JP2023112760A - Thermoplastic resin particle, method for producing thermoplastic resin fine particle and method for producing thermoplastic prepreg - Google Patents

Abstract

To provide thermoplastic resin particles that include voids inside the particles, so that they are easy to pulverize.SOLUTION: Thermoplastic resin particles have an average particle size of 0.5-10 mm, the particles having an internal voidage of 10-60%. A method for producing the thermoplastic resin fine particles includes a step of pulverizing the thermoplastic resin particles described herein, the resultant thermoplastic resin fine particles having an average particle size of 5-150 μm.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to thermoplastic resin particles used in thermoplastic prepregs comprising reinforcing fibers and thermoplastic resins.

Plastic-based composite materials composed of reinforcing fibers and matrix resins are lighter than metal-based composite materials and ceramic-based composite materials. As molded articles, it is used for electrical and electronic equipment members, precision machinery members, building materials, automobile members, household appliances, household goods, sporting goods, medical instruments, aircraft and space equipment members, and the like.

In recent years, fiber-reinforced thermoplastic resins using a thermoplastic resin as a matrix resin have attracted attention because of their moldability and ease of post-processing by welding.

One of the methods for impregnating reinforcing fibers with a thermoplastic resin is a powder impregnation method in which reinforcing fibers are passed through a slurry bath in which resin powder is dispersed. For example, Patent Document 1 describes a method of producing a prepreg using polyphenylene sulfide particles having a small particle size.

WO2019/203256

However, in the technique described in Patent Document 1, fine particles are required for impregnation, but it is difficult to pulverize thermoplastic resins that start from a pellet form such as thermoplastic resins with high toughness and some polymer alloy materials. Since the desired fine particles cannot be obtained, there is a concern that the impregnating properties may deteriorate when applied to powder impregnation.

Accordingly, an object of the present invention is to provide thermoplastic resin particles that are easily finely pulverized by having voids inside the particles.

In order to solve the above problems, the present invention mainly has the following configurations.
[1] Thermoplastic resin particles having an average particle diameter of 0.5 to 10 mm and an internal porosity of 10 to 60%.
[2] The thermoplastic resin constituting the thermoplastic resin particles is polyphenylene sulfide resin (PPS), polyarylene ether ketone resin (PAEK), polyether sulfone resin (PES), polyetherimide (PEI), liquid crystal polymer (LCP ), the thermoplastic resin particles according to [1], which is at least one thermoplastic resin selected from the group consisting of:
[3] A method for producing thermoplastic resin fine particles having an average particle size of 5 to 150 μm, comprising a step of pulverizing the thermoplastic resin particles according to [1] or [2].
[4] A method for producing thermoplastic resin fine particles, wherein foaming gas is injected into a thermoplastic resin in a molten state in a molding machine, and then the thermoplastic resin is discharged from the molding machine to increase the porosity inside the particles. A method for producing thermoplastic resin fine particles, comprising a step of obtaining thermoplastic resin particles having a content of 10 to 60%, and a step of pulverizing the obtained thermoplastic resin particles.
[5] A step of passing reinforcing fibers through a slurry in which thermoplastic resin fine particles obtained by the method for producing thermoplastic resin fine particles according to [3] or [4] are dispersed to obtain a reinforcing fiber base material; A method for producing a thermoplastic prepreg, comprising the step of heating and pressurizing the obtained reinforcing fiber base material.

According to the present invention, by forming voids in the thermoplastic particles, it is possible to obtain thermoplastic fine particles that are intended to easily pulverize even difficult-to-pulverize materials.

The present invention will be described in detail below together with embodiments.

