Fiber structure, crosslinked molded article, and method for manufacturing crosslinked molded article

Abstract

Provided are a fiber structure configured from two types of thermoplastic resins having thermal crosslinking reactivity, and a crosslinked molded body obtained by inducing a thermal crosslinking reaction between the thermoplastic resins. The fiber structure contains at least thermoplastic resins A and B that have thermal crosslinking reactivity with respect to each other, the thermoplastic resin A being an amorphous epoxy resin and at least one of the thermoplastic resins A and B having a fiber form.

Description

Related Applications

[0001] This application claims priority to Patent Application No. 2021-104634, filed in Japan on June 24, 2021, the entire contents of which are incorporated herein by reference. [Technical Field]

[0002] The present invention relates to a fiber structure composed of two types of thermoplastic resins, at least one of which has a fibrous shape and has thermal crosslinking reactivity (crosslinking reactivity caused by heat), and further to a crosslinked molded article obtained by subjecting these thermoplastic resins to a thermal crosslinking reaction. [Background technology]

[0003] Plastic molding materials are lighter than metal materials and have excellent moldability, so their use is expanding more and more, with or without reinforcing fibers such as glass fiber or carbon fiber, for housings for various sporting goods, bicycles, various electrical and electronic devices, and even industrial components. Plastic molding materials can be broadly divided into those that use thermosetting resins and those that use thermoplastic resins.

[0004] Generally, in the case of thermosetting resin molded articles, a crosslinking agent and a thermosetting resin are combined, and the resin is heat-cured by generating chemical crosslinks, thereby producing the desired molded article.

[0005] For example, Patent Document 1 (International Publication No. WO 2016 / 152856) discloses a fiber-reinforced plastic molding material in which a matrix resin contains, as essential components, a thermoplastic phenoxy resin, a thermosetting epoxy resin, and a crosslinking agent, the phenoxy resin being a room-temperature solid phenoxy resin with a melt viscosity of 3,000 Pa·s or less in a temperature range of 160 to 220°C, the matrix resin having an average particle size (d50) of 10 to 150 μm, and a fine powder of the matrix resin being attached to a reinforcing fiber substrate by a powder coating method. This document describes how, by attaching the phenoxy resin fine powder to a fiber-reinforced substrate and then thermosetting the phenoxy resin, epoxy resin, and crosslinking agent by a thermosetting reaction, FRP molded articles with high heat resistance and mechanical strength can be produced with high productivity and at low cost.

[0006] Furthermore, in the case of thermoplastic resin molded articles, it has been proposed to produce the desired molded article by first melting the thermoplastic resin, forming it into a desired shape, and then fixing the shape by cooling.

[0007] For example, Patent Document 2 (International Publication No. WO2014 / 021084) discloses a nonwoven fabric for use in producing a heat-resistant resin composite, the nonwoven fabric comprising heat-resistant thermoplastic fibers, reinforcing fibers, and polyester-based binder fibers, and lists polyetherimide-based fibers, semi-aromatic polyamide-based fibers, polyether ether ketone-based fibers, and polycarbonate-based fibers as the heat-resistant thermoplastic fibers. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] International Publication No. WO2016 / 152856 [Patent Document 2] International Publication No. WO2014 / 021084 Summary of the Invention [Problem to be solved by the invention]

[0009] However, in Patent Document 1, a resin molding material is prepared by adhering a fine powder of matrix resin to the reinforcing fibers by powder coating, and therefore, in such a resin molding material, it is difficult to adjust the amount of the fine powder of matrix resin relative to the reinforcing fibers. On the other hand, if a simple fine powder is applied to the reinforcing fibers as the matrix resin, it is easy to adjust the amount of the fine powder of matrix resin relative to the reinforcing fibers, but the resin fine powder is prone to spilling, which is disadvantageous in terms of handleability. On the other hand, in Patent Document 2, a nonwoven fabric made of heat-resistant thermoplastic fibers is used as a resin molding material, and the thermoplastic fibers that make up the nonwoven fabric are melted by heat treatment to obtain a molded body.However, since the thermoplastic resin that makes up the thermoplastic fibers has high heat resistance, the molding temperature due to melting becomes high, which is disadvantageous in terms of moldability.

[0010] Therefore, an object of the present invention is to solve the above problems and to provide a fiber structure that is easy to handle and has good moldability (i.e., can produce good crosslinked molded articles).

[0011] Another object of the present invention is to provide a thermally crosslinked molded article that exhibits moldability at low temperatures and heat resistance at temperatures higher than those during molding. [Means for solving the problem]

[0012] As a result of investigations aimed at solving such problems, the present inventors have focused on the fact that amorphous epoxy resins (or phenoxy resins) are thermoplastic resins that can be molded at relatively low temperatures while containing crosslinkable groups present in thermosetting resins. They have found that (i) by combining an amorphous epoxy resin with a thermoplastic resin that thermally crosslinks with the amorphous epoxy resin, it is possible to mold the resin into a thermoplastic resin, and that the strength of the molded article after heating can be improved by forming a crosslinked structure by heat; further, (ii) by making at least one of the resins a fibrous structure, it is possible to use a fiber structure as a molding material, and such a fiber structure has excellent handleability due to the fibrous resin and facilitates uniform resin distribution; and (iii) with regard to the fiber structure, before thermal crosslinking is formed between the amorphous epoxy resin and another crosslinkable resin, the fiber structure can be arranged in a desired shape and molded at a relatively low temperature due to the amorphous epoxy resin, and the heat resistance of the obtained molded article can be improved by thermal crosslinking, thereby completing the present invention.

[0013] That is, the present invention can be configured in the following manner. [Aspect 1] The thermoplastic resin composition comprises at least thermoplastic resins A and B which are thermally crosslinkable with each other, the thermoplastic resin A is an amorphous epoxy resin, A fiber structure, wherein at least one of the thermoplastic resins A and B has a fibrous shape. [Embodiment 2] The fiber structure according to embodiment 1, wherein both the thermoplastic resins A and B have a fibrous shape. Aspect 3 3. The fiber structure according to claim 1 or 2, wherein the thermoplastic resin A comprises amorphous epoxy fibers 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). Aspect 4 A fiber structure according to any one of aspects 1 to 3, wherein the weight ratio of the thermoplastic resin A to the thermoplastic resin B is 30 / 70 to 90 / 10 (preferably 35 / 65 to 79 / 21, and more preferably 40 / 60 to 70 / 30). Aspect 5 The fiber structure according to any one of aspects 1 to 4, which is a nonwoven fabric. Aspect 6 A fiber structure according to any one of aspects 1 to 5, wherein the glass transition temperature of the thermoplastic resin A is lower than the softening point of the thermoplastic resin B, and the temperature difference therebetween is 40°C or more (preferably 50°C or more, and more preferably 55°C or more). Aspect 7 A fiber structure according to any one of aspects 1 to 6, wherein the thermoplastic resin B is a polycarbonate resin. Aspect 8 A fiber structure according to any one of embodiments 1 to 7, further comprising reinforcing fibers. Aspect 9 A fiber structure according to aspect 8, wherein the weight ratio of the total amount of the thermoplastic resin A and the thermoplastic resin B to the reinforcing fibers is 70 / 30 to 25 / 75 (preferably 60 / 40 to 35 / 65, and more preferably 55 / 45 to 45 / 55). Aspect 10 A fiber structure according to aspect 8 or 9, wherein, when the fiber diameter of the reinforcing fibers in the fiber structure is taken as 100, the fiber diameter of the fibers made of at least one of thermoplastic resins A and B is 5 to 3500 (preferably 30 to 2000, more preferably 80 to 500). Aspect 11 A fiber structure according to any one of aspects 1 to 10, having an elongation of 1% or more (preferably 4% or more, more preferably 10% or more). Aspect 12 a preparation step of preparing the fiber structure according to any one of aspects 1 to 11; a heat molding step of stacking one or more of the fiber structures and heating them at a temperature equal to or higher than the flow initiation temperature of thermoplastic resins A and B; A method for producing a crosslinked molded article, comprising at least the steps of: Aspect 13 A method for producing a crosslinked molded article according to aspect 12, wherein the heat-molding step is carried out using a mold having a three-dimensional shape. Aspect 14 A method for producing a crosslinked molded article according to aspect 12 or 13, wherein the heat-molding step is carried out by heat treatment at 300°C or less (preferably 280°C or less, more preferably 250°C or less, and even more preferably 230°C or less). Aspect 15 A method for producing a crosslinked molded article according to Aspect 14, wherein the cooling step is carried out at a temperature that is 0 to 80°C lower than the heating temperature HT of the heat-molding step, i.e., (HT-80) to (HT-0)°C (preferably (HT-60)°C or higher, more preferably (HT-30)°C or higher). Aspect 16 A crosslinked molded article of the fiber structure according to any one of aspects 1 to 11, wherein the crosslinked molded article has a deflection temperature under load of 250°C or higher (preferably 280°C or higher, more preferably 300°C or higher). Aspect 17 17. The crosslinked molded article according to claim 16, wherein the crosslinked molded article has a complex-shaped region.

