US20030194521A1 - Flexible tube, resistant to stress cracking and impermeable to water vapour - Google Patents

Flexible tube, resistant to stress cracking and impermeable to water vapour Download PDF

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Publication number
US20030194521A1
US20030194521A1 US10/221,728 US22172802A US2003194521A1 US 20030194521 A1 US20030194521 A1 US 20030194521A1 US 22172802 A US22172802 A US 22172802A US 2003194521 A1 US2003194521 A1 US 2003194521A1
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Prior art keywords
tube
ethylene
mixture
fact
inclusive
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US10/221,728
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English (en)
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G?eacute;ry Dambricourt
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CEP Industrie SA
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Individual
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Publication of US20030194521A1 publication Critical patent/US20030194521A1/en
Priority to US11/298,592 priority Critical patent/US7381455B2/en
Abandoned legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/17—Component parts, details or accessories; Auxiliary operations
    • B29C45/26—Moulds
    • B29C45/36—Moulds having means for locating or centering cores
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/0046—Details relating to the filling pattern or flow paths or flow characteristics of moulding material in the mould cavity
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D35/00—Pliable tubular containers adapted to be permanently or temporarily deformed to expel contents, e.g. collapsible tubes for toothpaste or other plastic or semi-liquid material; Holders therefor
    • B65D35/02—Body construction
    • B65D35/04—Body construction made in one piece
    • B65D35/08—Body construction made in one piece from plastics material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/17—Component parts, details or accessories; Auxiliary operations
    • B29C45/26—Moulds
    • B29C45/27—Sprue channels ; Runner channels or runner nozzles
    • B29C45/2701—Details not specific to hot or cold runner channels
    • B29C45/2708—Gates
    • B29C2045/2714—Gates elongated, e.g. film-like, annular
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/17—Component parts, details or accessories; Auxiliary operations
    • B29C45/26—Moulds
    • B29C45/27—Sprue channels ; Runner channels or runner nozzles
    • B29C45/2701—Details not specific to hot or cold runner channels
    • B29C45/2708—Gates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
    • B29K2995/0037—Other properties
    • B29K2995/0065—Permeability to gases
    • B29K2995/0067—Permeability to gases non-permeable
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2023/00—Tubular articles
    • B29L2023/20—Flexible squeeze tubes, e.g. for cosmetics
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/13—Hollow or container type article [e.g., tube, vase, etc.]
    • Y10T428/1352—Polymer or resin containing [i.e., natural or synthetic]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/13—Hollow or container type article [e.g., tube, vase, etc.]
    • Y10T428/1352—Polymer or resin containing [i.e., natural or synthetic]
    • Y10T428/139—Open-ended, self-supporting conduit, cylinder, or tube-type article
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/13—Hollow or container type article [e.g., tube, vase, etc.]
    • Y10T428/1352—Polymer or resin containing [i.e., natural or synthetic]
    • Y10T428/1397—Single layer [continuous layer]

