Molding material and molded article

Abstract

A molding material containing a reinforcing fiber bundle (A) and a polyphenylene sulfide (B) having a melting point of 270°C or lower, and a molded article containing a reinforcing fiber having a weight average fiber length of 0.3 mm or more and 3.0 mm or less and a polyphenylene sulfide having a melting point of 270°C or lower or a polyphenylene sulfide having a crystallization temperature upon cooling of 190°C or lower. Since the generation of gas derived from the reinforcing fiber bundle and the binder at the time of molding processing can be reduced, the surface roughness of the molded article caused by the gas can be suppressed, and thus a molding material having both the surface smoothness and the mechanical properties of the molded article can be obtained.

Description

Technical Field

[0001] This invention relates to molding materials comprising reinforcing fiber bundles and polyphenylene sulfide, and molded articles comprising reinforcing fibers and polyphenylene sulfide. Background Technology

[0002] As molding materials using continuous reinforcing fiber bundles and thermoplastic resins as the matrix, thermoplastic prepregs, filaments, glass mats (GMT), and other diverse forms are well-known. Such molding materials possess the following characteristics: they are easy to mold by leveraging the properties of thermoplastic resins, or do not require the storage burden of thermosetting resins; furthermore, the resulting molded articles exhibit high toughness and excellent recyclability. In particular, molding materials processed into granules can be applied to economical and productive molding methods such as injection molding and stamping, making them useful as industrial materials.

[0003] Patent documents 1 and 2 disclose methods for obtaining molded articles with high mechanical properties by injection molding a molding material composed of continuous reinforcing fiber bundles and polyphenylene sulfide resin. On the other hand, patent document 3 discloses a method for improving the adhesion to epoxy resin while maintaining heat resistance and mechanical properties for polyarylene sulfide containing para-arylene sulfide units, meta-arylene sulfide units, and fillers.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2012-158746

[0007] Patent Document 2: Japanese Patent Application Publication No. 2012-158747

[0008] Patent Document 3: Japanese Patent Application Publication No. 8-269200 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] In the future, the miniaturization, thinning, and increasing complexity of molded products will place higher demands on the formability and appearance properties (the smoothness of the surface of the molded product after molding) of the molding materials.

[0011] On the other hand, when molding materials, if gas is generated from the molding materials, it can sometimes impair the formability and appearance characteristics. In particular, when molding small, thin-walled, and complex shapes as described above, even a very small amount of gas can sometimes have a significant impact on formability, dimensional accuracy, and appearance characteristics.

[0012] On the other hand, in order to impart high mechanical properties to molded articles, the molding materials constituting the molded articles need to contain reinforcing fiber bundles.

[0013] However, to date, there has been absolutely no attention paid to the gases generated from the reinforcing fiber bundles and their bundle-gathering agents, and no research has been conducted to reduce these gases. This can be attributed to the fact that the amount of gas generated from the reinforcing fiber bundles and their bundle-gathering agents is so small that there is no need to reduce it.

[0014] That is, for molding materials containing reinforcing fiber bundles, no molding material has yet been found that maintains good formability, dimensional accuracy, and appearance characteristics even when molded into small, thin-walled, and complex shapes.

[0015] The present invention addresses the issue of the above-mentioned realities, and more specifically, provides a molding material that combines excellent surface smoothness and mechanical properties of the molded article by reducing the generation of gas during molding and suppressing surface roughness of the molded article.

[0016] Methods for solving problems

[0017] To address the aforementioned issues, the present invention has the following configuration.

[0018] [1] A molding material comprising reinforcing fiber bundles (A) and polyphenylene sulfide (B), wherein the polyphenylene sulfide (B) has a melting point below 270°C.

[0019] [2] According to the molding material described in [1], the polyphenylene sulfide (B) comprises p-phenylene sulfide units and m-phenylene sulfide units, wherein the content of the m-phenylene sulfide unit is 7 mol% or more relative to the total amount of p-phenylene sulfide units and m-phenylene sulfide units.

[0020] [3] The molding material according to [1] or [2] is a long fiber particle.

[0021] [4] In any one of [1] to [3], the reinforcing fiber bundles (A) are arranged parallel to each other along the axial direction of the molding material, and the length of the reinforcing fiber bundles (A) is substantially the same as the length of the molding material.

[0022] [5] According to any one of [1] to [4], the cooling crystallization temperature of the above polyphenylene sulfide (B) is below 190°C.

[0023] [6] According to any one of [1] to [5], the difference between the cooling crystallization temperature and the melting point of the above polyphenylene sulfide (B) is 80°C or more.

[0024] [7] The molding material according to any one of [1] to [6] is a molding material comprising the above-mentioned polyphenylene sulfide (B) and a composite, the composite being composed of the above-mentioned reinforcing fiber bundle (A) and resin (C), the resin (C) being one or more resins selected from epoxy resin, phenolic resin and terpene resin, the composite being coated with the above-mentioned polyphenylene sulfide (B).

[0025] [8] The reinforcing fiber constituting the above-mentioned reinforcing fiber bundle (A) is carbon fiber, according to any one of [1] to [7] molding materials.

[0026] [9] The molding material according to any one of [1] to [8] has a bundle binder attached to the above-mentioned reinforcing fiber bundle (A).

[0027]

[10] A molded article comprising reinforcing fibers and polyphenylene sulfide, wherein the weight-average fiber length of the reinforcing fibers is 0.3 mm or more and 3.0 mm or less, and the melting point of the polyphenylene sulfide is 270°C or less.

[0028]

[11] A molded article comprising reinforcing fibers and polyphenylene sulfide, wherein the weight-average fiber length of the reinforcing fibers is 0.3 mm or more and 3.0 mm or less, and the cooling crystallization temperature of the polyphenylene sulfide is 190°C or less.

[0029]

[12] According to the molded article described in

[11] , the melting point of the above polyphenylene sulfide is below 270°C.

[0030]

[13] The molded article according to any one of

[10] to

[12] , wherein the polyphenylene sulfide comprises p-phenylene sulfide units and m-phenylene sulfide units, and the content of the m-phenylene sulfide units is 7 mol% or more relative to the total amount of p-phenylene sulfide units and m-phenylene sulfide units.

[0031]

[14] The molded article according to any one of

[10] to

[13] , wherein the polyphenylene sulfide comprises homopolymer polyphenylene sulfide consisting only of p-phenylene sulfide units and copolymer polyphenylene sulfide consisting of p-phenylene sulfide units and m-phenylene sulfide units.

[0032] The effects of the invention

[0033] According to the present invention, since the generation of gas from reinforcing fiber bundles and bundle binders during molding can be reduced, surface roughness of the molded article caused by gas can be suppressed, thus obtaining a molding material that combines the surface smoothness and mechanical properties of the molded article.

[0034] The molding material of the present invention can suppress the generation of gas from the reinforcing fiber bundles and the bundle binder during the molding process. In addition, the reinforcing fibers are well dispersed into the molded article during injection molding, and it is easy to manufacture molded articles with excellent mechanical properties. Therefore, it is not limited to molding methods such as injection molding, transfer molding, blow molding, and insert molding, but can also be applied to a wide range of molding methods such as plunger molding, compression molding, and stamping.

[0035] Examples of molded articles obtained by molding the molding material of the present invention include automotive parts such as thrust washers, oil filters, seals, bearings, gears, cylinder head covers, bearing retainers, intake manifolds, and pedals; semiconductor / liquid crystal manufacturing equipment parts such as silicon wafer carriers, IC chip trays, electrolytic capacitor trays, and insulating films; compressor parts such as pumps, valves, and seals; industrial machinery parts such as aircraft cabin interior parts; medical device parts such as sterilization equipment, columns, and piping; and food / beverage manufacturing equipment parts. Furthermore, the molding material of the present invention can relatively easily produce molded articles with thin walls of 0.5 to 2 mm. Examples of materials requiring such thin-walled molding include, for instance, electrical / electronic equipment components such as housings used in personal computers and mobile phones, and keyboard supports that support the keyboard inside a personal computer. For such electrical / electronic equipment components, when conductive carbon fiber is used as the reinforcing fiber, electromagnetic wave shielding is imparted, making it suitable. Attached Figure Description

[0036] Figure 1 A schematic diagram illustrating an example of the shape of the axial cross-section of a preferred embodiment of the molding material of the present invention.

[0037] Figure 2 A schematic diagram illustrating another example of the shape of the axial cross-section of a preferred embodiment of the molding material of the present invention.

[0038] Figure 3 A schematic diagram illustrating an example of the shape of a cross section orthogonal to the axis of a preferred embodiment of the molding material of the present invention.

[0039] Figure 4 A schematic diagram illustrating another example of the shape of a cross section orthogonal to the axis of the preferred embodiment of the molding material of the present invention.

[0040] Figure 5 A schematic diagram illustrating a further example of the shape of a cross section orthogonal to the axis of the preferred embodiment of the molding material of the present invention.

[0041] Figure 6 This is a three-dimensional perspective view of the interior of a typical long fiber particle (schematic diagram).

[0042] Figure 7 This is a three-dimensional perspective view of the interior of a typical short fiber particle (schematic diagram). Detailed Implementation

[0043] The present invention will now be described in detail along with its embodiments.

[0044] <Molding Materials>

[0045] The molding material of the present invention comprises reinforcing fiber bundles (A) and polyphenylene sulfide (B). By including reinforcing fiber bundles (A), the fiber length of the reinforcing fibers can be maintained at a long length, thereby exhibiting excellent mechanical properties.

[0046] The molding material of the present invention preferably comprises polyphenylene sulfide (B) and a composite, which is composed of reinforcing fiber bundles (A) and resin (C). The resin (C) is preferably one or more resins selected from epoxy resins, phenolic resins, and terpene resins. Furthermore, in the molding material of the present invention, the composite is preferably coated with polyphenylene sulfide (B). That is, it is preferably a form in which the composite composed of reinforcing fiber bundles (A) and resin (C) (impregnating resin) selected from epoxy resins, phenolic resins, and terpene resins is coated with polyphenylene sulfide (B).

