KR820002059B1 - A method for reducing sharkskin melt fracture during extrusion of ethylene polymers - Google Patents

Abstract

The redn. of shark-skin melt fracture during extrusion of a molten narrow mol. wt. distribution ethylene polymer into film under conditions which would normally produce fracture is effected by extruding the polymer through a die with die gap greater than 50, pref. 50-200mils and where(part of) the surface of the die lip and/or die land in contact with the polymer is at a divergent or convergent angle relative to the axis of polymer flow.

Description

Reduction of Sharkskin Melt Fraction in the Extrusion Process of Ethylene Polymers

1 is a transverse cross-sectional view of a spiral / Spider annulus die.

2 is a cross section of a spiral die.

3a to 3av show various forms of die gaps.

4 is a fluidized bed reactor for preparing ethylene polymers.

The present invention relates to melt fractions, especially Shark-skin melts, which are expressed during extrusion of a molten ethylene polymer having a narrow molecular weight distribution and linearity under flow rate and melting temperature conditions at which melt fracture is produced. A method of reducing the fracture, wherein the method has a die gap of at least 50 mils and at least a portion of the die lip and / or die land surface in contact with the molten polymer diverges to the flow axis of the molten polymer through the die or And extruding the polymer through a die at a converging angle.

Low density polyethylene for commercial use polymerizes in thick walled autoclaves or tubular reactors at 50,000 psi pressure and temperatures up to 300 ° C. The molecular structure of high pressure low density polyethylene is very complex. The arrangement of a single structure block is not really limited. The high pressure resin is characterized by its complex and long side chain molecular structure. The high pressure low density polyethylene resin has 1 to 6 carbon atoms, which is a short side chain that controls the degree of crystallinity (density) of the resin. The distribution frequency of these short side chains means that most of the chains are flat and have the same average number of side chains.

The distribution of short side chains that characterize high pressure low density polyethylene is narrow. Low density polyethylene exhibits complex properties. That is, the mechanical properties such as tensile strength, impact resistance, rupture strength, and tear strength are excellent and flexible. In addition, the lowering of strength does not occur at a relatively low temperature, and there is no brittleness even at a temperature such as -70 ° C. Low density polyethylene is relatively inert to acids, alkalis and inorganic solutions because of its excellent chemical resistance. However, they are reactive with hydrocarbons, halogenated hydrocarbons, oils and greases.

More than 50% of all low density polyethylene is used for film processing. Such films are mainly used for packaging such as meat, agricultural products, frozen foods, ice packs, cut meats, fiber and paper products, rack products, industrial liners, shipping pouches, pallet stretch and sealink packaging. Heavy film is used in construction and agriculture in large quantities.

Most low density polyethylene films are made by tubular blow extrusion. Film products produced in this way are about 2 inches in diameter and are used as sleeves or pouches. Polyethylene is a medium catalyst by homopolymerizing or copolymerizing alpha-olefins and ethylene in water using heterogeneous catalysts of transition metal compounds with many atoms. It can be prepared at pressure. Generally, these resins have a small amount of long side chains and mostly consist of short side chains. The side chain length is adjusted in the form of comonomers. Branch frequency is controlled by the concentration of comonomer used in the copolymerization process, and the side chain distribution frequency is affected by the characteristics of the transition metal element used in the copolymerization process. The short side chains characteristic of low density polyethylene polymerized with transition metal catalysts are very wide.

F. second. Filed by Karl et al. And filed under the name of US Patent Application No. 892,325 (filed March 3, 1978) and registered Patent Application No. 014,414 (February 27, 1979), which are methods for the production of ethylene copolymers in fluidized bed reactors. ), Ethylene copolymers containing a density of 0.91 to 0.96, melt flow rates ≥22 to ≤32, and containing a relatively small amount of catalyst, have a high-performance Mg-Ti-containing complex catalyst mixed with an inert carrier material to form the monomer in a gas phase. It is described that when copolymerized in, it can be produced in a relatively high yield as a granular form.

G. L. US Patent Application No. 892,322 (filed March 31, 1978) and registered Patent Application No. 012,720 (February 16, 1979) filed by Gock et al. In one application), a high-performance Mg-Ti-containing complex catalyst impregnated with an ethylene copolymer porous inert carrier material having a density of 0.91 to 0.96, a melt flow rate of ≧ 22 to ≦ 32, and a relatively low residual catalyst content is used as a particulate form. It is described that it can be produced in high yield.

ratio. this. US Patent Application No. 892,037 (filed March 31, 1978) and Registered Patent Application No. 014,412 (February 27, 1979), filed by Wagner et al. And named for the polymerization catalyst, preparation method, and ethylene homopolymerization. The ethylene homopolymer has a density of ≧ 0.958 to ≦ 0.972, a melt flow rate of ≧ 22 to ≦ 32, and a low residual catalyst content. In the case of a low pressure vessel can be produced for a relatively high yield of goods. The granular polymers thus prepared are beneficial for a variety of end uses.

The polymer produced by the above process using an Mg-Ti containing complex catalyst has a narrow molecular weight fraction with Mw / Mn of about >

Low Density Polyethylene: Rheology

The rheology of the polymers depends on the size of the molecular weight and the molecular weight distribution. In the extrusion of the film, it is important in two rheological aspects: layer milling and stretching. Polymeric melts in film extruders and extrusion dies undergo severe laminar deformation. As the extrusion screw pumps the melt through the film die, the melt exhibits a wide range of laminar ratios. Most film extrusion processes expose the melt to delaminate at rates in the range of 100 to 5000 sec ⁻¹ . Polymeric melts are commonly known to exhibit shear thinning behavior, or non-Newtonian flow phenomena. As the layer mill ratio increases, the velocity (the ratio of layer mill strain force τ to the layer mill ratio γ) decreases. The rate of decrease depends on the molecular weight, distribution, molecular coordination, ie the long side chains of the polymer. Short side chains have little effect on laminar velocity.

In general, high pressure low density polyethylene is composed of a wide molecular weight distribution and exhibits more pronounced shear thinning behavior in the shear ratio range common to film extrusion. The resin used in the present invention, which is composed of a narrow molecular weight distribution, is less likely to decrease the layer milling ratio at the layer milling ratio of the extrusion grade. Due to this difference, the resin having a narrow molecular weight distribution used in the present invention requires a higher force in the extrusion process and generates a higher pressure than the resin having a wide molecular weight distribution and a resin having an equivalent average molecular weight distribution. The rheology of the polymers has usually been dealt with with regard to shear deformation. In simple bed milling, the strain rate gradient is perpendicular to the flow direction. The deformation method is easy to experiment but does not provide the data necessary to understand the material reactions in filmmaking. Shear viscosity can be defined as shear stress and shear rate. In other words, η layer milling = tau ₁₂ / ｊ, where η layer milling is the layer milling viscosity (Poise), τ ₁₂ is the layer milling strain (dynes / cm ² ), and j is the layer milling ratio (sec ^-1 ). On the other hand, the extensional viscosity can be defined as the stress and strain rate.

In other words

는 일그러짐 비율(sec^-1)은 나타낸다.In the above equation, η _ext stands for external viscosity and π stands for normal strain (dynes / cm ² ).

Is a distortion ratio (sec ⁻¹ ).

The high laminar strain produced during the extrusion of a high molecular weight ethylene polymer composed of a narrow molecular weight distribution results in melt fracture, particularly sharkskin melt fracture. Sharkskin melt fractions are reported in the literature on many polymers. "Sharkskin" is a term that refers to a special form of irregular surface that occurs during the extrusion of certain thermoplastics under certain conditions. The essence of this "sharkskin" is a series of uprights perpendicular to the flow direction. a. The flow characteristics of polymer melts by Bridson are described on pages 78-81 of the semi-North Rhine-Rhönt 1970 edition.

In the present invention, the sharkskin melt fraction is measured by visually observing the surface of the formed extrudate without being subjected to release stress from a capillary die. In particular, the method for measuring sharkskin melt fraction is as follows. Light is emitted from the side of the extrudate and observed with a magnification microscope of 40X. Under the microscope, the polished surface with low layer milling of the extrudate turned into a rough surface that reached the critical layer mill found by Sharkskin Meltture, and the sharkskin fraction with high layer milling was formed. This method can usually be done up to ± 10% of the striae strain. Ethylene polymers having a narrow molecular weight distribution described herein exhibit the properties of sharkskin melt fractions when extruded using prior art extrusion methods.

