Multilayer composite material with nonwoven fabric reinforcement

Abstract

An embodiment of the present disclosure relates to a multi-layer thermoset composite including a first fabric reinforced layer, a nonwoven fabric, and a second fabric reinforced layer. The nonwoven fabric may be disposed between the first fabric reinforced layer and the second fabric reinforced layer. The thermoset resin may at least partially permeate the first fabric reinforced layer, the nonwoven fabric, and the second fabric reinforced layer. The thermoset resin may be an epoxy, an unsaturated polyester, or a polyurethane. The first and second fabric reinforced layers may each include one or more of glass fibers, carbon fibers, polyaramid fibers, polyethylene fibers, or basalt fibers. The nonwoven fabric may be formed from bicomponent fibers having a sheath / core configuration. The sheath may be formed from an ethylene-carboxylic acid copolymer, or an ionomer of an ethylene-carboxylic acid copolymer. Further embodiments include a method of making a multi-layer thermoset composite.

Description

[Technical Field]

[0001] Embodiments of this disclosure generally relate to multilayer composite materials, and more specifically to thermosetting multilayer composite structures having a nonwoven fabric layer. [Background technology]

[0002] Thermosetting composites generally exhibit high strength, low density, and high rigidity. Therefore, they are widely used in aircraft, aerospace, automobiles, high-speed rail, wind turbine blades, sporting goods, high-pressure gas tanks, and many other applications requiring high strength and low weight. However, they are often extremely brittle. Consequently, many composite materials, particularly laminated fabrics, often have insufficient impact resistance in the thickness direction.

[0003] The most common failure mode for thermosetting composites is considered to be delamination between layers. Since the layers are generally bonded to each other only by resin, the reinforcement of the composite in the thickness direction is insufficient. Without reinforcement, cracks rapidly propagate through the cross-linked resin after impact, leading to delamination.

[0004] Various methods have been used to reinforce thermosetting composites. For example, three-dimensional weaving, Z-pinning, weft knitting, and three-dimensional woven fabrics have all been attempted. However, these technologies increase the complexity and cost of the composite manufacturing process.

[0005] Therefore, there is still a need for composite structures that can provide sufficient impact strength across all axes without increasing manufacturing complexity. [Overview of the project]

[0006] Embodiments of the present disclosure address this need by providing a multilayer thermosetting composite comprising a nonwoven fabric reinforcement layer, a plurality of fabric reinforcement layers, and a thermosetting resin at least partially impregnated into these layers. Embodiments further address a method for producing the multilayer thermosetting composite of the present disclosure. These thermosetting composites offer improved mechanical properties, particularly transverse impact strength, compared to conventional composites.

[0007] In one embodiment, the multilayer thermosetting composite may include a first fabric reinforcement layer, a nonwoven fabric, and a second fabric reinforcement layer. The nonwoven fabric may be placed between the first and second fabric reinforcement layers. The thermosetting resin may at least partially permeate the first fabric reinforcement layer, the nonwoven fabric, and the second fabric reinforcement layer. The thermosetting resin may be epoxy, unsaturated polyester, or polyurethane. The first fabric reinforcement layer may include one or more of glass fibers, carbon fibers, polyaramid fibers, polyethylene fibers, or basalt fibers. The second fabric reinforcement layer may include one or more of glass fibers, carbon fibers, polyaramid fibers, polyethylene fibers, or basalt fibers. The nonwoven fabric may be formed from two-component fibers having a sheath / core structure. The sheath may be formed from an ethylene-carboxylic acid copolymer or an ionomer of an ethylene-carboxylic acid copolymer.

[0008] In another embodiment, a process for forming a thermosetting composite includes at least partially impregnating a dry multilayer composite with a thermosetting resin to form a wet uncured composite, and curing the wet uncured composite to form a thermosetting composite. The dry multilayer composite may include a first fabric reinforcement layer, a nonwoven fabric, and a second fabric reinforcement layer. The first fabric reinforcement layer may include one or more of glass fibers, carbon fibers, polyaramid fibers, polyethylene fibers, or basalt fibers. The second fabric reinforcement layer may include one or more of glass fibers, carbon fibers, polyaramid fibers, polyethylene fibers, or basalt fibers. The nonwoven fabric may be formed from two-component fibers having a sheath / core structure, the sheath being formed from an ethylene-carboxylic acid copolymer or an ionomer of an ethylene-carboxylic acid copolymer.

[0009] Additional features and advantages of the embodiments will be described in the following detailed description, some of which will be readily apparent to those skilled in the art from that description, or will be recognized by implementing the embodiments, claims, and accompanying drawings described herein, including the following "Modes for Carrying Out the Invention."

[0010] It should be understood that both the above and below descriptions are intended to illustrate various embodiments and to provide an overview or framework for understanding the nature and features of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments and are incorporated herein and constitute part of this specification. [Brief explanation of the drawing]

[0011] The following “Modes for Carrying Out the Invention” of specific embodiments of this disclosure will be best understood in conjunction with the following drawings, in which similar structures are shown with similar reference numerals.

