JP3586959B2 - Method for producing FRP molded body - Google Patents

Description

【００４３】
【発明の効果】
本発明のＦＲＰ成形体の製造方法によれば、プリプレグＡの樹脂含有率および離型シートとの剥離抵抗を特定の範囲とし、プリプレグＡのマトリックス樹脂を特定範囲の粘度のエポキシ樹脂とし、かつ、成形時の樹脂フローを特定値以下とすることにより、あるいは、このプリプレグＡと、樹脂含有率および繊維目付が特定の範囲のプリプレグＢとの交差積層とし、かつ、成形時の樹脂フローを特定値以下とすることにより、プリプレグの樹脂含有率が低いにもかかわらず、使用するプリプレグの表面のボコツキが少なく、ボイドが少なく、軽量性に優れたＦＲＰ成形体が得られる。また、ラッピングテープの喰い込みのない、品位、強度ともに優れたＦＲＰ成形体を得ることができる。
【図面の簡単な説明】
【図１】本発明において、プリプレグと離型シートとの剥離抵抗を測定する際に用いる、プリプレグ材を貼ったジグを示す概略斜視図である。
【図２】本発明において、プリプレグと離型シートとの剥離抵抗を測定する際の引張試験の状況を示す概略側面図である。
【符号の説明】
１ 両面接着テープ
２ プリプレグ
３ 離型シート
４ ステンレススチール板
５ 糸
６ クリップ
７ 引張試験機の上部掴み具
８ 引張試験機の下部掴み具[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing an FRP molded body using a prepreg containing a reinforcing fiber and a matrix resin, and more particularly, to a prepreg having excellent winding workability and a low resin content, and having low void content and light weight. And a method for producing a molded article.
[0002]
[Prior art]
BACKGROUND ART Fiber-reinforced prepregs have been widely used in sports and leisure applications as intermediate materials for molded products such as golf shafts, fishing rods, badminton shafts, and tennis racket frames. In recent years, fiber reinforced prepregs having a low resin content have been developed to further reduce the weight of golf shafts, fishing rods, and the like.
[0003]
In general, a fiber-reinforced prepreg is provided with a release sheet on one side thereof in a sheet or roll form for shape retention, storage, or transportation. When the fiber-reinforced prepreg is formed into a molded product such as a cylinder, for example, it is usually cut together with the release sheet, the fiber-reinforced prepreg is attached to the core, and the release sheet is peeled and wrapped to obtain the desired molded product. . At this time, the prepregs are laminated with the fiber direction directed in a predetermined direction, for example, the axial direction or the circumferential direction of the cylindrical core. Above, the fiber reinforced prepreg cut before being wound around the core is often left for about several hours, during which the prepreg partially peels from the release sheet in the fiber reinforced prepreg having a low resin content, Irregularities may occur on the surface (hereinafter, irregularities on the prepreg surface are referred to as bumps). In a fiber-reinforced prepreg having a high resin content, since the amount of resin is large, the adhesiveness between the release sheet and the fiber-reinforced prepreg was good, and such a problem hardly occurred. Wrapping the fiber-reinforced prepreg having such unevenness around the core causes wrinkles and voids, and causes problems such as a decrease in strength of the obtained molded product and poor quality.
[0004]
In addition, in order to prevent the occurrence of bumps after cutting the prepreg, it is conceivable to take measures such as shortening the standing time after cutting or increasing the environmental temperature for leaving. It is difficult to increase the production efficiency of products, and there is a problem that a large capital investment is required.
[0005]
Japanese Patent Publication No. 7-59645 discloses a method for producing a molded article in which the resin flow rate is reduced to 2% by weight or less using a prepreg having a resin content of 19 to 27% by weight. However, although this publication describes a prepreg having a low resin content, it does not disclose any wrapping workability. In addition, when molding a golf shaft, fishing rod, or the like, there is generally an operation of winding a wrapping tape, but if the resin flow amount is large, the wrapping tape bites into the molded body, resulting in a quality defect and a decrease in strength. Invite the problem.