Definitions

  • the invention relates to a package, in particular to a flexible tube, which is resistant to stress cracking and impermeable to water vapor.
  • Pasty substances such as tooth pastes, pharmaceutical products, cosmetology products, food products, hygiene products, dentifrices, cleaning products, fatty products, greases, mastics and glues, are often offered in packages of the tube type.
  • These tubes are made up of a tubular body of constant cross section, of circular, oval or other shape.
  • the tubular body which forms what is called the “skirt” in the following, has a first end generally closed by heat fusing and a second opposite end configured so as to form a head for distribution of the products contained in the skirt.
  • the distribution head is provided with a screwed, snapped or other closing device, of standard cap, service cap or other type.
  • the skirt of the tube must therefore be produced out of a flexible material.
  • This material must also be capable of heat fusing. It must also have characteristics of resistance to stress cracking and impermeability to water vapor in order to meet the specifications of compatibility of the products which are intended to be packaged in the tube.
  • EP 0 856 554-A describes an injected packaging with improved resistance to stress cracking, which has a wall consisting of a thermoplastic mixture containing a first ethylene-C 4 to C 5 olefin copolymer and a second ethylene-C 6 to C 10 olefin copolymer.
  • the mixture of these two copolymers must have a high fluidity index (standard ISO 1133) on the order of 10 g/10 min in order to be suitable for injection molding of objects with a wall of small thickness, hence the use in the mixture of an ethylene-C 4 to C 5 olefin copolymer with an MFI between 10 and 20 g/10 min, which is a material which is not resistant to stress cracking according to the specifications generally required. Furthermore, this document is silent as to the properties of flexibility of the tube as a function of the thickness of the wall and as to the properties of impermeability of the wall to water vapor.
  • the invention aims to provide a tube produced by the injection process which is at the same time flexible, resistant to stress cracking and impermeable to water, whereas these characteristics are incompatible with the injection process according to prior art when they are simultaneously required.
  • the invention proposes a tube made up of a skirt and a distribution head, characterized by the fact that its wall is made of an ethylene-linear C 4 to 10 olefin copolymer or of a mixture of ethylene-linear C 4 to 10 olefin copolymers having a fluidity index (MFI) measured according to the ISO 1133 standard between 3 and 10 g/10 min inclusive, and preferably between 3.5 and 9 g/10 min inclusive, and a density between 0.880 and 0.935 g/cm 3 inclusive, and preferably between 0.900 and 0.930 g/cm 3 inclusive, by the fact that the skirt has a wall thickness at mid-height between 0.30 and 1.00 mm inclusive, and preferably between 0.35 and 0.95 mm inclusive, for a length between 40 and 200 mm inclusive, and by the fact that the head and the skirt are manufactured in a single operation of injection in a mold, in order to obtain a flexible tube which is resistant to stress cracking and imperme
  • MFI fluidity index
  • the mixture of ethylene-linear C 4 to 10 olefin copolymers is either a mixture of ethylene-linear C 4 to 5 olefin copolymers or a mixture of ethylene-linear C 6 to 10 olefin copolymers.
  • the ethylene-linear C 4 to 10 olefin copolymer(s) is(are) ethylene-octene copolymer(s).
  • the injection mold for the tube has mold cavity 5 and mold insert 4 which has central part 8 whose free upper end 9 has feed channels 10 and is supported centered on cavity 5 during the phase of injection of the tube.
  • said end 9 is in the shape of a reentrant cone, and the angles ⁇ between channels 10 and the vertical axis of cavity 5 are less than 90°.
  • the total widths of channels 10 at their zones of connection A with the end piece of the head of the tube represent at least 15%, and preferably more than 25% of the perimeter of this end piece.
  • channels 10 have a width which increases from injection point 13 according to a centrifugal radial direction to their points of connection A with the end piece of the head of the tube.
  • the end piece of the distribution head has an annular zone of narrowing beyond the zone of connection A of channels 10 with the end piece of the head of the tube.
  • end piece included, central part 8 of the insert of the injection mold is mobile, and upper wall 6 of the end piece of the head of the tube is injected after movement of the mobile part back a determined distance as a function of the thickness of the wall which is desired.
  • a fluidity index of the ethylene-linear C 4 to 10 olefin copolymer or mixture of these copolymers between 5 and 10 g/10 min inclusive, and preferably between 5 and 9 g/10 min inclusive, and a thickness of the wall at mid-height of the skirt situated on the curve represented in FIG. 2, as a function of the length of the skirt+ or ⁇ 0.05 mm, in order to obtain a tube with improved flexibility.
  • the density of the ethylene-linear C 4 to 10 olefin copolymer or mixture of these copolymers is between 0.880 and 0.920 g/cm 3 inclusive, and preferably between 0.900 and 0.920 g/cm 3 inclusive, in order to obtain a tube with improved flexibility.
  • the fluidity index of the ethylene-linear C 4 to 10 olefin copolymer or mixture of these copolymers is between 5 and 10 g/10 min, and preferably between 5 and 9 g/10 min inclusive, and the density of the ethylene-linear C 4 to 10 olefin copolymer or mixture of these copolymers is between 0.900 and 0.920 g/cm 3 inclusive.
