JP6176691B1 - Unidirectional prepreg and fiber reinforced thermoplastic resin sheet - Google Patents

Abstract

An object of the present invention is to provide a fiber reinforced thermoplastic resin sheet having both high strength and moldability, to provide a unidirectional prepreg capable of obtaining such a fiber reinforced thermoplastic resin sheet, and A method for manufacturing a directional prepreg is provided. A tape-shaped unidirectional prepreg comprising an opened reinforcing fiber and a bisphenol A type epoxy resin represented by the formula (1): [wherein n represents an integer of 1 to 4] The bisphenol A type epoxy resin has a weight average molecular weight of 1000 to 35000, and the average content of the reinforcing fibers in the thickness direction of the unidirectional prepreg is 10 or less. [Selection] Figure 1

Description

  The present invention relates to a unidirectional prepreg and a fiber reinforced thermoplastic resin sheet containing reinforcing fibers.

  The fiber reinforced plastic (FRP) is a composite material that includes a thermosetting resin or a thermoplastic resin as a matrix and further includes reinforcing fibers such as carbon fibers and glass fibers in the resin. Fiber reinforced plastics whose matrix is a thermoplastic resin are used in a wide range of fields such as tanks, containers, ships and automobiles.

  As a method for producing a fiber reinforced plastic, for example, Patent Document 1 describes a method in which a continuous fiber bundle is impregnated with a solution diluted with a solvent to reduce the viscosity, and the solvent is removed in the next step. Patent Document 2 describes a pultrusion method in which a continuous fiber bundle immersed in a molten resin is opened, ironed, and mechanically impregnated by applying pressure to the resin. Patent Document 3 describes a method of producing a UD tape by applying tension after impregnation and preventing shrinkage of the width by the width direction depending on the distance between fulcrums and the surface drag applied to the tape, and maintaining the linearity of the fiber. Yes. Further, Patent Document 4 discloses a method for producing a fiber-reinforced composite material in which a reinforcing fiber bundle impregnated with a thermoplastic resin is solidified while being supported by two support members separated from each other by a distance calculated by a predetermined formula. Have been described.

  In recent years, for example, as described in Patent Document 5, as a method for producing a fiber-reinforced thermoplastic, a method in which an uncured thermoplastic resin and a reinforcing fiber are mixed and used has been proposed.

Japanese Patent Laid-Open No. 2005-239843 JP 2009-143158 A Japanese Patent Application No. 2014-134969 JP 2016-11403 A Japanese Patent No. 47089797

  Although various manufacturing methods described above have been proposed for fiber reinforced plastics, there is still a need for increasing the moldability and strength of fiber reinforced plastics. Therefore, the present invention provides a fiber reinforced thermoplastic resin sheet having both high strength and moldability, and a unidirectional prepreg capable of obtaining such a fiber reinforced thermoplastic resin sheet. Another object is to provide a method for producing the unidirectional prepreg.

［式中、ｎは１〜４の整数を表す］
で表されるビスフェノールＡ型エポキシ樹脂を含む、テープ状の一方向プリプレグであって、該ビスフェノールＡ型エポキシ樹脂は１０００〜３５０００の重量平均分子量を有し、該一方向プリプレグの厚み方向における該強化繊維の平均含有数は１０本以下である、一方向プリプレグ。
〔２〕前記一方向プリプレグの幅方向における前記強化繊維の平均含有密度は１５０〜２０００本／ｍｍである、前記〔１〕に記載の一方向プリプレグ。
〔３〕ビスフェノールＡをさらに含む、前記〔１〕または〔２〕に記載の一方向プリプレグ。
〔４〕前記一方向プリプレグに含まれる前記ビスフェノールＡ型エポキシ樹脂と前記ビスフェノールＡとの質量比は５０：５０〜９０：１０である、前記〔１〕〜〔３〕のいずれかに記載の一方向プリプレグ。
〔５〕強化繊維は炭素繊維である、前記〔１〕〜〔４〕のいずれかに記載の一方向プリプレグ。
〔６〕前記一方向プリプレグの幅長の変動係数は５％以下である、前記〔１〕〜〔５〕のいずれかに記載の一方向プリプレグ。
〔７〕前記〔１〕〜〔６〕のいずれかに記載の一方向プリプレグのランダム積層体である、繊維強化熱可塑性樹脂シート。
〔８〕前記繊維強化熱可塑性樹脂シートの単位厚みあたりの前記一方向プリプレグの層数は１０〜２０層／ｍｍである、前記〔７〕に記載の繊維強化熱可塑性樹脂シート。
〔９〕（ａ）強化繊維を、厚み方向における平均含有数が１０本以下になるまで開繊する工程、ここで、開繊された強化繊維の幅長の変動係数は５％以下である、および、
（ｂ）開繊された強化繊維に、式（１）：

［式中、ｎは１〜４の整数を表す］
で表されるビスフェノールＡ型エポキシ樹脂を含浸させる工程
を少なくとも含む、一方向プリプレグの製造方法。 The present inventors have found that when there are gaps (voids) that are not impregnated with the matrix resin between the reinforcing fibers, the mechanical properties of the finally obtained molded article are lowered, and a thick reinforcing fiber bundle is included. If this is the case, there will be excessive fiber orientation locally, stress transmission in a direction different from the fiber axis direction through the fiber will not be possible, and it will not be possible to fully utilize the strength of the original fiber. A unidirectional prepreg for obtaining a plastic resin sheet was studied. As a result, it has been found that the above object can be achieved by the unidirectional prepreg of the present invention described below.
That is, the present invention includes the following preferred embodiments.
[1] Reinforced fiber opened and formula (1):

[Wherein n represents an integer of 1 to 4]
A tape-shaped unidirectional prepreg comprising a bisphenol A type epoxy resin represented by the formula, wherein the bisphenol A type epoxy resin has a weight average molecular weight of 1000 to 35000, and the reinforcement in the thickness direction of the unidirectional prepreg Unidirectional prepreg having an average fiber content of 10 or less.
[2] The unidirectional prepreg according to [1], wherein the average content density of the reinforcing fibers in the width direction of the unidirectional prepreg is 150 to 2000 fibers / mm.
[3] The unidirectional prepreg according to [1] or [2], further including bisphenol A.
[4] The mass ratio of the bisphenol A type epoxy resin and the bisphenol A contained in the unidirectional prepreg is 50:50 to 90:10, one of the above [1] to [3] Directional prepreg.
[5] The unidirectional prepreg according to any one of [1] to [4], wherein the reinforcing fiber is a carbon fiber.
[6] The unidirectional prepreg according to any one of [1] to [5], wherein a variation coefficient of a width length of the unidirectional prepreg is 5% or less.
[7] A fiber-reinforced thermoplastic resin sheet, which is a random laminate of the unidirectional prepreg according to any one of [1] to [6].
[8] The fiber-reinforced thermoplastic resin sheet according to [7], wherein the number of layers of the unidirectional prepreg per unit thickness of the fiber-reinforced thermoplastic resin sheet is 10 to 20 layers / mm.
[9] (a) The step of opening the reinforcing fiber until the average content in the thickness direction is 10 or less, where the variation coefficient of the width length of the opened reinforcing fiber is 5% or less, and,
(B) Formula (1):

[Wherein n represents an integer of 1 to 4]
The manufacturing method of the unidirectional prepreg including the process of impregnating the bisphenol A type epoxy resin represented by these.

  By using the unidirectional prepreg of the present invention, a fiber-reinforced thermoplastic resin sheet excellent in moldability and strength can be obtained.

It is a schematic diagram of the cross section of the unidirectional prepreg of this invention. It is a schematic diagram of the cross section of the unidirectional prepreg which is not based on this invention. It is a schematic side view of the apparatus provided with the traverse guide. It is a schematic side view of the apparatus provided with the opening guide, the width guide, and the opening tank. It is a schematic side view of the manufacturing apparatus used in order to manufacture the unidirectional prepreg of an Example and a comparative example. It is a schematic side view of the manufacturing apparatus used in order to impregnate the resin composition in the unidirectional prepreg of an Example and a comparative example.

