CN104788782A - Method for improving slow crack growth resistance of PE (polyethylene) pipe - Google Patents

Method for improving slow crack growth resistance of PE (polyethylene) pipe Download PDF

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Publication number
CN104788782A
CN104788782A CN201510160113.2A CN201510160113A CN104788782A CN 104788782 A CN104788782 A CN 104788782A CN 201510160113 A CN201510160113 A CN 201510160113A CN 104788782 A CN104788782 A CN 104788782A
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resin
polyethylene tube
polyethylene
low density
type low
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CN104788782B (en
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侯书宾
吴源
田沛
危迎春
白成德
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YADA PLASTIC PRODUCT CO Ltd
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
    • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L23/04—Homopolymers or copolymers of ethene
    • C08L23/06—Polyethene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2203/00—Applications
    • C08L2203/18—Applications used for pipes
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2207/00—Properties characterising the ingredient of the composition
    • C08L2207/06—Properties of polyethylene
    • C08L2207/062—HDPE

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  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Rigid Pipes And Flexible Pipes (AREA)
  • Extrusion Moulding Of Plastics Or The Like (AREA)
  • Compositions Of Macromolecular Compounds (AREA)

Abstract

The invention discloses a method for improving slow crack growth resistance of a PE (polyethylene) pipe and belongs to the technical field of production of PE pipes. The method comprises steps as follows: during processing molding of the PE pipe, PE pipe raw material resin and LLDPE (linear low-density polyethylene) resin are evenly mixed, and the PE pipe is obtained through melting, extrusion and cooling; the mass ratio of the LLDPE resin to the PE pipe raw material resin is in a range of 0.5 permillage-5 permillage; the PE pipe raw material resin is PE resin obtained through polymerization with ethylene used as monomers; the LLDPE resin is PE resin with the density ranging from 0.910 g/cm<3> to 0.925 g/cm<3> and is obtained through copolymerization of ethylene and alpha-olefin. With the adoption of the method, on the premises that existing PE pipe processing technological conditions are not changed and other properties of the obtained PE pipe are not affected, the slow crack growth resistance of the obtained PE pipe can be significantly improved. The service life of the PE pipe is prolonged, and the usage safety of the PE pipe is guaranteed.

