JP2013249441A - Preform and fiber-reinforced resin molding using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a preform with a quick molding cycle time, and excellent in conveyability and handleability.SOLUTION: A preform is produced by preparing a laminate composed of at least three layers of a reinforcing fibrous substrate attached on the surface of which a binder is attached in advance; heating the laminate to melt the binder to adhere the interlayer of the reinforcing substrates. The preform is characterized in that, the amount of binder to be attached on the surface of the reinforcing fibrous substrate is increased, where interlayer temperature distribution in the laminating direction of the laminate is relatively lower on heating.

Description

  The present invention relates to a preform that makes a reinforcing fiber substrate into a desired form.

  When manufacturing fiber reinforced plastic (Fiber Reinforced Plastics, hereinafter referred to as FRP), when a reinforcing fiber is to be arranged in a specific direction with respect to a complicated shape, a preform formed with a reinforcing fiber in advance is formed. Various methods for impregnating the resin have been studied. As a method of manufacturing a preform, a plurality of sheet-like reinforcing fiber base materials are laminated, a binder is adhered between the base materials, and the plurality of reinforcing fiber base materials are fixed with a binder in a state of being deformed into a desired shape. And the like.

  In the conventional preform, the adhesion amount of the binder between the respective layers of the preform is constant, or the adhesion amount is large only in the layer facing the reinforcing fiber substrate adhered on one side. In addition, since the lamination order of the reinforcing fiber bases is generally laminated symmetrically within the preform, the amount of binder attached between the layers in the center of the preform tends to increase.

  When the molding cycle time of the preform is long, sufficient time can be secured for the heat welding process, that is, heat transfer between the layers of the preform, so that a sufficiently fixed state can be obtained even if the binder adhesion amount is constant between the layers. It was. When trying to shorten the molding cycle time, it may shift to the next molding cycle without sufficient heat transfer to the layers far from the mold that is the heat source, resulting in temperature distribution between the preform layers and insufficient adhesion. As a result, there have been problems that the handling property when the preform is conveyed is deteriorated and the appearance is deteriorated due to the deformation of the preform after demolding.

  In addition, when the volume content (%) (hereinafter abbreviated as Vf) of the reinforcing fiber base is low, the contact area between the reinforcing fiber bases is reduced, and the heat transfer during molding is significantly deteriorated. For this reason, in order to sufficiently transfer heat to each layer, it is necessary to lengthen the heating time or raise the heating temperature, which is economically inefficient. On the other hand, increasing the amount of binder attached can improve the adhesion, but increasing the amount of binder in all layers makes it difficult to impregnate the matrix resin during resin injection molding (resin transfer molding: hereinafter abbreviated as RTM). Thus, there has been a problem that an unimpregnated portion is generated or the impregnation time is increased.

  Also, a method for producing a binder for molding a preform and its composition have been proposed (see Patent Document 1), and in order to achieve both good appearance of a molded product and matrix resin impregnation in RTM molding, only the outermost layer has a binder amount. There is an example (see Patent Document 2) that increases the number, but neither of them considers shortening of the molding cycle time of the preform.

JP 2007-269971 A JP 2011-202065 A

  As described above, although it is known that the adhesive strength changes depending on the heating temperature and the heating time, and the adhesive strength changes according to the amount of binder attached, it is possible to reduce the molding cycle time. The reform structure is not disclosed. In addition, there is no description on how to adjust the adhesion amount of the binder with respect to the configuration of the shaping mold (with or without a heating device, etc.) and the temperature distribution inside the shaping mold.

  Accordingly, an object of the present invention is to obtain a preform exhibiting a sufficient fixing force in a short molding cycle time and having good matrix resin impregnation properties.