One of these characteristics is in the form of a waveform change perpendicular to the flow direction, which occurs at a low extrusion rate, i.e. less than the expected elastic turbulance. There is no effect and there is little change in melt fraction with temperature rise. There are several known methods for removing sharkskin melt fractions of polymers. One of these is raising the temperature of the resin. However, in film production, this method is not practical because the temperature rises due to bubble instability and the limitation of thermal conductivity, which lowers the film formation rate.

U.S. Patent No. 3,920,782 describes another method for removing sharkskin meltfraction.

Here, the sharkskin from the extrusion of the polymeric material is removed by cooling the surface of the extruded material to release the melt from the die at a reduced temperature while maintaining the ideal operating temperature. However, this method is very difficult to adjust. The invention of U.S. Patent No. 3,920,782 is based on the inventors' conclusion that the sharkskin meltfraction expressed in the light condition is the effect of the main cause exceeding the critical line velocity of the resin released from the die at operating temperature. However, in the method of the present invention, the sharkskin melt fraction of resins exhibited under constant operating conditions is mainly the result of exceeding the threshold of the layer milling strain and is considered to be the result of exceeding the threshold of the linear velocity. .

U.S. Patent No. 3,382,535 discloses a method of designing a die for use in high-speed extrusion coating of wires or cables with synthetic resins such as polypropylene, high density low density polyethylene, or polymers thereof. Sensitivity to the angle is good and sensitive.

The dies applied in the method of the present invention are designed to impart special strain conditions in high speed coating of wires and cables to prevent melt fractures that form roughly on the surface extruded with plastic on the wires.

Roughness on the surface of the coated wire is very different from that of the sharkskin melt fracture, which is subject to several different deformation conditions in the film making process. The invention of US Pat. No. 3,382,535 is significant in designing the taper angle of the die to converge the curved surface of the die (FIGS. 6 and 7 of the patent) in the flow direction of the resin.

In practice, however, the above method of reducing the taper angle of the die results in an increase in the threshold of the laminar ratio of the resin passing through the die.

The present invention relates to a method for reducing melt fraction by adjusting the exit dimension of a die.

The method of US Pat. No. 3,382,535 is implemented at a bedding ratio greater than about 200 sec ⁻¹ . In addition, the method of 3,382,535 above is to minimize the layer pressure drop of the die to be suitable for the final exit case of the die.

The method of the present invention using a converging die yields a high threshold layer ratio and can be processed without causing sharkskin meltfracture.

According to the method of the present invention using a converging die, the pressure drop of the die is reduced.

The resin applied to the method of the present invention is unaffected by the taper angle of the astringent die, which correlates with Sharkskin meltfraction expression.

U. S. Patent No. 3,879, 507 discloses a method of reducing melt fractions expressed in the process of extruding a foamable composition into a film or sheet.

This method is to increase the die land length or to slightly taper the die gap, which is certainly a relatively narrow range compared to the prior art in maintaining or reducing the die gap. 0.025 inches or 25 millimeters.

The method of the present invention is to apply a wide die gap of at least 50 mils using divergent or convergent dies.

According to the method of the invention the melt fraction, in particular the sharkskin melt fraction, is substantially reduced as a dimension change of the die. In other words, the ethylene polymer having a low molecular weight distribution is extruded through a die having a die gap of about 50 mils or more at a normal film extrusion temperature, wherein a portion of a die lip or die land surface in contact with the molten polymer is extruded. The above forms the divergence or convergence angle with respect to the flow axis of the molten polymer which passes through a die | dye.

The method utilization of the present invention is possible based on the fact that the occurrence of the Sharkskin melt fraction of the stress field at the die exit is determined. Sharkskin melt fractions can be adjusted and removed according to die exit dimensions and have nothing to do with die inlet or die land conditions. In this case, the design of the die to exclude or reduce molten fracture is based on a constant shear stress standard. That is, the die is configured such that the discharge shear stress is maintained at or near about 10 psi over a wide range of melt index (at least 0.5 to 20 MI) and temperature (about 325 ° F. to 500 ° F.). On the other hand, narrow dies, which typically have gap openings of less than 50 mils, suppress melt fracture at a constant critical velocity standard. The instrument is described on Brydson (Ibid), page 79, and requires a different design process within its range of usage (typically less than 50 mil gaps).

Suitable films for packaging should have a balance between wide end use and importance for a wide range of commercial uses. These properties include the optical qualities of the film, for example cloudy, glossy, and transparent. Mechanical strengths such as puncture resistance, tensile strength, impact strength, stiffness and tear resistance are important. Vapor permeability and gas permeability are important aspects in the packaging of perishable goods. Film conversion and packaging equipment is affected by film properties such as coefficient of friction, compartment, heat seal and flex resistance. Low density polyethylene has a wide range of uses, such as in food packaging and non-food packaging. Bags made of low density polyethylene generally include cargo bags, fiber bags, laundry and dry cleaning bags, and garbage bags. Low density polyethylene films are used as drum liners for various liquid and solid chemicals, as well as for inner wooden box protective packaging. Low density polyethylene films are used in various agricultural and horticultural applications for plant and crop protection, such as fruit and plant storage protection hats. Moreover, low density polyethylene films are also used in construction such as moisture or water vapor barriers. Low-density polyethylene films are also used for coatings and printing in newspapers and books.

As a suitable combination of these properties, high pressure low density polyethylene is most important for thermoplastic packaging films.

About 50% of the total use of such films is packaging. Films made from the polymers of the present invention, preferred as ethylene hydrocarbon copolymers, result in an improved combination of end use properties and are particularly suitable for many applications already met by high pressure low density polyethylene.

Improving some sort of film quality, such as eliminating or reducing sharkskin melted shells, or improving the extrusion properties of the resin, or the film extrusion process itself, has many advantages for high pressure low density polyethylene. It is extremely important about the adoption of this film as a substitute.

Narrow molecular weight distribution, linearity, melt fracture, especially sharkskin melt fracture, formed during melt extrusion of ethylene polymer can be reduced by extruding the polymer through a die having a die gap of at least about 50 mils, where the die in contact with the molten polymer At least a portion of the surface of the die lip and die land has an angle of divergence or convergence with respect to the flow axis of the molten polymer through the die.

The molten ethylene polymer is extruded through a die, preferably an annular die, having a die gap of about 50 to about 200 mils. Extrusion of the molten ethylene polymer through a die having a die gap of about 50 to about 200 millimeters is performed by US Patent Application No. 892,324 (filed March 31, 1978) to WAFraser et al. A patent application entitled "Method for Making Films with Low Density Ethylene Hydrocarbon Copolymers Re-applied by Patent Application No. 012,795) is described.

Dies used in the present invention include a spiral annular die, rod die and the like. FIG. 1 is a cross-sectional view through a spiral / spider annular die 1 through which molten thermoplastic ethylene polymer is extruded, and the die compartment 2 is a passage ( Include 3).

The molten thermoplastic ethylene polymer is extruded through the die passage. As a specific example, dimension b is about 140 mils and dimension a is about 40 mils. Die d has a diameter of about 1 to 72 inches, preferably 6 to 32 inches. Die gap c is about 100 mils.

2 is a cross-sectional view of the helical die 5 showing the helical region j, the low mouth region h, the die land g, and the die lips e and f. One specific dimension e and f is about 0.5 inches, g is about 2 inches, h is about 4 inches, and j is about 6 inches.

3 shows four different designs of Dilips. The die in FIG. 3 is one of the branched dies 6. The angle α is about 1 ° to about 45 °.

Dimension k is about 50 to about 200 mils, dimension m is about 0.00 to 1.5 inches, and dimension n is about 0.010 to 0.110 inches. The die of FIG. 3b has a convergent dilips 7 that come together. The die of FIG. 3C has both convergent dilips 8a and 8b. The die of FIG. 3av has both divergents 9a and 9b diverged.

In practice of the present invention, the angle of divergence or convergence is the area defined by the die land g and the die lip land f illustrated in FIG. The die into which the polymer melt enters is distributed around the die by helical dispensing (or other dispensing methods such as, for example, in a spider die) and distributed to die lands in land annular flow in annular flow.