Description

A kind of method improving polyethylene tube resistance to Slow Crack growth performance
Technical field
The present invention relates to polyethylene tube production technical field, particularly a kind of method improving polyethylene tube resistance to Slow Crack growth performance.
Background technology
Polyethylene (polyethylene, PE) pipe, due to the advantage such as have long service life, corrosion resistance nature is strong, snappiness good, lightweight, easy to connect, friction resistance is little, is widely used in the field such as fuel gas transmission, water supply and drainage.In life-time service process, can brittle rupture be there is in polyethylene tube.Brittle rupture is because polyethylene tube is caused by the Slow Crack growth caused under low-stress, is the broad form that polyethylene tube occurs to destroy in actual use.Destroying on the spot of polyethylene tube is the main inducing causing Slow Crack to increase, if tubing is in the damage such as cut, crackle of producing, transport and cause in construction process, or mechanical connection modification, flattening etc., these crackles can slowly expand to whole tube wall under the bending of outside or torsional load, and finally cause tubing system to be destroyed.For the polyethylene tube bearing interior pressure, it is inevitable for producing Slow Crack growth, and therefore, the resistance to Slow Crack growth performance improving polyethylene tube is significant for its work-ing life to raising.
At present, the method improving polyethylene tube resistance to Slow Crack growth performance mainly improves the performance of the material resin for processing polyethylene tube.The method such as passing through copolymerization controls the molecular weight distribution of material resin, degree of branching and degree of crystallinity etc.
Realizing in process of the present invention, the present inventor finds at least there is following problem in prior art: the existing performance by improving material resin improves method complex process, the operational difficulty that the resistance to Slow Crack of polyethylene tube increases performance.
Summary of the invention
In order to solve above-mentioned technical problem, the invention provides the method that the resistance to Slow Crack of simple, the maneuverable raising polyethylene tube of a kind of technique increases performance.
Specifically, following technical scheme is comprised:
A kind of method improving polyethylene tube resistance to Slow Crack growth performance, the method is: in polyethylene tube machine-shaping process, polyethylene tube material resin is mixed with type low density polyethylene resin, then through melting, extrude, cool and obtain polyethylene tube; The mass ratio of described type low density polyethylene resin and described polyethylene tube material resin is 0.5 ‰ ~ 5 ‰; Wherein, described polyethylene tube material resin is be the polyvinyl resin that monomer polymerization obtains with ethene; Described type low density polyethylene resin is the density that ethene and alpha-olefin copolymer obtain is 0.910 ~ 0.925g/cm 3polyvinyl resin.
Preferably, the mass ratio of described type low density polyethylene resin and described polyethylene tube material resin is 1 ‰ ~ 4 ‰.
Preferably, the mass ratio of described type low density polyethylene resin and described polyethylene tube material resin is 1 ‰ ~ 3 ‰.
Preferably, the mass ratio of described type low density polyethylene resin and described polyethylene tube material resin is 2 ‰.
Preferably, the density of described type low density polyethylene resin is 0.917 ~ 0.923g/cm 3.
Preferably, in described type low density polyethylene resin, the mass ratio of described alpha-olefin and described ethene is 5 ~ 10%, and described alpha-olefin is selected from least one in 1-butylene, 1-hexene and 1-octene.
Preferably, the density of described polyethylene raw material resin is 0.955 ~ 0.965g/cm 3, melt flow rate (MFR) is 0.20 ~ 0.30g/10min.
Preferably, after described polyethylene tube material resin and described type low density polyethylene resin are mixed, according to following processing parameter processing polyethylene tube: extrusion capacity 670 ~ 690kg/h, processing temperature 190 ~ 200 DEG C, screw speed 115 ~ 125rpm, melt pressure 130 ~ 150bar, melt temperature 190 ~ 200 DEG C.
Preferably, the density of described polyethylene tube material resin is 0.940 ~ 0.955g/cm 3, melt flow rate (MFR) is 0.80 ~ 0.90g/10min.
Preferably, after described polyethylene tube material resin and described type low density polyethylene resin are mixed, according to following processing parameter processing polyethylene tube: extrusion capacity 640 ~ 660kg/h, processing temperature 180 ~ 190 DEG C, screw speed 120 ~ 130rpm, melt pressure 95 ~ 115bar; Melt temperature 200 ~ 210 DEG C.
The beneficial effect of the technological method that the embodiment of the present invention provides is:
