CN107226878B

CN107226878B - Preparation method and application of polyethylene film

Info

Publication number: CN107226878B
Application number: CN201610168290.XA
Authority: CN
Inventors: 管炳伟; 吴文清; 张洪波; 贾世敏; 孙洪霞; 崔宇辉; 阳永荣; 王靖岱; 陈美�; 陈毓明; 胡晓波; 范小强; 韩国栋; 王晓丽; 王静; 魏文学; 张柯; 蒋斌波; 黄正梁; 王晓飞
Original assignee: China Petroleum and Chemical Corp; Zhejiang University ZJU
Current assignee: China Petroleum and Chemical Corp; Zhejiang University ZJU
Priority date: 2016-03-23
Filing date: 2016-03-23
Publication date: 2020-10-30
Anticipated expiration: 2036-03-23
Also published as: CN107226878A

Abstract

The invention discloses a preparation method of a polyethylene film, which comprises the following steps: 1) conveying a main catalyst in a catalyst system into a reactor by using a mixed liquid I as a carrier material flow, wherein the mixed liquid I comprises alkane, alkene and a cocatalyst; adding a supplementary olefin feed into a material flow II flowing out of the reactor to obtain a material flow III, dividing the material flow III into material flows IIIa and IIIb, and respectively refluxing the material flows IIIa and IIIb to the side part and the bottom part of the reactor; in the reactor, ethylene polymer is obtained through polymerization and discharged from the reactor; wherein the olefin comprises alpha-olefin and ethylene, and the molar ratio concentration ratio of the alpha-olefin to the ethylene in the mixed liquid I is at least 1; 2) carrying out blow molding on the ethylene polymer prepared in the step 1) to obtain the polyethylene film. The method provided by the invention improves the self-adhesiveness of the obtained film and reduces the haze.

Description

Preparation method and application of polyethylene film

Technical Field

The invention relates to a preparation method of a polyethylene film, in particular to a preparation method and application of the polyethylene film.

Background

At present, a polypropylene biaxially oriented film (BOPP) is a main product in the field of high-grade packaging because it has the advantages of light weight, transparency, no toxicity, moisture resistance, high mechanical strength and the like. And the novel polyethylene biaxially oriented film (BOPE) exhibits more excellent performance than BOPP, and is lighter in weight, and better in transparency, glossiness and printing effect. The BOPE mainly has a 3-5 layer film structure, most commonly 3 layers, namely an outer base layer, a core layer base layer and a functional layer. The main component of the core layer is Polyethylene (PE), and the adding amount of the PE accounts for about 99% of the weight of the core layer. The traditional polyethylene film has the tensile strength in the longitudinal direction which is far higher than that in the transverse direction, which can cause the transverse breaking elongation of the film to be insufficient when in use, thereby affecting the use performance of the polyethylene film. The PE used in conventional polyethylene films is mainly Linear Low Density Polyethylene (LLDPE), Low Density Polyethylene (LDPE) and metallocene linear low density polyethylene (mLLDPE).

Although there is a disclosure in the literature of a method for improving the self-adhesion of polyethylene films by adjusting the additive components. The ductility and the toughness of the preservative film are improved by adding the plasticizer of dioctyl phthalate and dioctyl adipate and the matching of inorganic filler calcium carbonate and aluminum oxide, so that the self-adhesiveness is enhanced. However, in some application fields of the film, such as food preservation and the like, the self-adhesion of the film is mainly realized by the characteristics of the plastic. And the additives inevitably involve problems of spillage which may affect the application of the film.

In view of this consideration, the inventors of the present invention have conducted studies with the purpose of solving the problems exposed by the prior art in the related art, and it is desirable to provide a method for producing a high performance ethylene polymer product having low haze and high self-adhesiveness using a fluidized bed reactor.

Disclosure of Invention

In view of the above deficiencies of the prior art, it is an object of the present invention to provide a process for producing polyethylene film, especially BOPE film, such as polyethylene film using a fluidized bed reactor.

The invention also aims to provide application of the polyethylene film prepared by the method in film products such as packaging materials or commodity labels.

According to an aspect of the present invention, there is provided a method for preparing a polyethylene film, comprising:

1) conveying a main catalyst in a catalyst system into a reactor by using a mixed liquid I as a carrier material flow, wherein the mixed liquid I comprises alkane, alkene and a cocatalyst; adding a supplementary olefin feed to a stream II flowing out of the reactor to obtain a stream III, dividing the stream III into streams IIIa and IIIb, and respectively refluxing the streams IIIa and IIIb to the side part and the bottom part of the reactor; in the reactor, ethylene polymer is obtained through polymerization and discharged from the reactor; wherein the olefin comprises alpha-olefin and ethylene, and the molar ratio of the alpha-olefin to the ethylene in the mixed liquid I is at least 1;

2) carrying out blow molding on the ethylene polymer prepared in the step 1) to obtain the polyethylene film.

According to the method provided by the invention, the film with high self-adhesion, low haze and high light transmittance can be prepared, and the film has good puncture resistance, high tear strength, high tensile strength and high tangent modulus. The film prepared by the method has good comprehensive performance and wide application prospect.

In the method of the invention, material circulation is carried out in the whole reaction system, thereby recycling the raw materials. Wherein, the mass flow of the material flow II flowing out of the reactor is large, which is a large-flow material circulation, and the material flow III is obtained after a small amount of feeding is supplemented. In the method of the invention, the mixed liquid I and the streams IIIa and IIIb are added into a reactor, wherein the alkane is contained, the vaporization latent heat of the alkane is high, and the heat transfer quantity of the alkane is large, so that reaction areas with different temperatures are presented in the reactor; and the mixed liquid I has high alpha-olefin content; therefore, the olefin monomer can respectively obtain the olefin polymer with high branch chain, low density and high molecular weight and the olefin polymer with low branch chain and low density and low molecular weight in different regions in the fluidized bed reactor under different temperature conditions, so that the olefin polymer with high and low molecular weight can be obtained and continuously mixed and fluidized, the content of a molecular chain segment or a molecular chain with high branching degree is improved, and the heat removal capability in the fluidized bed reactor can be greatly improved by alkane, so that the method can prepare the olefin polymer product with high and low molecular weight and high and low branching degree which are microscopically uniformly mixed, the light transmittance, the haze and the self-adhesion of the ethylene copolymer are improved, and the production yield is obviously improved. Then, by a blow molding process using the obtained ethylene polymer, a polyethylene film excellent in properties such as high self-adhesiveness, low haze and high light transmittance, and high puncture resistance, tear strength, tensile strength and tangent modulus is obtained.

