Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
  • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
  • B29C70/28—Shaping operations therefor
  • B29C70/40—Shaping or impregnating by compression not applied
  • B29C70/50—Shaping or impregnating by compression not applied for producing articles of indefinite length, e.g. prepregs, sheet moulding compounds [SMC] or cross moulding compounds [XMC]
  • B29C70/52—Pultrusion, i.e. forming and compressing by continuously pulling through a die
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
  • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
  • D04H1/42—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
  • D04H1/4209—Inorganic fibres
  • D04H1/4218—Glass fibres
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
  • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
  • D04H1/58—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives
  • D04H1/587—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives characterised by the bonding agents used
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
  • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
  • D04H1/58—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives
  • D04H1/593—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives to layered webs
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
  • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
  • D04H1/58—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives
  • D04H1/64—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives the bonding agent being applied in wet state, e.g. chemical agents in dispersions or solutions

Definitions

• This invention is directed to bonded glass fiber mats and, more particularly, to bonded mats having randomly disposed discrete glass fibers.
• Pultrusion is a process for continuously fo ⁇ ning reinforced plastic materials having a consistent cross-sectional profile.
• the word "pultrusion” is a hybrid which combines the words “pull” and "extrusion.”
• the product is literally pulled through a forming die.
• pultrusion involves feeding a multiplicity of fiberglass rovings, with additional plies of glass mat of appropriate width, through an impregnation system which applies a resin, normally a thermosetting material such as a polyester to the reinforcement.
• the resin-impregnated reinforcement is then reshaped to the approximate shape of the pultrusion die.
• the die itself is heated. As the product is drawn from the die, the resin is either cured, or very nearly cured.
• the endless product so formed is then cut in appropriate lengths.
• Pultruded products are used in a wide variety of applications. In many places they have replaced metallic construction materials, particularly those used in highly corrosive environments. Structural beams, floor gratings, handrails, ladders, and many similar products are now made by pultrusion processes.
• Continuous filament glass fiber mats have been used in a variety of pultrusion products.
• Continuous filament mats suffer from several limitations which can be problematic in pultrusion applications.
• continuous glass fiber mats can vary in weight by up to fifteen percent from one section to the next. This lack of consistency is undesirable in pultruded products, where weight uniforrnity is a main concern.
• the apparent density of the mat is relatively high. That is, the weight of the continuous filament mat is high relative to its thickness, which adds to the cost of such mats.
• mats formed from continuous filament glass fibers are mats formed from discrete or chopped glass fibers.
• Discrete glass fibers are relatively short in length, typically a few inches (many mm) or less.
• Attempts have been made in the past to use discrete glass fiber mats in pultrusion products.
• Such mats have been found to be mostly unacceptable because of lack of strength, conformability, i.e., the ability to be formed into complex shapes, compatibility with the matrix resin, or a combination of the above items.
• most discrete fiber mats have insufficient dry and wet tensile strength to survive the pultrusion process. 5 Therefore, a need exists for a bonded glass fiber mat which is flexible enough to be formed into complex shapes, is compatible with the matrix resin, and is lightweight yet has sufficient strength properties such that it can be used satisfactorily in pultrusion products.
• the present invention meets that need by providing an improved glass fiber mat which is lightweight, can be formed into complex shapes and has sufficient strength properties such that it can be used acceptably in pultrusion applications.
• the bonded mat of the present invention has been found to occupy generally the same volume as prior art continuous filament mats which typically weigh twice as much.
• the mat of the present invention will occupy generally the same volume in a pultruded product as would a continuous filament mat having twice the weight.
• the pultruded part can have comparable sectional performance properties as the same section produced with continuous filament mats.
• Use of the mat of the present invention will also result in a pultruded product with