The embodiment of the present invention improves polyethylene tube resistance to Slow Crack by adding type low density polyethylene resin in polyethylene tube machine-shaping process in material resin increases performance, and technique simply, easily operates.Because type low density polyethylene resin addition is little, therefore, adopt the embodiment of the present invention method can not change original polyethylene tube processing and forming technology condition and do not affect other performances of polyethylene tube prerequisite under, the resistance to Slow Crack of effective raising gained polyethylene tube increases performance, increase performance according to the resistance to Slow Crack of GB/T 18476-2001 to gained polyethylene tube to test, result shows, the resistance to Slow Crack of the polyethylene tube of the method gained of the embodiment of the present invention is adopted to increase nearly 2 times that performance is the polyethylene tube not adding type low density polyethylene resin.
Accompanying drawing explanation
In order to be illustrated more clearly in the technical scheme in the embodiment of the present invention, below the accompanying drawing used required in describing embodiment is briefly described, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.
Fig. 1 is the relation curve that LLDPE addition and the resistance to Slow Crack of polyethylene tube increase performance;
Fig. 2 is the relation curve of LLDPE addition and polyethylene tube elongation at break.
Embodiment
For making technical scheme of the present invention and advantage clearly, below in conjunction with accompanying drawing, embodiment of the present invention is described further in detail.
The embodiment of the present invention provides a kind of and improves the method that the resistance to Slow Crack of polyethylene tube increases performance, the method is: in polyethylene tube machine-shaping process, polyethylene tube material resin is mixed with type low density polyethylene resin, then through melting, extrude, cool and obtain polyethylene tube; Described type low density polyethylene resin be 0.5 ‰ ~ 5 ‰ with the mass ratio of described polyethylene tube material resin; Wherein, described polyethylene tube material resin is be the polyvinyl resin that monomer polymerization obtains with ethene; Described type low density polyethylene resin is the density that ethene and alpha-olefin copolymer obtain is 0.910 ~ 0.925g/cm 3polyvinyl resin.
Polyethylene tube is in life-time service process, and Slow Crack growth can cause the destruction of polyethylene tube, brings potential safety hazard.In the production of polyethylene tube, transport and process of deployment, cut or crackle is caused to be inevitable on polyethylene tube surface.Therefore, the resistance to Slow Crack being only improved polyethylene tube increases the work-ing life that performance could extend polyethylene tube, ensures the use safety of polyethylene tube.
LLDPE (Linear Low-Density Polyethylene, LLDPE) adopts the copolymerization of Ziegler-Natta initiator system to obtain by ethene and a small amount of alpha-olefin, and its molecular chain is linear structure, with a small amount of side base.LLDPE has lower degree of crystallinity and good resistance to impact shock and environmental stress crack resistance energy.Therefore, in polyethylene tube molding process, by type low density polyethylene resin and polyethylene tube material resin according to 0.5 ‰ ~ 5 ‰ ratio mix, crystalline structure and the degree of crystallinity of polyethylene tube material resin can be improved, carry out melting again, extrude, the step such as cooling, the resistance to Slow Crack of gained polyethylene tube increases performance and significantly improves compared with the polyethylene tube not adding LLDPE.And, because the addition of LLDPE is little, do not affect the processing and forming technology of existing polyethylene tube and other performances of polyethylene tube.
In the methods described above, the ratio of described type low density polyethylene resin and described polyethylene tube material resin is preferably 1 ‰ ~ 4 ‰, such as, can be 1.5 ‰, 1.8 ‰, 2 ‰, 2.2 ‰, 2.5 ‰, 3 ‰, 3.5 ‰ etc., and more preferably 1 ‰ ~ 3 ‰.Particularly when the ratio of described type low density polyethylene resin and described polyethylene tube material resin is 2 ‰, the resistance to Slow Crack of gained polyethylene tube increases nearly 2 times that performance is the polyethylene tube not adding LLDPE.
In the methods described above, the density of described type low density polyethylene resin preferably 0.917 ~ 0.923g/cm 3.
In the methods described above, in described type low density polyethylene resin, the mass ratio of described alpha-olefin and described ethene is preferably 5% ~ 10%, namely ethene and 5% ~ 10% alpha-olefin carry out copolymerization, can be such as 6%, 7%, 8%, 9% etc., in this proportional range, the side chain number of gained LLDPE molecule is moderate.Meanwhile, at least one in the preferred 1-butylene of described alpha-olefin, 1-hexene and 1-octene, can obtain the moderate LLDPE of branch lengths by ethene and above-mentioned alpha-olefin copolymer.Side chain number in polymer molecule and branch lengths can affect crystalline structure and the degree of crystallinity of polymer molecule, therefore, the LLDPE that the 1-butylene of 5% ~ 10%, 1-hexene, 1-octene or their arbitrary combination and ethylene copolymer obtain is conducive to crystalline structure and the degree of crystallinity of improving polyethylene raw material resin.Such as, LLDPE can select the model of China Petroleum & Chemical Co., Ltd. Maoming Branch to be the LLDPE of 7042.
