiber is smaller than the average (processed, e.g., chopped) length of the first fiber. Furthermore, as described herein, the average fiber diameter distribution and / or average fiber length distribution of the spin fiber of the present invention are much more concentrated (in terms of volume) near the target fiber diameter and / or target fiber length than in conventional spin fibers.

[0267] In some exemplary embodiments of the nonwoven mat of the present invention, the average fiber diameter of the first fiber is in the range of 10 μm to 11 μm; and the average fiber diameter of the second fiber is in the range of 3 μm to 4 μm. In some embodiments, the average processed fiber length of the first fiber is approximately 6 mm; and the average processed fiber length of the second fiber is in the range of 1 mm to 6 mm. For reference, relatively small fiber diameter values ​​are often expressed in micrometers (μm) or one hundred thousandth of an inch (HT), where 1 HT = 0.254 μm / micrometer (or 1 μm / micrometer = 3.937 HT).

[0268] For example, while a conventional spin fiber forming process will produce spin fibers (from the fiberizer (10)) having a forming length of approximately 12.7 mm (0.5 inches) to 50.8 mm (2 inches), the spin fiber forming process of the present invention (e.g., process (300)) will produce spin fibers (from the fiberizer (10)) having a forming length of approximately 76.2 mm (3 inches) to 304.8 mm (12 inches). These longer fiber lengths provide increased flexibility in downstream processing of the fibers as well as more control over the characteristics of the final product.

[0269] In some exemplary embodiments of the nonwoven mat of the present invention, the first fiber and the second fiber are bonded to each other by a polyvinyl alcohol (PVOH) binder.

[0270] The nonwoven mat of the present invention may or may not include a coating (i.e., impregnation) that penetrates into the mat. The coating may be considered as a combination of inorganic mineral fillers (e.g., alumina trihydrate and / or calcium carbonate), secondary binders (i.e., PVOH and / or acrylic emulsions), and other additives (e.g., defoamers, dispersants, repellents).

[0271] In an exemplary embodiment, the nonwoven mat is an unfilled product to which no coating or impregnation is applied, comprising a first fiber (with an average diameter in the range of 10 μm to 11 μm and an average processing length of about 6 mm), a second fiber (with an average diameter in the range of 3 μm to 4 μm and an average processing length in the range of 1 mm to 6 mm), and a PVOH binder as described above. In this embodiment, the mat comprises approximately 64 weight% of the first fiber, approximately 21 weight% of the second fiber, and approximately 15 weight% of the binder.

[0272] In another exemplary embodiment, the nonwoven mat is a low-filling product to which a coating / impregnation is applied, comprising a first fiber (with an average diameter in the range of 10 μm to 11 μm and an average processing length of about 6 mm), a second fiber (with an average diameter in the range of 3 μm to 4 μm and an average processing length in the range of 1 mm to 6 mm), and a PVOH binder as described above. In this embodiment, the mat comprises about 32 wt% of the first fiber, about 11 wt% of the second fiber, and about 7 wt% of the primary PVOH binder, as well as about 50 wt% of the coating (i.e., 47 wt% of the inorganic filler and about 3 wt% of the secondary binder).

[0273] In another exemplary embodiment, the nonwoven mat is a high-fill product to which a coating / impregnation is applied, comprising a first fiber (with an average diameter in the range of 10 μm to 11 μm and an average processing length of about 6 mm), a second fiber (with an average diameter in the range of 3 μm to 4 μm and an average processing length in the range of 1 mm to 6 mm), and a PVOH binder as described above. In this embodiment, the mat comprises about 13 wt% of the first fiber, about 4 wt% of the second fiber, and about 3 wt% of the primary PVOH binder, as well as about 80 wt% of the coating (i.e., 75 wt% of the inorganic filler and about 5 wt% of the secondary binder).

