Prepreg and layered product

Abstract

Provided is a prepreg which contains components [A] to [D], and in which an outer layer comprising component [A] and component [C] is disposed on both surfaces of an inner layer containing component [A] and component [B]. In a cross section in an out-of-plane direction, at least 60 area% of component [C] is included in the outer layer, and component [D] is disposed on one surface or both surfaces thereof. Component [A]: A thermosetting resin composition. Component [B]: Reinforcing fibers. Component [C]: Organic or inorganic particles. Component [D]: A non-woven fabric comprising a thermoplastic elastomer.　Provided are the prepreg and a layered product in which flame retardancy and vibration damping properties are improved and which are suitable for imparting a fiber-reinforced composite material with good adhesive properties between a vibration damping material and a resin.

Description

Prepregs and Laminates

[0001] The present invention relates to a prepreg and a laminate.

[0002] Composite materials, which use reinforcing fibers such as carbon fibers or glass fibers and a thermosetting resin such as epoxy resin or phenolic resin as a matrix resin, are used in a wide range of applications, from sports and leisure goods such as fishing rods and tennis and badminton rackets to various industrial equipment, civil engineering and construction, and aerospace. Mechanical properties such as strength and elastic modulus have traditionally been important for these composite materials in terms of weight reduction, and they have been particularly well-suited for use as structural materials for aircraft and vehicles. However, as the use of composite materials has expanded, additional functionalities such as flame retardancy, vibration damping, heat conductivity, and electrical conductivity have also become increasingly desirable.

[0003] Methods for making composite materials flame retardant include a method of promoting char formation in the matrix resin to suppress the diffusion of decomposition gases when the resin thermally decomposes, a method of suppressing heat generation when the resin burns, and a method of suppressing decomposition of the resin at the early stage of combustion by the heat absorption effect of an inorganic filler containing a heat-absorbing agent.

[0004] To promote char formation in matrix resins, additives that make the material less flammable, commonly known as flame retardants, are often added. Phosphorus compounds are commonly used as flame retardants, and several phosphorus compounds are industrially utilized. It is believed that phosphorus compounds convert to polyphosphoric acid, which has a dehydrating and carbonizing effect, during combustion, thereby promoting char formation. Flame retardant technologies using such phosphorus compounds include the addition of additive-type flame retardants such as red phosphorus or phosphate esters to epoxy resin compositions, and the introduction of phosphorus atoms into the crosslinked structure of the resin by using reactive flame retardants that contain phosphorus atoms in their molecules and react with the resin.

[0005] Patent Document 1 reports a technique for imparting flame retardancy without deteriorating mechanical properties by localizing a flame retardant filler in the vicinity of the outermost layer of a composite material.

[0006] Furthermore, as a means for improving the vibration damping properties of composite materials, there is a technique for converting the vibration energy of the material into thermal energy by using a vibration damping material in the form of particles or nonwoven fabric.

[0007] Patent Document 2 reports a technology for improving vibration damping properties without reducing the rigidity and strength of a composite material by localizing urethane particles having a three-dimensional crosslinked structure with a defined tan δ as a vibration damping material.

[0008] Patent Document 3 introduces a technology for improving vibration damping properties without reducing the rigidity and strength of a composite material by disposing a thermoplastic elastomer nonwoven fabric with a specified tan δ as a vibration damping material.

[0009] Patent Document 4 reports a technique for improving vibration damping properties by arranging a continuous sheet of vulcanized rubber or the like as a vibration damping material.

[0010] International Publication No. 2022 / 154041 International Publication No. 2011 / 122631 International Publication No. 2012 / 011487 Special Publication No. 2016-514632

[0011] However, when the functionality-improving measures described in these patent documents are used, the flame retardancy or vibration-damping properties are insufficient, making it difficult to meet the demand for both flame retardancy and vibration-damping properties in aerospace composite materials. For example, in the invention described in Patent Document 3, a layer of a second epoxy resin composition containing a thermoplastic elastomer nonwoven fabric is provided on one or both sides of a first epoxy resin composition impregnated into reinforcing fibers. However, in this case, if the second epoxy resin composition contains particles, the nonwoven fabric and the particles are mixed together, making it difficult to exhibit the inherent vibration-damping properties of the nonwoven fabric or the inherent functionality of the particles. The inventions described in the other patent documents mentioned above have faced challenges in improving the adhesion between the vibration-damping material and the resin, and in localizing the vibration-damping material, which are required to obtain composite materials with sufficient vibration-damping properties.

[0012] Therefore, an object of the present invention is to solve the above problems, that is, to provide a prepreg and a laminate suitable for providing a fiber-reinforced composite material that has both improved flame retardancy and vibration damping properties and good adhesion between the vibration damping material and the resin.