As in the second case, the use of the helical die is enhanced to uniform flow using length g, such as shrinkage. That is, by combining the better shrinkage and the die lip and die land, there is no polymer melt, no sharkskin melt fracture and a good constant flow can be obtained.

When at least one side of the die lip and die land forms a convergence angle, the area following the die land may diverge and advance to the final convergence area.

It is desirable to have an angle entering the die land, which can be from about 5 to about 20 degrees.

[Film extrusion]

I. Blown Film Extrusion

Films prepared as described herein can be extruded by a tubular blown film extrusion process. In this process, the polymer having a narrow molecular weight distribution is melt-extruded through an extruder. The extruder has therein an extrusion screw having a length to diameter ratio of 15: 1 to 21: 1. Reference: U.S. Patent Application No. 940,005 (September 6, 1978), John S. Miller et al., U.S. Patent No. 064,399 (August 8, 1979), entitled `` Process of extruding ethylene polymers ''.

The application states that the extruded screw contains a feed, a transition and a meter. Optionally, the extruded screw may contain a mixture as described in US Pat. Nos. 3,486,192, 3,730,492 and 3,756,574. Preferably the mixing section is located at the end of the screw.

The extruder used in the present invention has a ratio of the length and the internal diameter of the arrangement of 18: 1 to 32: 1. The extrusion screw used in the present invention has a ratio of length to diameter of from 15: 1 to 32: 1. For example, when using an extruder screw having a ratio of 18/1 in length and diameter in an extruder with 24/1, the loading time of the polymer melt is partially installed by installing various types of plugs, primers or static mixers in the space remaining in the extrusion barrel. Can be reduced.

After melting, the polymer is extruded through a die as described below.

The polymer is extruded at temperatures between 325 and 500 ° F. and extruded vertically upwards in the form of tubes, although it can be extruded downwards or laterally. The molten polymer is extruded through the annular die and then the tubular film is expanded as desired and then cooled or left to cool and then flattened. The tubular film passes the film through the collapse mold and the nip roll to flatten and the nip roll operates to provide a device for removing the film from the annular die.

For example, a constant pressure of gas such as air or nitrogen is maintained in the tubular bubble. As can be seen in the operation of a conventional film process, the pressure of the gas is controlled to give the tubular film the desired degree of expansion. The extent of expansion is 1/1 to 6/1, preferably 1/1 to 4/1 as measured by the ratio between the fully expanded tube periphery and the circumference of the digit. The tubular extrudate is cooled by conventional methods such as air, dry quench or mandrel.

The water-lowering property of the polymer of the present invention is excellent. As defined in the ratio between the gap of the die and the gauge of the film product and the blowing ratio, the water depth is maintained at 2 or more and 250 or less, preferably 25 or more and 150 or less. Very thin gauge films can be produced at high water depths from these polymers even when they are severely contaminated with foreign material / or gel. A thin gauge film of 0.5 to 3.0 mils is treated to show a final extension MD of 400 to 700% and a TD of 500 to 700% or more. Moreover, these films are not understood as splitties. The term "splitity" is a qualitative term describing the film's intriguing reaction at a high strain rate, "split" refers to the rate of crack propagation, which is the end use characteristic of certain types of film and the underlying prospects are unknown. .

As the polymer leaves the annular die, the extrudate cools and solidifies by decreasing the temperature below the melting point. The optical properties of the extrudate change when crystallization occurs and freezing lines are formed. The location of the freezing line on the annular die is a measure of the cooling rate of the film, which has a very significant effect on the optical properties of the resulting film.

Ethylene polymers may also be extruded in the form of rods or other solid cross sections using the same die geometry for only the outer surface. Moreover, the ethylene polymer may be extruded into a pipe through a cyclic die.

II. Slotted Cast Film Extrusion

The film of the present invention can also be extruded by a slot cast film extrusion process. This film extrusion method is well known in the art and is characterized by extruding a sheet of molten polymer through a slot die and then quenching the extrudate using a casting roll or water bath. The die is described below. In the chill roll process, the film can be extruded horizontally and placed on top of the chill roll or placed downward on the chill roll. The extrudate cooling rate in the slot cast process is very high. Quenching on a chill roll or water bath is so fast that the extrudate is cooled below the melting point so that it is nucleated too rapidly and the supramolecular structure has little time to grow, and the conifer is kept in a very small size. The optical properties of the slotcast film are greatly improved over the properties of the film using lower cooling rates, tubular blown film extrusion processes. The compound temperature in the slot cast film extrusion process is generally much higher than the compound temperature representative of the tubular blown film process. Melting strength is not a limited process for this film extrusion method. Shear viscosity and expansion viscosity are both low. The film can be extruded at a higher discharge rate than is usually done in blown film processes. Higher temperatures reduce shear stress in the die and raise the minimum emissions for the melt fraction.

[film]

The film of the present invention has a thickness of 0.10 to 20 mils, preferably 0.10 to 10 mils, most preferably 0.10 to 4.0 mils. 0.10 to 4.0 mil of film has the following characteristics.

Rupture Resistant: Approx. 7.0 in.-pounds / mil or more

Final extension: over 400%

Heat shrinkage after heating to 105 to 110 ° and cooling to room temperature: 3% or less.

Tensile Impact Strength: 500 to 2000 feet-lbs / (inch) ³ or more

Tensile strength: 2000 to 7000 psi or more.

Various conventional additives such as slip agents, barrier agents and antioxidants can be incorporated into the films according to conventional methods.

[Ethylene polymer]

The polymer used in the process of the present invention is a homopolymer of ethylene or a copolymer of a plurality of moles (more than 90%) of ethylene and a few mole percent (up to 10%) of one or more C ₃ -C ₈ alphaolefins. . C ₃ -C ₈ alphaolefins should contain side chains on carbon atoms closer than the fourth carbon atom.

Preferred C ₃ -C ₈ alpha olefins are propylene butene-1, pentene-1, hexene-1, 4-methylpentene-1 and octene-1.

The ethylene polymer has a melt flow rate of 22 to 32, preferably 25 to 30, and the value of the melt flow rate is another measure of the molecular weight distribution of the polymer. The range of melt flow rates (MFR) of 22 to 32 thus corresponds to a value of Mw / Mn of 2.7 to 4.1.

The copolymer has a density of 0.958 to 0.972, preferably 0.961 to 0.968.

The copolymer has a density of 0.91 to 0.96, preferably 0.917 to 0.955, most preferably 0.917 to 0.935.

For copolymers the density of the copolymer at a given melting rate is preferentially controlled by the amount of C ₃ -C ₈ comonomer copolymerized with ethylene. In the absence of comonomers, ethylene is homopolymerized with the catalyst of the present invention to provide a homopolymer having a density of at least 0.96. Therefore, if a larger amount of comonomer is gradually added to the copolymer, the density of the copolymer is gradually decreased. The amount of various C ₃ -C ₈ comonomers required to achieve this same result will vary from monomer to monomer under the same reaction conditions.

Therefore, in order to obtain the same result, a larger molar amount of different comonomers is required in the order of C ₃ > C ₄ > C ₅ > C ₆ > C ₇ > C ₈ in terms of given density at a given melting rate in the copolymer. .

The ethylene polymer of the present invention has an unsaturated group content (C = C / 1000 carbon atoms) of 1 or less, usually 0.1 to 0.3, and an n-hexane extract content of 3 wt% or less, preferably 2 wt% or less.

The polymers of the present invention, when prepared in the fluidized bed process described below, are granular materials having a precipitated bulk density of 15 to 32 pounds per ³ feet and an average particle diameter of 0.005 to 0.06 inches, preferably 0.02 to 0.04 inches. .

Particle size is important for the purpose of easily fluidizing polymer particles in a fluidized bed reactor.

Preferred polymers for preparing films in the process of the present invention are copolymers, in particular having a density of 0.917 to 0.924, a molecular weight distribution (Mw / Mn) of 2.7 to 3.6, preferably of 2.8 to 3.1, and a standard melt rate of 0.5 To 5.0, preferably 1.0 to 4.0.

The film produced in the process of the invention has a thickness of 0 to 10 mils, preferably 0 to 5 mils.

