Patent Application
20080292739
The present invention relates generally to preforms, and more particularly, to highly compacted glass fiber preforms that are produced directly from a glass fiber product formed of texturized or non-texturized continuous glass fibers coated with a thermoplastic sizing composition.
Acoustical sound insulators are used in a variety of settings where it is desired to reduce noise emissions by dissipating or absorbing sound. For example, it is known in the art to use a sound absorbing material in exhaust mufflers for internal combustion engines to dampen or attenuate sound made by the engine exhaust gases as they pass from the engine through the exhaust system and into the atmosphere. Typically, continuous glass fiber strands are positioned internally in a muffler as the sound absorbing material. Continuous glass fibers are preferred over other fibers, such as chopped glass fibers, because the length of the continuous fibers decreases the possibility that free fibers may dislodge from the muffler and exit into the atmosphere.
Continuous glass fiber strands may be positioned in a muffler by a variety of methods known in the art. For example, continuous glass fiber strands may be inserted directly into a muffler shell, such as is disclosed in U.S. Pat. No. 4,569,471 to Ingemansson et al. In particular, Ingemansson et al. disclose a process and apparatus for filling muffler shells by feeding continuous multifilament glass fiber strands through a nozzle and into a muffler outer shell. Compressed air is used expand the fiber strands into a wool-like material inside the shell.
Alternatively, fibrous filed bags may be utilized to fill the inner cavities of a muffler. U.S. Pat. No. 6,607,052 to Brandt et al. discloses a process for filling a muffler shell with continuous glass fiber strands in which a bag is filled with continuous glass fibers and inserted into a muffler cavity. The bag has a first side with one or more first perforations defining a first side total open area and a second side with either no perforations or one or more second perforations defining a second side total open area. The first side total open area is greater than the second side total open area. The bag is filled with a fibrous material (e.g., continuous glass fiber strands) and positioned adjacent to an internal structure located within a first muffler shell part. A partial vacuum is applied to draw the filled bag towards the internal structure. A second muffler shell part is then placed adjacent to the first muffler shell part such that the first and second muffler shell parts define an internal cavity containing the internal structure and the fibrous material-filled bag.
In addition to filling a muffler shell with continuous glass fiber strands, it is also known in the art to form preforms of continuous glass fiber strands which are adapted to be inserted into a muffler shell. U.S. Pat. No. 5,766,541 and EP 0 941 441 to Knutsson et al. discloses a preform of continuous glass fiber strands made by feeding continuous glass fiber strands into a perforated mold to form a continuous wool product in the mold, feeding a binder into the mold, compressing the mold to compact the wool product to a desired density, heating the mold to cure the binder, and removing the preform from the mold. The preform may then be inserted into a muffler cavity.
In U.S. Patent Publication No. 2001/0011780 A1 and EP 0 692 616 to Knutsson, continuous glass fiber strands and a powder binder are blown into a cavity formed of a perforated screen having the shape of the muffler to be filled. Hot air is then passed through the perforated screen to melt the binder and bond the fibers together. Next, cool air is circulated through the screen to cool the preform so that it can be removed from the screen and inserted into a muffler.
In many of the methods in existence for forming muffler preforms, a binder is applied to the fibers prior to filling a muffler mold with the fibers. Generally, the binder is sprayed onto the glass fibers during the texturization of the fibers to form a wool-like material. The binder conventionally used in muffler preforms is a thermosetting, phenolic-based resin. The phenolic-based resin is in a powder form and is sprayed onto the fibers with water as a slurry. After curing, thermosetting binders generally form crosslinked products through irreversible cross-linking reactions. Thus, once the binder in contact with the fibers is cured, such as in an oven, the cured binder holds or retains the fibers in the shape of the preform until the preform is installed into a muffler shell. After the preform is installed in the muffler shell, the binder is no longer needed, and is typically burned off by running the vehicle for a period of time sufficient to remove at least a substantial portion of the binder from the preform.
