NON-WOVEN MAT

Abstract

The invention described herein relates to non-woven mats and to methods for making same. The mat is formed from fibres that comprise a first polymeric material. The mat comprises a flange-portion (3) that is of greater density than the remaining portion of the mat and that further comprises a second thermoplastic polymeric material having a melting-point temperature that is lower than the melting-point temperature of the first polymeric material. The mats can be used in the formation of plates used in rotating biological contactors (RBCs). Other examples of applications include the formation of air filters, demisters and floating treatment wetlands.

Claims

1. A non-woven mat formed from fibres that comprise a first polymeric material, the mat comprises a flange-portion that is of greater density than the remaining portion of the mat and that further comprises a second polymeric material, the second polymeric material is a thermoplastic and has a melting-point temperature that is lower than the melting-point temperature of the first polymeric material.

2. A non-woven mat as claimed in claim 1, wherein the second polymeric material is substantially absent from the remaining portion of the mat.

3. A non-woven mat as claimed in claim 1, wherein the flange portion has a volumetric solid fraction of more than 0.85.

4. A non-woven mat as claimed in claim 1, wherein the melting point temperature of the first polymeric material is 1 C., 2 C., 3 C., 4 C., 5 C., 10 C., 15 C. or 20 C., 30 C., 40 C. or more, greater than the melting-point temperature of the second polymeric material.

5. A non-woven mat as claimed in claim 1, wherein the flange portion comprises a matrix comprising the second polymeric material in which fibres of the first polymeric material are entrapped.

6. A non-woven mat as claimed in claim 1, wherein the flange portion comprises a matrix comprising the second polymeric material in which fibres of the first polymeric material are uniformly distributed and/or randomly distributed.

7. A non-woven mat as claimed in claim 1, wherein the flange-portion forms a raised surface extending out from the surface of the mat.

8. A non-woven mat as claimed in claim 1, wherein when the first polymeric material is HMPPE, the second polymeric material is LMPPE; or wherein when the first polymeric material is PP, the second polymeric material may be any of LMPPE, HMPPE, or combinations thereof; or wherein when the first polymeric material is POM, the second polymeric material may be any of LMPPE, HMPPE, or combinations thereof; or wherein when the first polymeric material is TPE, the second polymeric material may be any of LMPPE, HMPPE, PP, POM, or combinations thereof; or wherein when the first polymeric material is PBT, the second polymeric material may be any of LMPPE, HMPPE, PP, POM, TPE, or combinations thereof; or wherein when the first polymeric material is PA, the second polymeric material may be any of LMPPE, HMPPE, PP, POM, TPE, PBT, or combinations thereof.

9. A non-woven mat as claimed in claim 1, wherein the non-woven mat is spun-inline and melt-bonded.

10. A non-woven mat as claimed in claim 1, wherein the fibres comprising the first polymer have average diameters greater than 0.3 mm; and/or wherein the fibres comprising the first polymer have average lengths greater than 500 mm; and/or wherein the volumetric solid fraction in the remaining portion of the mat is greater than 0.04 and/or less than 0.85.

11. A non-woven mat as claimed in claim 1, wherein the flange portion is at the periphery of the mat; and/or wherein the flange portion is around the periphery of an aperture in the mat.

12. A non-woven mat as claimed in claim 1, wherein the flange portion is a rib running through the body of the mat.

13. A non-woven mat as claimed in claim 1, wherein the flange portion is a fixing fitment.

14. A non-woven mat as claimed in claim 1, preceding claims, for use as plates in a biological rotating contactor and/or for use in filters, demisters or floating treatment wetlands.

15. A method of forming a flange in a non-woven mat, wherein the method comprises the steps of: a. providing a non-woven mat formed from fibres that comprise a first polymeric material and from a second polymeric material; b. heating the first and second polymeric materials to a process temperature that is higher than the melting-point temperature of the second polymeric material and lower than the melting-point temperature of the first polymeric material, and; c. compressing a portion of the non-woven mat so that the portion of the non-woven mat forms a flange-portion.

Description

FIGURES

[0086] The present invention is described by way of example only and with reference to the following figures.