Thermoplastic resins constituting the thermoplastic resin particles of the present invention include, for example, polyethylene terephthalate resin (PET), polybutylene terephthalate resin (PBT), polytrimethylene terephthalate resin (PTT), polyethylene naphthalate resin (PEN), liquid crystal Polyesters such as polyester resins, polyolefins such as polyethylene resins (PE), polypropylene resins (PP), polybutylene resins, styrene resins, polyoxymethylene resins (POM), polyamide resins (PA), polycarbonate resins ( PC), polymethylene methacrylate resin (PMMA), polyvinyl chloride resin (PVC), polyphenylene sulfide resin (PPS), polyphenylene ether resin (PPE), modified PPE resin, polyimide resin (PI), polyamideimide resin (PAI), Polyetherimide resin (PEI), polysulfone resin (PSU), modified PSU resin, polyethersulfone resin, polyketone resin (PK), polyarylene ether ketone resin (PAEK), polyarylate resin (PAR), polyethernitrile resin ( PEN), phenolic resin, phenoxy resin, fluorine-based resin such as polytetrafluoroethylene resin, polystyrene-based resin, polyolefin-based resin, polyurethane-based resin, polyester-based resin, polyamide-based resin, polybutadiene-based resin, polyisoprene-based resin , thermoplastic elastomers such as fluorine-based resins, copolymers thereof, modified products thereof, and resins obtained by blending two or more thereof. Among others, the group consisting of polyphenylene sulfide resins (PPS), polyarylene ether ketone resins (PAEK), polyether sulfone resins (PES), polyetherimides (PEI), liquid crystal polymers (LCP) from the viewpoint of mechanical properties and heat resistance At least one thermoplastic resin selected from is preferable, and a resin obtained by blending two or more of these thermoplastic resins is more preferable.

Examples of the polyarylene ether ketone resin (PAEK) include polyether ketone (PEK), polyether ether ketone (PEEK), polyether ether ketone ketone (PEEK), polyether ketone ketone (PEKK), polyether ketone ether Ketone ketone (PEKEKK), polyether ether ketone ether ketone (PEEKEK), polyether ether ether ketone (PEEEK), polyether diphenyl ether ketone (PEDEK), copolymers, modified products, and blends of two or more thereof It may be a resin or the like.

The thermoplastic resin according to the present invention may further contain fillers, other types of polymers, various additives, etc., if necessary.

As the filler, any one generally used as a filler for resins can be used, and the strength, rigidity, heat resistance, and dimensional stability of the fiber-reinforced thermoplastic resin base material and the molded product using the same can be further improved. be able to. Examples of fillers include glass fiber, carbon fiber, potassium titanate whisker, zinc oxide whisker, aluminum borate whisker, aramid fiber, alumina fiber, silicon carbide fiber, ceramic fiber, asbestos fiber, gypsum fiber, metal fiber, and the like. Fibrous inorganic filler, wollastonite, zeolite, sericite, kaolin, mica, talc, clay, pyrophyllite, bentonite, montmorillonite, asbestos, aluminosilicate, alumina, silicon oxide, magnesium oxide, zirconium oxide, titanium oxide, oxide Non-fibrous inorganic fillers such as iron, calcium carbonate, magnesium carbonate, dolomite, calcium sulfate, barium sulfate, magnesium hydroxide, calcium hydroxide, aluminum hydroxide, glass beads, ceramic beads, boron nitride, silicon carbide, silica, etc. are mentioned. You may contain 2 or more types of these. These fillers may be hollow. Moreover, it may be treated with a coupling agent such as an isocyanate compound, an organic silane compound, an organic titanate compound, an organic borane compound, an epoxy compound, or the like. As the montmorillonite, organic montmorillonite obtained by cation-exchanging interlayer ions with an organic ammonium salt may be used. If the fibrous filler is composed of discontinuous fibers, it can impart a function without impairing the reinforcing effect of the reinforcing fibers composed of continuous fibers.

Specific examples of impact modifiers include ethylene/methacrylic acid copolymers and salts of some or all of the carboxylic acid moieties in these copolymers with sodium, lithium, potassium, zinc or calcium, Ethylene/propylene-g-maleic anhydride copolymer, ethylene/butene-1-g-maleic anhydride copolymer, and the like.