• a bonded mat which is adapted for use in pultrusion applications.
• the mat comprises discrete, sized glass fibers, a coupling agent, and a binder selected from the group consisting of acrylic resins and styrene-polyester emulsions.
• the binder consists essentially of a
• the glass fibers are preferably from about 0.5 inch (12.7 mm) to about 3.0 inches (76 mm) in length, most preferably about 1.5 inches (38 mm) in length.
• the glass fibers also preferably have a diameter from about 10 microns to about 30 microns, most preferably from 16 to 23 microns.
• the coupling agent is preferably a silane. It is also preferable for the bonded mat to have a nominal basis weight of 0.20 to 1.0 oz ft 2 (61.030 to
• the bonded mat of the present invention has an average thickness of between 0.040 and 0.060 inch per ounce (0.036 and 0.054 mm/g) of mat material when subjected to 20 psi (239 kPa) of pressure, which is typical of compaction pressures encountered during pultrusion processes.
• a process for forming a bonded glass fiber mat which is adapted for use in pultrusion applications.
• the process is a modified papermal ⁇ ng process, typically known as the "wet-laid" process.
• the process for forming the bonded glass fiber mat is as follows. Discrete or chopped, sized fibers of a particular diameter and length are dispersed in an aqueous slurry through a combination of mechanical agitation and chemical dispersants. This slurry, suitably diluted, is presented to a continuous fine mesh conveyor or forming wire through which most of the water drains leaving a randomly oriented, uniform, continuous layer or web of fibers. Excess water is removed from the mat, typically by vacuum extraction.
• the web is transferred to a second screen conveyor and saturated with a binder selected from the group consisting of acrylic resins and styrene-polyester emulsions.
• a binder selected from the group consisting of acrylic resins and styrene-polyester emulsions.
• the binder saturated web is then passed through an oven where the water is evaporated and the binder cured.
• the resulting continuous, dry mat is wound upon a spool or mandril for further processing.
• a pultrusion product which comprises at least one layer of roving, at least one layer of veil, a resin, and a bonded mat.
• the bonded mat includes discrete, sized glass fibers, a coupling agent, and a binder consisting essentially of a compound selected from the group consisting of acrylic resins and styrene-polyester emulsions.
• the resin is preferably a styrene-based polyester or vinylester.
• a process for forming a pultruded product.
• the process comprises the steps of: providing a layer of glass roving; providing first and second layers of bonded mat each comprising discrete, sized glass fibers, a coupling agent, and a binder selected from the group consisting of acrylic resins and styrene-polyester emulsions; locating the roving layer between the first and second bonded mats; providing first and second layers of veil; locating the roving layer and the first and second bonded mats between the first and second layers of veil; impregnating the layers of veil, the first and second bonded mats and the roving layer with a thermosetting resin; and, drawing the impregnated layers of veil, mat and roving through a heated pultrusion die to form a pultruded product.
• the step of impregnating the layers of veil, mat and roving generally occurs in a resin bath ahead of the die but may occur when the veil layers, the roving layer, and the first and second mats pass through an initial portion of the heated pultrusion die.
• the thermosetting resin is a styrene-based polyester or vinylester. Accordingly, it is an object of the present invention to provide a bonded glass fiber mat which is flexible enough to be formed into complex shapes and is lightweight yet has sufficient strength properties such that it can be used satisfactorily in pultrusion products. It is a further object of the present invention to provide a bonded mat having randomly disposed discrete glass fibers.
• the bonded mat of the present invention is provided with discrete, sized glass fibers which are randomly dispersed throughout the bonded mat.
• Discrete fibers are non-continuous fibers which are relatively short in length, typically a few inches (many mm) or less.
• the fibers are preferably from about 0.5 inch (12.7 mm) to about 3.0 inches (76 mm) in length, most preferably about 1.5 inches (38 mm) in length.
• the glass fibers are preferably from about 10 microns to about 30 microns in diameter, most preferably 16 to 23 microns.
• the glass material is preferably E glass or S glass, but can be any other suitable glass product.
• the bonded mat also comprises a coupling agent, and a binder.
• the binder is selected from the group consisting of acrylic resins and styrene-polyester emulsions.
• the binder consists essentially of a thermosetting acrylic resin.
• the binder consists of a styrene/unsaturated polyester emulsion catalyzed with 1% BPO (benzoylperoxide).
• the binder is a thermosetting acrylic resin, an example of which is commercially available from Rohm and Haas Company under the product name "Experimental Resin HF-05.”
