JP2024139869A - Fiber-reinforced thermoplastic resin composition, fiber-reinforced thermoplastic resin molding material, and fiber-reinforced thermoplastic resin molded product - Google Patents

Abstract

[Problem] To provide a fiber-reinforced thermoplastic resin molded article having good appearance quality and heat resistance. [Solution] A fiber-reinforced thermoplastic resin composition comprising a thermoplastic matrix resin (A) which is at least one selected from an amorphous resin having a glass transition point exceeding 190°C and a crystalline resin having a melting point exceeding 300°C, a rosin resin (B) having a weight loss rate of less than 5% at 350°C, and reinforcing fibers (C) which include at least carbon fibers. [Selected Figures] None

Description

The present invention relates to a fiber-reinforced thermoplastic resin composition containing reinforcing fibers, a thermoplastic matrix resin, and a rosin resin, a fiber-reinforced thermoplastic resin molding material, and a fiber-reinforced thermoplastic resin molded product.

Compositions and molded articles containing reinforcing fibers and thermoplastic matrix resins are lightweight and have excellent mechanical properties, and are therefore widely used in sporting goods, aerospace, and general industrial applications.

Reinforcing fibers have an excellent reinforcing effect when combined with a thermoplastic matrix resin, but in order to obtain a good appearance, it is necessary to uniformly disperse the reinforcing fibers in the thermoplastic matrix resin. One method for improving fiber dispersion in fiber-reinforced thermoplastic resin molded products is to use a terpene resin as an additive (see, for example, Patent Document 1).

On the other hand, in recent years, fiber-reinforced resins have been attracting more attention, and their applications have been subdivided into many different areas, which has led to a demand for better properties. In particular, aircraft parts, engine parts, motor parts, and other parts are expected to be used at high temperatures. Metal materials have been used for these parts from the perspective of heat resistance, but by using highly heat-resistant resins as thermoplastic matrix resins, the heat resistance issue has been resolved, and there is an increasing demand for alternative composite materials that have better specific strength and specific stiffness than metals. Even in fiber-reinforced thermoplastic resin molded products using such highly heat-resistant thermoplastic matrix resins, a method of using polyether ether ketone oligomers as an additive has been proposed as a means of improving fiber dispersion (for example, Patent Document 2).

JP 2010-248482 A JP 2013-6960 A

However, the technologies described in Patent Documents 1 and 2 still do not provide a good balance between good appearance quality and heat resistance.

When a high heat-resistant thermoplastic matrix resin is used, the molding process temperature is higher than that of other resins. The additive described in Patent Document 1 lacks heat resistance, and the effect of the additive in improving fiber dispersion is limited. If the dispersion of the reinforcing fibers is not uniform, that is, if the fibers remain in the form of fiber bundles, this can cause poor appearance quality of the molded product, such as increased local surface roughness and color unevenness.
Also in the method described in Patent Document 2, the molecular weight of the polyether ether ketone oligomer used as an additive is low, and gas burning is not sufficiently suppressed.

In order to solve the above problems, the present invention mainly comprises the following components.
(1) A fiber-reinforced thermoplastic resin composition comprising: (A) a thermoplastic matrix resin which is at least one selected from an amorphous resin having a glass transition point exceeding 190°C and a crystalline resin having a melting point exceeding 300°C; (B) a rosin resin having a weight loss rate of less than 5% at 350°C; and (C) reinforcing fibers which include at least carbon fibers.
(2) The fiber-reinforced thermoplastic resin composition according to (1), wherein the rosin resin (B) is a rosin polyol.
(3) The fiber-reinforced thermoplastic resin composition according to (1) or (2), wherein the thermoplastic matrix resin (A) is at least one selected from a polyetherimide resin, a polyaryl ether ketone resin, and a polyether sulfone resin.
(4) The fiber-reinforced thermoplastic resin composition according to any one of (1) to (3), wherein the reinforcing fiber (C) is only carbon fiber.
(5) The fiber-reinforced thermoplastic resin composition according to any one of (1) to (4), wherein the weight ratio of the rosin resin (B) is 15% or more or 50% or less with respect to the reinforcing fiber (C).
(6) A fiber-reinforced thermoplastic resin molding material comprising: a thermoplastic matrix resin (A) which is at least one selected from an amorphous resin having a glass transition point exceeding 190°C and a crystalline resin having a melting point exceeding 300°C; a rosin resin (B) having a weight loss rate of less than 5% at 350°C; and reinforcing fibers (C) which contain at least carbon fibers, wherein the fiber-reinforced thermoplastic resin molding material comprises the thermoplastic matrix resin (A) on the outside of a composite (D) obtained by impregnating a reinforcing fiber bundle containing the reinforcing fiber (C) with the rosin resin (B), and the reinforcing fibers (C) are arranged approximately parallel to the axial direction of the molding material.
(7) The fiber-reinforced thermoplastic resin molding material according to (6), wherein the length of the reinforcing fiber (C) and the length of the molding material are substantially the same.
(8) The fiber-reinforced thermoplastic resin molding material according to (6) or (7), wherein the thermoplastic matrix resin (A) has a core-sheath structure in which the composite (D) is covered therearound.
(9) The fiber reinforced thermoplastic resin molding material according to any one of (6) to (8), having a length of 1 mm or more or 50 mm or less.
(10) A fiber-reinforced thermoplastic resin molded product using the fiber-reinforced thermoplastic resin composition according to any one of (1) to (5).

The fiber-reinforced thermoplastic resin composition and fiber-reinforced thermoplastic resin molding material of the present invention contain a rosin resin with excellent thermal decomposition resistance and a highly heat-resistant thermoplastic matrix resin, making it possible to obtain fiber-reinforced thermoplastic resin molded products with good appearance quality and heat resistance.