[0013] 1. A prepreg comprising components [A] to [D], in which outer layers consisting of components [A] and [C] are disposed on both sides of an inner layer containing components [A] and [B], and in the cross section in the out-of-plane direction, 60% or more by area of ​​component [C] is contained in the outer layers, and further comprising component [D] disposed on one or both sides. [A] Thermosetting resin composition [B] Reinforcing fibers [C] Organic or inorganic particles [D] Nonwoven fabric made of a thermoplastic elastomer 2. The air permeability of component [D] is 30 cc / cm ２ / sec or more 400cc / cm ２ / sec or less. 3. The prepreg according to above 1 or 2, wherein the thickness of the outer layer is 6 to 30 μm. 4. The prepreg according to any one of above 1 to 3, wherein the average particle size of component [C] is larger than the fiber diameter of component [B]. 5. The prepreg according to any one of above 1 to 4, wherein the average particle size of component [C] is larger than the opening diameter of component [D]. 6. The basis weight of component [D] is 5 to 30 g / m ２ 7. A laminate comprising components [A] to [E], wherein a layer 1 comprising component [A] and component [B] and a layer 2 comprising component [A] and component [C] are laminated together, component [D] is present between any adjacent layers 2, and a layer 3 comprising component [A], component [B], and component [E] is present as the outermost layer. [A] thermosetting resin composition [B] reinforcing fibers [C] organic or inorganic particles [D] nonwoven fabric comprising a thermoplastic elastomer [E] flame retardant 8. The air permeability of component [D] is 30 cc / cm ２ / sec or more 400cc / cm ２ / sec or less. 9. The laminate according to the above 7 or 8, wherein the ratio of the thickness of layer 3 to the thickness of the portion excluding layer 3 is 1:5 to 1:1. 10. The laminate according to any one of the above 7 to 9, wherein the average particle size of component [C] is larger than the fiber diameter of component [B]. 11. The laminate according to any one of the above 7 to 10, wherein the average particle size of component [C] is larger than the opening size of component [D]. 12. The laminate according to any one of the above 7 to 11, wherein the average particle size of component [E] is larger than the opening size of component [D]. 13. The basis weight of component [D] is 5 to 30 g / m ２ 13. The laminate according to any one of claims 7 to 12, wherein

[0014] The present invention makes it possible to provide a prepreg and a laminate suitable for obtaining a fiber-reinforced composite material having excellent flame retardancy and vibration damping properties.

[0015] In the prepreg of the present invention, component [A] is a thermosetting resin composition. Examples of thermosetting resins include phenolic resins, epoxy resins, cyanate resins, maleimide resins, and benzoxazine resins. Among these, epoxy resins are preferred in terms of mechanical properties and adhesiveness.

[0016] The epoxy resin is not particularly limited, and one or more types can be selected from bisphenol-type epoxy resins, amine-type epoxy resins, phenol novolac-type epoxy resins, cresol novolac-type epoxy resins, resorcinol-type epoxy resins, phenol aralkyl-type epoxy resins, dicyclopentadiene-type epoxy resins, epoxy resins having a biphenyl skeleton, urethane-modified epoxy resins, isocyanate-modified epoxy resins, and the like.

[0017] Examples of bisphenol type epoxy resins include bisphenol type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD ​​type epoxy resin, and bisphenol S type epoxy resin. Examples of amine-type epoxy resins include N,N,N',N'-tetraglycidyl-4,4'-methylenedianiline, N,N,N',N'-tetraglycidyl-2,2'-diethyl-4,4'-methylenedianiline, N,N,N',N'-tetraglycidyl-m-xylylenediamine, N,N-diglycidylaniline, N,N-diglycidyl-4-phenoxyaniline, N,N-diglycidyl-o-toluidine, N,N-diglycidyl-m-toluidine, N,N-diglycidyl-p-toluidine, N,N-diglycidyl-2,3-xylidine, N,N-diglycidyl-2,4-xylidine, and N,N-diglycidyl-3,4-xylidine.

[0018] In the present invention, a thermoplastic resin can be dissolved in the epoxy resin composition to control the tackiness of the resulting prepreg, control the resin flowability when the thermosetting resin composition is impregnated into the reinforcing fibers, and impart toughness to the resulting fiber-reinforced composite material. Such a thermoplastic resin may be any compound that is soluble in the epoxy resin used at room temperature, but a thermoplastic resin having a polyaryl ether skeleton is preferred. Specific examples include polysulfone, polyphenyl sulfone, polyether sulfone, polyether imide, polyphenylene ether, polyether ether ketone, and polyether ether sulfone. These thermoplastic resins having a polyaryl ether skeleton may be used alone or in combination as appropriate. Among these, polyether sulfone and polyether imide are preferred because they can impart toughness to the resulting fiber-reinforced composite material without reducing its heat resistance or mechanical properties.

[0019] In the present invention, the blending amount of the thermoplastic resin is preferably 5 to 40 parts by mass, more preferably 10 to 35 parts by mass, and even more preferably 14 to 30 parts by mass, relative to 100 parts by mass of the total amount of the thermosetting resin. By setting the blending amount of the thermosetting resin within this range, it is possible to ensure a balance between the viscosity of the thermosetting resin, the tackiness of the resulting prepreg, and the mechanical properties of the resulting fiber-reinforced composite material.

[0020] In the present invention, the thermosetting resin composition may contain component [E]: a flame retardant within a range that does not impair the effects of the present invention. Alternatively, by incorporating a flame retardant only into the resin composition used in the prepreg that is arranged in the outermost layer of the laminate, it is possible to effectively impart flame retardancy to the fiber-reinforced composite material and also to achieve excellent vibration damping properties, as will be described in detail below.

[0021] Component [B] is a reinforcing fiber. Preferred examples of the reinforcing fiber include carbon fiber, graphite fiber, aramid fiber, and glass fiber. Of these, carbon fiber is particularly preferred from the viewpoint of mechanical properties.

[0022] Component [C] is an organic or inorganic particle. Examples of organic particles include rubber particles and thermoplastic resin particles. Polyamide is the most preferred thermoplastic resin particle. Among polyamides, polyamide 12, polyamide 6, polyamide 11, polyamide 66, polyamide 6 / 12 copolymer, and polyamides semi-IPN-formed with an epoxy compound (semi-IPN polyamide) as described in Example 1 of JP-A-1-104624 (KOKAI) are particularly preferred. By using particles composed of semi-IPN-formed polyamides and epoxy resins that provide excellent adhesive strength with epoxy resins, excellent heat resistance and impact resistance can be imparted to prepregs. The shape of these thermoplastic resin particles may be spherical, non-spherical, or porous. However, spherical particles are preferred because they do not reduce the flow characteristics of the resin, provide excellent viscoelasticity, and provide high impact resistance without stress concentration points. Commercially available polyamide particles include SP-500, SP-10, TR-1, TR-2, 842P-48, 842P-80, and "Trepar (registered trademark)" TN (all manufactured by Toray Industries, Inc.), and "Orgasol (registered trademark)" 1002D, 2001UD, 2001EXD, 2002D, 3202D, 3501D, and 3502D (all manufactured by Arkema). These polyamide particles may be used alone or in combination.