In the process of the present invention, olefin monomers in stream III and mixed liquid I are polymerized as starting materials in a fluidized bed reactor in a plurality of reaction zones of different temperatures. Different polymerization temperatures and different olefin monomer concentrations can result in olefin polymers that differ in both structure and properties. According to the invention, a mixed solution containing alkane and alkene is used as a carrier to convey the catalyst into the reactor, so that a plurality of low-temperature reaction zones can be further formed in the reactor, and the content of molecular chains with high branching degree can be further improved. The polyethylene produced by this process has improved tensile strength, haze and self-adhesion; further, the overall properties of the resulting film article, such as puncture resistance, tangent modulus, tear strength, self-adhesion, and light transmittance, are improved, while haze is reduced.

According to the method provided by the invention, the catalyst is conveyed into the reactor by using a mixed solution containing alkane and olefin as a carrier, the mole content of alpha-olefin in the mixed solution is not lower than that of ethylene, and the content of alpha-olefin at the initial stage of the action of the catalyst is high, so that the branching degree of polyethylene is increased, and the density is reduced (LDPE low density polyethylene). The polymer obtained according to the invention has improved haze and self-adhesiveness under the condition of similar molecular weight.

According to a preferred embodiment of the present invention, the mixed liquid I may be used as a carrier stream capable of transporting the procatalyst powder to the reaction system. Wherein, preferably, the main catalyst is firstly conveyed into a pipeline or a pipe fitting connected with a polymerization reactor by a rotating device, and then the main catalyst powder is conveyed into a reaction system by the mixed liquid I. According to a particular embodiment of the invention, the rotating means are selected from pumps, compressors, fans and reducers.

According to a preferred embodiment of the present invention, the catalyst system comprises a ziegler-natta catalyst, a metallocene catalyst, a transition metal catalyst, an inorganic chromium catalyst and an organic chromium catalyst. The catalyst system includes a cocatalyst and a procatalyst. In a specific example, the amount of the main catalyst and the cocatalyst is the amount conventionally used in the art, such as the molar ratio of the main catalyst to the cocatalyst is 1:1 to 6:1, based on the molar ratio of the active metal element in the main catalyst to the active metal element in the cocatalyst. In a specific embodiment, the cocatalyst contained in the mixed liquid I is triethylaluminum. In another specific example, the amount of the co-catalyst in the mixed liquid is at least 150ppm (by weight content).

According to a preferred embodiment of the present invention, the molar ratio of alpha-olefin to ethylene in the mixed liquid I is in the range of 1 to 5, such as 1.3 to 5. In a preferred case, the molar ratio of the α -olefin to ethylene in the mixed liquid I is 1.5 to 5. At this time, the content of the alpha-olefin is higher, so that the branching degree of the polyethylene is increased, the density is reduced, and meanwhile, the haze and the self-adhesiveness of the polyethylene (or the ethylene polymer, which is referred to as the copolymerized ethylene herein) are further improved under the condition of the same molecular weight.

According to another preferred embodiment of the present invention, the alkane is contained in the mixed liquid I in an amount of 5 to 80 wt%. In a preferred case, the alkane content in the mixed liquid I is 10 to 65% by weight. The alkane content in the mixed liquid is controlled, which is beneficial to controlling the reaction temperature and forming a low-temperature reaction zone.

According to another preferred embodiment of the invention, the mass flow of the mixed liquid I is between 0.05% and 5%, preferably between 0.1% and 3%, of the mass flow of stream II.

In a particular embodiment, the alkane of the present invention comprises at least one of butane, isobutane, n-pentane, isopentane, n-hexane, cyclohexane and heptane. The alkane in the limited range has high vaporization latent heat and large heat transfer; it is advantageous to form reaction zones of different reaction temperatures in the reactor.

According to a preferred embodiment of the invention, the reaction pressure in the reactor is between 0.5 and 10MPa and the reaction temperature is between 40 and 150 ℃. In a specific example, the reaction pressure in the reactor is 1.5 to 5 MPa. In another specific embodiment, the reaction temperature in the reactor is 60-100 ℃.

According to the invention, the alkane, such as the alkane in the mixed liquid I, such as the alkane in the material flow IIIa or IIIb, has high vaporization latent heat and large heat transfer quantity, and can be used as a condensing agent. Thus, the reaction temperature in the polymerization zone into which the alkane is fed in the reactor is different from the reaction temperature in the other polymerization zones. According to a particular embodiment of the invention, the reactor is a fluidized bed reactor. The material flow is circulated in the whole reaction system including fluidized bed reactor, pipeline, heat exchange equipment, separation equipment and the like.

According to a particularly preferred embodiment of the invention, the reactor comprises reaction zones of different temperatures. The reactor is provided with a polymerization reaction zone into which a condensing agent (alkane) is input, the polymerization temperature is relatively low and is a low-temperature reaction zone, and the polymerization reaction zone into which no condensing agent is input is relatively high and is a high-temperature reaction zone. According to a specific embodiment of the invention, the reaction temperature of the low-temperature reaction zone is controlled at 60-75 ℃, preferably 65-75 ℃; the reaction temperature in the high-temperature reaction zone is controlled to be 75-100 ℃, preferably 80-90 ℃.

According to a preferred embodiment of the present invention, the superficial fluidization gas velocity of the fluidized-bed reactor is in the range of 0.1 to 10 m/s. The method of the present invention strictly controls the superficial fluidizing gas velocity of the fluidized bed reactor and aims at ensuring the good fluidizing state of the reactor and avoiding the large amount of powder material being carried out. When the superficial fluidization gas velocity is 0.3-0.8m/s, the method can further ensure the stable operation of the fluidized bed reactor and simultaneously ensure the stable existence of the low-temperature reaction zone and the high-temperature reaction zone. The reason may be that the superficial fluidization gas velocity is higher than the initial fluidization velocity of the bulk powder and lower than the entrainment velocity of most of the powder particles.

According to a preferred embodiment of the invention, the effluent stream II from the reactor contains alkanes and possibly unreacted olefin monomers (possibly ethylene and alpha-olefins). The components of the material flow II and the material flow III are not different greatly, and the mass flow rate is not different greatly. In a particular example, the mass flow of stream II is more than 90%, preferably more than 95% to 100% of the mass flow of stream III.

As the reaction proceeds and the polymer is discharged, make-up olefin feed is required. Said stream III, obtained after feeding with make-up olefin feed (involving make-up ethylene feed and make-up alpha-olefin feed), has an olefin content of from 1.0 to 60.0 mol%, such as preferably from 5.0 to 55.0 mol%. Wherein, in a specific example, the molar concentration of the alpha-olefin in the stream III is between 20% and 60% of the molar concentration of the ethylene.

