WO2014195799A2 - Composition polymère renforcée par fibres permettant une fabrication composite sans vide, à cycle rapide - Google Patents

Composition polymère renforcée par fibres permettant une fabrication composite sans vide, à cycle rapide Download PDF

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Publication number
WO2014195799A2
WO2014195799A2 PCT/IB2014/001617 IB2014001617W WO2014195799A2 WO 2014195799 A2 WO2014195799 A2 WO 2014195799A2 IB 2014001617 W IB2014001617 W IB 2014001617W WO 2014195799 A2 WO2014195799 A2 WO 2014195799A2
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WIPO (PCT)
Prior art keywords
cure
reinforced polymer
polymer composition
fiber reinforced
temperature
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PCT/IB2014/001617
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English (en)
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WO2014195799A3 (fr
Inventor
Felix N. NGUYEN
Alfred P. HARO
Kenichi Yoshioka
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Toray Industries, Inc.
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Publication of WO2014195799A2 publication Critical patent/WO2014195799A2/fr
Publication of WO2014195799A3 publication Critical patent/WO2014195799A3/fr

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    • 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
    • B29C70/42—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles
    • B29C70/44—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles using isostatic pressure, e.g. pressure difference-moulding, vacuum bag-moulding, autoclave-moulding or expanding rubber-moulding
    • 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
    • B29C70/42—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles
    • B29C70/46—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles using matched moulds, e.g. for deforming sheet moulding compounds [SMC] or prepregs

Definitions

  • the present invention relates to an innovative composite manufacturing method comprising application of external means for rapid heating as well as higher compaction pressure than atmospheric pressure to a fiber reinforced polymer composition.
  • the fiber reinforced polymer composition comprises a reinforcing fiber and an adhesive composition comprising at least a thermosetting resin and a curing agent.
  • the fiber reinforced polymer composition may further include an interlayer toughening material.
  • the cure cycle time is determined from an ambient condition or a starting temperature when the fiber reinforced polymer composition starts curing to reach about 90% DoC (Degree of Cure) until it is cooled to a temperature and demolded.
  • An embodiment of the invention relates to a molded composite article comprising at least a fiber reinforced polymer composition, wherein the reinforced polymer composition comprises at least a reinforcing fiber and an adhesive composition, wherein the composite article is manufactured by heating the reinforced polymer composition in a mold at a rate of at least 5 °C/min from a starting temperature to a cure temperature under a compaction pressure of greater than atmospheric pressure exerted by a fluid and curing the fiber reinforced polymer composition over a curing period of time, wherein before the cure temperature is reached, the adhesive composition has a minimum viscosity of at most 40 poise and a degree of cure of at most 60 % upon reaching the cure temperature, and wherein the composite article after the curing period has a void content of at most about 3 %, wherein the composite article has a cure cycle time of at most about 2.5 times the curing period.
  • the adhesive composition is capable of snap cure and the cure cycle might further comprise at least a step cure before the cure temperature is reached.
  • a cure cycle time of at most 3 hr could be achieved for a composite article that contains an interlayer toughening material and at most 1.5 hr for a composite article that does not.
  • Another embodiment relates to a fiber reinforced polymer composition
  • a fiber reinforced polymer composition comprising a fiber reinforced polymer composition comprising a reinforcing fiber and an adhesive composition, the adhesive composition comprising at least a thermosetting resin and a curing agent which snap-cures at a cure temperature, wherein the adhesive composition when heated at a rate of more than 5 °C/min from an ambient condition to the cure temperature has a minimum viscosity of at most about 30 poise and a degree of cure of at most 45 % upon reaching the cure temperature.
  • the adhesive composition may further comprise an accelerator, a thermoplastic resin, a filler or a combination thereof, wherein subjecting the fiber reinforced polymer composition to a cure cycle of at most about 1.5 hr under a compaction pressure of greater than atmospheric pressure exerted by a fluid results in a composite article having a void content of at most about 2 %.
  • a cure cycle of at most about 3 hr and a void content of at most about 2 % could be achieved.
  • Another embodiment of the invention relates to a method of manufacturing a composite article comprising: (1) placing a fiber reinforced polymer composition comprising a reinforcing fiber and an adhesive composition in a mold; (2) applying heat to the fiber reinforced polymer composition at a rate of at least 5 °C/min from a starting temperature to a cure temperature under a compaction pressure of greater than atmospheric pressure exerted by a fluid such that the adhesive composition absorbs the heat and fills interstices in the fiber reinforced polymer composition and has a minimum viscosity of at most about 40 poise during heating and a degree of cure of at most 60% upon reaching the cure temperature; (3) curing the fiber reinforced polymer composition at the cure temperature for a curing period of time to form a cured composite article, wherein the cured composite article has a void content of at most about 2 %.
  • the adhesive composition comprises a thermosetting resin and a curing agent, and might further comprise an accelerator, a thermoplastic resin, an interlayer toughener, a filler or a combination thereof.
  • Another embodiment of the invention relates a manufacturing method for a molded composite article comprising: (1) placing a reinforced polymer composition between a tool surface and a flexible material; (2) enclosing the fiber reinforced polymer composition in a pressurized chamber; (3) heating the reinforced polymer composition from a starting temperature to a cure temperature by circulating a first heated pressurized fluid in the tool and circulating a second heated pressurized fluid in the pressurized chamber, and (4) increasing the temperature of the first fluid at a heating rate ri and the second fluid at a heating rate r 2 , wherein ⁇ and r 2 are at least 5 °C/min, wherein the second fluid is similar or different from the first fluid and pressurized greater than atmospheric pressure, wherein the reinforced polymer composition comprises a reinforcing fiber and a snap-cure thermoset adhesive composition, wherein the snap-cure thermoset adhesive composition includes an interlayer toughening material that is localized to layers of reinforcing fiber, and wherein a set of heating rates, temperature, and comp
  • thermoplastic resin an interlayer toughener, a filler or a combination thereof.
  • manufacturing method may comprise a sinusoidal heating and cooling rate applied to at least one of the first fluid and second fluid.
  • inventions relate to a method of manufacturing an article comprising one of the above-described fiber reinforced polymer compositions, achieving a cure cycle time of at most 3 hr and a void content of at most 2 %.
  • FIG. 1 shows a schematic of molding a composite article, including (1) A tool made from a material such as aluminum, aluminum alloy, steel, invar, nickel shell, or composite with a jacket or pipes for circulating a pressurized heated incompressible fluid at least 0.1 psi such as water, oil, or other suitable liquids or a pressurized compressible fluid of at least 0.1 psi.
  • the tool could be heated by other means such as microwave, infrared, induction, or similar.
  • Heating units such as thermal heaters or inductors could be mounted on the opposite of the molding surface or inside the tool; (2) Fiber reinforced polymer composition; (3) Flexible material such as a silicone membrane, a bagging material, a metal/metal alloy caul plate, or a composite caul plate; (4) Pressurized chamber with heating elements (5) (e.g., thermal heaters, radiators, infrared heaters, induction heaters, or microwave heaters) mounted inside the chamber to heat up a pressurized compressible fluid at least 5 psi circulating in the pressurized chamber. Other pressurized incompressible fluids might also be used for circulation.