[0274] As mentioned above, a conventional application for the base mat or impregnated mat of the present invention is as a ceiling tile surface material. The mat of the present invention is expected to contribute to characteristics important to the function and / or customer acceptance of the finished ceiling tile (at least by including the spin fiber of the present invention). These characteristics may include reduced turbidity, increased opacity, and improved orientation. Orientation refers to the phenomenon in which the ceiling tile has different perceived visual effects when rotated 90 degrees. Furthermore, the mat of the present invention may have a smoother surface, which may reduce the amount of coating required to achieve the desired aesthetics. Furthermore, the mat of the present invention may have a desired surface porosity so that the ceiling tile exhibits acceptable acoustic performance.

[0275] For example, as described in this specification, it has been found that ceiling tiles made of a surface material formed from a nonwoven mat of the present invention exhibit reduced turbidity compared to similar surface materials made from conventional nonwoven mats.

[0276] To evaluate the turbidity of ceiling tiles surface-treated with non-woven fiber mats, a device called the cloud-runner Mottling Meter Control of Paint Mottling ("cloud-runner" device), manufactured by BYK-Gardner GmbH in Geretsried, Germany, was used. The cloud-runner device is typically sold to the automotive industry for measuring paint mottling (e.g., spots, blotches, clouds) of automotive finishes. The cloud-runner device can measure irregular brightness fluctuations by simulating visual evaluation under three different viewing angles, as illustrated in Figure 6 (600), and can characterize clouds / mottles by their size and visibility. In this way, the cloud-runner device has been proven to be an effective tool for quantifying and ranking the turbidity of ceiling tile surfaces.

[0277] The cloud runner device can measure "clouds" of different sizes (i.e., color variation / deviation) and provide numeric grades / values ​​indicating the turbidity of the sample. As shown in Table 8, each range of clouds requires a minimum scan length to be measured. The cloud runner device supports scan lengths from 10 cm to 100 cm and is selectable in 1 cm increments.

[0278] [Table 8]

[0279]

[0280] To evaluate ceiling tile surface material products, clouds within Md, Me, Mf, and Mg were measured. Data were collected using a cloud runner device set to a scan length of 23 cm. Five passes of this scan length were performed over the width or length of a sample of A3 (297 mm × 420 mm) or A4 (210 mm × 297 mm) size to obtain a single measurement. Unpainted and unfilled sample sheets were measured on a black background.

[0281] As illustrated in the graph (700) of FIG. 7, the effect of the ratio (x-axis) of adding finer (i.e., smaller diameter) glass fibers to a large amount of larger diameter (i.e., 10 μm) glass fibers on the "turbidity" grade (y-axis) of the nonwoven fiber mat was evaluated. In particular, a series of nonwoven sample mats were prepared using different blend ratios (0% to 40%) of 6.5 μm non-rotated WUCS glass fibers added to 10 μm WUCS glass fibers, and a series of nonwoven sample mats were also prepared using different blend ratios (0% to 40%) of 3.5 μm rotary formed glass fibers of the present invention added to 10 μm WUCS glass fibers. In this way, a sample containing 6.5 μm non-rotating WUCS glass fibers was compared with a sample containing 3.5 μm rotating glass fibers of the present invention at different loading percentages (%) across all three viewing angles (15°, 45°, and 60°) of the cloud runner device. It was found that containing 3.5 μm rotating fibers of the present invention reduced turbidity grades for both smaller (9 mm to 13 mm and 11 mm to 24 mm) clouds and larger (19 mm to 42 mm and 33 mm to 72 mm) clouds more effectively than 6.5 μm WUCS fibers. For example, while 3.5 μm rotating fibers of the present invention reduced turbidity grades for both smaller and larger clouds, 6.5 μm WUCS fibers had no significant effect on larger clouds. Furthermore, the 3.5 μm spin fiber of the present invention showed a much steeper reduction in turbidity grade according to the loading level (%) compared to the 6.5 μm WUCS fiber. In particular, at a 40% loading, the 3.5 μm spin fiber of the present invention showed an approximately 35% reduction in turbidity grade for 9 mm to 13 mm clouds, whereas at the same loading percentage, 6.The 5 μm WUCS fibers showed only an approximately 18% reduction in turbidity grade for clouds within this size range. Additionally, at a 40% loading, the 3.5 μm spin fibers of the present invention showed an approximately 45% reduction in turbidity grade for clouds between 33 mm and 72 mm, whereas at the same loading percentage, the 6.5 μm WUCS fibers did not show a significant reduction for clouds within this size range (0%). Therefore, due to its increased effect in the manufacture of ceiling tile surface materials with a reduced number of clouds, ceiling tiles with acceptable aesthetic properties can be achieved with a lower fiber loading of the 3.5 μm spin fibers of the present invention compared to the 6.5 μm WUCS fibers.

