EP0750650A1 - Melanges polymeres, films et articles composes de ces derniers - Google Patents

Melanges polymeres, films et articles composes de ces derniers

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Publication number
EP0750650A1
EP0750650A1 EP95914069A EP95914069A EP0750650A1 EP 0750650 A1 EP0750650 A1 EP 0750650A1 EP 95914069 A EP95914069 A EP 95914069A EP 95914069 A EP95914069 A EP 95914069A EP 0750650 A1 EP0750650 A1 EP 0750650A1
Authority
EP
European Patent Office
Prior art keywords
hot tack
polymer
component
weight percent
polymer blend
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP95914069A
Other languages
German (de)
English (en)
Inventor
Prasadarao Meka
James Mcleod Farley
Donna Sue Davis
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ExxonMobil Chemical Patents Inc
Original Assignee
Exxon Chemical Patents Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Exxon Chemical Patents Inc filed Critical Exxon Chemical Patents Inc
Publication of EP0750650A1 publication Critical patent/EP0750650A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J123/00—Adhesives based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Adhesives based on derivatives of such polymers
    • C09J123/02—Adhesives based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Adhesives based on derivatives of such polymers not modified by chemical after-treatment
    • C09J123/04—Homopolymers or copolymers of ethene
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J123/00—Adhesives based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Adhesives based on derivatives of such polymers
    • C09J123/02—Adhesives based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Adhesives based on derivatives of such polymers not modified by chemical after-treatment
    • C09J123/04—Homopolymers or copolymers of ethene
    • C09J123/08—Copolymers of ethene
    • C09J123/0807—Copolymers of ethene with unsaturated hydrocarbons only containing more than three carbon atoms
    • C09J123/0815—Copolymers of ethene with aliphatic 1-olefins
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2666/00—Composition of polymers characterized by a further compound in the blend, being organic macromolecular compounds, natural resins, waxes or and bituminous materials, non-macromolecular organic substances, inorganic substances or characterized by their function in the composition
    • C08L2666/02—Organic macromolecular compounds, natural resins, waxes or and bituminous materials
    • C08L2666/04—Macromolecular compounds according to groups C08L7/00 - C08L49/00, or C08L55/00 - C08L57/00; Derivatives thereof

Definitions

  • the present invention relates to heat sealable films and articles.
  • the invention relates to a blend of polymers one of which has a narrow molecular weight distribution and narrow composition distribution, the other being a high pressure low density polymer.
  • the blends of the invention exhibit excellent hot tack, heat sealing and other physical properties.
  • the blends may be used to make films, bags, pouches, tubs, trays, lids, packages, containers and other articles employing a heat seal.
  • plastic parts usefully employed in machines and toys may be constructed by joining together two individual plastic pieces by heating one or both of the plastic pieces, pressing them together, and then, allowing them to cool.
  • Heat sealing is very important in packaging applications.
  • Packages formed by a heat seal provide for the efficient transportation of a consumer item within the package, provide a display of the consumer item that promotes sales, and, in the food industry, the packaging is employed to preserve the freshness of the consumer item.
  • a manufacturer of packages or any other like article requiring a seal also requires excellent processibility.
  • polymers are used to form articles, which include packages, that may be joined together or sealed by the application of heat and/or pressure.
  • articles which include packages, that may be joined together or sealed by the application of heat and/or pressure.
  • Polymers or blends of polymers used to make the articles are selected for use because they provide a strong seal, which is easily and rapidly formed by a single short application of heat and/or pressure.
  • the entire heat sealed article is constructed from the same polymer or a blend of polymers or by the coextrusion of the same or different polymers. More often, the article is constructed of various areas or layers of different materials, and polymers which provide good heat sealing properties are utilized only in areas, or layers, where heat sealing will ultimately be necessary.
  • This type of construction is employed because the articles, for instance multilayer films, should have desirable physical and mechanical properties such as clarity, strength, resistance to puncture and tearing, in addition to heat sealing properties, and should be easily processed by high speed equipment. Many plastic materials are known to possess good physical and mechanical properties but often do not also possess good heat sealing properties.