Fiber-reinforced thermoplastic resin molded products using the fiber-reinforced thermoplastic resin composition and fiber-reinforced thermoplastic resin molding material of the present invention are useful for aircraft parts, automobile parts, electrical and electronic devices, etc. They are particularly useful for aircraft parts, engine parts, and motor parts that require high heat resistance.

FIG. 1 is a schematic diagram showing an example of a cross-sectional shape of a composite body according to the present invention. FIG. 1 is a schematic diagram showing an example of a preferred vertical cross-sectional form of a molding material in the present invention. FIG. 1 is a schematic diagram showing an example of a preferred cross-sectional shape of a molding material in the present invention. FIG. 2 is a schematic diagram showing another example of a preferred cross-sectional shape of a molding material in the present invention.

The present invention will be described in detail below with examples of its implementation.

The thermoplastic matrix resin (A) in the fiber-reinforced thermoplastic resin composition of the present invention is at least one type of thermoplastic matrix resin selected from an amorphous resin having a glass transition point of more than 190°C and a crystalline resin having a melting point of more than 300°C.

The glass transition point is defined as the point where a line equidistant from the line extending the low-temperature and high-temperature baselines in the vertical direction intersects with the curve of the step-like change in the glass transition in the differential scanning calorimetry chart obtained by heating the resin from 30°C to a temperature about 30°C higher than the end of the melting peak (for crystalline resins) or about 30°C higher than the end of the glass transition (for amorphous resins) at a heating rate of 10°C/min (1st Run), holding the resin in that state for 10 minutes, then cooling it at a cooling rate of 10°C/min to 30°C or lower, and then heating it again from 30°C to a temperature about 30°C higher than the end of the glass transition at a heating rate of 20°C/min (2nd Run) using differential scanning calorimetry (DSC) in accordance with JIS K-7122 (1987).

The melting point is defined as the temperature at the top of the crystalline melting peak in the differential scanning calorimetry chart of the second run obtained by measuring the glass transition point using differential scanning calorimetry (DSC) in accordance with JIS K-7121 (1987), changing the heating rate in the second run to 10°C/min, and then heating the resin from 30°C to a temperature approximately 30°C higher than the end of the crystalline melting peak.

In this measurement, if a crystal melting peak can be confirmed, it is defined as a crystalline resin, and if not, it is defined as an amorphous resin.

When there are multiple melting peaks or glass transition points, the highest melting point or glass transition point is taken as the melting point or glass transition point of the matrix resin.

By using these resins, it is possible to obtain good mechanical properties even in high temperature environments. Examples include polyetherimide resins, polyimide resins, polyamideimide resins, polysulfone resins, polyethersulfone resins, polyphenylene ether resins, modified polyphenylene ether resins, polyketone resins, polyaryl ketone resins, polyaryl ether ketone resins (particularly polyether ether ketone resins and polyether ketone ketone resins), polyarylate resins, polyamide resins, etc. Two or more of these can also be used in combination.

Among the thermoplastic matrix resins (A), polyetherimide resins, polyaryletherketone resins, and polyethersulfone resins are preferred, as they have an excellent balance of mechanical properties, fluidity, and heat resistance.

The fiber-reinforced thermoplastic resin composition of the present invention preferably contains 20 to 94.5 parts by weight of the thermoplastic matrix resin (A) per 100 parts by weight of the total of the thermoplastic matrix resin (A), the rosin resin (B), and the reinforcing fibers (C).

The rosin resin (B) contained in the fiber-reinforced thermoplastic resin composition of the present invention is a rosin resin whose weight loss rate at 350°C is less than 5% by weight. By using these, gas burning can be suppressed even at the molding temperature of the fiber-reinforced thermoplastic resin composition of the present invention.

The weight loss rate of rosin resin (B) at 350°C is determined by measuring the weight at 350°C by thermogravimetric analysis (TGA) using a platinum sample pan in a nitrogen atmosphere at a heating rate of 10°C/min, and calculating the weight loss rate based on the weight at room temperature.

Examples of the rosin resin (B) include purified rosin obtained by purifying natural rosin (gum rosin, tall oil rosin, wood rosin) derived from Masson pine, Slash pine, Merkus pine, Siberian pine, Loblolly pine, and Daio pine by vacuum distillation, steam distillation, extraction, recrystallization, etc. (hereinafter, natural rosin and purified rosin are collectively referred to as unmodified rosin), hydrogenated rosin obtained by hydrogenating the unmodified rosin, disproportionated rosin obtained by disproportionating the unmodified rosin, polymerized rosin obtained by polymerizing the unmodified rosin, acid-modified rosin such as acrylated rosin, maleated rosin, and fumarated rosin, esterified products of the rosin (hereinafter, these esterified products are referred to as rosin esters), rosin phenolic resin, and rosin polyol. The rosin resin may be used alone or in combination of two or more types.

The rosin resin (B) is preferably a rosin polyol, since it has excellent resistance to thermal decomposition at the molding temperature of the high heat-resistant matrix resin.

Rosin polyol is a compound having at least two rosin skeletons and at least two hydroxyl groups in the molecule. Examples of the rosin polyol include the reaction product of the unmodified rosin, hydrogenated rosin, or disproportionated rosin with an epoxy resin (see JP-A-5-155972). Examples of the epoxy resin include bisphenol type epoxy resins, novolac type epoxy resins, resorcinol type epoxy resins, phenol aralkyl type epoxy resins, naphthol aralkyl type epoxy resins, aliphatic polyepoxy compounds, alicyclic epoxy compounds, glycidylamine type epoxy compounds, glycidyl ester type epoxy compounds, monoepoxy compounds, naphthalene type epoxy compounds, biphenyl type epoxy compounds, epoxidized polybutadiene, epoxidized styrene-butadiene-styrene block copolymers, epoxy group-containing polyester resins, epoxy group-containing polyurethane resins, epoxy group-containing acrylic resins, stilbene type epoxy compounds, triazine type epoxy compounds, fluorene type epoxy compounds, triphenolmethane type epoxy compounds, alkyl-modified triphenolmethane type epoxy compounds, dicyclopentadiene type epoxy compounds, and aryl alkylene type epoxy compounds.