In the methods described above, the not special requirement of apparatus and method of various arch types ldpe resin and polyethylene tube material resin, those skilled in the art can select voluntarily according to practical situation.Such as, near the opening for feed of existing forcing machine, small-sized mixer can be installed, utilize small-sized mixer to add LLDPE in forcing machine.
In the methods described above, LLDPE and polyethylene tube material resin are mixed rear carried out melting, extrudes, the processing condition of the step such as cooling do not have special requirement, existing polyethylene tube contour machining procedure can be adopted.Those skilled in the art can select according to practical situation equally voluntarily.
Polyethylene tube can be divided into PE32 level, PE40 level, PE63 level, PE80 level and PE100 level five grades according to intensity, wherein, minimum desired strength (the Minimum required strength of PE100 level polyethylene tube, MRS) for the minimum desired strength of 10MPa, PE80 level polyethylene tube is 8MPa.These two kinds of polyethylene tubes are used for the conveying of firing G&W at present, in use need to bear pressure, and therefore, the resistance to Slow Crack growth performance improving PE100 level and these two kinds of polyethylene tubes of PE80 level is particularly important.Therefore, the embodiment of the present invention provides the method comparatively preferably improving PE100 level and PE80 level polyethylene tube resistance to Slow Crack growth performance.
It is specific as follows,
(1) PE100 level polyethylene tube, material resin is density 0.955 ~ 0.965g/cm 3, melt flow rate (MFR) 0.20 ~ 0.30g/10min high density polyethylene(HDPE) (HDPE) resin.According to the method that the embodiment of the present invention provides, by LLDPE and above-mentioned raw materials mixed with resin evenly after process polyethylene tube according to following processing parameter: extrusion capacity 670 ~ 690kg/h, processing temperature 190 ~ 200 DEG C, screw speed 115 ~ 125rpm, melt pressure 130 ~ 150bar, melt temperature 190 ~ 200 DEG C;
(2) PE80 level polyethylene tube, material resin is density 0.940 ~ 0.955g/cm 3melt flow rate (MFR) is medium-density polyethylene (MDPE) resin of 0.80 ~ 0.90g/10min, according to the method that the embodiment of the present invention provides, by LLDPE and above-mentioned raw materials mixed with resin evenly after process polyethylene tube according to following processing parameter: extrusion capacity 640 ~ 660kg/h, processing temperature 180 ~ 190 DEG C, screw speed 120 ~ 130rpm, melt pressure 95 ~ 115bar; Melt temperature 200 ~ 210 DEG C.
In following examples, adopt and the method for small-sized mixer is installed to add LLDPE on the opening for feed side of existing forcing machine.By adjusting the screw speed of small-sized mixer, control the ratio of added LLDPE.
In following examples, the resistance to Slow Crack growth performance time to rupture of otch tubing hydrostatic test of gained polyethylene tube represents, the time not occurring to destroy is longer, shows that resistance to Slow Crack increases performance better.Test and carry out according to GB/T 18476-2001 (being called for short otch experiment).By the sample tubing circumference quartern, 18 ~ 22% rear profile milling nominal wall thickness at equally divided position become longitudinal cut, at operating pressure 0.92MPa, temperature 80 DEG C, carry out hydrostatic test, and in record process of the test, the time of destruction is not revealed, do not occurred to tubing.
Following examples resin used is as follows:
For processing the HE3490-LS type high-density polyethylene resin that the resin of PE100 level polyethylene tube is Borealis AG, density: 0.960g/cm 3, melt flow rate (MFR) (190 DEG C/5Kg): 0.25g/10min.
For processing the ME3440 type medium density polyethylene resin that the resin of PE80 level polyethylene tube is Borealis AG, density: 0.951g/cm 3, melt flow rate (MFR) (190 DEG C/5Kg): 0.85g/10min.
LLDPE: China Petroleum & Chemical Co., Ltd. Maoming Branch, model 7042, its performance perameter: density: 0.920g/cm 3, melt flow rate (MFR): 2.0g/10min.The mass ratio of 1-butylene and ethene is 9%.
Embodiment 1
The present embodiment provides a kind of resistance to Slow Crack improving PE100SDR11 type polyethylene tube to increase the method for performance, by type low density polyethylene resin by the small-sized mixer on forcing machine opening for feed side and HE3490-LS type high-density polyethylene resin respectively according to 0 ‰, 1 ‰, 2 ‰, 3 ‰ and 4 ‰ ratio mix after carry out melting, extrude, the step such as cooling obtains PE100SDR11 type polyethylene tube.
Main process parameter is as follows:
Extrusion capacity 680kg/h, processing temperature 190 ~ 200 DEG C, screw speed 120rpm, melt pressure 139bar, melt temperature 195 DEG C;
Increase performance to the resistance to Slow Crack of gained polyethylene tube to test, acquired results is in table 1 and Fig. 1.
Table 1 Different L LDPE addition gained PE manages resistance to Slow Crack and increases performance