[0047] The workability of the molding material is improved by coating the composite with polyphenylene sulfide (B). The molding material of the present invention is compounded, for example, by injection molding to become the final molded article. From the perspective of the workability of the molding material, it is important that the composite and the polyphenylene sulfide resin do not separate until molding, and that the morphology described above (the morphology of the composite being coated with polyphenylene sulfide (B)) is maintained. Since the composite (especially the reinforcing fiber bundles) and the polyphenylene sulfide resin are completely different in shape (size, aspect ratio), specific gravity, and mass, if the molding material separates into the reinforcing fiber bundles and the polyphenylene sulfide resin during material transfer in the molding process, or if the separated components are graded, the flowability of the molding material during molding may decrease, or the mechanical properties of the molded article may deviate, or the surface of the molded article may become rough, resulting in reduced surface smoothness.

[0048] Furthermore, here, the term "composite" refers to a composite in which the spaces between the individual fibers of the reinforcing fiber bundle (A) are filled with resin (C) (hereinafter, the resin (C) is sometimes referred to as "impregnated resin"). In other words, it is a composite in which the resin (C) is impregnated between the individual fibers of the reinforcing fiber bundle (A). That is, it is a composite in which the reinforcing fibers are dispersed like islands in a sea of ​​impregnated resin.

[0049] It is desirable that the reinforcing fiber bundle (A) is completely impregnated with the impregnating resin, but a certain degree of porosity may also exist in the composite consisting of the reinforcing fiber bundle (A) and the impregnating resin. Such porosity is preferably in the range of 0 to 40% or less. More preferably, it is 0 to 20% or less. If the porosity is within this range, the impregnation / fiber dispersion promotion effect is excellent. The porosity is determined in portions of the composite using the ASTM 2734 (1997) test method.

[0050] Furthermore, there are no particular limitations on the coating form; examples include a form in which polyphenylene sulfide (B) is coated around a portion or all of the periphery of the strip-shaped composite. In such a form, a form in which more than 50% of the periphery of the strip-shaped composite is coated is preferred, a form in which more than 80% of the periphery of the strip-shaped composite is coated is more preferred, and a form in which the entire periphery of the strip-shaped composite is coated with polyphenylene sulfide (B) is most preferred.

[0051] If the composite is bonded to polyphenylene sulfide (B), there are no particular restrictions on the state of the boundary between the composite and the polyphenylene sulfide (B). However, it is preferable that the polyphenylene sulfide (B) partially enters into a part of the composite near the boundary and is compatible with the impregnated resin in the composite, or that it is impregnated in the reinforcing fiber bundle (A). In such a state, the coated polyphenylene sulfide (B) is not easily peeled off from the composite, resulting in a molding material with good workability. Stable feeding during molding reduces gas generation, achieves uniform plasticization, and exhibits excellent flowability.

[0052] The molding material of the present invention is preferably in granular shape, and is long fiber granules. Long fiber granules refer to resin materials containing reinforcing fibers of substantially the same length as the granule length along substantially the same direction. Generally, compared to short fiber granules, long fiber granules result in longer fiber lengths in the molded article, thus exhibiting superior mechanical properties. On the other hand, long fiber granules tend to have significantly poor formability (flowability). In particular, when polyphenylene sulfide is used as the thermoplastic resin, this tendency is significant due to the high molding temperature of polyphenylene sulfide, which leads to a rapid crystallization rate. Here, if the molding temperature is increased to improve formability (flowability), the amount of gas from the reinforcing fiber bundles and the binder increases during molding, resulting in a decrease in the appearance characteristics (surface smoothness) of the molded article.

[0053] However, even if the molding material is long fiber particles and the thermoplastic resin used is polyphenylene sulfide, the molding process can be carried out at a low molding temperature by adopting the solution of the present invention, that is, by using polyphenylene sulfide with a melting point below 270°C. As a result, while maintaining excellent mechanical properties, the generation of gases from the reinforcing fiber bundles and bundle binders during molding can be significantly suppressed, and the formability (flowability) can be significantly improved.

[0054] It should be noted that short fiber particles refer to resin materials in which reinforcing fibers are randomly dispersed in thermoplastic resin. Figure 6 The image shows a three-dimensional perspective view of the interior of long fiber particles (schematic diagram) (in the image, symbol 1 represents the reinforcing fiber bundle (A), and symbol 2 represents polyphenylene sulfide (B).) Figure 7 The image shows a three-dimensional perspective view of the interior of short fiber particles (schematic diagram) (in the diagram, symbol 2 represents polyphenylene sulfide (B), and symbol 3 represents reinforcing fiber). Furthermore, long fiber particles can be produced using known methods.

[0055] In the molding material of the present invention, it is preferable that the reinforcing fiber bundles (A) are arranged parallel to each other along the axial direction of the molding material (preferably granules), and the length of the reinforcing fiber bundles (A) is substantially the same as the length of the molding material. Here, "parallel to each other" means that the axis of the long axis of the reinforcing fiber bundle (A) and the axis of the long axis of the molding material point in the same direction, and the angle misalignment between the axes is preferably 20° or less, more preferably 10° or less, and even more preferably 5° or less. Furthermore, "substantially the same length" means, for example, in granular molding materials, that the reinforcing fiber bundles (A) are not cut off midway within the granules, or that there are substantially no reinforcing fiber bundles (A) that are significantly shorter than the total length of the granules. In particular, although the amount of reinforcing fiber bundles (A) shorter than the total length of the granules is not specified, if the content of reinforcing fibers with a length of 50% or less of the total length of the granules is 30% by mass or less, it is evaluated as substantially not containing reinforcing fiber bundles (A) that are significantly shorter than the total length of the granules. Further, the content of reinforcing fibers with a length of 50% or less of the total length of the granules is preferably 20% by mass or less. It should be noted that the so-called total particle length refers to the length of the particle in the direction parallel to the orientation direction of the reinforcing fibers within the particle. By having the reinforcing fiber bundle (A) have a length substantially the same as the molding material, the reinforcing fiber length in the molded product can be long, resulting in excellent mechanical properties.

[0056] There are no particular limitations on the length of the molding material; even in a continuous, long strip state, it can be used depending on the molding method. For example, as a thermoplastic filament prepreg, it can be wound onto a mandrel while being heated to obtain a rolled molded article. Furthermore, by heating / melting multiple strips of the molding material of the present invention together in one direction, a unidirectional thermoplastic prepreg can also be produced. On the other hand, from an operability point of view, the molding material is preferably long fiber particles of 1 to 50 mm. More preferably, it is 3 to 20 mm, and most preferably, it is 5 to 10 mm. By producing long fiber particles of such length, highly versatile injection molding particles can be produced, which can significantly improve operability during molding, achieve stable feeding during molding, and thus reduce gas generation.

[0057] Figures 1-2 This diagram schematically illustrates the shape of the axial cross-section of the molding material of the present invention. Figures 3-5 A diagram illustrating the shape of a cross section of the molding material of the present invention in a direction orthogonal to the axis.

[0058] The shape of the cross-section of the molding material is not limited to the shape shown in the figure, but is preferably as shown in the figure for the axial direction section. Figure 1 As shown, the preferred configuration is one in which reinforcing fiber bundles (A) are used as the core material and are sandwiched in layers of polyphenylene sulfide (B).

[0059] Furthermore, such as a section perpendicular to the axis. Figures 3-5 As shown, it is preferable that the reinforcing fiber bundle (A) forms the core structure and the polyphenylene sulfide (B) forms the sheath structure. The molding material is preferably configured as a core-sheath structure surrounding the reinforcing fiber bundle (A) coated with the aforementioned polyphenylene sulfide (B). By producing a molding material with such a structure, the reinforcing fiber bundles can remain longer in the molded article during molding, thereby improving the mechanical properties that are an effect of the present invention. Furthermore, a multi-core sheath structure can be configured where multiple reinforcing fiber bundles (A) are coated with polyphenylene sulfide (B). In this case, the number of reinforcing fiber bundles (A) is preferably two or more and six or less. It should be noted that when the molding material comprises a composite of the aforementioned reinforcing fiber bundles (A) and resin (C), the term "reinforcing fiber bundle (A)" is replaced with "composite." Figures 1-6 The term "1: Reinforcing fiber bundle (A)" has been replaced with "complex".

[0060] The molding material can be obtained by methods such as injection molding or compression molding, by compounding polyphenylene sulfide (B) in a composite consisting of reinforcing fiber bundles (A) and impregnated resin. From the perspective of the operability of the molding material, it is preferable that the composite and polyphenylene sulfide (B) remain together until molding, maintaining the morphology of the composite coated with polyphenylene sulfide (B). Since the impregnated resin has a low molecular weight, it is often a brittle and easily broken solid. Therefore, it is desirable to configure the polyphenylene sulfide (B) in a way that protects the composite, preventing the impregnated resin from breaking and scattering due to material handling, impacts during operation, or friction until molding.

[0061] [Reinforcing fiber bundles (A)]

[0062] In this invention, the reinforcing fiber bundle (A) refers to a state in which single fibers are arranged in one direction. Examples of the form of the reinforcing fiber bundle (A) include unidirectional fiber bundles, bidirectional fiber bundles, and multidirectional fiber bundles, but from the viewpoint of productivity in manufacturing molding materials, unidirectional fiber bundles are more preferable. Since a higher number of single filaments in the reinforcing fiber bundle (A) is more economical, a single fiber count of 10,000 or more is preferred. On the other hand, since a higher number of single filaments tends to be detrimental to the impregnation properties of the matrix resin, from the viewpoint of achieving both economy and impregnation properties, a count of 15,000 or more and 100,000 or less is more preferable, and a count of 20,000 or more and 50,000 or less is particularly preferred.

[0063] There are no particular limitations on the type of reinforcing fibers constituting the reinforcing fiber bundle (A). Examples of fibers that can be used include carbon fiber, glass fiber, aramid fiber, alumina fiber, silicon carbide fiber, boron fiber, metal fiber, natural fiber, and mineral fiber. One or more of these fibers can be used. From the viewpoint of obtaining lightweight molded articles with high strength and high modulus of elasticity, carbon fibers based on PAN (polyacrylonitrile), pitch, or rayon are preferred. In particular, from the viewpoint of high strength, reinforcing fibers with a tensile strength of 4,000 MPa or higher are preferred, more preferably 5,000 MPa or higher. From the viewpoint of high modulus of elasticity, reinforcing fibers with a tensile modulus of elasticity of 200 GPa or higher are preferred, more preferably 400 GPa or higher. In particular, reinforcing fibers with an elastic modulus of 400 GPa or higher, which are difficult to maintain in terms of fiber length, are preferred because they can better exhibit the effects of the molding material of the present invention described later.