Examples of the bisphenol type epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AD type epoxy resin, hydrogenated bisphenol A type epoxy resin, hydrogenated bisphenol F type epoxy resin, hydrogenated bisphenol AD type epoxy resin, and tetrabromobisphenol A type epoxy resin.

Examples of the novolac type epoxy resin include cresol novolac type epoxy resin, phenol novolac type epoxy resin, α-naphthol novolac type epoxy resin, bisphenol A type novolac type epoxy resin, and brominated phenol novolac type epoxy resin.

Examples of the aliphatic polyepoxy compound include 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, glycerol diglycidyl ether, glycerol triglycidyl ether, trimethylolpropane diglycidyl ether, trimethylolpropane triglycidyl ether, diglycerol triglycidyl ether, sorbitol tetraglycidyl ether, and diglycidyl ether.

Examples of the alicyclic epoxy compounds include 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate, 2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy)cyclohexane-meta-dioxane, bis(3,4-epoxycyclohexylmethyl)adipate, bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate, 3,4-epoxy-6-methylcyclohexyl-3,4-epoxy-6'-methylcyclohexanecarboxylate, methylene bis(3,4-epoxycyclohexane), dicyclopentadiene diepoxide, ethylene glycol di(3,4-epoxycyclohexylmethyl)ether, ethylene bis(3,4-epoxycyclohexanecarboxylate), lactone-modified 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate, and the like.

Examples of the glycidylamine type epoxy compound include tetraglycidyldiaminodiphenylmethane, triglycidyl paraaminophenol, triglycidyl meta-aminophenol, and tetraglycidyl meta-xylylenediamine.

Examples of the glycidyl ester type epoxy compounds include diglycidyl phthalate, diglycidyl hexahydrophthalate, and diglycidyl tetrahydrophthalate.

The method for producing the rosin polyol is not particularly limited, but an example thereof is a method in which the unmodified rosin, hydrogenated rosin or disproportionated rosin is subjected to a ring-opening addition reaction with an epoxy resin at 120°C to 200°C in the presence of a catalyst. Examples of the catalyst that can be used include amine catalysts such as trimethylamine, triethylamine, tributylamine, benzyldimethylamine, pyridine, and 2-methylimidazole, quaternary ammonium salts such as benzyltrimethylammonium chloride, Lewis acids, borate esters, organometallic compounds, and organometallic salts.

The softening point of the rosin resin (B) is 80°C to 200°C, and is preferably about 80°C to 180°C, more preferably about 90°C to 160°C, in order to provide excellent mechanical strength in fiber-reinforced resins and excellent handling and processability.

The number average molecular weight of the rosin resin (B) is preferably 1000 to 50,000. If the number average molecular weight is 1000 or more, the bending strength and tensile strength of the molded product when the composition is molded can be improved, and gas burning due to vaporization during molding can be suppressed. The number average molecular weight is more preferably 2000 or more, and even more preferably 4000 or more. Furthermore, if the number average molecular weight is 50,000 or less, the viscosity of the rosin resin (B) is appropriately low, so that the impregnation of the reinforcing fiber (C) contained in the molded product is excellent, and the dispersibility of the reinforcing fiber (C) in the molded product when the composition is molded can be further improved. The number average molecular weight is more preferably 25,000 or less, more preferably 15,000 or less, and even more preferably 10,000 or less. The number average molecular weight of such a compound can be measured using gel permeation chromatography (GPC).

The content of rosin resin (B) in the fiber-reinforced thermoplastic resin composition of the present invention is preferably 0.5 to 30 parts by weight per 100 parts by weight of the total of reinforcing fiber (C), thermoplastic matrix resin (A) and rosin resin (B). If the content of rosin resin (B) is 0.5 parts by weight or more, the fluidity and dispersibility of reinforcing fiber (C) in the molded product are further improved. 1 part by weight or more is preferable, and 2 parts by weight or more is preferable. On the other hand, if the content of rosin resin (B) is 30 parts by weight or less, gas burning during molding can be suppressed. 20 parts by weight or less is preferable, 15 parts by weight or less is more preferable, and 10 parts by weight or less is even more preferable. In addition, from the viewpoint of fluidity, dispersibility and suppression of gas burning, it is preferable that the weight ratio of rosin resin (B) to reinforcing fiber (C) is 15% or more or 50% or less.

The reinforcing fiber (C) contained in the fiber-reinforced thermoplastic resin composition of the present invention contains at least carbon fiber. The reinforcing fiber (C) may contain fibers other than carbon fiber, but from the viewpoint of specific strength and specific rigidity, it is preferable that the reinforcing fiber (C) contains only carbon fiber.

Examples of types of carbon fiber include PAN-based carbon fiber, pitch-based carbon fiber, cellulose-based carbon fiber, vapor-grown carbon fiber, and graphitized fibers of these. PAN-based carbon fiber is carbon fiber made from polyacrylonitrile fiber. Pitch-based carbon fiber is carbon fiber made from petroleum tar or petroleum pitch. Cellulose-based carbon fiber is carbon fiber made from viscose rayon or cellulose acetate. Vapor-grown carbon fiber is carbon fiber made from hydrocarbons. Of these, PAN-based carbon fiber is preferred because of its excellent balance between strength and elastic modulus. In order to further improve conductivity, carbon fiber coated with a metal such as nickel, copper, or ytterbium can also be used.

The average fiber diameter of the carbon fibers is not particularly limited, but from the viewpoint of the mechanical properties and surface appearance of the molded product, it is preferably 1 to 20 μm, and more preferably 3 to 15 μm. There is no particular limit to the number of single fibers in the reinforcing fiber bundle, but it is preferably 100 to 350,000, and from the viewpoint of productivity, it is more preferably 20,000 to 100,000.

