KR19990071757A - Products made of polypropylene, higher alpha-olefin copolymers - Google Patents

Abstract

Molded or extruded products made from propylene, α-olefin copolymers in which the α-olefins have 5 or more carbon atoms (higher alpha-olefins (HAO)) and the copolymers are prepared using a metallocene catalyst system are used for The coalescence provides substantially higher cold flow resistance and resilience than when the coales contain α-olefins having up to 4 carbon atoms. Other properties such as ultimate tensile strength and impact strength are also substantially higher. The polymers can be used alone or advantageously in extrusion profiles and molded parts with thermoplastic olefins (TPO). Parts made from propylene HAO copolymers or compounds made therefrom exhibit improved creep resistance over propylene ethylene copolymers.

Description

Products made of polypropylene, higher alpha-olefin copolymers

Polyolefin polymers are well known commercial products. Polyolefins have many uses and are well known to those skilled in the art. Polyolefins have many useful properties. However, in many applications, polyolefins exhibit unacceptable low temperature flow properties, ie they exhibit fluidity when subjected to small amounts of stress for extended periods of time at room or use temperatures. Low temperature flow resistance is one of the important properties in many polymer applications. Low temperature fluidity is defined as the irreversible deformation of a polymer product in response to an applied force or stress (less than the yield stress of a material) for an extended time at a selected temperature. Different polymers will exhibit different low temperature flow resistance.

Polypropylene homopolymers and copolymers are used in a wide range of applications. More than 5 million tonnes (4 million metric tons) of polypropylene are produced annually in the United States alone. Polypropylene has a variety of commercial uses, from packaging films and sheets to fiber structures used in molded food containers and diapers and hospital gowns, for example.

There are several types of polypropylene. One of these is a statistical copolymer of propylene, sometimes also known as a random copolymer, with another alpha-olefin (in this application, ethylene is included in this class). In the past, this could be largely represented by a copolymer of propylene and ethylene, typically prepared using a Ziegler-Natta catalyst. Copolymerization of higher alpha-olefins (HAO) (alpha-olefins having 5 or more carbon atoms) with propylene using Ziegler-Natta catalysts has been problematic in the past due to the low reactivity of these catalysts to higher alpha-olefins. Propylene-ethylene copolymers promoted by Ziegler-Natta catalysts have been commonly used in applications based on substantially different properties as compared to polypropylene homopolymers. Broadly stated, the difference between zigzag promoted homopolymers and propylene-ethylene copolymerization is manifested in properties such as lower melting point, greater flexibility, better transparency and slightly improved toughness in the copolymer.

EP 0 495 099 A1 (Mitsui Petrochemical Industries) proposes a process for the polymerization of propylene α-olefins using a metallocene-alumoxane catalyst system. This document also proposes propylene α-olefin copolymers in which propylene is present at 90 to 99 mol% and α-olefins are present at 1 to 10 mol%. It has been suggested that the propylene α-olefin copolymer will have a narrow molecular weight distribution (Mw / Mn), which will have a low melting point and will have excellent flexibility. The document also proposes a linear relationship between T _m and propylene content, but fails to distinguish the melting point drop action of different α-olefins.

EP 0 538 749 A1 (Mitsubishi Petrochemical Co.) proposes a propylene copolymer composition for producing a film having excellent low temperature heat sealability, which composition comprises from A 1 to 70 weight. % And B 30 to 99% by weight, where A is propylene ethylene or α-olefin copolymer, α-olefin has 4 to 20 carbon atoms or less Mw / Mn and B is propylene ethylene or α- It is an olefin copolymer, and alpha-olefin has Mw / Mn of 4-20 and 3.5-10 carbon atoms.

Copolymer A is polymerized with a metallocene catalyst system and copolymer B is polymerized with a Ziegler type catalyst.

Nearly all examples utilize propylene-ethylene copolymers or propylene homopolymers.

EP 0 318 049 A1 (Ausimont) proposes a crystalline copolymer of propylene with a small amount of ethylene and / or α-olefins. This copolymer is known to have very good mechanical properties. This copolymer is in the presence of a metallocene compound.

It is combined. In this document propylene-ethylene and propylene-1 butene copolymers are exemplified.

Among the polymers that have demonstrated acceptable low temperature flow resistance are polyvinyl chloride (PVC). The low temperature flow resistance of PVC enables the use of PVC in applications where relatively poor low temperature flow of polyolefins is unacceptable.

