CN106633323A

CN106633323A - Polyethylene composition and durable film

Info

Publication number: CN106633323A
Application number: CN201510712914.5A
Authority: CN
Inventors: 施红伟; 高达利; 殷建军; 乔金樑; 张师军; 郭梅芳; 于鲁强; 黄红红; 李汝贤; 王良诗
Original assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Current assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Priority date: 2015-10-28
Filing date: 2015-10-28
Publication date: 2017-05-10
Anticipated expiration: 2035-10-28
Also published as: CN106633323B

Abstract

The invention provides a polyethylene composition and a durable film. The polyethylene composition is prepared from linear low density polyethylene prepared by copolymerizing ethylene and alpha-olefin with an anti-aging assistant, wherein the weight-average molecular weight Mw of the polyethylene composition is 100,000g/mol to 180,000g/mol; Mw/Mn is 4.0 to 8.0; Mz/Mw is 4.0 to 6.0; Mz+1/Mw is 4.5 to 12.5. When the polyethylene composition is used for preparing a polyethylene film by a flat film strength method, the polyethylene composition has a high stretching ratio, a high film forming rate, very high forming performance, and superior durability.

Description

A kind of polyethylene composition and durable membrane

Technical field

The present invention relates to a kind of polyethylene composition and durable membrane.

Background technology

Biaxially-oriented polyethylene (Biaxially Oriented Polyethylene, BOPE) film is that have The thin-film material of polyethylene (PE) the resin Jing stretch processes shaping of special molecular structure.In BOPE In the molding process of film, after the process of film drawn, PE macromolecular chains and crystalline texture occur It is height-oriented, so as to significantly improve the tensile strength of film, tension fracture elongation rate is reduced, and make Film mist degree is lower, glossiness is higher and it is transparent more preferably.Additionally, blowing with the extrusion of prior art The polyethylene film product that modeling technique is prepared with extrusion casting technique is compared, and BOPE films have mechanics strong The advantages such as degree height, puncture resistant and shock resistance are good, excellent optical performance, environmental protection and energy saving.Therefore, BOPE films can be widely used in packaging bag, again packaging bag, Vacuum Heat sealer, low temperature packaging film, multiple Close the aspects such as film, medical and sanitary products, plastic film for agricultural use.

The biaxial tension processing method of the plastic sheeting for adopting at present has Flat film strength and envelope pulling method. Flat film strength has been applied in polypropylene (PP), polyamide (PA), polyethylene terephthalate Etc. (PET) in the processing of thin-film material, technique is more ripe.Compared with envelope pulling method, flat film draws Stretch stretching ratio big (cross directional stretch multiplying power is up to more than 10 times), fast (the highest winding of shaping speed of method Speed is up to hundreds of ms/min), production efficiency it is high and the mechanical strength of the film for obtaining, optical Can be with thickness evenness more preferably, but film forming is affected significantly by process condition fluctuations, film stretching Difficulty of processing is big, for film raw material has higher requirement.Existing Biaxially-oriented polyethylene raw material base This is only applicable to envelope pulling method and prepares BOPE films, and existing these polyethylene raw materials are adopted Flat film strength prepare BOPE films when, exist film forming poor (draw speed and stretching ratio are very low), Easily there is the defect for rupturing in film, i.e. be not suitable for preparing film using Flat film strength substantially.Therefore, In order to make full use of the above-mentioned advantage of Flat film strength, need a kind of good film-forming property of exploitation badly at present and film is not allowed Easily there is the polyethylene raw material that BOPE films are prepared suitable for Flat film strength of rupture.

Biaxial tension polyethylene film as agricultural film when warmhouse booth film is particularly, because its tool There is the characteristic of high-strength and high-transparent, with obvious advantage.But due to the thickness of Biaxial tension polyethylene film Degree is thinner than conventional blown film, and its durability may be subject to a certain degree of impact.Therefore it is high durable Property is more notable for the importance of Biaxial tension polyethylene film.

The content of the invention

The invention aims to be overcome existing polyethylene raw material is prepared using Flat film strength poly- Have that film forming is poor during vinyl film, film is easily broken and (is not suitable for being prepared using Flat film strength thin Film) and the not enough defect of durability, and provide a kind of new polyethylene composition and by the polyethylene composition Durable membrane made by thing.

Specifically, the polyethylene composition that the present invention is provided contains the line by ethene and alhpa olefin copolymerization Property low density polyethylene (LDPE) and anti-aging auxiliary agent, wherein, the weight average molecular weight of the polyethylene composition Mw is the g/mol of 100,000 g/mol-18 ten thousand, and Mw/Mn is 4.0-8.0, and Mz/Mw is 4.0-6.0, Mz+1/Mw is 4.5-12.5.

The durable membrane that the present invention is provided at least includes one layer by gathering that above-mentioned polyethylene composition is formed Pvdf layer.

The present inventor has found after further investigation, in the mistake that film is prepared using biaxial tension method Cheng Zhong, if the molecular weight distribution of polyethylene composition is narrow, possibly cannot carry out biaxial tension processing； And if the molecular weight distribution of polyethylene composition is wide, then may cause the in uneven thickness and nothing of film Method meets the problem of follow-up use requirement.And the polyethylene composition that the present invention is provided is by weight average molecular weight Mw is controlled in the g/mol of 100,000 g/mol-18 ten thousand, while Mw/Mn is controlled in 4.0-8.0, Mz/Mw Control is controlled in 4.5-12.5 in 4.0-6.0, Mz+1/Mw, and the polyethylene composition is adopted into biaxial tension Method has the advantages that stretching ratio is big, rate of film build is high when preparing film, disclosure satisfy that Flat film strength pair The high requirement of polyethylene raw material.Further, since the presence of anti-aging auxiliary agent can also in polyethylene composition Enough make the film for obtaining that there is excellent durability, great prospects for commercial application.

A preferred embodiment of the invention, drenches when the polyethylene composition is heated up by analytic type The temperature rising elution curve that washing-grading method is measured includes high temperature drip washing peak and low temperature drip washing peak, and the high temperature drenches The temperature for washing peak is 90-105 DEG C, and the temperature at the low temperature drip washing peak is 50-90 DEG C, with high temperature pouring On the basis of washing the gross area at peak and low temperature drip washing peak, the area at the high temperature drip washing peak is not higher than 60%, institute When the area for stating low temperature drip washing peak is not less than 40%, the polyethylene composition is with preferable film forming and resistance to Long on the basis of property, the film prepared by the polyethylene composition also has more excellent optical Energy and mechanical property, such as mist degree is relatively low, glossiness is higher, intensity and puncture-resistant ability are preferable.

Another kind of preferred embodiment of the invention, when component A, component B and component C Molecular weight distributing index be satisfied by M_w/M_nWhen≤4.5, the polyethylene composition is with preferable film forming Property and durability on the basis of, the film prepared by the polyethylene composition also has higher intensity And puncture resistance.

Another kind of preferred embodiment of the invention, when component A, group in the polyethylene composition Divide the density p of B and component C_A、ρ_BAnd ρ_CBetween relation meet -0.04≤ρ_A-ρ_B≤ 0.02 and -0.04 ≤ρ_A-ρ_CWhen≤0.02, the polyethylene composition on the basis of with preferable film forming and durability, by The film that the polyethylene composition is prepared also has tensile strength and punctured resistance is high and mist degree is low Advantage.

Other features and advantages of the present invention will be described in detail in subsequent specific embodiment part.

Description of the drawings

Accompanying drawing is, for providing a further understanding of the present invention, and to constitute the part of specification, with Detailed description below is used to explain the present invention together, but is not construed as limiting the invention. In accompanying drawing：

Fig. 1 is the structural representation for preparing the multiple reactor shunting means of polyethylene composition.

Description of reference numerals

1- first reactors；2- second reactors；The reactors of 3- the 3rd；4- solid-liquids (gas) separator； 5- homogenization silos；6- melt pelletization systems.

Specific embodiment

The specific embodiment of the present invention is described in detail below.It should be appreciated that this place is retouched The specific embodiment stated is merely to illustrate and explains the present invention, is not limited to the present invention.

The polyethylene composition that the present invention is provided contains the linea low density by ethene and alhpa olefin copolymerization Polyethylene and anti-aging auxiliary agent, wherein, weight average molecular weight Mw of the polyethylene composition is 10 The g/mol of ten thousand g/mol-18 ten thousand, the preferably g/mol of 100,000 g/mol-15 ten thousand；And Mw/Mn is 4.0-8.0, Mz/Mw is 4.0-6.0, and Mz+1/Mw is 4.5-12.5.In the present invention, Mw, Mn, Mz, Mz+1 is measured using high-temperature gel permeation chromatography instrument (GPC).