The carbon fibers may be surface-treated for the purpose of improving the adhesion between the carbon fibers and the thermoplastic matrix resin (A). Examples of surface treatment methods include electrolytic treatment, ozone treatment, and ultraviolet treatment.

The carbon fibers may be coated with a sizing agent for the purpose of preventing fuzzing of the carbon fibers and improving adhesion between the carbon fibers and the thermoplastic matrix resin (A). Specific examples of sizing agents include epoxy resins, phenolic resins, polyethylene glycol, polyurethane, polyester, emulsifiers, and surfactants. Two or more of these may be used. These sizing agents are contained on the surface of the carbon fibers in the molding material. The sizing agent is preferably water-soluble or water-dispersible, and is preferably an epoxy resin that has excellent wettability with the carbon fibers. Among these, a multifunctional epoxy resin is more preferable.

The fiber-reinforced thermoplastic resin composition of the present invention preferably contains 5 to 50 parts by weight of reinforcing fiber (C) per 100 parts by weight of the total of the thermoplastic matrix resin (A), the rosin resin (B), and the reinforcing fiber (C). If the content of reinforcing fiber (C) is less than 5 parts by weight, the tensile strength and impact strength of the molded article when the composition is molded will decrease. The content of reinforcing fiber (C) is preferably 10 parts by weight or more. Furthermore, if the content of reinforcing fiber (C) exceeds 50 parts by weight, the dispersibility of the reinforcing fiber (C) in the molded article will decrease, often causing a decrease in the impact strength and appearance quality of the molded article. The content of reinforcing fiber (C) is preferably 30 parts by weight or less.

In the fiber-reinforced thermoplastic resin composition of the present invention, the weight average fiber length (Lw) of the reinforcing fiber (C) is preferably 0.1 to 7.0 mm. If the weight average fiber length (Lw) is 0.1 mm or more, the mechanical properties of the molded product are further improved. Lw is preferably 0.3 mm or more. On the other hand, if the weight average fiber length (Lw) is 7.0 mm or less, the entanglement between the single yarns of the reinforcing fiber (C) is suppressed and the dispersibility is further improved, so that the mechanical properties and the appearance quality of the molded product are further improved. Lw is more preferably 5.0 mm or less, and even more preferably 4.0 mm or less. Here, the "weight average fiber length" in the present invention refers to the weight average fiber length calculated from the following formula that takes into account the contribution of the fiber length, rather than simply taking the number average by applying the calculation method of the weight average molecular weight to the calculation of the fiber length. However, the following formula is applied when the fiber diameter and density of the reinforcing fiber (C) are constant.
Weight average fiber length = Σ (Mi ² × Ni) / Σ (Mi × Ni)
Mi: fiber length (mm)
Ni: Number of reinforcing fibers of fiber length Mi

The weight average fiber length can be measured by the following method. Using an optical microscope with a hot stage, cut out an appropriate test piece from the molded product, heat it between glass plates on a hot stage set appropriately according to the melting temperature of the thermoplastic matrix resin (A) used, form it into a film, and uniformly disperse it. In the state where the thermoplastic matrix resin (A) is molten, observe it with an optical microscope (50 to 200 times). Measure the fiber length of 1,000 randomly selected reinforcing fibers (C) and calculate the weight average fiber length (Lw) from the above formula. Alternatively, put the test piece cut out from the molded product into a solvent in which the thermoplastic matrix resin (A) dissolves, and apply an appropriate heat treatment to prepare a solution in which the reinforcing fibers (C) are uniformly dispersed. Then, filter the solution and observe the reinforcing fibers (C) dispersed on the filter paper with an optical microscope (50 to 200 times). Measure the fiber length of 1,000 randomly selected reinforcing fibers (C) and calculate the weight average fiber length (Lw) from the above formula. The filter paper used here may be Advantec's quantitative filter paper (model number: No. 5C).

The fiber-reinforced thermoplastic resin composition of the present invention may contain other components in addition to the components (A) to (C) described above, provided that the object of the present invention is not impaired. Examples of other components include thermoplastic resins and thermosetting resins used as polymer blends or polymer alloys, inorganic fillers other than carbon fiber (glass fiber, organic fiber, etc.), flame retardants, crystal nucleating agents, UV absorbers, antioxidants, impact absorbers, vibration dampers, antibacterial agents, insect repellents, deodorants, color inhibitors, heat stabilizers, release agents, antistatic agents, plasticizers, lubricants, colorants, pigments, dyes, foaming agents, foam control agents, and coupling agents.

Next, we will explain the fiber-reinforced thermoplastic resin molding material of the present invention.

The composition of the fiber-reinforced thermoplastic resin molding material of the present invention is the same as that of the fiber-reinforced thermoplastic resin composition of the present invention, and includes a thermoplastic matrix resin (A) that is at least one selected from an amorphous resin having a glass transition point exceeding 190°C and a crystalline resin having a melting point exceeding 300°C, a rosin resin (B) whose weight loss rate at 350°C is less than 5%, and reinforcing fibers (C) that include at least carbon fibers.

The preferred material composition is also the same as that of the fiber-reinforced thermoplastic resin composition of the present invention, and it is preferred that the thermoplastic matrix resin (A) is a polyetherimide resin, a polyaryletherketone resin, and a polyethersulfone resin, the rosin resin (B) is a rosin polyol, and the reinforcing fiber (C) is only carbon fiber.

The weight ratio of each component is preferably within a specific range, as in the fiber-reinforced thermoplastic resin composition of the present invention. Specifically, the thermoplastic matrix resin (A) is preferably 20 to 94.5 parts by weight, 0.5 to 30 parts by weight of rosin resin (B), and 5 to 50 parts by weight of reinforcing fiber (C) per 100 parts by weight of the total of thermoplastic matrix resin (A), rosin resin (B), and reinforcing fiber (C). In addition, it is more preferable that the weight ratio of rosin resin (B) is 15% or more or 50% or less relative to the reinforcing fiber (C).

