JP2530698B2 - Blow molding of curable resin and blow molding method thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to a blow molding product of a curable resin and a blow molding method thereof.

(Prior Art) Generally, a blow molding method is known as a method for producing a complicated hollow molded product which is endless in the circumferential direction and has an undercut portion and the like. This blow molding method
Conventionally, it is applied when molding a thermoplastic resin,
It is not applied when molding with thermosetting resin.

Then, conventionally, as a method of molding a molded article having the above-mentioned complicated structure with a fiber-reinforced thermosetting resin, a rotational molding method utilizing centrifugal force during rotation has been known. In addition, as another method, a half-divided product is separately formed by a handle method or a vacuum forming method, and these half-divided products are bonded and finished in a later step, or the half-divided product is formed during the molding of these half-divided products. A method is known in which the joint end of the split is left unimpregnated or uncured, and the joint end is impregnated or cured in a subsequent step to finish.

(Problems to be Solved by the Invention) However, the conventional molding methods described above have the following problems, respectively.

First of all, there are a premix method and a preform method in the rotational molding method. However, since these are impregnated with a resin by centrifugal force and then cured by heating, it takes time to mold, and both require facility cost. Since it is bulky, the cost is high. Also,
The molded product is not sufficiently strong and the fibers are exposed and rough on the inner surface of the molded product, so that the molded product is used at most as a mannequin.

Further, in the method of joining the half-divided products, it takes time with manpower and work efficiency is poor, and since the reinforcing fibers are discontinuous in the joining portion, the strength of this joining portion is not sufficient and the internal pressure,
There was a problem that it was weak against external pressure and weeping stress.

(Means for Solving the Problems) The blow-molded product of the curable resin of the present invention is formed by forming a fiber-reinforced uncured or semi-cured curable resin into a bottomed or bottomless tubular shape and The inner surface and the outer surface of the functional resin are respectively covered with a stretchable tubular film to produce a parison, and the parison is blow-molded. Further, the filament winding layer or the tape winding layer is integrally coated on the outer peripheral surface of the molded product thus molded.

Further, the blow molding method of the curable resin of the present invention, fiber-reinforced uncured or semi-cured curable resin is formed into a bottomed or bottomless tubular shape, and the inner surface and outer surface of the curable resin are formed. After making a parison by covering each with a stretchable tubular film, mounting this parison in the mold, making the pressure inside the parison higher than the outside and expanding and deforming the parison along the inner wall surface of the mold It is cured and cured, and then released from the mold. The curable resin is a light or ultraviolet curable resin. Further, the film has heat shrinkability.

(Function) A fiber-reinforced uncured or semi-cured curable resin is formed into a bottomed or bottomless tubular shape, and the inner and outer surfaces of the curable resin are respectively covered with a stretchable tubular film. After making a parison and mounting the parison in the mold, the pressure inside the parison is made higher than that of the outside to cause the parison to expand and deform along the inner wall surface of the mold and harden. By molding, the curable resin can be blow-molded, and a hollow molded article having a complicated structure can be molded with the curable resin.

(Example) Hereinafter, the Example of this invention is described with reference to drawings.

The blow molding of the curable resin according to the present invention is obtained by molding a prepreg-shaped parison by blow molding.

FIG. 1 shows the configuration of a bottomless parison used in the blow molding method of the curable resin of the present invention.

In this bottomless parison 1, a curable resin laminate 2 formed by laminating uncured or semi-cured (prepreg) curable resin impregnated with reinforcing fibers is formed in a bottomless cylindrical shape. The inner surface and the outer surface of the curable resin laminate 2 are coated with tubular films 3 and 4, respectively.

As described above, the curable resin laminate 2 is obtained by impregnating the reinforcing fiber with the curable resin, and is essentially fluid. Therefore, it does not have the ability to receive and deform air pressure by itself, and therefore it is necessary to cover with the films 3 and 4. The curable resin laminate 2 is made by a hand-up method, a spray-up method, a flat plate laminating method, or the like in which a properly assembled chopped strand mat (reinforcing fiber) is impregnated with the curable resin. In addition, a sheet compound containing chopped strands or a mixture of chopped strands and a curable resin may be used. In this case, it is necessary to mold the curable resin laminate 2 so that the reinforcing fibers can freely move in the three-dimensional direction during blow molding. Therefore, a chopped strand mat impregnated with a curable resin is usually suitable. Further, in order to prevent a fault from being formed in the structure of the fiber which is the reinforcing material, it is necessary to appropriately devise the stacking when using the mat. Further, during the production of the curable resin laminate 2, the defoaming is mostly performed when the curable resin thermally shrinks, but the remaining bubbles may be defoamed by a conventional method such as a defoaming roll. In addition, by passing a ring made of rubber or the like having an appropriate diameter on the peripheral surface of the curable resin laminate 2,
The surface of the curable resin laminate 2 may be degassed in a squeezed shape. Further, the surface of the curable resin laminate 2 may be defoamed by applying high pressure air or the like.

