JP6946648B2 - How to make prepreg - Google Patents

Description

The present invention relates to a method for producing a prepreg, which is a method for producing a prepreg using a plurality of continuous reinforcing fibers impregnated with a thermoplastic resin.

Composite materials consisting of multiple continuous reinforcing fibers and resins are widely used in sports equipment applications, aerospace applications, vehicles, ships and other general industrial applications due to their light weight and excellent mechanical properties. In particular, a prepreg impregnated with reinforcing fibers using a thermoplastic resin for the resin is easier to melt by heating and solidify by cooling than a prepreg composed of a thermosetting resin and reinforcing fibers. It is expected to have effects such as handleability at times and shortening of cycle time, and is attracting attention from the viewpoint of reducing manpower and cost.

Further, in recent years, the uses of prepregs composed of thermoplastic resins and reinforcing fibers have been subdivided into various fields. When applied as a laminated material or a partial reinforcing material, a prepreg using a plurality of continuous reinforcing fibers oriented in one direction is in increasing demand as an intermediate base material due to its excellent mechanical properties.

Although the prepreg is excellent in tensile properties in the fiber direction, it is relatively inferior in bending properties and compressive properties. In order to improve these, there are methods such as using a high molecular weight thermoplastic resin, but when a high molecular weight thermoplastic resin is used, the fluidity of the molten resin in the manufacturing process decreases and the productivity increases. There is a problem that it drops. On the other hand, even if a high molecular weight thermoplastic resin having excellent mechanical properties is used, if the thermoplastic resin is in a molten state for a long time in the manufacturing process, there is a risk of thermal deterioration or oxidative deterioration of the thermoplastic resin. Will be higher.

Further, Patent Documents 1 and 2 describe a manufacturing method and an apparatus for uniformly arranging a plurality of continuous reinforcing fibers in a prepreg in order to impregnate a plurality of continuous reinforcing fibers with a thermoplastic resin.

Japanese Patent No. 5626660 Japanese Patent Publication No. 2014-518531

As described above, Patent Documents 1 and 2 describe a manufacturing method and an apparatus for uniformly arranging a plurality of continuous reinforcing fibers in a prepreg, but these documents describe thermoplasticity in the manufacturing process. The effect of the physical properties of the resin on the mechanical properties of the prepreg is not mentioned in detail.

Therefore, an object of the present invention is to provide a method for producing a prepreg, which can produce a prepreg composed of a thermoplastic resin having excellent mechanical properties and a plurality of continuously reinforced fibers with high productivity.

The above object of the present invention has been achieved by the following invention. That is, the present invention is as follows.

(1) In a method for producing a prepreg containing a thermoplastic resin and a plurality of continuous reinforcing fibers by passing a plurality of continuous reinforcing fibers through a tank containing the thermoplastic resin.
The space volume Vd [m ³ ] in the tank and the supply volume Qe [m ³ / s] of the thermoplastic resin to the tank per unit time satisfy the following formula (A) and also satisfy the following formula (A) .
^{The volume Qp [m 3} / s] of the prepreg passing through the outlet of the tank per unit time and the volume Qo [m ³ / s] of the thermoplastic resin discharged from the tank per unit time are given by the following equation (C). A method for producing a prepreg, which comprises satisfying.

10 ≤ Vd / Qe ≤ 9000 ... (A)
Qe-5.4 × Qp ≦ Qo ≦ Qe-0.2 × Qp ・ ・ ・ (C)

According to the present invention, a prepreg having excellent mechanical properties such as tensile strength and bending strength can be produced with high productivity.

Schematic cross-sectional view of an example of the manufacturing method of the present invention.

The present invention is a method for producing a prepreg containing a plurality of continuous reinforcing fibers and a thermoplastic resin. In the prepreg produced by the present invention, the continuous reinforcing fibers are preferably dispersed substantially uniformly in the prepreg without solidifying at a specific position, and each continuous reinforcing fiber is filled with a thermoplastic resin. .. That is, in the prepreg produced by the present invention, a plurality of continuous reinforcing fibers are impregnated with a thermoplastic resin.

