JP7083544B2 - Manufacturing method of fiber reinforced thermoplastic resin sheet - Google Patents

Description

The present invention relates to a method for producing a fiber-reinforced thermoplastic resin sheet.

The fiber reinforced plastic (FRP) is a composite material in which a thermosetting resin or a thermoplastic resin is used as a matrix, and the resin further contains reinforced fibers such as carbon fibers, aramid fibers, and glass fibers.

Fiber reinforced plastics using a thermosetting resin such as an epoxy resin or a urethane resin as a matrix are lightweight and have high strength, and are therefore used in the fields of aerospace, automobiles, sporting goods, and the like. Since the thermosetting resin has a low viscosity in an uncured state, it can be easily impregnated into the reinforcing fibers, and its strength can be increased by a curing reaction. However, thermosetting resins have the disadvantage of being brittle and inferior in impact resistance. Further, when a thermosetting resin is used as a matrix to produce a prepreg, it may be difficult to handle due to the short pot life of the resin, or the storage stability may not be sufficient. Further, there is a problem that a long molding time is required when molding a part or the like from a composite resin material. In recent years, an RTM molding method has been proposed in which a reinforcing fiber base material not impregnated with a resin is set in a mold and then a thermosetting resin is poured, and the molding time is significantly shortened by this method. However, even when the RTM molding method is used, it takes 10 minutes or more to mold one molded product.

On the other hand, fiber reinforced plastic (FRTP) using a thermoplastic resin as a matrix has high toughness, easy storage and management of prepreg, and does not require a curing reaction, so it can be used for injection molding, stamping molding, etc. It is possible to increase the speed of the molding cycle. Furthermore, FRTP has many advantages over fiber reinforced plastics using a thermosetting resin as a matrix, such as excellent recyclability and excellent repairability such as welding and repair, and is therefore put into practical use in a wide range of fields. ..

For example, Patent Document 1 uses a method in which chopped carbon fibers cut to a predetermined length are melt-kneaded together with resin pellets or resin powder in an extruder to be pelletized, and this is made into a molded product by injection molding. A method for producing chopped carbon fiber is described. Patent Document 2 describes a method for producing a chopped fiber bundle used for SMC (Sheet Molding Compound) and stampable sheets.

Patent Document 3 describes a reinforcing fiber having a specific fiber length and a specific two-dimensional orientation angle, which can be applied to a thin molded product and can obtain an isotropically mechanically excellent molded product. Prepregs to include are listed. In the prepreg described in Patent Document 3, the reinforcing fibers are present in the form of single threads.

As a method for producing a fiber-reinforced plastic using a thermoplastic resin as a matrix, a fiber-reinforced thermoplastic resin sheet, which is a laminate in which a chopped prepreg containing a thermoplastic resin and a reinforcing fiber is laminated, is also known. For example, in Patent Document 4, chopped strand prepregs having a length in a predetermined fiber direction are laminated in a sheet shape so that the fiber orientation is two-dimensionally random, and the laminate obtained is integrated by spot welding. The fiber-reinforced thermoplastic resin sheet obtained is described. Patent Document 5 describes an isotropic fiber-reinforced thermoplastic resin sheet obtained by heating and pressurizing a laminate obtained by laminating a specific chopped strand prepreg so that the fiber orientation is random.

Japanese Patent No. 4161409 Japanese Unexamined Patent Publication No. 2009-114612 Japanese Unexamined Patent Publication No. 2010-235779 Japanese Unexamined Patent Publication No. 2007-262360 Japanese Unexamined Patent Publication No. 2013-22140

Although the above-mentioned various methods for producing fiber-reinforced plastics have been proposed, there is still a demand for improving the strength of fiber-reinforced plastics. There is also a demand for fiber reinforced plastics with high strength and little variation in strength. For example, in the methods disclosed in Patent Document 1 and Patent Document 2, it is difficult to manufacture a thin-walled molded product because the fiber and the resin are impregnated in the molding mold at the time of injection molding or press molding. be. Further, there is a problem that the fiber orientation is disturbed due to the flow of the resin during molding, and it is difficult to control the fiber orientation. As disclosed in Patent Document 3, when the reinforcing fiber in the prepreg is in the form of a single thread, if the fiber length becomes long, the linearity of the fiber cannot be maintained and the physical properties may deteriorate.

Further, as disclosed in Patent Documents 4 and 5, it is known to produce a fiber-reinforced thermoplastic resin sheet through a step of laminating chopped strand prepregs in a sheet shape so that the fiber orientation becomes two-dimensionally random. However, Patent Documents 4 and 5 do not clearly specify the drop height and the weight of the base material, and do not pay any attention to the variation in the strength of the fiber-reinforced thermoplastic resin sheet due to these methods.

Therefore, the present invention can freely manufacture a fiber-reinforced thermoplastic resin sheet having high strength and little variation in strength in any size, thereby efficiently producing a high-quality sheet while minimizing material loss. It is intended to provide a method of manufacturing.

In order to achieve the above object, the present inventors have conducted diligent studies, and as a result, the unidirectional prepreg is freely dropped and sprayed and laminated under the condition that the drop height, the base weight and the volume satisfy a specific relationship. As a result, it was found that the above object could be achieved, and the present invention was completed.

により算出される値Ａは０．７以下である、製造方法。
［２］１つの散布口から１回に落下させる一方向プリプレグの重量（Ｘｇ）、および、被積層面から散布口までの距離（Ｈｍｍ）から次の式（２）：

により算出される値Ｂは０．０３以下である、前記［１］に記載の製造方法。
［３］一方向プリプレグの平均体積（Ｖｍｍ^３）は、４～６０ｍｍ^３である、前記［１］または［２］に記載の製造方法。
［４］被積層面を１または２以上の積層区画に分け、各積層区画において前記散布工程を行う、前記［１］～［３］のいずれかに記載の製造方法。
［５］１つの積層区画に対し２回以上の散布工程を行う、前記［４］に記載の製造方法。
［６］２つ以上の散布口から一方向プリプレグを落下させる、前記［１］～［５］のいずれかに記載の製造方法。
［７］散布部および／または積層部が、被積層面に対して略水平方向に連続的または間欠的に移動する、前記［１］～［６］のいずれかに記載の製造方法。
［８］各積層区画の大きさ（Ｌｍｍ^２）、および、被積層面から散布口までの距離（Ｈｍｍ）から次の式（３）：

により算出される値Ｃは１～５０である、前記［４］～［７］のいずれかに記載の製造方法。
［９］散布工程により得た積層物を加熱して一次接着凝集物を得る工程をさらに含む、前記［１］～［８］のいずれかに記載の製造方法。
［１０］繊維強化熱可塑性樹脂シートの単位面積あたりの重量は３００～１６００ｇ／ｍ^２である、前記［１］～［９］のいずれかに記載の製造方法。
［１１］繊維強化熱可塑性樹脂シートの繊維体積含有率は１０～９９体積％である、前記［１］～［１０］のいずれかに記載の製造方法。
［１２］強化繊維は炭素繊維である、前記［１］～［１１］のいずれかに記載の製造方法。
［１３］繊維強化熱可塑性樹脂シートにおいて、ＪＩＳ Ｋ ７１６４に従い測定した引張強度のＣＶ値は２０．０％未満である、前記［１］～［１２］のいずれかに記載の製造方法。 That is, the present invention includes the following preferred embodiments.
[1] A method for producing a fiber-reinforced thermoplastic resin sheet in which unidirectional prepregs containing reinforcing fibers and a thermoplastic resin are laminated so that the fiber directions are random.
Using a device having at least a spraying portion provided with a spraying port for spraying the one-way prepreg and a laminated portion having a laminated surface for laminating the one-way prepreg, a spraying port located above the laminated surface. Including the spraying step of dropping the one-way prepreg from the to the laminated surface, the average volume per one-way prepreg is V mm ³ , and the weight of the one-way prepreg dropped from one spray port at one time is Xg. Assuming that the distance from the laminated surface to the spray port is H mm, the following equation (1): from V, X and H:

The manufacturing method, wherein the value A calculated by the above method is 0.7 or less.
[2] From the weight (Xg) of the one-way prepreg dropped from one spraying port at one time and the distance (Hmm) from the laminated surface to the spraying port, the following equation (2):

The manufacturing method according to the above [1], wherein the value B calculated by the above method is 0.03 or less.
[3] The production method according to the above [1] or [2], wherein the average volume (Vmm ³ ) of the one-way prepreg is 4 to 60 mm ³ .
[4] The production method according to any one of [1] to [3], wherein the surface to be laminated is divided into one or two or more laminated sections, and the spraying step is performed in each laminated section.
[5] The manufacturing method according to the above [4], wherein the spraying step is performed two or more times on one laminated section.
[6] The production method according to any one of [1] to [5] above, wherein the unidirectional prepreg is dropped from two or more spray ports.
[7] The manufacturing method according to any one of [1] to [6] above, wherein the spraying portion and / or the laminated portion moves continuously or intermittently in a substantially horizontal direction with respect to the laminated surface.
[8] From the size of each laminated section (Lmm ² ) and the distance from the laminated surface to the spray port (Hmm), the following equation (3):

The production method according to any one of [4] to [7] above, wherein the value C calculated by the above method is 1 to 50.
[9] The production method according to any one of [1] to [8] above, further comprising a step of heating the laminate obtained by the spraying step to obtain a primary adhesive aggregate.
[10] The production method according to any one of [1] to [9] above, wherein the weight per unit area of the fiber-reinforced thermoplastic resin sheet is 300 to 1600 g / m ² .
[11] The production method according to any one of [1] to [10] above, wherein the fiber volume content of the fiber-reinforced thermoplastic resin sheet is 10 to 99% by volume.
[12] The production method according to any one of [1] to [11] above, wherein the reinforcing fiber is carbon fiber.
[13] The production method according to any one of [1] to [12] above, wherein the CV value of the tensile strength measured according to JIS K 7164 is less than 20.0% in the fiber-reinforced thermoplastic resin sheet.

According to the manufacturing method of the present invention, it is possible to efficiently manufacture a fiber-reinforced thermoplastic resin sheet having high strength while having a thin layer and having little variation in strength.

It is a figure which shows the schematic diagram of the spraying part and the laminated part of the apparatus used in one Embodiment of the manufacturing method of this invention. It is a figure for demonstrating an example of the spraying process in the manufacturing method of this invention. It is a figure which shows the schematic diagram of the whole apparatus used in one Embodiment of the manufacturing method of this invention. It is a figure for demonstrating an example of the spraying process in the manufacturing method of this invention. It is a figure for demonstrating another example of the spraying process in the manufacturing method of this invention. It is a figure which shows the schematic diagram for demonstrating the apparatus used in the Example of this invention. It is a figure which shows the schematic diagram for demonstrating the apparatus used in the Example and the comparative example of this invention. It is a figure for demonstrating the spraying process in an Example and a comparative example of this invention. It is a figure for demonstrating the spraying process in an Example and a comparative example of this invention. It is a figure for demonstrating the spraying process in an Example and a comparative example of this invention. It is a figure for demonstrating the spraying process in an Example and a comparative example of this invention. It is a figure for demonstrating the spraying process in an Example and a comparative example of this invention. It is a figure for demonstrating the spraying process in an Example and a comparative example of this invention.

Hereinafter, embodiments of the present invention will be described in detail. The scope of the present invention is not limited to the embodiments described here, and various modifications can be made without departing from the spirit of the present invention.