[0023] Examples of inorganic particles include particles made of metal oxides, metals, metal hydroxides, minerals, carbon, boron nitride, phosphorus, etc., and these may be used alone or in combination of two or more. Furthermore, the surfaces of inorganic particles may be coated with an organic substance to improve adhesion to resins. Specific examples of metal oxides include zinc oxide, magnesium oxide, alumina, titanium oxide, etc. Specific examples of metals include iron, copper, aluminum, etc. Examples of minerals include silica gel and clay. Examples of carbon include carbon black, carbon nanotubes, graphene, carbon particles, etc.

[0024] The average particle size of component [C] is preferably larger than the fiber diameter of component [B]. Here, the term "average particle size" refers to the volume-average particle size determined using a particle size distribution analyzer based on laser diffraction. Furthermore, the term "fiber diameter" refers to the average diameter calculated from the cross-sectional areas of 20 fibers whose cross sections, measured by radial cross-sectional observation, have a circularity of 0.9 or higher, assuming that the fibers are perfectly circular. If the number of fibers with a circularity of 0.9 or higher obtained is less than 20, the average of these fibers may be used. If no fibers have a circularity of 0.9 or higher, the average diameter of the 20 fibers with the highest circularity may be used. Having an average particle size of component [C] larger than the fiber diameter of component [B] prevents component [C] from penetrating into the reinforcing fiber bundles of component [B], thereby ensuring the interlaminar thickness between adjacent reinforcing fiber bundles. This allows the interlaminar resin to sufficiently penetrate the nonwoven fabric of component [D] during prepreg molding, thereby reducing the amount of voids in the molded fiber-reinforced composite material. The average particle size of component [C] is more preferably at least twice the fiber diameter of component [B]. On the other hand, if the average particle size of component [C] is too large, the thickness of the outer layer may become too large, resulting in a deterioration in mechanical properties. Therefore, it is preferably no more than 10 times the fiber diameter of component [B]. Furthermore, the average particle size of component [C] is preferably larger than the opening diameter of component [D] described below. By having the average particle size of component [C] larger than the opening diameter of component [D], it is possible to prevent component [C] from penetrating into the nonwoven fabric of component [D], thereby enabling the development of an excellent vibration-damping effect. The average particle size of component [C] is more preferably at least twice the opening diameter of component [D]. On the other hand, if the average particle size of component [C] is too large, the thickness of the outer layer may become too large, resulting in a deterioration in mechanical properties. Therefore, it is preferably no more than 10 times the opening diameter of component [D].

[0025] The content of component [C]: organic or inorganic particles is preferably 3 to 20 parts by mass, where the total mass of the thermosetting resin composition of component [A] and component [C] contained in the prepreg of the present invention is taken as 100. If the content of component [C] is less than 3 parts by mass, the interlayer thickness may not be sufficiently ensured. On the other hand, if the content exceeds 20 parts by mass, the viscosity of the resin composition may become too high, resulting in poor processability, or the adhesion between the reinforcing fibers and the resin composition may decrease, resulting in poor mechanical properties.

[0026] In the present invention, component [D] is a nonwoven fabric made of a thermoplastic elastomer. Here, a thermoplastic elastomer is an elastomer that softens from a rubbery state when heated and returns to its rubbery state when cooled. The term "nonwoven fabric" refers to a fabric-like material in which fibers in a thin-layer fiber assembly (web) are bonded together by chemical or mechanical methods (such as adhesive bonding, fusion, or envelopment) without spinning, weaving, or braiding. The inclusion of component [D] in the form of a nonwoven fabric can provide a fiber-reinforced composite material with excellent rigidity, strength, and vibration damping properties. Examples of thermoplastic elastomers that can be used include polystyrene-based thermoplastic elastomers, polyolefin-based thermoplastic elastomers, polyvinyl chloride-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, polyester-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, ionomer-based thermoplastic elastomers, and fluorine-based thermoplastic elastomers. Among these, from the viewpoint of adhesiveness to epoxy resins, polyamide-based thermoplastic elastomers having a polyamide structure and a polyether structure, or polyester-based thermoplastic elastomers having a polyester structure and a polyether structure are preferred. As the structure of the polyester-based thermoplastic elastomer, a block copolymer having a crystalline hard segment and an amorphous soft segment is preferred in that it has a high melting point, mechanical properties, heat resistance, vibration damping properties, and high impact absorption properties.

[0027] Since component [D] is placed on the surface of the outer layer by, for example, adhering it to the surface, it is not contained in the resin composition at the prepreg stage, although it is acceptable for some of the fibers constituting component [D] to penetrate into the resin of the outer layer.

[0028] The nonwoven fabric of component [D] has an air permeability of 30 cc / cm as measured by the Frazier method of JIS L1913 (2010). ２ / sec or more 400cc / cm ２ / sec. It is preferable that the air permeability is less than 30 cc / cm. ２ If the air permeability is less than 400 cc / cm, the resin will not easily penetrate into the nonwoven fabric, which will result in voids and a decrease in mechanical properties. Furthermore, if the resin does not sufficiently penetrate into the nonwoven fabric, the adhesive strength between the resin and the nonwoven fabric will decrease, which may cause peeling and a decrease in vibration damping effect. ２ If the flow rate is more than 45 cc / cm, the resin may penetrate excessively into the nonwoven fabric, which may reduce the vibration damping effect. ２ / sec or more 100cc / cm ２ It is presumed that if the time is less than 1 / sec, the adhesiveness and mechanical properties between the resin and the nonwoven fabric will be optimal.

