Fiber-reinforced thermoplastic resin substrate

Abstract

In order to provide a fiber-reinforced thermoplastic resin substrate having excellent thermal stability, the present invention provides a fiber-reinforced thermoplastic resin substrate obtained by impregnating a plurality of continuous reinforcing fibers with a polyaryletherketone resin, the total content of alkali metal and alkaline earth metal contained in the fiber-reinforced thermoplastic resin base material is 5 ppm or more and less than 50 ppm.

Description

Technical Field

[0001] The present invention relates to a fiber-reinforced resin substrate, and more particularly to a fiber-reinforced thermoplastic resin substrate comprising a polyaryletherketone resin. Background Art

[0002] Fiber-reinforced resin substrates, made by impregnating multiple continuous reinforcing fibers with thermoplastic resins, not only offer excellent lightweighting effects but also boast superior toughness, weldability, and recyclability compared to fiber-reinforced resin substrates using thermosetting resins. Consequently, they are being widely used in a variety of applications, including aircraft, automobiles, and other transportation equipment, as well as sports, electrical, and electronic components. In recent years, CFRTP (carbon fiber reinforced thermoplastic resin) intermediate substrates have been required to possess high added value, including high heat resistance, low water absorption, high toughness, and moldability, in addition to their traditional value-added mechanical strength and lightweight properties. Consequently, there is a strong demand for the development of high-performance CFRTP intermediate substrate technologies, primarily for aircraft, UAM (Urban Air Mobility), and automotive applications.

[0003] Polyaryletherketone (PAEK) resin is a crystalline thermoplastic resin with excellent heat and chemical resistance, and has attracted particular attention as a matrix resin for composite materials. However, fiber-reinforced PAEK resin matrices require processing at temperatures exceeding 300°C when manufacturing molded products. This leads to issues such as thickening and changes in thermal properties due to impurities in the fiber-reinforced PAEK resin matrix, resulting in a demand for composite materials with even better heat resistance and moldability.

[0004] Patent Document 1 discloses a method for producing a fiber-reinforced PAEK resin matrix having excellent impregnation properties, wherein an alkali metal salt or an alkaline earth metal salt is blended into the fiber-reinforced PAEK resin matrix in an amount of 0.005 wt % (50 ppm) or more relative to the PAEK resin.

[0005] Patent Document 2 discloses a highly crystalline fiber-reinforced polyetherketoneketone resin substrate having a total aluminum, phosphorus, and sodium content of 100 ppm or less.

[0006] Patent Document 3 discloses a method for producing a fiber-reinforced PAEK resin substrate having excellent thermal stability using a thermally stable surfactant containing sodium.

[0007] Patent Document 4 discloses a fiber-reinforced thermoplastic resin substrate having excellent processability and containing 0.2 to 3.2 wt % of an alkali metal salt or an alkaline earth metal salt.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Laid-Open No. 59-207929

[0011] Patent Document 2: International Publication No. 2020 / 213406

[0012] Patent Document 3: Japanese Patent Application No. 2020-513052

[0013] Patent Document 4: Japanese Patent Application Laid-Open No. 2022-91563 Summary of the Invention

[0014] Problems to be solved by the invention

[0015] The method proposed in Patent Document 1 produces a fiber-reinforced PAEK resin matrix with excellent impregnation properties. However, the addition of alkali metals and alkaline earth metals at a content of 50 ppm or more causes changes in molecular weight and crystallinity upon heating and cooling, posing a problem in process stability during the manufacture of molded products.

[0016] Patent Document 2 describes that by limiting the combined content of aluminum, phosphorus, and sodium to 100 ppm or less, a fiber-reinforced polyetherketoneketone resin matrix exhibits high crystallinity. However, the content of the alkaline earth metal salt is not specifically disclosed, and stability against the molding temperature is required. Furthermore, since the resin is produced using a sulfuric acid-based reprecipitation purification method, there are challenges in process stability, safety, operability, and economic efficiency during the production of molded products.

[0017] Patent Document 3 discloses a method for producing a fiber-reinforced PAEK resin substrate having excellent thermal stability by using a thermally stable surfactant containing sodium. Specifically, the method describes a substrate having a weight-average molecular weight change of 20% or less when heated at 375°C for 20 minutes under a nitrogen atmosphere. However, a fiber-reinforced PAEK resin substrate having even greater thermal stability is desired, and the content of alkali metals and alkaline earth metals in the fiber-reinforced PAEK resin substrate is not specifically disclosed.

[0018] Patent Document 4 discloses a fiber-reinforced thermoplastic resin matrix with excellent processability containing 0.2 to 3.2 wt% of an alkali metal salt or alkaline earth metal salt. However, there is no specific disclosure regarding a fiber-reinforced PAEK resin matrix with excellent thermal stability or the alkali metal and alkaline earth metal content in the fiber-reinforced PAEK resin matrix.

[0019] Thus, conventional technologies have insufficient thermal stability for fiber-reinforced PAEK resin substrates. The present invention provides a fiber-reinforced PAEK resin substrate having excellent thermal stability, process stability during component manufacturing, and excellent molding cycle performance.

[0020] Means for solving problems

[0021] The present invention for solving the above-mentioned problems has any of the following configurations.

[0022] [1] A fiber-reinforced thermoplastic resin substrate, wherein the fiber-reinforced thermoplastic resin substrate is obtained by impregnating a plurality of continuous reinforcing fibers with a polyaryletherketone resin, wherein the total content of alkali metals and alkaline earth metals contained in the fiber-reinforced thermoplastic resin substrate is 5 ppm or more and less than 50 ppm.

[0023] [2] The fiber-reinforced thermoplastic resin substrate according to [1], wherein the alkali metal in the fiber-reinforced thermoplastic resin substrate is sodium or potassium.

[0024] [3] The fiber-reinforced thermoplastic resin substrate according to [1] or [2], wherein the alkaline earth metal in the fiber-reinforced thermoplastic resin substrate is calcium or magnesium.