[0006]
[Problems to be solved by the invention]
The present invention has been made in view of the above problems, less occurrence of unevenness of the prepreg surface even if left after cutting, using a specific prepreg having a low resin content, by controlling the resin flow amount, It is an object of the present invention to obtain a light-weight molded body having few voids. It is another object of the present invention to obtain a molded article which is free from biting of a wrapping tape and has excellent quality and strength.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the method for producing an FRP molded article of the present invention has a resin content of at least 15 to 27% by weight and a peel resistance with a release sheet of at least 40 to 250 g / 25 mm. near is, and, as matrix resin, using a prepreg a is at least 50 poise epoxy resin viscosity at 90 ° C., reduction in resin content by the resin flow is 0.2 wt% or less as a whole It comprises a method characterized by molding.
[0008]
In addition, the method for producing an FRP molded article according to the present invention comprises the steps of: combining prepreg A as described above with prepreg B having a resin content of more than 27% by weight and a reinforcing fiber weight of 50 g / m ² or less. The method comprises laminating and molding so that the directions cross each other.
[0009]
When the FRP molded body is a tubular molded body, using a mandrel, prepreg A is arranged such that its reinforcing fiber direction is the axial direction of the mandrel, and prepreg B is such that its reinforcing fiber direction is the circumferential direction of the mandrel. It is preferable to arrange them in such a manner.
[0010]
In the present invention, the resin flow is the total amount of the resin that protrudes on the wrapping tape or at both ends of the molded product when the prepreg is laminated on the core body and then molded, for example, when the resin is cured by wrapping the wrapping tape. This means that it is expressed in terms of% by weight based on the initial weight of the prepreg.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with preferred embodiments. The prepreg of the present invention contains a reinforcing fiber and a matrix resin, and is prepared as a prepreg material obtained by sticking the prepreg on a release sheet before molding.
[0012]
Examples of the reinforcing fiber used in the present invention include glass fiber, aramid fiber, carbon fiber, graphite fiber and the like, and when formed into a molded product, carbon fiber is used because it shows particularly excellent mechanical properties. preferable. As the carbon fiber, a polyacrylonitrile-based or pitch-based carbon fiber can be used.
[0013]
As the matrix resin used in the present invention, an epoxy resin is usually used. Examples of the epoxy resin include bisphenol A type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, glycidylamine type epoxy resin, alicyclic epoxy resin, urethane modified epoxy resin, brominated bisphenol A type epoxy resin, and the like. Can be used. These epoxy resins can be used alone or in combination of two or more, and furthermore, from a liquid type to a solid type. Usually, a curing agent is often used in addition to an epoxy resin.
[0014]
The matrix resin of the prepreg A according to the present invention, Ru least 50 poise epoxy resin der viscosity at 90 ° C.. Preferably, an epoxy resin of 65 poise or more is used. By using an epoxy resin having such a viscosity, it is possible to suppress a decrease in the resin content to a predetermined value or less.
[0015]
The prepreg A in the present invention has a resin content of 15 to 27% by weight, preferably 16 to 25% by weight, more preferably 17 to 23% by weight. When the resin content is less than 15% by weight, the amount of the resin is too small to obtain a prepreg of good quality and quality. When the resin content exceeds 27% by weight, the effect of weight reduction is impaired and the present invention is not improved. Even if it is not applied, the surface of the prepreg will hardly be uneven.
[0016]
The peel resistance between the prepreg A and the release sheet is in the range of 40 to 250 g / 25 mm. Preferably it is in the range of 60 to 220 g / 25 mm.
[0017]
If the peeling resistance is less than 40 g / 25 mm, the surface of the prepreg A tends to be uneven. On the other hand, if it exceeds 250 g / 25 mm, it becomes difficult to peel the prepreg from the release sheet, and the workability deteriorates, such as the release sheet being broken.
[0018]
The peel resistance between the prepreg and the release sheet can be measured as follows.
The prepreg material is cut into a strip having a width of 25 mm and a length of 270 mm to obtain a test piece. As shown in FIG. 1, the prepreg 2 side of the test piece is bonded to the surface of a stainless steel jig 4 via a double-sided adhesive tape 1. The jig to which the test piece was attached was attached to the lower grip 8 of the tensile tester as shown in FIG. 2, the release sheet 3 was pulled upward by the upper grip 7 via the clip 6 and the thread 5, and the pulling speed was 50 mm / As a minute, the force required to peel the prepreg 2 and the release sheet 3 is measured. The measurement is performed at a measurement environment temperature of 23 ° C. and a humidity of 50%. The average value of the maximum load and the minimum load when such a measurement is performed is defined as the peel resistance.