により算出される値Ａは０．７以下である、製造方法である。上記特徴を有する本発明の製造方法によれば、薄層でありながらも高い強度と賦形性とを兼ね備え、強度のばらつきが少ない繊維強化熱可塑性樹脂シートを効率的に製造することができる。 [Manufacturing method of fiber reinforced thermoplastic resin sheet]
The manufacturing method of the present invention is a method for manufacturing a fiber-reinforced thermoplastic resin sheet in which unidirectional prepregs containing reinforced fibers and a thermoplastic resin are laminated so that the fiber directions are random, and the unidirectional prepreg is sprayed. Using a device having at least a spraying portion having a spraying port for laminating and a laminating part having a laminated surface for laminating the one-way prepreg, a one-way prepreg is provided from the spraying port located above the laminated surface. It includes a spraying step of dropping onto the laminated surface, where the average volume per one-way prepreg is Vmm ³ , and the weight of the one-way prepreg dropped from one spray port at one time is Xg. Assuming that the distance from the spray port to the spray port is H mm, the following equation (1): from V, X and H:

The value A calculated by the above method is 0.7 or less, which is a manufacturing method. According to the production method of the present invention having the above-mentioned characteristics, it is possible to efficiently produce a fiber-reinforced thermoplastic resin sheet having high strength and shapeability while having a thin layer and having little variation in strength.

If the value A calculated by the above equation (1) exceeds 0.7, the one-way prepreg cannot be sprayed and laminated with sufficient randomness. As a result, the strength of the obtained fiber-reinforced thermoplastic resin sheet is lowered, and the variation in strength is increased. Here, the randomness of the unidirectional prepreg in the present specification is particularly the randomness of the reinforcing fibers in the two-dimensional direction with respect to the laminated surface, and is increased by randomly laminating the prepregs in the two-dimensional direction. It is possible to obtain a fiber-reinforced thermoplastic resin sheet having strength and little variation in strength. When the value A is equal to or less than the above upper limit, variations in mechanical strength such as tensile strength can be suppressed. The lower limit of the value A is not particularly limited, but from the viewpoint of reducing the total number of sprays and easily increasing the production efficiency, a condition in which the spray weight per spray is large is preferable, and for example, 0.05 or more is preferable. The value A is, as understood from the above equation (1), the average volume per unidirectional prepreg (Vmm ³ ) and / or the weight of the unidirectional prepreg dropped from one spray port at one time (1). It is a value that is increased by increasing Xg) or decreasing the distance (H mm) from the surface to be laminated to the spray port. Therefore, the value A can be adjusted to the above range by appropriately setting these conditions. The average volume per one-way prepreg (Vmm ³ ), the weight of the one-way prepreg dropped from one spray port at one time (Xg), and the distance from the laminated surface to the spray port (Hmm) are , Measured by the method described below.

により算出される値Ｂは、好ましくは０．０３以下である。値Ｂが上記の上限以下である場合、繊維強化熱可塑性樹脂シートの強度ばらつきを抑制しやすい。値Ｂの下限値は特に限定されず、例えば０．００１以上であることが好ましい。値Ｂは、上記式（２）から理解されるように、１つの散布口から１回に落下させる一方向プリプレグの重量（Ｘｇ）を大きくするか、被積層面から散布口までの距離（Ｈｍｍ）を小さくすることにより、増大する値である。そのため、これらの条件を適宜設定することにより、値Ｂを上記範囲に調整することができる。なお、１つの散布口から１回に落下させる一方向プリプレグの重量（Ｘｇ）、および、被積層面から散布口までの距離（Ｈｍｍ）は、後述する方法により測定される。 In the manufacturing method of the present invention, the following formula (2):

The value B calculated by is preferably 0.03 or less. When the value B is not more than the above upper limit, it is easy to suppress the strength variation of the fiber-reinforced thermoplastic resin sheet. The lower limit of the value B is not particularly limited, and is preferably 0.001 or more, for example. As understood from the above equation (2), the value B increases the weight (Xg) of the one-way prepreg dropped from one spray port at one time, or increases the weight (Xg) from the laminated surface to the spray port (H mm). ) Is reduced, and the value is increased. Therefore, the value B can be adjusted to the above range by appropriately setting these conditions. The weight (Xg) of the one-way prepreg dropped from one spraying port at one time and the distance (Hmm) from the laminated surface to the spraying port are measured by the method described later.

により算出される。変動係数の値が小さいほど、繊維強化熱可塑性樹脂シートの等方性が高く、強度のばらつきが少ないことを表す。ここで、本発明においては、繊維強化熱可塑性樹脂シートの等方性の指標として、機械的強度、特に引張強度のばらつき（変動係数）に着目している。繊維強化熱可塑性樹脂シートについて測定可能な機械的強度としては、引張強度の他に、曲げ強度、曲げ弾性率等が挙げられる。この中でも、引張強度は、繊維強化熱可塑性樹脂シート全体における一方向プリプレグの配向性の影響をより受けやすい。そのため、引張強度のばらつきから、繊維強化熱可塑性樹脂シート全体における一方向プリプレグの配向性（等方性）のばらつきをより精度よく評価できると考えられる。これに対し、曲げ強度および曲げ弾性率は、実際には繊維強化熱可塑性樹脂シートの表層における一方向プリプレグの配向性の影響を反映しやすいため、これらの機械的強度のばらつきからは、シート全体におけるばらつきを高い精度で評価しにくい場合がある。本発明の製造方法により製造した繊維強化熱可塑性樹脂シートは、等方性が高く、強度のばらつきが少ないため、高い賦形性を有している。 According to the manufacturing method of the present invention, the unidirectional prepreg can efficiently manufacture a fiber-reinforced thermoplastic resin sheet laminated so that the fiber directions are random. Here, when the unidirectional prepregs are laminated in the fiber-reinforced thermoplastic resin sheet so that the fiber directions are random, the isotropic property of the fiber-reinforced thermoplastic resin sheet can be enhanced. This is because the fiber direction does not become excessive locally with respect to a certain direction, so that stress is sufficiently transmitted in a direction different from the fiber axial direction via the fiber, and the fiber is isotropically originally possessed. It is considered that this is because the strength can be fully utilized. Further, when the unidirectional prepregs are laminated so that the fiber directions are random, the variation in the mechanical strength of the fiber-reinforced thermoplastic resin sheet can be suppressed, and the isotropic property can be easily enhanced. This is considered to be due to the following reasons. First, focusing on one unidirectional prepreg contained in the fiber-reinforced thermoplastic resin sheet, the mechanical strength tends to be high in the fiber direction and weak in the width direction orthogonal to the fiber direction. be. Therefore, when the fiber direction is locally excessive with respect to a certain direction of the fiber-reinforced thermoplastic resin sheet, it has high mechanical strength in that direction, but with respect to the direction orthogonal to the direction. As a result, the mechanical strength decreases. Therefore, if such a portion where the fiber direction is locally excessive is present in the fiber-reinforced thermoplastic resin sheet, it exhibits high mechanical strength in one direction, but exhibits high mechanical strength in another direction. It is considered that the mechanical strength becomes low and sufficient isotropic properties cannot be obtained. In this case, when the mechanical strength of the fiber-reinforced thermoplastic resin sheet is measured and the coefficient of variation is calculated, the coefficient of variation tends to be high due to the large variation. In the present invention, the fluctuation coefficient (CV value) of the tensile strength of the fiber-reinforced thermoplastic resin sheet is preferably less than 20.0%, more preferably 19.0% or less, still more preferably 15.0% or less, particularly preferably. It is preferable that the unidirectional prepregs are randomly laminated so as to be 10.0% or less. The tensile strength of the fiber-reinforced thermoplastic resin sheet is measured according to JIS K 7164. Details of the measurement conditions are as described later. The coefficient of variation (CV value) is calculated from the standard deviation and mean value obtained from the measurement results for at least 5 measurement samples, and the following formula:

Is calculated by. The smaller the value of the coefficient of variation, the higher the isotropic property of the fiber-reinforced thermoplastic resin sheet, and the smaller the variation in strength. Here, in the present invention, as an index of the isotropic property of the fiber-reinforced thermoplastic resin sheet, attention is paid to the variation (coefficient of variation) in the mechanical strength, particularly the tensile strength. Examples of the measurable mechanical strength of the fiber-reinforced thermoplastic resin sheet include bending strength, bending elastic modulus, and the like, in addition to tensile strength. Among these, the tensile strength is more susceptible to the orientation of the unidirectional prepreg in the entire fiber-reinforced thermoplastic resin sheet. Therefore, it is considered that the variation in the orientation (isotropy) of the unidirectional prepreg in the entire fiber-reinforced thermoplastic resin sheet can be evaluated more accurately from the variation in the tensile strength. On the other hand, the bending strength and the flexural modulus tend to reflect the influence of the orientation of the unidirectional prepreg on the surface layer of the fiber-reinforced thermoplastic resin sheet. It may be difficult to evaluate the variation in the above with high accuracy. The fiber-reinforced thermoplastic resin sheet produced by the production method of the present invention has high isotropic properties and little variation in strength, and thus has high shapeability.

In the present invention, the average volume (Vmm ³ ) per unidirectional prepreg used for producing the fiber-reinforced thermoplastic resin sheet is preferably 4 to 60 mm ³ , more preferably 4 to 40 mm ³ . If the average volume per unidirectional prepreg exceeds the above upper limit, the number of substrates that can be sprayed per unit area decreases, and the variation in physical properties may increase. When the average volume is not more than the above upper limit, it is easy to make the number of base materials sufficient to enhance the isotropic property, and it is easy to suppress the variation in physical properties. For the volume per one-way prepreg (Vmm ³ ), the lengths in the fiber direction, the width direction orthogonal to the fiber direction, and the thickness direction of the one-way prepreg are measured using a digital caliper, and the product thereof is calculated. It is measured by doing. The above measurement is performed for each of at least 10 unidirectional prepregs arbitrarily selected, and the average value of the obtained results is taken as the average volume per unidirectional prepreg.

In the present invention, the average length of the unidirectional prepreg used for producing the fiber-reinforced thermoplastic resin sheet in the fiber direction is preferably 10 to 50 mm, more preferably 10 to 30 mm. When the average length of the unidirectional prepreg in the fiber direction is at least the above lower limit, the mechanical strength of the fiber-reinforced thermoplastic resin sheet can be easily increased and the variation thereof can be easily reduced. Further, when the average length is not more than the above upper limit, it is easy to suppress the generation of voids in the fiber-reinforced thermoplastic resin sheet. The length of the unidirectional prepreg in the fiber direction is measured using a digital caliper. The average value of the results obtained for each of at least 10 unidirectional prepregs arbitrarily selected is taken as the average length in the fiber direction of the unidirectional prepreg.

In the present invention, the average length in the width direction of the unidirectional prepreg used for producing the fiber-reinforced thermoplastic resin sheet is preferably 10 to 20 mm, more preferably 12 to 20 mm, still more preferably 15 to 20 mm. Here, the width direction of the unidirectional prepreg is a direction orthogonal to the fiber direction of the unidirectional prepreg. When the average length in the width direction of the unidirectional prepreg is equal to or greater than the above lower limit, it is easy to set the number of laminated sheets per unit thickness to a sufficient number, and it is easy to suppress variations in mechanical strength. Further, when the average length is not more than the above upper limit, it is easy to prevent the tape from cracking, so that it is easy to stabilize the volume of the base material per one-way prepreg, and it is easy to suppress the variation in mechanical strength. The widthwise length of a unidirectional prepreg is measured using a digital caliper. The average value of the results obtained for each of at least 10 unidirectional prepregs arbitrarily selected is taken as the average length in the width direction of the unidirectional prepreg.