[0282] In another test, as illustrated in the graph (800) of FIG. 8, the effect of the ratio (x-axis) of adding smaller (i.e., 3.5 μm) rotated glass fibers of the present invention, medium (i.e., 6.5 μm) rotated glass fibers of the present invention, and larger (i.e., 10 μm) rotated glass fibers of the present invention to a large amount of 10 μm to 11 μm WUCS glass fibers was also evaluated on the "turbidity" grade (y-axis) of the nonwoven fiber mat. This test evaluated the effect of an increase in the average fiber diameter of the rotated glass fibers of the present invention on the turbidity grade (y-axis) found in ceiling tile surface materials manufactured using each blend of fibers. In particular, ceiling tile surface material samples were produced by adding each of the smaller, medium, and larger diameter rotating glass fibers of the present invention to 10 μm to 11 μm WUCS glass fibers at different loading percentages (%), and these were measured across all three viewing angles (15°, 45°, and 60°) of the cloud runner device. It was found that including 3.5 μm rotating glass fibers of the present invention resulted in a relatively large reduction in turbidity grade (e.g., 37% to 50%) in the sample ceiling tile surface material, including 6.5 μm rotating glass fibers of the present invention resulted in a more appropriate reduction in turbidity grade (e.g., about 26%) in the sample ceiling tile surface material, and including 10 μm rotating glass fibers of the present invention resulted in no significant reduction in turbidity grade (e.g., 0%) in the sample ceiling tile surface material.

[0283] Additionally, when comparing cloud runner data for the 3.5 μm rotating glass fiber of the present invention and the 6.5 μm WUCS glass fiber (Fig. 7), it can be seen that the 3.5 μm rotating glass fiber of the present invention exhibits better performance than the 6.5 μm WUCS glass fiber for clouds in the ranges of 9 mm to 13 mm, 11 mm to 24 mm, 19 mm to 42 mm, and 33 mm to 72 mm. Part of this comparison is also illustrated in the graph (900) of Fig. 9a for a 60° field of view of the cloud runner device and for the smallest (9 mm to 13 mm) cloud and the largest (33 mm to 72 mm) cloud. Note that 60° is the widest supported field of view, at which point the cloud on the ceiling tile is best observed under oblique light.

[0284] Additionally, when comparing cloud runner data for the 6.5 μm rotating glass fiber of the present invention (Fig. 8) and the 6.5 μm WUCS glass fiber (Fig. 7), it can be seen that the 6.5 μm rotating glass fiber of the present invention exhibits comparable performance to the 6.5 μm WUCS glass fiber for clouds in the range of 9 mm to 13 mm (both achieving a reduction of about 18%), 11 mm to 24 mm, and 19 mm to 42 mm, while the 6.5 μm rotating glass fiber of the present invention exhibits better performance than the 6.5 μm WUCS glass fiber (20% reduction compared to 0% reduction) for clouds in the range of 33 mm to 72 mm. This comparison is also illustrated in the graph (910) of Fig. 9b for a 45° field of view of the cloud runner device.

