JPH0533645B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of Industrial Application) This invention relates to a structural material suitable for use in racket frames for tennis, squash, badminton, etc., poles for tent frames, pipes for structural materials, buried earthen pipes, blocks, fishing rods, etc., and a method for producing the same. It is related to. (Conventional technology and its problems) Fiber-reinforced composite materials that have been used as structural materials for building materials, sports equipment, etc. include materials that have a thermoplastic resin matrix and short fiber reinforcement added to this, and There is a material in which long fiber reinforcement is added to a thermosetting resin matrix. However, each of these materials has the following problems in terms of formability, strength, heat resistance, fatigue properties, etc., and there has been a strong demand for better fiber-reinforced composite materials. For example, in recent years, reinforced plastic poles have been appearing on the market as poles for mountain climbing tents, but they have the following problems.
It is still only partially used in fields where usage conditions are relatively lenient, such as in leisure tents. In other words, the structure of these reinforced plastic poles is that the reinforcing fibers are glass, carbon, and aromatic polyamide, and the matrix is epoxy.
Thermosetting resin such as polyester is used. The most commonly used manufacturing method for reinforced plastic poles is the so-called "drawn pipe" method, in which glass fibers are impregnated with polyester resin and continuously introduced into a curing tank to harden.
It's the manufacturing method. Some fibers are processed not only in the axial direction but also in the F/W process, and some use thermoplastic resins such as ABS resin as the core material or coating material, but in all cases, the reinforcing fiber matrix is made of thermosetting polyester, epoxy, etc. It is a synthetic resin. However, these thermosetting resins are inherently brittle and have the disadvantage of being easily broken when used in large bends like tent poles. Also,
If the rigidity is lowered to increase the amount of deflection during use, problems will arise in terms of comfort and wind pressure resistance.
In particular, when several poles are connected and used, stress concentration occurs at the joint, and most of the fractures occur at the joint. However, in the continuous pultrusion method, since the cross section is uniform, it is difficult to integrally reinforce only the joint portion. In addition, in the case of the F/W manufacturing method, it is difficult to change the complicated joint shape and outer diameter, and there are major problems such as dimensional accuracy and performance variations due to non-uniformity of tape wrapping. . On the other hand, the structure of fiber-reinforced plastic used as a material for golf club shafts is that carbon, glass, aromatic polyamide, boron, etc. are used as the reinforcing fibers, and thermosetting resins such as epoxy and polyester are used as the resin matrix. is used. The main feature of both shafts is that they are lighter than metal shafts, and they have the advantage of increasing head speed when the golfer swings, making it easier for even weak golfers to swing. The manufacturing method for this type of shaft can be roughly divided into the following two types. (1) Filament winding (F/W) method A continuous filament is impregnated with resin and wound on a mandrel at a predetermined angle in the axial direction. (2) Sheet winding method A cloth pre-impregnated with resin is wound around a mandrel. Both (1) and (2) are formed on a mandrel, wrapped with heat shrink tape, and fired in a curing furnace. However, in this manufacturing method, the dimensional accuracy during material molding is not sufficient, and the pressure during curing is dependent on the tightening force of the wrapped tape, so there is a limit to the dimensional accuracy of the product. Also, the wrapping tape may leave traces on the product.
Since the surface is buffed using a centerless glider, etc., there is a drawback that some of the fibers on the surface are removed. Furthermore, it is difficult to discontinuously change the complicated shape or outer diameter, and the degree of freedom in design is severely restricted. Furthermore, thermosetting resins such as epoxy and polyester are inherently brittle and have a high risk of breaking upon impact. Furthermore, the following two types of fiber-reinforced plastic structures for ball game racket frames are known. (1) Continuous fiber/resin matrix system (2) Short fiber or chopped fiber/resin matrix system Among these, those shown in (1) use epoxy, polyester, or phenolic thermosetting resin as the resin matrix. A continuous filament is impregnated with the resin, and the resin is cured by heating and pressure and molded into the desired shape. In addition, the type shown in (2) is a type in which the reinforcing members are composed of short discontinuous length fiber reinforcing members randomly dispersed in a resin matrix, and this resin may be either thermoplastic or thermosetting. Good too. As the thermosetting material, those shown in (1) are used, and as the thermoplastic material, for example, nylon,
polycarbonate, polyphenylene oxide,
These include acetals and other industrial thermoplastics. The molding method is mainly injection molding. On the other hand, characteristics required of a racket include toughness, rigidity, and repulsion. Regarding toughness, as for (1), the toughness of the matrix resin is poor, so expensive reinforcing fibers such as carbon fibers are usually
It is customary to obtain the necessary toughness by using 70% by weight. Most of the current tennis racket frames that use reinforced plastic use this manufacturing method because it is easy to obtain the required strength and shape. Regarding (2), the molecular weight of the matrix resin is usually kept low in consideration of moldability, especially fluidity during injection. Further, the fiber content is approximately 30% by weight, and the fiber length is often 1 mm or less (0.2 to 0.3 mm) after pelletizing and injection molding. Since the matrix resin does not have a high molecular weight and the length of the reinforcing fibers is extremely short, no improvement in mechanical strength can be expected with this configuration. Therefore, when it is stored in the trunk of a car in a stretched state, its internal temperature reaches 80 degrees Celsius.
