KR20070019657A - Development of thermoplastic composites using wet use chopped strand wucs - Google Patents

Abstract

A method for forming a thermoplastic composite 295 using wet chopped strand glass is provided. Wet reinforcing fibers, such as wet chopped strand glass fibers, are subsequently opened through the first carding machine 210, the condenser 220, and optionally the second carding machine 330. The opened reinforcing fibers are mixed with the resin 240 and sent to the first sheet former 270. The resin is preferably a polypropylene resin. An optional second sheet former may be used to form the final composite with high structural completeness. The resulting sheet can optionally pass through the needle felting device 280 to enhance the mechanical properties. The sheet is then passed through a thermal bonder 290 to thermally bond the reinforced glass fibers and the resin. The composite product out of the thermal bonder can then be used as a reinforcement in the molding process for making the composite article.

Description

DEVELOPMENT OF THERMOPLASTIC COMPOSITES USING WET USE CHOPPED STRAND (WUCS)}

FIELD OF THE INVENTION The present invention generally relates to methods of making thermoplastic composites and, more particularly, to dry methods for forming thermoplastic composites using wet chopped strand glass fibers.

Generally, glass fibers are formed by drawing a molten glass into a filament through a bushing or orifice plate, and adding a sizing composition to the filament comprising a lubricant, a coupling agent, and a binder resin for film formation. The aqueous sizing composition protects the fibers from interfilament wear and also allows good fusing between the glass fibers and the matrix in which they are used for reinforcement purposes. After the sizing composition is added, the fibers can be gathered into one or more strands, wound into a package, or collected by chopping in wet conditions. The gathered chopped strands may be dried and then cured into dry chopped strand glass (DUCS) or aggregated in the wet state of wet chopped strand glass (WUCS). Such chopped glass fiber strands are commonly used as reinforcements in thermoplastic articles. It is well known in the art that glass fiber reinforced polymer composites have higher mechanical properties compared to unreinforced polymers. Thus, the use of glass fiber reinforced composites results in better dimensional stability, tensile strength and tensile rate, bending strength and bending rate, impact resistance, and creep resistance.

Fiber mats, a form of fiber nonwoven reinforcement, are optimal as reinforcements for many types of plastic composites. The two most common methods of producing glass fibers from chopped glass fibers are the dry method and the wet method. Generally, in conventional wet methods, the chopped fibers are dispersed in a water slurry containing surfactants, viscosity modifiers, foam inhibitors, or other chemicals. Once the chopped glass fibers enter the slurry, the slurry is stirred so that the fibers are dispersed. The slurry comprising the fibers is placed on a moving screen and a significant amount of water is removed to form a web. The binder is then added and the resulting mat is dried to remove residuals and the binder is cured. The nonwoven mat formed is a combination of dispersed individual glass filaments. Wet methods are usually used when very uniform fiber distribution is required.

Common dry methods include processes such as air-laid processes and carding processes. In a typical air laid process, the dried chopped glass fibers are blown with air and sent to a conveyor or screen, where they are combined to form a mat. For example, dry chopped fibers and polymerized fibers are blown in air and gathered into loose webs on a screen or porous drum and then combined to form a mat in a random direction. In conventional carding methods, a thin wire or a series of rotating drums covered with teeth comb the glass fibers in parallel to impart direction to the web. The precise shape of the drum depends on the weight of the desired mat and the orientation of the fibers. The webs formed can be placed in parallel so that the majority of the fibers are aligned in the direction of web travel, or the fibers can be placed randomly without having a particular direction.

The dry method is particularly suitable when an open structure is required for the mat for the production of porous mats and for the rapid penetration of various liquids or resins. However, in such a conventional dry method, a mat which does not have a uniform weight distribution over the entire surface tends to be obtained, especially compared to a mat formed by a conventional wet method. In the dry process, the dry chopped fibers may be more expensive to process than the fibers used in the wet process because they are usually dried and aggregated in separate steps before the fibers are chopped.