[0019]
The reinforcing fiber in the prepreg A may be in the form of a woven fabric or the like, but in the case of a tubular molded body, a unidirectional prepreg obtained by impregnating a matrix resin into reinforcing fibers aligned in one direction is reinforced. It is preferable to laminate a plurality of fibers so that the fiber direction is a predetermined direction.
[0020]
The FRP molded article according to the present invention can be produced using only the prepreg A as described above, but is preferably a laminated molded article with the prepreg B.
[0021]
The resin content of prepreg B exceeds 27% by weight and is larger than that of prepreg A. When the tubular body is formed, the prepreg A is arranged such that the fiber direction thereof is oriented in the axial direction of the tubular body (or cylindrical core), and the prepreg B is arranged such that the fiber direction thereof is oriented in the circumferential direction. When the resin content of the prepreg B is 27% by weight or less, the adhesiveness to the prepreg A is deteriorated, and a void may be generated during molding.
[0022]
The prepreg B has a reinforcing fiber weight of 50 g / m ² or less. Preferably 5 to 50 g / ^{m 2,} more preferably 7~45g / ^{m 2,} particularly preferably from 10 to 40 g / ^{m 2.} The prepreg B also has a role of ensuring adhesiveness to the core and the prepreg A when wound around the core. Further, when the tubular body is molded, it is arranged in the circumferential direction, and is not provided to bear the axial bending strength of the molded article. Therefore, it may be thin and the content of the reinforcing fiber may be small. When the fiber weight exceeds 50 g / m ² , the amount of fibers is too large, and impregnation of the resin occurs, and it is difficult to obtain prepreg B of good quality and quality.
[0023]
The molding using the prepreg A and the prepreg B as described above is performed, for example, as follows. Using a unidirectional prepreg A and a unidirectional prepreg B, and a mandrel, prepreg A is arranged such that its reinforcing fiber direction is the axial direction of the mandrel, and prepreg B is arranged such that its reinforcing fiber direction is the circumferential direction of the mandrel. By arranging and molding, a tubular FRP molded body is obtained. However, another prepreg layer may be further used.
[0024]
In the present invention, the decrease in the resin content due to the resin flow during molding is reduced to 0.2% by weight or less as a whole. It is more preferably at most 0.1% by weight. If the decrease in the resin content due to the resin flow is more than 0.2% by weight, voids are generated in the molded body, and a problem occurs in that the bending strength and the compressive strength are reduced.
[0025]
The release sheet used in the present invention can have the peel resistance between the prepreg A and the release sheet within the above range by appropriately adjusting the type and amount of the silicone-based release agent, for example. Preferably, a release sheet having a release degree of 110 to 400 g / 20 mm, more preferably 150 to 340 g / 20 mm, and still more preferably 180 to 300 g / 20 mm is used.
[0026]
The peeling degree of the release sheet is measured as follows.
A release sheet as a sample is fixed on a smooth glass plate, and a permanent adhesive acrylic emulsion type pressure-sensitive adhesive is applied using an applicator (125 μm / wet). Immediately after coating, bake and dry at 100 ° C. for 120 seconds. Immediately, another release sheet of the same kind is placed on the upper side, and is bonded to the surface of the adhesive using a rubber roller. After leaving for about 30 minutes, cut into 2 cm width to make a test piece, measure the force when peeling the upper release sheet by 180 ° peel at a pulling speed of 1 m / min, and measure the release degree of the release sheet. And The measurement length is 10 cm.
[0027]
Further, in case of molding using a prepreg A and prepreg B as described above also, the matrix resin of the prepreg A is Ru least 50 poise epoxy resin der viscosity at 90 ° C.. Preferably, an epoxy resin having a viscosity of 65 poise or more is used. If the resin viscosity is lower than 50 poise, the tackiness of prepreg A is particularly low, the adhesion to prepreg B is poor, and the problem of void formation during molding tends to occur.
[0028]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples. In addition, the evaluation method of the prepreg in this example is as follows.
(1) The prepreg material on which the prepreg material was adhered was cut into 1 m × 1 m squares and left for 1 hour, and the number of convex portions having a major axis of 3 mm or more on the prepreg surface was counted.
[0029]
(2) The prepreg material on which the wrapping release sheet and the prepreg are adhered is cut in the fiber direction to a width of 100 mm and a length of 30 mm, the release sheet is peeled from the prepreg material, and the prepreg is a cylindrical core having a diameter of 15 mm and a length of 500 mm. Wound by hand. After winding, the prepreg was visually observed for wrinkles or projections.
