CN110774701B - High density polyethylene pipe, joint and sealing material - Google Patents
High density polyethylene pipe, joint and sealing material Download PDFInfo
- Publication number
- CN110774701B CN110774701B CN201910663703.5A CN201910663703A CN110774701B CN 110774701 B CN110774701 B CN 110774701B CN 201910663703 A CN201910663703 A CN 201910663703A CN 110774701 B CN110774701 B CN 110774701B
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- Prior art keywords
- density polyethylene
- film
- gas barrier
- barrier film
- inner layer
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Links
- 229920001903 high density polyethylene Polymers 0.000 title claims abstract description 148
- 239000004700 high-density polyethylene Substances 0.000 title claims abstract description 148
- 239000003566 sealing material Substances 0.000 title claims abstract description 38
- 230000004888 barrier function Effects 0.000 claims abstract description 111
- 229920005989 resin Polymers 0.000 claims abstract description 86
- 239000011347 resin Substances 0.000 claims abstract description 86
- 229920000219 Ethylene vinyl alcohol Polymers 0.000 claims abstract description 40
- 229920001684 low density polyethylene Polymers 0.000 claims abstract description 35
- 239000004702 low-density polyethylene Substances 0.000 claims abstract description 35
- 238000002844 melting Methods 0.000 claims abstract description 13
- 230000008018 melting Effects 0.000 claims abstract description 12
- 239000010410 layer Substances 0.000 claims description 184
- 239000003921 oil Substances 0.000 claims description 103
- -1 polyethylene terephthalate Polymers 0.000 claims description 57
- 239000012530 fluid Substances 0.000 claims description 35
- 229920000092 linear low density polyethylene Polymers 0.000 claims description 35
- 239000004707 linear low-density polyethylene Substances 0.000 claims description 35
- 238000000034 method Methods 0.000 claims description 34
- 239000010779 crude oil Substances 0.000 claims description 24
- 150000004945 aromatic hydrocarbons Chemical class 0.000 claims description 18
- 238000004458 analytical method Methods 0.000 claims description 16
- 239000002344 surface layer Substances 0.000 claims description 16
- 230000003141 anti-fusion Effects 0.000 claims description 15
- 239000000155 melt Substances 0.000 claims description 14
- 239000005020 polyethylene terephthalate Substances 0.000 claims description 13
- 229920000139 polyethylene terephthalate Polymers 0.000 claims description 13
- 239000006229 carbon black Substances 0.000 claims description 9
- 125000003118 aryl group Chemical group 0.000 claims description 8
- 239000004962 Polyamide-imide Substances 0.000 claims description 5
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- 229920001721 polyimide Polymers 0.000 claims description 5
- 238000007670 refining Methods 0.000 claims description 2
- 230000005855 radiation Effects 0.000 abstract description 67
- 230000006866 deterioration Effects 0.000 abstract description 38
- 239000002313 adhesive film Substances 0.000 abstract description 20
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- 239000004698 Polyethylene Substances 0.000 description 43
- 229920000573 polyethylene Polymers 0.000 description 43
- 239000000463 material Substances 0.000 description 37
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- 229920013716 polyethylene resin Polymers 0.000 description 15
- 230000035882 stress Effects 0.000 description 15
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- 239000005977 Ethylene Substances 0.000 description 7
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- VXNZUUAINFGPBY-UHFFFAOYSA-N 1-Butene Chemical compound CCC=C VXNZUUAINFGPBY-UHFFFAOYSA-N 0.000 description 6
- LIKMAJRDDDTEIG-UHFFFAOYSA-N 1-hexene Chemical compound CCCCC=C LIKMAJRDDDTEIG-UHFFFAOYSA-N 0.000 description 6
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 6
- 229910000831 Steel Inorganic materials 0.000 description 6
- 238000001125 extrusion Methods 0.000 description 6
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- 239000010959 steel Substances 0.000 description 6
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- 239000012298 atmosphere Substances 0.000 description 5
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- 238000007254 oxidation reaction Methods 0.000 description 5
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- UFWIBTONFRDIAS-UHFFFAOYSA-N Naphthalene Chemical compound C1=CC=CC2=CC=CC=C21 UFWIBTONFRDIAS-UHFFFAOYSA-N 0.000 description 4
- 239000004699 Ultra-high molecular weight polyethylene Substances 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 4
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- 238000004132 cross linking Methods 0.000 description 4
- 230000001747 exhibiting effect Effects 0.000 description 4
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- 238000006116 polymerization reaction Methods 0.000 description 4
- 238000000746 purification Methods 0.000 description 4
- 238000004513 sizing Methods 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 238000009864 tensile test Methods 0.000 description 4
- 229920000785 ultra high molecular weight polyethylene Polymers 0.000 description 4
- 230000002087 whitening effect Effects 0.000 description 4
- 239000004952 Polyamide Substances 0.000 description 3
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- 230000007423 decrease Effects 0.000 description 3
- 230000004927 fusion Effects 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
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- 230000002706 hydrostatic effect Effects 0.000 description 3
- 230000033001 locomotion Effects 0.000 description 3
- 239000003758 nuclear fuel Substances 0.000 description 3
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- 229920002647 polyamide Polymers 0.000 description 3
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- 239000002994 raw material Substances 0.000 description 3
- 238000007127 saponification reaction Methods 0.000 description 3
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- KWKAKUADMBZCLK-UHFFFAOYSA-N 1-octene Chemical compound CCCCCCC=C KWKAKUADMBZCLK-UHFFFAOYSA-N 0.000 description 2
- 229920010126 Linear Low Density Polyethylene (LLDPE) Polymers 0.000 description 2
- 239000004642 Polyimide Substances 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- 238000003916 acid precipitation Methods 0.000 description 2
- 238000007259 addition reaction Methods 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 2
- 230000001070 adhesive effect Effects 0.000 description 2
- 150000001299 aldehydes Chemical class 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 239000000498 cooling water Substances 0.000 description 2
- 229920001577 copolymer Polymers 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 238000007323 disproportionation reaction Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 229920000620 organic polymer Polymers 0.000 description 2
- 238000006864 oxidative decomposition reaction Methods 0.000 description 2
- 239000011990 phillips catalyst Substances 0.000 description 2
- 229920000098 polyolefin Polymers 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
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- 238000007348 radical reaction Methods 0.000 description 2
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- 239000013535 sea water Substances 0.000 description 2
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- 238000000638 solvent extraction Methods 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- 229910052717 sulfur Inorganic materials 0.000 description 2
- 239000011593 sulfur Substances 0.000 description 2
- MSYRKNADCLYPAU-UHFFFAOYSA-N 1-propylfluoranthene Chemical compound C1=CC=C2C3=CC=CC=C3C3=C2C1=CC=C3CCC MSYRKNADCLYPAU-UHFFFAOYSA-N 0.000 description 1
- 239000004593 Epoxy Substances 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 229920002292 Nylon 6 Polymers 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- OUUQCZGPVNCOIJ-UHFFFAOYSA-M Superoxide Chemical compound [O-][O] OUUQCZGPVNCOIJ-UHFFFAOYSA-M 0.000 description 1
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 1
- XTXRWKRVRITETP-UHFFFAOYSA-N Vinyl acetate Chemical compound CC(=O)OC=C XTXRWKRVRITETP-UHFFFAOYSA-N 0.000 description 1
- 239000006230 acetylene black Substances 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000012790 adhesive layer Substances 0.000 description 1
- 239000003963 antioxidant agent Substances 0.000 description 1
- 230000003078 antioxidant effect Effects 0.000 description 1
- 239000010692 aromatic oil Substances 0.000 description 1
- 238000006701 autoxidation reaction Methods 0.000 description 1
- 239000002199 base oil Substances 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000003139 buffering effect Effects 0.000 description 1
- 150000001732 carboxylic acid derivatives Chemical class 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000006231 channel black Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 238000003776 cleavage reaction Methods 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 239000013256 coordination polymer Substances 0.000 description 1
- 229920003020 cross-linked polyethylene Polymers 0.000 description 1
- 239000004703 cross-linked polyethylene Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 125000000753 cycloalkyl group Chemical group 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000012217 deletion Methods 0.000 description 1
- 230000037430 deletion Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- 239000006232 furnace black Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
- 239000012760 heat stabilizer Substances 0.000 description 1
- 239000012943 hotmelt Substances 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000012844 infrared spectroscopy analysis Methods 0.000 description 1
- 239000003112 inhibitor Substances 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000005304 joining Methods 0.000 description 1
- 150000002576 ketones Chemical class 0.000 description 1
- 150000002596 lactones Chemical class 0.000 description 1
- 238000010030 laminating Methods 0.000 description 1
- 238000003475 lamination Methods 0.000 description 1
- 239000002346 layers by function Substances 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 229920001179 medium density polyethylene Polymers 0.000 description 1
- 239000004701 medium-density polyethylene Substances 0.000 description 1
- 239000012968 metallocene catalyst Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- TVMXDCGIABBOFY-UHFFFAOYSA-N n-Octanol Natural products CCCCCCCC TVMXDCGIABBOFY-UHFFFAOYSA-N 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 229920001200 poly(ethylene-vinyl acetate) Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000001902 propagating effect Effects 0.000 description 1
- 239000002296 pyrolytic carbon Substances 0.000 description 1
- 230000002285 radioactive effect Effects 0.000 description 1
- 230000006798 recombination Effects 0.000 description 1
- 238000005215 recombination Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 230000007017 scission Effects 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
- 239000011800 void material Substances 0.000 description 1
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B1/00—Layered products having a non-planar shape
- B32B1/08—Tubular products
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
- B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
- B32B27/20—Layered products comprising a layer of synthetic resin characterised by the use of special additives using fillers, pigments, thixotroping agents
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
- B32B27/306—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising vinyl acetate or vinyl alcohol (co)polymers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/36—Layered products comprising a layer of synthetic resin comprising polyesters
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
- B32B7/03—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers with respect to the orientation of features
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
- B32B7/04—Interconnection of layers
- B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L11/00—Hoses, i.e. flexible pipes
- F16L11/04—Hoses, i.e. flexible pipes made of rubber or flexible plastics
- F16L11/12—Hoses, i.e. flexible pipes made of rubber or flexible plastics with arrangements for particular purposes, e.g. specially profiled, with protecting layer, heated, electrically conducting
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L21/00—Joints with sleeve or socket
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L47/00—Connecting arrangements or other fittings specially adapted to be made of plastics or to be used with pipes made of plastics
- F16L47/06—Connecting arrangements or other fittings specially adapted to be made of plastics or to be used with pipes made of plastics with sleeve or socket formed by or in the pipe end
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L9/00—Rigid pipes
- F16L9/12—Rigid pipes of plastics with or without reinforcement
- F16L9/123—Rigid pipes of plastics with or without reinforcement with four layers
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21D—NUCLEAR POWER PLANT
- G21D1/00—Details of nuclear power plant
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2307/00—Properties of the layers or laminate
- B32B2307/70—Other properties
- B32B2307/71—Resistive to light or to UV
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2581/00—Seals; Sealing equipment; Gaskets
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2597/00—Tubular articles, e.g. hoses, pipes
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Plasma & Fusion (AREA)
- High Energy & Nuclear Physics (AREA)
- Laminated Bodies (AREA)
- Rigid Pipes And Flexible Pipes (AREA)
- Coating Of Shaped Articles Made Of Macromolecular Substances (AREA)
Abstract
The present invention relates to high density polyethylene pipes, joints and sealing materials. Specifically, [ problem ]]The invention provides a high-density polyethylene pipe, a joint and a sealing material which can inhibit the deterioration caused by external factors such as radiation. [ means for solving problems]The high-density polyethylene pipe (10), joint, and sealing material of the present invention are provided with: with a density of 0.940g/cm3Above 0.980g/cm3An inner layer (1) mainly composed of the following high-density polyethylene, a gas barrier film (2) containing an ethylene-vinyl alcohol copolymer resin and covering the outer surface of the inner layer (1), an anti-melt adhesive film (3) containing a resin having a melting point of 150 ℃ or higher and covering the outer surface of the gas barrier film (2), and a resin having a density of 0.910g/cm and covering the outer surface of the anti-melt adhesive film (3)3Above 0.930g/cm3The outer layer (4) mainly composed of low-density polyethylene.