Wrapping fresh meat is one example of the poor properties of polyolefins compared to PVC. PVC films are known to "snap back" after deformation, and their value is recognized. This rapid recovery property is directly related to the cold flow resistance of the film. When exhibiting retail meats, such deformations are caused when handling packaged meats. Due to the "rapid recovery", meat wrapped in PVC does not exhibit the same handling effect even after packaging. When the polyolefin is transformed into handling, even after recovering the packaged meat itself (or even after restoring its shape before deforming) due to the low temperature flow tendency of the polyolefin, unacceptable finger marks or other depressions or deformations of the film are prevented. It has been repeatedly tried in film applications such as meat wraps, but with little commercial success. Polypropylenes and polyethylenes in polyolefins exhibit such defects, in particular due to their relatively poor low temperature flowability.

However, although PVC has many advantages in many other uses as well as those mentioned above, PVC has several substantial drawbacks that must be replaced by many plastics, for example polyolefins, which have high priority in many of the uses. . The first disadvantage is that the density of PVC is substantially higher than most polyolefins. Most PVC has a density of about 1.2 g / cc, whereas most polyolefins have a density lower than 1.0 g / cc. This has a very practical effect, ie a given PVC unit weight will yield substantially less product than polyolefin units. A second disadvantage of PVC is that it generates hydrochloric acid, for example when burning in waste or waste incinerators. Another drawback is the possibility of extracting plasticizers such as phthalate esters used in flexible PVC, especially in PVC applications involving food and pharmaceuticals.

Polypropylene can be molded or extruded in many forms. Conventional polypropylene homopolymers and conventional copolymers of propylene and ethylene exhibit creep or low temperature fluidity when subjected to forces or stresses. In addition, polypropylenes are often blended with other materials to modify their properties, for example to impart rubbery or even rubbery properties.

Certain types of blended polypropylene have rubbery properties. However, polypropylene compounds do not require vulcanization.

Polyolefins such as polypropylene are generally not considered elastic, but they are hard and lightweight. Rubber, on the other hand, is elastic, but hard.

Rubber products have generally found a wide range of uses in applications where elasticity and flexibility are required. The molding of the rubber into a final product requires a curing step, commonly called vulcanization, which also requires the use of special molding machines, long cycle times and a number of complex processing steps. Therefore, the rubber molding process cannot be easily mass produced due to such processing difficulties. It is highly desirable to find rubber or rubber-like compounds that do not require a vulcanization step.

Many attempts have been made to find such rubber analogs. For example, flexible plastics such as flexible vinyl chloride resins, ethylene / vinyl acetate copolymers and low density polyethylenes generally have excellent flexibility, assembly and molding properties, but poor heat resistance and resins that greatly limit their use. Experience Gillianency (Repulsive Elasticity)

To improve the properties of these flexible plastics, they were blended with high melting point plastics such as high density polyethylene and polypropylene. However, these blends lost flexibility.

More recently, a class of compounds with properties between the properties of cured rubbers and the properties of flexible plastics have been investigated. Such compounds are commonly referred to as thermoplastic elastomers (TPEs). Classical TPE structures include elastomeric matrices such as, for example, polybutadiene, polyester or polyurethane, bonded together in a thermoplastic bonding region. A well known example of TPE is Kraton ^R (a triblock of styrene and hydrogenated polybutadiene) commercially available from Shell, where a small area of glassy polystyrene is held together by a rubbery polybutadiene block at the thermoplastic crosslinking point. have. This structure is similar to the vulcanized elastomer at ambient temperature, but at temperatures above the polystyrene softening point, the system experiences plastic fluidity.

The subclass of thermoplastic elastomers in which only olefin based polymers are inserted is called thermoplastic olefin (TPO). Representative TPOs include melt blends or similar mixtures of one or more thermoplastic polyolefin resins with one or more olefin copolymer elastomers (OCEs). Thermoplastic polyolefin resins will provide TPO with hardness and temperature resistance, but elastomers not only improve the toughness of the material but also impart flexibility and resilience.

TPOs have special uses in the automotive business, for example in flexible exterior body parts such as bumper covers, nerf strips, air dams and the like. In such applications, it is desirable for the TPO to have good resilience (the ability to return to its original form after the part is deformed), low temperature impact strength, flexibility, high heat deformation temperature, surface hardness and surface finish. In addition, easy processability and moldability are desirable.

Other uses of TPO include films, footwear, sporting goods, electrical components, gaskets, water hoses and belts, which list only a few. Especially in a film, elastic modulus and transparency are important. Other of the above mentioned properties will be important depending on the intended use.