In order to achieve the above object, the preform in the present invention employs the following configuration.
(1) A preform obtained by laminating at least three layers of reinforcing fiber bases having a binder attached to the surface in advance, and a preform in which the layers of the reinforcing fiber bases are adhered by melting the binder by heating, A preform characterized in that the amount of binder attached to the surface of a reinforcing fiber substrate having a relatively low temperature distribution between layers in the stacking direction of the laminate during heating is increased.
(2) The preform according to (1), wherein the laminate is laminated in one or a plurality of divided molds, and the mold is heated to melt the binder.
(3) The laminate disposed between the molds heated from both sides is characterized in that the amount of binder attached to the reinforcing fiber base disposed in the approximate center in the stacking direction of the laminate is maximized (2 Preform described in).
(4) The reinforcing fiber base material having a binder attached on one side thereof was laminated with the binder attached surface facing substantially the center in the stacking direction of the laminate, and was laminated so that the binder attached surface was opposed to the substantially center. The preform as described in (3) characterized by the above.
(5) In the laminate disposed in the mold heated from one side, the preform is heated, and the binder adhesion amount of the reinforcing fiber base most distant from the mold surface to be heated is maximized. The preform as described in (2) characterized by the above.
(6) Reinforcing fiber base material with a binder attached on one side is laminated so as to be a binder attaching surface on the opposite side of the mold surface to be heated, and the binder attaching surface of the reinforcing fiber base furthest away from the heating surface is heated. (5) The substrate preform is characterized by being laminated toward the mold surface side.
(7) The preform according to any one of (1) to (6), wherein the porosity of the preform is 50% or more.
(8) Any one of (2) to (7), wherein the mold is heated to 10 ° C. or more from the glass transition temperature of the binder and then demolded after the mold is cooled to the glass transition temperature or less of the binder. The preform described in 1.
(9) The preform according to any one of (1) to (8), wherein a reinforcing fiber base made of carbon fiber is laminated.
(10) The preform according to any one of (1) to (9), wherein the reinforcing fiber has a tensile strength of 3000 MPa or more and a tensile modulus of 200 GPa or more.
(11) The preform according to any one of (1) to (10), wherein the reinforcing fiber substrate is a woven fabric.
(12) The preform according to any one of (1) to (11), wherein the adhesion amount of the binder is 3 g / m ² to 20 g / m ² .
(13) The preform according to any one of (1) to (12), wherein the binder has a glass transition temperature of 40 ° C to 95 ° C.
(14) The preform according to any one of (1) to (13), wherein the binder is attached to the reinforcing fiber substrate in a dotted, linear, or discontinuous linear form.
(15) The preform according to any one of (1) to (14), wherein the peel strength is 10 N / m or more.
(16) A fiber reinforced resin molded article obtained by impregnating the preform according to any one of (1) to (15) with a matrix resin and curing the preform.

  According to the present invention, it is possible to obtain a preform that exhibits a sufficient fixing force with a short molding cycle time and that has a good impregnation property with a matrix resin.

It is explanatory drawing which shows the temperature distribution between lamination | stacking at the time of heating only the single side | surface of the laminated body by this invention, and the adhesion amount of a binder. It is explanatory drawing which shows the temperature distribution between lamination | stacking at the time of heating both surfaces of the laminated body by this invention, and the adhesion amount of a binder. It is the figure which laminated | stacked the reinforcing fiber base material which adhered the same amount of the binder when only the single side | surface of the laminated body by this invention was heated, and made the binder adhesion surface oppose only the reinforcing fiber base material furthest away from the heating surface. It is the figure which laminated | stacked the reinforcing fiber base material which made the binder adhere the same amount when both surfaces of the laminated body by this invention were heated, and faced the binder adhesion surface toward the center between heating dies. It is a figure which shows the preform which shape | molded the laminated body with the heating type | mold by this invention.

  Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the drawings.

  FIG. 1 shows a shaped state of a laminated body 5 in which a large number of reinforcing fiber base materials 2 each having a binder 1 attached on one side are laminated between a heating mold 3 and a pressing mold 4. The laminate 5 of the present invention is obtained by laminating three or more reinforcing fiber substrates 2. The present invention is characterized in that the adhesion amount of the binder is changed in accordance with the temperature distribution difference between the laminations, and when the number of the reinforcing fiber bases is less than 3, the temperature distribution difference between the laminations cannot occur. Therefore, it is excluded from the scope of the present invention. The reinforcing fiber base material 2 has a binder 1 attached to at least one surface, and the laminated body in which three or more reinforcing fiber base materials 2 are laminated is heated to fix the reinforcing fiber base material 2 with the binder 1. Thus, the preform 6 is obtained. Further, when the laminate is preliminarily shaped into a desired shape at the time of heating, a fiber reinforced plastic having a curved surface or a complicated uneven shape can be obtained.