Examples of various additives include antioxidants, heat stabilizers (hindered phenols, hydroquinones, phosphites and substituted products thereof, copper halides, iodine compounds, etc.), weathering agents (resorcinol, salicylate, etc.). , benzotriazole-based, benzophenone-based, hindered amine-based, etc.), release agents and lubricants (fatty alcohols, aliphatic amides, aliphatic bisamides, bi-urea and polyethylene waxes, etc.), pigments (cadmium sulfide, phthalocyanine, carbon black, etc.) , Dyes (nigrosine, aniline black, etc.), plasticizers (octyl p-oxybenzoate, N-butylbenzenesulfonamide, etc.), antistatic agents (alkyl sulfate type anionic antistatic agents, quaternary ammonium salt type cationic charging Antistatic agents, nonionic antistatic agents such as polyoxyethylene sorbitan monostearate, betaine amphoteric antistatic agents, etc.), flame retardants (melamine cyanurate, hydroxides such as magnesium hydroxide, aluminum hydroxide, polyphosphoric acid ammonium, brominated polystyrene, brominated polyphenylene oxide, brominated polycarbonate, brominated epoxy resin, or combinations of these brominated flame retardants with antimony trioxide, etc.). You may mix|blend 2 or more types of these.

The average particle size of the thermoplastic resin particles of the present invention is 0.1 to 10 mm, preferably 1 to 7 mm. If the average particle size is 10 mm or more, pulverization becomes difficult, and if the average particle size is 0.1 mm or less, it is difficult to produce. Furthermore, the particles may be in the form of powder or pellets as long as they are within the range of the average particle size.

The average particle size of the thermoplastic resin particles is obtained by selecting 100 or more thermoplastic resin particles, photographing them with an optical microscope, and measuring the short diameter and long diameter of the photographed thermoplastic resin particles. The average value is used as a representative value.

The thermoplastic resin particles according to the present invention have a porosity of 10 to 60% inside the particles. It is preferably 20-55%, more preferably 30-50%. When the porosity is within the above range, the morphology of the particles can be maintained, and both handleability and pulverizability can be achieved.

The porosity of the thermoplastic resin particles was obtained by taking a three-dimensional image using an X-ray observation device, evaluating the porosity by image processing, and using the formula (1).

Porosity = void volume in thermoplastic resin particles/volume of thermoplastic resin particles (1)
As for the voids formed inside the thermoplastic resin particles according to the present invention, it is preferable that a plurality of voids are dispersed inside the particles. Since the voids are dispersed, the thickness of the resin in the voids becomes thin during pulverization, which facilitates pulverization.

The void size of the thermoplastic resin particles according to the present invention is preferably 1 to 100 μm, more preferably 10 to 80 μm. When the size of the voids is within the above range, pulverizability can be improved.

The thermoplastic resin particles according to the present invention are produced by injecting foaming gas in a supercritical state into a thermoplastic resin in a molding machine such as an extruder or an injection molding machine. Obtained by opening.

As the foaming gas, it is preferable to use a gas inert to the thermoplastic resin. An inert gas means a gas that does not chemically react with the thermoplastic resin used. Specific examples include, but are not limited to, air, nitrogen, carbon dioxide, and rare gases such as helium, neon, and argon. Moreover, these gases may be used singly or in combination of two or more. Among these, at least one selected from the group consisting of carbon dioxide and nitrogen is preferable, and nitrogen having a high degree of inertness is more preferable. The supply amount of foaming gas is preferably 0.1 to 1.0 wt%, more preferably 0.3 to 0.6 wt%. If the amount of foaming gas supplied is less than 0.1 wt %, the formation of voids is insufficient, and if it is 0.6 wt % or more, it becomes difficult to discharge the resin.

The method for producing thermoplastic resin fine particles of the present invention includes a step of pulverizing the thermoplastic resin particles.

In the method for producing thermoplastic resin fine particles of the present invention, the method for pulverizing the thermoplastic resin particles includes dry pulverization, wet pulverization, and freeze pulverization using a jet mill, bead mill, hammer mill, ball mill, cutter mill, stone mill, or the like. can be used. Cryogenic grinding and jet milling are preferred due to their energy efficiency and grinding capacity.

The average particle size of the thermoplastic resin fine particles obtained by the method for producing thermoplastic resin fine particles of the present invention is 5 to 150 μm, preferably 10 to 120 μm, more preferably 15 to 100 μm. By setting the average particle size to 5 to 200 μm, the fiber-reinforced thermoplastic resin can be stably produced. The average particle size can be measured using a laser diffraction/scattering particle size distribution analyzer described below.