However, TPO experiences that the polypropylene matrix does not resist stress for a relatively long time compared to TPEs such as Kraton G.

Polymer compositions, such as TPE, exhibit low temperature flow resistance and resilience generally above TPO. This low temperature flow resistance and resilience allows the use of TPE in applications where the relatively poor low temperature flow and resilience of polyolefins such as polypropylene is unacceptable. Such applications include molded products for automobiles and appliances. In molded products, shape is often an important variable. Low temperature fluidity due to the contained load or low temperature fluidity due to the applied force results in an unacceptable and irreversible deformation in the molded part. In addition, if the molded part is assembled from most polyolefins rather than TPO, much less weight and time will be required to cause deformation or load-hardening by static loading. The performance of most polyolefins will be even worse compared to TPE.

While TPEs have many advantages as mentioned above, the cost of TPEs may not allow them in some applications and to a minimum in others. TPO is much cheaper than TPE, but on the other hand, it is not an ideal choice due to the above mentioned waterborne properties.

Therefore, polyolefins, in particular polypropylene copolymers, that resist cold flow to a degree sufficient to be able to replace the polypropylene component in conventional PPs or blends such as TPO in many applications are needed.

Summary of the Invention

Propylene copolymers prepared by polymerizing propylene with α-olefins (higher alpha-olefins (HAO)) comonomers having at least 5 carbon atoms using a metallocene catalyst system have an α-olefin having less than 4 carbon atoms (the purpose of the present application). It has been found that this type shows a surprising improvement in important physical properties compared to propylene copolymers using ethylene). In an embodiment of the present invention, the most surprising step change of the present invention is demonstrated at low temperature flow resistance or creep resistance values on products made from materials made according to this embodiment. Such changes will be noted in products made from the copolymers of the invention themselves, or in parts assembled from TPOs containing these copolymers.

In an embodiment of the invention, extrusion, molding and calendering products, such as films, tubes, extruded profiles, molded parts, sheets or other assembled products, contain isotactic statistical copolymers of propylene and HAO and otherwise contain these copolymers. It consists of a TPO. HAO is present in the range of about 0.2 to about 6 mole percent. The copolymer will have a molecular weight distribution (MWD) Mw / Mn (weight average molecular weight / number average molecular weight) of 5 or less and a peak melting point (DSC) in the range of about 100 ° C. to about 145 ° C. Products made with these copolymers will exhibit improved creep or low temperature flow resistance when compared to similar flexible propylene ethylene copolymers.

This application is a partial continuing application (CIP) of US patent application Ser. No. 08 / 248,283, filed May 24, 1994.

The present invention generally relates to films, sheets, molded articles, extruded profiles, tubes or the like made from propylene α-olefin copolymers. These products exhibit special physical properties, including relatively low cold flow or creep. More specifically, the present invention relates to the use of certain propylene α-olefin copolymers (prepared using metallocene catalyst systems), wherein the α-olefins are selected from those having at least 5 carbon atoms.

These and other features, aspects, and advantages of the present invention will be better understood with reference to the following description, appended claims, and the accompanying drawings, in which Figure I is the effect of comonomers on melting point drop in propylene copolymers. Indicates.

The present invention relates to certain types of assembled polypropylene products and their use. These products have unique features that make them very suitable for use in specific applications. Flexible films, tubes, sheets, extruded profiles, molded articles and other products made therefrom have superior low temperature flow resistance compared to extruded profiles and molded parts made from polypropylene-ethylene copolymers. The detailed description of the present invention describes certain resins that are preferred for use in assembling products that fall within the scope of the present invention, preferred methods of making these resins, and articles of resin.

Those skilled in the art will appreciate that many modifications can be made to these preferred embodiments without departing from the scope of the present invention. For example, although the properties of films and shaped plaques are used to illustrate the properties of the copolymers of the present invention, these copolymers have many different uses. Although the description of the present invention has been specified, it is only shown for the purpose of illustrating the preferred embodiments of the present invention and should not be limited to limiting the present invention to these specific embodiments.

The term random or statistical copolymer as used herein refers to a copolymer of propylene and other α-olefins polymerized in a medium in which the content of various comonomers and other process conditions remain substantially uniform during the reaction. If the resulting “reactor blend” polymer is miscible in the melt, the compositional change of the resulting copolymer based on the conventional changes experienced in the chain reactor or where there are chemically distinct sites in the catalyst entity making the copolymer is present. Allowed in the definition.