Next, the form of the fiber-reinforced thermoplastic resin molding material of the present invention will be described. The fiber-reinforced thermoplastic resin molding material of the present invention contains a thermoplastic matrix resin (A) on the outside of a composite (D) formed by impregnating a reinforcing fiber bundle containing reinforcing fibers (C) with a rosin resin (B), and the reinforcing fibers (C) are arranged approximately parallel to the axial direction of the molding material.

Figure 1 is a schematic diagram showing an example of the cross-sectional shape of the composite (D) of the present invention. As shown in Figure 1, in the composite (D) of the present invention, rosin resin (B) is filled between each single fiber of the reinforcing fiber (C). In other words, each single fiber of the reinforcing fiber (C) is dispersed like an island in a sea of rosin resin (B). In the present invention, the longitudinal section means a section in a plane including the axial direction, and the transverse section means a section in a plane perpendicular to the axial direction. In addition, when the molding material is cylindrical, such as a pellet, the axial direction refers to the axis of the cylinder.

The phrase "arranged substantially parallel" refers to a state in which the long axis of the reinforcing fiber (C) and the long axis of the molding material are oriented in the same direction. The angle between the axes is preferably 20° or less, more preferably 10° or less, and even more preferably 5° or less. By arranging the reinforcing fibers (C) substantially parallel, the fiber length in the molding material can be kept uniform, and fiber dispersion can be improved in that fibers with extremely long fiber lengths can be eliminated.

In addition, it is preferable that the length of the reinforcing fiber (C) and the length of the molding material are substantially the same. "Substantially the same length" means that the reinforcing fiber (C) is not intentionally cut inside the molding material, and the molding material does not substantially contain reinforcing fiber (C) whose fiber length differs significantly from the overall length of the molding material. A form in which the reinforcing fiber (C) has substantially the same length as the molding material can improve fiber dispersion in that it is possible to eliminate fibers whose fiber length is significantly longer than the overall length of the molding material. Furthermore, the mechanical properties are improved by eliminating fibers whose fiber length is significantly shorter than the overall length of the molding material.

In the fiber-reinforced thermoplastic resin molding material of the present invention, by configuring the composite (D) to include a thermoplastic matrix resin (A) on the outside, the thermoplastic matrix resin (A) can protect the composite (D). This prevents the composite (D) from being crushed or scattered due to impacts or abrasions during transportation or handling of the molding material, and the shape of the molding material can be maintained, improving handleability.

2 and 3 are schematic diagrams showing an example of the cross-sectional form of the fiber-reinforced thermoplastic resin molding material of the present invention. The cross-sectional form of the molding material is not limited to that shown in the figure, as long as the thermoplastic matrix resin (A) is included on the outside of the composite (D). However, from the viewpoint of the handling property, the cross section of the molding material is preferably a form in which the composite (D) is sandwiched between layers of thermoplastic matrix resin (A) as shown in the longitudinal cross-sectional form of FIG. 2. More preferred forms include a form in which the composite (D) is arranged in a core-sheath structure in which the thermoplastic matrix resin (A) covers the periphery of the composite (D), as shown in the transverse cross-sectional forms of FIGS. 3 and 4. Alternatively, the composite (D) may be arranged so that the thermoplastic matrix resin (A) covers a plurality of composites (D) as shown in FIG. 4. In that case, the number of composites (D) is preferably about 2 to 6.

The length of the reinforcing fiber (C) and the molding material is preferably 1 mm or more and 50 mm or less, and more preferably 5 mm or more and 15 mm or less. By adjusting the length to the above range, the fluidity and ease of handling during molding can be sufficiently improved. An example of a particularly preferred embodiment of the molding material cut to an appropriate length in this way is long fiber pellets for injection molding. In addition, it is preferable that the molding material maintains approximately the same cross-sectional shape in the longitudinal direction and is continuous.

The composite (D) may be in a state where the thermoplastic matrix resin (A) and the rosin resin (B) partially penetrate into a part of the composite (D) near the boundary and are compatible with each other, or the fiber bundles of the reinforcing fibers (C) may be impregnated with the thermoplastic matrix resin (A) and the rosin resin (B).

The fiber-reinforced thermoplastic resin molding material of the present invention can be obtained by any known manufacturing method, including but not limited to the following method. For example, it can be obtained by the following method.

First, rovings of reinforcing fibers (C) are combined in parallel to the longitudinal direction of the fibers to produce a fiber bundle containing reinforcing fibers (C). Next, the fiber bundle is impregnated with molten rosin resin (B) to produce a composite (D). Furthermore, the fiber bundle or composite (D) is guided to an impregnation die filled with molten thermoplastic matrix resin (A), and the resin composition containing the thermoplastic matrix resin (A) is coated on the outside of the composite, which is then pulled out through a nozzle. After cooling and solidifying, the composite is pelletized to a specified length to obtain a molding material.

The molding material produced by the above method may also be dry-blended with pellets of melt-kneaded thermoplastic matrix resin (A) to obtain a mixture of molding materials. In this case, the content of reinforcing fiber (C) in the molded product can be easily adjusted.

Here, dry blending differs from melt kneading in that multiple materials are stirred and mixed at a temperature at which the resin components do not melt, resulting in a substantially homogeneous state. It is preferably used when using pellet-shaped molding materials, such as in injection molding or extrusion molding.

Next, we will explain the fiber-reinforced thermoplastic resin molded product of the present invention.

The composition of the fiber-reinforced thermoplastic resin molded product of the present invention is the same as that of the fiber-reinforced thermoplastic resin composition of the present invention, and includes a thermoplastic matrix resin (A) that is at least one selected from an amorphous resin having a glass transition point exceeding 190°C and a crystalline resin having a melting point exceeding 300°C, a rosin resin (B) that has a weight loss rate of less than 5% at 350°C, and reinforcing fibers (C) that include at least carbon fibers.