Phenolic-based binders such as are used in continuous glass fiber strand preforms for mufflers have many undesirable characteristics. For example, spraying the slurry containing the powder binder can lead to an uneven distribution of the binder on the glass fibers. As a result, a handleable and usable preform is possible only when there is binder present at fiber-to-fiber contact points. In order to achieve a stable and homogenous product, larger amounts of binder may be needed. In addition, the application of the phenolic binder creates environmental and safety issues because the application into the preform mold is not always accurate, and a portion of the phenolic-based binder may be deposited outside the preform mold and onto the apparatus and/or floor. Additionally, because the thermosetting phenolic-based binder exists in a solid form and possesses high softening points, high temperatures are required to place the binder in a molten state so that the binder may then be cured. Further, long cycle times are needed to complete the heat-cure-cool cycle to fully cure the binder because entire preform must be heated to the appropriate binder cure temperature and be held at that high temperature for the entire cure time. Such an extended cure time results in increased production cycle time and increased cost. Additionally, the decomposition of the phenolic-based binder during burn-off releases noxious gases and undesirable odors. Utilizing a phenolic-based binder also requires a more expensive and complicated spraying and/or texturizing gun because the gun needs to handle both the solid powder chemical and water that is sprayed onto the fibers during the fiber texturization. Additionally, separate binder handling and delivery equipment is required on the floor, thus adding to the complexity of the current processes.
Thus, there exists a need in the art for an alternative binder composition and a simple, compact process to form a muffler preform that is environmentally friendly and which effectively reduces the costs associated with phenolic powder binders and processes currently used to make muffler preforms.
It is an object of the present invention to provide a preform product that is formed of texturized fibers that are at least partially coated with a thermoplastic sizing composition that includes one or more thermoplastic materials. The texturized fibers are compressed into a shape that is independent of a shape of a cavity (e.g., muffler) in which it is to be inserted. The thermoplastic material includes chemicals and/or compounds that are thermoplastic and/or chemicals and/or compounds that possess thermoplastic properties such as the ability to undergo numerous heat and cool cycles. Optionally, the thermoplastic sizing composition includes a silane coupling agent. In addition, additives needed during fiber manufacturing and/or post-processing of the continuous fibers may also be included in the thermoplastic sizing composition. The continuous fibers are heat resistant fibers, and may include glass fibers, carbon fibers, mineral fibers, mineral wool, rock wool and/or synthetic fibers. The continuous fibers may also include a sizing composition that includes a film forming agent, a silane coupling agent, and a lubricant that is positioned between the continuous fiber and the thermoplastic sizing composition. The texturized fibers are capable of decompressing into a loose mass of texturized, continuous fibers, which, in turn, can be recompressed into the preform product. This “reversible” nature of the texturized fibers results in zero or near zero waste.
It is another object of the present invention to provide a fiber product for use in forming a preform that includes a heat resistant continuous fiber substantially evenly coated with a thermoplastic sizing composition that includes at least one thermoplastic material. The thermoplastic sizing composition enables the formation of a preform without the application of any additional sizing or, binder compositions at later stages of the formation of the preform. The thermoplastic sizing composition may be applied to the continuous fiber with a Loss on Ignition (LOI) from about 0.5 to about 30%. Additionally, the thermoplastic sizing composition may be aqueous or non-aqueous, and optionally includes a silane coupling agent. The heat resistant continuous fiber may be a glass fiber, a carbon fiber, a mineral fiber, mineral wool, rock wool, or a synthetic fiber. A non-aqueous thermoplastic sizing composition may be characterized by the substantial non-aqueous nature or state of the ingredients during their use and application onto the continuous fibers. The continuous fibers may also include a conventional sizing composition that includes a film forming agent, a silane coupling agent, and a lubricant where the conventional sizing composition is positioned between the continuous fiber and the thermoplastic sizing composition.
It is a further object of the present invention to provide a muffler preform that includes a plurality of heat resistant continuous glass fibers substantially evenly coated with a thermoplastic sizing composition that includes a thermoplastic material. The continuous fibers are compressed into a preform that has a shape independent of the shape of a muffler cavity into which it is to be inserted. The compressed fibers decompress upon the application of heat to form a loose mass of coated, texturized fibers that fill or nearly fill the muffler cavity. In particular, heating the thermoplastic material on the fibers melts and releases the fibers from their compressed form. The reversible nature of the muffler preform eliminates the need for a preform that has the precise and/or complex dimensions of a muffler shell. The continuous heat resistant fibers include glass fibers, carbon fibers, mineral fibers, mineral wool, rock wool and/or synthetic fibers. In a preferred embodiment, the continuous fibers are continuous glass fibers. The glass fibers provide for good sound attenuation over the range of sounds emitted by an automobile engine.
It is an advantage of the present invention that the thermoplastic size composition is non-corrosive in nature, and, as a result, enhances the lifetime of the mold as well as the lifetime of the muffler.