[0025] [4] The fiber-reinforced thermoplastic resin substrate according to any one of [1] to [3], wherein the temperature drop crystallization temperature change ΔTc measured after the fiber-reinforced thermoplastic resin substrate is treated under the following conditions is 0°C or more and 2°C or less.

[0026] Treatment conditions: 380°C × 30 min, nitrogen atmosphere

[0027] [5] The fiber-reinforced thermoplastic resin substrate according to any one of [1] to [4], wherein the weight average molecular weight change rate ΔMw of the polyaryletherketone resin when the fiber-reinforced thermoplastic resin substrate is treated under the following conditions is 25% or less.

[0028] Treatment conditions: 380°C × 30 min, nitrogen atmosphere

[0029] [6] The fiber-reinforced thermoplastic resin substrate according to any one of [1] to [5], wherein the polyaryletherketone resin in the fiber-reinforced thermoplastic resin substrate is a polyaryletherketone resin selected from the group consisting of polyetherketone, polyetheretherketone, polyetherketoneketone, polyetheretherketoneketone, polyetherketoneetherketoneketone, polyetheretherketoneetherketone, polyetheretheretherketone, polyetherdiphenyletherketone, and mixtures thereof, copolymers thereof, and copolymers thereof with other polyaryletherketone resins.

[0030] Effects of the Invention

[0031] The present invention improves the thermal stability of a fiber-reinforced thermoplastic resin substrate using a PAEK resin as a matrix resin by controlling the combined content of alkali metals and alkaline earth metals within a specific range. This improves the thermal stability of the PAEK resin substrate, which requires high-temperature processing. Consequently, it is possible to provide a fiber-reinforced PAEK resin substrate (prepreg) that exhibits excellent process stability and molding cycle performance during component manufacturing. DETAILED DESCRIPTION

[0032] Hereinafter, embodiments of the present invention will be described in detail.

[0033] <Reinforcement Fiber>

[0034] The type of reinforcing fiber is not particularly limited, and examples thereof include carbon fiber, metal fiber, organic fiber, and inorganic fiber. Two or more of these may be used. By using carbon fiber as the reinforcing fiber, a fiber-reinforced resin substrate having light weight and high mechanical properties can be obtained.

[0035] Examples of carbon fibers include polyacrylonitrile (PAN)-based carbon fibers made from polyacrylonitrile (PAN) fibers, pitch-based carbon fibers made from petroleum tar or petroleum pitch, cellulose-based carbon fibers made from viscose rayon or cellulose acetate, vapor-grown carbon fibers made from hydrocarbons, and graphitized fibers thereof. Among these carbon fibers, PAN-based carbon fibers are preferably used due to their excellent balance between strength and elastic modulus.

[0036] Examples of the metal fibers include fibers made of metals such as iron, gold, silver, copper, aluminum, brass, and stainless steel.

[0037] Examples of organic fibers include fibers made of organic materials such as aramid, polybenzoxazole (PBO), polyphenylene sulfide, polyester, polyamide, and polyethylene. Examples of aramid fibers include para-aramid fibers, which have excellent strength and elastic modulus, and meta-aramid fibers, which have excellent flame retardancy and long-term heat resistance. Examples of para-aramid fibers include poly(p-phenylene terephthalamide) fibers and copoly(p-phenylene-3,4'-oxydiphenylene terephthalamide) fibers, while examples of meta-aramid fibers include poly(m-phenylene isophthalamide) fibers. Para-aramid fibers, which have a higher elastic modulus than meta-aramid fibers, are preferably used as aramid fibers.

[0038] Examples of inorganic fibers include fibers made of inorganic materials such as glass, basalt, silicon carbide, and silicon nitride. Examples of glass fibers include E-glass fibers (for electrical use), C-glass fibers (for corrosion resistance), S-glass fibers, and T-glass fibers (high strength, high elastic modulus). Basalt fibers are fibers obtained by fiberizing basalt, a mineral, and are fibers with very high heat resistance. Basalt generally contains 9 to 25% by weight of FeO or FeO2, which are iron compounds, and 1 to 6% by weight of TiO or TiO2, which are titanium compounds. However, these components can also be increased in amount and fiberized in a molten state.

[0039] The fiber-reinforced thermoplastic resin substrate of the present invention is a prepreg and is often expected to function as a reinforcing material. Therefore, it is expected to exhibit high mechanical properties. In order to exhibit high mechanical properties, it is preferred to include carbon fibers as reinforcing fibers.

[0040] In the fiber-reinforced thermoplastic resin substrate of the present invention, the reinforcing fibers are usually used by arranging one or more reinforcing fiber bundles (which are formed by bundling multiple single fibers). The total number of filaments of the reinforcing fibers (the number of single fibers) when arranging one or more reinforcing fiber bundles is preferably 1,000 to 2,000,000. From the perspective of productivity, the total number of filaments of the reinforcing fibers is more preferably 1,000 to 1,000,000, further preferably 1,000 to 600,000, and particularly preferably 1,000 to 300,000. The upper limit of the total number of filaments of the reinforcing fibers can be determined by taking into account the balance in a manner that maintains good productivity, dispersibility, and operability.

[0041] The reinforcing fiber bundle of the present invention preferably has an average diameter of 5 to 10 μm and is composed of 1,000 to 50,000 reinforcing fibers bundled together. The reinforcing fiber bundle is impregnated with a polyaryletherketone resin composition as a matrix resin.

[0042] In the present invention, continuous reinforcing fibers refer to fibers that are not interrupted in the longitudinal direction of the fibers in a fiber-reinforced thermoplastic resin matrix. Examples of the morphology and arrangement of the reinforcing fibers in embodiments of the present invention include unidirectionally aligned reinforcing fibers, woven fabrics (cloths), knitted fabrics, braids, and tows. However, unidirectional alignment of the reinforcing fibers is preferred from the perspective of effectively improving mechanical properties in a specific direction.