  • a polymer composition's heat seal initiation temperature This is the temperature to which the polymer composition must be heated before it will usefully bond to itself under stress and/or strain.
  • Relatively low heat seal initiation temperatures are desirable in commercial heat sealing equipment. The lower temperatures provide for higher production rates of the packages on the equipment because the polymer does not need to be heated to as great a temperature to make the seal. Also, cooling of the seal to attain adequate strength will be faster. Qualitatively, every 10°C decrease in seal initiation temperature will result in 30% improvement in line speed productivity.
  • ethylene vinyl acetate (EVA) and ethylene methyl acrylate (EMA) copolymers have low seal initiation temperatures but these high pressure low density copolymers have poor hot tack strength.
  • LLDPE linear low density polyethylene
  • Hot tack is the capability of a heat seal to hold together, when pulled apart, immediately before thoroughly quenching the seal.
  • Hot tack strength is the measure of the maximum stress that can be applied before the seal fails. This is different from seal strength which is a measure of the strength of a seal after the seal has cooled.
  • Hot tack strength is the ability of a heat seal to hold together immediately after sealing, before the seal is cooled. Hot tack properties are important in packaging applications. A high hot tack strength at lower temperatures allows packaging manufacturers to increase line speeds.
  • Hot tack is also the constraining factor in determining the weight of material that can be packaged in a form-fill seal machine.
  • High hot tack is also advantageous in cases where bulky products tend to resist package edge sealing, where vibration or cutting takes place while the seal is hot, or where packages are filled hot.
  • VFFS or HFFS process a polymer composition is formed into a flexible pouch and almost immediately filled with the contents to be packaged and then the pouch is sealed closed. Since it is often difficult or impossible to maintain commercial sealing equipment at exactly the same sealing temperature throughout a commercial run, a broader range of sealing temperatures would make it easier to assure that all heat seals are made with acceptable strength.
  • the blend of polymers of the invention generally include a first polymer, component A, which has a narrow molecular weight distribution and composition distribution and a second polymer, component B, which is a high pressure polyethylene homopolymer or copolymer.
  • component A comprises between about 10 to 50 weight percent of the total weight percent polymer blend and component B comprises between about 50 to about 90 weight percent of the total weight percent of the polymer blend of the invention.
  • the polymer blend of the invention is useful as a film layer in an article of manufacture, particularly in a heat sealable article where the film layer is a seal layer.
  • Figure 1 is a graph of the relationship between the hot tack strength versus weight percent of component A for samples numbered EX. 1-9.
  • Figure 2 is a graph of the relationship between the hot tack strength versus weight percent of component A for samples numbered EX. 1, 10-12.
  • Figure 3 is a graph of the relationship between the hot tack strength versus weight percent of component A for samples numbered EX. 1, 13-15.
  • Figure 4 is a graph of the relationship between the hot tack strength versus weight percent of component A for samples numbered EX. 9, 16-18.
  • Figure 5 is a graph of the relationship between the hot tack strength versus weight percent of component A for samples numbered EX. 9, 16, 19-20.
  • Figure 6 is a graph of the relationship between the hot tack strength versus weight percent of component A for samples numbered EX. 12, 21-23.
  • Figure 7 is a graph of the relationship between the hot tack strength versus weight percent of component A for samples numbered EX. 9, 21, 24-25.
  • Figure 8 is a graph of the relationship between the hot tack strength versus temperature for samples numbered EX. 1, 10-12.
  • Figure 9 is a graph of the relationship between the hot tack strength versus temperature comparing the inventive blends with a prior art blend.
  • the invention concerns a blend of a narrow molecular weight distribution (NMWD) and a narrow composition distribution (NCD) polymer, component A, and a high pressure ethylene homopolymer or copolymer, component B, their production and applications for their use.
  • NMWD narrow molecular weight distribution
  • NCD narrow composition distribution
  • the polymer blend of the invention has unique properties which make them particularly well suited for use in polymeric films. These films are very useful in applications requiring heat sealability.
  • the line-speed (how fast a package can be made) is limited by the hot tack strength ofa particular film.
  • High hot tack strength during a wider range of lower sealing temperatures significantly increases line speeds and reduces the risk of "burn-through" as well as damage to temperature sensitive packaged goods.