[0064] Furthermore, from the viewpoint of improving the economy of the resulting molded article, glass fiber is preferred, and in particular, the combination of carbon fiber and glass fiber is preferred from the perspective of balancing mechanical properties and economy. Further, from the viewpoint of improving the impact absorption and shapeability of the resulting molded article, aramid fiber is preferred, and in particular, the combination of carbon fiber and aramid fiber is preferred from the perspective of balancing mechanical properties and impact absorption. Moreover, from the viewpoint of improving the electrical conductivity of the resulting molded article, reinforcing fibers coated with metals such as nickel, copper, and ytterbium, or pitch-based carbon fibers can also be used.

[0065] Preferably, a slugging agent is attached to the reinforcing fiber bundle (A). By attaching the slugging agent to the reinforcing fiber bundle (A), the operability during the transfer of the reinforcing fibers and the processability during the manufacturing of the molded material can be improved. There is no particular limitation on the type of slugging agent, but one or more of the following slugging agents, such as epoxy resin, urethane resin, acrylic resin, and various thermoplastic resins, can be used.

[0066] The reinforcing fiber bundle (A) is preferably 1% or more and 50% or less by mass relative to the total amount of molding material (100% by mass). More preferably, it is 10% or more and 30% or less by mass. If the content of the reinforcing fiber bundle (A) is less than 1% by mass, the mechanical properties of the resulting molded article may become insufficient. If it exceeds 50% by mass, the amount of gas generated from the reinforcing fiber and the bundle agent attached to the reinforcing fiber may increase.

[0067] [Polyphenylene sulfide (B)]

[0068] The polyphenylene sulfide (B) in this invention has a melting point below 270°C. The melting point of polyphenylene sulfide (B) can be determined by the temperature of the peak of the melting peak in differential scanning calorimetry (DSC). When using two or more polyphenylene sulfides, and their mixture exhibits a single melting peak, the melting point can be determined from the peak of that melting peak. Conversely, when using two or more polyphenylene sulfides, and multiple melting peaks are observed, the melting point is determined from the peaks of each individual melting peak.

[0069] By setting the melting point below 270°C, the molding temperature can be lowered, suppressing the generation of gases during molding. Furthermore, economic efficiency is improved. In particular, when the molding material contains impregnating resin and the reinforcing fibers are coated with a bridging agent, the decomposition of the impregnating resin and bridging agent during molding can be suppressed, allowing for the selection of impregnating resins and bridging agents with lower heat resistance. In other words, this provides greater freedom in the design and selection of impregnating resins and bridging agents.

[0070] In this invention, the melting point of polyphenylene sulfide (B) is more preferably 260°C or lower. By having a melting point of 260°C or lower for polyphenylene sulfide (B), the molding temperature can be lowered, resulting in excellent suppression of decomposition gases during molding and superior economy. In particular, when the molding material contains impregnating resin and the reinforcing fibers are attached with a binding agent, the decomposition of the impregnating resin and binding agent can be suppressed, allowing for greater freedom in the handling of the impregnating resin and binding agent. Furthermore, from the viewpoint of heat resistance, the melting point of polyphenylene sulfide (B) is preferably 240°C or higher. The melting point of polyphenylene sulfide (B) is determined as described below.

[0071] [1] The sample was heated from 40°C to 340°C using a differential scanning calorimeter at a heating rate of 20°C / min.

[0072] [2] After the heating in [1], the sample was cooled from 340°C to 40°C at a cooling rate of 20°C / min.

[0073] [3] After cooling down in [2], the sample was heated again from 40°C to 340°C at a heating rate of 20°C / min.

[0074] The apex of the melting peak observed during the heating process described above [3] is set as the melting point.

[0075] In this invention, the method for making the melting point of polyphenylene sulfide (B) below 270°C is not particularly limited. Examples include methods such as copolymerizing polyphenylene sulfide with m-phenylene sulfide and / or o-phenylene sulfide, which is mainly formed by a p-phenylene sulfide backbone; methods such as block copolymerizing other polymers at the ends of polyphenylene sulfide; and methods such as reducing molecular mobility by oxidative crosslinking of polyphenylene sulfide. In the case of block copolymerizing other polymers at the ends of polyphenylene sulfide, there are no restrictions on the other polymers. Examples include polyesters, polyamides, polyimides, polyamide-imides, polyetherimides, polyarylates, polysulfones, polyethersulfones, polyketones, polyetherketones, polyetheretherketones, polythioetherketones, polytetrafluoroethylene, polyorganosiloxanes, thermoplastic polyurethane resins, high-density polyethylene, low-density polyethylene, linear low-density polyethylene, polypropylene, polyacrylates, polymethacrylates, poly-1-butene, poly-1-pentene, polymethylpentene, ethylene / α-olefin copolymers, and other polyolefins.

[0076] In this invention, the polyphenylene sulfide (B) is preferably a polyphenylene sulfide obtained by copolymerizing p-phenylene sulfide and m-phenylene sulfide. That is, in this invention, the polyphenylene sulfide (B) preferably comprises p-phenylene sulfide units and m-phenylene sulfide units. In this invention, the content of m-phenylene sulfide units is preferably 7 mol% or more relative to the total amount of p-phenylene sulfide units and m-phenylene sulfide units. More preferably, it is 8 mol% or more, further preferably 10 mol% or more, and particularly preferably 10.5 mol% or more. By making the content of m-phenylene sulfide units 7 mol% or more, the melting point of the polyphenylene sulfide can be lowered, and the crystallization rate of the polyphenylene sulfide (B) is reduced, while the fluidity is improved. On the other hand, when the content of m-phenylene sulfide units is less than 7 mol%, the melting point of the polyphenylene sulfide is sometimes not sufficiently lowered.

[0077] There is no particular upper limit to the content of m-phenylene sulfide units in polyphenylene sulfide, but it is preferably 20 mol% or less, and more preferably 14 mol% or less. If the content of m-phenylene sulfide units is 20 mol% or less, in addition to achieving the desired mechanical properties, the mold release properties during molding are improved, and the molding cycle performance becomes better. Furthermore, if it is 14 mol% or less, in addition to possessing excellent flowability and mechanical properties, the improved mold release properties during molding can enhance molding cycle performance. On the other hand, when the content of m-phenylene sulfide units is greater than 20 mol%, the inherent heat aging resistance and chemical resistance of polyphenylene sulfide are reduced, which is sometimes undesirable.

[0078] Furthermore, when the molding material is a composite of polyphenylene sulfide (B) coated strips, if the content of m-phenylene sulfide units is 7 mol% or more, the crystallization of polyphenylene sulfide (B) in the coated composite is suppressed, the polyphenylene sulfide (B) is less prone to breakage, and a molding material with excellent workability can be obtained. Moreover, as described above, by improving the workability of the molding material, deviations in the mechanical properties of the molded article can be suppressed, surface smoothness can be improved, the decrease in the flowability of the molding material can be suppressed, or the flowability can be improved.

[0079] For this reason, when cutting polyphenylene sulfide (B) coated composite wire to produce granular molding materials, it is preferable that the content of m-phenylene sulfide units is 7 mol% or more, as this makes the polyphenylene sulfide (B) less prone to breakage. Furthermore, by ensuring the content of m-phenylene sulfide units is 7 mol% or more, fluidity is improved, resulting in lower shear stress applied to the reinforcing fibers during mixing or molding, thus maintaining a longer fiber length in the reinforcing fiber bundles (A) of the molded article. In particular, the effects of the molding material of the present invention are more pronounced for reinforcing fibers with an elastic modulus of 350 GPa or more, which are difficult to maintain in terms of fiber length.

[0080] The m-phenylene sulfide unit of polyphenylene sulfide (B) was determined using Fourier transform infrared spectroscopy (FT-IR). Specifically, the absorption peak at 780 cm⁻¹, which represents the m-phenylene sulfide unit, was measured. -1 The size of the absorption peak is used to calculate the content of m-phenyl sulfide units.

[0081] The cooling crystallization temperature of polyphenylene sulfide (B) is preferably below 190°C. More preferably, it is below 170°C. By keeping the cooling crystallization temperature of polyphenylene sulfide (B) below 190°C, the crystallization rate is slowed down, resulting in excellent flowability during molding. On the other hand, from the viewpoint of the mechanical properties and surface quality of the molded article, the lower limit of the cooling crystallization temperature of polyphenylene sulfide (B) is preferably 140°C. The cooling crystallization temperature of polyphenylene sulfide (B) is determined using a differential scanning calorimeter, by heating from 40°C to 340°C at a rate of 20°C / min, and then cooling from 340°C to 40°C at a rate of 20°C / min. The peak of the cooling crystallization at this point is set as the cooling crystallization temperature.

[0082] There are no particular limitations on the method for cooling the crystallization temperature of polyphenylene sulfide (B) to below 190°C. Examples include copolymerizing polyphenylene sulfide with m-phenylene sulfide and / or o-phenylene sulfide, which is mainly formed by the p-phenylene sulfide backbone; copolymerizing other polymers at the end of polyphenylene sulfide; and reducing molecular mobility by oxidative crosslinking of polyphenylene sulfide.

[0083] The difference between the melting point and the cooling crystallization temperature of polyphenylene sulfide (B) is preferably 80°C or higher. More preferably, it is 90°C or higher. The difference between the melting point and the cooling crystallization temperature refers to the temperature at which the resin, which is in a molten state at cooling temperature, crystallizes until it solidifies. Therefore, a large difference between the melting point and the cooling crystallization temperature means that the resin cures more slowly. With a difference of 80°C or higher between the melting point and the cooling crystallization temperature of polyphenylene sulfide (B), the curing is slower, the transferability of the mold surface is improved, and the surface smoothness is better, which is therefore preferred, and it can reduce the molding pressure during molding. On the other hand, from the viewpoint of the mechanical properties and surface quality of the molded article, the upper limit of the difference between the melting point and the cooling crystallization temperature of polyphenylene sulfide (B) is preferably 120°C.