The preferred material composition is also the same as that of the fiber-reinforced thermoplastic resin composition of the present invention, and it is preferred that the thermoplastic matrix resin (A) is a polyetherimide resin, a polyaryletherketone resin, and a polyethersulfone resin, the rosin resin (B) is a rosin polyol, and the reinforcing fiber (C) is only carbon fiber.

The weight ratio of each component is preferably within a specific range, as in the fiber-reinforced thermoplastic resin composition of the present invention. Specifically, it is preferable that the thermoplastic matrix resin (A) is 20 to 94.5 parts by weight, the rosin resin (B) is 0.5 to 30 parts by weight, and the reinforcing fiber (C) is 5 to 50 parts by weight, relative to a total of 100 parts by weight of the thermoplastic matrix resin (A), the rosin resin (B), and the reinforcing fiber (C). In addition, it is more preferable that the weight ratio of the rosin resin (B) is 15% or more or 50% or less relative to the reinforcing fiber (C).

In the fiber-reinforced thermoplastic resin molded product of the present invention, the weight average fiber length (Lw) of the reinforcing fibers (C) is preferably 0.1 to 7.0 mm, similar to the fiber-reinforced thermoplastic resin composition of the present invention.

Next, as a molding method for obtaining a fiber-reinforced thermoplastic resin molded product in the present invention, a molding method using a mold is preferable, and various molding methods such as injection molding, extrusion molding, and press molding can be used. In particular, a molding method using an injection molding machine can continuously obtain a stable molded product. There are no particular regulations for the conditions of injection molding, but for example, the following conditions are preferable: injection time: 0.1 seconds to 20 seconds, more preferably 1 second to 10 seconds, back pressure: 0.1 MPa to 20 MPa, more preferably 3 MPa to 15 MPa, holding pressure: 1 MPa to 150 MPa, more preferably 5 MPa to 100 MPa, holding pressure time: 1 second to 30 seconds, more preferably 5 seconds to 20 seconds, cylinder temperature: 350 ° C to 400 ° C, mold temperature: 80 ° C to 190 ° C. Here, the cylinder temperature refers to the temperature of the part of the injection molding machine where the molding material is heated and melted, and the mold temperature refers to the temperature of the mold into which the resin is injected to form a predetermined shape. By appropriately selecting these conditions, particularly the injection time, back pressure and mold temperature, the fiber length of the reinforcing fibers in the molded product can be easily adjusted.

Fiber-reinforced thermoplastic resin molded products using the fiber-reinforced thermoplastic resin composition and fiber-reinforced thermoplastic resin molding material of the present invention have excellent heat resistance and appearance quality. Fiber-reinforced thermoplastic resin molded products using the fiber-reinforced thermoplastic resin composition and fiber-reinforced thermoplastic resin molding material of the present invention are useful for aircraft parts, automobile parts, electrical and electronic devices, etc. They are particularly useful for aircraft parts, engine parts, and motor parts that require high heat resistance.

Aircraft parts include drone structural parts (frame structural joints, propellers, monocoque fuselages), drone exterior parts, secondary structural materials for UAMs, exterior parts for UAMs, engine parts, interior materials, etc. Automobile parts include intake and exhaust system parts, engine covers, cylinder head covers, hydraulic control valves, engine hoses, radiator hoses, gear boxes, bearing retainers, etc. The fiber-reinforced thermoplastic resin composition and fiber-reinforced thermoplastic resin molded products of the present invention are also suitable as electrical and electronic parts, and are used for motor insulating cores, motor bearings, coil bobbins, etc.

The present invention will be explained in more detail with reference to the following examples, but the present invention is not limited to the description of these examples. First, the methods for evaluating the various characteristics used in the examples will be explained.

(1) Appearance quality evaluation of molded products (fiber dispersion evaluation)
The number of undispersed CF bundles present on the front and back surfaces of the square plate-shaped test pieces for dispersibility evaluation obtained in each Example and Comparative Example was visually counted. The evaluation was performed on 50 molded products, and the fiber dispersion of the total number was judged according to the following criteria, with A and B being passed.
A: No undispersed CF bundles. B: 1 to 2 undispersed CF bundles. C: 3 or more undispersed CF bundles.

(2) Appearance quality evaluation of molded products (gas burn evaluation)
The percentage of discolored areas of 2 mm or more at the edge of the ISO dumbbell-shaped test pieces obtained in each Example and Comparative Example was visually counted. Evaluation was performed on 50 molded products, and the results were judged according to the following criteria, with A and B being considered as pass.
A: No samples showed gas burns. B: 1 to 2 samples showed gas burns. C: 3 or more samples showed gas burns.

(3) Heat resistance (tensile strength retention at high temperatures)
For the ISO dumbbell test pieces obtained in each Example and Comparative Example, tensile tests were performed at room temperature (25°C) and 125°C at a tensile speed of 5 mm/min using a tensile tester Autograph AG-50kNX (manufactured by Shimadzu Corporation) in accordance with ISO527 (2012), to determine the maximum point stress. Note that, in the 125°C test, the test was performed under conditions in which the temperature inside the thermostatic chamber was kept the same using a thermostatic chamber attached to the device.

(4) Heat resistance (deflection temperature under load)
For the strip-shaped test pieces obtained in each Example and Comparative Example, the load deflection temperature (1.80 MPa) was measured using a HDT tester 6M-2 manufactured by Toyo Seiki Co., Ltd. in accordance with ISO 75 (2013).

(5) Measurement of Melting Point of Thermoplastic Matrix Resin (A) The melting point of the sample was measured using a PerkinElmer differential scanning calorimeter (DSC-7 type) in accordance with JIS K-7121 (1987).