  • heating elements (5) e.g., thermal heaters, radiators, infrared heaters, induction heaters, or microwave heaters
  • a fluid herein and thereafter can be a liquid or a gas, or combinations of two gases of similar of different kinds, combinations of two liquids of similar or different kinds, or combinations of a liquid and a gas of similar or different kinds.
  • the heating elements could be mounted outside of the chamber to heat up the fluid before entering the chamber.
  • vacuum (not shown) can also be introduced between the fiber reinforced polymer composition and the flexible material.
  • FIG. 2 shows a schematic of molding a composite article, including (1) A tool made from a material such as aluminum, aluminum alloy, steel, invar, nickel shell, or composite with a jacket or pipes for circulating a pressurized heated incompressible fluid (7) at least 0.1 psi such as water, oil, or other suitable liquids or a pressurized compressible fluid of at least 0.1 psi. Heating units such as thermal heaters or inductors could be mounted on the opposite of the molding surface or inside the tool.
  • the tool could be heated by other means such as microwave, infrared, induction, or similar ; (2) Fiber reinforced polymer composition; (3) Flexible material such as a silicone membrane, a bagging material, a metal/metal alloy caul plate, or a composite caul plate; (4) Pressurized chamber with heating elements (5) (e.g., thermal heaters, radiators, infrared heaters, induction heaters, or microwave heaters) mounted inside the chamber to heat up a pressurized compressible fluid (6) at least 5 psi circulating in the pressurized chamber. Other pressurized incompressible fluids might also be used for circulation.
  • the heating elements could be mounted outside of the chamber to heat up the fluid before entering the chamber.
  • vacuum (not shown) can also be introduced between the fiber reinforced polymer composition and the flexible material.
  • WO2012064662A1 (Toray Industries, Arai et al, 2012) and WO2012135754A1 (Toray Industries, Arai et al., 2012) to process composite parts for experimental aircraft; however, achieving the void content and property consistency in large aircraft parts has yet to be established because edge breathing becomes increasingly difficult as part sizes increase. In addition, cycle time often exceeds even that of autoclave processing due to long pre- vacuum time. Together, these limitations make vacuum bag curing infeasible as an alternative method for making large composite parts. Microwave ovens can be used to reduce cure times, and are not as expensive as autoclaves to put in service. However, a microwave oven has never been built at a size sufficient to cure large aircraft parts. An oven of this size could result in poor distribution of the microwaves, making heat generation and heat transfer through the parts more difficult to control.
  • one solution is to stage the composite at a temperature before a cure temperature for a staging period of time to allow trapped air pockets and volatiles to be depressed into the resin and/or removed by vacuum. As a result, cure cycle times increase.
  • Globe Machine Manufacturing Company (US20120114973A1 , Jacobsen et al, 2012) introduced pressure presses or press-claves or rapidclaves to process automobile parts with class-A surfaces and high production rates, yet a void content could be more than 5 %.
  • a molding material is placed onto a heated mold by a circulating heating fluid on one side and the other is subjected to a pressurized air to provide high compaction pressure similar to that from an autoclave on the other to form the material into a desired shape.
  • This process would result in faster cure times than Quickstep process as a staging step might not be needed or shorter.
  • Such a machine might not be suitable to process a fiber reinforced polymer composition to achieve void- free, especially with a thick composite article or a composite article with thickness variations and/or ply drops, due to one direction conduction heating from the tool's surface.
  • Significant design changes would be required to adapt these presses for molding of a fiber reinforced polymer (FRP) composition such as a prepreg for aerospace void-free composite articles at high production rates.
  • FRP fiber reinforced polymer
  • fast heating should be provided on both sides of the prepreg once it is placed in a mold, the prepreg should be capable of absorbing rapid heat transfer rates or high thermal conductivity or high thermal diffusivity, and the adhesive composition should be capable of optimal resin flow and snap cure once a cure temperature is reached.
  • bagging and tooling materials should be capable of absorbing heat quickly during ramp up.
  • High thermally conductive fiber reinforced polymer composites may be needed to address exotherm issues when molding a part with different thicknesses or ply drops.
  • An embodiment of the invention relates to a molded composite article comprising at least a fiber reinforced polymer composition, wherein the reinforced polymer composition comprises at least a reinforcing fiber and an adhesive composition, wherein the composite article is manufactured by heating the reinforced polymer composition in a mold at a rate of at least 5 °C/min from a starting temperature to a cure temperature under a compaction pressure of greater than atmospheric pressure exerted by a fluid (e.g., a gas, water, an oil, or a high boiling point organic compound such as glycerol) and curing the fiber reinforced polymer composition over a curing period of time, wherein before the cure temperature is reached, the adhesive composition has a minimum viscosity of at most 40 poise and a degree of cure (DoC) of at most 60 % upon reaching the cure temperature, and wherein the composite article after the curing period has a void content of at most about 3 %, wherein the composite article has a cure cycle time of at most about 2.5 times the curing period.
  • the cure composite article has a cure cycle time of at most about 2.25 times the sum of staging period(s) and the curing period.
  • the cure cycle time in this invention is taken from an ambient condition or a starting temperature when the fiber reinforced polymer composition starts curing to the point of reaching about 90 % DoC until it is cooled back down to a temperature and demolded.
  • the above embodiment requires a void- free composite article comprising at least a reinforcing fiber and a thermosetting adhesive composition which is molded by a rapid molding method. Rapid cure cycles are needed to overcome production rate barriers for parts that are currently molded by an autoclave or an oven. Elimination of void space is preferred to maximize performance for the composite article, at least equivalent to autoclave-quality.
  • Compaction pressure of at least equal to atmospheric pressure applied directly to one of the surfaces of the composite article by vacuum and/or a pressurized fluid is needed to remove trapped air pockets and volatiles in the parts and/or force the adhesive resin to flow and fill interstices in the fiber reinforced polymer composition during cure to become void-free.
  • low compaction pressure of about atmospheric pressure the viscosity of the adhesive composition has to be controlled effectively during cure such that the resin can flow to fill interstices before the cure temperature is reached.
  • the cure temperature is selected depending on the desired glass transition temperature of the cured fiber reinforced polymer composition. The cure temperature could be about 250 °C or less, or about 180 °C or less, or even 150 °C or less.
  • a free standing post cure at a temperature higher than the cure temperature might be needed to further increase glass transition temperature (Tg).
  • Typical compaction pressure could be at least 15 psi, at least 25 psi, at least 45 psi, or even at least 85 psi (typical autoclave pressure). Note that compaction pressure from a vacuum in the vacuum bag only method is 14.7 psi (atmospheric pressure). A desired compaction pressure is selected to promote flowability, but should minimize resin bleed out during cure.
  • Cure cycle time could be decreased by applying faster heating rates of at least 5 °C/min, at least 10 °C/min or even at least 20 °C/min.
  • one or more of the fiber reinforced polymer compositions, the tooling material, the bagging material, and the caul plate material is capable of being heated up at a rate of at least 5 °C/min by a material or a heat medium in contact therewith.