If the temperature exceeds ℃, there is a high possibility that it will deform or break during use. In order to compensate for these drawbacks, it is necessary to make the racket frame thicker, but this is not very practical as it becomes heavier. In addition, as leisure sports have become more popular in recent years, it has become necessary to take into account sports injuries. For example, in one survey, about one-third of hard racket players answered that they had experienced pain in their elbows. Commonly referred to as tennis elbow, it is a condition in which the elbow on the side that holds the racket becomes painful for no particular reason while playing tennis. Rackets with poor vibration absorption properties are generally thought to cause vibrations to be transmitted to the elbow when struck, causing damage to the epicondyle of the humerus. This is thought to be due to the fact that in the continuous filament/resin matrix system listed in (1) above, which is currently the mainstream material for racket frames, the normally used epoxy resins and polyester resins have poor shock absorption properties. In addition, as a literature regarding industrial materials using nylon resin similar to the material used in the present invention, for example, "Nylon RIM Development for Automotive Body Panels" (SAE Technical Paper Series)
850157; 1985), "Nylon 6 RIM" (1985
American Chemical Society), and in addition to these, terminal amine polyether
(SAE Technical Paper on RIM)
Series 850155; 1985), an article in the American Chemical Society (1985) about the future of RIM in the United States, and an article in Plastakes Technology; May 1985 issue about RIM monomer casting. There is no description regarding long fiber reinforced products in any of the documents. (Object of the invention) The present invention has been made in view of the above circumstances, and
The purpose of the present invention is to provide a structural material that is excellent in lightness, strength, flexural modulus, etc., and has a greater degree of freedom in design of shape and material than conventional materials. (Disclosure of the Invention) The structural material according to the present invention (first invention) is a structural material made of a polyamide resin reinforced with continuous fibers and/or long fiber reinforcement, and the polyamide resin is formed by monomer casting. The fiber reinforced material is characterized in that it is surface-treated with a nylon surface treatment agent that is alcohol-soluble, water-soluble, or soluble in both alcohol and water. Further, the method for manufacturing a structural material according to the present invention (second invention) includes:
A method for producing a structural material made of polyamide resin reinforced with continuous fibers and/or long fiber reinforcement, the method comprising making the continuous fibers and/or long fiber reinforcement alcohol soluble, water soluble, or both alcohol and water. On the other hand, the surface of nylon is pre-treated with a soluble nylon surface treatment agent, placed in a predetermined shape, and placed in a mold.
The structural material is formed using a monomer casting method in which lactams are injected into a mold and heated to form a polyamide resin. The ω-lactams used in the present invention include α-pyrrolidone, α-piperidone, and ε-lactam.