Applicants have found that certain metallocene catalyst systems can be used to polymerize propylene statistical copolymers with properties that are highly desirable for conversion to various products. In general, these resins are isotactic polypropylene statistical copolymers, which use propylene and one or more alpha-olefins. In the present application, the term isotactic refers to at least about 90% mmmm pentad as measured by nuclear magnetic resonance (NMR), wherein m is mesodiad and (m is two different consecutive monomer units (dia D), preferably from about 94 to about 98% mmmm pentad, most preferably from about 95 to about 97% mmmm pentad.

Preparation of Resin

The polypropylene copolymer of the present invention is preferably prepared using a supported metallocene catalyst. The copolymer can be prepared in a fluidized or stirred phase gas phase reactor, a tank or loop slurry or bulk liquid phase reactor, or other processes conventionally used for the polymerization of polypropylene. Preferred are a series of bulk liquid boiling pool reactors.

Certain metallocene-type catalysts known to be useful for preparing isotactic olefin polymers are described, for example, in European Patent Application Nos. 485 820, 485 821, 485 822 and 485 823 and Wellborn, for example in Winter et al. US Patent No. 5,017,867 to Welborn. These publications are cited in this application as US patent practice.

Various publications describe the use of the catalyst system on the support medium and the use of the resulting supported catalyst. This includes Chang, U.S. Pat. 5,077,255, 5,124,418 and 4,701,432. All of these are incorporated herein by reference in US patent practice.

Special information regarding the use of support techniques for metallocene type catalysts for use in the preparation of propylene alpha-olefin polymers is disclosed in US Pat. 5,240,894. The catalyst used in the examples below is used for bulk liquid phase polymerization, but commercially available catalysts may also be used in other processes, including, for example, gas phase and slurry processes.

The resins prepared by the processes and catalysts referred to above may have an alpha-olefin comonomer in the range of about 0.2 mol% to about 6 mol%. With at least 6 mol% comonomers, the resulting resins can produce extruded profiles, or molded articles, having too low melting or softening points in most desirable applications. At less than 0.2 mol% comonomers, the flexural modulus becomes too high, creating a product that can be too stiff in most applications. In a more preferred embodiment, the alpha-olefin comonomer is present in the range of about 0.4 to about 3.5 mole percent. In the most preferred embodiment, the alpha-olefin is present in the range of about 0.5 to about 3 mole percent. In the most preferred embodiment, the alpha-olefin is present in the range of about 1 to about 3 mole percent.

In one preferred embodiment, the catalyst system comprises a silicone crosslinked bis (substituted 2-methyl-indenyl) zirconium dichloride or derivatives thereof, methyl alumoxane and an inorganic support. In a more preferred embodiment, dimethyl silyl bis (2-methyl-benzindenyl) zirconium dichloride is the best metallocene. This preferred catalyst system is used to prepare the propylene-ethylene and propylene-hexene resins used in the films, the physical properties of which are shown in Table I below. However, it would be possible to copolymerize any alpha-olefin having 2 to 20 carbon atoms using these catalysts and similar catalyst systems.

Further details regarding the preparation of catalyst systems and the preparation of resins are provided in the examples below.

Characteristics of the resin

The polymers of the present invention are substantially isotactic in nature. The polymer has a Mw / Mn (weight average molecular weight / number average molecular weight) of 5 or less, preferably 3.5 or less, more preferably 3.2 or less, most preferably 3.0 or less and most preferably 2.5 or less (molecular weight distribution MWD) It will be common to have a narrow molecular weight distribution characterized by. Mw / Mn (MWD) is determined by gel permeation chromatography (GPC) as well as molecular weight. This technique is well known. This technique is also described in co-pending US patent application Ser. No. 08 / 164,520, which is incorporated herein by reference in its US patent practice. The polymers of the present invention will exhibit a melting point in the range of about 100 ° C. to about 145 ° C., more preferably in the range of about 110 ° C. to about 135 ° C., and most preferably in the range of about 115 ° C. to about 135 ° C.

An important criterion for products made from these resins is whether they comply with food legislation, and this compliance is usually directly affected by the extractable amount of the product made with the resin. The U.S. Food and Drug Administration (FDA) standard (21 CFR §177.1520) uses the n-hexane reflux procedure, with the maximum extractable amount of the product of the present invention being less than about 5 weight percent, preferably less than about 4 weight percent, most Preferably less than about 3 weight percent is expected.