According to the polyethylene composition that the present invention is provided, the polyethylene composition is by analytic type temperature rising elution The temperature rising elution curve that classification (TREF) method is measured includes high temperature drip washing peak and low temperature drip washing peak, and institute The temperature for stating high temperature drip washing peak is preferably 90-105 DEG C, more preferably 95-100 DEG C；The low temperature drip washing peak Temperature be preferably 50-90 DEG C, more preferably 60-90 DEG C.Additionally, the area mistake at the high temperature drip washing peak Conference causes the optical property of the biaxially oriented film prepared by the polyethylene composition to be deteriorated, and low The area at warm drip washing peak is excessive, can cause the biaxially oriented film prepared by the polyethylene composition Mechanical property be deteriorated.Therefore, in order that the polyethylene composition is with good filming performance On the basis of endurance quality, also there is preferable optical property and mechanical property simultaneously, it is preferable that with On the basis of the gross area at the high temperature drip washing peak and low temperature drip washing peak, the area at the high temperature drip washing peak is not high In 60%, the area at the low temperature drip washing peak is not less than 40%；It is highly preferred that with the high temperature drip washing peak On the basis of the gross area at low temperature drip washing peak, the area at the high temperature drip washing peak is not higher than 50%, described low The area at warm drip washing peak is not less than 50%；Most preferably, with the high temperature drip washing peak and low temperature drip washing peak On the basis of the gross area, the area at the high temperature drip washing peak is 5-45%, and the area at the low temperature drip washing peak is 55-95%.

As a rule, if the melt temperature of polyethylene composition is too high, follow-up curtain coating processing can be caused During slab curing rate it is too fast, be unfavorable for be cast slab it is smooth；And if polyethylene composition Melt temperature is too low, then can cause subsequently to be cast in process that slab curing rate is slower, is both unfavorable for The raising of working (machining) efficiency, also results in film strength too low.Therefore, in order that the polyethylene composition Thing on the basis of with good filming performance and endurance quality, also with preferably curtain coating processability with And higher mechanical strength, it is preferable that the polyethylene composition is by differential scanning calorimetry (DSC) The melting peak temperature for measuring is 100-130 DEG C, more preferably 105-128 DEG C.

The present invention does not have to the content of the construction unit derived from the LLDPE from alhpa olefin Especially limit, for example, with ethylene unit unit in the LLDPE and derived from alpha alkene On the basis of the total content of the construction unit of hydrocarbon, the content of the construction unit of the derived from alpha alkene can be 0.5-20mol%, preferably 2.0-10mol%.In the present invention, the ethylene unit unit is referred to by second Alkene is polymerized the construction unit to be formed；The construction unit of the derived from alpha alkene is referred to by alpha-olefin polymerization shape Into construction unit.

A preferred embodiment of the invention, the LLDPE has component A, group Divide B and component C；Component A temperature be 190 DEG C, load be 2.16kg under melt index MI_AFor 0.01-2g/10min, density p_AFor 0.880-0.936g/cm³；Component B is in temperature 190 DEG C, load be 2.16kg under melt index MI_BFor 2.1-14.9g/10min, density p_BFor 0.910-0.930g/cm³；Component C temperature be 190 DEG C, load be that melting under 2.16kg refers to Number MI_CFor 15-150g/10min, density p_CFor 0.880-0.930g/cm³。

According to the present invention provide polyethylene composition, it is preferable that component A temperature be 190 DEG C, Load is melt index MI under 2.16kg_AFor 0.01-1.5g/10min, component B is in temperature 190 DEG C, load be 2.16kg under melt index MI_BFor 3-10g/10min, component C is in temperature It is melt index MI under 2.16kg to spend for 190 DEG C, load_CFor 15-100g/10min.It is highly preferred that Component A temperature be 190 DEG C, load be 2.16kg under melt index MI_AFor 0.01-1g/10min, component B temperature be 190 DEG C, load be 2.16kg under melt index MI_BFor 3-5g/10min, component C temperature be 190 DEG C, load be that melting under 2.16kg refers to Number MI_CFor 20-60g/10min.

In the present invention, the melt index is surveyed according to method specified in GB/T3682-2000 It is fixed, wherein, test condition includes that temperature is 190 DEG C, and load is 2.16kg.

According to the polyethylene composition that the present invention is provided, it is preferable that the density p of component A_AFor 0.910-0.930g/cm³, the density p of component B_BFor 0.913-0.928g/cm³, component C Density p_CFor 0.905-0.928g/cm³.It is highly preferred that the density p of component A_AFor 0.915-0.926g/cm³, the density p of component B_BFor 0.913-0.924g/cm³, component C Density p_CFor 0.910-0.926g/cm³.It is particularly preferred that component A, group in the polyethylene composition Divide the density p of B and component C_A、ρ_BAnd ρ_CBetween relation meet -0.04≤ρ_A-ρ_B≤ 0.02, and -0.04 ≤ρ_A-ρ_C≤ 0.02, the polyethylene composition for so enabling to is with preferable filming performance and resistance to Long on the basis of performance, also with very high tensile strength and punctured resistance and relatively low mist degree.

Component A, component B and component C are the linear low density polyethylene of ethylene/alpha-olefin copolymerization Alkene, wherein, linear structure is referred to only containing short-chain branch structure in strand, and does not contain long branched chain structure And cross-linked structure, it is determined by polymerized monomer and polymerization process condition, specially those skilled in the art Known, therefore not to repeat here.

According to the polyethylene composition that the present invention is provided, in order that the polyethylene composition for arriving is with good On the basis of good filming performance and endurance quality, also with preferable mechanical property and optical property, preferably Ground, in the polyethylene composition, the mass fraction W of component A_AFor 25-90 weight portions, The mass fraction W of component B_BFor 0.1-10 weight portions, the mass fraction W of component C_CFor 10-75 weight portions；It is highly preferred that in the polyethylene composition, the mass fraction of component A W_AFor 30-80 weight portions, the mass fraction WB of component B is 0.5-8 weight portions, the component The mass fraction W of C_CFor 20-70 weight portions；It is highly preferred that in the polyethylene composition, institute State the mass fraction W of component A_AFor 55-80 weight portions, the mass fraction W of component B_BFor 2-8 Weight portion, the mass fraction W of component C_CFor 20-55 weight portions.Further, the component The mass fraction W of A_AWith the mass fraction W of component C_CWith melt index MI of component A_ARelation It is preferred that meeting 5.2 × 1gMI_A+11.6≥W_A/W_C≥0.9×1gMI_A+ 2.1, more preferably meet 2.9 × 1gMI_A+6.8≥W_A/W_C≥1.1×1gMI_A+ 2.7, the polyethylene composition is so enabled to flat There is the rate of extension of bigger stretching ratio and Geng Gao in embrane method film biaxial tension processing.

According to the polyethylene composition that the present invention is provided, particularly preferably, the polyethylene composition is in temperature Spend for 190 DEG C, load be 2.16kg under melt index be 0.1-20g/10min, more preferably 0.5-10g/10min, most preferably 0.5-3g/10min；The polyethylene composition temperature be 190 DEG C, It is 0.880-0.940g/cm that load is the density under 2.16kg³, preferably 0.910-0.930g/cm³. By component A with above-mentioned particular melt index and density, component B and component C and anti-aging auxiliary agent On the basis of using cooperatively, by the overall melt index control of the polyethylene composition above-mentioned preferred In the range of, the polyethylene composition that enables to have simultaneously very excellent film forming, durability, Tensile strength and punctured resistance and relatively low mist degree.

According to the polyethylene composition that the present invention is provided, it is preferable that component A, component B and component The molecular weight distributing index of C is satisfied by M_w/M_n≤ 4.5, more preferably meet 2.0≤M_w/M_n≤4.2.Specifically Ground, in order to obtain component A with above-mentioned molecular weight distribution, component B and component C, component A, Component B and component C are obtained using metallocene catalyst polymerisation.Wherein, the metallocene catalyst Species can be this area conventional selection, its generally by metallocene compound and organo-aluminum compound with And optional electron donor composition, specifically it is known to the skilled person, therefore not to repeat here.This Bright inventor is had found after further investigation, will be obtained using metallocene catalyst polymerisation with above-mentioned Component A of melt index and density, component B and component C are used cooperatively with anti-aging auxiliary agent, are obtained Film on the basis of with good filming performance and endurance quality, also with very high puncture Can, it is highly suitable for packaging material.

