JP7066973B2 - Fiber reinforced plastic - Google Patents

Description

The present invention relates to fiber reinforced plastics.

Fiber reinforced plastics are widely used in various fields such as aircraft parts, automobile parts, wind turbine parts for wind power generation, and sports equipment. As a method of forming the fiber reinforced plastic, the fiber reinforced plastic is preheated to a temperature exceeding the melting point (or glass transition point) of the matrix resin by an IR heater or the like, and then pressure-cooled by a press molding machine equipped with a mold or the like. As a result, a compression molding method (stamping molding) that shapes the shape into a desired shape and solidifies it is generally performed.
The fiber-reinforced plastic is formed, for example, by laminating and integrating a plurality of prepreg base materials in which reinforcing fibers are impregnated with a thermoplastic resin.

Examples of the prepreg base material include those in which continuous reinforcing fibers having a long fiber length are arranged in one direction and impregnated with a thermoplastic resin into a sheet. A fiber-reinforced plastic formed of a prepreg base material using such continuous long reinforcing fibers can produce a structural material having excellent mechanical properties. However, since the fiber-reinforced plastic is a continuous reinforced fiber, its fluidity at the time of shaping is low, and it is difficult to shape it into a complicated shape such as a three-dimensional shape by stamping molding. Therefore, when the fiber reinforced plastic is used, the structural material to be manufactured is mainly limited to a material having a nearly planar shape.

As a method of increasing the fluidity at the time of shaping, for example, a reinforcing fiber aligned in one direction is impregnated with a thermoplastic resin, and a plurality of prepreg base materials having a notch intersecting the fiber axis are laminated. A method (I) of integrating them into a fiber-reinforced plastic has been proposed (Patent Document 1). Since the fiber-reinforced plastic obtained by the method (I) has a notch formed in the prepreg base material and the reinforcing fiber is divided, good fluidity can be obtained at the time of shaping. Further, by laminating a plurality of prepreg base materials so that the fiber axis direction of the reinforcing fiber is not biased to a specific direction, for example, the fiber axis direction is deviated by 45 ° in a plan view, the isotropic property of the mechanical properties is achieved. It is possible to obtain a fiber-reinforced plastic with good quality and little variation. In addition, anisotropy can be controlled by aligning the fiber axis directions in any direction and laminating.
However, the method (I) is not yet sufficient in terms of manufacturing convenience and cost. Especially in the industrial production of fiber reinforced plastics and structural materials (molded products), it is important to be able to manufacture them more easily and at low cost. Further, in order to obtain a structural material having a more complicated shape, it is important to increase the fluidity of the fiber-reinforced plastic during shaping.
When structural materials are manufactured by shaping fiber-reinforced plastics into complex shapes such as three-dimensional shapes, relatively short reinforced fibers with a fiber length of 100 mm or less are generally used to ensure fluidity during shaping. Is used. However, when the fiber length of the reinforcing fiber is shortened, the mechanical properties of the structural material after shaping tend to deteriorate.

Further, as a method of increasing the fluidity at the time of shaping, there is a method of randomly arranging discontinuous reinforcing fibers. For example, a method of dispersing a plurality of prepreg pieces cut out from a narrow tape-shaped prepreg base material at a certain length on a flat surface and integrating them by press molding to form a sheet-shaped fiber reinforced plastic (II). ) Is disclosed (Patent Document 2).
However, in the method (II), the prepreg pieces are dispersed by flying the prepreg pieces with air or by diffusing the prepreg pieces in a liquid fluid and then depositing the prepreg pieces, so that the fiber axial direction of the reinforcing fibers is completely aligned. It is extremely difficult to evenly disperse the prepreg pieces so that they point in random directions. Therefore, even within the same sheet, the fiber reinforced plastic has different mechanical properties such as strength depending on the location and orientation. It is often required that the structural material has little variation in mechanical properties such as strength, and that the mechanical properties are isotropic or the anisotropy thereof is controlled. However, in the method (II), it is difficult to obtain a fiber reinforced plastic having good isotropic mechanical properties or controlled anisotropy and less variation in mechanical properties.
In addition, fiber reinforced plastics are also required to have good heat resistance. Generally, the heat resistance of fiber reinforced plastic is greatly affected by the heat resistance of Trix resin in fiber reinforced plastic. Normally, the mechanical properties of a single resin tend to decrease at a temperature equal to or higher than the glass transition temperature of the resin. Similarly, in fiber reinforced plastics, the mechanical properties tend to decrease at a temperature equal to or higher than the glass transition temperature of the matrix resin. In order to minimize this deterioration of mechanical properties, it is necessary to uniformly disperse the reinforced fibers in the matrix resin in the fiber reinforced plastic. However, in the above method, in the step of heating and integrating the deposited prepreg pieces, only the molten matrix resin flows into the gaps between the deposited prepreg pieces. Therefore, in the obtained fiber reinforced plastic, a resin-rich portion is locally generated. Due to the influence of this resin-rich portion, the fiber-reinforced plastic obtained by the above method (II) has a problem of inferior heat resistance.

Further, the fiber reinforced plastic obtained by the method (I) has a problem that when stress is generated in the direction along the cut shape, the cut portion becomes a starting point of fracture and the mechanical properties are deteriorated. Further, since only the resin is substantially present in this cut portion, the heat resistance is inferior at a temperature equal to or higher than the glass transition temperature of the matrix resin, as in the method (II) disclosed in Patent Document 2. There's a problem.

Patent Document 3 discloses a method (III) for producing a fiber-reinforced plastic by dispersing reinforcing fibers by papermaking. In the fiber-reinforced plastic obtained by the method (III), since the reinforced fibers are dispersed almost uniformly, the mechanical properties are excellent in isotropic properties, there is little variation, and the heat resistance is also good.
However, in the fiber reinforced plastic obtained by the above method (III), the reinforced fibers are three-dimensionally entangled, so that the fluidity at the time of shaping is inferior. In addition, the manufacturing process is extremely complicated, and the cost is inferior. In addition, when an attempt is made to produce a fiber-reinforced plastic having a high content of reinforcing fibers by the above method (III), it is necessary to make paper in a state where the reinforcing fibers are denser. However, when the matrix resin is impregnated into such high-density paper-made reinforcing fibers, among the three-dimensionally entwined reinforcing fibers, the reinforcing fibers oriented in the thickness direction (impregnation direction) are particularly impregnated at the time of impregnation. Since it bears the stress of the pressing force, the pressure is not transmitted to the resin, which makes impregnation extremely difficult. Further, even when the fiber length of the reinforcing fiber is long, the three-dimensional entanglement becomes strong, so that impregnation is similarly difficult.

The following are proposed as fiber reinforced plastics that can obtain structural materials with high mechanical properties while using discontinuous reinforcing fibers.
(1) It is composed of a reinforced fiber having a fiber length of 5 to 100 mm and a thermoplastic resin, and the average value of tan δ'in the range of the melting point ± 25 ° C. of the thermoplastic resin is 0.01 ≤ tan δ'(average value) ≤ 0. Fiber reinforced plastic satisfying .2 (Patent Document 4). tan δ'is defined by the following two equations.
tanδ = G'' / G'
tanδ'= Vf x tanδ / (100-Vf)
(However, Vf is the volume fraction (%) of the reinforcing fiber in the fiber reinforced plastic, G'is the storage elastic modulus (Pa) of the fiber reinforced plastic, and G'' is the loss elastic modulus of the fiber reinforced plastic (however, Pa).)
The fiber-reinforced plastic of (1) has good mechanical properties because the tan δ'(average value) is controlled within a specific range.
However, in the fiber-reinforced plastic of (1), as shown in Examples 1 and 2, most of tan δ'is even in a state of being heated to the melting point of nylon resin (melting point: 225 ° C.) which is a thermoplastic resin. It hasn't changed. Since Vf / (100-Vf) is constant, the fact that tan δ'is hardly changed means that the value of tan δ itself is hardly changed, but the value of tan δ is also in the temperature range above the melting point. If it is small and has large properties as an elastic body, the fluidity of the reinforcing fiber and the thermoplastic resin will not be sufficiently high when heated at the time of shaping, and the reinforcing fiber will be cut at the time of shaping to become shorter. There is a risk that the mechanical properties of the later structural material will be insufficient.

Further, when manufacturing a fiber reinforced plastic or molding a molded product from a fiber reinforced plastic, a mold or the like is used for molding, so that excellent mold releasability from a metal is also required. If the mold release property from the metal is poor, the work efficiency is lowered, and if a part of the fiber reinforced plastic remains on the metal surface without being released at the time of mold release, it may cause a poor appearance.
As a method for improving the mold release property of fiber reinforced plastic from the metal surface, a method of applying a mold release agent to the metal surface (Reference 5) and a method of blending a mold release component such as a wax component into a matrix resin by extrusion kneading. (Reference 6). However, in the method of applying the mold release agent to the metal surface, if the mold surface temperature is high, the mold release performance gradually deteriorates after the mold release agent is applied, so the mold release agent is often applied. There is a problem that work efficiency is reduced. Further, in the method of blending the release component such as the wax component into the matrix resin by extrusion kneading, the release component is dispersed in the resin by the shearing force at the time of extrusion kneading, and the above methods (I) to (III) In the fiber reinforced plastic produced by the above, there is a problem that the dispersibility of the mold release component in the matrix resin is insufficient, so that the mold release performance is inferior.

International Publication No. 2014/142061 Japanese Patent Application Laid-Open No. 07-164439 International Publication No. 2010/013645 International Publication No. 2012/140793 JP 2015-51629 JP-A-2002-179895

An object of the present invention is to provide a fiber reinforced plastic which is excellent in releasability and can achieve both excellent mechanical properties and excellent fluidity at the time of shaping.

As a result of diligent studies to solve the above problems, the present inventors have found that the above problems can be solved by giving the fiber reinforced plastic a specific viscoelastic property and containing a mold release agent, and have found that the present invention can be solved. It came to be completed. That is, the gist of the present invention lies in the following (1) to (5).
(1) A fiber reinforced plastic containing reinforced fibers and matrix resin.
Contains at least one mold release agent,
The following formula of fiber-reinforced plastic in the temperature range of T-30 (° C.) to T-10 (° C.) (where T is the melting point of the matrix resin or the glass transition temperature when it does not have a melting point) ( The average value of the viscoelastic property tanδ represented by 1) was defined as tanδ (ave), and the maximum value of the viscoelastic property tanδ in the temperature range of T-10 (° C.) to T + 10 (° C.) was defined as tanδ (max). When, a fiber-reinforced plastic having a tan δ (ave) of 0.01 to 0.25 and a tan δ (max) -tan δ (ave) of 0.15 or more.
tanδ = G'' / G'・ ・ ・ (1)
However, the symbols in the formula (1) have the following meanings.
G'': Loss elastic modulus,
G': Storage elastic modulus.
(2) The fiber-reinforced plastic according to (1) above, wherein the average fiber length of the reinforcing fibers is 1 to 100 mm.
(3) The fiber-reinforced plastic according to (1) or (2) above, wherein the release agent is a higher fatty acid ester and / or a higher fatty acid salt.
(4) The fiber-reinforced plastic according to any one of (1) to (3) above, which contains 0.01 to 4 parts by mass of the mold release agent with respect to 100 parts by mass of the matrix resin.
(5) The fiber-reinforced plastic according to any one of (1) to (4) above, wherein the matrix resin is a thermoplastic resin.

The fiber-reinforced plastic of the present invention has excellent mold releasability, and can achieve both excellent mechanical properties and excellent fluidity during shaping.

It is a schematic diagram which showed one step of the measuring method of the degree of orientation pf. It is a schematic diagram explaining the processing by the image processing software in the calculation of a variance parameter dp. It is a top view which showed an example of the prepreg base material used in the manufacturing method of the fiber reinforced plastic of this invention. It is a top view which showed the other example of the prepreg base material used in the manufacturing method of the fiber reinforced plastic of this invention. It is a perspective view which showed the state that the material (A) is pressed by a pair of press rolls. It is a schematic diagram which showed an example of a double belt type heating and pressurizing machine.