(A) 1st Run Measurement: 5 mg of sample was used in a nitrogen atmosphere. (i) the temperature was increased from 30° C. to 380° C. at a rate of 10° C./min, (ii) the temperature was maintained at 380° C. for 10 minutes, and (iii) the temperature was cooled from 380° C. to 30° C. at a rate of 10° C./min.

(B) 2nd Run Measurement (iv) After the 1st Run was completed, the temperature was increased from 30° C. to 380° C. at a rate of 10° C./min.
When a crystalline melting peak was confirmed in (i), the resin was regarded as a crystalline resin, and the temperature at the top of the crystalline melting peak was regarded as the melting point.

(6) Glass transition temperature measurement of thermoplastic matrix resin (A) When no crystalline melting peak was observed in the measurement by (5), the resin was treated as amorphous, and the measurement was carried out under the same conditions as in (5) except that the heating rate in (iv) was changed to 20° C./min and the temperature range was changed from 30° C. to 250° C., to derive the glass transition temperature in (iv) (obtained from the point where a straight line equidistant in the vertical direction from the straight line extending the baselines on the low and high sides intersects with the curve of the stepwise change in the glass transition).

(A) 1st Run Measurement: 5 mg of sample was used in a nitrogen atmosphere. (i) the temperature was increased from 30° C. to 250° C. at a rate of 10° C./min, (ii) the temperature was maintained at 250° C. for 10 minutes, and (iii) the temperature was cooled from 250° C. to 30° C. at a rate of 10° C./min.

(B) 2nd Run Measurement (iv) After the 1st Run was completed, the temperature was increased from 30° C. to 250° C. at a rate of 20° C./min.

If a crystalline melting peak was confirmed in (i), the resin was judged to be crystalline, and the temperature at the peak top of the crystalline melting peak was taken as the melting point. If a crystalline melting peak was not confirmed, the resin was judged to be amorphous, and the glass transition point in (iv) was derived. (This was determined from the point where a line equidistant in the vertical direction from the line extending the baselines on the low and high temperatures intersects with the curve of the step-like change in the glass transition.)

(6) Measurement of Rosin Resin (B) during Heating The sample was measured by thermogravimetric analysis (TGA). Using a platinum sample pan, the sample was measured in a nitrogen atmosphere at a temperature increase rate of 10° C./min, and the weight loss rate at 350° C. was measured.

Thermoplastic matrix resin (A)
(A-1)
A polyetherimide resin (manufactured by Sabic, "ULTEM" (registered trademark) 1040) was used.

(A-2)
A polyether ether ketone resin ("PEEK 151G" manufactured by Victrex) was used.

(A-3)
A polyether ketone ketone resin (manufactured by Arkema, "KEPSTAN" (registered trademark) 7003) was used.

(A-4)
A polyethersulfone resin ("Sumikaexcel" (registered trademark) 3600G, manufactured by Sumitomo Chemical Co., Ltd.) was used.

(A-5)
A polycarbonate resin (manufactured by Teijin Chemical Co., Ltd., "Panlite" (registered trademark) L-1225L) was used.

Rosin resin (B)
(B-1)
The rosin resin (B-1) obtained in Production Example 1 (weight loss rate at 350° C.: 2.5%) was used.

(B-2)
Polymerized rosin: (Pine Crystal KR140 manufactured by Arakawa Chemical Industries, Ltd., weight loss rate at 350° C.: 61.5%) was used.

Reference Example 1. Preparation of Carbon Fiber (C) A copolymer mainly composed of polyacrylonitrile was spun, baked, and surface oxidized to obtain a continuous carbon fiber having a total number of single filaments of 24,000, a single fiber diameter of 7 μm, a mass per unit length of 1.6 g/m, a specific gravity of 1.8 g/cm ³ , and a surface oxygen concentration ratio [O/C] of 0.2. The strand tensile strength of this continuous carbon fiber was 4,880 MPa, and the strand tensile modulus was 225 GPa. Subsequently, a sizing agent mother liquid was prepared by dissolving glycerol polyglycidyl ether as a polyfunctional compound in water to a concentration of 2% by weight, and the sizing agent was applied to the carbon fiber by the immersion method, and the carbon fiber was dried at 230° C. The amount of sizing agent attached to the carbon fiber thus obtained was 1.0% by weight.

Production Example 1
Preparation of Rosin Resin (B-1) 100 parts of hydrogenated rosin were charged into a reaction apparatus equipped with a stirrer, a cooling tube, and a nitrogen inlet tube, and heated under a nitrogen stream until completely melted. Then, 190 parts of bisphenol A type polymeric epoxy resin (epoxy equivalent: 500) was added with stirring, and 0.1 part of 2-methylimidazole was added at 140°C. The mixture was allowed to react at 180°C for 3 hours to obtain rosin resin (B-1).

Example 1
A long fiber reinforced resin pellet manufacturing apparatus equipped with a coating die for the electric wire coating method installed at the tip of a TEX-30α type twin screw extruder (screw diameter 30 mm, L/D = 32) manufactured by Japan Steel Works, Ltd. was used, the extruder cylinder temperature was set to 350 ° C., the thermoplastic matrix resin (A-1) shown above was fed from the main hopper, and melt-kneaded at a screw rotation speed of 200 rpm. The rosin resin (B-1) heated and melted at 200 ° C. was adjusted to be discharged in an amount of 6 parts by weight per 100 parts by weight of (A) to (C) in total, and applied to a fiber bundle made of carbon fiber (C), and then supplied to a die opening (diameter 3 mm) from which the molten thermoplastic matrix resin (A-1) was discharged, and the carbon fiber (C) was continuously arranged so as to cover the periphery of the carbon fiber (C). At this time, the internal cross section of the fiber bundle was such that at least a part of the carbon fiber (C) was in contact with the thermoplastic matrix resin (A-1). The strand thus obtained was cooled and then cut with a cutter to a pellet length of 7 mm to obtain long fiber pellets. At this time, the take-up speed was adjusted so that the amount of carbon fiber (C) was 20 parts by weight per 100 parts by weight of the total of (A) to (C). The length of the carbon fiber (C) in the obtained long fiber pellets was substantially the same as the pellet length.