Caprolactam, ω-enantholactam, ω-caprylolactam, ω-pelargonolactam, ω-
Decanolactam, ω-undecanolactam, ω-
laurolactam or these c-alkyl-substituted -ω-lactams, and two or more of these ω
- mixtures of lactams, etc. However, the industrially advantageous lactams are ε-caprolactam and ω-
It is laurolactam. Moreover, the ω-lactams can contain a modifying component (soft component) as necessary. The soft component is a compound that has a functional group that reacts with the initiator used in the molecule and has a low Tg, and is usually a polyether or liquid polybutadiene that has a functional group. Commercially available raw materials used in the present invention include nylon RIM raw materials manufactured by Ube Industries, Ltd., such as UX-21. This is composed of component A consisting of an alkali catalyst and caprolactam, and component B consisting of caprolactam and a prepolymer containing a soft component. Further, as the anionic polymerization catalyst used in the present invention, sodium hydride (NaH) is preferable, but other known ω-lactam polymerization catalysts such as sodium, potassium, lithium hydride, etc. can be used. The amount added is preferably in the range of 0.1 to 5.0 mol% based on the ω-lactam. In addition, as a weight initiator, N-acetyl-ω-
Caprolactam is used, but other triallylisocyanurate, N-substituted ethyleneimine derivatives, 1,1'-carbonylbisaziridine, oxazoline derivatives, 2-(N-phenylbenzimidoyl)acetanilide, 2-N-morpholino -Cyclohexane-1,3-dicarboxanilide, etc., and already known compounds such as isocyanates and carbodiimides can also be used. The amount of these polymerization initiators added is desirably within the range of 0.05 to 1.0 mol % based on the amount of ω-lactam. In addition, the methods for adding it include (A) a method of directly adding and mixing it to an ω-lactam liquid containing an anionic polymerization catalyst; (B) a method of directly adding and mixing it to an ω-lactam liquid containing an anionic polymerization catalyst;
Method of mixing an ω-lactam liquid containing a polymerization initiator (C) There is a method in which the ω-lactam is added in advance to a solid or liquid ω-lactam together with an anionic polymerization catalyst, but any of these methods may be used. do not have. In addition, the polymerization temperature is generally preferably 120 to 200°C, but for special purposes it may be lower than 120°C or
It is also possible to carry out the polymerization at temperatures above 200°C. Continuous fibers, which are reinforcing materials, can be carbon fiber, aramid fiber, glass fiber, alumina fiber, or
Silicon carbide fibers, steel wires, amorphous metal fibers and/or mixtures thereof can be used as cloth,
Used in sleeve or roving form. For example, when producing a pipe-like structural material, the continuous fibers and/or long fibers are placed in a mold by winding the required amount around the core or by covering the core as a sleeve. When obtaining a block-shaped product, it may be placed in advance in a mold. When forming continuous fibers or long fibers into a desired shape in advance, and when placing the formed fibers at a predetermined position in a mold, it is necessary to coat the fiber surface with a sizing material. Conventionally, epoxy resin has been commonly used as this coating material. When fibers coated with epoxy resin are used for monomer casting, the epoxy resin inhibits the polymerization of the monomer, reducing the strength of the finished structural material. Experimental results show that pre-surface treatment of fibers using a nylon surface treatment agent that is alcohol-soluble, water-soluble, or soluble in both alcohol and water provides superior strength. Obtained. Since the present invention uses a monomer casting method, there is no restriction on molecular weight in consideration of moldability, and high molecular weight polyamide resin can be obtained, which has high strength, elastic modulus, and heat distortion temperature. The thickness can be reduced and the weight can be reduced. In addition, there is a so-called stampable sheet as a material in which thermoplastic resin is reinforced with long fibers, and a sheet made of nylon resin and continuous glass fiber mat can be considered as a nylon-based material. When obtaining a molded product with a desired shape, there are the following problems.
In other words, when using a stampable sheet as a molding material, it is necessary to handle the original fabric heated and melted outside the mold, but the temperature at this time is a high temperature of 200 to 350°C, and the molten original fabric is It is soft and extremely difficult to handle. Furthermore, since a heating device using far infrared rays is required, equipment costs are high. Furthermore, the press pressure during molding is as high as 100 to 300 kg/cm ² , and equipment costs such as molds are high. In addition, the reinforcing fibers may stand out on the surface of the molded product, and the air that has been drawn in when heating the material cannot escape during molding and remains behind, resulting in a poor surface finish. Moreover, it is difficult to mold thin, complicated, and shaped materials. Therefore, it can be said that the present invention based on the monomer casting method is far superior. In addition, in the present invention, since a polyamide resin that is extremely tough is used compared to a thermosetting resin that is inherently brittle, the amount of reinforcing fibers can be reduced, and in particular, by using continuous fibers and/or long fibers. Furthermore, further reinforcement and reduction of reinforcing fibers can be achieved, making it possible to achieve economical efficiency and weight reduction at the same time. In addition, the excellent vibration damping properties of the polyamide resin used in the matrix resin are even more noticeable because only a small amount of reinforcing fibers are required, making them ideal for racket frames, ball game shafts, and other products that are lightweight, durable, and have excellent appearance. This results in a structural material of 100%. Example 1 As shown in Fig. 1, a mandrel 1 made of SUS
Carbon fibers 2 woven at an angle of 25° in the axial direction were arranged around the mold in an amount such that the weight percentage was 35%, and the carbon fibers were placed in the mold. At this time, in the joint part 3, a radius is provided at a position where stress concentration occurs during bending deformation, so that there is a surface contact, and the uneven part is tapered, and the second
The thickness of the A and B sections, which were prone to breakage with the conventional right-angled cross-section joint shown in the figure, can be made thicker. This mold was heated at 150°C, and then the pressure inside the mold was reduced to 1 mmHg using a vacuum pump. 100g of ω-caprolactam was heated and melted at 130°C while substituting with nitrogen in flask 1.