[0012] [Figure 1] This is a schematic diagram of a thermosetting composite material according to one or more embodiments of the present disclosure. [Figure 2] This is a schematic diagram of a thermosetting composite material according to a further embodiment of the present invention. [Modes for carrying out the invention]

[0013] Embodiments of this disclosure address the need for impact strength across all axes by providing multilayer thermosetting composites and methods for producing such composites. These composites may comprise a nonwoven fabric, multiple fabric reinforcement layers, and a thermosetting resin. While not theoretically bound, it is conceivable that reactive groups on the fibers of the nonwoven fabric may react with the thermosetting resin, resulting in a stronger bond compared to a nonwoven fabric without reactive groups.

[0014] definition As used herein, the terms “comprising,” “including,” and “having,” and their derivatives, are not intended to exclude the existence of any additional components, processes, or procedures, whether or not they are specifically disclosed. To avoid any doubt, all compositions claimed through the use of the term “comprising” may include any additional additives, adjuvants, or compounds, whether polymeric or otherwise, unless otherwise stated. In contrast, the term “consisting essentially of” excludes any other components, processes, or procedures from the scope of any subsequent description, except those not essential to the operability. The term “consisting of” excludes any components, processes, or procedures not specifically described or listed.

[0015] As used herein, the term "ionomer" refers to a polymer compound having at least several ionic groups, ionizable groups, or both.

[0016] The term "polymer" refers to polymer compounds prepared by polymerizing monomers, whether identical or different in type. Therefore, the general term "polymer" encompasses the terms "homopolymer" and "copolymer." The term "homopolymer" refers to a polymer prepared from only one monomer, while the term "copolymer" refers to a polymer prepared from two or more different monomers, and for the purposes of this disclosure, may include "terpolymer" and "interpolymer." Trace amounts of impurities (e.g., catalyst residue) may be incorporated into and / or within the polymer. The polymer may be a single polymer or a polymer blend.

[0017] When used in this specification, "gsm" and "g / m" are used. 2" means grams per square meter, "min." / "mins." means minutes, "hr." / "hrs." means hours, "sec." means seconds, "mol." means moles, "mol.%" means mole percent, "wt.%" means weight percent, "mbar" means millibar, "MPa" means megapascal, "kJ / m 2 " means kilojoules per square meter, "g / cm 3 " means grams per cubic centimeter, "in." means inches, "°C" means degrees Celsius, "mm" means millimeters, "S / m" means Siemens per meter, "μm" means micrometers, "cP" means centipoises.

[0018] Embodiments Referring now to FIG. 1, the multilayer thermosetting composite 100 may include a first fabric reinforcing layer 120, a second fabric reinforcing layer 130, and a non-woven fabric 110 disposed between the first fabric reinforcing layer 120 and the second fabric reinforcing layer 130. The multilayer thermosetting composite 100 may further include a thermosetting resin that at least partially penetrates the first fabric reinforcing layer 120, the non-woven fabric 110, and the second fabric reinforcing layer 130.

[0019] The non-woven fabric 110 may be thermoplastic. A thermosetting multilayer composite including a thermoplastic non-woven fabric layer may be considered to have improved toughness compared to a thermosetting multilayer composite that does not include a thermoplastic non-woven fabric layer.

[0020] The non-woven fabric 110 may be prepared by any type of non-woven fabric manufactured by various techniques. For example, it may be a spunbond non-woven fabric, a meltblown non-woven fabric, a short fiber non-woven fabric, or a flash spun non-woven fabric, etc. According to some exemplary embodiments, the non-woven fabric may be a spunbond non-woven fabric.

[0021] As used herein, “spunbond nonwoven fabric” is a nonwoven fabric prepared in a single continuous process of spinning fibers and then dispersing them directly into a web by either a deflector or an airflow. The spunbond nonwoven fabric may be bonded to a resin thermally or by entanglement.

[0022] As used herein, "penetrate" means to penetrate below the surface of each layer. Therefore, when the thermosetting resin penetrates at least partially into the first fabric reinforcement layer 120, the nonwoven fabric 110, and the second fabric reinforcement layer 130, the resin penetrates below the surface of each of these layers.

[0023] The nonwoven fabric 110 may be placed between the first fabric reinforcement layer 120 and the second fabric reinforcement layer 130. According to some embodiments, the nonwoven fabric 110 may be in direct contact with the first fabric reinforcement layer 120 and the second fabric reinforcement layer 130. According to alternative embodiments, the first fabric reinforcement layer 120 may not be in direct contact with the nonwoven fabric 110. Similarly, the nonwoven fabric 110 may not be in direct contact with the second fabric reinforcement layer 130, i.e., an intervening layer may be present between them. One or more additional layers may be present between the fabric reinforcement layer and the nonwoven fabric 110.

[0024] According to some embodiments, the nonwoven fabric 110 may occupy at least 70%, at least 80%, at least 90%, at least 95%, or at least 99% of the total surface area of ​​the first fabric reinforcement layer 120 and the second fabric reinforcement layer 130. Therefore, the first fabric reinforcement layer 120 does not need to be in contact with the second fabric reinforcement layer 130 over more than 10% of its surface area.