It is yet another advantage of the present invention that the preform products are recyclable in that the texturized glass fibers from a non-usable preform can be re-molded and re-compressed into a compressed preform product.
It is an additional advantage of the present invention that the thermoplastic sizing composition enables the formation of the preform without the application of any additional sizing or binder compositions at later stages of the formation of the preform.
It is a further advantage of the present invention that because of the lack of additional chemicals in the inventive processes, the inventive methods are clean, dry, and environmentally friendly.
It is yet another advantage of the present invention that previously texturized fibers can be used to produce compressed preform products having any desired shape.
It is also an advantage of the present invention that the recycleability of the texturized glass fibers results in minimal or zero waste.
It is a feature of the present invention that an appropriate amount of glass is utilized in the compressed preform product to achieve optimum sound absorption, and the overall part weight is lowered.
It is another feature of the present invention that the compressed preform product is not required to have the exact or similar shape of the muffler cavity into which it is to be inserted.
It is yet another feature of the present invention that the preform product decompresses upon the application of heat.
It is a further feature of the present invention that in one exemplary embodiment, the thermoplastic binder is substantially even distributed on the continuous fibers as they are attenuated from the bushing.
The foregoing and other objects, features, and advantages of the invention will appear more fully hereinafter from a consideration of the detailed description that follows. It is to be expressly understood, however, that the drawings are for illustrative purposes and are not to be construed as defining the limits of the invention.
The advantages of this invention will be apparent upon consideration of the following detailed disclosure of the invention, especially when taken in conjunction with the accompanying drawings wherein:
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are described herein. All references cited herein, including published or corresponding U.S. or foreign patent applications, issued U.S. or foreign patents, or any other references, are each incorporated by reference in their entireties, including all data, tables, figures, and text presented in the cited references.
In the drawings, the thickness of the lines, layers, and regions may be exaggerated for clarity. It is to be noted that like numbers found throughout the figures denote like elements. It will be understood that when an element is referred to as being “on,” another element, it can be directly on or against the other element or intervening elements may be present. The terms “thermoplastic sizing”, “thermoplastic sizing composition” and “thermoplastic size” may be used interchangeably herein. In addition, the terms “size”, “sizing”, “size composition” and “size formulation” may be used interchangeably herein.
The present invention relates to preforms formed from continuous fibers that are substantially evenly coated with a thermoplastic sizing composition and a method of forming the preforms. The thermoplastic sizing composition enables the formation of the preform without the application of any additional sizing or binder compositions at later stages of the formation of the preform. The thermoplastic sizing composition may be used in an aqueous or non-aqueous phase, but is preferably non-aqueous in nature. The non-aqueous thermoplastic sizing composition may be characterized by the substantial non-aqueous nature or state of the ingredients during their use and application onto the fibers.
The thermoplastic sizing composition includes a thermoplastic material, and, optionally a silane coupling agent. The thermoplastic material in the thermoplastic sizing composition includes chemicals and/or compounds that are thermoplastic and/or chemicals and/or compounds that possess thermoplastic properties (e.g., the ability to undergo numerous heat and cool cycles and are thus “reversible” in nature). Other specific additives needed during fiber manufacturing and/or post-processing of the continuous fibers may also be included in the thermoplastic sizing composition. The thermoplastic sizing composition includes a thermoplastic material or a combination of thermoplastic materials. It is desirable that the thermoplastic material is capable of melting or having a lowered viscosity upon the application of energy and a higher viscosity or the ability to solidify naturally upon aided or unaided cooling. In addition, the thermoplastic sizing composition is desirably in a solidified form at room temperature.
The thermoplastic material may include chemicals or compounds capable of undergoing one or several heat cycles (i.e., melt and flow) and cool cycles (i.e., solidification). In addition, the thermoplastic materials may be based on synthetic or natural chemicals, polymers, oligomers, and/or waxes, including their modified structures or forms, and which may be ionic, non-ionic, or amphoteric in nature. The thermoplastic material is not particularly limited, and includes thermoplastic materials such as, but not limited, to polymers and/or modified polymers such those as based on polypropylene, polyester, polyamide, polyethylene, polyethylene oxide (PEO), polyacryl amide, polyacrylic acid, polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyphenylene ether (PPE), polyetheretherketone (PEEK), polyetherimides (PEI), polyvinyl chloride (PVC), ethylene vinyl acetate/vinyl chloride (EVA/VC), lower alkyl acrylate polymers, acrylonitrile polymers, partially hydrolyzed polyvinyl acetate, polyvinyl alcohol, polyvinyl pyrrolidone, styrene acrylate, polyolefins, polyamides, polysulfides, polycarbonates, rayon, nylon, phenolic resins, and epoxy resins; oxidized thermoplastics; functional thermoplastics; modified thermoplastics; waxes or waxy substances such as Vybar 103, Vybar 260, Vybar 825 (available from Baker Petrolite), and Polyboost 130 (available from S&S Chemicals); crystalline or semi-crystalline materials or waxes, microwaxes, microcrystalline waxes, silicones, modified silicones; surfactants, ethoxylated fatty alcohol ethers, ethoxylated fatty acid esters; modified fatty acid esters, modified fatty alcohol ethers, glycerol, modified glycerol, lubricants (stearates, metal stearates, ethylene bis-stearamide, and mono-stearamide); wetting agents; and combinations thereof.