  • Prior art blends typically require higher sealing temperatures. Therefore, dwell times are longer, line speeds are slower and the likelihood of "burn-through" is increased.
  • An added advantage of the inventive blends is a broader hot tack temperature window or range where the hot tack strength is commercially attractive.
  • the inventive blends allow for wider tolerances in packaging operations (seal bar temperature, dwell time, line speed, etc.) resulting in a more economical packaging operation.
  • Polymer Component A, of this invention can be produced using metallocene catalyst systems in a polymerization process in gas, slurry solution or high pressure phase.
  • the process for polymerizing involves the polymerization of one or more of the alpha-olefin monomers having from 2 to 20 carbon atoms, preferably 2-15 carbon atoms.
  • the invention is particularly well suited to the copolymerization reactions involving the polymerization of one or more of the monomers, for example alpha-olefin monomers of ethylene, propylene, butene-1, pentene-1, 4- methylpentene-1, hexene-1, octene-1, decene-1 and cyclic olefins such as styrene.
  • Other monomers can include polar vinyl, dienes, norbornene, acetylene and aldehyde monomers.
  • a copolymer of ethylene and at least one alpha- olefin comonomer having from 3 to 15 carbon atoms is utilized in the polymer blends of the invention.
  • metallicocene is defined to contain one or more cyclopentadienyl moiety in combination with a transition metal.
  • the metallocene can be substituted with principally hydrocarbyl substituent(s) but not to exclude a germanium, a phosphorous, a silicon or a nitrogen atom containing radical or unsubstituted or bridged or unbridged or any combination.
  • Various forms of the catalyst system of the metallocene type may be used in the polymerization process of this invention. Exemplary of the development of these metallocene catalysts for the polymerization of olefins is found in U.S. Patent Nos.
  • All the catalyst systems described above may be, optionally, prepolymerized or used in conjunction with an additive or scavenging component to enhance catalytic productivity.
  • a key characteristic of polymer Component A of the present invention is its composition distribution (CD).
  • CD composition distribution
  • the composition distribution of a copolymer relates to the uniformity of distribution of comonomer among the molecules of the copolymer.
  • Metallocene catalysts are known to incorporate comonomer very evenly among the polymer molecules they produce.
  • copolymers produced from a catalyst system having a single metallocene component have a very narrow composition distribution - most of the polymer molecules will have roughly the same comonomer content.
  • Ziegler-Natta catalysts on the other hand generally yield copolymers having a considerably broader composition distribution. Comonomer inclusion will vary widely among the polymer molecules.
  • CDBI Composition Distribution Breadth Index
  • a solubility distribution curve is first generated for the copolymer. This may be accomplished using data acquired from the TREF technique described above. This solubility distribution curve is a plot of the weight fraction of the copolymer that is solubilized as a function of temperature. This is converted to a weight fraction versus composition distribution curve. For the purpose of simplifying the correlation of composition with elution temperature all fractions are assumed to have a Mn > 15,000, where Mn is the number average molecular weight of the fraction. Low weight fractions generally represent a trivial portion of the polymer, component A, of the present invention. The remainder of this description and the appended claims maintain this convention of assuming all fractions have Mn > 15,000 in the CDBI measurement.
  • the CDBI is determined by establishing what weight percent of the sample has a comonomer content within 25% each side of the median comonomer content. Further details of determining the CDBI ofa copolymer are known to those skilled in the art. See, for example, PCT Patent Application WO 93/03093, published February 18, 1993.
  • the polymers of the present invention have CDBI's generally in the range of 50-98%, usually in the range of 60-98% and most typically in the range of 65- 95%. Obviously, higher or lower CDBI's may be obtained using other catalyst systems with changes in the operating conditions of the process employed.
  • MWD Molecular Weight Distribution
  • Mw weight average molecular weight
  • Mn number average molecular weight
  • the molecular weight distribution of a polymer can be determined with a Waters Gel Permeation Chromatograph equipped with Ultrastyrogel columns and a refractive index detector.
  • the operating temperature of the instrument was set at 145°C
  • the eluting solvent was trichlorobenzene
  • the calibration standards included sixteen polystyrenes of precisely known molecular weight, ranging from a molecular weight of 500 to a molecular weight of 5.2 million, and a polyethylene standard, NBS 1475.
