JPH0339812B2 - - Google Patents

Description

[Detailed description of the invention]

FIELD OF THE INVENTION This invention relates to articles molded from ethylene hydrocarbon copolymers, and in particular to wash basins injection molded from low density ethylene hydrocarbon copolymers having specific physical properties. Currently, it exhibits stress cracking resistance upon contact with detergents, vegetable oils and fats and/or at low temperatures (i.e.
e.g. lids, which have excellent impact strength at )
There is a need for molded plastic products such as closures, food and garbage containers, bottles, wash tubs and toys. Attempts have been made to mold these products from high pressure ethylene homopolymers or from mixtures of high density polyethylene and copolymers of ethylene and polar comonomers such as vinyl acetate or ethyl acrylate. However, products molded from high pressure polyethylene have insufficient stress cracking resistance and low temperature impact strength. Blends of polar copolymers and high-density polyethylene are better in these properties than high-pressure polyethylene, but they are extremely expensive to produce, have low translucency, have a lot of odor, and have poor It has electrical properties, high hexane extractable levels, and tends to exhibit color separation when pigmented. It has now been unexpectedly discovered in the present invention that articles molded from ethylene hydrocarbon copolymers have excellent stress cracking resistance and low temperature properties. In addition, products injection molded from ethylene hydrocarbon copolymers have high surface gloss and no matte swirl. Additionally, articles molded from the copolymers have excellent flex life, especially when bent across the direction of orientation. It is an object of the present invention to provide molded products of ethylene hydrocarbon copolymers with excellent stress cracking resistance and low temperature properties. Another object of the present invention is to provide an article injection molded from an ethylene hydrocarbon copolymer that has high gloss and is essentially free of matte swirls. Yet another object of the present invention is to provide articles molded from ethylene hydrocarbon copolymers that have low warpage. Yet another object of the present invention is to provide articles molded from ethylene hydrocarbon copolymers that have excellent flex life. Thus, according to the present invention, articles molded from ethylene hydrocarbon copolymers have excellent stress cracking resistance, low temperature properties and flex properties, have high gloss, low warpage and a matte swirl. It was found that there is essentially no Ethylene Copolymer The copolymer that can be used in the method of the invention comprises a high mole percent (90%) of ethylene and a low mole percent
(10%) of at least one monomer selected from the group consisting of propylene and butene-1. The copolymer is 22-32 preferably 25-30
It has a melt flow ratio of This melt flow ratio value is another means of indicating the molecular weight distribution of the polymer. Thus, a melt flow ratio (MFR) in the range of 22-32 corresponds to a Mw/Mn value in the range of about 2.7-4.1, and an MFR in the range of 25-30 corresponds to Mw/Mn in the range of about 2.8-3.6. The melt index of a copolymer reflects its molecular weight. Relatively high molecular weight polymers have relatively low melt indexes. Ultra high molecular weight ethylene polymers have a high load melt index (HLMI) of about 0.0, and very high molecular weight ethylene polymers have a high load melt index (HLMI) of about 0.0 to about 1.0. It is difficult, if not impossible, to mold such high molecular weight polymers with conventional injection molding equipment. On the other hand, polymers produced by the method of the present invention can be easily molded in such equipment. It ranges from 0.0 to about 100 preferably about
Standard load melt index from 0.5 to 80 and approx.
It has a high load melt index of 11 to about 2000. The melt index of the polymers produced by the process of this invention is a combined function of the polymerization temperature of the reaction, the density of the copolymer, and the hydrogen/monomer ratio of the reaction system. Thus, the melt index increases the polymerization temperature, decreases the density of the polymer and/or
It can be increased by increasing the monomer ratio. In addition to hydrogen, other chain transfer agents such as dialkyl zinc compounds can also be used to further increase the melt index of the copolymer. The copolymer of the present invention has an unsaturated group content of 1 C per 1000 carbon atoms, usually 0.1 to 0.3 C.
=C. The copolymers of the present invention have an n-hexane extractables (at 50 DEG C.) of about 3% by weight, preferably less than 2% by weight. The copolymer of the present invention has a residual catalyst amount (ppm) converted to titanium metal of >0 to 20 ppm at a productivity of 50,000, and >0 at a productivity of 100,000.
~10ppm and productivity of 300000>
Shows about 0 to 3 ppm. (For Cl, Br or I residues, the copolymers of the invention
It has a Cl, Br or I content depending on the Br or I content. From the Ti/Cl, Br or I ratio of the initial precursor,
From productivity information based only on titanium residue, Cl,
Br or I residual can be calculated. In most cases, the copolymers of the present invention prepared using only the Cl-containing component of the catalyst system (Cl/Ti = 7) have Cl residuals of >0 to 140 ppm at a productivity of 50,000;
For a productivity of 100,000 Cl contents of >0 to 70 ppm and for a productivity of 300,000 Cl contents of >0 to 20 ppm can be calculated. ) In the method of the invention,
Copolymers are easily produced with productivity up to about 1,000,000. The copolymers of the present invention are particulate materials having an average particle size on the order of about 0.005 to 0.07 inches, preferably about 0.02 to 0.041 inches in diameter. Particle size is important to facilitate fluidization of the polymer particles in a fluidized bed reactor, as discussed below. The copolymers of the present invention have a bulk density of about 15-31 lb/ ^ft3 . For forming articles such as lids, closures, food and garbage containers, wash basins, hinges and toys that must have excellent stress cracking resistance and/or low temperature strength, gloss or long flex life. Preferred copolymers of the present invention have a molecular weight of 0.918 to
Density of 0.935, molecular weight distribution of 2.7-4.1, 1-100,
Preferably, it has a standard melt index of about 7 to 80 and a secant modulus of about 30,000 to 80,000 psi. Preparation of Copolymer The copolymer of the present invention was prepared by FJ Karol et al.
The method described in U.S. Pat. It can be produced by a method of producing an ethylene hydrocarbon copolymer. These copolymers can be produced under low pressure gases as described below if the monomer charges are polymerized under a particular combination of operating conditions as described below and in the presence of a particular highly active catalyst as also described below. It can be easily produced by a phase fluidized bed reaction method. Highly active catalyst The compounds used to form the highly active catalyst used in the present invention include at least one titanium compound, at least one magnesium compound,