[0030]
(3) Four-point bending strength A FRP cylinder having a length of 850 mm and an inner diameter of 20 mm is formed, and the FRP cylinder is set on two fulcrums at a distance L between the fulcrums of 750 mm, and the center part between the two fulcrums is formed. In the above, measurement was performed by applying a bending load to the FRP cylinder with two indenters at a distance 1 between the indenters of 200 mm from the side opposite to the fulcrum. The loading speed was 5 mm / min, and the bending strength of the FRP cylinder was determined by the following equation.
Bending strength = Maximum bending moment (M) / Section modulus (Z)
M = bending load × (L−1) / 4
Z = (π / 32) × (cylindrical body outer diameter ⁴ −cylindrical body inner diameter ⁴ ) / cylindrical body outer diameter
Example 1
Epicoat 828 and Epicoat 1001 (bisphenol A glycidyl ether (epoxy equivalent: 189): manufactured by Yuka Shell Epoxy Co., Ltd.) 100 parts by weight, dicyandiamide 5 parts by weight, and 3 (3,4-dichlorophenyl) -1,1-dimethylurea 5 parts by weight are uniformly mixed, and a one-part curable epoxy resin composition having a viscosity of 87 poise at 90 ° C. is prepared using a release sheet having a release degree of 190 g / 20 mm to form a resin film. After the carbon fiber bundles (carbon fiber tensile strength 450 kgf / mm ² , elastic modulus 39 tf / mm ² ) are aligned in parallel with each other and in a sheet shape with a uniform tension substantially in parallel with the longitudinal direction of the resin film, A unidirectional prepreg material A having a carbon fiber reinforced prepreg having a width of 600 mm and a resin content of 19% by weight adhered to a release sheet was prepared at the same time as the B stage at the same time as the impregnation through which the fibers were impregnated (125 g / m ² fiber weight). In the obtained prepreg material, the peel resistance between the prepreg and the release sheet was 85 g / 25 mm. Using the resin film made of the above resin composition and the above carbon fibers, a one-way prepreg material B having a resin content of 33% by weight and a fiber weight of 35 g / m ² was prepared. The prepreg B is wound around the iron mandrel having a diameter of 20 mm once so that the fiber axis is in the circumferential direction, and then the prepreg A is wound twice around the fiber axis in the mandrel axial direction, and the prepreg B is further wound in the circumferential direction. Then, a polypropylene tape (width: 15 mm) was wrapped with a tape tension of 3 kg / 15 mm, placed in a curing furnace, and cured at 130 ° C. for 2 hours to prepare a pipe having a length of 850 mm. The resin flow during molding was 0.1% by weight or less as a whole. Table 1 shows the results of measuring the four-point bending strength and void ratio of this pipe.
[0032]
Example 2
A prepreg material A was prepared in the same manner as in Example 1 except that the resin content of prepreg A was changed to 22% by weight, and a pipe was prepared. In the obtained prepreg material A, the peel resistance between the prepreg and the release sheet was 102 g / 25 mm. Table 1 shows the evaluation results.
[0033]
Example 3
A pipe was prepared in the same manner as in Example 1, except that the resin content was 43% and the fiber weight was 35 g / m ² as prepreg B. Table 1 shows the evaluation results.
[0034]
Example 4
A prepreg material A was prepared in the same manner as in Example 1 except that a release sheet having a release degree of 300 g / 20 mm was used. In the obtained prepreg material A, the peel resistance between the prepreg and the release sheet was 210 g / 25 mm. Table 1 shows the evaluation results.
[0035]
Comparative Example 1
A pipe was made in the same manner as in Example 1 except that the resin content of prepreg A was changed to 12% by weight. In the obtained prepreg material A, the peel resistance between the prepreg and the release sheet was 8 g / 25 mm. Table 1 shows the evaluation results.
[0036]
Comparative Example 2
A prepreg material was prepared in the same manner as in Example 1, except that a release sheet having a degree of release of 95 g / 20 mm was used in the prepreg material A. In the obtained prepreg material A, the peel resistance between the prepreg and the release sheet was 4 g / 25 mm. Table 1 shows the evaluation results. Due to the large number of bumps, wrinkles occurred when wound around the mandrel, and only pipes with low bending strength and high void ratio were obtained.