In the present invention, the average thickness of the unidirectional prepreg used for producing the fiber-reinforced thermoplastic resin sheet is preferably 115 to 55 μm, more preferably 96 to 55 μm, still more preferably 77 to 55 μm. When the average thickness of the unidirectional prepreg is at least the above lower limit, it is easy to suppress the cracking of the tape, so that it is easy to stabilize the volume of the base material per one-way prepreg, and it is easy to suppress the variation in mechanical strength. Further, when the average thickness is not more than the above upper limit, it is easy to set the number of laminated sheets per unit thickness to a sufficient number, and it is easy to suppress the variation in mechanical strength. The thickness of the unidirectional prepreg is measured using a micrometer. The average value of the results obtained by performing the above measurement for each of at least 10 unidirectional prepregs arbitrarily selected is taken as the average thickness of the unidirectional prepregs.

(Device)
Next, the apparatus used in the manufacturing method of the present invention will be described. In the manufacturing method of the present invention, an apparatus having at least a spraying portion provided with a spray port for spraying the unidirectional prepreg and a laminated portion having a laminated surface for laminating the unidirectional prepreg is used. In the manufacturing method of the present invention, for example, an apparatus having a configuration as shown in FIG. 1 may be used. In the spraying device, in addition to the spraying portion and the laminated portion, a mechanism for adjusting the height of the spraying portion and the spraying portion or the laminated portion are moved in a quadric plane direction (for example, a direction substantially horizontal to the laminated surface). It may have a mechanism for the purpose. As the mechanism for moving, for example, an electric motor, a hydraulic motor, or the like may be used.

(Spraying part)
The configuration of the spraying portion provided with the spray port for spraying the unidirectional prepreg is not particularly limited as long as a predetermined amount of the unidirectional prepreg can be sprayed from the spray port to the surface to be laminated. The spraying unit is, for example, a spraying port for spraying a one-way prepreg, and a measuring unit for adjusting the weight of the one-way prepreg dropped at one time from one spraying port (hereinafter, also referred to as “spraying amount”). , A storage tank for storing the prepreg, a transportation unit for transporting the prepreg from the storage tank to the measuring unit, and the like may be provided. In the device, the one-way prepreg stored in the storage tank is supplied to the measuring section via the transport section, the weight is measured in the lightweight section, and when the predetermined weight is reached, the spray port opens and one-way. The prepreg freely falls onto the surface to be laminated. At this time, it is preferable that the environment from the spray port to the surface to be laminated is an environment in which no external force other than gravity is applied.

The spray port is usually located above the surface to be laminated and can be opened and closed. By opening the spray port, a predetermined amount of unidirectional prepreg is sprayed and set to be laminated on the surface to be laminated. Has been done. In the apparatus of the present invention, the spraying portion may have one spraying port or may have two or more spraying ports. From the viewpoint of easily increasing the production efficiency of the fiber-reinforced thermoplastic resin sheet by the production method of the present invention, the spraying portion preferably has two or more spraying ports. The size and shape of the spray port are not particularly limited, and a spray port having a desired size and shape may be used, but a shape that does not catch the unidirectional prepreg and is easy to spray is preferable. When the one-way prepreg freely falls in the spraying process, it basically spreads radially around the spraying point and is laminated.

(Laminated part)
The configuration of the laminated portion including the surface to be laminated for laminating the unidirectional prepreg is not particularly limited as long as the device is such that the unidirectional prepreg sprayed from the spray port is laminated on the surface to be laminated. The surface to be laminated is usually located below the spray port, and the one-way prepreg dropped from the spray port by gravity is set to be laminated on the surface to be laminated. The laminated portion may be, for example, a double belt press machine, a belt conveyor, a die (for example, a flat plate die having a shear edge structure, etc.), a table, or the like.

(Spraying process)
The manufacturing method of the present invention includes a spraying step of dropping a one-way prepreg onto the laminated surface from a spraying port located above the laminated surface by using an apparatus having at least a spraying portion and a laminated portion as described above. In the present specification, it is considered that one spraying step is performed by spraying one-way prepreg of a predetermined spraying amount (Xg) once from one spraying port. In that case, it is considered that one spraying step was performed on one section centered on a predetermined coordinate point on the laminated surface located below the center of the spraying port. The above-mentioned one section in which laminating is performed by one spraying step is also referred to as a laminating section below. Specifically, the spraying step is performed using the laminated surface having the size of the finally obtained fiber-reinforced thermoplastic resin sheet as one lamination section according to the desired size of the fiber-reinforced thermoplastic resin sheet. A thermoplastic resin sheet may be produced, or the surface to be laminated having the size of the finally obtained fiber-reinforced thermoplastic resin sheet is divided into two or more laminated sections, and two or more spraying steps are performed. Two thermoplastic resin sheets may be manufactured.

From the viewpoint of increasing the mechanical strength of the fiber-reinforced thermoplastic resin sheet, suppressing the variation in mechanical strength, and easily increasing the isotropic property, the number of spraying steps (ply) performed on one laminated section on the laminated surface. The number) is preferably 2 times or more, more preferably 3 times or more, and further preferably 4 times or more. The upper limit of the number of times of spraying to one laminated section is not particularly limited, and may be, for example, 50 times or less, preferably 20 times or less, and more preferably 10 times or less. Further, from the same viewpoint, it is preferable to divide the surface to be laminated per square meter into a stacking section of preferably 25 or more, more preferably 45 or more, still more preferably 100 or more, and perform spraying. Since the fiber-reinforced thermoplastic resin sheet may be continuously produced, the upper limit of the number of laminated sections on the surface to be laminated is not particularly limited.

In the spraying step, the weight per unit area of the surface to be laminated by one spraying (hereinafter, also referred to as "spraying grain") is the weight per unit area of the desired fiber-reinforced thermoplastic resin sheet (hereinafter, "" It may be set as appropriate according to (also referred to as "sheet marking"). From the viewpoint of easily increasing the strength and isotropic property of the fiber-reinforced thermoplastic resin sheet, it is preferably 1600 g / m ² or less, more preferably 1100 g / m ² or less. The lower limit of the sheet weight is not particularly limited, and may be, for example, about 300 g / m ² or more. Here, the spraying basis weight is calculated by dividing the spraying amount per spraying amount measured by the load cell of the spraying portion by the size of the laminated section.

In the spraying step, from the viewpoint of laminating the unidirectional prepregs so that the fiber directions are random, the distance from the laminated surface to the spray port (H mm, or less, “spray height” so that the value A is within the above-mentioned predetermined range. It is preferable to adjust (also referred to as "sa"). The distance from the laminated surface to the spray port is the distance between the position of the spray port where the one-way prepreg starts to fall and the position of the layered surface on which the dropped one-way prepreg is laminated. Specifically, for example, it is the distance of the portion shown as the spray height 10 in FIG. The distance is measured, for example, using a scale. The spray height (H mm) is appropriately set so that, for example, a value A in the above-mentioned predetermined range can be obtained according to the average volume of the unidirectional prepreg used in the manufacturing method of the present invention, the spray amount of the unidirectional prepreg, and the like. However, it is preferably 100 mm or more from the viewpoint of fully acting the providence of nature. Further, it is preferably 1000 mm or less from the viewpoint of suppressing the base material from spreading too wide.

In the production method of the present invention, the sprayed portion and / or the laminated portion may move continuously or intermittently. From the viewpoint of easily performing a plurality of spraying steps while maintaining the distance from the laminated surface to the spraying port, the spraying portion and / or the laminated portion is continuously or intermittently in a substantially horizontal direction with respect to the laminated surface. It is preferable to move.

By continuously or intermittently moving the spraying portion and / or the laminating portion and spraying and laminating the unidirectional prepreg, an isotropic laminate in the plane direction can be formed. When continuously manufacturing a thermoplastic resin sheet while continuously moving the spraying part or the laminated part in one direction, from the viewpoint of easily increasing productivity, two or more in parallel in the direction perpendicular to the moving direction. It is preferable to install a spray port. In this case, it is preferable to make the spraying interval (the interval for moving the spraying portion or the laminated portion) equal to the spacing between the adjacent spraying openings.

When the spraying part and / or the laminated part is moved intermittently, it is possible to spray even with one spraying port, and at this time, laminating is performed by adjusting the feed amount of the laminated part or the spraying part to a predetermined sheet width. You may.

In the case of batch production using a hydraulic press or the like, the spraying portion and / or the laminated portion is continuously or intermittently moved according to the desired size of the surface to be laminated until the laminate reaches a predetermined thickness. , It is preferable to repeat the spraying step. When spraying over a wide area, it is preferable to sequentially stack them in a grid pattern at equal spray intervals. In the case of continuous production using a double belt press or the like, it is preferable to increase the number of spraying portions by the number of sheets required for laminating a predetermined thickness. Further, it is preferable to spray the belts in a direction perpendicular to the traveling direction of the belt at equal intervals in the traveling direction of the belt according to the spacing of the spraying ports arranged in parallel.

(Laminated surface and laminated section)
In the manufacturing method of the present invention, the surface to be laminated may be divided into one or two or more laminated sections, and the spraying step may be performed in each laminated section. Specifically, as described above, even if a section having the desired size of the fiber-reinforced thermoplastic resin sheet is used as one laminated section on the surface to be laminated, a spraying step is performed to produce the thermoplastic resin sheet. Alternatively, the section having the desired size of the fiber-reinforced thermoplastic resin sheet may be divided into two or more laminated sections and sprayed twice or more to produce one thermoplastic resin sheet. From the viewpoint of easily obtaining a fiber-reinforced thermoplastic resin sheet having excellent isotropic properties, a section having a desired fiber-reinforced thermoplastic resin sheet size is divided into two or more laminated sections, and spraying steps are performed twice or more. It is preferable to produce one thermoplastic resin sheet.

により算出される値Ｃは、好ましくは１～５０、より好ましくは１～３０である。値Ｃが上記の範囲内である場合、隣り合う積層区画間での積層された一方向プリプレグの重なりが良好となりやすく、繊維強化熱可塑性樹脂シートの機械的強度のばらつきを抑制しやすい。 From the viewpoint that it is easy to manufacture a fiber-reinforced thermoplastic resin sheet having high strength and little variation in strength, from the size of each laminated section (Lmm ² ) and the distance from the laminated surface to the spray port (H mm). The following equation (3):

The value C calculated by is preferably 1 to 50, more preferably 1 to 30. When the value C is within the above range, the overlap of the laminated unidirectional prepregs between the adjacent laminated sections is likely to be good, and the variation in the mechanical strength of the fiber-reinforced thermoplastic resin sheet is likely to be suppressed.