  • the MWD of the polymer component A of this invention are termed "narrow".
  • “narrow” MWD means a Mw/Mn less than about 3.4, preferably less than or equal to 3, more preferably less than 2.5.
  • the MI of the polymers of the invention are generally in the range of about 0.1 dg min to about 1000 dg/min, preferably about 0.2 dg/min to about 300 dg min, more preferably about 0.3 to about 200 dg/min and most preferably about 0.5 dg/min to about 100 dg min.
  • Contemplated densities of component A of the invention are in the range of 0.85 to 0.96 g/cm 3 , preferably 0.87 to 0.940 g/cm 3 , more preferably 0.88 to about 0.935 g/cm 3 .
  • the density of component A is in the range of 0.900 to 0.915 g/cm 3 , 0.915 to 0.940 g/cm 3 , 0.88 to 0.9 g/cm 3 and greater than 0.940 g/cm 3 to 0.96 g cm 3 .
  • a particular attribute of Component A polymers is their very low level of extractable components.
  • the extractable levels for the polymers of Component A are in the range of between 5.5% to below 0.1%, preferably less than 3%, more preferably less than 2% and most preferably less than 1%.
  • the extractable level of films made from polymer component A is measured in accordance with the process detailed in 21 CFR 177.1520(d)(3)(ii).
  • component A can comprise a blend of component A polymers, which can be prepared by blending the desired components in the desired proportion using conventional blending techniques and apparatus, such as, for example, screw-type extruders, Banbury mixers, and the like.
  • the blends may be made by direct polymerization, without isolation of the blend components, using, for example, two or more catalysts in one reactor, or by using a single catalyst and two or more reactors in series or parallel.
  • Polymer Component B of the invention is very well known in the art and may be prepared by free radical initiators, typically in a tubular reactor under high pressure, peroxide being the preferred initiator.
  • free radical initiators typically in a tubular reactor under high pressure
  • peroxide being the preferred initiator.
  • U.S. Patent No. 4,719,193, incorporated herein by reference discloses a method of preparing polymer component B .
  • the molecular weight of the component B of the invention is in the range of 60,000 to 200,000
  • the melt index (MI) is from 0.2 to 50
  • the density ranges from 0.91 to 0.94 g/cm 3 , typical of linear low density polyethylene homopolymer (LDPE) and a linear low density copolymer and the like.
  • high pressure polyethylene homopolymer or copolymer is defined as a polyethylene homopolymer having a density less than 0.940 g/cm 3 or an ethylene copolymer of ethylene and an ethylenically unsaturated carboxylic acid ester or vinyl acetate.
  • Preferred ethylenically unsaturated acrylic acid esters include, for example, methyl acrylate, butyl acrylate, and ethyl acrylate.
  • a preferred monomer is vinyl acetate.
  • Ethylene methyl acrylate copolymers suitable for use in this invention are available from Exxon Chemical Company, Houston, Texas under the trademark OptemaTM.
  • Ethylene vinyl acetate copolymers suitable for use in the invention are also available from Exxon Chemical Company, Houston, Texas under the trademark ESCORENETM.
  • the B component of the polymer blend of the invention may be a blend of different prior art polymers, each differing in one or more of: molecular weight, MWD, comonomer type and content, density, MI and CD.
  • the polymer blend of the invention herein referred to as, the "A-B blend" may be used to form articles with particularly desirable heat sealing properties.
  • the A-B blend may be processed into films which possess particularly desirable heat sealing characteristics.
  • the A-B blend may be used to form films which are in turn formed into bags or pouches by heat sealing techniques known in the art.
  • the heat sealable film may also be used as package sealing material, for example, the film may be placed over the opening ofa container, and then secured to the container by the application of heat. This technique may be used to seal perishable items, such as food, into paper, plastic, glass, ceramic or metallic containers.
  • the articles of the invention may comprise other materials, especially in portions of the article not utilized for heat sealing.
  • the language "formed from” is intended to mean “comprising.”
  • all articles or portions of articles described may also be constructed to consist essentially of the inventive A-B blends.