The present invention, which is a method for producing a prepreg containing a plurality of continuous reinforcing fibers and a thermoplastic resin, has a step of passing the plurality of continuous reinforcing fibers through a tank containing the thermoplastic resin. Examples of the method having a step of passing a plurality of continuous reinforcing fibers through a tank containing a thermoplastic resin include a melting method, a powder method, and a mixed fiber (commingle) method. Among these, in the present invention, a melting method that does not require processing a thermoplastic resin in advance is preferably used.

Hereinafter, an example of the embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a method for manufacturing a prepreg according to an embodiment of the present invention, and 100 shows the entire prepreg manufacturing apparatus. In the present embodiment, the bobbin 102 around which the continuous reinforcing fiber 101 is wound is prepared, and the plurality of continuous reinforcing fibers 101 are continuously sent out from each of the plurality of bobbins 102 through the thread guide 103. The plurality of continuously reinforcing fibers 101 continuously sent out pass through the tank 104 containing the thermoplastic resin 107 quantitatively supplied from the feeder 105 filled with the thermoplastic resin. When the plurality of continuous reinforcing fibers 101 pass through the tank 104, the thermoplastic resin 107 can be impregnated into the plurality of continuous reinforcing fibers 101. The plurality of continuous reinforcing fibers 101 continuously pulled out from the tank 104 by the pulling force of the take-up roll 109 cool and solidify the thermoplastic resin 107 by passing through the cooling roll 108, and are taken up by the take-up roll 111. Be done. The prepreg 110 is manufactured by the above steps. All of the thermoplastic resin 107 that fills the tank 104 may pass through the tank 104 together with the plurality of continuous reinforcing fibers 101, and the thermoplastic resin 107 in the tank 104 together with the plurality of continuous reinforcing fibers 101. If it does not pass through, the excess thermoplastic resin 107 in the tank 104 can be discharged from the discharge port 106.

In the production method of the present invention, the ratio of the space volume Vd [m ³ ] in the tank to the supply volume Qe [m ³ / s] of the thermoplastic resin to the tank per unit time, Vd / Qe is 10 to 9000. It is more preferably 30 to 5500, still more preferably 70 to 1200. A large Vd / Qe means that the amount of thermoplastic resin supplied to the tank per unit time is small compared to the space volume of the tank. When this Vd / Qe exceeds 9000, the thermoplastic resin is small. The bending characteristics of the prepreg are deteriorated due to the thermal decomposition of the resin, and the reinforcing effect of other members is reduced. On the other hand, a small Vd / Qe means that a large amount of thermoplastic resin is supplied to the tank per unit time as compared with the space volume of the tank, and if this Vd / Qe is less than 10. , The amount of the thermoplastic resin supplied to the tank is large, and the yield of the thermoplastic resin deteriorates.

In the production method of the present invention, the space volume Vd [m ³ ] in the tank is preferably 0.6 × 10 ^{-7 to} 0.3, more preferably 0.8 × 10 -4-0.1, and even ^{more preferably 0.8 × 10 -4 to 0.1.} Is 0.1 × 10 ^{-3 to} 0.4 × 10 ^-1 . When Vd is 0.3 or less, a small amount of thermoplastic resin is required to fill the inside of the tank with the thermoplastic resin, and the yield of the thermoplastic resin is good. Further, when Vd is 0.6 × 10 ^-7 or more, the impregnation property when impregnating the plurality of continuous reinforcing fibers with the thermoplastic resin can be improved, so that the thermoplastic resin for the plurality of continuous reinforcing fibers can be improved. Is well impregnated.