Alhpa olefin in component A, component B and component C is each independently C₃-C₂₀In alkene At least one.From the ready availability angle of raw material, in component A, component B and component C Alhpa olefin be preferably propylene, 1- butylene, 2- butylene, 3-methyl-1-butene, 4- methyl isophthalic acids-butylene, 1- Amylene, 3- Methyl-1-pentenes, 4-methyl-1-pentene, 3,3- dimethyl -1- amylenes, 3,4- dimethyl -1- penta Alkene, 4,4- dimethyl -1- amylenes, 1- hexenes, 4- methyl isophthalic acids-hexene, 5- methyl isophthalic acids-hexene, 1- heptene, 2- heptene, 1- octenes, 1- decene, 1- 12 (carbon) alkene, 1- 14 (carbon) alkene, 1- 16 (carbon) alkene, 1- ten At least one in eight (carbon) alkene and 1- 20 (carbon) alkene, more preferably 1- butylene, 1- hexenes and 1- octenes In at least one.

The anti-aging auxiliary agent various can improve polyethylene composition ageing resistace for existing Material, for example, can in UV absorbers, energy quencher and radical scavenger at least It is a kind of.Count by 100 weight portions of the gross weight of component A, component B and component C, it is described anti- The content of aging auxiliary agent can be 0.01-5 weight portions.These anti-aging auxiliary agents can be commercially available. For example, the UV absorbers can be at least one in trade name UV-531, UV-326 etc.. Count by 100 weight portions of the gross weight of component A, component B and component C, the ultraviolet light is inhaled The content for receiving agent can be 0.01-1 weight portions, preferably 0.1-0.3 weight portions.Described energy is quenched Agent can be organic nickel compound, such as：Double (3,5- di-tert-butyl-4-hydroxyl benzyl phosphonic acids mono ethyl ester) nickel (business The name of an article be Irgastab 2002), 2,2- thiobis (4- t-octyl phenol epoxides) nickel-n-butylamine complex compound (business Name of an article UV-1084), 2,2- thiobis (4- t-octyl phenol epoxides) nickel (AM-101), the sulphur of dioctyl two For carbamic acid nickel (AM-108), N, in N- nickel dibutyl dithiocarbamates (NBC) at least It is a kind of.Organic nickel complex because of heavy metal ion toxicity problem, with component A, component B and component The gross weight of C is 100 weight portion meters, and the consumption of organic nickel compound energy quencher should be controlled Between 0.01-0.04 weight portions.The radical scavenger can be hindered amine light stabilizer, such as： Tinuvin123、Tinuvin622、Tinuvin791、GW-480、GW-540、GW-544、Chimassorb At least one in 944 grades.With the gross weight of component A, component B and component C as 100 weight Part meter, the content of the radical scavenger can be 0.01-1 weight portions, preferably 0.05-0.3 weight Part.

According to the polyethylene composition that the present invention is provided, it is preferable that the polyethylene composition is also containing profit Lubrication prescription, can so improve the extrusion processing characteristics of the polyethylene composition.The species of the lubricant Can be that the conventional of this area selects with consumption, for example, the lubricant can be selected from polyethylene glycol (PEG) series lubricant agent, fluoropolymer series lubricant agent, silicone lubricant, aliphatic alcohols lubrication Agent, fatty acid lubricant, fatty acid ester type emollients, stearic amide series lubricant agent, aliphatic acid gold In category soaps lubricant, alkane and oxidation of alkanes series lubricant agent and micro-and nano-particles series lubricant agent at least one Kind.Specifically, the PEG series lubricant agents for example can be that molecular weight divides for the PEG of 500-50000 Son, it can be through end-blocking, grafting, crosslinking Treatment, it is also possible to change through other chemical modifications or physics Property.The fluoropolymer series lubricant agent for example can be polytetrafluoroethylene (PTFE), Kynoar, poly- hexafluoro At least one in propylene etc., or other unimodal or multimodal fluoropolymers and crystallization or half The fluoropolymer of crystallization.The organo-silicic oil can for it is existing it is various with carbon, silicon atom for divide Sub- main chain, the oligomer or oligomer with organic groups such as methyl, phenyl, alkoxyl, vinyl is as side The compound of chain.The fatty alcohol type emollients for example can be soft fat alcohol, tallow alcohol, tallow At least one in fat alcohol etc..The fatty acid lubricant for example can be hard with stearic acid and/or 12- hydroxyls Resin acid.The fatty acid ester type emollients for example can be butyl stearate, stearic acid list glyceride, palm fibre At least one in palmitic acid acid cetyl ester, tearyl base ester etc..The stearic amide class profit Lubrication prescription for example can be stearic amide, oleamide, erucyl amide, n, n- ethylene bis stearic acid amides Etc. (EBS) at least one in.The fatty acid metal soaps lubricant for example can for lead stearate, At least one in calcium stearate, magnesium stearate, synthesis calcium acetate etc..The alkane and oxidation of alkanes class Lubricant for example can be atoleine, solid paraffin, Tissuemat E, polypropylene wax, ethylene oxide wax At least one in.The micro-and nano-particles series lubricant agent for example can be that powdered rubber and/or silica gel are micro- Grain.Additionally, counting by 100 weight portions of the gross weight of component A, component B and component C, institute The content for stating lubricant can be 0.05-5 weight portions, preferably 0.1-3 weight portions, more preferably 0.1-0.5 Weight portion.

Additionally, can also contain in the polyethylene composition existing various in polyvinyl resin, poly- second Other auxiliary agents being usually used in alkene film, and the polyethylene that described other auxiliary agents will not be provided the present invention The stretching film forming of composition, durability, mechanical property and optical property have adverse effect on.It is described Other auxiliary agents are included but is not limited to：In antioxidant, slipping agent, antistatic additive, antitack agent etc. at least one Kind.Additionally, the consumption of other auxiliary agents can be the conventional selection of this area, to this this area skill Art personnel can know that therefore not to repeat here.

The polyethylene composition can be prepared according to existing various methods, for example, first be made respectively Standby component A, component B and component C, then by component A, component B and component C with it is anti-ageing Change auxiliary agent and the selective lubricant for containing and other auxiliary agents enter according to proportioning in mechanical mixing equipment Row mechanical mixture, being subsequently adding in melt blending equipment carries out melt blending.Wherein, the mechanical mixture Equipment can be for example homogenizer, kneader etc..The melt blending equipment can be for example double spiral shells Bar extruder, single screw extrusion machine, mill, banbury etc..

A preferred embodiment of the invention, the polyethylene composition is as shown in Figure 1 more Prepare in reactor shunting means, the multiple reactor shunting means include first reactor 1, the Two reactors 2, the 3rd reactor 3, solid-liquid (gas) separator 4, homogenization silo 5 and melt pelletization System 6, wherein, the first reactor 1, the reactor 3 of second reactor 2 and the 3rd are connected in parallel, The number of solid-liquid (gas) separator 4 is three, respectively with first reactor 1, second reactor 2 connect with the 3rd reactor 3, component A that prepared by first reactor 1, are made by second reactor 2 Standby component B and component C that prepared by the 3rd reactor 3 are respectively different at solid-liquid (gas) It is separated in separator 4, is then pressed component A Jing after being separated, component B and component C Ratio is delivered in homogenization silo 5 and is mixed together uniformly with anti-aging auxiliary agent and other additives, it Sending in melt pelletization system 6 afterwards carries out extruding pelletization.Wherein, between the polymerization in each reactor can be Have a rest and be polymerized, or continuous polymerization.When using multiple reactor parallel polymerization, W hereinafter_A、 W_BAnd W_CFor yield in unit time of each component in respective reaction device.

The durable membrane can have single layer structure, it is possible to have sandwich construction.When described durable Property film when being sandwich construction, at least sandwich layer (usually thickness maximum layer) is by the polyethylene group The polyethylene layer that compound is formed.For example, the durable membrane can have upper epidermis, sandwich layer and following table The composite construction of layer, and at least described sandwich layer is the polyethylene layer formed by the polyethylene composition.It is logical For often, the thickness of the durable membrane can be 10-200 μm, preferably 10-100 μm.Additionally, When the durable membrane has the composite construction of upper epidermis, sandwich layer and layer, the upper epidermis and The thickness of layer is each independently the 1-25% of durable membrane's thickness, preferably 1-10%, More preferably 1-5%.

Additionally, the durable membrane can be monodirectional tension film, or biaxially oriented film, Preferably bidirectional oriented film, the biaxial tension for more preferably being prepared by flat film biaxial tension method is thin Film.

