JPH0688283B2 - Manufacturing method of synthetic resin pipe containing long glass fiber - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a synthetic resin pipe containing long glass fibers by using a press molding machine.

2. Description of the Related Art Conventionally, glass fiber-containing synthetic resin pipes such as FRP pipes are wrapped by a lap molding method in which a glass fiber mat is wrapped around a core material and impregnated with a polyester resin or the like, or cured.
Or impregnating glass roving with polyester resin,
It is manufactured by a filament-winning method in which this is wound around a core material and cured, or by a rotational molding method in which glass fibers and polyester resin or the like are charged into a rotary drum and molded into a tubular shape by centrifugal force.

Problems to be Solved by the Invention However, the lap molding method has a problem that the winding work of the glass fiber and the impregnation work of the polyester resin are troublesome and time-consuming, and the manufacturing efficiency is poor. On the other hand, in the Frament Winning method and the rotation forming method, there are problems that the apparatus used is large and the length of the obtained pipe is restricted.

The present invention has been made in view of these problems, and its object is to efficiently produce a synthetic resin pipe containing long glass fibers, which has a constant thickness and shows little partial variation in the long glass fiber content. The object is to provide a method capable of continuously producing well.

Means for Solving the Problems In order to achieve the above object, the production method of the present invention is to heat a synthetic resin plate having a low softening melt viscosity containing a long glass fiber layer, and press the inner mold of the press molding machine and the inner mold. A plurality of the above-mentioned heated synthetic resin plates are introduced between the split outer mold that surrounds the mold from both sides, and these synthetic resin plates are pressed by the inner mold and the split outer mold to form a tubular shape. It is characterized by being integrally molded.

Effect of the Invention According to the production method of the present invention, since the synthetic resin plate used has a low softening melt viscosity, the synthetic resin plate in which the resin is melted by heating is divided from the inner mold of the press molding machine. When multiple sheets are introduced between the outer molds and pinched, the molten resin of each synthetic resin plate easily flows under the pressure, and the gaps between the inner mold and the split outer mold are filled and joined together. It is integrally molded in a tubular shape, and at the same time, the long glass fibers in each synthetic resin plate also move and diffuse along with the flow of the resin, and are substantially uniformly contained in the synthetic resin molded in a tubular shape.

EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples.

FIG. 1 is an explanatory view of one embodiment of the manufacturing method of the present invention,
Here, p is a synthetic resin plate, A is a synthetic resin pipe containing long glass fibers, 1 is a heating device, 2 is a press molding machine, and 3 is a take-up roll.

The synthetic resin plate p used in the present invention is a synthetic resin plate containing a long glass fiber layer g and having a low softening melt viscosity. Specifically, polypropylene, polycarbonate, polyethylene, polyethylene terephthalate having a softening melt viscosity of 100,000 poise or less. , A thermoplastic synthetic resin layer r such as polybutylene terephthalate, polystyrene, nylon, acrylic, polyphenylene sulphand, or alloys thereof, and a long glass fiber layer g having an average fiber length of at least 10 mm or more are alternately laminated in three or more layers. Among them, a mat in which continuous spiral long glass fibers are stacked (for example, “Glaslon Continuous Strand Mat” manufactured by Asahi Fiber Glass Co., Ltd.) is alternately used with the resin layer r. A synthetic resin plate p having a stack of layers is particularly preferably used.

Further, as shown in FIGS. 1 and 2, the press molding machine 2 includes an inner mold 21 and upper and lower split outer molds 22, 22 'surrounding the inner mold 21.
The upper split outer die 22 (hereinafter referred to as the upper die) is configured to move up and down by hydraulic pressure, and the lower outer split die 22 '(hereinafter, the lower die). It is fixed). A pair of left and right hooks 23, 23 extending downward is provided on the front surface of the upper mold 22, and a pair of left and right hooks 23 ', 23' extending upward is provided on the front surface of the lower mold 22 '. There is. On the other hand, the inner mold 21 is formed in a cylindrical shape excluding the front head 24, and the front head 24 has a pair of upper and lower circular arc grooves 25, 25 for introducing the synthetic resin plates p, p. Are formed to face each other, and the upper and lower molds 22,
Engaging step portions 26, 26 'are formed to engage with the 2'hooks 23, 23'.