  • the heat sealing portion of any article described herein may consist essentially of the inventive A-B blend.
  • the blend may have additional components as further described below.
  • the A-B blend of polymers may be formed into films by methods well known in the art.
  • the polymers may be extruded in a molten state through a flat die and then cooled.
  • the polymers may be extruded in a molten state through an annular die and then blown and cooled to form a tubular film.
  • the tubular film may be slit and unfolded to form a flat film.
  • the films of the invention may be unoriented, uniaxially oriented or biaxially oriented.
  • the films of the invention may be single layer or multiple layer films.
  • the multiple layer films may comprise of one or more layers formed from the A-B polymer blend.
  • the films may also have one or more additional layers formed from other materials such as other polymers, polypropylene (PP), polyester, LDPE, HDPE, polyamide, polycarbonates, EVA and EVOH for instance, metal foils, paper and the like.
  • Multiple layer films may be formed by methods well known in the art. If all layers are polymers, the polymers may be coextruded through a coextrusion feedblock and die assembly to yield a film with two or more layers adhered together but differing in composition. Multiple layer films may also be formed by extrusion coating whereby a substrate material is contacted with the hot molten polymer as the polymer exits then die. Extrusion coating is particularly useful when the A-B blend heat seal layer is to be applied to substrates that are woven or knitted from natural or synthetic fibers or yams, e.g., textiles, or substrates made from non-polymer materials such as glass, ceramic, paper or metal.
  • Multiple layer films may also be formed by combining two or more single layer films prepared as described above.
  • the two layers ofa film so formed may be adhered together with an adhesive or by the application of heat and pressure.
  • the heat sealed article may be formed by pressing at least two portions of the article together at a temperature sufficient to soften at least one of the article portions.
  • the article portion which has been softened by heat is formed from the A-B blend of polymers. Although it is sufficient if only one of the article portions being heated and pressed to form a heat seal is formed from the A-B, it is preferable for all article portions directly involved in the heat seal to be formed from the A-B blend. Other portions of the article may be constructed of other materials.
  • Articles of the invention include a sealed container comprising a body and a sealing member secured thereto, wherein the sealing member comprises a seal layer comprising the A-B blend polymers.
  • the body may be constructed of any of a number of different materials such as paper, plastic, glass, ceramics, metals and textiles.
  • the body can be constructed with walls that are impervious to liquids and/or gases or the body may be constructed to allow the passage of liquids and/or gases.
  • the body may also be constructed with one or more portals to allow passage of small items through the body wall or to allow the consumer to inspect the item stored in the container without removing the item from the container.
  • the polymer blend of the invention contains about 10 to about 50 weight percent of polymer Component A, preferably about 20 to about 50 percent, more preferably about 20 to about 40 weight percent, and most preferably about 20 to about 30 weight percent.
  • the polymer blend contains about 50 to about 90 weight percent of polymer component B, preferably about 60 to about 90 weight percent, more preferably about 60 to about 80 weight percent, most preferably about 70 to about 80 weight percent.
  • the first component of the polymer blend of the invention contains about
  • the first polymer preferably 60 to 95 weight percent, more preferably 65 to 90 weight percent, even more preferably 70 to 90 weight percent and most preferably 75 to 90 weight percent.
  • the second component contains about 50 to about 100 weight percent of a high pressure ethylene homopolymer or copolymer, preferably 60 to 95 weight percent, more preferably 65 to 90 weight percent, even more preferably 70 to 90 weight percent and most preferably 75 to 90 weight percent.
  • the polymer blend of the invention or the individual components A and B may also be compounded with various conventional additives known in the art such as, for example, antioxidants, UV stabilizers, pigments, fillers, slip additives, block additives, and the like.
  • Seal initiation temperature is defined as the temperature at which a hot tack strength of 2 N/15 mm is observed.
  • the films of the invention generally have a seal initiation temperature less than about 110°C, preferably less than about 105 C C, more preferably less than about 100°C, and most preferably less than about 95°C.
  • Hot tack strength is measured in N/15mm.
  • Hot tack temperature range or hot tack temperature window is defined as the temperature range where a hot tack strength of ⁇ 2 N/l 5 mm is maintained.
