Patent Application
20050164582
1) Field of the Invention
The present invention concerns a high binder flame-retardant (FR) nonwoven fabric that can be employed in many applications, particularly in household goods, such as stuffing for comforters, pillows, or furniture; backing for curtains and rugs; and especially for mattress fabrics. The nonwoven fabric comprises from about 6 to about 40 weight percent of low melt binder (bicomponent fiber or low-melting fiber) and at least one of FR rayon fiber, FR acrylic fiber, FR melamine fiber, FR polyester fiber, and FR coated fiber; and optionally non-bonding, non-FR, synthetic fiber and/or natural fiber. Nonwoven fabric prepared from these components, possessing a batt weight of greater than about 4 oz./sq. yd. is capable of passing stringent flame-resistant tests.
2) Prior Art
Flame-retardant (FR) or flame-resistant materials are well known to those skilled in the textile art. Such materials can be woven or nonwoven, knitted, or laminates with other materials such that they pass various textile FR or flame-resistant tests, such as California TB 117 & TB 133 for upholstery; NFPA 701 for curtains and drapes; and California TB 129 dated October, 1992, concerning flammability test procedures for mattresses for use in public buildings. This last test is the most stringent test for mattresses known in the world. Another test for residential mattresses is California TB603. The criterion for compliance for TB 603 is as follows:
Various FR fibers are well known to those skilled in the textile art. FR fibers based on polyester, rayon, melamine, nylon, acrylic, and polyolefin fibers such as polyethylene or polypropylene fibers, are known and commercially available.
U.S. Pat. No. 6,214,058 issued to Kent et al. on Apr. 10, 2001, describes fabrics made from melamine fibers that may or may not be flame-resistant fabrics. This reference describes a process for dyeing melamine fabrics including blends of melamine and natural fibers (such as wool or cotton) or other synthetic fibers such as rayon or polyester. As a passing comment, it mentions that the melamine fiber may be FR.
U.S. Pat. No. 6,297,178 issued to Berbner et al. on Oct. 2, 2001, discloses flameproof fabrics based on FR melamine fibers and FR rayon fibers. The melamine and rayon fibers are made FR by coating the fibers with aluminum.
U.S. Pat. No. 4,863,797 (Sep. 5, 1989); U.S. Pat. No. 5,208,105 (May 4, 1993); U.S. Pat. No. 5,348,796 (Sep. 20, 1994); U.S. Pat. No. 5,503,915 (Apr. 2, 1996); U.S. Pat. No. 5,513,916 (Apr. 2, 1996); and U.S. Pat. No. 5,506,042 (Apr. 9, 1996) issued to Ichibori et al. disclose an FR composite fiber comprising: (A) 85 to 15 parts by weight of a fiber comprising a polymer containing 17 to 86% by weight of a halogen, and 6 to 50% by weight of an Sb compound based on the polymer, and (B) 15 to 85 parts by weight of at least one fiber selected from the group consisting of natural fibers and chemical fibers, the total amount of the fibers (A) and (B) being 100 parts by weight.
PCT application WO 03/023108 filed Sep. 11, 2002 in the name of Mater and Handermann discloses a highloft FR material composed of FR rayon or FR melamine that are inherently FR. Additionally the application also discloses and requires the use of modacrylic fibers. These materials have no coating thereon.
In spite of the above-mentioned patents and numerous other nonwoven FR fabrics, there is still a need in the industry to create economical nonwoven FR articles that pass the stringent guidelines for the California TB 129 testing as well as other tests for upholstery and curtains and drapes. Moreover, there is a need in the industry to produce such a nonwoven article from materials that are relatively inexpensive and that have light batt weights.
Generally, the California TB 129 test for mattresses states that the mattress must char, but not burn through, for a minimum of three minutes based on certain conditions such as the position of the flame, the temperature of the flame, the source of fuel being used, etc. Furthermore, after one hour (57 minutes after the flame source has been extinguished) of burning the test is terminated and certain conditions must be met, as more fully set forth herein.
For the California TB 603, the test for mattresses states that two burners are used to initiate the test. One on the panel, flame duration of 70 seconds, and one on the border with a flame duration of 50 seconds. Both are lit simultaneously. Then 10 minutes after burner ignition the mattress must emit less than 25 MJ of total heat release. Also 30 minutes after burner ignition The mattress must emit less than 200 kW of heat release rate.
The present invention relates to nonwoven fabric which is capable of passing the California TB 129 test when the nonwoven fabric is employed in a mattress, as well as other tests employed for other household goods like draperies.
