Amorphous epoxy fiber, fiber structure and molded body

Abstract

The present invention provides amorphous epoxy fibers with excellent dimensional stability, a fiber structure at least partially comprising such fibers, and a molded article obtained by melting such fibers. The amorphous epoxy fibers have a birefringence value of 0.005 or less. For example, the amorphous epoxy fibers may comprise an amorphous epoxy resin represented by the following general formula. Furthermore, the average fiber diameter of a single fiber of the amorphous epoxy fibers may be 40 μm or less. (Wherein, X is a dihydric phenol residue and n is 20 or greater)#imgabs0#

Description

[0001] Related applications

[0002] This application claims priority from Japanese Patent Application No. 2020-014084, filed in Japan on January 30, 2020, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present invention relates to an amorphous epoxy fiber and a fiber structure using the fiber, and further relates to a molded product obtained by melting the fiber. Background Art

[0004] Amorphous epoxy resins are thermoplastic resins that have excellent adhesion to various materials and are used in various applications because they can be molded at relatively low temperatures.

[0005] For example, Patent Document 1 (U.S. Patent No. 8,409,486) describes the use of a fiber material obtained by melt-spinning a polyhydroxy ether, an amorphous epoxy resin, as a binder fiber to secure reinforcing fibers. Specifically, the document describes a composite material obtained by securing reinforcing fibers in a predetermined arrangement using a thermoplastic fiber material composed of a polyhydroxy ether having a specific weight-average molecular weight and glass transition temperature to form a preform. A matrix material is then injected into the preform, followed by a curing treatment to crosslink the thermoplastic fiber material and the matrix material.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: U.S. Patent No. 8,409,486 Summary of the Invention

[0009] Problems to be solved by the invention

[0010] Thus, in Patent Document 1, only the fiber material composed of polyhydroxy ether is used as the binder fiber, and a separately prepared thermosetting resin is used as the matrix resin of the composite material.

[0011] On the other hand, composite materials using thermoplastic resins as matrix resins have also attracted attention in recent years. Furthermore, as mentioned above, amorphous epoxy resins can be molded at relatively low temperatures. Therefore, if a fiber structure containing amorphous epoxy fibers can be used as the matrix resin material for forming a thermoplastic composite material, it is expected that a composite material with good adhesion to reinforcing fibers (e.g., carbon fibers) can be easily molded.

[0012] However, the fiber material composed of polyhydroxy ether described in Patent Document 1 has poor dimensional stability, and when such a fiber material is melted to form a molded article, there is a problem in that the moldability is poor.

[0013] Therefore, in order to solve the above-mentioned problems, an object of the present invention is to provide an amorphous epoxy fiber having excellent dimensional stability.

[0014] Solutions to the Problem

[0015] The inventors of the present invention conducted extensive research to achieve the above-mentioned objectives and discovered that varying the spinning and stretching conditions during fiberization of an amorphous epoxy resin resulted in differences in the dry heat shrinkage of the resulting amorphous epoxy fibers at high temperatures. Furthermore, they discovered that this difference in dry heat shrinkage was influenced by the fiber's orientation. Further research revealed that amorphous epoxy fibers with birefringence values, an indicator of orientation, within a specific range exhibited sufficiently suppressed dry heat shrinkage at high temperatures, i.e., excellent dimensional stability. This led to the completion of the present invention.

[0016] That is, the present invention can be configured as follows.

[0017] [Method 1]

[0018] An amorphous epoxy fiber having a birefringence value of 0.005 or less (preferably 0.004 or less, more preferably 0.003 or less, and even more preferably 0.002 or less).

[0019] [Method 2]

[0020] The amorphous epoxy fiber according to embodiment 1 comprises an amorphous epoxy resin represented by the following general formula:

[0021] [Chemical Formula 1]

[0022]

[0023] (wherein X is a dihydric phenol residue, and n is 20 or greater (preferably 20 to 300, more preferably 40 to 280, and even more preferably 50 to 250)).

[0024] [Method 3]

[0025] The amorphous epoxy fiber according to aspect 1 or 2, wherein

[0026] The average fiber diameter of the single fibers is 40 μm or less (preferably 38 μm or less, more preferably 35 μm or less).

[0027] [Method 4]

[0028] The amorphous epoxy fiber according to any one of aspects 1 to 3 has a dry heat shrinkage at 100°C of 40% or less (preferably 35% or less, more preferably 30% or less, further preferably 25% or less, particularly preferably 20% or less).

[0029] [Method 5]

[0030] A fiber structure, at least a portion of which comprises the amorphous epoxy fiber according to any one of aspects 1 to 4.