It consists of at least one electron donor compound, at least one activator compound, and at least one inert carrier material. Titanium compounds have the structure Ti(OR) _a X _b . In the formula, R is a _C1 - _C14 aliphatic or aromatic hydrocarbon group or COR' (where R' is a _C1 - _C14 aliphatic or aromatic hydrocarbon group), and X is Cl, selected from the group consisting of Br, I or mixtures thereof, a is 0 or 1, b is 2-4, and a+b=3 or 4. Titanium compounds can be used separately or in their mixed forms, including TiCl ₃ , TiCl ₄ , Ti
( _OCH3 ) _Cl3 ,Ti _{( OC6H5} ) _Cl3 ,Ti( _OCOCH3 )
Included are _Cl3 and Ti( _OCOCH5 ) _Cl3 . Magnesium compounds have the structure MgX ₂ , where X is selected from the group consisting of Cl, Br, I, or mixtures thereof. Such magnesium compounds can be used individually or in mixtures thereof and include MgCl ₂ , MgBr ₂ and MgI ₂ . Anhydrous _MgCl2 is a particularly preferred magnesium compound. When producing the catalyst used in the present invention, the amount of the magnesium compound used is about 0.5 to 56 mol, preferably about 1 to 10 mol, per 1 mol of the titanium compound. The titanium and magnesium compounds should be used in a form in which they are readily soluble in the electron donor compound. The electron donor compound will be explained below. The electron donor compound is an organic compound that is liquid at 25° C. in which the titanium and magnesium compounds are partially or completely soluble. Electron donor compounds are known per se and are otherwise known as Lewis bases. Electron donor compounds include alkyl esters of aliphatic and aromatic carboxylic acids, aliphatic ethers,
Included are cyclic ethers and aliphatic ketones.
Preferred examples of such electron donor compounds are:
Alkyl esters of _C1 - _C4 saturated aliphatic carboxylic acids, alkyl esters of _C7 - _C8 aromatic carboxylic acids, _C2 - _C8 preferably _C3 - _C4 aliphatic ethers,
_C3 - _C4 cyclic ethers, preferably _C4 cyclic mono- or diethers, _C3 - _C6 preferably _C3 - _C4 aliphatic ketones. The most preferred electron donor compounds include methyl formate, ethyl acetate, butyl acetate, ethyl ether, hexyl ether, tetrahydrofuran, dioxane, acetone and methyl isobutyl ketone. Electron donor compounds can be used individually or in their mixed form. The amount of electron donor compound used is approximately 2 per mole of Ti.
~85 moles, preferably about 3-10 moles. The activator compound has the structure Al(R″) _c X′ _d H _e (where X′ is Cl or OR and R″ and R
are the same or different _C1 - _C14 saturated hydrocarbon groups, d is 0-1.5, e is 1 or 0, and c+d+e=3). Such activator compounds can be used individually or in mixtures thereof, including Al(C ₂ H ₅ ) ₃ , Al
( _C2H5 ) _{2Cl ,} Al ₍ iso- _{C4H9 ) 3} , _Al2 ( _C2H5 ) _{3Cl3 ,}
Al(iso− _C4H9 ) _2H , Al _{( C6H13} ) ₃ , _{Al(C9H17 ) 3 ,}
Included are Al( _{C2H5 ) 2H} and Al _{( C2H5} ) ₂ ( _{OC2H5 )} . When activating the catalyst used in the present invention, the amount of activator compound used per 1 mole of titanium compound is about 10 to
400 moles, preferably about 10-100 moles. The support material is a solid particulate material that is inert with respect to the other components of the catalyst composition and other active components of the reaction system. These 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 with an average particle size of about 10-250μ, preferably about 50-150μ. In addition, these materials are porous, with a density of 3 m ² /g,
Preferably it has a surface area of 50 m ² /g. The carrier material should be dry, ie should not contain occluded water. Drying of the carrier material is carried out by heating it at a temperature of 600°C. Alternatively, the carrier material, dried at a temperature of 200°C, may be
It may be treated with 8% by weight of one or more of the above-mentioned aluminum alkyl compounds. Modification of the support with this aluminum alkyl compound provides a catalyst composition with increased activity and also improves the morphology of the resulting ethylene polymer particles. The catalyst used in the present invention is prepared by first preparing a precursor composition from a titanium compound, a magnesium compound, and an electron donor in one or more steps as described below, and then combining this precursor composition with a carrier material and an active material. It is produced by processing the agent compound 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 ranging from about 20° C. to the boiling point of the compound. The titanium compound can be added to the electron donor compound before, after, or simultaneously with the addition of the magnesium compound. Dissolution of the titanium and magnesium compounds can be promoted by stirring and, in some cases, by refluxing both of these compounds in an electron donor compound. After the titanium and magnesium compounds are dissolved, the precursor composition is separated by precipitation or crystallization with a _C5 to _C8 aliphatic or aromatic hydrocarbon such as hexane, isopentane or benzene. The precipitated or crystallized precursor composition is isolated in the form of fine, free-flowing particles with an average particle size of about 10-100 microns and a bulk density of about 18-33 lb/ ^ft3 . A particle size of 100μ is preferred for use in fluidized bed processes. The particle size of the isolated precursor composition can be controlled by the crystallization or precipitation rate. When the precursor composition is prepared as described above, it has the formula Mg _n Ti ₁ (OR) _o X _p [ED] _q . In the formula, ED is an electron donor compound, m is 0.5-56, preferably 1.5-5.0, n is 0-1, p is 6-116, preferably 6-14, and q is 2-85. Preferably 4 to 11, R is a _C1 to _C14 aliphatic or aromatic hydrocarbon group or COR' (where R' is a _C1 to _C14 aliphatic or aromatic hydrocarbon group), and X is selected from the group consisting of Cl, Br, I or a mixture thereof. The letter written at the bottom right of the element titanium (Ti) is the Arabic numeral 1. The polymerization activity of a fully activated catalyst is so high in the process of the invention that it is necessary to dilute the precursor composition with a support material in order to effectively control the reaction rate. Dilution of the precursor composition can be accomplished before the precursor composition is partially or fully activated, or in parallel with such activation, as described below. The dilution of the precursor composition is from about 0.035 to 1 part, preferably about 0.1 part.