The nonwoven fabric/article of the present invention may be produced from a combination of FR synthetic fibers and/or from all natural fibers. In each case, the nonwoven fabric/article is bonded together by means of a low melt binder. The low melt binder may be bicomponent fiber or low-melting fiber. Additionally, the nonwoven article has at least one of FR rayon fibers, FR acrylic fibers, FR melamine fibers, FR polyester fibers, and FR coated fibers.
In the broadest sense, the present invention relates to a nonwoven article produced from about 6 to about 40 weight percent of low melt binder; at least one of FR rayon fiber, FR acrylic fiber, FR melamine fiber, FR polyester fiber, and FR coated fiber; and optionally non-binding, non-FR, synthetic and/or natural fibers.
In the broadest sense, the present invention also relates to a nonwoven article produced from a low melt binder, at least two FR fibers of the group of FR rayon, FR acrylic, FR polyester, and FR melamine, and optionally a non-binding synthetic fiber.
In the broadest sense, the present invention further relates to a nonwoven article produced from about 6 to about 40 weight percent of low melt binder, at least two FR materials selected from the group of FR rayon fibers, FR acrylic fibers, FR melamine fibers, FR polyester fibers, and FR coated fibers; and a non-binding synthetic or natural fiber.
In the broadest sense, the present invention still further relates to a nonwoven article produced from FR coated fibers, and about 6 to about 40 weight percent of a low melt binder.
The FIGURE is a graph of heat transmittance temperature in degrees Fahrenheit versus weight percent low melt binder for simple rayon/low melt binder nonwoven constructions.
The nonwoven article of the present invention is produced from materials generally known to those skilled in the textile art, however, before the present invention those materials have not been assembled into a nonwoven article like that of the present invention.
FR fibers are grouped into those that are inherently flame resistant, and those that are coated with an FR coating. Inherent FR fibers are those that have FR features by the end of manufacturing the resin (after the resin has initially solidified). FR coated fibers are those that apply the coating after the resin has initially solidified, or during the fiber making process, or after the fiber making process. Suitable FR fibers are those that can pass the various tests set forth below, and may be either the inherent type or those that are FR coated. FR fibers having too little flame resistance are not suitable for the present invention.
Inherent FR fibers employed in the nonwoven article of the present invention are FR rayon, FR melamine, FR polyester, and FR acrylic. More specifically, suitable FR rayon is sold under the registered trademark “Visil” by Sateri Oy and distributed by Ventex Incorporated. Visil is permanently fire resistant (“inherent”) because of the high silica content incorporated into the fiber during the manufacturing process of the resin. The silica forms an insulating barrier to the source of heat.
Suitable FR melamine fibers are well known in the textile art and can be purchased, for example, under the trade name “BASOFIL” by McKinnon-Land-Moran LLC. Like the FR rayon, the inherent FR melamine fibers do not melt or shrink away from a flame, but form a char that helps control the burn and shield the materials surrounded by fabric.
Suitable inherent FR acrylic fiber is well known to those skilled in the textile art and sold under the trade name “Modacrylic” distributed by Mitsui Textile Corporation and another suitable fiber may also be sold under the trade name “CEF Plus” by Solutia Inc.
Suitable inherent FR polyester, such as polyethylene terephthalate (PET) with phosphalane (organo phosphorus compound) such as that sold under the trademark Trevira CS® fiber, or Avora® Plus by Invista are known.
The FR coating employed is a type that has no binding characteristics. It is simply a coating which has an FR component therein, such as phosphorus, a phosphorus compound, red phosphorus, esters of phosphorus, or phosphorus complexes. The FR coating may be based on any material provided that it is compatible with the other components mentioned herein for the nonwoven batt. Typically, the FR coating resin is clear or translucent latex (where color is important, or any color and not translucent where color is unimportant) and is applied by spraying on the fiber. A suitable commercially available FR coating resin is known by the trade name “GUARDEX FR” made by GLO-TEX Chemicals in Spartanburg, S.C. There are several different GUARDEX FR resins and those skilled in the textile art can pick and choose among them to find that which is most compatible, taking into account such things as cost, appearance, smell, and the effect it may have on the other fibers in the nonwoven batt (does it make the other fibers rough, or have a soft hand, or discolor the other fibers). The FR coating resin may be applied to the nonwoven batt in a range from about 6 to about 25 weight percent of the nonwoven batt. It is also within the scope of the invention to apply the FR coating to just a portion of the fibers before such fibers are employed in the nonwoven batt. For example, the FR coating could be applied to the natural fibers, before they are dry laid/air laid onto a conveyor belt. Nevertheless, when considering the nonwoven batt as a whole, the amount of the FR coating remains within the range of 6 to 25 weight percent of the nonwoven batt. More typically the Fr coating is applied in a range from about 10 to about 18% by weight of the fibers to which it is applied.