[0084] There are no particular limitations on the method of making the difference between the melting point of polyphenylene sulfide (B) and the cooling crystallization temperature greater than 80°C. Examples include methods such as copolymerizing polyphenylene sulfide with m-phenylene sulfide and / or o-phenylene sulfide, which is mainly formed by the p-phenylene sulfide backbone; methods such as block copolymerizing other polymers at the end of polyphenylene sulfide; and methods such as reducing the molecular mobility by oxidative crosslinking of polyphenylene sulfide.

[0085] Polyphenylene sulfide (B) preferably comprises homopolymer polyphenylene sulfide consisting only of p-phenylene sulfide units, and copolymer polyphenylene sulfide consisting of p-phenylene sulfide units and m-phenylene sulfide units. By including both homopolymer and copolymer polyphenylene sulfide, the amount of gas generated during molding can be reduced, while the crystallinity of the polyphenylene sulfide can be increased, thus achieving a better balance between surface smoothness, mechanical properties, flowability, and molding recyclability.

[0086] The content of polyphenylene sulfide (B) relative to the total amount of molding material (100% by mass) is preferably 30% by mass or more and 98.9% by mass or less, more preferably 40% by mass or more and 94.5% by mass or less, and even more preferably 50% by mass or more and 89% by mass or less. By adjusting to such a range, a molding material with excellent moldability and handling is obtained. In addition, excellent mechanical properties can be imparted to the molded article. If the content of polyphenylene sulfide (B) is less than 30% by mass, the molding material contains less polyphenylene sulfide resin (B), so sometimes the reinforcing fiber bundles (A) cannot be sufficiently melt-mixed with the polyphenylene sulfide resin (B) during molding, and the fluidity is reduced during injection molding. In this case, the reinforcing fiber bundles (A) cannot be sufficiently dispersed in the molded article, molding becomes difficult, and this is sometimes undesirable.

[0087] Furthermore, if the content of polyphenylene sulfide (B) exceeds 98.9% by mass, the amount of reinforcing fiber bundles (A) contained in the molding material becomes relatively small, thus the fiber reinforcement effect imparted to the molded article becomes insufficient, and the mechanical properties of the resulting molded article become insufficient, which is sometimes undesirable. Additionally, in the case where polyphenylene sulfide (B) is used to coat part or all of the surrounding shape of a strip-shaped composite in the molding material, and the amount of polyphenylene sulfide (B) is less than 30% by mass, the coating layer becomes thin due to the small amount of polyphenylene sulfide (B), the molding material is prone to cracking, and the workability is reduced, which is also sometimes undesirable.

[0088] From the viewpoint of the mechanical properties of the molded article obtained by molding the molding material, the molecular weight of polyphenylene sulfide (B), expressed as weight-average molecular weight, is preferably 10,000 or more, more preferably 20,000 or more, and particularly preferably 30,000 or more. This is advantageous from the viewpoint that a higher weight-average molecular weight results in higher strength and elongation of the matrix resin. On the other hand, there is no particular upper limit on the weight-average molecular weight, but from the viewpoint of flowability during molding, it is preferably 1,000,000 or less, and more preferably 500,000 or less. It should be noted that the weight-average molecular weight can be determined using general GPC (gel permeation chromatography) methods such as SEC (size exclusion chromatography) as described above.

[0089] Furthermore, in polyphenylene sulfide (B), depending on its application, fillers such as mica, talc, kaolin, hydrotalcite, sericite, bentonite, calcium silicate, sepiolite, montmorillonite, wollastonite, silica, calcium carbonate, glass beads, glass flakes, glass microspheres, clay, molybdenum disulfide, titanium dioxide, zinc oxide, antimony oxide, calcium polyphosphate, graphite, barium sulfate, magnesium sulfate, zinc borate, calcium borate, aluminum borate whiskers, potassium titanate whiskers, and polymer compounds can be added; conductive materials such as metal-based and metal oxide-based compounds, carbon black and graphite powder can be added; halogen-based flame retardants such as brominated resins can be added; antimony-based flame retardants such as antimony trioxide and antimony pentoxide can be added; phosphorus-based flame retardants such as ammonium polyphosphate, aromatic phosphates and red phosphorus can be added; organic acid metal salt flame retardants such as borate metal salts, carboxylic acid metal salts and aromatic sulfonyl imide metal salts can be added; zinc borate, zinc... Inorganic flame retardants such as zinc oxide and zirconium compounds; nitrogen-based flame retardants such as cyanuric acid, isocyanuric acid, melamine, melamine cyanurate, melamine phosphate, and guanidine nitride; fluorine-based flame retardants such as PTFE; organosilicon-based flame retardants such as polyorganosiloxanes; metal hydroxide-based flame retardants such as aluminum hydroxide and magnesium hydroxide; other flame retardants; flame retardant additives such as cadmium oxide, zinc oxide, cuprous oxide, copper oxide, ferrous oxide, iron oxide, cobalt oxide, manganese oxide, molybdenum oxide, tin oxide, and titanium oxide; pigments, dyes, lubricants, release agents, compatibilizers, dispersants; crystal nucleating agents such as mica, talc, and kaolin; plasticizers such as phosphate esters; heat stabilizers; antioxidants; colorants; ultraviolet absorbers; flow modifiers; foaming agents; antibacterial agents; vibration damping agents; deodorizing agents; slip modifiers; and antistatic agents such as polyether ester amides.

[0090] [Resin (C) (Impregnated Resin)]

[0091] The resin (C) (impregnating resin) is preferably one or more resins selected from epoxy resin, phenolic resin and terpene resin.

[0092] By filling the spaces between the individual fibers of the reinforcing fiber bundle (A) with the aforementioned impregnated resin in the molding material, the dispersibility of the reinforcing fibers can be improved during the molding of the molding material.

[0093] Furthermore, the impregnating resin preferably has a lower melt viscosity than polyphenylene sulfide (B). Because the melt viscosity of the impregnating resin is lower than that of polyphenylene sulfide (B), the impregnating resin has higher fluidity during molding of the molding material, which improves the dispersion of reinforcing fiber bundles into the polyphenylene sulfide (B). Using one or more resins selected from epoxy resins, phenolic resins, and terpene resins as the impregnating resin results in a lower melt viscosity compared to polyphenylene sulfide (B), improving the dispersion of reinforcing fiber bundles in the molded article. Therefore, it is preferable to improve the mechanical properties of the molded article obtained by molding the molding material of the present invention, while also improving surface smoothness.

[0094] The impregnation resin is preferably a substance with high affinity for polyphenylene sulfide (B). By selecting an impregnation resin with high affinity for polyphenylene sulfide (B), it is possible to achieve good compatibility with polyphenylene sulfide (B) during the manufacture and molding of the molding material, thereby further improving the dispersibility of the reinforcing fibers.

[0095] The melt viscosity of the impregnating resin at 200°C is preferably 0.01 to 10 Pa·s. If the melt viscosity at 200°C is 0.01 Pa·s or higher, damage originating from the impregnating resin can be further suppressed, resulting in improved impact strength of the molded article. A melt viscosity of 0.05 Pa·s or higher is more preferred, and 0.1 Pa·s or higher is even more preferred. On the other hand, if the melt viscosity at 200°C is 10 Pa·s or lower, the impregnating resin can easily impregnate the interior of the reinforcing fiber bundle (A). Therefore, when molding the molding material of the present invention, the dispersibility of the reinforcing fibers can be further improved. A melt viscosity of 5 Pa·s or lower is preferred, and 2 Pa·s or lower is more preferred. The melt viscosity of the impregnating resin at 200°C can be measured using a viscoelasticity meter at 0.5 Hz using a 40 mm parallel plate.

[0096] The number-average molecular weight of the impregnating resin is preferably between 200 and 5,000. If the number-average molecular weight is 200 or higher, the flexural strength and tensile strength of the molded article can be further improved. A number-average molecular weight of 1,000 or higher is more preferable. Furthermore, if the number-average molecular weight is 5,000 or lower, the viscosity of the impregnating resin is moderately low, thus exhibiting excellent impregnation of the reinforcing fiber bundle (A), and further improving the dispersibility of the reinforcing fibers in the molded article. A number-average molecular weight of 3,000 or lower is more preferable. It should be noted that the number-average molecular weight of such an impregnating resin can be determined using gel permeation chromatography (GPC).

[0097] The heat loss when the impregnated resin is heated at 280°C for 30 minutes in nitrogen is preferably 5% by weight or less. More preferably, it is 3% by weight or less. With such a heat loss of 5% by weight or less, the generation of decomposition gases can be suppressed during impregnation of the reinforcing fiber bundle (A), and the generation of voids and poor surface appearance can be suppressed during molding. In addition, gas generation can be suppressed, especially during molding at high temperatures.

[0098] It should be noted that the so-called weight loss due to heating in this invention means that the weight of the impregnated resin before heating is set to 100%, and the weight loss rate of the impregnated resin before and after heating under the above heating conditions can be calculated by the following formula. It should also be noted that the weight before and after heating can be determined by thermogravimetric analysis (TGA) of the weight at the molding temperature using a platinum sample pan in an air atmosphere at a heating rate of 10°C / min.

[0099] (Weight loss due to heating) [% by weight] = {(Weight before heating - Weight after heating) / Weight before heating} × 100

[0100] In this invention, the so-called epoxy resin preferred as the impregnation resin refers to a compound having two or more epoxy groups and substantially containing no curing agent, and does not undergo curing based on so-called three-dimensional cross-linking even when heated. Because it has epoxy groups, the epoxy resin readily interacts with the reinforcing fibers, easily merging with the reinforcing fiber bundle (A) during impregnation, thus facilitating impregnation. Furthermore, the dispersibility of the reinforcing fibers during molding is further improved.

[0101] Furthermore, in this invention, examples of epoxy resins include glycidyl ether type epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, and alicyclic epoxy resins. Two or more of these can be used. Examples of glycidyl ether type epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AD ​​type epoxy resins, halogenated bisphenol A type epoxy resins, bisphenol S type epoxy resins, resorcinol type epoxy resins, hydrogenated bisphenol A type epoxy resins, phenolic varnish type epoxy resins, cresol phenolic varnish type epoxy resins, aliphatic epoxy resins having ether bonds, naphthalene type epoxy resins, biphenyl type epoxy resins, biphenyl aralkyl type epoxy resins, and dicyclopentadiene type epoxy resins. Examples of glycidyl ester type epoxy resins include glycidyl hexahydrophthalate and diglycidyl dimerate. Examples of glycidylamine type epoxy resins include triglycidyl isocyanurate, tetraglycidyl diaminodiphenylmethane, tetraglycidyl m-phenylenediamine, and aminophenol type epoxy resins. Examples of alicyclic epoxy resins include 3,4-epoxy-6-methylcyclohexyl methylformate and 3,4-epoxycyclohexyl methylformate. Among these, glycidyl ether type epoxy resins are preferred for achieving an excellent balance between viscosity and heat resistance, and bisphenol A type epoxy resins and bisphenol F type epoxy resins are more preferred.

