JPH0351581B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention is a fiber-reinforced thermosetting resin (hereinafter referred to as FRP)
The present invention relates to a method for manufacturing a resin cylindrical molded product with excellent workability, in which a plastic foam layer is used as a core material between an upper layer and an FRP lower layer, and the upper and lower layers are connected by ribs. (Conventional technology) Conventionally, FRP uses a plastic foam layer as a core material.
Large-diameter cylindrical molded products with Sanderch structure have been put to practical use in water tanks, silos, insulated pipes, heat-retaining containers, etc. for the purpose of improving heat-retaining performance and rigidity. The molding method used is to first mold an FRP cylindrical product using various molding methods such as hand lay-up method, spray-up method, filament winding method, centrifugal molding method, and rotational molding method. Thereafter, various plastic foams are attached or molded to the molded body, and an FRP layer is further formed to obtain a cylindrical molded product having an FRP sandwich structure. In the thus obtained large-diameter cylindrical molded product having a sandwich structure, the FRP upper layer and the FRP lower layer are supported by the strength of the plastic foam itself or by the adhesive strength between the FRP upper and lower layers and the plastic foam. Commonly used plastic foams are
Since the strength of the FRP upper layer is significantly lower than that of the lower layer, the plastic foam will break due to shear stress and buckling stress when a large load is applied. Also, if a local load is applied, the material will break due to concentrated stress. Furthermore, if repeated and extreme stress is applied, the plastic foam becomes powdery and does not retain its shape. In order to compensate for these drawbacks, a method has been adopted in which a high-strength core material is bonded between the upper and lower FRP layers using a high-strength adhesive. However, in general, high-strength core materials, such as high density and thermal conductivity, have drawbacks in terms of weight reduction and heat retention. In addition, high-strength core material is generally sold in the form of a fixed-length plate, and when forming a cylindrical object, it is necessary to bend and attach the fixed-length high-strength core material to match the radius of curvature of the upper and lower FRP layers. There is. In this case, since the high-strength core material has high rigidity, the rebound phenomenon is large, making it difficult to adhere with perfectly matching curvatures. Therefore, when attaching a high-strength core material, it is necessary to cut the high-strength core material into strips and attach them. The strength in the direction does not necessarily improve. In addition, such work
It's complicated. The present inventors have arrived at the present invention as a result of intensive research into a method for manufacturing a large-diameter cylindrical molded product that uses plastic foam and has high strength, excellent heat retention, and is lightweight. That is, the present invention provides a cylindrical molded article having a rib that connects the upper layer and the lower layer and a plastic foam layer between a fiber-reinforced thermosetting resin layer and a lower fiber-reinforced thermosetting resin layer. In the method for manufacturing using a cylindrical mold, (A) molding a fiber-reinforced thermosetting resin lower layer on the inner or outer surface of a cylindrical mold, (B) molding a plastic foam, and (C) molding a plastic foam. The process of cutting continuous grooves in the foam, (D) the process of molding continuous ribs, and (E) the process of molding the upper layer of fiber-reinforced thermosetting resin are () (A), (B), and (C). ), (D), (E), () (A), (B), (
C),
Perform the steps in the order selected from (D), (B), and (E);
The present invention also provides a method for manufacturing a resin cylindrical molded article, characterized in that steps (A), (C), (D), and (E) are carried out using a rotating large-diameter cylindrical mold. In the present invention, especially low-density plastic foam is used to improve heat retention and weight reduction, while also eliminating the lack of strength, which is a drawback of low-density plastic foam.
This is achieved by connecting the FRP upper layer and the FRP lower layer with ribs, and if necessary, the ribs can be installed at positions where concentrated loads are applied to prevent destruction due to concentrated loads.The manufacturing method has excellent workability due to the continuous process of the structure. I will provide a. The cylindrical molded product referred to in the present invention includes a cross section of a circle, an ellipse, a polygon, and other shapes, and a parallel or tapered tubular shape. Large diameter is 1m in diameter.