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

［式中、ｎは１〜４の整数を表す］
で表されるビスフェノールＡ型エポキシ樹脂を含み、該ビスフェノールＡ型エポキシ樹脂は１０００〜３５０００の重量平均分子量を有し、該一方向プリプレグの厚み方向における該強化繊維の平均含有数は１０本以下である。本発明の一方向プリプレグにおいて、厚み方向における強化繊維の平均含有数が１０本以下であることと、１０００〜３５０００の重量平均分子量を有する比較的低分子量のビスフェノールＡ型エポキシ樹脂とを含んでいることにより、樹脂マトリックス中にボイド等が含まれることなく強化繊維が存在する。このため、本発明の一方向プリプレグを用いて得られる繊維強化熱可塑性樹脂シートが、高い成形性と強度とを兼ね備える。 The unidirectional prepreg of the present invention comprises an opened reinforcing fiber and a formula (1):

[Wherein n represents an integer of 1 to 4]
And the bisphenol A type epoxy resin has a weight average molecular weight of 1000 to 35000, and the average content of the reinforcing fibers in the thickness direction of the unidirectional prepreg is 10 or less. is there. The unidirectional prepreg of the present invention includes an average content of reinforcing fibers in the thickness direction of 10 or less and a relatively low molecular weight bisphenol A type epoxy resin having a weight average molecular weight of 1000 to 35000. As a result, the reinforcing fibers are present without voids and the like contained in the resin matrix. For this reason, the fiber reinforced thermoplastic resin sheet obtained by using the unidirectional prepreg of the present invention has high moldability and strength.

  Examples of the reinforcing fibers included in the unidirectional prepreg of the present invention include organic fibers such as aramid fibers, polyethylene fibers, polyparaphenylene benzoxador (PBO) fibers, glass fibers, carbon fibers, silicon carbide fibers, alumina fibers, and Tyranno. Examples thereof include inorganic fibers such as fibers, basalt fibers, and ceramic fibers, metal fibers such as stainless fibers and steel fibers, and other reinforcing fibers using boron fibers, natural fibers, modified natural fibers, and the like as fibers. As these reinforcing fibers, reinforcing fibers composed of several thousand or more filaments are preferable, and reinforcing fibers composed of 3000 to 60000 filaments are suitably used for producing a unidirectional prepreg. When the unidirectional prepreg of the present invention is used as a molded body, the reinforcing fiber is more preferably a carbon fiber from the viewpoint of the strength and rigidity of the molded body. The unidirectional prepreg of the present invention may contain one type of reinforcing fiber or a combination of two or more types of reinforcing fibers.

  In a preferred embodiment of the unidirectional prepreg of the present invention 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, the carbon fiber is preferably a PAN-based carbon fiber.

  The presence or absence of twist in the reinforcing fiber is not particularly limited, but from the viewpoint of easily increasing the penetration of the matrix resin, a reinforcing fiber with little twist or no twist is preferable. From the same viewpoint, the number of twists of the reinforcing fiber is preferably 1 time / m or less, more preferably 0.5 times / m or less, and still more preferably 0.3 times / m or less.

  Carbon fiber is often wound around a bobbin that 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 (12K), 15000 pieces (15K), 18000 pieces (18K), 24000 pieces (24K), 30000 pieces (30K), 60000 pieces (60K)) are preferably bundled in a flat shape (carbon fiber tow). Used. The number of carbon fiber filaments may be appropriately changed according to the desired width and thickness of the opened carbon fiber and the unidirectional prepreg of the present invention, but from the viewpoint of productivity, preferably 3000 to 60000, More preferably, it is 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 prepreg to be produced. Moreover, it is preferable that the number of filaments is equal to or more than the above lower limit because it is easy to suppress fuzz due to single yarn breakage and cracking of the prepreg during fiber opening.

  The unidirectional prepreg of the present invention includes opened reinforcing fibers.

  In the opened reinforcing fibers included in the unidirectional prepreg of the present invention, the average content of reinforcing fibers in the thickness direction is 10 or less. If the average content in the thickness direction is more than 10, the reinforcing fibers are excessively overlapped in the thickness direction, so that the fibers cannot be sufficiently impregnated with the bisphenol A type epoxy resin. A gap (void) in which the resin is not impregnated is formed between the fiber and the fiber. If the prepreg contains voids, the voids remain in the molded body formed from the prepreg, for example, through a random laminate, and as a result, sufficient strength of the molded body cannot be obtained. Alternatively, in order to achieve sufficient strength of the molded body, high temperature and / or high pressure is applied so that voids are removed in the process of manufacturing a random laminate or molded product from the prepreg, and a long press time is used. Strict conditions such as applying are required. Such severe conditions are not preferable because they cause deterioration of the resin and a decrease in production efficiency. Further, the fiber orientation is excessively locally, the stress cannot be transmitted in a direction different from the fiber axis direction through the fiber, and the strength inherent to the fiber cannot be fully utilized. The upper limit of the average content in the thickness direction is preferably 8 or less, more preferably 7 from the viewpoint of further enhancing the penetration of the bisphenol A type epoxy resin and increasing the strength of the random laminate of the unidirectional prepreg of the present invention. The number is less than this, and even more preferably less than 6. The lower limit of the average content in the thickness direction is preferably as low as possible from the viewpoint of easily increasing the penetration of the resin, and is not particularly limited, but is preferably 1 or more, more preferably 2 or more, and even more preferably 3 or more. It is.

  When the opened reinforcing fiber has the above-described configuration, the average content of reinforcing fibers in the thickness direction of the unidirectional prepreg of the present invention can be 10 or less. Similarly, the average content of reinforcing fibers in the thickness direction of the unidirectional prepreg of the present invention is preferably 8 or less, more preferably 7 or less, even more preferably 6 or less, and particularly preferably 5.5 or less. It is. Moreover, the lower limit of the average content in the thickness direction is preferably 1 or more, more preferably 2 or more, and even more preferably 3 or more.

  The number of reinforcing fibers contained in the unidirectional prepreg of the present invention in the thickness direction is determined by embedding a cross-section of the prepreg in the thickness direction with a resin or the like and observing it with an electron microscope or the like. It is measured by counting the number of fibers present in the direction. In this way, the number of fibers present in the thickness direction is counted in at least five cross-sectional images, and the average value is defined as the average number of reinforcing fibers in the thickness direction. In the above cross-sectional observation, in order to minimize the influence on the prepreg due to the external force at the time of cutting, for example, the cross-section observation may be performed by cutting both surfaces of the prepreg sandwiched between rigid plates such as metal. . In addition, the measurement of the above-mentioned at least 5 places is, for example, about 50 cm in the fiber axis direction when the unidirectional prepreg of the present invention has a certain length (for example, in the form of a tape wound around a bobbin). Measurement may be performed at least at five intervals, and when the unidirectional prepreg of the present invention is in the form of a cut tape, at least five prepregs are arbitrarily selected from the plurality of cut prepregs. You may take out and measure. Hereinafter, when measuring at a plurality of locations, the measurement at a plurality of locations may be performed in the same manner as described above.

The average content density of the reinforcing fibers in the width direction of the opened reinforcing fibers contained in the unidirectional prepreg of the present invention is preferably 150 to 2000 / mm, more preferably 500 to 1500 / mm, and even more preferably. 700-1000 pieces / mm. When the average content density of reinforcing fibers in the width direction is not more than the above upper limit, voids are not easily generated inside the prepreg when the resin is impregnated. Moreover, when the average content density of the reinforcing fibers in the width direction is not less than the above lower limit, it is easy to prevent the prepreg from cracking. When the opened reinforcing fiber has the above-described configuration, the average density of reinforcing fibers in the width direction included in the unidirectional prepreg of the present invention is preferably 150 to 2000 fibers / mm, more preferably 500 to 1500. Book / mm, more preferably 700-1000 book / mm. By making the average content density of the reinforcing fibers in the width direction of the unidirectional prepreg of the present invention within the above range, the unidirectional prepreg of the present invention is less likely to crack even though it is a thin layer and the voids are reduced. It is easy to improve the characteristics of the prepreg. Furthermore, by using the unidirectional prepreg of the present invention having such characteristics, it is easy to improve the moldability and strength of the fiber-reinforced thermoplastic resin sheet, and the quality of the molded body produced from the fiber-reinforced thermoplastic resin sheet is also improved. Easy to improve. Here, the average content density of the reinforcing fibers in the width direction is an average number of reinforcing fibers contained per unit width of the prepreg of the present invention, and is calculated from the following equation (2). In addition, the measuring method of the average content number of the reinforced fiber in the thickness direction in Formula (2) is as having described above. Further, (1 / single yarn diameter [mm] of reinforcing fibers) in the formula (2) represents the number of reinforcing fibers that can be included in a unit laminate per 1 mm in the width direction.