[0102] Phenolic resins are resins with a phenolic skeleton that may contain substituents, such as cresol and naphthol. Specifically, examples of phenolic resins include phenolic varnish resins, o-cresol phenolic varnish resins, phenol aralkyl resins, naphthol phenolic varnish resins, and naphthol aralkyl resins. Among these, o-cresol phenolic varnish resins are preferred due to their excellent balance between heat resistance and workability, such as melt viscosity, which allows for faster composite drawing speeds and better flame retardancy.

[0103] Furthermore, the melting point of the phenolic resin is not particularly limited, but from the viewpoint of improving the heat resistance and workability of the molded material and suppressing exudation during long-term storage, it is preferable to exceed 80°C. More preferably, it exceeds 100°C, and even more preferably, it exceeds 120°C. There is no particular limitation on the upper limit of the melting point; it should be noted that the melting point of the phenolic resin can be determined by DSC measurement. Specifically, it can be determined from the value of the endothermic peak measured under a heating rate of 40°C / min.

[0104] Examples of terpene resins include resins made by polymerizing terpene monomers individually in an organic solvent in the presence of a Frederick catalyst, or resins made by copolymerizing terpene monomers with aromatic monomers, etc.

[0105] Examples of terpene monomers include α-pinene, β-pinene, dipentene, d-limonene, myrcene, allocirrhene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinene oil, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, γ-terpineol, juniperene, and p-terpinene. Monocyclic monoterpenes, such as dienes and carenes, are also examples. Furthermore, styrene and α-methylstyrene are examples of aromatic monomers.

[0106] Among these, α-pinene, β-pinene, dipentene, and d-limonene are preferred from a compatibility viewpoint, and even more preferably, homopolymers of these compounds. Furthermore, hydrogenated terpene resins obtained by hydrogenating these terpene resins are even more preferred from a compatibility viewpoint.

[0107] Furthermore, as a terpene resin, a terpene-phenol resin obtained by reacting a terpene monomer with a phenol in the presence of a catalyst can also be used. Here, as a phenol, it is preferable to use a substance having at least one substituent selected from alkyl, halogen, and hydroxyl groups on the benzene ring of the phenol. Specific examples include cresol, xylenol, ethylphenol, butylphenol, tert-butylphenol, nonylphenol, 3,4,5-trimethylphenol, chlorophenol, bromophenol, chlorocresol, hydroquinone, resorcinol, and chlorophenol. Two or more of these can be used. Among them, phenol and cresol are preferred.

[0108] The number average molecular weight of terpene-based resins and terpene-phenol resins is preferably 100 to 5,000, more preferably 500 to 1,000. If the number average molecular weight is 100 or higher, the heat loss of the terpene-based resin is reduced, thus improving the dispersibility of the reinforcing fiber bundles (A) in the molded article, which is therefore preferred. Furthermore, if the number average molecular weight is 5,000 or lower, the viscosity of the terpene resin is lower, thus improving the impregnation of the reinforcing fiber bundles (A) and the fiber dispersibility during molding, which is therefore preferred.

[0109] The content of resin (C) (impregnating resin) relative to the total amount of molding material (100% by mass) is preferably 0.1% by mass or more and 20% by mass or less, more preferably 3% by mass or more and 10% by mass or less. By falling within this range, a molding material with excellent moldability and workability is obtained. If the content of impregnating resin is less than 0.1% by mass, the impregnation of the reinforcing fiber bundle (A) may become insufficient, resulting in insufficient workability of the resulting molding material, which is undesirable. On the other hand, if it exceeds 20% by mass, the molded article contains a relatively higher proportion of low molecular weight components, thus the molded article becomes brittle and its mechanical properties decrease, which is also undesirable.

[0110] The molding material of the present invention is compounded, for example, by injection molding to obtain the final molded article. By keeping the resin (C) content within the above-mentioned numerical range, the workability of the molding material can be improved. As a result, deviations in the mechanical properties of the molded article can be suppressed, or the surface smoothness of the molded article can be improved. Furthermore, the decrease in the flowability of the molding material can be suppressed, or the flowability can be improved. In addition, excellent mechanical properties can be imparted to the resulting molded article.

[0111] [Additives to molding materials]

[0112] In the molding material of the present invention, it is preferable to further include 0.1 to 10% by mass of a compound having at least one structure selected from carbodiimide, urea, and urethane within one molecule, from the viewpoint of further improving the affinity between the reinforcing fiber bundle (A) and polyphenylene sulfide (B) and improving the tensile properties of the resulting molded article. The mixing amount is preferably 0.3 to 8% by mass, and is particularly preferred from the viewpoint of also considering the generation of decomposition gases during mixing with the matrix resin, in the range of 0.5 to 5% by mass.

[0113] As compounds with a carbodiimide structure, namely carbodiimide compounds, there are polycarbodiimides, such as aliphatic polycarbodiimides and aromatic polycarbodiimides. However, from the viewpoint of enhancing the affinity and reactivity between the fiber bundle (A) and polyphenylene sulfide (B), aliphatic polycarbodiimides are preferred.

[0114] The so-called aliphatic polycarbodiimide compound is a homopolymer or copolymer with repeating units represented by the general formula -N=C=N-R3- (where R3 represents a divalent organic group of alicyclic compounds such as cyclohexene, or a divalent organic group of aliphatic compounds such as methylene, ethylene, propylene, methyl ethylene) as the main constituent unit, preferably containing 70 mol% or more, more preferably 90 mol% or more, and even more preferably 95 mol% or more of the repeating unit.

[0115] As a compound having a urea structure, a substance obtained by reacting a diisocyanate with a diamine containing a compound having multiple amino groups (e.g., hydrazine, dihydrazide, etc.) can be used. Alternatively, polyurea can be synthesized by reacting an isocyanate with water to form an unstable carbamic acid. The carbamic acid decomposes to produce carbon dioxide, which immediately reacts with excess isocyanate to form amino groups that crosslink the urea. Alternatively, it can also be obtained by treating a compound having a carbodiimide structure with water, causing the carbodiimide to react with a urea.

[0116] As a compound having a urethane structure, substances obtained by reacting dichloroformate with diamine can be used. Alternatively, polyurethane can be synthesized by reacting diisocyanate with diols such as macromolecular diols, polyols, or a combination of macromolecular diols and single-chain diol extenders.

[0117] Of the compounds described above, polycarbodiimide is preferred from the viewpoint of interfacial adhesion to the reinforcing fiber bundle (A).

[0118] <Molded Products>

[0119] The molded article of the present invention is a molded article comprising reinforcing fibers and polyphenylene sulfide, wherein the weight-average fiber length of the reinforcing fibers is 0.3 mm or more and 3.0 mm or less, and the melting point of the polyphenylene sulfide is 270°C or less. Furthermore, the molded article of the present invention is a molded article comprising reinforcing fibers and polyphenylene sulfide (B), wherein the weight-average fiber length of the reinforcing fibers is 0.3 mm or more and 3.0 mm or less, and the cooling crystallization temperature of the polyphenylene sulfide is 190°C or less.

[0120] [Reinforcing fibers contained in the molded article]

[0121] The weight-average fiber length of the reinforcing fibers included in the molded article is 0.3 to 3.0 mm. More preferably, it is 0.5 to 2.8 mm. Even more preferably, it is 0.8 to 2.5 mm. By making the weight-average fiber length of the reinforcing fibers 0.3 mm or more, the mechanical properties of the molded article can be fully expressed. On the other hand, when the weight-average fiber length of the reinforcing fibers exceeds 3.0 mm, the fiber pattern of the reinforcing fibers is easily and significantly visible on the surface of the molded article, resulting in undulations on the surface of the molded article caused by the reinforcing fibers, leading to poor appearance, which is sometimes undesirable. Therefore, by making the weight-average fiber length of the reinforcing fibers 3.0 mm or less, such undulations can be suppressed, resulting in an excellent surface appearance of the molded article.

[0122] There are no particular limitations on the type of reinforcing fiber; examples can be found in the description of the reinforcing fiber bundles of the molding material. Furthermore, the preferred types and combinations of reinforcing fibers are also preferred for the same reasons.

[0123] The reinforcing fiber percentage is preferably 1 to 50% by mass relative to 100% of the molded article. More preferably, it is 10 to 30% by mass. If the reinforcing fiber percentage is less than 1% by mass, the mechanical properties of the resulting molded article may become insufficient, and if it exceeds 50% by mass, the appearance of the molded article may become unsatisfactory.

[0124] Preferably, a bridging agent is attached to the reinforcing fibers. By attaching the bridging agent to the reinforcing fibers, the mechanical properties of the molded article can be improved. There is no particular limitation on the type of bridging agent, but one or more of the following can be used: epoxy resin, urethane resin, acrylic resin, various thermoplastic resins, etc., or in combination of two or more.

[0125] [The polyphenylene sulfide contained in the molded article]

[0126] The polyphenylene sulfide resin contained in the molded article of this invention preferably has a melting point of 270°C or below. By setting the melting point to 270°C or below, molding can be performed at a lower molding temperature compared to conventional polyphenylene sulfide resins. This suppresses the thermal decomposition of the impregnating resin, binding agent, and other additives contained in the molding material, i.e., suppresses gas generation.

[0127] As a method for achieving a melting point of polyphenylene sulfide resin of 270°C or below, a polyphenylene sulfide resin with a desired melting point can be obtained by appropriately adjusting the above method. In this invention, the melting point of polyphenylene sulfide (B) is more preferably 260°C or below. Furthermore, from the viewpoint of heat resistance, the melting point of polyphenylene sulfide (B) is preferably 240°C or above.