This is accomplished by mechanically mixing or blending ~0.33 parts by weight of the precursor composition with 1 part by weight of the carrier material. For use in the method of the invention, the precursor composition must be fully or completely activated. That is, it must be treated with sufficient activator compound to convert the Ti atoms of the precursor composition to an active state. However, it has been found that even when an inert support is present, the method of activating the catalyst is very critical in order to obtain active substances. For example, a method similar to that described in U.S. Pat. Activation of the catalyst was attempted by adding it to the composition and subsequently removing the solvent by drying this slurry at a temperature between 20 and 80 °C to facilitate the use of the catalyst in gas phase processes. For commercial purposes, the gas phase fluidized bed process described below resulted in a product that was not sufficiently active. To prepare a useful catalyst, this activation or activation must be carried out in the absence of solvent, at least the final activation step, so that no further removal of solvent is required to obtain a sufficiently active dry catalyst. It was found necessary to implement the project in this manner. Two methods have been developed to achieve such results. In one method, the precursor composition is fully activated in the absence of a solvent by dry blending the precursor composition and an activator compound outside the reactor. In this dry blending method, the active agent compound is preferably used while being absorbed in a carrier material. However, this process had the disadvantage that the resulting fully activated dry catalyst was pyrophoric if it contained >10% by weight of activator compound. In another and preferred method of catalyst activation, the precursor composition is partially activated with an activator compound in a hydrocarbon slurry outside the polymerization reactor, and the hydrocarbon solvent is removed by drying; The partially activated precursor composition is then fed to a polymerization reactor where activation is completed with additional activator compound. Thus, in dry blending catalyst preparation methods, a solid particulate precursor composition is added to solid particles of a porous carrier material, homogeneously blended therewith, and the activator compound is absorbed. The activator compound, from its hydrocarbon solvent solution,
It is adsorbed onto the carrier material to give a coverage of about 10 to 50% by weight of active agent relative to the weight % of the carrier material. The amounts of precursor composition, activator compound, and carrier material used are such as to provide the desired Al/Ti molar ratio and a weight ratio of precursor composition to carrier material of no more than about 0.50, preferably no more than about 0.33. in such an amount as to give a final composition with The amount of support material thus provides the necessary dilution of the activated catalyst to provide the desired control of the polymerization activity of the catalyst in the reactor. If the final compositions contain about 10% by weight of activator compound, they are pyrophoric. During the dry blending operation (which may be carried out at ambient temperature (25 °C) or lower), the dry mixture is initially exothermic to avoid heat accumulation during the subsequent reduction reaction. Stir thoroughly. The resulting catalyst is thus completely reduced and activated and can be fed to the polymerization reactor and used therein as is. It is a free-flowing particulate material. In a second preferred method of catalyst activation, activation is carried out in at least two stages. In a first step, a solid particulate precursor composition diluted with a carrier material is mixed with a partially activated precursor having an activator compound/Ti molar ratio of about 1 to 10:1, preferably about 4 to 8:1. The body composition is reacted with sufficient active agent compound to provide the body composition and partially reduced.
This partial activation reaction is preferably carried out in a slurry of hydrocarbon solvent and the solvent is then removed by drying the resulting mixture at a temperature of the order of 20-80°C, preferably 50-70°C. . In this partial activation method, the activator compound can be used while being absorbed into the carrier material used to dilute it. The resulting product is a free-flowing solid particulate material that can be easily fed to a polymerization reactor. However, partially activated precursor compositions, at best, are poorly active as polymerization catalysts in the process of the present invention. To make this partially activated precursor composition active for ethylene polymerization, an additional amount of activator compound is added to the polymerization reactor to complete activation of the precursor composition in the reactor. I have to let it happen. Additional activator compound and partially activated precursor composition are preferably fed to the reactor by separate feed lines. Additional activator compounds may be sprayed into the reactor as a solution in a hydrocarbon solvent such as isopentane, hexane or mineral oil. This solution typically contains about 2-30% by weight of activator compound. The activator compound may also be added to the reactor in solid form by absorption onto a carrier material. For this purpose, the carrier material usually contains 10 to 50% by weight of active agent. The additional activator compound increases the total Al/Ti molar ratio in the reactor from about 10 to 400, preferably about 15 when the activator compound and titanium compound are fed to the partially activated precursor composition. ~60% to the reactor. The additional amount of activator compound added to the reactor reacts with the titanium compound within the reactor to complete activation. In continuous gas phase processes, such as the fluidized bed process described below, a partially or fully activated precursor composition is continuously fed in portions to the reactor and then treated during the continuous polymerization process. , the additional activator compound necessary to complete the activation of the partially activated precursor composition is delivered in portions to restore the active catalyst sites consumed during the reaction process. Do it like this. Polymerization Reaction The polymerization reaction is carried out in the absence of moisture, oxygen, carbon monoxide, carbon dioxide, and catalyst poisons, such as acetylene, by a gas phase method such as that found in fluidized beds, as described below, with a sufficient amount of water to initiate the polymerization reaction. It is carried out by contacting the monomer stream with a catalytically effective amount of a fully activated precursor composition (catalyst) at temperature and pressure. In order to obtain the desired density range of the copolymer, enough C ₃ , comonomer and ethylene are added to give a C ₃ -C ₈ comonomer proportion of 1 to 10 mol % in the copolymer. It is necessary to copolymerize. The amount of comonomer required to achieve such results will vary depending on the type of comonomer used. The table below lists the amounts (in moles) of various comonomers that must be copolymerized with ethylene to obtain a polymer having the desired density range at a given melt index. This table also lists the relative molar concentrations of comonomer/ethylene that must be present in the monomer gas stream fed to the reactor.