Useful melt flow rates of the polymers of the invention are in the range of about 0.1 to about 5000 dg / min. In a preferred embodiment, the melt fluidity is in the range of about 0.5 to about 200 dg / min. In the most preferred embodiment, the melt flow rate is in the range of about 1 to about 100 dg / min. Melt flow rate is measured by ASTM D-1238 Condition L.

Manufacture of films, tubes or sheets

The film can be prepared by any technique known to one of ordinary skill in the art. For example, both annular dies and blown films made by air cooling, or cast films using slot dies and chill chills, are acceptable techniques. Oriented films can be prepared by post-extruder manipulation of the blown film via heating and orientation, or by tentering techniques after longitudinal stretching of the extruded sheet. The film is generally in the range of about 0.2 to about 10 mils (5.08 to 254 μm).

The sheet may be produced by extruding a substantially flat profile from the die onto a chill roll, or alternatively by calendaring. The thickness of the sheet is generally thought to be 10 mils to about 100 mils (254 microns to 2540 microns), but may be substantially thicker than this. Test films or sheets can also be produced by compression molding techniques.

The tube can be obtained by profile extrusion. For use in medical applications, the tubes are typically in the range of about 0.31 cm (1/8 ") outer diameter to about 2.54 cm (1") outer diameter, and range from about 254 μm (10 mils) to about 0.5 cm (200 mils) It will have a wall thickness within the range.

Films made from the polymers of the invention can be used to package foods such as meat and snacks, for example. Such films can also be used to protect and display clothing.

The container can be manufactured using a sheet made of the polymer of an embodiment of the present invention. This container may be manufactured by thermoforming, solid state pressing, stamping, and other molding techniques may be used for foods such as meat or dairy products. Sheets may also be made to cover floors or walls or other surfaces.

Tubes made from the products of the present invention can be used for medical, food or other uses that will be apparent to those skilled in the art.

Molded products and extrusion profiles

Molded articles can be made by any technique known to those of ordinary skill in the art. For example, the molded article can be assembled by injection molding, blow molding, extrusion blow molding, rotational molding and foam molding. Molded parts have a thickness of at least 500 μm (20 mils) in most cases. For molded articles, the thickness of the cross section of the article will generally range from about 508 μm to about 2.5 cm.

Molded products for health protection devices, such as syringes, are also contemplated.

Table I below shows the physical property data of the propylene-ethylene copolymer film and the propylene-hexene copolymer film in accordance with the description of the present application. Film tests are used as an indicator of molded product or extruded profile performance.

The data in Table I below show that the other physical / mechanical properties of the products made with the resins of the present invention also improved as compared to the propylene copolymers of lower alpha-olefins, as mentioned above. It is readily apparent from the data in Table I that films made with hexene-1 copolymers exhibit relatively high low temperature flow (creep) resistance as indicated by their R _ma values (R _ma is defined below). Films made from propylene-ethylene copolymers, on the other hand, exhibit the expected relatively poor low temperature flow resistance. The above-mentioned differences (both promoted by metallocenes) between the propylene hexene-1 and propylene-ethylene copolymers tested can also be expected in the propylene copolymers of other HAOs as compared to the propylene-ethylene copolymers.

Properties of Extruded Profiles Made of Molded Products and Resins

The resins mentioned above will exhibit excellent properties when prepared from molded articles as compared to propylene α-olefin resins using commercially available Ziegler-Natta catalysts or metallocene catalysts with α-olefins having up to 4 carbon atoms.

Prospective Examples 5-8 suggest that the molded part will exhibit improved physical properties in the foregoing comparison.

R _ma measurement

A useful parameter to characterize cold flow resistance or creep resistance is a value known as time delayed compliance (TDC). In the present application, TDC is defined as the amount of strain divided by stress, the amount of strain force found in the product under a specified stress for a defined time. The prescribed time should be chosen such that the time delayed compliance at that time is at least twice the initial compliance of the material. Those skilled in the art will appreciate that the stress should be less than the yield strength of the specimen.

Techniques useful for evaluating the stepwise change in properties between the propylene-HA0 copolymer and the propylene-ethylene copolymer have been developed (all with metallocene catalysts).

For films, molded articles, tubes, sheets and similar products and other products made therefrom, the technique uses the ratio of the TDC of the propylene-ethylene copolymer to the TDC of the propylene-HAO copolymer.

This ratio is represented by the symbol R _ma , as follows:

R _ma =

In the above formula, the resin for making each product is selected such that the tensile modulus of each product is substantially the same as that of the other products.