Highly Active Catalyst

The compound used to form the high activity catalyst used in the fluidized bed polymerization process for making the polymer that can be used in the extrusion process of the present invention is at least one titanium compound, at least one magnesium compound And an electron donor compound, at least one activator, and at least one inert carrier material.

Titanium compound has the following structure.

Ti (OR) _a X _b

In the above formula

R is an aliphatic or aromatic hydrocarbon group or a COR 'group having from ₁ to ₁₄ carbon atoms, wherein R' is an aliphatic or aromatic hydrocarbon group from ₁ to ₁₄ carbon atoms.

X is CI, Br, I or mixtures thereof

a is 0, 1 or 2,

b is 1 to 4

a + b is 3 or 4.

These titanium compounds can be used individually or in mixtures, and include TiCl ₃ , TiCl ₄ , Ti (OOH ₃ ) Cl ₃ , Ti (OC ₆ H ₅ ) Cl ₃ , Ti (OCOCH ₃ ) Cl ₃ and Ti (OCOC ₆ H ₅ ) Cl ₃ and the like.

The magnesium compound has the following structure.

MgX ₂

In the above formula

X is Cl, Br, or I. These magnesium compounds may be used individually or in a mixed state, and include MgCl ₂ , MgBr ₃ and Mgl ₂ . Mousse MgCl ₂ is a particularly preferred magnesium compound.

In preparing the catalyst, 0.5 to 56, preferably 1 to 10 moles of magnesium compounds are used per mole of titanium compound.

Titanium compounds and magnesium compounds should have physical form and chemical properties that can be partially dissolved in the electron donor compound described below.

The electron donor compound is liquid at 25 ° C. and must be able to partially or completely dissolve the titanium compound and the magnesium compound. Electron donor compounds are known substances such as Lewis bases.

Electron donor compounds include aliphatic and aromatic carboxylic acids, aliphatic ethers, cyclic ethers, aliphatic ketones, and the like. Preferred among these electron donor compounds are alkyl esters of saturated aliphatic carboxylic acids having 1 to 4 carbon atoms, alkyl esters of aromatic carboxylic acids having 7 to 8 carbon atoms, and preferably C ₃ to C ₄ aliphatic ethers C ₃ to C ₄ cyclic ethers and Examples include C ₄ -cyclic mono- or di-ethers, C ₃ to C ₆ , in particular C ₃ to C ₄ aliphatic ketones, and the most preferred electron donor compounds are methyl formate, ethyl acetate, butyl acetate, ethyl Ethers, hexylethers, tetrahydrofuran, dioxane, acetone and methyl isobutyl ketone.

These electron donor compounds can be used individually or in mixture.

2 to 85, preferably 3 to 10 moles of electron donor compounds are used per mole of titanium.

The activator compound has the following structure.

A1 (R ") _c X _d 'H _e

In the above formula

X is Cl or OR "'

R "and R" 'are the same as or different from each other and represent a saturated hydrocarbon group having 1 to 14 carbon atoms.

d is 0 to 1.5

e is 1 or 2

c + d + e is 3.

These activators can be used individually or in combination, and include Al (C ₂ H ₅ ) ₃ , Al (C ₂ H ₅ ) ₂ Cl, Al (iC ₄ H ₉ ) ₃ , Al ₂ (C ₂ H ₅ ) ₃ Cl ₃ , Al (i C ₄ H ₉ ) ₂ H, Al (C ₆ H ₁₃ ) ₃ , Al (C ₂ H ₅ ) ₂ H and Al (C ₂ H ₅ ) ₂ (OC ₂ H ₅ ).

In order to activate the catalyst of the present invention, 10 to 400, preferably 15 to 60 moles of activator per mole of titanium compound is used.

The carrier material is a solid, granulated material that is inert to other components in the catalyst composition or the active ingredients in the reaction system. Carrier materials include inorganic materials such as silicon and aluminum oxides and molecular sieves, and organic materials such as olefin polymers such as polyethylene. The carrier material is used in the form of a dry powder having an average particle size of 10 to 250 mu, preferably 50 to I 50 mu. These materials are porous and preferably have a surface area of at least 3 m ² / g, preferably at least 50 m ² / g. The carrier material should be dry, i.e., dehydrated, and is usually dried prior to use by heating or pretreatment with a dehydrated inert gas. To further activate the carrier, the inorganic carrier is treated with 1 to 8% by weight of one or more aluminum alkyl compounds described above.

[Production of Catalyst]

The catalyst used to prepare the polymer used in the extrusion process of the present invention is prepared by first preparing a precursor composition from a titanium compound, a magnesium compound, and an electron donor compound, as described below. After immersing this precursor composition in the carrier material, the carrier material is treated with the activator in one or more steps as described below.

The precursor composition is formed by dissolving the titanium compound and the magnesium compound in the electron donor compound at a temperature between about 20 ° C. and the boiling point of the electron donor compound. The titanium compound may be added to the electron donor compound before, after or simultaneously with the addition of the magnesium compound. Dissolution of the titanium compound and the magnesium compound in the electron donor compound can be promoted by stirring or optionally refluxing.

After the titanium compound and magnesium compound are dissolved, the precursor composition is liberated by crystallization or by precipitation with C ₅ to C ₈ aliphatic or aromatic hydrocarbons such as hexane, isopentane or benzene.

The crystallized or precipitated precursor composition has an average particle size of 10 to 100 microns with fine free flow, and the sediment depth is 18 to 33 Lb / ft ³ which is liberated in powder form.

The precursor composition prepared as above has the following structure.

Mg _m T _i (OR) _n X _p [ED] _q

In the above formula

ED stands for electron donor,

m is 0.5 to 56, preferably 1.5 to 5,

n is 0.1 to 2,

p is 2 to 116, preferably 6 to 14,

q is 2 to 85, preferably 4 to 11,

R is a C ₁ to C ₁₄ aliphatic or aromatic hydrocarbon group or a COR 'group, and R' is a C ₁ to C ₁₄ aliphatic or aromatic hydrocarbon group

X is Cl, Br, I or a mixture thereof.

The precursor composition is immersed in the carrier material at 0.033 to 1, preferably 0.1 to 0.33 parts per weight part of the carrier material.

Immersion of the precursor composition in the activated support is performed by dissolving the precursor composition in the electron donating compound and then mixing the support with the dissolved precursor composition such that the precursor composition is immersed in the support. The solvent is removed by drying at 70 캜 or below.

The support may also be immersed by adding a precursor to a solution of chemical impurities to form the precursor composition in the electron donating compound without separating the precursor composition from the solution. The excess electron donating compound is removed by drying at 70 캜 or lower.

Alternatively, the precursor composition may be diluted in a carrier material. Dilution of the precursor composition may be performed simultaneously with or before activation of the precursor composition partially or completely. The method of diluting the precursor composition is carried out by mixing 0.033 to 1, preferably 0.1 to 0.33 parts by weight of the precursor composition with 1 part by weight of the carrier material.

[Activation of precursor material]

For use in making the polymers used in the extrusion process of the present invention, the precursor composition must be fully activated. That is, the Ti atom in the precursor composition must be activated by treatment with a sufficient amount of activator.

In order to make a useful catalyst, at least the final activation step must be carried out in the absence of solvent to avoid the need to remove the fully activated catalyst to remove the solvent. The activation process consists of diluting the immersed precursor composition (A) and the precursor composition with a carrier material (B).

A. Activation of the Submerged Precursor Composition

The activation process is carried out in at least two ways. Firstly, a precursor composition immersed in silica is reacted and partially reduced with a sufficient amount of activator to partially activate the molar ratio of activator / Ti> 0 to <10: 1, preferably 4 to 8: 1. Obtain a precursor composition. The partial reduction reaction is carried out in a hydrocarbon solvent slurry to remove the solvent by drying the resulting mixture at 20 to 80 ° C, preferably 50 to 70 ° C. In the partial activation process, the activator may be used while submerging in the carrier material used as a support for the precursor composition. The resulting material is a free fluid bed solid material that can be easily fed to the reactor.

However, the partially activated and immersed precursor composition is weakly active as a polymerization catalyst in the polymerization reaction.

