JP2637375B2 - PVC pipe for lining existing pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vinyl chloride resin pipe for lining the inner surface of an existing pipe, and more particularly to an underground or building body which mainly constitutes a pipe for laying cables such as power wiring and communication wiring. The present invention relates to a vinyl chloride resin pipe for lining, which is subsequently inserted into an inner surface of a buried existing pipe for repair, reinforcement, etc., and is installed in a lining state.

[0002]

2. Description of the Related Art Existing pipes as described above may cause unexpected cracks or damage due to corrosion over many months or external pressure from the surroundings. When these damages occur, for example, in the case of an underground pipe, there is a risk of causing an accident such as a short circuit, a short circuit, a disconnection, or the like in an internal power wiring, a communication wiring, or the like due to infiltration of groundwater or the like. However, in practice, for example, buried underground in buildings above ground,
Alternatively, it is difficult to replace an existing pipe of this kind, which is buried in the body of the building itself, in terms of construction.

[0003] Therefore, recently, in order to repair or reinforce the existing pipe, a synthetic resin pipe is inserted later inside the pipe,
A lining method for lining the inner surface has been attracting attention. In this lining method, as shown in Japanese Patent Application Laid-Open No. 1-295828, a thermoplastic synthetic resin pipe having an outer diameter smaller than its inner diameter is inserted into an existing pipe to be repaired in a heat-softened state. By introducing steam into the resin pipe and applying internal pressure, the resin pipe is expanded in the radial direction, brought into close contact with the inner surface of the existing pipe, and then solidified as it is using a cooling medium.

Further, as the synthetic resin tube used in the above-mentioned lining method, it is preferable to use a tube having flexibility and good heat expansion properties. Developed polyvinyl chloride pipe for lining showing stable elongation characteristics (Japanese Patent Laid-Open No. 3-275334).
issue).

[0005]

However, the existing pipe,
In particular, iron pipes are mainly used for gas pipes and power wiring pipes, and there are many curved pipes, and the burial place is close to the ground,
The following problems may occur or may occur.

[0006] In addition to being a curved pipe, the unevenness of the inner surface due to corrosion of the iron pipe causes a large resistance when the resin pipe is inserted, making it impossible to insert the resin pipe, or causing abrasion of the resin pipe due to contact with the existing pipe, resulting in expansion during expansion. This may cause cracking. Also, even after construction, because the pipeline is buried near the ground,
It is susceptible to vibrations and ground changes due to vehicle traffic,
The existing pipe may be displaced and the inserted resin pipe may be cracked by receiving the stress.

[0007] In order to solve or prevent these problems, it is necessary to first reduce the resistance at the time of insertion of an existing pipe. Therefore, a resin pipe having excellent heat expansion properties is required to be inserted with a smaller diameter. Is desirable. Further, it is desirable to use a resin pipe which has excellent strength against shocks such as vibration and has flexibility which can follow the displacement of the existing pipe.

In view of the above technical background, the present invention provides a lining resin tube which is more excellent in heat expansion property, impact strength and flexibility than that described in the above-mentioned JP-A-3-275334. With the goal.

[0009]

As a result of various experiments and studies, the present inventors have found that a resin composition containing a vinyl chloride resin as a main component is sufficiently kneaded at a high temperature, and the particle size of the vinyl chloride resin in a molded product is reduced. Was found to have the highest heat expandability when the average particle size was 0.01 to 0.1 μm, and the present invention was completed. That is, the vinyl pipe for lining of the existing pipe of the present invention, in order to achieve the above object, the average degree of polymerization of vinyl chloride resin as a main material in a specific range, and the vinyl chloride resin vinyl in the molding process. Specific stabilizers and lubricants are used as a stabilizer and a lubricant for suppressing a decomposition reaction, and further a specific modifier for improving strength and flexibility is added.
~ 1100 straight vinyl chloride resin as the main component,
3.5 to 7.0 parts by weight of a lead-based stabilizer having a lead content of 75% or more based on 100 parts by weight of the straight vinyl chloride resin,
It comprises a resin composition containing 1.5 to 3.0 parts by weight of a lead-based lubricant and 10 to 12 parts by weight of an acrylic modifier.

In the above resin composition, a straight polymer obtained by homopolymerizing a vinyl chloride monomer is used as a vinyl chloride resin as a main component in a resin containing other components (vinyl acetate copolymer, ethylene copolymer). This is because heat stability at the time of high temperature and melting is poor, and it is easily decomposed when highly kneaded. If the straight vinyl chloride resin has an average degree of polymerization of less than 700, the strength, particularly the impact strength (IZOD strength), is insufficient, and a sufficient practical strength as a lining tube cannot be obtained. However, in the case of vinyl chloride resin having an average degree of polymerization exceeding 1100, the elongation is low in the lining working temperature range of about 75 to 95 ° C., and particularly the elongation at relatively low temperature is poor. Nonuniform thickness and burst are likely to occur. The preferred lower limit of the average degree of polymerization is 800 and the preferred upper limit is 1100.

[0011] Next, in the resin composition, a lead-based stabilizer and a lead-based lubricant are blended as essential components for the following reasons.