[Table] A flow reaction system that can be used to carry out the present invention is illustrated in FIG. To explain this, the reactor 10 consists of a reaction zone 12 and a moderation zone 14. Reaction zone 12 contains growing polymer particles and formed polymer particles fluidized by continuous passage of a reforming polymerizable gas component in the form of a make-up feed and a recycle gas through the reaction zone. Consists of a bed with catalyst particles. To maintain a vegetative fluidized bed, the flow rate of the gaseous body through the bed must exceed the minimum flow rate required for fluidization, preferably about G _nf .
It is 1.5 to 10 times, more preferably about 3 to 6 times.
G _nf as used here refers to the minimum flow rate of the gaseous body required to achieve fluidization [CYWen
& Y.H.Yu, "Mechanics of Fluidization", Chemical Engineering Progress
Symposium Series, Vol.62, p100-111
(1966)]. It is essential that the layer always contains particles to prevent the formation of local "hot spots" and to confine the particulate catalyst to the reaction zone and distribute it throughout the zone. At start-up, the reaction zone is usually charged with a layer of particulate polymer before the gas is passed. Such particulate polymer may be the same type as the polymer to be produced, or may be different. When the type is different, it is removed together with the desired polymer particles to be formed as the initial product. Eventually, the start-up layer is replaced by a fluidized bed of intended polymer particles. The partially to fully activated precursor composition (catalyst) used in the fluidized bed is preferably stored in a gas-sealed reservoir 32 in preparation for use. Thus, the gas is inert to the storage material, such as nitrogen or argon. Fluidization is accomplished by high flow rates of circulating gas (typically on the order of about 50 times the flow rate of the make-up gas feed) into and through the bed. The fluidized bed is
It has the appearance of a dense body of vegetative particles in the form of a free spiral flow, as formed by the gentle passage of gas through the layer (percolation). The pressure drop across this layer is equal to or slightly higher than the cross-sectional area of the entire layer, thus
It depends on the reactor geometry. Makeup gas is supplied to the bed at a flow rate equal to the flow rate at which the product polymer particles are removed. The composition of the makeup gas is measured by a gas analyzer 16 located above the layer. This device measures the composition of the gas that is to be recycled. Accordingly, the makeup gas composition is adjusted to maintain an essentially steady state gas composition within the reaction zone. To ensure complete fluidization, the recycle gas and, if desired, a portion of the make-up gas are returned into the reactor from a point 18 located below the fluidized bed. Thus, a gas distribution plate 20 is present above the return point 18 to aid fluidization of the bed. The portion of the gas flow that does not react in the bed constitutes the circulating gas. This is preferably removed from the polymerization zone by passing it through a moderation zone 14 located above the layer, where the entrained particles are given the opportunity to fall back into the layer below. Particle return may be assisted by a cyclone 22 which may form part of the deceleration zone or may be located outside of it. When desired, the circulating gas is supplied at a high gas flow rate to prevent fines from contacting heat transfer surfaces or compressor blades.
It may be passed through a filtration device 24 designed to remove small particles. The circulating gas is then compressed in a compressor 25 and passed through a heat exchanger 26 where the heat of reaction is removed and then returned to the bed. Due to the constant removal of the heat of reaction, there does not seem to be any noticeable temperature gradient in the upper part of the layer. However, about 6 to 12 inches at the bottom of the bed, a temperature gradient exists between the inlet gas temperature and the temperature of the remainder of the bed. The bed thus almost immediately adjusts the temperature of the circulating gas that has come above this bottom layer of the bed zone to make it similar to the temperature of the rest of the bed, thereby keeping it essentially isothermal under steady-state conditions. It has been observed that it works. Thus, the recycled material is transferred to the base 18 of the reactor.
The liquid then enters the vessel and is returned to the fluidized bed through the distribution plate 20. Compressor 25 can also be installed downstream of heat exchanger 26. When operating the reactor, the role played by the distribution plate 20 is important. The fluidized bed contains growing or forming particulate polymer particles and catalyst particles. When the polymer particles are hot and can be active, their settling must be prevented. This is because if a stationary body is present, the active catalyst contained therein can continue to react and cause melting. It is therefore important to diffuse the circulating gas into the bed at a flow rate sufficient to maintain fluidization at the base of the bed. The distribution plate 20 serves this purpose and can be a screen, a slotted plate, a perforated plate, a bubble bell plate, etc. All members of the plate may be stationary or may be of the movable type as disclosed in US Pat. No. 3,298,792. Whatever the plate design, it must disperse the circulating gas into the particles at the base of the bed to keep them in a fluid state and keep the resin particles flowing when the reactor is not in operation. It must function to support the stationary layer. The movable parts of the plate are
It can be used to dislodge and displace any polymer particles trapped within or deposited on the plate. In the polymerization reaction of the present invention, hydrogen can be used as a chain transfer agent. The hydrogen/ethylene ratio used is approximately 0 per mole of ethylene monomer in the gas stream.
Corresponds to ~2.0 moles of hydrogen. Any gas inert to the catalyst and reactants may be present in the gas stream. The activator compound is preferably added to the reactor at the hottest portion of the gas, which is typically downstream of heat exchanger 26. The active agent may thus be supplied from the dispenser 27 to the gas circulation system via the line 27A. In order to increase the melt index value of the copolymer to be produced, the structure Zn(R _a )(R _b ) (where R _a and
R _b is the same or different C ₁ -C ₁₄ aliphatic or aromatic hydrocarbon groups) can be used together with hydrogen in combination with the catalyst of the present invention. this
The Zn compound is present in the gas flow in the reactor at a concentration of about 0 to 50% per mole of titanium compound (as Ti) in the reactor.