  • Faster heating rates exceptionally lower both viscosity and degree of cure (DoC), allowing the adhesive resin composition to fill interstices more completely while reaching the cure temperature more quickly.
  • Viscosity could be measured using a dynamic viscoelasticity measuring device (ARES, manufactured by TA Instruments) using parallel plates while simply increasing the temperature at a desired rate, with a strain of 10%, frequency of 0.5 Hz, and gap between two plates of 1 mm.
  • the percent cure of the adhesive composition (or DoC) could be determined using a differential scanning calorimeter (DSC) (Q200 with an RCS (mechanical refrigeration cooling system), manufactured by TA
  • thermosetting resin composition is determined by measuring the calorific power of curing (H 0 ) of the
  • DoC is calculated as [(3 ⁇ 4 - Hi) /H 0 x 100].
  • the adhesive composition When the adhesive composition is designed with snap-cure capability at the cure temperature, the cycle time is even reduced further.
  • the adhesive composition may comprise a latent curing agent and an accelerator that are activated at a desired temperature during the ramp up.
  • One or more step cures could be introduced, in which the fiber reinforced polymer composition is dwelled (staged) at a certain staging temperature below the cure temperature for a staging period of time while under vacuum to allow the adhesive resin composition to flow and fill completely a substantial amount of interstices in the present fiber reinforced polymer compositions before ramping to the cure temperature. Step cures often needed when a higher compaction pressure than 15 psi is not available, as normally observed by vacuum bag only molding methods.
  • the staging temperature could be in a temperature range within which the adhesive composition has a low viscosity.
  • the adhesive composition could have a minimum viscosity of at most 100 poise, or at most 50 poise, or even at most 20 poise and a degree of cure of at most 60 %, at most 50 %, at most 40 % before the cure temperature is reached, and snap-cure over a curing period of time of at most 60 min, at most 30 min or even at most 10 min. If a step cure is needed, the staging period of time could be at least about 5 min, at least 30 min, at least 60 min, or even at least 120 min to allow the adhesive
  • DoC degree of cure
  • a higher DoC before ramping up to the cure temperature could be needed to avoid expansion of air pockets due to volatiles such as residual moisture and low molecular weight components typically released at a higher temperature than 120 °C.
  • keeping the fiber reinforced polymer composition more than 120 min at the staging temperature to achieve the higher DoC might not be desired.
  • the fiber composite comprises an interlayer toughening material or an interlayer toughener, localized between two layers of the reinforcing fibers.
  • interlayer toughening material is needed to satisfy mode II fracture toughness and compression after impact (CAI) requirements of primary structures of aircraft.
  • CAI fracture toughness and compression after impact
  • the interlayer toughening material could block air paths and reduce resin flow in the x, y plane, z- direction or both, or even trap air pockets between two layers of the reinforcing fibers due to insufficient wetting by a base thermosetting resin.
  • a long staging period may be implemented to reduce voids.
  • higher compaction pressure than atmospheric pressure minimizes the corresponding staging periods and allows faster cycle times.
  • the interlayer toughener could be one or more thermoplastics, one or more elastomers, or combinations of one or more elastomers and one or more thermoplastics, or combinations of an elastomer and an inorganic material such as glass, or nanofibers or micronfibers.
  • the interlayer toughener could be in the form of a particulate or a sheet with a desired thickness (e.g., film, a mat, a woven or a non-woven fabric/veil). In some cases, the sheet form is preferred for ease of manufacturing the fiber reinforced polymer composition.
  • the average particle size could be no more than 100 ⁇ , or 5- 50 ⁇ , to keep them in the interlayer after curing to provide maximum toughness enhancement.
  • Such particles are generally employed in amounts of up to about 30 %, or up to about 15 % by weight (based upon the weight of total resin content in the composite composition).
  • the resulting interlayer thickness may be at most 200 ⁇ , at most 100 ⁇ or even at most 50 ⁇ .
  • the amount of the interlayer toughener and/or the thickness of the interlayer depend on desired mechanical properties versus weight of the fiber reinforced polymer composition. For instance, a higher amount of the interlayer tougheners could be needed to increase Guc and C AI, but at the expense of compressive properties such as open-hole compression (OHC).
  • thermoplastic materials examples include polyamides.
  • Suitable thermoplastic materials include polyamides.
  • Known polyamide particles include SP- 500, produced by Toray Industries, Inc., "Orgasol ®” produced by Arkema, and Grilamid ® TR- 55 produced by EMS-Grivory, nylon-6, nylon-12, nylon 6/12, nylon 6/6, and Trogamid ® CX by Evonik.
  • the interlayer toughener could be a conductive material or coated with a conductive material (e.g., Micropearl ® AU215, AU225 [Ni and Au-plated polymeric particles] from
  • Conductive refers to the electrical conductivity of a material. In some cases, it may also refer to the thermal conductivity, or collectively refers to both electrical and thermal conductivities of the material, or its thermoelectric property, i.e., its capability to generate an electric potential from a temperature difference, or heat from an electric potential difference.
  • An electrically conductive material herein refers to a material having an electrical conductivity of at least 10 "13 S/m, at least 10 "10 S/m, 10 "5 S/m, or even at least 10 "1 S/m, while a non-conductive material is a material having an electrical conductivity of less than 10 " S/m.
  • Examples of conductive interlayer particles include but are not limited to carbon particles and conductive material coated organic or inorganic particles.
  • the conductive interlayer particles could be larger and have a narrower size distribution than the interlayer toughener to provide better contact between two layers of the reinforcing fibers or two barrier layers. Typical amounts of the conductive particles could be up to 50 % of the total interlayer tougheners.
  • the interlayer toughener could be deposited directly on either surface of the plurality of reinforcing fibers impregnated by an adhesive composition, or incorporated in another adhesive composition if it is in a particulate form or a fibrous form, or impregnated by this adhesive composition if it is an assembly of a fibrous material.
  • the interlayer toughener could further comprise a curable functional group, such as an epoxy group, an amine group, an amide group, a carboxylic group, a carbonyl group, other suitable oxygen- or nitrogen-containing group, or a combination thereof, that reacts with either the adhesive compositions or the reinforcing fibers to further enhance fracture toughness and CAI.
  • the interlayer toughener could be a combination of a micron-sized thermoplastic particle as described above and a nanofiber such that the thermoplastic particle and the nanofiber could form discrete layers in the interlayer such that the layer of nanofibers is closer to the reinforcing fiber, the nanofiber could fill spaces among the interlayer particles (no discrete layers), or both.
  • Nanofibers are fibrous materials having a diameter of less than 1 um, less than 500 nm or even less than 100 nm. Suitable nanofibers could be carbon nanotubes (sometimes referred to as CNT), carbon nanofibers, oxide nanofibers (e.g.
  • the nanofiber could be an assembly of the nanofibers.
  • the assembly of the nanofibers could have a substantial amount of the nanofibers aligned in a direction or in random orientations.
  • the assembly could have a thickness of at least 10 nm, at least 100 nm, at least 1 ⁇ or even at least 10 ⁇ , and/or an area weight of at least 0.01 g/m 2 , at least 0.1 g/m 2 or even at least 1 g/m 2 .