  • the films of the invention have a hot tack strength greater than about 1.5 N/l 5 mm, preferably greater than 2 N/l 5 mm and most preferably greater than 3 N/l 5 mm at a temperature of greater than about 100°C.
  • the films of the invention have a hot tack strength greater than about 1.5 N/l 5 mm, preferably greater than 2 N/l 5 mm and most preferably greater than about 3 N/l 5 mm at a temperature of greater than about 105°C.
  • the films of the invention have a hot tack strength greater than about 1.5 N/l 5 mm, preferably greater than 2 N/l 5 mm and most preferably greater than about 3 N/l 5 mm at a temperature of about 110°C.
  • the films of the invention have a hot tack strength temperature window greater than about 10°C at a hot tack strength greater than or equal to about 2 N/l 5 mm.
  • the hot tack strength temperature range is greater than about 12°C to about 40°C, preferably greater than about 15°C to about 40°C, more preferably greater than about 20°C to about 40°C and most preferably greater than about 25°C to about 30°C at a hot tack strength greater than about 2 N/l 5 mm, preferably greater than about 2.5 N/l 5 mm and most preferably greater than 3 N/l 5mm.
  • the film of the invention has a hot tack strength greater than about 2 N/l 5 mm at a temperature between about 100°C to about 115 °C.
  • the film of the invention has a hot tack strength of greater than about 2.5 N/15 mm at temperature greater than about 100° C.
  • the film of the invention has a hot tack strength greater than 2 N/l 5 mm preferably greater than 2.5 N/l 5 mm, more preferably greater than 3 N/l 5 mm at a temperature of greater than about 80°C or in the range of about 80°C to about 95°C.
  • Sample No. Ul and U2 in Table 1 are prepared using free radical initiation of ethylene under high pressure conditions in a tubular reactor.
  • the reactor temperature range is 149-260°C, and pressure range of 36,000 psig (248,220 kPa) to 45,000 psig (310,275 kPa) and a residence time of 2 s to 30 s.
  • Samples No. U3 in Table 1 is prepared similar to Ul and U2 using free radical initiation and high pressure conditions in a tubular reactor, using vinyl acetate as the comonomer.
  • Sample No. U4 in Table 1 is prepared similar to Ul and U2 using free radical initiation and high pressure conditions in a tubular reactor, with methyl acrylate and acrylic acid as the comonomers.
  • EXAMPLE H Sample No. XI, is prepared using silicon bridged transition metal catalyst.
  • Sample No. XI is prepared using the catalyst mentioned above, and reaction conditions of ethylene pressure of 19000 psig (131,005 kPa), temperature in zone 1 of 137°C, and zone of 5 166°C, butene 9 mole%, and hexene 45 mole%.
  • Sample No. X2 is prepared similar to XI, except the temperature in zone 1 was
  • Sample No. X3 is prepared in a similar manner as samples XI and X2, except only hexene is used as a comonomer.
  • blend components of the invention were melt homogenized using a
  • HDPE high density polyethylene
  • EXAMPLE DJ The blend samples numbered EX. 2-8, 10, 11, 13, 14, 18, 19, 20, 22, 23,
  • EXAMPLE IV The blend samples numbered EX. 2-8, 10, 11, 13, 14, 16, 17, 19, 20, 22,
  • the hot tack strength is measured by heat sealing the films at temperatures and separating and measuring the hot tack strength immediately after sealing.
  • a commercial hot tack tester (DTC Hot Tack Tester Model 52-D) is used for hot tack measurement.
  • the conditions for sealing and hot tack strength measurement were as follows: dwell time - 0.5 s, pressure - 0.5 N/m ⁇ -2, delay time - 0.4 s, and peel speed - 200 mm/s.
  • the hot tack strength is measured for the condition of sealing seal layer-to-seal layer, and not for HDPE-to-seal layer or HDPE-to-
  • Predicted Hot Tack Strength at a selected temperature X°C F ⁇ x HT ⁇ . + Fg x HTJJ
  • F ⁇ is the weight fraction of the component A of the blend
  • HT ⁇ is the hot tack strength for 100% component A at temperature X°C
  • Fg is the weight fraction of Component B of the blend
  • HTg is the hot tack strength for 100% Component B at temperature X°C.