It is preferably used in molar amounts of about 20-30 molar (as Zn). The Zn compound is also preferably in the form of a dilute solution (2-10% by weight) in a hydrocarbon solvent or in a solid diluent such as silica.
It is introduced into the reactor in adsorbed form at 50% by weight. These compositions are therefore prone to spontaneous combustion. The zinc compound may be added alone or may be added to the reactor from a feed device (not shown, which could be adjacent to the dispenser 27 near the hottest part of the gas circulation). It may also be added with an additional portion of activator compound. It is essential to operate the fluidized bed reactor at a temperature below the sintering temperature of the polymer particles. Then,
A working temperature below the sintering temperature is desirable to ensure that sintering does not occur. To produce an ethylene copolymer by the method of the present invention, the temperature is about 30-115°C.
A working temperature of about 75-95° C. is preferred, and a temperature of about 75-95° C. is most preferred. Temperatures of about 75-90°C are used to produce products with densities of about 0.91-0.92, and temperatures of about 80-100°C are used to produce products with densities of about >0.92-0.94.
temperature is used. Fluidized bed reactors are operated at pressures up to about 1000 psi, preferably between about 150 and 350 psi. By using pressures at the higher end of this range, heat transfer is facilitated. This is because an increase in pressure increases the unit volume heat capacity of the gas. The partially to fully activated precursor composition is injected into the layer from a point 30 located above the distribution plate 20 at a flow rate equal to its consumption.
Injecting the catalyst from a point above the distribution plate is an important feature of the invention. Because the catalyst used in the practice of this invention is highly active, if a fully activated catalyst is injected into an area below the distribution plate, polymerization will begin there and eventually cause clogging of the distribution plate. become. Instead, injection into the vegetative layer helps distribute the catalyst throughout the layer and tends to eliminate the formation of localized areas of high catalyst concentration that can also cause the formation of "hot spots." A gas inert to the catalyst, such as nitrogen or argon, is used to convey the partially to fully activated precursor composition and any required additional activator compound or non-gaseous chain transfer agent into the bed. used. The rate of layer formation is controlled by the catalyst injection rate. Bed productivity can be increased by simply increasing the catalyst injection rate, and can be decreased by simply decreasing the catalyst injection rate. Since changing the catalyst injection rate also changes the amount of reaction heat generated, the temperature of the circulating gas is adjusted up or down to adjust this amount of heat. Thus, an essentially constant temperature is thereby ensured within the layer.
Also, of course, complete mechanization of the fluidized bed and circulating gas cooling system is required to be able to detect any temperature changes within the bed so that the operator can adjust the temperature of the circulating gas accordingly. Under given combined operating conditions, the fluidized bed is maintained at an essentially constant height by withdrawing a portion of the bed as product at a rate equal to the production rate of particulate polymer product. Since there is a direct relationship between the rate of heat generation and the rate of product formation, it is useful to measure the temperature rise of the gas across the reactor (the difference between the temperature of the incoming gas and the temperature of the outgoing gas) when the gas velocity is held constant. Therefore, the production rate of particulate polymer is determined. The granular polymer product is preferably distributed on a distribution plate 20
Or it is taken out continuously from a location 34 in the vicinity. The particles are then suspended in a portion of the gas stream and discharged before they settle, in order to prevent them from reaching their final collection zone and further polymerizing and sintering. This antisedimentation gas can also be used to transport the product from one reactor to another, as described above. Preferably, the particulate polymer product is continuously withdrawn by continuous operation of a pair of timing valves 36 and 38 defining a separation zone 40. While valve 38 is closed, valve 36 is open releasing a plug of gas and product between valve 36 and zone 40 into zone 40, and then valve 36 is closed. At that time, valve 3
8 is opened to transport the product to an external collection zone. Valve 38 is then closed in preparation for the next product recovery operation. Finally, the fluidized bed is equipped with a suitable drainage system for draining the bed during start-up and shutdown. Then,
This reactor does not require the use of stirring and/or wall scraping means. The supported highly active catalyst system of the present invention has approximately 0.005
It is believed to result in a fluidized bed product having an average particle size of ~0.07in, preferably about 0.02-0.04in. A gaseous monomer stream, with or without an inert gas diluent, is fed to the reactor at a production rate of about 2 to 10 lb/hr/ft ³ per unit space (bed volume) time. As used herein, the term "virgin resin (or polymer)" refers to the particulate polymer as it is recovered from the polymerization reactor. The copolymers of the present invention may contain additives such as fillers, pigments, stabilizers, antioxidants, lubricants, flame retardants, UV absorbers, plasticizers, blowing agents, etc. to produce the desired effect. Can be added in amounts. Processing The articles of the invention are manufactured by methods well known in the art, such as injection molding, rotational molding, blow molding. Articles such as lids, closures, food and garbage containers, wash basins, and toys are manufactured by ram or screw injection molding processes well known in the art. For example, "Polythene" by Renfrew Morgan, 2nd edition, pages 549-570 (1960, published by Interscience Publishers),
Describes injection molding of polyethylene. Articles of the invention are molded on standard injection molding machines. In this molding, the copolymer is heated in a molding machine to a temperature of about 180 DEG to 270 DEG C. until plasticized and then injected into a mold cavity of the desired shape at a gage pressure of about 500 to about 2000 psi. The copolymer is cooled within the mold cavity at a temperature of about 15 to about 60°C until it conforms to the shape of the mold cavity. The molded article is then removed from the mold. Articles such as bottles and containers are molded by injection or extrusion blow molding processes well known in the art. For example, Renfrow-Morgan, Ibid., 571-579.