  Here, the laminate 5 of the present invention is characterized in that the adhesion amount of the binder 1 between layers is increased as the distance from the heating surface of the heating mold 3 (the surface on which the laminate 5 is placed) is increased. This is because the reinforcing fiber base 2 disposed near the heating surface side of the heating die 3 is sufficiently heated even with a small amount of the binder 1, and the interlayer can be sufficiently fixed by the binder 1. In this state, since voids other than the binder 1 are sufficiently formed between the layers, it is possible to spread to every corner without deteriorating the impregnation property even when impregnating the matrix resin described later. Pinholes generated due to insufficient impregnation can be suppressed.

  On the other hand, the reinforcing fiber base material 2 away from the heating surface of the heating mold 3 increases the adhesion amount of the binder 1 even if it is difficult to be heated by increasing the adhesion amount of the binder 1, and the adhesion failure of the binder 1. Further, it is possible to prevent the substrate from being twisted when the preform 6 is conveyed.

Specifically, the adhesion amount of the binder 1 of the reinforcing fiber substrate 2 close to the heating surface is preferably 3 to 7 g / ^{m 2,} more preferably from 3 to 5 g / ^{m 2.} The adhesion amount of the binder 1 of the reinforcing fiber base 2 that is farthest from the heating surface is preferably 15 to 20 g / m ² , more preferably 15 to 18 g / m ² . The adhesion amount of the binder 1 of the reinforcing fiber substrate 2 between the reinforcing fiber substrate 2 close to the heating surface and the reinforcing fiber substrate 2 farthest from the heating surface is preferably 7 to 15 g / m ² , more preferably. It is preferable that the amount of the binder 1 is gradually increased as the distance from the heating surface of the heating die 3 is increased to 8 to 14 g / m ² .

In addition, the difference in adhesion amount of the binder 1 of the stacked reinforced adjacent fiber substrate 2 is preferably in the range of 4~9g / ^{m 2,} more preferably from 4~7g / ^{m 2.}

  When the amount of the binder 1 attached to the reinforcing fiber base 2 of each layer is out of the above range, when the amount of the binder 1 attached is small, the adhesion between the layers is lowered, and when the amount is large, the matrix resin is not easily impregnated. is there.

  Although FIG. 1 shows a mode in which only one mold is a heating mold 3 and the binder 1 is attached only to one side of the reinforcing fiber base 2, the present invention has various combinations other than this. Can be applied.

  FIG. 2 shows a shortening of the molding time by arranging heating dies 3 on the upper and lower sides and heating them from both sides. In this case, the stacking order of the laminated body 5 in which a large number of the reinforcing fiber bases 2 having the binder 1 attached on one side is laminated is such that the adhesion amount of the binder 1 between the laminated reinforcing fiber bases 2 is close to the center of the laminated body. It is characterized by increasing with time.

  In FIG. 3, as in FIG. 1, the heating fiber 3 and the pressing die 4 are used so that the reinforcing fiber base material 2 with the same amount of the binder 1 attached to one side faces upward with respect to the mold surface of the heating die 3. This shows a shaped state of a laminate 5 in which a large number of layers are laminated and only the reinforcing fiber base 2 closest to the pressing die 4 is laminated with the binder 1 adhesion surface facing downward. By using the reinforcing fiber base 2 to which the same amount of the binder 1 is adhered, the amount of the binder 1 adhered between the layers farthest from the heating mold can be easily increased.

  In FIG. 4, the structure of the laminated body 5 using the reinforcing fiber base material 2 in which the same amount of the binder 1 is attached to one side between the upper and lower heating molds 3 as in FIG. 2 is shown. Is. It is characterized by laminating so that the adhesion surface of the binder 1 faces in the center in the thickness direction of the laminate 5.

  As for the heating mold 3 used at the time of forming the preform 6, a method of heating the mold with a mold temperature control device is often used, but is not particularly specified if the temperature of the mold is kept constant and temperature adjustment is easy. .

  In the present invention, the porosity of the preform can be calculated from the volume content Vf (%) of the reinforcing fiber substrate by the porosity = 100−Vf (%). A porosity of 50% or more is preferable because the matrix resin easily flows between the reinforcing fiber bases 2. If the porosity of the preform is to be less than 50%, it is necessary to apply an excessive pressure with the pressing die 4 or the like, which may increase the molding cycle time of the preform. When the porosity of the preform is increased, the reinforcing effect by the reinforcing fiber base is reduced. Therefore, the upper limit of the porosity is preferably 60%. When the porosity is 60% or more, the contact area between the reinforcing fiber bases 2 is reduced, and there is a possibility that the fixing force cannot be obtained regardless of the amount of the binder 1 attached.