It is desirable to form a fibrous mat having a uniform weight (as in the wet method) and having a porous open structure (as in the dry method) when reinforcing in forming the composite part. Thus, it is possible to make a non-porous mat with a substantially uniform weight distribution, which has a substantially uniform weight distribution, which can be used for the production of reinforced composite parts that can overcome the disadvantages of conventional wet and dry methods, at low cost and efficiently. I need a way.

It is an object of the present invention to provide a dry process for forming thermoplastic composites using wet reinforcing fibers. In a preferred embodiment the wet reinforcing fibers are wet chopped strand fibers. Generally, wet reinforcing fibers are agglomerated into bales, packages, or bundles of individual glass fibers. In the first step, the wet reinforcing fibers and the resin fibers are opened. In particular, the bundles or agglomerates of the wet reinforcing fibers are fed to the first carding machine which at least partially opens the bundles and filaments the wet reinforcing fibers. The first carding machine then feeds the condenser at least partially opened wet reinforcing fibers to the condenser to remove water from the wet reinforcing fibers. The reinforcing fibers can then be sent to a second carder for further filamentation and separation. The resin fiber is opened while passing through the third carding machine. Preferably the resin fiber is a polypropylene fiber. In other embodiments, the resin may be in the form of flakes, granules, or powders. Alternatively, resin in the form of flakes, granules, or powder may be added in addition to the resin fibers. The first, second, and third openers may be bale openers well known in the art.

In the second step, the reinforcing fibers and the resin fibers are transferred to the blower unit to be mixed. In this blower unit, the reinforcing fibers and the resin fibers are mixed with each other in the air stream. Preferably about 20-60% of the fibers in the air stream are reinforcing fibers and 40-80% are resin fibers.

In the third step, the mixed reinforcing fibers and the resin fibers are transferred from the blower unit to the first sheet molding machine to form the fibers into sheets. In some embodiments of the invention, the reinforcing fibers and resin fibers are sent from the blower unit to the filling box top, which towers the metered mixture of reinforcing fibers and resin fibers to the first sheet former. The fill box top may include a baffle to aid in mixing the reinforcing fibers with the resin fibers. If necessary, the sheet can be sent to form a second sheet. The composite product formed from the sheets discharged from the second sheet forming machine has a weight distribution of 100 to 3000 g / m 2.

In an optional fourth step, the sheet discharged from the first sheet molding machine or the second sheet molding machine is subjected to a sewing method in which a needle is inserted into the fibers of the sheet to entangle the reinforcing fibers with the resin fibers. The sewing method can be performed in a needle felting device.

After forming the sheet or undergoing an optional stitching step, the sheet passes through a thermal bonder to thermally bond the reinforcing fibers with the resin fibers. Thermal bonders include heating and bonding methods known in the art. The temperature of the thermal bonder is about 100 ° C. to 250 ° C. and depends on the melting point of the specific resin fiber used. Composite articles (eg, bonding mats) from thermal bonders can then be used as reinforcements in the molding process for making thermoplastic composite articles.

It is another object of the present invention to provide an apparatus for forming a composite article formed from wet reinforcing fibers. Preferably the wet chopped strained glass fibers agglomerated in the form of bales, packages, or bundles of each glass fiber are wet reinforced fibers. The apparatus comprises a first carding machine for at least partially opening the bundle of wet reinforcing fibers, a condenser for receiving the bundle of the wet reinforcing fibers at least partially opened and removing water therefrom to obtain dehydrated reinforcing fibers, dehydration And a blower unit for receiving the mixed reinforcing fibers and the resin and mixing them to form a mixture, a first sheet molding machine for receiving the mixture into a sheet and a thermal bonder for bonding the reinforcing fibers and the resin to form a composite product. In a preferred embodiment the device comprises a second carding machine for separating the reinforcing fibers from the at least partially opened wet reinforcing fiber bundles. Additionally, the apparatus may include a second sheet molding machine for further shaping the sheet, a filling box top for supplying a mixture of reinforcing fibers and resin to the first sheet molding machine, and / or a needle felting device for mechanically reinforcing the sheet. .