In the production method of the present invention, the volume Qp [m ³ / s] of ^{the prepreg passing through the outlet of the tank per unit time is preferably 0.8 × 10 -9 to} 0.7 × 10 -3, more preferably ^{0.8 × 10 -9 to 0.7 × 10 -3.} It is 0.1 × 10 ^{-7 to} 0.3 × 10 ^-3 , more preferably 0.6 × 10 ^{-7 to} 0.9 × 10 ^-4 . When Qp is 0.7 × 10 ^-3 or less, the impregnation property of the thermoplastic resin into the plurality of continuous reinforcing fibers is improved. Further, when Qp is 0.8 × 10 ^-9 or more, high productivity can be obtained.

^{The volume Qp [m 3} / s] of the prepreg passing through the outlet of the tank per unit time is the speed [m / s] of the prepreg passing through the outlet of the tank and the dimensions of the outlet (area [m ² ]). Can be obtained from.

In the production method of the present invention, assuming that the volume of the prepreg passing through the outlet of the tank per unit time is Qp [m ³ / s], the supply volume of the thermoplastic resin to the tank per unit time is Qe [m ³ / s]. ] Is preferably 0.2 × Qp to 5.4 × Qp, more preferably 0.3 × Qp to 4.7 × Qp, and further preferably 0.4 × Qp to 4.1 × Qp. be. When Qe is 5.4 × Qp or less, the yield of the thermoplastic resin is improved. When Qe is 0.2 × Qp or more, the impregnation property of the thermoplastic resin into the plurality of continuous reinforcing fibers is good, and the amount of the thermoplastic resin in the tank is always larger than the required amount of the thermoplastic resin constituting the prepreg. Many, stable production is possible.

In the production method of the present invention, it is preferable that a part of the thermoplastic resin is discharged from the tank when a plurality of continuous reinforcing fibers are passed through the tank. By doing so, the thermoplastic resin that has been thermally decomposed in the tank can be discharged, and the thermoplastic resin that is less affected by the thermal decomposition can be contained in the tank. The discharge point when a part of the thermoplastic resin is discharged from the tank is not particularly limited, and a discharge point may be provided on the bottom surface of the tank or a discharge point may be provided on the side surface of the tank. Further, the number of discharge points is not limited, and it does not matter whether a plurality of discharge points are installed in the tank or only one discharge point is installed.

Further, when a part of the thermoplastic resin is discharged from the tank, in the production method of the present invention, the volume of the thermoplastic resin supplied to the tank per unit time is set to Qe [m ³ / s] per unit time. Assuming that the volume of the prepreg passing through the outlet of the tank is Qp [m ³ / s], the volume Qo [m ³ / s] of the thermoplastic resin discharged from the tank per unit time is Qe-5.4 × Qp ~. It is preferably Qe-0.2 × Qp, more preferably Qe-4.7 × Qp to Qe-0.2 × Qp, and even more preferably Qe-4.1 × Qp to Qe-0.4 × Qp. Is. Here, the discharge volume Qo [m ³ / s] of the thermoplastic resin from the tank per unit time means the volume discharged from the discharge point installed in the tank as described above. When a plurality of discharge points are installed in the tank, the total volume of the thermoplastic resin discharged from the plurality of discharge points is calculated as the discharge volume of the thermoplastic resin from the tank per unit time Qo [m ^3]. / S].

In the present invention, when Qo is Qe−0.2 × Qp or less, the yield of the thermoplastic resin is improved. When Qo is Qe-5.4 × Qp or more, the amount of thermoplastic resin in the tank is always larger than the required amount of the thermoplastic resin constituting the prepreg, enabling stable production and a plurality of continuous reinforcing fibers. The impregnation of the thermoplastic resin is also improved. In order to control Qo to Qe-0.2 × Qp or less, there are means such as reducing the outlet dimension of the discharge port.