[0285] From tests using a cloud runner device, it was found that for smaller clouds (i.e., clouds in the range of 9 mm to 13 mm), conventional ceiling tile surface materials typically have a turbidity grade of 27 or higher. However, by replacing about 8% of the conventional fibers with the 3.5 μm rotated glass fibers of the present invention, a turbidity grade of less than 27 could be easily achieved (see Fig. 9a). Additionally, by using more of the 3.5 μm rotated glass fibers of the present invention, the turbidity grade for these smaller clouds can be easily reduced to about 17 or lower (see Fig. 9a).

[0286] From tests using a cloud runner device, it was found that for larger clouds (i.e., clouds in the range of 33 mm to 72 mm), conventional ceiling tile surface materials typically have a turbidity grade of 19 or higher. However, by replacing about 3% of the conventional fibers with the 3.5 μm rotated glass fibers of the present invention, a turbidity grade of less than 19 could be easily achieved (see Fig. 9a). Additionally, by using more of the 3.5 μm rotated glass fibers of the present invention, the turbidity grade of these smaller clouds could be easily reduced to about 9 or lower (see Fig. 9a).

[0287] Other advantages may arise from this ability of the spin glass fibers of the present invention to reduce turbidity in nonwoven fibrous mats. For example, the effect of using conventional ULF microfibers (with an effective fiber diameter of approximately 3.00 μm) and the spin fibers of the present invention (with an effective fiber diameter of approximately 3.56 μm) in a nonwoven mat was evaluated. In particular, for large clouds (considered to be within the range of 19 to 42 mm) and a target turbidity grade of 15, it was determined that 40.58 weight percent of the mat would need to be conventional microfibers to achieve the target, whereas 31.88 weight percent of the mat would need to be the microfibers of the present invention to achieve the target. Thus, the spin fibers of the present invention are more efficient than other microfibers in reducing large clouds. From the above measurements, it was determined that 13.54 weight percent of the mat per 1 μm of conventional microfibers would be required to achieve the goal, whereas 8.96 weight percent of the mat per 1 μm of microfibers of the present invention would be required to achieve the goal. Therefore, if conventional microfibers and microfibers of the present invention are manufactured to have the same average fiber diameter, the spin fibers of the present invention will require less material to impart the same reduction in turbidity.

[0288] In some embodiments, it may be possible to use various concepts of the invention in combination with one another. Additionally, any specific element mentioned in connection with the specifically disclosed embodiments should be interpreted as available for use with all disclosed embodiments, provided that the incorporation of the specific element does not contradict the express conditions of the embodiments. The scope of the general concept of the invention presented herein is not intended to be limited to the specific exemplary embodiments shown and described herein. From the given disclosures, those skilled in the art will not only understand the general concept of the invention and its accompanying advantages, but will also discover various changes and modifications thereto. For example, despite exemplary embodiments that often disclose the use of glass fibers, alternative concepts of the invention may include fibers made of materials other than glass, such as mineral wool or rock wool. Accordingly, it is intended to encompass all such changes and modifications that fall within the spirit and scope of the general concept of the invention, as described and / or claimed herein, and any equivalent thereof.

