JPH03275335A - Polyvinyl chloride resin tube for lining existing tube - Google Patents

Abstract

PURPOSE:To uniformly expand peripherally by a method wherein the resin tube concerned is made by blending 3-25 pts.wt. of MMA-based and/or MBS- based modifiers with 100 pts.wt. of mixture mainly consisting of mixture of 40-60wt.% of polyvinyl chloride resin having the mean degree of polymerization of 400-600 and 60-40wt.% of polyvinyl chloride resin having the mean degree of polymerization of 1,050-1,350. CONSTITUTION:Polyvinyl chloride resin tube P for lining for repairing and reinforcing existing tube is made out of resin composition which is prepared by blending 3-25 pts.wt. of MMA-based and/or MBS-based modifiers with 100 pts.wt. of mixture mainly consisting of mixture of 40-60wt.% of polyvinyl chloride resin having the mean degree of polymerization pL of 400-600 and 60-40wt.% of polyvinyl chloride resin having the means degree of polymerization pH of 1,050-1,350. As a result, even when unevenness develops in temperature distribution by heating, uniform and satisfactory elongation is realized in the range of working temperature, resulting in realizing uniform tubular thickness after expansion and preventing the bursting of the tube from occurring at expansion.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to vinyl chloride resin pipes for lining the inner surface of existing pipes, and more specifically to underground or This invention relates to a vinyl chloride resin pipe for lining an existing pipe buried inside a building frame, which is later inserted into the inner surface and installed as a lining for the purpose of repairing, reinforcing, etc.

BACKGROUND OF THE INVENTION Existing pipes as described above may suffer unexpected cracks or damage due to corrosion over the years or external pressure from the surrounding area. If such damage occurs, for example, in the case of underground pipes, there is a risk that underground water infiltration may cause accidents such as short circuits, current leaks, and disconnections in internal power wiring, communication wiring, etc. However, in practice, existing pipes of this type, such as those buried underground in above-ground structures or within the framework of the building itself,
It is difficult in construction to replace it itself.

For this reason, recently, in order to repair and reinforce existing pipes,
A lining method in which a synthetic resin pipe is later inserted inside the pipe and the inner surface is lined is attracting attention. As seen in Japanese Patent Application Laid-open No. 1-295828, this lining method involves inserting a thermoplastic synthetic resin pipe with an outer diameter smaller than the inner diameter into a softened state by heating it into the existing pipe to be repaired. 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.

Conventionally, resin pipes for lining as described above have an average degree of polymerization of 151,100 to 151,100, which is generally widely used as a material for forming underground pipes from various points of view such as material cost, durability, and thermal deformation characteristics. The use of hard vinyl chloride resin pipes of about 1,300 has been considered and used on many trials.

Problems to be Solved by the Invention However, it has been recognized that when such hard vinyl chloride resin pipes are used, the following problems occur during heating with a heating medium and pressurized expansion process after insertion into an existing pipe. ing.

That is, the resin pipe for lining has an inner diameter of 50 to 95% of the existing pipe inner diameter.
%, but in order to facilitate insertion into existing pipes, it is desirable to select and use one with a relatively small diameter. In that case, it is necessary to exhibit large elongation during heating and expansion. However, in practice, when steam is introduced into the vinyl chloride resin for lining to heat and soften it, drainage inevitably accumulates inside the pipe, creating areas that prevent sufficient heating, or forming parts that are too close to the inner surface of the existing pipe. Due to the influence of heat being taken away by the existing pipe side in the part where the resin pipe is
Variations in temperature distribution occur within a range of about 95°C. Of course, this temperature range is above the softening point temperature (73 to 75°C) of vinyl chloride resin.\However, during heating and expansion, non-uniform elongation occurs in the circumferential direction, and as a result, the tube thickness after expansion increases. There is a problem in that not only the tube becomes non-uniform, but also local over-expanded portions are generated, which may even cause cracks called bursts in the tube wall.

Furthermore, during lining construction, the resin pipe for lining shrinks in the radial and length directions due to thermal contraction during the cooling process after heating and expansion.

To cope with such contraction, pressure is applied inside the tube to cope with contraction in the circumferential direction, and both ends of the tube are fixed to cope with contraction in the length direction. However, for this reason, internal strain occurs in the resin pipe after the lining has been applied, resulting in a significant decrease in seismic strength and impact strength.

Therefore, even if the above-mentioned variations occur in the temperature distribution due to heating, this invention shows uniform and good elongation in the construction temperature range, and therefore makes the tube thickness uniform after expansion and prevents bursts from occurring during expansion. To provide a vinyl chloride resin pipe for lining, which can prevent such damage, improve workability, and quickly alleviate or eliminate internal distortion of the resin pipe after construction, thereby making it excellent in seismic strength. With the goal.