The fiber volume content in 100% by volume of the prepreg containing the plurality of continuous reinforcing fibers and the thermoplastic resin obtained by the production method of the present invention is preferably 30 to 70% by volume, more preferably 35 to 65% by volume, still more preferably. Is 40 to 60% by volume. When the fiber volume content is 30% by volume or more, the mechanical properties of the prepreg are excellent and the reinforcement to other members is excellent. When the fiber volume content is 70% by volume or less, the impregnation property of the thermoplastic resin into the plurality of continuous reinforcing fibers is excellent.

The porosity in 100% by volume of the prepreg containing the plurality of continuous reinforcing fibers and the thermoplastic resin obtained by the production method of the present invention is preferably 5% by volume or less, more preferably 4% by volume or less, still more preferably 3% by volume. It is as follows. When the porosity is 5% by volume or less, the mechanical properties of the prepreg are excellent, and the reinforcement to other members is excellent. As a means for controlling the void ratio to 5% by volume or less, the melt viscosity of the thermoplastic resin to be impregnated is lowered, the pressure applied at the time of impregnation is increased, and the plurality of continuous reinforcing fibers are sufficiently impregnated with the thermoplastic resin. There are means such as continuously supplying the tank with an amount of thermoplastic resin corresponding to a desired fiber volume content, which is necessary for the above.

The bending strength of the prepreg obtained by the production method of the present invention measured by JIS K 7074 (1988) is preferably 750 MPa or more, more preferably 900 MPa or more, still more preferably 1,000 MPa or more. When the bending strength is 750 MPa or more, it is excellent in reinforcing other members. The larger the bending strength of the prepreg, the more preferable it is, but the practical upper limit is considered to be about 2,000 MPa.

As a means for controlling the bending strength to 750 MPa or more, there are means such as suppressing thermal decomposition of the thermoplastic resin and adjusting the porosity to a low value.

In the production method of the present invention, when passing a plurality of continuous reinforcing fibers through the tank, it is preferable that the continuous reinforcing fibers are arranged and passed in one direction along the passing direction. By doing so, the continuous reinforcing fibers in the obtained prepreg can be made to be oriented in one direction. That is, in the prepreg containing the plurality of continuous reinforcing fibers and the thermoplastic resin obtained by the production method of the present invention, the orientation direction of the plurality of continuous reinforcing fibers is not particularly limited, but the workability in producing the prepreg is excellent. Therefore, it is preferable that the fibers are oriented in one direction.

The continuous reinforcing fibers used in the production method of the present invention are not particularly limited, and examples thereof include carbon fibers, metal fibers, organic fibers, and inorganic fibers.

Examples of carbon fibers include polyacrylonitrile (PAN) -based carbon fibers, pitch-based carbon fibers, cellulose-based carbon fibers, vapor-phase growth-based carbon fibers, and graphitized fibers thereof. Of these, the PAN-based carbon fiber is a carbon fiber made from polyacrylonitrile fiber. Pitch-based carbon fibers are carbon fibers made from petroleum tar or petroleum pitch. Cellulose-based carbon fibers are carbon fibers made from viscose rayon, cellulose acetate, or the like. The vapor phase growth type carbon fiber is a carbon fiber made from a hydrocarbon or the like. Among these carbon fibers, PAN-based carbon fibers are preferably used because they have an excellent balance between strength and elastic modulus.

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

Examples of the organic fiber include fibers made of an organic material such as aramid fiber, polyphenylene sulfide fiber, polyester fiber, polyamide fiber, and polyethylene fiber. Examples of the aramid fiber include a para-type aramid fiber having excellent strength and elastic modulus and a meta-type aramid fiber having excellent flame retardancy and long-term heat resistance. Examples of the para-aramid fiber include polyparaphenylene terephthalamide fiber and copolyparaphenylene-3,4'-oxydiphenylene terephthalamide fiber, and examples of the meta-aramid fiber include polymetaphenylene isophthalamide fiber. Can be mentioned. As the aramid fiber, a para-aramid fiber having a higher elastic modulus than the meta-aramid fiber is preferably used.