[0043] <Polyaryletherketone resin>

[0044] As described above, the reinforcing fibers are impregnated with a polyaryletherketone resin (PAEK resin). The polyaryletherketone resin used in the present invention is not particularly limited as long as it is a thermoplastic resin having repeating units in which an aryl group is bonded to an ether group and a ketone group, but is preferably a polymer having units represented by the following general formula (Ia) and general formula (Ib).

[0045] [Chemical Formula 1]

[0046]

[0047] Here, Ar 1 and Ar 2 Each represents an arylene group. 1 and Ar 2 Can be the same or different. 1 and Ar 2 Preferably, each independently represents one or more arylene groups selected from the group consisting of 1,3-phenylene, 1,4-phenylene, 4,4'-biphenylene, 1,4-bis(4-phenoxybenzoyl)phenylene, 1,4-naphthylene, 1,5-naphthylene, 2,6-naphthylene, and anthracene. X represents an electron withdrawing group. X is preferably one or more groups selected from the group consisting of a carbonyl group and a sulfonyl group. Y is one or more groups selected from the group consisting of an oxygen atom, a sulfur atom, and an alkylene group. Y is preferably one or more groups selected from the group consisting of -CH2-, isopropylidene, and hexafluoroisopropylidene.

[0048] In these structural units, preferably at least 50 mol% of X, more preferably at least 70 mol% of X, are carbonyl groups. Also, preferably at least 50 mol% of Y, more preferably at least 70 mol% of Y, are oxygen atoms.

[0049] Examples of the polyaryletherketone include polyetheretherketones having a structural unit of the following formula (II) and / or a structural unit of the following formula (III), polyetherketones having a structural unit of the following formula (IV), polyetherketoneketones having a structural unit of the following formula (V) and / or a structural unit of the following formula (VI), polyetheretherketoneketones having a structural unit of the following formula (VII), and polyetherketoneetherketoneketones having a structural unit of the following formula (VIII). These may be used alone or in combination of two or more.

[0050] [Chemical Formula 2]

[0051]

[0052] The polyaryletherketone resin used in the present invention is not particularly limited and may be selected from the group consisting of polyetherketone (PEK), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyetheretherketoneketone (PEEKK), polyetherketoneetherketoneketone (PEKEKK), polyetheretherketoneetherketone (PEEKEK), polyetheretheretherketone (PEEEK), polyetherdiphenyletherketone (PEDEK), and mixtures thereof, copolymers thereof, and copolymers thereof with other PAEK resins. For example, commercially available products such as "VESTAKEEP (registered trademark)" manufactured by Polyplastics-Evonik Corporation, "VICTREX (registered trademark)" manufactured by Victrex Japan Inc., "KEPSTAN (registered trademark)" manufactured by Arkema Co., Ltd., and "AvaSpire (registered trademark)", "KetaSpire (registered trademark)", and "NovaSpire (registered trademark)" manufactured by Solvay Specialty Polymers Japan Co., Ltd. can also be used. Among the above-mentioned group, materials other than PEKK are preferred from the viewpoint of molding processability.

[0053] <Fiber-reinforced thermoplastic resin base material>

[0054] The fiber-reinforced thermoplastic resin substrate of the present invention is a fiber-reinforced PAEK resin substrate obtained by impregnating continuous reinforcing fibers with a polyaryletherketone resin, and is a thermoplastic prepreg containing a PAEK resin as a matrix resin.

[0055] In the present invention, the combined metal content of alkali metals and alkaline earth metals contained in the fiber-reinforced thermoplastic resin substrate is 5 ppm or more and less than 50 ppm. If this combined metal content is 50 ppm or more, the thermal stability of the fiber-reinforced thermoplastic resin substrate decreases, leading to reduced process stability and molding cycle performance during component manufacturing. On the other hand, if this combined metal content is less than 5 ppm, the adhesion between the PAEK resin and the reinforcing fibers decreases, limiting the environments and conditions in which it can be used as a fiber-reinforced thermoplastic resin substrate. Furthermore, the PAEK resin used to improve adhesion requires more cleaning steps, resulting in increased costs and a tendency to be uneconomical.

[0056] The upper limit of the metal content is preferably 48 ppm or less, more preferably 40 ppm or less. When the upper limit of the total metal content is within this preferred range, a fiber-reinforced thermoplastic resin substrate with superior thermal stability tends to be obtained. The lower limit of the metal content is preferably 10 ppm or greater. Setting the metal content to 10 ppm or greater reduces the number of PAEK resin cleaning steps and allows the use of inexpensive PAEK resin, which tends to be economically advantageous.

[0057] Here, the total metal content of the fiber-reinforced thermoplastic resin substrate refers to: after being thermally decomposed using sulfuric acid, nitric acid, hydrofluoric acid and perchloric acid, it is dissolved with dilute nitric acid, and for this solution, the value (mass parts per million) of the content of alkali metals and alkaline earth metals in the obtained solution is calculated using high-frequency induction plasma (ICP) or the like. For example, it can be quantified in the following manner: for the solution obtained by thermally decomposing using sulfuric acid, nitric acid, hydrofluoric acid and perchloric acid and dissolving with dilute nitric acid, it is analyzed by ICP emission spectrometry or atomic absorption spectrometry. In particular, ICP emission spectrometry can analyze multiple elements simultaneously and with high sensitivity, and is therefore a common method for the quantification of trace elements.

[0058] It should be noted that alkali metals include lithium, sodium, potassium, rubidium, cesium, and francium, and alkaline earth metals include magnesium, calcium, strontium, barium, and radium.

[0059] In the present invention, the alkali metal contained in the fiber-reinforced thermoplastic resin substrate is preferably sodium or potassium. When the alkali metal is sodium or potassium, the electrical and thermal properties of the fiber-reinforced thermoplastic resin substrate tend to be excellent.