To obtain a partially activated, immersed precursor composition that is active in the ethylene polymerization, an additional activator must be added to the polymerization reactor to fully activate the precursor composition in the reactor. The additional activator and the partially activated and immersed precursor composition are preferably fed to the reactor via a separate feed tube. The additional activator is sprayed into the reactor in the form of a solution dissolved in a hydrocarbon solvent or mineral oil such as isopentane, hexane. This solution generally contains from 2 to 30% by weight of activator. The additional activator is added to the reactor in an amount such that the Al / Ti molar ratio of the titanium compound supplied with the activator and the partially activated and immersed precursor composition is in the range of 10 to 400, preferably 15 to 60. do. The amount of additional activator added to the reactor reacts with the titanium compound in the reactor to fully activate the titanium compound.

B. Activation Reaction to Dilute Precursor with Carrier

Both methods result in: In the first method, the precursor composition is totally activated outside the reactor in the absence of solvent by mixing the precursor composition with an activator.

In this anhydrous mixing method, the activator is preferably used while absorbing the carrier material. However, this method has the disadvantage that the resulting anhydrous, fully activated catalyst contains at least 10% by weight of activator and is pyrolytic.

In the second preferred catalyst activation method, the precursor composition is partially activated with an activator in the hydrocarbon slurry, the hydrocarbon solvent is dried off, and the partially activated precursor composition is fed to the synthesis reactor to complete the activation reaction with additional activator. Let's do it.

In anhydrous mixing of the catalyst, the solid precursor composition is added to the solid particles of the porous carrier material in which the activator is absorbed and mixed. The activator is absorbed into the carrier in the form of a solution dissolved in a hydrocarbon solvent such that 90 to 50 wt% of the carrier material is loaded with 10 to 50 wt% of the activator. The amount of precursor composition, activator and carrier material to be used is an amount having a desired A1 / Ti molar ratio and the weight ratio of precursor composition to carrier material in the final composition is 0.50 or less, preferably 0.33 or less. The amount of this carrier material is necessary to dilute the activated catalyst so as to control the polymerization activity of the catalyst in the reactor. If the final composition contains at least 10% by weight of activator it is pyrolytic. During the anhydrous mixing process carried out at a temperature of 25 ° C. or lower, the anhydrous mixture is stirred well to avoid initial thermal formation during the subsequent exothermic reduction reaction. The resulting catalyst can thus be fully reduced and activated and fed to the polymerization reactor. This is a free flowing material.

Secondly, it consists of at least two stages which are activated in the preferred catalyst activation reaction. In the first step, the solid precursor composition diluted with the carrier material is reacted with a sufficient amount of activator and partially reduced to partially activate the mole ratio of activator Ti from 1 to 10: 1, preferably from 4 to 8: 1. Obtain a precursor composition. This partial reduction reaction is preferably carried out in a hydrocarbon solvent and then the resulting mixture is dried at 20 to 80 ° C., preferably 50 to 70 ° C. to remove the solvent. In this partial activation reaction, the activator is used by diluting the activator while absorbing the carrier material.

The resulting material is a free flowing solid material which can be easily fed into the polymerization reactor. However, the partially activated precursor composition is less active for use as a polymerization catalyst in the polymerization reaction described below. To obtain a partially activated precursor composition that is active in the ethylene polymerization, an additional activator must be added to the polymerization reactor to complete the activation of the precursor composition. The additional activator and the partially activated precursor composition are preferably fed to the reactor via a separate feed tube. The additional activator can be sprayed into the reactor in the form of a solution dissolved in a hydrocarbon solvent or inorganic oil such as isopentane or hexane. This solution usually contains 2 to 30% by weight of activator. The activator may also be added to the reactor in solid form absorbed by the carrier material. The carrier material contains 10 to 50% by weight of activator for this purpose.

The additional activator is added to the reactor in an amount such that the molar ratio of A1 / Ti of the titanium compound supplied with the activator and the partially activated precursor composition is in the range of 10 to 400, preferably 15 to 60. The amount of additional activator added to the reactor reacts with the titanium compound in the reactor to complete the activation.

In subsequent gas phase processes, such as the fluidized bed process described below, the abstract amount of the partially or fully activated precursor composition or the amount of the partially activated precursor composition immersed in the support is a fraction of the additional amount of the partially activated precursor composition. Along with the abstract amount for activation, it is continuously fed to the reactor during the subsequent polymerization to change the activated catalyst consumed during the reaction.

[Polymerization reaction]

Polymerization is a gaseous process, such as a fluidized bed process, which is a fully activated precursor in which monomeric oil is immersed in a support at a temperature and pressure sufficient to induce polymerization in the absence of catalyst poisons such as moisture, oxygen, CO, CO ₂ and acetylene. It is carried out by contacting a catalytically effective amount of the material composition (catalyst).

A C ₃ to C ₈ comonomer in the copolymer by scavenging> copolymerized with a C ₃ comonomers of ethylene to get the density of the copolymer> and to obtain a 0 to 10 mol%. The amount of comonomer needed to obtain the results depends on the special comonomer used.

The table below describes the amounts and moles of the various comonomers copolymerized with ethylene to obtain the desired density of the intermediate at a certain dissolution rate. State molarity is also described.

The fluidized acid reaction system used in the present invention is illustrated in FIG. For reference, reactor 10 consists of a reaction zone 11 and a speed reduction 12.

The reaction zone 11 consists of a successive fluidized bed of polymer phases formed, polymer particles formed and a small amount of catalyst particles polymerizable and modified gaseous components in the form of feed and recycle gas through the reaction zone. In order to maintain a viable fluidized bed, the flow rate of the gas passing through the bed should be at least the minimum flow required for fluidization, preferably 1.5 to 10 times Gmf and more preferably 3 to 6 times Gmf. Gmf is used as an indicator to reduce the minimum gas flow required to achieve fluidization.

[Reference: C. Y. Wen and Y. H. Yu, "Mechanics of Fluidization", Chemical Engineering Progress Symposium Series, Vol. 62, p. 100 111 (1966).

The bed should contain particles that prevent local "hot spots" from forming and dissipate and disperse special catalysts in the reaction zone. In operation, the reaction zone is filled with special polymer particles before gas flow begins.

Such particles may be essentially the same as or different from the polymer being formed. If different it is recovered as polymer particles formed as the first product. As a result, the fluidized bed of the desired polymer particles replaces the starting phase. The partially or fully activated precursor compound (catalyst) used in the fluidized bed is preferably fed to reservoir 13 under a blank cut of gas inert to the storage material, such as nitrogen and argon.

By increasing the low circulation rate of the gas passing through the bed, fluidization is usually about 50 times the feed gas feed rate. The fluidized bed has an appearance in which dense clumps of visible particles are vortex-free, such as when the gas is filtered through the bed. The pressure falling through the bed is equal to or slightly greater than the mass of the bed divided by the cross section. It is therefore dependent on the geometry of the reactants.

The feed gas is fed to the bed at the same rate as the particulate polymer product is recovered. Check by gas analyzer 14 located on top of the composition layer of the feed gas.

The composition of the feed gas is measured by measuring the composition of the gas recycled to the gas analyzer, and the composition of the feed gas is adjusted to maintain a constant gas composition in the reaction zone.

A portion of the recirculation gas and, if necessary, of the feed gas is returned through the gas recirculation piping 15 to the reactor at point 16 below to confirm fluidization completion.

There is a gas distribution line 17 above the return point to help fluidize the bed.

The unreacted gaseous fraction in the bed is combined with the recycle gas removed from the polymerisation zone, preferably passing it through the deceleration zone 12 in the bed where the added particles are given the opportunity to recover to the bed.

The recycle gas is compressed in compressor 18 and then passed through heat exchanger 19 where the heat of reaction is taken away before returning to bed. The temperature of the bed is controlled to a constant temperature under the blown state by continually removing the heat of reaction. There was no noticeable increase or decrease in temperature in the top of the bed. The increase or decrease in temperature occurs between the temperature of the inlet gas and the temperature of the gas remaining in the bed at the bottom of the bed, about 6-12 inches.

The recycle gas is returned to the fluidized bed through the reactor and distribution plate 17 at base 16. Compressor 18 is also located downstream of heat exchanger 19. Distribution plate 17 plays an important role in reactor operation. The fluidized bed contains catalyst particles as well as particulate polymers of increasing size and particulate polymers already formed. Since the polymer particles are warm and active, they must be restrained because if there is an inactive mass, the active catalyst contained therein will continue to react and cause confusion. Therefore, it is important to diffuse recycle gas into the bed at a rate sufficient to maintain fluidization at the bed base. Distribution plates 17 are used for this purpose, which may be screens, flaws, perforated plates, foam cap plates, and the like. The components of the plates are all stationary or mobile types disclosed in US Pat. No. 3,298,792.

