JPS63163084A - Plumbing pipe - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a water supply and drainage pipe, and more particularly to a water supply and drainage pipe that has improved blistering and layer peeling in halogen water with a low concentration of 50 ppm or less. [Prior Art] High pressure process (radical polymerization) has been used to process polyethylene for years. However, since halogen (mostly chlorine) is added for the purpose of sterilization, there is a problem that blisters will form on the surface that comes into contact with water when used for a long period of time, and sometimes a layer of 30 to 70 g thick will peel off. Examples of this were also discovered. In order to deal with this, JIS K87B2 was established for quality control. This evaluation method evaluates the occurrence of surface blisters at a chlorine concentration of 2000 ppm as a measure of chlorine water resistance. Comparing polyethylene in light of this standard, it was found that medium- and low-pressure polyethylene is superior to high-pressure polyethylene and passes the standard, and the market is gradually replacing the material. The mechanism by which halogen water causes blisters and layers to separate is currently unknown, but it has been determined that carbon black, which is added to protect pipes from UV deterioration, is the cause. . For this reason, the inner layer in contact with water is natural colored polyethylene, and the outer layer is polyethylene containing carbon black. 58-80
No. 458). On the other hand, as a study focusing on carbon black,
2 by increasing the particle size to 35-500p, m.
It has been shown that the chlorine resistance of water with a high concentration of 1,000 ppm is improved (Japanese Patent Application Laid-open No. 33288/1983).
Furthermore, with regard to additives, the addition of sulfur and the combination of a sulfur-based synergist and a specific phenolic antioxidant are known (JP-A-57-83341, JP-A-57-182890). issue). [Problem to be Solved by the Invention 1] However, since pipes for supplying water, hot water, and sewage cannot be easily repaired once they have been constructed, more reliable materials are required. According to experiments conducted by the present inventors, in the case of carbon blur and glue made by the same manufacturer, the coarser the particle size, the better the chlorine water resistance tends to be against high concentrations of 2000 ppm chlorine. However, even if the same type of carbon black is made by a different manufacturer, carbon black with a smaller particle size may have better chlorine water resistance, and it has been found that particle size alone does not lead to improvement in chlorine water resistance. did. Furthermore,
Even with the optimum carbon black in high concentration (2000pp■) chlorine water selected in this way, the halogen concentration is 50PPI, which is the halogen concentration of practical water! Surprisingly, we have found that in many cases, water with a chlorine concentration below has no effect at all. Additionally, the addition of sulfur and sulfur-based synergists has the drawback of being avoided in drinking water pipes due to their distinctive odor. From this situation, it is thought that the mechanism of blistering or inner layer peeling of polyethylene pipes due to halogen-containing water differs depending on the halogen concentration in the water, and from this perspective, water with a halogen concentration of 50 pp- or less, which is the halogen concentration of practical water, is considered to differ. A study was conducted. [Means for Solving the Problems J] As a result of the above-mentioned search, the present invention has been developed by adding a formamidine compound in addition to the carbon black formulation.
It was found that an extremely large improvement effect was exhibited at a chlorine concentration of 0PP11. That is, the present invention is a water supply and drainage pipe characterized by being made of an ethylene/α-olefin copolymer composition containing 0.5 to 5 weight 2 of carbon black and 0.01 to 1 weight 2 of a formamidine compound. . In the present invention, any type of carbon black can be used in combination with the formamidine compound, but it is preferable to use carbon black whose product of specific surface area and electron spin density is 1×1022 spins. m2/
Carbon black of g27g2 or less is used. The polyethylene used in the present invention is ethylene α obtained using a Ziegler type catalyst or a Phillips type catalyst.
It is an olefin copolymer, and the preferred density is o, soo.
~0.935 g/c 3, more preferably 0.111
5-0.930 gnats3. Also, preferred MFR
is 0, O1-5 g/IQ min, more preferably 0.05
~2.0 g/10 min. Examples of the α-olefin as a comonomer to be copolymerized include 1-olefins having about 3 to 20 carbon atoms, such as propylene, butene-1°pentene-1, hexene-1, 4-methylpentene-1, and octene-1. Preferred 1-olefins are 1-butene, 1-hexene, 4-methylpentene-1, and 1-octene. Ethylene and these alpha olefins (typical content is 3-1
The copolymer with 5 weight 2) can be produced by a gas phase method, a solution method, a slurry method, a high pressure method, etc. The ethylene/α-olefin copolymer also includes a blend of high-pressure polyethylene of 30% by weight or less. The formamidine compound used is represented by the general formula %, where R1 is an alkyl group, R2 is hydrogen,
hydroxyl group or alkoxy group, R5 is an alkyl group or phenyl group, R4 is hydrogen, hydroxyl group, alkoxy group or -
It is GOOR+. Such formamidine compounds are preferably N-(4-ethoxycarbonylphenyl)-N'-ethyl-N-7enylformamidine, N-(4-ethoxycarbonylphenyl)-N'-methyl-N" -(A-methoxyphenyl)formamidine, N,N'-bis(4
-ethoxycarbonylphenyl)-N'-methylformamidine, N-(4-butoxycarbonylphenyl)-
N-methyl-N'-methyl-N'-phenylformamidine, N-(3-methoxy-4-ethoxycarbonylphenyl)-N', N-diphenylformamidine, N
-(4-ethoxycarbonylphenyl)-N'-cutyl-N'-(4-methoxyphenyl)formamidine. The concentration of formamidine compound in polyethylene is 0.0
1-1% by weight, preferably 0.03-0.5% by weight2, more preferably 0.03-0.2% by weight. Less than 0.01% by weight has little effect, and 1% by weight
Even if the concentration is higher, the improvement effect will be saturated, so the concentration is restricted from an economical point of view. Furthermore, the carbon black used in the present invention may be any carbon black for coloring, reinforcing, etc.