Page describes blow molding of polyethylene.
In blow molding, the copolymer is heated in a molding machine as described above, then heated to a temperature near the melting point of the resin;
It is injected into a mold cavity, preferably maintained at about 80 to about 120 degrees Celsius, and formed into a tubular body called a parison, which is then transferred to another cooling mold with the desired shape and applied to the walls of the mold cavity. The sample is pressed against the sample using air pressure, and then cooled. The article is then removed from the mold. Extrusion blow molding, for example, consists of extruding an elongated tube of copolymer into a split mold, which is then closed by sealing at either the top or the bottom. This tube is then inflated against the internal contour of the mold, for example by air pressure introduced into the extrudate. The molding is then cooled, the mold is opened, and the contents are ejected. Articles such as large toys and industrial-sized food and garbage containers are primarily manufactured by rotational molding instead of injection molding because of the complex shapes and large economic factors involved. Rotational molding methods are well known in the art;
"Encyclopedia of Polymer Science and
9, pp. 118-137 (1968, published by Interscience Publishers). In this method, powdered resin or fine resin particles are charged into a mold cavity and then rotated in a heated oven (500-600°) until the resin melts and coats the inside of the mold cavity. The mold with the molten resin is then transferred to a cooling means,
There, the molten resin is cooled until it solidifies and conforms to the shape of the mold cavity. Before being processed by the above method, the copolymer may be mixed or compounded with various additives and then added to the molding machine, or alternatively the copolymer may be directly added to the molding machine with the additives. May be added. Articles Molded articles of the present invention made from ethylene hydrocarbon copolymers include lids, closures, containers for food and garbage, washing tubs, bottles, rice cakes, hinges, and the like. The articles of the present invention may, if desired, be subjected to further treatments such as coating, painting, etc., depending on its end use. EXAMPLES The following examples are intended to illustrate the articles of the invention and their molding, and are not intended to limit the invention in any way. The properties of the copolymers of the present invention were determined by the following test methods. Density ASTM D-1505 Condition plate samples at 100°C for 1 hour to approach equilibrium crystallinity. g/
Record as cc. All density measurements are performed on density gradient columns. Melt index (MI) ASTM D-1238
- Condition E - Measured at 190℃ - g/
Recorded in units of 10 min. Flow rate (HLMI) ASTM D-1238-Condition F-Measured at 10 times the weight used in the melt index test above. Melt flow ratio (MFR) = flow rate/melt index molecular weight distribution (Mw/Mn) Gel permeation chromatography Eastylogel packing: Porosity order is
10 ⁷ , 10 ⁵ , 10 ⁴ , 10 ³ , and 60 Å. The solvent is
It is perchlorethylene at 117℃. Detection: Infrared at 3.45μ. Unsaturated infrared spectrophotometer (Perkin Elmer,
Model 21). A press molded article prepared from 25 mil thick resin was used as the test specimen, and the transvinylidene unsaturation was 10.35μ.
Absorbance is measured at 11.0μ for terminal vinyl unsaturation and at 11.25μ for pendant (side chain) vinylidene unsaturation. The absorbance per ml of thickness of a press-formed product is directly proportional to the product of the unsaturated concentration and the extinction coefficient. In addition,
The extinction coefficient is the literature value of RJde Kock et al. [J.
Polymer Science, Part B, 2, 339
(1964)] was adopted. Preparation of the precursor composition In 5 flasks equipped with a mechanical stirrer
16.0 g (0.168 mol) of anhydrous MgCl ₂ was mixed with 850 ml of pure tetrahydrophthane under nitrogen atmosphere. This mixture was stirred at room temperature (~25<0>C) while 13.05 g (0.069 mol) of _TiCl4 was added dropwise thereto. After complete addition of _TiCl4 , the contents of the flask were heated until reflux occurred, about 1/2 to 1 hour, to dissolve the solids. The system was then cooled to room temperature and 3 pure n-hexane was added slowly over 1/4 hour. As a result, a yellow solid was precipitated. Decant the supernatant and
Washed 3 times with 1 of n-hexane. The solids were then filtered and heated to 40-60 °C in a rotary evaporation flask.
to form 55 g of solid precursor composition. At this point in the precursor composition, some of the Mg and/or Ti compounds may have been lost during the isolation of the precursor composition.
Analyze the content of Mg and Ti. The empirical formula used in this example to record these precursor compositions is that the Mg and Ti are present in the form of the compounds as they were originally added to the electron donor, and the precursor It was derived by assuming that all other residual weight in the body composition is due to the electron donor compound. The results of solid analysis are Mg: 6.1%, Ti:
It was 4.9%. This is TiMg2.45 Cl8.9
(THF) equivalent to 7.0. THF stands for tetrahydrofuran. Activation Procedures Procedure A: This procedure relates to a multi-step activation process of precursor compositions. According to this operation, the precursor composition is only partially reduced before it is introduced into the polymerization reactor, and activated so that the remaining reduction process is completed after it is introduced into the reactor. I do. Charge the desired weight of dry, inert carrier material into a mixing vessel or tank. In the examples described herein, the amount of inert carrier material is approximately 500 grams for silica and approximately 1000 grams for polyethylene carrier. This inert carrier material is then mixed with a sufficient amount of anhydrous aliphatic hydrocarbon diluent, such as isopentane, to form a slurry system. Making a slurry typically requires about 4 to 7 ml of diluent per gram of inert carrier. The desired weight of the precursor composition is then charged into the mixing vessel and thoroughly mixed into the slurry system. The amount of precursor composition used in this activation operation to prepare the catalyst in the examples described herein is about 80-135 grams.