The GUARDEX FR products are generally cured at about 300 degrees Fahrenheit, or preferably lower to minimize yellowing. Although this product must be cured, it has no significant binding effect on the other fibers in the nonwoven batt. It is merely cured to the fibers themselves so that it provides an FR characteristic to the fibers in addition to any FR characteristics or lack thereof of the fibers that are in the nonwoven batt.
While the above FR product (GUARDEX) is a liquid product applied as a spray, other FR resin in solid form may be applied as a hot melt product to the fibers, or as a solid powder which is then melted into the fibers.
The FR fibers come in different deniers from approximately 1.5 to about 10 dpf (denier per filament).
The low melt binder may be either a bicomponent fiber, for example, or a low melt polymer fiber. The low melt binder is generally employed in a range of from about 5 to about 50 weight percent of the nonwoven batt. The bicomponent fiber generally contains a low melt portion and a high melt portion. Consequently, the bicomponent fiber may be either the side-by-side type wherein the low melt component is adjacent to high melt component, or the sheath-core type wherein the high melt component is the core and the low melt component forms the sheath. Such bicomponent fibers are well known to those skilled in the textile art and may be based upon polyolefin/polyester, copolyester/polyester, polyester/polyester, polyolefin/polyolefin, wherein the naming convention is the low melt component followed by the high melt component. In those types wherein it is polyester/polyester, or polyolefin/polyolefin, the high melt component has at least 5 and preferably 8 degrees Fahrenheit higher melt temperature than the low melt temperature. More specifically, for example, a polyolefin/polyolefin could be polyethylene/polypropylene. Suitable bicomponent fibers are preferable a 50:50 low melt portion to high melt portion. But the present invention also contemplates a broader range of 20:80 to 80:20 for the bicomponent fiber.
Where the low melt binder is a low melt polymer fiber, those fibers mentioned above with respect to the low melt component of the bicomponent fiber are also suitable low melt polymer fibers. In other words, the low melt polymer fiber may be copolyester, or polyolefin, such as polyethylene. Lastly, the low melt binder may also be latex sprayed onto the nonwoven batt. In this situation, the latex employed has a low melt temperature so that once the latex is sprayed on to the nonwoven fiber batt, it can be cured by means of heat (subjecting the nonwoven batt to an oven for a short period of time sufficient to cure the latex). Such low melt binders are well known to those skilled in the textile art.
It is within the scope of the present invention to provide a low melt binder in the form of latex. Such products are well known and commercially available. It is also known to make an FR resin in the form of latex. Those skilled in the textile art recognize that it may be desirable to combine low melt binder latex with FR resin latex and apply such a product to the nonwoven batt by spraying.
Suitable non-FR synthetic fibers can be polyester such as polyethylene terephthalate (PET) or a copolyester, rayon, nylon, polyolefin such as polyethylene fibers, acrylic, melamine, and combinations of these. Other synthetic fibers not mentioned may also be employed. When non-FR synthetic fibers are employed, they give the batt certain characteristics like loft, resilience (springiness), tensile strength, and thermal retention, useful for household goods. Preferred are PET and rayon fibers.
Natural fibers may also be employed in the nonwoven batt of the present invention. Natural fibers such as flax, kenaf, hemp, cotton, and wool may be employed, depending on the properties desired. Preferred are flax and kenaf.
Because the synthetic fibers and natural fibers are non-binding and are not flame resistant, such fibers can be used to dial-in desired characteristics and cost. As such it is also within the scope of the present invention to employ a mixture of synthetic and natural fibers.
Currently, there are no regulations in effect for mattresses for home (residential) use. However, California is considering drafting such regulations and many industry experts say that such proposed regulations will mirror California TB 129. The strictest flame-resistant test for mattresses is the state of California, Department of Consumer Affairs, Bureau of Home Furnishings and Thermal Insulation, Technical Bulletin 129. The purpose of this test is to set a standard for the behavior of mattresses used in public occupancy such as hotels, motels, dormitories, prisons, etc. Specifically, this test measures the mattress when it is subjected to a specific flaming ignition source under well-ventilated conditions. Under such conditions, it should char but not support flame for at least 3 minutes. The California TB 129 test specifies a fabric wrapped around foam with a horizontal flame at 1800 degrees Fahrenheit for 3 minutes. There can be no drips, and the fabric must contain the foam although the foam may be melted or partially melted. The fabric cannot let the flame reach and ignite the foam.