The fiber reinforced plastic of the present invention is a fiber reinforced plastic containing reinforced fibers and a matrix resin, and contains at least one mold release agent. More specifically, it is a fiber reinforced plastic containing reinforced fibers and a matrix resin.
It contains at least one mold release agent and has a temperature range of T-30 (° C.) to T-10 (° C.) (however, T is the melting point of the matrix resin, or if it does not have a melting point, it is at the glass transition temperature. The average value of the viscoelastic property tan δ represented by the following formula (1) of the fiber-reinforced plastic in (1) is tan δ (ave), and the viscous elasticity in the temperature range of T-10 (° C.) to T + 10 (° C.). When the maximum value of the characteristic tan δ is tan δ (max), the tan δ (ave) is 0.01 to 0.25, and the tan δ (max) -tan δ (ave) is 0.15 or more. be.
tanδ = G'' / G'・ ・ ・ (1)
However, the symbols in the formula (1) have the following meanings.
G'': Loss elastic modulus,
G': Storage elastic modulus.

(Reinforcing fiber)
The reinforcing fiber is not particularly limited, and for example, an inorganic fiber, an organic fiber, a metal fiber, or a reinforcing fiber having a hybrid structure in which these are combined can be used. One type of reinforcing fiber may be used alone, or two or more types may be used in combination.

Examples of the inorganic fiber include carbon fiber, graphite fiber, silicon carbide fiber, alumina fiber, tungsten carbide fiber, boron fiber, glass fiber and the like. Examples of the organic fiber include aramid fiber, high-density polyethylene fiber, other general nylon fiber, polyester fiber and the like. Examples of the metal fiber include fibers such as stainless steel and iron, and carbon fiber coated with metal may also be used. Among these, carbon fiber is preferable in consideration of mechanical properties such as strength of the structural material which is the final molded product.

The carbon fiber is not particularly limited, and examples thereof include polyacrylonitrile (PAN) -based carbon fiber and PITCH-based carbon fiber.
Preferred carbon fibers are carbon fibers having a strand tensile strength of 1.0 GPa or more and 9.0 GPa or less and a strand tensile elastic modulus of 150 GPa or more and 1000 GPa or less as measured according to JIS R7601 (1986).
A more preferable carbon fiber is a carbon fiber having a strand tensile strength of 1.5 GPa or more and 9.0 GPa or less and a strand tensile elastic modulus of 200 GPa or more and 1000 GPa or less as measured according to JIS R7601 (1986).

The average fiber length of the reinforcing fibers in the fiber reinforced plastic is preferably 1 to 100 mm, more preferably 3 to 70 mm, further preferably 5 to 50 mm, particularly preferably 10 to 50 mm, and most preferably 10 to 35 mm.
Generally, the longer the reinforcing fiber is, the more excellent the mechanical properties can be obtained. However, especially at the time of stamping molding, the fluidity is lowered, so that it becomes difficult to obtain a structural material having a complicated three-dimensional shape. When the average fiber length of the reinforcing fiber is not more than the upper limit value, excellent fluidity is obtained at the time of shaping, and the reinforcing fiber and the matrix resin are easy to flow. Therefore, it is easy to obtain a structural material having a complicated three-dimensional shape such as a rib or a boss. Further, if the average fiber length of the reinforcing fibers is at least the lower limit value, a structural material having excellent mechanical properties can be manufactured.

(Measuring method of average fiber length)
The resin in the fiber reinforced plastic is burned off, only the reinforced fibers are taken out, and the fiber length of the reinforced fibers is measured with a caliper or the like. Measurements are made on 100 randomly selected reinforcing fibers and the average fiber length is calculated as their mass average.
The average fiber diameter of the reinforcing fibers is preferably 1 to 50 μm, more preferably 5 to 20 μm.

(Matrix resin)
The matrix resin may be a thermoplastic resin or a thermosetting resin. As the matrix resin, one type may be used alone, or two or more types may be used in combination.
As the matrix resin, a thermoplastic resin is preferable. Since a thermoplastic resin generally has a higher toughness value than a thermosetting resin, using a thermoplastic resin as a matrix resin makes it easy to obtain a structural material having excellent strength, particularly impact resistance. In addition, the shape of the thermoplastic resin is determined by cooling and solidification without any chemical reaction. Therefore, when a thermoplastic resin is used, it can be molded in a short time, and the productivity of fiber reinforced plastics and structural materials is excellent.

The thermoplastic resin is not particularly limited, and is a polyamide resin (nylon 6 (melting point: 225 ° C.), nylon 66 (melting point: 260 ° C.), nylon 12 (melting point: 175 ° C.), nylon MXD6 (melting point: 237 ° C.), etc. ), Polyolefin resin (low density polyethylene (melting point: 95 to 130 ° C.), high density polyethylene (melting point: 120 to 140 ° C.), polypropylene (melting point: 165 ° C.), etc.), Modified polyolefin resin (modified polypropylene resin (melting point: 160 ° C.)) ~ 165 ° C), etc.), polyester resin (polyethylene terephthalate, polybutylene terephthalate, etc.), polycarbonate resin (glass transition temperature: 145 ° C), polyamideimide resin, polyphenylene oxide resin, polysulfone resin, polyethersulfone resin, polyetheretherketone Examples thereof include resins, polyetherimide resins, polystyrene resins, ABS resins, polyphenylene sulfide resins, liquid crystal polyester resins, copolymers of acrylonitrile and styrene, copolymers of nylon 6 and nylon 66, and the like.
Examples of the modified polyolefin resin include resins obtained by modifying a polyolefin resin with an acid such as maleic acid (acid-modified polypropylene resin).
As the thermoplastic resin, one type may be used alone, two or more types may be used in combination, and two or more types may be used as a polymer alloy.
The thermoplastic resin consists of a group consisting of a polyolefin resin, a modified polypropylene resin, a polyamide resin, and a polycarbonate resin in terms of the balance between the adhesiveness with the reinforcing fiber, the impregnation property into the reinforcing fiber, and the raw material cost of the thermoplastic resin. It is preferable to include at least one selected.

The thermosetting resin is not particularly limited, and examples thereof include an epoxy resin, a phenol resin, an unsaturated polyester resin, a urethane resin, a urea resin, a melamine resin, and an imide resin.
As the thermosetting resin, one type may be used alone, or two or more types may be used in combination.
As the thermosetting resin, epoxy resin, phenol resin, unsaturated polyester resin, and imide resin are preferable, and fiber reinforced plastic is preferable from the viewpoint of developing the mechanical properties of the fiber reinforced plastic after the thermocurable resin is cured. From the viewpoint of ease of manufacture, epoxy resin and unsaturated polyester resin are more preferable.

(Release agent)
The release agent is not particularly limited, and for example, a higher fatty acid ester, a higher fatty acid metal salt, a higher fatty acid, a paraffin wax, a beeswax, an olefin wax, an olefin wax having a carboxy group and / or a carboxylic acid anhydride group, and a silicone. Examples include oils, organopolysiloxanes, aliphatic amines, ethylene bisamide compounds and the like. Of these, higher fatty acid esters and higher fatty acid metal salts are preferable. As the release agent, one type may be used alone, or two or more types may be used in combination.
As the higher fatty acid ester, a partial ester or a total ester of a monovalent or polyvalent alcohol having 1 to 20 carbon atoms and a saturated fatty acid having 10 to 30 carbon atoms is preferable. Examples of such monohydric or polyhydric alcohols include ethylene glycol, glycerin, dipentaerythritol, tripentaerythritol, and sorbitan. Examples of such saturated fatty acids include caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, linoleic acid, linolenic acid, and montanic acid. Of these, stearic acid and montanic acid are preferable.

As the higher fatty acid metal salt, a partially saponified or totally saponified product of the higher fatty acid ester, or a salt of a saturated fatty acid having 10 to 30 carbon atoms and a metal element is preferable. Examples of such saturated fatty acids include caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, linoleic acid, linolenic acid, and montanic acid. Of these, stearic acid and montanic acid are preferable. Examples of such metal elements include calcium, magnesium, sodium, lithium, barium, zinc, aluminum and the like.
As the higher fatty acid, a substituted or unsubstituted saturated fatty acid having 10 to 30 carbon atoms is preferable, and an unsubstituted or unsubstituted saturated fatty acid having 10 to 30 carbon atoms is more preferable. Examples of such higher fatty acids include caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, linoleic acid, linolenic acid, and montanic acid. Of these, stearic acid and montanic acid are preferable.

The amount of the release agent in the fiber-reinforced plastic of the present invention is not particularly limited, but it is preferable that 0.01 to 4 parts by mass of the release agent is contained with respect to 100 parts by mass of the matrix resin, and 0.02 to 2 parts. By mass is more preferable, 0.03 to 1 part by mass is further preferable, and 0.05 to 0.5 part by mass is most preferable.

Other additives may be added to the fiber reinforced plastic of the present invention according to the required characteristics of the target structural material.
Other additives include, for example, flame retardants, weather resistance improvers, antioxidants, heat stabilizers, UV absorbers, plasticizers, lubricants, colorants, compatibilizers, non-fibrous fillers, conductive fillers, etc. Examples thereof include a surfactant and the like, and a thermoplastic resin may be used as another additive.

The fiber-reinforced plastic of the present invention has a tan δ (ave) of 0.01 to 0.25 and a tan δ (max) -tan δ (ave) of 0.15 or more. When tan δ (ave) and tan δ (max) -tan δ (ave) each satisfy the above range, excellent mold release property due to the effect of the mold release agent is exhibited, and excellent mechanical properties and excellent shaping are excellent. It is possible to achieve both fluidity and fluidity.
“Tan δ (ave)” is a temperature range from T-30 (° C.) to T-10 (° C.) (where T is the melting point of the matrix resin or the glass transition temperature when it does not have a melting point). It is an average value of the viscoelastic property tan δ of the fiber-reinforced plastic of.
The “tan δ (max)” is the maximum value of the viscoelastic property tan δ in the temperature range of T-10 (° C.) to T + 10 (° C.).
The viscoelastic property tan δ is expressed by the following equation (b1).
tanδ = G'' / G'・ ・ ・ (b1)
(However, G'' is the loss elastic modulus (Pa), and G'is the storage elastic modulus (Pa).)
The tan δ (ave) of the fiber reinforced plastic of the present invention is 0.01 to 0.25, preferably 0.02 to 0.20, and more preferably 0.03 to 0.15. When tan δ (ave) is extremely low (close to zero), it means that it is close to a completely elastic body, and its properties are far from those of a plastic material, and mechanical properties and fluidity as a plastic material cannot be expected. However, when tan δ (ave) is at least the lower limit value, a fiber reinforced plastic having a good balance of mechanical properties and flow properties can be obtained, and excellent mold release property is exhibited due to the effect of the mold release agent. When tan δ (ave) is not more than the upper limit value, a structural material having excellent mechanical properties can be manufactured.
The tanδ (max) -tanδ (ave) of the fiber-reinforced plastic of the present invention is 0.15 or more, preferably 0.25 or more, and more preferably 0.35 or more. When tan δ (max) -tan δ (ave) is equal to or higher than the lower limit, excellent fluidity can be obtained at the time of shaping, so that it is possible to prevent the reinforcing fibers from being cut at the time of shaping and the mechanical properties of the structural material from deteriorating. ..
When tan δ (max) -tan δ (ave) is extremely large, that is, when tan δ (max) is extremely large, only the matrix resin flows at the time of shaping, and the reinforcing fibers do not follow the flow of the matrix resin. From this viewpoint, the tanδ (max) -tanδ (ave) of the fiber-reinforced plastic of the present invention is preferably 1.5 or less, more preferably 0.9 or less.
The tan δ of the fiber reinforced plastic becomes smaller as the dispersibility of the reinforced fiber becomes higher. The tan δ of the fiber reinforced plastic can be adjusted, for example, by adjusting the clearance between the belts at the time of pressurization in the method for producing the fiber reinforced plastic described later. The narrower the clearance, the better the dispersibility of the reinforcing fibers in the fiber reinforced plastic, and the smaller the tan δ tends to be. Further, for example, the value of tan δ (max) − tan δ (ave) can be adjusted by adjusting the fiber volume content (Vf) of the reinforced fiber in the fiber reinforced plastic. The higher the Vf of the fiber reinforced plastic, the smaller the tan δ (max) tends to be.
In addition, the entanglement of the reinforcing fibers and the friction between the reinforcing fibers in the fiber reinforced plastic also affect the tan δ (max), and the larger the entanglement and the friction, the smaller the tan δ (max) tends to be.
If the polymer alloy has a plurality of melting points and a glass transition temperature, one melting point or glass transition temperature T satisfying the range of tanδ (ave) and tanδ (max) -tanδ (ave) of the present invention. It suffices to have the above.