  The binder 1 used in the present invention may be any material that has adhesiveness at room temperature or when heated, such as a thermosetting resin such as a phenol resin or an epoxy resin, or a thermoplastic resin such as polypropylene. It may be a composition. Among these, those having adhesiveness at room temperature are difficult to store, and the process of spraying on the surface of the reinforcing fiber substrate 2 becomes complicated, so that it is a resin or composition having adhesiveness when heated to 70 ° C. or higher. Preferably there is. Also, the form thereof is not particularly limited, such as solid, liquid, paste-like, etc., but since the process of spraying on the surface of the reinforcing fiber base 2 is simple, it is a dotted, linear or discontinuous line In particular, it is easy to automate a method of having a solid form at room temperature (about 25 ° C.), spraying it on the surface of the reinforcing fiber base 2 as a powder cake, and heating and fusing it. This method is suitable for mass production.

  The mold temperature during preform molding is preferably higher by 10 ° C. than the glass transition temperature of the binder 1 and cooled to a temperature lower than the glass transition temperature of the binder 1 when the preform is removed. If the temperature of the mold does not become 10 ° C. or higher than the glass transition temperature of the binder 1 at the time of preform molding, the binder 1 may not melt, and the temperature is higher than the glass transition temperature of the binder 1 at the time of preform demolding. In this case, the layers may be separated and peeled off before the binder 1 fixes the layers.

  Moreover, it is preferable that the glass transition temperature of the binder 1 shall be 40-95 degreeC. When the glass transition temperature is lower than 40 ° C., the binder 1 may be melted in the storage state. When the glass transition temperature is higher than 95 ° C., the heating mold 3 becomes high temperature at the time of preform molding, and workability may be deteriorated.

  In the present invention, it is preferable that the preform 6 laminated and fixed is adhered so that the adhesive strength between the respective layers is 10 N / m or more. When the adhesive force between layers is less than 10 N / m, the reinforcing fiber base 2 cannot support its own weight, and there is a disadvantage that it is peeled off when the preform 6 is conveyed. The peel strength of the preform reinforcing fiber substrate 2 was measured by simulating the method of the T-type peel adhesion strength test of JIS K 6854-3 (1999).

  The reinforcing fiber base 2 is a fiber in which reinforcing fibers are arranged in a sheet form, and examples of the reinforcing fibers include carbon fibers, glass fibers, allied fibers, metal fibers, and the like. Carbon fiber is preferably used in that a fiber-reinforced composite material is obtained. As the carbon fiber used in the present invention, a polyacrylonitrile (PAN) carbon fiber having an excellent property in terms of strength using an acrylic fiber as a raw material is a pitch having an excellent property in terms of elastic modulus using a petroleum pitch as a raw material. Any of the carbon-based carbon fibers may be used.

  The reinforcing fiber preferably has a tensile strength of 3000 MPa or more and a tensile modulus of 200 GPa or more. When the tensile strength is less than 3000 MPa or the tensile elastic modulus is less than 200 GPa, the plate thickness must be increased in order to ensure the desired rigidity, resulting in an increase in weight.

  As the form of the reinforcing fiber base 2, it is preferable that the reinforcing fiber base 2 is composed of continuous reinforcing fibers if high strength is required, and when it is required to be inexpensive, a non-woven fabric obtained by cutting the reinforcing fibers short can be selected. it can. When continuous reinforcing fibers are used, a unidirectional material (UD material) in which reinforcing fiber bundles are aligned in one direction may be used, or a woven material obtained by weaving reinforcing fiber bundles may be used. Then, the woven material is easier to use. Plain weave, satin weave, twill weave, non-crimp cloth, etc. can be selected as appropriate for the weaving structure of the woven fabric material. Can be high. Also, satin weave and twill weave are good for draping and are therefore preferably used when shaping a three-dimensional shape with a deep depth.

  In order to laminate the reinforcing fiber base material 2, it is common to use a method in which the reinforcing fiber base material 2 that has been cut into an arbitrary shape in advance is stacked and shaped, but the reinforcing fiber to which the binder 1 is attached. When the base material 2 is laminated, the shape of the laminate can be stabilized by heating and cooling after superposing the reinforcing fiber base materials 2.