In the press molding machine 2 having such a structure, the inner mold 21 and the upper and lower molds 22, 22 'are closed when the upper and lower molds 22, 22' are closed by lowering the upper mold 22 as shown in FIGS. A cylindrical gap 27 for molding is formed between the mold 22 and 22 '. When the upper die 22 is lifted from this state, the hooks 23, 23 of the upper die 22 are engaged with the engaging stepped portion 26 at the upper edge of the inner die 21, as shown in FIG.
And the inner mold 21 is pulled up to a position where the hooks 23 ', 23' of the lower mold 22 'and the engaging step 26' of the lower edge of the inner mold 21 are engaged. Therefore, when the upper and lower molds 22 and 22 'are opened, the gap 27 between the inner mold 21 and the upper and lower molds 22 and 22' is expanded, so that the synthetic resin plate p can move freely.

According to the manufacturing method of the present invention, first, the above-mentioned synthetic resin plates p are arranged vertically as shown in the figure, supplied to the heating device 1, and heated there. It is necessary to set the heating temperature above the melting temperature of the resin, and if it is lower than the melting temperature, the resin will not melt at the time of the next press molding because the resin will not melt and the joining of the synthetic resin plates p, p Not enough,
The disadvantage is that a satisfactory pipe cannot be obtained. As an example of the heating temperature, in the case of a polypropylene resin plate, the melting temperature or more and 250 ℃ or less, preferably 210 ~ 230 ℃
It is heated at the temperature of. If the temperature exceeds 250 ° C, the polypropylene resin deteriorates and loses its strength, so it should be avoided.

When the synthetic resin plate p is heated in this manner, the synthetic resin layer r is melted and the molten resin is partially mixed with the long glass fiber layer g, so that the synthetic resin plate p becomes soft but loses its shape. Absent.

The upper and lower synthetic resin plates p, p heated as described above are used for the inner metal when the upper and lower molds 22, 22 'of the press molding machine 2 are opened as shown in FIG. While being curved through a pair of upper and lower circular arc grooves 25, 25 of the mold 21, it is introduced between the inner mold 21 and the upper and lower molds 22, 22 '. As shown in FIG. 3, the upper and lower synthetic resin plates p, p thus introduced are placed on the inner mold 21 and the lower mold 22 ', respectively.

When the introduction of the synthetic resin plates p, p is completed, the upper and lower molds 22, 22 'are closed by the lowering of the upper mold 22, as shown in FIGS. 1 and 4, and the synthetic resin plates p, p are closed by the inner mold 21. And the upper and lower dies 22 and 22 '. When pinched in this way, the synthetic resin plate p,
Since the viscosity of the molten resin of p is as low as 100,000 poise as described above, the molten resin easily flows under that pressure, and the cylindrical gap between the inner mold 21 and the upper and lower molds 22, 22 'is 27 While being buried, they are joined to each other and integrally molded into a tubular shape. At the same time, the long glass fibers in the upper and lower synthetic resin plates p, p also move and diffuse along with the flow of the molten resin, and are substantially evenly contained in the resin molded into a cylinder. Therefore, at the joints of the synthetic resin plates p, p, the resins from above and below are united, and the long glass fibers from above and below are contained intertwined with each other, so that the same great strength as in the non-joined portions can be obtained.

When the press molding is completed in this way, the upper mold 22 is lifted to open the upper and lower molds 22, 22 'as shown in FIGS. The resin pipe A is taken up by the take-up rolls 3,3. The synthetic resin plates p, p connected to the pipe A along with the take-up are the inner mold 21 and the upper and lower molds 22, 2 of the press molding machine 2.
Introduced between 2 '.

After that, by repeating the press molding in the same manner, a continuous long glass fiber-containing synthetic resin pipe A can be efficiently manufactured.

The synthetic resin pipe A containing long glass fibers obtained by the above method has a constant wall thickness as shown in FIG. 5 because it is formed by press molding. The long glass fibers are substantially evenly contained in the joint portion of the synthetic resin plates p, p in a state of being entwined with each other by moving and diffusing, so that there is almost no partial variation in the long glass fiber content.