In measuring R _ma , it is important that substantially all of the variables affecting the properties of the product in both the numerator and denominator of the ratio are equal.

These variables include but are not limited to the following variables:

For resins: Molecular weight should change below 10%

For assembled products: assembly conditions and techniques; Dimensions of the test specimen; Post-assembly treatment; Blend Ingredients or Additives

Those skilled in the art will think that the comonomer content (either HAO or ethylene) can be varied to obtain a nearly identical tensile modulus in both propylene-HAO and propylene-ethylene copolymerization.

By choosing the same tensile modulus of the product for both the numerator and the denominator, the comparison can be made at a certain degree of flexibility of the product. Products made with the isotactic propylene-HAO copolymers of the present invention will have a R _ma greater than about 1.1, which means a significantly improved low temperature flow resistance compared to the isotactic propylene-ethylene copolymer. If the R _ma of the article is at least about 1.1, blends of olefin polymers in which at least one polymer is a statistical isotactic propylene-HAO copolymer can also be considered. Possible blend materials include, but are not limited to, the following compounds; Ethylene copolymers of ethylene unsaturated esters, copolymers of polyethylene homopolymers and α-olefins, polypropylene homopolymers and copolymers, ethylene propylene rubber (EP), ethylene, propylene, diene monomer elastomers (EPDM), styrene- Butadiene-styrene (SBS), lubricants, antistatic agents, colorants, antioxidants, stabilizers, fillers, and additives such as caCO ₃ , additives such as talc and glass fibers, and other additives well known to those skilled in the art.

R _ma 1.1 or higher suggests that the product will exhibit significantly better low temperature flow resistance than products made from propylene-ethylene copolymers. The larger the number of R _ma, the better the compliance of the propylene-HAO copolymer compared to the propylene-ethylene based products. In a preferred embodiment, R _ma is at least 1.2. In a more preferred aspect, R _ma is at least 1.3.

In addition to better low temperature flow resistance, these propylene-HAO copolymers exhibit other improved physical properties. Table I below demonstrates that the tensile strength and impact strength of the propylene-HAO copolymers, for example, have been significantly improved by comparing the physical properties of the propylene copolymer of ethylene and the propylene copolymer of HAO.

A further fact that the class of propylene-HAO copolymers is distinguished from the class of propylene-ethylene or propylene-butene copolymers is found in the reaction of the melting point of the copolymer when incorporating comonomers. Illustrating this in FIG. I, it can be seen that the melting point drop when incorporating a given molar comonomer is about twice as high in the propylene-HAO copolymer than in the ethylene and butene resin classes of the propylene copolymer.

Also contemplated are blends of olefin polymers including the statistical propylene HAO copolymers of the present invention and other materials such as additives or other polyolefins.

Example 1

Preparation of Metallocene Catalyst

Silica supported metallocene catalysts are prepared according to the teachings of USSN 07 / 885,170, using dimethyl silyl, bis (2 methyl, 4,5 benzinyl) zirconium dichloride as the metallocene. Catalyst formulations are described in Organic Metallics, v 13, No. 3, 1994, p. 954-963, 400 g of silica (Davison 948), 10 g of metallocene and 3 L of methyl alumoxane (MAO) 3 L in toluene solution. Recover approximately 600 g of the final catalyst system. The catalyst is prepolymerized at a rate of about 15 ° C. at a ratio of 1 weight of ethylene per weight of catalyst system. Ethylene is added for 1.5 hours to ensure low reaction rates.

Example 2

Preparation of Propylene-Ethylene Copolymer

About 15 g of ethylene and 550 g of propylene are added to an autoclave maintained at 30 ° C. After allowing equilibration time, 0.2 g of the prepolymerized catalyst of Example 1 is added to the reactor and the temperature is raised to 50 ° C. for several minutes. Immediate response was observed. The reactions are stopped after 30 minutes to limit the conversion content of ethylene to make their concentration almost constant in the reaction medium during the reaction period. A total of 114 g of propylene-ethylene statistical copolymer was obtained. The weight average molecular weight is 184,000, as measured by size exclusion chromatography, its ethylene content (measured by FTIR) is 3.3% by weight, and the peak melting point is 121 ° C.