Description
Technical Field
The present invention relates to a high-density polyethylene pipe, a joint, and a sealing material used for nuclear power plants and the like.
Background
The pipeline for nuclear power plant laid in a nuclear power-related facility is required to have a performance capable of safely carrying out the transport of a fluid containing a radioactive substance for a long period of time and the transport of the fluid at a high radiation dose. Conventionally, steel pipes have been used as pipelines for nuclear power plants. However, since many man-hours and machines are required for construction of nuclear facilities that are subject to space and time constraints, steel pipes cannot be said to be optimal. In this case, replacement with resin pipes is being performed in which movement and processing are easy, and joining between pipes and joints is also easy.
As a resin pipe, use of a high-density polyethylene pipe used as a long-distance pipe for a water pipe has been studied. However, high density polyethylene pipes have a disadvantage that they are inferior to steel pipes in radiation resistance and are likely to be brittle at high radiation doses. When a high-density polyethylene pipe deteriorates and a minute defect is generated in the resin, stress is concentrated at the defect portion and a fracture or a crack is generated when pressure from a fluid inside the pipe, earth pressure from the outside of the pipe, or the like is applied.
The deterioration of polyethylene progresses due to autoxidation mainly involving radicals, and the deterioration of polyethylene is promoted not only by the action of radiation but also by ultraviolet rays and oxygen. In the case where the fluid conveyed through the high-density polyethylene pipe contains a radioactive substance or has a possibility of being irradiated, it is important that no leakage event occurs, and therefore, it is necessary to take measures to prevent deterioration due to external factors such as radiation, oxygen, and ultraviolet rays.
For example, patent document 1 describes a technique of adding 1 to 7 parts by mass of a hydrogenated aromatic deterioration inhibitor or propylfluoranthene to high-density polyethylene.
Documents of the prior art
Patent document
Patent document 1: japanese laid-open patent publication No. 2017-020628
Patent document 2: japanese laid-open patent publication No. 2017-101688
Disclosure of Invention
Problems to be solved by the invention
When a deterioration preventing agent is added to high-density polyethylene as in patent document 1, or when tie molecules are reinforced with a crosslinked structure as in patent document 2, the radiation resistance of the high-density polyethylene pipe can be improved. Further, when the high density polyethylene pipe has a double pipe structure, it is difficult for ultraviolet rays and oxygen in the atmosphere to reach the inside, and therefore, the pipe integrity can be maintained for a certain period of time even outdoors or the like with a high radiation dose.
However, these high-density polyethylene pipes have a durability life of 40 years or more, and cannot be said to have sufficient durability as compared with steel pipes which do not need to be replaced in a short period of time. High density polyethylene, while having the compressive strength and hardness required for pipes, has the essential disadvantage of lacking ductility and being susceptible to brittle fracture when used continuously at high radiation doses. Radical reactions that degrade resins are easily initiated by radiation and are promoted by external factors such as oxygen and ultraviolet rays, and therefore, a high level of measures for preventing these factors are required.
Further, sealing materials such as high-density polyethylene pipe joints, gaskets, and circular rings used together with high-density polyethylene pipes are sometimes exposed to external factors such as ultraviolet rays, and countermeasures are also required. As a material of the sealing material, there are Ultra High Molecular Weight Polyethylene (UHPE) and the like, and long-term sealing of not only a piping material but also a radioactive solution in nuclear fuel facilities and the like is expected.
Accordingly, an object of the present invention is to provide a high-density polyethylene pipe, a joint, and a sealing material which can suppress deterioration due to external factors such as radiation.
In order to solve the above problems, a high density polyethylene pipe according to the present invention includes: with a density of 0.940g/cm3Above 0.980g/cm3An inner layer mainly composed of the following high-density polyethylene, a gas barrier film containing an ethylene-vinyl alcohol copolymer resin and covering the outer surface of the inner layer, a melt-resistant adhesive film (heat-resistant adhesive film) containing a resin having a melting point of 150 ℃ or higher and covering the outer surface of the gas barrier film, and a resin having a density of 0.910g/cm and covering the outer surface of the melt-resistant adhesive film3Above 0.930g/cm3The outer layer mainly composed of the following low-density polyethylene.
The joint and the sealing material of the present invention have the same layer structure as the high density polyethylene pipe.
Effects of the invention
According to the present invention, it is possible to provide a high-density polyethylene pipe, a joint, and a sealing material which can suppress deterioration due to external factors such as radiation.
Drawings
FIG. 1 is a sectional view schematically showing a high density polyethylene pipe of the present invention.
FIG. 2 is a perspective view schematically showing a high-density polyethylene pipe of the present invention.
FIG. 3 is a graph showing the relationship between% CN of oil used as an additive and elongation at break.
FIG. 4 is a graph showing the relationship between% CA of an oil used as an additive and elongation at break.
FIG. 5 is a graph showing the relationship between MFR and elongation at break of linear low density polyethylene used for a gas barrier film.
Fig. 6 is a graph showing the relationship between the total thickness of the gas barrier film and the elongation at break.
FIG. 7 is a graph showing the relationship between the thickness of an ethylene-vinyl alcohol copolymer resin used for a gas barrier film and the elongation at break.
FIG. 8 is a graph showing the relationship between the thickness of a fusion-bond preventing film (fusion-bond preventing film) and the elongation at break.
FIG. 9 is a graph showing the relationship between the thickness of the protective layer (outer layer) and the elongation at break.
Detailed Description
Hereinafter, a high-density polyethylene pipe, a joint, and a sealing material according to an embodiment of the present invention will be described with reference to the drawings.
Fig. 1 is a cross-sectional view schematically showing a high-density polyethylene pipe of the present invention. Fig. 2 is a perspective view schematically showing the high-density polyethylene pipe of the present invention. In fig. 2, the inside of the pipe body is exposed to show the layer structure of the high density polyethylene pipe.
As shown in fig. 1 and 2, the high-density polyethylene pipe 10 of the present embodiment includes: the pipe comprises a cylindrical inner layer 1 forming a pipe, a gas barrier film 2 covering the outer surface of the inner layer 1, an anti-melt adhesive film 3 covering the outer surface of the gas barrier film 2, and an outer layer 4 serving as a protective layer covering the outer surface of the anti-melt adhesive film 3.
The high-density polyethylene pipe 10 is mainly used as a fluid transport pipe for transporting fluid between machines and facilities. The high-density polyethylene pipe 10 has excellent radiation resistance and suppresses deterioration of the high-density polyethylene pipe (inner layer 1) due to external factors such as radiation, oxygen, and ultraviolet rays, and is therefore particularly suitable for use in the transport of fluids containing high-concentration radioactive substances and the transport of fluids at high radiation doses.
In order to fundamentally improve the intrinsic defect that high density polyethylene has that it is easily brittle-broken when continuously used at a high radiation dose, the high density polyethylene pipe 10 is a multilayer pipe in which the outside of a conduit (inner layer 1) through which a fluid flows is covered with a gas barrier film 2 and a protective layer (outer layer 4) for improving weather resistance. In resin molding into the protective layer (outer layer 4), the gas barrier film 2 and the protective layer (outer layer 4) are provided with a layer structure in which the fusion-bonding preventing film 3 is interposed therebetween so as not to cause cracking of the gas barrier film 2.
The density of the inner layer 1 is 0.940g/cm3Above 0.980g/cm3The following High Density Polyethylene (HDPE) was used as a main component. Since high-density polyethylene has low brittleness although it has high tensile strength and impact resistance, the inner layer 1 mainly composed of high-density polyethylene provides the compressive strength and hardness required for pipes.
The high-density polyethylene may contain 1-butene, 1-hexene, and the like as monomers in addition to ethylene, as long as the physical properties such as density are not impaired. The density of the high-density polyethylene is preferably 0.940g/cm3Above 0.970g/cm3Hereinafter, more preferably 0.945g/cm3Above 0.965g/cm3The following.
The high-density polyethylene can be obtained by polymerization using any of ziegler catalyst, metallocene catalyst, phillips catalyst, and the like. The high-density polyethylene may be a mixed material blended with another resin or a recycled material obtained by recycling a polyethylene product as a raw material. The high-density polyethylene may further contain other resins such as polypropylene as long as it is in a range of less than 50% by mass.
As a heightThe density polyethylene may be used, for example, at a reaction pressure of 5kgf/cm2Above 200kgf/cm2And a resin polymerized at a reaction temperature of 60 ℃ to 100 ℃ inclusive. Further, a resin having a Melt Flow Rate (MFR) determined in accordance with ISO1133 of 0.1g/10 min to 3.0g/10 min, more preferably 0.2g/10 min to 0.5g/10 min under the conditions of a test temperature of 190 ℃ and a test load of 5.0kgf (49.03N) can be used. However, the high-density polyethylene constituting the inner layer 1 is not limited to the resin exhibiting such physical properties.
In the inner layer 1, usual additives such as an antioxidant and a heat stabilizer may be added to the base material mainly composed of the high-density polyethylene, or usual additives may not be added. In fig. 1 and 2, the shape of the inner layer 1 is a cylindrical shape, but the dimensions of the inner layer 1, such as ovality, cross-sectional shape, longitudinal shape, inner and outer diameters, and wall thickness, are not particularly limited.