The present invention also includes methods of forming insulating sheets and / or low weight chopped strand glass mats. No resin fibers are used in this way. Wet reinforcing fibers, such as, for example, wet chopped strand glass fibers, are opened while passing through the first carding machine, the condenser, and optionally the third carding machine. The wet reinforcing fibers are then sent to the sheet former by the blower unit. Sheets exiting the sheet forming machine have a small structural integrity. As a result, the sheet can be sent to a needle processing apparatus for mechanical reinforcement. The binder resin is added before the sheet passes through the thermal bonder. The binder resin is added in any suitable manner known to those skilled in the art. The resulting product, for example a fibrous mat, can be used as an insulating product or with other types of foams and polymeric substrates.

The foregoing and other objects, features, and advantages of the present invention will become more apparent upon consideration of the following detailed description with reference to the accompanying drawings. The drawings for the purposes of illustration will be readily understood but they should not be construed as limiting the invention.

1 is a flow chart illustrating the steps of a representative dry method of the present invention.

2 is a schematic of an air-laid method using wet chopped strand glass fibers according to one or more exemplary embodiments of the present invention.

3 is a schematic view of another embodiment of the present invention in which no resin fibers are used.

4 is a graph showing the acoustic characteristics of the composite formed by the conventional dry method and the composite formed by the present invention.

Unless otherwise stated, all technical and scientific terms used herein have the general meaning understood by those of ordinary skill in the art to which this invention belongs. Although specific methods and materials equivalent or similar to the methods and materials described herein were used in the experiments and practices of the present invention, the preferred methods and materials are described herein. Like reference numerals in the drawings denote like elements.

The present invention relates to a method for forming thermoplastic composites using wet reinforcing fibers such as, for example, wet use chopped strands (WUCS) in the dry process. As shown in Fig. 1, in the method, the reinforcing fibers and the resin fibers are opened (step 10), the reinforcing fibers and the resin fibers are mixed (step 20), and the reinforcing fibers and the resin fibers are molded into sheets (step 30). ), Selectively stitch the sheets (step 40), and thermally bond the sheets (step 50) to give the sheet structural integrity. As used herein, a "sheet" includes a veil or mat, and the terms "sheet", "veil", "mat" are interchangeable.

In step 20 shown in FIG. 1, the reinforcing fibers and the resin fibers are opened. Suitable reinforcing fibers include, but are not limited to, wet use chopped strand glass fibers. Other kinds of glass fibers such as type A glass fiber, type C glass fiber, type E glass fiber, and type S glass fiber can also be used as the wet chopped strand glass fiber. Wet reinforcing fibers as used in the present invention are generally aggregated in the form of bales, packages, or bundles of each glass fiber. As used herein, the term “bundle” refers to the aggregation of wet reinforcing fibers in any form, which would be readily understood and distinguished by one of ordinary skill in the art.

In a preferred embodiment, the reinforcing fibers are wet chopped strand (WUCS) glass fibers. Wet chopped strand glass fibers used as reinforcing fibers can be formed by conventional methods known in the art. Preferably the wet chopped strand glass fibers contain 5-30% moisture, more preferably 5-15% moisture. This chopped strand glass fiber, Preferably it is 6-75 mm in length, More preferably, it is 18-50 mm. In addition, the diameter of this glass fiber is 11-25 micrometers, Preferably it is 12-16 micrometers.

The type of resin fiber used in the method of the present invention is not particularly limited, and polypropylene fiber, polyester terephthalate (PET) fiber, polyvinyl acetate (PVA) fiber, ethylene vinyl acetate / vinyl chloride (EVA / VC) fiber , Lower alkyl acrylate polymer fibers, acrylonitrile polymer fibers, partially hydrolyzed polyvinyl acetate fibers, polyvinyl alcohol fibers, polyvinyl p Lollidon (polyvinyl pyrrolidone) fiber, styrene acrylate fiber, nylon fiber, cellulosic fiber (e.g. cotton), natural fiber (e.g. sisal, jute) ), Kenaf, hemp) or combinations thereof. In a preferred embodiment, the resin fibers are polypropylene fibers. Preferably the length of resin fiber is 6-75 mm, More preferably, it is 18-50 mm. In addition, the resin fibers have 3 to 30 deniers (weight per unit length), and preferably 3 to 7 deniers. This resin fiber is functionalized with an acidic group by carboxylating with an acid such as, for example, acrylic acid or maleated acid, or an anhydride group or vinyl. It can be functionalized by the addition of acetate. In another embodiment, the resin may be in the form of flakes, granules or powders rather than fibers. Alternatively resin in the form of flakes, granules and / or powder may be added to the resin fibers.