  • reinforcing fibers include carbon fibers, organic fibers such as aramid fibers, silicon carbide fibers, metal fibers (e.g., alumina fibers), boron fibers, tungsten carbide fibers, glass fibers (e.g., S glass, S-l glass, S-2 glass, S-3 glass, E-glass, L-glass from AGY), and natural/bio fibers.
  • Carbon fiber in particular is used to provide the cured fiber reinforced polymer composition exceptionally high strength and stiffness as well as light weight. Of all carbon fibers, those with a strength of 2000 MPa or higher, an elongation of 0.5% or higher, and modulus of 200 GPa or higher are preferably used.
  • carbon fibers are those from Toray Industries having a standard modulus of about 200-250 GPa (Torayca ® T300, T300J, T400H, T600S, T700S, T700G), an intermediate modulus of about 250-300 GPa (Torayca ® T800H, T800S, TIOOOG, M30S, M30G), or a high modulus of greater than 300 GPa (Torayca ® M40, M35J, M40J, M46J, M50J, M55J, M60J).
  • the form and the arrangement of a plurality of reinforcing fibers used are not specifically limited. Any of the forms and spatial arrangements of the reinforcing fibers known in the art such as long fibers in a direction, chopped fibers in random orientation, single tow, narrow tow, woven fabrics, mats, knitted fabrics, and braids can be employed.
  • the term "long fiber” as used herein refers to a single fiber that is substantially continuous over 10 mm or longer or a fiber bundle comprising the single fibers.
  • short fibers refers to a fiber bundle comprising fibers that are cut into lengths of shorter than 10 mm.
  • a form wherein a reinforcing fiber bundle is arranged in one direction may be most suitable.
  • a cloth-like (woven fabric) form is also suitable for the present invention.
  • the adhesive composition could comprise at least a thermosetting resin and a curing agent.
  • the thermosetting resin may be defined herein as any resin which can be cured with a curing agent or a cross-linker compound by means of an externally supplied source of energy (e.g., heat, light, electromagnetic waves such as microwaves, UV, electron beam, or other suitable methods) to form a three dimensional crosslinked network having the required a preferred minimum resin modulus.
  • the thermosetting resin may be selected from, but is not limited to, epoxy resins, epoxy novolac resins, ester resins, vinyl ester resins, cyanate ester resins, maleimide resins, bismaleimide resins, bismaleimide-triazine resins, phenolic resins, novolac resins, resorcinolic resins, unsaturated polyester resins, diallylphthalate resins, urea resins, melamine resins, benzoxazine resins, polyurethanes, and mixtures thereof (e.g., epoxy and benzoxazine for reduced water uptake and hot- wet properties, or epoxy and cyanate ester for improved Tg), as long as it does not deteriorate the effects of the invention.
  • epoxy resins epoxy novolac resins, ester resins, vinyl ester resins, cyanate ester resins
  • maleimide resins bismaleimide resins, bismaleimide-triazine resins
  • phenolic resins no
  • epoxy resins could be used, including mono-, di-functional, and higher functional (or multifunctional) epoxy resins and mixtures thereof.
  • Multifunctional epoxy resins are preferably selected as they provide excellent glass transition temperature (Tg), modulus and even high adhesion to a reinforcing fiber.
  • epoxies are prepared from precursors such as amines (e.g., epoxy resins prepared using diamines and compounds containing at least one amine group and at least one hydroxyl group such as tetraglycidyl diaminodiphenyl methane, triglycidyl-p-aminophenol, triglycidyl- m-aminophenol, triglycidyl aminocresol and tetraglycidyl xylylenediamine and their isomers), phenols (e.g., bisphenol A epoxy resins, bisphenol F epoxy resins, bisphenol S epoxy resins, bisphenol R epoxy resins, phenol-novolac epoxy resins, cresol-novolac epoxy resins and resorcinol epoxy resins), naphthalene epoxy resins, dicyclopentadiene epoxy resins, epoxy resins having a biphenyl skeleton, tris(hydroxyphenol)methane based epoxies (
  • thermosetting resin matrix mixtures of two or more of these epoxy resins, and compounds having one epoxy group or monoepoxy compounds such as glycidylaniline, glycidyl toluidine or other glycidylamines (particularly glycidylaromatic amines) can be employed in the formulation of the thermosetting resin matrix.
  • compounds having one epoxy group or monoepoxy compounds such as glycidylaniline, glycidyl toluidine or other glycidylamines (particularly glycidylaromatic amines) can be employed in the formulation of the thermosetting resin matrix.
  • Examples of commercially available products of bisphenol A epoxy resins include jER ® 825, 828, 834, 1001, 1002, 1003, 1003F, 1004, 1004AF, 1005F, 1006FS, 1007, 1009, and 1010 (which are manufactured by Mitsubishi Chemical Corporation), EPON ® 825 and EPON ® 828 (from Momentive).
  • Examples of commercially available products of the brominated bisphenol A epoxy resin include jER ® 505, 5050, 5051 , 5054 and 5057 (which are manufactured by Mitsubishi Chemical Corporation).
  • Examples of commercially available products of hydrogenated bisphenol A epoxy resin include ST5080, ST4000D, ST4100D and ST5100 (which are manufactured by Nippon Steel Chemical Co., Ltd.).
  • Examples of commercially available products of bisphenol F epoxy resins include jER ® 806, 807, 4002P, 4004P, 4007P, 4009P and 401 OP (which are manufactured by Mitsubishi Chemical Corporation), and EpoTohto ® YDF2001 , YDF2004 (which are manufactured by
  • An example of a bisphenol S epoxy resin is Epiclon ® EXA-154 (manufactured by DIC Corporation).
  • Examples of commercially available products of tetraglycidyl diaminodiphenyl methane resins include SUMI-EPOXY ® ELM434 (manufactured by Sumitomo Chemical Co., Ltd.), YH434L (manufactured by Nippon Steel Chemical Co., Ltd.), jER ® 604 (manufactured by Mitsubishi Chemical Corporation), and Araldite ® MY720, MY721, and MY722 (which are manufactured by Huntsman Advanced Materials).
  • Examples of commercially available products of triglycidyl aminophenol or triglycidyl aminocresol resins include SUMI-EPOXY ® ELM100 (manufactured by Sumitomo Chemical Co., Ltd.), Araldite ® MY0500, MY0510 and MY0600, MY0610 (which are manufactured by Huntsman Advanced Materials) and jER ® 630 (manufactured by Mitsubishi Chemical Corporation).
  • Examples of commercially available products of tetraglycidyl xylylenediamine and hydrogenated products thereof include TETRAD-X and TETRAD-C (which are manufactured by Mitsubishi Gas Chemical Company, Inc.).
  • Examples of commercially available products of phenol-no volac epoxy resins include jER ® 152 and jER ® 154 (which are manufactured by Mitsubishi Chemical Corporation), and Epiclon ® N-740, N-770 and N-775 (which are manufactured by DIC Corporation).
  • cresol-novolac epoxy resins examples include Epiclon ® N-660, N-665, N-670, N-673 and N-695 (which are manufactured by DIC
  • Denacol ® EX-201 manufactured by Nagase chemteX Corporation.