[0014] It should be noted that any combination of at least two elements disclosed in the claims and / or the specification and / or the drawings is included in the present invention, and in particular any combination of two or more of the claims set forth in the claims is included in the present invention. [Effects of the Invention]

[0015] The fiber structure of the present invention is not only easy to handle due to its fiber structure, but also can be easily formed into a complex shape because the resin in the fiber structure is flowable by heating. configuredWhen a fiber structure is heated to form a molded article, the fiber structure can be molded while a crosslinking reaction occurs between the resins in the fiber structure due to heating. Furthermore, the thermal crosslinking of the resin in the molded article improves the strength of the molded article, and the molded article has excellent heat resistance even when exposed to temperatures higher than the molding temperature. DETAILED DESCRIPTION OF THE INVENTION

[0016] The fiber structure of the present invention contains at least thermoplastic resins A and B which are thermally crosslinkable with each other, and the thermoplastic resin A is an amorphous epoxy resin.

[0017] (Thermoplastic resin A) The thermoplastic resin A used in the present invention, i.e., the amorphous epoxy resin, may be a thermoplastic resin obtainable by a condensation reaction between a dihydric phenol compound and an epihalohydrin (e.g., epichlorohydrin), or a polyaddition reaction between a dihydric phenol compound and a bifunctional epoxy compound.

[0018] Examples of dihydric phenol compounds that can be used as raw materials for amorphous epoxy resins include hydroquinone, resorcinol, 4,4'-dihydroxybiphenyl, 4,4'-dihydroxydiphenyl ketone, 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 Examples of suitable dihydric phenol compounds include (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, and bis(4-hydroxyphenyl)sulfone (bisphenol S). These dihydric phenol compounds can be used alone or in combination of two or more. Furthermore, it is preferable to use bisphenols as the dihydric phenol compound, and it is particularly preferable to use at least one dihydric phenol compound selected from the group consisting of bisphenol A, bisphenol F, and bisphenol S.

[0019] Examples of bifunctional epoxy compounds that can be used as raw materials for amorphous epoxy resins include epoxy oligomers obtained by condensation reactions between the above-mentioned dihydric phenol compounds and epihalohydrins, such as hydroquinone diglycidyl ether, resorcinol diglycidyl ether, bisphenol S epoxy resins, bisphenol A epoxy resins, bisphenol F epoxy resins, methylhydroquinone diglycidyl ether, chlorohydroquinone diglycidyl ether, 4,4'-dihydroxydiphenyloxide diglycidyl ether, 2,6-dihydroxynaphthalene diglycidyl ether, dichlorobisphenol A diglycidyl ether, tetrabromobisphenol A epoxy resins, and 9,9-bis(4-hydroxyphenyl)fluorene diglycidyl ether. These bifunctional epoxy compounds can be used alone or in combination of two or more. It is more preferable to use at least one bifunctional epoxy compound selected from the group consisting of bisphenol A epoxy resins and bisphenol F epoxy resins.

[0020] The amorphous epoxy resin can be produced in the absence of a solvent or in the presence of a reaction solvent, and the reaction solvent preferably used is an aprotic organic solvent such as methyl ethyl ketone, dioxane, tetrahydrofuran, acetophenone, N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylacetamide, sulfolane, etc. The amorphous epoxy resin obtained by the solvent reaction can be converted into a solvent-free solid resin by removing the solvent using an evaporator or the like.

[0021] In producing the amorphous epoxy resin, a conventionally known polymerization catalyst can be used, and for example, alkali metal hydroxides, tertiary amine compounds, quaternary ammonium compounds, tertiary phosphine compounds, quaternary phosphonium compounds, etc. can be suitably used.

[0022] The amorphous epoxy fiber of the present invention may contain an amorphous epoxy resin represented by the following formula:

[0023] [ka]

[0024] In the formula, X may be a dihydric phenol residue, and n may be 20 or greater. The dihydric phenol residue may have a chemical structure derived from the above-mentioned dihydric phenol compound, or may contain one or more chemical structures. For example, X may have a chemical structure derived from at least one dihydric phenol compound selected from the group consisting of bisphenol A, bisphenol F, and bisphenol S. n represents the average degree of polymerization, and may be, for example, in the range of 20 to 300, preferably 40 to 280, and more preferably 50 to 250.

[0025] The amorphous epoxy resin may also have a functional group such as a hydroxyl group (for example, a phenolic hydroxyl group) or an epoxy group at its terminal.

[0026] In the present invention, "amorphous" can be confirmed by the presence or absence of an endothermic peak when a sample is heated in nitrogen at a rate of 10°C / min using a differential scanning calorimeter (DSC). If the endothermic peak is very broad and cannot be clearly identified, it may be determined to be substantially amorphous, as this is at a level that does not pose a problem in practical use.

[0027] The weight-average molecular weight of the amorphous epoxy resin can be appropriately selected depending on the shape, and can be selected from a wide range of, for example, 10,000 to 200,000. When the amorphous epoxy resin is made into fiber, from the viewpoint of improving spinnability, the weight-average molecular weight of the amorphous epoxy resin may be about 10,000 to 100,000, preferably about 20,000 to 90,000, and more preferably about 30,000 to 80,000. The weight-average molecular weight of the amorphous epoxy resin can be calculated in polystyrene equivalent terms by gel permeation chromatography (GPC).

[0028] 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, from the viewpoint of moldability. There is no particular restriction on the lower limit of the glass transition temperature of the amorphous epoxy resin, but from the viewpoint of the heat resistance of the resulting molded article, 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).

[0029] Amorphous epoxy resins are, for example, 300°C and a shear rate of 1000 sec -1 The melt viscosity at this temperature may be 600 to 4000 poise, preferably 700 to 3000 poise, and more preferably 800 to 2000 poise.

[0030] The amorphous epoxy resin may be in the form of fiber, powder, a solution or emulsion composed of an amorphous epoxy resin and a solvent or dispersion medium, or a combination thereof, as long as it can form the fiber structure of the present invention. For example, the powdery material can be prepared by pulverizing the raw material resin with a known pulverizer to have a desired average particle size, which may be, for example, 10 to 100 μm, preferably 20 to 80 μm, and more preferably 30 to 60 μm. The average particle size is a value measured by the method described in the Examples below. Of these, the amorphous epoxy resin is preferably in the form of fiber, and the fiber will be described in detail below.

[0031] (amorphous epoxy fiber) The amorphous epoxy fiber is not particularly limited as long as it is made of an amorphous epoxy resin, and can have various fiber diameters depending on the shape of the intended fiber structure. The average fiber diameter of the amorphous epoxy fiber may be, for example, 40 μm or less, preferably 38 μm or less, and more preferably 35 μm or less. For example, when amorphous epoxy-based fibers are used as a material for forming a matrix resin of a composite material with reinforcing fibers, the average fiber diameter of the single fibers is within the above range, which is advantageous for mixing with the reinforcing fibers. ,example For example, it may be 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, still more preferably 15 μm or more, and particularly preferably 20 μm or more. When the cross-sectional shape of the fiber is not a perfect circle, the average fiber diameter of the single fiber may be a value measured from the circumscribed circle diameter of the cross-sectional shape of the fiber. The average fiber diameter is a value measured in the examples described later.

[0032] The total fineness of the amorphous epoxy fiber can be adjusted appropriately depending on the application, etc., 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.

[0033] The number of filaments in the amorphous epoxy fiber can be adjusted appropriately depending on the application, etc., and the fiber may be 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.

[0034] The amorphous epoxy-based fibers may be continuous or discontinuous depending on the shape of the fiber structure. The amorphous epoxy-based fibers may be crimped or non-crimped. When the fiber structure is a nonwoven fabric, the fibers are cut to an appropriate length depending on the type of nonwoven fabric. When the amorphous epoxy fiber is a discontinuous fiber, the average fiber length may be, for example, 3 to 80 mm, preferably 7 to 70 mm, and more preferably 15 to 60 mm. When the fiber has such an average fiber length, entanglement between the fibers can be suppressed, and therefore the processability during mixing is excellent.