Referring now to Figure 2, the opening process of the wet reinforcing fibers and resin fibers is shown in detail. Although FIG. 2 shows the opening of the wet chopped strand (WUCS) glass fibers as the preferred wet reinforcing fibers, any suitable wet reinforcing fibers known to those skilled in the art can be used in the method shown. In order to open the wet chopped stranded glass fibers, the WUCS glass fibers 200, usually in the form of a bale, package, or bundle of each glass fiber, are supplied to the first carding machine 210, which is part of the WUCS glass fiber. At least partially open and filamentize (eg individualize). The first carding machine 210 then feeds the WUCS glass fibers 200 to the condenser 220, where the water in the WUCS glass fibers 200 is removed. In an exemplary embodiment, free water, such as at least 70% of the water outside the glass fibers, is removed. However, it is preferable that substantially all of the water is removed from the condenser 220. The expression "substantially all water" as used herein indicates that all or almost all free water is removed.

Once the WUCS glass fiber 200 passes through the condenser 220, the glass fiber can pass through the second carding machine 230. The second carding machine 230 further filaments and separates the WUCS glass fibers 200.

In order to open the resin fiber 240, the resin fiber 240 passes through the third carding machine 250, in which the resin fiber 240 is opened and filamentized. In another embodiment where the resin is in the form of flakes, granules or powders, the third carding machine 250 may be formed into a blower unit 260 for mixing the WUCS glass fibers 200 and the resin fibers together. It can be replaced by a device suitable for dispersing. Such suitable devices will be readily apparent to those skilled in the art. In embodiments in which resin in the form of flakes, granules, or powder is added to the resin fibers 240, the third bale threading machine 250 is not replaced with flakes, granules, or powder dispersion devices. Alternatively, resin powder, flakes or granules may be added to the resin fibers 240 or introduced in place of the resin fibers prior to thermal bonding in the thermal coupler 290.

Chopped roving, dry chopped strand glass, A-, C-, E-, or S-type fiberglass, natural fiber (e.g., sisal, jute, kenaf ( kenaf)), other types of fibers such as aramid fibers, metal fibers, ceramic fibers, mineral fibers, carbon fibers, graphite fibers, polymer fibers, or combinations thereof. It can thus be opened and filamented by an additional carding machine (not shown). This fiber may be added to the air stream in the blower unit 260 and mixed with the WUCS glass fiber 200 as described below in connection with the resin fiber 240. If such fibers are added, preferably 10-30% of the fibers in the air stream are composed of these additional fibers.

The first, second, and third carding machines 210, 230, 250 may preferably be veil carding machines or other types of carding machines suitable for opening wet reinforcing fiber bundles. The composition of the carding machine is determined by the type and physical properties of the fiber to be opened. Openers suitable for use in the present invention may be conventional standard bale openers with or without a weighing device. The bale threader is equipped with a variety of fine threading elements and may also optionally include one or more liker-in drums or saw tooth drums. The bale drawer can be equipped with a feeding roller or a combination of a feeding roller and a nose bar. As the condenser 220, any drying or water removing device known in the art may be used, such as, but not limited to, an air dryer, an oven, a roller, a suction pump, a heating drum dryer, an infrared heating device, a hot air blower, and a microwave radiating device. Do not.

After the WUCS glass fibers 200 and the resin fibers 240 are opened and filamentized, they are transferred to the blower unit 260 and mixed with each other in the air stream (step 20 of FIG. 1). Preferably about 20-60% of the fibers in the air stream are reinforcing fibers (eg WUCS glass fibers) and 40-80% are resin fibers. The reinforcing fibers present in the air stream are preferably 40 to 60%.