[0031] [Method 6]

[0032] The fiber structure according to embodiment 5 is a mixed filament, a knitted fabric, or a nonwoven fabric.

[0033] [Method 7]

[0034] A molded article using the amorphous epoxy fiber according to any one of aspects 1 to 4 as a matrix.

[0035] [Method 8]

[0036] A method for producing a molded article, which is the method for producing a molded article according to Embodiment 7, comprising:

[0037] The amorphous epoxy fiber according to any one of aspects 1 to 4 or the fiber structure according to aspect 5 or 6 is heat-molded at a temperature not lower than the glass transition temperature of the amorphous epoxy resin constituting the amorphous epoxy fiber.

[0038] It should be noted that any combination of at least two constituent elements disclosed in the claims and / or the specification is encompassed by the present invention. In particular, any combination of two or more claims is encompassed by the present invention.

[0039] Effects of the Invention

[0040] The amorphous epoxy fiber of the present invention has excellent dimensional stability because its birefringence value is controlled within a specific range. DETAILED DESCRIPTION

[0041] (Amorphous epoxy resin)

[0042] The amorphous epoxy fiber of the present invention is composed of an amorphous epoxy resin. The amorphous epoxy resin used in the present invention is a thermoplastic resin obtainable by a condensation reaction of a dihydric phenol compound and an epihalohydrin, or a polycondensation reaction of a dihydric phenol compound and a bifunctional epoxy compound.

[0043] Examples of the divalent phenol compound used as a raw material for the amorphous epoxy resin include hydroquinone, resorcinol, 4,4'-dihydroxybiphenyl, 4,4'-dihydroxybenzophenone, 2,2-bis(4-hydroxyphenyl)propane [bisphenol A], 1,1-bis(4-hydroxyphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, bis(4-hydroxyphenyl)methane [bisphenol F], 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)butane, 1,1-bis(4-hydroxyphenyl)- 1-phenylethane, bis(4-hydroxyphenyl)diphenylmethane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(3-phenyl-4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3-tert-butylphenyl)propane, 1,3-bis(2-(4-hydroxyphenyl)propyl)benzene, 1,4-bis(2-(4-hydroxyphenyl)propyl)benzene, 2,2-bis(4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane, 9,9-bis(4-hydroxyphenyl)fluorene, bis(4-hydroxyphenyl)sulfone [bisphenol S], etc. These diphenol compounds can be used alone or in combination of two or more. In addition, as the diphenol compound, bisphenols are preferably used, and at least one diphenol compound selected from bisphenol A, bisphenol F and bisphenol S is particularly preferably used.

[0044] As the difunctional epoxy compound of the raw material becoming amorphous epoxy resin, the epoxy oligomer obtained by the condensation reaction of the above-mentioned dihydric phenol compound and epihalohydrin, for example hydroquinone diglycidyl ether, resorcinol diglycidyl ether, bisphenol S type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, methylhydroquinone diglycidyl ether, chlorohydroquinone diglycidyl ether, 4,4 '-dihydroxydiphenyl oxide diglycidyl ether, 2,6-dihydroxynaphthalene diglycidyl ether, dichlorobisphenol A diglycidyl ether, tetrabromobisphenol A type epoxy resin, 9,9-bis (4-hydroxyphenyl) fluorene diglycidyl ether etc. can be enumerated.These difunctional epoxy compounds can be used alone respectively, or can be used in combination of two or more.As difunctional epoxy compound, more preferably use at least one difunctional epoxy compound selected from bisphenol A type epoxy resin and bisphenol F type epoxy resin.

[0045] The production of amorphous epoxy resins can be carried out in the absence of a solvent or in the presence of a reaction solvent. As the reaction solvent used, an aprotic organic solvent such as methyl ethyl ketone, dimethicone, or the like can be appropriately used. In addition, the amorphous epoxy resin obtained by the solvent reaction can be subjected to a desolvation treatment using an evaporator or the like to obtain a solvent-free solid resin.

[0046] In the production of amorphous epoxy resins, conventionally known polymerization catalysts can be used, for example, alkali metal hydroxides, tertiary amine compounds, quaternary ammonium compounds, tertiary phosphine compounds, quaternary Compounds, etc.

[0047] The amorphous epoxy fibers of the present invention may contain an amorphous epoxy resin represented by the following formula.

[0048] [Chemical Formula 2]

[0049]

[0050] In the formula, X is a diphenol residue, and n can be 20 or greater. The diphenol residue can be a chemical structure derived from the above-mentioned diphenol compounds, and can include one or more chemical structures. For example, X can have a chemical structure derived from at least one diphenol compound selected from bisphenol A, bisphenol F, and bisphenol S. n represents the average degree of polymerization, and can be, for example, in the range of 20 to 300, preferably 40 to 280, and more preferably 50 to 250.