[0035] Preferably, the amorphous epoxy fiber may have a birefringence value of 0.005 or less. Here, the birefringence value is an index showing the molecular orientation state of the amorphous epoxy resin, and the smaller the birefringence value, the lower the molecular orientation in the fiber axis direction. Such amorphous epoxy fibers are preferred because they can achieve thermal crosslinking while reducing shrinkage at high temperatures. The birefringence value of the amorphous epoxy fiber may be preferably 0.004 or less, more preferably 0.003 or less, and even more preferably 0.002 or less. The lower limit of the birefringence value is not particularly limited, but may be, for example, about 0.0001. The birefringence value is a value measured by the method described in the Examples below.

[0036] The amorphous epoxy fiber can be obtained by melt spinning an amorphous epoxy resin. A known melt spinning device can be used for melt spinning the amorphous epoxy resin. For example, pellets of the amorphous epoxy resin are melt-kneaded in a melt extruder, and the molten polymer is introduced into a spinning tube. The molten polymer is then metered using a gear pump, and a predetermined amount is discharged from a spinning nozzle. The resulting filament is wound up, thereby producing the amorphous epoxy fiber of the present invention.

[0037] In particular, when obtaining amorphous epoxy fibers having a birefringence value of 0.005 or less, it is preferable to lower the melt viscosity at the spinning temperature in the spinning step. For example, the shear rate at the spinning temperature is 1000 sec -1 The spinning temperature may be adjusted so that the melt viscosity at RT is 600 to 4000 poise, and the melt viscosity may be preferably 700 to 3000 poise, and more preferably 800 to 2000 poise. Also, for example, the spinning temperature may be 250 to 330°C, preferably 260 to 320°C, and more preferably 280 to 315°C.

[0038] The discharge speed from the spinning nozzle can be appropriately set depending on the viscosity of the molten polymer at the spinning temperature, the nozzle hole diameter, and the discharge rate, but by setting the discharge speed relatively low, the shear stress applied to the molten polymer in the nozzle can be reduced. For example, the discharge speed may be in the range of 2.54 to 42.4 m / min, preferably 4.24 to 33.9 m / min, and more preferably 4.24 to 25.4 m / min.

[0039] The spinning speed (winding speed) can be set appropriately depending on the viscosity of the molten polymer at the spinning temperature, the nozzle hole diameter, and the discharge rate, but a relatively low winding speed can reduce the fiber orientation. For example, the discharged yarn is preferably taken up at a winding speed in the range of 100 to 2000 m / min, more preferably 100 to 1500 m / min, even more preferably 100 to 1000 m / min, particularly preferably 100 to 750 m / min, and most preferably 100 to 500 m / min.

[0040] In the method for producing an amorphous epoxy fiber according to the present invention, the fiber obtained after melt spinning may be used as an undrawn yarn without being drawn. , spinning The fiber obtained in the yarn process may be subjected to a drawing process in order to adjust the fiber diameter, for example. The drawing temperature is preferably (Tg-30) to (Tg+20)°C, where Tg is the glass transition temperature of the amorphous epoxy resin. From the viewpoint of adjusting the birefringence of the amorphous epoxy fiber, the draw ratio of the yarn discharged from the spinning nozzle may be set as low as possible (for example, about 1.01 to 1.3, preferably about 1.01 to 1.2). However, taking into consideration both the adjustment of the fiber diameter and the draw ratio, the draw ratio may be set according to the drawing temperature. For example, when the drawing temperature is (Tg-30)°C or higher but lower than (Tg-20)°C, the draw ratio is preferably 1.01 to 1.2; when (Tg-20)°C or higher but lower than Tg°C, the draw ratio is preferably 1.01 to 1.4; and when Tg°C or higher but lower than (Tg+20)°C, the draw ratio is preferably 1.01 to 1.7.

[0041] (Thermoplastic resin B) Thermoplastic resin B has functional groups that can crosslink with thermoplastic resin A, an amorphous epoxy resin, upon heating. Unlike thermosetting resins, thermoplastic resins do not inherently undergo crosslinking reactions when different types of resins are heated and melted together. However, amorphous epoxy resins, perhaps because they contain secondary hydroxyl groups, are capable of forming crosslinking reactions similar to those of thermosetting resins with other thermoplastic resins having functional groups that react with secondary hydroxyl groups, even though they are thermoplastic resins. In such cases, heating not only makes it possible to melt at least one of the thermoplastic resins, but also to cause a crosslinking reaction between both thermoplastic resins, thereby improving the heat resistance of the molded article after the crosslinking reaction.

[0042] The occurrence of a crosslinking reaction between thermoplastic resins A and B can be confirmed, for example, by (i) the fact that the molded product after the crosslinking reaction does not melt or deform and maintains its shape even when heated to or above the glass transition temperature of either thermoplastic resin A or B, whichever has the higher glass transition temperature; or (ii) the fact that the deflection temperature under load shown in the examples is equal to or higher than the glass transition temperature. The occurrence of a crosslinking reaction can also be confirmed by (iii) the increase in melt viscosity of the molded product at a predetermined high temperature. Furthermore, (iv) while the presence of expandable reinforcing fibers may cause the molded product to expand at high temperatures due to the repulsive force of the fibers, the crosslinked molded product of the present invention can suppress this expansion due to the crosslinked structure of the resin, and can also be confirmed by the fact that the expansion rate (e.g., the rate of change in the thickness direction) upon heating above the glass transition temperature is suppressed compared to a non-crosslinked molded product. The occurrence of a crosslinking reaction can be confirmed, for example, by at least one of (i) to (iv).

[0043] Thermoplastic resin B is capable of causing a crosslinking reaction between thermoplastic resins A and B, and may be in the form of fibers, powder, a solution or emulsion composed of thermoplastic resin B and a solvent or dispersion medium, or a combination thereof. The powdery material can be prepared by pulverizing the raw material resin with a known pulverizer to have a desired average particle size, which may be, for example, 10 to 100 μm, preferably 20 to 80 μm, and more preferably 30 to 60 μm. The average particle size is a value measured in the examples described later. Of these, the thermoplastic resin B is preferably in the form of fibers, and the fibers will be described in detail below.

[0044] Fibers made of thermoplastic resin B (hereinafter referred to as fiber B) can have various fiber diameters depending on the type of resin and the shape of the intended fiber structure. The average fiber diameter of single fibers of fiber B may be, for example, similar to that of amorphous epoxy fibers. When the cross-sectional shape of the fiber is not a perfect circle, the average fiber diameter of single fibers may be a value measured from the circumscribed circle diameter of the cross-sectional shape of the fiber. The average fiber diameter is a value measured in the examples described below.

[0045] Alternatively, when thermoplastic resin A is composed of amorphous epoxy fibers with a relatively large fiber diameter, taking into consideration blendability, etc., the average fiber diameter of single fibers of fiber B is preferably smaller than the average fiber diameter of the amorphous epoxy fibers, and specifically may be, for example, 35 μm or less, preferably 30 μm or less, and more preferably 20 μm or less. Also, the lower limit of the average fiber diameter of single fibers of fiber B may be, for example, 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, still more preferably 12 μm or more, and particularly preferably 15 μm or more.

[0046] The total fineness of fiber B can be adjusted appropriately depending on the application, etc., 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.

[0047] The number of filaments in fiber B can be adjusted appropriately depending on the application, etc., and may be 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.

[0048] Fiber B may be continuous or discontinuous depending on the shape of the fiber structure. Fiber B may be crimped or non-crimped. When the fiber structure is a nonwoven fabric, it is cut to an appropriate length depending on the type of nonwoven fabric. When the fibers are discontinuous, the average fiber length of the fibers B may be, for example, 3 to 80 mm, preferably 7 to 70 mm, and more preferably 15 to 60 mm. When the fibers have such an average fiber length, entanglement between the fibers can be suppressed, and therefore the processability during mixing is excellent.

[0049] From the viewpoint of improving heat resistance, the softening point of thermoplastic resin B is preferably higher than the glass transition temperature of thermoplastic resin A. Here, the softening point refers to the melting point when thermoplastic resin B is a crystalline resin, and refers to the glass transition temperature when thermoplastic resin B is an amorphous resin. For example, the difference between the softening point of thermoplastic resin B and the glass transition temperature of thermoplastic resin A may be 40°C or more, more preferably 50°C or more, and even more preferably 55°C or more. As long as they have thermal crosslinking reactivity, the glass transition temperatures of thermoplastic resin A and thermoplastic resin B can be set appropriately, but for example, the difference between the softening point of thermoplastic resin B and the glass transition temperature of thermoplastic resin A may be 200°C or less.

[0050] The thermoplastic resin B is not particularly limited as long as it is capable of undergoing a thermal crosslinking reaction, for example, an ester exchange reaction, with the thermoplastic resin A, and examples thereof include resins having an electron-withdrawing functional group such as a carbonate group, an aldehyde group, a ketone group, or an ester group, such as polycarbonate resins.

[0051] (Polycarbonate resin) The polycarbonate resin used in the present invention is a polymer containing a repeating unit represented by the following formula, and is not particularly limited as long as it has melt moldability.