[0128] Furthermore, the polyphenylene sulfide resin contained in the molded article of the present invention preferably comprises homopolymer polyphenylene sulfide composed only of p-phenylene sulfide units, and copolymer polyphenylene sulfide composed of p-phenylene sulfide units and m-phenylene sulfide units. By using homopolymer polyphenylene sulfide and copolymer polyphenylene sulfide, the crystallization rate and cooling crystallization temperature can be appropriately controlled. That is, since the curing rate of the molded article can be controlled, rapid curing and extreme curing delay within the mold during injection molding can be suppressed, and as a result, the fluidity of the resin during molding can be ensured. In addition, the cycle time can be maintained.

[0129] Furthermore, by including homopolymer polyphenylene sulfide composed solely of p-phenylene sulfide units and copolymer polyphenylene sulfide composed of both p-phenylene sulfide and m-phenylene sulfide units in the aforementioned polyphenylene sulfide resin, the crystallinity of the polyphenylene sulfide resin can be controlled. By appropriately adjusting the blending amount of the aforementioned polyphenylene sulfide resin, the crystallinity of the polyphenylene sulfide resin can be increased. Therefore, the polyphenylene sulfide resin in the molded article obtained by, for example, injection molding can have a high degree of crystallinity, thereby improving its mechanical properties.

[0130] The aforementioned polyphenylene sulfide resin may simply include homopolymer polyphenylene sulfide composed solely of p-phenylene sulfide units and copolymer polyphenylene sulfide composed of both p-phenylene sulfide and m-phenylene sulfide units. For example, homopolymer polyphenylene sulfide particles composed solely of p-phenylene sulfide units and copolymer polyphenylene sulfide particles composed of both p-phenylene sulfide and m-phenylene sulfide units are dry-blended to obtain pre-mixed particles (hereinafter, mixed particles). These mixed particles are then supplied as polyphenylene sulfide in the main hopper of a twin-screw extruder, thereby enabling the blending of homopolymer polyphenylene sulfide composed solely of p-phenylene sulfide units and copolymer polyphenylene sulfide composed of both p-phenylene sulfide and m-phenylene sulfide units.

[0131] Furthermore, the mixing ratio of homopolymer polyphenylene sulfide composed solely of p-phenylene sulfide units and copolymer polyphenylene sulfide composed of both p-phenylene sulfide and m-phenylene sulfide units is not particularly limited. However, relative to a total of 100 parts by weight of homopolymer polyphenylene sulfide composed solely of p-phenylene sulfide units and copolymer polyphenylene sulfide composed of both p-phenylene sulfide and m-phenylene sulfide units, a mixing ratio of 1 to 50 parts by weight of homopolymer polyphenylene sulfide composed solely of p-phenylene sulfide units and 99 to 50 parts by weight of copolymer polyphenylene sulfide composed of both p-phenylene sulfide and m-phenylene sulfide units is more preferably 5 to 40 parts by weight of homopolymer polyphenylene sulfide composed solely of p-phenylene sulfide units and 95 to 60 parts by weight of copolymer polyphenylene sulfide composed of both p-phenylene sulfide and m-phenylene sulfide units is more preferably 95 to 60 parts by weight of copolymer polyphenylene sulfide composed solely of p-phenylene sulfide units.

[0132] If the amount of homopolymer polyphenylene sulfide composed solely of p-phenylene sulfide units is less than 1 part by weight, the crystallization rate and cooling crystallization temperature cannot be properly controlled, and the curing rate of the molded product becomes extremely slow. Therefore, the cycle time during injection molding becomes longer, which is sometimes undesirable. Furthermore, if it exceeds 50 parts by weight, the crystallization rate becomes too fast, which increases the curing rate within the mold during injection molding and reduces fluidity, which is sometimes undesirable.

[0133] Furthermore, if the amount of the copolymer polyphenylene sulfide composed of p-phenylene sulfide units and m-phenylene sulfide units is less than 50 parts by weight, the crystallization rate is too fast. As a result, the curing rate in the mold during injection molding increases and the fluidity decreases, which is sometimes undesirable. In addition, if the amount exceeds 99 parts by weight, the crystallization rate and the cooling crystallization temperature cannot be properly controlled, and the curing rate of the molded article becomes extremely slow. As a result, the cycle time during injection molding becomes longer, which is sometimes undesirable.

[0134] Example

[0135] The present invention will be further described in detail below through examples. First, the evaluation method used in the present invention will be described below.

[0136] (1) Determination of melting point and cooling crystallization temperature of polyphenylene sulfide (B)

[0137] The melting point and cooling crystallization temperature of polyphenylene sulfide (B) were determined using a differential scanning calorimeter TA3000 (manufactured by Metcal). The results are described below.

[0138] [1] The sample was heated from 40°C to 340°C using a differential scanning calorimeter TA3000 (made by Metcal). The heating rate was 20°C / min.

[0139] [2][1] After heating, the sample was cooled from 340℃ to 40℃ at a cooling rate of 20℃ / min.

[0140] [3] After cooling down in [2], the sample was heated again from 40°C to 340°C at a heating rate of 20°C / min.

[0141] The apex of the melting peak observed during the heating process described above [3] will be set as the melting point. In addition, the apex of the cooling crystallization peak observed during the cooling process described above [2] will be set as the cooling crystallization temperature.

[0142] (2) Determination of tensile strength of molded articles

[0143] The tensile strength of the ISO-type dumbbell test piece obtained by injection molding of the molding material was determined according to ISO 527 (2012). Under the conditions of a distance of 114 mm between the supports, a tensile speed of 5 mm / min, a temperature of 23°C, and a relative humidity of 50%, the testing machine used was the Instron Universal Testing Machine Model 5566 (manufactured by Instron Co., Ltd.).

[0144] (3) Determination of the flexural modulus of the molded article

[0145] The bending properties of the ISO-type dumbbell test piece obtained by injection molding of the molding material were determined according to ISO 178 (1993). The flexural modulus was determined using a 3-point bending test fixture (indenter radius 5 mm) with the fulcrum distance set to 64 mm and a test speed of 2 mm / min. The testing machine used was the Instron (registered trademark) universal testing machine model 5566 (manufactured by Instron Co., Ltd.).

[0146] (4) Determination of the weight-average fiber length of the reinforcing fibers contained in the molded article

[0147] A portion of an ISO-type dumbbell-shaped test piece obtained by injection molding of the molding material was cut out and heated and pressurized at 320°C to obtain a film approximately 30 μm thick. The resulting film was observed using an optical microscope at 150x magnification. At least 400 reinforcing fibers dispersed within the film were selectively extracted, and their lengths were measured down to 1 μm. The weight-average fiber length was calculated using the following formula. Here, "weight-average fiber length" refers to the average fiber length calculated by applying the method for calculating weight-average molecular weight to the calculation of fiber length, not simply taking the average, but considering the contribution of fiber length. However, this formula is applied when the fiber diameter and density of the reinforcing fibers are constant.

[0148] Weight-average fiber length = Σ(Mi) 2 ×Ni) / Σ(Mi×Ni)

[0149] Mi: Fiber length (mm)

[0150] Ni: Number of carbon fibers with fiber length Mi

[0151] i: Measure the number of fibers.

[0152] (5) Measurement of surface smoothness (surface roughness Rz) of molded products

[0153] The surface of the mold mirror side of the ISO-type dumbbell test piece obtained by injection molding of the molding material is measured using a surface roughness tester (Tokyo Seimitsu Co., Ltd.). The smaller the Rz, the smaller the surface roughness and the better the surface smoothness.

[0154] (Refer to Example 1) Preparation of polyphenylene sulfide (B-1) [a homopolymer polyphenylene sulfide composed only of p-phenylene sulfide units]

[0155] In a 20-liter high-pressure reactor equipped with a stirrer, 2383 g (20.0 mol) of a 47% sodium hydrosulfide aqueous solution, 848 g (20.4 mol) of sodium hydroxide (96% purity), 3271 g (33 mol) of N-methyl-2-pyrrolidone (NMP), 541 g (6.6 mol) of sodium acetate, and 3000 g of deionized water were added. The mixture was slowly heated to 225°C over approximately 3 hours while nitrogen gas was introduced at atmospheric pressure. After distilling off 4200 g of water and 80 g of NMP, the reaction vessel was cooled to 150°C. The amount of hydrogen sulfide scattering per 1 mol of sodium hydrosulfide added was 0.018 mol.

[0156] Next, 2940 g (20 mol) of p-dichlorobenzene (p-DCB) and 2620 g (26.2 mol) of NMP were added. The reaction vessel was sealed under nitrogen atmosphere, and the mixture was stirred at 400 rpm while heating at a rate of 0.8 °C / min to 227 °C, then heated at a rate of 0.6 °C / min to 270 °C, and held at 270 °C for 170 min. The mixture was then cooled at a rate of 0.4 °C / min to 180 °C, and then quenched to near room temperature. The contents were removed, diluted with 10 L of NMP, and the solvent and solids were separated by filtration through an 80 mesh sieve. The resulting particles were washed several times with 20 L of warm water and filtered to obtain polyphenylene sulfide (B-1). It was then dried with hot air at 80 °C and then under reduced pressure at 120 °C. The final obtained (B-1) had a melt flow rate (MFR) of 600 g / 10 min.

[0157] (Refer to Example 2) Preparation of polyphenylene sulfide (B-2) [a copolymer polyphenylene sulfide composed of p-phenylene sulfide units and m-phenylene sulfide units]

[0158] Instead of 2940 g (20 mol) of p-dichlorobenzene (p-DCB), 2499 g (17 mol) of p-dichlorobenzene (p-DCB) and 441 g (3 mol) of m-dichlorobenzene (m-DCB) were used. All other things being equal, the polyphenylene sulfide (B-2) was obtained by operating in the same manner as in Reference Example 1 above. The final obtained (B-2) had an MFR of 775 g / 10 min.

[0159] (Refer to Example 3) Preparation of polyphenylene sulfide (B-3) [a copolymer polyphenylene sulfide composed of p-phenylene sulfide units and m-phenylene sulfide units]

[0160] Instead of 2940 g (20 mol) of p-dichlorobenzene (p-DCB), 2646 g (18 mol) of p-dichlorobenzene (p-DCB) and 294 g (2 mol) of m-dichlorobenzene (m-DCB) were used, and polyphenylene sulfide (B-3) was obtained by operating in the same manner as in Reference Example 1 above. The final obtained (B-3) had an MFR of 170 g / 10 min.