The process for preparing biaxially oriented film using flat film biaxial tension method is known to the skilled person. Specifically, first above-mentioned polyethylene composition is added in casting apparatus carries out extrusion curtain coating slab, then The slab for obtaining is carried out into drawing and forming in film biaxial tension equipment.During extrusion curtain coating, The structure of the film that slab die head can be obtained as needed is selected, and for example, has list when needing to obtain During the film of Rotating fields, single layer die can be adopted；When the film (tool for needing acquisition with sandwich construction Have the film of upper epidermis, sandwich layer and layer three-decker) when, die head can be combined using sandwich construction, And in the compound die head of the sandwich construction at least one of which (sandwich layer) with equipped with above-mentioned polyethylene composition Extruder hopper is connected, and at least one of which (sandwich layer) in the film for so enabling to is by above-mentioned poly- The polyethylene layer that vinyl composition is formed.In extrusion, extrusion temperature can be 160-260 DEG C, The temperature of curtain coating chilling roller can be 15-85 DEG C.Additionally, the biaxial tension can be using synchronous farad Stretching process (carries out film longitudinal direction (MD) and laterally (TD) stretching) simultaneously, it would however also be possible to employ point Footwork drawing process (first carries out film longitudinal stretching, then carries out film cross directional stretch).The synchronization Method stretching concrete technology be：The slab is Jing after being fully warmed-up, while carrying out the drawing of vertical and horizontal direction Stretch, wherein, preheating temperature can be 75-165 DEG C, and draft temperature can be 75-160 DEG C, longitudinal direction (MD) Stretching ratio >=4 times, horizontal (TD) stretching ratio >=5 times, cross directional stretch speed >=50%/s.Institute State the method for fractional steps stretching concrete technology be：The slab carries out longitudinal stretching Jing after being fully warmed-up, first, it After carry out cross directional stretch, wherein, preheating temperature can be 65-158 DEG C, and draft temperature can be 65-155 DEG C, longitudinal direction (MD) stretching ratio >=4 times, horizontal (TD) stretching ratio >=5 times, laterally Rate of extension >=50%/s.Additionally, setting process can not be carried out after film drawing and forming, it is also possible to enter Row annealing setting is processed.When annealing setting process is carried out, film setting treatment temperature can be 80-165℃.Finally, film can also carry out surface corona process, cutting edge and winding process, final to obtain To durable membrane of the present invention.

The durable membrane that the present invention is provided has that preferable film forming and stretching ratio be big, rate of extension It is high.During the biaxially oriented film is prepared using Flat film strength, as described above, described resistance to Longitudinal direction (MD) stretching ratio >=4 times of long property film；Horizontal (TD) stretching ratio >=5 times.Draw Stretch that multiplying power is bigger, then the mechanical strength of durable membrane is higher.Horizontal (TD) of the durable membrane Rate of extension >=50%/s, preferably 60-100%/s, so ensure that the continuous production of industrialization.

The durable membrane that the present invention is provided has higher mechanical strength and preferable optical property.It is described Biaxially oriented film performance can meet：Longitudinal direction (MD) tensile strength >=55MPa, preferably >=60MPa； Laterally (TD) tensile strength >=65MPa, preferably >=70MPa.The puncture of the biaxially oriented film Intensity >=2.5N, preferably >=3.5N.Tension fracture elongation rate≤350% of the biaxially oriented film, Preferably≤300%.Mist degree≤8%, preferably≤5%.In the present invention, the longitudinal tensile strength It is measured according to method specified in GB/T 1040.3-2006 with transverse tensile strength.It is described to puncture by force Degree is measured according to method specified in GB/T 10004-2008, wherein, the thickness of film sample is 25±5μm.The tension fracture elongation rate is surveyed according to method specified in GB/T 1040.3-2006 It is fixed.

The low production cost of the durable membrane that the present invention is provided, processing technology are simple, versatility is good, open up The wide application of polyethylene film.

Hereinafter will be described the present invention by embodiment.

In the following Examples and Comparative Examples：

Film biaxial tension equipment is purchased from Br ü ckner companies of Germany, model Karo IV.

The polyethylene composition and film performance are tested in accordance with the following methods：

(1) molecular weight and molecualr weight distribution index (M_w、Mw/Mn、Mz、Mz+1)：Using English It is red that the type gel permeation chromatographs of PL-GPC 220 of Polymer Laboratories companies of state combine IR5 types External detector is measured, and chromatographic column is 3 series connection 10 μm of MIXED-B posts of Plgel, solvent and stream Dynamic is mutually 1,2,4- trichloro-benzenes, and column temperature is 150 DEG C, and flow velocity is 1.0mL/min, using PL companies EasiCal PS-1 Narrow distribution polystyrenes standard specimens carry out universal calibration.

(2) analytic type temperature rising elution test：Manufactured using Polymer Char S.A. companies of Spain The type temperature rising elution analyzers of TREF 300 are measured, and comprise the following steps that：By 80mg polyethylene compositions Thing is put in container, and (1,2,4- trichloro-benzenes, antioxidant BHT addition is 0.03 to injection 40mL solvents Weight %), 160 DEG C are warming up under nitrogen protection, then the constant temperature 60 under the mixing speed of 200rpm Minute, then 2mL solution is moved in analytical column, fast cooling (rate of temperature fall is 40 DEG C/min) To 95 DEG C, constant temperature 45 minutes, then temperature is slowly dropped to into 35 DEG C with the speed of 0.1 DEG C/min, then Kept for 30 minutes at 35 DEG C, subsequently with the ramp of 1.0 DEG C/min and with the pump of 0.5mL/min Flow velocity drip washing analytical column, leachates determine concentration with infrared detector, obtain the sample dissolved under different temperatures Product concentration, obtains temperature rising elution curve after normalization.

(3) melt temperature：Protected in nitrogen using Perkin-Elmer DSC-7 differential scanning calorimeters Under carry out DSC tests and obtain, wherein, temperature and hot-fluid are corrected using indium, amount of samples is 5mg. First by sample with the ramp of 10 DEG C/min to 180 DEG C, 5min is then kept to disappear at such a temperature Except thermal history, then 0 DEG C is cooled to the speed of 10 DEG C/min, and after keeping 1min at 0 DEG C again 180 DEG C are warming up to again with the speed of 10 DEG C/min, are heated up from first time heating, cooling and again and are recorded Heat flow curve determine melt temperature.

(4) content of the construction unit of derived from alpha alkene：Using BRUKER AVANCE III 400Hz Nuclear magnetic resonance spectrometer, by¹³C NMR spectrums (NMR) method is determined, wherein, visited using 10mm Head, 125 DEG C of test temperature, 90 pulses, waltz16 uncouples, and sampling time AQ is 5s, during delay Between D1 be 10s.Sample preparation：Sample is dissolved in deuterated o-dichlorohenzene with the concentration of 10%w/v, and Heating for dissolving in 130-140 DEG C of oil bath.

(5) melt index (MI)：It is measured according to method specified in GB/T 3682-2000, Wherein, test temperature is 190 DEG C, and load is 2.16kg.

(6) density：According to method specified in GB/T 1033.2-2010 and using density gradient column method It is measured.

Embodiment 1

The present embodiment is used to illustrate polyethylene composition and the durable membrane of present invention offer.

The polyethylene composition that the present embodiment is provided is by component A, component B, component C, anti-aging auxiliary agent With lubricant composition.Component A, component B and component C are the linear of ethylene/alpha-olefin copolymerization Low density polyethylene (LDPE) (LLDPE), and using identical catalyst system (metallocene catalyst) and Prepared by polymerization technique, difference is the amounts of hydrogen and alhpa olefin copolymerization list added when preparing different component The species and molar content of body is different, comprises the following steps that：

By ethene, alhpa olefin, hydrogen and nitrogen (ethene, alhpa olefin, hydrogen and nitrogen are polymer grade, Use Jing removing water, after oxygen, similarly hereinafter) gas fluidized bed reactor is added to, it is subsequently adding catalyst (metallocene catalyst system is the load prepared by CN102453124A embodiments 1 to system Type metallocene catalyst, similarly hereinafter), afterwards temperature be 84 DEG C, pressure be 2.0MPa under conditions of gather Close, respectively obtain component A, component B and component C.Wherein, component A, component B and component C The control of melt index realize that the control of density is by adjusting α alkene by adjusting the addition of hydrogen The species and addition of hydrocarbon and realize.Alhpa olefin used is 1- hexenes during preparing component A, is made Alhpa olefin used is 1- hexenes during standby component B, prepares alhpa olefin used during component C For 1- butylene.