The precursor composition has an elemental titanium content of 1±0.1 mmol/g. The desired amount of activator compound necessary to partially activate the precursor composition is added to the contents of the mixing vessel to partially activate the precursor composition. The amount of activator compound used here depends on the Al/
Ti ratio >0-10:1, preferably 4-8:1
This is the amount. The activator compound is mixed in the form of a solution containing approximately 20% by weight of the activator compound (triethylaluminum in the example described) in an inert aliphatic hydrocarbon solvent (hexane in the example described herein). Add to tank. Activation is accomplished by mixing and contacting the activator compound with the precursor composition. All of the above operations are carried out at room temperature and at atmospheric pressure in an inert atmosphere. The slurry thus obtained is dried to remove the hydrocarbon diluent at atmospheric pressure and a temperature of 60° C. under a dry inert purging gas such as nitrogen or argon. This process usually requires about 3-5 hours. The resulting product has an activated precursor composition homogeneously blended with an inert carrier. It is in the form of a dry, free-flowing granular material. The dried non-pyrophoric product is stored under an inert gas atmosphere. If additional activator compound is to be fed to the polymerization reactor in this step A to complete the activation of the precursor component, it is preferable to first adsorb the activator onto an inert compound such as silica or polyethylene. Most preferably, however, the activator is injected into the reaction zone as a dilute solution in a hydrocarbon solvent such as isopentane. If the activator compound is to be absorbed onto a silica support, the two materials are mixed in a vessel containing about 4 ml of isopentane per gram of carrier material. The resulting slurry is then dried to remove the hydrocarbon diluent at a temperature of 65±10° C. for about 3 to 5 hours under a purge nitrogen atmosphere at atmospheric pressure. When the activator compound is injected into the polymerization reaction system as a dilute solution, a solution having a concentration of about 5 to 10% by weight is preferred. Regardless of the method used to introduce the activator into the polymerization reactor to complete the activation of the precursor composition, the activator increases the Al/Ti ratio within the reactor from 10 to 400. :1, preferably 10
Add in proportions to maintain a level of ~100:1. The silica was heated to 200°C before being used in the present invention.
Let dry for 4 hours. Operation B: In this operation, complete activation of the precursor composition is achieved by blending and contacting the precursor composition with an activator compound absorbed on an inert carrier material. The activator compound is adsorbed onto the inert carrier material by slurrying it with the carrier material in an inert hydrocarbon solvent and then drying the slurry to remove the solvent, thereby producing a
A composition containing 50% by weight of activator compound is prepared. That is, 500 g of silica, which had been previously dehydrated at a temperature of 800° C. for 4 hours, was charged into a mixing container. The desired amount of activator compound is then dissolved in a hydrocarbon solvent such as, for example, hexane.
Add to the mixing vessel as a % weight solution and mix (slurry) with the inert carrier at room temperature and atmospheric pressure. The solvent is then removed by drying the resulting slurry in a flowing stream of dry inert gas, such as nitrogen, at atmospheric pressure and a temperature of 65±10° C. for about 3 to 5 hours. This dried composition is in the form of free-flowing particles having the size of the carrier. Approximately 500 g of dry silica carrier activator (50/50 weight percent silica/activator) is then placed in the mixing vessel. Desired weight of precursor composition (80-100
g) is also added into this mixing vessel. These materials are thoroughly mixed under a dry inert gas such as nitrogen or argon at atmospheric pressure and room temperature for about 1-3 hours. The resulting composition is a physical mixture of dry, free-flowing particles having a particle size on the order of 10-150 microns. During this mixing operation, the activator contacts the precursor composition and fully activates it. During the resulting exothermic reaction, the temperature of the catalyst is 50°C to avoid significant deactivation of the catalyst composition.
should not be exceeded. The activated composition thus obtained has an Al/Ti ratio of approximately 10:50 and may be pyrophoric if it contains >10% by weight of activator. The composition is kept under a dry inert gas such as nitrogen or argon until it is injected into the reactor. Example 1 In this series of experiments, the catalyst produced as described above and activated by activation procedure A was used to convert ethylene to propylene or butene-1.
(propylene in experiments 1 and 2, experiment 3
~14, copolymerized with butene-1),
A polymer with a density of 0.940 was produced. In each case, the Al/Ti molar ratio of the partially activated precursor composition was between 4.4 and 5.8. Completion of activation of the precursor composition in the polymerization reactor was accomplished using triethylaluminum (as a 5 wt% solution in isopentane in runs 1-3 and 6-14,
and 5 as adsorbed on silica at a 50/50 wt% ratio) to produce a fully activated catalyst with an Al/Ti molar ratio of about 29-140 in the reactor. . The polymerization reaction for each experiment was carried out in a fluidized bed reactor at a pressure of about 300 psig for >1 hour after equilibrium was reached, at a gas velocity of about 5 to 6 times Gmf, at a gas velocity of about 3 to 1 ft ³ per ft 3 of bed space. It was run continuously with a space-time yield of 6 lbs/hr. The reactor system is as shown in the accompanying drawings and has a lower section 10 feet high and 13 1/2 inches inside diameter and an upper section 16 feet high and 23 1/2 inches inside diameter. In some experiments, diethylzinc was added as a 2.6% by weight solution in isopentane during the reaction run;
A constant Zn/Ti molar ratio was maintained. When diethylzinc was used, triethylaluminum was also added as 2.6% by weight of isopentane. Table A below shows the following operating conditions used for Experiments 1-13. the weight percent of the precursor composition in the blend of silica and precursor composition; the Al/Ti ratio of the partially activated precursor composition; the Al/Ti ratio maintained within the reactor; the polymerization temperature; Volume % of ethylene in the reactor; _H2 /ethylene molar ratio; comonomer (Cx)/ _C2 molar ratio in the reactor; productivity of the catalyst. Table B shows the properties of the granular virgin resins produced in Runs 1-13: density, melt index (MI); melt flow ratio (MFR); bulk density; and average particle size.