  • the wall of the tube is made of an ethylene-octene copolymer with a fluidity index between 5 and 6 g/10 min inclusive and a density equal to 0.919 g/cm 3 .
  • the density of the ethylene-linear C 4 to 10 olefin copolymer or mixture of these copolymers is between 0.925 and 0.935 g/cm 3 inclusive for a thickness of the wall at mid-height of the skirt close to 0.45 mm, between 0.920 and 0.930 g/cm 3 for a thickness of the wall at mid-height of the skirt close to 0.60 mm, between 0.915 and 0.925 g/cm 3 for a thickness of the wall at mid-height of the skirt close to 0.75 mm, in order to obtain a tube with reinforced impermeability to water vapor.
  • Preferable in this case is a wall made of a mixture of: a) 33 to 67 wt %, with respect to the total weight of the mixture, of an ethylene-linear C 4 to 10 olefin copolymer having a density between 0.900 and 0.920 g/cm 3 inclusive, and [b] 67 to 33 wt %, with respect to the total weight of the mixture, of an ethylene-linear C 4 to 10 olefin copolymer having a density between 0.920 and 0.935 g/cm 3 inclusive, in order to obtain a tube with reinforced impermeability to water vapor and with optimized flexibility as a function of the thickness of the wall at mid-height of the skirt.
  • the wall is a mixture of: a) 33 to 67 wt %, with respect to the total weight of the mixture, of an ethylene-octene copolymer having a fluidity index between 3 and 6.5 g/10 min inclusive and a density between 0.900 and 0.920 g/cm 3 inclusive, and b) 67 to 33 wt %, with respect to the total weight of the mixture, of an ethylene-octene copolymer having a fluidity index between 3 and 6.5 g/10 min and a density between 0.920 and 0.935 g/cm 3 inclusive, in order to obtain a tube with reinforced impermeability to water vapor and optimized flexibility as a function of the thickness of the wall at mid-height and of the length, of the skirt.
  • the wall is a mixture of: a) 33 to 67 wt %, with respect to the total weight of the mixture, of an ethylene-octene copolymer having a fluidity index between 5 and 6 and a density equal to 0.919 g/cm 3 , and b) 67 to 33 wt %, with respect to the total weight of the mixture, of an ethylene-octene copolymer having a fluidity index between 3 and 4 g/10 min and a density equal to 0.935 g/cm 3 .
  • each ethylene-octene copolymer represents 50 wt % of said mixture.
  • the tube has a wall made of a mixture of: a) 33 to 67 wt %, with respect to the total weight of the mixture, of an ethylene-octene copolymer having a fluidity index between 3 and 5 g/10 min and a density equal to 0.915 g/cm 3 , and b) 67 to 33 wt %, with respect to the total weight of the mixture, of an ethylene-octene copolymer having a fluidity index between 3 and 4 g/10 min and a density equal to 0.935 g/cm 3 , in order to optimize the resistance to stress cracking and impermeability to water at the expense of less flexibility of the wall of the tube.
  • FIG. 1 diagrammatically represents the zones of selection of the fluidity indexes and densities of the ethylene-linear C 4 to 10 olefin copolymer or mixture of these copolymers according to the particular properties which are desired for the tube which is obtained.
  • FIG. 2 represents, in the form of a curve, the thicknesses of the wall of the skirt at mid-height of the skirt which are to be chosen as a function of the desired length of the skirt, when the wall of the tube is made of an ethylene-linear C 4 to 10 olefin copolymer or mixture of these copolymers having [a fluidity index] between 5 and 10 g/10 min inclusive, and preferably between 5 and 9 g/10 min inclusive, in order to obtain a tube with improved flexibility.
  • FIG. 3 represents, in the form of a curve, the thicknesses of the wall of the skirt at mid-height of the skirt which are to be chosen as a function of the desired length of the skirt, when the wall of the tube is made of an ethylene-linear C 4 to 10 olefin copolymer or mixture of these copolymers having [a fluidity index] between 3 and 6.5 g/10 min inclusive, and preferably between 3.5 and 6.5 g/10 min inclusive, in order to obtain a tube with improved resistance to stress cracking, in particular in the presence of surfactant products.
  • FIG. 4 represents a mold of prior art which can be used for the injection of the tube according to the invention.
  • FIG. 5 represents a mold of prior art which is preferably used for the injection of the tube of the invention.
  • FIG. 6 diagrammatically represents the flow sheets during injection of the tube of the invention with the mold represented in FIG. 5.
  • FIG. 7 is an enlarged view of the part noted VII in FIG. 5.
  • FIG. 8 diagrammatically represents a perspective view of the head of the mold which is to be used most preferably for injection of the tube of the invention.
  • FIG. 9 is a view in section according to axis IX-IX of FIG. 8.
  • FIG. 10 is atop view of upper part 9 of the mobile part of the mold represented in FIG. 7.
  • the tubes consist of a skirt, of constant cross section, of circular, oval or other shape, closed at one of its ends by heat fusing, after filling of the tube with the pasty product which is to be packaged.
  • the tube is configured in such a way as to form a distribution head for the product contained in the skirt.
  • the capacity of the tube is its primary characteristic.
  • the capacity is defined by the length and the diameter of the skirt, that is to say by the length and the diameter of the circular cross section of the skirt.
  • the capacities ordinarily offered on the market are between 2 and 500 mL.
  • the ratios of the skirt lengths with respect to the diameter of the skirts ordinarily observed on the market are between 2.5 and 6, and preferably 4.
  • the invention preferably applies to the formats in effect on the market and therefore complies with a ratio of skirt length with respect to the diameter between 2.5 and 6, and preferably 4.