[0025] The nonwoven fabric 110 may be formed from two-component fibers having a sheath / core structure. The term "two-component fiber" may refer to a fiber comprising a pair of polymer compositions tightly bonded to each other along the length of the fiber. The pair of polymer compositions may form a sheath-core structure in cross-section. The two-component sheath-core structure may have a circular, trefoil, pentaphylla, octaphylla, dumbbell, sea-island, or star-shaped cross-section. In all of these configurations, the core may be located internally, surrounded by a sheath, and both may extend substantially along the entire length of the fiber.

[0026] Binary fibers can have an average fiber diameter of 1 μm to 100 μm. For example, binary fibers can have an average fiber diameter of 2 μm to 50 μm, 2 μm to 90 μm, 5 μm to 75 μm, 5 μm to 50 μm, 10 μm to 40 μm, or any subset thereof.

[0027] Two-component fibers may be continuous fibers. The term "continuous fiber" refers to fibers of indeterminate or extreme lengths. In practice, due to manufacturing issues, "continuous fibers" may have one or more breaks, but "continuous fibers" are distinguishable from "short fibers" because short fibers are cut to a predetermined length, while continuous fibers are not. Continuous fibers may have an average fiber length of at least 0.1 inches, at least 0.25 inches, at least 0.5 inches, at least 1 inch, at least 2 inches, at least 3 inches, at least 4 inches, at least 5 inches, or even at least 6 inches.

[0028] The sheath may have a lower melting point than the core. For example, the sheath may have a melting point at least 5°C, at least 10°C, at least 20°C, at least 40°C, or even at least 60°C lower than the melting point of the core.

[0029] Nonwoven fabric 110 has a weight of 10 g / m². 2 ~1000g / m 2 It may have a basis weight. As used herein, "basis weight" refers to the mass per unit surface area of ​​the sheet of material. In some examples, nonwoven fabric 110 has a basis weight of 50 g / m².2 ~1000 g / m 2 、100 g / m 2 ~1000 g / m 2 、10 g / m 2 ~500 g / m 2 、10 g / m 2 ~100 g / m 2 、50 g / m 2 ~100 g / m 2 、10 g / m 2 ~50 g / m 2 、 or may have a basis weight of any subset of these.

[0030] The non-woven fabric 110 may have an average thickness of 0.1 mm to 10 mm. For example, the non-woven fabric 110 may have an average thickness of 0.1 mm to 8 mm, 0.1 mm to 5 mm, 0.1 mm to 1 mm, 1 mm to 10 mm, 1 mm to 5 mm, 3 mm to 8 mm, or any subset of these.

[0031] To achieve a preferred thickness, the non-woven fabric 110 may include multiple layers of the non-woven fabric 110. For example, the non-woven fabric 110 may include at least 1, 2, 3, 4, 5, 10, 15, 20, or more than 20 layers of the non-woven fabric 110. The layers of the non-woven fabric 110 may be hot-pressed together before being combined into a thermosetting multilayer composite, or may simply be placed on top of each other.

[0032] The non-woven fabric 110 may include bicomponent fibers. The bicomponent fibers may include a sheath and a core. The sheath of the bicomponent fibers can be formed from an ethylene-carboxylic acid copolymer or an ionomer of an ethylene-carboxylic acid copolymer. The core of the bicomponent fibers can be formed from a polyamide.

[0033] The two-component fiber may be a sheath of 10% to 60% by weight. For example, the two-component fiber may be 10% to 50% by weight, 10% to 40% by weight, 10% to 30% by weight, 20% to 60% by weight, 20% to 50% by weight, 20% to 40% by weight, 30% to 60% by weight, 30% to 50% by weight, 30% to 45% by weight, 40% to 50% by weight, or any subset thereof.

[0034] The sheath of the two-component fiber may contain at least 80% by weight of an ethylene-carboxylic acid copolymer or its ionomer. For example, the sheath may contain at least 85% by weight, at least 90% by weight, at least 95% by weight, at least 99% by weight, or even more than 99.99% by weight of an ethylene-carboxylic acid copolymer or its ionomer.

[0035] In some embodiments, the carboxylic acid may be acrylic acid or methacrylic acid. In some exemplary embodiments, the carboxylic acid is methacrylic acid. The sheath of the two-component fiber may contain 70% to 99% by weight of ethylene monomer. It should be understood that the “ethylene monomer” may be incorporated into polymers such as ethylene-carboxylic acid copolymers or their ionomers. For example, the sheath may contain 80% to 99% by weight, 70% to 90% by weight, 80% to 90% by weight, 90% to 99% by weight, or any subset thereof of ethylene monomer.

[0036] Various acid content is intended for ethylene-carboxylic acid copolymers or ionomers of ethylene-carboxylic acid copolymers. For example, ethylene-carboxylic acid copolymers or ionomers of ethylene-carboxylic acid copolymers may have acid content of 1% to 20% by weight, 1% to 15% by weight, 1% to 10% by weight, 1% to 5% by weight, 5% to 20% by weight, 5% to 15% by weight, 5% to 10% by weight, 10% to 20% by weight, 10% to 15% by weight, 15% to 20% by weight, or any subset thereof.