Means for Solving the Problems As a result of various experiments and research for the above-mentioned purpose, the inventors found that, in terms of the average degree of polymerization of the polyvinyl chloride resin used, two types of polychloride resins having different degrees of polymerization in specific ranges were found. By using a mixture of vinyl resins and selecting a specific modifier, it exhibits good elongation characteristics within the in-shell lining construction temperature range (approximately 75 to 95 degrees Celsius). We have discovered that the internal strain that occurs in the resin pipe after construction can be quickly alleviated or eliminated, while making the change in elongation relatively small, and that it is possible to obtain practically sufficient strength, impact resistance, and rigidity, and the present invention I was able to complete it.

That is, the present invention uses vinyl chloride resin pipes for lining for repairing and reinforcing existing pipes as a specific object, and has an average degree of polymerization of 1.
The main component is a mixture of 40 to 60% by weight of a polyvinyl chloride resin of 5L400 to 600 and 60 to 40% by weight of a polyvinyl chloride resin of an average degree of polymerization of i5.1050 to 350, based on 100 parts by weight of the mixture. , a resin composition containing 3 to 25 parts by weight of an MMA-based and/or MBS-based modifier.

The polyvinyl chloride resin that is the main component of the resin pipe according to the present invention is used in combination with two types of polyvinyl chloride resins having different average degrees of polymerization in the above-mentioned construction temperature range (approximately 75 to 95 The purpose is to provide the material with as good elongation as possible at temperatures (°C) and to alleviate or eliminate internal stress strain in a short period of time. The reason why the average degree of polymerization of each polyvinyl chloride resin is defined within the above range is as follows. That is, the average degree of polymerization (PL
) is less than 400, the impact strength will be significantly inferior, and if it exceeds 600, the elongation will be low in the above-mentioned construction temperature range, and bursting will easily occur during heating expansion. Furthermore, if the average degree of polymerization (PII) of the polyvinyl chloride resin with a relatively higher degree of polymerization is less than 1050, the resin pipe will have significantly poor mechanical strength,
This is because if it exceeds 0, the elongation within the above-mentioned construction temperature range will be insufficient and the workability will also be poor. The present inventors measured the original average elongation rate at a temperature of 80°C for various mixtures composed of various combinations of two types of polyvinyl chloride resins with different average degrees of polymerization, and When a stress relaxation property test was conducted, the results were as shown in Table 1 below.

Table 1 As shown in the results in Table 1 above, sample fish 1 to 3 were mixed with two types of polyvinyl chloride resin within the specified range of the present invention.
80, which is a relatively low temperature within the construction temperature range, compared to sample Nα4.5, which deviates from the specified range.
It can be seen that it shows relatively good elongation under heating conditions at .degree. C., and also has a significantly low stress residual rate over time. The most preferable range of average degree of polymerization of each polyvinyl chloride resin to be mixed with each other is T) L450 to 5501 for those with a low degree of polymerization, p, 110 for those with a high degree of polymerization.
It is about 0 to 1200.

Regarding the blending ratio of the above two types of polyvinyl chloride resins, the blending amount of the resin with a relatively low average degree of polymerization is 60% by weight.
If it exceeds 40% by weight, the mechanical strength of the resin pipe will drop significantly, and if it is less than 40% by weight, uniform elongation within the above-mentioned construction temperature range will not be obtained.

The most preferable mixing ratio is about 45 to 55% by weight for polyvinyl chloride resins with a relatively low degree of polymerization.

Next, the addition of a modifier is essential for improving the elongation and strength of polyvinyl chloride resin, and among the various modifiers known as modifiers for vinyl chloride,
In particular, MMA-based and MBS-based modifiers should be used selectively, either alone or in combination. The MMA modifier is a copolymer rubber mainly composed of acrylic ester, methyl methacrylate,
It is a multi-component resin obtained by graft polymerization of monomers such as styrene and acrylonitrile, and the MBS modifier is a butadiene-styrene-methyl methacrylate copolymer.

By adding one or two of these modifiers, it is possible to achieve the desired effect of improving elongation and strength, but MBS
The effect of improving the weather resistance of resin pipes is insufficient in the case of MMA-based modifiers, and in this respect, it is relatively preferable to use MMA-based modifiers.

Other modifiers for vinyl chloride resin include CPE and EV.
A type, ABS type, etc. are known, but none of them can be expected to have an effect of improving elongation in the lining construction temperature range or is insufficient compared to the use of the above-mentioned specific modifier used in the present invention. becomes.

If the proportion of the modifier is less than 3 parts by weight per 100 parts by weight of the polyvinyl chloride resin mixture, the practical strength of the resin pipe will be insufficient and the elongation improvement effect within the lining construction temperature range will also be insufficient. be. However, even if more than 25 parts by weight is added, no further improvement in elongation or practical strength can be expected; rather, it is disadvantageous in that it causes a decrease in rigidity. The most preferable amount of the modifier is about 6 to 18 parts by weight per 100 parts by weight of the polyvinyl chloride resin mixture.