Claims

Claim 1 A method for manufacturing mineral fibers, comprising the steps of: rotating a spinner having a peripheral wall including a plurality of orifices; feeding molten mineral material to the rotating spinner to centrifuge a stream of molten mineral material through the orifices; mixing combustion air and combustion gas and feeding the mixture to an annular burner located around the spinner; generating an annular flow of air induced within a passage located between the annular burner and an annular blower; directing the hot gas from the annular burner and the annular flow of air induced toward the spinner and the stream of molten mineral material to heat the spinner and elongate the stream of molten mineral material into a plurality of mineral fibers; and directing a source of cooling air to a quill pan located below the spinner through a hollow quill extending through the spinner, wherein the cooling air is delivered to the quill pan at a flow rate of about 30 cubic feet / min to about 60 cubic feet / min. Claim 2 In paragraph 1, the method wherein the quill fan is cooled to a temperature of less than 750℉. Claim 3 A method according to claim 1 or 2, further comprising the step of controlling a spinner to rotate at a speed of about 900 rpm (revolutions per minute) to about 2,400 rpm. Claim 4 A method according to any one of claims 1 to 3, wherein the hot gas from the annular burner is directed toward a stream of spinner and molten mineral material at a flow rate of about 240 cubic feet / min to about 300 cubic feet / min. Claim 5 A method according to any one of claims 1 to 4, wherein the annular blower outputs air of about 410 cubic feet / min to generate an annular flow of induced air. Claim 6 A method in which, in any one of paragraphs 1 to 5, the mineral fiber is a glass fiber. Claim 7 A method according to any one of claims 1 to 6, wherein the mineral fibers have an average diameter of less than 6 μm. Claim 8 A method according to any one of claims 1 to 7, wherein the mineral fiber has an average diameter of less than 5 μm. Claim 9 A method according to any one of claims 1 to 8, wherein the mineral fibers have an average diameter of less than 4 μm. Claim 10 A method according to any one of claims 1 to 9, wherein the mineral fiber has an average diameter of less than 3 μm. Claim 11 A method according to any one of claims 1 to 10, wherein the mineral fiber comprises at least 10,000 distinct fibers; the mineral fiber has an average fiber diameter x; and x is less than the median fiber diameter of the mineral fiber. Claim 12 A method according to any one of claims 1 to 11, wherein the mineral fiber comprises at least 10,000 distinct fibers; the mineral fiber has a target generated fiber diameter y; the mineral fiber has an average fiber diameter x; and y < 2x. Claim 13 A method according to any one of claims 1 to 12, wherein the mineral fiber comprises at least 10,000 distinct fibers; the mineral fiber has a target generated fiber diameter of less than 6.5 μm; the mineral fiber has an average fiber diameter x; and the standard deviation from x is less than 3.5 μm. Claim 14 In paragraph 13, the method in which the standard deviation from x is less than 3.0 μm. Claim 15 In paragraph 13, the method in which the standard deviation from x is less than 2.5 μm. Claim 16 A method according to any one of claims 1 to 15, wherein the mineral fiber comprises at least 10,000 distinct fibers; the mineral fiber has a fiber diameter distribution having two Gaussian peaks; the two Gaussian peaks represent ≥ 85% of the volume of the mineral fiber; and ≥ 40% of the volume of the mineral fiber is represented by a Gaussian peak corresponding to the minimum diameter of the mineral fiber. Claim 17 A method according to any one of claims 1 to 16, wherein the mineral fibers do not contain any fibers with a diameter greater than 22 μm. Claim 18 In paragraph 17, the mineral fibers do not contain any fibers with a diameter greater than 20 μm. Claim 19 In paragraph 17, the mineral fibers do not contain any fibers with a diameter greater than 16 μm. Claim 20 In paragraph 17, the mineral fibers do not contain any fibers with a diameter greater than 15 μm. Claim 21 In paragraph 17, the mineral fibers do not contain any fibers with a diameter greater than 14 μm. Claim 22 A method according to any one of claims 1 to 21, wherein the mineral fiber has an average formed length of more than 50.8 mm (2 inches). Claim 23 A method according to any one of claims 1 to 22, wherein