[0051] Furthermore, the amorphous epoxy resin may have a functional group such as a hydroxyl group (for example, a phenolic hydroxyl group) or an epoxy group at a terminal.

[0052] In the present invention, "amorphous" can be confirmed by the presence or absence of an endothermic peak when the sample is heated at a rate of 10°C / min in nitrogen using a differential scanning calorimeter (DSC). Even if the endothermic peak is very broad and cannot be clearly identified, this level does not pose a problem in practical use and can be considered to be substantially amorphous.

[0053] From the perspective of improving spinnability, the weight average molecular weight of the amorphous epoxy resin may be in the range of 10,000 to 100,000, preferably 20,000 to 90,000, and more preferably 30,000 to 80,000. The weight average molecular weight of the amorphous epoxy resin refers to a value measured by gel permeation chromatography (GPC).

[0054] From the perspective of moldability of amorphous epoxy fibers, the glass transition temperature (hereinafter sometimes referred to as Tg) of the amorphous epoxy resin may be 100°C or lower, preferably 98°C or lower, and more preferably 95°C or lower. The lower limit of the glass transition temperature of the amorphous epoxy resin is not particularly limited, but from the perspective of heat resistance of the resulting fiber, it may be, for example, 30°C or higher, preferably 50°C or higher, and more preferably 60°C or higher. The glass transition temperature of the amorphous epoxy resin is measured by differential scanning calorimetry (DSC).

[0055] For amorphous epoxy resin, for example, at 300°C and a shear rate of 1000 sec -1 The melt viscosity may be 600 to 4000 poise, preferably 700 to 3000 poise, more preferably 800 to 2000 poise.

[0056] Within the scope that does not impair the effects of the present invention, the amorphous epoxy fiber of the present invention may contain components other than amorphous epoxy resins. As components other than such amorphous epoxy resins, for example, there can be mentioned: antioxidants, plasticizers, antistatic agents, free radical inhibitors, matting agents, ultraviolet absorbers, flame retardants, dyes, pigments, polymers other than amorphous epoxy resins, etc.

[0057] The amorphous epoxy fiber of the present invention may contain 50 wt% or more of an amorphous epoxy resin, preferably 80 wt% or more, more preferably 90 wt% or more, further preferably 98 wt% or more, and even more preferably 99.5 wt% or more.

[0058] (Amorphous epoxy fiber)

[0059] The birefringence value of the amorphous epoxy fiber of the present invention is 0.005 or less. Here, the birefringence value is an indicator of the molecular orientation state of the amorphous epoxy resin. The smaller the birefringence value, the lower the molecular orientation relative to the fiber axis. The amorphous epoxy fiber of the present invention has a specific birefringence value, and therefore, can reduce shrinkage under high temperature. The birefringence value of the amorphous epoxy fiber can be preferably 0.004 or less, more preferably 0.003 or less, and even more preferably 0.002 or less. In addition, the lower limit of the birefringence value is not particularly limited, for example, it can be around 0.0001. It should be noted that the birefringence value is a value measured by the method described in the examples described below.

[0060] The amorphous epoxy fibers of the present invention can appropriately adjust the average fiber diameter of the single fibers according to the application, etc. The average fiber diameter of the single fibers can be 40 μm or less, preferably 38 μm or less, and more preferably 35 μm or less. For example, when amorphous epoxy fibers are used as a material for forming a matrix resin of a composite material, by making the average fiber diameter of the single fibers within the above range, they can be fully mixed with the reinforcing fibers. In addition, as long as they have a specific birefringence value, the lower limit of the average fiber diameter of the single fibers is not particularly limited, for example, it can be 5 μm or more, preferably 12 μm or more, and more preferably 15 μm or more. It should be noted that when the fiber cross-sectional shape is not a perfect circle, the average fiber diameter of the single fibers can be a value measured based on the diameter of the circumscribed circle of the fiber cross-sectional shape.

[0061] The amorphous epoxy fiber of the present invention can be appropriately adjusted in number of filaments depending on the intended use, and may be either a monofilament or a multifilament. In the case of a multifilament, the number of filaments may be, for example, 5 to 3,000, preferably 10 to 2,000, more preferably 30 to 1,500, and even more preferably 50 to 500.

[0062] The total fineness of the amorphous epoxy fiber of the present invention can be appropriately adjusted according to the application, and may be, for example, 1 to 10,000 dtex, preferably 10 to 5,000 dtex, more preferably 50 to 3,000 dtex, and even more preferably 100 to 1,500 dtex.

