JPH039858B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a fiber-reinforced resin cylindrical molded article having a foamed resin layer. Conventionally, fiber-reinforced resin cylindrical molded products having a foamed resin layer have been put to practical use in water tanks, heat-resistant containers, etc. for the purpose of improving heat retention performance, rigidity performance, etc. The molding method used is a reinforcing material such as glass fiber and a liquid thermosetting resin such as unsaturated polyester resin, using various molding methods such as hand lay-up method, centrifugal molding method, and filament winding method. A common method is to first form a fiber-reinforced resin molded body, and then attach a fixed length plate of various synthetic resin foams to the molded body using an adhesive or the like. In the case of a Sanderutsch molded product, a fiber-reinforced resin molded layer is further formed on the outer peripheral surface of the foam in the next step to obtain a composite molded product. This method is cumbersome and requires a long working time, as it involves applying an adhesive to each foam of a fixed length one by one. Another technical problem is that since there are seams on the foam surface, it is necessary to fill the seams with putty or the like, which is time-consuming and reduces heat retention performance.
In addition, in the case of a cylindrical shape, a curved part occurs, so it is necessary to bend and attach the standard length foam to match the radius of curvature. Due to this phenomenon, it is difficult to adhere with perfectly matched curvatures.
Generally, when attaching a foam to a fiber-reinforced resin body using a flat object, pressure is applied with a weight to improve adhesion, but in the case of a cylindrical molded object with a curved part, a weight is applied. Even when applying pressure, it is necessary to repeat the work several times at regular intervals, so the time required to complete one molded product becomes enormous. Although it is possible to use hydraulic pressure or the like to improve the adhesion of the foam, it requires large-scale equipment and is economically problematic. In order to solve this problem, it can be easily imagined that a foaming resin is sprayed from the outside of the fiber-reinforced resin molded body using a spray machine or the like to form a foam layer. However, when blowing foam from the outside, about 30% of the supplied material is dispersed into the air as mist, which goes against resource conservation and is extremely problematic in terms of the working environment.Especially in the case of urethane foaming, isocyanates are present. It is toxic and poses health problems for workers. In order to improve the above-mentioned drawbacks, JP-A-49-
In No. 8562, a mold release sheet is attached to the inside of a rotating cylindrical body, a foamed synthetic resin layer is formed inside this mold release sheet, and then roving-shaped reinforcing fibers are attached in the axial direction of the cylindrical body. A shaft-like body wrapped with roving-like reinforcing fibers such as glass fibers with approximately the same dimensions as the length of the mold body is installed approximately in the center of the mold body, and is wound inside the foam layer using centrifugal force, so that the winding is transferred. After finishing the process, insert a shaft-like body with a nozzle for supplying resin and a shaft-like body with approximately the same size as the length of the mold body, in the same way as when supplying reinforcing material, in the center of the mold body axis. A centrifugal molding method has been proposed in which a resin is sprayed onto the fibers through a fixed nozzle, and centrifugal force is used to impregnate the fiber reinforcement with the resin to obtain a composite tube that covers the inner peripheral surface of the foam layer. There is. This method is an excellent molding method in that the foam resin layer and the fiber-reinforced resin layer are continuously molded, and there is no seam in the foam resin layer, and the inner-roll molding is effective in terms of the working environment and economy. be. However, as is well known, glass fibers and carbon fibers called reinforcing fibers generally have a specific gravity that is approximately twice or more than that of resin. Therefore, if two types of substances with different specific gravities are supplied to the rotating body in a state where centrifugal force is exerted, as in the example of the patent,
It is located in substances with high specific gravity. That is, first, the glass fiber with a high specific gravity is placed on the outside, and the resin sprayed over it has a low specific gravity, so it completely separates from the glass fiber, and the resin does not penetrate into the glass fiber. This results in no adhesion between the fiber reinforced resin layer and the foam layer. In addition, this method fixes separate shaft-like bodies of resin and fiber reinforcement material, each having approximately the same length as the mold body, near the central axis of the mold body, and supplies the fiber reinforcement material and resin in separate processes. However, it is not concrete how to move and operate the shaft-shaped body during actual molding, and it is extremely difficult to realize. The present inventors have successfully produced a foam resin layer and a fiber-reinforced resin layer seamlessly and continuously, and formed a cylindrical molded product that is superior in terms of environmental hygiene and in terms of economy and performance. As a result of intensive research on the method, the present invention was arrived at. That is, the present invention provides (A) a fiber-reinforced thermosetting resin on the inner wall surface of a cylindrical mold that rotates at a speed that generates a centrifugal force smaller than twice the force of gravity; A step of pressing and molding with the weight of at least one rotating press roll; (B) a step of supplying a foamable resin and foam-molding; as necessary, the above (A) and (B)
Provided is a method for manufacturing a fiber-reinforced resin cylindrical molded article having a foamed resin layer, which is characterized in that the molding is performed through repeated steps. The cylindrical mold used in the present invention is preferably one that can be split into at least two parts along the rotation axis direction and can be closed on the outside with a tightening bolt.