The variation coefficient (CV value) of the width length of the opened reinforcing fibers contained in the unidirectional prepreg of the present invention is preferably 5% or less. In the present invention, the coefficient of variation is determined by measuring the length of the width substantially orthogonal to the fiber direction of the opened reinforcing fiber at at least 10 points, and from the average value and standard deviation obtained from the results, the coefficient of variation (CV) = It is calculated by the standard deviation / average value formula. When the opened reinforcing fiber has the above-described configuration, the variation coefficient of the width length in the unidirectional prepreg of the present invention can be preferably 5% or less. Thereby, when manufacturing a random laminated body from the prepreg of this invention, it becomes difficult to produce lamination | stacking nonuniformity and it becomes easy to ensure the isotropy of a random laminated body.

  A preferred embodiment of the unidirectional prepreg of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic view of a cross section when a unidirectional prepreg of a preferred embodiment of the present invention in which the average content of reinforcing fibers in the thickness direction is 10 or less is cut in the thickness direction. FIG. 2 shows a schematic diagram of a cross section when a unidirectional prepreg not having the average content of the reinforcing fiber in the thickness direction is more than 10 and cut in the thickness direction. In FIG. 1 showing a preferred embodiment of the present invention, the matrix resin 1 containing the bisphenol A resin is sufficiently permeated between the reinforcing fibers 2, but in FIG. 2 showing one embodiment not corresponding to the present invention, It is considered that there is a void 3 between the reinforcing fibers 2 where the matrix resin 1 containing the bisphenol A type resin does not exist. This difference is considered to affect the formability when producing the final molded product and the strength of the obtained molded product. FIG. 1 is a schematic view showing an embodiment of the unidirectional prepreg of the present invention, and does not limit the cross-sectional shape of the unidirectional prepreg of the present invention.

［式中、ｎは１〜４の整数を表す］
で表されるビスフェノールＡ型エポキシ樹脂を含む。該ビスフェノールＡ型エポキシ樹脂は１０００〜３５０００の重量平均分子量を有する。これにより、テープ生産時の取扱い性が良く、さらにこのテープを用いて製造される繊維強化熱可塑性シートの成形性・賦形性を高めることができる。ビスフェノールＡ型エポキシ樹脂の重量平均分子量は、生産性・成形性の観点から、好ましくは５０００〜２５０００である。ここで、重量平均分子量は、ゲル浸透クロマトグラフィー(ＧＰＣ)を用いた装置により測定される。重量平均分子量が上記の下限以上であることが一方向プリプレグの取扱性の観点から好ましく、重量平均分子量が上記の上限以下であることが、ランダム積層体を製造する際の樹脂の流動性が良好となり、ボイド率が低く十分な強度を有する成形体を製造しやすいため好ましい。 The unidirectional prepreg of the present invention further comprises formula (1):

[Wherein n represents an integer of 1 to 4]
The bisphenol A type epoxy resin represented by these is included. The bisphenol A type epoxy resin has a weight average molecular weight of 1000 to 35000. Thereby, the handleability at the time of tape production is good, Furthermore, the moldability and the shapeability of the fiber reinforced thermoplastic sheet manufactured using this tape can be improved. The weight average molecular weight of the bisphenol A type epoxy resin is preferably 5000 to 25000 from the viewpoints of productivity and moldability. Here, the weight average molecular weight is measured by an apparatus using gel permeation chromatography (GPC). The weight average molecular weight is preferably not less than the above lower limit from the viewpoint of handleability of the unidirectional prepreg, and the weight average molecular weight is not more than the above upper limit, the resin fluidity when producing a random laminate is good. Therefore, it is preferable because it is easy to produce a molded body having a low void ratio and sufficient strength.

  The unidirectional prepreg of the present invention preferably contains a further compound capable of reacting with the bisphenol A type epoxy resin. Examples of such compounds include bisphenol A (2,2-bis (4-hydroxyphenyl) propane; BPA), bisphenol F (4,4′-methylene-bisphenol; BPF), bisphenol S (bis (4-hydroxy Phenyl) sulfone; BPS), bisphenol B (2,2-bis (4-hydroxyphenyl) butane; BPB), bisphenol E (4,4 '-(methylmethylene) bisphenol; BPE), bisphenol P (2,2- Bis (3-methyl-4-hydroxyphenyl) propane; BPP) and the like are preferable, and bisphenol A is preferable. The unidirectional prepreg of the present invention contains a bisphenol A type epoxy resin and a further compound capable of reacting with the bisphenol A type epoxy resin, and these components are polymerized at the time of forming a random laminate, thereby obtaining a stronger sheet. It is preferable because it is easy to obtain. In addition, when the prepreg is produced and the random laminate is molded, the heat resistance of the molded body can be expected to be increased by being taken into the polymerizing resin.

  In a preferred embodiment of the present invention in which the unidirectional prepreg of the present invention contains bisphenol A type epoxy resin and bisphenol A, the mass ratio of the bisphenol A type epoxy resin and the bisphenol A contained in the unidirectional prepreg is prepreg. From the viewpoint of the strength, rigidity, and heat resistance of the molded product obtained by using, the ratio is preferably 50:50 to 90:10, more preferably 60:40 to 80:20. It is preferable from the viewpoint of increasing the heat resistance of the molded article obtained from the prepreg that the ratio of bisphenol A in the mass ratio is not less than the above lower limit. Moreover, it is preferable that the ratio of bisphenol A in the mass ratio is not more than the above upper limit because the reinforced fiber thus opened is easily impregnated with bisphenol A type epoxy resin and bisphenol A in a well dispersed state.

  In addition to the above, the unidirectional prepreg of the present invention may contain any additive. Examples of the additive include an organic solvent, a reaction accelerator, a coupling agent, a pigment, an antifoaming agent, an antifungal agent, and a deterioration preventing agent. When these additives are added, the amount thereof may be appropriately changed according to the purpose of addition.

  The unidirectional prepreg of the present invention has a tape shape. The tape-shaped prepreg may be wound around a bobbin or may be cut into a predetermined length.

  The average thickness of the unidirectional prepreg of the present invention is preferably 10 to 200 μm, more preferably 20 to 180 μm, and still more preferably 40 to 160 μm. It is preferable that the average thickness is not more than the above upper limit because generation of voids inside the prepreg can be suppressed. Moreover, since it is possible to suppress cracking of the prepreg, the average thickness is preferably equal to or more than the above lower limit. The said average thickness is an average value which measured the thickness of this prepreg using the thickness meter about at least 10 places of a prepreg.

  Considering the average content density and thickness of the above-described opened reinforcing fibers, the average width of the unidirectional prepreg of the present invention is preferably 10 to 18 mm when using, for example, a 12K carbon fiber yarn. In this case, if the average width is 10 mm or more, it is easy to suppress the generation of voids in the produced prepreg, and if the average width is 18 mm or less, fluffing due to single yarn breakage at the time of opening and cracking of the prepreg are suppressed. Cheap. Here, the average width is an average value obtained by measuring the width of the prepreg at least at 10 locations using a measurement camera or the like. In the unidirectional prepreg of the present invention, the width direction is a direction orthogonal to the fiber direction on the prepreg surface.

  The average length in the fiber direction of the unidirectional prepreg of the present invention is not particularly limited. It changes suitably according to the use application of a unidirectional prepreg.

  The unidirectional prepreg of the present invention is measured according to JIS-7075 in a fiber-reinforced thermoplastic sheet having an average thickness of 2 mm from the viewpoint of easily improving the moldability and mechanical strength of the finally obtained molded product, preferably 0 to It has a void fraction of 0.4%.

  In the unidirectional prepreg of the present invention, a binding agent may be attached to the opened reinforcing fiber. By attaching the restraining agent, it is easy to improve the width restraint of the opened reinforcing fiber, and it is possible to suppress cracks that may occur when the unidirectional prepreg of the present invention is manufactured. The adhesion amount of the restraining agent is preferably 0.8% by weight or less based on the weight of the reinforcing fiber in consideration of the influence on the physical property deterioration of the finally obtained prepreg, and is 0.3 to 0.5 More preferably, it is% by weight. It is preferable that the amount of binding of the restraining agent is not more than the above upper limit because it is easy to improve the restraining property of the width of the opened reinforcing fiber. By making the adhesion amount of a restraining agent into the above-mentioned range, it is easy to suppress the physical property fall of the molded object obtained from a prepreg, and the crack which may occur when manufacturing a unidirectional prepreg. The type of the binding agent to be used is not particularly limited, but an emulsified epoxy resin, an emulsified modified polyolefin resin, or the like is preferably used.