[0063] The amorphous epoxy fiber of the present invention has a specific birefringence value, and therefore, can reduce the dry heat shrinkage at 100°C. For example, the dry heat shrinkage at 100°C can be 40% or less, preferably 35% or less, more preferably 30% or less, further preferably 25% or less, and particularly preferably 20% or less. The lower limit of the dry heat shrinkage is not particularly limited, but is preferably 0%, for example, it can be around 1%. In this way, the amorphous epoxy fiber of the present invention has excellent dimensional stability and therefore excellent formability. In addition, the amorphous epoxy fiber of the present invention is composed of an amorphous epoxy resin, and therefore can be formed at a relatively low temperature, and has excellent low-temperature formability. It should be noted that the dry heat shrinkage is a value measured by the method described in the examples described later.

[0064] (Method for producing amorphous epoxy fibers)

[0065] The method for manufacturing amorphous epoxy fibers of the present invention may include a spinning process of melt-spinning an amorphous epoxy resin. By adjusting the spinning conditions (especially the spinning temperature and spinning speed) in the spinning process, the shear stress applied to the molten polymer during spinning can be reduced, and amorphous epoxy fibers that meet specific birefringence values ​​can be obtained.

[0066] When melt-spinning an amorphous epoxy resin, a known melt-spinning apparatus can be used. For example, pellets of the amorphous epoxy resin are melt-kneaded using a melt extruder, and the molten polymer is introduced into a spinning cylinder. Subsequently, a gear pump is used to measure the molten polymer, a predetermined amount is ejected from a spinning nozzle, and the resulting filaments are wound to produce the amorphous epoxy fiber of the present invention. It should be noted that the filaments obtained by melt-spinning and winding can be used directly without stretching.

[0067] By reducing the melt viscosity at the spinning temperature during the spinning process, the shear stress applied to the molten polymer can be reduced, thereby suppressing the orientation of the fiber. For example, the shear rate at the spinning temperature can be 1000 sec -1The spinning temperature is adjusted so that the melt viscosity at 600 to 4000 poise is achieved, preferably 700 to 3000 poise, more preferably 800 to 2000 poise. By increasing the spinning temperature, the melt viscosity of the amorphous epoxy resin can be reduced. The spinning temperature can be appropriately set according to the type of amorphous epoxy resin. For example, the spinning temperature can be 250 to 330°C, preferably 260 to 320°C, and more preferably 280 to 315°C.

[0068] The size of the spinning hole (single hole) in the spinning spinneret can be appropriately set according to the desired fiber diameter, for example, it can be 0.02 to 1 mm. 2 About 0.03 to 0.5 mm, preferably 0.03 to 0.5 mm 2 About 0.03 to 0.15 mm, more preferably 0.03 to 0.15 mm 2 It should be noted that the shape of the spinning hole can be appropriately selected according to the desired cross-sectional shape of the fiber, and is preferably a perfect circle.

[0069] The ejection speed from the spinning nozzle can be appropriately set according to the viscosity of the molten polymer at the spinning temperature, the nozzle aperture, and the ejection rate. By setting it relatively low, the shear stress applied to the molten polymer within the nozzle can be reduced. For example, the ejection speed can be in the range of 2.54 m / min to 42.4 m / min, preferably 4.24 m / min to 33.9 m / min, and more preferably 4.24 m / min to 25.4 m / min.

[0070] The spinning speed (winding speed) at this time can be appropriately set according to the viscosity of the molten polymer at the spinning temperature, the aperture of the nozzle, and the ejection amount. By making it relatively low, the orientation of the fiber can be reduced. For example, it is preferably drawn in the range of 100m / min to 2000m / min, more preferably 100m / min to 1500m / min, further preferably 100m / min to 1000m / min, particularly preferably 100m / min to 750m / min, and most preferably 100m / min to 500m / min. In addition, from the perspective of adjusting the orientation of the fiber, the ratio of the ejection speed to the winding speed (draft ratio; winding speed / ejection speed) can be, for example, in the range of 2 to 300, preferably 5 to 200, more preferably 10 to 100, and further preferably 15 to 50.

[0071] In the method for producing amorphous epoxy fibers of the present invention, the fibers obtained after melt spinning may be used directly as undrawn yarns without being drawn. Furthermore, as long as the amorphous epoxy fibers have a specific birefringence value, a drawing step may be included to draw the fibers obtained by the spinning step, for example, from the perspective of adjusting the fiber diameter. From the perspective of reducing shrinkage at high temperatures, it is preferred to use the fibers as undrawn yarns.

