JPH0729385B2 - Method for manufacturing corrosion resistant reinforced plastic pipe - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to a method of manufacturing a reinforced plastic pipe having excellent corrosion resistance.

[Prior art]

In recent years, a composite pipe having a sandwich structure in which an intermediate layer such as a resin mortar is provided between an inner and outer reinforced resin layer having a long glass fiber as a reinforcing material may be used in a pipe of a large diameter sewer or the like. is there. This type of composite pipe is lighter in weight and more excellent in corrosion resistance than metal pipes and concrete pipes.

[Problems to be Solved by the Invention]

By the way, the water flowing down the sewer contains a part of domestic wastewater such as industrial wastewater, and the water quality may be extremely poor depending on the location, and the above-mentioned composite pipe may not show sufficient corrosion resistance. That is, in the composite pipe obtained by the conventional manufacturing method, the glass fiber material as a reinforcing material exists up to the vicinity of the inner wall surface of the pipe, and when the inner wall surface has pinholes or cracks, the water that flows down has these pinholes or cracks. Through which the glass fiber material continuously embedded in the tube wall penetrates. Since glass fiber has poor chemical resistance and is particularly weak against alkali and acid, it may deteriorate indefinitely and the strength of the inner surface reinforced resin layer may be significantly reduced, and it may be damaged by external force such as earth pressure. There's a problem. Therefore, the present applicant has previously proposed a method of manufacturing a composite pipe as disclosed in Japanese Patent Publication No. 61-29254. This manufacturing method, a strip containing a non-woven fabric, a group of short fibers and a resin on the core mold, after depressurizing by depressurizing strongly, the resin is semi-cured and wound on the core mold to form an inner surface protective layer. It is formed so that the outer surface reinforced resin layer is formed after that, the inner surface protection layer is sufficiently defoamed and pin holes are very few and it is semi-cured in advance. It has an excellent effect that no crack is generated. However, even in the composite pipe obtained by this production method, since the inner surface protective layer contains the nonwoven fabric and the short fibers,
It was impossible to completely eliminate the pinholes, and even if the pinholes were completely impregnated, water was present at the interface between the resin and the roving, and the permeation of the chemical solution was unavoidable. In view of such circumstances, the present invention has an object to provide a method of manufacturing a reinforced plastic pipe having excellent corrosion resistance.

[Means for Solving the Problems]

In order to achieve such an object, the present invention forms an uncured thermosetting resin layer of a desired thickness around a cylindrical mold that has been subjected to a mold release process, and heats the mold to heat it. After curing the surface side portion of the thermosetting resin layer in a non-cured state by a predetermined thickness from the mold side surface, a reinforcing material and a thermosetting resin are wound thereon and heated again. The gist is a method of manufacturing a corrosion-resistant reinforced plastic pipe in which all uncured thermosetting resins are cured.

[Work]

According to the above configuration, the surface side exposed to the outside air is kept uncured by heating the uncured thermosetting resin layer having a desired thickness formed on the die peripheral surface from the die side. A cured layer having a predetermined thickness is formed from the surface on the side of the mold, and first, a resin-only layer having a predetermined thickness is formed in a portion corresponding to the innermost layer of the tube. Next, the reinforcing material and the thermosetting resin are wound further, but the resin in the part corresponding to the innermost layer has already been hardened, and it is wound so that glass fiber etc. as a reinforcing material does not enter the innermost layer. Can be turned. Then, after that, all the resins can be cured to complete the tube.