［式中、ｎは１〜４の整数を表す］
で表されるビスフェノールＡ型エポキシ樹脂を含浸させる工程
を少なくとも含む、一方向プリプレグの製造方法も提供する。本発明の上記一方向プリプレグも、好ましくは本発明の製造方法により製造される。本発明の製造方法は、強化繊維を厚み方向における平均含有数が１０本以下になるまで開繊する工程（以下において「工程（ａ）」とも称する）と、開繊された強化繊維に樹脂を含浸させる工程（以下において「工程（ｂ）」とも称する）とが含まれていればよいが、通常は、工程（ａ）を行った後で、工程（ｂ）が行われる。しかし、開繊を行いながら含浸を行う、工程（ａ）と工程（ｂ）とを同時に行う方法も本発明の製造方法に含まれる。 The present invention also provides
(A) a step of opening the reinforcing fibers until the average content in the thickness direction is 10 or less, wherein the variation coefficient of the width length of the opened reinforcing fibers is 5% or less, and
(B) Formula (1):

[Wherein n represents an integer of 1 to 4]
A method for producing a unidirectional prepreg comprising at least a step of impregnating a bisphenol A type epoxy resin represented by the formula: The unidirectional prepreg of the present invention is also preferably manufactured by the manufacturing method of the present invention. The production method of the present invention comprises a step of opening the reinforcing fibers until the average content in the thickness direction is 10 or less (hereinafter also referred to as “step (a)”), and a resin is applied to the opened reinforcing fibers. The step of impregnation (hereinafter also referred to as “step (b)”) may be included, but usually, after step (a) is performed, step (b) is performed. However, a method of simultaneously performing the step (a) and the step (b) in which the impregnation is performed while the fiber is opened is also included in the production method of the present invention.

  The reinforcing fiber used in the step (a) is not particularly limited, but is an unopened reinforcing fiber that is usually also referred to as “raw yarn”. Such a reinforcing fiber is wound around a bobbin which is a cylindrical tube with a constant traverse width, and is often used after being unwound.

  Here, the fiber bundle is usually sent out in a meandering manner with respect to the traveling direction only by unwinding the raw yarn traversed around the cylindrical bobbin. From the viewpoint of easily obtaining the unidirectional prepreg of the present invention described above, it is possible to use an apparatus that eliminates the traverse derived from the raw yarn and allows the fiber bundle to be sent straight out in the traveling direction without meandering. preferable.

  An apparatus for eliminating the traverse is shown in FIG. For example, it is preferable to use an apparatus including a feed mechanism that unwinds and feeds the raw yarn, a plurality of yarn path guides 7, and a traverse guide 8 that eliminates the traverse of the reinforcing fibers. The process of unwinding, for example, carbon fiber using such an apparatus will be described below. As shown in FIG. 3, the traverse guide 8 is provided either above or below the immediately preceding yarn path guide 7a so as to intersect perpendicularly with the immediately preceding thread path guide 7a (in FIG. Provided below the yarn path guide 7a). Here, it is preferable that the contact surface with the guide of the flat fiber bundle is sent out so that all of the immediately preceding yarn path guide 7a, the traverse guide 8 and the immediately following thread path guide 7b are the same surface. As the delivery mechanism, an apparatus including a raw yarn bobbin holder 5 for setting the raw yarn 4 and a delivery tension generating motor 6 is exemplified. As the yarn path guide 7, a metal vertical guide roller is preferably used. The yarn path guide 7 is preferably provided along the traveling direction of the fiber bundle so as to be substantially parallel to the raw yarn bobbin holder 5. The diameter of the yarn path guide 7 is preferably about 20 to 40 mm from the viewpoint of space saving of equipment and handling of reinforcing fibers. The reinforced fiber yarn 4 set in the yarn bobbin holder 5 is sent out by driving the delivery tension generating motor 6 and sent to the step (a) for opening the reinforced fiber through the yarn path guide 7. It is done.

  The fiber bundle of the raw yarn 4 is twisted by 90 ° when it is sent out from the immediately preceding yarn path guide 7a to the traverse guide 8, and 90 ° when it is sent out from the traverse guide 8 to the immediately following yarn path guide 7b. When passing, it will be twisted once. Thereby, the traverse derived from the raw yarn is eliminated, and the carbon bundle can be sent out straight in the traveling direction without meandering. When the fiber bundle is sent out from the immediately preceding yarn path guide to the immediately following thread path guide, the twist direction is used in the S direction, the Z direction, or a combination of these with respect to the fiber traveling direction.

  The traverse guide 8 may be the same metal vertical guide roller as the yarn path guide 7 or may be a pin guide having a small diameter. Further, the traverse guide may be provided so as to be driven in the direction opposite to the traveling direction of the fiber bundle using a driving source such as a motor, or fine irregularities may be provided on the surface of the guide. By providing the traverse guide 8 so as to apply resistance to the fiber bundle in this way, the end of the fiber bundle can be prevented from being folded when the fiber bundle passes through the traverse guide 8, and the fiber bundle is flattened. (For example, when using a 12K raw yarn, the width orthogonal to the fiber direction is 5 to 8 mm or 8 to 10 mm).

  The distance between the traverse guide 8, the immediately preceding yarn path guide 7a, and the immediately following thread path guide 7b is preferably 1 m or more. As a result, it is possible to prevent the end portion from being folded due to the fiber bundle passing through the traverse guide.

  The production method of the present invention includes at least a step (a) of opening the reinforcing fiber unwound as described above until the average content in the thickness direction is 10 or less. If the average content in the thickness direction is more than 10, the reinforcing fibers are excessively overlapped in the thickness direction, so that the fibers cannot be sufficiently impregnated with the bisphenol A type epoxy resin. A gap (void) in which the resin is not impregnated is formed between the fiber and the fiber. The upper limit of the average content in the thickness direction is preferably 8 or less, more preferably 7 from the viewpoint of further enhancing the penetration of the bisphenol A type epoxy resin and increasing the strength of the random laminate of the unidirectional prepreg of the present invention. The number is less than this, and even more preferably less than 6. The lower limit of the average content in the thickness direction is preferably as low as possible from the viewpoint of easily increasing the penetration of the resin, and is not particularly limited, but is preferably 1 or more, more preferably 2 or more, and even more preferably 3 or more. It is.

  In the step (a), the tension applied to the reinforcing fiber at the time of opening is preferably 0.02 to 0.1 g / piece, more preferably 0.04 to 0.06 g / piece. By applying tension in such a range, it is easy to improve the spreadability and to easily suppress fuzz due to single yarn breakage. When the tension is lower than 0.02 g / strand, the average content in the thickness direction of the opened reinforcing fibers obtained because the fiber bundle is not sufficiently expanded may not be sufficiently reduced. Moreover, when it is higher than 0.1 g / string, fuzz due to single yarn breakage may easily occur.

  In order to improve the opening property of the reinforcing fiber, at least one of an ultrasonic fiber opening method, an electrostatic fiber opening method, a press fiber opening method, a jet fiber opening method, a ventilation type fiber opening method and the like may be used.

  In the step (a), for example, opening may be performed using an apparatus including a opening guide and a width guide. In FIG. 4, in addition to the opening guides 13a-13h and the width guide 10, the example of the apparatus provided with the opening tank 11 is shown. The spread guides 13a to 13h are, for example, cylindrical shapes having a predetermined diameter, and are fixed at predetermined positions. By the fiber opening guides 13a to 13h, a load is applied from the substantially radial direction to the reinforcing fiber 9 before the fiber opening, and the reinforcing fiber is pressed from the vertical direction in the traveling direction. As a result, the fiber bundle is spread and the reinforcing fibers are opened. The number of opening guides is not particularly limited, and may be appropriately changed according to the width of the fiber bundle of the reinforcing fibers 9 before opening, the desired width of the unidirectional prepreg, and the like. Similarly, the winding angle between the fiber bundle and the spread guides 13a to 13h may be appropriately changed.