As can be seen from Table 1, when the addition of LLDPE reaches 2 ‰, the resistance to Slow Crack growth performance of gained polyethylene tube is best, 80 DEG C, in the hydrostatic test of 0.92MPa, 2135h can be kept not destroy, and the time that destruction does not occur is nearly 2 times of the polyethylene tube not adding type low density polyethylene resin.When the addition of LLDPE continues to increase, the resistance to Slow Crack that still can improve polyethylene tube increases performance, but the time not occurring to destroy reduces to some extent.
Test result is carried out as shown in table 2 and Fig. 2 according to the elongation at break of GB15558.1 to the polyethylene tube of different type low density polyethylene resin addition gained.
Table 2 Different L LDPE addition gained PE pipe elongation at break
As can be seen from Table 2, along with the increase of type low density polyethylene resin addition, the elongation at break of gained polyethylene tube increases to some extent.
Simultaneously, when being 2 ‰ according to GB15558.1 to type low density polyethylene resin addition, other performances of the PE100SDR11 type polyethylene tube of gained are tested, result shows, the complete conformance with standard requirement of other performance index, and significant difference is not had compared with the polyethylene tube not adding type low density polyethylene resin.Therefore, type low density polyethylene resin is added in PE100 level polyethylene tube material resin, do not changing existing PE100SDR11 type polyethylene tube fabrication process condition and under not affecting the prerequisite of other performances of gained polyethylene tube, significantly improving the resistance to Slow Crack growth performance of gained polyethylene tube.
Embodiment 2
The present embodiment provides a kind of resistance to Slow Crack improving PE80SDR11 type polyethylene tube to increase the method for performance, by type low density polyethylene resin by the small-sized mixer on forcing machine opening for feed side and ME3440 type medium density polyethylene resin respectively according to 0 ‰, 1 ‰, 2 ‰, 3 ‰ and 4 ‰ ratio mix after carry out melting, extrude, the step such as cooling obtains PE80SDR11 type polyethylene tube.
Main process parameter is as follows:
Extrusion capacity 650kg/h, processing temperature 180 ~ 190 DEG C, screw speed 125rpm, melt pressure 105bar, melt temperature 202 DEG C.
Increase performance to the resistance to Slow Crack of gained polyethylene tube to test, acquired results is in table 3 and Fig. 1.
Table 3 Different L LDPE addition gained PE manages resistance to Slow Crack and increases performance
As can be seen from Table 3, when the addition of type low density polyethylene resin reaches 2 ‰, the resistance to Slow Crack growth performance of gained polyethylene tube is best, 80 DEG C, in the hydrostatic test of 0.92MPa, 2020h can be kept not destroy, and the time that destruction does not occur is nearly 2 times of the polyethylene tube not adding LLDPE.When the addition of type low density polyethylene resin continues to increase, the resistance to Slow Crack that still can improve polyethylene tube increases performance, but the time not occurring to destroy reduces to some extent.
Test result is carried out as shown in table 4 and Fig. 2 according to the elongation at break of GB15558.1 to the polyethylene tube of different type low density polyethylene resin addition gained.
Table 4 Different L LDPE addition gained PE pipe elongation at break
As can be seen from Table 4, along with the increase of type low density polyethylene resin addition, the elongation at break of gained polyethylene tube increases to some extent.
Simultaneously, when being 2 ‰ according to GB15558.1 to type low density polyethylene resin addition, other performances of the PE80SDR11 type polyethylene tube of gained are tested, result shows, the complete conformance with standard requirement of other performance index, and significant difference is not had compared with the polyethylene tube not adding type low density polyethylene resin.Therefore, type low density polyethylene resin is added in the material resin of PE80 level polyethylene tube, do not changing existing PE80SDR11 type polyethylene tube fabrication process condition and under not affecting the prerequisite of other performances of gained polyethylene tube, significantly improving the resistance to Slow Crack growth performance of gained polyethylene tube.
To sum up, the method of the embodiment of the present invention by type low density polyethylene resin is mixed with polyethylene tube material resin, do not changing existing polyethylene tube fabrication process condition and under not affecting the prerequisite of other performances of gained polyethylene tube, the resistance to Slow Crack significantly improving gained polyethylene tube increases performance, extend polyethylene tube work-ing life, ensure the use safety of polyethylene tube.
The above is only understand technical scheme of the present invention for the ease of those skilled in the art, not in order to limit the present invention.Within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (10)