[0060] The alkaline earth metal contained in the fiber-reinforced thermoplastic resin matrix is ​​preferably magnesium or calcium. When the alkaline earth metal is magnesium or calcium, the electrical and thermal properties of the fiber-reinforced thermoplastic resin matrix tend to be excellent.

[0061] The fiber-reinforced thermoplastic resin matrix preferably contains no metals other than sodium, potassium, magnesium, and calcium (i.e., the concentration is below the detection limit). By limiting the metals contained in the matrix to the aforementioned metals, the retention stability, electrical properties, and thermal properties of the PAEK resin can be further improved.

[0062] The fiber-reinforced thermoplastic resin substrate of the present invention preferably has a crystallization temperature change (ΔTc) of 0°C to 2°C, more preferably 0°C to 1°C. When the crystallization temperature change is within this range, the fiber-reinforced thermoplastic resin substrate tends to have superior mechanical properties, thermal weldability, and molding cycleability. Specifically, when the crystallization temperature change is 2°C or less, the thermal stability of the fiber-reinforced thermoplastic resin substrate is further enhanced, improving welding characteristics and molding cycleability. Furthermore, the retention stability of the PAEK resin in the fiber-reinforced thermoplastic resin substrate can be improved.

[0063] It should be noted that the so-called crystallization temperature change upon cooling (ΔTc) in the present invention can be calculated using the following formula (a), unless otherwise specified, by measuring the crystallization temperature upon cooling Tc(1) of a fiber-reinforced thermoplastic resin substrate that has not been heat-treated and the crystallization temperature upon cooling Tc(2) of a fiber-reinforced thermoplastic resin substrate that has been heated at 380°C for 30 minutes in a nitrogen atmosphere using a differential scanning calorimeter (Q2500 manufactured by TA Instruments).

[0064] ΔTc=Tc(1)-Tc(2) · · · · (a)

[0065] Tc(1): Cooling crystallization temperature of fiber-reinforced thermoplastic resin matrix without heat treatment

[0066] Tc(2): Crystallization temperature of the fiber-reinforced thermoplastic resin matrix after heating at 380°C for 30 minutes in a nitrogen atmosphere

[0067] By adjusting the total metal content of alkali metals and alkaline earth metals contained in the fiber-reinforced thermoplastic resin matrix to 5 ppm or more and less than 50 ppm and modifying the terminal and main chain structures of the PAEK resin, the crystallization temperature change (ΔTc) can be adjusted to fall within the above range.

[0068] In order to keep the total metal content within the above range and thereby maintain the change in the cooling crystallization temperature within the scope of the present invention, it is more preferable to use water with low electrical conductivity in the powder method in the method for producing a fiber-reinforced thermoplastic resin substrate described below. In addition, it is preferable to use a surfactant that does not contain metal.

[0069] In the fiber-reinforced thermoplastic resin substrate of the present invention, the weight-average molecular weight change (ΔMw) of the PAEK resin after treatment at 380°C for 30 minutes in a nitrogen atmosphere is preferably 25% or less, and more preferably 20% or less. When this weight-average molecular weight change is within the above range, the fiber-reinforced thermoplastic resin substrate tends to exhibit superior mechanical properties, thermal weldability, and molding cycleability. Specifically, when the weight-average molecular weight change is 25% or less, the thermal stability of the fiber-reinforced thermoplastic resin substrate is further enhanced, improving welding properties and molding cycleability. Furthermore, the retention stability of the PAEK resin in the fiber-reinforced thermoplastic resin substrate can be improved.

[0070] It should be noted that, unless otherwise specified, the weight average molecular weight change rate (ΔMw) of the PAEK resin can be calculated using the following formula (b) by measuring the weight average molecular weight Mw (1) of the PAEK resin in the fiber-reinforced thermoplastic resin matrix before heat treatment and the weight average molecular weight Mw (2) of the PAEK resin in the fiber-reinforced thermoplastic resin matrix after heating at 380° C. for 30 minutes under a nitrogen atmosphere using gel permeation chromatography as described later.

[0071] ΔMw[%]={Mw(2)-Mw(1)} / Mw(1)×100···(b)

[0072] Mw(1): Weight average molecular weight of the PAEK resin in the fiber-reinforced thermoplastic resin matrix without heat treatment

[0073] Mw(2): Weight average molecular weight of the PAEK resin in the fiber-reinforced thermoplastic resin matrix after heating at 380°C for 30 minutes in a nitrogen atmosphere

[0074] The weight-average molecular weight can be determined by gel permeation chromatography using an eluent in which the resin component used is dissolved. For example, the weight-average molecular weight can be determined by using a gel permeation chromatography (PL-220 (manufactured by Polymer Laboratories), HLC-8320GPC (manufactured by Tosoh Corporation)) using a mixture of chlorophenol and a halogenated benzene such as chlorobenzene, chlorotoluene, bromobenzene, bromotoluene, dichlorobenzene, dichlorotoluene, dibromobenzene, or dibromotoluene as the eluent, or a mixture of pentafluorophenol and chloroform, and calculating the weight-average molecular weight in terms of polystyrene.

[0075] The fiber-reinforced thermoplastic resin substrate of the present invention preferably has a weight loss rate ΔW during heating of 0.08% or less, more preferably 0.05% or less. The weight loss rate is represented by the following formula (c), and is determined by thermogravimetric analysis of a sample heated from 50°C at a rate of 10°C / minute to any temperature of 380°C or higher under normal pressure. The weight of the sample (W1) at the time the temperature reaches 100°C and the weight of the sample (W2) at the time the temperature reaches 380°C are compared.

[0076] ΔW=(W1-W2) / W1×100 (%) · · · (c)

[0077] A weight loss rate ΔW exceeding 0.08% is not preferred because, for example, excessive gas generation during molding of the fiber-reinforced thermoplastic resin substrate tends to occur. Furthermore, a weight loss rate ΔW exceeding 0.08% is not preferred because it increases the amount of deposits deposited on the mold during molding, which tends to reduce productivity. The lower limit of the weight loss rate ΔW of the fiber-reinforced thermoplastic resin substrate is not particularly limited; lower values ​​tend to result in better properties, but generally, it tends to be in the range of 0.01% or higher.