Examples of the inorganic fiber include fibers made of an inorganic material such as glass, basalt, silicon carbide, and silicon nitride. Examples of the glass fiber include E glass fiber (for electricity), C glass fiber (for corrosion resistance), S glass fiber, and T glass fiber (high strength and high elasticity), and any of these may be used. Basalt fiber is a fiber of basalt, which is a mineral, and has extremely high heat resistance. _{Basalt generally contains 9 to 25% of FeO or FeO 2} which is an iron compound _{and 1 to 6% of TiO or TiO 2} which is a titanium compound, but these components are increased in a molten state to become fibrous. It is also possible to do.

In the production method of the present invention, it is more preferable to use at least one continuous reinforcing fiber selected from the group consisting of carbon fiber, glass fiber, basalt fiber, and aramid fiber as the continuous reinforcing fiber, and among these, lightweight. It is particularly preferable to use carbon fibers that efficiently exhibit mechanical properties such as chemical conversion and strength.

As the plurality of continuous reinforcing fibers, a plurality of types thereof may be used in combination, and a composite effect can be expected by combining different continuous reinforcing fibers. For example, by combining carbon fiber and glass fiber as continuous reinforcing fibers, it is possible to achieve both a high reinforcing effect by carbon fibers and a cost reduction by inexpensive glass fibers.

In a prepreg containing a plurality of continuous reinforcing fibers and a thermoplastic resin obtained by the production method of the present invention, the plurality of continuous reinforcing fibers are usually composed of one or a plurality of reinforcing fiber bundles in which a large number of single fibers are bundled. Will be done. The total number of filaments (number of single fibers) of the plurality of continuous reinforcing fibers when one or a plurality of reinforcing fiber bundles are arranged includes the plurality of continuous reinforcing fibers and the thermoplastic resin obtained by the production method of the present invention. It is preferably in the range of 1,000 to 2,000,000 during the prepreg. From the viewpoint of productivity, the total number of filaments of the plurality of continuous reinforcing fibers obtained by the production method of the present invention and the plurality of continuous reinforcing fibers in the prepreg containing the thermoplastic resin is 1,000 to 1,000,000. Is more preferable, 1,000 to 600,000 is even more preferable, and 1,000 to 300,000 is particularly preferable. The upper limit of the total number of filaments of the plurality of continuous reinforcing fibers is selected so as to maintain good productivity, dispersibility, and handleability in consideration of the balance between dispersibility and handleability.

In the prepreg containing the plurality of continuous reinforcing fibers and the thermoplastic resin obtained by the production method of the present invention, the average diameter of the single fibers in the plurality of continuous reinforcing fibers is preferably 5 to 10 μm, and the average diameter of the single fibers is 6. ~ 8 μm is more preferable.

Further, it is preferable to use a plurality of continuous reinforcing fibers having a tensile strength of 3,000 to 6,000 MPa. The relationship is that the strength (MPa) of the plurality of continuous reinforcing fibers = (single fiber strength (N)) / single fiber cross-sectional area (mm ^2).

Further, the reinforcing fiber bundle constituting the plurality of continuous reinforcing fibers may be surface-treated with a sizing agent in order to improve adhesiveness, composite mechanical properties, and higher-order processability. The sizing agent contains components such as bisphenol type epoxy compound, linear low molecular weight epoxy compound, polyethylene glycol, polyurethane, polyester, emulsifier or surfactant to adjust the viscosity, improve scratch resistance, improve fluff resistance, and improve focusing. , Preferably mixed for the purpose of improving higher workability.

The means for applying the sizing agent is not particularly limited, but for example, there are a method of immersing in the sizing liquid via a roller, a method of contacting the roller to which the sizing liquid is attached, a method of atomizing the sizing liquid and spraying the sizing liquid. .. Further, either a batch type or a continuous type may be used, but a continuous type having good productivity and small variation is preferable. At this time, it is preferable to control the sizing liquid concentration, temperature, thread tension, etc. so that the amount of the sizing agent active ingredient adhered to the reinforcing fibers is uniformly within an appropriate range. Further, it is more preferable to ultrasonically vibrate the reinforcing fibers when the sizing agent is applied.