[0087] FIG. 1 is a diagram showing example combinations of first and second polymeric materials; some of these combinations are feasible for use with the invention described herein. LMPPE denotes a low melting-point polyethylene and HMPPE denotes a high melting point polyethylene within the normal melting point temperature range of polyethylene (PE) types, PP denotes polypropylene, POM denotes polyoxymethylene, TPE denotes thermoplastic polyester elastomer, PBT denotes polybutylene terephthalate and PA denotes polyamide (Nylon-66).

[0088] FIG. 2 compares the melting-point temperatures of the polymeric materials in the example combinations as shown in FIG. 1. All the first as well as the second polymeric materials, in the example combinations, are thermoplastics and none undergoes thermal degradation at a temperature less than its respective melting-point temperature. Each type of polymer material exhibits a range of melting-point temperatures, which relate to the variation in the polymeric structure of different manufactured versions of the material. Each temperature range given in FIG. 2 typifies the particular material but does not necessarily cover the full range. Inspection of the chart in FIG. 2 shows clear differences in the melting-point temperature ranges for the following combinations: PA-PBT, PBT-POM, TPE-PP, PP-HMPPE and HMPPE-LMPPE. For these particular combinations, a wide range of manufactured individual versions are available for the first and second polymeric materials. By comparison, the melting-point temperature ranges in the POM-PP combination are continuous. Thus, the availability of individual versions of the first and second polymeric materials for this particular combination is limited. The version of the PP must be drawn from near the bottom of its melting-point temperature range, and the version of the POM must be drawn from near the top of its melting-point temperature range.

[0089] The most cost-effective polymeric material is generally polyethylene. It has been found that LMPPE coincides generally, but not exclusively, with the established category of low-density polyethylene (LDPE). Similarly, HMPPE generally coincides with the established category of high-density polyethylene (HDPE). Density ranges of LDPE and HDPE are approximately 915 to 930 kg/m.sup.3 and 940 to 970 kg/m.sup.3, respectively. In the example of the spun-inline mat with flange portions, the difference between melting-point temperatures in the HMPPE-LMPPE combination is 19 C. The PBT-POM combination has the largest difference in melting-point temperatures of the first and second polymeric materials, and the combination POM-PP has the lowest difference.

[0090] FIG. 3 shows the features of an opened thermal compression mould (5 and 6) for making a flange portion in a non-woven mat (7). In this case, the flange portion is made using a preformed flange shape (8) made of the second polymeric material. Heating sources (9) are placed on both sides of the mould to concentrate heat on the flange shape. Alternatively, the flange shape may be heated from one side only. Closing the mould forces the second polymeric material from the flange shape into the space between the fibres of the compressed mat.

[0091] FIG. 4 shows the non-woven mat (7) in the enclosed mould with a finished flange portion. The flange portion (3), at the periphery of the mat, comprises the mat's fibres entrapped in a matrix of the second polymeric material. In this case, the surface of the flange portion is flush with the surface of the compressed mat.

[0092] FIG. 5 shows elevations of the plate sections for use in RBC units (1) described above (e.g. U.S. Pat. No. 4,165,281 (Niigata Engineering Company. Ltd.)). Each plate section contains six installation apertures (2). Flange portions are shown at the periphery (3) of the plate section and at the periphery (4) of the apertures.

[0093] FIG. 6 compares the values of Young's modulus of the new and existing mats, before and after a prolonged period of service within a RBC. The objective was to establish the mechanical stability of the mat over a prolonged period of use, subject to typical mechanical stresses and with frequent immersion in water.

[0094] FIG. 7 shows the results of tests performed to determine the ultimate tensile strength (UTS) of the existing and new mat, before and after a period in service within a rotating biological contractor (RBC). The objective was to verify that the new mat has a UTS which is sufficient for use within a RBC when formed into plate sections (see FIG. 5) and which is stable over a period of several months.

[0095] FIG. 8 shows Test Locations, TL1 to TL6, used for the stiffness tests, on the peripheral flanges of the new and existing plate sections. The objective was to establish the stiffness of the manufactured plate sections (comprising mat reinforced by formed flange portions).

[0096] FIG. 9 compares the deflections under load of the new and existing plate sections at two of the test locations (TL1 and TL4).

[0097] FIG. 10 compares values of a stiffness parameter at all test locations. The results indicate that new plate sections have lower deflections under load and are much stiffer than the existing plate sections.