[0078] The fiber-reinforced thermoplastic resin substrate in the present invention preferably has a thickness of 0.1 to 1.5 mm. A thickness of 0.1 mm or greater can improve the strength of a molded article obtained using the fiber-reinforced thermoplastic resin substrate. A thickness of 0.2 mm or greater is more preferred. On the other hand, a thickness of 1.5 mm or less facilitates impregnation of the reinforcing fibers with the polyaryletherketone resin. A thickness of 1 mm or less is more preferred, 0.7 mm or less is even more preferred, and 0.6 mm or less is even more preferred.

[0079] Furthermore, in the fiber-reinforced thermoplastic resin matrix of the present invention, when the total volume of the fiber-reinforced thermoplastic resin matrix is ​​100 volume percent, the reinforcing fibers preferably comprise at least 20 volume percent and no more than 65 volume percent. By including at least 20 volume percent of reinforcing fibers, the strength of a molded article obtained using the fiber-reinforced thermoplastic resin matrix can be further improved. A more preferred amount is 30 volume percent or more, and even more preferably 40 volume percent or more. On the other hand, by including reinforcing fibers in a range of 65 volume percent or less, the reinforcing fibers are more easily impregnated with the thermoplastic resin. The volume content of the reinforcing fibers is more preferably 60 volume percent or less, and even more preferably 55 volume percent or less. It should be noted that the volume content can be adjusted to a desired range by adjusting the amounts of reinforcing fibers and PAEK resin added.

[0080] The volume content (Vf) of the reinforcing fibers in the fiber-reinforced thermoplastic resin matrix is ​​calculated by measuring the mass W0 of the fiber-reinforced thermoplastic resin matrix, decomposing and eluting the PAEK resin in the fiber-reinforced thermoplastic resin matrix according to the sulfuric acid decomposition method described in JIS K7075-1991, and measuring the mass W1 of the reinforcing fibers remaining after washing and drying.

[0081] Vf (volume %) = (W1 / ρf) / {W1 / ρf+(W0-W1) / ρr}×100 (d)

[0082] ρf: density of reinforcing fiber (g / cm 3 )

[0083] ρr: density of polyaryletherketone resin (g / cm3 )

[0084] <Method for Manufacturing Fiber-Reinforced Thermoplastic Resin Base Material>

[0085] The fiber-reinforced thermoplastic resin substrate of the present invention can be obtained by impregnating continuous reinforcing fibers with the polyaryletherketone resin composition.

[0086] Examples of methods for impregnating continuous reinforcing fibers with polyaryletherketone resin include: a film method, in which a film of polyaryletherketone resin is melted and pressurized to impregnate the reinforcing fiber bundles with the polyaryletherketone resin; a mixing method, in which a fibrous polyaryletherketone resin is blended with a reinforcing fiber bundle, the fibrous polyaryletherketone resin is melted and pressurized to impregnate the reinforcing fiber bundles with a thermoplastic resin; a powder method, in which a powdered polyaryletherketone resin is dispersed between the fibers in the reinforcing fiber bundles, the powdered polyaryletherketone resin is melted and pressurized to impregnate the reinforcing fiber bundles with the polyaryletherketone resin; and a drawing method, in which a reinforcing fiber bundle is impregnated with the polyaryletherketone resin by impregnating the reinforcing fiber bundles with molten polyaryletherketone resin and pressurizing. The powder method and the drawing method are preferred, with the powder method being more preferred, as they allow for the production of a variety of fiber-reinforced thermoplastic resin substrates with varying thicknesses and fiber volume contents.

[0087] Among the powder methods, the following powder method is more preferred, namely, the reinforcing fiber bundle is passed through a suspension obtained by dispersing a powdered polyaryletherketone resin in water using a surfactant, the powdered polyaryletherketone resin attached to the reinforcing fiber bundle is melted, and pressurized to impregnate the reinforcing fiber bundle with the polyaryletherketone resin.

[0088] For the PAEK resin powder used in the powder method, the resin powder is preferably micronized to achieve optimal homogeneity of the suspension and good impregnation of the reinforcing fibers. The volume average particle size of the primary particles of the PAEK powder is preferably 1 to 100 μm, more preferably 5 to 50 μm, and even more preferably 10 to 35 μm. A volume average particle size within the above range tends to have high impregnation into the reinforcing fibers. It should be noted that the volume average particle size is calculated based on the particle size distribution measured using the laser diffraction and scattering method in accordance with ISO 13320:2020.

[0089] The water used in the powder method for the suspension is preferably pure water, ion-exchanged water, or ultrapure water, more preferably ion-exchanged water or ultrapure water, and even more preferably ultrapure water. The conductivity of pure water, ion-exchanged water, and ultrapure water is 1-10 μS / cm, 0.1-1 μS / cm, and 0.055-0.1 μS / cm, respectively.

[0090] The surfactant used in the suspension used in the powder method is preferably a metal-free surfactant, more preferably a nonionic surfactant or an amphoteric surfactant.

[0091] <Method for producing molded articles and composites>

[0092] The fiber-reinforced thermoplastic resin substrate of the present invention is laminated in an arbitrary configuration and then molded by applying heat and / or pressure. Examples of methods for applying heat and / or pressure include: press molding, in which the fiber-reinforced thermoplastic resin substrates laminated in an arbitrary configuration are placed in a mold or on a press plate, the mold or press plate is closed, and pressurized; autoclave molding, in which the fiber-reinforced thermoplastic resin substrates laminated in an arbitrary configuration are placed in an autoclave and pressurized and heated; bag molding, in which the fiber-reinforced thermoplastic resin substrates laminated in an arbitrary configuration are wrapped with a film or the like, the interior is reduced in pressure, and then heated in an oven while being pressurized at atmospheric pressure; and wrapping tape, in which a tape is wrapped around the fiber-reinforced thermoplastic resin substrates laminated in an arbitrary configuration while applying tension, and then heated in an oven. In particular, molding methods using molds for pressurization are preferred because they produce molded products with few voids and excellent appearance quality.