The size of each laminated section is calculated as follows. For example, when the spraying step is performed using a section having the desired size of the fiber-reinforced thermoplastic resin sheet on the laminated surface as one laminated section, the size of the finally obtained fiber-reinforced thermoplastic resin sheet is laminated. It will be the size of the compartment. For example, when the spraying step is performed by dividing the section having the desired size of the fiber-reinforced thermoplastic resin sheet on the laminated surface into two or more laminated sections by using one spraying port, the spraying section and / Alternatively, it is necessary to move the laminated portion to the surface to be laminated in the x-axis and y-axis directions in the substantially horizontal direction and perform spraying twice or more. In this case, the product of the moving distances in the x-axis and y-axis directions is taken as the size of each laminated section. Further, when the spraying step is performed by dividing the section having the desired size of the fiber-reinforced thermoplastic resin sheet on the laminated surface into two or more laminated sections by using, for example, two or more spraying ports, the spraying step is performed. It is necessary to move the spraying portion and / or the laminated portion having two or more spraying ports to the surface to be laminated in the x-axis and / or y-axis directions in the substantially horizontal direction to perform spraying twice or more. In this case, the product of the distance between the spray ports and the moving distance in the x-axis and / or the y-axis direction is taken as the size of each laminated section. The shape of each laminated section may be appropriately determined according to the desired shape of the fiber-reinforced thermoplastic resin sheet, but when the one-way prepreg freely drops in the spraying step, it is basically centered on the spraying point. Since it spreads radially and the stacking is performed, it is preferable to spray the laminated section having a shape such as a square or a circle, and the moving distance and / or the distance between the spraying openings is set to be equal to each other so that the laminated section becomes a square. It is more preferable to do so.

Examples of the method of dividing the surface to be laminated into one or two or more laminated sections and performing the spraying step in each laminated section to produce a fiber-reinforced thermoplastic resin sheet include the following embodiments (1) to (3). ..

(1) A mode in which the surface to be laminated is divided into one laminated section and a spraying step is performed using one spray port. In this embodiment, specifically, the size of the desired fiber-reinforced thermoplastic resin sheet on the surface to be laminated. A thermoplastic resin sheet is manufactured by performing a spraying step using the section having a fiber as one laminated section. The number of spraying times in one laminated section may be once or may be two or more, but it is preferable to perform the spraying step two or more times in one laminated section.

(2) A mode in which the surface to be laminated is divided into two or more laminated sections and a spraying step is performed using one spraying port. The compartments having a size are divided into two or more n laminated compartments, and a spraying step is performed in each laminated compartment to produce a thermoplastic resin sheet. In this embodiment, the spraying portion and / or the laminated portion is continuously or intermittently moved in a substantially horizontal direction with respect to the surface to be laminated, and the spraying step is performed in each of the n laminated sections. Here, the number of times of spraying in one laminated section may be once or twice or more, but performing the spraying step twice or more in one laminated section has high strength and has high strength. It is preferable from the viewpoint that it is easy to efficiently manufacture a fiber-reinforced thermoplastic resin sheet with little variation in strength.

(3) A mode in which the surface to be laminated is divided into two or more laminated sections and a spraying step is performed using two spray ports. In this embodiment, specifically, the desired fiber-reinforced thermoplastic resin sheet on the surface to be laminated. The compartments having a size are divided into two or more n laminated compartments, and a spraying step is performed in each laminated compartment to produce a thermoplastic resin sheet. In this embodiment, the spraying portion and / or the laminated portion is continuously or intermittently moved in a substantially horizontal direction with respect to the surface to be laminated, and the spraying step is performed in each of the n laminated sections. Here, the number of times of spraying in one laminated section may be once or twice or more, but performing the spraying step twice or more in one laminated section has high strength and has high strength. It is preferable from the viewpoint that it is easy to efficiently manufacture a fiber-reinforced thermoplastic resin sheet with little variation in strength.

The method of performing the spraying step m times for each of the n laminated sections will be described in more detail with respect to the above-mentioned aspects (2) and (3) (where n and m are integers of 2 or more). ). In this case, for example, the following aspects (a) and (b) can be considered. As an aspect of (a), after performing one spraying step in one section of n laminated sections, the spraying section or the laminated section is moved at a predetermined distance in the x-axis direction or the y-axis direction to be next. Move to one section and perform one spraying step in the next section. This was performed for all n laminated sections, and after performing a total of n spraying steps, a second spraying step was performed in each laminated section in the same manner, and a total of 2 × n spraying steps were performed. I do. Then, a method of repeating the above-mentioned steps until the number of times of spraying in each laminated section becomes m times can be mentioned. As an aspect of (b), after performing m times of spraying steps in one section of n laminated sections, the spraying section or the laminated section is moved at a predetermined distance in the x-axis direction or the y-axis direction to be next. A method of moving to one section and performing m spraying steps in the next section can be mentioned. The aspect (a) is preferable from the viewpoint that it is easy to efficiently manufacture a fiber-reinforced thermoplastic resin sheet having high strength and little variation in strength.

(Laminate)
In the production method of the present invention, a unidirectional prepreg laminate can be obtained on the surface to be laminated through the spraying step as described above. The height of the laminate is preferably 5 to 50 mm, more preferably 5 to 30 mm, still more preferably 5 to 15 mm from the viewpoint of suppressing voids contained during sheet molding. Here, the height of the laminate can be measured by a scale as the average height.

[Heating process]
A fiber-reinforced thermoplastic resin sheet can be produced by heating the laminate of unidirectional prepregs obtained as described above. Pressurization may be performed together with heating. From the viewpoint of easily increasing the mechanical strength of the fiber-reinforced thermoplastic resin sheet, it is preferable to heat and pressurize the laminate to produce the fiber-reinforced thermoplastic resin sheet. The heating temperature in the heating step for producing the fiber-reinforced thermoplastic resin sheet is preferably 100 to 300 ° C. When pressurizing, the pressure at the time of pressurization is preferably 0.1 to 10 MPa, more preferably 0.5 to 5.0 MPa. Specifically, for example, a method of passing a one-way prepreg laminate deposited and laminated on a conveyor such as a steel belt between heat rolls together with a steel belt and heating, pressurizing, or intermittently pressing, or a belt press. A method of continuously heating and cooling with a heating and cooling method, a method of preheating with a far-infrared heater and then cold pressing, a method of using a heating and cooling press, and the like can be mentioned. The temperature of the heating step for producing the fiber-reinforced thermoplastic resin sheet is preferably 100 ° C. or higher higher than the glass transition temperature of the resin. As a result, the fluidity of the resin becomes good, and it becomes possible to fill the gap existing between the laminated prepregs by further applying pressure. As a result, it becomes easy to reduce the voids of the obtained molded product.

[Embodiment of the manufacturing method of the present invention]
Next, the production method of the present invention will be described in detail by the following embodiments. In the following, in explaining the configuration shown in the drawings, terms indicating directions such as "up" and "down" and other terms including them are used, but the purpose of using these terms is used. Is to facilitate understanding of embodiments through drawings. Therefore, these terms do not necessarily indicate the direction in which the embodiments of the present invention are actually used, and the terms do not limit the technical scope of the invention described in the claims.

(First Embodiment)
A first embodiment of the manufacturing method of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic view of a spraying portion and a laminated portion of the apparatus used in this embodiment. As shown in FIG. 1, the apparatus used in the manufacturing method of the present embodiment has one spray port for spraying the one-way prepreg, and the weight (Xg) of the one-way prepreg dropped from one spray port at one time. It has one measuring unit 2 for adjusting, a storage tank 3 for storing the prepreg, and a spraying unit 5 including a transport unit 4 for transporting the prepreg from the storage tank 3 to the measuring unit 2. In the present embodiment, the surface to be laminated is divided into 25 laminated sections as shown in FIG. 2, and the spraying step is performed three times in each laminated section to produce a fiber-reinforced thermoplastic resin sheet. Specifically, as shown in FIG. 2, after the first spraying step is performed in the laminated section shown as a1, the spraying portion and / or the laminated portion moves in the x-axis or y-axis direction in FIG. , The second spraying step is performed in the adjacent laminated section shown as a2. Then, after performing one spraying step (a total of 25 spraying steps) in each of the 25 laminated sections, the second spraying step in the section is then performed in the laminated section shown as a26. Is carried out in each of the 25 laminated sections. For example, this spraying step is repeated 3 times, and a total of 75 spraying steps are performed to produce a fiber-reinforced thermoplastic resin sheet having 3 plies. In this embodiment, the size of each laminated section (Lmm ² ) is calculated from the product of the distance for moving the spray port in the x-axis direction and the distance for moving the spray port in the y-axis direction between the spraying steps. As shown in FIG. 2, it is preferable to set the moving distances in the x-axis and y-axis directions to be equal so that the laminated section is square, from the viewpoint of easily enhancing the isotropic property of the fiber-reinforced thermoplastic resin sheet.

(Second Embodiment)
A second embodiment of the manufacturing method of the present invention will be described with reference to FIGS. 1, 3 and 4. FIG. 1 is as described for the first embodiment. As shown in FIG. 3, the apparatus used in the manufacturing method of the present embodiment has a structure in which five spraying portions 5 shown in FIG. 1 are arranged in parallel. In the present embodiment, it is preferable that the laminate laminated on the surface to be laminated 6 is obtained by a plurality of spraying steps, for example, three spraying steps are performed in one laminated section. Is preferable. A specific spraying process will be described with reference to FIG. FIG. 4 shows a schematic view in which the surface to be laminated is divided into 25 laminated sections. The apparatus used in the manufacturing method of the present embodiment has five spray ports, and if each spray port is a spray port a to e, the one-way prepreg sprayed from the spray port a by the first spraying step is It is laminated in the stacking section described as a1 shown in FIG. Similarly, the one-way prepregs sprayed from each of the spray ports b to e in the first spraying step are laminated in the stacking section described as b1 to e1 shown in FIG. 4, respectively. In the present embodiment, the distance between the adjacent spray ports is set so that the unidirectional prepregs sprayed from the five spray ports a to e overlap each other and one laminate can be obtained. Although it is described as the first spraying step, in this case, since one spraying step is performed at each of the five spraying ports, the number of spraying steps is counted as five. The same applies to the following. After the first spraying step, the laminated portion 7 moves in the direction opposite to the arrow direction in FIG. 4 by a predetermined distance, and / or the spraying portion 5 moves in the direction of the arrow in FIG. 4 by a predetermined distance. Then, it is laminated in the stacking section shown as the following a2 to e2. In the present embodiment, the one-way prepreg laminated in the sections a1 to e1 sprayed in the first spraying step and the one-way prepreg laminated in the sections a2 to e2 sprayed in the second spraying step. The moving distance and / or moving speed of the spraying portion or the laminated portion is set so that the above and the two overlap each other to obtain one laminated product. After performing the first spraying step in each of the 25 laminated sections, this operation was repeated 3 times, and finally 15 spraying steps were performed from each of the 5 spray ports, and the square shown in FIG. 4 Laminates can be obtained. In this embodiment, the size of each laminated section (Lmm ² ) is derived from the product of the distance between the centers of the spray ports and the distance to move the sprayed portion or the laminated portion in the direction of the arrow in FIG. 4 or the opposite direction. Calculated. As shown in FIG. 4, it is preferable to set the spray port spacing and the moving distance to be equal so that the laminated section is square, from the viewpoint of easily enhancing the isotropic property of the fiber-reinforced thermoplastic resin sheet.

As a modification of the present embodiment, the number of spray ports may be more than 5 or less than 5. The five spray ports may be set at intervals such that the unidirectional prepregs sprayed from each do not overlap each other. In the above embodiment, it is understood that the spraying step is performed three times for one laminated section of the laminated surface, and it is described that the number of plies in the fiber-reinforced thermoplastic resin sheet in this case is three times. .. The number of spraying steps on one laminated surface may be less than 3 times or more than 3 times. The movement of the spray and / or laminate may be intermittent or continuous. Further, the number of storage tanks in the spraying portion may be one for one spraying port or one for a plurality of spraying ports.