  • the length of the skirt is therefore between 40 and 200 mm.
  • the skirt of the tube must at the same time be resistant to stress cracking, impermeable to water vapor, and flexible.
  • Stress cracking or “stress cracking” is a phenomenon of physicochemical attack of a surfactant product on a polymer. This phenomenon is expressed by the formation of micro-cracks in the polymer, which can go as far as bursting the wall. The risk of bursting is particularly great in the vicinity of the heat fused end.
  • the products contained in the tube are loaded to varying degrees with surfactants and can therefore cause cracking or bursting of the envelope.
  • the tube is filled with a surfactant solution with a concentration of 0.3%, for example, of Igepal CO 630 or ethoxylated nonylphenol in distilled water, and is fused at the end by hot squeezing.
  • a surfactant solution with a concentration of 0.3%, for example, of Igepal CO 630 or ethoxylated nonylphenol in distilled water, and is fused at the end by hot squeezing.
  • the tube is placed in an oven at 55° C. for 24 hours. Coming out of the oven, a pressure of 2 to 4.5 bars is applied for 2 to 10 seconds, according to the specifications of the orderer. Coming out of the oven, the tube must not have any leak at the fused part or any crack or tear of the wall.
  • the products contained in the flexible envelope are also loaded to varying degrees with water.
  • the packaged products are evolving towards aqueous base emulsions.
  • the packaging of these products must therefore meet increasingly severe criteria of impermeability to water vapor in order to prevent an excessive loss of weight by evaporation of the water through the flexible wall, and consequently a modification of the “pasty” character of the cream packaged in the tube.
  • the measurement of the permeability to water is always done in percentage of the loss of weight of the cream by evaporation, with respect to the initial weight of cream contained in the tube.
  • the weight loss ratio therefore depends simultaneously on the porosity with regard to water and on the ratio between the surface area of evaporation, that is to say the surface area of the skirt, and the volume of cream contained in the tube.
  • the test of impermeability to water consists of placing the tubes, which are filled beforehand with the product which to be tested and are fused, in an oven whose temperature, depending on the tests, is between 45 and 55° C., for a period of time, depending on the tests, between 2 and 8 weeks.
  • the loss of weight must be less than 2%, 3%, 5% or 8% in the least restrictive case.
  • the difficulty of the test increases with reduction of the size of the tube: as the capacity of the tube decreases, the ratio of evaporation surface area constituted by the skirt with respect to the volume of cream contained in the tube increases.
  • the evaporation being proportional to the surface area of the skirt, the loss of weight is proportionally greater for tubes of small capacity, moreover which are partially filled.
  • the skirt of the tube must be flexible in order to allow evacuation of the pasty products contained in it, simply by the user putting pressure on the wall.
  • the flexibility of the wall is inversely proportional to its thickness and to the density of the thermoplastic material.
  • the thickness of the wall is a function of the length of the skirt.
  • the material coming out of the point of injection of the material, must travel the route inside of the mold ensuring the filling of the mold.
  • the material changes state (rheology in the melted state) and can be degraded by exceeding its limit shearing speed or its limit temperature, if the material is too viscous, if the wall is too thin, or if the length of running in the mold (length of the skirt) is too long.
  • the density of the copolymer has no significant influence on the injectability but has a determining influence on the flexibility of the wall.
  • two ethylene-octene copolymers of the same grade (for example, 6) form a stiff wall for a density of 0.950 g/cm 3 and a very flexible wall for a density of 0.900 g/cm 3 , if this wall has a thickness of 0.6 mm.
  • the invention therefore consists of obtaining, by the process of injection, a thin wall for wall lengths of 40 to 200 mm and of formulating a material which simultaneously has good characteristics of flexibility, resistance to stress cracking and impermeability to water, the wall thickness increasing correlatively with the length of the skirt, the wall being sufficiently thick for allowing injection of very viscous materials guaranteeing resistance to stress cracking, the density of the formulated materials guaranteeing impermeability to water vapor of the wall, the wall keeping an acceptable flexibility taking into account its thickness and the density of the formulated material, the material being injected without irremediable degradation by exceeding the limit shearing speed or exceeding the limit temperature during the injection.
  • an ethylene-linear C 4 to C 10 olefin copolymer or a mixture of ethylene-linear C 4 to C 10 olefin copolymers having a fluidity index (MFI) measured according to the ISO 1133 standard between 3 and 10 g/10 min, and preferably between 3.5 and 9 g/10 min, and a density between 0.880 and 0.935 g/cm 3 , that is to say when the copolymer or mixture of these copolymers has a fluidity index and a density included in the white zone noted [a, b, c, d] in FIG.
  • MFI fluidity index
  • [it] can be injected without destruction by exceeding the limit shearing speed and/or exceeding the limit temperature, in order to form a tube whose skirt has a wall thickness between 0.30 and 1.0 mm, and preferably between 0.35 and 0.95 mm, with a skirt length between 40 and 200 mm.