[0093] As a press molding method, the following methods can be used: hot pressing, in which a fiber-reinforced thermoplastic resin substrate is pre-placed in a mold, pressurized and heated while the mold is closed, and then, in the closed state, the fiber-reinforced thermoplastic resin substrate is cooled by cooling the mold to obtain a molded product; and stamping molding, in which a fiber-reinforced thermoplastic resin substrate is pre-heated to a temperature above the melting point of the thermoplastic resin using a heating device such as a far-infrared heater, a hot plate, a high-temperature oven, or dielectric heating, and then, in a state where the thermoplastic resin is melted and softened, is placed on the mold that becomes the lower surface of the molding mold, and then the mold is closed and the mold is closed, followed by pressurized cooling. Among these, stamping molding is preferred from the perspective of accelerating the molding cycle and thus improving productivity.

[0094] The fiber-reinforced thermoplastic resin substrate and its molded article of the present invention can be subjected to integrated molding such as insert molding and outsert molding, straightening treatment by heating, highly productive bonding processes such as heat welding, vibration welding, and ultrasonic welding, and integration using adhesives to obtain a composite.

[0095] As the composite, a composite molded article in which the fiber-reinforced thermoplastic resin substrate of the present invention and a molded article composed of a thermoplastic resin are bonded at least partially together is preferable.

[0096] The molded article (molding material and its molded article) comprising a thermoplastic resin integrated with the fiber-reinforced thermoplastic resin substrate of the present invention is not particularly limited, and examples thereof include resin materials and their molded articles, metal materials and their molded articles, inorganic materials and their molded articles, etc. Among them, resin materials and their molded articles are preferred from the perspective of bonding strength with the fiber-reinforced thermoplastic resin substrate of the present invention.

[0097] The matrix resin of the molding material and its molded article integrated with the fiber-reinforced thermoplastic resin substrate of the present invention may be the same type of resin as the fiber-reinforced thermoplastic resin substrate and its molded article of the present invention, or a different type of resin. To further enhance bonding strength, the same type of resin is preferred. When different types of resin are used, it is more preferable to provide a resin layer at the interface.

[0098] Example

[0099] The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto.

[0100] In the examples and comparative examples, the following materials were used as PAEK resin, additives, and reinforcing fibers.

[0101] [PAEK resin: Reference example 1]

[0102] PAEK-1 resin was synthesized according to the method described in Japanese Patent No. 6339184.

[0103] Specifically, a 300-liter tank equipped with a lid, a stirrer / stirring seal, a nitrogen inlet, and a discharge port was charged with diphenyl sulfone (125.52 kg) and heated to 150°C. After the diphenyl sulfone was completely dissolved, 4,4'-difluorobenzophenone (44.82 kg, 205.4 mol), 1,4-dihydroxybenzene (16.518 kg, 150 mol), and 4,4'-dihydroxydiphenyl (9.311 kg, 50 mol) were added to the tank. The contents were then heated to 160°C. While maintaining a nitrogen atmosphere, dry sodium carbonate (21.368 kg, 201.6 mol) and potassium carbonate (1.106 kg, 8 mol) (both passed through a 500-micron sieve) were added. The temperature was raised at 1°C / minute to 180°C and held for 100 minutes. The temperature was then raised at 1°C / minute to 200°C and held for 20 minutes. The temperature was raised at 1°C / minute to 305°C and maintained until the desired melt viscosity (determined by the increase in stirrer torque) was reached. The reaction mixture was injected into a belt caster, cooled in a water bath, pulverized, and washed with acetone and water. The resulting polymer powder was dried in a drum dryer until the measured temperature of the contents reached 112°C. The dried polymer powder was pulverized in a jet mill to obtain particles with a volume average particle size of 23 μm. This was designated as PAEK-1 resin.

[0104] [Reinforcement Fiber: Reference Example 2]

[0105] CF-1: A carbon fiber bundle (manufactured by Toray Industries, Ltd., product name: T700S-12K) was treated at 350° C. for 30 minutes in air to burn off the sizing agent, and the resulting product was used.

[0106] [water]

[0107] The deionized water used in the powder method was the following.

[0108] Water-1: conductivity 0.079 μm / Scm

[0109] Water-2: conductivity 2.01 μm / Scm

[0110] Water-3: conductivity 3.00μm / Scm

[0111] Water-4: conductivity 9.5 μm / Scm.

[0112] [Surfactant]

[0113] The deionized water used in the powder method was the following.

[0114] Surfactant-1: Metal-free surfactant "Amphitol" (registered trademark) 20N (manufactured by Kao Corporation, amine oxide)

[0115] Surfactant-2: Metal-containing surfactant Pelex TR (manufactured by Kao Corporation, sodium dialkyl sulfosuccinate).

[0116] [Quantification of alkali metal and alkaline earth metal content]

[0117] The total content of the fiber-reinforced thermoplastic resin matrix, PAEK resin, and alkali metal and alkaline earth metal components was quantified using the following method. A 5g sample was weighed into quartz, thermally decomposed with sulfuric acid, nitric acid, hydrofluoric acid, and perchloric acid, then dissolved in dilute nitric acid and diluted to 50mL. This solution was quantitatively analyzed for various elements using ICP emission spectrometry (PerkinElmer Optima 4300DV) to determine the contents of lithium, sodium, potassium, rubidium, cesium, francium, magnesium, calcium, strontium, barium, and radium.