Usually, the cross section is a circle, ellipse, polygon, or partially missing one of these. Materials for this mold include metal, wood, plastic, stone, etc., with metal being particularly preferred. The size of this mold is not particularly limited, but it is usually about 1 to 4 m in inner diameter and 1 to 10 m in length, considering the molding inside the mold and the transportation of the molded product. Of course, the diameter and length can also be outside the above range. In the present invention, a fiber-reinforced thermosetting resin, that is, a fiber-reinforced material and a liquid thermosetting resin supply section is placed inside the mold, and the supply section can freely move back and forth, or The part is fixed and the mold itself is designed to move back and forth. Further, the mold according to the present invention is rotated by a plurality of rollers driven by a motor. The rotational speed at this time is selected to be a speed that generates a centrifugal force smaller than twice the gravity, preferably 1.2 times the gravity or less, and optimally a speed that generates a centrifugal force smaller than the gravity. Generally, the centrifugal force on the wall of a rotating body is F=
It is determined by mγω ² . In this case, F is centrifugal force, m is unit mass, γ is radius of the rotating body, and ω is angular velocity. If a cylindrical mold with an inner diameter of 2 m is rotated at a speed of 60 revolutions per minute to produce an FRP cylindrical molded product, the centrifugal force acting on a 1 cm ³ unit of the molded material will be 7.24 g, assuming the specific gravity of the molding material is approximately 1.8.・cm/s ² , and the gravity is F=mα... (Note: α is acceleration)
It is calculated as 1.8g・cm/s ² , which is about four times the force of gravity. In this case, for the centrifugal force to be twice the gravity, the rotational speed is 42 revolutions/min and the circumferential speed is 266 m/min.
It takes about a minute. According to the experiments conducted by the present inventors,
In the general centrifugal molding method, in order to prevent the supplied molding material from falling from the mold, a centrifugal force of more than twice the force of gravity, preferably four times or more, is required. If the amount is less, it becomes difficult to press the molding material against the wall. From the above, the mold body of the present invention varies depending on the inner mold, so it is not necessarily accurate, but the speed is 1 to 30 revolutions/minute,
Preferably 1 to 18 revolutions/min, more preferably 1 to 18 revolutions/min.
Rotation speed of about 15 revolutions/minute or circumferential speed of 0.5~
Rotates at 300m/min. Examples of the fiber reinforcing material used in the fiber-reinforced thermosetting resin include known fiber reinforcing materials such as glass fiber, carbon fiber, and aramid fiber (manufactured by DuPont, Kevlar fiber), with glass fiber being particularly preferred.
Such a reinforcing material may be in the form of a pine, a roving, or a chop formed by cutting the roving into an appropriate length, and a combination thereof may also be used. In addition, the amount of such reinforcing material used is usually 10 to 80% by weight, preferably 15 to 60% by weight, in the molded product.