The mixed WUCS glass fibers 200 and resin fibers 240 are then sent from the blower unit 260 to the first sheet former 270 by air flow where the fibers are molded into sheets (step 30 in FIG. 1). In the exemplary embodiment of the present invention, the opened WUCS glass fibers 200 and resin fibers 240 are sent from the blower unit 260 to the filling box top 265, where the WUCS glass fibers 200 and resin fibers 240 are provided. Is sent to the first sheet former 270 after the amount has been metered, for example, by an electronic weighing device. This filling box top 265 may be located within the first sheet former 270 or may be located outside the first sheet former 270. Additionally, the filling box top 265 may include a baffle for further mixing the WUCS glass fibers 200 and the resin fibers 240 before entering the first sheet former 270.

In another embodiment (not shown), the mixed WUCS glass fibers 200 and resin fibers 240 may be used to align the fibers in parallel as in a carding process prior to entering the first sheet former 270. It is blown over a tooth or thin wired drum or a series of drums.

In a preferred embodiment, the sheet formed by the first sheet former 270 is transferred to the second sheet former 275. In the second sheet molding machine 275, the sheet becomes substantially uniform in WUCS glass fiber 200 and resin fiber 240 distribution. Additionally, the second sheet molding machine 275 imparts a high structural completeness to the final composite product 295. In particular, the formed composite product 295 may have a weight distribution of 100 to 3000 g / m 2, preferably of 600 to 2000 g / m 2.

The first sheet former 270 and the second sheet former 275 include at least one liquor-in drum having two to four sieve drums. Depending on the reinforcing fibers used, the first sheet molding machine 270 and the second sheet molding machine 275 may be equipped with one or more of a condenser, a dispensing conveyor, a powder duster and a chip duster. Sheet molding machines with condensers and distribution conveyors are generally used to allow more fiber to be fed into the filling box tower and to increase the amount of air passing through the filling box tower. In order to improve the transverse distribution of the opened fibers, the dispensing conveyor can move across the direction of the sheet. As a result, the opened fibers are conveyed from the condenser to the filling box tower without pressure or with slight pressure.

The sheet exiting the first sheet molding machine 270 and the second sheet molding machine 275 has a weak structural completion. Therefore, in order to entangle the WUCS glass fiber 200 and the resin fiber 240, a stitching method of inserting a needle into the fiber of the sheet may be passed (step 40 of FIG. 1). The stitching method is executed in the needle felting device 280. Needle felting device 280 includes web feed mechanism, needle beam with needle plate, about 500 to about 7500 visible felt needles per machine width / m, removal plate, bed plate, and take-up mechanism It includes. The visible felt needle can be repeatedly inserted into and taken out of the sheet to mechanically entangle the WUCS glass fibers 200 and the resin fibers 240 with each other. The best needle selection for use in the special reinforcing and resin fibers used in the method of the present invention will be readily apparent to those skilled in the art.

After the sheet forming step 30 or the optional stitching step 40, the sheet is thermally bonded to the WUCS glass fiber 200 and the resin fiber 240 while passing through the thermal bonder 290. The thermoplastic properties of the resin fibers are used to form bonds with reinforcing fibers (eg, WUCS glass fibers 200) by heating upon thermal bonding. The thermal coupler 290 includes oven bonding, oven bonding using forced air, infrared heating, hot calendering, belt calendering, ultrasonic bonding, microwave heating, heating drums known in the art. Any heating and bonding method can be used, such as a heated drum. Optionally, two or more of these heating and bonding methods may be used together to bond the WUCS glass fibers 200 and the resin fibers 240 in the sheet. The temperature of this thermal bonder 290 is about 100 ° C to about 250 ° C, depending on the melting point of the particular resin fiber used.