  • the tube which is obtained has an excessive permeability to water vapor.
  • the ethylene-linear C 4 to C 10 olefin copolymer or mixture of these copolymers has a density greater than 0.935 g/cm 3 , the stiffness of the tube which is obtained becomes excessive, for a thickness of weight [sic] between 0.30 and 1.00 mm, and preferably between 0.35 and 0.95 mm required for making the material injectable.
  • the tube in order to obtain a tube which can be manufactured by the process of injection, in a single injection operation and having a permeability to water vapor and a resistance to stress cracking in accordance with the specifications defined in the preceding, a flexibility allowing evacuation of the product by simple pressure of the user and an ability to be fused by the so-called “hot air” or “heating grippers” methods currently used, the tube must consist of an ethylene-linear C 4 to C 10 olefin copolymer or a mixture of ethylene-linear C 4 to C 10 olefin copolymers having a fluidity index between 3 and 10 g/10 min inclusive and a density between 0.880 and 0.935 g/cm 3 .
  • the ethylene-linear C 4 to C 10 olefin copolymer or the mixture of ethylene-linear C 4 to C 10 olefin copolymers has a fluidity index between 3.5 and 9 g/10 min inclusive and a density between 0.900 and 0.930 inclusive.
  • one will preferably choose mixtures of ethylene-linear olefin copolymers having the same number of carbons in the olefin, when the material is composed of a mixture of two copolymers.
  • the thickness of the wall has to be modulated as a function of the length of the skirt because the tube is to be manufactured by the process of injection, in a single operation.
  • the thickness of the wall referred to here is the average thickness of the wall along the length of the skirt of this wall. By convention, this average thickness is measured at mid-height of the skirt of the tube which is obtained.
  • ethylene-linear C 4 to C 10 olefin copolymer or a mixture of ethylene-linear C 4 to C 10 olefin copolymers having a fluidity index between 5 and 10 g/10 min inclusive, and preferably between 5 and 9 g/10 min inclusive.
  • the minimum thickness of the wall being determined by the length of the skirt of the tube and the fluidity index of the material which is used, it has been found that with the ethylene-linear C 4 to C 10 olefin copolymer or mixture of these copolymers having a fluidity index between 5 and 10 g/10 min inclusive, and preferably between 5 and 9 g/10 min inclusive, that is to say having a relatively high fluidity index, the average thickness of the wall of the skirt must be chosen on the curve represented in FIG. 2, as a function of the desired skirt length. Thus, the average thickness of the skirt tends towards a lower limit in the vicinity of:
  • This choice is particularly pertinent for large tubes or for materials of high density, because it allows one to minimize the stiffness imposed, either by the thickness induced by the flow length, or by the density of the material.
  • the tube will be even more flexible if it is injected out of an ethylene-linear C 4 to 10 olefin copolymer or mixture of these copolymers whose MFI is between 5 and 10 g/10 min inclusive, and preferably between 5 and 9 g/10 min inclusive, and whose density is between 0.900 and 0.920 g/cm 3 inclusive, which allows one to choose the minimum wall thickness for a given skirt length.
  • a particularly preferred practical example of this solution is an ethylene-octene copolymer with a fluidity index between 5 and 6 inclusive and a density equal to 0.919 g/cm 3 , for example, Dowlex 2035E.
  • the wall thickness correlating with its length, the increased permeability of a wall of great length produced in a material of lower density is compensated for by the improvement of the ratio of evaporation surface area with respect to the volume of contained cream resulting from the increase of the size of the tube, and by the thickening of the wall.
  • Modulation of the composition of the mixture permits one to modulate the density and therefore to stabilize the flexibility of the wall as a function of its thickness, that is to say indirectly of the length of the skirt, the increased porosity being compensated for by the improvement of the ratio of the evaporation surface area with respect to the weight of contained cream, as disclosed in the preceding.
  • the desired effect will be reached by using a mixture of 33 to 67 wt %, with respect to the total weight, of Dowlex 2035E with a fluidity index between 5 and 6 g/10 min and a density equal to 0.919 g/cm 3 and 67 to 33 wt %, with respect to the total weight, of Dowlex NG 2429, with a fluidity index between 3 and 4 g/10 min and a density equal to 0.935 g/cm 3 .
  • a mixture of 50 wt % of the first copolymer and 50 wt % of the second copolymer is more preferred because this mixture guarantees control of the amount measured in each injection and an optimized balance between weight loss and flexibility for tubes of small size.
  • a preferred mixture according to the invention for obtaining a tube with a good resistance to stress cracking and a very good impermeability to water vapor with an acceptable flexibility will contain a mixture containing 50 wt % of each of the ethylene-actene [sic; octene] copolymers mentioned above.
  • the fluidity index of the material is reduced into a limit greater than or equal to 3 and preferably 3.5. It is then preferable to use materials consisting of a mixture of 33 to 67 wt %, with respect to the total weight of the mixture, of an ethylene-linear C 4 to C 10 olefin copolymer with a fluidity index between 3 and 4 g/10 min and a density equal to 0.935 g/cm 3 and 67 to 33 wt %, with respect to the total weight of the mixture, of an ethylene-linear C 4 to C 10 olefin copolymer with a fluidity index between 5 and 6 g/10 min and a density equal to 0.915 g/cm 3 .