The inner layer 1 preferably contains at least one of an oil containing naphthenes produced during crude oil purification and an oil containing aromatic hydrocarbons produced during crude oil purification in a base material mainly composed of high-density polyethylene. When these oils are blended, the sliding property of the polyethylene molecules is improved as described later, and the deterioration of the high density polyethylene due to the breakage of the fine grains is suppressed.
The oil containing naphthenes may be an oil obtained by purifying a naphthene-based crude oil as a raw material. For example, there can be used an oil obtained by distilling a naphthenic crude oil under reduced pressure and removing an oil containing aromatic components by solvent extraction. In addition to solvent extraction, oil purified by adsorption treatment, clay treatment, deacidification treatment, or the like may be used. Here, cycloalkane means a compound represented by the general formula: cnH2nCyclic hydrocarbons are shown.
As the aromatic hydrocarbon-containing oil, a paraffinic crude oil and/or a naphthenic crude oil may be blended as a raw material, and these oils may be purified. For example, residual oil having a high specific gravity and a high viscosity, which is produced in the purification process of paraffinic crude oil or naphthenic crude oil, can be used. For the purpose of explanation,aromatic hydrocarbons refer to the general formula: cnH2n-6The aromatic hydrocarbon represented, that is, an unsaturated cyclic hydrocarbon having a conjugated double bond.
The oil containing naphthenes is preferably an oil having a% CN of 10% to 100% in a ring analysis measured by an n-d-M method, more preferably an oil having a% CN of 10% to 80%, and still more preferably an oil having a% CN of 20% to 60%, among oils produced when a naphthene-based crude oil is purified. When the% CN is about 20% or more and about 60% or less, a high effect of suppressing deterioration of the high density polyethylene is obtained.
Among oils produced when refining paraffinic crude oils or naphthenic crude oils, the aromatic-containing oils preferably have a% CA of 5% to 100%, more preferably have a% CA of 5% to 60%, and still more preferably have a% CA of 5% to 40%, as measured by the n-d-M method. When the% CA is about 5% to about 40%, a high effect of suppressing deterioration of the high density polyethylene is obtained.
Further, as the oils containing naphthenes and aromatics, for example, oils having a% CN of ring analysis measured by n-d-M method of 20% to 60% and a% CA of ring analysis measured by n-d-M method of 5% to 40% among oils produced when crude oil is refined can be used as additives.
The n-D-M method is a method of structure-based analysis of oils (Ring analysis method) according to ASTM D3238-85, and is generally used for compositional analysis of base oils. Based on the density d20 of the oil at 20 ℃, the refractive index nD20 of the oil at 20 ℃ and the average molecular weight data of the oil, the mass ratio of paraffinic carbons to the total carbon amount (% CP), the mass ratio of naphthenic carbons to the total carbon amount (% CN), the mass ratio of aromatic carbons to the total carbon amount (% CA), the average number of naphthenic rings per molecule (RN), and the average number of aromatic rings per molecule (RA) were determined by the n-d-M method.
The gas barrier film 2 is formed of a resin film containing at least ethylene-vinyl alcohol copolymer resin (EVOH). According to the gas barrier film 2 containing an ethylene-vinyl alcohol copolymer resin, oxygen in the outside air is shielded, and oxidative deterioration of the high-density polyethylene of the inner layer 1 is suppressed.
Typically, the high density polyethylene has an oxygen permeability coefficient of about 0.4X 10-10cm3(STP)·cm/(cm2s-cmHg), the oxygen permeability coefficient of the low density polyethylene is about 6.9X 10-10cm3(STP)·cm/(cm2S · cmHg). In contrast, the oxygen permeability coefficient of the ethylene-vinyl alcohol copolymer resin is as small as about 0.0001X 10-10cm3(STP)·cm/(cm2S cmHg), the oxygen permeation can be suppressed to 1/4000 for high density polyethylene and 1/67000 for low density polyethylene.
The gas barrier film 2 may be formed of a single layer containing an ethylene-vinyl alcohol copolymer resin, or may be formed of a plurality of layers including a layer containing an ethylene-vinyl alcohol copolymer resin.
The average polymerization degree, ethylene content and saponification degree of the ethylene-vinyl alcohol copolymer resin are not particularly limited. For example, the average polymerization degree may be 500 to 3000. The ethylene content may be, for example, 20% to 80%. The ethylene content is preferably 25% or more from the viewpoint of improving flexibility and water resistance. The saponification degree may be, for example, 85% to 99%. From the viewpoint of ensuring gas barrier properties, the saponification degree is preferably 90% or more, and more preferably 95% or more.
The thickness of the ethylene-vinyl alcohol copolymer resin is preferably 0.5 μm or more, more preferably 1 μm or more, and still more preferably 5 μm or more. Further, it is preferably 60 μm or less, more preferably 50 μm or less, and further preferably 30 μm or less. When the thickness of the ethylene-vinyl alcohol copolymer resin is 0.5 μm or more, excellent gas barrier properties can be obtained as the thickness is larger, and oxidative deterioration of the resin of the inner layer 1 can be suppressed. Further, since pinholes are less likely to occur, it is easy to ensure gas impermeability satisfactorily. When the thickness is 5 μm or more and 50 μm or less, particularly high radiation resistance is obtained by the neutron shielding ability of the resin itself. On the other hand, when the thickness is 60 μm or less, the gas barrier film 2 is less likely to be broken when the high-density polyethylene pipe 10 is constructed, moved, or the like because it has flexibility as it is thinner.
The ethylene-vinyl alcohol copolymer resin may be a mixed material blended with other resins. Examples of the other resins to be blended include ethylene-vinyl acetate copolymers, ethylene-propylene copolymers, polyolefins, modified polyolefins, polyamides, and polyesters. The ethylene-vinyl alcohol copolymer resin may be a resin modified with an epoxy compound or the like, or may be a copolymer containing a monomer other than ethylene and vinyl acetate.
As shown in fig. 1 and 2, the gas barrier film 2 is preferably a multilayer film including an intermediate layer 22 containing an ethylene-vinyl alcohol copolymer resin and surface layers (21, 23) laminated on both sides of the intermediate layer 22. In fig. 1 and 2, the surface layers (21, 23) include an inner layer 21 disposed inside the intermediate layer 22 and an outer layer 23 disposed outside the intermediate layer 22, but the number of layers stacked on both surfaces of the intermediate layer 22 is not particularly limited.
The surface layers (21, 23) preferably contain at least one of Low Density Polyethylene (LDPE) and Linear Low Density Polyethylene (LLDPE). These polyethylenes can be coextruded with ethylene-vinyl alcohol copolymer resins. Further, according to the polyethylene, since a high neutron shielding ability can be obtained by the resin itself, radiation deterioration of the resin of the inner layer 1 can be suppressed.
In particular, when the surface layers (21, 23) are formed of low-density polyethylene, a multilayer film having high flexibility, impact resistance, cold resistance, moisture resistance and the like can be formed with high precision. Further, external pressure, impact, and the like applied to the high-density polyethylene pipe 10 can be alleviated, and damage of the inner layer 1, peeling, falling, and the like of the gas barrier film 2 can be prevented. Here, the low density polyethylene means a density of 0.910g/cm3Above 0.930g/cm3The following polyethylenes. The low density polyethylene may contain 1-butene, 1-hexene, and the like as monomers in addition to ethylene.
When the surface layers (21, 23) are formed of linear low-density polyethylene, higher tensile rupture strength, adhesiveness, cold resistance, and the like can be obtained than when the surface layers are formed of low-density polyethylene. Is described in detailThe linear low-density polyethylene means a polyethylene having a density of 0.910g/cm3Above 0.925g/cm3Hereinafter, the content of the monomer having a branched chain is a few%. The linear low-density polyethylene may contain 1-butene, 1-hexene, 1-octene, and the like as monomers in addition to ethylene. The linear low-density polyethylene can be polymerized by using any catalyst such as a ziegler catalyst or a phillips catalyst.
The melt index (MFR, melt flow rate) of the low-density polyethylene and the linear low-density polyethylene forming the surface layers (21, 23) is preferably 0.5g/10 min or more, as determined in accordance with ISO 1133. Further, it is preferably 50g/10 min or less, more preferably 20g/10 min or less, further preferably 10g/10 min or less, and particularly preferably 5g/10 min or less. It is known that the molecular weight of a resin has a correlation with MFR. When polyethylene exhibiting such MFR is used, the amount of low molecular weight components is small, and therefore high neutron shielding ability can be obtained by the resin itself.
The surface layers (21, 23) may be formed by laminating other resins as long as the layers containing low-density polyethylene or linear low-density polyethylene are provided on both sides of the intermediate layer 22. For example, from the viewpoint of toughening the multilayer film, the multilayer structure may be one containing Polyamide (PA) such as nylon 6 and Polyester (PE) such as polyethylene terephthalate.
Specific examples of the multilayer film include, but are not limited to, LDPE/EVOH/LDPE, LLDPE/EVOH/LLDPE, and the like. In view of improving the radiation resistance, it is preferable to exclude a low molecular weight component from the low density polyethylene and the linear low density polyethylene. Between the intermediate layer 22 and the surface layers (21, 23), another layer such as an adhesive layer may be provided as necessary.
The thickness of the multilayer film is preferably 20 μm to 200 μm. When the thickness is 20 μm or more, the greater the durability, the more the high density polyethylene pipe 10 is thick, and therefore, when it is laid in an excessively harsh environment where external force is easily applied, such as when it is used for construction, transportation, or the like, or outdoors, the gas barrier property can be satisfactorily ensured. Further, when the thickness is 200 μm or less, the thinner the film, the less flexibility is lost, so that the handling property and the winding property to the catheter (inner layer 1) are good, and the breakage of the film at the time of handling is reduced.
The total thickness of the gas barrier film 2 when wound on the outer periphery of the inner layer 1 is preferably 20 μm or more, and more preferably 50 μm or more. Further, it is preferably 500 μm or less, more preferably 400 μm or less, and further preferably 300 μm or less. When the total thickness is 20 μm or more, the greater the thickness, the higher the gas barrier property can be obtained, and therefore, the oxidative degradation of the resin of the inner layer 1 can be reliably suppressed. In addition, when the total thickness is 50 μm or more and 400 μm or less, particularly high radiation resistance can be obtained. On the other hand, when the total thickness is 500 μm or less, the thinner the film, the lower the material cost of the gas barrier film 2 and the labor for winding the film.