In order to obtain a synthetic resin pipe having a high strength at the joint portion of the synthetic resin plates p, p, a pair of left and right convex rib forming surfaces 28a, 28a and 28a ', 28a' are respectively provided as shown in FIG. Using the upper and lower molds 22a and 22a ', the synthetic resin pipe A'in which the convex ribs a and a are formed on the left and right joints as shown in FIG. 7, or the upper and lower molds as shown in FIG. Of synthetic resin plate p, p
It suffices to increase the joint area by forming recesses p1 and protrusions p2 that mesh with each other at both ends. When the convex ribs a, a as described above are formed, the long glass fibers flow into the inside thereof from above and below, so that the strength of the bonded portion is significantly improved.

In order to form four convex ribs in the circumferential direction in order to increase the rigidity of the formed synthetic resin pipe, rib forming grooves 29, 29 'are formed in the upper and lower molds 22b, 22b' as shown in FIG. The synthetic resin plate may be pressed by providing the convex rib forming surfaces 28a and 28a ', respectively.

Further, in order to form the convex ribs at intervals in the axial direction of the synthetic resin pipe as shown in FIG. 11, as shown in FIG. 10, the upper and lower molds 22c having rib grooves 30, 30 'provided on the pressing surface are formed. , 22c ', the molten resin flows and the rib grooves 30, 30'
At the same time as filling the gaps, the long glass fibers also move along with the flow and enter the rib grooves 30, 30 'to form a pipe A "around which the convex ribs b are provided.

Although the present invention has been described above with reference to the respective embodiments, the present invention is not limited to such embodiments. For example, an inner die of a press molding machine is changed to a prismatic shape to form a square pipe. It goes without saying that various modifications can be made, such as manufacturing or using a press molding machine in which the inner mold is surrounded by split outer molds from the left and right sides.

EFFECTS OF THE INVENTION As is clear from the above description, according to the present invention, a high-strength synthetic resin pipe containing long glass fibers having a constant wall thickness and almost no partial variation in long glass fiber content can be efficiently and continuously connected. It is possible to obtain the effect that it can be manufactured efficiently.

[Brief description of drawings]

FIG. 1 is an explanatory view of an embodiment of the manufacturing method of the present invention, and FIG. 2 shows a press molding machine used in the present invention. FIGS. 1 (a) and 1 (b) show a state in which outer mold halves are closed. The fractured side view and the front view of FIG. 3 are the fractured side view and the front view of the principal part in the state where the split outer mold is opened, and FIG. 3 is the inner mold and the outer mold. FIG. 4 is a sectional view showing a state in which a synthetic resin plate is introduced between the two, FIG. 4 is a sectional view showing a state in which the synthetic resin plate is clamped by an inner mold and a split outer mold, and FIG. Sectional drawing of the synthetic resin pipe containing long glass fiber obtained, FIG. 6 is a sectional view showing the introduction state of the synthetic resin plate of another embodiment using a press molding machine in which the shape of the outer mold is different, FIG. Is a sectional view of a synthetic resin pipe containing long glass fibers obtained in the same example, and FIG. 8 shows another example of the synthetic resin plate used in the present invention. FIG. 9 is a partial perspective view, FIG. 9 is a sectional view showing the introduction state of a synthetic resin plate of another embodiment using a press molding machine in which the shape of the outer split mold is further different, and FIG. 10 is the outer split mold closed. 11 is a side view of a main part of another embodiment of the present invention in a broken state, FIG.
The figure is a perspective view of a synthetic resin pipe containing long glass fibers obtained in the same example. 1 ... Heating device, 2 ... Press molding machine, 21 ... Inner mold,
22,22 ', 22a, 22a', 22b, 22b ', 22c, 22c' ... External mold, 27 ... Gap, p ... Synthetic resin plate, g ... Long glass fiber layer, A, A ' , A ″ …… Synthetic resin pipe with long glass fiber.

Claims (1)

[Claims] 1. A synthetic resin plate having a low softening and melting viscosity containing a long glass fiber layer is heated to provide the above-mentioned structure between an inner die of a press molding machine and a split outer die surrounding the inner die from both sides. Introducing a plurality of heated synthetic resin plates, the synthetic resin plates are clamped by an inner mold and a split outer mold to be integrally molded into a cylindrical shape. Production method.