That's all. The resin cylindrical molded product obtained by the manufacturing method of the present invention includes, for example, (A) a step of molding an FRP lower layer, (B) a step of molding a plastic foam, and (C) a step of cutting grooves in the plastic foam. , (D) the process of molding the ribs, and (E) the process of molding the FRP upper layer. In other words, depending on the shape and purpose of the rib, for example, there are ribs that are molded in the order of (A), (B), (C), (D), and (E); Examples include those molded in the order of E) and those molded in the order of (A), (B), (C), (D), (B), and (E). The molding method in the above steps (A) and (E) may be various molding methods such as hand lay-up method, spray-up method, filament winding method, centrifugal molding method, rotational molding method, etc. ) and (E) may be formed using different molding methods. The molding method in step (B) may be by pasting a fixed length plate of various low-density plastic foams, or by spray foam molding. Process (C) is performed using a plastic foam cutting machine.
This is done by cutting the plastic foam molded on the FRP lower layer into grooves in the circumferential direction, spiral direction, or base grain direction as necessary. The cross-sectional shape of the groove can be selected from any shape such as a square, a U-shape, a V-shape, or a semicircle. The molding methods in step (D) are (A), (B), (C), (D), and (E).
Among those molded in the following order, when molded on the inner surface of a cylindrical mold, it is molded by hand lay-up method, spray-up method, centrifugal molding method, rotational molding method, etc.
In addition, when molding is performed on the outer surface of a cylindrical mold, a hand lay-up method, a spray-up method, a filament winding method, etc. are used. (A), (D), (B), (E)
Among those molded in this order, when molding is performed on the inner surface of a cylindrical mold, it is molded by hand lay-up method, spray-up method, rotary molding method, etc., and when molded on the outside surface of a cylindrical mold, it is molded by hand lay-up method, spray-up method, rotary molding method, etc. It is molded by the lay-up method, spray-up method, filament winding method, etc. Among those molded in the order of (A), (B), (C), (D), (B), and (E), when molding on the inner surface of a cylindrical mold, hand lay-up method, spray-up method,
It is molded by a rotational molding method or the like, and in the case of molding on the outer surface of a cylindrical mold, it is molded by a hand lay-up method, a spray-up method, or the like. Examples of the fiber reinforcing material used in the upper and lower layers of 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. The amount of reinforcing material used is usually 10 to 80% by weight, preferably 15% by weight of the molded product.
A suitable amount is ~60% by weight, more preferably 20-50% by weight. The thermosetting resin used in the upper and lower fiber reinforced thermosetting resin layers includes known liquid thermosetting resins such as unsaturated polyester resins, epoxy resins, phenolic resins, and vinyl ester resins. Saturated polyester resins are preferred. When using this unsaturated polyester resin, it is preferable to use a method of curing using a combination of a peroxide or the like as a catalyst and a metal salt, an amine, or the like as a curing accelerator. Incidentally, such unsaturated polyester resin may be cured by other curing means such as ultraviolet curing. The plastic foam used in the present invention is preferably one with a low density, and includes generally known plastic foams such as urethane resin, acrylic resin, polyvinyl chloride resin, urea resin, phenolic resin, polyethylene resin, polystyrene resin, and copolymers thereof. Low density plastic foams may be mentioned. Further, the plastic foam may be a fixed length plate, or may be a spray foam or an injection foam molded material. The density of such plastic foam is 0.01-0.2 g/
cm ³ is preferable, more preferably 0.01 to 0.1 g/cm ³
It is. The ribs in the present invention may have a structure that connects the FRP upper layer and the FRP lower layer, and the ribs may be in any of the circumferential direction, base grain direction, and spiral direction. Dimensions are height 5~
The thickness is 100 mm, preferably 10-80 mm, and 0.5-50 mm, preferably 0.5-30 mm. Note that the spacing between the ribs is appropriately selected depending on the dimensions of the ribs, the direction of the ribs, the required strength, etc. The material for the ribs is preferably FRP due to the molding process and structure, but it is a material that can be bonded to the upper FRP layer and the lower FRP layer, and whose strength is at least twice, preferably at least 3 times, the strength of the core material used. Any material may be used, and the material may be appropriately selected from generally known materials. Furthermore, the ribs may be formed before or after the plastic foam is pasted or formed.