[0037]
Comparative Example 3
A prepreg material A was prepared in the same manner as in Example 1 except that a release sheet having a release degree of 370 g / 20 mm was used. In the obtained prepreg material A, the peel resistance between the prepreg and the release sheet was 270 g / 25 mm. Table 1 shows the evaluation results together with the ruggedness, winding property and the like of the prepreg material. When wound around a mandrel, it was difficult to peel off the release sheet from the carbon fiber reinforced prepreg, and the winding took a very long time.
[0038]
Example 5
A pipe was made in the same manner as in Example 1 except that the resin content of prepreg A was changed to 27% by weight. Table 1 shows the evaluation results. From the viewpoint of reducing the weight of the pipe, it was determined that the resin content was close to the limit.
[0039]
Comparative Example 4
A pipe was made in the same manner as in Example 1, except that the resin content of prepreg B was changed to 25% by weight. Table 1 shows the evaluation results. Poor adhesion to prepreg material A was observed, voids were generated between layers, and only pipes having low bending strength were obtained.
[0040]
Comparative Example 5
A pipe was made in the same manner as in Example 1 except that the composition of Epicoat 828 and Epicoat 1001 in Prepreg Material A was adjusted and a resin having a viscosity of 34 poise at 90 ° C. was used. The resin viscosity was too low, the adhesion to the prepreg material B was poor, voids were formed between the layers, and only pipes with low bending strength were obtained. As a result, it was found that in the present invention, it is also important to appropriately adjust the resin viscosity.
[0041]
In each of Examples and Comparative Examples, 20 pipes were formed. In Examples 1 to 5, the wrapping tape did not bite at all, but in Comparative Examples 2, 4, and 5, two of the 20 wrapping tapes bite, and there was a problem that quality defects occurred. Was.
[0042]
[Table 1]

[0043]
【The invention's effect】
According to the method for producing an FRP molded article of the present invention, the resin content of the prepreg A and the peel resistance with the release sheet are in a specific range, the matrix resin of the prepreg A is an epoxy resin having a specific range of viscosity, and The resin flow at the time of molding is set to a specific value or less, or the prepreg A is cross-laminated with the prepreg B having a specific resin content and a specific fiber weight, and the resin flow at the time of molding is set to a specific value. By setting the content as described below, an FRP molded article having less ruggedness, less voids, and excellent lightness on the surface of the prepreg to be used is obtained despite the low resin content of the prepreg. In addition, it is possible to obtain an FRP molded article which is excellent in quality and strength without biting the wrapping tape.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view showing a jig to which a prepreg material is adhered, which is used when measuring a peel resistance between a prepreg and a release sheet in the present invention.
FIG. 2 is a schematic side view showing a state of a tensile test when measuring a peel resistance between a prepreg and a release sheet in the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Double-sided adhesive tape 2 Prepreg 3 Release sheet 4 Stainless steel plate 5 Thread 6 Clip 7 Upper gripper of tensile tester 8 Lower gripper of tensile tester

Claims (6)

At least, the resin content is in the range of 15-27 wt%, Ri range near the peeling resistance 40~250g / 25mm of the release sheet, and the matrix resin is at least 50 poise viscosity at 90 ° C. A method for producing an FRP molded article, comprising molding using prepreg A, which is an epoxy resin, such that a reduction in resin content due to a resin flow is 0.2% by weight or less as a whole. The method for producing an FRP molded article according to claim 1 , wherein the prepreg A is a one-way prepreg . The prepreg A according to claim 1 or 2, and a prepreg B having a resin content of more than 27% by weight and a reinforcing fiber weight of 50 g / m ² or less are laminated so that the directions of the reinforcing fibers intersect each other. A method for producing an FRP molded article, comprising: The method for producing an FRP molded article according to claim 3, wherein the prepreg B is a unidirectional prepreg . 5. The FRP molded article according to claim 4, wherein a prepreg A is disposed so that a reinforcing fiber direction thereof is in an axial direction of the mandrel, and a prepreg B is disposed such that a reinforcing fiber direction thereof is in a circumferential direction of the mandrel using a mandrel . Production method. The method for producing an FRP molded article according to any one of claims 1 to 5, wherein the release degree of the release sheet on the side to which the prepreg A is attached is in the range of 110 to 400 g / 20 mm .

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