That is, the expansion performance of the resin tube at the time of heating is such that the particle size of the vinyl chloride resin in the molded article is 0.01 to 0.1.
As described above, it is effective to set the thickness to μm. The particle diameter in the above range is set to a temperature of 190 to 2 during molding.
This can be achieved by setting the temperature to a high temperature of 00 ° C. and sufficiently kneading with a high shearing elasticity in a molding machine such as an extrusion machine to disintegrate the coarse particles to densify the particle structure.

However, a vinyl chloride resin undergoes a decomposition reaction at about 190 ° C., and since this reaction is a chain reaction, kneading at such a high temperature causes a rapid deterioration of the resin. Therefore, a high-performance stabilizer for suppressing the thermal decomposition reaction is required. The reason why lead-based ones are selected from various stabilizers is that they are excellent in decomposition suppressing power especially at high temperatures. However, those having a low lead content are poor in the effect of suppressing the thermal decomposition of the vinyl chloride resin, so it is necessary to use a stabilizer having a lead content of 75% or more. Specific examples of such a lead-based stabilizer include dibasic lead sulfite (lead content 80%), tribasic lead sulfate (lead content 83%), and dibasic lead phosphite (lead content 83%). ) And the like.

Usually, in molding a resin tube, the material resin is melt-kneaded in a molding machine and then press-fitted into a round die for forming a tube. Due to poor slippage, the molten resin drifts in the die and tends to stay. Such a drift increases the variation in the thickness of the tube extruded from the die and reduces the heat expansion property of the resin tube, and the stagnation causes degradation and degradation of the resin. Therefore, a lubricant is required that imparts continuous lubricity to the molten resin up to the die exit even at a high temperature. The reason why lead-based metal soap is selected from various lubricants is that it is particularly excellent in lubricity at high temperatures, and examples thereof include lead-based metal soaps such as lead stearate and dibasic lead stearate.

[0015] The larger the molding die, the longer the time the molten resin is exposed to high temperatures, and the more likely it is for the drift or stagnation to occur in the die. Stability and lubricity are required. In addition, the resin tube is usually manufactured as a rolled material of about 200 m. However, the longer the length, the more easily the vinyl chloride resin is decomposed, so that thermal stability and lubricity are also required.

If the amount of the lead-based stabilizer is less than 3.5 parts by weight per 100 parts by weight of the straight vinyl chloride resin, the effect of suppressing the above-mentioned thermal decomposition reaction of the vinyl chloride resin is poor. If the amount is more than the weight part, it will remain in a solid state in the molded tube, so that the expansion during heating is rather inhibited. Therefore, the blending ratio of the lead-based stabilizer is 3.5 to 7.0 with respect to 100 parts by weight of the straight vinyl chloride resin.
It must be 0 parts by weight. Also, as described above, the larger the diameter of the resin pipe, the higher the thermal stability is required.
When the diameter is relatively small, less than 50 mm, the amount is preferably 3.5 to 5.0 parts by weight, particularly preferably 3.5 to 4.5 parts by weight.
For relatively large ones with a diameter of 250 mm or more, 5.0 to 7.0.
0 parts by weight is preferable, and particularly 6.0 to 7.0 parts by weight is preferable.

On the other hand, if the compounding ratio of the lead-based lubricant is less than 1.5 parts by weight with respect to 100 parts by weight of the straight vinyl chloride resin, the effect of eliminating the drift of the molten vinyl chloride resin in the die described above is poor. If the amount exceeds 3.0 parts by weight, the shearing force in the molding machine decreases, so that high kneading cannot be performed and the particle structure of the vinyl chloride resin cannot be densified. Therefore,
The blending ratio of the lead-based lubricant is 1.5-3. It must be 0 parts by weight. Also, as described above, a resin pipe having a large diameter requires higher lubricity, so that a relatively small resin pipe having a diameter of less than 250 mm preferably has a weight of 1.5 to 2.5 parts by weight, particularly 1.5 to 2 parts by weight. 0.0 parts by weight is preferred. In the case of a relatively large one having a diameter of 250 mm or more, the amount is preferably 2.0 to 3.0 parts by weight, particularly preferably 2.5 to 3.0 parts by weight.

Further, the compounding of the modifier is essential for improving mainly the elongation and strength of the vinyl chloride resin. Among various known modifiers for vinyl chloride, especially acrylic resin is used. The system modifier should be selectively used. Specifically, a multi-component resin obtained by craft-polymerizing a monomer such as methyl methacrylate (MMA), styrene, or acrylonitrile on a copolymer rubber mainly composed of an acrylate ester can be exemplified.

If the mixing ratio of the acrylic modifier is less than 10 parts by weight per 100 parts by weight of the straight vinyl chloride resin, the practical strength of the resin pipe is insufficient, and the effect of improving the elongation in the lining construction temperature range is also reduced. Not enough, while 1
Even if added over 2 parts by weight, the effect of improving elongation and practical strength cannot be expected to be further improved, but rather it is disadvantageous in that the rigidity is reduced. Therefore, the blending ratio of the acrylic modifier must be 10 to 12 parts by weight based on 100 parts by weight of the straight vinyl chloride resin.