Although the thermoplastic properties of the resin fibers can be used to join the reinforcing fibers (eg, WUCS glass fibers 200) and the resin fibers (eg, resin fibers 240), the monocomponent bonded fibers that bind the fibers. (single component binding fiber), bicomponent binding fiber, and / or powdered polymer may be added to the sheet to further bond the WUCS glass fiber 200 and the resin fiber 240. . Representative examples of such fibers include polyester fibers, polyethylene fibers, and polypropylene-polyethylene fibers. Such a binder may be added when the WUCS glass fiber 200 and the resin fiber 240 are first joined in the blower unit 260. If the binder is in powder or flake form, the sheet may be added to the sheet before entering the thermal bonder 290. Examples of suitable methods for adding the binder to the sheet include spraying the binder onto the sheet and coating or injecting the binder onto the sheet. As the sheet comprising the binder passes through the thermal bonder 290, the binder further binds the WUCS glass fibers 200 and the resin fibers 240.

Another method that can be used to increase the strength of the sheet after passing through the first sheet former 270 or the second sheet former 275 is chemical bonding. In chemical bonding, a binder is provided on the sheet or web to bond the reinforcing fibers with the resin fibers. Liquid binders, powder adhesives, foams and in some cases organic solvents may be used as chemical binders. Suitable examples of chemical binders include acrylate polymers and copolymers, styrene-butadiene copolymers, vinyl acetate ethylene copolymers, and combinations thereof, It is not limited to this. For example, polyvinyl acetate (PVA), ethylene vinyl acetate / vinyl chloride (EVA / VC), lower alkyl acrylate polymer, styrene-butadiene rubber, acrylonitrile polymer (acrylonitrile polymer), polyurethane, epoxy resin, polyvinyl chloride, polyvinylidene chloride, copolymer of vinylidene chloride with other monomers, partially hydrolyzed polyvinyl acetate, polyvinyl alcohol , Polyvinyl pyrrolidone, polyester resins, and styrene acrylate can be used as the binder. This chemical binder may be used by injection, coating or spraying on the sheet. Although the temperature required for initiation of chemical bonding is generally lower than the temperature required to thermally bond the reinforcing fibers with the resin fibers, the chemical bonding method is not as desirable as the thermal bonding method, which eliminates additional sheet drying and remaining binder. Because it is necessary.

The composite product 295 (eg, bonding mat) exiting the thermal bonder 290 can be used as a substantially reinforcement in the molding method for producing the composite article. For example, composite product 295 may be used for molding semi-structural and acoustic components of automobiles, for example in the furniture industry, such as for making backrests, for making cubicle partitions, and for industrial applications. And other industrial uses, such as parts for construction vehicles. The formed composite product 295 can be expanded by reheating (eg, loft) to have improved hardness and acoustic properties. Additionally, the composite product 295 may be further processed by conventional nip rolling (not shown) or laminating to be used in scrims and films. Shear slitting (not shown) then results in a final product that can be molded into interior parts such as headliners or trim panels of automobiles, object shelves, sunshades, instrument panel structures, and door interiors.

The processing of the composite product 295 exiting the thermal coupler 290 can be done in-line, ie in a continuous manner or in individual steps. Preferred processing is inline. In addition, any additional method, such as the addition of special films, scrims and / or fabrics, will be within the scope of the present invention.

Referring now to FIG. 3, another embodiment of the method of the present invention is shown. No resin fibers are used in this other embodiment. Wet reinforcement fibers 300, in particular wet chopped strand glass fibers, are generally provided in the form of veils, packages or bundles of individual glass fibers such as the first carding machine 210, the condenser 220 and optionally a second carding machine (FIG. 3). Are not shown) in turn. This wet reinforcing fiber 300 is then sent to the first sheet former 270 by the blower unit 260. Alternatively, the wet reinforcing fibers 300 may be conveyed to the fill box top 265 before entering the first sheet former 270. The filling box top 265 measures the amount of the reinforcing fibers 300 and supplies them to the first sheet forming machine 270. As in the preferred embodiment described above, the sheet may optionally be sent to a second sheet former (not shown in FIG. 3) and / or to a needle felting device 280 for mechanical reinforcement. The binder resin 350 may be added before the sheet passes through the thermal bonder 290. The binder resin 350 may be added by any suitable method, for example, by pouring and extracting or spraying the binder resin 350 onto the sheet. Any bonding resin can be used as long as the wet reinforcing fiber 300 can be bonded. Suitable examples include single and bicomponent fibers or powders. The amount of binder may vary depending on the type of mat desired. The sheet then passes through a thermal bonder 290 to cure the binder resin 350 and impart structural integrity to the reinforcing fibers 300. Alternatively, catalysts such as ammonium chloride, p-toluene, sulfonic acid, aluminum sulfate, ammonium phosphate, or zinc nitrate may be used to improve the rate of cure and the quality of the cured binder resin. The resulting product 395, such as, for example, a fiber mat, can be used as an insulating material or with other types of foams and polymeric substrates.