  • the flexibility of the wall is attenuated proportionally to the increase of its thickness.
  • Table 1 hereafter presents examples of implementation of the invention. These examples are intended to illustrate the invention and not to limit it.
  • all the copolymers are ethylene-octene copolymers or ethylene butene or ethylene hexene copolymers.
  • tests have been done with ethylene-linear C 4 to C 10 olefin copolymers giving similar results, the properties of flexibility, resistance to stress cracking and barrier to water vapor being modulated in the same manner as a function of the fluidity index and the density of the material as well as the thickness of the wall.
  • the materials of the invention can be injected, the head and the skirt being injected in a single operation, using extreme conditions of injection pressure allowing one to inject materials with high viscosity into thin walls.
  • the usual injection pressures are on the order of 450 to 600 bars.
  • the injection pressures which are used are on the order of 1250 to 2500 bars depending on the length of the skirt, the thickness of the skirt and the viscosity of the injected material.
  • the tube is injected into a mold as represented in FIG. 4 and composed of an insert noted 4 in FIG. 4, a cavity insert 5 in FIG. 4, and a nozzle receiver 6 in FIG. 4 in which injection nozzle 7 in FIG. 4 fits, that is to say the channel through which the melted plastic material is led into the cavity insert defined by the nozzle receiver, the cavity insert and the insert.
  • the insert Under the effect of the very high injection pressure necessary for injecting the material in the wall thicknesses required for the flexibility of the tube, the insert has a tendency to bow towards the cavity insert. This results in a variable wall thickness and therefore in variable flexibility.
  • the decentering of the insert generates preferential streams of material during injection of the skirt, preferential streams which join together in “weld lines”, these “weld lines” forming zones of lack of resistance to stress cracking.
  • a first injection mold for obtaining this result is that of the type represented in FIG. 5. As seen in FIG. 5, this mold has central part 8 . Central part 8 of insert 4 has free end 9 in FIG. 5 which rests centered on nozzle receiver 6 .
  • FIG. 7 is an enlarged view of the part noted VII in FIG. 5.
  • weld lines have the serious disadvantage of creating zones of lack of resistance to stress cracking of the skirt. Moreover, these weld lines can possibly cause the appearance of facets on the skirt which modify the original shape of the tube, degrade its appearance and in certain cases, can induce defects during laying of decoration (silk screen process, labelling, hot marking) and therefore degrade the appearance of this decoration.
  • the invention also proposes a process which makes it possible to considerably attenuate the weld lines while keeping the necessary support of the insert on the nozzle receiver.
  • this process consists of placing the injection point noted 13 in a plane situated below the upper part of the head of the tube at point of connection A between feed channels 10 and the head of the tube.
  • the stream of injected material travels a route characterized by an angle, noted ⁇ in FIG. 9, less than 90°.
  • a mold for implementation of the process of the invention will include cavity insert 5 , stationary insert 4 having central part 8 of which free upper part 9 is in the shape of a reentrant cone with respect to the insert.
  • An advantageous solution consists of providing total widths of connection of the feed channels at the point of connection A with the upper part of the head of the tube, which represent at least 15% of the perimeter of the upper part of the head of the tube.
  • Another solution which further improves the annular feed but which reduces the area of support of the insert at the nozzle receiver consists of bringing the total widths of connection of the feed channels at the point of connection with the head of the tube to more than 25% of the perimeter of the upper part of the head.
  • annular zone of narrowing Z formed on the vertical side of the end piece, at the entrance of the upper part of the head of the tube, after the zone of connection with the radial feed channels.
  • the narrowing zone must be sufficiently thick, with a thickness at least greater than the thickness of the wall of the skirt of the tube.
  • central insert 8 can be made mobile in insert 4 .
  • This arrangement is advantageously used when one does not wish to connect a “reducer” end piece on the tube, reducer which is then constituted by the top summit wall of the head of the tube. This wall is injected after the injection of the skirt and without interruption, after movement of the central insert back proportionally to the desired wall thickness of the reducer.
  • the opening hole is obtained by perforation a posteriori, the diameter of the hole being modulated to the desired size, taking into account the cream contained in the tube.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Tubes (AREA)
  • Rigid Pipes And Flexible Pipes (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
  • Manufacture Of Macromolecular Shaped Articles (AREA)
  • Gas Separation By Absorption (AREA)
  • Preventing Corrosion Or Incrustation Of Metals (AREA)
  • Injection Moulding Of Plastics Or The Like (AREA)
  • Packages (AREA)
  • Insulators (AREA)
  • Insulating Bodies (AREA)
  • Wrappers (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)
US10/221,728 2000-03-17 2001-03-16 Flexible tube, resistant to stress cracking and impermeable to water vapour Abandoned US20030194521A1 (en)