  The laminated structure of the reinforcing fiber base 2 for forming the preform 6 can be appropriately adopted according to a desired shape and design. For example, when molding an automobile outer panel, the surface area is large and the shape of the thin plate is large, and the working load is assumed to be a bending load and a shearing load such as torsion. It is common to employ a quasi-isotropic laminated structure in which reinforcing fiber bundles are arranged in directions of 0 °, 90 °, + 45 °, and −45 ° using a unidirectional woven fabric. However, anisotropy can be appropriately provided according to the type of vehicle and the part to be applied.

  In addition to carbon fibers, other reinforcing fibers and auxiliary materials such as mats, non-woven fabrics, and fillers can be used for the purpose of improving surface design, moldability, and matrix resin impregnation. For example, the use of a glass surface mat or the like may improve surface smoothness and matrix resin impregnation. There is also a technique for reducing costs by using continuous fibers of glass and other organic fibers in combination with carbon fibers. Furthermore, not only fibers but also a core material such as urethane can be used together to reduce weight and cost.

  The preform 6 of the present invention as described above can obtain FRP by RTM molding. In RTM molding, a low-viscosity liquid matrix resin is injected and impregnated into a preform placed in a mold to obtain FRP. When a thermosetting resin is used as the matrix resin, it is necessary to cure the thermosetting resin by heating after impregnation.

  As a mold for installing the preform 6, a closed mold made of a rigid body may be used, or a rigid open mold and a flexible film (bag) may be used. In the latter case, the preform is placed between the rigid open mold and the flexible film. As the rigid material, metals such as steel and aluminum, FRP, wood, plaster, and the like can be used. As a material for the flexible film, polyamide, fluorine resin, silicone resin, or the like can be used.

  Next, a method for manufacturing the preform 6 and a method for manufacturing FRP using the obtained preform will be described.

  A method for manufacturing the preform 6 will be described with reference to FIG. Reinforced fiber base material with a small amount of binder 1 attached so that the binder 1 attached surface faces upward on the heating mold 3 set to 10 ° C. higher than the glass transition temperature of the binder 1. Laminate sequentially from 2. The pressing mold 4 is placed on the laminated reinforcing fiber base 2 and the laminate 5 is pressurized. Thereafter, the laminate is taken out of the heating mold 3 and cooled, and the laminate is used as a preform 6.

  As a specific procedure of the manufacturing method of FRP using the obtained preform 6, when a rigid closed mold is used, it can be pressurized and clamped, and the matrix resin can be pressurized and injected. At this time, a suction port can be provided separately from the injection port and connected to a vacuum pump for suction. Further, the liquid matrix resin may be injected while maintaining the atmospheric pressure without applying pressure at the injection port while performing suction from the suction port.

When a rigid open mold and a flexible film are used, injection of the matrix resin into the preform is usually realized by suction from the suction port and injection from the injection port at atmospheric pressure. In order to achieve good impregnation of the matrix resin into the preform by injection at atmospheric pressure, the resin impregnation coefficient is at least 1 × 10 ⁻¹⁰ m ² on the surface of at least one side of the reinforcing fiber base material, and the reinforcement It is effective to use a resin diffusion medium layer having a resin impregnation coefficient ratio with the fiber substrate 2 in the range of 1.5 to 10. The resin impregnation coefficient is a value measured by the following measurement method.

In the resin impregnation process, it is known that the behavior of the resin impregnated into the base material follows the Darcy law shown in the following equation, and the impregnation rate is obtained by the following equation.
v = (K / μ) × (ΔP / ΔL) (1)
Here, v (m / s) is the impregnation rate, K (m ² ) is the impregnation coefficient, μ is the resin viscosity (Pa · s), ΔP (Pa) / ΔL (m) is the pressure gradient per unit length. is there. If this equation is integrated over time t (s), the impregnation coefficient can be obtained by the following equation.
K = (L × L × μ) / (2 × P × t) (2)
Here, L (m) is the distance from the resin inlet to the flow front (the tip of the fluid resin). If the distance from the resin inlet to the flow front, the arrival time there, the resin viscosity, and the molding pressure are known from the equation (2), the impregnation coefficient can be calculated.

  It is also preferable to apply a gel coat to the rigid surface prior to installation of the preform. After installing the preform, mold clamping or bagging is performed, followed by injection of matrix resin.