After testing, the performance of component A, component B and component C that are prepared by said method is as follows：

Melt index MI of component A_A=1.5g/10min, density p_A=0.913g/cm³, molecular weight distribution Index M_w/M_n=3.4, the molar content=7.5mol% of alhpa olefin comonomer；

Melt index MI of component B_B=2.1g/10min, density p_B=0.913g/cm³, molecular weight distribution Index M_w/M_n=3.2, the molar content=7.5mol% of alhpa olefin comonomer；

Melt index MI of component C_C=15g/10min, density p_C=0.905g/cm³, molecular weight distribution refers to Number M_w/M_n=3.5, the molar content=9.1mol% of alhpa olefin comonomer.

Anti-aging auxiliary agent is Chimassorb 944, is produced by BASF Corp. of Germany.

Lubricant is the PEG lubricants produced by Switzerland's Clariant Corporation, and molecular weight is 10000.

(1) preparation of polyethylene composition：

Above-mentioned each component is weighed by proportioning and mixed, wherein the mass fraction W of component A_AFor 80 Weight portion, the mass fraction W of component B_BFor 10 weight portions, the mass fraction W of component C_CFor 20 Weight portion, W_A/W_C=4 (meet 5.2 × 1gMI_A+11.6≥W_A/W_C≥0.9×1gMI_A+ 2.1, it is also full 2.9 × 1gMI of foot_A+6.8≥W_A/W_C≥1.1×1gMI_A+2.7)；With said components A, component B and group The quality sum for dividing C is 100 weight portion meters, and the addition of anti-aging auxiliary agent is 0.3 weight portion, is lubricated The addition of agent is 0.1 weight portion.Add mixture in high speed agitator afterwards and be well mixed, then The material for mixing is added in the feeder of the double screw extruder of W＆P companies manufacture, material Jing Entered in twin-screw by feeder, the temperature of screw rod is maintained in the range of 180 ± 10 DEG C in process, Jing screw rods melting mixing is uniform, extrude, granulate and dry, and obtains polyethylene composition pellet, after testing Its melt index MI=2.4g/10min, its specific nature is as shown in Table 1 and Table 2.

(2) preparation of durable membrane：

Polyethylene composition pellet obtained in above-mentioned steps (1) is dried, Sweden is added to afterwards The sandwich layer extruder of the multilayer extrusion casting machine of model LCR400 of Labtech companies and upper and lower Melting extrusion is carried out in the extruder of top layer and slab is cast, wherein, in the upper and lower top layer extruder also Need to add inorganic antitack agent (silica, similarly hereinafter), and add in upper and lower top layer extruder it is anti- Stick is 0.02: 1 with the weight ratio of polyethylene composition pellet, during curtain coating slab, will be cast Chilling roll temperature is set as 25 DEG C, makes polyethylene thickness slab, and it is by upper epidermis, sandwich layer and layer structure Into.

Above-mentioned polyethylene thickness slab is put in the stretching clamp of film biaxial tension equipment, is adopted and is first indulged The two-way step drawing technological forming that laterally (TD) is stretched to after (MD) stretching, each step process condition It is as follows：MD preheating temperatures are 100 DEG C, and MD draft temperatures are 110 DEG C, and MD stretching ratios are 4 times； TD preheating temperatures are 100 DEG C, and TD draft temperatures are 115 DEG C, and TD stretching ratios are 5 times, film TD rates of extension are 60%/s；Film setting temperature is 120 DEG C, and it is 25 μm thin to obtain average thickness Film, it is made up of upper epidermis, sandwich layer and layer, and each layer raw material is the polyethylene composition of the present embodiment The thickness for also containing antitack agent, upper epidermis and layer in thing, and upper epidermis and layer is 0.5 μm.

Embodiment 2

Ethene, alhpa olefin, hydrogen and nitrogen are added in gas fluidized bed reactor, are subsequently adding and are urged Agent system, afterwards temperature be 88 DEG C, pressure be 1.8MPa under conditions of be polymerized, respectively obtain group Divide A, component B and component C.Wherein, the control of the melt index of component A, component B and component C Make and realized by adjusting the addition of hydrogen, the control of density passes through species and the addition for adjusting alhpa olefin Measure and realize.Alhpa olefin used is 1- butylene during preparing component A, prepares the process of component B In alhpa olefin used be 1- butylene, prepare component C during alhpa olefin used be 1- hexenes.

Melt index MI of component A_A=0.01g/10min, density p_A=0.930g/cm³, molecular weight distribution Index M_w/M_n=3.0, the molar content=1.6mol% of alhpa olefin comonomer；

Melt index MI of component B_B=10.0g/10min, density p_B=0.930g/cm³, molecular weight distribution Index M_w/M_n=2.8, the molar content=1.9mol% of alhpa olefin comonomer；

Melt index MI of component C_C=60g/10min, density p_C=0.922g/cm³, molecular weight distribution refers to Number M_w/M_n=2.9, the molar content=3.8mol% of alhpa olefin comonomer.

Anti-aging auxiliary agent is Tinuvin622, is produced by BASF Corp. of Germany.

(1) preparation of polyethylene composition：

Above-mentioned each component is weighed by proportioning and mixed, wherein the mass fraction W of component A_AFor 55 Weight portion, the mass fraction W of component B_BFor 5 weight portions, the mass fraction W of component C_CFor 55 Weight portion, W_A/W_C=1 (meets 5.2 × 1gMI_A+11.6≥W_A/W_C≥0.9×1gMI_A+ 2.1, it is also full 2.9 × 1gMI of foot_A+6.8≥W_A/W_C≥1.1×1gMI_A+2.7)；With said components A, component B and group The quality sum for dividing C is 100 weight portion meters, and the addition of anti-aging auxiliary agent is 0.2 weight portion, is lubricated The addition of agent is 0.1 weight portion.Add mixture in high speed agitator afterwards and be well mixed, then The material for mixing is added in the feeder of the double screw extruder of W＆P companies manufacture, material Jing Entered in twin-screw by feeder, the temperature of screw rod is maintained in the range of 230 ± 10 DEG C in process, Jing screw rods melting mixing is uniform, extrude, granulate and dry, and obtains polyethylene composition pellet, after testing Its melt index MI=0.9g/10min, its specific nature is as shown in Table 1 and Table 2.

(2) preparation of durable membrane：

Polyethylene composition pellet obtained in above-mentioned steps (1) is dried, Sweden is added to afterwards The sandwich layer extruder of the multilayer extrusion casting machine of model LCR400 of Labtech companies and upper and lower Melting extrusion is carried out in the extruder of top layer and slab is cast, wherein, in the upper and lower top layer extruder also The antitack agent and polyethylene composition added in inorganic antitack agent, and upper and lower top layer extruder need to be added The weight ratio of pellet is 0.02: 1, during curtain coating slab, curtain coating chilling roll temperature is set as 85 DEG C, polyethylene thickness slab is made, it is made up of upper epidermis, sandwich layer and layer.

Above-mentioned polyethylene thickness slab is put in the stretching clamp of film biaxial tension equipment, is adopted and is first indulged The two-way step drawing technological forming that laterally (TD) is stretched to after (MD) stretching, each step process condition It is as follows：MD preheating temperatures are 130 DEG C, and MD draft temperatures are 126 DEG C, and MD stretching ratios are 4 times； TD preheating temperatures are 130 DEG C, and TD draft temperatures are 128 DEG C, and TD stretching ratios are 6 times, film TD rates of extension are 100%/s；Film setting temperature is 130 DEG C, and it is 25 μm to obtain average thickness Film, it is made up of upper epidermis, sandwich layer and layer, and each layer raw material is the polyethylene group of the present embodiment The thickness for also containing antitack agent, upper epidermis and layer in compound, and upper epidermis and layer is 1 μm.

Embodiment 3

The polyethylene composition that the present embodiment is provided is polymerized using the multiple reactor shunting means shown in Fig. 1 Arrive, wherein the polymerization of first reactor 1 prepare component A, the polymerization of second reactor 2 prepare component B, the The polymerization of three reactor 3 prepares component C, and component A, component B and component C are ethylene/alpha-olefin copolymerization LLDPE (LLDPE), these three components are using identical catalyst system (cyclopentadienyl gold Metal catalyst) and polymerization technique preparation, difference is amounts of hydrogen, the α added when preparing different component The species and molar content of olefin comonomer and the yield in unit time of each reactor are different, tool Body step is as follows：

Alhpa olefin, n-hexane and hydrogen are added in polymer reactor, and polymer reactor is heated to Default polymerization temperature, is afterwards added to vinyl monomer and catalyst system in polymer reactor simultaneously, And temperature be 140 DEG C, pressure be 2.5MPa under conditions of polyase 13 0 minute, respectively obtain component A, Component B and component C.Wherein, the control of the melt index of component A, component B and component C passes through Adjust the addition of hydrogen and realize, the control of density is by adjusting the species and addition of alhpa olefin and reality It is existing.Alhpa olefin used is 1- octenes during preparing component A, prepares α used during component B Alkene is 1- butylene, and alhpa olefin used is 1- butylene during preparing component C.