[0052] [ka]

[0053] In the formula, Y may be a direct bond, an alkylene group having 1 to 8 carbon atoms, an alkylidene group having 2 to 8 carbon atoms, a cycloalkylene group having 5 to 15 carbon atoms, a cycloalkylidene group having 5 to 15 carbon atoms, an oxygen atom, a sulfur atom, -CO-, -SO-, or -SO2-.

[0054] The polycarbonate resin preferably has a bisphenol A skeleton in which Y is a methylene group. For example, in the monomer units in the polycarbonate resin, the proportion (molar ratio) of the bisphenol A skeleton to the whole may be 65% or more, preferably 75% or more. The polycarbonate resin may have branched chains, but the degree of branching is preferably less than 0.1 mol%.

[0055] The weight-average molecular weight of the polycarbonate-based resin used in the present invention can be appropriately selected depending on the shape, and can be selected, for example, from the range of 10,000 to 100,000. When the polycarbonate-based resin is made into fibers, from the viewpoint of improving spinnability, the weight-average molecular weight of the polycarbonate-based resin may be about 25,000 to 80,000, preferably about 35,000 to 65,000, and more preferably about 45,000 to 55,000. The weight-average molecular weight of the polycarbonate-based resin can be calculated in polystyrene equivalent terms by gel permeation chromatography (GPC).

[0056] From the viewpoint of moldability, the glass transition temperature (hereinafter sometimes referred to as Tg) of the polycarbonate-based resin may be 200°C or lower, preferably 190°C or lower, and more preferably 180°C or lower. There is no particular lower limit for the glass transition temperature of the polycarbonate-based resin, but it may be 135°C or higher, preferably 140°C or higher, and more preferably 145°C or higher. The glass transition temperature of the polycarbonate-based resin is measured by differential scanning calorimetry (DSC).

[0057] The melt viscosity of polycarbonate resin is, for example, 320°C and a shear rate of 1000 sec -1 The melt viscosity at this temperature may be 600 to 4000 poise, and more preferably 800 to 3000 poise.

[0058] The melt flow rate (MFR) of the polycarbonate resin measured in accordance with ISO1183 may be, for example, 8 to 35 g / 10 min, and more preferably 11 to 18 g / 10 min.

[0059] Among these, thermoplastic resin B preferably has a fibrous form, more preferably polycarbonate-based fibers, and particularly preferably polycarbonate-based fibers with an orientation degree of less than 0.70. Polycarbonate-based fibers with such an orientation degree are preferred because they can achieve thermal crosslinking while reducing shrinkage at high temperatures. Here, the orientation degree can be calculated as the orientation degree ft using the following formula: ft=1-(Cu / C) 2 Cu: Sound velocity in unoriented PC polymer (km / sec) In the present invention, Cu=1.0. C: Measured speed of sound (km / sec)

[0060] The degree of orientation may be preferably 0.68 or less, more preferably 0.65 or less, even more preferably 0.62 or less, and particularly preferably 0.61 or less. There is no particular restriction on the lower limit of the degree of orientation, but it may be 0.1 or more.

[0061] Polycarbonate-based fibers can be obtained by melt spinning a polycarbonate-based resin. A known melt spinning device can be used for melt spinning a polycarbonate-based resin. For example, pellets of a polycarbonate-based resin are melt-kneaded in a melt extruder, and the molten polymer is introduced into a spinning tube. The molten polymer is then metered with a gear pump and discharged in a predetermined amount from a spinning nozzle. The resulting yarn is wound up, thereby producing a polycarbonate-based fiber.

[0062] For example, a method for producing polycarbonate-based fibers may include a melt-kneading step in which a polycarbonate-based resin is melt-kneaded at a high temperature (for example, 305°C or higher, preferably 310°C or higher, and more preferably 315°C or higher, but below the decomposition temperature of the resin) to obtain a molten polymer; a discharge step in which the molten polymer is discharged from a spinning nozzle in a predetermined amount; and a winding step in which the discharged thread (or molten raw yarn) is wound up at a predetermined take-up speed (or spinning speed).

[0063] More specifically, a known melt spinning device can be used for melt spinning polycarbonate-based fibers. For example, polycarbonate-based resin pellets are melt-kneaded in a melt extruder, and the molten polymer is introduced into a spinning tube. The molten polymer is then metered by a gear pump and discharged in a predetermined amount from a spinning nozzle, and the resulting filament is wound up.

[0064] The extrusion speed from the spinning nozzle can be set appropriately depending on the viscosity of the molten polymer at the spinning temperature, the nozzle hole diameter, and the extrusion amount, but by setting it relatively low, the shear stress applied to the molten polymer within the nozzle can be reduced.

[0065] For example, the size of the spinning hole (single hole) in the spinneret is 0.02 to 1 mm 2 Approximately, preferably 0.03 to 0.5 mm 2 Approximately, more preferably 0.05 to 0.15 mm 2 The shape of the radiation hole can be appropriately selected depending on the required cross-sectional shape of the fiber.

[0066] For example, the discharge rate from the spinning nozzle can be set appropriately depending on the number and diameter of the holes in the nozzle, and may be, for example, about 10 to 300 g / min, preferably about 20 to 280 g / min.

[0067] The spinning speed (take-up speed) can be set appropriately depending on the viscosity of the molten polymer at the spinning temperature, the nozzle hole diameter, and the discharge rate, but by setting the take-up speed relatively low, the orientation of the fibers can be reduced. For example, the take-up speed may be preferably in the range of 500 to 4000 m / min, more preferably 600 to 3000 m / min, and even more preferably 800 to 2500 m / min.

[0068] In the method for producing polycarbonate-based fibers, the fibers obtained after melt spinning may be used as undrawn yarns without being drawn, or the yarns discharged from the spinning nozzle may be drawn at an extremely low draw ratio (for example, a draw ratio of about 1.01 to 1.3, preferably about 1.01 to 1.2).

[0069] (fiber structure) In the fiber structure of the present invention, at least one of the thermoplastic resins A and B has a fibrous shape, and it is preferred that both of the thermoplastic resins A and B have a fibrous shape. The shape of the fiber structure of the present invention can be appropriately set depending on the application, and may be, for example, a filament such as a string-like material or a rope-like material, or various types of fabric such as a nonwoven fabric, a woven fabric, or a knitted fabric, and the nonwoven fabric may be a dry-laid nonwoven fabric or a wet-laid nonwoven fabric. When the fiber structure is a fabric such as a nonwoven fabric, woven fabric, or knitted fabric, the basis weight is 10 to 1500 g / m 2 and preferably 30 to 1100 g / m 2 More preferably, it is 50 to 700 g / m 2 may be. The dry nonwoven fabric may be prepared by mechanically three-dimensionally entangling a web formed from predetermined fibers using a hydroentanglement method, a needle punching method or the like. For example, in the case of a dry nonwoven fabric, the fiber structure has a basis weight of 200 to 1500 g / m 2 and preferably 300 to 1100 g / m 2 , more preferably 400 to 700 g / m 2 may be. The wetlaid nonwoven fabric may be obtained by preparing a slurry containing fibers and a solvent, and then subjecting this slurry to a conventional papermaking process. For example, in the case of a wet-laid nonwoven fabric, the fiber structure has a basis weight of 10 to 300 g / m 2 and preferably 30 to 250 g / m 2 , more preferably 50 to 150 g / m 2 may be.

[0070] The thermoplastic resin A and the thermoplastic resin B forming the fiber structure may contain components other than these thermoplastic resins, provided that the effects of the present invention are not impaired. Examples of such components other than the thermoplastic resin B include antioxidants, heat stabilizers, plasticizers, antistatic agents, radical inhibitors, delustering agents, UV absorbers, flame retardants, dyes, pigments, and other polymers.

[0071] The content ratio of thermoplastic resin A to thermoplastic resin B in the fiber structure can be appropriately set depending on the type of resin, the application of the fiber structure, etc., but may be, for example, thermoplastic resin A / thermoplastic resin B = 30 / 70 to 90 / 10 by weight, preferably 35 / 65 to 79 / 21, and more preferably 40 / 60 to 70 / 30. When the content ratio of thermoplastic resin A to thermoplastic resin B is within the above range, the crosslink density of the crosslinked molded article becomes sufficiently high, and an even more excellent effect of improving heat resistance can be obtained.

[0072] The fiber structure may further be combined with other fibers as long as the effects of the present invention are not impaired. For example, the fiber structure may be a blended yarn or fabric that combines fibers made of thermoplastic resin A and / or thermoplastic resin B with other fibers.