[0118] [Crystallization temperature]

[0119] The cooling crystallization temperature (Tc) of the fiber-reinforced thermoplastic resin substrate was measured using TA Instruments Q2500 in a nitrogen atmosphere under the following measurement conditions: The cooling crystallization temperature of the fiber-reinforced thermoplastic resin substrate was the value of the exothermic peak of the first run.

[0120] First Run

[0121] ·30℃×5 minutes hold

[0122] Heating from 30°C to 380°C at a rate of 10°C / min

[0123] 380℃×5 minutes hold

[0124] Cool down from 380℃ to 30℃ at a rate of 10℃ / min.

[0125] [Crystallization temperature change during cooling (ΔTc)]

[0126] The crystallization temperature change upon cooling (ΔTc) was calculated using the following formula (a) by measuring the crystallization temperature upon cooling for an unheated fiber-reinforced thermoplastic resin substrate and for a fiber-reinforced thermoplastic resin substrate heated at 380°C for 30 minutes under a nitrogen atmosphere using differential scanning calorimetry.

[0127] ΔTc=Tc(1)-Tc(2) · · · · (a)

[0128] Tc(1): Cooling crystallization temperature of fiber-reinforced thermoplastic resin matrix without heat treatment

[0129] Tc(2): The cooling crystallization temperature of the fiber-reinforced thermoplastic resin substrate after heating at 380°C for 30 minutes in a nitrogen atmosphere.

[0130] [Weight average molecular weight of PAEK resin]

[0131] To 8 mg of sample, add 4 mL of the following measurement solvent and slowly stir at 170-180°C for 20 minutes. Then, filter using a 0.45 μm filter. The weight-average molecular weight (Mw) of the PAEK resin is calculated using gel permeation chromatography (GPC) in terms of polystyrene. The GPC measurement conditions are shown below.

[0132] Device: PL-220 manufactured by Polymer Laboratories)

[0133] Detector: Differential refractive index detector RI

[0134] Chromatographic column: Shodex HT-806M (2 pieces) (8.0 mm × 30 cm, manufactured by Showa Denko)

[0135] Determination solvent: 1,2,4-trichlorobenzene / 4-chlorophenol

[0136] Flow rate: 0.7 mL / min

[0137] Column temperature: 115°C

[0138] Injection volume: 0.200mL.

[0139] [Change in weight average molecular weight of PAEK resin (ΔMw)]

[0140] The weight-average molecular weight change rate (ΔMw) of the PAEK resin was calculated using the following formula (b) by measuring the weight-average molecular weight of the PAEK resin using gel permeation chromatography for an unheated fiber-reinforced thermoplastic resin substrate and for a fiber-reinforced thermoplastic resin substrate heated at 380°C for 30 minutes under a nitrogen atmosphere.

[0141] ΔMw[%]={Mw(2)-Mw(1)} / Mw(1)×100· · · · (b)

[0142] Mw(1): Weight average molecular weight of the PAEK resin in the fiber-reinforced thermoplastic resin matrix without heat treatment

[0143] Mw(2): Weight average molecular weight of the PAEK resin in the fiber-reinforced thermoplastic resin matrix after heating at 380°C for 30 minutes in a nitrogen atmosphere

[0144] [Measurement of fiber volume content (Vf)]

[0145] The fiber volume content (Vf) in the fiber-reinforced thermoplastic resin matrix is ​​calculated by measuring the mass W0 of the fiber-reinforced thermoplastic resin matrix, decomposing and eluting the PAEK resin in the fiber-reinforced thermoplastic resin matrix according to the sulfuric acid decomposition method described in JIS K7075-1991, and measuring the mass W1 of the reinforcing fibers remaining after washing and drying.

[0146] Vf (volume %) = (W1 / ρf) / {W1 / ρf+(W0-W1) / ρr}×100 (d)

[0147] ρf: density of reinforcing fiber (g / cm 3 )

[0148] ρr: density of PAEK resin (g / cm 3 ).

[0149] [Examples 1 to 3, Comparative Examples 1 to 3]

[0150] Using a powder method, 16 strands of paralleled continuous carbon fibers (CF-1) were impregnated with PAEK-1 resin to produce a fiber-reinforced thermoplastic resin matrix. Specifically, the strands were first stretched in an aqueous slurry of PAEK-1 resin to coat the carbon fibers with the PAEK-1 resin. The aqueous slurry contained 16,000 ml of water and 11.3 g of surfactant per 11,000 g of PAEK-1 resin pulverized and powdered using a jet mill. The amount of water and surfactant varied in each of the Examples and Comparative Examples to achieve the metal content in the resulting fiber-reinforced thermoplastic resin matrix as shown in Table 1. The strands were then stretched by passing them through a die heated to 380°C. The PAEK-1 resin melted or softened, completely impregnating the strands, resulting in a fiber-reinforced thermoplastic resin matrix with unidirectionally aligned reinforcing fibers.

[0151] The resulting fiber-reinforced thermoplastic resin substrate was subjected to the aforementioned evaluation. The evaluation results are shown in Table 1. Note that, among the alkali metal and alkaline earth metal contents, lithium, rubidium, cesium, francium, strontium, barium, and radium were below the detection limit, so only sodium, potassium, magnesium, and calcium are reported.

[0152] [Table 1]

[0153]

[0154] The results of Examples 1 to 3 and Comparative Examples 1 to 3 will be compared and described.

[0155] As shown in Table 1, the fiber-reinforced thermoplastic resin substrates of Examples 1 to 3, in which the combined content of alkali metals and alkaline earth metals was 5 ppm or more and less than 50 ppm, all exhibited a small change in crystallization temperature ΔTc of 2°C or less and a ΔMw of 25% or less, demonstrating excellent thermal stability.

[0156] On the other hand, as shown in Table 1, the fiber-reinforced thermoplastic resin substrate of Comparative Example 1, obtained using Water-4, which has a high electrical conductivity, exhibited a high combined content of alkali metals and alkaline earth metals, resulting in increased ΔTc and ΔMw. Furthermore, the fiber-reinforced thermoplastic resin substrates of Comparative Examples 2 and 3, obtained using Metal-Containing Surfactant-2, also exhibited a high combined content of alkali metals and alkaline earth metals, resulting in further increased ΔTc and ΔMw.