Priority Applications (1)

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US11/298,592 US7381455B2 (en) 2000-03-17 2005-12-12 Flexible tube, resistant to stress cracking and impermeable to water vapor

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FR0003469A FR2806385B1 (fr) 2000-03-17 2000-03-17 Tube souple, resistant a la fissuration sous contrainte et impermeable a la vapeur d'eau
FR00/03469 2000-03-17
PCT/FR2001/000800 WO2001068355A1 (fr) 2000-03-17 2001-03-16 Tube souple, resistant a la fissuration sous contrainte et impermeable a la vapeur d'eau

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US11/298,592 Continuation US7381455B2 (en) 2000-03-17 2005-12-12 Flexible tube, resistant to stress cracking and impermeable to water vapor

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US20030194521A1 true US20030194521A1 (en) 2003-10-16

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US10/221,728 Abandoned US20030194521A1 (en) 2000-03-17 2001-03-16 Flexible tube, resistant to stress cracking and impermeable to water vapour
US11/298,592 Expired - Lifetime US7381455B2 (en) 2000-03-17 2005-12-12 Flexible tube, resistant to stress cracking and impermeable to water vapor

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US (2) US20030194521A1 (ja)
EP (1) EP1263569B9 (ja)
JP (1) JP2003526581A (ja)
CN (1) CN1321804C (ja)
AT (1) ATE254997T1 (ja)
AU (1) AU4426401A (ja)
CA (1) CA2402540A1 (ja)
DE (2) DE60101318D1 (ja)
DK (1) DK1263569T5 (ja)
ES (1) ES2211787T3 (ja)
FR (1) FR2806385B1 (ja)
MX (1) MXPA02009078A (ja)
RU (1) RU2266203C2 (ja)
WO (1) WO2001068355A1 (ja)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20060188676A1 (en) * 2003-01-24 2006-08-24 Gery Bernard Marie Dambricourt Flexible tube made from polypropylene and method for production of said tube
US20060204693A1 (en) * 2003-01-24 2006-09-14 Gery Bernard Marie Dambricourt Fully emptiable flexible tube with an amplified return effect
US20100119644A1 (en) * 2008-11-07 2010-05-13 Giflor S.R.L. Mould for injection moulding of tubes having slim walls and being made of plastic
US9617042B2 (en) 2014-01-17 2017-04-11 Cep Tubes Injection-molded flexible tube based on high-density polyethylene

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8906187B2 (en) * 2008-06-25 2014-12-09 Colgate-Palmolive Company Method of making shoulder/nozzles with film barrier liners
US20100187255A1 (en) * 2009-01-23 2010-07-29 Wen-Kui Hsu Flexible tubular container with tear-off structure
CH706993A1 (en) * 2012-09-19 2014-03-31 Alpla Werke Injection molding apparatus and method for producing a tube head, and tube head.
FR3000035B1 (fr) * 2012-12-21 2016-01-08 Albea Services Tube ameliore exploitant les proprietes de la jupe pour la tete de tube.
CN104708777A (zh) * 2013-12-13 2015-06-17 汉达精密电子(昆山)有限公司 套筒顶出结构
EP3292980A1 (fr) * 2016-09-13 2018-03-14 Aisapack Holding SA Procédé et dispositif d'extrusion et d'étiquetage d'un produit cylindrique