In addition, it goes without saying that the polyvinyl chloride composition according to the present invention may contain stabilizers, lubricants, pigments, coloring agents, etc. that are commonly added.

The types and amounts of these additives are not particularly limited, and may be in accordance with conventional methods for manufacturing resin pipes. For example, stabilizers include lead-based, organotin-based,
It is common to mix 1.0 to 3.0 parts by weight of one type or a combination of two or more metal soaps, etc., and 0.5 to 1.5 parts by weight of lubricants as fillers. Titanium oxide, etc. and colorants may be blended in an amount of 0.5 parts by weight or less, if necessary.

Further, the resin pipe according to the present invention may be manufactured according to a normal extrusion molding method, and there are no particular restrictions on manufacturing conditions or the like.

Effects of the Invention According to the resin pipe made of the resin composition of the present invention, as can be seen from the examples below, the temperature within the construction temperature range during lining construction for repairing existing pipes, etc. It exhibits relatively stable and good elongation properties despite variations in Therefore, when the tube is expanded by applying pressure from the inside while being heated by introducing steam, the tube will elongate uniformly in the circumferential direction regardless of slight unevenness in temperature, and the wall thickness of the tube can be made uniform. At the same time, it is possible to prevent the occurrence of bursts due to localized excessive elongation, expand the tolerance range for variations in construction conditions such as heating temperature conditions during construction, and improve workability while ensuring reliable lining construction without defects. do.

Furthermore, internal stress and strain generated within the resin pipe after construction can be alleviated or eliminated within a relatively short period of time. Therefore,
It can be made to have excellent strength, especially seismic strength and impact resistance, and can be constructed with a lining with excellent durability and safety.

Examples Various polyvinyl chloride pipes having a diameter of 123 mm and a wall thickness of 4.0 mm (within ±1%) were manufactured by extrusion molding using resin compositions having the formulations shown in Table 2 below.

Table 2 The various vinyl chloride resin pipes (P) mentioned above are classified into inner diameters of 150 (20% expansion) and 185 as shown in Figure 1.
(50% expansion tube) Two types of metal test tubes (M)
(corresponding to the existing pipe), and has a steam port (1) and a steam outlet (0) at both ends (R
), steam (S) at a temperature of 111°C and a pressure of 5/2 is injected from the steam inlet (I) to expand the resin pipe (P) and cover its outer peripheral surface with the test pipe (
It was brought into close contact with the inner circumferential surface of M), and the pressurized state was maintained for 2 hours, and then cooled with compressed air.

Then, the resin tube (P) was removed from the test tube (M), and a sample (
20% expansion tube), the wall thickness distribution in the circumferential direction of the resin tube after expansion at the section XX in FIG. 1 was measured and its tolerance was investigated.

On the other hand, a sample (
Regarding the 50% swollen tube), the presence or absence of steam leakage from the public wall during inflation and the presence or absence of bursts were examined by visual inspection after inflation.

In addition, for each resin composition of the above formulation, JISK6
According to the test method of No. 742, the elongation rate was determined in an atmosphere of 80 ° C., and the test piece was taken in the same manner as above, and the test piece was subjected to 0.5% tensile deformation and maintained,
The stress residual rate after 100 hours was measured.

The results are also listed in Table 3.

[Margin below]

As shown in the table above, the resin pipe made of the polyvinyl chloride resin composition according to the present invention has a significantly lower temperature than the comparative example at 80°C, which corresponds to the relatively low heating temperature during lining construction. Shows extremely good elongation. Therefore, when the resin pipe for lining is expanded under a heated state, the degree of non-uniformity in the wall thickness of the pipe is small, and it can be expanded uniformly in the circumferential direction, resulting in a severe expansion rate of 50%. It was confirmed that no burst occurred even when the pipe was inflated, and that it was possible to safely and reliably install lining inside existing pipes. In addition, the resin pipe made of the polyvinyl chloride resin composition according to the present invention has excellent properties of relieving internal stress strain over time after being heated and expanded, and also has excellent impact resistance strength. was confirmed.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a state in which an expansion test is performed on a resin pipe for lining. (P)...Resin pipe, (M)...Test tube,...
Steam inlet, (S)...Steam. (I) As of April 26, 1990

Claims (1)

[Claims] 40-60% by weight of polyvinyl chloride resin with an average degree of polymerization @p@_L400-600 and an average degree of polymerization @p@_H105
A resin composition whose main component is a mixture with 60 to 40% by weight of a polyvinyl chloride resin of 0 to 1350, and 3 to 25 parts by weight of an MMA-based and/or MBS-based modifier to 100 parts by weight of the mixture. A vinyl chloride resin pipe for lining existing pipes.