the mineral fibers have an average formed length ranging from about 76.2 mm (3 inches) to about 304.8 mm (12 inches). Claim 24 A package of spin-forming fibers comprising at least 10,000 distinct fibers, wherein the fibers have an average fiber diameter x; and the fiber diameter distribution of the fibers has a standard deviation from x of less than 3.5 μm. Claim 25 In paragraph 24, a package in which the standard deviation from x is less than 3.0 μm. Claim 26 In paragraph 24, a package in which the standard deviation from x is less than 2.5 μm. Claim 27 In any one of paragraphs 24 to 26, the fiber is a package having an average diameter of less than 5 μm. Claim 28 In any one of paragraphs 24 to 26, the fibers are a package having an average diameter of less than 4 μm. Claim 29 In any one of paragraphs 24 to 26, the fiber is a package having an average diameter of less than 3 μm. Claim 30 In any one of paragraphs 24 through 29, the fiber is a package having an average formed length of more than 50.8 mm (2 inches). Claim 31 A package in which, in any one of paragraphs 24 through 29, the fiber has an average formed length ranging from about 76.2 mm (3 inches) to about 304.8 mm (12 inches). Claim 32 In any one of paragraphs 24 to 31, x is less than the median fiber diameter of the fiber, package. Claim 33 A package in which, in any one of paragraphs 24 to 32, 90% of the fibers have a diameter ≤ 1.525x. Claim 34 A package in which, in any one of paragraphs 24 through 33, the fiber is a glass fiber. Claim 35 In any one of claims 24 to 34, the mineral fiber comprises at least 10,000 distinct fibers; the mineral fiber has a fiber diameter distribution having a first Gaussian peak and a second Gaussian peak; and the first Gaussian peak and the second Gaussian peak represent ≥ 85% of the volume of the mineral fiber, package. Claim 36 In paragraph 35, the package, wherein ≥ 40% of the volume of the mineral fiber is represented by a first Gaussian peak corresponding to the minimum diameter of the mineral fiber. Claim 37 A nonwoven mat comprising a plurality of first fibers; a plurality of second fibers; and a binder that holds the first fibers and the second fibers together in an interleaved arrangement; wherein the first fibers have an average fiber diameter greater than about 7 μm; the second fibers have an average fiber diameter x less than about 6 μm; and the fiber diameter distribution of the second fibers has a standard deviation from x less than 3.5 μm. Claim 38 In paragraph 37, a nonwoven mat in which the standard deviation from x is less than 3.0 μm. Claim 39 In paragraph 37, a nonwoven mat in which the standard deviation from x is less than 2.5 μm. Claim 40 A nonwoven mat according to any one of paragraphs 37 to 39, wherein the second fiber has an average diameter of less than 5 μm. Claim 41 A nonwoven mat according to any one of paragraphs 37 to 39, wherein the second fiber has an average diameter of less than 4 μm. Claim 42 A nonwoven mat according to any one of paragraphs 37 to 39, wherein the second fiber has an average diameter of less than 3 μm. Claim 43 A nonwoven mat according to any one of paragraphs 37 to 42, wherein the second fiber has an average formed length of more than 50.8 mm (2 inches). Claim 44 A nonwoven mat according to any one of claims 37 to 42, wherein the second fiber has an average formed length in the range of about 76.2 mm (3 inches) to about 304.8 mm (12 inches). Claim 45 A nonwoven mat according to any one of paragraphs 37 to 44, wherein x is less than the median fiber diameter of the second fiber. Claim 46 A nonwoven mat according to any one of paragraphs 37 to 45, wherein 90% of the second fiber has a diameter ≤ 1.525x. Claim 47 A nonwoven mat in which, in any one of paragraphs 37 to 46, the first fiber is a glass fiber. Claim 48 A nonwoven mat in which, in any one of paragraphs 37 to 47, the second fiber is a glass fiber. Claim 49 A nonwoven mat, wherein in any one of paragraphs 37 to 48, the second fiber is a spin-forming fiber. Claim 50 A nonwoven mat according to any one of claims 37 to 49, wherein the nonwoven mat comprises at least 1 weight percent of a second fiber based on the weight of the nonwoven mat. Claim 51 A nonwoven mat according to any one of claims 37 to 49, wherein the nonwoven mat comprises at least 10 weight percent of a second fiber based on the weight of the nonwoven mat. Claim 52 A nonwoven mat according to any one of claims 37 to 49, wherein the nonwoven mat comprises at least 20 weight