The thermoplastic resin used in the production method of the present invention is not particularly limited as long as it is a thermoplastic resin, for example, polypropylene, polyethylene, polystyrene, polyvinyl chloride, polyvinyl acetate, ABS resin, ABS resin, polyethylene terephthalate, and the like. Polybutylene terephthalate, polyamide, polyamideimide, polyacetal, polycarbonate, modified polyphenylene oxide, polyvinyl alcohol, polyalkylene oxide, polysulfone, polyphenylene sulfide, polyarylate, polyetherimide, polyetheretherketone, polyethersulfone, polyimide, liquid crystal polymer, Examples thereof include polymethylmethacrylate and polysulfone.

In particular, since a prepreg having excellent heat resistance, strength, rigidity and other physical properties can be obtained, it is preferable to use a polyamide resin as the thermoplastic resin used in the production method of the present invention.

Here, the polyamide resin is a polyamide containing amino acids, lactam or diamine and a dicarboxylic acid as main constituents. Typical examples of its main constituents are amino acids such as 6-aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid and paraaminomethylbenzoic acid, lactam such as ε-caprolactam and ω-laurolactam, and tetramethylenediamine. , Hexamethylenediamine, 2-methylpentamethylenediamine, nonamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2,4- / 2,4,4-trimethylhexamethylenediamine, 5-methylnonamethylenediamine, Metaxylylenediamine, paraxamethylenediamine, 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, Fat groupes such as bis (4-aminocyclohexyl) methane, bis (3-methyl-4-aminocyclohexyl) methane, 2,2-bis (4-aminocyclohexyl) propane, bis (aminopropyl) piperazine, aminoethyl piperazine, Alicyclic, aromatic diamine, and adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, terephthalic acid, isophthalic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, Examples thereof include aliphatic, alicyclic, and aromatic dicarboxylic acids such as 5-sodium sulfoisophthalic acid, 2,6-naphthalenedicarboxylic acid, hexahydroterephthalic acid, and hexahydroisophthalic acid. In the present invention, these raw materials are used. Nylon homopolymers or copolymers derived from can be used alone or in the form of a mixture, respectively.

Specific examples of the polyamide resin particularly useful as the thermoplastic resin used in the production method of the present invention include polycaproamide (nylon 6), polyhexamethylene adipamide (nylon 66), and polytetramethylene adipamide. (Nylon 46), Polyhexamethylene sebacamide (Nylon 610), Polyhexamethylene dodecamide (Nylon 612), Polyundecaneamide (Nylon 11), Polydodecaneamide (Nylon 12), Polycaproamide / Polyhexamethyleneazi Pamide copolymer (nylon 6/66), polycaproamide / polyhexamethylene terephthalamide copolymer (nylon 6 / 6T), polyhexamethylene adipamide / polyhexamethylene terephthalamide copolymer (nylon 66 / 6T), polyhexamethylene Adipamide / polyhexamethylene isophthalamide / polycaproamide copolymer (nylon 66 / 6I / 6), polyhexamethylene adipamide / polyhexamethylene isophthalamide copolymer (nylon 66 / 6I), polyhexamethylene terephthalamide / poly Hexamethylene isophthalamide copolymer (nylon 6T / 6I), polyhexamethylene terephthalamide / polydodecaneamide copolymer (nylon 6T / 12), polyhexamethylene adipamide / polyhexamethylene terephthalamide / polyhexamethylene isophthalamide copolymer (nylon) 66 / 6T / 6I), Polyxylylene adipamide (Nylon XD6), Polyhexamethylene terephthalamide / Poly-2-methylpentamethylene terephthalamide copolymer (Nylon 6T / M5T), Polynonamethylene terephthalamide (Nylon 9T) , And a mixture thereof, a copolymer, and the like. Among them, polyamide 6 having excellent impregnation property and handleability in reinforcing fibers is preferable.