0.21 g of NaH (50% oil) was added and completely reacted and dissolved. 100g in the other flask at the same time
ω-caprolactam was weighed out, heated and melted at 130° C. while replacing the mixture with nitrogen, and then 0.13 g of N-acetyl-ω-caprolactam was added and completely dissolved. The lactam mixture was simultaneously injected into the mold and kept at 150°C for 30 minutes. After being removed from the mold, it was annealed in oil at 90°C for 2 hours and then heated in boiling water for 3 hours. As a result, a structural material pipe 4 having excellent lightness, bending elasticity, and bending strength was obtained. Example 2 As shown in FIG. 3, the same procedure as Example 1 was carried out except that the outer diameter of the concave portion of the joint portion 3 was increased to increase the strength of the joint portion. As a result, as in the case of Example 1, lightness and
A structural material pipe 4 having excellent bending elasticity and bending strength and having a reinforced joint portion was obtained. Example 3 Carbon fibers 2 woven at an angle of 25 degrees in the axial direction were placed around the SUS mandrel 1 shown in Fig. 4 in an amount of 35% by weight, and molded. It was installed inside. this mold
It was heated at 150°C, and then the pressure inside the mold was reduced to 1 mmHg using a vacuum pump. 100g of ω-caprolactam was placed in a flask of 1 while purging with nitrogen.
Melt by heating to 130℃ and add 0.21g of NaH (50% oil).
was added for complete reaction and dissolution. the other one at the same time
100 g of ω-caprolactam was weighed into a flask, and heated and melted at 130°C while substituting with nitrogen. 0.13 g of N-acetyl-ω-caprolactam was added and completely dissolved. The lactam mixture was simultaneously injected into the mold, the lid was quickly closed, and the temperature was kept at 150°C for 30 minutes. As a result, a hollow pipe-shaped golf club shaft 5 was obtained. Next, a persimmon head was attached to the tip part 6 of FIG. 4, and a rubber grip was attached to the grip part 7 to prepare a product. There were no problems with durability when actually shooting golf balls. Example 4 As shown in FIG. 5, the process was carried out in the same manner as in Example 3 except that the thickness of a part of the shaft 5 (portion P) was made smaller than the other part and the carbon fibers 2 were arranged. Ta. Position the P part on the tip 6 side or on the grip 7 side.
By changing the position to the side, the position of the tight point could be freely designed. Example 5 Structural materials of the present invention were manufactured using the same monomer casting method as in Example 1, except that the fiber angle was 15°, with various amounts of carbon fibers. The results of examining the bending modulus, bending strength, fatigue properties, heat resistance, and fracture energy of the structural materials obtained in this way are shown in Figures 6, 7, and 8.
The results were as shown in FIG. 9, Tables 1 and 2. In these figures, A represents the product of the present invention, and B represents the product of the present invention.
1 is a sample made of an epoxy matrix reinforced with carbon long fibers, C is a sample made of a polyamide resin material using short fiber (carbon fiber) reinforcement, and D is a commercially available epoxy matrix reinforced with carbon long fibers. E represents a sample cut from a tennis racket frame made of a polyamide resin/short fiber (carbon fiber) material. To be more specific about each sample above, A is from Ube Industries, Ltd.
UBE nylon RIM (UX-21) reinforced with continuous carbon fiber (BC-7364-24 manufactured by Toho Rayon Co., Ltd.), B is carbon fiber prepreg (HYE 1648 AIE manufactured by Kasei Fiberlite Co., Ltd.), C D is BASF Ultra Mid (6,6 nylon) A3W reinforced with short carbon fibers, D is Dunlop Tennis.