[0073] For example, the fiber structure may further contain reinforcing fibers. The type of reinforcing fiber used in the composite is not particularly limited. However, from the viewpoint of the mechanical strength of the resulting composite, at least one type selected from the group consisting of glass fiber, carbon fiber, liquid crystal polyester fiber, aramid fiber, polyparaphenylene benzobisoxazole fiber, polyparaphenylene benzobisimidazole fiber, polyparaphenylene benzobisthiazole fiber, ceramic fiber, and metal fiber may be used. These reinforcing fibers may be used alone or in combination of two or more types. Among these, carbon fiber or glass fiber is preferred from the viewpoint of improving mechanical properties.

[0074] The reinforcing fibers may be continuous or discontinuous. In the case of discontinuous fibers, the average fiber length of the reinforcing fibers may be, for example, 3 to 80 mm, preferably 7 to 70 mm, and more preferably 15 to 60 mm. Reinforcing fibers having such an average fiber length can improve the strength of the molded body and also suppress entanglement between fibers, thereby providing excellent processability during mixing. Furthermore, reinforcing fibers having such an average fiber length can be used as reinforcing fibers that can exhibit expandability. The average fiber length of the reinforcing fibers in the present invention can be determined by the measurement method described below.

[0075] The average fiber diameter of the reinforcing fibers is not particularly limited, but may be, for example, 25 μm or less, preferably 20 μm or less, and more preferably 15 μm or less. The lower limit of the average fiber diameter of the reinforcing fibers may be, for example, 3 μm or more, and preferably 5 μm or more. Furthermore, in relation to the average fiber diameter of the fibers made of at least one of thermoplastic resins A and B, when the average fiber diameter of the reinforcing fibers is taken as 100, the average fiber diameter of the fibers made of at least one of thermoplastic resins A and B may be 5 to 3500, preferably 30 to 2000, and more preferably 80 to 500. When the average fiber diameter of the fibers made of at least one of thermoplastic resins A and B is within the above range relative to the average fiber diameter of the reinforcing fibers, the fibers can be well mixed with the reinforcing fibers, resulting in excellent processability.

[0076] The proportion of reinforcing fibers in the fiber structure of the present invention may be, for example, a weight ratio of the total amount of thermoplastic resin A and thermoplastic resin B to the reinforcing fibers in the fiber structure, (thermoplastic resin A + thermoplastic resin B) / (reinforcing fibers) = 70 / 30 to 25 / 75, preferably 60 / 40 to 35 / 65, and more preferably 55 / 45 to 45 / 55. When the weight ratio of reinforcing fibers is greater than the above lower limit, the reinforcing effect of the reinforcing fibers is increased, and the strength of the molded body can be further increased. On the other hand, when the weight ratio of reinforcing fibers is less than the above upper limit, the portion impregnated with resin increases, and the strength of the molded body can be further increased.

[0077] The proportion of fibers in the fiber structure may be, for example, 80% by weight or more, preferably 90% by weight or more, more preferably 95% by weight or more, and particularly preferably 100% by weight. Even when a powdery material is contained in the fiber structure, a higher proportion of fibers is preferable because it can prevent the powdery material from falling off.

[0078] The fiber structure preferably has a high elongation, and for example, the breaking elongation at room temperature may be 1% or more, preferably 4% or more, and more preferably 10% or more. The upper limit of the breaking elongation is not particularly limited, but may be, for example, about 200%. A fiber structure with high elongation is preferable because it has good adaptability to curved shapes. Here, the breaking elongation is a value measured by the method described in the examples below.

[0079] The fiber structure of the present invention can be effectively used in many applications, including industrial materials, agricultural materials, civil engineering materials, electrical and electronic materials, optical materials, aircraft, automobiles, and ships, and is particularly useful as an intermediate material for obtaining crosslinked molded articles, as described below.

[0080] (Method of manufacturing crosslinked molded body) A crosslinked molded article can be obtained by heat treating the fiber structure of the present invention to soften or melt the thermoplastic resins A and / or B in the fiber structure and cause a thermal crosslinking reaction. Specifically, the method for producing a crosslinked molded body may include at least a preparation step of preparing the fiber structure, and a heat-molding step of heating the fiber structure alone or multiple layers at a temperature equal to or higher than the flow initiation temperature of thermoplastic resins A and B.

[0081] (preparation process) In the preparation step, one or more desired fiber structures are prepared. When the fiber structure contains reinforcing fibers, a composite material reinforced with the reinforcing fibers can be obtained using only the fiber structure. When a plurality of fiber structures are prepared, the same type or different types of fiber structures may be prepared. If necessary, a single or multiple reinforcing fiber substrates made of reinforcing fibers may be prepared together with the fiber structure. The reinforcing fiber substrates can be used appropriately depending on the application, etc., and may be, for example, fabrics such as woven fabrics, non-crimp fabrics (NCF), unidirectionally aligned materials (UD materials), knitted fabrics, nonwoven fabrics, tows made of bundled multifilaments, monofilaments, etc. These reinforcing fiber substrates may be used alone or in combination of two or more types. In addition, examples of reinforcing fibers include the reinforcing fibers described in the fiber structure. When a plurality of reinforcing fiber substrates are prepared, the reinforcing fiber substrates may be of the same type or different types.

[0082] (Heat forming process) The prepared fiber structure is subjected to a heat molding step. The heat molding method is not particularly limited as long as at least one of the thermoplastic resins A and B in the fiber structure can be formed into a matrix by heating, and a general molding method for a molded body can be used. During the heat molding process, thermoplastic resins A and B melt and undergo a thermal crosslinking reaction at their contact interface. This crosslinking reaction is thought to involve the formation of three-dimensional crosslinks through an ester exchange reaction between hydroxyl groups present in thermoplastic resin A and carbonate groups or ester groups present in thermoplastic resin B.

[0083] In the heat molding step, the prepared fiber structure and, if necessary, the reinforcing fiber substrate may be heated and compressed. In other words, the molded product may be a molded product that does not contain reinforcing fibers, or may be a molded product that contains reinforcing fibers.

[0084] When the molded article of the present invention is a composite material containing reinforcing fibers, examples of a method for manufacturing the composite material include a manufacturing method in which a laminate formed by laminating a fiber structure and a reinforcing fiber cloth (e.g., a reinforcing fiber woven fabric) is heat-molded, and a manufacturing method in which a fiber structure containing reinforcing fibers is heat-molded.

[0085] The molding method may be, for example, a method in which the material is softened by heating and then formed into a desired shape by applying external stress, such as heat press molding, vacuum molding, or compressed air molding.

[0086] The heat-molding step may utilize heated platens or a mold of the desired shape, if necessary. The mold may have a three-dimensional shape, for example, a curved surface shape or an uneven shape.

[0087] The hot forming step may also include drawing, stretching, flanging, bending, etc. For example, in drawing, in cylindrical deep drawing, the depth / drawing diameter ratio may be 0.5 or more, or the depth / drawing diameter ratio may be 0.7 or more.

[0088] Furthermore, in the hot molding process, it is possible to stack multiple fiber structures with different specifications, or to separately place fiber structures with different specifications in a mold of a certain size and then hot mold them. In some cases, they can also be molded together with other reinforcing fiber substrates or composite materials.

[0089] The heat molding step is not limited as long as the target resin can be softened or melted and molded into a desired shape by heating to a temperature equal to or higher than the glass transition temperature of at least one of thermoplastic resins A and B (preferably the amorphous epoxy resin that is thermoplastic resin A, and more preferably both thermoplastic resins A and B), and the heating temperature may be, for example, 300°C or lower, preferably 280°C or lower. From the viewpoint of preventing deterioration of the molded body, the heating temperature may be 250°C or lower, preferably 230°C or lower.

[0090] When the molded body is heated and molded, it may be molded under pressure. There is no particular limitation on the pressure, but it is usually 0.05 N / mm 2 or more (e.g., 0.05 to 15 N / mm 2There is no particular limit to the time for heat molding, but prolonged exposure to high temperatures can cause the polymer to deteriorate, so it is usually preferable to keep it to within 30 minutes.

[0091] After the heat molding step, a cooling step may be performed or may be omitted. That is, the cooling step may be performed at a temperature that is 0 to 80°C lower than the heating temperature HT of the heat molding step, i.e., at (HT-80) to (HT-0)°C. For example, when removing the product without cooling, i.e., at (HT-0)°C, a step of heating and compressing the product while keeping the mold at a constant temperature, and then releasing the pressure and removing the product at the same temperature as during heating may be performed.

[0092] When a molded article is produced using the fiber structure of the present invention, the thermoplastic resins A and B in the fiber structure are crosslinked by heating, so that the cooling treatment for reducing the expansiveness and fluidity of the matrix resin after the heating step can be omitted or can be carried out at a higher temperature than usual. Therefore, from the viewpoint of working efficiency, the cooling temperature may be preferably (HT-60)°C or higher, more preferably (HT-30)°C or higher.