More preferably, the amount is 20 to 50% by weight. In addition, examples of the liquid thermosetting resin used in the fiber-reinforced thermosetting resin include known liquid thermosetting resins such as unsaturated polyester resin, epoxy resin, phenol resin, and vinyl ester resin, and in particular, unsaturated polyester resin. is preferred. When using this unsaturated polyester resin, a method of curing using a combination of peroxide or the like as a catalyst and a metal salt, amine, or the like as a curing accelerator is preferred. Such catalysts and curing accelerators may be supplied onto the fiber reinforcing material on the inner surface of the mold separately from the resin or mixed in advance. This liquid thermosetting resin has the ability to impregnate fiber reinforced materials,
Viscosity is important because of the sag phenomenon. In other words, if the resin viscosity is too low, the molded product tends to whiten or sag, while if it is too high, impregnating properties are poor, so even when the molding material is pressed with a roller, it does not stick to the mold surface. It will fall and will not be able to be molded. From this point of view, the viscosity of such resin is usually
The viscosity is appropriately selected from 0.5 to 20 poise/25°C (Bruck-Field viscosity), preferably 1.0 to 15 poise/25°C, and more preferably 2 to 10 poise. In the molding method of the present invention, the fiber-reinforced thermosetting resin is molded by pressing the surface of the uncured resin with the weight of a freely rotating press roll to impregnate the fiber-reinforced material with the liquid thermosetting resin. , followed by curing. This molding method, as shown in JP-A No. 54-111577, uses a chain wheel or the like to force the mold body and the pressure roll, which have significantly different diameters, to rotate at the same speed to perform impregnation and defoaming. The method is completely different. That is, in the present invention, the mechanism is such that the pressure roll freely rotates as shown in FIG. At this time, the pressure roll may be adjusted by at least one crank, a shaft that can move in an appropriate width, or a combination thereof so that it can freely move forward and backward with an appropriate width. desirable. When such a roll presses the molding material, the rotation of the pressure roll is not artificially manipulated, and is capable of responding to variations in rotational speed due to resistance of the molding material, etc., while being synchronized with the rotation of the mold. . When molding the fiber-reinforced thermosetting resin, the weight of the press roll is used to sufficiently impregnate the fiber-reinforced material with the liquid thermosetting resin. Of course, it is okay to apply some load as long as it does not interfere with the free rotation of the press roll, but if the load is too large or the roll itself is heavy, the rotation speed of the mold body will be slow and the roll will This is not preferable because it sinks into the molding material and the resin is squeezed out, resulting in a molded product with a low resin content. On the other hand, if the weight of the press roll is too small, resin impregnation will be insufficient, air bubbles will remain in the molding material, and the material will fall from the mold surface, making molding impossible. Therefore, the pressure roll used in the present invention usually has a length of 10 to 100 cm, preferably 30 to 100 cm.
70 cm, and its own weight is 20 to 600 g, preferably 50 to 400 g, more preferably 80 to 300 g, that is, a pressing force is applied to the surface of the molding material. In order to efficiently achieve resin impregnation and air bubble defoaming using such rolls, it is preferable to use three or more of the above rolls at appropriate intervals in the present invention. As for the shape of the press roll, its length is as described above, but it can be changed as appropriate depending on the length of the molded product, and its diameter is smaller than the inner diameter of the mold body, so that it can be freely moved within the mold body. Any size that can be rotated is sufficient, and a diameter of 5 to 40 cm is usually appropriate. In addition, it is better to have grooves on the outer circumferential surface of the roll that comes into contact with the molding material during pressing, and the shape of the grooves can be freely selected from linear, spiral, or grid pattern in the roll axis direction, and the depth can also be freely selected. You can choose. Furthermore, the pressure roll may have a mesh-like net coated on its outer peripheral surface. The material of the roll used in the present invention may be any material as long as it can generate the above-mentioned pressing force, and examples thereof include known materials such as iron, aluminum, stainless steel, copper, wood, and plastic, and combinations thereof. I can't help it. The inside of the roll may or may not be empty. In the method of the present invention, foam molding is performed by supplying a foamable resin before or after molding the fiber-reinforced thermosetting resin layer. As the foaming resin used in this case, any generally known resin can be freely selected as long as it is a resin that is supplied as a liquid resin and then reacts and foams. For example, there are hard urethane resins, urea resins, phenolic resins, etc. Even if the supplied material is in the form of powder or granules like thermoplastic resins, by installing a heat melting mechanism, even resins that become molten and foam can be molded. is possible. For example, generally known thermoplastic resins for foaming, such as acrylic resin, polyethylene resin, polystyrene resin, and copolymer foam products of the above-mentioned resins, can also be used. These foaming resins may be used alone, or may be used in combination with various inorganic fillers, microscopic hollow spheres, reinforcing fibers, etc. In addition, the expansion ratio of the foam to be used can be freely selected depending on the purpose of use, but generally it is 2.