According to a preferred embodiment of the invention, the stream III comprises regulators and/or inert components. The regulator is adopted, and the molecular weight distribution of the ethylene polymer obtained by polymerization can be regulated according to different contents of the regulator. Among them, the regulator is preferably hydrogen gas. By using inert components, part of the heat generated during the polymerization can be removed and the composition of stream III can also be adjusted. Among them, the inert component is preferably nitrogen. In this case, the stream II flowing out of the reactor may contain regulators and/or inert components. In one embodiment, the content of said modifier in said stream III is controlled to be between 0.3 and 14.5 mol%. In another embodiment, the amount of inert components in the stream III is controlled to be in the range of from 25.0 to 75.0 mol%. In a specific example, the alkane content of said stream III is controlled to be in the range of 0.5 to 50.0 mol%, such as 1.0 to 35.0 mol%. At least one of a make-up alkane feed, an inert component feed, and a make-up modifier feed may also be included in stream III to better control the composition in stream III, depending on the process requirements.

According to a preferred embodiment of the invention, said stream III is divided into streams IIIa and IIIb after compression and gas-liquid separation. Wherein stream IIIa flows into the reactor through the side of the reactor. And stream IIIb flows into the reactor through the bottom of the reactor. According to one embodiment of the invention, the alkane in stream IIIa represents 60 to 90 wt.% of the total alkane in stream III. I.e. the alkane in stream III flows mostly into the reactor from the side of the reactor via stream IIIa. According to one embodiment of the invention, the olefins in stream IIIa represent from 10 to 50% by weight of the total amount of olefins in stream III.

According to another embodiment of the invention, in both IIIa and IIIb, there are regulators and inert components. Wherein the amount of regulator in IIIb is 50-100% wt of the amount of regulator in III. The amount of inert components in IIIa is 10-100% wt of the amount of inert components in III. Wherein the alpha-olefins in stream IIIa represent from 10 to 100 wt% of the total alpha-olefins in stream III.

In the process of the present invention, the temperature of the polymerization reaction zone refers to the highest temperature in the polymerization reaction zone. According to one embodiment of the invention, the alkane and alkene monomers in stream IIIa are passed into the fluidized bed reactor from the side, while the remaining alkane and alkene monomers in stream III are fed into the fluidized bed reactor from the bottom in stream IIIb. This can further improve the efficiency of heat removal in the reactor and the space-time yield of the reaction.

In the method of the invention, after the olefin polymer flows out of the fluidized bed reactor, the olefin polymer enters a storage tank and a purge tank to purge and remove olefin monomers in the olefin polymer by inert components, then enters a degassing bin to further remove the olefin monomers in the olefin polymer, and finally the ethylene polymer is discharged from the lower part of the degassing bin to be granulated.

According to the present invention, the α -olefin is selected from at least one of propylene, 1-butene, 1-pentene, 1-hexene, 1-octene and 1-decene.

According to a preferred embodiment of the present invention, the ethylene polymer is prepared with moles of said alpha-olefin monomer unitsThe content is 1-30%. For example, the molar content of alpha-olefin monomer units is 1 to 10%. The content of alpha-olefin monomer units of the polymer (accessible C)¹³NMR) is higher than that produced by other methods, and the degree of branching is higher; and wherein the monomer units of alpha-olefin monomer units head-to-head (meaning that the two carbon atoms to which the pendant groups are attached are directly attached) are higher in content than those prepared by other methods; further, it is advantageous to improve the haze and the self-adhesiveness.

According to a preferred embodiment of the present invention, the ethylene polymer produced has a density of 0.890g/cm³To 0.922g/cm³Preferably 0.895 to 0.917g/cm³. In the ethylene polymer, the melt flow rate at 230 ℃ and 2.16kg is 0.1 to 10g/10min, preferably 0.5 to 5.0g/10 min. The weight average molecular weight of the ethylene polymer is 20000-250000, and the molecular weight distribution index is 2-15.

According to a preferred embodiment of the present invention, the ethylene polymer has a melting point of 110-. The ethylene polymer has a haze of less than 12.0%, preferably less than 10.3%, more preferably less than 9.6%, such as less than 9.0%. The ethylene polymer has a self-adhesion value of 0.2N/cm²-1N/cm²Preferably 0.3N/cm²-1N/cm²。

In the process of the present invention, the space-time yield refers to the yield of olefin polymer per unit bed volume per unit time.

According to a preferred embodiment of the invention, the film has a self-adhesion of 0.2N/cm²-2N/cm²Preferably 0.3N/cm²-1N/cm². In a particular embodiment, the film has a self-adhesiveness of not less than 0.6N/cm². The haze of the film is less than 6.0%, preferably less than 5.0%, more preferably less than 4.0%. In a specific embodiment, the film has a haze of no greater than 1.5%.

According to the invention, in step 2), the ethylene polymer obtained in step 1) is subjected to a blow molding process to obtain a polyethylene film. The thickness of the film is conventional in the art. In one embodiment, the film is a BOPE film (biaxially oriented polyethylene film). The blow molding process is a blow molding process commonly used in the art, and the parameters are parameters commonly used in the prior art and are not described herein again.

According to a preferred embodiment of the present invention, in the step 2), the ethylene polymer prepared in the step 1) is used as a core layer to prepare a BOPE film. The skin layer of the BOPE film can adopt the skin layer commonly used in the prior art, such as the skin layer of the polypropylene copolymer and/or the linear low density polyethylene.

According to another aspect of the invention, the application of the polyethylene film prepared by the method in packaging materials and/or commodity labels is also provided. Wherein the application comprises preparing the film by the method and then using the film in packaging materials and/or commodity labels. The film has the advantages of good comprehensive performance, high self-adhesion, low haze, high light transmittance, good puncture resistance, high tear strength, high tensile strength, high tangent modulus and the like, and can be widely used in cooking films, high-transparency films, barrier protective films, heat sealing films or label films.

Compared with the prior art, the invention utilizes the fluidized bed reactor with liquid condensation process to prepare ethylene polymer, and utilizes the mixed liquid containing high alpha-olefin/ethylene molar ratio to send the main catalyst into the reactor, the material flow IIIa flows into the reactor through the side part of the reactor, and the material flow IIIb flows into the reactor through the bottom part of the reactor; more reaction zones with different temperatures can be further formed in the reactor, so that the polymer with high and low molecular weights, high and low branching degrees, micro-uniform mixing and a specific structure is obtained, the content of molecular chains containing high branching degrees is further improved, and a high-performance film is further prepared. The method of the invention has simple process; the operation is simple and convenient; the investment cost of facilities is low; the continuous stability is good; diversified polyethylene films can be produced; the obtained film has good comprehensive performance, reduced haze, improved light transmittance, or improved self-adhesion. Meanwhile, the film has good puncture resistance, high tear strength, high tensile strength, high tangent modulus and the like.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings briefly described below are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 shows a schematic representation of a reaction apparatus for carrying out the process according to the invention.

FIG. 2 shows a schematic representation of the formation of multiple olefin polymerization reaction zones within a fluidized bed reactor that differ in temperature.