The fiber volume content (Vf) of the reinforced fiber in the fiber reinforced plastic of the present invention is preferably 5 to 70% by volume, more preferably 10 to 60% by volume, further preferably 15 to 50% by volume, and 25 to 45% by volume. % Is most preferable. When the Vf of the reinforcing fiber is not more than the upper limit value, the interface strength is less likely to decrease due to the decrease in toughness, and the fluidity at the time of molding is also less likely to decrease. When the Vf of the reinforcing fiber is at least the lower limit value, the mechanical properties required for the fiber reinforced plastic can be easily obtained.
The Vf value of the fiber reinforced plastic means the volume ratio of the reinforcing fiber to the total volume of other components such as the reinforcing fiber, the matrix resin, the mold release agent, and other additives in the fiber reinforced plastic. Since the Vf value measured based on JIS K7075 is a value that varies depending on the abundance of voids in the fiber reinforced plastic, the fiber volume content rate that does not depend on the abundance of voids is adopted in the present invention.

(Orientation degree pf)
In the fiber-reinforced plastic of the present invention, the degree of orientation pf of the reinforcing fibers in the direction orthogonal to the thickness direction is preferably 0.001 to 0.8. pf is an index showing the orientation state of the reinforcing fibers in the direction orthogonal to the thickness direction in the fiber reinforced plastic. When pf is "0", it means that the reinforcing fibers are oriented in an ideal state in a direction orthogonal to the thickness direction of the fiber reinforced plastic. The larger the value of pf, the higher the degree to which the reinforcing fibers are disturbed toward the outside of the plane orthogonal to the thickness direction.
Although it depends on the fiber length of the reinforcing fibers, the larger the value of pf, the more difficult it is to obtain the fluidity at the time of shaping due to the entanglement between the reinforcing fibers and the friction between the reinforcing fibers. That is, the more the reinforcing fibers are disturbed toward the outside of the surface orthogonal to the thickness direction, the more easily the reinforcing fibers are entangled with each other and the friction between the reinforcing fibers is likely to occur, and it is difficult to obtain the fluidity at the time of shaping. When the average fiber length of the reinforcing fibers is 1 mm to 100 mm and the pf is 0.8 or less, it is easy to obtain excellent fluidity at the time of shaping, and it is easy to obtain a structural material having excellent mechanical properties. The lower limit of pf is not particularly limited in terms of the physical properties of the fiber reinforced plastic. However, it is difficult to set pf to 0, and 0.001 or more is a realistic value. The upper limit of pf is preferably 0.5, more preferably 0.3, and even more preferably 0.15.

(Measurement method of pf)
As shown in FIG. 1, a measurement sample 2210 having a width of 2 mm is cut out from a fiber reinforced plastic 2200 having a thickness of 2 mm, and measurement is carried out as follows.
The width direction of the measurement sample 2210 is the x direction, the thickness direction is the y direction, and the length direction is the z direction.

ただし、式（ｂ２）中、Ｉ（δ）は、１次元配向プロファイルにおける、ｙｚ平面でのｚ方向を基準とした方位角δのときの強度である。
強化繊維がｘ方向に完全配向しているときにＳｘは最大の値をとる。強化繊維がｘ方向から傾きを持つことでＳｘの値は小さくなる。Ｓｘが小さくなる要因としては、強化繊維のｘ方向に対する傾きにおける厚み方向の成分と、厚み方向に直交する平面内の成分がある。すなわち、強化繊維のｘ方向に対する傾きにおけるｙｚ平面内の成分と、ｘｚ平面内の成分の両方が、Ｓｘが小さくなる要因となる。ｐｆでは、厚み方向と直交する面の外方向へ向かって強化繊維が乱れている度合いを評価するため、強化繊維の傾きにおけるｘｚ平面内の成分の影響を除去するために、次の操作を行う。 <Actually measured integral value in the x direction>
The measurement sample 2210 is irradiated with X-rays in the x direction to obtain a one-dimensional orientation profile derived from the diffraction of the 002 surface of graphite. The one-dimensional orientation profile derived from the diffraction of the 002 surface of graphite is obtained by a method of capturing an image using a two-dimensional detector and then obtaining a profile in the circumferential direction in the 002 diffraction portion using analysis software. Further, in the case of a one-dimensional detector, the one-dimensional orientation profile derived from the diffraction of the 002 surface of graphite can be obtained by fixing the detector at 002 diffraction and rotating the sample by 360 °.
Next, from the obtained one-dimensional orientation profile, the measured integral value Sx in the x direction is calculated by the following equation (b2).

However, in the equation (b2), I (δ) is the intensity at the azimuth angle δ with respect to the z direction in the yz plane in the one-dimensional orientation profile.
Sx has the maximum value when the reinforcing fibers are completely oriented in the x direction. The value of Sx becomes smaller because the reinforcing fiber has an inclination from the x direction. Factors that reduce Sx include a component in the thickness direction in the inclination of the reinforcing fiber with respect to the x direction and a component in a plane orthogonal to the thickness direction. That is, both the component in the yz plane and the component in the xz plane in the inclination of the reinforcing fiber with respect to the x direction cause the Sx to become small. In pf, in order to evaluate the degree to which the reinforcing fibers are disturbed toward the outside of the plane orthogonal to the thickness direction, the following operation is performed in order to eliminate the influence of the components in the xz plane on the inclination of the reinforcing fibers. ..

ただし、式（ｂ３）中、Ｉ（ψ）は、前記１次元配向プロファイルにおける、ｘｚ平面でのｚ方向を基準とした方位角ψのときの強度である。
次いで、下式（ｂ４）により、ｘ方向の予測積分値Ｆを算出する。

ただし、Ｖａは、測定試料２２１０中の強化繊維の繊維体積含有率（Ｖｆ）である。Ｖｂは、後述する補正用の標準試料中の強化繊維の繊維体積含有率（Ｖｆ）である。Ａ（ψ）は、強度補正係数である。 <Predicted integral value in the x direction>
The measurement sample 2210 is irradiated with X-rays in the y direction to obtain a one-dimensional orientation profile derived from the diffraction of the 002 surface of graphite. Next, I (ψ) is standardized by the following equation (b3) to calculate the fiber ratio G (ψ) at the azimuth angle ψ.

However, in the equation (b3), I (ψ) is the intensity at the azimuth angle ψ with respect to the z direction in the xz plane in the one-dimensional orientation profile.
Next, the predicted integral value F in the x direction is calculated by the following equation (b4).

However, Va is the fiber volume content (Vf) of the reinforcing fibers in the measurement sample 2210. Vb is the fiber volume content (Vf) of the reinforcing fiber in the standard sample for correction described later. A (ψ) is an intensity correction coefficient.

ただし、Ｉ（ψ，δ）は、方位角ψの標準測定試料についての方位角δにおける強度である。
積分値Ｓ（ψ）においては、Ｓ（ψ）＝Ｓ（π－ψ）の関係にある。横軸にψ、縦軸にＳ（ψ）をとってプロットし、ψが０°～１８０°の範囲で正規分布近似したものを方位角ψにおける強度補正係数Ａ（ψ）とする。 The strength correction coefficient A (ψ) is obtained as follows.
As a standard sample for correction, a UD material having a thickness of 2 mm is prepared by aligning reinforcing fibers in one direction so as to be completely oriented in the z direction, and this is used as a 0 ° material. The reinforcing fibers and the matrix resin used in the standard sample are the same as those in the measurement sample 2210. Va, which is the fiber volume content (Vf) of the reinforcing fiber in the measurement sample 2210, and Vb, which is the fiber volume content (Vf) of the reinforcing fiber in the standard sample for correction, are the same but different. You may.
Then, as a further standard sample, a 15 ° material is produced in the same manner as the 0 ° material, except that the reinforcing fibers are aligned in one direction so that the azimuth angle ψ is completely oriented in the direction of 15 °. Similarly, 30 ° material, 45 ° material, 60 in which the reinforcing fibers are aligned in one direction so that the azimuth angle ψ is completely oriented in each of the directions of 30 °, 45 °, 60 °, 75 °, and 90 °. Prepare ° materials, 75 ° materials, and 90 ° materials.
Next, a standard measurement sample having a width of 2 mm is cut out from each standard sample in the same manner as the measurement sample 2210. X-rays are incident on the standard measurement sample in the x direction to obtain a one-dimensional orientation profile derived from the diffraction of the 002 plane of graphite. In the one-dimensional orientation profile of the standard measurement sample derived from the 90 ° material, the strength is almost constant. From the one-dimensional orientation profile of each standard measurement sample, the integral value S (ψ) of the strength I (ψ, δ) of the material having the azimuth angle ψ is calculated by the following equation (b5).

However, I (ψ, δ) is the intensity at the azimuth angle δ for the standard measurement sample of the azimuth angle ψ.
In the integrated value S (ψ), there is a relationship of S (ψ) = S (π-ψ). Plot with ψ on the horizontal axis and S (ψ) on the vertical axis, and let the strength correction coefficient A (ψ) at the azimuth angle ψ be obtained by approximating the normal distribution in the range of 0 ° to 180 °.

<Predicted integral strength of correction in the x direction>
The predicted integral value F in the x direction and the actually measured integral value Sx do not always match. Therefore, the integral value correction coefficient B (Sx) is calculated using a standard sample.
A standard measurement sample is cut out from each standard sample in the same manner as in the calculation of the intensity correction coefficient A (ψ). For each standard measurement sample, the measured integrated value Sx (α) is calculated by the above-mentioned method for calculating the measured integrated value in the x direction. In addition, α is 0 °, 15 °, 30 °, 45 °, 60 °, 75 °, 90 °. Further, for each standard measurement sample, the predicted integral value F (α) in the x direction is obtained by the above-mentioned method for calculating the predicted integral value in the x direction. When Sx (α) is plotted on the horizontal axis and Sx (α) / F (α) is plotted on the vertical axis, there is a high correlation, and the linear approximation is taken as the integral correction coefficient B (Sx).
The integral correction coefficient B (Sx) is multiplied by the predicted integral value F in the x direction to obtain the predicted integral strength F'for the correction in the x direction.

<Calculation of pf>
The pf is calculated by the following formula (b6).