percent of a second fiber based on the weight of the nonwoven mat. Claim 53 A nonwoven mat according to any one of paragraphs 37 to 52, wherein the binder comprises polyvinyl alcohol. Claim 54 A nonwoven mat that, in any one of paragraphs 37 to 53, further comprises an inorganic filler. Claim 55 A nonwoven mat according to any one of claims 37 to 54, wherein the average fiber diameter of the first fiber is in the range of about 10 μm to about 11 μm; and the average fiber diameter of the second fiber is in the range of about 3 μm to about 4 μm. Claim 56 A nonwoven mat according to any one of paragraphs 37 to 55, wherein the second fiber does not contain any fibers with a diameter greater than 22 μm. Claim 57 A nonwoven mat according to any one of claims 37 to 55, wherein the second fiber does not contain any fibers with a diameter greater than 20 μm. Claim 58 A nonwoven mat according to any one of paragraphs 37 to 55, wherein the second fiber does not contain any fibers with a diameter greater than 16 μm. Claim 59 A nonwoven mat according to any one of paragraphs 37 to 55, wherein the second fiber does not contain any fibers with a diameter greater than 15 μm. Claim 60 A nonwoven mat according to any one of paragraphs 37 to 55, wherein the second fiber does not contain any fibers with a diameter greater than 14 μm. Claim 61 In any one of paragraphs 37 to 60, the nonwoven mat has a first surface and a second surface opposite to the first surface, and each surface is a nonwoven mat 1,000 m 2 A nonwoven mat containing approximately 100 or fewer flocs. Claim 62 In paragraph 61, each surface of the nonwoven mat is a nonwoven mat 1,000 m 2 Non-woven mat having approximately 50 or fewer flocks per unit. Claim 63 In paragraph 61, each surface of the nonwoven mat is a nonwoven mat 1,000 m 2 Non-woven mat having approximately 25 or fewer flocks per unit. Claim 64 In paragraph 61, each surface of the nonwoven mat is a nonwoven mat 1,000 m 2 Non-woven mat having approximately 15 or fewer flocks per unit. Claim 65 A nonwoven mat according to any one of claims 37 to 64, wherein the average fiber diameter of the first fiber is in the range of about 8 μm to about 13 μm. Claim 66 A nonwoven mat according to any one of claims 37 to 65, wherein the average fiber diameter of the second fiber is in the range of about 3 μm to about 3.5 μm. Claim 67 A nonwoven mat according to any one of claims 37 to 66, wherein the first fiber comprises about 10% w / w to about 50% w / w of the total weight of the first fiber and the second fiber; and the second fiber comprises about 50% w / w to about 90% w / w of the total weight of the first fiber and the second fiber. Claim 68 A nonwoven mat according to any one of claims 37 to 66, wherein the nonwoven mat comprises more first fibers than second fibers in weight percent based on the total weight of the first fibers and second fibers. Claim 69 A board comprising a surface material on at least one main surface thereof, wherein the surface material comprises a nonwoven mat according to any one of claims 37 to 68. Claim 70 A ceiling tile comprising a surface material on at least one main surface, wherein the surface material comprises a non-woven mat according to any one of claims 37 to 68. Claim 71 A method for manufacturing a nonwoven fibrous mat comprising: (i) dispersing a plurality of first fibers in a first aqueous solution to form a first slurry; (ii) dispersing a plurality of second fibers in a second aqueous solution to form a second slurry; (iii) mixing the first slurry, the second slurry, and a water-soluble or water-dispersible binder to form a third slurry; (iv) depositing the third slurry to form a wet-laid web composed of the first fibers, the second fibers, and the binder; and (v) a step of drying a wet-laid web to form a nonwoven fibrous mat, wherein the first fiber has an average fiber diameter in the range of about 6.5 μm to about 15 μm; the second fiber has an average fiber diameter x of less than 6.0 μm; the fiber diameter distribution of the second fiber has a standard deviation from x of less than 3.5 μm; and the nonwoven mat has a first surface and a second surface opposite to the first surface, and each surface is a nonwoven mat 1,000 m 2 A method having fewer than 100 flocs per day. Claim 72 In paragraph 71, the method wherein the binder is added to the first slurry. Claim 73 In paragraph 71, the method wherein the binder is added to the second slurry.

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