In the drawings, like components are denoted by like reference numerals. The figures are not drawn to scale. The reference numerals are explained below:

1 distribution plate

2 a fluidized bed reactor;

3, a compression device;

4a heat exchange device;

5, separating equipment;

6 a feeding pump;

7 gas circulation pipeline;

8, discharging a tank;

9 purging the tank;

10 degassing bin;

11 a fluid pipeline for introducing the main catalyst into the reactor by taking the mixed solution I as a carrier stream;

12 and 19 a fluid conduit for introducing stream IIIa into the reactor;

13 a fluid line for withdrawing solid ethylene polymer from the reactor;

14 for feeding H₂、N₂And a fluid conduit for introducing ethylene into the recycle line;

15 a fluid conduit for introducing alpha-olefin comonomer into the recycle line;

16 a fluid conduit for introducing a condensing agent into the circulation line;

17 a fluid conduit for introducing the stream IIIb separated by the separation device into the reactor;

18 a pump for delivering the mixed liquid I to the pipe 11;

19. means for feeding main catalyst powder into the duct 11.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to examples, but those skilled in the art will appreciate that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.

Method for characterizing structure and performance of ethylene polymer

(1) Characterization of melting and crystallization temperatures: differential Scanning Calorimetry (DSC).

The sample to be tested is weighed at about 6mg, heated at a rate of 20 ℃/min to about 220 ℃ and held in a nitrogen stream for 2min, then cooled at a rate of 20 ℃/min to about 40 ℃, and held at this temperature for 2min to crystallize the sample. The sample was then re-melted by heating to 220 ℃ at a ramp rate of 20 ℃/min. The melting scan was recorded, a thermogram was obtained, and the melting temperature and crystallization temperature were read therefrom.

(2) Characterization of weight average molecular weight (Mw): gel Permeation Chromatography (GPC).

The sample to be tested was prepared at a concentration of 70mg/50ml of stabilized 1,2, 4-trichlorobenzene (250. mu.g/ml BHT (CAS REGISTRYNUMBER 128-37-0), and then the sample was heated to 170 ℃ for 2.5 hours for dissolution, measured on a Waters GPCV2000 at 145 ℃ at a flow rate of 1.0ml/min. with the same stabilizing solvent, and three Polymer Lab columns were used in series (Plgel, 20 μm mixed ALS, 300X 7.5 mm).

(3) Determination of molecular weight distribution index (PDI): model RMS-800 flat plate rheometer from Rheometrics.

The operation was carried out with increasing vibration frequency from 0.1rad/s to 100 rad/s. The cross modulus (crossover modules) can be derived from PI by the following equation: PI 105/Gc, where Gc is the cross modulus, which is the value determined when G '═ G "(expressed in Pa), where G' is the storage modulus and G" is the loss modulus.

(4) Characterization of melt flow index (MFR): measured according to ISO method 1133 at 230 ℃/2.16 kg.

(5) And (3) determination of ethylene content: IR spectroscopy.

(6) Determination of the alpha-olefin content: IR spectroscopy.

(7) Measurement of Density: determined according to ISO 1183.

(8) Thickness: determined according to GB/T6672-.

(9) Tear strength: measured according to ASTM D1922.

(10) Puncture resistance: determined according to BB/T0024-.

(11) Transparency: determined according to BB/T0024-;

(12) haze: measured according to GB/T2410-.

(13) Self-adhesion: determined according to GB/T10457-.

In a specific example, as shown in FIG. 1, in a fluidized bed reactor 2 having nitrogen gas fluidized therein, a main catalyst powder of Ziegler-Natta catalyst is first fed into a pipe 11 connected to the reactor 2 through a device 19 such as a feeding device, a mixed liquid I containing alkane and alkene is fed into the pipe 11 by a pump device 18, the main catalyst powder is fed into the reactor 2 by using the mixed liquid 11 as a carrier, and the mixed liquid I further contains a cocatalyst, wherein one or more connections between the pipe 11 and the reactor 2 may be provided. A line 7 is connected to the top expanded section of the fluidized bed reactor 2 for receiving a stream II from the fluidized bed reactor 2. The feed in stream II may contain unreacted olefin monomer as well as alkanes and the like. Stream III is obtained after make-up of the olefin feed (which may be via 14 and line 15). Stream II can also be supplemented with alkane feed (via line 16) and make-up modifier (via line 14, e.g., H) as required by the experiment₂) And inert component feed (via line 14, e.g. N)₂) Etc., to obtain stream III. The stream III is distributed to the streams IIIa and IIIbInto the bottom and top of the reactor. In one embodiment, stream III from heat exchanger 4 is passed through a gas-liquid separator 5 to be divided into streams IIIa and IIIb. The major part of the total content of condensate in stream III is located in stream IIIa which is injected into the fluidized bed reactor 2 via fluid lines 12 and 19 (the feed rate can be increased by pump 6) and the remainder of the condensate is located in stream IIIb and enters the fluidized bed reactor 2 with fluid line 17 below the distribution plate 1, wherein the connection of line 19 to reactor 2 can be one or more. According to the method of the present invention, a high-temperature reaction zone A and a low-temperature reaction zone B are formed in a fluidized bed reactor, as shown in FIG. 2.

The solid polymer generated in the polymerization reaction is intermittently discharged from a fluid pipeline 13, and is conveyed to a downstream working section for further processing after being devolatilized by a discharging tank 8, a purging tank 9 and a degassing bin 10. An ethylene polymer was obtained.

Example 1

This example uses magnesium chloride-loaded TiCl₃A Ziegler-Natta catalyst which is a main catalyst (the feeding amount of the main catalyst is 2.18kg/h) and takes triethyl aluminum as a cocatalyst. Wherein the molar ratio of the main catalyst to the cocatalyst is 3.11 in terms of Ti/Al. The reaction scheme is shown in FIG. 1.

The mass flow of the mixed liquid I is 1.8t/h and accounts for 0.42 percent of the mass flow of the material flow II. In the mixed liquid I, the alkane was contained in an amount of 50% by weight of the mixed liquid (molar content was 49%), the olefin was contained in an amount of 50% by weight of the mixed liquid (molar content was 51%), wherein the ethylene content was 4.9% by weight of the mixed liquid (molar content was 12.5%), and the 1-hexene content was 45.1% by weight of the mixed liquid (molar content was 38.5%). The mixed liquid I also contained 200ppm of triethylaluminum co-catalyst.

The superficial fluidization gas velocity in the reactor was 0.75 m/s. The pressure in the reactor was 2.1MPa and the temperature was 89 ℃.

After the supplementary feeding in the material flow II, the material flow III is obtained. The mass flow of stream II accounted for 97.8% of the mass flow of stream III. 80 wt% of the isopentane in stream III was in stream IIIa and the remainder was in stream IIIb.