  The width guide 10 includes a pair of guides provided so as to be positioned outside both ends of the fiber bundle, and is provided so as to be perpendicular to the opening guide at least at one position between the opening guides 13a to 13h. It is done. Since the fiber bundle of the reinforcing fiber 9 before opening passes through the inside of the width guide 10, the opening width of the fiber bundle can be adjusted, and the width accuracy of the opened reinforcing fiber can be increased. The number and width of the width guides 10 are not particularly limited, and may be appropriately changed according to the number of filaments of fibers, the desired width of the unidirectional prepreg, and the like.

  The materials of the spread guides 13a to 13h and the width guide 10 are not particularly limited, but metals such as steel, stainless steel, and alumina are preferably used. From the viewpoint of reducing fiber wear, it is preferable to use a guide in which chromium is electroplated on the surface of stainless steel. Since the guide made of such a material has a smoothed surface, wear due to contact between the guide and the fiber during opening can be reduced, and fuzz due to single yarn breakage can be suppressed.

  The opening tank 11 is a tank provided to store the opening solution 12 containing a liquid such as water, and the opening guide and the width guide are provided in the opening so that the reinforcing fiber can be opened while being sent out in the liquid. May be provided. Thus, the sizing agent applied at the time of manufacture of a reinforcing fiber can be removed by performing fiber opening while immersing the reinforcing fiber in the liquid. In order to increase the elution property of the sizing agent in the opening tank, the temperature of the liquid in the opening tank may be increased, or a liquid to which a surfactant or the like is added may be used.

  A binding agent may be attached to the opened reinforcing fiber. By attaching the restraining agent, it is easy to improve the width restraint of the opened reinforcing fiber, and it is possible to suppress cracks that may occur when the unidirectional prepreg of the present invention is manufactured. The restraining agent may be included in the above-described opening tank, or separately from the opening tank (desize tank) for removing the sizing agent contained in the reinforcing fibers, a tank (resizing tank) to which the restraining agent is attached. It may be provided. By attaching the binding agent, it is easy to suppress shrinkage in the width direction of the opened reinforcing fibers in the subsequent step (b). The adhesion amount of the restraining agent is preferably 0.8% by weight or less based on the weight of the reinforcing fiber in consideration of the influence on the physical property deterioration of the finally obtained prepreg, and is 0.3 to 0.5 More preferably, it is% by weight. Although it does not specifically limit as an example of a restraint agent, The emulsified epoxy resin, modified polyolefin resin, etc. are utilized suitably.

  Next, the step of removing moisture and the like contained in the reinforcing fibers, the step of drying (for example, the drying roller 14 in FIG. 4), and the step of winding (for example, FIG. 4) are performed on the reinforcing fibers opened as described above. The drive roller 15 and the winding part 16) inside may be applied as necessary.

  In the step of drying the opened reinforcing fibers, for example, a plurality of drying rolls capable of adjusting the temperature may be used. The fiber bundle can be completely dried by being sent out so that the fiber bundle comes into contact with the drying roll. The temperature of the drying roll may be appropriately changed according to the tape width, the winding speed, the volatility of the solution in the fiber opening tank, and the temperature range of 80 to 200 ° C. is preferably used. Moreover, the temperature of each drying roll may be the same or different.

  In the winding process, a mechanism (winding shaft, motor, etc.) and a reel for winding the opened reinforcing fibers are used. When the reel attached to the take-up shaft rotates, the opened reinforcing fiber can be taken up on the reel. The winding speed may be appropriately changed according to the opening property of the fiber bundle, the width of the opened reinforcing fiber, etc., preferably 50 m / min or less, more preferably 5 to 30 m / min. It is preferable to perform winding at a speed in the above range because it is easy to improve the accuracy of the width.

  In the step of winding the opened reinforcing fibers, for example, a scraper, a brush, or the like may be provided so as to come into contact with the roller in order to remove fuzz due to single yarn breakage that occurs due to contact with each roller.

  The reinforcing fiber opened through the above process has a coefficient of variation (CV) of a width length of 5% or less. The method for calculating the coefficient of variation is as described above for the opened reinforcing fibers included in the unidirectional prepreg. By making the variation coefficient of width length 5% or less, when manufacturing a random laminated body from the prepreg of the present invention, uneven lamination hardly occurs and it is easy to ensure the isotropy of the random sheet.

［式中、ｎは１〜４の整数を表す］
で表されるビスフェノールＡ型エポキシ樹脂を含浸させる。工程（ｂ）で含浸させるビスフェノールＡ型エポキシ樹脂の重量平均分子量は好ましくは１０００以下である。ビスフェノールＡ型エポキシ樹脂の重量平均分子量が上記の上限以下であることが、樹脂が低粘性であり、強化繊維間にボイドが生じることなく含浸させやすいため好ましい。 In the step (b) following the step (a), the reinforcing fiber that has been opened is represented by the formula (1):

[Wherein n represents an integer of 1 to 4]
Is impregnated with a bisphenol A type epoxy resin represented by The weight average molecular weight of the bisphenol A type epoxy resin impregnated in the step (b) is preferably 1000 or less. It is preferable that the weight average molecular weight of the bisphenol A type epoxy resin is not more than the above upper limit because the resin has low viscosity and is easily impregnated without forming voids between the reinforcing fibers.

  In the step (b), it is preferable to impregnate further compounds that can react with the bisphenol A type epoxy resin. Examples of such compounds include bisphenol A, bisphenol F, bisphenol S, bisphenol B, bisphenol E, and bisphenol P, and bisphenol A is preferred. Random laminates using the unidirectional prepreg obtained by impregnating the opened reinforcing fibers with bisphenol A type epoxy resin and a further compound capable of reacting with bisphenol A type epoxy resin in step (b) These compounds are preferable because these compounds are polymerized not only within one unidirectional prepreg but also between adjacent unidirectional prepregs, and the strength of the random laminate is easily increased.

  In a preferred embodiment of the present invention in which bisphenol A is impregnated with bisphenol A type epoxy resin in step (b), the mass ratio between the bisphenol A type epoxy resin and the bisphenol A contained in the unidirectional prepreg is determined using prepreg. From the viewpoint of strength, rigidity, and heat resistance of the molded article obtained in this manner, the ratio is preferably 50:50 to 90:10, more preferably 60:40 to 80:20. It is preferable that the ratio of bisphenol A in the mass ratio is not less than the above lower limit because the heat resistance of the molded product obtained from the prepreg can be easily increased. Moreover, it is preferable that the ratio of bisphenol A in the mass ratio is not more than the above upper limit because the reinforced fiber thus opened is easily impregnated with bisphenol A type epoxy resin and bisphenol A in a well dispersed state.

  In the step (b), any additive other than the above may be impregnated. Examples of the additive include an organic solvent, a reaction accelerator, a coupling agent, a pigment, an antifoaming agent, an antifungal agent, and a deterioration preventing agent. When these additives are added, the amount thereof may be appropriately changed according to the purpose of addition.

  As a method of impregnating the bisphenol A type epoxy resin in the step (b), the opened reinforcing fiber may be impregnated using the bisphenol A type epoxy resin as it is, or a bisphenol A type epoxy resin and an organic solvent may be impregnated. You may impregnate using the varnish containing. It is preferable to impregnate using varnish from the viewpoint of increasing the permeability to the reinforcing fibers by lowering the viscosity of the resin and facilitating the impregnation without forming voids between the reinforcing fibers. The organic solvent that can be contained in the varnish is preferably an organic solvent having high solubility in the bisphenol A type epoxy resin, more preferably a polar solvent such as DNP / NMP, still more preferably a ketone solvent, and particularly preferably methyl ethyl ketone.

  The impregnation method is not particularly limited, and may be performed by coating bisphenol A type epoxy resin or a solution thereof on the upper and lower surfaces of the reinforcing fiber opened using the discharge die, or the opened reinforcing fiber You may immerse in the solution containing a bisphenol A type epoxy resin. Here, the reinforcing fiber impregnated with the resin or the resin solution tends to shrink in the width direction due to the surface tension of the resin or the resin solution. This shrinkage may cause an increase in thickness, disorder of fiber directionality, cracking, and the like. In order to prevent such shrinkage, it is preferable to use, for example, a coating apparatus in the step (b).