Since the effect of the invention is remarkable, it is preferable that the product of the specific surface area and the electron spin density is lX1022 spin. m2/g27
g2 or less, particularly preferably 7 x 1021 spins, 21g
2 or less carbon black. Here, the measured value of the specific surface area of carbon black is a value determined by the BET method using nitrogen. Further, the electron spin density is a value determined by the following method. That is, the carbon black to be subjected to measurement is sandwiched between drug packaging paper and ground. Next, 10-40B of this crushed sample
After filling a glass tube with an inner diameter of 0.5 mm and reducing the pressure to 1 hmHg, an electron spin resonance spectrum (ESR spectrum) is measured. ESR spectrum is JEOL JE
Although the measurement was performed using an S-FEIX spectrometer, any method that can accurately measure the unpaired electron concentration may be used with a measuring device or
The measurement conditions are not limited. In the present invention, measurements were made in the range of 3300±2500 Gauss under the conditions of microwave power of 1 mW, modulation frequency of 100 Hertz, and modulation width of 8.3 Gauss. Sensitivity (Q) based on microwave absorption of the sample
The decrease in the Mn/MgO standard sample was corrected by comparing the spectral intensities of the Mn/MgO standard sample measured under constant conditions across all samples at the same time as the carbon black. The absorption area intensity was determined by integrating the first-order differential type ESR spectrum obtained by the above method twice in the range of 3300±2500 Gauss. The electron spin density is determined from the unpaired electron concentration under the same conditions as carbon black. As the carbon black used in the present invention, the carbon black having the specific surface area x electron spin density as described above may be appropriately selected from, for example, furnace black, thermal black, channel black, acetylene black, etc., regardless of its manufacturing method. However, in the case of materials other than acetylene black, in general, materials other than acetylene black are fired at a high temperature of about 800 to 1500°C to remove volatile components, and at the same time reduced with hydrogen etc. This is the so-called reduced carbon black, which is extracted by cooling in an inert gas atmosphere. Furthermore, these carbon blacks do not necessarily need to be used alone, but two or more types of carbon blacks may be mixed.This means that expensive acetylene black or reduced carbon black may be used with inexpensive carbon black, as long as the effects of the present invention are not impaired. This means that it can be mixed with black, so it has great industrial significance. The carbon black concentration in the ethylene/α-olefin copolymer in the present invention is 0.5 to 5% by weight2, preferably 0.
．． 5 to 3 weight 2 is selected as a practical range. Various known methods can be used to mix the formamidine compound and carbon black used in the present invention into the ethylene φα olefin copolymer. A method is used in which a highly concentrated masterbatch is first created using a roll, Banbury mixer, Negoo, twin-shaft mixer, etc., and then this is further diluted to create a final masterbatch, which is then mixed with virgin pellets during molding. . In addition to the above two essential components, antioxidants, neutralizing agents, antistatic agents, pigments, dispersants, etc. can be added to the ethylene/α-olefin copolymer composition used in the present invention. However, since some of these additives may adsorb halogen or react with halogen, reducing the sterilizing effect of halogen-containing water, the concentration of addition should be determined with care. Among these additives, the addition of antioxidants to # is desirable. Specifically, 2,6-di-t-butyl-
p-cresol, 1,1.3-)lis-(2-methyl-
4-hydroxy-3-t-butylphenyl)butane, tetrakis[methylene-5-(3°,5-di-t-butyl-4-hydroxyphenyl)propionate comethane,
4.4'-Thiobis-(6-t-butyl-m-cresol), 1,3.5-trimethyl-2,4,8-
) Lis-(3,5-di-t-butyl-4-hydroxybenzyl)benzene, n-tadecyl-β-(4-hydroxy-3°,5-di-t-butylphenyl)propionate, Tris-( 3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate, 4,4'-butylidene-bis(6-t-butyl-cresol),
1,3.5-tris-(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)incyanuric acid, 3
, 5-di-t-butyl-4-hydroxycyanuric acid and 1
．． Triester of 3.5-tris-(2-hydroxyethyl)-s-triazine-2,4,8(IH,3H,5H)-)ion (Product name: Good Right 3
125), bis-[3,3-bis-(4-hydroxy-
3'-t-butylphenyl)-butyric acid fuglycol ester, triethylene glycol-bis-(
3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate 1 and the like. The manufacture of tubes from the ethylene ψα olefin copolymer composition formulated according to the invention is carried out by conventional molding methods. That is, for example, the outer diameter is 24.5 mm, the gap is 3. Ei
A mixture of ethylene/α-olefin copolymer and carbon black was extruded from an aoiwm single-screw extruder with a straight die of mm at a resin temperature of 140 to 220°C, and cooled while controlling the diameter by plate sizing to obtain a nominal diameter of 13 mm.