The long fiber pellets thus obtained were injection molded using an injection molding machine (J110AD manufactured by Japan Steel Works, Ltd.) under the following conditions: injection time: 2 seconds, back pressure: 5 MPa, holding pressure: 40 MPa, holding time: 10 seconds, cylinder temperature: 350°C, mold temperature: 150°C. ISO dumbbell test pieces, square plate test pieces for dispersibility evaluation measuring 80 mm x 80 mm x 3 mm thick, and rectangular test pieces measuring 80 mm x 10 mm x 4 mm thick were produced as molded products. Here, the cylinder temperature refers to the temperature of the part of the injection molding machine where the molding material is heated and melted, and the mold temperature refers to the temperature of the mold into which the resin is injected to form a predetermined shape. The obtained test pieces (molded products) were left to stand for 24 hours in a constant temperature and humidity chamber adjusted to a temperature of 23°C and 50% RH, and then subjected to characteristic evaluation. The evaluation results obtained by the above-mentioned methods are summarized in Table 1.

(Examples 2 and 3)
Molded articles were produced and evaluated in the same manner as in Example 1, except that the type of thermoplastic matrix resin used was changed as shown in Table 1, and the cylinder temperature was set to 370° C. and the mold temperature was set to 170° C. The evaluation results are summarized in Table 1.

Example 4
Molded articles were produced and evaluated in the same manner as in Example 1, except that the type of thermoplastic matrix resin used was changed as shown in Table 1. The evaluation results are shown in Table 1.
(Examples 5 to 9)
Molded articles were produced and evaluated in the same manner as in Example 1, except that the composition ratio was changed as shown in Table 1. The evaluation results are shown in Table 1.

(Comparative Example 1)
Molded articles were produced and evaluated in the same manner as in Example 1, except that the type of thermoplastic matrix resin used was changed as shown in Table 1, and the cylinder temperature was set to 280° C. and the mold temperature was set to 90° C. The evaluation results are summarized in Table 1.

(Comparative Examples 2 and 3)
Molded articles were produced and evaluated in the same manner as in Example 1, except that the composition ratio or the type of rosin resin used was changed as shown in Table 1. The evaluation results are shown in Table 4.
In Example 1, excellent fiber dispersion and gas scorch resistance resulted in excellent appearance quality and high heat resistance. Materials in Examples 2 to 4, which used different resin types, and Examples 5 to 9, which used different composition ratios, also showed excellent appearance quality and heat resistance.

In contrast, in Comparative Example 1, an amorphous resin with a low glass transition point was used, resulting in a molded product with poor heat resistance.

In Comparative Example 2, since no rosin resin was included, entanglement of fibers occurred, dispersibility was insufficient, and the appearance quality was inferior due to poorly dispersed areas.

In Comparative Example 3, the rosin resin had low thermal decomposition resistance, so the molded product had insufficient dispersibility and significant gas burns, resulting in poor appearance quality.

Fiber-reinforced thermoplastic resin molded products made using the fiber-reinforced thermoplastic resin composition and fiber-reinforced thermoplastic resin molding material of the present invention have excellent heat resistance and appearance quality, and are therefore suitable for use in aircraft parts, automobile parts, electrical and electronic parts, etc.

1. Thermoplastic matrix resin [A]
2 Rosin resin [B]
3 Reinforcing fiber [C]
4. Complex [D]

Claims (10)

A fiber-reinforced thermoplastic resin composition comprising (A) a thermoplastic matrix resin which is at least one selected from an amorphous resin having a glass transition point exceeding 190°C and a crystalline resin having a melting point exceeding 300°C, (B) a rosin resin having a weight loss rate of less than 5% at 350°C, and (C) reinforcing fibers which include at least carbon fibers. The fiber-reinforced thermoplastic resin composition according to claim 1, wherein the rosin resin (B) is a rosin polyol. The fiber-reinforced thermoplastic resin composition according to claim 1, wherein the thermoplastic matrix resin (A) is at least one selected from polyetherimide resin, polyaryletherketone resin, and polyethersulfone resin. The fiber-reinforced thermoplastic resin composition according to claim 1, wherein the reinforcing fibers (C) are carbon fibers only. The fiber-reinforced thermoplastic resin composition according to claim 1, wherein the weight ratio of the rosin resin (B) to the reinforcing fiber (C) is 15% or more or 50% or less. A fiber-reinforced thermoplastic resin molding material comprising a thermoplastic matrix resin (A) which is at least one selected from an amorphous resin having a glass transition point exceeding 190°C and a crystalline resin having a melting point exceeding 300°C, a rosin resin (B) having a weight loss rate of less than 5% at 350°C, and reinforcing fibers (C) which include at least carbon fibers, the fiber-reinforced thermoplastic resin molding material comprising the thermoplastic matrix resin (A) on the outside of a composite (D) formed by impregnating a reinforcing fiber bundle containing the reinforcing fiber (C) with the rosin resin (B), and the reinforcing fibers (C) arranged approximately parallel to the axial direction of the molding material. The fiber-reinforced thermoplastic resin molding material according to claim 6, wherein the length of the reinforcing fiber (C) and the length of the molding material are substantially the same. The fiber-reinforced thermoplastic resin molding material according to claim 6, wherein the thermoplastic matrix resin (A) has a core-sheath structure that covers the periphery of the composite (D). The fiber-reinforced thermoplastic resin molding material according to claim 6, having a length of 1 mm or more or 50 mm or less. A fiber-reinforced thermoplastic resin molded product using the fiber-reinforced thermoplastic resin composition according to claims 1 to 5.

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