[0037] At least some of the acidic groups of the ethylene-carboxylic acid copolymer or its ionomer may be neutralized. According to some embodiments, these acidic groups may be neutralized with cations such as Zn cations, Na cations, K cations, Ca cations, Mg cations, or combinations thereof.

[0038] Various cation neutralization levels of the sheath are intended. For example, the sheath may have cation neutralization levels ranging from 0.1 mol% to 60 mol%. As used herein, the “cation neutralization level” of the sheath refers to the percentage of acid groups in the sheath that are neutralized by cations. It should be understood that the moles referred to when calculating “mol%” are the moles of acid groups. In some embodiments, the sheath may have cation neutralization levels ranging from 1 mol% to 60 mol%, 5 mol% to 60 mol%, 10 mol% to 60 mol%, 20 mol% to 60 mol%, 40 mol% to 60 mol%, 0.1 mol% to 60 mol%, 0.1 mol% to 40 mol%, 0.1 mol% to 20 mol%, 0.1 mol% to 10 mol%, 0.1 mol% to 1 mol%, 5 mol% to 50 mol%, 10 mol% to 40 mol%, 10 mol% to 30 mol%, or any subset thereof.

[0039] Ethylene-carboxylic acid copolymers, or their ionomers, may have melt flow rates (MFRs) ranging from 12 g / 10 min to 60 g / 10 min. For example, the MFR may be 12 g / 10 min to 45 g / 10 min, 12 g / 10 min to 30 g / 10 min, 20 g / 10 min to 60 g / 10 min, 20 g / 10 min to 40 g / 10 min, 40 g / 10 min to 60 g / 10 min, or any subset thereof. The MFR may be measured at 190°C and a 2160 g load according to ASTM D1238. Higher melt flow rates within a specific range are thought to enable easier processing.

[0040] A suitable ionomer of ethylene / carboxylic acid copolymer is SURLYN® ionomer resin, available from Dow, Inc. (Midland, MI).

[0041] Ionomers can have densities of 0.950 to 0.980 g / cc. For example, ionomers can have densities of 0.950 to 0.970 g / cc, 0.950 to 0.960 g / cc, 0.960 to 0.980 g / cc, 0.960 to 0.970 g / cc, 0.970 to 0.980 g / cc, or any combination thereof.

[0042] While not bound by theory, it is believed that the acidic reactive groups in the sheath of the two-component fiber improve the interfacial bonding energy, thereby improving the reinforcing performance. In contrast, standard polyester, polyamide, and polypropylene nonwovens lack these reactive groups and therefore have insufficient bonding strength with this resin.

[0043] The core of a two-component fiber may contain a polyamide. The polyamide may be a polymer containing repeating amide (-CONH-) groups. For example, the core of a two-component fiber may contain one or more of the following: polyamide 6, polyamide 11, polyamide 12, polyamide 66, polyamide 610, polyamide 612, polyamide 66 / 610, polyamide 666, polyamide 6 / 69, nylon 1010, nylon 1012, PA 6T, or blends thereof. A commercially available polyamide is Zytel® resin, available from DuPont.

[0044] The sheath and / or core of the two-component fiber may contain other additives. For example, the sheath and / or core may contain dyes, pigments, antioxidants, UV stabilizers, spin finishers, and other conventional additives.

[0045] While not bound by theory, it is conceivable that a nonwoven fabric 110 constructed from a single component, such as an ethylene-carboxylic acid copolymer or its ionomer, would lack sufficient mechanical strength to serve its intended purpose, especially at high temperatures. However, the two-component nonwoven fabric of the present invention is believed to provide sufficient mechanical strength at both high and low temperatures.

[0046] The spunbond nonwoven fabric 110 may be prepared using a conventional spin bonding method, such as that disclosed in International Publication No. 2019 / 084774.

[0047] The first fabric reinforcement layer 120 may contain one or more of the following: glass fibers, carbon fibers, polyaramid fibers, polyethylene fibers, or basalt fibers. The second fabric reinforcement layer 130 may contain one or more of the following: glass fibers, carbon fibers, polyaramid fibers, polyethylene fibers, or basalt fibers.

[0048] The first and second fabric reinforcement layers 120 and 130 may each independently contain at least 90% by weight, at least 95% by weight, at least 99% by weight, or even more than 99.9% by weight of glass fibers, carbon fibers, polyaramid fibers, polyethylene fibers, or basalt fibers, and any thermosetting resin impregnated into the fabric reinforcement layer.

[0049] The first and second fabric reinforcement layers may have a basis weight of 10 gsm to 10,000 gsm. For example, the first and second fabric reinforcement layers may have weights of 10 gsm to 1,000 gsm, 100 gsm to 10,000 gsm, 100 gsm to 1,000 gsm, or any subset thereof.

[0050] The first and second fabric reinforcement layers may each include a unidirectionally oriented fabric, a biaxially oriented fabric, or both. It should be understood that the first and second fabric reinforcement layers may, but do not need to, include fabrics of the same orientation.

[0051] The fabric reinforcement layer may have an average thickness of 0.1 mm to 10 mm. For example, the fabric reinforcement layer may have an average thickness of 0.1 mm to 8 mm, 0.1 mm to 5 mm, 0.1 mm to 1 mm, 1 mm to 10 mm, 1 mm to 5 mm, 3 mm to 8 mm, or any subset thereof.