(Elliptical dissociation constant ec)
In the fiber reinforced plastic of the present invention, the elliptical deviation coefficient ec of the orientation profile of the reinforcing fibers on the surface orthogonal to the thickness direction is preferably 1 × 10 ^-5 to 9 × 10 ^-5 . ec is an index showing the dispersibility of the two-dimensional orientation of the reinforcing fibers in the plane orthogonal to the thickness direction in the fiber reinforced plastic of the present invention. ec is the dissociation constant of the orientation profile described above from its approximate ellipse.
In a fiber reinforced plastic in which reinforcing fibers are randomly oriented, the larger the ec, the larger the variation in mechanical properties. When ec is 9 × ^10-5 or less, it is easy to suppress the variation in mechanical properties. The ec of the fiber reinforced plastic of the present invention is preferably 8.5 × 10 ^-5 or less, more preferably 8 × 10 ^-5 or less.
The preferable lower limit of ec is not particularly limited in terms of the mechanical properties of the fiber reinforced plastic. However, for example, as the fiber length of the reinforcing fiber becomes longer, the difficulty of manufacturing a fiber-reinforced plastic having a small ec value increases. If the fiber length of the reinforcing fiber is lengthened, the mechanical properties are improved, but the ec value tends to increase accordingly, and the variation in the mechanical properties increases. Considering the balance between the mechanical properties and the variation thereof, the preferable lower limit value of ec according to the average fiber length of the reinforcing fiber, which is realistic from the viewpoint of manufacturing, is as follows. When the average fiber length of the reinforcing fibers is 1 to 3 mm, the ec is preferably 1 × 10 ^-5 or more. When the average fiber length of the reinforcing fibers is more than 3 mm and 10 mm or less, the ec is preferably 1.5 × 10 ^-5 or more. When the average fiber length of the reinforcing fibers is more than 10 mm and 35 mm or less, the ec is preferably 2 × 10 ^-5 or more. When the average fiber length of the reinforcing fibers is more than 35 mm and 70 mm or less, the ec is preferably 3 × 10 ^-5 or more. When the average fiber length of the reinforcing fibers is more than 70 mm and 100 mm or less, the ec is preferably 4 × 10 ^-5 or more.

ただし、式（ｂ７）中、ａは楕円の長径である。ｂは楕円の短径である。βは回転角である。
Ｉａ（ψ）がＩ（ψ）に最も近くなるときのａ、ｂ、βは、下式（ｂ８）で表される楕円からの乖離度Ｒが最少になるように数値計算すればよい。そして、そのときの乖離度Ｒの最少値をｅｃとする。

(Measurement method of ec)
The profile of the intensity I (ψ) at the azimuth angle ψ measured when the predicted integral value in the x direction is obtained in the measurement of pf is approximated by the ellipse Ia (ψ) represented by the following equation (b7).

However, in the formula (b7), a is the major axis of the ellipse. b is the minor axis of the ellipse. β is the angle of rotation.
A, b, and β when Ia (ψ) is closest to I (ψ) may be numerically calculated so that the degree of deviation R from the ellipse represented by the following equation (b8) is minimized. Then, the minimum value of the dissociation degree R at that time is set to ec.

(Distribution parameter dp)
The dispersion parameter dp of the reinforcing fiber in the cross section of the fiber reinforced plastic of the present invention in the thickness direction is preferably 100 to 80. dp is an index showing the three-dimensional dispersion of the reinforcing fibers in the fiber reinforced plastic. When dp is "100", it means that the reinforcing fibers are dispersed in the matrix resin in an ideal state. The smaller the value of dp, the higher the ratio of locally agglomerated reinforcing fibers and the higher the ratio of the resin-rich portion.
The smaller the value of dp and the worse the dispersibility of the reinforcing fibers, the worse the heat resistance. When dp is 80 or more, good heat resistance can be easily obtained. The dp of the fiber reinforced plastic of the present invention is more preferably 84 or more, further preferably 88 or more. The upper limit of dp of the fiber reinforced plastic of the present invention is 100 in theory. From a manufacturing point of view, the practical upper limit of dp is 98.
The fluidity of the fiber-reinforced plastic during shaping is caused by the flow of the resin or the slip of the resin layer at the time of shaping. Therefore, the wider the path through which the resin in the fiber reinforced plastic can flow, the higher the fluidity can be obtained at the time of shaping. That is, the smaller the dp, the higher the fluidity at the time of shaping. In the fiber-reinforced plastic of the present invention, by controlling the pf within the above range, high fluidity is exhibited even if the value of dp is high.

２値化後の処理対象画像の強化繊維部分において、図２に示すように強化繊維が完全理論分散していると仮定する。そして、図２に示すように、強化繊維の半径を下式（ｂ１０）で表される長さＬｅ分だけ長くし、前記強化繊維の半径がＬａとなるように、画像編集ソフトにより２値化後における強化繊維部分を膨張させる。なお、Ｌｅは、強化繊維が理想分散した状態における、隣り合う強化繊維の外壁面間の距離が最も遠くなるところの距離の半分の距離である。２値化後における強化繊維部分において実際に強化繊維が理想分散していたときに前記した膨張処理をすれば、強化繊維部分が処理対象画像の全面積を占めることになる。
前記の画像編集ソフトによる膨張処理後、下式（ｂ１１）によりｄｐを算出する。

ただし、式（ｂ１１）中、Ｓ１は、処理対象画像中の前記膨張処理後の強化繊維部分の面積である。Ｓ２は、処理対象画像の全体面積である。
本発明の繊維強化プラスチックの厚みは、０．１～１０．０ｍｍが好ましく、０．２５～６．０ｍｍがより好ましく、０．４～４．０ｍｍがさらに好ましい。厚みが上限値以下であれば、繊維強化プラスチックの製造における加圧時にマトリックス樹脂がはみ出しにくく、厚み制御が容易である。厚みが下限値以上であれば、繊維強化プラスチックの製造における加圧時にせん断応力が掛かりやすく、強化繊維をランダム化させて機械物性の等方性や異方性をコントロールすることが容易になる。 (Dp measurement method)
The dp can be measured by processing a cross-sectional photograph of a sample piece cut out from a fiber reinforced plastic in the thickness direction using image editing software.
Specifically, for example, a sample piece is cut out from a fiber reinforced plastic, and a cross-sectional photograph of the sample piece is taken. For example, an optical microscope can be used for taking a cross-sectional photograph. The dot pitch at the resolution at the time of photographing is preferably 1/10 or less, more preferably 1/20 or less of the diameter of the reinforcing fiber, from the viewpoint that the accuracy of the evaluation by dp becomes higher.
Next, the cut photo is processed as follows using image editing software.
In the cut photograph, the portion corresponding to the rectangular range of 2 mm in the thickness direction and 1.5 mm in the direction orthogonal to the thickness direction in the cross section of the sample piece is used as the image to be processed. In the image to be processed, the image editing software binarizes the reinforcing fiber portion, the resin portion, and the void portion. For example, in the image to be processed in which the reinforcing fiber portion is white, the resin portion is gray, and the void portion is black, the reinforcing fiber portion is black and the resin portion and the void portion are green.
As shown in FIG. 2, the unit of the regular hexagon H when the reinforcing fibers C are completely theoretically dispersed on the cut surface of the fiber reinforced plastic having the radius of the reinforcing fibers r (μm) and the fiber volume content of Vf (volume%). The length La of one side is obtained by the following equation (b9).

It is assumed that the reinforcing fibers are completely theoretically dispersed as shown in FIG. 2 in the reinforcing fiber portion of the image to be processed after binarization. Then, as shown in FIG. 2, the radius of the reinforcing fiber is lengthened by the length Le represented by the following equation (b10), and binarized by image editing software so that the radius of the reinforcing fiber becomes La. The later reinforcing fiber portion is expanded. In addition, Le is a distance of half of the distance where the distance between the outer wall surfaces of the adjacent reinforcing fibers is the longest in the state where the reinforcing fibers are ideally dispersed. If the above-mentioned expansion treatment is performed when the reinforcing fibers are actually ideally dispersed in the binarized reinforcing fiber portion, the reinforcing fiber portion occupies the entire area of the image to be processed.
After the expansion process by the image editing software, the dp is calculated by the following formula (b11).

However, in the formula (b11), S1 is the area of the reinforcing fiber portion after the expansion treatment in the image to be processed. S2 is the total area of the image to be processed.
The thickness of the fiber reinforced plastic of the present invention is preferably 0.1 to 10.0 mm, more preferably 0.25 to 6.0 mm, still more preferably 0.4 to 4.0 mm. When the thickness is not more than the upper limit, the matrix resin does not easily squeeze out during pressurization in the production of the fiber reinforced plastic, and the thickness can be easily controlled. When the thickness is not less than the lower limit, shear stress is likely to be applied at the time of pressurization in the production of fiber reinforced plastic, and it becomes easy to randomize the reinforced fibers to control the isotropic and anisotropy of mechanical properties.

(Manufacturing method of fiber reinforced plastic)
As a method for producing a fiber-reinforced plastic of the present invention, a method having the following steps (i) to (iii) is available because it is easy to control tan δ (ave) and tan δ (max) -tan δ (ave) within the above range. preferable.
(I) A step of obtaining a material (A) containing a prepreg base material in which a reinforcing fiber aligned in one direction is impregnated with a matrix resin and a notch is formed so as to intersect the fiber axis.
(Ii) The material (A) is made by using a pressurizing device that pressurizes the material (A) substantially uniformly in a direction orthogonal to the traveling direction so that the direction of the fiber axis of the reinforcing fiber intersects the traveling direction. A step of pressurizing in a state of being heated to a temperature T equal to or higher than the melting point of the matrix resin or, if not having a melting point, the glass transition temperature or higher, while traveling in one direction.
(Iii) A step of cooling the material (A) pressurized by the pressurizing device to obtain a fiber reinforced plastic.

{Step (i)}
In the step (i) in the method for producing a fiber-reinforced plastic of the present invention, a material (A) containing a prepreg base material is obtained. The material (A) may be a single-layer material composed of only one prepreg base material, or may be a prepreg laminate in which two or more prepreg base materials are laminated.
The prepreg base material used in the step (i) is one in which the reinforcing fibers aligned in one direction are impregnated with the matrix resin. Additives may be added to the prepreg base material according to the required characteristics of the target structural material.
The prepreg base material used in the step (i) is formed with a notch so as to intersect the fiber axis. As a result, in the prepreg base material, the reinforcing fibers having a long fiber length aligned in one direction are divided by the cut, and the fiber length is 1 to 100 mm.
When a sheet-shaped fiber reinforced plastic is formed by dispersing and integrating prepreg pieces cut out from a prepreg base material, which is generally called a random material, it is difficult to design parts because the mechanical properties vary. On the other hand, in the methods according to the steps (i) to (iii), since the fiber reinforced plastic is obtained by using the prepreg base material with the notch, the mechanical properties are better than the case of using the random material, and the variation is also good. Can be made smaller.

The shape of the notch formed in the prepreg base material used in the method for producing a fiber-reinforced plastic of the present invention is not particularly limited, and may be, for example, a straight line, a curved line, or a polygonal line.
The angle of the cut reinforcing fiber formed in the prepreg base material used in the method for producing the fiber reinforced plastic of the present invention with respect to the fiber axis is also not particularly limited, but the angle θ between the fiber axis of the reinforcing fiber and the cut is 0 ° <θ. A notch having <90 ° (hereinafter, also referred to as a notch (b)) and a notch having an angle θ of −90 ° <θ <0 ° (hereinafter, also referred to as a notch (c)) are formed. Is preferable. The angle θ is positive counterclockwise with respect to the fiber axis of the reinforcing fiber in a plan view.
The prepreg base material used in the present invention has a notch in which the angle θ between the fiber axis of the reinforcing fiber and the notch is 0 ° <θ <90 ° (hereinafter, also referred to as a notch (b)) and the angle θ. A notch (hereinafter, also referred to as a notch (c)) in which −90 ° <θ <0 ° is formed. The angle θ is positive counterclockwise with respect to the fiber axis of the reinforcing fiber in a plan view.