(Third Embodiment)
The production method of the third embodiment of the present invention will be described with reference to FIGS. 1 and 5. FIG. 1 is as described for the first embodiment. Although a schematic view of the entire apparatus used in the present embodiment is not shown, it has a configuration in which two spraying portions shown in FIG. 1 are arranged in parallel and a laminated portion is located below the spraying port. Also in this embodiment, the laminate to be laminated on the surface to be laminated 6 is preferably obtained by a plurality of spraying steps, for example, one spraying step from each spraying port to one laminated section. Therefore, it is preferable that after laminating on a total of two laminated sections, the spraying portion and / or the laminating portion moves to further spray and laminate on the adjacent laminated surfaces. A specific spraying process will be described with reference to FIG. FIG. 5 shows a schematic view in which the surface to be laminated is divided into 16 laminated sections. The apparatus used in the manufacturing method of the present embodiment has two spray ports, and if each spray port is a spray port a and b, the one-way prepreg sprayed from the spray port a by the first spraying step is It is laminated in the stacking section described as a1 shown in FIG. Similarly, the one-way prepreg sprayed from the spray port b in the first spraying step is laminated in the stacking section described as b1 shown in FIG. In the present embodiment, the distance between the adjacent spray ports is set so that the unidirectional prepregs sprayed from the two spray ports a and b overlap each other to obtain one laminate. Then, the laminated portion 7 moves in the direction opposite to x in FIG. 5, and / or the sprayed portion 5 moves in the x direction in FIG. 5, whereby the laminated section shown by the following a2 and b2 is shown. The second spraying step is performed in. Next, the laminated portion 7 moves in the x-direction and the y-direction in FIG. 5, and / or the spraying portion 5 moves in the direction opposite to the x-direction and the direction opposite to the y-direction in FIG. , The one-way prepreg sprayed from the spray ports a and b by the next third spraying step is laminated on the surface to be laminated described as a3 and b3 shown in FIG. 5, respectively. In the present embodiment, the one-way prepreg sprayed in the first spraying step and the one-way prepreg sprayed in the second spraying step overlap each other so that one laminate can be obtained. The interval, the moving distance and / or the moving speed of the spraying part or the laminated part are set. In this way, the spraying step is finally performed 24 times from each of the two spraying ports, and the laminate as shown in FIG. 5 can be obtained. As shown in FIG. 5, it is preferable to set the spray port spacing and the moving distance to be equal so that the laminated section is square, from the viewpoint of easily enhancing the isotropic property of the fiber-reinforced thermoplastic resin sheet.

[Fiber reinforced thermoplastic resin sheet]
The fiber-reinforced thermoplastic resin sheet obtained by the production method of the present invention is a random laminate of unidirectional prepregs containing reinforced fibers and a thermoplastic resin, and includes reinforced fibers and a thermoplastic resin. As used herein, the random laminate of unidirectional prepregs is a laminate in which a plurality of unidirectional prepregs are laminated so that the fiber directions in each unidirectional prepreg are random to each other. The reinforcing fibers contained in the one-way prepreg are usually opened reinforcing fibers.

As described above, the fiber-reinforced thermoplastic resin sheet obtained by the production method of the present invention has no portion where the fiber orientation is locally excessive, and is oriented in a direction different from the fiber axial direction via the fiber. Stress transfer is uniform. It is considered that the fiber-reinforced thermoplastic resin sheet obtained by the production method of the present invention having such characteristics has little variation in strength in all directions. Therefore, when a molded product is manufactured from a fiber-reinforced thermoplastic resin sheet, the moldability is improved, and it is possible to manufacture a homogeneous molded product with little variation in strength.

The mechanical strength such as the tensile strength of the fiber-reinforced thermoplastic resin sheet varies depending on the type of fiber used for manufacturing the fiber-reinforced thermoplastic resin sheet, the type of resin, the fiber volume content (Vf), etc., and the fiber-reinforced thermoplastic resin. The above can be appropriately selected and set according to the strength desired for the molded product obtained from the sheet. According to the manufacturing method of the present invention, relatively high mechanical strength can be achieved as compared with the thermoplastic resin sheet manufactured by the method not according to the manufacturing method of the present invention. Further, according to the manufacturing method of the present invention, it is possible to suppress variations in mechanical strength as described above. Specifically, the coefficient of variation (CV value) of the tensile strength of the fiber-reinforced thermoplastic resin sheet is preferably less than 20.0%, more preferably 19.0% or less, still more preferably 15.0% or less, particularly. It is preferably 10.0% or less. The coefficient of variation (CV value) of the tensile elastic modulus is preferably 20.0% or less, and more preferably 10.0% or less. The lower the coefficient of variation (CV value), the smaller the variation, and the lower limit thereof is not particularly limited and may be 0% or more. The coefficient of variation is the coefficient of variation (CV value) = standard deviation / average value × 100 (%) from the average tensile strength measured by the method described later and the standard deviation of the results of at least five measurements of the tensile strength. Calculated by the formula.

The average tensile strength of the fiber-reinforced thermoplastic resin sheet is measured according to JIS K 7164 using a precision universal testing machine manufactured by Shimadzu Corporation, and the average value of at least 5 measurements is taken as the average tensile strength. The details of the measurement conditions are as described in, for example, Examples.

The number of layers of the unidirectional prepreg laminated in the thickness direction of the fiber-reinforced thermoplastic resin sheet may be appropriately set depending on the thickness of the fiber-reinforced thermoplastic resin sheet, but is preferably 17 to 35 layers, more preferably 20 to 35. It is a layer. It is preferable that the number of layers of the one-way prepreg laminated in the thickness direction is at least the above lower limit because it is easy to reduce variations in physical properties. Further, it is preferable that the number of layers of the unidirectional prepreg laminated in the thickness direction is not more than the above upper limit from the viewpoint of stable production of the tape base material. The number of layers of the unidirectional prepreg laminated in the thickness direction of the fiber-reinforced thermoplastic resin sheet obtained by the production method of the present invention is obtained from an image obtained by observing a cross section of the fiber-reinforced thermoplastic resin sheet using an electronic or optical microscope. , Measured visually.

The void ratio of the fiber-reinforced thermoplastic resin sheet is measured according to JIS-7075 from the viewpoint of easily increasing the moldability and mechanical strength of the fiber-reinforced thermoplastic resin sheet, and is preferably 0 to 1.0%, more preferably 0. It is ~ 0.5% or less.

The thickness of the fiber-reinforced thermoplastic resin sheet may be appropriately changed depending on the thickness desired for the finally obtained molded product. The thickness of the fiber-reinforced thermoplastic resin sheet is measured using a micrometer.

[One-way prepreg]
The one-way prepreg used in the production method of the present invention contains reinforced fibers and a thermoplastic resin. In the production method of the present invention, one kind of one-way prepreg may be used, or for example, two or more kinds of one-way prepregs different from each other in the kind and content of the reinforcing fiber and / or the thermoplastic resin are used. You may.

(Reinforcing fiber)
Examples of the reinforcing fiber include organic fiber such as aramid fiber, polyethylene fiber and polyparaphenylene benzoxador (PBO) fiber, glass fiber, carbon fiber, silicon carbide fiber, alumina fiber, tyranno fiber, genbuiwa fiber and ceramic fiber. Examples thereof include inorganic fibers, metal fibers such as stainless fibers and steel fibers, and reinforced fibers using boron fibers, natural fibers, and modified natural fibers as fibers. As these reinforcing fibers, a reinforcing fiber composed of several thousand or more filaments is preferable, and a reinforcing fiber composed of 3000 to 60,000 filaments is used for producing a unidirectional prepreg contained in a fiber-reinforced thermoplastic resin sheet. It is preferably used. From the viewpoint of the strength and rigidity of the fiber-reinforced thermoplastic resin sheet obtained by the production method of the present invention, the reinforcing fiber is more preferably carbon fiber. The one-way prepreg used in the production method of the present invention may contain one kind of reinforcing fiber or may contain two or more kinds of reinforcing fibers in combination. The reinforcing fiber contained in the unidirectional prepreg is preferably an opened reinforcing fiber, and more preferably a reinforcing fiber opened to a thickness of 10 μm to 50 μm.

In a preferred embodiment in which the reinforcing fiber is a carbon fiber, the carbon fiber may be a pitch-based carbon fiber or a PAN-based carbon fiber. From the viewpoint of handleability, it is preferable that the carbon fiber is a PAN-based carbon fiber.

The presence or absence of twist in the reinforced fiber is not particularly limited, but from the viewpoint of easily increasing the penetration of the matrix resin in manufacturing the unidirectional prepreg and increasing the strength of the fiber reinforced thermoplastic resin sheet, the twist is small or twisted. No reinforcing fiber is preferred. From the same viewpoint, the number of twists of the reinforcing fibers is preferably 1 time / m or less, more preferably 0.5 times / m or less, and even more preferably 0.3 times / m or less.

When carbon fiber is used as the reinforcing fiber, the carbon fiber is often wound around a bobbin, which is a cylindrical tube with a constant traverse width. The filament diameter of one carbon fiber is usually 5 to 8 μm, and a plurality of carbon fibers have a predetermined number of filaments (specifically, 1000 (1K), 3000 (3K), 6000 (6K), 12000). A fiber bundle (carbon fiber tow) assembled flatly with (12K), 15,000 (15K), 18,000 (18K), 24,000 (24K), 30,000 (30K), 60,000 (60K)) is preferable. It will be used. The number of filaments of the carbon fiber may be appropriately changed depending on the desired width and thickness of the opened carbon fiber and the unidirectional prepreg used in the present invention, but is preferably 3000 to 60,000 from the viewpoint of productivity. Books, more preferably 6000 to 24000. It is preferable that the number of filaments is not more than the above upper limit because it is easy to suppress the generation of voids inside the manufactured prepreg. Further, it is preferable that the number of filaments is not less than the above lower limit because it is easy to suppress fluffing and cracking of the prepreg due to single yarn breakage at the time of opening the fiber.

(Thermoplastic resin)
The thermoplastic resin contained in the unidirectional prepreg is not particularly limited as long as it is a resin having thermoplasticity. The thermoplastic resin is a thermoplastic resin or a polyamide resin (for example, nylon 6, nylon 12, nylon) which is a polymer of a field-polymerized compound in which polymerization proceeds in the process of producing a prepreg after impregnating the reinforcing fiber. 66, nylon 46, etc.), polyester resin (eg polyethylene terephthalate, polybutylene terephthalate, etc.), polyolefin resin (eg polyethylene, polypropylene, etc.), polyether ketone resin, polyphenylene sulfide resin, polyetherimide resin, polycarbonate resin, heat. Examples thereof include a resin having a thermoplastic property obtained by modifying a curable resin, a copolymer thereof, a modified product, and a resin obtained by blending two or more kinds thereof. The one-way prepreg may contain one type of thermoplastic resin, or may contain two or more types of thermoplastic resins in combination. In addition to the above-mentioned thermoplastic resin, an elastomer and / or a rubber component may be added to the unidirectional prepreg or the fiber-reinforced thermoplastic resin sheet from the viewpoint of improving impact resistance.

The thermoplastic resin contained in the unidirectional prepreg has a melt viscosity of preferably 10 to 3500 mPa · s in a state of being melted by heating to a melting point or a glass transition temperature or higher. The melt viscosity of the thermoplastic resin is measured by a viscometer.