[0052] The thermosetting resin can penetrate at least partially into the first fabric reinforcement layer 120, the nonwoven fabric 110, and the second fabric reinforcement layer 130.

[0053] The thermosetting resin may be epoxy, unsaturated polyester, or polyurethane. The resin may be fluid in the temperature range of 23°C to 70°C. For example, the viscosity of the resin at 23°C to 70°C may be 0.1 cP to 1000 cP, 0.1 cP to 500 cP, 0.1 cP to 300 cP, 1 cP to 1000 cP, 1 cP to 800 cP, 1 cP to 500 cP, 1 cP to 300 cP, 10 cP to 1000 cP, 10 cP to 800 cP, 10 cP to 500 cP, 10 cP to 300 cP, 100 cP to 1000 cP, 100 cP to 500 cP, or any subset thereof.

[0054] The first fabric reinforcement layer 120, the nonwoven fabric 110, and the second fabric reinforcement layer 130 may together have a thermosetting resin content of 10% to 50% by weight. For example, the composite material may have a thermosetting resin content of 10-40% by weight, 20-50% by weight, 30-50% by weight, or any subset thereof.

[0055] Thermosetting resins may be curable. Thermosetting resins may be cured thermally, chemically, or both. Thermosetting resins may be cured thermally at temperatures of 40°C to 500°C, 40°C to 100°C, 40°C to 80°C, 60°C to 500°C, 60°C to 100°C, or any subset thereof.

[0056] The multilayer thermosetting composite 100 may further contain a resin curing agent. The resin curing agent reacts with the resin or other components of the multilayer thermosetting composite 100 to accelerate the curing of the resin. The ratio of the weight of the resin to the total weight of the resin and resin curing agent may be 50% to 100% by weight, 60% to 90% by weight, 70% to 80% by weight, or any subset thereof. A suitable combination of resin and curing agent is Airstone® 760 epoxy resin and Airstone® 766® epoxy curing agent (both available from Olin® Epoxy) in a ratio of 100 / 33.

[0057] Referring to Figure 2, the multilayer thermosetting composite material 100 may include additional layers, such as an additional layer of fabric reinforcement. For example, the multilayer thermosetting composite material 100 may include a third fabric reinforcement layer 150. The third fabric reinforcement layer 150 may be located on the opposite side of the nonwoven fabric 110 layer from the first fabric reinforcement layer 120. The third fabric reinforcement layer 150 may have a different fiber orientation than the first fabric reinforcement layer 120.

[0058] The multilayer thermosetting composite material 100 may include a fourth fabric reinforcement layer 140. The fourth reinforcement layer 140 may be located on the opposite side of the nonwoven fabric layer 110 from the second fabric reinforcement layer 130. The fourth fabric reinforcement layer 140 may have a different fiber orientation than the second fabric reinforcement layer 130.

[0059] A process for forming a multilayer thermosetting composite material 100 may include impregnating a dry multilayer composite material with a thermosetting resin at least partially to form a wet uncured composite material, and curing the wet uncured composite material to form a thermosetting composite material. The dry multilayer composite material may include a first fabric reinforcement layer 120, a nonwoven fabric 110, and a second fabric reinforcement layer 130, as described above.

[0060] The process for forming a thermosetting composite may optionally further include pressing a dry multilayer composite to form a dry multilayer composite.

[0061] Impregnating a dry multilayer composite with a thermosetting resin at least partially may include placing the dry multilayer composite into a mold and injecting the thermosetting resin into the mold. Impregnating a dry multilayer composite with a thermosetting resin at least partially may be achieved using resin transfer molding (RTM) or vacuum-assisted resin transfer molding (VARTM).

[0062] Curing a wet, uncured composite may involve heating the wet, uncured composite to at least 50°C over a period of 3 hours. For example, a wet, uncured composite may be cured at a temperature of at least 60°C or at least 70°C for at least 3 hours, at least 4 hours, at least 5 hours, or at least 6 hours.

[0063] The process for forming a thermosetting composite may further include subjecting a wet multilayer composite to a vacuum. The vacuum may be applied before and / or during the curing process. The vacuum may be 0 mbar to 20 mbar, 5 mbar to 20 mbar, 10 mbar to 20 mbar, 0 mbar to 15 mbar, 5 mbar to 15 mbar, or any subset thereof.

[0064] The presence of a vacuum allows the resin to flow across the dry multilayer composite to form a wet multilayer composite. The resin and multilayer composite may then be sealed together in a vacuum bag. The vacuum can also help to push the resin into the multilayer composite.

[0065] Test method Mode I interlaminar fracture toughness (G Ic ) According to ASTM D5528-13, the mode I interlaminar fracture toughness (G) of each composite sheet sample was determined. Ic The following was tested: Samples were tested using a double cantilever beam (DCB) in an INSTRON 5969 Universal test system. The test speed was set to 5 mm / min. The sample size was 125 mm × 25 mm × 4 mm, with one side of the initial delamination of a polyvinylidene fluoride ("PVDF") film (13 μm) inserted into the central layer, and the initial delamination length was approximately 50 mm from the edge. Before testing, the samples were equilibrated in the laboratory at 23°C and 50% relative humidity for over 48 hours. Each recorded measurement is the average of six test specimens.