Further, in the prepreg base material used in the step (i), a region in which a plurality of cuts (b) are formed in the fiber axis direction of the reinforcing fiber (hereinafter, also referred to as a region (B)) and a cut (c) are reinforced. It is preferable that a plurality of regions formed in the fiber axis direction of the fiber (hereinafter, also referred to as a region (C)) are alternately formed in a direction orthogonal to the fiber axis of the reinforcing fiber. As described above, in the prepreg base material used in the step (i), in a plan view in a state where the reinforcing fibers aligned in one direction are arranged so that the fiber axis direction is the lateral direction, a linear cut with a downward slope to the left is performed. The region (B) in which a plurality of (b) are formed and the region (C) in which a plurality of linear cuts (c) descending to the right are formed are alternately formed in a direction orthogonal to the fiber axis of the reinforcing fiber. It is preferable that the fiber is used.
In the prepreg base material, the regions (B) and the regions (C) are alternately formed in the direction orthogonal to the fiber axis of the reinforcing fiber, so that in the step (ii), the entire base material is randomly formed in the fiber axis direction of the reinforcing fiber. The formation occurs more uniformly, and the deviation of the reinforcing fibers in the fiber axis direction becomes smaller. Therefore, the fiber-reinforced plastic is less likely to swell or warp, and the winding diameter at the time of winding becomes small. Further, a fiber reinforced plastic having excellent mechanical properties and excellent isotropic properties can be obtained.
In addition, in the embodiment in which the region (B) and the region (C) are alternately formed in the direction orthogonal to the fiber axis of the reinforcing fiber, the region (B) consisting of a row of cuts (b) and an example of the cut ( It is not limited to the mode in which the region (C) consisting of c) is alternately formed. An embodiment in which a region (B) consisting of two rows of cuts (b) and a region (C) consisting of two rows of cuts (c) are alternately formed, and a region (B) consisting of three rows of cuts (b). ) And the region (C) composed of the three cuts (c) may be alternately formed.

The angle θ of each notch (b) in the region (B) is preferably 10 ° to 89 °, more preferably 25 ° to 89 °. When the angle θ of each notch (b) in the region (B) is within the above range, randomization in the fiber axis direction of the reinforcing fibers tends to occur more uniformly.
The angle θ for each notch (b) in the region (B) may be the same or different. It is preferable that the angle θ for each notch (b) in the region (B) is the same in that the randomization of the reinforcing fibers in the fiber axis direction is more likely to occur.
The length of the notch (b) is not particularly limited and can be set as appropriate. It is preferable that the length of each notch (b) is the same. The length of each notch (b) may be different.
The number of cuts (b) in the fiber axis direction of the reinforcing fibers in the region (B) is not particularly limited, and the length of the reinforcing fibers divided by the cuts may be appropriately determined to be a desired length.
The number of columns of the notch (b) in the region (B) may be one column or two or more columns.

The angle θ of each notch (c) in the region (C) is preferably −89 ° to −10 °, more preferably −89 ° to −20 °. When the angle θ of each notch (c) in the region (C) is within the above range, randomization in the fiber axis direction of the reinforcing fibers tends to occur more uniformly.
The angle θ for each notch (c) in the region (C) may be the same or different. It is preferable that the angle θ for each notch (c) in the region (C) is the same in that randomization in the fiber axis direction of the reinforcing fibers is more likely to occur.
The absolute value of the angle θ of each cut (b) in the region (B) and the angle θ of each cut (c) in the region (C) are such that randomization of the reinforcing fibers in the fiber axis direction is more likely to occur. It is more preferable that the absolute value of is the same. The absolute value of the angle θ of each notch (b) in the region (B) may be different from the absolute value of the angle θ of each notch (c) in the region (C), but these absolute values may be different. It is preferable that the difference is as small as possible.
The length of the notch (c) is not particularly limited and can be set as appropriate. It is preferable that the length of each notch (c) is the same. The length of each notch (c) may be different.
The length of the notch (c) is preferably the same as the length of the notch (b). The length of the notch (c) and the length of the notch (b) may be different.
The number of cuts (c) in the fiber axis direction of the reinforcing fibers in the region (C) is not particularly limited, and the length of the reinforcing fibers divided by the cuts may be appropriately determined to be a desired length.
The number of columns of the notch (c) in the region (C) may be one column or two or more columns. It is preferable that the number of columns of the notch (c) in the region (C) is the same as the number of columns of the notch (b) in the region (B).

The relationship between the region (B) and the region (C) in the prepreg base material is the region (C) when the region (B) is inverted so as to be line-symmetrical with respect to the direction orthogonal to the fiber axis of the reinforcing fiber. ) Is preferred. This facilitates more uniform randomization of the reinforcing fibers in the fiber axis direction.
Further, the end of the notch (b) closest to the region (C) in the region (B) and the end of the notch (c) closest to the region (B) in the region (C) are the fiber shafts of the reinforcing fibers. It is preferable that the directions are staggered. This facilitates more uniform randomization of the reinforcing fibers in the fiber axis direction.
It is preferable that the length in the direction orthogonal to the fiber axis of the reinforcing fiber in the region (B) and the length in the direction orthogonal to the fiber axis of the reinforcing fiber in the region (C) are the same.

Specific examples of the prepreg base material include the prepreg base material 12 illustrated in FIG.
In the prepreg base material 12, the reinforcing fibers 13 aligned in one direction are impregnated with the matrix resin 14, and the cuts (b) 15 and the cuts (c) 16 are formed so as to intersect the fiber axis of the reinforcing fibers 13. ing. The notch (b) 15 is a notch in which the angle θ formed by the reinforcing fiber 13 with the fiber axis is 0 ° <θ <90 °. The notch (c) 16 is a notch in which the angle θ formed by the reinforcing fiber 13 with the fiber axis is −90 ° <θ <0 °.
In the prepreg base material 12, a region (B) 17 consisting of a row of notches (b) 15 formed in the fiber axis direction of the reinforcing fiber 13 and a plurality of rows formed in the fiber axis direction of the reinforcing fiber 13. The region (C) 18 composed of the notch (c) 16 is alternately formed in the direction orthogonal to the fiber axis of the reinforcing fiber 13. That is, in the prepreg base material 12, rows of notches (b) 15 and rows of notches (c) 16 are alternately formed in a direction orthogonal to the fiber axis of the reinforcing fiber 13.
Further, the prepreg base material may be the prepreg base material 12A exemplified in FIG.
The prepreg base material 12A is the same as the prepreg base material 12 except that the region (B) 17A is provided in place of the region (B) 17 and the region (C) 18A is provided in place of the region (C) 18. The region (B) 17A is the same as the region (B) 17 except that two rows of notches (b) 15 are formed in the fiber axis direction of the reinforcing fiber 13. The region (C) 18A is the same as the region (C) 18 except that two rows of notches (c) 16 are formed in the fiber axis direction of the reinforcing fiber 13. In the prepreg base material 12A, rows consisting of cuts (b) 15 and rows consisting of cuts (c) 16 are alternately formed in every two rows in a direction orthogonal to the fiber axis of the reinforcing fiber 13.

In the prepreg base material used in the method for producing a fiber-reinforced plastic of the present invention, the preferable range of the length of the reinforcing fiber cut by the cut is the same as the preferable range of the fiber length of the reinforcing fiber in the fiber-reinforced plastic described above. ..

The fiber volume content (Vf) in the prepreg base material used in the method for producing a fiber reinforced plastic of the present invention is preferably 5 to 70% by volume, more preferably 10 to 60% by volume, still more preferably 15 to 50% by volume. , 25-45% by volume are most preferred. When Vf is at least the lower limit value, it is easy to obtain a structural material having sufficient mechanical properties. When Vf is not more than the upper limit value, good fluidity can be easily obtained at the time of shaping.
The Vf value of the prepreg base material means the volume ratio of the reinforcing fiber to the total volume of other components such as the reinforcing fiber, the matrix resin, the mold release agent, and other additives in the prepreg base material. Since the Vf value measured based on JIS K7075 is a value that varies depending on the abundance of voids in the fiber prepreg base material, the fiber volume content that does not depend on the abundance of voids in the method for producing a fiber reinforced plastic of the present invention. Adopt the rate.

The thickness of the prepreg base material used in the method for producing a fiber-reinforced plastic of the present invention is preferably 50 to 500 μm. When the thickness of the prepreg base material is at least the lower limit, the prepreg base material can be easily handled. Further, when two or more prepreg base materials are laminated to obtain the material (A) having a desired thickness, it is possible to prevent the number of laminated prepreg base materials from becoming too large, so that the productivity is improved. When the thickness of the prepreg base material is not more than the upper limit, voids (pores) inside the prepreg base material generated during the production of the prepreg base material can be suppressed, and a fiber reinforced plastic having sufficient mechanical properties can be obtained. Cheap.
In the method for producing a fiber reinforced plastic of the present invention, the influence of the thickness of the prepreg base material on the strength of the finally obtained structural material is small.
The method for producing the prepreg base material used in the method for producing the fiber-reinforced plastic of the present invention is not particularly limited, and a known method can be adopted. As the prepreg base material, a commercially available prepreg base material may be used. Examples of the method for forming a notch in the prepreg base material include a method using a laser marker, a cutting plotter, a die, and the like. The method using a laser marker is preferable because it can process a notch having a complicated shape such as a curved line or a zigzag line at high speed. The method using a cutting plotter is preferable because it is easy to process even a large-sized prepreg base material having a size of 2 m or more. The method using a die is preferable in that it can be processed at high speed.

When the material (A) is a prepreg laminated body, in the prepreg laminated body, it is preferable to laminate a resin sheet between the prepreg base materials to be laminated to form a resin layer. As a result, the fluidity is improved in the step (ii), the isotropic property and anisotropy of the mechanical properties are controlled, and it becomes easy to obtain a fiber reinforced plastic having less variation in the mechanical properties.
The resin used for the resin layer is not particularly limited, and examples thereof include the same as the matrix resin used for the prepreg base material. The matrix resin used for the resin layer is preferably the same resin as the matrix resin used for the prepreg base material. The resin used for the resin layer may be a resin different from the matrix resin used for the prepreg base material.
When the material (A) is a prepreg laminated body, in the embodiment in which a plurality of prepreg base materials are laminated in the step (i), the fiber axial direction of the reinforcing fibers in the prepreg base material is the material (A) in the step (ii). ) May intersect with the traveling direction.
As a specific example of the laminating mode of the prepreg laminated body of the material (A), for example, a mode in which two or more prepreg base materials are aligned and laminated so that the fiber axes of the reinforcing fibers of each prepreg base material are aligned in the same direction. Can be mentioned. In the above aspect, since the directions of the fiber axes of the reinforcing fibers of each prepreg base material are aligned, the direction of the fiber shafts of the reinforcing fibers and the traveling direction of the material (A) intersect with each other in the step (ii). It is easy to control their angular relationship so that they do.

Further, the direction of the fiber axis of the reinforcing fiber may be deviated between the prepreg base materials forming the prepreg laminate. That is, when laminating a plurality of prepreg base materials, it is not always necessary to strictly control the angle of each prepreg base material so that the directions of the fiber axes of the reinforcing fibers of each prepreg base material are completely aligned.
Further, even if there is a deviation in the direction of the fiber axis of the reinforcing fiber between the laminated prepreg base materials, the direction of the fiber axis of the reinforcing fiber for the prepreg base material of 66% or more with respect to the number of laminated bodies in the prepreg laminated body. The deviation is preferably 40 ° or less, more preferably 10 ° or less. The smaller the deviation in the direction of the fiber axis of the reinforcing fiber between the prepreg base materials, the smaller the angular relationship between the traveling direction of the material (A) and the direction of the fiber axis of the reinforcing fiber of each prepreg base material in the step (ii). It becomes easy to control.

The number of laminated prepreg base materials in the prepreg laminated body of the material (A) is preferably 2 to 16, more preferably 4 to 12. When the number of laminated prepreg base materials is at least the lower limit, it is easy to obtain a fiber reinforced plastic having sufficient mechanical properties. When the number of laminated prepreg base materials is not more than the upper limit, the laminating work becomes easy and the productivity is excellent.

The material (A) preferably contains at least one mold release agent. If the material (A) contains at least one mold release agent, the cooled material (A) in the step (iii) is excellent in releasability from the pressurizing device, and the fiber reinforced plastic is used. It is possible to manufacture a fiber reinforced plastic having excellent releasability from a molding mold during molding. The release agent may be contained in the prepreg base material, a resin film containing the release agent may be arranged on the surface of the prepreg base material or between layers of the prepreg laminate, and the release agent may be in a particle or liquid state. May be added with. Since the release agent of the material (A) is dispersed in the step (ii), the dispersibility and arrangement of the release agent in the material (A) have little influence on the obtained fiber reinforced plastic.