  • Examples of commercially available products of naphthalene epoxy resins include HP- 4032, HP4032D, HP-4700, HP-4710, HP-4770, HP-5000, EXA-4701 , EXA-4750, EXA-7240 (which are manufactured by DIC Corporation) and MY0816 (which is manufactured by Huntsman).
  • Examples of commercially available products of dicyclopentadiene epoxy resins include Epiclon ® HP7200, HP7200L, HP7200H and HP7200HH (which are manufactured by DIC Corporation), Tactix ® 558 (manufactured by Huntsman Advanced Material), and XD- 1000-lL and XD-1000-2L (which are manufactured by Nippon Kayaku Co., Ltd.).
  • Examples of commercially available products of epoxy resins having a biphenyl skeleton include jER ® YX4000H, YX4000 and YL6616 (which are manufactured by
  • Examples of commercially available products of isocyanate-modified epoxy resins include AER4152 (manufactured by Asahi Kasei Epoxy Co., Ltd.) and ACR1348
  • thermosetting resin having a desirable resin modulus of at least 2.5 GPa may comprise both a tetrafunctional epoxy resin (in particular, a tetraglycidyl diaminodiphenyl methane epoxy resin) and a difunctional glycidylamine, in particular a difunctional glycidyl aromatic amine such as glycidyl aniline or glycidyl toluidine.
  • a tetrafunctional epoxy resin in particular, a tetraglycidyl diaminodiphenyl methane epoxy resin
  • difunctional glycidylamine in particular a difunctional glycidyl aromatic amine such as glycidyl aniline or glycidyl toluidine.
  • Another difunctional epoxy resin such as a difunctional bisphenol A or F/epichlorohydrin epoxy resin could be used to provide an increase in a flexural deflection of the cured adhesive composition;
  • the average epoxy equivalent weight (EEW) of the difunctional epoxy resin may be from 177 to 1500, for example.
  • the thermosetting resin may comprise 50 to 70 weight % tetrafunctional epoxy resin, 10 to 30 weight percent difunctional bisphenol A or F/epichlorohydrin epoxy resin, and 10 to 30 weight percent difunctional glycidyl aromatic amine.
  • the curing agent is also referred to as a cross-linker compound.
  • a cross-linker compound There are no specific limitations or restrictions on the choice of a compound as the curing agent, as long as it has at least one active group which reacts with the thermosetting resin and collectively provides the minimum resin modulus.
  • suitable curing agents include polyamides, dicyandiamide [DICY], amidoamines (e.g., aromatic amidoamines such as aminobenzamides, aminobenzanilides, and aminobenzenesulfonamides), aromatic diamines (e.g., diaminodiphenylmethane, diaminodiphenylsulfone [DDS] such as Aradur ® 9664-1 from Huntsman), aminobenzoates (e.g., trimethylene glycol di-p-aminobenzoate and neopentyl glycol di-p-amino-benzoate), aliphatic amines (e.g., triethylenetetramine, isophoronediamine), cycloaliphatic amines (e.g., isophorone diamine), imidazole derivatives, guanidines such as tetramethylguanidine, carboxylic acid anhydrides (e.g., methylhexanethoxylic acid an
  • a suitable curing agent or suitable combination of curing agents is selected from the above list.
  • dicyandiamide it will generally provide the product with good elevated-temperature properties, good chemical resistance, and a good combination of tensile and peel strength.
  • Aromatic diamines on the other hand, will typically give high heat and chemical resistance and high modulus.
  • Aromatic amidoamines could provide high resin modulus and high adhesion to the reinforcing fibers.
  • Aminobenzoates will generally provide excellent tensile elongation though they often provide inferior heat resistance compared to aromatic diamines.
  • Acid anhydrides generally provide the resin matrix with low viscosity and excellent workability, and, subsequently, high heat resistance after curing.
  • Phenol-novolac resins and cresol-novolac resins provide moisture resistance due to the formation of ether bonds, which have excellent resistance to hydrolysis. Note that a mixture of two or more above curing agents could be employed.
  • the reinforcing fiber and the adhesive composition could adhere more firmly, and in particular, the heat resistance, the mechanical properties such as compressive strength, and the environmental resistance of the fiber reinforced composite material obtained may be markedly enhanced.
  • an aromatic amidoamine e.g., 3-aminobenzamide
  • the curing agent can be employed in an amount up to about 75 parts by weight per 100 parts by weight of total thermosetting resin (75 phr).
  • the curing agent might also be used in an amount higher or lower than a stoichiometric ratio between the thermosetting resin equivalent weight and the curing agent equivalent weight to increase resin modulus or glass transition temperature or both.
  • an equivalent weight of the curing agent is varied by the number of reaction sites or active hydrogen atoms and is calculated by dividing its molecular weight by the number of active hydrogen atoms.
  • an amine equivalent weight of 2-aminobenzamide (molecular weight of 136) could be 68 for 2 functionality, 45.3 for 3 functionality, 34 for 4 functionality, and 27.2 for 5 functionality.
  • thermosetting resin having at least a functional group available to crosslink with an epoxy such as a benzoxazine resin could be used as a curing agent for the epoxy resin.
  • benzoxazine resins include, but are not limited to, multi-functional n- phenyl benzoxazine resins such as phenolphthaleine based, thiodiphenyl based, bisphenol A based, bisphenol F based, and/or dicyclopentadiene based benzoxazines.
  • n- phenyl benzoxazine resins such as phenolphthaleine based, thiodiphenyl based, bisphenol A based, bisphenol F based, and/or dicyclopentadiene based benzoxazines.
  • the weight ratio of the epoxy resin(s) to the benzoxazine resin(s) could be between 0.01 and 100.
  • the combination typically improves processability of the benzoxazine resin and achieves exceptional resin modulus, heat resistance and hot-wet properties owing to the benzoxazine resin.
  • Another embodiment of the invention relates to a fiber reinforced polymer composition
  • a fiber reinforced polymer composition comprising a fiber reinforced polymer composition comprising a reinforcing fiber and an adhesive composition, the adhesive composition comprising at least a thermosetting resin and a curing agent which snap-cures at a cure temperature, wherein the adhesive composition when heated at a rate of more than 5 °C/min from an ambient condition to the cure temperature has a minimum viscosity of at most about 30 poise and a degree of cure of at most 45 % upon reaching a cure temperature.
  • the adhesive composition when heated with a ramp rate of about 5 °C/min from an ambient condition to the cure temperature, may have a minimum viscosity of at most about 30 poise and a degree of cure (DoC) of at most 45 % upon reaching the cure temperature.
  • DoC degree of cure
  • the viscosity of the adhesive composition should be controlled effectively during cure such that the resin can flow to fill interstices before the cure temperature is reached and once the cure temperature is reached, the resin snap cures.
  • Faster heating rate of more than 5 °C/min could be desired to exceptionally lower both viscosity and degree of cure (DoC), allowing the adhesive resin composition to fill interstices more completely while reaching the cure temperature more quickly.
  • the adhesive composition may comprise a latent curing agent and an accelerator that is activated at a triggering temperature during the ramp up to speed up the reaction between the thermosetting resin and the curing agent.