In the production method of the present invention, flame retardants, weather resistance improvers, other antioxidants, heat stabilizers, ultraviolet absorbers, plasticizers, lubricants, colorants, compatibility agents, depending on the required characteristics of the prepreg. , Conductive filler and the like can be added.

Next, the present invention will be specifically described based on Examples and Comparative Examples, but the present invention is not limited to these Examples.

(1) Method for measuring bending strength measured by JIS K 7074 (1988)
The bending strength of the prepreg containing a plurality of continuous reinforcing fibers and a thermoplastic resin was measured according to the method A of JIS K 7074 (1988).

Judgment was made according to the following criteria according to the obtained measured values of bending strength. In addition, AA to B were accepted.
AA: Bending strength 1,000 MPa or more A: Bending strength 900 MPa or more and less than 1,000 MPa B: Bending strength 750 MPa or more and less than 900 MPa C: Less than 750 MPa (2) ^{Measurement method of specific gravity (g / cm 3} ) Specific gravity measuring machine (manufactured by ALFA MIRAGE) , ELECTRONIC DENSIMTER SD-200L) was used to measure the specific densities of reinforcing fibers, thermoplastic resin compositions, prepregs and the like.

(3) Method for measuring fiber volume content and void ratio After weighing the mass W1 of a prepreg containing about 0.5 g of continuously reinforced fibers and a thermoplastic resin, the prepreg is placed in an electric furnace set at a temperature of 500 ° C. in a nitrogen stream. After leaving it for 120 minutes, the thermoplastic resin composition in the prepreg was completely thermally decomposed. Then, the fiber was transferred to a container in a dry nitrogen stream and cooled for 15 minutes, and then the mass W2 of the reinforcing fiber was weighed to determine the amount of the reinforcing fiber. Each value was calculated from each of these measured values by the following formula.

Fiber volume content (%) = (W2 (g) / specific gravity of reinforcing fiber (g / cm ³ )) / (W1 (g) / specific density of prepreg (g / cm ³ )) × 100
Resin volume content (%) = ((W1-W2) (g) / specific gravity of thermoplastic resin composition (g / cm ³ )) / (W1 (g) / specific density of prepreg (g / cm ³ )) × 100
Porosity (%) = 100-Fiber volume content (%) -Resin volume content (%)
(4) Parameters in the Production Method of the Present Invention (A) Carbon fiber (T700SC-12K manufactured by Toray Industries, Inc.) was used as the continuous reinforcing fiber.

As the thermoplastic resin (B), polyamide 6 (“Amilan” (registered trademark) CM1007 manufactured by Toray Industries, Inc.) was used.

(C) Vd / Qe [s]
(C-1) 30
(C-2) 1100
(C-3) 4800
(C-4) 8700
(C-5) 4
(C-6) 10500
(D) Qe [m ³ / s]
(D-1) 0.6 × Qp
(D-2) 3.8 × Qp
(E) Qo [m ³ / s]
(E-1) Qe-0.5 × Qp
(E-2) Qe-0.2 × Qp
(E-3) Qe-0.8 × Qp
(Example 1)
Carbon fiber is used as a plurality of continuous reinforcing fibers, polyamide 6 resin is used as the thermoplastic resin composition, Vd / Qe is (c-1), and the volume Qe of the thermoplastic resin supplied to the tank per unit time is (). d-1), the prepreg was manufactured by the manufacturing method shown in FIG. 1 with the discharge volume Qo of the thermoplastic resin from the tank per unit time as (e-1).