The fiber-reinforced thermoplastic resin substrate according to the present invention can be obtained by impregnating a reinforcing fiber substrate with thermoplastic resin fine particles.

In the present invention, a continuous fiber substrate composed of continuous reinforcing fibers refers to a fiber-reinforced thermoplastic resin substrate in which the reinforcing fibers are continuous. Examples of the form and arrangement of the continuous fiber substrate in the present invention include unidirectionally aligned continuous reinforcing fibers, woven fabric (cloth), knitted fabric, braided cord, tow, and the like. Among them, the one in which the reinforcing fibers are aligned in one direction is preferable because the mechanical properties in a specific direction can be efficiently improved.

The type of reinforcing fiber is not particularly limited, and examples thereof include carbon fiber, metal fiber, organic fiber, and inorganic fiber. You may use 2 or more types of these. By using carbon fibers as the reinforcing fibers, it is possible to obtain a fiber-reinforced thermoplastic resin base material that is lightweight and has high mechanical properties.

Examples of carbon fibers include PAN-based carbon fibers made from polyacrylonitrile (PAN) fibers, pitch-based carbon fibers made from petroleum tar or petroleum pitch, and cellulose-based carbon made from viscose rayon, cellulose acetate, or the like. fibers, vapor-grown carbon fibers made from hydrocarbons, and graphitized fibers thereof; Among these carbon fibers, PAN-based carbon fibers are preferably used because they have an excellent balance between strength and elastic modulus.

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

Examples of organic fibers include fibers made of organic materials such as aramid, polybenzoxazole (PBO), polyphenylene sulfide, polyester, polyamide, and polyethylene. Examples of aramid fibers include para-aramid fibers that are excellent in strength and elastic modulus, and meta-aramid fibers that are excellent in flame retardancy and long-term heat resistance. Examples of para-aramid fibers include polyparaphenylene terephthalamide fibers and copolyparaphenylene-3,4′-oxydiphenylene terephthalamide fibers, and meta-aramid fibers include polymetaphenylene isophthalamide fibers and the like. are mentioned. As the aramid fibers, para-aramid fibers having a higher elastic modulus than meta-aramid fibers are preferably used.

Examples of inorganic fibers include fibers made of inorganic materials such as glass, basalt, silicon carbide, and silicon nitride. Glass fibers include, for example, E glass fiber (for electrical use), C glass fiber (for corrosion resistance), S glass fiber, and T glass fiber (high strength and high modulus of elasticity). Basalt fiber is a fibrous material made from mineral basalt, and is a fiber with extremely high heat resistance. Basalt generally contains 9-25% by weight of iron compounds FeO or FeO ₂ and 1-6% by weight of titanium compounds TiO or TiO _{2 ;} It is also possible to make fibers by

Since the fiber-reinforced thermoplastic resin substrate according to the present invention is often expected to serve as a reinforcing material, it is desirable to exhibit high mechanical properties. It preferably contains carbon fibers.

In the fiber-reinforced thermoplastic resin base material, the continuous fiber base material is usually configured by arranging one or more reinforcing fiber bundles each made up of a large number of single fibers. When one or more reinforcing fiber bundles are arranged, the total number of filaments (number of single fibers) per reinforcing fiber bundle is preferably 1,000 to 2,000,000. From the viewpoint of productivity, the total number of filaments of the reinforcing fibers is more preferably 1,000 to 1,000,000, still more preferably 1,000 to 600,000, and 1,000 to 300,000. Especially preferred. The upper limit of the total number of filaments per reinforcing fiber bundle should be determined in consideration of the balance between dispersibility and handleability so that productivity, dispersibility, and handleability can be maintained satisfactorily.

One reinforcing fiber bundle is preferably configured by bundling 1,000 to 50,000 reinforcing fiber monofilaments having an average diameter of 5 to 10 μm.

As the impregnation method, the powder impregnation method is highly preferred, in which the thermoplastic resin fine particles are dispersed in the interstices of the fibers in the reinforcing fiber bundle, and then the thermoplastic resin fine particles are melted and pressurized to impregnate the reinforcing fiber bundle with the thermoplastic resin. It is preferable because a quality fiber-reinforced base material can be produced with good productivity.