The thermoplastic resin contained in the unidirectional prepreg is preferably a solvent-soluble thermoplastic resin from the viewpoint of easily enhancing the impregnation property into the reinforcing fibers. Examples of the solvent include organic solvents, and specific examples thereof include polar solvents such as DNP and NMP, preferably ketone solvents, and more preferably methyl ethyl ketone. In this case, the reinforcing fibers can be impregnated by using a varnish obtained by dissolving a thermoplastic resin in a solvent.

(Manufacturing method of one-way prepreg)
Examples of the method of impregnating the reinforcing fiber with the thermoplastic resin include a method using a solvent-soluble resin bath and a molten resin impregnated bath (hot melt method or dry method).

When the thermoplastic resin is impregnated, the thermoplastic resin impregnated in the reinforcing fibers is then solidified. The heating temperature may be appropriately changed depending on the type of reinforcing fiber used, the type of solvent when a resin solution is used, the volatile temperature, etc., but in the case of an amorphous resin, the temperature is 100 ° C. or higher higher than the glass transition temperature. It is preferable to process with. In the case of a crystalline resin, it is preferable to process it at a temperature higher than the melting point by 30 ° C. or higher.

The one-way prepreg tape obtained as described above can be cut to produce a one-way prepreg. The cutting method is not particularly limited, and a cutter such as a pelletizer, a guillotine method, or a Kodak method may be preferably used. A unidirectional prepreg (chopped prepreg) can be produced by using these to cut a unidirectional prepreg tape to a desired fiber length (for example, 10 to 30 mm).

<Molded body>
(Manufacturing method of molded product)
The fiber-reinforced thermoplastic resin sheet obtained by the production method of the present invention has high strength and moldability, and has little variation in strength, and is suitably used as an intermediate material for producing various fiber-reinforced plastic molded bodies. Can be done. Such a fiber-reinforced thermoplastic resin sheet is also referred to as a stampable sheet, and is a material that substitutes for sheet metal. Here, the conventionally known prepreg includes a portion in which the fiber orientation is excessive. In order to reduce the influence of excessive fiber orientation, it was necessary to make the sheet thicker. However, as described above, the fiber-reinforced thermoplastic resin sheet produced by the production method of the present invention is a thin layer because there are extremely few or no portions where the fiber orientation is locally excessive. However, it has both high strength and plasticity, and there is little variation in strength. Therefore, it is possible to manufacture a molded product having sufficient strength even under conditions of lower temperature, lower pressure, and shorter time than before. Since molding is possible under such mild conditions, it is possible to avoid losing randomness during molding.

As a method for producing a molded product using a fiber-reinforced thermoplastic resin sheet, press molding can be mentioned. Press molding is a method of manufacturing a molded product by bending, shearing, compressing, or the like by bending, shearing, compressing, or the like on a fiber-reinforced thermoplastic resin sheet using a processing device, a mold, or the like. Examples of the molding form include deep drawing, flange, call gate, edge curling, and stamping. Examples of the press forming method include a die pressing method, a heating / cold pressing method, a cold pressing method, and an autoclave method used for forming a large member (for example, an aircraft member). For example, when aiming for application in an automobile production line, the fiber-reinforced thermoplastic resin sheet is preheated at a temperature equal to or higher than the melting point of the thermoplastic resin contained in the sheet or the glass transition temperature to soften the sheet. After heating, this can be conveyed to a molding die provided in a press machine and pressed to manufacture a molded product. By setting the mold temperature at this time to be equal to or lower than the melting point of the thermoplastic resin contained in the sheet or the glass transition temperature, it is possible to cure the material at the same time as shaping the material, so that molding in a high cycle can be performed. It will be possible.

Since the resin contained in the fiber-reinforced thermoplastic resin sheet obtained by the production method of the present invention is a thermoplastic resin, the fiber-reinforced thermoplastic resin sheet is heated and the resin is melted to have a melting point or a glass transition temperature or lower. It is also suitable for stamping molding, in which the material is put into the mold set in and pressed to transform it into the shape of the molding mold and cool it at the same time. Further, since the sheet is particularly excellent in moldability, it is also suitable for molding a deep-drawn shape, which is difficult to mold when a conventional fiber reinforced plastic is used.

(Molded body)
The use of the molded product produced from the fiber-reinforced thermoplastic resin sheet obtained by the production method of the present invention is not limited in any way, and for example, electric and electronic equipment parts, columns, reinforcing materials and the like used for OA equipment and mobile phones and the like. Examples include building materials, structural parts for automobiles, parts for aircraft, and the like. The molded product produced from the fiber-reinforced thermoplastic resin sheet obtained by the production method of the present invention has high strength with little variation. Further, it can be used not only as a sheet but also as a reinforcing material as a one-way material.

Hereinafter, the present invention will be specifically described with reference to Examples, but these do not limit the scope of the present invention. First, the evaluation method will be described.

<Measurement of average tensile strength and coefficient of variation>
The average tensile strength of the fiber-reinforced thermoplastic resin sheet was measured according to JIS K 7164 using a precision universal testing machine manufactured by Shimadzu Corporation, Autograph AG-100kNXplus. Specifically, from the flat plate-shaped fiber-reinforced thermoplastic resin sheets obtained in Examples and Comparative Examples described later, the length is 250 ± 1.0 mm in an arbitrary length direction and a width direction perpendicular to it. A rectangular sample with a width of 35 ± 0.2 mm was cut out and used as a measurement sample. As described above, 5 measurement samples were prepared. For the measurement sample, the tensile strength was measured at a chuck distance (distance between gauge points) of 150 mm and a crosshead speed of 1.0 mm / min according to JIS K 7164, and the average value of the tensile strength obtained for the five measurement samples was averaged. The tensile strength was used. Further, the standard deviation was calculated from the result of the tensile strength, and the coefficient of variation was calculated from the formula of the coefficient of variation CV value [%] = (invariant standard deviation / mean value) × 100.

<Measurement of average volume (Vmm ³ ) per unidirectional prepreg>
The volume per unidirectional prepreg was calculated from the lengths of the unidirectional prepreg in the fiber direction, the width direction orthogonal to the fiber direction, and the thickness direction using a digital caliper, and the product thereof. The above measurement was performed for each of 10 arbitrarily selected one-way prepregs, and the average value of the obtained results was taken as the average volume per one-way prepreg.

<Measurement of weight (Xg) of one-way prepreg dropped from one spray port at one time>
Gram measurement was performed and measured in the load cell of the weighing unit provided in the spraying unit.

<Measurement of distance (Hmm) from the laminated surface to the spray port>
The distance from the laminated surface to the spray port was measured on a scale.

<Measurement of weight per unit area (spraying basis weight) of the laminated surface by one spraying>
The spraying basis weight was calculated by dividing the weight of the base material (spraying amount) in one spraying step by the size of each laminated section.

<Measurement of fiber volume content of fiber reinforced thermoplastic resin sheet>
Measured according to JIS K 7075.

<Total number of sprays per unit area>
The number of sprays required to produce the fiber-reinforced thermoplastic resin sheet was calculated by dividing by the area of the fiber-reinforced thermoplastic resin sheet.

[Manufacturing Example 1: Manufacture of unidirectional prepreg tape (a)]
A continuous fiber bundle of 800tex, 12,000 filament carbon fiber (Toray Co., Ltd., Torayca (registered trademark) T700SC-12000) and an emulsion resin (Matsumoto Yushi Pharmaceutical Co., Ltd., PPE-104) are used for the concentration of the resin component. The sizing agent was continuously immersed in an emulsion tank containing a sizing agent mother liquor diluted with tap water so as to have a value of 0.2% by weight, and the sizing agent was applied to the carbon fibers. At this time, the fiber bundle was thinly spread in the emulsion tank through several guides. Then, the fiber-opening tape was obtained by drying while removing the excess water impregnated in the carbon fiber with a hot roller at 100 ° C. The width of the obtained spread tape was 15 mm to 17 mm.

As a matrix resin to be impregnated in the spread tape, a composition containing a field-polymerized epoxy compound (manufactured by Nagase ChemteX Corporation, DENATITE XNR6850V, 55 parts by weight of bisphenol A type epoxy compound having a weight average molecular weight of 200 to 1000, 30 parts by weight of bisphenol A). 100 parts by weight of the composition (including 15 parts by weight of methyl ethyl ketone) and 8 parts by weight of the curing agent (DENATITE XNH6850V, organic phosphorus compound manufactured by Nagase ChemteX Corporation) were thoroughly mixed and stirred to form a composition for a matrix resin (including 15 parts by weight of methyl ethyl ketone). Resin paste) was obtained. The composition for matrix resin is applied from both sides of the spread tape so that the fiber volume content (Vf) is 40%, and immediately after the application, both sides of the tape are pressed by a release belt and heated via a guide. -By cooling, the bisphenol A type epoxy compound and bisphenol A polymerize, and the smoothness is high. A polymer of the bisphenol A type epoxy compound and bisphenol A, which is a field-polymerized epoxy resin (thermoplastic epoxy resin). A unidirectional prepreg tape was obtained that was fully impregnated with.

[Manufacturing Example 2: Manufacture of unidirectional prepreg tape (b)]
A continuous fiber bundle of 800tex, 12,000 filament carbon fibers (TAIRYFIL TC36P-12K, manufactured by Formosa Plastics Corporation) is continuously immersed in a water tank containing tap water, and at this time, several guides are used in the water tank. The fiber bundle was thinly spread through the cloth. Then, the fiber-opening tape was obtained by drying while removing the excess water impregnated in the carbon fiber with a hot roller at 100 ° C. The width of the obtained spread tape was 15 mm to 17 mm.

As a matrix resin to be impregnated in the spread tape, a composition containing a field-polymerized epoxy compound (manufactured by Nagase ChemteX Corporation, DENATITE XNR6850V, 55 parts by weight of bisphenol A type epoxy compound having a weight average molecular weight of 200 to 1000, 30 parts by weight of bisphenol A). 100 parts by weight of the composition (including 15 parts by weight of methyl ethyl ketone) and 8 parts by weight of the curing agent (DENATITE XNH6850V, organic phosphorus compound manufactured by Nagase ChemteX Corporation) were thoroughly mixed and stirred to form a composition for a matrix resin (including 15 parts by weight of methyl ethyl ketone). Resin paste) was obtained. The composition for matrix resin is applied from both sides of the spread tape so that the fiber volume content (Vf) is 40%, and immediately after the application, both sides of the tape are pressed by a release belt and heated via a guide. -By cooling, the bisphenol A type epoxy compound and bisphenol A polymerize to form a polymer (thermoplastic epoxy resin) of the above bisphenol A type epoxy compound and bisphenol A, which is a field-polymerized epoxy resin with high smoothness. A fully impregnated, one-way prepreg tape was obtained.

[Manufacturing Example 3: Manufacture of unidirectional prepreg (1)]
The one-way prepreg tape (a) obtained in Production Example 1 was cut to a length of 29 mm in the fiber direction using a cutting device to obtain a one-way prepreg (1) (one-way chopped prepreg).

[Manufacturing Example 4: Manufacture of unidirectional prepregs (2) to (4)]
The unidirectional prepregs (2) to (4) are obtained by cutting the unidirectional prepreg tape (b) obtained in Production Example 2 to a length of 29 mm, 26 mm or 13 mm in the fiber direction using a cutting device, respectively. rice field.