[0093] Furthermore, by omitting the cooling step or performing it at a higher temperature than usual, the molding time including the heating step and the cooling step can be shortened, thereby improving the molding cycle property. For example, when a molded article is produced using the fiber structure of the present invention, the molding time including the heating step and the cooling step can be shortened to, for example, 20 minutes or less.

[0094] (Crosslinked molded body) The crosslinked molded article of the present invention comprises at least one of thermoplastic resins A and B as a matrix resin, and is reinforced with reinforcing fibers as necessary. Because thermoplastic resins A and B undergo a crosslinking reaction during heat molding, the molded article having a crosslinked structure (i.e., the crosslinked molded article) can exhibit heat resistance, for example, at temperatures higher than the temperature during heat molding.

[0095] For example, the crosslinked molded article may be heat resistant at 250° C., and preferably at 280° C. The heat resistance at the above temperature can be determined if the crosslinked molded article can maintain its shape when heated by placing the molded article on a plate heater at the target temperature.

[0096] Furthermore, since the crosslinked molded article has excellent heat resistance, it also has a high deflection temperature under load, and the deflection temperature under load of the crosslinked molded article may be, for example, 250° C. or higher, preferably 280° C. or higher, and more preferably 300° C. or higher. There is no particular upper limit to the heat resistance temperature, but it may be 400° C. or lower.

[0097] In the manufacturing process of a molded article, the cooling step can be omitted or can be performed at a higher temperature than usual, which can suppress dimensional changes in the mold caused by thermal changes. In this case, the dimensional accuracy of the obtained crosslinked molded article can be improved. For example, the dimensional accuracy of the crosslinked molded article can be determined by measuring the wall thickness at multiple points of a molded article having a certain thickness and examining the variation in the measured wall thickness.

[0098] The crosslinked molded article of the present invention has a density of 2.00 g / cm 3 Preferably, it is 1.95 g / cm or less. 3 or less, more preferably 1.90 g / cm 3 The lower limit of the density is determined appropriately depending on the material selected, but is, for example, 0.1 g / cm 3 It may be to some extent.

[0099] The crosslinked molded article of the present invention preferably has a thickness of 0.05 mm or more (preferably 0.1 mm or more). It may be more preferably 0.3 mm or more, and even more preferably 0.5 mm or more. The upper limit of the thickness can be appropriately set depending on the thickness required for the molded article, and may be, for example, about 10 mm.

[0100] Furthermore, the crosslinked molded article of the present invention can control dimensional change at high temperatures when expandable reinforcing fibers are present. When such reinforcing fibers are present, the molded article may expand at high temperatures due to the repulsive force of the fibers. However, the crosslinked molded article of the present invention can suppress this expansion due to the crosslinked structure of the resin. The crosslinked molded article of the present invention may, for example, be placed in a hot air oven heated to 260°C and heated for 10 minutes. The dimensional change in the thickness direction (thickness of the thermally crosslinked molded article after heating) may be, expressed as a percentage of the thickness at room temperature (25°C) (thickness of the thermally crosslinked molded article before heating), for example, 150% or less, preferably 145% or less, and more preferably 141% or less.

[0101] The crosslinked molded article of the present invention may be a one-dimensional structure (e.g., a rod-shaped structure) or a two-dimensional structure (e.g., a plate-shaped structure), but because it can be formed via a fiber structure, the degree of freedom in shape is increased and it is useful as a three-dimensional structure. Examples of three-dimensional structures include deep-drawn molded articles, bulged molded articles, flanged molded articles, bent molded articles, and combinations thereof. In all of these molded articles, elongation occurs due to tensile stress, bending stress, etc., and therefore, it is possible to utilize the elongation of the fiber structure to enable good processing. Furthermore, the crosslinked molded article of the present invention may include a complex-shaped region. The complex-shaped region is a region having a three-dimensional shape in the plane direction or thickness direction, and examples thereof include protrusions, recesses, curved portions, portions with varying thickness, ribs, and bosses. For example, the protrusions or recesses may have a cross-sectional shape in which the ratio of the height of the protrusion or the depth of the recess to the maximum width of the protrusion or recess is 0.2 or more.

[0102] The crosslinked molded article of the present invention can be formed into complex shapes, and therefore can be used for a wide range of applications, including parts and housings for personal computers, displays, office automation equipment, mobile phones, personal digital assistants, digital video cameras, optical equipment, audio equipment, air conditioners, lighting equipment, toys, home appliances, electrical and electronic equipment parts, and other electrical and electronic equipment products; interior and exterior members, supports, panels, reinforcing materials and other civil engineering and building materials; various members, frames, hinges, arms, axles, wheel bearings, beams, pillars, supports, and rails for vehicles (bicycles, automobiles, motorcycles, ships, aircraft, etc.); instrument panels, seat frames, door trims, pillar trims, handles, and various modules. They are suitable for use in interior vehicle parts; exterior vehicle parts such as chassis, trays, outer panels or body parts, bumpers, moldings, under covers, engine covers, air deflectors, spoilers, cowl louvers, and aero parts; fuel system, exhaust system, and intake system parts for vehicles such as motor parts, CNG tanks, gasoline tanks, fuel pumps, air intakes, intake manifolds, carburetor main bodies, carburetor spacers, various pipes, and various valves; drone and aircraft parts such as landing gear pods, winglets, spoilers, edges, rudders, elevators, failings, and ribs; and sports and leisure goods such as rackets and fishing rods. [Example]

[0103] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the following examples, various physical properties were measured by the following methods.

[0104] [Birefringence Value] The birefringence value was calculated from the retardation measured using a polarizing microscope "BX53" manufactured by Olympus Corporation equipped with a Berek type compensator under a light source of λ=546.1 nm (e-line) using the following formula: The fiber thickness indicates the fiber diameter. Δn=R / d Δn: birefringence value, R: retardation (nm), d: fiber thickness (nm)

[0105] [Orientation degree] The degree of orientation of the entire molecule was determined from the sound velocity. The sound velocity was measured using a DDV-5-B manufactured by Rheovibron. A fiber bundle with a fiber length of 50 cm was fixed to the device, and a load of 0.1 g / dtex was applied. The sound wave propagation velocity was measured at each point where the distance from the sound source to the detector was 50, 40, 30, 20, and 10 cm, and the sound velocity was calculated from the relationship between distance and propagation time (n=5). The sound velocity, which is an index of the degree of orientation of the entire molecule, was measured, and the degree of orientation ft was calculated using the following formula. ft=1-(Cu / C) 2 Cu: Sound velocity in unoriented PC polymer (km / sec) In the present invention, Cu=1.0. C: Measured speed of sound (km / sec)

[0106] [Average fiber length] The fiber lengths of 100 randomly selected fibers were measured, and the average value was taken as the average fiber length.

[0107] [Average fiber diameter (μm)] A magnified photograph was taken at a predetermined magnification using a scanning electron microscope (SEM), and the average value of the diameters of 100 randomly selected fibers was measured and used as the average fiber diameter.

[0108] [Average particle diameter (μm)] Using a laser diffraction / scattering particle size distribution analyzer (LA-950V2 manufactured by Horiba, Ltd.), the particle group was irradiated with laser light, and the particle size distribution was calculated from the intensity distribution pattern of the diffracted and scattered light emitted from the particle group, and the average particle diameter was calculated.

[0109] [Glass transition temperature Tg (℃), melting point (℃)] The glass transition temperature and melting point of the resin were measured using a Mettler TA3000-DSC in a nitrogen atmosphere by heating the sample to 350°C at a heating rate of 10°C / min. The glass transition temperature was taken as the inflection point on the DSC chart, and the melting point was taken as the endothermic peak temperature.

[0110] [Elongation (%)] The elongation of the fiber structure was measured using a precision universal testing machine (Autograph AGS-D, manufactured by Shimadzu Corporation). Test pieces 50 mm wide and 200 mm long were taken, and the distance between the gripping parts was set to 100 mm. The ends of each test piece were fixed with the gripping parts and pulled at a rate of 100 mm / min until breakage. The average test force at break was taken as the breaking strength, and the percentage of the distance traveled divided by the distance between the gripping parts (100 mm) was taken as the elongation.

[0111] [Formability evaluation] The moldability was evaluated based on the molding temperature, and was evaluated as ◯ when moldable at 280°C, and x when not moldable at 280°C.

[0112] [Heat resistance] The test sample was placed on a plate heater heated to 280°C, and the shape of the test sample was visually checked after 2 minutes. If the test sample did not melt and its shape was maintained, it was evaluated as ◯, and if the test sample melted and its shape was not maintained, it was evaluated as ×.