In addition, it goes without saying that the resin composition according to the present invention may be added with fillers, pigments, coloring agents and the like which are usually added. The type and amount of these additives are not particularly limited, and may be in accordance with a conventional method for manufacturing a resin tube. For example, titanium oxide and the like as a filler and a coloring agent may be blended in a range of 0.5 part by weight or less based on 100 parts by weight of the straight vinyl chloride resin as needed.

The production of the resin tube according to the present invention may be carried out according to a usual extrusion molding method, and there is no particular restriction on the production conditions and the like.

[0022]

In the vinyl chloride resin pipe for lining of the existing pipe according to the present invention, the resin composition forming the pipe is referred to as a lead-based stabilizer containing a high concentration of lead, a lead-based lubricant, and an acrylic-based modifier. By using a specific additive, the thermal stability and lubricity of the resin composition are improved, and thus the heat expansion property, impact strength and flexibility of the resin tube are improved.

[0023]

EXAMPLES Using a resin composition having the composition shown in Table 1 below, a long lining vinyl chloride resin tube for lining was manufactured at a molding temperature of 195 ° C. by an extrusion molding method. The dimensions of the resin pipe are 113 mm in diameter x 4.0 mm in thickness corresponding to the existing pipe with a diameter of 150 mm, and 3 mm in diameter corresponding to the existing pipe with a diameter of 450 mm.
Two types of 75 mm x 8.0 mm thick were used.

[0024]

[Table 1]

The following items were evaluated for each of the manufactured resin tubes. [Discoloration and appearance] The resin tube was evaluated by visual observation. [Variation in Resin Tube Thickness] The thickness of the resin tube was measured and evaluated based on the maximum thickness and the minimum thickness. [Heat expansion property and inner surface condition] As shown in FIG. 1, each resin pipe (P) cut into a length of 2 m is inserted into a test pipe (M) having an inner diameter of 150 mm or 450 mm, which is regarded as an existing pipe. Is closed with a clamp-type plug (R) having a steam inlet (I) and the same outlet (O), at a temperature of 11 ° C.
Steam at 0 ° C. and a pressure of 0.6 kg / cm ² is press-fitted to expand the resin tube (P) so that its outer peripheral surface is brought into close contact with the inner peripheral surface of the test tube (M). After holding for 2 hours while keeping, the mixture was cooled with compressed air. Then, the resin pipe (P) is removed from the test pipe (M),
The presence or absence of breakage of the resin tube (P) and the state of the inner surface were visually observed.

[Impact strength] 64 mm from the above expanded resin tube
A test piece of × 12.7 mm was cut out and subjected to JIS K7110.
The IZOD intensity was measured based on the above. [Flexibility] From the above-mentioned expanded resin tube, 113 mm diameter tube is 1
0mm x 80mm test piece, 375mm diameter tube is 15mm x 16
A test piece of 0 mm was cut out and according to JIS K7203,
A bending test was performed, and the occurrence of cracks, cracks, and the like in the test piece when the deflection amount was set to 20 mm was evaluated by visual observation. Table 2 shows the evaluation results.

[0027]

[Table 2]

As shown in the above table, the resin compositions of the examples can be formed into good tubes having a uniform thickness and no scorching lines as compared with those of the comparative examples. It was confirmed that the composition exhibited extremely good elongation upon heating and also had excellent impact strength and flexibility after expansion.

[0029]

As described above, the vinyl chloride resin pipe for lining of the existing pipe of the present invention has an average degree of polymerization of 700-11.
No. 00 as a main component, 3.5 to 7.0 parts by weight of a lead stabilizer having a lead content of 75% or more and 100 parts by weight of the straight vinyl chloride resin, To 3.0 parts by weight and 10 parts of acrylic modifier
Since the resin composition contains up to 12 parts by weight, it exhibits good swelling properties when heated. Therefore, it is possible to insert the pipe into the existing pipe in a state of a smaller diameter than the conventional resin pipe, so that the insertion work is facilitated and abrasion due to contact with the inner surface of the existing pipe can be avoided. In addition, even after construction, the existing pipes are buried near the ground and are susceptible to vibrations and ground fluctuations from the ground because they have excellent impact strength, excellent flexibility, and good followability to existing pipes. Stable construction is possible.

Further, the thermal stability and lubricity of the resin composition are improved by the above-mentioned specific additives, so that a large-diameter resin pipe can be manufactured, the ability to cope with an existing pipe is expanded, and a long pipe is used. The resin tube can be manufactured, and the production efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an execution state of an expansion test of a lining resin pipe.

[Explanation of symbols]

 P: Resin tube M: Test tube I: Steam inlet S: Steam

Claims (1)

(57) [Claims] 1. A lead-based stabilizer comprising a straight vinyl chloride resin having an average degree of polymerization of 700 to 1100 as a main component and a lead content of 75% or more based on 100 parts by weight of the straight vinyl chloride resin. 0 parts by weight, lead lubricant 1.5-3.
A vinyl chloride resin pipe for lining of an existing pipe, comprising a resin composition containing 0 parts by weight and 10 to 12 parts by weight of an acrylic modifier.