E represents the material cut out from MAXPOWER-DX, and E represents the material cut out from Dunlop Tennis MAX200G. All samples other than B are comparative examples. As can be seen from Table 1, product A of the present invention has a higher retention rate of flexural modulus at high temperatures despite having a lower reinforcing fiber content than B and C, and has better heat resistance than comparative examples. It turns out that she has excellent sex. Note that among B, (I) is a special material using heat-resistant resin for aerospace, but A has better heat resistance than this. Furthermore, Table 2 shows the magnitude of fracture energy, and the larger this value is, the more difficult it is to fracture. In the same table, the fracture energy of A is slightly lower than B, but the reinforcing fiber content of A is lower than that of B.
Considering that the breaking strength of A is approximately half that of B, it is considered that A is superior to B in terms of breaking strength when the same amount of fibers are included. Furthermore, Figures 6 and 7 show the relationship between carbon fiber content and flexural modulus, and the relationship between carbon fiber content and flexural strength.A is higher than C in both flexural modulus and flexural strength. It can be seen that A is equivalent to or higher than B if the carbon fiber content is considered. In addition, it can be seen that in A, by adjusting the amount of carbon fiber, it is possible to obtain the bending elastic modulus and bending strength according to the required characteristics. Note that B has less freedom in design than A because it is difficult to reduce the amount of carbon fiber in actual manufacturing. Figure 8 shows the fatigue characteristics, A, B,
Since the fracture strength differs depending on each material of C, the fatigue test results were expressed as the ratio of fatigue stress to each fracture strength. As can be seen from the figure, A is particularly superior to B and C. In addition, numerical values such as 45.5Kg/mm ² , 14.5Kg/mm ² , 50Kg/mm ² etc. in the figure represent fatigue stress values when the durability limit is 10 ⁵ times. Figure 9, like Figure 8, shows the ratio of fatigue stress to fracture strength, where A is the structural material (carbon fiber) of the present invention formed by the monomer casting method, and A' is the continuous reinforcing material. Each represents a composite material (stampable sheet) made of nylon resin using glass fiber mat. As can be seen from the same table, A has better fatigue characteristics than A'. In addition, 91Kg/mm ² , 8 in the figure
The value Kg/mm ² represents the fatigue stress value when the durability limit is 10 ⁵ times, as in the case of Fig. 8. The test conditions were a three-point bending test with a fiber angle of ±15° for the bending elastic modulus and bending strength, and a test speed of 2.5 mm/min. The span interval was 100 mm, and the test piece dimensions were 4 (thickness) x 10 (width) x 150 (length) mm.
The fatigue test was conducted using a three-point bending fatigue test at a constant stress and a frequency of 1 Hz. The fiber angle was ±15°, the test piece dimensions were 4 (thickness) x 10 (width) x 150 (length) mm, and the span interval was 80 mm, and the durability limit was set at 10 ⁵ times. Fracture energy was measured under the same conditions as bending strength. Heat resistance is 100℃ from the rigidity (E20) at room temperature.
(E100) and the retention rate of rigidity at 150°C (E150) (E100/E20, E150/E20). The equipment used in each of the above tests was manufactured by Intesco Co., Ltd.