[0072] When a stretching process is included, from the perspective of adjusting the birefringence value of the amorphous epoxy fiber, the birefringence value of the unstretched yarn is preferably 0.0045 or less, more preferably 0.0035 or less, further preferably 0.0025 or less, and particularly preferably 0.0015 or less. Taking the glass transition temperature (Tg) of the amorphous epoxy resin as a reference, the stretching temperature is preferably Tg-30°C or higher and Tg+20°C or lower. In addition, from the perspective of adjusting the birefringence value of the amorphous epoxy fiber, it is preferred to set the stretching ratio to be as low as possible (for example, a stretching ratio of about 1.01 to 1.3, preferably a stretching ratio of about 1.01 to 1.2) for the yarn ejected from the spinning nozzle. Taking into account the adjustment of the fiber diameter, the stretching ratio can be set according to the stretching temperature. For example, when the stretching temperature is Tg-30°C or higher and lower than Tg-20°C, the stretching ratio is preferably 1.01 to 1.2; when Tg-20°C or higher and lower than Tg°C, the stretching ratio is preferably 1.01 to 1.4; when Tg°C or higher and Tg+20°C or lower, the stretching ratio is preferably 1.01 to 1.7.

[0073] (Fiber structure)

[0074] The amorphous epoxy fibers of the present invention can be used as fiber structures at least partially containing the amorphous epoxy fibers. The amorphous epoxy fibers can be used in any fiber form, such as short fibers, chopped fibers, filament yarns, spun yarns, threads, and ropes. Furthermore, the amorphous epoxy fibers can be either non-composite or composite fibers.

[0075] The fiber structure of the present invention may be a fabric. The fabric may be formed using the amorphous epoxy fiber of the present invention. The fabric may be in any form, including nonwoven fabrics (including paper), woven fabrics, and knitted fabrics. Such fabrics can be produced using amorphous epoxy fibers using known or customary methods.

[0076] For the fiber structure of the present invention, as long as the effect of the present invention is not impaired, amorphous epoxy fibers can be combined with other fibers. For example, a mixed filament obtained by mixing amorphous epoxy fibers with other fibers can be used. As a cloth, the amorphous epoxy fibers of the present invention can be included as, for example, a main fiber, and its ratio relative to the whole can include more than 50% by mass, preferably more than 80% by mass, and particularly more than 90% by mass. By making such a cloth (especially paper, non-woven fabric), a cloth that fully utilizes the characteristics of amorphous epoxy fibers can be obtained. When the fiber structure is used for the manufacture of a composite material, the fiber structure can be a mixed filament or a mixed fiber cloth containing reinforcing fibers as other fibers.

[0077] Amorphous epoxy fibers and fiber structures containing the same can be extremely effectively used in various shapes in a wide range of applications, including industrial materials, agricultural materials, civil engineering materials, electrical and electronic materials, optical materials, and aircraft / automobile / shipbuilding fields.

[0078] (Molding)

[0079] The amorphous epoxy fibers of the present invention can be used as molded articles using the amorphous epoxy fibers as a matrix. In the present invention, the molded article may be any article obtained by molding amorphous epoxy fibers or fiber structures. For example, it may be a molded article containing no reinforcing fibers obtained by molding amorphous epoxy fibers or fiber structures, or it may be a composite material containing reinforcing fibers obtained by molding amorphous epoxy fibers or fiber structures together with reinforcing fibers.

[0080] The method for producing a molded article of the present invention may include at least a step of preparing the amorphous epoxy fiber or fiber structure and a heat molding step of heating the amorphous epoxy fiber or fiber structure at a temperature not lower than the glass transition temperature of the amorphous epoxy resin.

[0081] The heat molding method is not particularly limited as long as the amorphous epoxy fibers can be melted and integrated, and a general molding method for a molded body can be used.

[0082] In the heat molding process, there are no limitations as long as the amorphous epoxy fiber can be melted and molded into the desired shape by heating at a temperature above the glass transition temperature of the amorphous epoxy resin. For example, the heating temperature may be 300°C or lower, and preferably 280°C or lower. Furthermore, since amorphous epoxy fibers can be molded at relatively low temperatures, the heating temperature may be 250°C or lower, and preferably 230°C or lower, to prevent degradation of the molded article.

[0083] When the molded body is heated and molded, it can be molded under pressure. The pressure is not particularly limited, but is usually 0.05N / mm 2 Above (e.g. 0.05-15N / mm 2 The time for heat molding is not particularly limited, but if the polymer is exposed to high temperature for a long time, it may deteriorate, so it is usually preferably within 30 minutes.

[0084] It should be noted that the shape of the molded article is not particularly limited and can be appropriately determined depending on the intended use. Heat molding can also be performed by stacking multiple fabrics of varying specifications or placing fabrics of varying specifications in a mold of a predetermined size. Depending on the circumstances, the article can also be molded together with other reinforcing fiber fabrics or composite materials. Furthermore, a molded article obtained by a single heat molding process can be subjected to a second heat molding process depending on the intended purpose.