[0029] The melting point of the material constituting the nonwoven fabric of component [D] is preferably 180°C or higher but lower than 250°C. It is more preferably 200°C or higher but lower than 230°C. If the melting point of the material constituting the nonwoven fabric is lower than 180°C, the nonwoven fabric may melt and mix with and become compatible with the resin during molding of the prepreg, resulting in a decrease in vibration damping effect. On the other hand, if the melting point of the material is higher than 250°C, it is thought that the adhesion between the resin and the nonwoven fabric may decrease.

[0030] The nonwoven fabric of component [D] has a basis weight of 5 to 30 g / m ２ More preferably, it is 10 to 25 g / m ２ The weight of the nonwoven fabric is 5 g / m ２ If the weight per unit area of ​​the nonwoven fabric is less than 30 g / m, the resulting fiber-reinforced composite material may not exhibit sufficient vibration-damping properties. ２If the tensile strength exceeds 100%, the resulting fiber-reinforced composite material will have excellent vibration-damping properties, but will tend to have reduced rigidity and strength.

[0031] The nonwoven fabric of component [D] preferably has an opening diameter of 0.5 to 20 μm, more preferably 1 to 5 μm. The opening diameter is determined by measuring the area A (μm ２ ) and then take the average of the values ​​obtained from the following formula for all apertures.

[0032] Opening diameter (μm) = 2 x (A / π) １／２ If the opening size is less than 0.5 μm, the resin will not sufficiently penetrate into the nonwoven fabric, which may reduce the adhesion between the resin and the nonwoven fabric and reduce the vibration-damping effect.On the other hand, if the opening size of the nonwoven fabric exceeds 20 μm, the particles of component [C] and particles of component [E] will be more likely to penetrate into the nonwoven fabric, which may reduce the vibration-damping effect.

[0033] In the prepreg of the present invention, outer layers made of component [A] and component [C] are disposed on both sides of an inner layer containing component [A] and component [B], and in the out-of-plane cross section, the outer layers contain 60 area% or more of the component [C] contained in the entire prepreg, and component [D] is disposed on one or both sides of the outer layers. Preferably, the outer layers contain 98 area% or more of the component [C] contained in the entire prepreg. If the amount of component [C] contained in the outer layers is less than 60 area% of the component [C] contained in the entire prepreg, the resin of component [A] is likely to migrate to the inner layer during curing, resulting in insufficient adhesion between the nonwoven fabric made of the thermoplastic elastomer of component [D] and the resin of the layer, and sufficient vibration damping properties may not be obtained. Regarding the outer layer, the layer consisting of component [A] and component [C] is a layer containing only component [A] and component [C], but the outer layer may contain additives other than component [C] as long as they do not impair the effects of the present invention, and such additives are considered to be contained in the composition of component [A]. The same applies to "Layer 2" described below.

[0034] The method for producing the prepreg of the present invention comprises three steps.

[0035] In the first step, component [A] is impregnated into reinforcing fibers to obtain a prepreg precursor 1. That is, component [A] is used as a matrix resin, and this component [A] is composited with reinforcing fibers to form the inner layer of the prepreg.

[0036] In the second step, films composed of component [A] and component [C] are attached to both sides of prepreg precursor 1 to obtain prepreg precursor 2. The films may be applied to a release sheet, for example, so that the resin side of the film is attached to both sides of precursor 1 as a resin film with a release sheet. That is, the above-mentioned component [A] is compounded with [C] to form a film, which is then attached to both sides of prepreg precursor 1 to form outer layers.

[0037] In the third step, a nonwoven fabric made of component [D], a thermoplastic elastomer, is attached to one or both surfaces of the prepreg precursor 2 to obtain the desired prepreg.

[0038] In the prepreg of the present invention, the thickness of the outer layer is preferably 6 to 30 μm. It is more preferably 10 to 16 μm. If the thickness of the outer layer is less than 6 μm, the adhesion between the nonwoven fabric made of the thermoplastic elastomer of component [D] and the resin of the outer layer may be insufficient, and sufficient vibration damping properties may not be obtained. On the other hand, if the thickness of the outer layer exceeds 30 μm, the amount of resin relative to the entire prepreg is too high, and this may result in a deterioration in flame retardancy.

[0039] In the prepreg of the present invention, the weight of the reinforcing fiber is 100 to 1000 g / m ２ It is preferable that the reinforcing fiber basis weight is 100 g / m ２ If the weight of the reinforcing fibers is less than 1000 g / m, it is necessary to increase the number of layers to obtain a predetermined thickness when molding the fiber-reinforced composite material, which may make the layering work complicated. ２If the fiber mass content exceeds this range, the drapeability of the prepreg tends to deteriorate. The fiber mass content in the prepreg is preferably 40 to 90% by mass, and more preferably 50 to 80% by mass. If the fiber mass content is less than 40% by mass, the resin ratio is high, which may prevent the advantages of the excellent mechanical properties of the reinforcing fibers from being fully utilized, and the heat generated during curing of the fiber-reinforced composite material may be too high. If the fiber mass content exceeds 90% by mass, impregnation with the resin may be insufficient, resulting in a fiber-reinforced composite material with many voids.

[0040] The prepreg of the present invention may be in the form of a unidirectional (UD) prepreg, a woven fabric prepreg, or a nonwoven fabric such as a sheet molding compound.

[0041] The laminate produced using the prepreg of the present invention can be produced by laminating the prepregs in a predetermined shape and applying heat and pressure to cure the matrix resin. Known methods for applying heat and pressure include press molding, autoclave molding, wrapping tape molding, and internal pressure molding.