The polymerization time is 2h, and finally the ethylene/1-hexene binary copolymer, namely the ethylene-hexane binary polymer A, is obtained.

The contents of the individual components of stream III in this example are reported in Table 1 below.

TABLE 1

The characterization results of the properties and structure of the ethylhexyl binary polymer a prepared in this example are shown in table 4 below.

Example 2

This example uses magnesium chloride-loaded TiCl₃A Ziegler-Natta catalyst which is a main catalyst (with the loading of 1.75kg/h) and takes triethyl aluminum as a cocatalyst. Wherein the molar ratio of the main catalyst to the cocatalyst is 3.11 in terms of Ti/Al. The reaction scheme is shown in FIG. 1.

The mass flow of the mixed liquid I is 1.3t/h and accounts for 0.30 percent of the mass flow of the material flow II. In the mixed liquid I, the content of alkane isopentane was 45 wt% (molar content was 35%) and the content of olefin was 55 wt% (molar content was 65%) of the mixed liquid, wherein the content of ethylene was 8.8 wt% (molar content was 17.8%) and the content of 1-butene was 46.2 wt% (molar content was 47.2%) of the mixed liquid, and the mixed liquid further contained 180ppm of a triethylaluminum co-catalyst.

The superficial fluidization gas velocity in the reactor was 0.70 m/s. The pressure of the fluidized bed reactor was 2.0MPa and the temperature was 88 ℃.

After the supplementary feeding in the material flow II, the material flow III is obtained. The mass flow of stream II accounted for 96.8% of the mass flow of stream III. 80 wt% of the isopentane in stream III was in stream IIIa and the remainder was in stream IIIb.

The polymerization time is 2h, and finally the ethylene/1-butylene binary copolymer, namely the ethylene-butylene binary polymer B, is obtained.

The contents of the individual components of stream III in this example are reported in Table 2 below.

TABLE 2

The characterization results of the properties and structure of the polymer B prepared in this example are shown in Table 4 below.

Example 3

This example uses magnesium chloride-loaded TiCl₃Ziegler-Natta catalyst (main catalyst feeding amount 2.03kg/h) and triethyl aluminum as a cocatalyst. Wherein the molar ratio of the main catalyst to the cocatalyst is 3.11 in terms of Ti/Al. The reaction scheme is shown in FIG. 1.

The mass flow of the mixed liquid I is 1.7t/h and accounts for 0.37 percent of the mass flow of the material flow II. In the mixed liquid I, the content of alkane-n-hexane was 25% by weight (molar content was 25%) of the mixed liquid, the content of olefin was 75% by weight (molar content was 75%) of the mixed liquid, wherein the content of ethylene was 7.8% by weight (molar content was 23.8%) of the mixed liquid, and the content of 1-octene was 67.2% by weight (molar content was 51.2%) of the mixed liquid, and the mixed liquid further contained 180ppm of triethylaluminum co-catalyst.

The superficial fluidization gas velocity in the reactor was 0.68 m/s. The pressure of the fluidized bed reactor was 2.1MPa and the temperature was 87 ℃.

After the supplementary feeding in the material flow II, the material flow III is obtained. The mass flow of stream II accounted for 97.2% of the mass flow of stream III. 80 wt% of the isopentane in stream III was in stream IIIa and in stream IIIb.

The contents of the individual components of stream III in this example are reported in Table 3 below.

TABLE 3

The characterization results of the properties and structure of the polymer C prepared in this example are shown in Table 4 below.

Comparative example 1

This comparative example used the procedure disclosed in WO00/02929A1, example 35, to prepare an ethylene-hexane dipolymer D starting from ethylene and 1-hexene.

The characterization results of the properties and structure of the hexanediyl polymer D prepared by this comparative example are shown in table 4 below.

Comparative example 2

The difference from example 1 is that no mixed liquid I is used, and the cocatalyst and the main catalyst are directly added into the reactor, and ethylene and 1-hexene are used as raw materials to prepare the ethylene-hexane binary polymer E. That is, the process in this comparative example was similar to CN104628904CN, but the amounts of feed were different. The characterization results of the properties and structure of the ethylhexyl binary polymer E prepared by this comparative example are shown in Table 4 below.

Comparative example 3

The same as example 2, except that the cocatalyst and the main catalyst were directly added to the reactor without mixing the liquid I, and ethylene and 1-butene were used as raw materials to prepare the ethylene-butadiene unit polymer F. That is, the process in this comparative example was similar to CN104628904CN, but the amounts of feed were different. The characterization results of the properties and the structure of the ethylhexyl binary polymer F prepared by the comparative example are shown in the following Table 4.

TABLE 4

From the above results of characterization of the ethylene polymers prepared in examples 1-3 and comparative examples, it can be seen that the polymers A, B and C prepared in examples 1-3 have a higher content of alpha-olefin monomer units than the polymers D-F of comparative examples 1-3, and the content of head-to-head alpha-olefin monomer units is higher, indicating that the ethylene polymers obtained by the process of the present invention have more branches and higher degree of branching.

In addition, the copolymer prepared by the method of the invention has lower melt index MFR, obviously lower molecular weight distribution coefficient PI, density and haze than the polymer of the comparative example and higher self-adhesiveness than the copolymer of the comparative example under the condition of the same monomer and relatively close weight average molecular weight of the polymer (see example 1 and comparative examples 1 and 2, and example 2 and comparative example 3). This is relevant for the production process. According to the production method of the invention, the content of the molecular chain with high branching degree is high, the chain entanglement degree is increased, the adhesive property is improved, and further, the density is reduced, the haze is reduced, and the self-adhesion is improved.

In examples 1-3, the copolymer having octene as a comonomer had the longest branch length; the copolymer with butene as comonomer has the shortest branch length, so the haze is C < A < B, and the self-adhesiveness is C > A > B.

From the above characterization results of the ethylene polymers prepared in examples 1-3 and comparative examples 1-3, it can be seen that further using a mixed solution containing alkane and alkene as a carrier to transport the main catalyst into the reactor, and controlling the mole ratio of alpha-olefin to ethylene therein is more beneficial to increase the branching degree, and is beneficial to decrease the polymer density, decrease the haze, increase the self-adhesiveness and narrow the molecular weight distribution.

The following are examples of the preparation of BOPE films

Example 4

(1) Preparation of BOPE film

The BOPE film of this embodiment includes three total layers of outer layer 1, sandwich layer and outer layer 2 in proper order, and outer layer 1 and outer layer 2 link to each other with the both sides face of sandwich layer respectively, and outer layer 1 and 2 are the outermost layer of film and external environment direct contact.