The films 3 and 4 are made of a resin having properties such as high elasticity, not being immersed in a curable resin, having no air permeability, and being easily peeled off after curing.
Polyethylene, polypropylene, polyvinyl alcohol, etc. are used. Further, these films 3 and 4 are displaced from the curable resin laminate 2 during expansion due to blowing pressure (including the case of sucking and expanding from the outside). It is formed into a tubular shape with no end in the circumferential direction so that a fault cannot be formed.
Furthermore, these films 3 and 4 are configured to be contractible in the circumferential direction so that the curable resin laminate 2 can be covered with the surfaces taut. Therefore, these films 3,4
Is preferably a heat-shrinkable film that has been stretched in the circumferential direction in advance and has the ability to be shrunk in the circumferential direction by slight heating, and an inflation-molded film of the above resin is suitable for this.

In this way, by covering the inner and outer surfaces of the curable resin laminate 2 with the stretchable films 3 and 4, blow molding, which will be described later, becomes possible. Here, normally, the parison is preheated before molding in order to increase the stretchability of the film (thermoplastic), and the curable resin laminate 2 is heated by this heating.
Since there is a possibility that the curing reaction of (1) is started and promoted, it is important to cut off the chain of this heating and curing reaction as much as possible. Therefore, the curable resin used in the present invention is preferably a photocurable resin or an ultraviolet curable resin.

The photocurable resin or the ultraviolet curable resin does not start the reaction unless it receives light or ultraviolet rays, and is therefore stable for storage in a dark place and heating during molding. Further, the photo-curable resin or the ultraviolet-curable resin has a characteristic that the curing is completed in a short time once the reaction is started.

As the photocurable resin or the ultraviolet curable resin, known, for example, radical polymerization type unsaturated polyester resin, saturated or unsaturated acrylic resin, modified epoxy resin, modified urethane resin and the like or a mixture thereof, and cationic polymerization Type epoxy resin. Furthermore, it is possible to effectively use a mixture of the above resin and an unsaturated monomer copolymerizable therewith.

As the photosensitizer, known benzoin derivatives, benzophenones, acetophenones, acyloximes, benzyl ketals, diazonium salts, amines and the like are used, and they can be used in combination with a peroxide.
Further, if necessary, an isocyanate compound, a metal chelate or the like known as a reactive thickener is used. It is also possible to maintain the semi-cured state of this curable resin by irradiating it while controlling light or ultraviolet rays, and to increase the viscosity by this action.

Then, in the bottomless parison 1 configured as described above, for example, as shown in FIG. 4, the inner film 3 is fitted on the peripheral side surface of the cylindrical core 6 and the curable resin laminate is attached to the inner film 3. It can be manufactured by winding 2 and covering it with the outer film 4, and then pulling out the core 6. At this time, the inner and outer films 3 and 4 must be closely attached to the curable resin laminate 2 so that wrinkles and bubbles are not generated. Therefore, when the films 3 and 4 are covered, they are slightly heated by the heater 7 to shrink the films 3 and 4 in the circumferential direction, and by passing through the defoaming ring 8, the defoaming and the wall thickness are adjusted.

Further, in order to continuously manufacture such a bottomless parison 1, a tube having a heat-shrinkable film in the width direction is wrapped by heat fusion or the like immediately before coating on the curable resin laminate 2 to form a tube. You may take the method of converting.

Further, the diameter of the core 6 is gradually tapered so that the peripheral side surface of the core 6 is tapered in the axial direction, or a large number of holes are bored in the peripheral side surface of the core 6 to extend outward from this hole. By blowing pressurized air, the inner film 3 and the core 6
You may make it easy to release from.

By constructing the parison as described above, the following requirements can be met, and it becomes possible to manufacture a prepregnate parison, which has been conventionally regarded as difficult.

The curable resin laminate can be maintained in an uncured or semi-cured state.

The film adheres to the curable resin laminate without leaving wrinkles or bubbles.

The fiber-reinforced curable resin laminate closely follows the inner wall surface of the mold during blow molding.

In addition, there is usually some time elapsed from the production of the parison until the blow molding, but this elapsed time can be freely selected, that is, the parison is maintained in the production state as described above. If it is possible, the degree of freedom in the steps of blow molding can be increased.

Next, a case of blow molding using the bottomless parison 1 configured as described above will be described.

Here, a case where a cheese pipe joint is molded by blow molding will be described as an example.

In blow molding, as shown in FIG. 3, the bottomless parison 1 produced as described above is preheated to some extent from the inner and outer surfaces with a heater or the like (not shown), and then the bottomless parison 1 is placed between the molds 10. Then, the mold 10 is closed and mounted. After that, air having an appropriate pressure is blown into the bottomless parison 1 from the blow-in port 11 to expand and deform the bottomless parison 1 so that the bottomless parison 1 is along the inner wall of the mold 10 and the lamp 12 emits light or ultraviolet rays. Is irradiated to cure the bottomless parison 1 in a state of being deformed into a cavity shape. After the curing is completed, the mold 10 is opened and the mold is released, and the films 3 and 4 are peeled off to form the cheese pipe joint.