[0042] The laminate of the present invention contains components [A] to [E], and is a laminate in which multiple layers 1 containing components [A] and [B] and layers 2 containing components [A] and [C] are laminated together, with component [D] present somewhere between adjacent layers 2, and layer 3 containing components [A], [B], and [E] as the outermost layer. Here, with regard to layer 2, the layer containing components [A] and [C] refers to a layer containing only components [A] and [C]. However, by heating or other operations, some of the reinforcing fibers of component [B] contained in layer 1 may be included in layer 2. In the above prepreg, the inner layer containing components [A] and [B] corresponds to layer 1, and the layers containing only components [A] and [C], including the outer layers, correspond to layer 2. Furthermore, among the prepregs containing component [A], component [B], and component [E], only the one positioned as the outermost layer in the laminate is considered to be layer 3, and the other layers, even if they contain component [E], are considered to be layer 1.

[0043] Component [E] is a flame retardant. Examples of flame retardants include phosphate esters, ammonium polyphosphate, red phosphorus, aluminum hydroxide, magnesium hydroxide, and zinc borate. Among these, red phosphorus is preferably used because it has a high phosphorus content and exhibits excellent flame retardancy. The flame retardant may exist in the resin in multiple forms, including flakes, particles, or other forms, as a component insoluble in the resin, or may exist dissolved in the resin.

[0044] In the present invention, when component [E] is present in particulate form, it is preferable that the average particle size of component [E] is larger than the pore size of component [D]. Having an average particle size of component [E] larger than the pore size of component [D] makes it possible to prevent component [E] from penetrating into the interior of the nonwoven fabric of component [D], thereby enabling the development of an excellent vibration-damping effect. It is more preferable that the average particle size of component [E] is at least twice the pore size of component [D]. On the other hand, if the average particle size of component [E] is too large, the thickness of the outer layer may become too large, resulting in a decrease in mechanical properties. Therefore, it is preferable that the average particle size of component [E] is no more than 10 times the pore size of component [D].

[0045] The content of component [E] is preferably 1 to 30 parts by mass relative to 100 parts by mass of the thermosetting resin. It is more preferably 5 to 20 parts by mass. If the content is less than 1 part by mass, the flame retardancy of the fiber-reinforced composite material tends to decrease. On the other hand, if the content is more than 30 parts by mass, the mechanical properties of the fiber-reinforced composite material tend to decrease.

[0046] In the laminate of the present invention, the ratio of the thickness of Layer 3 to the thickness of the portion excluding Layer 3 is preferably 1:5 to 1:1. Here, the thickness of Layer 3 refers to the total thickness of multiple Layers 3 when there are multiple Layers 3. If the thickness of Layer 3 is smaller than the ratio of 1:5, sufficient flame retardancy may not be obtained. On the other hand, if the thickness of Layer 3 is larger than the ratio of 1:1, the mechanical properties may be reduced.

[0047] The upper and lower limits of the above-mentioned ranges can be combined in any way.

[0048] The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0049] The materials used in the examples and comparative examples of the present invention are as follows:

[0050] <Component [A]: Thermosetting Resin Composition> [Epoxy Resin] N,N,N',N'-tetraglycidyl-4,4'-methylenedianiline ("Sumiepoxy (registered trademark)" ELM434, manufactured by Sumitomo Chemical Co., Ltd.) N,N,N',N'-tetraglycidyl-4,4'-methylenedianiline ("Araldite (registered trademark)" MY721, manufactured by Huntsman Advanced Materials) Bisphenol A type epoxy resin ("jER (registered trademark)" 825, manufactured by Mitsubishi Chemical Corporation) Bisphenol A type epoxy resin ("EPON (registered trademark)" 2005, manufactured by HEXION) Carboxyl group-terminated butadiene acrylonitrile rubber (CTBN)-modified bisphenol A type epoxy resin ("HyPOX (registered trademark)" RA95, manufactured by CVC Thermoset Specialities) Bisphenol F type epoxy resin (EPICLON (registered trademark)" 830, manufactured by DIC Corporation) N,N-diglycidyl aniline (GAN, manufactured by Nippon Kayaku Co., Ltd.) [Thermoplastic resin] Polyethersulfone (Sumikaexcel (registered trademark)" PES5003P, manufactured by Sumitomo Chemical Co., Ltd.) Polyethersulfone (VIRANTAGE (registered trademark)" VW-10700RFP, manufactured by Solvay Advanced Polymers) [Curing agent] 4,4'-diaminodiphenyl sulfone (Seikacure S, manufactured by Wakayama Seika Kogyo Co., Ltd.).

[0051] <Component [B]: Reinforcing fiber> Carbon fiber ("Torayca (registered trademark)" T800S, manufactured by Toray Industries, Inc., fiber diameter 4.5 μm) Carbon fiber ("Torayca (registered trademark)" T830H, manufactured by Toray Industries, Inc., fiber diameter 4.4 μm) <Component [C]: Organic or inorganic particles> Polyamide particles ("Trepearl (registered trademark)" TN, manufactured by Toray Industries, Inc., average particle size 13 μm).

[0052] <Component [D]: Nonwoven fabric made of thermoplastic elastomer> Polyester nonwoven fabric (OF-17047 (T-2A), manufactured by Nippon Vilene Co., Ltd., basis weight: 20.5 g / m ２ , melting point: 209°C, air permeability: 47 cc / cm ２ / sec, opening diameter 4.9 μm) Polyester nonwoven fabric (Hytrel (registered trademark) 5520, manufactured by Toray Celanese Co., Ltd., basis weight: 18 g / m ２ , Melting point: 208°C, Air permeability: >412.8cc / cm ２ / sec, aperture diameter 27 μm).

[0053] <Component [E]: Flame retardant> Red phosphorus ("Novared (registered trademark)" 120UF, manufactured by Rinkagaku Kogyo Co., Ltd., average particle size 13 μm).