By yield in unit time W of component A in first reactor 1 in preparation process_A, second reaction Yield in unit time W of component B in device 2_BWith the yield in unit time of component C in the 3rd reactor 3 W_CWeight ratio maintain W_A∶W_B∶W_C=75: 2: 35, wherein W_A/W_C=2.1 (meet 5.2 ×1gMI_A+11.6≥W_A/W_C≥0.9×1gMI_A+ 2.1, also meet 2.9 × 1gMI_A+6.8≥W_A/W_C ≥1.1×1gMI_A+2.7)。

Melt index MI of component A_A=0.1g/10min, density p_A=0.920g/cm³, molecular weight distribution Index M_w/M_n=3.1, the molar content=2.1mol% of alhpa olefin comonomer；

Melt index MI of component B_B=5.0g/10min, density p_B=0.920g/cm³, molecular weight distribution Index M_w/M_n=3.5, the molar content=5.1mol% of alhpa olefin comonomer；

Melt index MI of component C_C=25g/10min, density p_C=0.920g/cm³, molecular weight distribution refers to Number M_w/M_n=3.2, the molar content=5.1mol% of alhpa olefin comonomer.

Anti-aging auxiliary agent is GW-540, is produced by BASF Corp. of Germany.

(1) preparation of polyethylene composition：

Component A obtained above, component B and component C are conveyed respectively in yield in unit time ratio It is separated in different solid-liquid (gas) separators 4 and and then is transported to the homogenization material for stirring In storehouse 5, then anti-aging auxiliary agent and lubricant is added to carry out mixing homogenizing by proportioning.Wherein, with above-mentioned The quality sum of component A, component B and component C be 100 weight portion meters, the addition of anti-aging auxiliary agent Measure as 0.3 weight portion, the addition of lubricant is 0.5 weight portion.Homogenized feed bin 5 is homogenized afterwards Mixture be added to W＆P companies manufacture double screw extruder feeder in, material is via feeding Device is entered in twin-screw, and the temperature of screw rod is maintained in the range of 200 ± 10 DEG C in process, Jing spiral shells Bar melting mixing is uniform, extrude, granulate and dry, and obtains polyethylene composition pellet, and after testing it melts Melt index M I=0.6g/10min, its specific nature is as shown in Table 1 and Table 2.

(2) preparation of durable membrane：

Polyethylene composition pellet obtained in above-mentioned steps (1) is dried, Sweden is added to afterwards Melting extrusion is carried out in the multilayer extrusion casting machine of model LCR400 of Labtech companies and casting is cast Piece, during curtain coating slab, by curtain coating chilling roll temperature 35 DEG C is set as, makes polyethylene thickness slab, The slab is single layer structure.

Above-mentioned polyethylene thickness slab is put in the stretching clamp of film biaxial tension equipment, is adopted and is first indulged The two-way step drawing technological forming that laterally (TD) is stretched to after (MD) stretching, each step process condition It is as follows：MD preheating temperatures are 116 DEG C, and MD draft temperatures are 118 DEG C, and MD stretching ratios are 4 times； TD preheating temperatures are 120 DEG C, and TD draft temperatures are 120 DEG C, and TD stretching ratios are 5 times, film TD rates of extension are 100%/s；Film setting temperature is 122 DEG C, and it is 25 μm to obtain average thickness Single thin film.

Embodiment 4

Method according to embodiment 1 prepares polyethylene composition and durable membrane, except for the difference that, resists Aging auxiliary agent by Tianjin Xin Lifeng companies produce, the trade mark is UV-531, and with component A, component B and The quality sum of component C is 100 weight portion meters, and the addition of anti-aging auxiliary agent is 0.3 weight portion, is obtained To the film that average thickness is 25 μm, it is made up of upper epidermis, sandwich layer and layer, and each layer raw material is equal Also to contain antitack agent in the polyethylene composition of the present embodiment, and upper epidermis and layer, upper epidermis and The thickness of layer is 0.5 μm.

Embodiment 5

Method according to embodiment 1 prepares polyethylene composition and durable membrane, except for the difference that, resistance to Long the drawing process in the preparation process of property film is synchronous bidirectional stretching, and preheating temperature is 105 DEG C, is drawn Temperature is stretched for 110 DEG C, the stretching ratio of MD and TD is 4 times, and rate of extension is 60%/s, is obtained Average thickness is 25 μm of film, wherein, the thickness of upper epidermis and layer is 0.5 μm.

Embodiment 6

Method according to embodiment 1 prepares polyethylene composition and polyethylene film, except for the difference that, In the preparation process of component A, alhpa olefin is 1- hexenes, and the performance of component A for obtaining is as follows： Melt index MI of component A_A=1.5g/10min, density p_A=0.928g/cm³, molecular weight distributing index M_w/M_n=3.0, the molar content=1.9mol% of alhpa olefin comonomer.That is, component A, component B and The density p of component C_A、ρ_BAnd ρ_CBetween relation be unsatisfactory for -0.04≤ρ_A-ρ_B≤ 0.02 and -0.04≤ ρ_A-ρ_C≤ 0.02, the film that average thickness is 25 μm is obtained, wherein, the thickness of upper epidermis and layer It is 0.5 μm.

Comparative example 1

This comparative example is used to illustrate polyethylene raw material and the durable membrane of reference.

(1) polyethylene raw material：

Polyethylene raw material used by this comparative example is that the film-grade of DOW chemical companies of U.S. production is linearly low Density polyethylene, trade mark ELITE 5400G, catalyst is metallocene catalyst, melt index MI=1.0g/10min, density p=0.916g/cm³, molecular weight distributing index M_w/M_n=3.2.

(2) preparation of durable membrane：

Method according to embodiment 3 prepares durable membrane, except for the difference that, by the polyethylene composition Pellet is substituted with the polyethylene raw material of this comparative example step (1) of identical weight part, and Jing attempts for many times equal There is the situation of stretching rupture of membranes, it is impossible to stretch film forming.Additionally, by durable membrane's preparation process TD rates of extension are down to after 50%/s, and Jing attempts the situation for stretching rupture of membranes still occur for many times, it is impossible to draw It is stretched into film.

Comparative example 2

(1) polyethylene raw material：

Polyethylene raw material used by this comparative example is identical with comparative example 1.

(2) preparation of durable membrane：

The durable membrane of this comparative example adopts the upper blowing method film blowing device of DR.COLLIN companies of Germany Extrusion and blow molding is obtained, and concrete grammar is as follows：The polyethylene raw material that above-mentioned steps (1) are chosen is added Enter in the hopper of upper blowing method film blowing device extruder, after the abundant fusion plastification of the extruded machine of raw material, by machine The annular die extrusion of head makes melt membrane tube, afterwards compressed air inflation (blow-up ratio is 2.5 times), And make durable membrane Jing after vane cooling, wherein film is single layer structure that average thickness is 25 μm.

Comparative example 3

This comparative example is used to illustrate polyethylene composition and the durable membrane of reference.

The polyethylene composition that this comparative example is provided is made up of component 1, component 2 and lubricant.Described group Point 1 and component 2 be the LLDPE (LLDPE) of ethylene/alpha-olefin copolymerization, and adopt Prepared with identical catalyst system (metallocene catalyst) and polymerization technique, difference is to prepare difference The amounts of hydrogen added during component and the species and molar content of alhpa olefin comonomer are different, tool Body step is as follows：

Ethene, alhpa olefin, hydrogen and nitrogen are added in gas fluidized bed reactor, are subsequently adding and are urged Agent system, afterwards temperature be 84 DEG C, pressure be 2.0MPa under conditions of be polymerized 60 minutes, point Do not obtain component 1 and component 2.Wherein, the control of the melt index of component 1 and component 2 is by adjusting The addition of hydrogen and realize, the control of density is realized by adjusting the species and addition of alhpa olefin. Alhpa olefin used is 1- hexenes during preparing component 2, prepares alhpa olefin used during component 2 For 1- butylene.

After testing, the component 1 for being prepared by said method and the performance of component 2 are as follows：

Melt index MI of component 1₁=5.0g/10min, density p₁=0.913g/cm³, molecular weight distribution refers to Number M_w/M_n=3.2, the molar content=7.5mol% of alhpa olefin comonomer；

Melt index MI of component 2₂=15g/10min, density p₂=0.905g/cm³, molecular weight distribution refers to Number M_w/M_n=3.5, the molar content=9.8mol% of alhpa olefin comonomer.