The thermoplastic sizing composition may also optionally contain a silane coupling agent in a partially or a fully hydrolyzed state or in a non-hydrolyzed state. The silane coupling agents may also be in monomeric, oligomeric or polymeric form prior to, during, or after their use. The silane is preferably an organosilane. Non-limiting examples of silane coupling agents which may be used in the present size composition may be characterized by the functional groups amino, epoxy, vinyl, methacryloxy, ureido, isocyanato, and azamido. Suitable silane coupling agents that may be used in the thermoplastic size composition include aminosilanes, silane esters, vinyl silanes, methacryloxy silanes, epoxy silanes, sulfur silanes, ureido silanes, isocyanato silanes, fatty or long alkyl chain trialkoxysilanes (e.g., octyltrialkoxysilane, hexadecyltrialkoxysilane, and octadecyltrialkoxysilane), polymer chain trialkoxysilanes, polyethyleneglycol trialkoxysilane, polyethyleneoxide trialkoxysilane, polyether trialkoxysilane, and azido silanes.
If the thermoplastic sizing composition is in an aqueous phase, water may be included in an amount sufficient to dilute the thermoplastic sizing composition to a viscosity that is suitable for its application to glass fibers. In particular, the thermoplastic sizing composition may contain up to about 99% water, but preferable contains from about 40 to about 95% water. The fibers may then be dried for further use.
Additives may be included in the thermoplastic sizing composition to impose desired properties or characteristics to the composition and/or the final product. Non-exclusive examples of additives for use in the thermoplastic sizing composition include pH adjusting agents, chain flexibilizers, UV stabilizers, antioxidents, acid- or base-capturers, metal deactivators, processing aids, oils, lubricants, antifoaming agents, antistatic agents, thickening agents, adhesion promoters, compatabilizers, stabilizers, flame retardants, impact modifiers, pigments, dyes, colorants, masking fluids, and/or odors or fragrances.
In one exemplary embodiment, the thermoplastic sizing composition is applied to glass fibers during fiber formation. It is also to be appreciated that the methods described herein are made with reference to glass fibers for illustrative purposes, and that any continuous fiber capable of withstanding heat may be used in accordance with the present invention. For example, as shown in
When the thermoplastic sizing composition is applied onto the glass fibers 10 under the bushing, no additional step of applying a separate sizing composition, such as is described with respect to the alternate embodiment below, is needed. When the inventive thermoplastic sizing is in a non-aqueous form, the thermoplastic sizing composition is used in a molten form to lower the viscosity, to improve the flow, to improve the wetting on the fiber surface, and to allow a homogeneous or substantially homogenous application of the thermoplastic sizing composition on the fibers along their length during their manufacture.
Desirably, the application method applies a substantially even coating of the thermoplastic sizing composition onto the glass fibers 10. As used herein, the phrase “substantially even coating” is meant to indicate that the fibers 10 are evenly coated or nearly evenly coated with the thermoplastic sizing. The thermoplastic size composition may be applied to the fibers 12 with a Loss on Ignition (LOI) from approximately 0.5 to about 30% or more on the dried fiber, preferably between about 2 to about 10%, and most preferably from about 3 to about 7%. LOI may be defined as the percentage of organic solid matter deposited on the glass fiber surfaces.