Alternatively, a preformed material joined together may be used. As shown in Table 1, the cylindrical molded product formed in this way is lightweight, has high heat retention, and has high strength physical properties, compared to cylindrical molded products made using conventional low-density plastic foam. The cylinder deflection is 1/4 to 1/2.
The amount of deformation is 2 to 6 times higher in local compression. In addition, it has the same or half the heat retention ability, and compared to a cylindrical molded product using a high-strength core material with the same strength, it has three times the heat retention ability and weighs 1/1.8 becomes. Therefore, the resin cylindrical molded product obtained by the manufacturing method of the present invention has excellent properties such as strength, heat retention, rigidity, and weight reduction, so it can be used for heat retention tanks, water tanks, silos, heat retention pipes, scrubbers, pig pens, etc. It can be used widely. Next, the present invention will be described in detail with reference to Examples. Example 1 A cylindrical molded article having a structure as shown in FIG. 1-b and having ribs in the spiral direction and having a diameter of 2 m and a length of 3 m was obtained. A cylindrical mold is rotated at a circumferential speed of 22.5 m/min, and an unsaturated polyester resin (Polylite FG-104, manufactured by Dainippon Ink Chemical) and 6% cobalt naphthenate as an accelerator are applied to the inner wall of the mold using a liquid thermosetting resin supply device. (Dainippon Ink Chemical) 0.4 parts by weight and as a catalyst
1.0 part by weight of 55% methyl ethyl ketone peroxide (manufactured by NOF) was mixed and supplied at 10 kg/min.
Next, glass fiber (Glass Roving SP-3, manufactured by Asahi Fiber) was cut into chopped strands with a length of 50 mm using a fiber reinforcing agent supply device.
Kg/min. Further, they were pressed with three freely rotating steel pressing rolls having unevenness. This pressure roll had a diameter of 15 cm, a length of 60 cm, and a weight of 10 kg, and the interval between the three rolls was 10 cm. Spray foaming was performed on the FRP lower layer with a thickness of 3 mm thus obtained using a urethane resin spray foaming device Mini Probler (manufactured by Ransburg Japan). The resin used is Hyprox RP-986C (manufactured by Dainippon Ink Chemical) as a polyol component.
Hyprox as a polyisocyanate component
SP-290 (manufactured by Dainippon Ink Chemical) was used. The discharge pressure at this time was 6 kg/cm ² . The foam layer thus obtained had a thickness of about 40 mm, but since the surface was uneven, it was cut to a thickness of 30 mm using a foam cutting machine. Note that the density of the foam was 0.05 g/cm ³ . After this, the foam cutting machine cut the material into 30mm deep and 40mm wide.
mm rectangular cross-sectional shape with a groove distance of 500 mm in the spiral direction
Grooves were cut in mm. The above-mentioned unsaturated polyester resin mixture and glass fibers (Chopmats CM-455,
manufactured by Asahi Fiber) using the hand lay-up method.
Ribs were molded to connect the upper and lower FRP layers. Thereafter, an FRP upper layer was molded to a thickness of 3 mm using the same molding method as for the FRP lower layer described above. The cylindrical molded product obtained in this way has a diameter of 2 m and a length of 3 m, the FRP lower layer has a thickness of 3 mm, the urethane foam layer has a thickness of 30 mm, the FRP upper layer has a thickness of 3 mm, and the FRP lower layer and FRP FRP ribs with a height of 30 mm and a width of 40 mm connected to the upper layer are spirally stretched 500 mm.
It is something to have at intervals. Example 2 A cylindrical molded article with a diameter of 2 m and a length of 3 m having ribs in the helical direction of a structural example as shown in FIG. 2-a was obtained. Using the same unsaturated polyester resin mixture and chop mat as in Example 1, a 3 mm thick FRP lower layer was molded on the outer surface of the cylindrical mold by the hand lay-up method, and on top of this, a 30 mm thick layer was formed in the same manner as in Example 1. A polyurethane foam layer was obtained. Also, in the same way, 500 mm in the spiral direction in a rectangular shape with a height of 30 mm and a width of 10 mm.