[0066] Mode I was calculated according to the Modified Beam Theory (MBT) method. The beam theory equation for the strain energy release rate of a fully integrated (i.e., clamped to the delamination front) double cantilever beam is given by Equation 1.

[0067] formula 1

number

[0068] (In the formula,

[0069] P=load,

[0070] δ = displacement at the point of load,

[0071] b = specimen width,

[0072] a = delamination length)

[0073] Mode II interlaminar fracture toughness (G IIc ) The mode II interlaminar fracture toughness (G) of the composite sheet sample was determined using the end-notched flexure (ENF) test, in accordance with ASTM D7905-19. IIc The following was tested: The sample size was 160 mm × 25 mm × 4 mm, with one side of the initial delamination of a PVDF film (13 μm) inserted into the central layer, and the initial delamination length was approximately 50 mm from the edge. Before testing, the samples were equilibrated in the laboratory at 23°C and 50% relative humidity for more than 48 hours. Each recorded measurement is the average of six test specimens. The measurements were calculated using Equation 2.

[0074] formula 2

number

[0075] (In the formula, m is the CC coefficient, P Max(where a0 is the maximum force from the destructive test, a0 is the crack length used in the destructive test, B is the specimen width, and the other variables are as described above).

[0076] Bending strength and elastic modulus Bending strength and modulus of elasticity were measured according to ISO 14125.

[0077] density Density was measured according to ASTM D792.

[0078] Barcol hardness Barcol hardness was measured according to ASTM D2583.

[0079] Meltflow rate MFR was measured at 190°C and under a 2160g load according to ASTM D1238.

[0080] Fiber content The reinforcing fiber content of the entire sample was measured according to ASTM D3171-15, Method A8. [Examples]

[0081] A series of examples and comparative examples of the present invention were prepared according to several embodiments of this disclosure. A list of the raw materials used is shown in Table 1. Unless otherwise specified, all samples were 500 mm × 500 mm sheets. The release film was 250 mm × 500 mm. Release film may be used to ensure that the sample is broken in the appropriate layer during testing. Therefore, although release film was present in the test samples, it is an optional component. [Table 1]

[0082] Embodiment 1 of the present invention (IE1): A series of fabrics were laid in a mold, and the dry multilayer composite material of the present disclosure was formed in the following order. A 1:3 layer biaxial carbon fiber cloth A. 2:2 layer unidirectional carbon fiber fabric B. 3.1-layer ionomer / polyamide nonwoven fabric. 4:1 layer release film. 5:2 layer unidirectional carbon fiber fabric B. A 6:3 layered biaxial carbon fiber fabric A. 7:1 peel-off ply. 8: Flow mesh.

[0083] Comparative example 1 (CE1): Carbon fiber / epoxy composites without nonwoven fabric reinforcement were prepared according to the following method. A series of fabrics were laid in a mold, and a dry multilayer composite was formed in the following order. A 1:3 layer biaxial carbon fiber cloth A. 2:2 layer unidirectional carbon fiber fabric B. 3:1 layer release film. 4:2 layer unidirectional carbon fiber fabric B. A 5:3 layered biaxial carbon fiber fabric A. 6:1 peel-off ply. 7: Flow mesh.

[0084] Example 2 (CE2): A carbon fiber / epoxy composite material having one layer of polyamide nonwoven fabric A as a reinforcing layer was prepared according to the following method. A series of fabrics were laid in a mold, and a dry multilayer composite material was formed in the following order. A 1:3 layer biaxial carbon fiber cloth A. 2:2 layer unidirectional carbon fiber fabric B. 3.1 layer polyamide nonwoven fabric A. 4:1 layer release film. 5:2 layer unidirectional carbon fiber fabric B. A 6:3 layered biaxial carbon fiber fabric A. 7:1 peel-off ply. 8: Flow mesh.

[0085] Comparative Example 3 (CE3): A carbon fiber / epoxy composite material having one layer of polyamide nonwoven fabric B as a reinforcing layer was prepared according to the following method. A series of fabrics were laid in a mold, and a dry multilayer composite material was formed in the following order. A 1:3 layer biaxial carbon fiber cloth A. 2:2 layer unidirectional carbon fiber fabric B. 3.1 layer polyamide nonwoven fabric B. 4:1 layer release film. 5:2 layer unidirectional carbon fiber fabric B. A 6:3 layered biaxial carbon fiber fabric A. 7:1 peel-off ply. 8: Flow mesh.

[0086] Press, seal, and cure A 300mm long injection hose was positioned adjacent to the flow mesh on one side of the sample, with the vacuum outlet on the opposite side. Two loops of an adhesive sealing strip were attached around each layer laid in the mold. The dried multilayer composite was then sealed with two layers of vacuum bag film.