No matter how designed, the plates must penetrate the recycle gas through the particles at the bed base to maintain flow and also support the inert bed of resin particles when the reactor is not operating. The mobile component in the plate is used to remove polymer particles in or on the plate.

Hydrogen is used as side chain transfer agent in the polymerization reaction of the present invention. The hydrogen / ethylene ratio used varies from about 0 to 2.0 moles of hydrogen per mole of monomer in the gas stream.

Gases inert to the catalyst and reactants may also be present in this gas stream. It is preferred to add the active compound downstream from the heat exchanger 19 to the reaction system. The active compound is thus fed via the pipe 21 from the dispenser 20 to the gas recycle system.

The structural Zn (R _a ) (R _b ) compounds are hydrogen, molecular weight modifiers or side chains in which R _a and R _b are the same or different C ₁ -C ₄ aliphatic or aromatic hydrocarbon residues, to increase the dissolution rate of the resulting polymer. It may be used in combination with a catalyst described as a transfer agent. About 0 to 100, preferably about 20 to 30 moles of Z _n compound (as Z _n ) per mole of titanium compound (as Ti) in the reactor is used for the gas flow in the reactor. It is preferred to introduce about 10 to 50% by weight of the zinc compound into a reactor diluted with a hydrocarbon solvent (2 to 30% by weight) or by adsorbing to a solid diluent such as the type described above, ie silica.

These compositions tend to spontaneously ignite. The zinc compound is added alone or with the zinc compound, a portion of the active compound is added to the reactor from a feeder located near the dispenser 20.

It is important to operate the fluidized bed reactor at a temperature lower than the sintering temperature of the polymer particles to avoid sintering. Among the polymerization methods described herein, the operating temperature for producing the ethylene polymer is preferably about 30 to 115 ° C, and most preferably about 75 to 95 ° C. Temperatures of about 75 to 95 ° are applied to make polymers having a density of about 0.91 to 0.92, and temperatures of about 80 to 100 ° C. are used to produce polymers having a density of about 0.92 to 0.94 and a density of 00.94 to 0.97 A temperature of about 90-115 ° C. is applied to prepare the polymer.

Fluid bed reactors operate at pressures up to about 1000 psi, preferably at pressures from about 150 to 350 psi, and when operated at high pressures in this range, an increase in pressure increases the heat volume per unit volume of gas. Heat transfer is good.

Partially or fully activated precursor composition is injected at point 22 on distribution plate 17 equal to its consumption rate. Preferably, the catalyst is injected at the point in the bed where the polymer particles are mixing well. Injection of the catalyst at points on the distribution plate is an important feature of the present invention. The catalysts described here are highly active, and when fully activated catalysts are injected under the distribution plate, polymerization may occur there and eventually the distribution plate may be blocked. Instead, injection of a viable bed bed assists in distributing the catalyst to the bedlock and eliminates the formation of high concentration points of the localized catalyst, which also leads to the formation of "heart spats". Purchasing catalyst in the reactor over the bed causes excess catalyst carryover into the recycle line where polymerization begins and line flushing and heat exchange occurs.

A gas that is inert to the catalyst, such as nitrogen or argon, is used to transport the partially or fully reduced precursor composition and additional activating compounds or necessary non-gaseous side chain transfer agents into the bed.

The rate of bed formation is controlled by the rate of catalyst injection. Increasing the catalyst injection rate increases the production rate and decreases the production rate due to the reduction of the catalyst injection rate.

Since the change in catalyst injection rate changes the rate of generation of reaction heat, the temperature of the recycle gas entering the reactor is adjusted to adjust the change in heat generation rate. This keeps the temperature in the bed constant. Full mechanization of the fluidized bed and recycle gas cooling system is necessary to detect temperature changes in the bed to allow the functional group to properly control the use of the recycle gas.

Under a given operating condition, the fluidized bed pulls out a portion of the bed as a product at the same rate as the rate of formation of the granulated polymer product to maintain a constant height. Since the rate of heat production is directly related to product formation, the temperature rise of the gas across the reactor (difference between the inlet and outlet gas temperatures) determines the rate of particulate polymer formation at a constant gas velocity.

The particulate polymer product is preferably continuously withdrawn at or near the distribution plate 17 and at a point 23 and a portion of the gas flow and to reduce further polymerization and sintering when the particles reach the collection zone. It is ejected as a particle into a suspension of. Suspended gases are also used to push the products of one reactor into another.

The granulated polymer product is conveniently and preferably withdrawn by the continuous operation of the clocked valves 24 and 25 limiting the separator 26. When the valve 25 is closed, the valve 24 is opened to flush gas fogging and fire to the 26 zone between it and the valve 24 and close the valve 24. Open the valve 25 to move the product to the external recovery. The valve 25 is plugged in to wait for the next product recovery operation. Emission gases containing unreacted monoliths are withdrawn from zone 26 via line 27 and recompressed in compressor 28 and directly or via purifier 29 of recycle compressor I8 in line 30. Turn to gas recirculation line 15 at the point of backflow.

Finally, the fluidized bed functional group is equipped with a suitable release system to enable the release of the bed during start up and shutdown. The reactor does not require agitation means and / or means for scraping walls. The recirculating gas line 15 and its parts (pressor 18, heat exchanger 19) should have a smooth surface and avoid unnecessary interference to prevent the flow of recycle gas.

The catalyst system and polymerization process described above produce fluid bed polymers with an average particle size of between about 0.005 and about 0.06 inches, preferably between about 0.02 and about 0.04 inches.

With or without an inert gas diluent, the gas monolithic flow is fed to the reactor at about 2 to 10 pounds / hour / (foot volume of bed) 3.

The properties of the polymers produced in the examples are determined by the following test methods.

Density: For materials with a density less than 0.940, the ASTM-1505 method is used and the plaque is brought to 100 ° C. for l hour to reach equilibrium crystallinity. For materials with a density above 0.940, a modified method is used, in which the test plaques are brought to I20 ° C. for 1 hour and immediately cooled to room temperature to reach equilibrium crystallinity.

All density values are reported in g / cm ³ .

All density measurements are made in the density gradient column.

Melting rate (MI): Recording at g / 10 min measured at ASTMI-1238-condition E-190 ° C

Flow Rate (HLMI): measured at 10 times the weight used in ASTMD-1238-condition F-melting point index test

Productivity: Collect a sample of resin product and determine the% of the ash content. Since the ash is composed of a catalyst, the productivity is therefore the pounds of polymer produced per pound of total catalyst consumed. The amount of ash Ti, Mg and halide is determined by elemental analysis.

n-hexane extraction (test for polyethylene film for food contact applications): A 200 inch ² sample of 1.5 milligauge film is cut into 1 ^μ × 6 ^μ projection slab size and weighed to the nearest 0.1 mg. The projection slide is placed in a container and extracted with 300 ml of n-hexane at 50 ± 1 ° C. for 2 hours. Pour the extract still in a weighed dish. After the extract is dried in a vacuum dryer, the culture dish is weighed to an approximate value of 0.1 mg. The extract normalized to the original sample weight is reported as the weight fraction of the n-hexane extract.

Average Particle Size: This is calculated from sieve analysis using a 500 g sample according to ASTM-D-I921 Method A. The calculation is based on the unclassified weight remaining in the delusion.

Unsaturation: Infrared Spectrophotometer (Perkin Elmer Model 21) The test material uses a 25 mm thick record made from resin. Absorbance is measured at 10.35μ for transvinylidene unsaturation, 11.0μ for terminal a half unsaturation, and 11.25μ for accessory vinylidene unsaturation. The absorbance per mm of thickness of the record is directly proportional to the unsaturated concentration and the rate of absorption. Absorption can be found in the literature of R. J. de kock, et al, J. PoIymer Science, Part B. 2,339 (1964).

Bulk density: Resin is passed through a 3/8 ^μ diameter funnel and poured into a cylinder with I00ml scale up to 100m1 without shaking the cylinder, and the weight difference is measured. The measurement is reported in Lbs / ft ³ .