The external layer 1 and the external layer 2 are prepared from the following raw materials in parts by weight: 70 wt% of Linear Low Density Polyethylene (LLDPE) with the trade name SP1520 from Mitsui chemical company, 10 wt% of copolymerized polypropylene (MFR ═ 2g/10min) with the trade name H5200 from Korean LG chemical company, 16 wt% of Metallocene Polyethylene (MPE) with the trade name Exceded 1327KD from Exxon Mobil chemical company, and 4 wt% of anti-blocking master batch (ABPP 905 DCPP).

The core layer comprises the following raw materials in parts by weight: 94 wt% of the ethylene/1-hexene copolymer obtained in example 1 (ethylene-hexene dipolymer A), 3 wt% of a slip functional masterbatch (603PP), 3 wt% of a carbon octamer (ethylene-octene copolymer synthesized by metallocene catalyst, Dow 488-4A).

The outer layer 1, the outer layer 2 and the core layer material are uniformly mixed according to the proportion, then are conveyed to a storage tank, are respectively conveyed to three single-screw extruders through pipelines to be extruded, and are extruded into a tube blank through a three-layer co-extrusion die head, wherein the layering weight proportion of the tube blank is the outer layer 1: core layer: the outer layer 2 is 20:60:20, the screw diameter of the single screw extruder of the outer layer is 50mm, the length-diameter ratio is 30:1, the extrusion temperature is 220 ℃, the screw diameter of the single screw extruder of the core layer is 100mm, the length-diameter ratio is 30:1, the extrusion temperature is 220 ℃, the extruded materials are converged in a three-layer co-extrusion die head to form a tube blank, the temperature of the extrusion die head is 223 ℃, and the extruded tube blank is drawn into a stretching oven after being cooled. And (3) filling compressed air into the tube blank in a stretching oven for stretching, wherein the stretching temperature is 116 ℃, the transverse stretching multiple is 2.2-2.7, and the longitudinal stretching multiple is 2.2-2.7, so that a film with the thickness of 25 mu m can be obtained, and the biaxially oriented film is forcibly cooled by an air ring, split, rolled and slit to obtain a final product, namely a BOPE film G.

(2) Characterization of the Properties of the BOPE films

The performance characterization results of the BOPE film G prepared in this example are detailed in table 5 below.

Example 5

(1) Preparation of BOPE film

The external layer 1 and the external layer 2 are prepared from the following raw materials in parts by weight: 70 wt% of Linear Low Density Polyethylene (LLDPE) having a trade name SP1520 from Mitsui chemical company, 10 wt% of copolymerized polypropylene (MFR ═ 2g/10min) having a trade name H5200 from Korean LG chemical company, 16 wt% of Metallocene Polyethylene (MPE) having a trade name Exceded 1327KD from Exxon Mobil chemical company, and 4 wt% of anti-blocking master batch.

The core layer comprises the following raw materials in parts by weight: 94% by weight of the ethylene/1-butene copolymer obtained in example 2 (ethylene-butylene B) 3% by weight of a slip-functional masterbatch (as in example 4) and 3% by weight of a carbon octant (as in example 4).

The outer layer 1, the outer layer 2 and the core layer material are uniformly mixed according to the proportion, then are conveyed to a storage tank, are respectively conveyed to three single-screw extruders through pipelines to be extruded, and are extruded into a tube blank through a three-layer co-extrusion die head, wherein the layering weight proportion of the tube blank is the outer layer 1: core layer: the outer layer 2 is 20:60:20, the screw diameter of the single screw extruder of the outer layer is 50mm, the length-diameter ratio is 30:1, the extrusion temperature is 220 ℃, the screw diameter of the single screw extruder of the core layer is 100mm, the length-diameter ratio is 30:1, the extrusion temperature is 220 ℃, the extruded materials are converged in a three-layer co-extrusion die head to form a tube blank, the temperature of the extrusion die head is 223 ℃, and the extruded tube blank is drawn into a stretching oven after being cooled. And (3) filling compressed air into the tube blank in a stretching oven for stretching, wherein the stretching temperature is 116 ℃, the transverse stretching multiple is 2.2-2.7, and the longitudinal stretching multiple is 2.2-2.7, so that a film with the thickness of 25 mu m can be obtained, the film after the biaxial stretching is forcibly cooled by an air ring, and the film is wound and slit after being split, so that a final product, namely a BOPE film H, is obtained.

(2) Characterization of the Properties of the BOPE films

The performance characterization results of the BOPE film H prepared in this example are detailed in table 5 below.

Example 6

(1) Preparation of BOPE film

The external layer 1 and the external layer 2 are prepared from the following raw materials in parts by weight: 70 wt% of Linear Low Density Polyethylene (LLDPE) having a trade name SP1520 from Mitsui chemical company, 10 wt% of copolymerized polypropylene (MFR 2g/10min) having a trade name H5200 from Korean LG chemical company, 16 wt% of Metallocene Polyethylene (MPE) having a trade name Exceded 1327KD from Exxonfu chemical company, and 4 wt% of anti-blocking master batch (same as example 4).

The core layer comprises the following raw materials in parts by weight: 94% by weight of the ethylene/1-octene copolymer obtained in example 3 (polymer C of ethylene-diene origin), 3% by weight of a slip-functional masterbatch (as in example 4), 3% by weight of a carbon octant (as in example 4).

The outer layer 1, the outer layer 2 and the core layer material are uniformly mixed according to the proportion, then are conveyed to a storage tank, are respectively conveyed to three single-screw extruders through pipelines to be extruded, and are extruded into a tube blank through a three-layer co-extrusion die head, wherein the layering weight proportion of the tube blank is the outer layer 1: core layer: the outer layer 2 is 20:60:20, the screw diameter of the single screw extruder of the outer layer is 50mm, the length-diameter ratio is 30:1, the extrusion temperature is 220 ℃, the screw diameter of the single screw extruder of the core layer is 100mm, the length-diameter ratio is 30:1, the extrusion temperature is 220 ℃, the extruded materials are converged in a three-layer co-extrusion die head to form a tube blank, the temperature of the extrusion die head is 223 ℃, and the extruded tube blank is drawn into a stretching oven after being cooled. And (3) filling compressed air into the tube blank in a stretching oven for stretching, wherein the stretching temperature is 116 ℃, the transverse stretching multiple is 2.2-2.7, and the longitudinal stretching multiple is 2.2-2.7, so that a film with the thickness of 25 mu m can be obtained, and the biaxially oriented film is forcibly cooled by an air ring, split, rolled and slit to obtain a final product, namely a BOPE film I.

(2) Characterization of the Properties of the BOPE films

The performance characterization results of the BOPE film I prepared in this example are detailed in table 5 below.

Comparative example 4

(1) Preparation of BOPE film

The core layer comprises the following raw materials in parts by weight: 94 wt% of the ethylene/1-hexene copolymer (ethylhexyl dipolymer D) obtained in comparative example 1, 3 wt% of a slip functional masterbatch, 3 wt% of a carbon octamer.