DETAILED DESCRIPTION

[0098] Non-woven mats are found in a wide range of products including cushion fillings, clothing, personal hygiene aids, geotextile membranes, paper and card, insulating materials and filters of various types. Production of such a wide range of products requires non-woven mats with diverse properties and structures, determined by variables such as physical properties of fibres and their polymeric materials, method of fibre laying, bonding between fibres, method of finishing and mat thickness.

[0099] By way of example, the improved method of forming flange portions is applied to a spun-inline melt-bonded mat, which is constructed using a method similar to that described in the Asahi Kasei website. The example mat is manufactured directly from a melt of the first polymeric material, which is extruded through a die containing multiple holes. Hole diameter is 0.7 mm, and pitch spacing of the holes is 5 mm. The working face of the die, 80 mm wide by 2 m long, contains 5600 extrusion holes. The multitude of fibres, in the molten state, fall vertically under gravity onto water-cooled rollers which cause the fibres to spiral, above the surface of the water, and fuse at their contiguous surfaces. The bonded mat then falls into the cooling water and onto a submerged conveyor. This inline, continuous process produces long stretches of mats very cost-effectively. Using the improved method described herein, the second polymeric material is then used to form flange portions in the mat described above.

[0100] Consider a mat containing a flange portion. The fibres comprise a first polymeric material and the flange portion contains the compacted fibres embedded in a matrix of a second polymeric material, which is a thermoplastic. The method of making flange portions described herein is applicable to any first polymeric material provided the material is not significantly affected, physically or chemically, by the conditions of the thermal compression process used to make the flange portion.

[0101] The method of thermal compression, described herein, involves applying a process compression pressure to the flange portion which has been heated to the process temperature.

[0102] FIG. 3 is an exploded diagram showing, in part, the two halves (5) and (6) of a thermal compression mould used to make flange portions. It also shows the mat (7), the second polymeric material (8) and two heating elements (9). FIG. 4 is a diagram showing, in part, the fully enclosed mould containing the flange portion (3).

[0103] FIG. 4 shows the second polymeric material may be applied to the flange portion in the form of a preformed shape (8), which may be cut from plastic sheet of the required polymeric material and thickness or pre-moulded from the material. Preformed shapes are made to the same plan width as that of the flange portion. Preformed flange shapes are applied to the surface of the flange portion and, to hold them in place, may be glued, preferably using hot melt, to the mat's surface.

[0104] The second polymeric material may also be applied to the flange portion in the form of granules spread evenly over the surface of the mat's surface. Granules smaller than the pore size of the mat may fall into the flange portion of the mat, but this does not impair the production and strength of the finished flange portion.

[0105] Further, the second polymeric material may be applied to the flange portion of the mat as a hot melt through a lance, preferably driven robotically.

[0106] The mould shown in FIGS. 3 and 4 is heated from both sides, which maximises productivity.

[0107] The temperature of the heating elements (9) is closely controlled so that the second polymeric material is liquefied, whilst the fibres are not damaged and recover their initial strength after cooling. The conditions and duration of the thermal compression are controlled to obtain the desired effect in the flange portion whilst maximising productivity.

[0108] When using one-sided heating, the heating should preferably be applied to the side of the compacted mat not in contact with the second polymeric material, so the second polymeric material is heated through the compacted mat. This type of heating is called herein indirect heating. Such indirect heating improves the flow of melted second polymeric material into the compacted mat and minimises any lateral flow into the open mat outside the flange portion.

[0109] Application of the process compression pressure to the flange portion should preferably be delayed until the temperature of the second polymeric material has reached process temperature.

[0110] The second polymeric material practically fills the space between the fibres of the first polymeric material in the flange portion, which maximises the strength and stiffness of the portion. The F.sub.v value of the finished flanged portion is greater than 0.85. Experience indicates that the minimum thickness, Tm (mm), of preformed flange shapes needed to fill the space is related to the initial volumetric solid fraction, F.sub.v, and thickness, T (mm), of the mat, as follows:

[00002]$\begin{array}{cc}\mathrm{Tm}{\mathrm{TF}}_v& \left(\mathrm{Equation}2\right)\end{array}$

[0111] Similarly, the thickness, Tf, of such flange portions is given by:

[00003]$\begin{array}{cc}\mathrm{Tf}2{\mathrm{TF}}_v& \left(\mathrm{Equation}3\right)\end{array}$

[0112] Consider a mat with F.sub.v and T values of 0.06 and 50 mm respectively. Equation 2 indicates Tm has a value of approximately 3 mm, so flange shapes may be cut, in this case, from standard plastic sheet of this thickness. Equation 3 indicates Tf has a value of approximately 6 mm.