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the description of these examples. Evaluation of physical properties in each example and comparative example was carried out according to the following methods.

[Volume content (Vf)]
After measuring the mass W0 of the fiber-reinforced thermoplastic resin substrate obtained in each example and comparative example, the fiber-reinforced thermoplastic resin substrate was heated in the air at 550° C. for 240 minutes to burn off the resin component. , the mass W1 of the remaining reinforcing fibers was measured, and the volume content (Vf) of the fiber-reinforced thermoplastic resin substrate was calculated by the following formula (2).
Vf (% by volume) = (W1/ρf)/{W1/ρf+(W0−W1)/ρ1}×100 (2)
ρf: Density of reinforcing fiber (g/cm ³ )
ρr: Density of resin composition (g/cm ³ ).

[Porosity of thermoplastic resin particles]
For the thermoplastic resin particles obtained in each example and comparative example, a three-dimensional image was taken using an X-ray microscope (Xradia 510 versa manufactured by Carl Zeiss), and voids were evaluated by image processing. obtained by

Porosity = void volume in thermoplastic resin particles/volume of thermoplastic resin particles (3)
[Average particle size of thermoplastic resin particles]
The average particle size of the thermoplastic resin particles obtained in each example and comparative example is obtained by selecting 100 or more thermoplastic resin particles, photographing them using an optical microscope, and photographing the short and long diameters of the thermoplastic resin particles. to measure. The average value was used as a representative value.

[Average particle size of thermoplastic resin fine particles]
The particle size of the thermoplastic resin particles obtained in each example and comparative example was measured using a laser diffraction/scattering particle size distribution analyzer (manufactured by Nikkiso Co., Ltd., Microtrac MT3300), and D50 (μm) was a representative value. and

[material]
In each example and comparative example, the following raw materials were used.
Thermoplastic resin:
Polyphenylene sulfide “Torelina (registered trademark)” manufactured by Toray Industries, Inc.
Polyetherimide "ULTEM (registered trademark)" manufactured by Savik Co., Ltd.

(Example 1)
Raw materials were mixed according to the composition shown in Table 1, and after the mixture was put into the feed port of the injection molding machine, 0.3% by mass of nitrogen gas was supplied. J110AD-180HD specification manufactured by Japan Steel Works, Ltd. was used as an injection molding machine, and T100-J specification manufactured by Trexel was used as a gas supply device. Melt-kneading was carried out at a predetermined kneading temperature and screw rotation speed, and a strand-like molten resin was discharged from the tip of the injection molding machine. The extruded strand-shaped molten resin was cooled and pulverized to obtain a sample of thermoplastic resin particles. The obtained thermoplastic resin particles were subjected to the above evaluation. Table 1 shows the evaluation results.

The obtained thermoplastic resin particles were pulverized by a freeze pulverizer to obtain thermoplastic resin fine particles. The obtained thermoplastic resin fine particles were subjected to the above evaluation.

(Example 2)
Fine thermoplastic resin particles were obtained in the same manner as in Example 1, except that the raw materials for the thermoplastic resin particles were changed to the formulations and weight ratios shown in Table 1. The obtained fiber-reinforced thermoplastic resin fine particles were subjected to the above evaluation. Table 1 shows the evaluation results.

(Comparative Examples 1 and 2)
A thermoplastic fine particle and a fiber-reinforced thermoplastic resin substrate were obtained in the same manner as in Example 1, except that the production conditions for the thermoplastic resin particles were as shown in Table 1. The obtained thermoplastic resin fine particles were subjected to the above evaluation.

The fiber-reinforced thermoplastic resin substrate according to the present invention can be molded into a desired shape by any molding method such as autoclave molding, press molding, and film molding. Molded articles obtained by molding using the fiber-reinforced thermoplastic resin base material according to the present invention include, for example, aircraft engine peripheral parts, aircraft interior parts, aircraft exterior parts, vehicle frameworks, automobile engine peripheral parts, automobile underhood parts, It is effective for automobile gear parts, automobile interior parts, automobile exterior parts, intake and exhaust system parts, engine cooling water system parts, automobile electrical parts, and electric/electronic parts such as LED reflectors and SMT connectors.