[0085] When the molded body of the present invention is a composite material containing reinforcing fibers, examples of methods for producing the composite material include a method for heat-molding a laminated body formed by laminating a fiber structure and a reinforcing fiber cloth (e.g., a reinforcing fiber fabric), a method for heat-molding a fiber structure containing reinforcing fibers, and the like.

[0086] The type of reinforcing fiber used in the composite material is not particularly limited. From the viewpoint of the mechanical strength of the resulting composite material, examples include glass fiber, carbon fiber, liquid crystal polyester fiber, aramid fiber, polyparaphenylene benzodione, and polyparaphenylene benzodione. At least one of poly(p-phenylene benzobisimidazole) fiber, poly(p-phenylene benzodithiazole) fiber, ceramic fiber, and metal fiber. These reinforcing fibers can be used alone or in combination of two or more. Among them, from the viewpoint of improving mechanical properties, preferably carbon fiber or glass fiber.

[0087] The shape of the reinforcing fiber cloth is not particularly limited and can be appropriately set depending on the intended use, and examples thereof include woven fabrics, non-crimp fabrics (NCF), unidirectional materials (UD materials), knitted fabrics, and nonwoven fabrics.

[0088] The density of the molded article of the present invention is preferably 2.00 g / cm 3 Below. Preferably 1.95g / cm 3 Below, more preferably 1.90 g / cm 3 The lower limit of density can be appropriately determined according to the choice of material, for example, it can be 0.1 g / cm 3 about.

[0089] In addition, the thickness of the molded article of the present invention is preferably 0.05 mm or more (preferably 0.1 mm or more). It can be more preferably 0.3 mm or more, and further preferably 0.5 mm or more. In addition, the upper limit of the thickness can be appropriately set according to the thickness required for the molded article, for example, it can be about 10 mm.

[0090] The molded article of the present invention can be produced inexpensively without requiring any special process, and therefore can be suitably used as, for example, housings for computers, displays, OA equipment, mobile phones, portable information terminals, digital cameras, optical equipment, audio players, air conditioners, lighting equipment, toys, electrical appliances, electronic equipment parts, and other home appliances; civil engineering / building materials such as interior components, exterior components, pillars, panels, and reinforcing materials; various parts, frames, hinges, brackets, axles, wheel bearings, beams, columns, supports, and guide rails for vehicles (automobiles, bicycles, ships, airplanes, etc.); and various other components for instruments. Vehicle interior parts such as chassis, trays, outer panels, or body parts, bumpers, moldings, under covers, hoods, fairings, spoilers, cowl shutters, aviation parts, etc.; vehicle fuel system, exhaust system or air intake system parts such as engine parts, CNG tanks, gasoline tanks, fuel pumps, air intakes, intake manifolds, carburetor bodies, carburetor baffles, various pipes, various valves; UAV / aircraft parts such as landing gear pods, winglets, spoilers, edges, rudders, elevators, fairings, ribs, etc.

[0091] Example

[0092] The present invention will be described in more detail below with reference to the following examples, but the present invention is not limited to these examples. It should be noted that in the following examples, various physical properties represent values ​​measured by the following methods.

[0093] [Melt viscosity]

[0094] The melt viscosity of the amorphous epoxy resin was measured using a Capilograph "1CPMD-C" manufactured by Toyo Seiki Seisaku-sho, Ltd. at 300°C and a shear rate of 1000 sec. -1 The measurement was carried out under the conditions of .

[0095] [Birefringence value]

[0096] The birefringence value was calculated using the following formula from the retardation measured under a light source of λ = 546.1 nm (e-line) using an Olympus polarizing microscope "BX53" equipped with a Berek compensator: Note that the fiber thickness represents the fiber diameter.

[0097] Δn=R / d

[0098] Δn: birefringence value, R: retardation (nm), d: fiber thickness (nm)

[0099] [Average fiber diameter (μm)]

[0100] The fibers were magnified and photographed at a predetermined magnification using a scanning electron microscope (SEM), and the diameters of 100 randomly selected fibers were measured. The average of the obtained values ​​was defined as the average fiber diameter.

[0101] [Dimensional stability evaluation]

[0102] Dimensional stability was evaluated as the dry heat shrinkage of the fiber. Fibers cut into 10 cm pieces were kept in an air thermostat at 100°C for 30 minutes without fixing the ends. The shrinkage was then calculated using the following formula based on the fiber length (X cm).