The gas barrier film 2 and the inner layer 1 may be fusion-bonded to each other or bonded by an adhesive, an adhesive material, or the like, but is preferably not fusion-bonded or bonded to the inner layer 1. When the inner layer 1 and the gas barrier film 2 are surface-joined by fusion bonding or adhesion, when a force is applied in the longitudinal direction or the radial direction of the pipe, stress is generated in opposite directions in the inner layer 1 and the gas barrier film 2 having different elongations, respectively, and thus the probability of occurrence of stress cracking or breakage increases. The gas barrier film 2 may contain an oil containing naphthene or an oil containing aromatic hydrocarbon, similarly to the inner layer 1.
Here, the action and effect of the oil and the gas barrier film 2 added to the inner layer 1 of the high-density polyethylene pipe 10 will be specifically described.
Polyethylene pipes are lighter in weight than steel pipes and are easy to move and process, and thus are widely used as long-distance pipes for water pipes and the like. However, unlike steel pipes, polyethylene pipes are made of organic polymers mainly composed of carbon and hydrogen. Polyethylene tends to undergo a brittle fracture when internal pressure, external pressure, impact, or the like is applied to a pipe, damage is caused to the pipe, or the pipe is exposed to a chemical substance, because deterioration progresses due to external factors such as radiation, ultraviolet rays, and heat, and elasticity, stress environment cracking resistance, impact resistance, and the like are reduced.
It is known that, in the case of an organic polymer, a molecule is excited by radiation, ultraviolet rays, heat, or the like, and bonds in the molecule are broken and decomposed. For example, when radiation or the like acts on polyethylene, hydrogen radicals (H) and hydrocarbon radicals (R) are generated. The reactivity of the radicals is high, and the radicals are bonded to each other (re-bonding), or the radicals are introduced to generate another radical (initiation reaction), or the radicals are added to a double bond (addition reaction), or a molecular chain is cut while the radicals are bonded to each other (disproportionation reaction).
The recombination and addition reactions of free radicals bring about an increase in the molecular weight called crosslinking, and the disproportionation reactions bring about a decrease in the molecular weight called disintegration. In a polyethylene pipe, when molecular chains are crosslinked and disintegrated, resistance to impact and bending is reduced, and physical properties such as brittleness of the pipe body are changed. As described above, when embrittlement of the pipe body progresses, the following problems occur when internal pressure, external pressure, impact, load, and the like are applied: stress cracking or creep rupture such as cracking or cracking, or cracking or brittle cracking in the pipe wall, or cracking of the pipe body, etc. are likely to occur.
As a pipe material such as a polyethylene pipe for water distribution, high-density polyethylene having been subjected to high performance by multi-stage polymerization or by an improved catalyst can be used. For such high density polyethylene, long term hydrostatic strength and environmental stress crack resistance can be improved by increasing the high molecular weight region, increasing the tie molecules connecting between the crystalline structures.
In general, it is known that the crystalline region is not easily affected even in an excessively severe environment, and the amorphous region is increasingly subjected to cleavage of tie molecules in an excessively severe environment. It is considered that if the tie molecules are cut, stress concentration is likely to occur in the resin when an external force is applied, and the long-term hydrostatic strength, environmental stress cracking resistance, and impact resistance are lowered.
In particular, in an atmosphere in which oxygen is present, it is known that propagation reaction (chain reaction) of oxidation proceeds by radicals. Initially, as in reaction formula (1), a hydrocarbon radical (R.cndot.) is reacted with oxygen (O)2) The reaction produces peroxygenated radicals (ROO.).
[ solution 1]
R·+O2→ROO·…(1)
The peroxygen radical (ROO. cndot.) is reactive, and as shown in the reaction formula (2), hydrogen (H) is extracted from other molecules (RH) to generate a peroxide (ROOH) and a new hydrocarbon radical (R. cndot.).
[ solution 2]
ROO·+RH→ROOH+R·…(2)
The newly formed hydrocarbon radical (R.cndot.) then forms another peroxidic radical (ROO.cndot.) according to equation (1), which forms another peroxide (ROOH) according to equation (2). The peroxide (ROOH) is unstable, and thus, as in the reaction formulas (3) to (5), a new oxygen radical (RO.), a peroxide radical (ROO.), and the like are generated.
[ solution 3]
ROOH→RO·+·OH…(3)
[ solution 4]
2ROOH→ROO·+RO·+H2O…(4)
[ solution 5]
RO·+RH→ROH+R·…(5)
In the atmosphere in the presence of oxygen, by such a propagating reaction of oxidation, the originally produced hydrocarbon radicals (R ·) propagate in large numbers into new radicals, and crosslinking and disintegration of the molecular chains progress. Therefore, deterioration of the resin is accelerated, and stress cracking and creep rupture are easily generated.
In addition, ozone is sometimes generated by radiation or ultraviolet rays in the atmosphere in which oxygen exists. Ozone has high reactivity with polyethylene having a double bond, and ozonides are produced by reaction with polyethylene. Since ozonides are unstable, the O-O bond is broken to produce aldehydes, ketones, esters, lactones, peroxides, and the like. It is known that molecular decomposition caused by such a reaction forms minute cracks (ozone cracks) in the resin.
In particular, when a fluid pressure, an earth pressure, or the like of about 1MPa or more is applied to a polyethylene pipe, the molecular chains tend to be stretched, so that the permeability of ozone is high and stress tends to concentrate on a specific site. In this case, the possibility of the occurrence of ozone cracks and the possibility of fracture starting from ozone cracks are increased.
In addition, polyethylene pipes are sometimes used for the transport of high temperature fluids. The various reactions that cause the decomposition of molecules are also related to molecular motion, i.e., the vibration and collision probability of the molecules. The more vigorous the molecular motion is at high temperature, and therefore, when polyethylene is exposed to high temperature, crosslinking and disintegration of molecular chains are accelerated, and deterioration of resin remarkably proceeds.
In particular, in a system involving an oxidation reaction, since the thickness of an oxide layer, the diffusion rate of oxygen, and the reaction rate of oxidative decomposition are affected by temperature, the oxidative decomposition of molecules is accelerated. Generally, the reaction rate is 2 times when the temperature is increased by 10 ℃. Therefore, in the case of using a polyethylene pipe for the transportation of a fluid at a high temperature, etc., when polyethylene is exposed to a high temperature, oxidative deterioration is accelerated, crosslinking and disintegration of molecular chains proceed, and deterioration of the resin becomes remarkable.
Such degradation of polyethylene by radiation, ultraviolet rays, heat, or the like deteriorates various properties such as elastic modulus, tensile strength, elongation, and the like, and deteriorates stress environment cracking resistance, impact resistance, and the like. In an excessively severe environment such as a radiation environment, an ultraviolet environment, a high-temperature environment, or the like, when a polyethylene pipe, a joint, or the like is continuously used, problems such as stress cracking, creep rupture, generation of undesirable phenomena such as cracking, or breakage of a pipe body, and fluid leakage are caused when internal pressure, external pressure, impact, or the like is applied, or when the pipe, the joint, or the like is exposed to a chemical substance.
On the other hand, when the inner layer 1 of the high density polyethylene pipe 10 is covered with the gas barrier film 2, the permeation of oxygen is inhibited, and the propagation reaction of oxidation is suppressed, so that the oxidative degradation of the resin of the inner layer 1 can be suppressed even at a high dose of radiation. When oil containing naphthene or oil containing aromatic hydrocarbon is blended in the inner layer 1, radicals generated by the action of radiation or ultraviolet rays can be trapped by the oil component.
In general, polyethylene has a characteristic that cracks, fissures, and the like are generated by various external factors such as radiation, ultraviolet rays, and heat, and the elongation is reduced and whitening occurs on the fracture surface in any fracture mode, although the polyethylene varies depending on the kind of the external factor. Whitening or cracking occurs on the fractured surface, and voids and fibrils exist. Whitening is a phenomenon caused by mie scattering of light due to void formation. Whitening indicates the occurrence of a form of damage consisting of voids and fibrils, i.e., a fine line break.
In general, it is known that the breakage of polyethylene by drawing proceeds in the following order of (a) to (D).
(A) Local area propagation of strain occurring just after tensile yield
(B) Propagation of fine-line fracture zone
(C) In the concentrated part of the fine grain breakage, molecular chain cutting and cracking occur
(D) Polymer fracture
In addition, for the crystal level, it is known that the change as described below is produced by stretching.
(a) Cracking of crystals at molecular level (molecular chain peeling)
(b) Bulk breaking of crystals (molecular chain peeling)
(c) Sliding rotation of molecules within a crystal (small variation)
Wherein in (a) and (b), the crystalline region is destroyed and the amorphous region is increased. In addition, the molecular chains are peeled off from the crystal region to form voids and fibrils, which cause fine line breakage. However, in (c), the crystal region is less damaged, and the amorphous region is hardly increased.
The amorphous region increased by this mechanism becomes a starting point of fracture typified by stress cracking. The following is therefore desirable: the formation of voids and fibrils, and the occurrence of fine crack are prevented as much as possible, and brittle crack and creep crack do not occur when pressure from a fluid inside the pipe, and/or earth pressure from outside the pipe, or the like is applied.
On the other hand, when the oil containing cycloalkane and/or the oil containing aromatic hydrocarbon is blended in the inner layer 1 of the high-density polyethylene pipe 10, the slidability of molecules present in the polyethylene crystal can be greatly improved. By converting the change in the crystal level into sliding rotation of molecules within the crystal, formation of voids and fibrils and fine grain fracture can be reduced, and the amorphous region is less likely to be enlarged, so brittle fracture and creep fracture caused by deterioration of high density polyethylene can be reduced.
Furthermore, oils containing naphthenes have SP values similar to those of polyethylene and are well compatible with polyethylene. When oil containing cycloalkane is added to the inner layer 1 of the high-density polyethylene tube 10, the oil penetrates into the fine parts of the molecules in the crystal, and the sliding properties of the molecules in the crystal can be greatly improved. Therefore, it is possible to suppress the cracking of the crystal at the molecular level and the bulk cracking of the crystal, while easily causing the sliding rotation of the molecules within the crystal.
In addition, oils containing naphthenes also exhibit fluidity at low temperatures close to normal temperatures. In general, a high-molecular material is likely to cause low-temperature embrittlement, and high-density polyethylene has a disadvantage of low impact resistance at low temperatures, and therefore it is important that sliding rotation of molecules is likely to occur in crystals and in the periphery of tie molecules. When oil containing cycloalkane is added to the inner layer 1 of the high-density polyethylene pipe 10, the oil penetrating into the crystal and around the tie molecules retains high fluidity even at low temperatures, and sliding rotation of the molecules in the crystal is easily caused, so that resistance to low-temperature embrittlement and impact resistance at low temperatures can be improved.