The outer layer 1, the outer layer 2 and the core layer material are uniformly mixed according to the proportion, then are conveyed to a storage tank, are respectively conveyed to three single-screw extruders through pipelines to be extruded, and are extruded into a tube blank through a three-layer co-extrusion die head, wherein the layering weight proportion of the tube blank is the outer layer 1: core layer: the outer layer 2 is 20:60:20, the screw diameter of the single screw extruder of the outer layer is 50mm, the length-diameter ratio is 30:1, the extrusion temperature is 220 ℃, the screw diameter of the single screw extruder of the core layer is 100mm, the length-diameter ratio is 30:1, the extrusion temperature is 220 ℃, the extruded materials are converged in a three-layer co-extrusion die head to form a tube blank, the temperature of the extrusion die head is 223 ℃, and the extruded tube blank is drawn into a stretching oven after being cooled. And (3) filling compressed air into the tube blank in a stretching oven for stretching, wherein the stretching temperature is 116 ℃, the transverse stretching multiple is 2.2-2.7, and the longitudinal stretching multiple is 2.2-2.7, so that a film with the thickness of 25 mu m can be obtained, and the biaxially oriented film is forcibly cooled by an air ring, split, rolled and slit to obtain a final product, namely a BOPE film J.

(2) Characterization of the Properties of the BOPE films

The performance characterization results of the BOPE film J prepared in this example are detailed in table 5 below.

Comparative example 5

(1) Preparation of BOPE film

The external layer 1 and the external layer 2 are prepared from the following raw materials in parts by weight: 70 wt% of Linear Low Density Polyethylene (LLDPE) having a trade name SP1520 from Mitsui chemical company, 10 wt% of copolymerized polypropylene (MFR 2g/10min) having a trade name H5200 from Korean LG chemical company, 16 wt% of Metallocene Polyethylene (MPE) having a trade name Exceed1327KD from Exxonfu chemical company, and 4 wt% of anti-blocking master batch (same as example 4).

The core layer comprises the following raw materials in parts by weight: 94% by weight of the ethylene/1-hexene copolymer obtained in comparative example 2 (ethylene-hexane bipolymer E), 3% by weight of a slip-functional masterbatch (as in example 4), 3% by weight of a carbon octamer (as in example 4).

The outer layer 1, the outer layer 2 and the core layer material are uniformly mixed according to the proportion, then are conveyed to a storage tank, are respectively conveyed to three single-screw extruders through pipelines to be extruded, and are extruded into a tube blank through a three-layer co-extrusion die head, wherein the layering weight proportion of the tube blank is the outer layer 1: core layer: the outer layer 2 is 20:60:20, the screw diameter of the single screw extruder of the outer layer is 50mm, the length-diameter ratio is 30:1, the extrusion temperature is 220 ℃, the screw diameter of the single screw extruder of the core layer is 100mm, the length-diameter ratio is 30:1, the extrusion temperature is 220 ℃, the extruded materials are converged in a three-layer co-extrusion die head to form a tube blank, the temperature of the extrusion die head is 223 ℃, and the extruded tube blank is drawn into a stretching oven after being cooled. And (3) filling compressed air into the tube blank in a stretching oven for stretching, wherein the stretching temperature is 116 ℃, the transverse stretching multiple is 2.2-2.7, and the longitudinal stretching multiple is 2.2-2.7, so that a film with the thickness of 25 mu m can be obtained, and the biaxially oriented film is forcibly cooled by an air ring, split, rolled and slit to obtain a final product, namely a BOPE film K.

(2) Characterization of the Properties of the BOPE films

The performance characterization results of the BOPE film K prepared in this example are detailed in table 5 below.

Comparative example 6

(1) Preparation of BOPE film

The core layer comprises the following raw materials in parts by weight: 94% by weight of the ethylene/1-butene copolymer obtained in comparative example 3 (ethylene-butylene copolymer F), 3% by weight of a slip-functional masterbatch (same as in example 4), 3% by weight of a carbon octant (same as in example 4).

The outer layer 1, the outer layer 2 and the core layer material are uniformly mixed according to the proportion, then are conveyed to a storage tank, are respectively conveyed to three single-screw extruders through pipelines to be extruded, and are extruded into a tube blank through a three-layer co-extrusion die head, wherein the layering weight proportion of the tube blank is the outer layer 1: core layer: the outer layer 2 is 20:60:20, the screw diameter of the single screw extruder of the outer layer is 50mm, the length-diameter ratio is 30:1, the extrusion temperature is 220 ℃, the screw diameter of the single screw extruder of the core layer is 100mm, the length-diameter ratio is 30:1, the extrusion temperature is 220 ℃, the extruded materials are converged in a three-layer co-extrusion die head to form a tube blank, the temperature of the extrusion die head is 223 ℃, and the extruded tube blank is drawn into a stretching oven after being cooled. And (3) filling compressed air into the tube blank in a stretching oven for stretching, wherein the stretching temperature is 116 ℃, the transverse stretching multiple is 2.2-2.7, and the longitudinal stretching multiple is 2.2-2.7, so that a film with the thickness of 25 mu m can be obtained, and the biaxially oriented film is forcibly cooled by an air ring, split, rolled and slit to obtain a final product, namely a BOPE film L.

(2) Characterization of the Properties of the BOPE films

The performance characterization results of the BOPE film L prepared in this example are detailed in table 5 below.

TABLE 5

Comparing examples 4-6 above with comparative examples 4-6, it can be seen that both the tear strength and puncture resistance of BOPE films G, H and I are significantly better than BOPE film J, K, L. In particular, the BOPE film G, H, I formed from the copolymer A, B, C prepared by the method of the present invention had superior self-adhesion, haze, and light transmission to the BOPE film J, K, L of comparative example, where haze was lower than the data for comparative example and light transmission and self-adhesion were higher than the data for comparative example. . The polyethylene produced by the method has high content of alpha-olefin monomer units, and the alpha-olefin monomer units connected with the head are high in content, so that the branching degree is high, and the method is favorable for improving the movement capability of a strong molecular chain. Among them, the ethylene-propylene copolymer C having octene as a comonomer has the longest branch length, increased chain entanglement, and the highest adhesive property.

The film provided by the invention has the advantages of high light transmittance, high self-adhesion, low haze, low density, light weight, high performance such as tear strength and puncture resistance and the like, and further has wide application prospect.

Any numerical value mentioned in this specification, if there is only a two unit interval between any lowest value and any highest value, includes all values from the lowest value to the highest value incremented by one unit at a time. For example, if the amount of a component of a living being, or a value of a process variable such as temperature, pressure, time, etc., is 50 to 90, it is meant in this specification that values of 51 to 89, 52 to 88 … …, and 69 to 71, and 70 to 71, etc., are specifically enumerated. For non-integer values, units of 0.1, 0.01, 0.001, or 0.0001 may be considered as appropriate. These are only some specifically named examples. In a similar manner, all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be disclosed in this application.