The thickness of the material (A) is preferably 0.25 to 6.0 mm, more preferably 0.4 to 6.0 mm, still more preferably 0.5 to 4.0 mm. When the thickness of the material (A) is at least the lower limit, it is easy to obtain a fiber reinforced plastic having sufficient mechanical properties. If the thickness of the material (A) is not more than the upper limit, the direction of the fiber axis of the reinforcing fiber in the material (A) is more likely to be randomized by the pressurization in the step (ii), and the isotropic or anisotropic mechanical properties are likely to occur. It is easy to obtain fiber reinforced plastics whose properties are controlled and whose mechanical properties are less likely to vary.

{Step (ii)}
In the step (ii), the material (A) is pressed by using a pressurizing device capable of pressurizing the material (A) in the thickness direction so that the pressurization becomes substantially uniform over the direction orthogonal to the traveling direction of the material (A). While traveling in one direction, the pressure is applied while being heated to a temperature T equal to or higher than the melting point of the matrix resin or, if not having a melting point, the glass transition temperature or higher.
In the step (ii), the direction of the fiber axis of the reinforcing fiber in the material (A) intersects with the traveling direction of the material (A) during pressurization by the pressurizing device. As a result, the reinforcing fibers cut by the cut flow together with the matrix resin, and the direction of the fiber axis of the reinforcing fibers changes in various directions. As a result, the direction of the fiber axis of the reinforcing fiber in the material (A) is randomized. Further, by improving the dispersibility of the reinforcing fibers, it is possible to obtain a fiber-reinforced plastic in which the tan δ is controlled to be low and is within the above range. In addition, since the dispersibility of the release qualitative agent is also improved, a fiber reinforced plastic having excellent release qualitative properties can be obtained.
In the step (ii), the angle φ formed by the direction orthogonal to the traveling direction of the material (A) and the direction of the fiber axis of the reinforcing fiber in the material (A) is preferably −20 ° to 20 °, preferably −5 to 5 °. Is more preferable. As a result, the direction of the fiber axis of the reinforcing fiber is more likely to be randomized, and the dispersibility of the reinforcing fiber is further improved. In the step (ii) in the method for manufacturing a fiber reinforced plastic of the present invention, the angle φ formed by the fiber axis directions of all the reinforcing fibers is −20 ° to 20 ° with respect to the direction orthogonal to the traveling direction of the material (A). It is preferable to make it.
When the prepreg laminate is used as the material (A), the condition of the angle φ is satisfied with 66% or more of the reinforcing fibers in the prepreg base material with respect to the number of laminated prepreg laminates. May be good.

The angle θ formed by the direction orthogonal to the traveling direction of the material (A) and the direction of the fiber axis of the reinforcing fiber is the traveling of the material (A) when the material (A) is traveled and pressurized in the step (ii). It is an angle formed by the direction orthogonal to the direction and the direction of the fiber axis of the reinforcing fiber in the prepreg base material in the material (A). For the angle θ, the counterclockwise direction when the material (A) is viewed from above is positive, and the clockwise direction is negative.
When a pressurizing device provided with at least a pair of press rolls whose axial direction of the roll coincides with the direction orthogonal to the traveling direction of the material (A) is used as the pressurizing device in the step (ii), the angle θ is the press roll. It corresponds to the angle formed by the axial direction of the material (A) and the direction of the fiber axis of the reinforcing fiber in the prepreg base material in the material (A).
The preferable range of the temperature T in the step (ii) in the present invention is a temperature equal to or higher than the melting point of the matrix resin impregnated in the prepreg substrate, or higher than the glass transition temperature of the matrix resin when the matrix resin does not have a melting point. Is. When the material (A) contains two or more kinds of matrix resins, the temperature T is based on the highest temperature among the melting points or the glass transition temperatures of the matrix resins.
The temperature T varies depending on the type of the matrix resin, but is preferably 150 to 450 ° C., more preferably 200 to 400 ° C. within the range in which the matrix resin melts. When the temperature T is within the above range, it is easy to flow the reinforcing fiber together with the matrix resin, the isotropic property and anisotropy of the mechanical properties are controlled, and it is easy to obtain a fiber reinforced plastic with little variation in the mechanical properties.

In the step (ii) in the method for producing a fiber reinforced plastic of the present invention, the material (A) may be preheated before the material (A) is heated to the temperature T. When preheating is performed, the preferred range of the preheating temperature and the preheating method are preferably 150 to 400 ° C, more preferably 200 to 380 ° C. At the preheating stage, the matrix resin of the material (A) may or may not be melted.
The method for preheating the material (A) is not particularly limited, and examples thereof include a method using an IR heater, a circulating hot air oven, and the like.

The clearance between the belts directly under the roll at the point where the pressure is applied by the pair of press rolls is preferably 30 to 80%, more preferably 40 to 70% with respect to the thickness of the material (A). When the clearance between the belts is at least the lower limit value, it is easy to prevent the material (A) from being excessively crushed and greatly deformed, and it is easy to obtain a fiber reinforced plastic having a desired shape. When the clearance between the belts is not more than the upper limit value, the dispersibility of the reinforcing fibers is improved, the value of tan δ is small, and it is easy to obtain a fiber reinforced plastic having excellent mechanical properties. The clearance between the presses means the distance between the press surfaces that come into contact with the material (A) when the pressurization is applied. For example, when a double belt type heating and presser is used, the clearance between the presses is the distance between the belts. When the material (A) is directly pressed by a pair of press rolls, the clearance between the presses is the distance between the outer peripheral surfaces of the rolls.
The following can be considered as factors for improving the dispersibility of the reinforcing fibers by reducing the clearance between the belts at the point where the pressure is applied by the pair of press rolls. At the point where the pressure is applied by the pair of press rolls, the thickness of the material (A) is temporarily reduced at the portion sandwiched by the belt. At this time, in the vicinity of the belt in the thickness direction of the material (A), the flow velocities of the reinforcing fibers and the matrix resin follow the running of the belt and become about the same as the speed of the belt. On the other hand, the flow velocities of the reinforcing fibers and the matrix resin in the central portion of the material (A) in the thickness direction are pushed back by pressure immediately before the press roll and slowed down, and immediately after the press roll, they are pushed out by pressure and become faster. It is considered that the dispersibility of the reinforcing fibers is improved by the shearing force due to the difference in the flow velocity in the thickness direction in the material (A).
The time for pressurizing the material (A) is preferably 0.1 to 30 minutes, more preferably 0.5 to 10 minutes.

The traveling speed of the material (A) in the step (ii) is preferably 0.1 to 25 m / min, more preferably 0.2 to 20 m / min, and even more preferably 0.5 to 15 m / min. If the traveling speed of the material (A) is at least the lower limit, the productivity is high. When the traveling speed of the material (A) is not more than the upper limit value, it is easy to obtain a fiber reinforced plastic having excellent isotropic mechanical properties and little variation in mechanical properties.
By controlling the pressurization clearance, pressurization time, and temperature T of the material (A) in the step (ii), not only the mechanical properties of the obtained fiber reinforced plastic are made excellent in isotropic properties, but also the machine. The anisotropy of physical properties can be controlled as desired.
In the step (ii) of the present invention, the material (A) is traveled in one direction by a pressurizing device including at least a pair of press rolls in which the axial direction of the roll is orthogonal to the traveling direction of the material (A). The step (ii-1) of pressurizing while heating to the temperature T is preferable.

In the step (ii-1), as shown in FIG. 5, the axial direction of the pair of press rolls 10 coincides with the orthogonal direction X with respect to the traveling direction of the material (A). The material (A) 100 is run in one direction by the pair of press rolls 10 and pressed to a temperature T while being heated. At this time, the material (A) 100 is pressurized so that the direction Y of the fiber axis of the reinforcing fiber 110 in the material (A) 100 intersects the traveling direction of the material (A).
In the pair of press rolls, the axial directions of the upper and lower press rolls are the same.
As a method of heating the material (A) to the temperature T in the step (ii-1), a method of using a heating roll as a press roll and pressurizing the material (A) while heating is preferable.
If the material (A) can be heated to the temperature T only by heating it before pressurizing it with the press roll, use a press roll having no heating function. May be good. Further, when the material (A) can be heated to the temperature T only by the heating roll used as the press roll, preheating may not be performed.
In the step (ii-1), a pair of press rolls may be used in only one stage or in two or more stages. When two or more press rolls paired up and down are provided in the step (ii-1), the axial directions of all the press rolls are made to coincide with the orthogonal direction X with respect to the traveling direction of the material (A).
In the step (ii-1), the material (A) is sandwiched between at least a pair of belts and heated while running so as to pass between at least a pair of press rolls, and the material (A) is heated by the at least pair of press rolls. It is preferable to use a double belt type heating and pressurizing machine that pressurizes. In this case, it is preferable to dispose a release paper or a release film between the material (A) and the belt, or to perform a mold release treatment on the belt surface in advance. The material of the belt is not particularly limited, and a metal material is preferable in terms of heat resistance and durability.
The step (ii-1) is not limited to the mode performed by using the double belt type heating and pressurizing machine. For example, the material (A) may be pressed by a pair of press rolls while the strip-shaped material (A) is run without being sandwiched by a pair of belts. In this case, it is preferable that the clearance between the pair of press rolls is within the above range.
The step (ii) is not limited to the mode in which a pressurizing device including at least a pair of press rolls is used. For example, a pressurizing device for pressing with a flat surface and a press roll, a pressurizing device with a press machine for pressing with a flat surface and a flat surface, and a pressurizing device including a plurality of spherical presses may be used for pressurizing.

{Step (iii)}
In the step (iii), the material (A) pressurized by the pressurizing device in the step (iii) is cooled to obtain a fiber reinforced plastic. When the matrix resin is a thermoplastic resin, the temperature of the material (A) is lowered to below the melting point of the matrix resin or below the glass transition temperature to solidify the material (A) to obtain a fiber reinforced plastic.
When a prepreg laminate is used as the material (A), the obtained fiber-reinforced plastic is in the form of a sheet in which the prepreg base materials are adhered to each other and integrated. Therefore, even when the prepreg laminate is used, the obtained fiber reinforced plastic is easy to handle.
The method for cooling the material (A) is not particularly limited, and examples thereof include a method using a hot water roll. A method of cooling by allowing the material (A) to cool may be adopted.
The cooling time is preferably 0.5 to 30 minutes.

[Example of Embodiment]
Hereinafter, as an example of the embodiment of the step (iii-1) and the step (iii), an example using the double belt type heating and pressurizing machine 1 (hereinafter, simply referred to as heating and pressurizing machine 1) illustrated in FIG. 6 will be described. .. The mode in which the step (ii) and the step (iii) are carried out is not limited to the mode in which the heating and pressurizing machine 1 is used.
The heating and pressurizing machine 1 includes a pair of belts 12 for running the strip-shaped material (A) 100 in one direction while sandwiching the material (A) 100 from above and below, a pair of IR heaters 14 for preheating the material (A) 100, and a preheated material. (A) A pair of press rolls 10 that sandwich and pressurize 100 from above and below are in three stages, and a pair of hot water rolls 16 that sandwich and cool the material (A) 100 pressed by the press roll 10 from above and below are in three stages. It has a take-up roll 18 for winding up the fiber-reinforced plastic 120 which has been cooled and solidified.
The pair of press rolls 10 pressurize the material (A) 100 while rotating in a direction in which the material (A) 100 passing between them is sent out to the downstream side. In the heating and pressurizing machine 1, the axial direction of the pair of press rolls 10 coincides with the orthogonal direction X with respect to the traveling direction of the supplied material (A) 100. The pair of hot water rolls cool the material (A) 100 while rotating in the direction of sending the material (A) 100 passing between them to the downstream side.