With respect to the one-way prepregs (1) to (4) obtained as described above, the average volume (Vmm ³ ) per one-way prepreg, the average length in the fiber direction, and the average length in the width direction according to the above method. And the average thickness was measured. The results are shown in Table 1 below.

[Spraying part]
The spraying portion in the apparatus used in the examples and comparative examples described later will be described with reference to FIG. As shown in FIG. 1, the device adjusts the weight (Xg, also referred to as “spray amount”) of the one-way prepreg to be dropped from one spray port 1 for spraying the one-way prepreg at one time. It is provided with a measuring unit 2 for storing the prepreg, a storage tank 3 for storing the prepreg, and a spraying unit 5 including a transport unit 4 for transporting the prepreg from the storage tank 3 to the measuring unit 2. The spraying portion 5 was installed so that the distance (H mm, spraying height 10) from the laminated surface 6 to the lower end of the spraying port 1 was a predetermined height. In the spraying section 5, the unidirectional prepreg in the storage tank 3 is transported to the measuring section 2 via the transport section 4, and the weight of the unidirectional prepreg transported into the lightweight section 2 reaches a predetermined spraying amount (Xg). When the weight reached a certain level, the transportation was stopped, the spray port 1 was opened, and the unidirectional prepreg with a predetermined spray amount was set to be sprayed on the laminated surface 6. In addition, the spraying section was set so that one spraying was performed intermittently at a predetermined spraying interval. Below each spray port 1, as shown in FIG. 1, a laminated portion 7 provided with a surface to be laminated 6 for laminating a unidirectional prepreg was located.

[Example 1: Production of fiber-reinforced thermoplastic resin sheet (1)]
(Device)
In Example 1, a device as shown in FIG. 3 in which five spraying portions 5 shown in FIG. 1 are lined up was used. In such a device, the distance 11 (also referred to as “spraying port spacing”) between the centers of adjacent spraying ports was set to 62 mm. In Example 1, a double belt press machine as shown in FIG. 6 was used as the laminated portion 7, and the upper surface of the lower belt 12 of the double belt press machine was used as the laminated surface 6. The lower belt 12 is set to continuously move in the direction of the arrow in FIG. 6 at a predetermined speed (also referred to as “layered surface moving speed”). Using such an apparatus, the surface to be laminated was divided into the laminated sections shown in FIG. 4 and a spraying step was performed to produce a fiber-reinforced thermoplastic resin sheet (1).

(Manufacturing conditions)
Using the one-way prepreg (1), a fiber-reinforced thermoplastic resin sheet (1) was manufactured under the following conditions.
Number of spray ports: 5 Spray amount (Xg): 3.90 g
Spray height 10 (Hmm): 200mm
Spraying port spacing: 62 mm
Interval of spraying process: 18.6 seconds Movement speed of laminated surface: 200 mm / min Total number of laminated sections: 25 sections Size of each laminated section (Lmm ² ): 3844 mm ²
Number of spraying steps for one laminated section (hereinafter, also referred to as Ply number): 3 times Spraying basis weight: 1014 g / m ²
When the interval between the spraying steps is 18.6 seconds and the moving speed of the laminated surface is 200 mm / min as described above, the moving distance between the spraying steps of the laminated surface is (18.6/60) × 200. = 62 mm. As described above, the spray port spacing is also 62 mm. Therefore, the size (Lmm ² ) of each laminated section is calculated as 62 mm × 62 mm = 3844 mm ² . Further, the spraying process is performed three times for one laminated section, and in this case, the number of plies is three times. The laminate 9 obtained by this spraying step had a height of 15 mm. As shown in FIG. 6, the laminate 9 is heated at a temperature of 150 ° C. for 10 minutes while niping between the upper belt 13 and the lower belt 12 set so that the gap is 2.0 mm. The fiber-reinforced thermoplastic resin sheet (1) was obtained by pressing and cooling while applying a pressure of 20 bar at room temperature. The width of the obtained fiber-reinforced thermoplastic resin sheet (1) was 310 mm, the thickness was 2.0 mm, and the weight per unit area (sheet basis weight) was 3041 g / m ² .

[Example 2: Production of fiber-reinforced thermoplastic resin sheet (2)]
(Device)
In Example 2, an apparatus having one spraying portion 5 as shown in FIG. 1 was used. In Example 2, a sedimentary board 14 as shown in FIG. 7 was used as the laminated portion 7. Using such an apparatus, the surface to be laminated was subjected to a spraying step on 64 laminated sections as shown in FIG. 8, and a fiber-reinforced thermoplastic resin sheet (2) was manufactured. Specifically, after performing one spraying step with the sedimentary disc 14 shown in FIG. 7 stopped, the sedimentary disc 14 is moved by a distance of 40 mm in the X-axis direction in FIG. 7 and again 1 The spraying step was performed several times, and the depositor 14 was further moved by a distance of 40 mm in the X-axis direction and / or the y-axis direction in FIG. This step (1 spray + 1 deposit move) was performed in 64 laminated sections, and this was repeated 3 times. (In other words, the number of spraying steps until the laminate was obtained was 192 times in total, and the number of spraying steps (Ply number) for the same laminated surface was 3 times).
(Production method)
The one-way prepreg (2) was placed in the storage tank 3 to produce a fiber-reinforced thermoplastic resin sheet under the following conditions.
Number of spray ports: 1 Spray amount (Xg): 1.62g
Spray height 10 (Hmm): 100mm
Distance to move the surface to be laminated (X-axis and Y-axis directions): 40 mm
Total number of laminated compartments: 64 compartments Size of each laminated compartment (Lmm ² ): 1600 mm ²
Number of spraying steps for one laminated section: 3 times Spraying basis weight: 1014 g / m ²
By this spraying step, a laminate having a size of about 320 mm square was obtained, which was laminated on the sedimentary board 14. The laminate obtained by this spraying step had a height of 25 mm. The obtained laminate was transferred to a belt conveyor equipped with a heating / pressurizing mechanism together with a depository, and heated at a heating unit at 150 ° C. for 1 minute and 30 seconds while feeding at a belt speed of 420 mm / min, and then 5 mm. The unidirectional prepregs were temporarily fastened to each other by passing between the upper and lower pressure rollers set in the gap and pressurizing to obtain a primary adhesive agglomerate (temporary fastening sheet). The primary adhesive agglomerates were separated from the depository and transported into a flat plate mold installed in a hydraulic press, and heated and pressed under the conditions of 150 ° C. and 5 MPa to obtain a fiber-reinforced thermoplastic resin sheet (2). The obtained fiber-reinforced thermoplastic resin sheet (2) had a size of 102400 mm ² (320 mm square), a thickness of 2.1 mm, and a weight per unit area (sheet texture) of 3041 g / m ² .

[Example 3: Production of fiber-reinforced thermoplastic resin sheet (3)]
A fiber-reinforced thermoplastic resin sheet (3) was produced in the same manner as in Example 2 except that the spray height 10 (H mm) was set to 300 mm. The laminate obtained by this spraying step had a height of 15 mm.
The obtained fiber-reinforced thermoplastic resin sheet (3) had a size of 102400 mm ² (320 mm square), a thickness of 2.1 mm, and a weight per unit area (sheet texture) of 3041 g / m ² .

[Example 4: Production of fiber-reinforced thermoplastic resin sheet (4)]
(Device)
In Example 4, the same equipment as in Example 2 was used. In Example 4, after performing one spraying step with the depositor 14 shown in FIG. 7 stopped, the depositor 14 is moved by a distance of 60 mm in the X-axis direction in FIG. 7 and again. A single spraying step was performed and the depositor 14 was further moved 60 mm in the X-axis and / or y-axis directions in FIG. Using such an apparatus, the surface to be laminated was divided into 25 laminated sections as shown in FIG. 2 and a spraying step was performed to produce a fiber-reinforced thermoplastic resin sheet (4).
(Production method)
The one-way prepreg (2) was placed in the storage tank 3 to produce a fiber-reinforced thermoplastic resin sheet under the following conditions.
Spray amount (Xg): 3.65g
Spray height 10 (Hmm): 300mm
Distance to move the surface to be laminated (X-axis and Y-axis directions): 60 mm
Total number of laminated compartments: 25 compartments Size of each laminated compartment (Lmm ² ): 3600 mm ²
Metsuke: 1014g / m ²
Other conditions: Similar to Example 2, the laminate obtained by this spraying step had a height of 15 mm. The obtained fiber-reinforced thermoplastic resin sheet (4) had a size of 90000 mm ² (300 mm square), a thickness of 2.1 mm, and a weight per unit area (sheet texture) of 3041 g / m ² .

[Example 5: Production of fiber-reinforced thermoplastic resin sheet (5)]
A fiber-reinforced thermoplastic resin sheet (5) was produced in the same manner as in Example 4 except that the spraying amount (Xg) was 5.47 g and the number of spraying steps for one laminated section was twice. The basis weight for spraying under this condition was 1519 g / m ² . The obtained fiber-reinforced thermoplastic resin sheet (5) had a size of 90000 mm ² (300 mm square), a thickness of 2.1 mm, and a weight per unit area (sheet texture) of 3041 g / m ² .

[Example 6: Production of fiber-reinforced thermoplastic resin sheet (6)]
(Device)
In Example 6, an apparatus in which three spraying portions 5 shown in FIG. 1 are lined up was used. In such a device, the distance between the centers of adjacent spray openings (also referred to as “spray outlet interval”) was set to 86 mm. The same apparatus as in Example 2 was used except that the number of spray ports was three and the spray port intervals were set as described above. That is, the apparatus used in the sixth embodiment has a configuration in which three spray ports are arranged at the predetermined spray port intervals in FIG. 7. In Example 6, after performing one spraying step with the depositor 14 shown in FIG. 7 stopped, the depositor 14 is moved by a distance of 86 mm in the X-axis direction in FIG. 7 and again. One spraying step was performed and the depositor 14 was further moved by a distance of 86 mm in the X-axis direction in FIG. Using such an apparatus, the surface to be laminated was divided into nine laminated sections as shown in FIG. 9 and a spraying step was performed to produce a fiber-reinforced thermoplastic resin sheet (6).
(Production method)
The unidirectional prepreg (3) was placed in the storage tank 3 to produce a fiber-reinforced thermoplastic resin sheet under the following conditions.
Number of spray ports: 3 Spray port spacing: 86 mm
Spray amount (Xg): 3.75g
Spray height 10 (Hmm): 300mm
Distance to move the surface to be laminated (X-axis and Y-axis directions): 86 mm
Total number of laminated compartments: 9 compartments Size of each laminated compartment (Lmm ² ): 7396 mm ²
Number of spraying steps for one laminated section: 6 times Spraying basis weight: 507 g / m ²
The laminate obtained by this spraying step had a height of 20 mm. The obtained fiber-reinforced thermoplastic resin sheet (6) had a size of 66564 mm ² (258 mm square), a thickness of 2.1 mm, and a weight per unit area (sheet texture) of 3041 g / m ² .

[Example 7: Production of fiber-reinforced thermoplastic resin sheet (7)]
(Production method)
The unidirectional prepreg (3) was placed in the storage tank 3 and sprayed in the same manner as in Example 6 except that the following conditions were met, and the unidirectional prepreg (3) was divided into 9 laminated sections to reinforce the fibers. A thermoplastic resin sheet (7) was manufactured.
Spray amount (Xg): 4.50g
Spray height 10 (Hmm): 300mm
Number of spraying steps for one laminated section: 5 times Spraying basis weight: 608 g / m ²
The laminate obtained by this spraying step had a height of 20 mm. The obtained fiber-reinforced thermoplastic resin sheet (7) had a size of 66564 mm ² (258 mm square), a thickness of 2.1 mm, and a weight per unit area (sheet texture) of 3041 g / m ² .