The PEG lubricants that lubricant is produced for Switzerland's Clariant Corporation, molecular weight 10000.

(1) preparation of polyethylene composition：

Above-mentioned each component is weighed by proportioning and mixed, wherein the mass fraction W of component 1₁For 80 Weight portion, the mass fraction W of component 2₂For 20 weight portions, W₁/W₂=4；Be subsequently adding lubricant (with The quality sum of said components 1 and component 2 is 100 weight portion meters, and the addition of lubricant is 0.1 weight Amount part), add mixture in high speed agitator be well mixed afterwards, then the material for mixing is added Enter in the feeder of the double screw extruder of W＆P companies manufacture, material enters double spiral shells via feeder In bar, the temperature of screw rod is maintained in the range of 180 ± 10 DEG C in process, Jing screw rod melting mixings Uniformly, extrude, granulate and dry, obtain polyethylene composition pellet, its specific nature such as table 1 and table Shown in 2.

(2) preparation of durable membrane：

Method according to embodiment 1 carries out the preparation of durable membrane, as a result shows, through repeatedly trial, The maximum tension multiplying power of biaxially oriented film is only 2 times of (TD) × 2 times (MD), film TD highests Stretching ratio is only 10%/s, i.e. stretching ratio and rate of extension are too low, and stretching film forming is poor, Do not possess practicality.

Comparative example 4

Ethene, alhpa olefin, hydrogen and nitrogen are added in gas fluidized bed reactor, are subsequently adding and are urged Agent system, afterwards temperature be 84 DEG C, pressure be 2.0MPa under conditions of be polymerized 60 minutes, point Do not obtain component 1 and component 2.Wherein, the control of the melt index of component 1 and component 2 is by adjusting The addition of hydrogen and realize, the control of density is realized by adjusting the species and addition of alhpa olefin. Alhpa olefin used is 1- butylene during preparing component 1, prepares alhpa olefin used during component 2 For 1- hexenes.

Melt index MI of component 1₁=0.01g/10min, density p₁=0.930g/cm³, molecular weight distribution Index M_w/M_n=2.8, the molar content=1.8mol% of alhpa olefin comonomer；

Melt index MI of component 2₂=5.0g/10min, density p₂=0.922g/cm³, molecular weight distribution refers to Number M_w/M_n=2.7, the molar content=4.1mol% of alhpa olefin comonomer.

(1) preparation of polyethylene composition：

Above-mentioned each component is weighed by proportioning and mixed, wherein the mass fraction W of component 1₁For 55 Weight portion, the mass fraction W of component 2₂For 55 weight portions, W₁/W₂=1；Be subsequently adding lubricant (with The quality sum of said components 1 and component 2 is 100 weight portion meters, and the addition of lubricant is 3 weight Part), add mixture in high speed agitator be well mixed afterwards, then the material for mixing is added To in the feeder of the double screw extruder of W＆P companies manufacture, material enters twin-screw via feeder In, the temperature of screw rod is maintained in the range of 230 ± 10 DEG C in process, and Jing screw rod melting mixings are equal It is even, extrude, granulate and dry, obtain polyethylene composition pellet, its specific nature such as Tables 1 and 2 It is shown.

(2) preparation of durable membrane：

Method according to embodiment 2 carries out the preparation of durable membrane, as a result shows, through repeatedly trial, The maximum tension multiplying power of biaxially oriented film is only 2 times of (TD) × 2 times (MD), film TD highests Stretching ratio is only 10%/s, i.e. stretching ratio and rate of extension are too low, and stretching film forming is poor, Do not possess practicality.

Comparative example 5

(1) preparation of polyethylene composition：

The polyethylene composition that this comparative example is provided is obtained using the polymerization of multiple reactor shunting means, wherein the The polymerization of one reactor prepares the polymerization of component 1, second reactor and prepares component 2, and component 1 and component 2 are The LLDPE (LLDPE) of ethylene/alpha-olefin copolymerization, both components adopt identical Prepared by catalyst system (metallocene catalyst) and polymerization technique, difference is when for preparing different component institute The unit interval of the amounts of hydrogen, the species of alhpa olefin comonomer and molar content and each reactor of addition Yield is different.Comprise the following steps that：

Alhpa olefin, n-hexane and hydrogen are added in polymer reactor, and polymer reactor is heated to Default polymerization temperature, is afterwards added to vinyl monomer and catalyst system in polymer reactor simultaneously, And temperature be 140 DEG C, pressure be 2.5MPa under conditions of polyase 13 0 minute, respectively obtain component 1 With component 2.Wherein, the addition that the control of the melt index of component 1 and component 2 passes through regulation hydrogen And realize, the control of density is realized by adjusting the species and addition of alhpa olefin.Prepare component 1 Used in the process of alhpa olefin be 1- octenes, prepare component 2 during alhpa olefin used be 1- butylene.

By yield in unit time W of component in first reactor 1 in preparation process₁With second reactor Yield in unit time W of middle component 2₂Weight ratio maintain W₁∶W₂=20: 80.

Melt index MI of component 1₁=0.1g/10min, density p₁=0.920g/cm³, molecular weight distribution refers to Number M_w/M_n=3.1, the molar content=2.1mol% of alhpa olefin comonomer；

Melt index MI of component 2₂=25g/10min, density p₂=0.920g/cm³, molecular weight distribution refers to Number M_w/M_n=3.5, the molar content=5.1mol% of alhpa olefin comonomer.

Each component obtained above is transported in solid-liquid (gas) separator in yield in unit time ratio Row is separated and is further transported in the homogenization silo with stirring, then adds lubricant to carry out by proportioning Mixing homogenizing.Wherein, lubricant is the Tissuemat E of Honeywell Inc. of U.S. production, with said components 1 and the quality sum of component 2 be 100 weight portion meters, the addition of lubricant is 1 weight portion.Afterwards The mixture that homogenized feed bin is homogenized is added to the feeder of the double screw extruder of W＆P companies manufacture In, material is entered in twin-screw via feeder, and the temperature of screw rod is maintained at 200 ± 30 DEG C in process In the range of, Jing screw rods melting mixing is uniform, extrude, granulate and dry, and obtains polyethylene composition grain Material, its specific nature is as shown in Table 1 and Table 2.

(2) preparation of durable membrane：

Method according to embodiment 3 carries out the preparation of durable membrane, as a result shows, through repeatedly trial, The maximum tension multiplying power of biaxially oriented film is only 2 times of (TD) × 2 times (MD), film TD highests Stretching ratio is only 10%/s, i.e. stretching ratio and rate of extension are too low, and stretching film forming is poor, Do not possess practicality.

Test case

Test case is used to illustrate the test of durable membrane and reference durable membrane's performance.

(1) Film Haze：It is measured according to method specified in GB/T 2410-2008, wherein, Film sample thickness is 25 ± 5 μm, and acquired results are as shown in table 3.

(2) film modulus, tensile strength and tension fracture elongation rate：According to GB/T 1040.3-2006 Specified in method be measured, acquired results are as shown in table 3.

(3) membrane puncture intensity：It is measured according to method specified in GB/T10004-2008, its In, film sample thickness is 25 ± 5 μm, and acquired results are as shown in table 3.

(4) ageing-resistant performance：According to GB/T-16422《Xenon lamp aging test method》Specified in side Method is tested the ageing-resistant performance of film, test index：Tensile strength and elongation at break, calculate Index：Tensile strength retention rate and reserved elongation at break, acquired results are as shown in table 3.

Table 1

Table 2

Note：In table 2, high temperature drip washing peak area ratio and low temperature drip washing peak area ratio are drenched with high temperature drip washing peak and low temperature On the basis of washing the gross area at peak.

Result from table 3 can draw, using the polyethylene composition of present invention offer in embodiment 1-3 Thing prepares biaxial tension PE films, with film forming multiplying power is big, stretching speed compared with the film of prior art Rate is fast, durability is good, mechanical strength is high, good in optical property advantage, the equal energy of performance of prepared film Meet longitudinal direction (MD) tensile strength >=55MPa, laterally (TD) tensile strength >=65MPa, puncture strong Degree >=2.5N, tension fracture elongation rate≤350%, mist degree≤8%.It is right with embodiment 5 from embodiment 1 Than as can be seen that when the density p of component A, component B and component C in the polyethylene composition_A、ρ_B And ρ_CBetween relation meet -0.04≤ρ_A-ρ_B≤ 0.02 and -0.04≤ρ_A-ρ_CWhen≤0.02, the polyethylene Composition is prepared on the basis of with preferable film forming and durability by the polyethylene composition Film also has higher tensile strength and punctured resistance and relatively low mist degree.From embodiment 1 with it is right The contrast of ratio 1-2 is as can be seen that the commercial polyethylene raw material prepared using prior art cannot be drawn into Film, thus be not suitable for being processed using Flat film strength, and compared with envelope pulling method, using flat Film stretching method formed film mechanical strength and puncture strength is higher and Film Haze is relatively low.Additionally, from Embodiment 1-3 is with the contrast of comparative example 3-5 as can be seen that using the polyethylene composition for providing of the invention As the raw material for preparing film, with more preferable filming performance and endurance quality, more prospects for commercial application.