It was TYPE2050. Furthermore, the damping performance is 4 (thickness) × fiber angle ±15°
A material of 10 (width) x 150 (length) mm was suspended with a string, an impact was applied with an impact hammer, the acceleration (α) was measured with an acceleration pick-up, and α/F was frequency analyzed. The damping ratio (ζ) was calculated using Dynamic Analyzer 3562A manufactured by YHP Corporation. That is, the above α/F was subjected to frequency analysis, and ζ was determined from FIG. 10 using the following equation. ζ=(1/2)×(Δω/ωn) T ₀ =Tn/√2 The results show that nylon resin (UX-21 heated and polymerized) that does not contain reinforcing fibers
0.0558, 0.0107 for those containing continuous carbon fibers without surface treatment (fiber angle 17°), 0.0135 for those containing continuous carbon fibers surface treated with a nylon surface treatment agent (fiber angle 12°), surface treatment Containing continuous carbon fibers (fiber angle 19°) without
0.0122, nylon resin (NY66) containing 15% by weight of short carbon fibers is 0.0230, 30% by weight of nylon resin (NY66) is 0.0159, epoxy resin containing long carbon fibers is 0.0098, short fibers in nylon matrix A specimen cut from a commercially available racket frame (Max 200G PRO) reinforced with carbon fiber was
It was 0.0323. As can be seen from these data, the structural material according to the present invention is excellent in various aspects such as strength, heat resistance, and fatigue properties. Example 6 Around a nylon tube, which is a synthetic resin tube, a cloth made of 45% aromatic polyamide resin (trade name: KEVLAR49) made of braided carbon fiber was wrapped around it in an amount that made it 10% by weight. It was installed inside the mold of a mid-sized tennis racket frame. Heat this mold at 150℃,
Next, the pressure inside the mold was reduced to 1 mmHg using a vacuum pump. 300g of omega-caprolactam 1
was heated and melted in a flask at 130° C. while purging with nitrogen, and 0.64 g of NaH (50% oily) was added to completely react and dissolve. At the same time, 300 g of ω-caprolactam was weighed into the other flask 1, and heated and dissolved at 130° C. while replacing the flask with nitrogen. 0.4 g of N-acetyl-ε caprolactam was then added and completely dissolved. Inject the lactam mixture into the mold at the same time, quickly close the lid, and incubate at 150°C for 30 minutes.
I kept it. Next, the core portion 16 was filled with urethane foam, and a grip was attached to the shaft portion 10b to produce a product as shown in FIG. 11. This tennis racket frame 10 included a head portion 10a and a grip portion 10b, and the product weight was 325 g.
There were no problems with the durability of this frame 10 when playing with full strength. Figure 15 shows the vibration damping characteristics of this racket with strings attached. FIG. 15 is according to the present invention, and has the cross section shown in FIG. 13, and as described above, the core filled in the core portion 16 is foamed urethane, 15 is a nylon tube, and 14 is a resin layer (nylon) on the surface. This shows the vibration damping waveform when a continuous filament sleeve of aromatic polyamide resin (trade name: KEVLAR49) with a carbon fiber content of 45% and a content of 10% by weight is used as the fiber of the base material 13. Moreover, FIG. 12 and FIG. 16 are comparative examples, in which the core 12 is made of urethane foam, and the outer part 13 is made of continuous filament of 70% by weight of carbon fiber.
The figure shows the vibration damping waveform of a racket made by hardening an epoxy resin containing the following by applying heat and pressure and molding it into a desired shape. 14 is a resin layer (epoxy resin). The weight of this racket was 340g. The vibration damping waveform was obtained as follows. That is,
As shown in FIG.
a) Attach an aluminum plate 20 to the grip to dampen vibrations when the ball is hit by letting the ball fall naturally as shown in the figure, centered on the hitting surface of the racket 18, which is hung on a string with the side facing up. accelerometer 19
and observed it as a vibration-damped waveform on a cathode ray tube. From the thus obtained attenuation waveforms shown in FIGS. 15 and 16, the damping ratio ζ was calculated using the following formula based on FIG. 17. ζ=1/2π(n-1)・lnω ₁ /ω _o When the damping ratio was calculated, the one in Figure 16 was obtained.
0.0222, while the one in Figure 15 is 0.0582
It was hot. As can be seen from these data, the product of the present invention has extremely superior vibration damping characteristics compared to conventional products. Example 7 Component A (caprolactam containing an alkali catalyst) and component B (caprolactam containing a prepolymer) of UBE nylon RIM (UX-21) are heated and melted at 90 to 100°C while substituting with nitrogen to obtain both components A and B. Quickly mix and add 0.5% of Toray AQ nylon (A-70).