  The matrix resin may be a thermosetting resin such as an epoxy resin, a vinyl ester resin, or an unsaturated polyester resin, or a thermoplastic resin as long as it is a low viscosity and liquid resin. Usually, an epoxy resin is preferably used because of its good adhesion to the reinforcing fibers and high strength. In addition, when using a molded article in the place exposed to high temperature, you may utilize heat resistant resins, such as a bismaleimide resin and a polyimide resin. Various additives can also be added to the matrix resin. For example, when an ultraviolet absorbent is mixed with the matrix resin, the matrix resin can be prevented from being deteriorated by ultraviolet rays. In the case of an epoxy resin, the viscosity of the matrix resin is about 100 to 160 Pa · s at room temperature (about 25 ° C.).

  Although the use of the preform of the present invention is not particularly limited, it is particularly suitably used when an automobile outer panel is composed of FRP. Specific examples include hood hoods, roofs, doors, trunk lids, and fenders.

  In particular, CFRP, which is an FRP formed using carbon fiber as a reinforcing fiber in the preform of the present invention, is lighter than metal materials such as steel and aluminum, and is superior in strength and rigidity. Suitable as a material for rigid panel structures, especially automobile outer panel

  Hereinafter, the present invention will be described more specifically based on examples. In this example, a preform was prepared using the following materials.

<Material>
-Bidirectional woven fabric: CO6343B manufactured by Toray Industries, Inc. (woven yarn: carbon fiber T300-3K, woven structure: plain weave, fabric weight: 198 g / m ² , thickness: 0.25 mm, warp woven density: 12.5 / 25mm, weft density: 12.5 / 25mm)
・ Binder: Toray Industries, Inc. CT-006 (binder for reinforcing fiber base)

<Production of reinforcing fiber base>
While calculating so that the mass per unit area (adhesion amount) was 4 g / m ^{2 on} one surface of the bi-directional woven fabric, the binder was wrapped in a gauze that was superposed on a plurality of sheets. Subsequently, the binder is fixed on the fabric by passing it under the far-infrared heater at 0.3 m / min so that the surface temperature of the bidirectional fabric is sufficient to melt the tackifier. Thus, a reinforcing fiber substrate a was produced.

Further, a reinforcing fiber base material b was prepared in the same manner as the reinforcing fiber base material a, except that the binder adhesion amount was changed to 12 g / m ² .
A reinforcing fiber substrate c was prepared in the same manner as the reinforcing fiber substrate a except that the amount of the binder attached was changed to 20 g / m ² .

  Moreover, the reinforced fiber base material n without a binder was prepared.

<Cutting out test piece>
A test piece having a size of 150 × 25 mm was cut out from each reinforcing fiber substrate so that the longitudinal direction was 0 ° and 90 ° when the directions of warp and weft were 0 ° and 90 °, respectively.

<Example 1>
From the bottom, the test pieces cut out from the respective reinforcing fiber bases are, from below, the test pieces of the reinforcing fiber base a, the test pieces of the reinforcing fiber base b, the test pieces of the reinforcing fiber base c, and the test pieces of the reinforcing fiber base n. It laminated | stacked so that it might become, and the laminated body was obtained. In addition, the base material with a binder was laminated | stacked so that the binder adhesion surface might become upward. Then, the obtained laminated body was arrange | positioned at the heating type | mold heated at 100 degreeC so that the surface without the binder of the reinforced fiber base material a might contact the heating type | mold surface.

Next, a weight (pressing die) was placed on the laminate for 30 seconds so as to cover a range of 100 mm from one side in the major axis direction, thereby forming a preform. A spacer having a thickness of 1 mm was sandwiched between the weight and the flat plate so that the porosity was 55%. Here, the porosity was calculated as follows.
Porosity = 100−Vf (%)
Vf = (W2 × 100) / (ρ × T2) (%)
W2: Weight of reinforcing fiber per 1 cm ^{2 of} FRP (g / cm ² )
ρ: Density of reinforcing fiber (g / cm ³ )
T2: FRP thickness (mm)

  The preform was removed from the heating mold, the preform was taken out from the heating mold, and the naturally cooled preform was not peeled off between layers.

  The resulting preform was subjected to a delamination test in order from the layer far from the heating surface. The adhesive strength between any of the layers was 10 N / m or more.

<Example 2>
A peel test was performed in the same manner as in Example 1 except that the time for placing the weight was changed from 30 seconds to 60 seconds. The obtained preform was lifted even when the end portion was grasped, and the adhesive strength between any layers was 10 N / m or more.