Take out the pipe A (outer diameter 21.5a+m, inner diameter 14.5II11, wall thickness 3.5mm). As the guide to use,
It can be used with straight heads, cross heads, and offset soybeans, and for sizing, sizing plates, outside mandrels, sizing boxes, inside mandrels, etc. can be used. [Functions and Effects] In the water supply and drainage pipe of the present invention, a formamidine compound is added to the ethylene/α-olefin copolymer in addition to the conventionally blended carbon black. The problems of blistering and delamination caused by the process have been significantly improved. Note that the improvement effect can be further improved by selecting carbon black in which the product of its specific surface area and electron spin density is equal to or less than a certain value. [Example 1] In the following Examples and Comparative Examples, a water flow test to demonstrate the effects of the present invention was conducted in the following manner. That is, JIS-8
A length of 50 cm was cut from a pipe formed into a 13A vibe specified by 7f12, and this was set in a low concentration chlorine water flow test device. This device adjusts the chlorine concentration from 0.1 to
It can be precisely adjusted within the range of 100PP11, and the water pressure of this chlorine water is 1kg/cm2. Water can be passed through the pipe at a flow rate of 0.45 m3/hr. For a certain period of time↓lJ-,!
No/Yu, Ii Tsubu-~Un#-Ron--A-65-c
++58 1111 samples were taken, this sample was placed horizontally on a fixed plate, and a plate parallel to the fixed plate was pushed from above to compress and deform the sample to 70% of its diameter, and in this state the parallel plate was Move and rotate the sample while keeping the entire outer circumference in contact with the fixed plate. Repeat this rotation operation 20 times
The evaluation of blistering in the one-pass water test, which was conducted twice to evaluate the presence or absence of peeling of the inner layer of the pipe, was based on JIS-8782. Example 1 Linear polyethylene manufactured by Mitsubishi Yuka Co., Ltd. (Mitsubishi Polyethylene Iy 7)
-LL r M40FJ, MFR: 0.7g/1
0 minutes, density: Q, 922g/cra', butene-
N-(4-ztoxycarponylphenyl)-N-ethyl-N-2-enylformamidine (0.1% by weight 2), tetrakis [methylene-5-(
3',5'-di-t-butyl-4-hydroxyphenyl)propionate 1 methane 0.14i amount 2 is added,
It was granulated into pellets using a 40i+m extruder. On the other hand, the specific surface ax electron spin density is 1. l30X 1022 spins. Furnace carbon black with m2/g27g2. “Geest KH+ r city* 6J y i4.1FI
))-11 JnG nine rolls to prepare a masterbatch with a carbon black concentration of 25 weight 2, which was then mixed with the above composition and a final carbon black concentration of 2.5.
The mixture was mechanically mixed to a weight of 2 and put into the pipe forming machine described above to form a 13A pipe specified in JIS-8762. As a result of a water flow test with chlorinated water with a chlorine concentration of 50pp■,
No layer peeling was observed after 150 days of water passage. Further, the level of blistering at this time was grade 2. This evaluation result shows that the chlorine water resistance was significantly improved compared to the formamidine compound-free system of Comparative Example 1. Example 2 Specific surface area x electron spin density of carbon black is 2. O
An experiment similar to Example 1 was conducted using IX to 21 spin and 127 g2 acetylene black manufactured by Denki Kagaku Kogyo Co., Ltd. In the 50pP ■ chlorine concentration water flow test, the inner layer of the pipe did not peel off even after 150 days, and the blistering level was grade 1, indicating that it is very good. Comparative Example 1 When the formamidine compound in Example 1 was tested without being mild, the 50PP11 low-temperature water flow test result showed that approximately 65 JLm of layer peeling was observed after 80 days. The blistering level at this time was grade 6.

Claims (2)

[Claims] (1) A water supply and drainage pipe comprising an ethylene/α-olefin copolymer composition containing 0.5 to 5% by weight of carbon black and 0.01 to 1% by weight of a formamidine compound. (2) As carbon black, the product of specific surface area and electron spin density is 1×10^2^2 spin. m^2/g^2
Claim 1 using the following carbon black:
Water supply and drainage pipes as described in section.