On the other hand, aromatic hydrocarbon-containing oils are characterized by high viscosity index and low tendency to bleed out of the high density polyethylene of the substrate over a wide temperature range. Therefore, when the aromatic hydrocarbon-containing oil is added to the inner layer 1 of the high-density polyethylene pipe 10, the effect of the oil addition can be maintained for a long time. In addition, the fluid flowing inside the pipe (inner layer 1) is less likely to be contaminated by the oil oozing out.
In addition, aromatic-containing oils are characterized by high lightning. Therefore, when the aromatic hydrocarbon-containing oil is used as the additive, the high-density polyethylene pipe 10 can be safely manufactured.
In addition, most of the aromatic hydrocarbon-containing oils contain impurities such as sulfur and have a high acid value. Sulfur, aldehyde, carboxylic acid, and the like are likely to participate in the radical reaction, and thus the oil itself deteriorates sacrificially, thereby obtaining an effect of suppressing deterioration of the inner layer 1 of the high-density polyethylene pipe 10.
In addition, oils containing cycloalkanes or oils containing aromatics show the effect of softening polyethylene. It is generally known that polyethylene becomes hard and easily embrittled when it is continuously used in a radiation environment. However, when the oil containing naphthenes or the oil containing aromatic hydrocarbons is blended in the inner layer 1 of the high-density polyethylene pipe 10, the high-density polyethylene itself of the base material is softened, and thus embrittlement by radiation is less likely to occur.
The amount of the naphthenic oil or aromatic oil added is preferably 0.1 to 7 parts by mass, more preferably 1 to 7 parts by mass, based on 100 parts by mass of the high-density polyethylene. When the amount exceeds 7 parts by mass, the oil bleeds out, and it is difficult to properly blend the oil. On the other hand, when the amount is less than 0.1 part by mass, a sufficient effect due to the addition cannot be obtained. On the other hand, in the above-mentioned range of the addition amount, the effect of suppressing the deterioration of the resin and the effect of improving the slidability of the polyethylene molecules are higher as the addition amount is larger.
The content of oil contained in the base material mainly composed of high-density polyethylene can be measured by, for example, infrared spectroscopic analysis. The increase or decrease in the crystalline region and the amorphous region in the substrate can be examined, for example, by using a Differential Scanning Calorimeter (DSC). In general polyethylene, the amount of heat generation due to the melting of crystals due to the deterioration of the resin is greatly reduced. However, when an oil containing cycloalkane or an oil containing aromatic hydrocarbon is blended as an additive, the calorific value of crystal melting hardly decreases.
The fusion-bond preventing film 3 is formed of a resin film containing a resin having a melting point of 150 ℃ or higher. According to the melt adhesion preventing film 3, when the outer layer 4 described later is resin-molded, the outer layer 4 is prevented from being directly melt-adhered to the gas barrier film 2, and heat transfer of the molten resin to the gas barrier film 2 can be prevented. Since it is possible to prevent a large tension from being applied to the gas barrier film 2 melt-bonded to another layer and the gas barrier film 2 itself from being melted, pinholes and cracks are less likely to be generated in the gas barrier film 2, and the gas barrier properties of the gas barrier film 2 can be satisfactorily ensured.
The fusion-bonding preventing film 3 is preferably formed of a polyethylene terephthalate stretched film, a polyimide film, or a polyamideimide film. The melting point of the stretched polyethylene terephthalate or polyamideimide is 150 ℃ or higher. In addition, the polyimide does not melt until it is thermally decomposed at a temperature higher than 150 ℃ (about 500 ℃). Therefore, according to these resins, the melt adhesion preventing film 3 itself is not melted at the melting temperature at the time of resin molding into the outer layer 4, and the melt adhesion of the gas barrier film 2 and the heat transfer to the gas barrier film 2 can be reliably suppressed.
Further, the stretched polyethylene terephthalate, polyimide and polyamideimide have an aromatic ring, have high radiation resistance, and are less likely to change physical properties even at a high radiation dose. Therefore, when the resin is molded into the outer layer 4, the gas barrier properties of the gas barrier film 2 are satisfactorily ensured by suppressing melt adhesion and heat transfer, and the inner layer 1 and the gas barrier film 2 can be protected from radiation, impact, external pressure, and the like after the production of the high-density polyethylene pipe 10.
The total thickness of the fusion-bond preventing film 3 when wound around the outer periphery of the gas barrier film 2 is preferably 10 μm or more, more preferably 20 μm or more, and still more preferably 50 μm or more. Further, it is preferably 300 μm or less, more preferably 200 μm or less, and further preferably 150 μm or less. When the total thickness is 10 μm or more, the thicker the film, the more the fusion bonding and heat transfer are suppressed, and the gas barrier property of the gas barrier film 2 can be ensured satisfactorily. In addition, when the total thickness is 20 μm or more and 200 μm or less, particularly high radiation resistance can be obtained by the neutron shielding ability of the resin itself. On the other hand, when the total thickness is 300 μm or less, the thinner the thickness, the lower the material cost of the anti-fusion bonding film 3 and the labor for winding.
The outer layer 4 has a density of 0.910g/cm3Above 0.930g/cm3The following Low Density Polyethylene (LDPE) is used as the main component. The outer layer 4 can be provided by resin molding by extrusion molding, injection molding, or the like so as to cover the outer peripheral surface of the melt adhesion preventing film 3. Since low density polyethylene has high flexibility, impact resistance, moisture resistance, water resistance, chemical resistance and the like, the inner layer 1, the gas barrier film 2 and the anti-melting layer can be protected by the outer layer 4 mainly composed of low density polyethyleneThe adhesive film 3 is not damaged by impact, external pressure, damage, chemicals, water vapor, rainwater, dew, or the like.
A typical double tube has a structure in which a guide tube and a covering layer are fusion bonded and a resin matrix is continuous. Therefore, the impact and dynamic strain of the brittle fracture generated in the coating layer are easily transmitted to the conduit, and cause a cracking phenomenon such as stress cracking in the conduit. In particular, when the covering layer is high density polyethylene or medium density polyethylene, the impact and dynamic strain transmitted to the catheter become large as compared with low density polyethylene having high flexibility.
In contrast, in the high-density polyethylene pipe 10, the gas barrier film 2 and the fusion-bonding preventing film 3 are provided between the guide pipe (inner layer 1) and the protective layer (outer layer 4), and the protective layer (outer layer 4) contains low-density polyethylene as a main component. Therefore, the gas barrier film 2 and the fusion-bonding preventing film 3 can prevent the impact, the propagation of dynamic strain, and the development of cracks from the outer layer 4 to the inner layer 1. Further, since the outer layer 4 contains low-density polyethylene as a main component, it can be easily joined to a joint by electrofusion or the like.
The outer layer 4 preferably contains carbon black as an additive. As the carbon black, for example, furnace black, channel black, acetylene black, pyrolytic carbon black, and the like can be used. When carbon black is blended, ultraviolet rays are absorbed, and therefore, deterioration of ultraviolet rays in the outer layer 4 and the inner layer 1 can be suppressed. That is, since the high density polyethylene pipe 10 itself has improved weather resistance, the fluid transport can be maintained well even outdoors or the like under a high radiation dose.
The content of carbon black in each outer layer 4 is preferably 1.0% by mass or more, more preferably 1.5% by mass or more. Further, it is preferably 4.0% by mass or less, more preferably 3.0% by mass or less, and further preferably 2.5% by mass or less. When the content is 1.0 mass% or more, the greater the content, the higher the ultraviolet ray absorbing effect can be obtained, and therefore the weather resistance of the high density polyethylene pipe 10 can be sufficiently improved. When the content is 4.0% by mass or less, a large amount of carbon black is less likely to cause aggregates in the resin when the content is small. Therefore, the agglomerated masses can be prevented from becoming the starting points of environmental stress cracks or brittle fractures.
The thickness of the outer layer 4 is preferably 0.4mm or more, more preferably 0.5mm or more, and further preferably 0.8mm or more. Further, it is preferably 4mm or less, more preferably 3mm or less, and further preferably 2mm or less. When the thickness is 0.4mm or more, the protective performance of the outer layer 4 can be improved as the thickness is increased. When the thickness is 0.5mm or more and 3mm or less, particularly high radiation resistance is obtained by the neutron shielding ability of the resin itself. On the other hand, when the thickness is 4mm or less, the material cost of the outer layer 4 can be reduced as the thickness is thinner.
Next, a method for producing the high-density polyethylene pipe will be described.
The guide tube (inner layer 1) and the protective layer (outer layer 4) of the high-density polyethylene tube can be manufactured by the following method: polyethylene prepared as pellets or the like is heated and melted, and if necessary, additives such as oil and carbon black are added and kneaded, and the obtained polyethylene resin composition is used as a material for extrusion molding, injection molding, and the like.
In the production of the polyethylene resin composition and the production of the high-density polyethylene pipe, the additives may be dry blended or may be directly mixed with the resin. However, if the kneading of the solid additive such as carbon black is insufficient, the solid additive is coagulated to become a starting point of the fracture. Therefore, the additives are preferably prepared in advance as a master batch and then mixed, and particularly preferably prepared as a master batch in a state of being mixed with oil and then mixed.
For example, in the production of a polyethylene resin composition, when an additive is dry-blended, master batch pellets prepared by blending the additive and polyethylene resin pellets are put into a hopper of a pellet production apparatus and melt-kneaded. Then, the kneaded molten resin composition is extruded into water through a stainless steel disc having a plurality of holes (for example, a diameter of about 3mm) formed therein, and cut into a predetermined length (for example, a length of about 3mm) by a knife provided in parallel with the disc surface, whereby polyethylene resin composition pellets containing an additive can be obtained.
Alternatively, in the production of the polyethylene resin composition, the oil blended as the additive may be separately and directly mixed into the molten resin composition during melt kneading. For example, the master batch pellets and the polyethylene resin pellets are put into a hopper of a pellet production apparatus together, and at the same time, oil is dropped at a constant dropping rate using a micro-tube pump or the like, and they are melt-kneaded. Then, the kneaded molten resin composition is extruded in water and cut into a predetermined length, whereby polyethylene resin composition pellets containing an additive can be obtained.
In the production of the high-density polyethylene pipe, only the polyethylene resin composition pellets containing the additive may be used as the material, or the master batch pellets and the polyethylene resin pellets may be used as the material. For example, the catheter (inner layer 1) can be produced by feeding these pellets to a hopper of an extruder (tube production apparatus), heating and melting the pellets in the extruder, extruding the pellets in a cylindrical shape from a die, sizing the pellets as needed while taking out the pellets by a take-out machine, and cooling the pellets by introducing the pellets into a cooling water tank or the like.
As the kneader, various kneaders such as a batch kneader such as a Banbury mixer, a twin-screw kneader, a rotor type twin-screw kneader, and a Busco kneader can be used. As the extruder, for example, a single screw extruder, a twin screw extruder, or the like can be used. The mold may be any of a straight head mold, a crosshead mold, an offset (offset) mold, and the like. The sizing may be performed by any of a sizing plate method, an outer mandrel method, a size box method, an inner mandrel method, and the like.