It was poured onto carbon fibers (reinforcing material) whose surface had been treated with methanol solution and kept at 150°C for 10 minutes. Using this product, a racket frame similar to that of Example 6 was manufactured. The obtained racket frame showed performance equivalent to or better than that of the product of Example 6. Example 8 The same procedure as in Example 7 was carried out except that cloth was used as the reinforcing fiber so that the carbon fiber content was 30% by weight. The frame head wall thickness is 1.5mm (average)
It was hot. The resin of this racket frame had an intrinsic viscosity [η] of 3.07. (Solvent m-cresol; according to ISO307). Example 9 The carbon fiber content is 70% by weight, the area of the ball hitting surface of the frame is increased by 170% compared to the mid size, and the thickness of the head part of the frame is up to 1 mm thicker than in Example 8. The same procedure as in Example 8 was carried out except for the following. Example 10 20 layers of plain weave cloth made of Toray carbon fiber T-300 (3000 filament) were laminated and set in a mold, and molten ω-lactam containing a polymerization catalyst and an initiator was injected into the mold. A plate-shaped sample of polyamide resin was prepared by heating. Carbon fibers coated with the following two types of sizing agents (A and B) were prepared in advance and used. A. Alcohol-soluble nylon A-70 manufactured by Toray Industries (0.5% concentration) B. Epoxy sizing agent (0.5% concentration) The mechanical properties of the obtained samples were measured and the results are shown in the attached table. In addition, the amount of fracture deflection, bending elastic modulus, and bending fracture stress are based on JIS
It was measured according to the test method of K7055, and the interlaminar shear strength was measured according to the test method of JIS K7057. From this result, it can be seen that when fibers coated with an epoxy sizing agent are used, strength etc. are lowered due to poor polymerization. [Effects of the Invention] The structural material according to the present invention does not use a brittle thermosetting resin as a matrix resin, but uses a polyamide resin with excellent strength, and furthermore, this is reinforced with continuous fibers and/or long fibers. By reinforcing the material, we were able to obtain a structural material with excellent lightness, strength, flexural modulus, vibration damping properties, etc. This structural material is produced by the manufacturing method according to the second invention, that is, by arranging the fiber reinforcing material in a predetermined shape in advance, and adding a resin to serve as a matrix by a monomer casting method. Since it can be manufactured, it is easy to mold and can be molded into various shapes. Conventional fiber-reinforced composite materials have been manufactured using the Primics method, in which reinforcing materials are mixed with resin in advance and then molded, which generally makes it difficult to mold into complex shapes. In comparison, the product of the present invention is easier to mold as described above and has a greater degree of freedom in design.

【table】

【table】 [Brief explanation of drawings]

1 to 5 are cross-sectional views showing embodiments of the present invention, FIGS. 6 and 7 are graphs showing elastic modulus and bending strength, FIGS. 8 and 9 are graphs showing fatigue curves, and FIG. Fig. 10 is an explanatory diagram of the method of calculating the damping ratio, Fig. 11 is a front view of the tennis racket frame, Fig. 12 is a sectional view of the conventional product, Fig. 13 is a sectional view of the product of the present invention, and Fig. 14 is the attenuation. FIG. 15 and FIG. 16 are graphs showing the attenuation waveforms of the example and comparative example, and FIG. 17 is an explanatory diagram of the method of calculating the attenuation ratio. 1... Mandrel, 10... Racket frame, 10a... Head part, 10b... Grip part.

【table】

【table】

Claims (1)

[Scope of Claims] 1. A structural material made of a polyamide resin reinforced with continuous fibers and/or long fiber reinforcement, wherein the polyamide resin is formed by monomer casting, and the fiber reinforcement is made of alcohol. A structural material characterized by being surface-treated with a nylon surface treatment agent that is soluble, water-soluble, or soluble in both alcohol and water. 2. The structural material according to claim 1 or 2, wherein the polyamide resin has an intrinsic viscosity [η] of 1.8 or more. 3. The structural material according to claim 1 or 2, wherein the polyamide resin contains 10 to 80% by weight of continuous fiber reinforcement and/or long fiber reinforcement. 4. The structural material according to any one of claims 1 to 3, wherein the structural material is a rod. 5. The structural material according to any one of claims 1 to 3, wherein the structural material is a tennis racket. 6. A method for producing a structural material made of polyamide resin reinforced with continuous fibers and/or long fiber reinforcement, the continuous fiber and/or long fiber reinforcement being alcohol-soluble, water-soluble, or both alcohol and water. The surface of the nylon is pre-treated with a soluble nylon surface treatment agent, placed in a mold in a predetermined shape, and then molten omega-lactams containing a polymerization catalyst and an initiator are injected into the mold. A method for manufacturing a structural material, comprising forming the structural material using a monomer casting method in which polyamide resin is formed by heating. 7. The method for manufacturing a structural material according to claim 6, wherein the structural material is a rod. 8. The method for manufacturing a structural material according to claim 6, wherein the structural material is a tennis racket frame.