  • the triggering temperature could be at least 80 °C, at least 100 °C, or even at least 120 °C. The better latency of the curing agent/accelerator combination leads to a lower the DoC and in turns an exceptional out time.
  • One or more step cures could be introduced, in which the fiber reinforced polymer composition is dwelled (staged) at a certain staging temperature below the cure temperature for a staging period of time while under vacuum to allow the adhesive resin composition to flow and completely fill a substantial amount of interstices in the fiber reinforced polymer composition before ramping to the cure temperature.
  • Step cures may be used when a compaction pressure greater than 15 psi is not available, as normally observed by vacuum bag only molding methods. Higher compaction pressures between 15-45 psi might need a step cure with a shorter staging period to effectively eliminate trapped air pockets or volatiles. No step cure might be needed when the compaction pressure is higher than 45 psi.
  • the staging temperature could be in a temperature range within which the adhesive composition has a low viscosity.
  • the staging temperature could be in a temperature range within which the adhesive composition has a low viscosity. If a step cure is needed, the staging period of time could be at least about 1 min, at least 5 min, at least 30 min, at least 60 min, or even at least 120 min. As a result, the adhesive composition might reach a degree of cure (DoC) of at most 10 %, at most 30 %, at most 50 % or even at most 60 % before ramping up to the cure temperature. A higher DoC before ramping up to the cure temperature could be needed to avoid expansion of air pockets due to volatiles such as residual moisture and low molecular weight components typically released at a higher temperature than 120 °C. Yet, in order to achieve desired cure cycle times, keeping the fiber reinforced polymer composition more than 120 min at the staging temperature to achieve the higher DoC might not be desired.
  • DoC degree of cure
  • An accelerator could be used with the curing agent to speed up the reaction.
  • a compound or combination of compounds as the accelerator, as long as it can accelerate reactions between the resin and the curing agent and does not deteriorate the effects of the invention.
  • Examples include urea compounds, sulfonate compounds, boron trifluoride piperidine, p-t-butylcatechol, sulfonate compounds, tertiary amines or salts thereof, imidazoles or salts thereof, phosphorus curing accelerators, triphenylphosphine, metal carboxylates and Lewis or Bronsted acids or salts thereof.
  • Suitable urea compounds include ⁇ , ⁇ -dimethyl- N'- (3,4-dichlorophenyl) urea, toluene bis(dimethylurea), 4,4 '-methylene bis (phenyl dimethylurea), and 3-phenyl- 1 ,1- dimethylurea.
  • Commercial examples of such urea compounds include DCMU99
  • an imidazole compound or derivative thereof examples include 2MZ, 2PZ and 2E4MZ (all manufactured by Shikoku Chemicals Corporation).
  • An example of inclusion imidazole compound including Nissocure ® TIC-188 [2P4MHZ (2-phenyl-4-methyl-5-hydroxymethylimidazole)/TEP (l,l ,2,2-tetrakis(4- hydroxyphenyl)ethane] from Nippon Soda.
  • Lewis acid catalysts include complexes of a boron trihalide and a base, such as a boron trifluoride piperidine complex, boron trifluoride monoethyl amine complex, boron trifluoride triethanol amine complex, and boron trichloride octyl amine complex.
  • sulfonate compounds include methyl p- toluenesulfonate, ethyl p-toluenesulfonate and isopropyl p-toluenesulfonate.
  • a combination of one or more curing agents and one or more accelerators could be optimized to keep a DoC of at most 60 %, at most 40 %, at most 20 % or even at most 10 % during ramp up to the cure temperature and snap cure within at most 5 min, at most 10 min, at most 30 min or even at most 60 min to achieve at least a DoC of 90 % before cooling down.
  • An amount of the accelerator used could be at least 0.1 phr, at least 0.5 phr, or even at least 5 phr.
  • the accelerator could be selected and tailored to trigger and to speed up the reaction between the thermosetting resin and the curing agent or encapsulated by a material that could trigger a release mechanism of the accelerator at a certain temperature.
  • the triggering temperature could be at least 80 °C, at least 100 °C, or even at least 120 °C.
  • suitable combinations of accelerator and curing agent and their ratios in an adhesive composition are selected such that when a heat transfer rate of at least 5 °C/min, at least 10 °C/min, or even at least 20 °C/min is applied to the adhesive composition, heat resistance or Tg and mechanical properties of the formulated resin are not impaired significantly and the desired DoC is met before the cure temperature is reached. Examples of such combinations include DCMU or U-24 with DIC Y and sulfonate with DDS .
  • the adhesive composition could further comprise an interlayer toughener.
  • an interlayer toughener There is no restriction on choices of the interlayer toughener, as long as the effects of the inventions are not deteriorated. Examples of the interlayer toughener were already discussed previously.
  • the adhesive composition could optionally comprise a thermoplastic resin, a filler, or a combination thereof.
  • the thermoplastic resin may be used to modify the viscosity of the adhesive composition for processing purposes, and/or enliance its toughness.
  • the thermoplastic resin when present, may be employed in any amount up to 50 phr, or even up to 35 phr for ease of processing.
  • polyetherimides polyimides having phenyltrimethylindane structure
  • polysulfones polyethersulfones (e.g., Sumikaexcel ® PES5003P from Sumimoto Chemical Co., Ltd., Virantage ® VW-10700RP from Solvay)
  • polyetherketones polyetheretherketones
  • polyaramids polyethernitriles
  • polybenzimidazoles their derivatives and their mixtures thereof.
  • the selected thermoplastic resin could be soluble in the thermosetting resin to a large extent to form a homogeneous mixture.
  • the thermoplastic resins could be compounds having aromatic skeletons which are selected from the group consisting of polysulfones, polyethersulfones, polyamides,
  • polyamideimides polyimides, polyetherimides, polyetherketones, and polyetheretherketones, their derivatives, the alike or similar polymers, and mixtures thereof.
  • Polyethersulfones, polyimides, polyetherimides and mixtures thereof could be of interest due to their high heat resistance and toughness.
  • Suitable polyethersulfones for example, may have a number average molecular weight of from about 10,000 to about 75,000.
  • the filler in the adhesive composition may be used to further improve mechanical properties such as toughness or strength or physical/thermal properties of the cured fiber reinforced polymer composition as long as the effects of the present invention are not deteriorated.
  • the filler is intended to toughen the thermosetting resin inside the plurality of reinforcing fibers (hereafter referred to intralayer toughener)
  • its longest dimension could be no more than 1 ⁇ .
  • a filtering effect in that particles could be concentrated outside a plurality of reinforcing fibers could result if the longest dimension is greater than 1 ⁇ .
  • One or more polymeric and/or inorganic tougheners can be used.
  • the intralayer toughener could be a conductive material or a non-conductive material.
  • the intralayer toughener may be uniformly distributed in the form of particles in the cured fiber reinforced polymer composition to maximize its effects on the intended purpose(s).
  • Such intralayer tougheners include, but are not limited to, elastomers, branched polymers, hyperbranched polymers, dendrimers, rubbery polymers, rubbery copolymers, block copolymers, core-shell particles, oxides or inorganic materials such as clay, polyhedral oligomeric silsesquioxanes (POSS), carbonaceous materials (e.g., carbon black, carbon nanotubes, carbon nanofibers, fuUerenes), ceramics and silicon carbides, with or without surface modification or functionalization.