• This binder consists of a polyacrylic acid, triethanolamine and a promoter for the esterification of the acid groups.
• This binder is preferred because it is both strong and virtually inert to styrene which, as will be discussed below, is present in many resins used during pultrusion.
• the coupling agent can be any compound which serves to increase the adhesion of the binder or matrix resin to the glass fibers.
• a preferred coupling agent is a silane, an example of which is commercially available from OSi Specialties, Inc. under the product name "A-174.”
• the coupling agent is preferably from 0.1 to 0.04 weight percent of the final mat product.
• the coupling agent is preferably incorporated into the binder to insure that it is present at a specific level in the final mat rather than mixed with the glass fibers where it may be subject to being washed off during manufacture of the mat by white water and also to insure that the coupling agent does not interfere with fiber dispersion.
• the binder of the present invention contains about 1.4 solids weight percent of the silane coupling agent.
• Size is applied to alter the surface characteristics of the glass to, for example, impart lubricity to the glass.
• the size can be any suitable glass size composition.
• Typical ingredients of size compositions include lubricants such as tristearates, trioleates, polyvinyl pyrrolidone and mixtures thereof; film formers such as water soluble polymers; and coupling agents such as silanes.
• a preferred size composition contains a fatty acid amide, a silane, and a water soluble polymer and is compatible with the acrylic resin of the present invention. Glass fibers having such a size composition are commercially available from Owens-Corning Fiberglas Corporation under the product name "Wet Chopped Strands" with size number 685.
• the bonded mat can be formed by a variety of processes, including air-laid and wet-laid processes.
• the bonded mat is preferably formed by a wet-laid process.
• the wet laid process initially involves forming an aqueous dispersion or slurry of discrete, sized glass fibers in a mix tank with general chemical dispersion agents and agitation.
• the process water, "white water,” used to disperse the fibers may, in addition to the dispersion agents, contain defoamers and viscosity modifiers.
• dispersion agents are quaternary ammonium compounds and amine compounds such as polyoxyethylated tallow amine.
• the total solids content of the slurry is preferably from about 0.5% to about 0.9%, and is most preferably about 0.7%.
• the aqueous dispersion is processed into a wet-laid mat by a modified papermaking process utilizing an inclined wire fourdrineer such as the "Delta former,” available from Valmet-Sandy Hill Corporation, or the “Hydroformer” available from Domes (a division of the Voith- nor).
• inclined wire fourdrineer such as the "Delta former,” available from Valmet-Sandy Hill Corporation, or the "Hydroformer” available from Domes (a division of the Voith- nor).
• Examples of other machines which can be used to produce the mat of the present invention include Rotoformers and variations thereof which .are available from Valmet-Sandy Hill Corporation, and the "Vertiformer," which is commercially available from the Black Clawson Company.
• the aqueous fiber dispersion or slurry is processed into a wet-laid mat in the following manner.
• the above-described diluted slurry is deposited onto the screen conveyor or forming wire of an inclined wire fourdrineer.
• the majority of the water drains through the forming wire leaving a randomly oriented fiber web which is further dewatered by a vacuum slot or like device.
• the wet web is transferred to a second screen conveyor and a binder and a coupling agent applied.
• the mat is impregnated with the coupling agent and binder in a conventional manner, such as by curtain coating, spraying, a twin wire dip bath, or a two roll padder. Water, excess binder, and excess coupling agent are removed by a vacuum device.
• the binder-impregnated glass fiber product is dried and cured in one or more ovens.
• a typical temperature range for drying is from about 425°F (218°C) to about 580°F (304°C).
• the dried and cured product is the finished glass fiber mat.
• the glass fiber mat may be used to form a pultruded product through a conventional pultrusion process.
• one or more layers of roving, one or more layers of a veil, and a resin are used in forming the pultruded product.
• the layers of roving provide the pultruded product with longitudinal strength and structural support.
• the rovings or yarns may be made from glass, graphite, boron or polyaramid fibers.
• the roving is made from glass fibers.
• the bonded mat provides the pultruded product with transverse strength and structural support.
• the bonded mat of the instant invention offers the opportunity to introduce rovings in the transverse direction which rovings may be secured to the bonded mat by stitching. This arrangement allows the required amount of pultrusion die fillage to be met by adjusting the mat weight while the amount of transverse roving can be independently adjusted to meet the strength requirements of the pultruded product.