Molecular Weight Distribution (M _w / M _n ) Gel Permeation Chromatography Density Less Than 0.94 For Resin: Styrogel Filling: (The pore size order is 10 ⁷ , 10 ⁵ , 10 ⁴ , 10 ³ , 90 A °) Solvent at 117 Perchlorethylene. Density 0.94 or more for resin: Stroke filling: (The pore size order is 10 ⁷ , 10 ⁶ , 10 ⁵ , 10 ⁴ , 60 A °) The solvent is ortho dichlorobenzene at 135 ° C. Detection against resin: at 3.45 μm infrared

The following examples illustrate the preparation of the invention and are not intended to limit its scope.

I _a. Preparation of Saturated Electrode Material

Into a 12 L flask with a stirrer was added 41.8 g (0.439 mol) of anhydrous magnesium chloride and 2.5 L of tetrahydronifuran. 27.7 g (0.184 mol) of titanium tetrachloride are added dropwise to the mixture over 30 minutes. At this time, to completely dissolve the mixed material, the mixed solution is heated to 60 ℃ for 30 minutes.

500 g of porous silica sand was added and the mixed solution was stirred for 15 minutes. The mixture is dried for 3 to 5 hours in a nitrogen stream at 60 ° C. to obtain a dried powder of silica particle size. The chemical formula of the adsorption precursor composite is as follows.

TiMg _3.0 Cl ₁₀ (THF) _6.7

I _b . Preparation of Saturated Precursors from Progenitor Pro-Flame Composites

In a 12 L flask equipped with a stirrer, 146 g of precursor complex is dissolved in 2.5 L of dry tetrahydrofuran. The solution is then heated to 60 ° C. to promote dissolution. 500 g of porous silica sand is added and the mixture is stirred for 15 minutes. This mixed solution is dried for 3 to 5 hours in a nitrogen gas stream of 60 ° C. or less to obtain a dry powder of silica sand particle size.

The precursor composites used in the preparation are made in the same way as the I _a method, except that they are recovered from solution by crystallization or precipitation using tetrahydrofuran.

Precursor composites lose some of the magnesium and titanium compounds during their separation, so that the total isotope of the isotopes can be performed at this point. The empirical formula for the precursor composition described here is derived on the assumption that magnesium and titanium are present in the form of the compound at the time of addition as an electron donating compound. The degree of electron donation is determined by chromatographic method.

II. Activation method

To maintain the slurry, add as many saturated precursor composites and activators as necessary to a mixing tank containing sufficient anhydrous aliphatic hydrocarbons such as isopentane.

The activator and precursor compounds are used to result in partially activated precursor composites with an aluminum / titanium ratio of greater than 0 and less than 10: 1, better 4 to 8: 1.

The contents of the slurry are thoroughly mixed for 15 to 30 minutes at room temperature and atmospheric pressure. The resulting slurry is then dried over a dry inert gas such as nitrogen or argon at atmospheric pressure 65 ± 10 ° C. to remove the hydrocarbon diluent. This process takes about 3 to 5 hours. The resulting catalyst is present in saturated form with partially activated precursor composites in the silica sand pores. The material consists of flowable particles of silica sand shape and size. If the alkylaluminum content is not more than 10% by weight, the catalyst is non-flammable and future catalysts are stored and stored in dry inert gases such as nitrogen and argon. Moreover, the method of using this catalyst is currently put into a polymerization reactor, fully activated in a reactor, and is used.

When a separate active agent is injected into the polymerization reactor for the full activation of the precursor synthesis agent, a dilution solution using a hydrocarbon such as isopentane as a solvent is injected into the reactor. This dilution solution contains 5 to 30% of the talcum agent in volume ratio.

The activator is added to the polymerization reactor to maintain the aluminum / titanium ratio of the reactor at a level of 10 to 400: 1, and even better to 15 to 60: 1.

Example 1

Preparation of Copolymer

In the presence of a catalyst activated according to the above-mentioned preparation and activation method A, ethylene causes a series of polymerization reactions with propylene or 1-burene (test runs 1 to 2 propylene, 3 to 14 1-burene), having a density of 0.940 or less. Polymer-. The partially activated precursor composite in each of these experiments has a (alnium / titanium) molar ratio of 4.4 to 5.8. The complete activation of the precursor composite in the polymerization reactor is characterized by the fact that triethyl aluminum (test runs 1 to 3, 4 to 14 Test run 4 to 5 in the case of 5 weight percent in pentane solvent is adjusted to 50/50 weight percent in case of absorbing silica sand.

After the equilibration, each of the polymerization reactions was performed in a fluid bed reaction system with a pressure of 300 psia and a gas velocity of 3 to 6 Lbs / hr / ft ³ for the space time yield of the bed space. It is continued for 1 hour or more in the state of about 5 to 6 times. The reaction system is shown earlier. The bottom of the device is 13.5 inches inside and 10 feet high, and the top is 23.5 inches inside and 16 feet high.

Some of the trial runs added diethylzinc (isopentane solvent, 2.6% solution) to keep the (zinc / titanium) molar ratio constant. Where diethyl zinc was used, triethyl aluminum was also added by preparing a 2.6 weight% solution with isopentane as a solvent.

Test Runs 1 to 14 in Table A below list the various operating conditions applied to these tests. For example, the weight percentage of precursor composite in a mixture of silica sand and precursor composite; The (aluminum / titanium) ratio in the partially activated precursor composite; the (aluminum / titanium) ratio maintained in the reactor; Polymerization temperature; Ethylene volume percentage in the reactor; (hydrogen / ethylene) molar ratio; Molar ratio of co-unit (Cx) / C _{2 in the} reactor; catalyst productivity (zinc / titanium) molar ratio and the like. Table B below lists the properties of the granular resins produced in Test Runs 1-14. Eg Density: Melt Index (MI) Melt Fow Ratio, Ash (Weight Percent), Titanium Content (ppm); Bulk density and average particle size.

Table A: Reaction conditions (operation number 1-14)

Table B: Properties of Preparation Polymer (Operation No. 1-14)

Example 2

Blown film extrusion method using a 24/1 extruder of a 2.5 inch diameter, 18: l L / b extrusion screw with an ethylene-butene copolymer having a density of 0.924, a melt index of 2.0, prepared according to Example 1 Blown film extrusion) yielded a 1.5 x 10 ^-3 inch thick film. The extrusion screw was 12.5 inches in the feed section, 7.5 inches in the transition section, 20 inches in the metering section, and 5 inches in the mixing section. The mixing portion was a groove-shaped mixing portion having the following characteristics. 2.5 inches in diameter, 3.0 inches in channel, 0.541 inches in channel radius, 0.25 inches in mixing part width, 0.20 inches in washing part width and 4.5 inches in mixing part length. The voids of the spring barrel are 1 inch in diameter and 9 inches in length with a fixed mixer. There was a plug that was 2.496 inches long and 11 inches long. In addition, a 20/60/20 mesh screen group and a 3 inch diameter die were used. The spacing of the molds was 40 × 10 ⁻³ inches and the sides of the molds were parallel to the flow axis of the polymer melt. The melting temperature of the copolymer was about 400 ° F., and the height of the Nip roll was about l 5 feet. Cooling consisted of a Ventri type air ring and all films were produced at a blow-up ratio of 2: 1. The film yield was 7.27 pounds / hour / inch (fabric length) and the Sharkskin melt fraction was measured using a microscope at 40 magnification. At this time, the light was split from the side of the compact, and under the microscope the transition from the low-shear gloss of the extrudate to the critical 1-shear, the high from the matte surface (the starting point of the Sharkskin Fracture). Transitions to high-shear deep ridges and sharkskin melt fractions have been seen. High sharkskin melt fractions were observed during film production.

Example 3

In the manufacturing method of Example 2, the melting temperature was about 380 ° F., and the film production rate was changed under the same conditions except that the film production rate was changed to 4.l 4 pounds / hour / inch (manufacture length). High sharkskin melt fractions were observed during film production.

Example 4

The manufacturing process of Example 2 was made under the same conditions except changing the film production rate to 80 × 10 ⁻³ inches and the melting temperature to about 390 ° F. to a film yield of 7.38 pounds / hour / inch (manufacturing length). Low sharkskin melt fractions were observed during film production.