The kneading temperature of the polyethylene is preferably 120 ℃ to 250 ℃. In the case of using a Banbury mixer, a molten resin composition is obtained by kneading at 180 ℃ for 10 minutes or the like, for example. The polyethylene resin composition may contain titanium oxide in an amount of 0.1 to 5 parts by mass per 100 parts by mass of polyethylene.
The gas barrier film 2 and the anti-fusion bonding film 3 may be film-formed by a suitable method such as coating forming. The multilayer film used as the gas barrier film 2 may be formed by a suitable method such as a coextrusion method or a lamination method. The multilayer film may be formed by any one of a non-stretched film, a uniaxially stretched film, and a biaxially stretched film. The multilayer film is preferably formed by biaxially stretching a film from the viewpoint of obtaining high strength and excellent gas barrier properties.
The gas barrier film 2 may be wound around the outer circumference so as to cover the outer surface of the resin-molded duct (inner layer 1). The resin-molded inner layer 1 is preferably cooled in advance to a temperature at least not causing hot-melt adhesion by water cooling or air cooling before being wound with the gas barrier film 2. The winding method of the gas barrier film 2 may be any one of one-turn winding, multiple-turn winding, and spiral winding. Among them, a winding system having an arbitrary overlapping width is preferably provided from the viewpoint of reliably exhibiting gas barrier properties. For example, it is preferable to provide multi-turn winding or spiral winding having an overlapping width of 1/2 or more of the film width.
The fusion-bonding preventing film 3 may be wound around the outer circumference so as to cover the outer surface of the gas barrier film 2 wound around the pipe (inner layer 1). The winding form of the fusion-bonding preventing film 3 may be any one of one-turn winding, multiple-turn winding, and spiral winding. Among them, in the case of resin molding the outer layer 4, a winding system having an arbitrary overlapping width is preferably provided from the viewpoint of suppressing direct melt adhesion of the outer layer 4 to the gas barrier film 2 and suppressing heat transfer of the molten resin to the gas barrier film 2. For example, it is preferable to provide multi-turn winding or spiral winding having an overlapping width of 1/2 or more of the film width.
The protective layer (outer layer 4) can be formed by: the pipe (inner layer 1) around which the gas barrier film 2 and the melt adhesion preventing film 3 are wound is supplied to a jacket (sheath) extrusion molding apparatus as a core wire, and the polyethylene resin composition for the protective layer is extrusion molded on the outer periphery of the supplied core wire. The high-density polyethylene pipe 10 can be produced by heating and melting the polyethylene resin composition in a sheath extrusion molding device, covering the outer periphery of the core wire, extruding the composition from a die, sizing the composition as needed while taking out the composition with a take-out machine, and cooling the composition in a cooling water tank or the like.
Next, the joint and the sealing material made of high density polyethylene will be described.
The joint of the present embodiment has the same layer structure as the high density polyethylene pipe 10. Specifically, the joint of the present embodiment includes: the gas barrier film comprises a cylindrical inner layer 1 through which fluid flows, a gas barrier film 2 covering the outer surface of the inner layer 1, an anti-melt-bonding film 3 covering the outer surface of the gas barrier film 2, and an outer layer 4 covering the outer surface of the anti-melt-bonding film 3.
The size, shape, connection method, and the like of the joint of the present embodiment are not particularly limited. The connection method may be any of mechanical, electrofusion, screw, and the like. The joint of the present embodiment may have a flange, a nut, a bracket, a sealing material, and the like as long as the body portion has a layer structure including the inner layer 1, the gas barrier film 2, the melt adhesion preventing film 3, and the outer layer 4, as in the high density polyethylene pipe 10.
The joint of the present embodiment can be produced by the following method, for example, in the same manner as the high density polyethylene pipe 10 described above: after extrusion molding of the body (inner layer 1), winding of the gas barrier film 2 and the melt adhesion preventing film 3, and the like are performed using the polyethylene resin composition as a material, secondary processing is performed on the molded body up to the formation of the protective layer (outer layer 4).
The sealing material of the present embodiment has the same layer structure as the high-density polyethylene pipe 10. Specifically, the sealing material of the present embodiment includes: an inner layer 1 in contact with a fluid, a gas barrier film 2 covering an outer surface of the inner layer 1, an anti-melt adhesive film 3 covering an outer surface of the gas barrier film 2, and an outer layer 4 covering an outer surface of the anti-melt adhesive film 3.
As polyethylene used for the sealing material, ultra-high molecular weight polyethylene having a molecular weight of about 100 to about 700 ten thousand can be preferably used. Specifically, a resin having a melt index of less than 0.1g/10 min at a test temperature of 190 ℃ and a test load of 21.6kgf, which is determined in accordance with ISO1133, can be used. However, the polyethylene used for the sealing material is not limited to resins exhibiting such physical properties. In the case of using ultra-high molecular weight polyethylene, the inner layer 1 does not have to be high density polyethylene.
The sealing material of the present embodiment may be in the form of a gasket such as a flange gasket (flange packing) or a circular ring, and the size, shape, and the like are not particularly limited. The sealing material is constituted by a layer having the inner layer 1, the gas barrier film 2, the anti-fusion bonding film 3, and the outer layer 4, at least a part of a region between a surface in contact with the fluid and a surface exposed to the outside air or ultraviolet rays, as in the high-density polyethylene pipe 10 described above, and the entire surface of the sealing material does not necessarily need to be covered with the gas barrier film 2, the anti-fusion bonding film 3, or the outer layer 4.
The joint and the sealing material of the present embodiment are produced by, for example, the following methods in the same manner as the high density polyethylene pipe 10: the polyethylene resin composition is used as a material, and after injection molding of the base (inner layer 1), winding and sticking of a film, and the like, a protective layer (outer layer 4) is formed on the outside thereof.
According to the high-density polyethylene pipe, the joint, and the sealing material of the present embodiment described above, the inner layer is covered with the gas barrier film, and therefore, oxidative degradation of the inner layer resin due to oxygen in the outside air can be suppressed. Therefore, even when the high-density polyethylene pipe, joint, or sealing material is exposed to high radiation dose radiation, oxygen in the atmosphere, strong ultraviolet rays such as outdoors in summer, acid rain, or the like for a long time, or is in contact with a fluid containing a radioactive substance at a high concentration or a high radiation dose, a high-temperature fluid, or the like for a long time, the propagation reaction of oxidation is suppressed, and deterioration of the resin in the inner layer due to external factors such as radiation, ultraviolet rays, oxygen, and heat is greatly suppressed.
In addition, according to the high-density polyethylene pipe, joint, and sealing material of the present embodiment, since the gas barrier film is covered with the outer layer, when earth pressure, impact, load, or the like is applied from the outside, it is possible to suppress deterioration of the gas barrier film itself and the inner layer due to radiation and ultraviolet rays while preventing damage to the gas barrier film. Further, since the fusion-bonding preventing film is provided between the gas barrier film and the outer layer, the outer layer can be formed by resin molding using a molten resin on the outside of the gas barrier film, and in this case, the soundness of the gas barrier film can be ensured. Unlike the case where the protective tape is wound on the outermost surface, the outer layer of the resin molding is less likely to have gaps and holes and is less likely to peel off, and therefore, the resistance to external factors that degrade the resin can be improved.
Therefore, when fluid pressure, earth pressure, impact, load, or the like is applied to the high-density polyethylene pipe, joint, or sealing material, environmental stress cracking or creep rupture is less likely to occur, and cracking, brittle cracking, or the like, and cracking of the pipe or joint are prevented. That is, the intrinsic defect of polyethylene, which easily causes brittle fracture cracking, can be fundamentally improved. Even if minute defects invisible to the naked eye are present, brittle fracture and stress cracking are less likely to occur due to stress concentration thereon, and sufficient elongation and elasticity can be obtained, so that stress environment cracking resistance and impact resistance can be improved.
In particular, high density polyethylene pipes, joints, and sealing materials with reduced brittle fracture and creep fracture due to resin deterioration can be obtained not only in normal environments but also in various severe environments such as high-dose irradiation environments, ultraviolet environments such as outdoor environments in summer, high-temperature environments such as summer, and environments exposed to high concentrations of oxygen and acid rain. Further, a high-density polyethylene pipe, a joint, and a sealing material which are less likely to deteriorate in long-term hydrostatic strength, elasticity, environmental stress cracking resistance, impact resistance, and the like, and are less likely to cause brittle fracture cracking and cracking can be obtained.
The use of the high-density polyethylene pipe, the joint, and the sealing material according to the present embodiment is not particularly limited. The high-density polyethylene pipe, joint, and sealing material can be used in a suitable environment. In addition, high density polyethylene pipes and joints are used for the transport of suitable fluids such as water, seawater, and the like. The sealing material can be used for sealing a suitable fluid during storage, transportation, handling, and the like of the fluid.
In particular, high density polyethylene pipes and joints are used for the transport of fluids such as water, seawater, etc. in nuclear power related facilities. In the nuclear energy-related facility, tens to hundreds of nuclear energy facilities are surrounded by pipes and connected to a plurality of contaminated water retention zones. The total length of these pipes is generally from about 10km to about 20 km. The high-density polyethylene pipe and the joint can be suitably used for such a nuclear facility pipe. According to the high-density polyethylene pipe and the joint, it is possible to transport a fluid containing a radioactive substance, and to transport a fluid at a high radiation dose or outdoors, robustly and reliably for a long period of time.
The sealing material is effective for sealing a fluid in a nuclear power-related facility, a nuclear fuel facility, or the like, and is suitably used as a sealing material for a nuclear power facility pipe, a nuclear fuel facility pipe, a radioactive substance storage container, or the like. The sealing material can be particularly suitable for sealing a fluid containing a high concentration of radioactive substances and sealing a fluid at a high radiation dose.
According to the high-density polyethylene pipe, the joint, and the sealing material of the present embodiment, deterioration of the resin is greatly suppressed, and therefore, even at a high radiation dose at which radicals are likely to be generated, it is possible to reliably prevent occurrence of a leakage event while maintaining soundness of the resin molded body. When a fluid containing a high concentration of radioactive substance is treated, the fluid can be used for a long period of time, and the frequency of replacement and inspection can be reduced, so that the number of steps and materials for laying and installation, the risk of exposure of constructors and inspectors, and the like can be greatly reduced.