[0161] (Refer to Example 4) Preparation of polyphenylene sulfide (B-4) [a homopolymer polyphenylene sulfide composed only of p-phenylene sulfide units]

[0162] In a 20-liter high-pressure vessel equipped with a stirrer and a bottom valve, 2383 g (20.0 mol) of a 47% (w / w) sodium hydrosulfide aqueous solution, 831 g (19.9 mol) of sodium hydroxide (96% (w / w) purity), 3960 g (40.0 mol) of N-methyl-2-pyrrolidone (NMP), and 3000 g of deionized water were added. The mixture was slowly heated to 225°C over approximately 3 hours while nitrogen gas was introduced at atmospheric pressure. After distilling off 4200 g of water and 80 g of NMP, the reaction vessel was cooled to 160°C. The amount of hydrogen sulfide scattering per 1 mol of sodium hydrosulfide added was 0.021 mol.

[0163] Next, 2942 g (20.0 mol) of p-dichlorobenzene and 1515 g (15.3 mol) of NMP were added, and the reaction vessel was sealed under nitrogen. Then, while stirring at 400 rpm, the temperature was increased from 200 °C to 227 °C at a rate of 0.8 °C / min, followed by an increase to 274 °C at a rate of 0.6 °C / min. After holding at 274 °C for 50 minutes, the temperature was increased to 282 °C. The outlet valve at the bottom of the autoclave was opened, and while pressurized with nitrogen, the contents were flash-evaporated into a vessel equipped with a stirrer over 15 minutes. The mixture was stirred briefly at 250 °C to remove most of the NMP, recovering the solid material containing polyphenylene sulfide and its salts.

[0164] The obtained solid material and 15120g of ion-exchanged water were added to an autoclave equipped with a stirrer and washed at 70°C for 30 minutes, followed by filtration through a glass filter. Then, 17280g of ion-exchanged water heated to 70°C was injected into the glass filter and filtered to obtain a filter cake.

[0165] The obtained filter cake, 11880g of ion-exchanged water, and 4g of calcium acetate monohydrate were added to an autoclave equipped with a stirrer. After purging the autoclave with nitrogen, the temperature was raised to 192°C and maintained for 30 minutes. The autoclave was then cooled and the contents were removed.

[0166] The contents were filtered through a glass filter, and then 17280g of ion-exchanged water at 70°C was injected for further filtration to obtain a filter cake. The resulting filter cake was dried with hot air at 80°C, and then further dried under vacuum at 120°C for 24 hours to obtain dried polyphenylene sulfide. The final MFR of (B-4) was 1000g / 10min.

[0167] (Refer to Example 5) Preparation of polyphenylene sulfide (B-5) [polyphenylene sulfide composed only of p-phenylene sulfide units and copolyphenylene sulfide composed of polysiloxanes]

[0168] Following the method described in Japanese Patent Application Publication No. 64-45433, 937 g (12 mol) of anhydrous sodium sulfide, 3570 g (14 mol) of 4,4'-dichlorodiphenyl sulfide, and 10280 g (104 mol) of N-methyl-2-pyrrolidone (NMP) were added to an autoclave equipped with a reflux tube and a stirrer. The mixture was heated under nitrogen atmosphere and refluxed at 200°C for 3 hours. The reaction mixture was then injected into water, and the crude product obtained by filtration was extracted with 300 ml of high-temperature toluene. As a result, 2720 g of polyphenylene sulfide oligomers insoluble in toluene were obtained.

[0169] Next, 1164 g (6.5 mol) of the above-mentioned polyphenylene sulfide oligomer, 400 g (3 mol) of p-aminobenzylthiophenol, 530 g (3.8 mol) of anhydrous potassium carbonate, and 10280 g (104 mol) of N-methyl-2-pyrrolidone (NMP) were added to an autoclave equipped with a stirrer. The mixture was stirred at 130 °C for 1 hour under a nitrogen atmosphere, followed by stirring at 140–150 °C for 1.5 hours. The reaction mixture was then heated at 220 °C for 15 minutes and held at 200 °C for 20 minutes. After cooling the resulting solution, 400 mL of water was added, and the precipitated crude product was obtained by filtration. The crude product was washed with methanol and dried under reduced pressure. As a result, 1215 g of polyphenylene sulfide was obtained.

[0170] The obtained polyphenylene sulfide (PPS) 500 g, NMP 1380 g, amino-modified polydimethylsiloxane (Shin-Etsu Silico "X-22-161A") 30.5 g, and bisphenol A dianhydride 50.9 g were added to an autoclave equipped with a stirring blade to prepare a reaction mixture, which was then heated to reflux. After removing the water by azeotropic extraction, the autoclave was sealed and purged with nitrogen three times. The reaction mixture was then heated to 250 °C for approximately 15 minutes using a hot jacket while stirring at 240 rpm. The reaction was then carried out at 250 °C for 60 minutes, followed by rapid cooling of the autoclave to obtain the product. To recover the obtained product, the polymer was washed with hexane at 50 °C for 15 minutes and filtered twice. Further, it was washed with methanol at 50 °C for 15 minutes and filtered twice. Finally, it was washed with water at 70 °C for 15 minutes and filtered once to obtain PPS (B-5).

[0171] <Reinforcing Fiber Bundles (A)>

[0172] (A-1): Carbon fiber "Treka" T800-24K (manufactured by Toreka Co., Ltd.) was used. Polyglycerol polyglycidyl ether (epoxy equivalent: 140 g / eq), which is used as a binder for the carbon fiber, was attached at a weight of 1.0 wt% relative to the total weight of the binder and the carbon fiber (100% by mass).

[0173] (A-2): Carbon fiber "Treka" M55JB-6K (manufactured by Toreka Co., Ltd.) was used. Polyglycerol polyglycidyl ether (epoxy equivalent: 140 g / eq), which is used as a binder for the carbon fiber, was attached at a weight of 1.5% relative to the total weight of the binder and the carbon fiber (100% by mass).

[0174] (Example 1)

[0175] Epoxy resin (JAPAN EPOKI SC) manufactured by JER828 was melted in a molten bath at 200°C and supplied to a copier using a gear pump. The epoxy resin was applied from the copier onto a roller heated to 200°C, forming a film. Carbon fibers (A-1) were passed through this roller while in contact with it, ensuring a certain amount of epoxy resin adhered per unit length of the carbon fiber bundle. The epoxy resin-coated carbon fibers were heated to 230°C and passed between free rollers arranged alternately in a straight line, resulting in a composite in which the epoxy resin was fully impregnated with the carbon fibers.

[0176] Next, polyphenylene sulfide (B-2) is melted at 320°C using an extruder and extruded through a crosshead die installed at the front end of the extruder. At the same time, the resulting composite is continuously fed into the crosshead die, thereby obtaining a filament coated with polyphenylene sulfide (B-2).

[0177] After cooling the obtained filament, it was cut into 7mm lengths using a cutter to obtain long fiber particles, which serve as the molding material of this invention. These particles have a core-sheath structure with a composite as the core and polyphenylene sulfide (B-2) as the sheath. Furthermore, the carbon fiber bundles are arranged parallel to each other along the axial direction of the molding material, and the length of the carbon fiber bundles is substantially the same as the length of the molding material.

[0178] The resulting long fiber particles also showed no fuzzing caused by handling, indicating good operability.

[0179] The obtained long-fiber granular molding material was injection molded using a Sumitomo Heavy Industries SE75DUZ-C250 injection molding machine under the following conditions: injection time: 2 seconds; back pressure: 10 MPa; holding time: 10 seconds; cycle time: 55 seconds; barrel temperature: 280°C; mold temperature: 160°C, to produce ISO-type tensile dumbbell test pieces (molded articles). Here, barrel temperature refers to the temperature at which the molding material in the injection molding machine is heated and melted; mold temperature refers to the temperature of the mold into which the molding material is injected to form the specified shape. Cycle time refers to the time from the start of one injection molding process to the removal of the molded article. Injection pressure refers to the maximum pressure measured when the molten molding material is filled into the mold during injection molding. The resulting test pieces (molded articles) were evaluated using the above method after being left to stand in a constant temperature and humidity chamber adjusted to 23°C and 50% RH for 24 hours. The properties of the molding material, the injection pressure during injection molding, and the evaluation results of the molded products are shown in Table 1.

[0180] (Examples 2-8 and 11-15)

[0181] The type and content of reinforcing fiber bundles (A), the type and content of polyphenylene sulfide (B), and the type and content of resin (C) were changed as described in Table 1. Otherwise, the molding material (long fiber particles) was obtained by operating in the same manner as in Example 1.

[0182] The resulting particles have a composite in which epoxy resin is fully impregnated with carbon fibers. Furthermore, the composite is coated with polyphenylene sulfide (PPS). The resulting particles also have a core-sheath structure with the composite as the core and PPS as the sheath. The length of the resulting long fiber particles is 7 mm, similar to that in Example 1. Furthermore, the carbon fiber bundles are arranged parallel to each other along the axial direction of the molding material, and the length of the carbon fiber bundles is substantially the same as the length of the molding material.

[0183] The long fiber particles obtained in Examples 2-8 and 11-14 did not exhibit fuzzing due to handling, demonstrating good operability. On the other hand, the long fiber particles obtained in Example 15 contained a large amount of reinforcing fiber bundles (A), resulting in a relatively small amount of polyphenylene sulfide (B), leading to uneven coating and fuzzing, which was a result of poor operability. The obtained molding materials were injection molded in the same manner as in Example 1 to produce molded articles, and the results were evaluated. The characteristics of the molding materials, the injection pressure during injection molding, and the evaluation results of the molded articles are shown in Table 1.

[0184] (Examples 9 and 10)

[0185] Similar to Example 1, epoxy resin (Japanan EcoKi Slime Co., Ltd. jER828) was melted in a melt bath at 200°C and supplied to a copier using a gear pump. The epoxy resin was applied from the copier onto a roller heated to 200°C, forming a film. Carbon fibers (A-1) were passed through this roller while in contact with it, with a certain amount of epoxy resin adhering to each unit length of the carbon fiber bundle. The epoxy resin-adhered carbon fibers were then passed between free rollers, heated to 230°C and arranged alternately up and down in a straight line, to obtain a composite in which the epoxy resin was fully impregnated with the carbon fibers.