[0113] Flange portions, which protrude from the surface of the compressed mat, may be made using preformed flange shapes of increased thickness. To obtain the thickness of the preformed shape required, the thickness Tm is increased by the required height of the protruding part of the flange portion. Protruding flange portions are heated indirectly through the compressed mat so that the protruding part of preformed flange shape is unaffected by the thermal compression.

Characterisation of Tested Mats

[0114] By way of example, the invention is applied to the production of RBC plate sections with the shape and dimensions shown in FIG. 5. These plate sections, and samples of mat cut from the plate sections, were tested and the results discussed below with reference to FIGS. 6 and 7. The first and second polymeric materials consist of a thermoplastic polyester elastomer (TPE) and a low melting-point polyethylene (LMPPE), respectively. Based on their densities, the two polymers fall into the categories of TPE and LDPE; more specifically TPC-ET (thermoplastic copolyester elastomer) and MDPE Lumicene Supertough 22ST05.

[0115] The mat for the plate section was spun-inline from a melt of the TPE using a method similar to that described in the Asahi Kasei website. The mat is 50 mm thick and has a F.sub.v value of 0.057. The fibres are continuous and have an average diameter of 0.75 mm. The flange portion is 5.7 mm thick, made using 3 mm thick preformed shapes.

[0116] Process temperature and process compression pressure used to make the flange portion were 125 C. and 1.2 MPa, respectively. For comparison, the melting-point temperatures of the TPE and LDPE are 205 C. and 113 C., and their densities are 1190 kg/m.sup.3 and 921 kg/m.sup.3, respectively. The Vicat A50 softening temperature of the TPE is 180 C.

Testing of Mats and Plate Sections

[0117] RBC plate sections made using the method described herein are compared in term of strength and flexibility against purchased plate sections made using the method described in JP Patent Application No. 2007 301511 (A) and Korean Patent No. 10 1019069. To a good approximation, both types of plate sections have the dimensions and shape given in FIG. 5.

[0118] Purchased plate sections are called herein existing plate sections. Plate sections made using the invention herein and that are subject to tests described here are as described above under Characterisation of Tested Mats and are called new plate sections. Similarly, the mats, used to make the plate sections are called the existing mat (ie those purchased) and the new mat (ie as described above under characterisation of Tested Mats.

[0119] The drawing given in FIG. 5 shows the plate section (1), the six fixing apertures (2), the peripheral flange portions (4) around the fixing apertures, and the peripheral flange portion (3) around the plate section. The flange portions in the two types of plate sections vary in thickness. Flange portions in existing plate sections are approximately 4 mm thick, whereas portions in new plate sections are 5.7 mm thick, which is the thickness obtained by using the minimum thickness, Tm, of the second polymeric material.

[0120] Whereas the new mat is a spun-inline melt-bonded type, the existing mat is an air-laid adhesive-bonded type. Table 3 lists the main features of the main types of non-woven mats. The existing mat is of the type given in the 2.sup.nd column from the left of Table 3, and the new mat is of the type given in the right-hand column of Table 3.

[0121] Table 1 compares the physical and chemical properties of the new and existing plate sections. Compared to the existing mat, the new mat has a higher F.sub.v value (0.057 against 0.04) but a lower overall density (53 kg/m.sup.3 against 68 kg/m.sup.3), owing to the lower density of the fibre of the first polymeric material.

TABLE-US-00001 TABLE 1 Properties of mats and flange portions compared in tests Property Unit New sections Existing sections First polymer TPE (Hytrel Saran 5526 - Dupont) Second polymer LDPE (Lumicene Not applicable Supertough 22ST05) Fibre diameter (first polymer) mm 0.65 to 0.80 0.58 Density of first polymer kg/m.sup.3 1190 1700 Density of second polymer kg/m.sup.3 921 Not applicable Mat thickness mm 62 50 Mat density kg/m.sup.3 53 68 Volumetric solid fraction content of mat, fraction 0.057 (preferred) 0.04 F.sub.v Mat bonding Thermal Adhesive Bonding of flange portions Matrix entrapment Thermally moulded Thickness of flange portions mm 5.7 3.5-4.5 Void of flange portions fraction <0.05 0.4 to 0.5

[0122] Tests were performed on the new and existing mat and plate sections to establish the mechanical characteristics of the mat and the effectiveness of the flanged sections at providing a stiffening effect when the mat is formed into the plate sections.