【table】

[Table] Example 2 Control The control was carried out at 16000 psi and
It is a high-pressure commercially available polyethylene resin (Union Carbide DNDA 0415) manufactured at 205°C. Example 3 Resins as produced in Examples 1 and 2 were injection molded to form wash basins and lids using 8 oz. Impco and 3 oz. Moslo injection molding machines, respectively. Wash tub is 500 oz. in an 8 oz Impco molding machine
It was injection molded at a cylinder temperature of 1,400 psi, an injection gauge pressure of 1400 psi, and a clamping time of 44 seconds. The settings for other attached devices are as listed in the table. The lids were injection molded in a 3 oz. Moslo ram machine at a material temperature of 545 mm, a gauge pressure of 825 psi, and a clamp time of 15 seconds. The lid is also provided with a central gate with an opening 0.030in in diameter and 0.030in in length.
The diameter was 6 inches and the thickness was 0.040 inches. Other suitable conditions are listed in the table. Table Machine type Impco Injection pressure psi 1400 Cylinder temperature 〓 Nozzle 500 Front 500 Center 500 Rear 450 Mold temperature 〓 Movable 80 Fixed 75 Cycles, sec Injection 12 Clamp (mold clamping time) 44 Booster 4 Break pack 4 Gate Delay 12 Gate Spacing 72 Each of the resins of Examples 1 and 2 was tested for secant modulus of elasticity according to ASTM D638. Further, the melt index, density and melt flow ratio of these resins are as shown in the table. The lids were tested for stress cracking resistance in Crisco oil. The lid was bent so that the sides were facing outward, the opposing edges touching and stapled together. The bent portion opposite the stapled edge was then immersed in Crisco oil until cracks were observed. The results are shown in the table. The low temperature impact strength of the washing tub was measured at -40〓 and -60〓. This is done by dropping a 10lb cylindrical spear with a 1in diameter hemispherical head from an elevated height of 3in above the sprue surface of the washtub until the washtub is shattered or perforated. I was disappointed. The height at which failure occurred was multiplied by the weight of the spear, and the result was reported in ft-lb. The degree of warpage and gloss was determined by visual observation in comparison to a similar product molded under the same conditions from a high pressure polyethylene resin of the same melt index and density. The data shows that products molded from the ethylene hydrocarbon copolymers of the present invention have higher stiffness, superior stress cracking resistance, and impact strength as indicated by secant modulus, compared to products molded from high-pressure polyethylene resins. and warpage resistance.

【table】

[Table] Warpage resistance Excellent Very good Examples 4 to 7 Copolymers were prepared according to the procedure of Example 1. a comonomer reacted with ethylene to produce a copolymer; a melt index of the resulting copolymer;
The density and melt flow ratio are as shown in the table.

TABLE Examples 8-11 Each of the polymers of Examples 4-7 was molded in an 8-ounce Impco molding machine as described in Example 3 at a cylinder temperature as listed in the table and a gauge pressure 100 psi above the lowest mold fill pressure. I made a washing tub. The cold impact strength of the washing tub was reduced to −40 by following the procedure as described in Example 3.
Measured at 〓 and −60〓. The results are shown in the table. The data shows that products such as wash tubs formed from the copolymers of the present invention have excellent impact strength.

Table: (1) Two out of six cracked Examples 12-19 Examples 12-19 butene-1 copolymers were prepared according to the procedure of Example 1. The comonomers reacted to form the polymer and the density, melt index and secant modulus of the copolymer produced are as shown in the table. The high pressure polyethylene resins of Examples 17-19 were commercially available under the trade names "PEP" 231, 530 and 440 (Union Carbide Corporation).

[Table] Example 20 Washing tubs were made by injection molding the butene-1 copolymer resins of Examples 13 to 15 under the conditions previously described and then tested for impact strength at -60〓 according to the procedure previously described. Tested. Perforations occurred in the wash tub at a number of ft-lb as shown in the table. Wash tubs molded from the high pressure control resin of Example 3 were crushed at 5 ft-lb.
The data are shown in the table. Table resin example impact strength (ft-lb) 13 25.8 (perforation) 14 20 (perforation) 15 20.8 (perforation) 3 5 (crushing) Examples 21-23 Butene-1 copolymer was prepared according to the procedure of Example 1. . “DNDA 0180” (Union Carbide
A commercially available high-pressure polyethylene designated as Co., Ltd. was used as a control. Also included for comparison is the low pressure process resin of Example 12, which has a higher melt index than either the butene-1 copolymer or polyethylene. The resin was compression molded in accordance with ASTM D-1928 to produce specimens 0.125 inches thick, and ASTM
Follow the instructions for D1693 Vent Strip Test
Tested for stress cracking resistance in 100% Igepar. The time required for 50% of 20 molded specimens to crack was measured at 50°C. The results are shown in the table.

The results show that even though the low pressure resins are about 50% higher in modulus than the high pressure resins and therefore under more stress in the vent strip test, they are the most stress crack resistant commercially available polyethylenes. It shows that it is substantially better in stress cracking resistance than high pressure stirred reactor resins, which are considered one of the most popular. Even when the melt index of the low pressure process resin was increased to 7.0 as in Example 23, the low pressure process resin was substantially more stress crack resistant than the high pressure process resin having a melt index of 2.0. An increase in melt index is usually caused by
Decreases stress cracking resistance. Examples 24-27 Each of the polymers of Examples 4-7 was molded into a lid in a 3-ounce Moslo injection molding machine as described in Example 3 at a cylinder temperature as listed in the table and a gauge pressure of 120 psi above the lowest mold fill pressure. I made it. The lids were tested for stress cracking resistance in Crisco oil according to the procedure described in Example 3. The results are shown in the table. The data shows that articles such as lids made from the copolymers of the present invention have excellent stress cracking resistance.

Table: Example 28 The butene-1 copolymer resins of Examples 12-16 were injection molded into lids and then subjected to Crisco oil stress cracking resistance testing as previously described. No cracks were observed in the bends even after 21 days of immersion in Crisco oil. Under similar conditions, the high pressure resin of Example 3 cracked after 3 minutes.

[Brief explanation of drawings]

FIG. 1 shows a gas phase fluidized bed reactor in which the catalyst system of the present invention can be used. The explanations of the symbols representing the main parts in the figure are as follows: 10: reactor, 12: reaction zone, 14: deceleration zone, 16: gas analyzer, 18: gas introduction point,
20: Gas distribution plate, 22: Cyclone, 2
4: filtration device, 26: heat exchanger, 27: dispenser, 30: inert gas introduction point, 32: reservoir for impregnated precursor composition, 34: product discharge point.

Claims (1)

[Claims] 1. A low-pressure vapor phase copolymer of ethylene and at least one monomer selected from the group consisting of propylene and butene-1, which has an Mw/Mn in the range of 2.7 to 4.1 and 22 to 32. Melt flow ratio, 0.1
~0.3C=C/1000C atoms total unsaturated group content,
Low pressure vapor phase process with density of 0.91-0.94, melt index of 7-100 g/10 min, secant modulus of 30000-80000 psi, stress cracking resistance of 21 days or more and impact strength of 20 ft 1b at -40°C. Washing tub injection molded from polymer.