[0113] [Evaluation of deflection temperature under high temperature] The samples were cut into a length of 80 mm, a width of 10 mm, and a thickness of 4 mm, and the deflection temperature under load was measured in a flatwise test at a load of 1.8 MPa using an S-3M HDT tester (manufactured by Toyo Seiki Seisakusho Co., Ltd.) with reference to ISO75A-f.

[0114] [Dimensional change in thickness direction before and after heating] The thickness of the sample at 25°C before heating was measured, and then the sample was placed in a hot air oven heated to 260°C and heated for 10 minutes. The dimensional change rate in the thickness direction was then calculated from the thickness of the sample before heating and the thickness of the sample after heating according to the following formula. Dimensional change rate in the thickness direction (%) = sample thickness after heating (mm) / sample thickness before heating (mm) × 100

[0115] [Handling evaluation] During the process of setting the fiber structure in the mold, the presence or absence of fibers and / or powder falling off from the fiber structure was visually confirmed, and the evaluation was made as ◯ if no falling off occurred and × if falling off occurred.

[0116] [Molding cycle] The molding time, which was the total time for the heating and cooling steps, was measured, and evaluation was performed by rating a good result if the molding time was within 20 minutes, and rating an unsatisfactory result if the molding time exceeded 20 minutes.

[0117] [Example 1] (1) Preparation of amorphous epoxy fibers Amorphous epoxy resin with a weight average molecular weight of 60,000, a glass transition temperature of 84°C, and a shear rate of 1,000 sec at 300°C. -1 A bisphenol A (BPA)-type phenoxy resin (YP-50s, manufactured by Nippon Steel Chemical & Material Co., Ltd.) with a melt viscosity of 890 poise was used. This resin was melt-extruded using a twin-screw extruder and discharged from a 0.2 mm diameter x 100 hole round nozzle at a spinning temperature of 300°C. The ratio of discharge speed to winding speed (draft) was adjusted to 37.1, and the fiber was wound at a winding speed of 167 m / min. The resulting amorphous epoxy fiber had a birefringence value of 0.00146, an average fiber diameter of 33 μm, and a Tg of 84°C.

[0118] (2) Preparation of polycarbonate fibers The polycarbonate resin used had a weight-average molecular weight of 52,300 and a glass transition temperature of 145°C. This resin was melt-extruded using a twin-screw extruder and discharged from a 0.2 mmΦ x 100-hole round-hole nozzle at a spinning temperature of 320°C. The ratio of discharge speed to winding speed (draft) was adjusted to 143, and the fiber was wound at a winding speed of 1,500 m / min. The resulting polycarbonate fiber had a degree of orientation of 0.57, an average fiber diameter of 15 μm, and a Tg of 145°C. (3) Fabrication of fiber structures 20 parts by weight of the amorphous epoxy fiber obtained in (1) (filaments were crimped and then cut to a fiber length of approximately 51 mm and used), 30 parts by weight of the polycarbonate fiber obtained in (2) (filaments were crimped and then cut to a fiber length of approximately 51 mm and used), and 50 parts by weight of glass fiber (manufactured by Nippon Electric Glass Co., Ltd.: average fiber diameter 14 μm, filaments were cut to a fiber length of 51 mm and used) as a reinforcing fiber were needle-punched to a weight of 650 g / m 2 A dry nonwoven fabric of this size was obtained as the fiber structure. (4) Preparation of cross-linked molded body Five sheets of the fiber structure obtained in (3) were stacked and placed in a mold (250 mm square), and subjected to a pressure of 5 N / mm at 280°C. 2 The fiber structure was press-molded under a pressure of 1000 kJ / cm2, and the mold was then cooled to 220°C to obtain a molded product with a thickness of 2 mm. The cooling process was completed when the mold pressure was released and the molded product no longer expanded after removal. The molded product had a good appearance, with no surface roughness, uneven thickness, shrinkage, or warping. The resulting fiber structure and molded product were evaluated, and the results are shown in Table 1.

[0119] [Example 2] A woven fabric having a basis weight of 650 g / m was prepared by the needle punch method in the same manner as in Example 1, except that the amount of amorphous epoxy fiber was 40 parts by weight and the amount of polycarbonate fiber was 10 parts by weight. 2 A fiber structure was produced as a dry nonwoven fabric, and then a molded article was obtained. The molded article had a good appearance without surface roughness, uneven thickness, shrinkage, or warping. The fiber structure and molded article were evaluated, and the results are shown in Table 1.

[0120] [Example 3] A spunbonded ... 2 A fiber structure was produced as a dry nonwoven fabric, and then a molded article was obtained. The molded article had a good appearance without surface roughness, uneven thickness, shrinkage, or warping. The fiber structure and molded article were evaluated, and the results are shown in Table 1.

[0121] [Example 4] The composition consisted of 40 parts by weight of the amorphous epoxy fiber obtained in (1) of Example 1 (filaments were cut to a fiber length of 13 mm), 10 parts by weight of the polycarbonate fiber obtained in (2) (filaments were cut to a fiber length of 13 mm), and glass fiber (manufactured by Nippon Electric Glass Co., Ltd.: average fiber diameter 11 μm, fiber length 13 mm, specific gravity 2.5 g / cm) as a reinforcing fiber. 3 ) 50 parts by weight of a slurry containing 160 g / m by a wet laid process. 2 A wetlaid nonwoven fabric (mixed paper) of this type was obtained as a fiber structure. 20 sheets of this fiber structure were stacked together, placed in a mold (250 mm square), and subjected to a pressure of 5 N / mm at 280°C. 2 The mold was then cooled to 220°C to obtain a molded product with a thickness of 2 mm. The molded product had a good appearance, with no surface roughness, uneven thickness, shrinkage, or warping. The obtained fiber structure and molded product were evaluated, and the results are shown in Table 1.

[0122] [Example 5] A woven fabric having a basis weight of 160 g / m was produced by a wet laid process in the same manner as in Example 4, except that the amount of amorphous epoxy fiber was 20 parts by weight and the amount of polycarbonate fiber was 30 parts by weight. 2 A fiber structure was produced as a wet-laid nonwoven fabric, and then a molded article was obtained. The obtained molded article had a good appearance without surface roughness, uneven thickness, shrinkage, or warping. The obtained fiber structure and molded article were evaluated, and the results are shown in Table 1.

[0123] [Example 6] A woven fabric having a basis weight of 150 g / m was produced by a wet laid process in the same manner as in Example 5, except that the reinforcing fibers were carbon fibers (manufactured by Teijin Limited: average fiber diameter 7 μm, fiber length 13 mm). 2 A fiber structure was produced as a wet-laid nonwoven fabric, and then a molded article was obtained. The obtained molded article had a good appearance without surface roughness, uneven thickness, shrinkage, or warping. The obtained fiber structure and molded article were evaluated, and the results are shown in Table 1.

[0124] [Example 7] A fiber structure was produced in the same manner as in Example 1, except that the amorphous epoxy fiber, polycarbonate fiber, and reinforcing fiber were 35 parts by weight, 35 parts by weight, and 30 parts by weight, respectively, and then a molded article was obtained. The molded article obtained had a good appearance without surface roughness, uneven thickness, shrinkage, or warpage. The obtained fiber structure and molded article were evaluated, and the results are shown in Table 1.

[0125] [Example 8] An amorphous epoxy fiber was obtained in the same manner as in Example 1, except that the ratio of the discharge speed to the take-up speed (draft) was adjusted to 18.6, the fiber was taken up at a take-up speed of 167 m / min, and the fiber was further drawn at a drawing temperature of 100°C, a drawing speed of 12 m / min, and a draw ratio of 1.5 to obtain a fiber. The obtained amorphous epoxy fiber had a birefringence value of 0.00351, an average fiber diameter of 25 μm, and a Tg of 84°C. A fiber having a basis weight of 650 g / m was obtained by needle punching in the same manner as in Example 1, except that the amorphous epoxy fiber was used. 2 A fiber structure was produced as a dry nonwoven fabric, and then a molded product was obtained. The obtained molded product had some surface roughness and uneven thickness, but no shrinkage or warping was observed overall, and the appearance was relatively good. The obtained fiber structure and molded product were evaluated, and the results are shown in Table 1.

[0126] [Example 9] An amorphous epoxy fiber was obtained in the same manner as in Example 1, except that the ratio of the discharge speed to the take-up speed (draft) was adjusted to 18.6, the fiber was taken up at a take-up speed of 167 m / min, and the fiber was further drawn at a drawing temperature of 100°C, a drawing speed of 12 m / min, and a draw ratio of 1.75 to obtain a fiber. The birefringence value of the obtained amorphous epoxy fiber was 0.00809, the average fiber diameter was 36 μm, and the Tg was 84°C. Except for using this amorphous epoxy fiber, a fiber having a basis weight of 650 g / m was obtained by needle punching in the same manner as in Example 1. 2 A fiber structure was produced as a dry nonwoven fabric, and then a molded product was obtained. The molded product did not show any shrinkage or warping as a whole, but had a rough surface and uneven thickness. The fiber structure and molded product were evaluated, and the results are shown in Table 1.