[0103] Dry heat shrinkage (%) = {(10-X) / 10}×100

[0104] [Moldability Evaluation]

[0105] A molded body containing 50 wt% of amorphous epoxy fibers as a matrix and 13 mm cut length carbon fibers (manufactured by Teijin Limited: average fiber diameter 7 μm, specific gravity 1.8 g / cm 3 ) 50wt% slurry was wet laid to obtain a unit area weight of 254g / m 2 Then, the obtained nonwoven fabric was subjected to a pressure of 3N / mm at 260℃. 2 The composite material was press-molded for 3 minutes under a pressure of 1000 nm to obtain a composite material with a thickness of 1 mm. The moldability was evaluated based on the appearance of the composite material (surface roughness, thickness unevenness, shrinkage, and warping) according to the following criteria.

[0106] ◎: No surface roughness, uneven thickness, shrinkage, or warping.

[0107] ○: Slight surface roughness, thickness unevenness, shrinkage, and warping were observed.

[0108] ×: Surface roughness, uneven thickness, shrinkage, and warping are very noticeable.

[0109] [Evaluation of low temperature formability]

[0110] A molded body containing 55 wt% of amorphous epoxy fibers as a matrix and 13 mm cut length glass fibers (manufactured by Nippon Electric Glass Co., Ltd.: average fiber diameter 10.5 μm, specific gravity 2.5 g / cm2) as reinforcing fibers were used. 3 ) 45wt% slurry, through the wet laid process to obtain a unit area weight of 98g / m 2 Then, the obtained nonwoven fabric was subjected to a 200°C and 3N / mm2 The composite material was press-molded for 1 minute under a pressure of 1000 nm to obtain a composite material with a thickness of 1 mm. The moldability was evaluated based on the appearance of the composite material (surface roughness, thickness unevenness, shrinkage, and warping) according to the following criteria.

[0111] ◎: No surface roughness, uneven thickness, shrinkage, or warping.

[0112] ○: Slight surface roughness, thickness unevenness, shrinkage, and warping were observed.

[0113] ×: Surface roughness, uneven thickness, shrinkage, and warping are very noticeable.

[0114] [Example 1]

[0115] As an amorphous epoxy resin, a bisphenol A (BPA) type phenoxy resin (manufactured by Nippon Steel Chemical & Materials Co., Ltd., "YP-50s") having a weight average molecular weight of 60,000, a glass transition temperature of 84°C, and a melt viscosity of 890 poise at 300°C was used. The resin was melt-extruded through a twin-screw extruder and ejected from a 0.2 mm Φ × 100 hole circular orifice nozzle at a spinning temperature of 300°C. The ejection speed was adjusted to 4.5 m / min, the winding speed was adjusted to 167 m / min, and the ratio of the ejection speed to the winding speed (draw-down ratio) was adjusted to 37.1, and the fiber was wound. The obtained fiber was evaluated, and the results are shown in Table 1.

[0116] [Example 2]

[0117] Fibers were obtained in the same manner as in Example 1 except that the discharge speed was adjusted to 8.1 m / min, the winding speed was adjusted to 300 m / min, and the ratio of the discharge speed to the winding speed (draft ratio) was adjusted to 37.0. The obtained fibers were evaluated, and the results are shown in Table 1.

[0118] [Example 3]

[0119] Fibers were obtained in the same manner as in Example 1 except that the discharge speed was adjusted to 12.1 m / min, the winding speed was adjusted to 450 m / min, and the ratio of the discharge speed to the winding speed (draft ratio) was adjusted to 37.2. The obtained fibers were evaluated, and the results are shown in Table 1.

[0120] [Example 4]

[0121] Fibers were obtained in the same manner as in Example 1 except that the discharge speed was adjusted to 25.9 m / min, the winding speed was adjusted to 1400 m / min, and the ratio of the discharge speed to the winding speed (draft ratio) was adjusted to 54.1. The obtained fibers were evaluated, and the results are shown in Table 1.

[0122] [Example 5]

[0123] Fibers were obtained in the same manner as in Example 1, except that the ejection speed was adjusted to 9.0 m / min, the winding speed was adjusted to 167 m / min, and the ratio of the ejection speed to the winding speed (draft ratio) was adjusted to 18.6. Furthermore, the fibers were stretched at a stretching temperature of 100°C, a stretching speed of 12 m / min, and a stretching ratio of 1.5 to obtain stretched fibers. The resulting fibers were evaluated, and the results are shown in Table 1.

[0124] [Example 6]

[0125] A drawn fiber was obtained in the same manner as in Example 5 except that the drawing temperature was 80° C., the drawing speed was 12 m / min, and the drawing ratio was 1.25. The obtained fiber was evaluated, and the results are shown in Table 1.