While the embodiments of the high density polyethylene pipe, joint, and sealing material of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications may be made without departing from the technical scope. For example, the above-described embodiments are not necessarily limited to the embodiments having all the configurations described above. Further, a part of the configuration of the embodiment may be replaced with another configuration, or another configuration may be added to the configuration of the embodiment. Further, as for a part of the configuration of the embodiment, addition of other configurations, deletion of the configuration, and replacement of the configuration may be performed.
For example, the high-density polyethylene pipe, the joint, and the sealing material are configured to include the inner layer 1, the gas barrier film 2, the fusion-bonding preventing film 3, and the outer layer 4 in this order, but functional layers such as a buffer layer for buffering impact may be provided between the inner layer 1 and the gas barrier film 2, and between the gas barrier film 2 and the fusion-bonding preventing film 3. The buffer layer may be formed, for example, by coating the buffer layer with a density of less than 0.940g/cm3The polyethylene of (A) isA resin molded body of the main component, or other films, tapes, and the like.
Examples
The present invention will be described in detail below with reference to examples, but the technical scope of the present invention is not limited thereto.
Test pieces of high density polyethylene pipes were produced by changing the amounts of oils containing naphthenes and aromatics and the layer structure of the gas barrier film, and the tensile elongation at break after the radiation irradiation treatment was evaluated.
As the substrate of the inner layer, high density polyethylene produced by using a ziegler catalyst was used. A base material of high-density polyethylene was blended with an oil containing cycloalkane or an oil containing aromatic hydrocarbon as an additive, and kneaded at 180 ℃ for 10 minutes using a Banbury mixer to produce pellets for high-density polyethylene pipes. Then, the pellets were put into an injection molding machine and molded into a cylindrical duct (inner layer).
Next, the gas barrier film was wound around the outer periphery of the molded duct (inner layer) using a winder, and the melt-resistant adhesive film was wound around the outer periphery of the gas barrier film. Next, on the outer periphery of the gas barrier film, the density of carbon to be blended was 0.910g/cm3Above 0.930g/cm3The following low-density polyethylene was extrusion-molded to form a protective layer (outer layer) to obtain a high-density polyethylene pipe.
From the produced high-density polyethylene pipe, a 1B dumbbell type test piece described in Japanese Industrial Standards (JIS K7162) was produced. The prepared test piece was irradiated at a radiation dose rate of 1kGy/h60Gamma rays emitted by a Co radiation source. The absorbed radiation dose was 1000 kGy.
< tensile test >
The tensile test was carried out according to the Japan Water pipe Association Standard "polyethylene pipe for Water distribution JWWA K144". The testing machine used was the one described in JIS B7721, which was equipped with a device for indicating the maximum tensile force and a holder for clamping a dumbbell-shaped test piece. The thickness of the test piece and the width of the parallel portion were measured, and a mark line (mark line) for measuring the elongation was marked at the center of the parallel portion, and then a tensile test was performed at a test speed of 25mm/min at room temperature. The distance between the marked lines was 50 mm. The tensile test was performed, the distance between the standard lines at the time of breaking the test piece was measured, and the elongation at the time of breaking was calculated by the following numerical formula (1). In the numerical expression (1), EB represents the elongation (%) at break, L0 represents the distance (mm) between the standard lines, and L1 represents the distance (mm) between the standard lines at break.
EB=(L1-L0)/L0×100…(1)
The following shows the results of measuring the tensile elongation at break after the radiation irradiation treatment for the test pieces prepared by changing the amount of oil containing naphthenes added.
As a base material of the catheter (inner layer), a material having a density of 0.95g/cm was used3The high density polyethylene of (1). As the additive, an oil having a% CN of a ring analysis measured by an n-d-M method of an oil produced when a crude oil is purified as a predetermined value and a% CA of 30% is used. The amount of the oil added was 5 parts by mass per 100 parts by mass of the high-density polyethylene. As the gas barrier film, a multilayer film of LLDPE/EVOH/LLDPE was used, in which the thickness of EVOH was 24 μm and the MFR (melt flow rate) of LLDPE was 3g/10 min so that the total thickness of the multilayer film when wound on the outer periphery was 300 μm. As the anti-melt-adhesive film, a polyethylene terephthalate stretched film was used so that the total thickness of the stretched film when wound on the outer periphery was 100 μm. As the protective layer (outer layer), a layer of 2mm thick low density polyethylene containing 3 mass% of carbon was formed.
FIG. 3 is a graph showing the relationship between% CN of oil used as an additive and elongation at break.
In fig. 3, the horizontal axis represents% CN (%) of oil used as an additive, and the vertical axis represents elongation (%) at break due to stretching.
As shown in fig. 3, in the case of adding oil containing naphthenes as an additive, when% CN is 20% or more and 60% or less, the following results were obtained: the tensile elongation at break is significantly increased and the radiation deterioration is well suppressed.
Next, the results of measuring the tensile elongation at break after the radiation irradiation treatment were shown for the test pieces prepared by changing the amount of the aromatic hydrocarbon-containing oil added.
As a base material of the catheter (inner layer), a material having a density of 0.95g/cm was used3The high density polyethylene of (1). As the additive, an oil having a% CA of a ring analysis measured by an n-d-M method of a crude oil purification method of a predetermined value and a% CN of 40% was used. The amount of the oil added was 5 parts by mass per 100 parts by mass of the high-density polyethylene. As the gas barrier film, a multilayer film of LLDPE/EVOH/LLDPE was used, in which the thickness of EVOH was 24 μm and the MFR of LLDPE was 3g/10 min so that the total thickness of the multilayer film when wound on the outer periphery was 300 μm. As the anti-melt-adhesive film, a polyethylene terephthalate stretched film was used so that the total thickness of the stretched film when wound on the outer periphery was 100 μm. As the protective layer (outer layer), a layer of 2mm thick low density polyethylene containing 3 mass% of carbon was formed.
Fig. 4 is a graph showing the relationship between% CA of oil used as an additive and elongation at break.
In fig. 4, the horizontal axis represents% CA (%) of the aromatic hydrocarbon-containing oil used as an additive, and the vertical axis represents elongation (%) at break due to stretching.
As shown in fig. 4, when the aromatic hydrocarbon-containing oil was added as an additive, the following results were obtained when the% CA was 5% to 60%, particularly 5% to 40%: the tensile elongation at break is significantly increased and the radiation deterioration is well suppressed.
Next, the measurement results of the tensile elongation at break after the radiation irradiation treatment are shown for the test pieces produced by changing the MFR of the LLDPE of the gas barrier film.
As a base material of the catheter (inner layer), a material having a density of 0.95g/cm was used3The high density polyethylene of (1). As the additive, an oil having a% CN of ring analysis of 40% and a% CA of 30% by n-d-M method among oils produced when crude oil is refined was used. The amount of the oil added was 5 parts by mass per 100 parts by mass of the high-density polyethylene. As the gas barrier film, a multilayer film of LLDPE/EVOH/LLDPE was used, in which EVOH was 24 μm thick so as to be wound on the outer peripheryThe total thickness of the multilayer film in the case of (2) is 300. mu.m. As the anti-melt-adhesive film, a polyethylene terephthalate stretched film was used so that the total thickness of the stretched film when wound on the outer periphery was 100 μm. As the protective layer (outer layer), a layer of 2mm thick low density polyethylene containing 3 mass% of carbon was formed.
Fig. 5 is a graph showing the relationship between MFR and elongation at break of linear low density polyethylene used for a gas barrier film.
In fig. 5, the horizontal axis represents MFR (g/10 min) of linear low-density polyethylene used as the surface layer of the gas barrier film, and the vertical axis represents elongation (%) at break due to stretching.
As shown in fig. 5, when the MFR of the linear low density polyethylene used as the surface layer of the gas barrier film was 0.8g/10 min or more and 10g/10 min or less, the following results were obtained: the tensile elongation at break exceeded 400%, and radiation deterioration was well suppressed.
Next, the results of measuring the tensile elongation at break after the radiation irradiation treatment were shown for the test pieces prepared by changing the total thickness of the gas barrier film.
As a base material of the catheter (inner layer), a material having a density of 0.95g/cm was used3The high density polyethylene of (1). As the additive, an oil having a% CN of ring analysis of 40% and a% CA of 30% by n-d-M method among oils produced when crude oil is refined was used. The amount of the oil added was 5 parts by mass per 100 parts by mass of the high-density polyethylene. As the gas barrier film, a multilayer film of LLDPE/EVOH/LLDPE was used, in which EVOH was 24 μm in thickness and LLDPE had an MFR of 3g/10 min. As the anti-melt-adhesive film, a polyethylene terephthalate stretched film was used so that the total thickness of the stretched film when wound on the outer periphery was 100 μm. As the protective layer (outer layer), a layer of 2mm thick low density polyethylene containing 3 mass% of carbon was formed.
Fig. 6 is a graph showing the relationship between the total thickness of the gas barrier film and the elongation at break.
In fig. 6, the horizontal axis represents the total thickness (μm) of the gas barrier film when wound around the outer periphery of the inner layer, and the vertical axis represents the elongation (%) at the time of breaking due to stretching.
As shown in fig. 6, when the total thickness of the gas barrier film is 50 μm or more and 400 μm or less, the following results are obtained: the tensile elongation at break is significantly increased and the radiation deterioration is well suppressed.
Next, the results of measuring the tensile elongation at break after the radiation irradiation treatment were shown for the test pieces prepared by changing the thickness of EVOH of the gas barrier film.
As a base material of the catheter (inner layer), a material having a density of 0.95g/cm was used3The high density polyethylene of (1). As the additive, an oil having a% CN of ring analysis of 40% and a% CA of 30% by n-d-M method among oils produced when crude oil is refined was used. The amount of the oil added was 5 parts by mass per 100 parts by mass of the high-density polyethylene. As the gas barrier film, a multilayer film of LLDPE/EVOH/LLDPE was used, wherein the MFR of LLDPE was 3g/10 minutes so that the total thickness of the multilayer film when wound on the outer periphery was 300. mu.m. As the anti-melt-adhesive film, a polyethylene terephthalate stretched film was used so that the total thickness of the stretched film when wound on the outer periphery was 100 μm. As the protective layer (outer layer), a layer of 2mm thick low density polyethylene containing 3 mass% of carbon was formed.
Fig. 7 is a graph showing the relationship between the thickness and the elongation at break of an ethylene-vinyl alcohol copolymer resin used for a gas barrier film.
In fig. 7, the horizontal axis represents the thickness (μm) of the ethylene-vinyl alcohol copolymer resin used as the intermediate layer of the gas barrier film, and the vertical axis represents the elongation (%) at break due to stretching.
As shown in fig. 7, when the thickness of the ethylene-vinyl alcohol copolymer resin used as the intermediate layer of the gas barrier film is 10 μm or more and 50 μm or less, the following results are obtained: the tensile elongation at break is significantly increased and the radiation deterioration is well suppressed.