[0127] [Comparative Example 1] A wet-laid nonwoven fabric was obtained by a wet-laid process using a slurry containing 50 parts by weight of glass fiber (manufactured by Nippon Electric Glass Co., Ltd.: average fiber diameter 11 μm, fiber length 13 mm) in the same manner as in Example 5, except that the amorphous epoxy fiber and polycarbonate fiber were not included. Next, 20 parts by weight of amorphous epoxy resin and 30 parts by weight of polycarbonate resin were prepared, and each was pulverized to obtain powder with an average particle diameter of 60 μm. The powder was then blended in a dry powder mixer, and the entire amount was applied to the wet nonwoven fabric to obtain a basis weight of 160 g / m. 2 A fiber structure was produced. Twenty sheets of the resulting fiber structure were stacked together, placed in a mold (250 mm square), and subjected to a pressure of 5 N / mm at 280°C. 2 The mold was then cooled to 220° C. to obtain a molded article with a thickness of 2 mm. The obtained fiber structure and molded article were evaluated, and the results are shown in Table 1.

[0128] Comparative Example 2 A fiber structure was produced in the same manner as in Example 1, except that the amounts of amorphous epoxy fiber were 0 part by weight, polyetherimide fiber (manufactured by Kuraray Co., Ltd.: average fiber diameter 15 μm, fiber length as crimped fiber approximately 51 mm), and reinforcing fiber were 50 parts by weight, and then a molded product was obtained in the same manner as in Example 1, except that the molding temperature was 340° C. and the cooling temperature was 180° C. The obtained fiber structure and molded product were evaluated, and the results are shown in Table 1.

[0129] Comparative Example 3 A fiber structure was produced in the same manner as in Example 1, except that 20 parts by weight of amorphous epoxy fiber, 30 parts by weight of polyetherimide fiber (manufactured by Kuraray Co., Ltd.: average fiber diameter 15 μm, fiber length as crimped fiber approximately 51 mm), and 50 parts by weight of reinforcing fiber were used, and then a molded article was obtained in the same manner as in Comparative Example 2. The obtained molded article had a good appearance, with no surface roughness, uneven thickness, shrinkage, or warping. The obtained fiber structure and molded article were evaluated, and the results are shown in Table 1.

[0130] [Table 1]

[0131] As shown in Table 1, in Examples 1 to 9, the fiber structures were all easy to handle when molding into molded articles, and furthermore, the molding cycle was also excellent. Furthermore, although the molding temperature for processing the fiber structure into a molded article is 280° C., the molded article after molding exhibits heat resistance even when the temperature rises to the molding temperature of 280° C. Furthermore, in the measurement of the deflection temperature under load, all of the molded articles had a deflection temperature under load of 280° C. or higher, and in particular, in Examples 1, 3, and 5-9, the deflection temperature exceeded 300° C. Furthermore, since not only the reinforcing fibers but also at least one of the thermoplastic resins A and B is a fiber, the fiber structure can be stretched when used, and in particular, the elongation of a dry fiber structure can be improved. Furthermore, compared to Comparative Examples 2 and 3, in which no thermal crosslinking reaction was performed, in all Examples, the change in thickness before and after heating can be reduced, and dimensional change at high temperatures can be controlled.

[0132] On the other hand, in Comparative Example 1, since both thermoplastic resins A and B were in powder form, even though a fiber structure was formed from the reinforcing fibers, some material fell off when the fiber structure was carried or cut to an appropriate size, making it difficult to handle. Also, in Comparative Example 1, it was not possible to test the elongation of the fiber structure. In Comparative Examples 2 and 3, thermoplastic resin B is a polyetherimide resin that is not crosslinked with thermoplastic resin A. Therefore, even though the molding temperature is as high as 340°C, the molded articles do not exhibit heat resistance at 280°C, because this temperature exceeds the glass transition temperature of 217°C. In addition, the deflection temperature under load of all molded articles is significantly reduced compared to the Examples. [Industrial Applicability]

[0133] The fiber structure of the present invention can be suitably used in a variety of applications. Furthermore, a crosslinked molded article formed by thermally crosslinking the thermoplastic resin in the fiber structure of the present invention to form a matrix not only has improved heat resistance due to the crosslinked structure, but can also be usefully formed into objects with complex shapes. Therefore, the fiber structure can be used extremely effectively as, for example, housings for electrical and electronic devices, parts for civil engineering and building materials, vehicle components, sports and leisure goods, etc.

[0134] While the preferred embodiments of the present invention have been described above, those skilled in the art will readily envision various changes and modifications within the scope of the present invention, as understood from the specification. Accordingly, such changes and modifications are to be construed as falling within the scope of the invention as defined by the claims.

Claims

1. The thermoplastic resin composition comprises at least thermoplastic resins A and B which are thermally crosslinkable with each other, the thermoplastic resin A is an amorphous epoxy resin, the thermoplastic resin B is a polycarbonate-based resin, At least one of the thermoplastic resins A and B has a fibrous shape, the thermoplastic resin B contains polycarbonate-based fibers having an orientation degree of less than 0.70, A fiber structure in which the proportion of fibers in the fiber structure is 80% by weight or more.

2. A thermoplastic resin composition comprising at least thermoplastic resins A and B which are thermally crosslinkable with each other, the thermoplastic resin A is an amorphous epoxy resin, At least one of the thermoplastic resins A and B has a fibrous shape, the thermoplastic resin A contains an amorphous epoxy fiber having a birefringence value of 0.005 or less, A fiber structure in which the proportion of fibers in the fiber structure is 80% by weight or more.

3. A thermoplastic resin composition comprising at least thermoplastic resins A and B which are thermally crosslinkable with each other, the thermoplastic resin A is an amorphous epoxy resin, At least one of the thermoplastic resins A and B has a fibrous shape, It has a nonwoven fabric shape, A fiber structure in which the proportion of fibers in the fiber structure is 80% by weight or more.

4. A thermoplastic resin composition comprising at least thermoplastic resins A and B which are thermally crosslinkable with each other, the thermoplastic resin A is an amorphous epoxy resin, At least one of the thermoplastic resins A and B has a fibrous shape, The elongation is 1% or more, A fiber structure in which the proportion of fibers in the fiber structure is 80% by weight or more.

5. The fiber structure according to any one of claims 1 to 4, wherein both the thermoplastic resins A and B have a fibrous shape.

6. 5. The fiber structure according to claim 1, wherein a content ratio of the thermoplastic resin A to the thermoplastic resin B is 30 / 70 to 90 / 10 by weight.

7. 5. The fiber structure according to claim 1, wherein the glass transition temperature of the thermoplastic resin A is lower than the softening point of the thermoplastic resin B, and the temperature difference therebetween is 40° C. or more.

8. 5. The fiber structure according to claim 1, wherein the thermoplastic resin B is a polycarbonate-based resin.

9. The fiber structure according to any one of claims 1 to 4, further comprising reinforcing fibers.

10. 10. The fiber structure according to claim 9, wherein a weight ratio of the total amount of the thermoplastic resin A and the thermoplastic resin B to the reinforcing fibers is 70 / 30 to 25 / 75.

11. 10. The fiber structure according to claim 9, wherein, when the fiber diameter of the reinforcing fiber in the fiber structure is 100, the fiber diameter of the fiber made of at least one of thermoplastic resins A and B is 5 to 3500.

12. a preparation step of preparing the fiber structure according to any one of claims 1 to 4; a heat molding step of stacking one or more of the fiber structures and heating them at a temperature equal to or higher than the flow initiation temperature of thermoplastic resins A and B; A method for producing a crosslinked molded article, comprising at least the steps of:

13. The method for producing a crosslinked molded article according to claim 12, wherein the heat-molding step is carried out using a mold having a three-dimensional shape.

14. The method for producing a crosslinked molded article according to claim 12, wherein the heat-molding step is carried out by a heat treatment at 300°C or less.

15. The method for producing a crosslinked molded article according to claim 14, wherein the cooling step is carried out at a temperature of (HT-80) to (HT-0) °C, which is 0 to 80 °C lower than the heating temperature HT of the hot molding step.

16. A crosslinked molded article of the fiber structure according to any one of claims 1 to 4, wherein the crosslinked molded article has a deflection temperature under load of 250°C or higher.

17. 17. The crosslinked molded article according to claim 16, which has a complex shaped region.

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