~60 times is preferable. In addition, when the thickness of the foam layer is not uniform, it is preferable to cut it with a cutter or the like to make it uniform. The foamed resin supply method in the present invention is appropriately selected depending on the type of foamed resin. Regardless of which foaming resin is used, the resin is generally a two-component mixture type, so the raw material tank for supply is usually installed outside the cylindrical mold, and a transfer pump or the like is used. A method is adopted in which unfoamed resin is supplied from a gun body containing a mixing system, which is attached to the tip of a dye for fixing a supply device set inside a cylindrical body through a hose. In addition to the above-mentioned spray method, the method for supplying the foaming liquid resin may be a dropping method that simply utilizes gravity, a method in which a space is provided so as to form a foamed resin layer, and the resin is injected and foamed. The combination of the fiber-reinforced thermosetting resin layer and the foamed resin layer formed by the above-mentioned molding can be freely selected. For example, it is possible to have a fiber-reinforced thermosetting resin layer as an inner layer and a foamed resin layer as an outer layer, or vice versa, or it is also possible to have three or more layers laminated on top of those outer layers. . Preferably, it has a three-layer structure with a foam layer between fiber-reinforced thermosetting resin layers. still,
When the foamed resin layer is the outermost layer, it can be coated with metal, plastic, paper, etc. after the cylindrical molding is formed, or it can be pasted on the inner surface of the mold beforehand and coated at the same time as the molding. Also good. In the latter case, the other covering material has the advantage of acting as a release base between the mold and the foamed resin layer. Next, a molding example of the fiber-reinforced thermosetting resin layer in the present invention will be explained with reference to the drawings. As shown in FIG. 1, a molding body A is rotated by a roller 5 that transmits the rotation of a motor 4, and a reciprocating sliding body C having a press roll, a molding material supplying part, etc. therein is moved to a cantilever type dyeing body. A device is used that can move back and forth along the body B. Alternatively, as shown in FIG. 3, the molding material supply part and the press roll mounting part I are fixed without moving along the cantilever dyeing body B, and the molding die A is rotated and forming is performed at the same time. A device is used that can be moved back and forth by a mold movement motor 11 controlled by a self-propelled motor control panel 15 as the process progresses. In the mold body A, the reinforcing material entered from the fiber reinforcing material receiving port 7 is cut by the reinforcing material cutter 8 and dropped onto the inner surface of the mold, and then resin, catalyst, etc. are supplied from the liquid thermosetting resin supply device E. Supplied on the reinforcement. After that, the press roll F presses the molding material. At this time, the pressure roll F is designed to have some play due to the pressure roll bearing 30 and crank 29 as shown in FIG. The mold body A or the reciprocating sliding body C moves as molding progresses to form a molded product, and a cylindrical product is produced after the liquid thermosetting resin is cured. Unlike conventional methods, the fiber-reinforced resin cylindrical product with a foamed resin layer formed in this way is produced continuously, and since there is no seam in the foamed layer, it has excellent heat insulation performance and also has excellent adhesive performance. It has excellent strength because the fiber reinforcement is uniformly dispersed, and can be used as cylindrical containers such as tanks, purification layers, and silos. Example 1 A cylindrical body with an inner diameter of 2.8 m and a length of 6 m was used to
First, a fiber-reinforced thermosetting resin layer was molded using manufacturing equipment as shown in Figures 2, 4, and 5. Glass roving SP-3 (manufactured by Asahi Fiberglass Co., Ltd.) was cut into 50 mm length on the surface of an iron mold rotating at a speed of 6 revolutions/min (peripheral speed 53 m/min).