1. one kind is improved the method that the resistance to Slow Crack of polyethylene tube increases performance, it is characterized in that, described method is: in polyethylene tube machine-shaping process, mixed by polyethylene tube material resin with type low density polyethylene resin, then through melting, extrude, cool and obtain polyethylene tube; The mass ratio of described type low density polyethylene resin and described polyethylene tube material resin is 0.5 ‰ ~ 5 ‰;
Described polyethylene tube material resin is take ethene as the polyvinyl resin that monomer polymerization obtains;
Described type low density polyethylene resin is the density that ethene and alpha-olefin copolymer obtain is 0.910 ~ 0.925g/cm 3polyvinyl resin.
2. method according to claim 1, is characterized in that, the mass ratio of described type low density polyethylene resin and described polyethylene tube material resin is 1 ‰ ~ 4 ‰.
3. method according to claim 2, is characterized in that, the mass ratio of described type low density polyethylene resin and described polyethylene tube material resin is 1 ‰ ~ 3 ‰.
4. method according to claim 3, is characterized in that, the mass ratio of described type low density polyethylene resin and described polyethylene tube material resin is 2 ‰.
5. method according to claim 1, is characterized in that, described type low density polyethylene resin density is 0.917 ~ 0.923g/cm 3.
6. method according to claim 1 or 5, it is characterized in that, in described type low density polyethylene resin, the mass ratio of described alpha-olefin and described ethene is 5% ~ 10%, and described alpha-olefin is selected from least one in 1-butylene, 1-hexene and 1-octene.
7. method according to claim 1, is characterized in that, the density of described polyethylene raw material resin is 0.955 ~ 0.965g/cm 3, melt flow rate (MFR) is 0.20 ~ 0.30g/10min.
8. method according to claim 7, it is characterized in that, after described polyethylene tube material resin and described type low density polyethylene resin are mixed, according to following processing parameter processing polyethylene tube: extrusion capacity 670 ~ 690kg/h, processing temperature 190 ~ 200 DEG C, screw speed 115 ~ 125rpm, melt pressure 130 ~ 150bar, melt temperature 190 ~ 200 DEG C.
9. method according to claim 1, is characterized in that, the density of described polyethylene tube material resin is 0.940 ~ 0.955g/cm 3, melt flow rate (MFR) is 0.80 ~ 0.90g/10min.
10. method according to claim 9, it is characterized in that, after described polyethylene tube material resin and described type low density polyethylene resin are mixed, according to following processing parameter processing polyethylene tube: extrusion capacity 640 ~ 660kg/h, processing temperature 180 ~ 190 DEG C, screw speed 120 ~ 130rpm, melt pressure 95 ~ 115bar; Melt temperature 200 ~ 210 DEG C.
CN201510160113.2A 2015-04-07 2015-04-07 A kind of method improving polyethylene tube resistance to slow crack growth performance Active CN104788782B (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109422947A (en) * 2017-08-29 2019-03-05 中国石油天然气股份有限公司 Multimodal polyethylene and process for its preparation

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1476464A (en) * 2000-10-27 2004-02-18 ���з����о���˾ Polyethylene pipe resins and production thereof
CN100551962C (en) * 2004-04-03 2009-10-21 博里利斯技术有限公司 Pressureless polymer pipe
CN103958595A (en) * 2012-01-24 2014-07-30 博里利斯股份公司 Polyethylene composition with improved low temperature pressure resistance

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1476464A (en) * 2000-10-27 2004-02-18 ���з����о���˾ Polyethylene pipe resins and production thereof
CN100551962C (en) * 2004-04-03 2009-10-21 博里利斯技术有限公司 Pressureless polymer pipe
CN103958595A (en) * 2012-01-24 2014-07-30 博里利斯股份公司 Polyethylene composition with improved low temperature pressure resistance

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109422947A (en) * 2017-08-29 2019-03-05 中国石油天然气股份有限公司 Multimodal polyethylene and process for its preparation

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