After the glass fibers 10 are treated with the thermoplastic sizing composition, the coated glass fibers 10 are gathered into a strand 18 by a gathering shoe 20. When the thermoplastic sizing composition is in a non-aqueous and molten form, the strand 18 may be cooled by a cooling apparatus 22 (e.g., a water bath) to solidify the thermoplastic sizing composition onto the glass fibers 10. The coated fibers 10 may also (or alternatively) be air cooled and/or air-dried. If the coated fibers 10 are permitted to air dry or solidify, no further drying is needed. The thermoplastic sizing may also be allowed to cool and solidify naturally and wound into a single end direct roving package. On the other hand, if the thermoplastic sizing composition is an aqueous form, the strand 18 may be passed through or by a heating element such as a conventional oven and/or radio frequency drying equipment (not illustrated) to remove excess water, either partially or completely. Once the excess water is removed, the thermoplastic material is allowed to cool and solidify onto the glass fibers 10. After the thermoplastic material is solidified onto the glass fiber 10, the continuous, dried strand 24 is then gathered onto a creel to form a roving or package 26. Alternatively, the strand 18 may be wound into a package 26 during the fiber manufacturing or fiber formation process and then passed through an oven or other drying apparatus to remove excess water so that the fibers 24 having the thermoplastic sizing thereon are ready to be used to form preforms.
The glass utilized to form the continuous strand may be any type of glass suitable to withstand high temperatures, such as those emanating from engine exhaust. Preferred types of glass fibers include E-type glass fibers, S-type glass fibers, Hiper-tex™, and Advantex® glass fibers. It is contemplated that other types of heat resistant continuous fibers such as carbon fibers, mineral fibers, mineral wool, and rock wool (i.e., continuous basalt fibers) and synthetic fibers such as polyamide, aramid, and/or polyaramid may be utilized and/or commingled with the glass fibers to form the preform product. Glass fibers are preferred for use in mufflers because of their sound attenuation capability and resistance to the extreme heat conditions, such as those produced within a muffler. Because a thermoplastic sizing composition is applied to the glass fibers, the inventive method may be performed without the addition of, or commingling with, any other fibers or fibrous materials including any other types of glass fibers or synthetic and/or thermoplastic fibers. However, the addition of inorganic glass of different types and/or thermoplastic fibers such as polyester, polyethylene, polyethylene terephthalate, polypropylene, polyamide is not excluded from the realm of the present invention.
One exemplary method for forming the inventive preforms includes introducing a nozzle into the mold cavity (30), texturizing a glass strand and filling a mold cavity (32), compressing the texturized fibers (34), heating the compressed, texturized fibers (36), cooling the compressed, texturized fibers (38), and demolding (40), as is depicted in
One exemplary method of forming a preform product according to the present invention is depicted generally in
To fill the mold cavity 50 with a desired amount of glass fibers, the nozzle 44 is moved downwardly in the direction of arrow 64 until the neck 68 of the nozzle 44 is inserted into the mold cavity 50 through an opening or orifice 66 in the wall 54 of the mold 52. It is envisioned that the neck 68 may be inserted into the mold cavity 50 from any direction, such as from the sides or bottom of the mold 52. Once the neck 68 is in direct communication with the mold cavity 50 (see
The nozzle 44 blows the continuous glass strands 24 into the mold cavity 50 through the opening 66 in the walls 54 of the mold 52. Preferably, the air is pressurized by a conventional compressor and supplied by a hollow conduit in direct communication with the nozzle 44. As the continuous glass strands 24 are fed into the mold cavity 50, the expansion of the air flow into the mold cavity 50 separates the fibers forming the glass strands and entangles the individual fibers 10 to give the fibers a “fluffed-up” or wool-like appearance (i.e., texturize the glass fibers 10). It is to be noted that although the preferred embodiment described herein depicts the use of texturized glass fibers, non-texturized glass fibers may alternatively be used to form a preform product, in which case the nozzle 44 (e.g., texturizing gun) may be replaced by a simpler texturizing gun for providing the glass strands 24 into the mold cavity 50. In addition, it is within the purview of the invention to utilize pre-texturized continuous fibers and manually or automatically insert the pre-texturized fibers into the mold cavity 50. A vacuum may be applied to the mold cavity 50 in the vacuum box 60 to evenly distribute and guide or direct the continuous, texturized glass fibers 11 within the mold cavity 50 and to gather any small, broken glass fibers.