  • PES polyhedral oligomeric silsesquioxanes
  • block copolymers examples include the copolymers whose composition is described in US 68941 13 (Court et al, Atofina, 2005) and include Nanostrength ® SBM (polystyrene-polybutadiene- polymethacrylate), and AMA (polymethacrylate-polybutylacrylate-polymethacrylate), both produced by Arkema.
  • suitable block copolymers include Fortegra ® and the amphiphilic block copolymers described in US 7820760B2, assigned to Dow Chemical.
  • core-shell particles examples include the core-shell (dendrimer) particles whose compositions are described in US20100280151A1 (Nguyen et al, Toray Industries, Inc., 2010) for an amine branched polymer as a shell grafted to a core polymer polymerized from polymerizable monomers containing unsaturated carbon-carbon bonds, core-shell rubber particles whose compositions are described in EP 1632533A1 and EP 2123711A1 by Kaneka Corporation, and the "KaneAce MX" product line of such particle/epoxy blends whose particles have a polymeric core polymerized from polymerizable monomers such as butadiene, styrene, other unsaturated carbon-carbon bond monomer(s), or their combinations, and a polymeric shell compatible with the epoxy, typically polymethylmethacrylate, polyglycidylmethacrylate, polyacrylonitrile or similar polymers.
  • core-shell (dendrimer) particles whose compositions are
  • block copolymers in the present invention are the "JSR SX” series of carboxylated polystyrene/poly divinylbenzenes produced by JSR Corporation; "Kureha Paraloid” EXL-2655 (produced by Kureha Chemical Industry Co., Ltd.), which is a butadiene alkyl methacrylate styrene copolymer; "Stafiloid” AC-3355 and TR-2122 (both produced by Takeda Chemical Industries, Ltd.), each of which are acrylate methacrylate copolymers; and “PARALOID” EXL-2611 and EXL-3387 (both produced by Rohm & Haas), each of which are butyl acrylate methyl methacrylate copolymers.
  • suitable oxide particles include Nanopox ® produced by nanoresins AG. This is a master blend of functionalized nanosilica particles and an epoxy.
  • the reinforcing fiber such as carbon fiber is thermally conductive
  • the fiber reinforced polymer composite loses its thermal conductivity.
  • the resin and the interlayer toughening material (if present) of the fiber reinforced polymer composition are certainly made to have suitable thermal conductivities.
  • an interfacial region between the reinforcing fiber and the adhesive composition becomes an insulated region. Consequently, suitable thermally conductive materials could be incorporated in the resin, in the interlayer, and/or in the interfacial region to regain the conductivity.
  • the adhesive composition is tailored to have a thermal conductivity of at least 0.2 W/m.K, at least 0.25 W/m.K or even at least 0.3 W/m.K, and when combined with a reinforcing fiber in the cured fiber reinforced polymer composition, z-direction thermal conductivity of at least 0.25 W/m.K, at least 0.3 W/m.K or even at least 0.4 W/m.K could be achieved.
  • High thermally conductive fiber reinforced polymer composites could also address exotherm issues when molding a part with different thicknesses or ply drops.
  • Another embodiment of the invention relates to a method of manufacturing a composite article comprising: (1) placing a fiber reinforced polymer composition comprising a reinforcing fiber and adhesive composition comprising at least a thermosetting resin and a curing agent in a mold; (2) applying heat to the fiber reinforced polymer composition at a rate of at least 5 °C/min from a starting temperature to a cure temperature under a compaction pressure of greater than atmospheric pressure exerted by a fluid such that the adhesive composition absorbs the heat and fills interstices in the fiber reinforced polymer composition and has minimum viscosity of at most about 40 poise during heating and a degree of cure of at most 60 % upon reaching the cure temperature; (3) snap-curing the fiber reinforced polymer composition at the cure temperature for a curing period of time to form a cured composite article, wherein the cured composite article has a void content of at most about 2 %.
  • the cure cycle time could be at most 5 hr, at most 3 hr or even at most 2 hr.
  • the composite article comprises a reinforcing fiber, a thermosetting resin and a curing agent.
  • the fiber reinforced polymer composition might further comprise an accelerator, an interlayer toughener, a thermoplastic resin, a filler or a combination thereof. There is no limitation on the choices of these components as long as the effects of the invention are not deteriorated.
  • the reinforced polymer composition in a mold may be heated at a rate of at least 5 °C/min, at least 10 °C/min, or even at least 20 °C/min from an ambient condition or a starting temperature to a cure temperature under a compaction pressure at least about atmospheric pressure.
  • Higher heating rates not only reduce the cure cycle time but also lower viscosity and DoC, allowing the adhesive resin composition to flow and fill a substantial amount of interstices in the fiber reinforced polymer composition.
  • Higher compaction pressure allows better elimination of trapped air pockets and/or volatiles.
  • the adhesive composition could have a minimum viscosity of at most 100 poise, or at most 50 poise, or even at most 20 poise and a DoC of at most 60%, at most 50 %, at most 40 % before the cure temperature is reached, and snap-cure over a curing period of time of at most 60 min, at most 30 min or even at most 10 min.
  • a staging period of time could be at least about 5 min, at least 30 min, at least 60 min, or even at least 120 min to allow the adhesive composition to reach a degree of cure (DoC) of at most 10 %, at most 30 %, at most 50 % or even at most 70 % before ramping up to the cure temperature.
  • DoC degree of cure
  • the cure temperature is selected depending on the desired glass transition temperature of the cured fiber reinforced polymer composition.
  • the cure temperature could be about 250 °C or less, or about 180 °C or less, or even 150 °C or less.
  • the fiber reinforced polymer composition could be kept at the cure temperature until a DoC of at least 80 % or even at least 90 % is attained.
  • Snap cure adhesive compositions could allow the snap-curing period of time to reach 90 % degree DoC in at most 60 min, at most 30 min, at most 10 min, or even at most 5 min.
  • the ratio of the curing period of time to the staging period of time is at least about 0.1.
  • Another embodiment of the invention relates a manufacturing method for a molded composite article comprising: (1) placing one of the above reinforced polymer compositions between a tool surface and a flexible material; (2) enclosing the fiber reinforced polymer composition in a pressurized chamber; (3) heating the reinforced polymer composition from a starting temperature to a cure temperature by circulating a first heated pressurized fluid in the tool and circulating a second heated pressurized fluid in the pressurized chamber, and (4) increasing the temperature of the first fluid at a heating rate ri and the second fluid at a heating rate r 2 , wherein rj and r 2 are at least 5 °C/min, wherein the second fluid is similar or different from the first fluid and pressurized greater than atmospheric pressure, wherein the reinforced polymer composition comprises a reinforcing fiber and a snap-cure thermoset adhesive composition, wherein the snap-cure thermoset adhesive composition includes an interlayer toughening material that is localized to layers of the reinforcing fiber, and wherein a set of heating rates
  • a reinforcing fiber, a snap-cure thermoset adhesive composition comprises a thermosetting resin, a curing agent and an accelerator.