[0126] [Example 7]

[0127] A drawn fiber was obtained in the same manner as in Example 5 except that the drawing temperature was 60° C., the drawing speed was 12 m / min, and the drawing ratio was 1.05. The obtained fiber was evaluated, and the results are shown in Table 1.

[0128] [Comparative Example 1]

[0129] Fibers were obtained in the same manner as in Example 1, except that the ejection speed was adjusted to 9.0 m / min, the winding speed was adjusted to 167 m / min, and the ratio of the ejection speed to the winding speed (draft ratio) was adjusted to 18.6. Furthermore, the fibers were stretched at a stretching temperature of 100°C, a stretching speed of 12 m / min, and a stretch ratio of 1.75 to obtain stretched fibers. The resulting fibers were evaluated, and the results are shown in Table 1.

[0130] [Comparative Example 2]

[0131] A drawn fiber was obtained in the same manner as in Comparative Example 1 except that the drawing was performed at a drawing temperature of 80° C., a drawing speed of 12 m / min, and a drawing ratio of 1.5. The obtained fiber was evaluated, and the results are shown in Table 1.

[0132] [Comparative Example 3]

[0133] A drawn fiber was obtained in the same manner as in Comparative Example 1 except that the drawing was performed at a drawing temperature of 60° C., a drawing speed of 12 m / min, and a drawing ratio of 1.25. The obtained fiber was evaluated, and the results are shown in Table 1.

[0134] [Comparative Example 4]

[0135] The fibers obtained in Example 4 were stretched at a stretching temperature of 60° C., a stretching speed of 12 m / min, and a stretching ratio of 1.1 to obtain stretched fibers. The obtained fibers were evaluated, and the results are shown in Table 1.

[0136] [Comparative Example 5]

[0137] Fibers were obtained in the same manner as in Example 1 except that the discharge speed was adjusted to 4.0 m / min, the winding speed was adjusted to 1400 m / min, and the ratio of the discharge speed to the winding speed (draft ratio) was adjusted to 350. The obtained fibers were evaluated, and the results are shown in Table 1.

[0138]

[0139] As shown in Table 1, in Examples 1 to 4, amorphous epoxy fibers having specific birefringence values ​​were obtained by adjusting the spinning conditions. Furthermore, in Examples 5 to 7, amorphous epoxy fibers having specific birefringence values ​​and excellent dimensional stability were obtained by adjusting the spinning and stretching conditions. Therefore, composite materials obtained by molding using such amorphous epoxy fibers as a matrix exhibit good appearance and excellent moldability.

[0140] On the other hand, in Comparative Examples 1 to 5, the obtained fibers had poor dimensional stability due to the inability to control birefringence. Consequently, composite materials molded using the obtained fibers as a matrix exhibited surface roughness, significant thickness variations, and significant shrinkage, resulting in poor moldability of the obtained fibers.

[0141] Industrial Applicability

[0142] The amorphous epoxy fibers and fiber structures comprising the amorphous epoxy fibers of the present invention can be suitably used in a variety of applications. Furthermore, they can be used as molded articles in which the amorphous epoxy fibers are melted and used as a matrix. Such amorphous epoxy fibers, fiber structures, and molded articles can be extremely effectively used in the fields of general industrial materials, electrical and electronic fields, civil engineering and construction, aircraft, automobile, railway, and shipbuilding, agricultural materials, optical materials, and medical materials.

[0143] As described above, the preferred embodiments of the present invention have been described, but those skilled in the art can easily conceive of various changes and modifications within the obvious scope after reading this specification. Therefore, such changes and modifications are to be construed as being within the scope of the invention defined by the claims.

Claims

1. An amorphous epoxy fiber having a birefringence value of 0.005 or less, The amorphous epoxy fiber comprises an amorphous epoxy resin represented by the following general formula: Wherein, X is a dihydric phenol residue, n is 20 or more, The average fiber diameter of a single fiber is less than 40 μm. The amorphous epoxy fiber is an undrawn fiber. 2 . The amorphous epoxy fiber according to claim 1 , wherein the amorphous epoxy fiber has a dry heat shrinkage at 100° C. of 40% or less.

3. A fiber structure, at least a portion of which comprises the amorphous epoxy fiber according to claim 1 or 2. The fiber structure according to claim 3 , which is a mixed filament, a woven fabric, or a non-woven fabric.

5. A molded article using the amorphous epoxy fiber according to claim 1 or 2 as a matrix.

6. The method for producing the molded article according to claim 5, comprising: The amorphous epoxy fiber according to claim 1 or 2, or the fiber structure according to claim 3 or 4, is heat-molded at a temperature not lower than the glass transition temperature of the amorphous epoxy resin constituting the amorphous epoxy fiber.

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