Next, the results of measuring the tensile elongation at break after the radiation irradiation treatment were shown for the test pieces produced by changing the thickness of the anti-fusion bonding film.
As a base material of the conduit (inner layer), use is made ofThe density was 0.95g/cm3The high density polyethylene of (1). As the additive, an oil having a% CN of ring analysis of 40% and a% CA of 30% by n-d-M method among oils produced when crude oil is refined was used. The amount of the oil added was 5 parts by mass per 100 parts by mass of the high-density polyethylene. As the gas barrier film, a multilayer film of LLDPE/EVOH/LLDPE was used, in which the thickness of EVOH was 24 μm and the MFR of LLDPE was 3g/10 min so that the total thickness of the multilayer film when wound on the outer periphery was 300 μm. As the anti-melt adhesive film, a polyethylene terephthalate stretched film was used. As the protective layer (outer layer), a layer of 2mm thick low density polyethylene containing 3 mass% of carbon was formed.
Fig. 8 is a graph showing the relationship between the thickness of the anti-fusion bonding film and the elongation at break.
In fig. 8, the horizontal axis represents the thickness (μm) of the anti-fusion bonding film, and the vertical axis represents the elongation (%) at break due to stretching.
As shown in fig. 8, when the thickness of the anti-fusion bonding film is 20 μm or more and 200 μm or less, the following results were obtained: the tensile elongation at break is significantly increased and the radiation deterioration is well suppressed.
Next, the results of measuring the tensile elongation at break after the radiation irradiation treatment were shown for the test pieces produced by changing the thickness of the protective layer (outer layer).
As a base material of the catheter (inner layer), a material having a density of 0.95g/cm was used3The high density polyethylene of (1). As the additive, an oil having a% CN of ring analysis of 40% and a% CA of 30% by n-d-M method among oils produced when crude oil is refined was used. The amount of the oil added was 5 parts by mass per 100 parts by mass of the high-density polyethylene. As the gas barrier film, a multilayer film of LLDPE/EVOH/LLDPE was used, in which the thickness of EVOH was 24 μm and the MFR of LLDPE was 3g/10 min so that the total thickness of the multilayer film when wound on the outer periphery was 300 μm. As the anti-melt-adhesive film, a polyethylene terephthalate stretched film was used so that the total thickness of the stretched film when wound on the outer periphery was 100 μm. As the protective layer (outer layer), a layer of low density polyethylene containing 3 mass% of carbon was formed.
Fig. 9 is a graph showing the relationship between the thickness of the protective layer (outer layer) and the elongation at break.
In fig. 9, the horizontal axis represents the thickness (mm) of the protective layer (outer layer) and the vertical axis represents the elongation (%) at break due to stretching.
As shown in fig. 9, when the thickness of the protective layer (outer layer) is 0.5mm or more and 3mm or less, the following results are obtained: the tensile elongation at break is significantly increased and the radiation deterioration is well suppressed.
Next, the results of measuring the tensile elongation at break after the radiation irradiation treatment were shown for the test pieces produced by changing the layer configuration of the gas barrier film and the type of the anti-fusion adhesive film.
As a base material of the catheter (inner layer), a material having a density of 0.95g/cm was used3The high density polyethylene of (1). As the additive, an oil having a% CN of 32% and a% CA of 10% of ring analysis by n-d-M method among oils produced when crude oil is refined was used. The amount of the oil added was 5 parts by mass per 100 parts by mass of the high-density polyethylene.
[ Table 1]
As shown in table 1, when Linear Low Density Polyethylene (LLDPE) was used as the surface layer of the gas barrier film, radiation deterioration was suppressed as compared with the case of using Low Density Polyethylene (LDPE). Although the anti-fusion bonding film can obtain high radiation resistance regardless of the type, the use of the polyamideimide film particularly suppresses radiation deterioration compared to the use of a stretched polyethylene terephthalate film or a polyimide film as the anti-fusion bonding film.
Description of the reference numerals
10 high density polyethylene pipe
1 inner layer
2 gas barrier film
21 surface layer
22 intermediate layer
23 surface layer
3 anti-fusion adhesive film
4 outer layer
Claims (13)
1. A high-density polyethylene pipe comprising:
with a density of 0.940g/cm3Above 0.980g/cm3The inner layer mainly composed of the following high-density polyethylene,
a gas barrier film containing an ethylene-vinyl alcohol copolymer resin covering the outer surface of the inner layer,
an anti-fusion bonding film covering the outer surface of the gas barrier film and containing a resin having a melting point of 150 ℃ or higher, and
a density of 0.910g/cm covering the outer surface of the fusion-bond preventing film3Above 0.930g/cm3The outer layer mainly composed of the following low-density polyethylene.
2. The high density polyethylene pipe of claim 1, wherein the inner layer comprises at least one of:
an oil containing naphthenes formed when refining crude oil, and
an aromatic-containing oil produced when crude oil is refined.
3. The high density polyethylene pipe of claim 1, wherein the inner layer comprises at least one of:
an oil containing naphthenes and having a% CN of 20-60% in a ring analysis measured by an n-d-M method, among oils produced when crude oil is refined, and
an aromatic hydrocarbon-containing oil having a% CA of 5% to 40% in a ring analysis measured by an n-d-M method, among oils produced when crude oil is purified.
4. The high-density polyethylene pipe according to claim 1, wherein the ethylene-vinyl alcohol copolymer resin has a thickness of 1 μm or more and 50 μm or less.
5. The high density polyethylene pipe of claim 1,
the gas barrier film is a multilayer film having: an intermediate layer containing an ethylene-vinyl alcohol copolymer resin, and surface layers laminated on both sides of the intermediate layer,
the surface layer contains at least one of low-density polyethylene and linear low-density polyethylene.
6. The high-density polyethylene pipe according to claim 5, wherein the total thickness of the multilayer film when wound around the outer periphery is 50 μm or more and 400 μm or less.
7. The high-density polyethylene pipe according to claim 1, wherein the melt adhesion preventing film is a polyethylene terephthalate stretched film, a polyimide film, or a polyamideimide film.
8. The high-density polyethylene pipe according to claim 1, wherein the total thickness of the fusion-bond preventing film when wound around the outer periphery is 20 μm or more and 200 μm or less.
9. The high density polyethylene pipe of claim 1 wherein the outer layer comprises carbon black.
10. The high-density polyethylene pipe according to claim 9, wherein a content of the carbon black in the outer layer is 1.0 mass% or more and 3.0 mass% or less.
11. The high density polyethylene pipe as claimed in any one of claims 1 to 10, which is a pipeline for nuclear power equipment for fluid transportation in nuclear power-related facilities.
12. A joint, comprising:
with a density of 0.940g/cm3Above 0.980g/cm3The inner layer mainly composed of the following high-density polyethylene,
a gas barrier film containing an ethylene-vinyl alcohol copolymer resin covering the outer surface of the inner layer,
an anti-fusion bonding film covering the outer surface of the gas barrier film and containing a resin having a melting point of 150 ℃ or higher, and
a density of 0.910g/cm covering the outer surface of the fusion-bond preventing film3Above 0.930g/cm3The outer layer mainly composed of the following low-density polyethylene.
13. A sealing material, comprising:
with a density of 0.940g/cm3Above 0.980g/cm3The inner layer mainly composed of the following high-density polyethylene,
a gas barrier film containing an ethylene-vinyl alcohol copolymer resin covering the outer surface of the inner layer,
an anti-fusion bonding film covering the outer surface of the gas barrier film and containing a resin having a melting point of 150 ℃ or higher, and
a density of 0.910g/cm covering the outer surface of the fusion-bond preventing film3Above 0.930g/cm3The outer layer mainly composed of the following low-density polyethylene.
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JP2018141625A JP6990629B2 (en) | 2018-07-27 | 2018-07-27 | High density polyethylene pipes, fittings and sealing materials |
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JPH01319580A (en) * | 1988-06-22 | 1989-12-25 | Haishiito Kogyo Kk | Packing material |
JP2642155B2 (en) * | 1988-08-02 | 1997-08-20 | 株式会社クラレ | Gas barrier multi-layer hose |
JP2003097770A (en) * | 2001-09-25 | 2003-04-03 | Hitachi Cable Ltd | Hose for cooling carbon dioxide gas |
JP2004225820A (en) * | 2003-01-23 | 2004-08-12 | Hitachi Metals Ltd | Multi-layer resin tube |
JP2009092095A (en) * | 2007-10-04 | 2009-04-30 | Toyox Co Ltd | Gas barrier property synthetic resin pipe and heating/cooling panel |
JP5965201B2 (en) * | 2012-04-27 | 2016-08-03 | 日立Geニュークリア・エナジー株式会社 | High pressure hose for nuclear facilities and nuclear facilities |
US20140182735A1 (en) * | 2012-12-28 | 2014-07-03 | Thercom Holdings, Llc | Thermoplastic extrusion with vapor barrier and surface sulfonation |
JP6287142B2 (en) * | 2013-12-06 | 2018-03-07 | 凸版印刷株式会社 | Multilayer pipe |
CN204756182U (en) * | 2015-05-19 | 2015-11-11 | 曼瑞德集团有限公司 | High creep resistance hinders oxygen type plastic tubing |
JP2017020628A (en) | 2015-07-15 | 2017-01-26 | 日立Geニュークリア・エナジー株式会社 | Fluid transfer piping |
CN106523810B (en) * | 2015-09-14 | 2019-09-06 | 军事科学院系统工程研究院军事新能源技术研究所 | A kind of MULTILAYER COMPOSITE fuel feed pipe |
CN205424129U (en) * | 2015-11-30 | 2016-08-03 | 河北亚大汽车塑料制品有限公司 | Multilayer pipe |
JP6571505B2 (en) | 2015-11-30 | 2019-09-04 | 日立Geニュークリア・エナジー株式会社 | Piping for nuclear equipment, piping joint structure for nuclear equipment, and fluid transportation equipment for nuclear equipment |
JP6693833B2 (en) * | 2016-08-04 | 2020-05-13 | 日立Geニュークリア・エナジー株式会社 | Polyethylene resin composition and piping materials, piping and fittings containing the same |
JP6211153B1 (en) * | 2016-08-08 | 2017-10-11 | 株式会社森武工務店 | Pipe connection structure |
JP6868931B2 (en) * | 2016-11-11 | 2021-05-12 | 日立Geニュークリア・エナジー株式会社 | Hard products, components, pipes, and fittings in nuclear equipment |
JP2018100330A (en) * | 2016-12-20 | 2018-06-28 | 日立Geニュークリア・エナジー株式会社 | Polyethylene resin composition, piping material, piping, joint and member using the same, and method for producing polyethylene resin composition |
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KR20200013223A (en) | 2020-02-06 |
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