The nonwoven batt of the present invention may be constructed as follows. The various combinations of fibers that can be employed in the present invention may be weighed and then dry laid/air laid onto a moving conveyor belt, for example. The size or thickness of a nonwoven batt is generally measured in terms of ounces per square yard. The speed of the conveyor belt, for example, can determine or provide the desired batt weight. If a thick batt is required, then the conveyor belt moves slower than for a thin batt. The weight percent of the total fibers in the batt is 100 percent. This does not include the weight of the FR resin since it is not in fiber form. It does, however, include the bicomponent fibers.
Suitable nonwoven fabrics of the present invention have a batt weight greater than about 4 oz./sq. yd. Preferably the batt weight ranges from 4 oz./sq. yd. to 20 oz./sq. yd., with the most preferred range being 6 oz./sq. yd. to 9 oz./sq. yd. Using a batt weight greater than about 20 oz./sq. yd. offers no significant improvement in performance and is more costly. If desired, any rearrangement of the fibers such as by carding occurs next. Then the conveyor belt moves to an area where any spray-on material is added to the nonwoven batt, for example, the FR coating sprayed onto the nonwoven batt as a latex while the batt is still positioned on the conveyor belt. If the conveyor belt is foraminous, the excessive latex FR resin drips through the belt and may be collected for reuse later. Once all the sprayed-on materials have been applied, if any, the conveyer belt can then move the nonwoven dry laid batt to an oven for melting and curing the low melt component of the bicomponent fiber or the low melt polymer fiber. The residence time in the oven depends on the fibers employed and is easily determinable by one skilled in the textile art. Thereafter, the nonwoven batt is cooled so that any low melt binder material re-solidifies thus locking the fibers employed into a solid batt. Thereafter, the batt may be cut to any size desired to serve as mattress fabric or other purposes such as stuffing for comforters, pillows, and furniture.
General Procedures
Various fiber components, some FR fibers and some synthetic fibers (primarily employed for increasing physical properties of the nonwoven batt), are set forth in the various examples having a range of dpf between 1.5 and 10, as mentioned previously. Also, the weight of the fiber batt as well as the burn test results according to California TB 129, measured in seconds, are set forth in the examples.
More specifically, for Example 3, the specimen consisted of a twin-size, innerspring mattress and foundation set. The specimen was covered with a white/off-white-colored ticking material. The construction of the mattress is well described in California TB 129.
The test specimen, after conditioning to 73 degrees and 50 percent relative humidity was placed on a steel frame on a load cell platform along the far side of the test room. The specified propane burner was placed centrally and parallel to the bottom horizontal surface of the mattress 1 inch from the vertical side panel of the mattress. The computer data acquisition system was started, then the burner was ignited and allowed to burn for 180 seconds. The test was continued until either all combustion ceased, or one hour passed.
The specimen does not meet the test requirements if any of the following criteria are exceeded:
For Example 5, a pair of twin mattresses was tested under California 603 for residential use. The criterion for compliance for TB 603 is as follows:
Heat transmittance value is indicator of how much heat is transferred from one side of the nonwoven batt to the other, opposite side, for given period of time and under certain heating conditions. The value, expressed as a temperature, is the temperature of the side of the nonwoven farthest from the flame. The best result is the lower value result, indicating the nonwoven is a great insulator. Specifically, the barrier specimen is in a horizontal fixed position. A burner is located beneath the specimen. The distance from the top of the burner to the specimen is 49 mm. The propane flow rate is controlled to 1.25 standard cubic feet per hour. An infrared temperature gun, with an emissivity of 0.95, is used to measure the temperature on the opposite side of the specimen. The temperature is recorded every 10 seconds for a duration of 90 seconds. The maximum temperature recorded between 40 seconds and 90 seconds is given as the test result.
Various combinations of FR fibers with other synthetic and/or natural fibers such as rayon, PET, flax, and kenaf were produced. The various fibers were dry laid onto a moving conveyor belt as is known in the textile art. For Samples 1-6 and 11, where an FR resin was employed, it was sprayed on to the nonwoven fiber batt. The nonwoven fiber batt was transported via the conveyor belt to an oven such that the low melt component melts. Then the fibers were transported to a cooling area where the low melt component of the low melt binder re-solidified thus locking the various fibers into a unitary structure as a batt. These various nonwoven batts, at various weights, were then subjected to a burn time test similar to the California TB 129 test. In the test, the nonwoven fabric was wrapped once around the foam. A flame was applied directly to the nonwoven fabric for at least 300 seconds and the structural integrity was noted. All of the test samples maintained their structural integrity for at least the time indicated, and the flame did not reach the foam. The burn time is listed in seconds. The batt weight is listed in ounces per square yard.