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US4959005A (en) * 1989-02-23 1990-09-25 Primtec Self-aligning mold for injection molding of hollow plastic products
US5174941A (en) * 1988-06-02 1992-12-29 Primtec Injection-molding product wall-thickness control methods
US5677383A (en) * 1991-10-15 1997-10-14 The Dow Chemical Company Fabricated articles made from ethylene polymer blends
US5928740A (en) * 1997-02-28 1999-07-27 Viskase Corporation Thermoplastic C2 -α-olefin copolymer blends and films
US6032800A (en) * 1998-05-14 2000-03-07 Cryovac, Inc. Laminate and package made therefrom
US6124008A (en) * 1997-02-04 2000-09-26 L'oreal Injected-molded package of blended ethylene/olefin copolymers
US6297323B1 (en) * 1997-06-02 2001-10-02 Basf Aktiengesellschaft Polymer mixture
US20010046606A1 (en) * 2000-01-24 2001-11-29 Li-Min Tau Composition and films thereof
US6538070B1 (en) * 1991-12-30 2003-03-25 Dow Global Technologies Inc. Ethylene interpolymer polymerizations
US6723398B1 (en) * 1999-11-01 2004-04-20 Dow Global Technologies Inc. Polymer blend and fabricated article made from diverse ethylene interpolymers

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JPH03226462A (ja) * 1990-01-31 1991-10-07 Daiwa Can Co Ltd プラスティックチューブ
JP3244135B2 (ja) * 1992-10-26 2002-01-07 三井化学株式会社 絞り出しチューブ状円筒容器
DE69311497T2 (de) * 1992-10-26 1997-11-06 Mitsui Petrochemical Ind Zusammendrückbarer rohrförmiger Behälter und Verfahren zu seiner Herstellung
FR2764230A1 (fr) * 1997-06-06 1998-12-11 Carnaudmetalbox Sante Beaute Procede de fabrication d'un tube souple et tube obtenu selon ce procede

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Publication number Priority date Publication date Assignee Title
US5174941A (en) * 1988-06-02 1992-12-29 Primtec Injection-molding product wall-thickness control methods
US4959005A (en) * 1989-02-23 1990-09-25 Primtec Self-aligning mold for injection molding of hollow plastic products
US5677383A (en) * 1991-10-15 1997-10-14 The Dow Chemical Company Fabricated articles made from ethylene polymer blends
US6538070B1 (en) * 1991-12-30 2003-03-25 Dow Global Technologies Inc. Ethylene interpolymer polymerizations
US6124008A (en) * 1997-02-04 2000-09-26 L'oreal Injected-molded package of blended ethylene/olefin copolymers
US5928740A (en) * 1997-02-28 1999-07-27 Viskase Corporation Thermoplastic C2 -α-olefin copolymer blends and films
US6297323B1 (en) * 1997-06-02 2001-10-02 Basf Aktiengesellschaft Polymer mixture
US6032800A (en) * 1998-05-14 2000-03-07 Cryovac, Inc. Laminate and package made therefrom
US6723398B1 (en) * 1999-11-01 2004-04-20 Dow Global Technologies Inc. Polymer blend and fabricated article made from diverse ethylene interpolymers
US20010046606A1 (en) * 2000-01-24 2001-11-29 Li-Min Tau Composition and films thereof

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20060188676A1 (en) * 2003-01-24 2006-08-24 Gery Bernard Marie Dambricourt Flexible tube made from polypropylene and method for production of said tube
US20060204693A1 (en) * 2003-01-24 2006-09-14 Gery Bernard Marie Dambricourt Fully emptiable flexible tube with an amplified return effect
US7695789B2 (en) * 2003-01-24 2010-04-13 Cep Industrie Fully emptiable flexible tube with an amplified return effect
US20100119644A1 (en) * 2008-11-07 2010-05-13 Giflor S.R.L. Mould for injection moulding of tubes having slim walls and being made of plastic
US9617042B2 (en) 2014-01-17 2017-04-11 Cep Tubes Injection-molded flexible tube based on high-density polyethylene

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RU2002124864A (ru) 2004-02-20
MXPA02009078A (es) 2004-04-05
DE60101318T2 (de) 2004-08-19
DK1263569T5 (da) 2005-05-17
ES2211787T3 (es) 2004-07-16
EP1263569B9 (fr) 2005-01-26
CN1321804C (zh) 2007-06-20
AU4426401A (en) 2001-09-24
US7381455B2 (en) 2008-06-03
FR2806385A1 (fr) 2001-09-21
DK1263569T3 (da) 2004-04-05
ATE254997T1 (de) 2003-12-15
WO2001068355A1 (fr) 2001-09-20
RU2266203C2 (ru) 2005-12-20
EP1263569B1 (fr) 2003-11-26
CA2402540A1 (fr) 2001-09-20
DE60101318T4 (de) 2005-07-21
CN1427768A (zh) 2003-07-02
DE60101318D1 (de) 2004-01-08
EP1263569A1 (fr) 2002-12-11
FR2806385B1 (fr) 2002-12-06
JP2003526581A (ja) 2003-09-09
US20070082160A1 (en) 2007-04-12

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