[0087] The resin was transferred to the dry multilayer composite using the VARTM method. Specifically, a vacuum pump was connected to the vacuum outlet, and the system was pressurized to a vacuum of 0-20 mbar. The resin system (Airstone 760 epoxy resin / Airestone 766 epoxy hardener = 100 / 33, resin hardener mixture) was degassed under vacuum for 5 minutes to remove all air bubbles. Once the resin was degassed, it was connected to an injection hose and flowed across the sample surface through a flow mesh using vacuum pressure. The resin inlet was sealed, and the resin was forced into the sample by the pressure difference across the surface of the vacuum bag.

[0088] Once completed, the wet sample was cured by heating at 70°C for 6 hours. After curing, the product was removed from the mold. Auxiliary materials such as release plies and flow mesh were removed, and the laminate was cut into test specimens.

[0089] result. Table 2 discloses the mode I and mode II interlaminar fracture toughness of the examples and comparative examples of the present invention. [Table 2]

[0090] Depending on whether the interlaminar fracture toughness is mode I or mode II, the embodiments of the present invention perform significantly better than the comparative examples. The prominent defects in CE1 under mode I are thought to be caused by the absence of a nonwoven two-component reinforced layer.

[0091] The samples of the present invention and comparative samples showed similar results for other material properties such as density, hardness, flexural strength, and flexural modulus. This indicates that the adverse effects of this composite reinforcement process on other mechanical properties are minimal.

[0092] One exception is the lower flexural strength of sample CE3. The 30% decrease in flexural strength of CE3 compared to CE1 is thought to be due to the excessively dense thermoplastic nonwoven fabric in the composite. This density may cause insufficient penetration of the epoxy resin.

[0093] All documents cited herein, including any cross-referenced or related patents or applications, and any patent applications or patents to which this application claims priority or benefit, are incorporated herein by reference in their entirety unless expressly excluded or otherwise limited. No reference to any document constitutes prior art relating to any invention disclosed or claimed herein, nor does it teach, suggest or disclose such invention, either alone or in any combination with any other reference. Furthermore, if any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in any document incorporated by reference, the meaning or definition assigned to that term in this document shall prevail.

[0094] While specific embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, the appended claims are intended to encompass all such changes and modifications that fall within the scope of the invention. Examples of the inventions of this application include the following: [1] A multilayer thermosetting composite material, A first fabric reinforcement layer comprising one or more of the following: glass fibers, carbon fibers, polyaramid fibers, polyethylene fibers, or basalt fibers, A nonwoven fabric formed from two-component fibers having a sheath / core structure, wherein the sheath is formed from an ethylene-carboxylic acid copolymer or an ionomer of an ethylene-carboxylic acid copolymer, A second fabric reinforcement layer comprising one or more of the following: glass fibers, carbon fibers, polyaramid fibers, polyethylene fibers, or basalt fibers, Includes, The thermosetting resin penetrates at least partially into the first fabric reinforcement layer, the nonwoven fabric, and the second fabric reinforcement layer. The thermosetting resin is epoxy, unsaturated polyester, or polyurethane. A multilayer thermosetting composite material in which the nonwoven fabric is disposed between the first fabric reinforcement layer and the second fabric reinforcement layer. [2] The multilayer thermosetting composite material according to [1] above, wherein the nonwoven fabric is a spunbond nonwoven fabric. [3] The multilayer thermosetting composite material according to [1] or [2] above, wherein the sheath comprises an ionomer of an ethylene-carboxylic acid copolymer having a cation neutralization level of 0.1 mol% to 60 mol%. [4] The multilayer thermosetting composite material according to any one of [1] to [3] above, wherein the sheath is neutralized with Zn cations, Na cations, or both. [5] The multilayer thermosetting composite material according to any one of [1] to [4] above, wherein the ethylene-carboxylic acid copolymer or the ionomer of the ethylene-carboxylic acid copolymer has a carboxylic acid content of 1% to 20% by weight. [6] The multilayer thermosetting composite material according to any one of [1] to [5] above, wherein the ethylene-carboxylic acid copolymer or ionomer of the ethylene-carboxylic acid copolymer has a melt flow rate (MFR) of 12 g / 10 min to 60 g / 10 min when measured at 190 °C and a load of 2160 g according to ASTM D1238. [7] A multilayer thermosetting composite material according to any one of [1] to [6] above, wherein the two-component fibers have an average fiber diameter of 1 μm to 100 μm. [8] The multilayer thermosetting composite material according to any one of [1] to [7] above, wherein the two-component fibers are continuous fibers. [9] A multilayer thermosetting composite material according to any one of [1] to [8] above, wherein the core contains a polyamide.

[10] A process for forming a thermosetting composite, A thermosetting resin is impregnated at least partially into a dry multilayer composite to form a wet, uncured composite, The process includes curing the wet, uncured composite material to form a multilayer thermosetting composite material, wherein the dried multilayer composite material is A first fabric reinforcement layer comprising one or more of the following: glass fibers, carbon fibers, polyaramid fibers, polyethylene fibers, or basalt fibers, A nonwoven fabric formed from two-component fibers having a sheath / core structure, wherein the sheath is formed from an ethylene-carboxylic acid copolymer or an ionomer of an ethylene-carboxylic acid copolymer, A second fabric reinforcement layer comprising one or more of the following: glass fibers, carbon fibers, polyaramid fibers, polyethylene fibers, or basalt fibers, A process that includes this.