  After impregnating the resin, the reinforcing fiber may be subjected to a squeezing step of draining with a roller. The squeezing pressure P applied to the roller is preferably 0.05 MPa to 0.3 MPa, more preferably 0.1 MPa to 0.25 MPa. Thereby, void removal and resin amount control can be performed. If the squeezing pressure is lower than the above lower limit, the resin adhesion amount is not stable and voids remain in the unidirectional prepreg, which is not preferable. Further, if the squeezing pressure is higher than the above upper limit, it is difficult to increase the resin amount of the unidirectional prepreg, which is not preferable. The amount of the resin is preferably controlled so that the reinforcing fiber volume content Vf in the finally obtained unidirectional prepreg is preferably 20 to 60%, more preferably 35 to 55%. It is preferable to set it as the above-mentioned range from a viewpoint of the moldability of the molded object obtained from the prepreg of this invention. It is preferable that the volume content is equal to or less than the above upper limit because the entangled portions (unimpregnated portions) between the fibers are reduced and it is easy to obtain a voidless structure. Moreover, since it is easy to raise the intensity | strength of a molded object, it is preferable that a volume content rate is more than said lower limit.

  Next, the resin impregnated in the reinforcing fibers is solidified. The solidification method is not particularly limited, and may be performed by heating the reinforcing fiber impregnated with the resin. The heating temperature may be appropriately changed depending on the type of reinforcing fiber to be used or the type of solvent or the volatilization temperature when a resin solution is used. preferable. By this solidification, the resin is linearly polymerized via a terminal reactive group (epoxy group) represented by the formula (1), and a unidirectional prepreg containing a bisphenol A type epoxy resin having a polymerization average molecular weight of 1000 to 35000. Is obtained.

  A fiber-reinforced thermoplastic resin sheet exhibiting isotropy can be produced by arranging the unidirectional prepreg of the present invention, for example, so as to be randomly stacked on a mold having a desired size, and heating and pressing. it can. The heating temperature for producing the fiber-reinforced thermoplastic resin sheet of the present invention is preferably higher by 100 ° C. than the glass transition temperature of the resin. Thereby, the fluidity | liquidity of resin becomes favorable and it becomes possible to fill the clearance gap which exists between the prepreg laminated | stacked by further pressurizing. As a result, it becomes easy to reduce voids of the obtained molded body.

  As described above, the unidirectional prepreg of the present invention includes a bisphenol A type epoxy resin represented by the formula (1) having a relatively low weight average molecular weight of 1000 to 35000. Therefore, when the fiber reinforced thermoplastic resin sheet is produced by heating at the above heating temperature, further polymerization of the bisphenol A type epoxy resin proceeds. This polymerization is performed not only within one unidirectional prepreg contained in the fiber-reinforced thermoplastic resin sheet, but also between adjacent unidirectional prepregs. As a result, it is considered that the unidirectional prepregs in the fiber-reinforced thermoplastic resin sheet are more firmly bonded to each other and high strength is achieved.

  As described above, the fiber-reinforced thermoplastic resin sheet of the present invention is excellent in strength and has high moldability. This is because the resin is polymerized during the production of the fiber reinforced thermoplastic resin sheet as described above, and the reinforced fibers are opened in the unidirectional prepreg so that the average content of reinforcing fibers in the thickness direction is 10 or less. It is considered that it is contained in a fibrillated state and generation of a gap (void) in which the resin between the fibers is not impregnated is suppressed as much as possible. Furthermore, since the reinforcing fibers opened so that the average content of the reinforcing fibers in the thickness direction of the unidirectional prepreg is 10 or less are contained, the fibers are locally constant in the fiber-reinforced thermoplastic resin sheet. It is considered that high strength is achieved with a low coefficient of variation without excessive orientation.

  The fiber-reinforced thermoplastic resin sheet of the present invention having the above characteristics has excellent moldability. Conventionally known prepregs often contain voids, and these voids remain in the thermoplastic resin sheet obtained from such prepregs. Therefore, in order to achieve sufficient strength of the molded body, it may be necessary to remove the voids by press molding at a high temperature and / or high pressure for a long time so that the voids are removed. In addition, when there is an excessive fiber orientation, the stress cannot be transmitted in a direction different from the fiber axis direction through the fiber, and the inherent strength of the fiber may not be fully utilized. It was. However, in the fiber reinforced thermoplastic resin sheet of the present invention, as described above, the generation of voids is suppressed as much as possible, and there is an excessive local localized fiber orientation in the fiber reinforced thermoplastic resin sheet. Therefore, it is possible to produce a molded body having sufficient strength even under conditions of lower temperature, lower pressure, and shorter time than before.

  Examples of the method for producing a molded body using the fiber-reinforced thermoplastic resin sheet of the present invention include press molding. Press molding is a method for producing a molded article by applying deformation such as bending, shearing, compression, etc. to the fiber-reinforced thermoplastic resin sheet of the present invention using a processing apparatus and a mold. Examples of the molding form include deep drawing, flange, coal gate, edge curling, stamping and the like. Examples of the press molding method include a die press method and an autoclave method used for molding a large-sized member (for example, an aircraft member).

  Since the resin contained in the fiber reinforced thermoplastic resin sheet of the present invention is a thermoplastic resin, the fiber reinforced thermoplastic resin sheet of the present invention is heated, and the resin is melted and softened to be deformed into the shape of the mold. It is also suitable for stamping molding that is cooled and then cooled.

  Since the fiber reinforced thermoplastic resin sheet of the present invention is particularly excellent in moldability, deep drawing press molding, which is difficult to mold when using conventional fiber reinforced plastic, molding at low pressure (4 MPa or less), and short time It can be used for stamping molding that can be molded with

  The shape of the fiber-reinforced thermoplastic resin sheet of the present invention may be appropriately changed depending on the desired shape of the molded body, and is not particularly limited.

  The number of layers of the unidirectional prepreg per unit thickness of the fiber reinforced thermoplastic resin sheet of the present invention is 10 to 20 layers / mm from the viewpoint of easily increasing the strength of the molded body obtained from the fiber reinforced thermoplastic resin sheet. It is preferable.

  Since the fiber-reinforced thermoplastic resin sheet of the present invention has good resin impregnation properties with respect to the reinforcing fibers of the unidirectional prepreg, the fiber-reinforced thermoplastic sheet having an average thickness of 2 mm is measured according to JIS-7075, preferably 0. The void ratio can be -0.4%. Thus, the molded object obtained from the fiber reinforced thermoplastic resin sheet which has a low void rate is excellent in moldability, and it becomes possible to raise mechanical strength.

  The use of the molded body produced from the fiber-reinforced thermoplastic resin sheet of the present invention is not limited at all, but for example, building materials such as electrical and electronic equipment parts, struts and reinforcing materials used for OA equipment and mobile phones, and for automobiles. Examples include structural parts and aircraft parts. The molded body produced from the fiber-reinforced thermoplastic resin sheet of the present invention has high strength with little variation. Moreover, it can utilize also for the reinforcing material etc. as not only a sheet | seat but a unidirectional material.

  EXAMPLES Hereinafter, the present invention will be specifically described by way of examples, but these do not limit the scope of the present invention.

  In FIG. 5, the schematic side view of the manufacturing apparatus used in order to manufacture the unidirectional prepreg of an Example and a comparative example is shown. The production apparatus includes a wound reinforcing fiber winding package 17, a yarn introduction roller 19, a resin discharge die 20, a conveyance belt guide roller 21, a conveyance belt 22, a drying furnace (polymerization furnace) 23, and a cooling device 24. .

  FIG. 6 shows a part of the details of the manufacturing apparatus shown in FIG. 5 in order to explain in more detail the apparatus relating to the step of impregnating the opened reinforcing fibers with resin. In FIG. 5, the height at which the opened reinforcing fibers are in contact with the yarn introduction roller 19 and the height at which the reinforcing fibers after impregnation with the resin are in contact with the conveying belt 22 are the same. In a part of the examples, the height was adjusted so as to be inclined at an angle A as shown in FIG.