  • the error bars in Figures 1-8 for the observed hot tack strength are based on ⁇ ⁇ , which represents one standard deviation.
  • the predicted maximum hot tack strength and the observed maximum hot tack strength values for the samples numbered EX. 1-15, along with the composition of the blends are shown in Table 6.
  • the predicted maximum hot tack strength shown in Tables 6 and 7 is calculated by using the relationship.
  • Figure 1 represents the maximum observed hot tack strength versus weight percent of XI in Ul for samples numbered EX. 1-9, and the predicted maximum hot tack strength for samples numbered EX. 2-8.
  • the hot tack values for the inventive blends is better than the conventional polyethylene sample EX. 1.
  • the observed hot tack values for the inventive blends is in general greater than the predicted hot tack values, and this result is unexpected.
  • Figure 2 represents the maximum observed hot tack strength versus weight percent of X2 in Ul for the samples numbered EX. 1, 10-12, and the predicted hot tack values for samples numbered EX. 10 and 11.
  • the observed maximum hot tack strength values for samples numbered EX. 10 and 11 are significantly and unexpectedly better than the predicted maximum hot tack strength.
  • Figure 3 represents the maximum hot tack strength versus weight percent of X3 in Ul for the samples numbered EX. 1, 13-15, and the predicted hot tack strength values for samples numbered EX. 13 and 14. Clearly, the observed hot tack values for the inventive blends numbered EX. 13 and 14 are better than the predicted values.
  • Figure 4 represents the maximum observed hot tack strength versus weight percent of XI in U2 for the samples numbered EX. 16-18, and 9, and the predicted hot tack values for samples numbered EX. 17 and 18.
  • the observed maximum hot tack strength values for samples numbered EX. 17 and 18 are significantly and unexpectedly better than the predicted maximum hot tack strength.
  • Figure 5 represents the maximum observed hot tack strength versus weight percent of X2 in U2 for the s.amples numbered EX. 16, 19,20, and 9, and the predicted hot tack values for samples numbered EX. 19 and 20.
  • the observed maximum hot tack strength values for samples numbered EX. 19 and 20 are better than the predicted maximum hot tack strength.
  • Figure 6 represents the maximum observed hot tack strength versus weight percent of XI in U3 for the samples numbered EX. 21-23, and 12, and the predicted hot tack values for samples numbered EX. 22 and 23.
  • Figure 7 represents the maximum observed hot tack strength versus weight percent of X2 in U3 for the samples numbered EX. 21, 24, 25, and 9, and the predicted hot tack values for samples numbered EX. 24, and 25.
  • the observed maximum hot tack strength values for samples numbered EX. 24 and 25 are significantly and unexpectedly better th.an the predicted maximum hot tack strength.
  • Figure 8 represents the hot tack strength versus temperature for samples numbered EX. 1, and 10-12.
  • the hot tack strength for the inventive blends EX. 10 and 11, is significantly better than the prior art polyethylene EX. 1, and at 40 wt% component X2 in prior art polyethylene sample EX. 1, the maximum hot tack strength is unexpectedly better than one would expect based on linear additivity of the two components involved (Ex. 1 and EX. 12).
  • Figure 9 represents the hot tack strength versus temperature for a prior art polyethylene sample numbered EX. 1, and a prior art blend of LDPE LLDPE (80/20 wt%) in comparison to the inventive blends of samples EX. 3 and 10 which contain 20 wt% of components XI and X2 respectively in the prior art polyethylene EX. 1.
  • the inventive blends show improved hot tack between 95-105°C in comparison to the prior art samples EX. 1 and a blend of LDPE/LLDPE.
  • the inventive blends show broader sealing window (defined as the temperature range where hot tack strength stays above a certain level, for example 2 N/l 5 mm).
  • the catalyst system may comprise various other transition metal metallocenes that are activated by alumoxane and/or ionic activators as the cocatalyst to produce polymers having a narrow molecular weight distribution and narrow composition distribution.
  • high pressure ethylene terpolymers can be utilized in the polymer blends of the invention.