  • the fiber reinforced polymer composition might further comprise an interlayer toughener, a thermoplastic resin, a filler or a combination thereof.
  • the reinforced polymer composition may be heated by circulating a first heated pressurized fluid in the tool and/or circulating a second heated pressurized fluid in a pressurized chamber from an ambient condition or a starting temperature to a cure temperature, wherein the second fluid can be similar or different from the first fluid and pressurized greater than atmospheric pressure, wherein the heating rate ri of the first fluid and the heating rate r 2 of the second fluid are at least 5 °C/min, at least 10 °C/min, or even at least 20 °C/min and v ⁇ could be greater than, lesser than or equal to r 2 , wherein a suitable set of the heating rates, the cure temperature, compaction pressure from the second fluid, and time could be applied such that a cure cycle time of at most 5 hr and a void content of at most 2 % are achieved.
  • At least one of the fiber reinforced polymer compositions, the tooling material, the flexible material, the bagging material, and the caul plate material is capable of being heated up at a rate of at least 5 °C/min by a material or a heat medium in contact therewith.
  • Tooling materials for the tool could be metals, metal alloys, composites, or a combination thereof.
  • Selection of a tooling material could depend on its heat absorption characteristic of the tooling material from the heated first fluid and its heat transfer rate to the fiber reinforced polymer composition.
  • Aluminum tools, invar tools, nickel shell tools are some suitable examples.
  • other available methods in the state of the art could be used to heat the tool. Examples of such methods include multizone heating by induction (Roctool, US 8657595 B2 and US 20120070526 Al) and multizone heating by a fluid from electrical heaters (Surface Generation Ltd., US
  • Another embodiment relates to a manufacturing method for a molded void-free composite article comprising at least one of the aforementioned fiber reinforced polymer compositions by heating the reinforced polymer composition in a mold at a rate of at least at least 10 °C/min from an ambient condition or a starting temperature to a cure temperature under a compaction pressure at least 20 psi, wherein the cure cycle time is at most 2 hr.
  • One embodiment of the present invention relates to a manufacturing method to combine fibers and resin matrix (adhesive composition) to produce a curable fiber reinforced polymer composition (sometimes referred to as a "prepreg") which is subsequently cured to produce a composite article.
  • a curable fiber reinforced polymer composition sometimes referred to as a "prepreg"
  • employable is a wet method in which a plurality of reinforcing fibers is soaked in a bath of the resin matrix dissolved in a solvent such as methyl ethyl ketone or methanol, and withdrawn from the bath to remove solvent.
  • a solvent such as methyl ethyl ketone or methanol
  • Another suitable method is a hot melt method, where an adhesive composition is heated to lower its viscosity, directly applied to the reinforcing fibers to obtain a resin-impregnated prepreg; or alternatively, as another method, the adhesive composition is coated on a release paper to obtain a thin film. The film is consolidated onto both surfaces of a sheet of reinforcing fibers by heat and pressure.
  • Comparative Examples 1 -2 and Examples 1 -3 show the effects of fast ramp over cure cycle time and use of processing parameters to achieve void-free laminate.
  • the prepreg system did not contain an interlayer toughening material.
  • T700G-31 fiber was used.
  • Some of the hot mixture was degassed in a planetary mixer rotating at 1500 rpm for a total of 20 min, and poured into a metal mold with a 0.25 in. thick Teflon ® insert.
  • the resin was heated to the cure temperature of 180 °C with a ramp rate of 1.7 °C/min, and dwell at the cure temperature for 2 hr before cooled back down to room temperature.
  • the hot resin was first cast into a thin film using a knife coater onto a release paper.
  • the film was consolidated onto a bed of fibers on both sides by heat and compaction pressure.
  • the prepregs were cut and hand laid up with the sequence listed in Table 2 for each type of mechanical test, according to an ASTM procedure. Panels were cured by a specific method as shown in Table 1 for either autoclave (AC), vacuum bag (VB), low pressure rapidclave (LR) or high pressure rapidclave (HR).
  • the AC method herein and thereafter is used as the reference method for comparison of cure cycle time, void content and performance from other methods.
  • Comparative Examples 3-5 and Examples 4-6 show the effects of applying high compaction pressure to achieve void-free laminate and cure cycle time when an interlayer toughening material was present. T800S-10 fiber was used.
  • FAW was 190 g/m , and the cure temperature was 180 C.
  • Comparative Examples 6-7 and Examples 7-10 show the effects of applying high compaction pressure to achieve void-free laminate and cure cycle time when an interlayer toughening material was present.
  • T800S-10 fiber was used.
  • the resin, prepreg, and mechanical evaluations were performed using procedures as in previous Comparative Example 3.
  • One notable difference was that an accelerator was used to reduce cycle time. As shown, though cure cycle time could be reduced versus similar cases without an accelerator as seen in Comparative Examples 6-7, void content remained the same or worse for Comparative Example 7 with a compaction pressure of 14.7 psi and high ramp rate of 21 °C/min.
  • Comparative Example 8 and Example 11 Comparative Example 9 and Example 12 show the effects of applying high compaction pressure to achieve void-free laminate and cure cycle time when an interlayer toughening material was not present, but more reactive curing agents were used. T700G-31 fiber was used.
  • Percent translation is a measure of how effectively a fiber's strength is utilized in a fiber reinforced polymer composite. It was calculated from the equation below, where a measured tensile strength (TS) is normalized by a measured strand strength of fibers and fiber volume fracture (V f ) in the fiber reinforced polymer composite. Note that V f can be determined from an acid digestion method.

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Abstract

La présente invention concerne une composition polymère renforcée par fibres. L'invention concerne également un ensemble de paramètres de traitement, qui convient pour traiter la composition polymère renforcée par fibres afin de fabriquer un article composite sans vide, à un débit rapide et qui présente des performances similaires à un article durci dans un autoclave. La technologie de fabrication composite utilise des débits rapides de chauffage/refroidissement et des technologies de matériaux permettant non seulement l'absorption de transferts thermiques rapides et un équilibre adapté entre la cinétique de durcissement et les caractéristiques d'écoulement, mais également d'excellentes performances thermiques et mécaniques de l'article composite, équivalant aux propriétés d'un article durci en autoclave ou les dépassant. Le processus est applicable à des pièces en polymère renforcées par fibres, actuellement fabriquées à partir d'un autoclave, mais qui exigent des rythmes de production plus rapides.
PCT/IB2014/001617 2013-06-07 2014-06-05 Composition polymère renforcée par fibres permettant une fabrication composite sans vide, à cycle rapide WO2014195799A2 (fr)

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DE102017113595A1 (de) * 2017-06-20 2018-12-20 Siempelkamp Maschinen- Und Anlagenbau Gmbh Verfahren und Vorrichtung zum Herstellen eines Bauteils aus einem Faserverbundwerkstoff
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US20230191722A1 (en) * 2021-12-17 2023-06-22 Rohr, Inc. Systems and methods for thermoplastic panel manufacturing

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CN115725157B (zh) * 2022-12-29 2023-12-08 西安交通大学城市学院 一种质轻高强度的碳纤维复合材料及其制备方法

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