Grooves were cut at intervals of mm, and the unsaturated polyester resin mixture and the glass roving used in Example 1 were cut.
Ribs were formed using SP-3 using the filament winding method. Furthermore, an FRP upper layer with a thickness of 3 mm was molded on top of this using the same molding method as the FRP lower layer. The thus obtained cylindrical molded product has a diameter of 2 m and a length of 3 m,
FRP bottom layer thickness 3mm, urethane foam layer thickness 30mm
mm, the thickness of the FRP upper layer is 3 mm, and the FRP lower layer and FRP upper layer are connected with a height of 30 mm and a width of 10 mm.
It has ribs spaced at 500mm intervals in the spiral direction. Example 3 A cylindrical molded article with a diameter of 2 m and a length of 3 m having ribs of the structural example as shown in FIG. 3-b was obtained. A 3 mm thick FRP lower layer was formed in the same manner as in Example 1, and a 3 mm thick semicircular groove as shown in 3-b in FIG. 3 was cut. A 3 mm thick FRP rib 3 connecting the upper and lower layers was molded into this groove. Furthermore, urethane resin was spray foamed into this FRP semicircular groove in the same manner as in Example 1. The urethane foam was uneven, so the unevenness was cut away. Thereafter, an FRP upper layer was formed in the same manner as the FRP lower layer. Furthermore, the density of the obtained foam is 0.05
g/ ^cm3 . The thus obtained cylindrical molded product had a diameter of 2 m, a length of 3 m, an FRP lower layer thickness of 3 mm, a urethane foam layer thickness of 30 mm, and an FRP upper layer thickness of 3 mm.
It also has a rib with a semicircular cross section and a thickness of 3 mm. Example 4 A cylindrical molded product having a circular cross section with a diameter of 2 m and a length of 3 m and having ribs in the circumferential direction was obtained. Using the same unsaturated polyester resin mixture and glass fiber as in Example 2, an FRP lower layer with a thickness of 3 mm was molded into a cylindrical mold with an occluded cross section by the hand lay-up method. A 30 mm thick Piocelan board (manufactured by Sekisui Plastics Co., Ltd.) was pasted on top of this, and the FRP and FRP upper layer were formed in the same manner as in Example 2. The thus obtained occluded cylindrical molded product has a diameter of 2 m, an occluded portion of 1 m, and a length of 3 mm.The thickness of the FRP lower layer is 3 mm, and the thickness of the PIOCELAN boat foam layer is 30 mm.
mm, the thickness of the FRP upper layer is 3 mm, and the FRP lower layer is
It has FRP ribs with a height of 30 mm and a width of 10 mm connected to the FRP upper layer at intervals of 500 mm in the circumferential direction. Comparative Example 1 For comparison, an FRP sandwich cylindrical molded product having a conventional structure was molded under the same conditions as in Example 1 except that FRP ribs were not installed.

【table】

【table】 [Brief explanation of drawings]

1 and 2 are partial sectional views perpendicular to the axis of the resin cylindrical molded product of the present invention. 1...FRP lower layer, 2...Plastic foam,
3...Rib, 4...FRP upper layer.

Claims (1)

[Scope of Claims] 1. A resin cylindrical molded article having a fiber-reinforced thermosetting resin upper layer and a fiber-reinforced thermosetting resin lower layer, a rib connecting the upper layer and the lower layer, and a plastic foam layer. In the method of manufacturing using a cylindrical mold, (A) a fiber-reinforced thermosetting resin lower layer is molded on the inner or outer surface of a large-diameter cylindrical mold, and (B) a plastic foam is molded. (C) Cutting continuous grooves into the plastic foam; (D) Forming continuous ribs; (E) Forming the upper layer of fiber-reinforced thermosetting resin; ()(A) ), (B), (C), (D), (E), () (A), (B), (
C),
Perform the steps in the order selected from (D), (B), and (F);
and a method for producing a resin cylindrical molded article, characterized in that steps (A), (C), (D), and (E) are performed in a rotating large-diameter cylindrical mold.