The continuous glass strands 24 are fed into the mold cavity 50 until the mold 52 has been filled with a desired quantity of glass fibers, which is the state represented by
Turning to
Once the thermoplastic material partially or completely achieves a molten state, the heat source 76 may be turned off and/or removed. The vacuum box 60, however, remains on to create suction to pull ambient air through the first and second perforated plates 56, 58, and disc 74. This passage of air through the disc 74 efficiently cools the thermoplastic material on the fibers and permits a rapid solidification of the thermoplastic material thus setting the compressed disc 74 into a disc-like preform. (See
The melting temperature depends on the specific thermoplastic material, and may melt at temperatures as low as 30° C. The amount of time necessary to achieve a temperature at which the glass fibers become bonded together is much shorter than the amount of time needed for a conventional thermoset binder to bond the fibers in a preform process. This reduction in heating time also equates to a shorter cooling time and overall reduced cycle time. For example, a cycle time of the instant invention may be 10 seconds compared to a cycle time of 22 minutes or more for conventional thermoset preform processes. Additionally, the uniform application of the thermoplastic sizing material on all of the surfaces of the glass fibers, achieved during the fiber manufacturing step, provides for a homogenous disc 74 (e.g., preform) and a consistent good part quality.
As represented in
It is also considered within the purview of the invention to form a compressed preform product without the aid of suction, such as is created in a vacuum box. In such an embodiment, glass fiber strands may be texturized with the aid of a texturizing apparatus (e.g., a texturizing gun) and filled into a mold cavity or, alternatively, previously texturized fibers may be inserted into a mold cavity. The texturized fibers may then be compressed into a compressed preform that is subsequently heated and cooled. A mold may be heated in a manner in which heat permeates the mold, for example, by placing the mold into an oven. After the mold is permitted to cool, the compressed preform product is removed.
In an alternate embodiment described below, the thermoplastic material is applied to the glass fibers as they are introduced into the mold cavity and entangled by the air flow within the nozzle to form texturized glass fibers. In this embodiment, the thermoplastic material may be referred to as a “thermoplastic binder,” but may include the same materials and function in the same way as the thermoplastic materials described above. The thermoplastic binder and can be ionic, non-ionic, or ampohoteric in nature, and is preferably sprayed onto the continuous fibers that have previously been applied with a convention aqueous sizing and dried to achieve a texturized fiber that is encapsulated or nearly encapsulated with the thermoplastic material. The thermoplastic binder may be in molten state during application (e.g., spraying) or, alternatively, it may be in a solid state or in be present in an aqueous slurry that includes the thermoplastic material in a solid state. As discussed above, the even or substantially even coating of thermoplastic material on the glass fiber 78 provides for a homogenous end product.
Turning to
The conventional size composition further includes water to dissolve or disperse the active solids for application onto the glass fibers. Water may be added in an amount sufficient to dilute the aqueous sizing composition to a viscosity that is suitable for its application to glass fibers and to achieve the desired solids content on the fibers. In particular, the size composition may contain up to about 99% water. The size composition may be applied to the fibers with a Loss on Ignition (LOI) of from approximately 0.01-1.0% on the dried fiber.
Once the neck 68 is in direct communication with the mold cavity 50 (see
In at least one exemplary embodiment of the present invention, the compressed disc 74 may be used as acoustic absorbing material in an engine exhaust muffler. One or more discs 74, depending on the size of the disc 74 and the size of the muffler, are randomly placed in the cavity of the muffler shell. It is to be appreciated that the compressed disc 74 may not necessarily have the shape of the muffler cavity. The compressed disc 74 may have exact or similar shape of the muffler cavity and may also be in a compressed form having similar shape of the muffler cavity. The compressed disc 74 thus provides for reduced complexity in the designing the preform shape. Upon heating the muffler, the compressed fibers within the disc 74 decompress and fill or nearly fill the muffler cavity. In particular, heating the thermoplastic material on the fibers melts and releases the fibers from their compressed or strained form. The glass fibers provide for good sound attenuation over the range of sounds emitted by an automobile engine. This reversible nature of the compressed disc 74 eliminates the need for a preform that has the precise and often complex dimensions of the muffler into which it is to be inserted. In addition, because the compressed disc(s) 74 are inserted into at least a partially finished muffler shell, there is no interference with the welding joints or overlap of the glass fibers outside of the muffler cavity. It is to be appreciated that the compressed disc 74 may be used in other embodiments that utilize texturized fibers as an inner component.