Example 3

Preparation of Propylene-Hexene Copolymer

To the autoclave of Example 2 is added 550 g of propylene and 34 g of hexene-1. The catalyst of Example 1 was added (0.2 g) and the temperature was adjusted as in Example 2. Since the relative reactivity of propylene and hexene-1 is about the same under these conditions, the reaction is allowed for a total of 2 hours. A total of 222 g of propylene-hexene statistical copolymer was obtained. The weight average molecular weight as measured by size exclusion chromatography is 204,000, its hexene-1 content is 2.9% by weight (measured by FTIR), and the peak melting point is 126 ° C.

Example 4

Preparation of Propylene-1-octene Copolymer (Expected Example)

2550 g of propylene are added to the autoclave of Example 2 with about 45 g of 1-octene equivalent to the molar amount of Example 3. The catalyst of Example 1 is added and the temperature is adjusted as in Example 2. Since the reactivity of propylene and 1-octene is about the same under these conditions, the reaction is allowed for a total of 2-3 hours. At least 200 g of propylene-octene statistical copolymer can be expected. The weight average molecular weight is at least 200,000 as measured by size exclusion chromatography. The octene-1 content is expected to be 2.0-4% by weight (measured by FTIR) and the peak melting point is in the range of 125-135 ° C.

Examples 5 and 6

Film manufacturing and testing

This example illustrates the preparation of a film from the copolymers of Examples 2 and 3, including detailed procedures and characterization for making the film. The data is summarized in Table I below. (Steps and tests for making films with the resins prepared in Example 4 will follow the same procedure)

9.2 g of the granular copolymer is compression molded between Mylar ^R sheets to an area of 15 cm x 15 cm and a thickness of 0.5 mm to prepare a film of the copolymer to be identified. The molding procedure is as follows: 1) access the platen (adjusted to a temperature of 200 ° C.) until the mylar sheet is in contact with the sample; Hold for 1 minute without application pressure; 2) increase the tightening force to 10 tons and hold for 1 minute; 3) increase the tightening force to 40 tons and hold for 2 minutes; 4) Release the tightening force and allow the film (still between mylar sheets) to cool in a room temperature water bath. After the film is conditioned for 6 days at room temperature, the dumbbell-shaped sample is die cut from the film.

Tensile properties of the resulting samples are measured on a Zwick REL 2051 tensile tester at a temperature of 25 ± 2 ° C. for standard tensile properties and adhere to procedure DIN 53457 (1987). To measure time delayed compliance, the tensile specimen is placed in the tester as in the standard tensile test. Apply the pre-measured load and record the sample elongation as a function of time. Choose a load where 50 to 60% of the specimens experience yielding (for the samples shown herein, a load of 11.7 MPa is chosen). The sample elongation recorded at 480 seconds after the initial application of the load is selected as a measure of cold flowability for a particular load and the strain force divided by the applied stress is referred to as "time delayed compliance".

The evaluation results are shown in Table I below.

R _ma measurement

Tensile properties of the parts made from the resins of Examples 2-4 are measured in a tensile tester at a temperature of 25 ± 2 ° C. for standard tensile properties. To measure time delayed compliance, the tensile specimen is placed in the tester as in the standard tensile test. Apply the pre-measured load and record the elongation of the specimen as a function of time. The same load is selected for all parts to be tested by the definition of R _ma , where the two parts have approximately the same modulus. The elongation of the sample, recorded at 480 seconds after the initial application of the load, is selected as a measure of cold flowability for a particular load, and the strain force divided by the applied stress is referred to as "time-delayed compliance".

Example 7 (Expected Example)

Molded product manufacturing and testing

The following examples are used to compare propylene polymers prepared with conventional Ziegler-Natta catalysts or by using propylene copolymers of propylene and alpha-olefins having up to 4 carbon atoms, prepared with metallocene catalyst systems and using these copolymers. When compared to the assembled TPO, enumerate the expected improvement in the molded part performance of the propylene copolymer or TPO assembled using the copolymer of the present invention.

Mechanical properties are evaluated by the following test:

(1) Melt Flow Rate-ASTM D-1238, Condition L.

(2) Flexural modulus, secant-ASTM D-790.

(3) Shore D Hardness-ASTM D-2240.

(4) Notched Izod-ASTM D-256.

(5) Tensile Properties-ASTM D-638.

(6) Brittleness temperature-ASTM D-746.

(7) Bicket Softening Temperature-ASTM D-1525.

(8) Shrinkage-ASTM D-995.

(9) Density-ASTM D-2240.