[0123] Samples of existing and new mat were tested to establish the Young's modulus (YM) and Ultimate Tensile Strength (UTS). YM is a measure of dimensional stability, with higher numbers indicating a more dimensionally-stable material and low numbers indicating a more elastic material. UTS is a measure of the resistance of the material to failure under tension, with higher numbers indicating a stronger material.

[0124] The mat samples were cut from manufactured plate sections. These tests were carried out first on samples from unused plate sections and then on plate sections which had been used in a rotating biological contactor for at least 30 weeks. The objective was to compare the values of YM and UTS of the two mats and to determine the effect of a long period of use.

[0125] Samples of whole plate sections made using the existing and new methods were tested to compare the resistance of the existing and new plate sections to deflection under load. A stiffness parameter is defined for the comparison.

Comparison of Mechanical Strength and Stability

[0126] As indicated in Table 2, six new plate sections and six existing plate sections were tested. The plate sections were installed in a full-scale operational RBC for 30 weeks.

[0127] Four samples cut from the new plate sections and four samples from the existing plate sections were used for measuring the Young's Modulus (YM) before and after a prolonged period of use in a full-scale RBC. Further tension was then applied to measure the ultimate tensile strength (UTS).

[0128] For these tests, rectangular test samples were cut from the plate sections. Each sample was 100 mm wide by 300 mm long, and one of the 100 mm edges consisted of part of the flange portion around the plate's periphery. The other 100 mm edge was filled with epoxy resin to give a solid strip 25 mm wide and 50 mm thick, allowing it to be clamped securely for testing without distorting the fibres.

[0129] The new mat is formed by a process involving spun-inline linear extrusion and melt-bonding and therefore has different tensile characteristics along the length of the mat, compared to across the width of the mat. Plate sections were cut as described above to create two samples in which the mat was aligned length-wise and two samples in which the mat was aligned width-wise, for separate analysis. The existing mat is formed in a non-directional process (air-laid with adhesive bonding) and its tensile characteristics are similar in all directions.

TABLE-US-00002 TABLE 2 Samples of plate sections used to determine mechanical stability of the mat Extension at Time in Breaking breaking Plate Sample Orientation operation load load UTS YM sections ref. of mat (weeks) (N) (%) (kN/m.sup.2) (kN/m.sup.2) New A06L Length 0 >168 >100% >27.2 57.2 A12L Length 30 >175 >100% >28.4 57.0 A06W Width 0 161 26.9% 25.5 108 A12W Width 30 164 29.2% 26.0 102 Existing B0 N/A 0 366 58.2 73.1 126 B1 N/A 56 293 56 58.5 105 B2 N/A 56 293 49.7 58.6 118 B3 N/A 56 295 79.8 59.0 74

[0130] FIG. 6, comparing the Youngs Modulus, shows that the new plate section has a similar stiffness to the existing mat in the width-wise direction and a far lower YM (i.e. greater elasticity) in the lengthwise direction, owing to the way in which the fibres forming the mat are laid in a longitudinal direction, but curled, during manufacture of the mat. Importantly, FIG. 6 demonstrates that the Youngs Modulus of the new plate section changed little during 30 weeks' use in a RBC, whereas the YM of the existing plate section reduced over a longer period, indicating a reduction in material stiffness over time.

[0131] FIG. 7 shows that the new plate section has a lower ultimate tensile strength than the existing plate section, but that the strength of the new plate section remains almost constant after prolonged use, whereas the strength of the existing plate section was significantly reduced after use in a RBC. The loads applied during the measurement of UTS were far in excess of those likely to occur within a RBC or similar application of the technology so both materials are considered to have adequate UTS.

[0132] All samples from both the new and existing mats failed (at their ultimate respective loads) within the mat rather than at the link between the flange portion and the remaining portion of the mat, indicating that forming flange portions, using the invention described herein or the method described in Japanese Patent Application No.: 2007 301511, produces portions securely attached to the mat.

Comparison of Stiffness

[0133] The other group of tests was performed to compare the deflection and stiffness of new and existing plate sections under load. The tests were performed on whole plate sections.