Further, the compressed disc 74 enables a lower part total weight. For example, typical muffler cavities are voluminous, and existing muffler preforms have the exact shape of the voluminous cavity (i.e., the existing preforms are not in a compressed form). To achieve good handleability of such voluminous preform shapes, more glass (e.g., 120-140 g/L) is required than is typically needed (i.e., approximately 80-100 g/L) to achieve optimum acoustic properties. On the other hand, in the present invention, the compressed disc 74 has an increased density (e.g., 600 g/L or higher) by the nature of it being compressed. As a result, an appropriate amount of glass is utilized to achieve a stable preform as well as optimum sound absorption, and the lower overall part weight is ideally achieved.
Additionally, the thermoplastic material on the fibers allows a bad preform product (e.g., a preform that that has not been properly compressed or has not been properly made due to a failure in any of the processing steps) to be converted into a usable preform part. Thus, the preform products formed by the inventive methods are recyclable. In particular, the texturized glass fibers forming the compressed disc, once they have been expanded to their “fluffy” texturized state by the addition of heat, may be re-compressed and re-molded into a compressed disc 74 due to the thermoplastic nature of the material. Thus, a preform product that has not been properly compressed may be re-compressed into a good preform product. Recycling the texturized glass fibers results in zero waste in the inventive method.
The method of the present invention provides numerous advantages over conventional methods of making preforms. For example, the process described herein is a simpler and a more compact process than conventional preform processes. The thermoplastic size composition is non-corrosive in nature, and, as a result, enhances the lifetime of the mold and enables the use of less expensive materials and mufflers. In addition, because the thermoplastic size compositions are non-hazardous substances, no special precautions need to be taken when handling or applying the thermoplastic size composition, unlike conventional phenolic binders. Due to the lack of additional chemicals in the inventive process, the inventive method is clean, dry, and environmentally friendly.
Having generally described this invention, a further understanding can be obtained by reference to certain specific examples illustrated below which are provided for purposes of illustration only and are not intended to be all inclusive or limiting unless otherwise specified.
The examples set forth below are divided generally into fiber products having the inventive sizing composition applied thereto and preform parts made from the sized fibers using the inventive methods described herein. The quality of the fiber product was assessed by measuring the tex and LOI on the fiber products. The quality of the preform parts was assessed by measuring the density, dimensions, and dimensional stability (e.g., handling ability) of the preform parts.
Continuous glass fibers were applied with a non-aqueous sizing composition including an ethoxylated fatty alcohol (ethoxylation with n=10-20 and a C18 fatty alcohol) during the manufacturing (e.g. forming) of the glass fibers. The composition was composed of 98% by weight of the ethoxylated fatty alcohol and 2% by weight of an aminosilane. The sizing composition was used in a molten form and applied to the forming fibers in a continuous way using an applicator roll type apparatus. The fibers were gathered to form a strand and wound into a package as the sizing on the strand was permitted to cool and solidify. The total sizing composition was applied to the glass fibers at a level of 7% by weight of the fibers, and was measured by burning off the chemistry from the fiber strand. The wound fiber strand may be used to form a preform product.
A non-aqueous sizing composition based on a lower molecular weight modified polypropylene (i.e., a molecular weight of approximately 6500-7000) was applied to continuous glass fibers during their manufacturing. “Modified polypropylene” as used in this example is meant to indicate maleic anhydride functional moieties grafted onto polypropylene chains (e.g., Licocene 1332 available commercially from Clariant). The modified polypropylene (35% by weight) was then melt blended with micro waxes (65% by weight) in order to lower and adjust the processing and application viscosity. No silanes were utilized in the sizing composition. The composition was used in molten form and applied to the forming fibers in a continuous manner using an applicator roll type apparatus. The fibers were gathered to form a strand and then wound into a package as the sizing on the strand was permitted to cool and solidify. The total composition was applied to the glass fibers at a level of 7.10% by weight of fibers. The wound fiber strand may be used to form a preform product.
A non-aqueous sizing composition based on a lower molecular weight modified polypropylene (i.e., a molecular weight of approximately 4000) was applied to continuous glass fibers during their manufacturing. A “modified polypropylene” as used in this example is meant to indicate silane functional moieties grafted onto polypropylene chains (e.g., Licocene 3262 available commercially from Clariant). The modified polypropylene (40% by weight) was melt-mixed with 60% by weight of a wax, blends of waxes, micro waxes, or polyethylene waxes in order to adjust to the processing viscosity. No additional silane was utilized in the sizing composition. The composition was used in molten form and applied to the forming fibers in a continuous manner using an applicator roll type apparatus. The fibers were gathered to form a strand and then wound into a package as the sizing on the strand was permitted to cool and solidify. The total sizing composition was applied to the glass fibers at a level of 6.73% by weight of fibers. The wound fiber strand may be used to form a preform product.