• the veil layers are used to provide a protective exterior layer which encases the glass fiber mats.
• Each veil layer comprises a fabric formed from glass or a thermoplastic material, such as a polyester.
• Inorganic veils such as glass veils made from E, C, or ECR glass are commercially available from the Owens-Corning Fiberglas Corporation.
• An organic veil comprising a spun lace polyester veil is commercially available from Precision Fabrics Group under the product name "Nexus.”
• a spun-woven polyester veil is commercially available from Precision Fabrics Group under the product name "Reemay.”
• the pultruded product may include the aforementioned layers stacked in order (from top to bottom) as follows: glass or thermoplastic veil, glass fiber mat, roving, glass fiber mat, roving, glass fiber mat, glass or thermoplastic veil.
• the pultruded product is formed in the following manner. First and second layers of glass roving, first and second layers of veil, and first and second layers of bonded mat are provided. The layers are arranged in order (from top to bottom) as follows: veil, glass fiber mat, roving, glass fiber mat, roving, glass fiber mat, veil. The combined layers are then impregnated with a thermosetting resin and drawn through a heated pultrusion die. Thereafter, the pultruded product is cured and cooled, resulting in a finished pultruded product.
• the bonded glass fiber mat of the present invention can also be used in other processes, such as a conventional reactive thermoplastic manufacturing process.
• Example A bonded mat having randomly dispersed glass fibers was formed in accordance with the present invention in the following manner.
• One hundred four (104) pounds (47.174 kg) of a silane coupling agent (commercially available from OSi Specialties Inc. under the product name "A-174") was hydrolyzed in 5800 pounds (2.6 metric tons) of water to which 3.6 pounds (1.633 kg) of glacial acetic acid had been added for a period of 30 minutes.
• Eight thousand nine hundred eleven (8911) pounds (4.0 metric tons) of a formaldehyde-free acrylic resin commercially available from Rohm and Haas Company as "Experimental Resin HF-05" was added to that mixture.
• Glass fibers generally having a diameter of 23 microns and a length of 1.5 inches (38 mm) were formed into a mat using a wet-laid process.
• the process or white water used in the wet-laid process contained approximately 10 ppm (parts per million) of a dispersion agent (commercially available from Rhone-Poulenc under the product name "Rhodameen VP532"); 15 ppm of a viscosity modifier (commercially available from American Cyanamid under the product name "Magnifloc 1885A”); and 5-10 ppm of defoamer (commercially available from Henkel under the product name "NXZ”) and was pH controlled to about 8.0 by ammonia.
• a dispersion agent commercially available from Rhone-Poulenc under the product name "Rhodameen VP532”
• 15 ppm of a viscosity modifier commercially available from American Cyanamid under the product name "Magnifloc 1885A”
• the above binder was applied to the mat at approximately 10% solids.
• the resultant mat had a nominal 5.6 percent loss on ignition (LOI) which yields a 0.08 weight percent silane level on the mat.
• Three layers of nominal 1.0 oz/ft 2 (305.152 g/m 2 ) bonded mat produced in essentially the same manner as the mat set out above were compressed under 20 psi (239 Pa) of pressure and exhibited a total thickness of 0.139 inch (3.531 mm) which indicates an average thickness of 0.046 inch per ounce (0.041 mm/g) of material.
• the average tensile strength in the longitudinal direction of the mat was 35.8 lbs/2-inch (16.2 kg/51-mm) strip, and the average tensile strength in the cross-machine direction of the mat was 31.3 lbs/2-inch (14.2 kg/51-mm) strip. While certain representative embodiments and details have been shown for purposes of illustrating the invention, it will be apparent to those skilled in the art that various changes in the processes and products disclosed herein may be made without departing from the scope of the invention, which is defined in the appended claims.

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• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Chemical & Material Sciences (AREA)
• General Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Dispersion Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Composite Materials (AREA)
• Mechanical Engineering (AREA)
• Nonwoven Fabrics (AREA)
• Reinforced Plastic Materials (AREA)
• Moulding By Coating Moulds (AREA)
• Laminated Bodies (AREA)

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Citations (2)

• 1995
  • 1995-05-25 TW TW084105280A patent/TW282431B/zh active
  • 1995-05-26 JP JP8502209A patent/JPH10501855A/ja active Pending
  • 1995-05-26 AU AU26924/95A patent/AU2692495A/en not_active Abandoned
  • 1995-05-26 EP EP95922132A patent/EP0765409A1/en not_active Withdrawn
  • 1995-05-26 WO PCT/US1995/006744 patent/WO1995034703A1/en not_active Application Discontinuation

Patent Citations (2)

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