[0186] Next, particles of polyphenylene sulfide resin (B-1), particles of polyphenylene sulfide resin (B-2), and aliphatic polycarbodiimide ("Carboji Light HMV-8CA" (manufactured by Nisshin Textile Co., Ltd.)) were dry-blended to obtain a mixture (mixed particles) that became an intermediate raw material. In this mixture (100% by mass), the content of polyphenylene sulfide resin (B-1) was 29% by mass, the content of polyphenylene sulfide resin (B-2) was 67% by mass, and the content of aliphatic polycarbodiimide was 4% by mass.

[0187] The resulting mixed particles were fed from the main hopper of the extruder to be melt-mixed using a JSW-manufactured TEX-30α twin-screw extruder (screw diameter 30 mm, die diameter 5 mm, barrel temperature 260 °C, screw speed 150 rpm). The molten material was discharged into the die and coated around the composite material to obtain a continuous molten molding material (wire).

[0188] At this point, the discharge amount in the above-mentioned die head was adjusted so that the contents of reinforcing fiber bundles (A), polyphenylene sulfide resin (B), resin (C) and aliphatic polycarbodiimide in the molding material were respectively the values ​​recorded in Table 1 relative to the molding material (100 parts by mass).

[0189] After cooling the obtained continuous molding material (filament), it was cut with a cutter to obtain molding material (long fiber particles) with a length of 7 mm.

[0190] The resulting particles have a composite in which epoxy is fully impregnated with carbon fibers. Furthermore, in the resulting particles, this composite is coated with a resin composition consisting of polyphenylene sulfide (B-1), polyphenylene sulfide (B-2), and aliphatic polycarbodiimide (“Carboji Light HMV-8CA” (manufactured by Nisshin Textile Co., Ltd.)). The resulting particles also have a core-sheath structure with the composite as the core and the aforementioned resin composition as the sheath. The length of the resulting long fiber particles is 7 mm, similar to that in Example 1. Furthermore, the carbon fiber bundles are arranged parallel to each other along the axial direction of the molding material, and the length of the carbon fiber bundles is substantially the same as the length of the molding material.

[0191] The resulting long fiber particles also showed no fuzzing due to handling, indicating good operability. Molded articles were produced by injection molding the obtained molding material in the same manner as in Example 1, and the results were evaluated. The properties of the molding material, the injection pressure during injection molding, and the evaluation results of the molded articles are shown in Table 1.

[0192] (Comparative Examples 1-4)

[0193] The type and content of reinforcing fiber bundles (A), the type and content of polyphenylene sulfide (B), and the type and content of resin (C) were changed as described in Table 1. Otherwise, the molding material (long fiber particles) was obtained by operating in the same manner as in Example 1.

[0194] The resulting particles have a composite in which epoxy resin is fully impregnated with carbon fibers. Furthermore, the composite is coated with polyphenylene sulfide (PPS). The resulting particles also have a core-sheath structure with the composite as the core and PPS as the sheath. The length of the resulting long fiber particles is 7 mm, similar to that in Example 1. Furthermore, the carbon fiber bundles are arranged parallel to each other along the axial direction of the molding material, and the length of the carbon fiber bundles is substantially the same as the length of the molding material.

[0195] The long fiber particles obtained in Comparative Examples 1-4 did not exhibit fuzzing due to handling, demonstrating good workability. Molded articles were produced by injection molding of the obtained molding material in the same manner as in Example 1, and the evaluation results are shown in Table 2.

[0196] (Comparative Example 5)

[0197] Particles of polyphenylene sulfide resin (B-1), polyphenylene sulfide resin (B-2), polyphenylene sulfide resin (B-4), and epoxy resin (C) were dry-blended to obtain a mixture that serves as an intermediate raw material. The respective contents of this mixture are shown in Table 2.

[0198] Using a JSW-manufactured TEX-30α twin-screw extruder (screw diameter 30mm, die diameter 5mm, barrel temperature 260℃, screw speed 150rpm), the above mixture was fed from the main hopper of the extruder for melt mixing. While degassing through the downstream vacuum vent, the molten resin composition was discharged from the die orifice to obtain a continuous molding material (filament).

[0199] After cooling the obtained continuous molding material, it was cut with a cutter to obtain granules of thermoplastic resin composition with a length of 7 mm.

[0200] The resulting particles do not contain reinforcing fiber bundles (A), so the length of the reinforcing fiber bundles cannot be determined, and they also do not have a core-sheath structure.

[0201] The obtained resin granules were injection molded using a Sumitomo Heavy Industries SE75DUZ-C250 injection molding machine under the following conditions: injection time: 2 seconds; back pressure: 10 MPa; holding time: 10 seconds; cycle time: 45 seconds; barrel temperature: 280°C; mold temperature: 160°C, to produce ISO-type tensile dumbbell test pieces (molded articles). Here, barrel temperature refers to the temperature at which the molding material in the injection molding machine is heated and melted, and mold temperature refers to the temperature of the mold into which the molding material is injected to form the specified shape. The resulting test pieces (molded articles) were then placed in a constant temperature and humidity chamber adjusted to 23°C and 50% RH for 24 hours before being evaluated using the above method. The evaluation results are shown in Table 2.

[0202] Examples 1-15: Due to the low melting point of polyphenylene sulfide (PPS), the molding pressure and processing temperature during molding can be lower. As a result, the amount of gas generated during molding can be reduced, resulting in a smaller surface roughness Rz of the molded product. In other words, molding materials with smooth surfaces and excellent mechanical properties can be produced.

[0203] Furthermore, in Examples 2-4, 6-10, and 12-15, since the polyphenylene sulfide includes homopolymer polyphenylene sulfide composed only of p-phenylene sulfide units and copolymer polyphenylene sulfide composed of both p-phenylene sulfide and m-phenylene sulfide units, compared to the case of copolymer polyphenylene sulfide composed only of m-phenylene sulfide units (Examples 1 and 5), the filling of the mold with the molding material into the mold can be completed before the solidification of the molten molding material in the mold begins, while simultaneously accelerating the crystallization rate, i.e., the curing rate. Thus, the molding materials of Examples 2-4, 6-10, and 12-15 can achieve shorter cycle times.

[0204] Furthermore, compared to Example 11, which lowers the melting point of polyphenylene sulfide by copolymerizing polysiloxane, Examples 1-10 and 12-15 allow for lower molding temperatures, which further suppresses gas generation and results in a smaller surface roughness of the molded product.

[0205] Furthermore, since the carbon fiber bundle content in Examples 1-14 is within a suitable range, the injection pressure can be lower compared to Example 15.

[0206] Comparative Examples 1 to 4 are molding materials with a melting point of polyphenylene sulfide above 270°C, and poor surface smoothness of the molded articles after molding due to the generation of gas from the bundle binder of reinforcing fiber bundles during molding.

[0207] Comparative Example 5, lacking reinforcing fiber bundles (A), is a molding material with poor mechanical properties.

[0208] [Table 1]

[0209]

[0210] [Table 2]

[0211]

[0212] Explanation of symbols

[0213] 1: Reinforcing fiber bundles (A)

[0214] 2: Polyphenylene sulfide (B)

[0215] 3: Reinforcing fibers.

Claims

1. A molding material comprising reinforcing fiber bundles (A) and polyphenylene sulfide (B), wherein the polyphenylene sulfide (B) has a melting point below 270°C, the polyphenylene sulfide (B) comprising p-phenylene sulfide units and m-phenylene sulfide units, wherein the content of the m-phenylene sulfide units relative to the total amount of p-phenylene sulfide units and m-phenylene sulfide units is 7 mol% or more, and the molding material is long fiber particles.

2. The molding material according to claim 1, wherein the polyphenylene sulfide (B) comprises homopolymer polyphenylene sulfide particles consisting only of p-phenylene sulfide units and copolymer polyphenylene sulfide particles consisting of p-phenylene sulfide units and m-phenylene sulfide units.

3. The molding material according to claim 1, wherein the reinforcing fiber bundles (A) are arranged parallel to each other along the axial direction of the molding material, and the length of the reinforcing fiber bundles (A) is substantially the same as the length of the molding material.

4. The molding material according to claim 1, wherein the cooling crystallization temperature of the polyphenylene sulfide (B) is below 190°C.

5. The molding material according to claim 1, wherein the difference between the cooling crystallization temperature and the melting point of the polyphenylene sulfide (B) is above 80°C.

6. The molding material according to claim 1 is a molding material comprising the polyphenylene sulfide (B) and a composite comprising the reinforcing fiber bundle (A) and a resin (C), wherein the resin (C) is one or more resins selected from epoxy resin, phenolic resin and terpene resin, and the composite is coated with the polyphenylene sulfide (B).

7. The molding material according to claim 1, wherein the reinforcing fiber constituting the reinforcing fiber bundle (A) is carbon fiber.

8. The molding material according to any one of claims 1 to 7, wherein the slugging agent is attached to the reinforcing fiber bundle (A).

9. A molded article comprising reinforcing fibers and polyphenylene sulfide, wherein the weight-average fiber length of the reinforcing fibers is 0.3 mm or more and 3.0 mm or less, the polyphenylene sulfide has a melting point of 270°C or less, and the polyphenylene sulfide comprises p-phenylene sulfide units and m-phenylene sulfide units, wherein the content of the m-phenylene sulfide units is 7 mol% or more relative to the total amount of p-phenylene sulfide units and m-phenylene sulfide units.

10. A molded article comprising reinforcing fibers and polyphenylene sulfide, wherein the weight-average fiber length of the reinforcing fibers is 0.3 mm or more and 3.0 mm or less, the cooling crystallization temperature of the polyphenylene sulfide is below 190°C, the melting point of the polyphenylene sulfide is below 270°C, and the polyphenylene sulfide comprises p-phenylene sulfide units and m-phenylene sulfide units, wherein the content of the m-phenylene sulfide units is 7 mol% or more relative to the total amount of p-phenylene sulfide units and m-phenylene sulfide units.

11. The molded article according to claim 9 or 10, wherein the polyphenylene sulfide comprises homopolymer polyphenylene sulfide consisting only of p-phenylene sulfide units, and copolymer polyphenylene sulfide consisting of p-phenylene sulfide units and m-phenylene sulfide units.

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