[0054] (1) Method for preparing thermosetting resin composition [Production Examples 1 and 4] Compounds selected from the above were added to a kneading device in the types and amounts shown in "First, before temperature increase" in Table 1, and the mixture was heated to 140°C or higher and kneaded under heat. The mixture was then cooled to 80°C or lower, and compounds selected from the above were added in the types and amounts shown in "First, after temperature decrease" in Table 1, followed by stirring to obtain a primary thermosetting resin composition.

[0055] Further, compounds selected from the above were added in the types and amounts shown in "Secondary, before temperature increase" in Table 1, and the mixture was heated to 140°C or higher and kneaded under heat. The mixture was then cooled to 80°C or lower, and compounds selected from the above were added in the types and amounts shown in "Secondary, after temperature decrease" in Table 1, followed by stirring to obtain a secondary thermosetting resin composition.

[0056] [Production Examples 2 and 3] Compounds selected from the above were added to a kneading device in the types and amounts shown in "First, before temperature increase" in Table 1, and the temperature was increased to 60°C or higher, followed by heat kneading. Next, compounds selected from the above were added in the types and amounts shown in "First, after temperature decrease" in Table 1, and the mixture was stirred to obtain a primary thermosetting resin composition.

[0057] (2) Prepreg Manufacturing Method [Example 1] The primary resin composition obtained in Manufacturing Example 1 was coated with a knife coater to form a prepreg with a resin basis weight of 37 g / m ２This resin film was set in a prepreg making machine, and a plurality of carbon fibers T800S (191 g / m2) aligned in one direction in a flat shape were used to make a primary resin film. ２ The prepreg precursor 1 (hereinafter referred to as precursor 1) was obtained by overlapping the prepreg precursor 1 on both sides of the prepreg precursor 1 and impregnating the prepreg precursor 1 with the primary resin composition, and then peeling off the release paper.

[0058] Next, the secondary resin composition obtained in Production Example 1 was applied to a sheet having a resin basis weight of 16 g / m using a knife coater. ２ This was coated onto release paper to produce a secondary resin film. This secondary resin film was then laminated onto both sides of precursor 1 to obtain prepreg precursor 2 (hereinafter, precursor 2). Furthermore, after peeling off the release paper, OF-17047 (T-2A) was laminated onto both sides of precursor 2 as component [D] to obtain the target prepreg.

[0059] [Example 2] The target prepreg was obtained in the same manner as in Example 1, except that component [D] was applied to only one side of precursor 2.

[0060] [Reference Example 1] The target prepreg was obtained in the same manner as in Example 1, except that component [D] was not applied.

[0061] [Reference Example 2] The primary resin composition obtained in Production Example 2 was coated with a knife coater to give a resin basis weight of 65 g / m ２ This resin film was set in a prepreg making machine, and unidirectionally aligned carbon fiber T830H (basis weight 196 g / m) was used to make a primary resin film. ２ ) and impregnated with the primary resin composition to obtain the desired prepreg.

[0062] [Reference Example 3] The target prepreg was obtained in the same manner as in Reference Example 2, except that the primary resin composition obtained in Production Example 3 was used instead of the primary resin composition obtained in Production Example 2.

[0063] [Example 3] The primary resin composition obtained in Production Example 4 was coated with a knife coater to a resin basis weight of 32 g / m ２ The secondary resin composition obtained in Production Example 4 was coated on release paper using a knife coater to a resin basis weight of 21 g / m２ The target prepreg was obtained in the same manner as in Example 1, except that the resin was coated on a release paper.

[0064] [Reference Example 4] The target prepreg was obtained in the same manner as in Example 3, except that component [D] was not applied.

[0065] Example 13 The target prepreg was obtained in the same manner as in Example 1, except that component [D] was changed to "Hytrel (registered trademark)" 5520.

[0066] (3) Evaluation of the Content of Component [C] in the Outer Layer Containing Component [A] and Component [C] of the Prepreg Each prepreg prepared in (2) was sandwiched between two smooth Kapton films, heated to 180°C at a heating rate of 1.7°C / min, and cured at 180°C for 2 hours. Separately, the cured product was embedded in an epoxy resin prepared by mixing EpoKwick FC Resin as the base resin and EpoKwick FC Hardener as the curing agent. After curing at 65°C, the cross section at 90° to the fiber axis was wet-polished. The polished cross section was observed using an optical microscope. The content of component [C] in the outer layer containing component [A] and component [C] of the prepreg was determined as the ratio of the area occupied by component [C] in the layer not containing reinforcing fibers to the area occupied by component [C] in the prepreg cross section. The thickness of the outer layer was determined as the average value of the outer layer thickness within a 700 μm length of the cross section of the prepreg.

[0067] (4) Manufacturing Method of Composite Material The prepregs prepared in (2) were laminated as in the Examples and Comparative Examples described later, and then heated in an autoclave at a temperature of 180°C for 2 hours under a pressure of 6 kg / cm. ２ The composite material was prepared by molding at a temperature rise rate of 1.7°C / min.

[0068] (5) Evaluation of the Thickness of Layer 3 (Containing Component [E]) and Other Layers in the Laminate The composite material obtained in (4) was embedded in resin, and then a cross section in the direction 90° to the fiber axis was wet polished. The exposed cross section of the composite material was observed using an optical microscope. From the cross-sectional photograph, the thickness of Layer 3 containing Component [E] and the thickness of the other layers were measured, and the thickness ratio was calculated.

[0069] (6) Vibration Damping Evaluation The vibration damping properties of the composite material were evaluated as follows. The composite material prepared in (4) was cut into 10 mm x 90 mm square test specimens with the fiber direction aligned with the longitudinal direction. The test specimens were fixed at one end with a cantilever beam, and impact was applied to generate damped free bending vibrations. The half-life was calculated from the response amplitude. The vibration waveform was obtained using a strain gauge. A strain gauge (KFG-5-120-C1-11L1M2R manufactured by Kyowa Electric Industry Co., Ltd.) was attached to the test specimen at a position 40 mm longitudinally from the free end using CC-33A adhesive. The region extending 35 mm longitudinally from the fixed end of the test specimen was used as the gripping section, with the beam length set to 55 mm ± 2 mm. The response amplitude was measured using a digital oscilloscope. The time when the displacement reached its maximum was designated t = 0, and the time until the amplitude was reduced by half was defined as the half-life. Furthermore, the composite material after the vibration-damping evaluation was observed to check whether or not the nonwoven fabric had peeled off from the resin.