The method of the present invention has many advantages over conventional dry and wet methods. In particular, the process of the present invention results in a substantially uniform distribution of the reinforcing fibers and the resin fibers in both the mat and the formed composite product. "Substantially uniform distribution of reinforcing fibers and resin fibers" means a uniform or almost uniform distribution of resin fibers and reinforcing fibers. In addition, the use of wet chopped strand glass fibers in the present invention is less expensive, in particular, than conventional dry methods using dry chopped strand glass fibers. In addition, the process of the present invention may add other kinds of reinforcing fibers and / or resin fibers to obtain a number of desired composite properties. The binding chemicals of the reinforcing fibers can be easily modified to suit the properties of the individual types of resin fibers. Thus, according to the method of the present invention, various kinds of mats and composite products can be formed.

The formed composite product can also be reheated and expanded to have improved stiffness and acoustical properties as compared to products produced by conventional wet methods (eg loft). For example, an 800GSM product containing 55% WUCS formed by a conventional wet method may be lofted to a height of about 5mm, while a product containing 55% WUCS produced by the method of the present invention may be raised to a height of about 9mm. Can be lofted. This lofting allows the composite formed by the method of the present invention to have better sound absorption.

With the description of the present invention, the present invention may be better understood with reference to the examples provided below for purposes of explanation, but the following description does not limit the invention.

Yes

Composite products are produced according to preferred embodiments of the present invention. In particular, the wet chopped strand glass fibers were sequentially passed through a first bale carding machine, a condenser, and a second bale carding machine to dry and individualize. The polypropylene fibers are opened by a third bale carding machine, and the opened polypropylene fibers are added to the WUCS fibers and sent to a sheet molding machine. The sheet is then passed through a thermal bonding oven at 140 ° C. to 200 ° C. to form a composite product. The composite formed comprises about 55% WUCS glass fibers and 45% polypropylene fibers. The composite article is also molded by conventional wet methods using wet chopped strand glass fibers and polypropylene fibers. Like the composite formed by the method of the present invention, the composite article formed by the conventional method comprises about 55% WUCS glass fibers and 45% polypropylene fibers.

A comparison of the acoustic properties of the composite article according to the invention and the composite article by the conventional wet method was performed according to ASTM E1050. This result is shown in Table 1. 4 shows the results of Table 1. FIG. As shown in Fig. 4, the composite product according to the present invention method shown by the solid line shows superior sound absorption performance as compared to the composite product by the conventional wet method shown by the dotted line.

Frequency (Hz) Method of the invention Normal wet method 250 0.02 0.02 500 0.06 0.04 1000 0.11 0.07 2000 0.28 0.18 2500 0.38 0.28 3150 0.52 0.43 4000 0.69 0.61 5000 0.85 0.70 6300 0.97 0.71

Table 2 below shows a comparison of various characteristics of the composite product formed by the present method, the composite product formed by the conventional wet method, and the composite product formed by the conventional dry method. Acoustic measurements were performed according to ASTM E1050 and mechanical strength measurements were performed according to SAE J949. As shown in Table 2, the composite products formed by the method of the present invention exhibit better weight uniformity, reinforcement content consistency, and mechanical properties than products by conventional dry methods. In addition, the composite article by the method of the present invention exhibits better acoustical properties and post-heating thickness (eg lofting) compared to the composite article formed by conventional wet methods. It can be seen from Table 2 that the molding price of the composite product using the method of the present invention is lower than the molding price using a conventional dry method.