Specifically, the fiber-reinforced thermoplastic resin base material or molded article thereof in the present invention can be used for aircraft engine peripheral parts such as fan blades, landing gear pods, winglets, spoilers, edges, rudders, elevators, failings, ribs, and the like. Aircraft-related parts, various seats, front bodies, under bodies, various pillars, various members, various frames, various beams, various supports, various rails, automobile body parts such as various hinges, engine covers, air intake pipes, timing belt covers , intake manifolds, filler caps, throttle bodies, cooling fans and other automobile engine peripheral parts, cooling fans, radiator tank tops and bases, cylinder head covers, oil pans, brake pipes, fuel pipe tubes, exhaust system parts, etc. Automotive gear parts such as hood parts, gears, actuators, bearing retainers, bearing cages, chain guides, chain tensioners, shift lever brackets, steering lock brackets, key cylinders, door inner handles, door handle cowls, interior mirror brackets, air conditioner switches, Automotive interior parts such as instrument panels, console boxes, glove boxes, steering wheels, trims, front fenders, rear fenders, fuel lids, door panels, cylinder head covers, door mirror stays, tailgate panels, license garnishes, roof rails, engine mount brackets, rear Automotive exterior parts such as garnishes, rear spoilers, trunk lids, rocker moldings, moldings, lamp housings, front grilles, mudguards, side bumpers, air intake manifolds, intercooler inlets, turbochargers, exhaust pipe covers, inner bushes, bearing retainers, engines Intake and exhaust system parts such as mounts, engine head covers, resonators, and throttle bodies, engine cooling water system parts such as chain covers, thermostat housings, outlet pipes, radiator tanks, alternators, and delivery pipes, connectors and wire harness connectors, motor parts, Automobile electrical parts such as lamp sockets, sensor in-vehicle switches, combination switches, and electrical and electronic parts such as generators, motors, transformers, current transformers, voltage regulators, rectifiers, resistors, inverters, relays, power contacts, switches, circuit breakers, switches, knife switches, multi-pole rods, motor cases, TV housings, notebook computer housings and internal parts, CRT display housings and internal parts, printer housings and internal parts, mobile phones, mobile personal computers, Mobile terminal housings and internal parts such as handheld mobile devices, housings for ICs and LEDs, capacitor base plates, fuse holders, various gears, various cases, electric parts such as cabinets, connectors, connectors for SMT, card connectors, jacks, coils , coil bobbins, sensors, LED lamps, sockets, resistors, relays, relay cases, reflectors, small switches, power supply parts, coil bobbins, capacitors, variable condenser cases, optical pickup chassis, oscillators, various terminal boards, transformers, plugs, prints Substrates, tuners, speakers, microphones, headphones, small motors, magnetic head bases, power modules, Si power modules and SiC power modules, semiconductors, liquid crystals, FDD carriages, FDD chassis, motor brush holders, transformer parts, parabolic antennas, computer related It is preferably used for electronic parts such as parts.

Claims (5)

Thermoplastic resin particles having an average particle diameter of 0.5 to 10 mm and a porosity inside the particles of 10 to 60%. The thermoplastic resin constituting the thermoplastic resin particles consists of polyphenylene sulfide resin (PPS), polyarylene ether ketone resin (PAEK), polyethersulfone resin (PES), polyetherimide (PEI), and liquid crystal polymer (LCP). 2. The thermoplastic resin particles according to claim 1, which are at least one thermoplastic resin selected from the group. 3. A method for producing thermoplastic resin fine particles having an average particle size of 5 to 150 μm, comprising a step of pulverizing the thermoplastic resin particles according to claim 1 or 2. In a method for producing thermoplastic resin fine particles, a foaming gas is injected into a thermoplastic resin in a molten state in a molding machine, and then the thermoplastic resin is discharged from the molding machine, whereby the porosity inside the particles is 10 to 60. %, and a process for finely pulverizing the obtained thermoplastic resin particles. A step of passing reinforcing fibers through a slurry in which thermoplastic resin fine particles obtained by the method for producing thermoplastic resin fine particles according to claim 3 or 4 are dispersed to obtain a reinforcing fiber base material; A method for producing a thermoplastic prepreg, comprising the steps of heating and pressurizing a base material.