(10) Flexing Beam Resilience-A 5 inch by 0.5 inch by 0.125 inch specimen secured with 1/2 inch mandrel is bent at an angle of 90 ° and held for 3 seconds. After release, the specimens were recovered without stress for 2 minutes. Next, measure the deviation from the vertical and record it as resilience. 0 ° will produce a complete recovery and "perfect" resilience.

Samples are injection molded into standard parts in a Van Dorn injection molding press for various ASTM tests and then selected mechanical properties are tested.

Although the invention has been described in considerable detail with reference to certain preferred embodiments of the invention, other variations are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred forms contained therein.

polymer Copolymer of Example 2 Copolymer of Example 3 Tensile Modulus (MPa) 583 604 TDC (Load 11.8 Mpa; Time 480 sec) 5.3 3.15 R _ma 1.0 1.68 Tensile Strength (Ultimate-MPa) 38.0 43.7 Dart Impact Strength (Nm / mm) 12.5 14.0 DSC peak melting point (° C) 121 126

Claims (11)

A product composed of an isotactic copolymer of propylene and at least one α-olefin having 5 or more carbon atoms, The α-olefin is present in the copolymer in the range of 0.2 to 6 mol%, based on the total moles of monomers in the copolymer, the copolymer has Mw / Mn ≦ 5, and the copolymer is 100 ° C. to 145 Has a peak melting point in the range of < RTI ID = 0.0 > A product having R _ma of at least 1.1, preferably 1.2 and more preferably 1.3 of a product made from said copolymer. The method of claim 1, The article also comprises a second polyolefin, wherein the second polyolefin is selected from the crowd consisting of polyethylene, polypropylene and olefinic elastomers. The method of claim 1, Wherein said α-olefin is selected from the group consisting of 1-pentene, 4-methyl-1-pentene, 1-hexene and 1-octene, and wherein said α-olefin is present in the range of 0.5 to 3 mol%. The method of claim 1, Wherein said propylene copolymer is prepared using a metallocene catalyst system and said copolymer has Mw / Mn < 3.5. The method of claim 4, wherein Wherein said metallocene catalyst system contains a silicone crosslinked bis (substituted 2-methyl-indenyl) zirconium dichloride and methylalumoxane activator. The method of claim 1, The article also comprises an additional comonomer, wherein said copolymer is selected from the group of α-olefins having 2 to 20 carbon atoms. The method of claim 1, Wherein said product is one of a film, molded part, tube, or sheet. A product comprising at least one first isotactic propylene α-olefin copolymer, wherein the α-olefin is selected from the group consisting of 1-pentene, 4-methyl-1-pentene, 1-hexene and 1-octene; Polymerizing the propylene α-olefin copolymer using a metallocene-alumoxane catalyst system, wherein the metallocene is dimethyl silyl bis (2-methyl-benzindenyl) zirconium dichloride; The α-olefin is present in the range of 1 to 3 mol% based on the total moles of the propylene α-olefin copolymer; The copolymer has Mw / Mn ≦ 3; The copolymer has a melting point in the range of 115 ° C to 135 ° C. A film comprising an isotactic copolymer of propylene, a first α-olefin and a second comonomer, wherein the first α-olefin is selected from 1-pentene, 4-methyl-1-pentene, 1-hexene and 1-octene. Selected from the composed crowd; The second comonomer is selected from the group consisting of ethylene, 1-butene, 4-methyl 1-pentene, 1-hexene and 1-octene; The total amount of the first α-olefin and the second comonomer in the copolymer is 0.5 to 3 mol% based on the total moles of monomers of the copolymer in the first α-olefin and the second comonomer. Exists in the range of; The copolymer has Mw / Mn ≦ 3; The film made from the copolymer has an extractable amount of less than 3% by weight; _Wherein said film has a R _{ma of} at least 1.2. A molded article comprising a propylene α-olefin copolymer, wherein the α-olefin is selected from the group consisting of 1-pentene, 1-hexene and 1-octene; Polymerizing the propylene α-olefin copolymer using a metallocene catalyst system, wherein the metallocene is dimethyl silyl bis (2-methyl-benzinyl) zirconium dichloride; The α-olefin is present in the range of 1-2 mol%; The copolymer has Mw / Mn ≦ 3; The copolymer has a melting point in the range of 115 ° C to 135 ° C; The copolymer is isotactic; Molded articles made from the propylene α-olefin copolymers have an extractable amount of less than 3% by weight; Molded _article wherein R _ma of said molded _article exceeds 1.3. The method of claim 10, Wherein said product is selected from the crowd consisting of food containers, medical equipment, syringes and passenger car parts.