[Production Example 1: Method for opening reinforcing fiber]
The device that opens the reinforcing fiber is a mechanism that feeds the raw yarn, a mechanism that winds the opened reinforcing fiber, and a guide through which the carbon fiber passes, a fiber opening tank that opens the reinforcing fiber, and controls the feeding or winding speed. A control mechanism was provided. Note that the mechanism for feeding the raw yarn has a device for canceling the traverse. The fiber bundle is threaded at a winding speed of 20 m / min, the fiber bundle is unwound under the condition of a tension of 0.04 to 0.06 g / piece, and then immersed in the solution in the fiber opening tank. The fiber was opened by applying pressure and dried to obtain a reinforced fiber (hereinafter also referred to as “opening tape”). In each example and comparative example, the guide width was adjusted to obtain a desired average width. The number of filaments, average width and variation coefficient thereof, and average content of reinforcing fibers in the thickness direction used in each example and comparative example are as shown in each example. The average width of the opened reinforcing fibers and the coefficient of variation thereof were measured using a camera.

[Production Example 2: Production of resin composition]
1000 g of hot melt epoxy (XNR / H6850) manufactured by Nagase ChemteX Corporation (550 g of bisphenol A type epoxy resin represented by the above formula (I) having a weight average molecular weight of 200 to 1000, 300 g of bisphenol A, and 150 g of methyl ethyl ketone) Was prepared, and mixed uniformly using a stirrer to obtain a resin composition having a viscosity of 100 to 200 mPa · s.

[Example 1]
A carbon fiber yarn (a) having a single yarn diameter of 7 μm and a filament number of 12 k was opened according to the method of Production Example 1. The opened carbon fiber (hereinafter also referred to as “opening tape 1”) has an average width of 16 mm, a coefficient of variation (CV) of width of 2.4%, and 5.25 reinforcing fibers in the thickness direction. It had an average content. The opened tape 1 was passed through at a predetermined speed (4 mm / min), and the resin composition obtained in Production Example 2 was discharged from a resin discharge die (impregnation die) to impregnate the tape. Here, as for the details of the setting of the apparatus in the impregnation step, the distance B between the center of the conveying belt guide roller 21 and the lower surface die head 20b shown in FIG. 6 is 20 mm, and the angle A is 1 °. The impregnated resin-impregnated tape was received by a conveyor belt and passed through a drying / polymerization furnace set to 200 ° C. over 1 minute to produce a tape-shaped unidirectional prepreg 1. The length of the manufactured tape was 200 m. In the above process, the tension applied to the tape was 300 g. As a result, a prepreg having an average thickness of 0.071 mm, an average width of 15.1 mm, and a fiber volume content (Vf) of 40% (adhesion amount accuracy of ± 2%) was obtained. The obtained prepreg had good resin adhesion on both sides.

[Example 2]
A carbon fiber yarn (b) having a single yarn diameter of 7 μm and a filament number of 12 k was opened according to the method of Production Example 1. The opened carbon fiber (hereinafter also referred to as “opening tape 2”) has an average width of 16 mm, a coefficient of variation (CV) of 4.7% width length, and 5.25 reinforcing fibers in the thickness direction. It had an average content. A tape-shaped unidirectional prepreg 2 was produced in the same manner as in Example 1 except that the spread tape 2 was used, the distance B shown in FIG. 6 was 10 mm, and the angle A was 2 °. As a result, a prepreg having an average thickness of 0.06 mm, an average width of 17.1 mm, and a fiber volume content (Vf) of 40% (adhesion amount accuracy of ± 2%) was obtained. The obtained prepreg had good resin adhesion on both sides.

Example 3
A carbon fiber yarn (c) having a single yarn diameter of 7 μm and a filament number of 12 k was opened according to the method of Production Example 1. The opened carbon fiber (hereinafter also referred to as “opening tape 3”) has an average width of 13 mm, a coefficient of variation (CV) of 4.4% width length, and 6.46 reinforcing fibers in the thickness direction. It had an average content. A tape-shaped unidirectional prepreg 3 was produced in the same manner as in Example 1 except that the spread tape 3 was used, the distance B shown in FIG. 6 was 10 mm, and the angle A was 2 °. As a result, a prepreg having an average thickness of 0.10 mm, an average width of 14.1 mm, and a fiber volume content (Vf) of 40% (adhesion amount accuracy of ± 2%) was obtained. The obtained prepreg had good resin adhesion on both sides.

Example 4
A carbon fiber yarn (d) having a single yarn diameter of 7 μm and a filament number of 12 k was opened according to the method of Production Example 1. The opened carbon fiber (hereinafter also referred to as “opening tape 4”) has an average width of 13 mm, a coefficient of variation (CV) of 4.1% width length, and 6.46 reinforcing fibers in the thickness direction. It had an average content. A tape-shaped unidirectional prepreg 4 was produced in the same manner as in Example 1 except that the spread tape 4 was used, the distance B shown in FIG. 6 was 20 mm, and the angle A was 1 °. As a result, a prepreg having an average thickness of 0.10 mm, an average width of 13.2 mm, and a fiber volume content (Vf) of 40% (adhesion amount accuracy of ± 2%) was obtained. The obtained prepreg had good resin adhesion on both sides.

Example 5
A carbon fiber yarn (e) having a single yarn diameter of 7 μm and a filament number of 60 k was opened according to the method of Production Example 1. The opened carbon fiber (hereinafter also referred to as “opening tape 5”) has an average width of 80 mm, a coefficient of variation (CV) of width length of 3.8%, and 5.25 reinforcing fibers in the thickness direction. It had an average content. A tape-shaped unidirectional prepreg was used in the same manner as in Example 1 except that the spread tape 5 was used, the tension applied to the tape was 1000 g, the distance B shown in FIG. 6 was 20 mm, and the angle A was 1 °. 5 was produced. As a result, a prepreg having an average thickness of 0.072 mm, an average width of 78 mm, and a fiber volume content (Vf) of 40% (adhesion amount accuracy of ± 2%) was obtained. The obtained prepreg had good resin adhesion on both sides.

Example 6
A carbon fiber yarn (f) having a single yarn diameter of 7 μm and a filament number of 15 k was opened according to the method of Production Example 1. The opened carbon fiber (hereinafter also referred to as “opening tape 6”) has an average width of 17 mm, a coefficient of variation (CV) of 1.6% width length, and 6.2 reinforcing fibers in the thickness direction. It had an average content. A tape-shaped unidirectional prepreg 6 was manufactured in the same manner as in Example 1 except that the spread tape 6 was used, the distance B shown in FIG. 6 was 20 mm, and the angle A was 1 °. As a result, a prepreg having an average thickness of 0.075 mm, an average width of 15 mm, and a fiber volume content (Vf) of 40% (adhesion amount accuracy of ± 2%) was obtained. The obtained prepreg had good resin adhesion on both sides.

Example 7
A carbon fiber yarn (g) having a single yarn diameter of 7 μm and a filament number of 12 k was opened according to the method of Production Example 1. In the fiber opening step, a modified polyolefin resin was adhered as a restraining agent in an amount of 0.4% with respect to the weight of the carbon fiber. The opened carbon fiber (hereinafter also referred to as “opening tape 7”) has an average width of 17 mm, a coefficient of variation (CV) of 1.6% width length, and 6.2 reinforcing fibers in the thickness direction. It had an average content. A tape-shaped unidirectional prepreg 7 was produced in the same manner as in Example 1 except that the spread tape 7 was used, the distance B shown in FIG. 6 was 20 mm, and the angle A was 1 °. As a result, a prepreg having an average thickness of 0.095 mm, an average width of 13 mm, and a fiber volume content (Vf) of 40% (adhesion amount accuracy of ± 2%) was obtained. The obtained prepreg had good resin adhesion on both sides.

[Comparative Example 1]
A carbon fiber yarn (h) having a single yarn diameter of 7 μm and a filament number of 12 k was opened according to the method of Production Example 1. The opened carbon fiber (hereinafter also referred to as “opening tape 8”) has an average width of 16 mm, a coefficient of variation (CV) of a width length of 6.4%, and 5.25 reinforcing fibers in the thickness direction. It had an average content. A tape-shaped unidirectional prepreg 8 was manufactured in the same manner as in Example 1 except that the spread tape 8 was used, the distance B shown in FIG. 6 was 70 mm, and the angle A was 10 °. When the unidirectional prepreg 8 was manufactured, shrinkage in the width direction of the reinforcing fibers was observed. As a result, a prepreg having an average thickness of 0.17 mm, an average width of 7.1 mm, and a fiber volume content (Vf) of 40% (adhesion amount accuracy of ± 2%) was obtained. The obtained prepreg contracted in width.