【Example】

Hereinafter, the present invention will be described in detail with reference to the drawings showing an embodiment thereof. FIG. 1 shows an example of a manufacturing apparatus used for carrying out the method for manufacturing a corrosion-resistant reinforced plastic pipe according to the present invention. As shown in the figure, the manufacturing apparatus 1 is a molding device of a drostholm type, and is a cylindrical metal whose one side is open to rotate around a rotary shaft 12 horizontally extended from the apparatus main body 11. A mold (mandrel) 13 is provided, and an endless steel belt 14 is spirally wound around the mold 13, and the mold surface 15 formed by the steel belt 14 is advanced by the rotation of the mold 13. ing. Then, the steel belt 14 reaching the open end of the mold 13 returns to the original position through the center of the mold 13 and is wound around the mold 13 again. Further, the mold 13 is configured such that the open end thereof faces the curing furnace 16. On the other hand, on the device body 11 side of the mold 13, the second
As shown in the figure, a preheating heater 17 is provided on the inner side, and a thermosetting resin supply hose 18 and a spatula 19 are provided on the outer side, respectively. The preheater 17 is provided only between the main body 11 of the apparatus and a preheat zone of a certain length, and preheats the mold 13 at that portion from the inside. In the figure, 3 is thermosetting resin, 21 is glass paper,
Reference numeral 22 is a glass strand, 23 is a resin concrete supply means, and 24 is a release sheet. Both the glass paper 21 and the glass strand 22 are impregnated with a thermosetting resin in advance. The manufacturing apparatus 1 is configured as described above, and the reinforced plastic pipe can be continuously obtained as follows. That is, the mold release sheet 24 is spirally wound while rotating the mold 13 and advancing the mold surface 15 formed by the steel belt 14 toward the curing furnace 16. Then, a desired amount of the thermosetting resin 3 is supplied from the supply hose 18 onto the release sheet 24, and the thermosetting resin layer 31 having a uniform thickness is formed continuously by the spatula 19. Thermosetting resin layer
31 moves gradually in the direction of the curing furnace 16 with the advance of the mold surface 15, but is heated from the mold 13 side by the preheat heater 17 while in the preheating zone, and from the portion facing the release sheet 24. It hardens gradually. However, in the preheating zone, the thermosetting resin layer 31 is set so as not to be completely cured, so that at least the surface in contact with the outside air may pass through the preheating zone while remaining in an uncured state. Has been The thickness of the cured portion can be freely changed by adjusting the amount of resin supplied, the mandrel molding length, the heater temperature, the molding speed, and the like. Then, the glass paper 21 as a reinforcing material, the glass strand 22 and the resin concrete 25 supplied from the resin concrete supply means 23, respectively, glass paper 21, glass strand 22, resin concrete 25, glass strand 22, glass paper 21 of After being laminated and wound in sequence, the reinforced plastic pipe can be continuously obtained by heating again in the curing furnace 16 to cure the uncured thermosetting resin. The release sheet 24
Are to be removed after molding. The obtained reinforced plastic tube is composed of only the innermost layer and the resin, and does not contain the fibrous material, filler, etc. that cause it, and therefore has no pinholes. Moreover, since it is made of resin only, the inner wall surface looks good. The resin used in this production method is not particularly limited, and examples thereof include unsaturated polyester resins, vinyl ester resins, and epoxy resins. Of these, vinyl ester resins are particularly preferable because of their excellent chemical resistance. . The resin forming the innermost layer and the resin wound with the reinforcing material may be the same resin, or different resins may be used. For example, if a quick-hardening resin is used as the resin forming the innermost layer, there is an advantage that the molding line can be shortened. Example 1 A FRPM tube having a diameter of 80 cm was molded using the manufacturing apparatus shown in FIG. The manufacturing conditions were as follows. Length of preheater 50cm Heater surface temperature 100 ℃ Molding speed 20m / h Resin used Unsaturated polyester resin (Permec N made by NOF CORPORATION including 1 phr hardener) Glass paper (200g / m ² ) Glass used Roving (No. 2200) The resulting tube had a glossy inner wall surface, and no pinholes, voids, etc. were found visually. Also, when the tube cross section was cut and observed, a resin-only layer was formed from the inner wall surface to a depth of 1 mm. (Comparative Example 1) The innermost layer of the tube was made of resin and glass chop (thickness 13 μm, length
A tube was molded in the same manner as in Example 1 except that a semi-cured sheet composed of 5 cm) and a polyester non-woven fabric (100 g / m ² ) was strongly pressed to defoam and then molded on a mold. The inner wall surface of the obtained tube was glossy, but the chop pattern was visible and was not good-looking. Further, when the tube cross section was cut and observed, the reinforcing fiber material was present up to the innermost layer. (Comparative Example 2) A tube was formed in the same manner as in Example except that the innermost layer of the tube was formed of resin and glass mat (300 g / m ² ). On the inner wall surface of the obtained tube, pinholes were partially seen and the matte was transparent, and the appearance was not good. Further, when the tube cross section was cut and observed, the reinforcing fiber material was present up to the innermost layer. The jig 4 as shown in FIG.
The tube 5 obtained in 2 was sliced into 30 cm widths, mounted and flattened by 5% to reproduce the state of being buried in the soil, and the inner wall surface of the tube was exposed to a 10 wt% sulfuric acid solution 6 at 23 ° C ± 1 ° C. The time until a white crack was formed on the inner wall surface of the pipe was measured. As a result, the tube obtained in Example 1 did not crack after 6070 hours, whereas Comparative Example 1 cracked white at 3000 hours and Comparative Example 2 at 700 hours. The method for manufacturing the corrosion-resistant reinforced plastic pipe according to the present invention is not limited to the above-mentioned embodiments. In the above embodiment, the reinforced plastic pipe is continuously molded by using the Drostholm molding apparatus, but it may be molded by the batch method. Further, if the surface of the mold has been previously subjected to a release treatment, the release sheet may not be used. Further, in the above example,
The obtained reinforced plastic pipe was a FRPM pipe having a resin concrete layer as an intermediate layer, but a normal FRP pipe without a resin concrete layer can also be obtained.

【The invention's effect】

The method for producing a corrosion-resistant reinforced plastic pipe according to the present invention, as described above, first, the thermosetting resin layer formed around the mold which has been subjected to the mold release treatment, the surface side portion thereof is in an uncured state. While holding the resin, a layer of resin only was formed on the innermost layer of the pipe by hardening it from the surface on the side of the mold to a predetermined thickness, and then a reinforcing material and a thermosetting resin were wound thereon, so that the inner wall surface of the pipe It is possible to provide an excellent reinforced plastic pipe which is smooth, has no pinholes, etc., and is free from deterioration in strength of the pipe due to corrosion of the glass fiber material as a reinforcing material.

[Brief description of drawings]

FIG. 1 is a side view showing an example of a manufacturing apparatus used for carrying out the manufacturing method according to the present invention, and FIG. 2 is a longitudinal sectional view showing a supply means portion of a thermosetting resin forming the innermost layer thereof. FIG. 3 is an explanatory view for explaining the state of the chemical resistance test of the obtained reinforced plastic. 13 …… Mold, 21 …… Glass paper (reinforcing material), 22 ……
Glass strand (reinforcing material), 24 …… Release sheet, 25…
… Resin concrete, 3… Thermosetting resin

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Claims (1)

[Claims] 1. An uncured thermosetting resin layer having a desired thickness is formed around a release-molded cylindrical mold, and the surface side of the thermosetting resin layer is heated by the heat of the mold. After curing a predetermined thickness from the mold side surface while holding the part in an uncured state, a reinforcing material and a thermosetting resin are wound on it and heated again to form an uncured thermosetting resin. A method for manufacturing a corrosion-resistant reinforced plastic tube that cures everything.