[0157] Industrial applicability

[0158] The fiber-reinforced thermoplastic resin substrate and its molded article of the present invention can be used in various applications such as aircraft parts, automobile parts, electrical and electronic parts, building components, various containers, daily necessities, household goods, and sanitary products by leveraging their excellent properties. The fiber-reinforced thermoplastic resin substrate and its molded article of the embodiments of the present invention are particularly preferably used in applications such as aircraft engine peripheral parts, aircraft exterior parts, automobile body parts and vehicle frames, automobile engine peripheral parts, automobile engine under-hood parts, automobile gear parts, automobile interior parts, automobile exterior parts, intake and exhaust system parts, engine cooling water system parts, automobile electrical components, and electrical and electronic components, which require particularly high impregnation properties, heat aging resistance, and surface appearance.Specifically, the fiber-reinforced resin and its molded article according to the embodiment of the present invention are preferably used for aircraft engine peripheral parts such as fan blades, landing gear compartments, winglets, spoilers, edges, rudders, elevators, shock absorbers, ribs and other aircraft-related parts, various sheets, front body parts, bottom body parts, various pillars, various components, various frames, various beams, various brackets, various rails, various hinge parts and other automobile body parts, engine hoods, intake pipes, timing belt covers, intake manifolds, pipe covers, throttle bodies, radiator fans and other automobile engine peripheral parts, radiator fans, radiator tank tops and bottoms, cylinder head covers, oil pans, brake pipes, fuel piping pipes, exhaust system parts and other automobile engine hood parts, gears, actuators. , bearing supports, bearing covers, chain guides, chain tensioners and other automotive gear parts, gear lever brackets, steering wheel lock brackets, lock cylinders, interior door handles, door handle housings, rearview mirror frames, air conditioner switches, instrument panels, console boxes, storage boxes, steering wheels, interior trims and other automotive interior decoration parts, front hoods, rear fenders, fuel filler caps, doors, cylinder head covers, rearview mirrors, tailgates, license plate decorations, roof longitudinal beams, engine seat brackets, rear decorations, rear spoilers, trunk lids, door sills, inlays, lampshades, air outlet grilles, fenders, side guards and other automotive exterior decoration parts, intake manifolds, intercooler intake pipes, turbochargers, exhaust pipe covers, inner wall sleeves, bearing supports, engine mounts, engine top covers, mufflers, and throttle bodies and other intake and exhaust system parts Engine cooling water system components such as parts, chain covers, thermostat housings, outlet pipes, radiator tanks, alternators, and delivery pipes, connectors, wiring harness connectors, motor parts, lamp holders, vehicle-mounted sensor switches, combination switches and other automotive electrical components, electrical and electronic components such as generators, motors, transformers, converters, voltage regulators, rectifiers, resistors, inverters, relays, power contacts, switches, interrupters, switches, knife switches, multi-pole rods, motor housings, TV housings, laptop computer housings and internal components, CRT display housings and internal components, printer housings and internal components, mobile phones, mobile computers, handheld mobile devices and other portable terminal housings and internal components, IC or LED corresponding housings, electrical Container baffles, fuse holders, various gears, various housings, industrial chassis and cabinets and other electrical components, connectors, SMT-compatible connectors, card connectors, sockets, coils, coil bobbins, sensors, LED lights, sockets, resistors, relays, relay housings, reflectors, small switches, power supply components, coil bobbins, capacitors, variable capacitor housings, optical pickup chassis, resonators, various terminal blocks, mutual inductors, plugs, printed circuit boards, tuners, speakers, microphones, headphones, small motors, head mounts, power modules, Si power modules, SiC power modules, semiconductors, liquid crystals, FDD brackets, FDD chassis, motor brush holders, transformer components, parabolic antennas, computer-related components and other electronic components.

Claims

1. A fiber-reinforced thermoplastic resin substrate, comprising: a plurality of continuous reinforcing fibers impregnated with a polyaryletherketone resin; wherein the total content of alkali metals and alkaline earth metals contained in the fiber-reinforced thermoplastic resin substrate is 5 ppm or more and less than 50 ppm.

2. The fiber-reinforced thermoplastic resin substrate according to claim 1, wherein The alkali metal in the fiber-reinforced thermoplastic resin matrix is ​​sodium or potassium.

3. The fiber-reinforced thermoplastic resin substrate according to claim 1 or 2, wherein The alkaline earth metal in the fiber-reinforced thermoplastic resin matrix is ​​calcium or magnesium.

4. The fiber-reinforced thermoplastic resin substrate according to claim 1 or 2, wherein The fiber-reinforced thermoplastic resin substrate is treated under the following conditions, and the crystallization temperature change ΔTc measured by cooling is 0° C. or more and 2° C. or less. Treatment conditions: 380°C for 30 min in a nitrogen atmosphere.

5. The fiber-reinforced thermoplastic resin substrate according to claim 1 or 2, wherein When the fiber-reinforced thermoplastic resin substrate is treated under the following conditions, the weight average molecular weight change rate ΔMw of the polyaryletherketone resin is 25% or less, Treatment conditions: 380°C for 30 min in a nitrogen atmosphere.

6. The fiber-reinforced thermoplastic resin substrate according to claim 1 or 2, wherein The polyaryletherketone resin in the fiber-reinforced thermoplastic resin matrix is ​​a polyaryletherketone resin selected from the group consisting of polyetherketone, polyetheretherketone, polyetherketoneketone, polyetheretherketoneketone, polyetherketoneetherketoneketone, polyetheretherketoneetherketone, polyetheretheretherketone, polyetherdiphenyletherketone, and mixtures thereof, copolymers thereof, and copolymers thereof with other polyaryletherketone resins.

Images