  • polymer blends of the invention are useful in articles of manufacture such as potato chip bags, cereal bags and pouches, cookies and cracker bags and pouches, detergents and other powder bags, condiments or candy containers, liquid containers, such as bag-in-box applications, vegetable or fruit bags and meat and cheese bags.
  • the film of the invention are also useful in shrink packaging or plastic wrap applications.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Manufacture Of Macromolecular Shaped Articles (AREA)
  • Compositions Of Macromolecular Compounds (AREA)

Abstract

Mélanges polymères, films et articles présentant des caractéristiques de tenue des soudures à chaud améliorées. Ce mélange polymère comprend un polymère présentant une distribution de composition et de poids moléculaire étroite ainsi qu'un copolymère ou homopolymère d'éthylène haute pression. Les articles et films ainsi obtenus présentent des caractéristiques physiques sensiblement améliorées ainsi qu'une tenue des soudures à chaud étonnamment élevée et des températures d'amorçage de thermosoudage étonnamment faibles, ce qui leur confère une aptitude de mise en ÷uvre améliorée avec des vitesses de production supérieures dans des appareils de thermosoudage industriels.
EP95914069A 1994-03-15 1995-03-15 Melanges polymeres, films et articles composes de ces derniers Withdrawn EP0750650A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US214321 1980-12-08
US21432194A 1994-03-15 1994-03-15
PCT/US1995/003301 WO1995025141A1 (fr) 1994-03-15 1995-03-15 Melanges polymeres, films et articles composes de ces derniers

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EP0750650A1 true EP0750650A1 (fr) 1997-01-02

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EP (1) EP0750650A1 (fr)
JP (1) JPH09510484A (fr)
CA (1) CA2185469A1 (fr)
WO (1) WO1995025141A1 (fr)

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JPH11147295A (ja) * 1997-04-08 1999-06-02 Nippon Polychem Kk 積層体
EP1333044B2 (fr) † 2002-02-04 2011-06-15 Borealis Technology Oy Film avec une resistance au choc elevée
WO2006073962A1 (fr) 2005-01-03 2006-07-13 Dow Global Technologies Inc. Compositions de resine elastomere avec une meilleure resistance a l'ecoulement pulse
CA2800056A1 (fr) 2012-12-24 2014-06-24 Nova Chemicals Corporation Compositions de melange de polyethylene
CN105778258B (zh) * 2016-03-24 2018-04-17 福建师范大学泉港石化研究院 一种含稀土配合物的香蕉保鲜材料膜母粒的制备方法
CN105694197B (zh) * 2016-03-24 2017-11-07 福建师范大学 一种含稀土配合物的猕猴桃保鲜膜母粒的制备方法
CN105778255B (zh) * 2016-03-24 2017-11-14 福建师范大学泉港石化研究院 一种含稀土配合物的双孢菇保鲜膜膜母粒的制备方法
CN105801994B (zh) * 2016-03-24 2017-11-10 福建师范大学泉港石化研究院 一种含稀土配合物的葡萄保鲜膜母粒的制备方法
CN105602090B (zh) * 2016-03-24 2017-08-25 福建师范大学 一种含稀土配合物的荔枝保鲜膜母粒的制备方法
CN105778259B (zh) * 2016-03-24 2017-09-29 福建师范大学 一种含稀土配合物的草莓保鲜膜母粒的制备方法
CN105778260B (zh) * 2016-03-24 2017-12-19 福建师范大学泉港石化研究院 一种含稀土配合物的枇杷保鲜膜母粒的制备方法

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US5288531A (en) * 1991-08-09 1994-02-22 The Dow Chemical Company Pouch for packaging flowable materials
DE69308153T3 (de) * 1992-09-16 2012-04-05 Exxonmobil Chemical Patents, Inc. (N.D.Ges.D. Staates Delaware) Weiche filme mit verbesserten physikalischen eigenschaften
US5360648A (en) * 1993-06-24 1994-11-01 The Dow Chemical Company Pouch for packaging flowable materials

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Publication number Publication date
CA2185469A1 (fr) 1995-09-21
WO1995025141A1 (fr) 1995-09-21
JPH09510484A (ja) 1997-10-21

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