[0070] (7) Flame Retardancy Evaluation The flame retardancy of the composite material was evaluated using the following procedure. The composite material prepared in (4) was cut into a 150 mm x 300 mm square test piece with the fiber direction aligned with the longitudinal direction. Next, the test piece was fixed vertically with its longitudinal direction, and a burner flame was applied to the lower side for 30 seconds. The duration of combustion after the burner was removed was measured and used as an index of flame retardancy. The burner was a six-burner (3.0 mm burner diameter, 10.16 mm burner spacing) manufactured by Koshin Chemical Manufacturing Co., Ltd. The six nozzles of the six-burner were aligned horizontally, with all nozzles horizontally spaced 20 mm from the surface of the test piece, and the vertical center of the burner nozzles was positioned 55 mm above the bottom edge of the test piece. Propane / butane gas for a cassette cylinder (Asada Multigas A250) was used as fuel for the burner. A flow meter was installed between the burner and the cylinder, and the flow rate was adjusted to 0.1 mL / min. The flame length was set to 25 mm.

[0071] In the following examples, the fiber direction of the carbon fibers in each layer of the laminate was the same. For ease of understanding, in Table 3, except for Examples 10 and 12, the parts where the laminate structure was changed from the base example (for example, Examples 5 and 6 are based on Example 4, and Example 7 is based on Example 6) are marked with a star.

[0072] Example 4: Using the prepregs prepared in (2), the prepreg laminate shown in Table 3 was prepared, with a total of two layers of nonwoven fabric of component [D]. Prepregs 1 and 5 were laminated last (Layer 3). In this case, the layer containing the reinforcing fiber of component [B] in prepregs 2 to 4 corresponds to Layer 1, and the resin layer between Layer 1 and the adjacent Layer 1 corresponds to Layer 2 (in Prepregs 2 and 3, the "outer layer" formed by the secondary resin composition corresponds to Layer 2, with the nonwoven fabric of component [D] present between them). This laminate was molded using Method (4) to obtain a composite material. The flame retardancy of the resulting composite material was evaluated, and the burn time was 44 seconds.

[0073] [Example 5] The target composite material was obtained in the same manner as in Example 4 (the base example), except that the prepreg of Reference Example 3 was used instead of the prepreg of Reference Example 2. When the flame retardancy of the obtained composite material was evaluated, the burning time was 31 seconds, indicating good flame retardancy. In this example, prepregs 1 and 5, which used the prepreg obtained in Reference Example 3, constituted Layer 3 (the layer containing component [E]).

[0074] Example 6 The prepregs shown in Table 3 were laminated in the same manner as in Example 4, except that a total of four layers of nonwoven fabric of component [D] were arranged. This laminate was molded by method (4) to obtain a composite material. When the vibration-damping properties of the obtained composite material were evaluated, the half-life was 69 milliseconds, demonstrating better vibration-damping properties than Comparative Examples 1 and 2, in which the same type of reinforcing fiber was used in each layer of Prepregs 1 to 5. Furthermore, when the composite material was observed after the vibration-damping evaluation, no peeling of the nonwoven fabric was observed.

[0075] Example 7 The target composite material was obtained in the same manner as in Example 6, except that the prepreg of Reference Example 3 was used instead of the prepreg of Reference Example 2. When the vibration-damping properties of the obtained composite material were evaluated, the half-life was 63 milliseconds, indicating better vibration-damping properties than those of Comparative Examples 1 and 2. Furthermore, when the composite material was observed after the vibration-damping evaluation, no peeling of the nonwoven fabric was observed.

[0076] Example 8 The prepregs prepared in (2) were used to prepare the prepreg laminate configuration shown in Table 3. The nonwoven fabric of component [D] was laminated on both sides of prepreg 2 and both sides of prepreg 4, resulting in a total of four layers. This laminate was molded using the method in (4) to obtain a composite material. The flame retardancy of the obtained composite material was evaluated, revealing a burning time of 9.25 seconds, demonstrating good flame retardancy. Furthermore, the vibration damping property was evaluated, revealing a half-life of 47 milliseconds, demonstrating good vibration damping property. Furthermore, after the vibration damping property evaluation, the composite material was observed, and no peeling of the nonwoven fabric was observed. In this example, all of prepregs 1 to 5 contain component [E], but prepregs 1 and 5, which are the outermost layers, correspond to layer 3.

[0077] Example 9 A composite material was obtained in the same manner as in Example 8, except that the prepreg prepared in (2) was used and the nonwoven fabric of component [D] was laminated in a total of two layers to form the prepreg laminate shown in Table 3. The flame retardancy of the obtained composite material was evaluated, and the burning time was 4 seconds, indicating good flame retardancy. Furthermore, the vibration damping property was evaluated, and the half-life was 57 milliseconds, indicating good vibration damping property. Furthermore, when the composite material was observed after the vibration damping property evaluation, no peeling of the nonwoven fabric was observed. In this example, all of prepregs 1 to 5 were layers containing component [E], but prepregs 1 and 5, which were located in the outermost layers, corresponded to layer 3.

[0078] [Example 10] A composite material was obtained in the same manner as in Example 8, except that the prepreg prepared in (2) was used to form the prepreg laminate configuration shown in Table 3. When the vibration-damping properties of the obtained composite material were evaluated, the half-life was 49 milliseconds, indicating good vibration-damping properties. Furthermore, when the composite material was observed after the vibration-damping evaluation, no peeling of the nonwoven fabric was observed.