Kg/min, and then an unsaturated polyester resin liquid with a viscosity of 6 poise/25°C containing 0.4% by weight of 6% by weight cobalt naphthenate solution (manufactured by Dainippon Ink Chemical Co., Ltd.) as a curing accelerator ( Polylite FG-104, manufactured by Dainippon Ink Chemical Co., Ltd.) and 55% by weight MEKPO solution as a catalyst (manufactured by NOF Corporation)
An unsaturated polyester resin solution (same as above) with a viscosity of 5 poise and 25°C mixed with 1.5% by weight of supplied. Thereafter, it was pressed with a stainless steel press roll having a length of 50 cm, a diameter of 15 cm, and a weight of 11.5 kg and having grooves in the circumferential direction. At that time, the pressure roll is approximately
Three press rolls were used with a roll interval of 10 cm, and the pressing force due to the weight of each press roll was approximately 230 g/cm. Incidentally, the reciprocating sliding body to which the supply section for glass fibers, resin, etc. and the pressure roll were attached was moved at a speed of 30 cm/min along the mold rotation axis. The obtained cylindrical molded article having a fiber-reinforced thermosetting resin layer had a length of 6 m, a diameter of 2.8 m, and a wall thickness of 8 mm. After the resin layer is cured, while rotating the mold in the same manner as described above, Hyprox SP-290 (manufactured by Dainippon Ink Chemical Co., Ltd.) is added as a polyisocyanate component and Hyprox RR-986C (manufactured by Dainippon Ink Chemical Co., Ltd.) as a polyol component on the resin layer. (manufactured by Ink Kagaku Co., Ltd.) was mixed and sprayed using a spray foaming device Mini Probler (manufactured by Nihon Ransburg Co., Ltd.). The gun body of this device was attached downward to the reciprocating sliding body C shown in FIG. Both components were heated to 49° C. by a heater hose and sprayed at a pressure of 6 kg/cm ² by a compressor at 700/min. The thickness of the hard urethane foam layer obtained was approximately 40 mm, but the surface was uneven with a thickness of 3 to 8 mm, so the surface was cut using a carbide blade wheel cutter installed inside the dust collection cover. A hard urethane foam layer with a uniform thickness (30 mm) was formed by cutting 10 mm. still,
The finished density of this foamed layer was 0.067 Kg/cm ³ . Immediately after forming the foam layer, a fiber-reinforced thermosetting resin layer is formed on the foam layer in the same manner as described above,
A cylindrical molded product with a three-layer structure including a urethane foam layer between fiber-reinforced thermosetting resin layers was obtained. Example 2 Using a hollow cylindrical mold with a length of 6 m, an inner diameter of 2.8 m, and a string length of 1 m as shown in Fig. 6, Example 1 was prepared.
After forming a fiber-reinforced thermosetting resin layer in the same manner as above, a hard urethane foam layer was formed thereon to obtain a two-layered cylindrical molded product. This molded product had a fiber-reinforced thermosetting resin layer with a thickness of 8 mm and a urethane foam layer with a length of 30 mm. Application example (fabrication of septic tank) As shown in Figure 8, the cylindrical molded product formed in Example 1 was made with a diamond cutter to make three holes with a diameter of 60 cm, and after smoothing the holes with a file, it was hand-molded in advance. Manhole made of FRP with an outer diameter of 60 cm (Resin used: Polylite FH- containing 1% by weight of 55% by weight methyl ethyl ketone peroxide solution)
123 - Manufactured by Dainippon Ink &Chemicals; Glass chopped mat used: 450g/m ² , 8 ply) was applied to each opening with unsaturated polyester resin putty for reinforcement.
Bonded using 4 plies of 450 g/m ² glass chopped mat and liquid unsaturated polyester resin. In addition, pre-formed FRP mirrors were joined to the front and rear openings of the cylindrical molding in the same manner as the manhole described above. The FRP mirror used in this case was made using 8 plies of 450g/ ^m2 glass chopped mat, molded using the same resin used to mold the manholes mentioned above, and was 8mm thick with a curved surface. It is an arc with a radius of 4m. The physical properties of the obtained septic tank were investigated. (1) Mechanical strength of cylindrical molded product

[Table] Note that the test piece used was one cut out from a cylindrical molded product prepared separately in Example 1. (2) Measurement of strain in the septic tank We measured the strain when water was injected at each point from X ₁ to X ₉ (X ₇ to X ₉ is inside the septic tank) shown in Figures 7 and 8. . In addition, X ₁ is the center of the mirror, X ₂ is the center of the mirror, X ₂ is a point 1/3 horizontally away from X ₁ of the mirror, and X ₃ is 1/3 further away from X ₂ .