[Comparative Example 2]
A carbon fiber yarn (i) having a single yarn diameter of 7 μm and a filament number of 12 k was opened according to the method of Production Example 1. The opened carbon fiber (hereinafter also referred to as “opening tape 9”) has an average width of 16 mm, a coefficient of variation (CV) of 7.2% in width length, and 5.25 reinforcing fibers in the thickness direction. It had an average content. A tape-shaped unidirectional prepreg 9 was produced in the same manner as in Example 1 except that the spread tape 9 was used, the distance B shown in FIG. 6 was 100 mm, and the angle A was 0 °. As a result, a prepreg having an average thickness of 0.3 mm, an average width of 5 mm, and a fiber volume content (Vf) of 40% (adhesion amount accuracy of ± 2%) was obtained. The obtained prepreg contracted in width and became rod-shaped.

  About the unidirectional prepregs 1 to 9 obtained as described above, according to the following measurement method, the average content of reinforcing fibers in the thickness direction of the unidirectional prepreg, the average content density of the reinforcing fibers in the width direction, the average thickness, and the average The width and fiber volume content were measured. Moreover, the adhesiveness of the resin was evaluated according to the following evaluation method. The obtained results are shown in Table 1. Furthermore, when the weight average molecular weight of the bisphenol A type epoxy resin represented by the above formula (I) contained in the obtained unidirectional prepregs 1 to 9 was measured using gel permeation chromatography, all were 1000 to 35000. there were.

  The content of the reinforcing fibers in the thickness direction of the unidirectional prepreg is obtained by cutting the obtained prepreg in the thickness direction, observing the cross-section at 100 to 1000 times using an electron microscope, and obtaining the thickness in the obtained image. It was measured by counting the number of fibers present in the direction. The said measurement was performed about five places and the average value was made into the average content number of the reinforced fiber in the thickness direction.

  The average content density of reinforcing fibers in the width direction of the unidirectional prepreg is based on the average content of reinforcing fibers in the thickness direction measured as described above and the single yarn diameter of the carbon fibers used in each of the examples and comparative examples. Calculation was performed according to the above equation (2).

  The average thickness was obtained by measuring the thickness of the unidirectional prepreg every 1 m using a thickness meter and calculating the average value.

  The average width was obtained by measuring the width of the unidirectional prepreg at least every 50 cm with respect to the fiber direction using a camera, and calculating the average value.

  When the fiber volume content was measured from the weight of the prepreg per 1 m, the fiber volume content was 40% in all Examples and Comparative Examples. Further, the adhesion amount accuracy was ± 2% in all Examples and Comparative Examples.

The resin adhesion was evaluated on both sides of the obtained unidirectional prepreg for the presence or absence of exposed portions (rubbing) of fibers according to the following criteria.
Evaluation standard of resin adhesion A: No part where the fiber is exposed B: Almost no part where the fiber is exposed C: Some parts where the fiber is exposed D: The fiber is exposed There are many parts

Example 8
The tape obtained in Example 1 was cut so that the length in the fiber direction was 20 mm. After the unidirectional prepreg thus obtained was dispersed in a 300 mm square mold so that the fiber directions were dispersed, the mold was heated at 150 ° C. for 10 minutes without applying pressure, and the unidirectional prepreg was The resin contained in was polymerized. Thereafter, the pressure was increased at 4 MPa for 20 minutes while maintaining 150 ° C., and then the temperature was lowered to 80 ° C. or lower to remove the mold. In this way, a 300 mm square unidirectional prepreg random laminate 1 (non-continuous fiber isotropic sheet) having an average thickness of 2 mm was produced.

Example 9
A random laminate 3 of a unidirectional prepreg was produced in the same manner as in Example 8 except that the tape obtained in Example 3 was used.

Example 10
A random laminate 3 of unidirectional prepreg was produced in the same manner as in Example 8 except that the tape obtained in Example 6 was used.

Example 11
A random laminate 4 of unidirectional prepreg was produced in the same manner as in Example 8 except that the tape obtained in Example 7 was used.

[Comparative Example 3]
A random laminate 5 of a unidirectional prepreg was produced in the same manner as in Example 8 except that the tape obtained in Comparative Example 1 was used.

[Comparative Example 4]
A random laminate 6 of unidirectional prepreg was produced in the same manner as in Example 8 except that the tape obtained in Comparative Example 2 was used.

  About the random laminated bodies 1-6 obtained as mentioned above, according to the following measuring method, average bending strength and average bending elastic modulus were measured. The obtained results are shown in Table 2. Moreover, the cross-sectional properties were evaluated according to the following evaluation methods. The obtained results are shown in Table 2.

  The average bending strength and the average bending elastic modulus were measured using a universal testing machine (100 kN Tensilon) manufactured by Shimadzu Corporation according to ASTM D790. As a measurement sample, a large number of test pieces were produced by cutting out the random laminates obtained in each Example and Comparative Example into a length of 80 mm, a width of 35 mm, and a thickness of 2 mm, and 10 pieces were extracted therefrom and used. The average value and CV were calculated from the results obtained by 10 measurements.

For the cross-sectional properties, a cross section obtained by cutting the obtained random laminate in the thickness direction was observed with an electron microscope, and the presence or absence of unevenness of the resin was evaluated according to the following criteria.
Evaluation criteria for resin adhesion A: no resin bias B: almost no resin bias C: slightly resin bias D: very much resin bias

DESCRIPTION OF SYMBOLS 1 Matrix resin 2 Reinforcing fiber 3 Void 4 Original yarn 5 Original yarn bobbin holder 6 Sending tension generating motor 7 Yarn path guide 7a Yarn path guide just before 7b Yarn path guide just after 8 Traverse guide 9 Reinforcing fiber before opening 10 Width guide DESCRIPTION OF SYMBOLS 11 Opening tank 12 Opening solution 13a-13h Opening guide 14 Drying roller 15 Driving roller 16 Winding part 17 Winding package of the opened reinforcing fiber 18 Opened reinforcing fiber 19 Leading roller 20 Resin discharge die 20a Upper die head 20b Lower die head 21 Conveying belt guide roller 22 Conveying belt 23 Drying furnace 24 Cooling device 25 Unidirectional prepreg tape

Claims (8)

Opened reinforcing fiber and formula (1):

[Wherein n represents an integer of 1 to 4]
A tape-shaped unidirectional prepreg comprising a polymer of a bisphenol A type epoxy resin represented by the following formula and a compound selected from the group consisting of bisphenol A, bisphenol F, bisphenol S, bisphenol B, bisphenol E and bisphenol P there, the average content number of the reinforcing fibers in the thickness direction of the unidirectional prepreg is less than ten, unidirectional prepreg. The average content density of the reinforcing fibers in the width direction of the unidirectional prepreg is 150 to 2000 fibers / mm, where the average content density is the following formula (2):

The unidirectional prepreg according to claim 1 , which is calculated by: The unidirectional prepreg according to claim 1 or 2, wherein the polymer is a polymer of a bisphenol A type epoxy resin represented by the formula (1) and bisphenol A. The unidirectional prepreg according to any one of claims 1 to 3 , wherein the reinforcing fiber is a carbon fiber. The unidirectional prepreg according to any one of claims 1 to 4 , wherein a variation coefficient of the width length of the unidirectional prepreg is 5% or less. A fiber-reinforced thermoplastic resin sheet, which is a random laminate of the unidirectional prepreg according to any one of claims 1 to 5 . The fiber-reinforced thermoplastic resin sheet according to claim 6 , wherein the number of layers of the unidirectional prepreg per unit thickness of the fiber-reinforced thermoplastic resin sheet is 10 to 20 layers / mm. (A) a step of opening the reinforcing fiber until the average content in the thickness direction is 10 or less ,
(B) Formula (1):

[Wherein n represents an integer of 1 to 4]
Impregnating a bisphenol A type epoxy resin represented by the formula: and a compound selected from the group consisting of bisphenol A, bisphenol F, bisphenol S, bisphenol B, bisphenol E and bisphenol P ; and
Heating the reinforcing fiber impregnated with resin to solidify the resin impregnated in the reinforcing fiber, the method for producing a unidirectional prepreg, comprising reinforcing the unidirectional prepreg in the thickness direction The manufacturing method whose average content of a fiber is 10 or less .

Images