It should be noted that the above-mentioned embodiments are only for explaining the present invention, and do not constitute any limitation to the present invention. The present invention has been described with reference to exemplary embodiments, but the words which have been used herein are words of description and illustration, rather than words of limitation. The invention can be modified, as prescribed, within the scope of the claims and without departing from the scope and spirit of the invention. Although the invention has been described herein with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed herein, but rather extends to all other methods and applications having the same functionality.

Claims

1. A preparation method of a polyethylene film comprises the following steps:

1) conveying a main catalyst in a catalyst system into a reactor by using a mixed liquid I as a carrier material flow, wherein the mixed liquid I comprises alkane, alkene and a cocatalyst; adding a supplementary olefin feed into a material flow II flowing out of the reactor to obtain a material flow III, dividing the material flow III into material flows IIIa and IIIb, and respectively refluxing the material flows IIIa and IIIb to the side part and the bottom part of the reactor; in the reactor, ethylene polymer is obtained through polymerization and discharged from the reactor; wherein the olefin comprises alpha-olefin and ethylene, and the molar ratio concentration ratio of the alpha-olefin to the ethylene in the mixed liquid I is at least 1;

2) subjecting the ethylene polymer prepared in the step 1) to a blow molding process to obtain a polyethylene film,

wherein the ethylene polymer has a self-adhesion of 0.2N/cm²-1N/cm²；

Wherein the ethylene polymer has a haze of less than 12.0%.

2. The method of claim 1, wherein the ethylene polymer has a self-adhesion of 0.3N/cm²-1N/cm²。

3. The method according to claim 1 or 2, wherein the polyethylene film is a biaxially oriented polyethylene film.

4. The process according to claim 1 or 2, wherein the molar ratio of the α -olefin to ethylene in the mixed liquid I is from 1 to 5; and/or the content of alkane in the mixed liquid is 5-80 wt%; and/or the mass flow of the mixed liquid I accounts for 0.05-5% of the mass flow of the material flow II.

5. The process according to claim 4, wherein the molar ratio of the α -olefin to ethylene in the mixed liquid I is from 1.3 to 5.

6. The method according to claim 5, wherein the molar ratio of the α -olefin to ethylene in the mixed liquid I is 1.5 to 5.

7. The method as claimed in claim 4, wherein the alkane is contained in the mixed liquid in an amount of 10 to 65 wt%.

8. The process according to claim 4, wherein the mass flow of the mixed liquid I is 0.1 to 3% of the mass flow of stream II.

9. The process according to claim 1 or 2, characterized in that the reaction pressure in the reactor is 0.5-10 MPa; the reaction temperature is 40-150 ℃; and/or the superficial gas velocity of the sulphide in the reactor is between 0.1 and 10 m/s.

10. The process of claim 9, wherein the reaction pressure in the reactor is 1.5 to 5 MPa.

11. The process of claim 9, wherein the reaction temperature is 60 to 100 ℃.

12. The process of claim 9 wherein the superficial sulfiding gas velocity in the reactor is in the range of 0.3 to 0.8 m/s.

13. The process of claim 1 or 2, wherein the reactor comprises reaction zones of different temperatures; and/or the reactor is a fluidized bed reactor.

14. The process according to claim 1 or 2, characterized in that the content of olefins in the stream III is between 1.0 and 60.0 mol%; the content of alkane is 0.5-50.0 mol%; or the molar concentration of the alpha-olefin in the stream III is 20-60% of the molar concentration of the ethylene.

15. The process according to claim 14, wherein the olefin content in stream III is between 5.0 and 55.0 mol%.

16. The method of claim 14, wherein the alkane is present in an amount of 1.0 to 35.0 mol%.

17. The process according to claim 1 or 2, characterized in that the alkane in stream IIIa represents 60-90 wt% of the total amount of alkane in stream III; and/or the olefins in stream IIIa represent from 10 to 50 wt% of the total olefins in stream III; and/or the mass flow rate of the material flow II accounts for more than 90 percent of the mass flow rate of the material flow III.

18. The process of claim 17, wherein the mass flow rate of stream II is greater than 95% of the mass flow rate of stream III.

19. A method according to claim 1 or 2, characterized in that said stream III comprises regulators and/or inert components.

20. The method of claim 19, wherein the modulating agent is hydrogen gas.

21. The method of claim 19, wherein the inert component is nitrogen.

22. The method of claim 19, wherein the modifier is present in an amount of 0.3 to 14.5 mol%; and/or in the stream II the amount of inert components is from 25.0 to 75.0 mol%.

23. The process of claim 5, wherein stream III comprises at least one of a make-up alkane feed, a make-up moderator feed, and a make-up inert component feed.

24. The method according to claim 1 or 2, wherein the alkane is selected from at least one of butane, isobutane, n-pentane, isopentane, n-hexane, cyclohexane and heptane; and/or the alpha-olefin is selected from at least one of propylene, 1-butene, 1-pentene, 1-hexene, 1-octene and 1-decene.

25. Method according to claim 1 or 2, characterized in that the film has a self-adhesion of 0.2N/cm²-2N/cm²(ii) a And/or the film has a haze of less than 6.0%.

26. The method of claim 25, wherein the film has a self-adhesion of 0.3N/cm²-1N/cm²。

27. The method of claim 25, wherein the film has a haze of less than 5.0%.

28. The method of claim 27, wherein the film has a haze of less than 4.0%.

29. The process of claim 1 or 2, wherein the catalyst system comprises a ziegler-natta catalyst, a metallocene catalyst, a transition metal catalyst, an inorganic chromium catalyst, and an organic chromium catalyst.

30. The process according to claim 1 or 2, wherein the ethylene polymer is produced with a molar content of α -olefin monomer units of 1 to 30%;

or the ethylene polymer prepared has the following characteristics: the density is 0.890g/cm³To 0.922g/cm³(ii) a In thatThe melt flow rate is 0.1-10g/10min at 230 ℃ and 2.16 kg; the weight-average molecular weight is 20000-250000, and the molecular weight distribution index is 2-15.

31. The process of claim 30 wherein the ethylene polymer is produced having a molar content of α -olefin monomer units of from 1 to 10%.

32. The method of claim 30, wherein the melt flow rate is 0.5 to 5.0g/10min at 230 ℃ and 2.16 kg.

33. The process of claim 1, wherein the ethylene polymer has a haze of less than 10.3%.

34. The method of claim 33, wherein the ethylene polymer has a haze of less than 9.6%.

35. Use of a polyethylene film prepared by the process of claim 1 or 2 in packaging materials and/or labels for goods.

36. The method of claim 35, wherein the polyethylene film is used in a retort film, a high clarity film, a barrier protective film, a heat seal film, or a label film.