A non-aqueous sizing composition based on a hyperbranched polyethylene wax (e.g., Vybar 260 available commercially from Beker Petrolite) was applied to continuous glass fibers during their manufacturing. The hyperbranched polyethylene wax (32.7% by weight) was melt blended with 65.3% by weight of a wax, blends of waxes, micro waxes, or polyethylene waxes in order to adjust to the processing viscosity. Additionally, 2% by weight of an aminosilane was added to the sizing composition. The composition was used in molten form and applied to the forming fibers in a continuous manner using an applicator roll type apparatus. The fibers were gathered to form a strand and wound into a package as the sizing on the strand was permitted to cool and solidify. The total composition was applied to the glass fibers at a level of 7% by weight of fibers. The wound fiber strand may be used to form a preform product.
A non-aqueous sizing composition based on a hyperbranched polyethylene wax (e.g., Polyboost 130 available commercially from S&S Chemicals) was applied to continuous glass fibers during their manufacturing. The hyperbranched polyethylene wax (32.7% by weight) was melt-mixed with 65.3% by weight of a wax, blends of waxes, or micro waxes in order to adjust to the processing viscosity. The composition was used in molten form and applied to the forming fibers in a continuous manner using an applicator roll type apparatus. The fibers were gathered to form a strand and then wound into a package as the sizing on the strand was permitted to cool and solidify. The total composition was applied to the glass fibers at a level of 6% by weight of fibers. The wound fiber strand may be used to form a preform product.
A stable 30 g preform disk having a diameter of 65 mm was obtained using 2 strands of 3000 tex/7% by weight of the fibers of a thermoplastic coating input and texturized at 5 bar with a linear feed speed of 16 g/s (i.e., approx 1 kg/min). In this example, the 30 g of fibers was texturized into a mold having a volume of 330 ml. Compression enabled a preform product thickness reduction from 100 mm to 15 mm (i.e., a compression factor of 6.7). To obtain a proper setting of the fibers, the disc was heated with a hot air blower for 5 seconds at 130° C. while compression on the fibers was maintained. Room temperature air was allowed to be sucked through the preform for 5 seconds before removing the disc from the perforated plate. A vacuum of approximately 180 mbar (25 m/s) was applied during the entire process.
A 30 g stable preform disc having a diameter of 65 mm was obtained using 2 strands of 3000 tex/7% by weight of the fibers of a thermoplastic coating was texturized at 5 bar at a linear line speed of 16 g/s (i.e., approximately 1 kg/min). In this example, the 30 g of fibers was texturized into a mold having a volume of 330 ml. Compression enabled a preform product thickness reduction from 100 mm to 15 mm (i.e., a compression factor of 6.7). To obtain a proper setting of the fibers using lower vacuum energy, a 60 mbar vacuum (10 m/s) was utilized. Heating the disc at 130° C. using a hot air blower appeared to be efficient to achieve a solid part after a minimum of 10 s. 10 seconds of cooling time by removing the heat source was necessary before the disc was removed from the mold (i.e., demolding).
A stable 215 g elliptic preform having a diameter of 215 mm×165 mm was formed (see, e.g.,
In order to demonstrate the reversibility, i.e., the ability of a compacted preform part formed in accordance with the inventive method and thermoplastic sizing composition to decompress or “fluff up” under heat, a compacted preform (shown in
To demonstrate the reduction of waste that is achieved using the inventive method and inventive sizing composition, a compacted preform part formed in accordance with an exemplary method of the present invention was purposely destroyed by decompacting and pulling apart the preform part. The decompated, texturized strands were then placed into a mold cavity, heated, and cooled. The result was a newly formed compacted and usable preform part. Thus, the sized, texturized fibers can be re-used and re-compressed if an unacceptable part is formed, thereby reducing, or even eliminating, waste.
The foregoing description of the specific embodiments will so fully reveal the general nature of the invention that others can, by applying knowledge within the skill of the art (including the contents of the references cited herein), readily modify and/or adapt for various applications such specific embodiments, without undue experimentation, without departing from the general concept of the present invention. Therefore, such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein.
The invention of this application has been described above both generically and with regard to specific embodiments. Although the invention has been set forth in what is believed to be the preferred embodiments, a wide variety of alternatives known to those of skill in the art can be selected within the generic disclosure. The invention is not otherwise limited, except for the recitation of the claims set forth below.