It is a remote location. X ₄ to _{X 9} are points 65 cm horizontally to the left from the center of the right end of the torso, and each point is 1/5 of the lower half of the circumference from there. Moreover, each strain value is expressed as a relative value of the strain value of a septic tank into which water has not been injected after fabrication.

【table】

[Table] Strain was measured using a static strain meter (Shinkoh PS10/AT).
type), Switchbox (PS-7502 manufactured by Shinkoh)
This was done using a strain gauge (PC-10-11 manufactured by Tosokki Co., Ltd.). (3) Measuring the deflection of the septic tank At point Y (1.6m away from the left end of the body) and point X (center of the mirror) shown in Figure ₇ , measure the amount of deflection (displacement) when the amount of water injected is increased. It was measured.
Figure 9 shows the data for water injection amount (water depth) of 0.5m, 1m, 1.5m, 2m, and 2.3m. Incidentally, the deflection was measured using a dial gauge (manufactured by Pico Stock Co., Ltd.).

[Brief explanation of drawings]

The drawings show an example of an apparatus used to carry out the method for manufacturing a molded article according to the present invention, and FIG. 2 is a side view of the device shown in FIG. 1, and FIG. 3 is a vertical cross-sectional front view of a molding device that can move along FIG. 4 is a front view of a portion where a pressure roll is attached, FIG. 5 is a partial side view of FIG. 4, and FIG. FIG. 2 is a sectional view of a mold for molding. Further, FIG. 7 is a side view of a septic tank prepared in an applied example, FIG. 8 is a plan view thereof, and FIG. 9 is a graph showing the deflection (displacement amount) when poured into the septic tank. A...Mold body, B...Cantilever beam body, C...Reciprocating sliding body, D...Fibre reinforcement supply device, E...Liquid thermosetting resin supply device, F...Press roll, G...Mold body Frame part, H... Molding material supply part and press roll mounting part, I... Rail, 1... Hinge part, 2... Tightening bolt, 3... Tightening bolt, 4... Motor, 5...
Roller, 6... Support, 7... Fiber reinforced material receiving port, 8... Reinforced material cutter, 9... Fiber reinforced material falling port, 10... Mold inner surface, 11... Mold rotation motor, 12
...Reducer for mold rotation, 13...Motor for mold movement, 1
4... Model movement reducer, 15... Self-propelled motor control panel, 16... Bearing, 17... Traverse worm gear, 18... Reinforcement cutter drive motor, 19... Resin supply nozzle, 20... Air cylinder, 21... Arm, 22...Reinforcing material cutting resin presser roller, 23...Fiber reinforced material, 24...Iron presser roller for preventing reinforcement from coming off, 25...Air cylinder for reinforcing material cutting, 26...Rotary pulley for reinforcing material cutting, 27...Motor, 28...Resin supply nozzle,
29... Crank, 30... Press roll bearing, 31...
Press roll shaft rod, 32...Cut-circular internal shape material, 33...
Manhole, 34...Mirror part, _X1 ...Distortion measurement and deflection measurement location, _X1 to _X9 ...Distortion measurement location, Y...Deflection measurement location.

Claims (1)

[Claims] 1. On the inner wall surface of a cylindrical mold that rotates at a speed that generates a centrifugal force smaller than twice the force of gravity, (A) a fiber-reinforced thermosetting resin is supplied, and at least one piece of fiber-reinforced thermosetting resin is supplied, and at least one It has a foamed resin layer characterized by a step of pressing and molding with the weight of a pressure roll, (B) a step of supplying a foamable resin and foaming, and repeating the above steps (A) and (B) as necessary. A method for manufacturing fiber-reinforced resin cylindrical molded products.