The preferred embodiment of the present invention described in detail above, but, the present invention is not limited to above-mentioned reality The detail in mode is applied, in the range of the technology design of the present invention, can be to the technical side of the present invention Case carries out various simple variants, and these simple variants belong to protection scope of the present invention.

It is further to note that each particular technique described in above-mentioned specific embodiment is special Levy, in the case of reconcilable, can be combined by any suitable means.In order to avoid need not The repetition wanted, the present invention is no longer separately illustrated to various possible combinations.

Additionally, can also be combined between a variety of embodiments of the present invention, as long as its Without prejudice to the thought of the present invention, it should equally be considered as content disclosed in this invention.

Claims

1. a kind of polyethylene composition, the polyethylene composition contains by ethene and alhpa olefin copolymerization Into LLDPE and anti-aging auxiliary agent, it is characterised in that the polyethylene composition Weight average molecular weight Mw is the g/mol of 100,000 g/mol-18 ten thousand, and Mw/Mn is 4.0-8.0, Mz/Mw For 4.0-6.0, Mz+1/Mw is 4.5-12.5.

2. polyethylene composition according to claim 1, wherein, the polyethylene composition by The temperature rising elution curve that analytic type temperature rising elution staging is measured includes high temperature drip washing peak and low temperature drip washing peak, And the temperature at the high temperature drip washing peak is 90-105 DEG C, the temperature at the low temperature drip washing peak is 50-90 DEG C； On the basis of the gross area at the high temperature drip washing peak and low temperature drip washing peak, the area at the high temperature drip washing peak is not Higher than 60%, the area at the low temperature drip washing peak is not less than 40%；

Preferably, the temperature at the high temperature drip washing peak is 95-100 DEG C, and the temperature at the low temperature drip washing peak is 60-90℃；On the basis of the gross area at the high temperature drip washing peak and low temperature drip washing peak, the high temperature drip washing The area at peak is not higher than 50%, and the area at the low temperature drip washing peak is not less than 50%.

3. polyethylene composition according to claim 1, wherein, the polyethylene composition by The melt temperature that differential scanning calorimetry is measured is 100-130 DEG C, preferably 105-128 DEG C.

4. polyethylene composition according to claim 1, wherein, the linear low density polyethylene The content of the derived construction unit from alhpa olefin of alkene is 0.5-20mol%, preferably 2-10mol%.

5. the polyethylene composition according to any one in claim 1-4, wherein, the line Property low density polyethylene (LDPE) contains component A, component B and component C；Component A temperature be 190 DEG C, Load is melt index MI under 2.16kg_AFor 0.01-2g/10min, density p_AFor 0.880-0.936g/cm³；Component B temperature be 190 DEG C, load be that melting under 2.16kg refers to Number MI_BFor 2.1-14.9g/10min, density p_BFor 0.910-0.930g/cm³；Component C is in temperature It is melt index MI under 2.16kg for 190 DEG C, load_CFor 15-150g/10min, density p_CFor 0.880-0.930g/cm³。

6. polyethylene composition according to claim 5, wherein, component A is in temperature 190 DEG C, load be 2.16kg under melt index MI_AFor 0.01-1.5g/10min, component B exists Temperature is 190 DEG C, load is melt index MI under 2.16kg_BFor 3-10g/10min, component C Temperature be 190 DEG C, load be 2.16kg under melt index MI_CFor 15-100g/10min；It is preferred that Ground, component A temperature be 190 DEG C, load be 2.16kg under melt index MI_AFor 0.01-1g/10min, component B temperature be 190 DEG C, load be 2.16kg under melt index MI_BFor 3-5g/10min, component C temperature be 190 DEG C, load be that melting under 2.16kg refers to Number MI_CFor 20-60g/10min.

7. polyethylene composition according to claim 5, wherein, the density p of component A_A For 0.910-0.930g/cm³, the density p of component B_BFor 0.913-0.928g/cm³, component C Density p_CFor 0.905-0.928g/cm³；Preferably, the density p of component A_AFor 0.915-0.926g/cm³, the density p of component B_BFor 0.913-0.924g/cm³, component C Density p_CFor 0.910-0.926g/cm³。

8. polyethylene composition according to claim 7, wherein, in the polyethylene composition The density p of component A, component B and component C_A、ρ_BAnd ρ_CBetween relation meet -0.04≤ρ_A-ρ_B ≤ 0.02 and -0.04≤ρ_A-ρ_C≤0.02。

9. polyethylene composition according to claim 5, wherein, in the polyethylene composition In, the mass fraction W of component A_AFor 25-90 weight portions, the mass fraction of component B W_BFor 0.1-10 weight portions, the mass fraction W of component C_CFor 10-75 weight portions；Preferably, In the polyethylene composition, the mass fraction W of component A_AIt is described for 30-80 weight portions The mass fraction W of component B_BFor 0.5-8 weight portions, the mass fraction W of component C_CFor 20-70 Weight portion；Preferably, the mass fraction W of component A_AWith the mass fraction W of component C_CWith group Divide melt index MI of A_ARelation meet 5.2 × lgMI_A+11.6≥W_A/W_C≥0.9× lgMI_A+ 2.1, preferably meet 2.9 × lgMI_A+6.8≥W_A/W_C≥1.1×lgMI_A+2.7。

10. polyethylene composition according to claim 5, wherein, the polyethylene composition exists Temperature is 190 DEG C, load be melt index under 2.16kg is 0.1-20g/10min, preferably 0.5-10g/10min。

11. polyethylene compositions according to claim 5, wherein, component A, component B M is satisfied by with the molecular weight distributing index of component C_w/M_n≤ 4.5, preferably meet 2.0≤M_w/M_n≤4.2； Preferably, component A, component B and component C are obtained using metallocene catalyst polymerisation.

12. polyethylene compositions according to claim 5, wherein, component A, component B C is each independently with the alhpa olefin in component C₃-C₂₀At least one in alkene, preferably propylene, 1- butylene, 2- butylene, 3-methyl-1-butene, 4- methyl isophthalic acids-butylene, 1- amylenes, 3- Methyl-1-pentenes, 4-methyl-1-pentene, 3,3- dimethyl -1- amylenes, 3,4- dimethyl -1- amylenes, 4,4- dimethyl -1- amylenes, 1- hexenes, 4- methyl isophthalic acids-hexene, 5- methyl isophthalic acids-hexene, 1- heptene, 2- heptene, 1- octenes, 1- decene, In 1- dodecylenes, tetradecene, cetene, 1- vaccenic acids and 1- eicosylenes at least At least one in one kind, more preferably 1- butylene, 1- hexenes and 1- octenes.

13. polyethylene compositions according to claim 5, wherein, with component A, component The gross weight of B and component C is 100 weight portion meters, and the content of the anti-aging auxiliary agent is 0.01-5 weight Part；Preferably, the anti-aging auxiliary agent is in UV absorbers, energy quencher and light stabilizer It is at least one.

A kind of 14. durable membranes, the durable membrane at least includes one layer by claim 1-13 The polyethylene layer that polyethylene composition described in middle any one is formed.

15. durable membranes according to claim 14, wherein, the durable membrane has The composite construction of upper epidermis, sandwich layer and layer, and at least described sandwich layer is by the polyethylene composition The polyethylene layer of formation；Preferably, when the durable membrane has upper epidermis, sandwich layer and layer During composite construction, the thickness of the upper epidermis and layer is each independently durable membrane's thickness 1-25%.

16. durable membranes according to claim 14, wherein, the durable membrane serves as reasons Flat film biaxial tension method prepares biaxially oriented film；Preferably, using flat film biaxial tension legal system During the standby biaxially oriented film, longitudinal stretching multiplying power >=4 times, cross directional stretch multiplying power >=5 times； During the biaxially oriented film is prepared using flat film biaxial tension method, cross directional stretch speed >= 50%/s.

17. durable membranes according to any one in claim 14-16, wherein, it is described resistance to Long the thickness of property film is 10-200 μm, preferably 10-100 μm.