[0134] The test rig comprised a stiff frame containing six bolt-fixing points for securely holding individual plate sections horizontally. Six bolts, with washers of the same outer diameter (85 mm) as the flange portions around the holes, pass through the six fixing holes to secure individual plate sections to the frame.

[0135] The new and existing plate sections were immersed in water for 25 days to simulate the effects of any short-term hydrolysis on the strength of the plate sections.

[0136] For the tests, six test locations (TLs) were identified at different positions around the outer peripheral flange portion, as indicated in FIG. 8. For example, TL4 is on the outer circumference of the peripheral flange portion, and TL1 is diametrically opposite, on the inner circumference.

[0137] The stiffness of each section was tested by applying an upward vertical force at each test location, through a chain and catch. As indicated in FIG. 8, the catch (10), made from 3 mm-diameter angled stainless steel rod, passes under the flange portion; its design ensures the applied vertical force passes through the centre of the flange portion. The catch did not penetrate or damage the peripheral flange portions of the new or existing plate sections in any of the tests.

[0138] Using a conventional tensile-testing machine, the applied upward vertical force was increased from zero until either the applied force reached 100 N or the measured vertical deflection reached a maximum of 50 mm. Since the plate sections are 50 mm thick such a deflection is substantial and would not normally be experienced in practice. The range of applied forces used in the tests was wider than the range experienced by plate sections under normal operating conditions within a RBC or similar device.

[0139] In the tests, the applied vertical force is countered by the resisting mechanical stresses in the flange portion and adjoining mat.

[0140] Test results have been compared in terms of deflection and stiffness for which a stiffness parameter, S (N/mm), has been derived, as follows:

[00004]$\begin{array}{cc}S=F/D& \left(\mathrm{Equation}4\right)\end{array}$

where F (N) is the applied force and D (mm) is the deflection. Stiffness values relate to either the maximum deflection of 50 mm or the maximum force of 100 N, depending on which condition occurred first.

[0141] FIG. 9 shows the relationships between deflection and applied force at the two test locations, TL1 and TL4, for both the new and existing plate sections. Under a load of 20 N, the deflection at TL1 was approximately 50 mm for the existing plate section but only 25 mm for the new plate section. Similarly, at TL 4, the deflections were approximately 14 mm and 7 mm respectively. Thus, the results indicate that new plate sections resists deflection under load much better than existing plate sections.

[0142] Loads as high as 100 N are not practical in normal operation within a RBC. However, under such a high load, the existing and new plate sections deflections at TL4 were 48 mm and 37 mm respectively, confirming that the new plate section has lower deflections under a range of loads.

[0143] FIG. 10 compares values of the stiffness parameter, S (N/mm), determined from Equation 4 for the new and existing plate sections at all test locations. The results indicate that the new plate is stiffer than the existing plate at all locations. Further, the value of stiffness parameter was highest at TL4 and lowest at TL1. With reference to FIG. 8 showing the positions of the test locations and fixing apertures, this result suggests that stiffness is inversely related to the distances between a test location and the fixing apertures.

[0144] New plate sections have substantially higher stiffness to counteract deflection from the plane of the plate section, yet they also have greater elasticity within the mat to accommodate a small amount of movement within the plane of the mesh. These characteristics are advantageous in applications such as within a RBC. Importantly, the YM and UTS of the new mat remained constant after prolonged use within a RBC which suggests that the mechanical characteristics will remain consistent over the lifetime of the plate section.

TABLE-US-00003 TABLE 3 The following table lists the main features of different types of non-woven mats. Fibre type Staple Spun-inline from melt Fibre length (mm) 20 to 200 Continuous Fibre chemical Natural fibres and Thermoplastic properties thermoplastics Fibre diameter 10-500 10-50 20-50 <20 100-1000 (m) Fibre laying Air-laying or Filtering of Air jetting of spun fibres Water mechanisms carding of wet fibres immersion of dry fibres from slurry melted fibres Mat bonding* G, F, H, N or C F, G or N A or A + F M S Mat features Common High density Strong and Good loft Low fibre mats e.g. mats, hard wearing e.g. content with clothing e.g. paper cushions good rigidity Notes: *Methods of mat bonding include: A = air entanglement, C = pressure compaction, G = glued, F = fused by heating, H = hydro-entanglement, M = melt entanglement and fusing, N = needle punched, S = stitched