In all samples where FR resin was employed (Samples 1-6 and 11), GUARDEX FR resin was used. The FR resin, because it is sprayed on, is based on the total weight of the fibers that are employed to make up the nonwoven batt. In all samples, a bicomponent fiber comprising a low melt sheath component of copolyester and a high melt core component of PET was employed. In Samples 2, 4, and 9 the FR acrylic employed was 7 dpf (denier per filament). In Sample 7 the dpf of the FR acrylic was 5, and in Samples 3, 5, and 10 the dpf was 2. The dpf of the FR rayon in Samples 4 and 9 was 3.5. In Sample 8 it was 5 dpf, and in Samples 5 and 10 it was 8 dpf. The nonwoven batt construction and results are set forth below in Table 1.
*Weight % based on weight of all other components.
**The burn time was terminated because it had more than passed the test. In all other instances the burn time test was permitted to go to completion (i.e. where the flame burned through the nonwoven material such that it could no longer contain the liquefied foam.).
***Weight % based on the weight of natural fibers only.
Sammple 2 was a repeat of Samples 1, 5, 6, and 8-10 and their corresponding burn time tests, except that in Samples 1 and 5 the amount of bicomponent employed was 20 weight percent, while the amount of PET employed was 5 weight percent less. In each instance, the burn time in seconds was stopped at 600 seconds. 600 seconds is more than 3 times longer than what is required by California TB 129. The results are set forth in Table 2 below.
While this result is consistent for Samples 1 and 6, the retest of Sample 8 gave a slightly stronger result.
A nonwoven batt similar to Sample 5 was made, except that 20 weight percent FR resin was sprayed onto the batt (instead of 14 weight percent, as in Sample 5). The batt weight was 5.85 oz./sq. yd. (instead of 8 oz./sq. yd., as in Sample 5). A twin size mattress was constructed as described in the General Procedures and more specifically in California TB 129. This mattress was subjected to the full Flammability Test Procedure for Mattresses for Use in Public Buildings specified in the General Procedures and more specifically in California TB 129. The test results are reported below.
The ambient temperature was 75 degrees Fahrenheit with a relative humidity of 50 percent. After the test, the specimen was removed from the test room and was damaged in the following manner:
The results of the test were as follows:
Peak Rate of Heat Release = 40.60 KW
Total Heat Release = 8.60 MJ
Weight Loss in First 10 Minutes = 0.5 lbs.
A weight loss of 3 lbs. or more in the first 10 minutes is a test failure. For this Example, the result of 0.5 lbs. is excellent. A test failure also occurs if the maximum rate of heat released exceeds 100 KW. For this Example, the result of 40.60 KW is excellent. A test failure occurs if the total heat release is 25 MJ or more in the first 10 minutes. For this Example the result was 8.60 MJ. This was excellent.
In this example, the nonwoven batt includes either 30 or 40 weight percent low melt binder (bicomponent fiber or low-melting fiber) and 60 or 70 weight percent FR coated rayon. The FR rayon was coated with 15 weight percent add-on FR coating resin from Glotex-Glotard FFR. The batt weight was 9 oz./sq. yd. in both cases. The 40/60 batt had a heat transmittance value of 560° Fahrenheit as measured by an infrared temperature measurement device. The 30/70 batt had a heat transmittance value of about 520° Fahrenheit.
Generally for simple nonwoven batts constructed from low melt binder and FR coated rayon, there appears to be a “sweet spot” in terms of performance between 15% and 25% low melt binder, as illustrated in the FIGURE. Although there is a performance deterioration after about 30% low melt binder, such simple construction nonwovens are capable of passing the above identified tests. Therefore it offers a low cost solution for manufacturing FR mattresses, for example.
Two twin size mattresses were constructed and tested under TB 603 testing conditions. The construction of the barrier and the results from the test are set forth below.
Mattress Barrier Blends #1:
Mattress Barrier Blends #2:
e. Border—70% post treated rayon and 30% low melt
f. Construction—Mattresses were two-sided, baseline-3, tight top produced by Restonic Mattress Corporation.
Thus, it is apparent that there has been provided, in accordance with the present invention, a nonwoven fabric that fully satisfies the objects, aims, and advantages set forth above. While the present invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the textile art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and broad scope of the present invention.
This is a continuation-in-part of U.S. patent application Ser. No. 10/298,990, filed Nov. 18, 2002, and entitled “FLAME-RETARDANT NONWOVENS.”
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10298990 | Nov 2002 | US |
| Child | 11037522 | Jan 2005 | US |