The pair of belts 12 are mounted by being hung on a drive roll 20 provided on the upstream side of the IR heater 14 and a driven roll 22 provided on the downstream side of the hot water roll 16, respectively, and are rotated by the drive roll 20. Be moved. The material (A) 100 runs by rotating the pair of belts 12 in a state of sandwiching the material (A) 100.
In the embodiment using the heating and pressurizing machine 1, as the step (ii-1), the strip-shaped material (is so that the direction of the fiber axis of the reinforcing fiber in the material (A) 100 intersects with the traveling direction of the material (A) 100. A) 100 is continuously supplied to the heating and pressurizing machine 1. Specifically, the strip-shaped material (A) 100 in which the directions of the fiber axes of the reinforcing fibers intersect with respect to the length direction is continuously supplied to the heating and pressurizing machine 1 in the length direction.
In the heating and pressurizing machine 1, the material (A) 100 is preheated by the IR heater 14 while being run so as to pass between the pair of press rolls 10 in a state of being sandwiched between the pair of belts 12, and the material (A) is used by the press roll 10. A) Pressurize 100 in a state of being heated to a temperature T. As a result, the matrix resin and the reinforcing fibers flow in the material (A) 100, the direction of the fiber axis of the reinforcing fibers is randomized, and the dispersibility of the reinforcing fibers is improved. In this example, it is preferable that the clearance between the belts is within the above range at each of the points where the material (A) 100 is pressed by each pair of press rolls 10 arranged in three stages.
Further, in this example, it is preferable to use a heating roll as the press roll 10 to heat the material (A) 100 to the temperature T and pressurize it at the same time. If the material (A) 100 can be pressurized by the press roll 10 while the material (A) 100 is heated to the temperature T only by preheating with the IR heater 14, the material (A) 100 is pressed without being heated by the press roll 10. Only may be done.
Next, as a step (iii), the material (A) 100 pressurized by the press roll 10 is run so as to pass between the pair of hot water rolls 16 while being sandwiched between the pair of belts 12 and hot water. By cooling with a roll 16, a strip-shaped fiber reinforced plastic 120 is obtained.

The obtained fiber reinforced plastic 120 is taken off from the pair of belts 12 on the downstream side of the driven roll 22 and then wound on the take-up roll 18 via the guide roll 24.
A double belt type heating / pressurizing machine such as the heating / pressurizing machine 1 is advantageous in that a series of steps from heating and pressurizing the material (A) to cooling can be easily performed.
The fiber-reinforced plastic of the present invention described above contains a mold release agent, and tanδ (ave) and tanδ (max) -tanδ (ave) are controlled in a specific range, so that the mold release property is excellent. In addition, both excellent mechanical properties and excellent fluidity at the time of shaping can be achieved.

Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited to the following description.
[Measurement of viscoelastic property (tanδ)]
A disk having a diameter of 25 mm was cut out from the fiber reinforced plastic obtained in each example with a water jet cutter and used as a test piece.
As a test device, a leometer manufactured by TA Instruments (product name "AR-G2") was used. Two upper and lower parallel plates made of aluminum with a diameter of 25 mm were attached, and mapping was performed to remove the residual torque. By performing this "mapping", accurate measurement becomes possible. After adjusting the parallel plate gap to 0 points at the melting point of the matrix resin of the test piece (165 ° C when the matrix resin is polypropylene, 225 ° C when nylon 6), on the lower plate of the upper and lower parallel plates. The specimen was set and the upper plate was lowered to the position where the entire surface was in contact with the specimen. The gap (clearance) between the upper and lower parallel plates at this time was taken as the test piece thickness at the time of measurement. While keeping the clearance constant, at a temperature 30 ° C lower than the melting point, which is the measurement start temperature (135 ° C when the matrix resin is polypropylene, 195 ° C when nylon 6), two parallel sheets are placed under the following measurement conditions. A test piece was sandwiched between plates and a constant strain was applied, and the response at that time, the storage elastic modulus G'and the loss elastic modulus G', was recorded. The value obtained by dividing the loss elastic modulus G'' by the storage elastic modulus G'was defined as tan δ.
(Measurement condition)
Frequency: 1Hz,
Distortion: 0.1%,
Measurement temperature range: 30 ° C lower than the melting point of the matrix resin to 10 ° C higher than the melting point of the matrix resin (135 ° C to 175 ° C when the matrix resin is polypropylene, 195 to 235 when the matrix resin is nylon 6) ℃)
Temperature rise rate: 2 ° C / min,
Measurement point: Every 30 seconds (every 1 ° C).
[Liquidity at the time of shaping]
The fluidity of the fiber-reinforced plastic obtained in each example at the time of shaping was evaluated by the following method.
From the obtained fiber reinforced plastic, a plate-like material having a length of 78 mm and a width of 78 mm was cut out. When the matrix resin is polypropylene, heat it at 230 ° C for 10 minutes using a mini test press (manufactured by Toyo Seiki Co., Ltd., product name: MP-2FH) by stacking the plates to a thickness of about 4 mm, and then 145 ° C. It was pressed for 60 seconds under the condition of 5 MPa. When the matrix resin was nylon 6, it was heated at 290 ° C. for 10 minutes and then pressed at 200 ° C. and 5 MPa for 60 seconds. The initial thickness h _A (mm) before press molding and the final thickness h _B (mm) after press molding were measured, and the fluidity was evaluated by the ratio h _A / h _B obtained by dividing the initial thickness by the final thickness. In addition, there is a phenomenon called springback in which the thickness of the fiber reinforced plastic increases due to the residual stress of the reinforced fiber due to the softening of the matrix resin of the fiber reinforced plastic. If the fiber-reinforced plastic spring-backed by heating could not be pressed to the initial thickness _hA (mm) by press molding under the above conditions, it was recorded as x.

[Bending physical properties]
<Measurement of bending strength, coefficient of variation (CV value), and bending strength retention rate at 80 ° C>
The fiber reinforced plastics obtained in each example were cut into 300 mm squares and laminated in the same direction (so that the directions of MD, TD, etc. were the same at the time of laminating) by a thickness of 2 mm. The laminate is placed in a 300 mm square and 15 mm deep stamp die, heated to 200 ° C when the matrix resin is polypropylene, and 250 ° C when the matrix resin is nylon 6, and then a multi-stage press machine (Kondo). In a compression molding machine manufactured by Metal Industry Co., Ltd., product name: SFA-50HH0), when the matrix resin is polypropylene, it is 200 ° C., and when the matrix resin is nylon 6, it is 250 ° C. It was heated and pressurized for 1 minute. Then, the mixture was cooled to room temperature at the same pressure to obtain a plate-shaped fiber-reinforced plastic plate having a thickness of 2 mm. A bending test piece having a length of 100 mm and a width of 25 mm was cut out from the obtained fiber-reinforced plastic plate with a wet cutter, and a three-point bending test was performed according to the test method specified in JIS K7074 to measure the bending strength. At this time, the longitudinal direction of the bending test piece coincides with the MD direction (direction of 90 ° with respect to the axial direction of the roll) at the time of manufacturing the fiber reinforced plastic, and the one coincides with the TD direction (axial direction of the roll). Six of each were prepared, a total of 12 tests were performed, and the average value was recorded as the bending strength. As the testing machine, the Instron universal testing machine 4465 type was used. The test was also carried out at room temperature (23 ° C) and 80 ° C. Furthermore, the coefficient of variation (CV value, unit:%), which is an index of variation, is calculated by calculating the standard deviation from the measured value of the bending strength at room temperature (23 ° C) and dividing the standard deviation by the average value. bottom.
The ratio σ _{80 ° C} / σ _RT (unit:%) was calculated as the 80 ° C. bending strength retention rate. However, σ _{80 ° C} is the bending strength measured at 80 ° C. σ _RT is the bending strength measured at room temperature.
For Comparative Examples 5 to 7 having no clear MD direction and TD direction at the time of manufacture, an arbitrary direction was set as the MD direction, and a direction orthogonal to that direction was evaluated as the TD direction.

[Evaluation of releasability]
The releasability of the fiber reinforced plastic obtained in each example was evaluated by the following method.
The fiber reinforced plastic obtained in each example was cut into 180 mm squares, and these were laminated in the same direction (so that the directions of MD, TD, etc. were the same at the time of laminating) for a thickness of 6 mm, and 125 ° C. was higher than the melting point of the matrix resin. Put it in a far-infrared heater type heating device (manufactured by NGK Kilntech Co., Ltd., product name: H7GS-71289) set at a high temperature (290 ° C when the matrix resin is polypropylene, 350 ° C when the matrix resin is nylon 6). And heated for 5 minutes. Using a 300t press machine (manufactured by Kawasaki Hydromechanics Co., Ltd.) equipped with a 310 mm square and 40 mm deep stamping die (lower mold is concave, upper mold is convex), the mold temperature is 90 ° C and the molding pressure is 18 MPa. The fiber-reinforced plastic in which the resin was melted by heating was charged in the center of the lower die of the mold and pressed for 1 minute to obtain a stamping molded product having a size of 310 mm and a thickness of 2 mm. The surface of the mold was pressed without performing a mold release treatment such as application of a mold release agent. In addition, the time from when the fiber reinforced plastic was taken out from the far-infrared heater type heating device to when it was pressed was 25 seconds. After opening the upper and lower dies attached to the press machine, the stamping molded product was removed from the dies by the protrusion of the ejector pin. At this time, if the ejector pin broke and penetrated the stamping molded product and could not be removed from the mold, it could be removed by the protrusion of the ejector pin, but a part of the stamping molded product was peeled off and remained on the mold surface. If it was, it was recorded as △, and if it could be removed without any problem, it was recorded as ○.

[Evaluation of pf and ec]
According to the above-mentioned pf measuring method and ec measuring method, pf and ec were measured, respectively. For the X-ray diffraction measurement, an X-ray diffractometer equipped with a fiber sample table (TTR-III manufactured by Rigaku Co., Ltd.) was used, the measurement sample was placed on the table, and the target was Cu. Specifically, while irradiating X-rays from above the measurement sample, the measurement sample is rotated about its thickness direction, and the diffracted X-rays are emitted by a detector arranged at a diffraction angle of 2θ = 24.5 °. I took it in. As a standard sample, a sample having a Vf of 35% by volume was used.

[Evaluation of dp]
A 3 cm square sample piece was cut out from a fiber reinforced plastic and embedded in Technobit 4000 manufactured by kulzer. After the technobit 4000 was cured, it was polished and mirror-treated so that the cross section of the sample piece was exposed.
Next, a cross-sectional photograph of the sample piece was taken under the following conditions.
(Shooting conditions)
Equipment: Olympus Industrial Optical Microscope BX51M
Lens magnification: 500x Shooting dot pitch: 0.17μm
In the obtained cross-sectional photograph, the portion corresponding to the range (0.5 mm in the direction orthogonal to the thickness direction × the thickness direction) in the cross section of the sample piece was used as the processing target image. Using Softfair Win-Loof as image editing software, dp was calculated according to the above-mentioned dp measurement method. The calculation of dp was performed at 5 points in the cross section of each sample piece, and the average value was obtained.

[Production Example 1: Production of prepreg base material A]
100 parts by mass of polyamide 6 resin (UBE nylon manufactured by Ube Kosan Co., Ltd., product number: 1013B, specific gravity 1.14) as a release agent, a partially saponified montanic acid (Luwas OP manufactured by BASF, calcium montanate and montanoic acid ester). (Oxidation value 7 to 14 mgKOH / g, saponification value 110 to 130 mgKOH / g) was premixed with 0.2 parts by mass, and then a film having a grain size of 48 g / m ² was prepared by using an extruder and a T-die. bottom.
Carbon fiber (Pyrofil CF toe manufactured by Mitsubishi Rayon, product number: TR 50S15L, carbon fiber diameter 7 μm, number of filaments: 15,000, toe grain: 1.0 g / m, specific gravity 1.82) in one direction and flat The fiber sheets were arranged in a shape and had a grain size of 75 g / m ² .
The fiber sheet is sandwiched between the films from both sides, heated and pressurized by passing the calendar roll multiple times, the fiber sheet is impregnated with the resin, the fiber volume content (Vf) is 33% by volume, and the grain is 170 g / m ² . , A prepreg base material A having a theoretical thickness of 125 μmm was prepared.