In FIG. 1, a bobbin 102 on which a plurality of continuous reinforcing fibers 101 are wound was prepared, and a plurality of continuous reinforcing fibers 101 were continuously sent out from each bobbin 102 through a thread guide 103. The plurality of continuously reinforcing fibers 101 continuously sent out were impregnated with the thermoplastic resin 107 quantitatively supplied from the feeder 105 filled with the thermoplastic resin in the tank 104. A plurality of continuous reinforcing fibers 101 impregnated with the thermoplastic resin 107 in the tank 104 were continuously pulled out from the nozzles of the tank 104. A plurality of continuous reinforcing fibers 101 pulled out by the take-up roll 108 were passed through the cooling roll 107 to be cooled and solidified, and wound up by the take-up roll 110 to obtain a prepreg 110 having a fiber volume content of 50% by volume.

(Example 2)
A prepreg 110 was obtained in the same manner as in Example 1 except that Vd / Qe was set to (c-2).

(Example 3)
A prepreg 110 was obtained in the same manner as in Example 1 except that Vd / Qe was set to (c-3).

(Example 4)
A prepreg 110 was obtained in the same manner as in Example 1 except that Vd / Qe was set to (c-4).

(Example 5)
A prepreg 110 was obtained in the same manner as in Example 1 except that the volume Qe of the thermoplastic resin supplied to the tank per unit time was set to (d-2).
(Example 6)
A prepreg 110 was obtained in the same manner as in Example 1 except that the discharge volume Qo of the thermoplastic resin from the tank per unit time was set to (e-2).
(Example 7)
A prepreg 110 was obtained in the same manner as in Example 1 except that the discharge volume Qo of the thermoplastic resin from the tank per unit time was set to (e-3).

(Comparative Example 1)
A prepreg 110 was obtained in the same manner as in Example 1 except that Vd / Qe was set to (c-5).

(Comparative Example 2)
A prepreg 110 was obtained in the same manner as in Example 1 except that Vd / Qe was set to (c-6).

100 Manufacturing equipment 101 Reinforcing fiber bundle 102 Bobbin 103 Thread guide
104 Tank 105 Feeder 106 Discharge port 107 Thermoplastic resin 108 Cooling roll 109 Pick-up roll 110 Prepreg 111 Wind-up roll

Claims (5)

In a method for producing a prepreg containing a thermoplastic resin and a plurality of continuous reinforcing fibers by passing a plurality of continuous reinforcing fibers through a tank containing the thermoplastic resin.
The space volume Vd [m ³ ] in the tank and the supply volume Qe [m ³ / s] of the thermoplastic resin to the tank per unit time satisfy the following formula (A) and also satisfy the following formula (A) .
^{The volume Qp [m 3} / s] of the prepreg passing through the outlet of the tank per unit time and the volume Qo [m ³ / s] of the thermoplastic resin discharged from the tank per unit time are given by the following equation (C). A method for producing a prepreg, which comprises satisfying.
10 ≤ Vd / Qe ≤ 9000 ... (A)
Qe-5.4 × Qp ≦ Qo ≦ Qe-0.2 × Qp ・ ・ ・ (C) The volume Qe [m ³ / s] of the thermoplastic resin supplied to the tank per unit time and the volume Qp [m ³ / s] of the prepreg passing through the outlet of the tank per unit time are given by the following equation (B). The method for producing a prepreg according to claim 1, wherein the prepreg is produced.
0.2 × Qp ≦ Qe ≦ 5.4 × Qp ・ ・ ・ (B) The method for producing a prepreg according to claim 1 or 2, wherein a part of the thermoplastic resin is discharged from the tank when a plurality of continuous reinforcing fibers are passed through the tank. The production of the prepreg according to any one of claims 1 to 3 , wherein when a plurality of continuous reinforcing fibers are passed through the tank, the continuous reinforcing fibers are arranged and passed in one direction along the passing direction. Method. The method for producing a prepreg according to any one of claims 1 to 4 , wherein the continuous reinforcing fiber contains carbon fiber.

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