<Example 3>
A peel test was performed in the same manner as in Example 1 except that the time for placing the weight was changed from 30 seconds to 90 seconds. The obtained preform was lifted even when the end portion was grasped, and the adhesive strength between any layers was 10 N / m or more.

<Comparative Example 1>
From the bottom, the reinforcing fiber base material is laminated in the order of the test piece of the reinforcing fiber base material b, the test piece of the reinforcing fiber base material b, the test piece of the reinforcing fiber base material b, and the test piece of the reinforcing fiber base material n. A peel test was conducted in the same manner as in Example 1 except that the change was made. The layer far from the heated surface peeled off when lifted without sticking. The other layers were also bonded, but the bonding strength between the layers was less than 10 N / m.

<Comparative example 2>
A peel test was performed in the same manner as in Comparative Example 1 except that the time for placing the weight was changed from 30 seconds to 60 seconds. The obtained preform was lifted even when the end portion was grasped, but the adhesive force between the layers far from the heating surface was less than 10 N / m.

<Comparative Example 3>
A peel test was performed in the same manner as in Comparative Example 1 except that the time for placing the weight was changed from 30 seconds to 90 seconds. The adhesive strength between any of the layers was 10 N / m or more.

  From the results of comparison with the above Examples and Comparative Examples, it became clear that in the present invention, a preform having good transportability can be obtained in a short molding cycle time, and an optimal shaping state can be realized.

  Since the molding cycle time can be shortened and the appearance and handleability of the preform are improved, it is particularly suitable for automotive outer plate parts requiring high design and mass productivity. However, it is not limited to these.

1: Binder 2: Fiber base material 3: Heating type 4: Pressing type 5: Laminate 6: Preform

Claims (16)

A preform obtained by laminating at least three layers of reinforcing fiber bases with a binder attached to the surface in advance and melting the binder by heating to bond the layers of the reinforcing fiber bases. A preform characterized in that the amount of binder attached to the surface of a reinforcing fiber substrate having a relatively low temperature distribution between layers in the body lamination direction is increased. The preform according to claim 1, wherein the laminate is laminated in one or a plurality of divided molds, and the mold is heated to melt the binder. The laminated body arranged between the molds heated from both sides has the largest binder adhesion amount of the reinforcing fiber base arranged at the approximate center in the lamination direction of the laminated body. Preforms. The reinforcing fiber base material having a binder attached on one side is laminated with the binder attached surface facing the substantially center in the laminating direction of the laminate, and laminated so that the binder attached surface faces the substantially center. The preform according to claim 3. In the laminate disposed in a mold heated from one side, the preform is a preform for heating the binder, and the binder adhesion amount of the reinforcing fiber base most distant from the mold surface to be heated is maximized. The preform according to claim 2. A reinforcing fiber base material having a binder attached on one side is laminated so as to be a binder attaching surface on the side opposite to the mold surface to be heated, and the binder attaching surface of the reinforcing fiber base furthest away from the heating surface is heated on the mold surface. The base material preform according to claim 5, wherein the base material is laminated toward the side. The preform according to any one of claims 1 to 6, wherein the preform has a porosity of 50% or more. The preform according to any one of claims 2 to 7, wherein after the mold is heated to 10 ° C or more from the glass transition temperature of the binder, the mold is cooled to the glass transition temperature or less of the binder and then demolded. . The preform according to any one of claims 1 to 8, which is formed by laminating a reinforcing fiber base made of carbon fiber. The preform according to any one of claims 1 to 9, wherein the reinforcing fiber has a tensile strength of 3000 MPa or more and a tensile elastic modulus of 200 GPa or more. The preform according to any one of claims 1 to 10, wherein the reinforcing fiber base is a woven fabric. The preform according to any one of claims 1 to 11, wherein an adhesion amount of the binder adhered to the surface of the reinforcing fiber substrate is 3 g / m ² to 20 g / m ² . The preform according to any one of claims 1 to 12, wherein the binder has a glass transition temperature of 40 ° C to 95 ° C. The preform according to any one of claims 1 to 13, wherein the adhesion form of the binder on the reinforcing fiber base is a dotted, linear, or discontinuous linear shape. The preform according to any one of claims 1 to 14, having a peel strength of 10 N / m or more. A fiber-reinforced resin molded article obtained by impregnating the preform according to any one of claims 1 to 15 with a matrix resin and curing the preform.

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