[0079] Example 11 A composite material was obtained in the same manner as in Example 10, except that the prepreg prepared in (2) was used and the nonwoven fabric of component [D] was laminated so that a total of two layers were arranged, as shown in Table 3. The vibration-damping properties of the obtained composite material were evaluated, and the half-life was 49 milliseconds, indicating good vibration-damping properties. Furthermore, no peeling of the composite nonwoven fabric was observed after the vibration-damping property evaluation.

[0080] Example 12 A composite material was obtained in the same manner as in Example 10, except that the prepregs prepared in (2) were used to form the prepreg laminate shown in Table 3, and the nonwoven fabric of component [D] was laminated in two layers, one on the underside of prepreg 1 (the side facing prepreg 2) and one on the top side of prepreg 5 (the side facing prepreg 4). The vibration-damping properties of the resulting composite material were evaluated, revealing a half-life of 58 milliseconds, indicating good vibration-damping properties. Furthermore, no peeling of the composite nonwoven fabric was observed after the vibration-damping evaluation.

[0081] Example 14 A composite material was obtained in the same manner as in Example 6, except that the prepregs prepared in (2) were used to form the prepreg laminate shown in Table 3, and the prepregs 2 and 4 were the prepregs of Example 13. When the vibration-damping properties of the obtained composite material were evaluated, the half-life was 74 milliseconds, which was inferior to that of Example 6 in which OF-17047 (T-2A) was used as component [D], but the vibration-damping properties were better than those of Comparative Example 1 which did not contain component [D]. Furthermore, no peeling of the composite nonwoven fabric was observed after the vibration-damping property evaluation.

[0082] Comparative Example 1 A composite material was obtained in the same manner as in Example 4, except that the prepreg laminate shown in Table 3 did not further contain component [D].

[0083] The flame retardancy of the resulting composite material was evaluated, and the burning time was 45 seconds. Furthermore, the vibration-damping property was evaluated, and although no peeling of the composite nonwoven fabric was observed after the vibration-damping property evaluation, the half-life was 81 milliseconds, indicating poor vibration-damping property.

[0084] Comparative Example 2 A composite material was obtained in the same manner as in Example 5, except that the prepreg laminate shown in Table 3 did not further contain component [D].

[0085] After the vibration-damping evaluation, the composite material was observed and no peeling of the nonwoven fabric was observed. However, the half-life was 74 milliseconds, indicating low vibration-damping properties.

[0086] Comparative Example 3 A composite material was obtained in the same manner as in Example 9, except that the prepreg lamination form shown in Table 3 did not contain component [D].

[0087] The flame retardancy of the resulting composite material was evaluated, and the burning time was 2.5 seconds, indicating good flame retardancy. After the vibration-damping evaluation, the composite material was observed, and no peeling of the nonwoven fabric was observed. However, the half-life was 69 milliseconds, indicating poor vibration-damping. In this example, all of prepregs 1 to 5 contain component [E], but the outermost prepregs 1 and 5 correspond to layer 3.

[0088] Comparative Example 4 A composite material was obtained in the same manner as in Example 11, except that the prepreg lamination form shown in Table 3 did not contain component [D].

[0089] The flame retardancy of the resulting composite material was evaluated, and the burning time was 18.25 seconds, indicating low flame retardancy. After the vibration-damping evaluation, the composite material was observed, and no peeling of the nonwoven fabric was observed, but the half-life was 66 milliseconds, indicating low vibration-damping ability.

[0090]

[0091]

[0092]

Claims

1. A prepreg comprising components [A] to [D], with outer layers consisting of components [A] and [C] disposed on both sides of an inner layer containing components [A] and [B], with component [C] accounting for 60% or more by area in the cross section in the out-of-plane direction of the outer layers, and with component [D] disposed on one or both sides. [A] Thermosetting resin composition [B] Reinforcing fiber [C] Organic or inorganic particles [D] Nonwoven fabric made of a thermoplastic elastomer 2. The air permeability of component [D] is 30 cc / cm ２ / sec or more 400cc / cm ２ The prepreg according to claim 1, wherein the elongation is less than 1 / sec.

3. The prepreg according to claim 1 or 2, wherein the thickness of the outer layer is 6 to 30 μm.

4. The prepreg according to claim 1 or 2, wherein the average particle size of component [C] is larger than the fiber diameter of component [B].

5. The prepreg according to claim 1 or 2, wherein the average particle size of component [C] is larger than the opening size of component [D].

6. The basis weight of component [D] is 5 to 30 g / m ２ The prepreg according to claim 1 or 2, 7. A laminate comprising components [A] to [E], in which a layer 1 comprising components [A] and [B] and a layer 2 comprising components [A] and [C] are laminated together, component [D] is present between any of the adjacent layers 2, and a layer 3 comprising components [A], [B], and [E] is present as the outermost layer. [A] Thermosetting resin composition [B] Reinforcing fibers [C] Organic or inorganic particles [D] Nonwoven fabric comprising a thermoplastic elastomer [E] Flame retardant 8. The air permeability of component [D] is 30 cc / cm ２ / sec or more 400cc / cm ２ The laminate of claim 7, wherein the elongation is less than 1 / sec.

9. The laminate according to claim 7 or 8, wherein the ratio of the thickness of layer 3 to the thickness of the portion excluding layer 3 is 1:5 to 1:

1.

10. The laminate according to claim 7 or 8, wherein the average particle size of component [C] is larger than the fiber diameter of component [B].

11. The laminate according to claim 7 or 8, wherein the average particle size of component [C] is larger than the opening size of component [D].

12. The laminate according to claim 7 or 8, wherein the average particle size of component [E] is larger than the opening size of component [D].

13. The basis weight of component [D] is 5 to 30 g / m ２ The laminate according to claim 7 or 8,