[11] The process according to

[10] above, wherein the nonwoven fabric is a spunbond nonwoven fabric.

[12] The process according to

[10] or

[11] , further comprising pressing the dry multilayer composite to form a dry multilayer composite.

[13] Impregnating the dry multilayer composite material with a thermosetting resin at least partially is The process involves placing the aforementioned dried multilayer composite material into a mold, Injecting a crosslinkable liquid resin into the mold, The process described in any of the above

[10] to

[12] , including the process described above.

[14] The process according to any one of

[10] to

[13] above, wherein curing the wet uncured composite material includes heating the wet uncured composite material to at least 50°C over a period of 3 hours.

[15] The process according to any one of

[10] to

[14] above, further comprising subjecting the wet multilayer composite to a vacuum.

Claims

1. A multilayer thermosetting composite material, Glass fiber, carbon fiber, polyaramid fiber, polyethylene fiber, or basalt fiber A first fabric reinforcement layer comprising one or more of the following, Formed from a two-component fiber having a sheath / core structure, the sheath is ethylene-carbon Ingredients formed from ionic acid copolymers or ionomers of ethylene-carboxylic acid copolymers Woven fabric and, Glass fiber, carbon fiber, polyaramid fiber, polyethylene fiber, or basalt fiber A second fabric reinforcement layer including one or more of the following, Includes, The thermosetting resin is present in at least the first fabric reinforcement layer, the nonwoven fabric, and the second fabric reinforcement layer. It has also partially penetrated, The thermosetting resin is epoxy, unsaturated polyester, or polyurethane. The nonwoven fabric is disposed between the first fabric reinforcement layer and the second fabric reinforcement layer. Multilayer thermoset composite.

2. The multilayer thermosetting composite material according to claim 1, wherein the nonwoven fabric is a spunbond nonwoven fabric.

3. The sheath has an ethylene-cation neutralization level of 0.1 mol% to 60 mol%. A multilayer thermosetting composite material according to claim 1 or 2, comprising an ionomer of a rubonate copolymer. 。

4. The claim states that the sheath is neutralized with a Zn cation, a Na cation, or both. A multilayer thermosetting composite material as described in any of 1 to 3.

5. The ethylene-carboxylic acid copolymer, or the ethylene-carboxylic acid copolymer The nomer has a carboxylic acid content of 1% to 20% by weight, any one of claims 1 to 4. The multilayer thermosetting composite material described in [reference].

6. The ethylene-carboxylic acid copolymer, or the ethylene-carboxylic acid copolymer When Nomar measured at 190°C and a load of 2160g according to ASTM D1238 Having a melt flow rate (MFR) of 12 g / 10 min to 60 g / 10 min, claims 1 to A multilayer thermosetting composite material as described in any of item 5.

7. The two-component fiber has an average fiber diameter of 1 μm to 100 μm, according to any of claims 1 to 6. A multilayer thermosetting composite material as described below.

8. The multilayer thermosetting composite according to any one of claims 1 to 7, wherein the two-component fiber is a continuous fiber. Asphalt mixture.

9. The core comprises polyamide, as described in any one of claims 1 to 8. 。

10. A process for forming a thermosetting composite material, A thermosetting resin is impregnated at least partially into the dry multilayer composite material, and the wet, uncured composite material To form, The process includes curing the wet, uncured composite material to form a multilayer thermosetting composite material, The dried multilayer composite material is Glass fiber, carbon fiber, polyaramid fiber, polyethylene fiber, or basalt fiber bag A first fabric reinforcement layer containing one or more of the following, Formed from a two-component fiber having a sheath / core structure, the sheath is made of ethylene-calcium carbonate. Formed from ionomers of ammonium carboxylic acid copolymers or ethylene-carboxylic acid copolymers. Nonwoven fabric and Glass fiber, carbon fiber, polyaramid fiber, polyethylene fiber, or basalt fiber bag A second fabric reinforcement layer containing one or more of the following, A process that includes this.

11. The process according to claim 10, wherein the nonwoven fabric is a spunbond nonwoven fabric.

12. Claim 1 further comprises pressing the dried multilayer composite material to form a dried multilayer composite material. The process described in 0 or 11.

13. The process involves at least partially impregnating the aforementioned dry multilayer composite material with a thermosetting resin. The process involves placing the aforementioned dried multilayer composite material into a mold, Injecting a crosslinkable liquid resin into the mold, The process according to any one of claims 10 to 12, including the process described above.

14. The process of curing the aforementioned wet, uncured composite material involves a minimum of 3 hours of curing the aforementioned wet, uncured composite material. The process according to any one of claims 10 to 13, comprising heating to at least 50°C.

15. The method further comprises subjecting the wet, uncured composite material to a vacuum, as in any one of claims 10 to 14. The process described.

16. Before and / or during the curing process, a vacuum is applied to allow the resin to dry the multilayer composite material horizontally. The process according to any one of claims 10 to 14, further comprising cutting and flowing.

17. The process according to any one of claims 10 to 16, wherein the thermosetting resin is epoxy. vinegar.

18. The multilayer thermosetting composite material according to any one of claims 1 to 9, wherein the thermosetting resin is epoxy.

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