In FIG. 3, reference numerals 13 and 14 are cores provided at both ends of the bottomless parison 1, and reference numeral 15 is a vent hole formed in the mold 10.

Most of the deformation resistance at the time of blow molding is due to the two inner and outer films 3 and 4, so that it can be deformed more easily than blow molding of ordinary thermoplastic resin. Therefore, as described above, the parison is not limited to be expanded and deformed by blowing air into the parison, but the parison is expanded and deformed by degassing the inside of the mold (vacuum forming) to suck the outside of the parison. The parison can be expanded and deformed by using them together. Here, since the photocurable resin or the ultraviolet curable resin completes the curing in a short time once the reaction is started, the irradiation time of the lamp is usually about 1 minute, which shortens the molding time. Can be planned. Irradiation of the lamp to the parison may be performed from the outside of the parison, but it is usually preferable to perform irradiation from the inside of the parison as described above.

As the lamp 12, a known one such as a high pressure mercury lamp or a metal halide lamp is used.

In addition, after demolding, the molded cheese pipe joint may be subjected to post-irradiation for further reliable curing.

As described above, a hollow molded product (cheese pipe joint in this example) can be molded by blow molding with the fiber-reinforced curable resin. Since this molded product is molded with the curable resin covered with the films 3 and 4, the fibers are not exposed on the inner and outer surfaces of the molded product,
These surfaces can be beautifully finished.

FIG. 2 is a sectional view showing the structure of a bottomed parison. The bottomed parison 20 is formed in a bottomed cylindrical shape so as to close one end of the bottomless parison, and the configuration except this shape is the same as the bottomless parison. Therefore, the same components are denoted by the same reference numerals and the description thereof is omitted here. The second
Reference numeral 21 in the figure is a core, and a rod is provided in the core 21.
22 is inserted.

By using the bottomed parison 20 to perform blow molding in the same manner as described above, a container or the like can be molded.

In addition, a reinforced plastic layer (FRP layer) such as a filament winding layer or a tape winding layer may be integrally formed on the outer peripheral surface of the molded product thus molded. The filament winding layer is
It is formed by the filament winding method in which a roving-like reinforcing material impregnated with a thermosetting resin is wound around the outer peripheral surface of the molded product, and the tape winding layer is a tape-like reinforcement impregnated with a thermosetting resin. It is formed by a tape winding method in which the material is wound around the outer peripheral surface of the molded product. Further, both of them may be used together to form a reinforced plastic layer on the outer peripheral surface of the molded product.

(Effects of the Invention) As described above, according to the present invention, blow molding with a fiber-reinforced curable resin is possible. As a result, even a complicated hollow material which is endless in the circumferential direction and has an undercut portion and the like can be easily and inexpensively molded by the fiber-reinforced curable resin.

Further, by molding as in the present invention, it is possible to cleanly finish the inner side surface and the outer side surface of the hollow molded article, and therefore this hollow molded article can be used for many things such as pipes. it can.

Furthermore, since this molded product is integrally formed by blow molding a fiber-reinforced curable resin,
Also, it has the characteristic of being strong against weeping stress.

Further, since the photo-curable resin and the ultraviolet-curable resin are used, the pre-heating performed when the parison is mounted on the mold does not react with the resin, and the blow molding can be performed in an optimum state.

By integrally covering the outer peripheral surface of the molded product with the filament winding layer or the tape winding layer, the strength and heat resistance of the molded product can be further improved.

[Brief description of drawings]

1 is a sectional view showing the structure of a bottomless parison, FIG. 2 is a sectional view showing the structure of a bottomed parison, FIG. 3 is a sectional view showing blow molding by a bottomless parison, and FIG. 4 is a bottomless parison. FIG. 6 is a perspective view showing a manufacturing process of. 1 ... Bottomless parison 2 ... Curable resin composition object 3, 4 ... Film 10 ... Mold 12 ... Lamp

Claims (5)

(57) [Claims] 1. A fiber-reinforced uncured or semi-cured curable resin is formed into a bottomed or bottomless tubular shape, and the inner and outer surfaces of the curable resin are each formed into a stretchable tubular film. A blow-molded product of a curable resin obtained by forming a parison by coating and blow-molding the parison. 2. A fiber-reinforced uncured or semi-cured curable resin is formed into a bottomed or bottomless tubular shape, and the inner and outer surfaces of the curable resin are each formed into a stretchable tubular film. After making a parison by coating and mounting this parison in the mold, the pressure inside the parison is made higher than the outside to cause the parison to expand and deform along the inner wall surface of the mold and harden. A method of blow molding a curable resin, characterized by releasing from a mold. 3. The blow molding method for a curable resin according to claim 2, wherein the curable resin is a light or ultraviolet curable resin. 4. The film is heat-shrinkable.
Blow molding method of curable resin described. 5. The molded product according to claim 1, wherein the outer peripheral surface of the molded product is integrally coated with a filament winding layer or a tape winding layer.