characteristic Invention method Normal wet method Ordinary Dry Method Weight uniformity ± 3 to 5% ± 3 to 5% ± 5 to 10% Reinforcement content uniformity ± 2% ± 2% ± 3 to 5% Mechanical properties 100% 100% 80 to 90% Acoustic characteristics 100% 70 to 90% 100% Thickness after heating 100% 50 to 60% 100% price 100% 100% 110 to 120%

In general, the present invention has been described above with specific examples. Although the present invention has been described as a preferred embodiment, those skilled in the art may make various changes in the description. The present invention is not limited to anything other than the claims described below.

Claims (20)

At least partially opening the bundle of wet reinforcing fibers 200; Removing water from the wet reinforcing fibers to obtain dehydrated reinforcing fibers (220); Mixing the resin 240 and the dehydrated reinforcing fibers to form a mixture of the dehydrated reinforcing fibers and the resin (260); Shaping the mixture into a sheet (270); Thermally bonding (290) the resin with dehydrated reinforcing fibers to form a composite article (295). 2. The method of claim 1, further comprising separating (230) dehydrated reinforcing fibers from the bundle. The method of claim 1 wherein the wet reinforcing fiber is a wet use chopped strand glass fiber. Chopped roving, dry chopped strand glass fiber, A-, C-, E-, S-type glass fiber, natural fiber, carbon fiber, aramid fiber, metal fiber, ceramic fiber, mineral (mineral) further comprising the step of adding a selected from fibers, graphite fibers and combinations thereof. 2. The method of claim 1, wherein forming the sheet comprises sequentially passing the mixture through a first sheet former (270) and a second sheet former (275). 6. The method of claim 5, wherein the sheet has a substantially uniform distribution of dehydrated reinforcing fibers and resin. The method of claim 1, further comprising sending the mixture to a filling box tower (265) prior to forming the sheet. 2. The method of claim 1, further comprising passing the sheet through a needle felting device (280) prior to thermal bonding. An apparatus for forming a composite article from wet reinforced fibers, A first carding machine 210 for at least partially opening the bundle of wet reinforcing fibers 200; A condenser 220 for receiving a bundle of the at least partially opened wet reinforcing fibers and removing water therefrom to obtain dehydrated reinforcing fibers; A blower unit 260 which receives the dehydrated reinforcing fibers and the resin 240 and mixes them to form a mixture; A first sheet former (270) for receiving the mixture into a sheet; And a thermal bonder (290) for bonding the reinforcing fibers and the resin to form a composite article (295). 10. The apparatus of claim 9, further comprising a second carding machine (230) for separating the dehydrated reinforcing fibers from the bundle. 10. The apparatus of claim 9, wherein the wet reinforcing fibers are wet use chopped strand glass fibers. 10. The apparatus of claim 9, further comprising a second molding machine (275) receiving a sheet from the first molding machine. 10. The apparatus of claim 9, further comprising a needle felting device (280) for mechanically strengthening the sheet. 10. The apparatus of claim 9, further comprising a packing box top (265) for receiving the mixture and sending the mixture to the first sheet forming machine. At least partially opening the bundle of wet reinforcing fibers 200; Removing water from the wet reinforcing fibers to obtain dehydrated reinforcing fibers (220); Molding (270) a sheet comprising the dehydrated reinforcing fibers; Adding (350) a binder resin to the sheet; Passing the sheet through a thermal bonder (290) to form a fiber mat (395) to cure the binding resin. The method of claim 15 further comprising separating the dehydrated reinforcing fibers from the bundle. 16. The method of claim 15, wherein the wet reinforcing fibers are wet chopped strand glass fibers. 16. The method as set forth in claim 15, wherein said sheet is passed through a needle felting device (280) before said binder resin is cured. 16. The method of claim 15 wherein forming the sheet comprises sequentially passing dehydrated reinforcing fibers through a first sheet former (270) and a second sheet former (275). 16. The method of claim 15, further comprising sending the dehydrated reinforcing fibers to a fill box top (265) prior to forming the sheet.

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