Example 5

Manufacturing frame showing the manufacturing frame of the manufacturing method of Example 2 in Table 3a (where dimensions are α angle = 4.57 ° and k = 80 × 10 ⁻³ inches m = 50 × 10 ⁻³ inches n = 40 × 10 ⁻³ inches ), And the melting temperature was about 298 ° F., and the film production rate was changed to 7.22 lb / hour / inch (manufacture length) except that the same conditions were used. Melt fraction could not be observed during film production.

Example 6

The manufacturing process of Example 2 was changed to that used in Example 5 and prepared under the same conditions except that it was changed to a melting temperature of about 410 ° F. and a film yield of 8.38 pounds / hour / inch (manufacturing length). Low sharkskin melt fractions were observed during film production.

The deficiencies from Examples 2 to 6 are summarized in Table I.

TABLE I

The data in Table I show that the spacing of manufacturing frames is the preferred factor for adjusting the Sharkskin melt fraction. Films with high melt fractions were produced in Examples 2 and 3 where the sides of the mold were parallel to the melt flow axis and the mold spacing was 40 × 10 ⁻³ inches. Also in Example 3, in which the film production rate was lowered significantly, the malt fraction was high. The new design was made when comparing the production frame (the design frame devised in Example 5) with one side in the manufacturing frame non-equilibrium with the melt flow axis, and the manufacturing frame (Example 4) with flat sides on each side and 80 × 10 ^-3 inch spacing. In the case of a manufacturing frame, melt fraction did not generate | occur | produce. The newly designed manufacturing framework showed low melt fractions even at higher production rates and at higher temperatures (Example 6).

Example 7

An ethylene butene copolymer of density 0.924, melt index 2.0, prepared according to Example 1, was used to produce a 1.5 × 10 −3 inch thick film using a screw extruder with a diameter of 2.5 inches as described in Example 2.

Change the mold to the mold shown in Figure 3a (α = -5.7, thread spacing k = 0.1 inches, m = 0.5 inches, n = 0.06 inches), and melt the copolymer at approximately 400 ° F. The height was about 15 feet. Cooling was a Venturi type air ring with a blowing ratio of 2: 1 and a film yield of 7.0 pounds / hour / inch (fabric length). As in Example 2, the sharkskin melt fraction appeared, but the melt fraction could not be observed during film production.

Example 8

In the manufacturing method of Example 7, a part of the dimensions of the production frame was changed (α = 20 ° m = 0.110 inch), and the other conditions were manufactured under the same conditions. Melt fraction could not be observed during film production.

Example 9

In the manufacturing method of Example 7, a part of the dimensions of the production frame was changed (α = 40 ° m = 0.050 inch), except that the same conditions were produced under the same conditions. Melt fraction could not be observed during film production.

Example 10

In the manufacturing method of Example 7, the production frame was changed to α = 0 ° m = 0 inches, that is, each side of the production frame was parallel, except for the same conditions. High melt fractions were observed during film production.

The experiments from Examples 7 to 10 emphasize that the melt fracture does not appear even when the non-equilibrium angle is 40 ° (Example 9) when using the newly designed manufacturing frame (Examples 7 to 9). have. When the sides of the production frame are parallel, the melt fracture is generated even if the production frame spacing is sufficient as the production frame spacing before the inclined surface of the newly designed production frame.

Example 11

A round bar was made using a capillary rheometer with an ethylene butene copolymer of density 0.919, melt index 2.0 prepared according to Example 1.

Rod dies are 0.123 centimeters in inner diameter and have a parallel surface of 2.40 cm in length. The melting temperature of the copolymer was 180 ° C. and the polymer was extruded at a volumetric flow rate of 0.011 cm ³ / sec.

The apparent shear rate γ _a (Apparent shear rate) is measured according to the following equation.

Apparent shear rate

Q = volumetric flow rate, cubic centimeters / second

r = inner diameter of manufacturing frame, cm

The apparent shear rate at a melt peurek Miniature starting point was (r = radius of the channel calculation) (prepared from r = radius of the mold exit of the calculation) respectively, and channel shear rate also 60sec ^-1 60sec ^-l.

Example 12

In the preparation method of Example 1L, the melt opening diameter was 0.337 cm in the sewing vessel dimensions, and was changed to 0.126 cm in the production frame spacing and 2.54 cm in length, except that they were manufactured under the same conditions. The die lip had a mold cutting section and an inclination angle of 10 ° as shown in Table 3c.

The melting temperature of the copolymer was 180 ° C., and the polymer was extracted at a volume flow rate of 0.024 ⁴ cm ³ / sec. The apparent layer rolling ratio was measured in the same manner as in Example 11. The apparent shear rate at the melt fracture origin was 125 sec ^-1 (r = frame radius at the exit) and the channel shear rate was also 7 sec ^-1 (r = channel radius in the equation).

The experimental data of Example 11 and Example 12 were nearly doubled before reaching the melt-fraction starting point with the same diameter of the exit using the newly designed manufacturing frame (Example 12) when compared to the manufacturing plane of the flat surface. It is shown that polymer flow rates are possible.

The ethylene compounds used in the present invention can be regarded as linear polymers, given that the bases generated in the polymer are inevitably a function of the concentration and form of the comonomers reacting with ethylene when making the polymer. Of course, such comonomers are not used to make homopolymers.

The shear rate applied to the present invention is any surface reaches up to about 200sec ^-l can be achieved in about 100sec ^-1. This shear rate is measured at the outlet of the mold.

The polymer typically passes through the mold at a rate of 5 to 15 pounds / hour / inch (mill length), ideally 8 to 12 pounds / hour / inch (mill length). An ethylene-butene copolymer having a melt index of 2, a density of 0.92 and a Mw / Mn of 2.2 to 4.1, prepared at the above-described method, and heated to about 410 ° F. at a melting temperature was used as a raw material, and the manufacturing frame spacing was 0.85 inch, shown in FIG. One wave-wave dimension Using a die lip of 0.25 inch, die lip ftQ.50 inch, die land g 0.5 inch, land entry h, 0.50 inch, flow rate approximately 10 pounds / The present invention has been devised to make it easy to produce homopolymer workpieces at about 83 sec ⁻¹ lamination rate with good processing capacity to minimize melt fractions at time / inch (fabric length). Dyland g has a gap width of 0.040 inch, which serves to provide back pressure to improve the uniformity of the film thickness. The inclination of the die lip f is about 5 degrees.

Example 13

The present invention relating to extrusion production can also be used for pipe production. The pipe is made by the manufacturing method applied to the copolymer of Example 2. Extrusion of the homopolymer with a melt temperature of 335 ° F. and a production rate of 8.0 pounds per hour / inch (fabric length) yielded a melt-fracture-free pipe with an internal diameter of 0.5 inches and a thickness of 20 × 10 ^-3 inches. As shown in Fig. 2, the production frame is 1.78 inches in outer diameter, g = 0.5 inches in die land (0.040 inches in the manufacturing frame spacing in g), die lip 0.3 inches (angle 13 degrees at f), and die lip e 0.2 inches. An annular production frame (0.110 inches of spacing at e) was used.

The polymers used in all examples have a melt flow rate value of about 25.4.

Polymers that could be used in the present invention include catalyst products of the above-described composition and products made by ball mill grinding or cloud drying. The ball mill grinding catalyst method was filed in US Patent No. 085,313 (October 26, 1979) and the spray drying catalyst method was filed in US Patent No. 095,010 (November 26, 1976). Polymers made for use in the present invention using such catalysts include all copolymers, including TerpoIymer, filed in US Patent Application No. 049,555 (June 18, 1979). The above three patent publications are referred to by reference.

Ethylene polymers made from ball mill catalysts have a molecular weight distribution Mw / Mn of about 3 to 6, which corresponds to a melt flow rate (MFR) of about 26 to 40.

Claims (1)

The linear ethylene polymer is drawn through the die with a gap of at least 50 mils and at least a portion of the die lip and / or die land surface in contact with the molten polymer is divergent or convergent with respect to the flow axis of the molten polymer through the die. Characterized by extruding to reduce the melt fraction that is expressed during extrusion of the polymer having a narrow molecular weight distribution and linearity under flow rate and melting temperature conditions to produce a high level of melt fraction.

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