[Manufacturing Example 2: Production of prepreg base material B]
A prepreg base material B was produced in the same manner as in Production Example 1 except that a film made of only a polyamide 6 resin (UBE nylon manufactured by Ube Kosan Co., Ltd., product number: 1013B, specific density 1.14) was produced. This prepreg base material has a fiber volume content (Vf) of 33% by volume, a basis weight of 170 g / m ² , and a theoretical thickness of 125 μmm. The prepreg base material B does not contain a mold release agent.

[Manufacturing Example 3: Production of prepreg base material C]
A prepreg similar to Production Example 1 except that a film having a grain size of 38 g / m ² consisting of only an acid-modified polypropylene resin (modic manufactured by Mitsubishi Chemical Corporation, product number: P958V, MFR: 50, specific density 0.91) was produced. The base material C was prepared. This prepreg base material has a fiber volume content (Vf) of 33% by volume, a basis weight of 151 g / m ² , and a theoretical thickness of 125 μmm. The prepreg base material C does not contain a mold release agent.

[Manufacturing Example 4: Production of prepreg base material D]
A prepreg base material D was produced in the same manner as in Production Example 3 except that the basis weight of the film was 29 g / m ² and the basis weight of the fiber sheet was 110 g / m ² . This prepreg base material has a fiber volume content (Vf) of 49% by volume, a basis weight of 167 g / m ² , and a theoretical thickness of 123 μmm. The prepreg base material D does not contain a mold release agent.

[Example 1]
From the prepreg base material A obtained in Production Example 1, a rectangular prepreg base material having a size of 300 mm (0 ° direction with respect to the fiber axis) × 900 mm (90 ° direction with respect to the fiber axis) was cut out. Using a cutting plotter (L-2500 cutting plotter manufactured by Rezac), a notch having a depth for cutting the reinforcing fiber was made in the prepreg base material to obtain a notched prepreg base material. In the cutting process, as shown in FIG. 5, a region (B) in which a plurality of cuts (b) in which the angle θ between the fiber axis of the reinforcing fiber and the cut is + 45 ° is formed in a row in the fiber axis direction of the reinforcing fiber. And the region (C) in which a plurality of cuts (c) having an angle θ of −45 ° are formed in a row in the fiber axis direction of the reinforcing fiber are alternately formed in a direction orthogonal to the fiber axis of the reinforcing fiber. It was carried out as follows. The angle θ was set to be positive counterclockwise with respect to the fiber axis of the reinforcing fiber in a plan view. The fiber length of the reinforcing fiber divided by the notch was 25 mm.
Four of the notched prepreg base materials were laminated so that the fiber axes of the reinforcing fibers were in the same direction to obtain a prepreg laminate. The thickness of the prepreg laminate was 0.5 mm.
The double-belt type heating and presser illustrated in FIG. 6 in which the upper and lower belts are driven at 0.8 m / min is used with the reinforcing fibers in the prepreg laminate in the direction orthogonal to the traveling direction of the prepreg laminate (the axial direction of the press roll). A plurality of prepreg laminates were continuously charged so that the angle φ formed by the fiber axis direction of the above was 0 ° and there was no gap before and after each prepreg laminate. In the double belt type heating and pressurizing machine, the prepreg laminate is heated by a two-stage press roll under the conditions of a roll temperature of 380 ° C. and a clearance of 300 μm between belts directly under the roll to melt the thermoplastic resin. bottom. Then, it was passed through a 1.5 m cooling section equipped with a one-stage hot water roll under the conditions of a roll temperature of 30 ° C. and a belt-to-belt clearance of 300 μm directly under the roll, and the thermoplastic resin was solidified to obtain a fiber reinforced plastic. The apparent running speed of the prepreg laminated body is the same as the driving speed of the belt.
The thickness of the obtained fiber-reinforced plastic was 0.5 mm, and the basis weight was 680 g / m ² .

[Example 2]
A fiber-reinforced plastic was obtained in the same manner as in Example 1 except that the clearance between the belts directly under the roll during heating and cooling was set to 400 μm. The thickness of the obtained fiber-reinforced plastic was 0.5 mm, and the basis weight was 680 g / m ² .

[Comparative Example 1]
A fiber-reinforced plastic was obtained in the same manner as in Example 1 except that the prepreg base material B obtained in Production Example 2 was used. The thickness of the obtained fiber-reinforced plastic was 0.5 mm, and the basis weight was 680 g / m ² .

[Comparative Example 2]
Using the prepreg base material C obtained in Production Example 3, the fiber reinforced plastic is the same as in Example 1 except that the roll temperature during heating and pressurization is 270 ° C. and the belt driving speed is 1.0 m / min. Got The thickness of the obtained fiber-reinforced plastic was 0.5 mm, and the basis weight was 600 g / m ² .

[Comparative Example 3]
Using the prepreg base material D obtained in Production Example 4, a fiber reinforced plastic was obtained in the same manner as in Comparative Example 2 except that the belt driving speed was set to 0.5 m / min. The thickness of the obtained fiber-reinforced plastic was 0.5 mm, and the basis weight was 670 g / m ² .

[Comparative Example 4]
In Comparative Example 4, a fiber-reinforced plastic is produced by the above method (I).
A 300 mm square prepreg base material is cut out from the prepreg base material C obtained in Production Example 3, and a cutting plotter (manufactured by Rezac Co., Ltd., product name: L-2500) is used to make linear cuts at regular intervals. An intricate prepreg substrate was obtained. In the notch processing, the fiber length of the carbon fiber is 25.0 mm, the notch length is 20.0 mm, and the angle between the fiber axis of the reinforcing fiber and the notch is in the part inside the 5 mm portion from the peripheral edge of the prepreg base material. All θ was applied so as to be + 45 °. The fiber direction of each notched prepreg base material is 0 ° / 45 ° / 90 ° / -45 ° / -45 ° / 90 ° / 45 ° / 0 ° from the top of the 16 notched prepreg base materials. The layers were laminated so as to be / 0 ° / 45 ° / 90 ° / −45 ° / −45 ° / 90 ° / 45 ° / 0 °. Pseudo-isotropic ([0/45/90 / -45] s2) prepregs are made by spot welding the laminated notched prepreg base materials with an ultrasonic welder (manufactured by Nippon Emerson, product name: 2000LPt). A laminate was produced.
The prepreg laminate is placed in a 300 mm square and 15 mm deep inro die, heated to 200 ° C., and then placed in a multi-stage press (compression molding machine manufactured by Kondo Metal Industry Co., Ltd., product name: SFA-50HH0). It was heated and pressurized at a pressure of 0.1 MPa for 2 minutes on a board surface at 200 ° C. Then, the laminate was cooled to room temperature under the same pressure to obtain a plate-shaped fiber-reinforced plastic having a thickness of 2 mm.

[Comparative Example 5]
In Comparative Example 5, a fiber-reinforced plastic is produced by the above method (II).
The prepreg base material D obtained in Production Example 4 was slit into a strip having a width of 15.0 mm and then continuously cut into a length of 25.0 mm using a guillotine-type cutting machine to have a fiber length of 25. A 0 mm chopped strand prepreg was obtained. 244 g of the obtained chopped strand prepreg was weighed and freely dropped one by one from a height of 30 cm into a 300 mm square and 15 mm deep inro mold, and laminated so that the fiber orientation was random. ..
After heating the inro die on which the chopped strand prepreg is laminated to 200 ° C, a multi-stage press machine (compression molding machine manufactured by Kondo Metal Industry Co., Ltd., product name: SFA-50HH0) is used to control the pressure of 0.1 MPa on the board surface at 200 ° C. It was heated and pressurized with pressure for 2 minutes. Then, the laminate was cooled to room temperature under the same pressure to obtain a plate-shaped fiber-reinforced plastic having a thickness of 2 mm.

[Comparative Example 6]
In Comparative Example 6, a fiber reinforced plastic is produced by the above method (III).
A carbon fiber (Pyrofil TR 50S manufactured by Mitsubishi Rayon) was cut to 6 mm using a rotary cutter to obtain chopped carbon fiber. Similarly, a fiber made of an acid-modified polypropylene resin (Modic P958V, MFR50 manufactured by Mitsubishi Chemical Corporation) was cut to 3 mm to obtain a chopped polypropylene fiber. 0.74 kg of chopped polypropylene fiber was added to 110 kg of a polyethylene oxide aqueous solution having a mass concentration of 0.12%, and the mixture was sufficiently stirred using a stirrer. Subsequently, 0.37 kg of chopped carbon fiber was added and stirred for 10 seconds to obtain a dispersion liquid. The obtained dispersion is poured into a 100 cm square mesh frame, the polyethylene oxide aqueous solution is filtered, and then the water content is completely removed in a dryer at 120 ° C., and the fiber volume content is 20% by mass (fiber mass content 33 mass). %) To obtain a prepreg substrate having a grain size of 1.11 kg / m ² . The obtained prepreg base material was cut into 30 cm squares and two layers were stacked to obtain a prepreg laminate. The prepreg laminate was placed in a 300 mm square and 15 mm deep inro die, heated to 200 ° C, and then placed in a multi-stage press (compression molding machine manufactured by Kondo Metal Industry Co., Ltd., product name: SFA-50HH0). It was heated and pressurized at a pressure of 0.1 MPa for 2 minutes on a board surface at 200 ° C. Then, the prepreg laminate was cooled to room temperature under the same pressure to obtain a plate-shaped fiber-reinforced plastic having a thickness of 2 mm.

The evaluation results of each example are shown in Table 2.
In addition, "DBP randomization" in Table 1 means a method of randomizing the fiber axial direction of a reinforcing fiber by pressurizing with a double belt type heating and pressurizing machine.

11: Double belt type heating and pressurizing machine 12, 12A: Prepreg base material 13: Reinforcing fiber 14: Matrix resin 15: Notch (b)
16: Notch (c)
17, 17A: Area (B)
18, 18A: Region (C)
110: Press roll 112: Belt 114: IR heater 116: Hot water roll 118: Winding roll 120: Drive roll 122: Driven roll 124: Guide roll 1100: Material (A)
1110: Reinforcing fiber 1120: Fiber reinforced plastic X: Direction perpendicular to the traveling direction of the material (A) Y: Fiber axis direction of the reinforcing fiber

Claims (5)

A fiber reinforced plastic containing reinforced fibers and matrix resin , which is formed from a prepreg base material .
Contains at least one mold release agent,
The following formula of the fiber-reinforced plastic in the temperature range of T-30 (° C.) to T-10 (° C.) (where T is the melting point of the matrix resin or the glass transition temperature when it does not have a melting point). The average value of the viscoelastic property tanδ represented by (1) is tanδ (ave), and the maximum value of the viscoelastic property tanδ in the temperature range of T-10 (° C.) to T + 10 (° C.) is tanδ (max). A fiber-reinforced plastic having a tan δ (ave) of 0.01 to 0.25 and a tan δ (max) -tan δ (ave) of 0.15 or more.
tanδ = G'' / G'・ ・ ・ (1)
However, the symbols in the formula (1) have the following meanings.
G'': Loss elastic modulus,
G': Storage elastic modulus. The fiber-reinforced plastic according to claim 1, wherein the reinforcing fiber contains carbon fiber, and the average fiber length of the carbon fiber is 1 to 100 mm. The fiber-reinforced plastic according to claim 1 or 2, wherein the release agent is a higher fatty acid ester and / or a higher fatty acid salt. The fiber-reinforced plastic according to any one of claims 1 to 3, wherein the mold release agent contains calcium montanate and a montanic acid ester. At least one type of heat selected from the group in which the matrix resin consists of a polyamide resin, a polyolefin resin, a modified polyolefin resin, a polyester resin, a polycarbonate resin, a polyether sulfone resin, a polyether ether ketone resin, a polyetherimide resin, and a polyphenylene sulfide resin. The fiber-reinforced plastic according to any one of claims 1 to 4, which comprises a plastic resin.

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