[Example 8: Production of fiber-reinforced thermoplastic resin sheet (8)]
(Production method)
The unidirectional prepreg (3) was placed in the storage tank 3 and sprayed in the same manner as in Example 6 except that the following conditions were met, and the unidirectional prepreg (3) was divided into 9 laminated sections to reinforce the fibers. A thermoplastic resin sheet (8) was manufactured.
Spray amount (Xg): 7.50g
Spray height 10 (Hmm): 500mm
Number of spraying steps for one laminated section: 3 times Spraying basis weight: 1014 g / m ²
The laminate obtained by this spraying step had a height of 20 mm. The obtained fiber-reinforced thermoplastic resin sheet (8) had a size of 66564 mm ² (258 mm square), a thickness of 2.1 mm, and a weight per unit area (sheet texture) of 3041 g / m ² .

[Example 9: Production of fiber-reinforced thermoplastic resin sheet (9)]
A fiber-reinforced thermoplastic resin sheet (9) was produced in the same manner as in Example 8 except that the one-way prepreg (4) was used instead of the one-way prepreg (3). The laminate obtained by this spraying step had a height of 30 mm.
The obtained fiber-reinforced thermoplastic resin sheet (9) had a size of 66564 mm ² (258 mm square), a thickness of 2.1 mm, and a weight per unit area (sheet texture) of 3041 g / m ² .

[Comparative Example 1: Production of Fiber Reinforced Thermoplastic Resin Sheet (10)]
(Device)
In Comparative Example 1, the same apparatus as in Example 2 was used. In Comparative Example 1, after performing one spraying step with the depositor 14 shown in FIG. 7 stopped, the depositor 14 was moved by a distance of 80 mm in the X-axis direction in FIG. 7 and again. A single spraying step was performed and the depositor 14 was further moved a distance of 80 mm in the X-axis or y-axis direction in FIG. Using such an apparatus, the surface to be laminated was divided into 16 laminated sections as shown in FIG. 12, and a spraying step was performed to produce a fiber-reinforced thermoplastic resin sheet (10).
(Production method)
The one-way prepreg (2) was placed in the storage tank 3 to produce a fiber-reinforced thermoplastic resin sheet under the following conditions.
Number of spray ports: 1 Spray amount (Xg): 6.49g
Spray height 10 (Hmm): 300mm
Distance to move the surface to be laminated (X-axis and Y-axis directions): 80 mm
Total number of laminated sections: 16 sections Number of spraying steps for one laminated section: 3 times Size of each laminated section (Lmm ² ): 6400 mm ²
Metsuke: 1014g / m ²
Other conditions: Similar to Example 2, the laminate obtained by this spraying step had a height of 15 mm. The obtained fiber-reinforced thermoplastic resin sheet (10) had a size of 102400 mm ² (320 mm square), a thickness of 2.1 mm, and a weight per unit area (sheet texture) of 3041 / m ² .

[Comparative Example 2: Production of Fiber Reinforced Thermoplastic Resin Sheet (11)]
A fiber-reinforced thermoplastic resin sheet (11) was produced in the same manner as in Comparative Example 1 except that the spray height 10 (H mm) was 100 mm.
The obtained fiber-reinforced thermoplastic resin sheet (11) had a size of 102400 mm ² (320 mm square), a thickness of 2.1 mm, and a weight per unit area (sheet texture) of 3042 g / m ² .

[Comparative Example 3: Production of Fiber Reinforced Thermoplastic Resin Sheet (12)]
(Device)
In Comparative Example 3, an apparatus in which three spraying portions 5 shown in FIG. 1 were lined up was used. In such a device, the distance between the centers of adjacent spray openings (also referred to as “spray outlet interval”) was set to 86 mm. The same apparatus as in Example 2 was used except that the number of spray ports was three and the spray port intervals were set as described above. That is, the device used in Comparative Example 3 has a configuration in which three spray ports are lined up at the predetermined spray port intervals in FIG. 7. In Comparative Example 3, after performing one spraying step with the depositor 14 shown in FIG. 7 stopped, the depositor 14 was moved by a distance of 86 mm in the X-axis direction in FIG. 7 and again. One spraying step was performed and the depositor 14 was further moved by a distance of 86 mm in the X-axis direction in FIG. Using such an apparatus, the surface to be laminated was divided into 9 laminated sections and a spraying step was performed as shown in FIG. 9, and a fiber-reinforced thermoplastic resin sheet (12) was manufactured.
(Production method)
The unidirectional prepreg (3) was placed in the storage tank 3 to produce a fiber-reinforced thermoplastic resin sheet under the following conditions.
Spray amount (Xg): 3.75g
Spray height 10 (Hmm): 100mm
Distance to move the surface to be laminated (X-axis and Y-axis directions): 86 mm
Total number of laminated compartments: 9 compartments Size of each laminated compartment (Lmm ² ): 7396 mm ²
Number of spraying steps for one laminated section: 6 times Spraying basis weight: 507 g / m ²
Other conditions: Similar to Example 2, the laminate obtained by this spraying step had a height of 20 mm. The obtained fiber-reinforced thermoplastic resin sheet (12) had a size of 66564 mm ² (258 mm square), a thickness of 2.1 mm, and a weight per unit area (sheet texture) of 3042 g / m ² .

[Comparative Example 4: Production of Fiber Reinforced Thermoplastic Resin Sheet (13)]
(Device)
In Comparative Example 4, the same equipment as in Example 2 was used. In Comparative Example 4, after performing one spraying step with the depositor 14 shown in FIG. 7 stopped, the depositor 14 was moved by a distance of 60 mm in the X-axis direction in FIG. 7 and again. A single spraying step was performed and the depositor 14 was further moved 60 mm in the X-axis or y-axis direction in FIG. Using such an apparatus, the surface to be laminated was divided into 25 laminated sections as shown in FIG. 13 and a spraying step was performed to produce a fiber-reinforced thermoplastic resin sheet (13).
(Production method)
The one-way prepreg (2) was placed in the storage tank 3 to produce a fiber-reinforced thermoplastic resin sheet under the following conditions.
Spray amount (Xg): 11.0g
Spray height 10 (Hmm): 200mm
Distance to move the surface to be laminated (X-axis and Y-axis directions): 60 mm
Total number of laminated compartments: 25 compartments Size of each laminated compartment (Lmm ² ): 3600 mm ²
Number of spraying steps for one laminated section: 1 spraying basis weight: 3041 g / m ²
Other conditions: Similar to Example 2, the laminate obtained by this spraying step had a height of 15 mm. The obtained fiber-reinforced thermoplastic resin sheet (13) had a size of 90000 mm ² (300 mm square), a thickness of 2.1 mm, and a weight per unit area (sheet texture) of 3042 g / m ² .

The following table shows the production conditions of the fiber-reinforced thermoplastic resin sheets obtained in the above Examples and Comparative Examples, the tensile strength measured according to the above method, the coefficient of variation of the tensile strength, and the total number of sprays per unit area. Shown in 2. The value A in Table 2 is calculated from the formula A = (X / H) × V, the value B is calculated from the formula B = X / H, and the value C is the formula C = L / H. It is calculated from.

As is clear from the results shown in Table 2, it was confirmed that the CV values were low and the fiber-reinforced thermoplastic resin sheet had high isotropic properties in Examples 1 to 9. In Example 6, the dispersibility of the chopped base material was improved by setting the spraying amount at one time to 5.5 g or less and increasing the number of laminated sheets from 3 layers to 6 layers as compared with Comparative Example 1. It is considered that the improvement led to the reduction of CV. On the other hand, in Comparative Examples 1 to 4, the tensile strength was relatively lowered and the CV value could not be sufficiently reduced. The above reason is that in Comparative Example 1, since the amount of spraying in one spraying step is larger than that in Example 2, the one-way prepreg cannot be sufficiently dispersed when spraying the one-way prepreg. It is thought that it was a result. In Comparative Example 2, in addition to the reason in Comparative Example 1, it is considered that the dispersibility of the unidirectional prepreg was further lowered due to the low spray height. In Comparative Example 3, the amount of spraying per application was reduced and the number of Ply was increased, but it was considered that the effect of the decrease in the dispersibility of the one-way prepreg due to the low spray height could not be compensated. Be done. In Comparative Example 4, it is considered that this is because the amount of spraying at one time is large and the number of Ply is small. In particular, in Example 8, although the spraying weight per spraying is large, the variation is reduced by increasing the spraying height and setting the value A and the like within a predetermined range, and the productivity and physical characteristics are reduced. Very good results were obtained in terms of reliability.

1 Spraying port 2 Measuring part 3 Storage tank 4 Transporting part 5 Spraying part 6 Laminated surface 7 Laminated part 8 One-way prepreg 9 Laminated product 10 Spraying height 11 Spraying port spacing 12 Lower belt 13 Upper belt 14 Sedimentation board

Claims (12)

A method for producing a fiber-reinforced thermoplastic resin sheet in which a unidirectional prepreg containing a reinforcing fiber and a thermoplastic resin is laminated so that the fiber directions are random.
Using a device having at least a spraying portion provided with a spraying port for spraying the one-way prepreg and a laminated portion having a laminated surface for laminating the one-way prepreg, a spraying port located above the laminated surface. Including the spraying step of dropping the one-way prepreg from the to the laminated surface, the average volume per one-way prepreg is V mm ³ , and the weight of the one-way prepreg dropped from one spray port at one time is Xg. Assuming that the distance from the laminated surface to the spray port is H mm, the following equation (1): from V, X and H:

The value A calculated by the above method is 0.05 or more and 0.7 or less. From the weight (Xg) of the one-way prepreg dropped from one spraying port at one time and the distance (Hmm) from the laminated surface to the spraying port, the following equation (2):

The manufacturing method according to claim 1, wherein the value B calculated by the above method is 0.03 or less. The manufacturing method according to claim 1 or 2, wherein the average volume (Vmm ³ ) of the one-way prepreg is 4 to 60 mm ³ . The manufacturing method according to any one of claims 1 to 3, wherein the surface to be laminated is divided into one or two or more laminated sections, and the spraying step is performed in each laminated section. The manufacturing method according to claim 4, wherein the spraying step is performed two or more times on one laminated section. The manufacturing method according to any one of claims 1 to 5, wherein the unidirectional prepreg is dropped from two or more spray ports. From the size of each laminated section (Lmm ² ) and the distance from the laminated surface to the spray port (Hmm), the following equation (3):

The manufacturing method according to any one of claims 4 to 6, wherein the value C calculated by the above method is 1 to 50. The production method according to any one of claims 1 to 7, further comprising a step of heating the laminate obtained by the spraying step to obtain a primary adhesive agglomerate. The manufacturing method according to any one of claims 1 to 8, wherein the weight per unit area of the laminated surface by one spraying is 300 to 1600 g / m ² . The production method according to any one of claims 1 to 9, wherein the fiber volume content of the fiber-reinforced thermoplastic resin sheet is 10 to 99% by volume. The production method according to any one of claims 1 to 10, wherein the reinforcing fiber is carbon fiber. The production method according to any one of claims 1 to 11, wherein the CV value of the tensile strength measured according to JIS K 7164 in the fiber-reinforced thermoplastic resin sheet is less than 20.0%.

Images