Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L77/00—Compositions of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Compositions of derivatives of such polymers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
  • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
  • C08L67/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L77/00—Compositions of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Compositions of derivatives of such polymers
  • C08L77/02—Polyamides derived from omega-amino carboxylic acids or from lactams thereof
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L77/00—Compositions of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Compositions of derivatives of such polymers
  • C08L77/06—Polyamides derived from polyamines and polycarboxylic acids
• • 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
  • B29C2949/00—Indexing scheme relating to blow-moulding
  • B29C2949/07—Preforms or parisons characterised by their configuration
  • B29C2949/0861—Other specified values, e.g. values or ranges
  • B29C2949/0862—Crystallinity
• • 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
  • B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
  • B29C49/0005—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor characterised by the 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
  • B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
  • B29C49/22—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor using multilayered preforms or parisons
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2439/00—Containers; Receptacles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B37/00—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding
  • B32B37/14—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers
  • B32B37/15—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers with at least one layer being manufactured and immediately laminated before reaching its stable state, e.g. in which a layer is extruded and laminated while in semi-molten state
  • B32B37/153—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers with at least one layer being manufactured and immediately laminated before reaching its stable state, e.g. in which a layer is extruded and laminated while in semi-molten state at least one layer is extruded and immediately laminated while in semi-molten state

Definitions

• the present invention relates to improving the adhesion between a barrier layer and a support layer in coextruded blow-molded applications. More particularly this invention relates to the incorporation of a modified polyethylene having adhesive properties into either the. barrier layer or the support layer, wherein the modified polyethylene is prepared by grafting an unsaturated carboxylic acid or derivative thereof to high-density polyethylene. Furthermore, the present invention also relates to modification of the rheology of base resins, such as PET, so that they more closely match the rheology of high density polyethylene (a preferred material for the support layer in the coextruded blow-molded applications). A better match in rheological properties facilitates layer uniformity within a parison, resulting in more consistent final products.
• Plastics have long been used for various container applications due to their light weight, ready availability, relatively low cost to produce and high strength.
• Polyolefin resins have proven particularly useful for such applications. While polyolefin resins possess many desired properties, they are not particularly effective as a barrier to gases or vapors of chemicals such as hydrocarbons, alcohols, ketones, ethers, etc. Thus, polyolefin resins by themselves are not suitable for many applications where containment of chemical vapors is critical for environmental or safety reasons. These applications include fabricated articles such as storage or transportation containers or vessels, for example, fuel tanks, conduits or membranes.
• the adhesive layer comprises a resin such as a modified polyethylene prepared by grafting an unsaturated carboxylic acid or a derivative thereof to high-density polyethylene (HDPE).
• a resin such as a modified polyethylene prepared by grafting an unsaturated carboxylic acid or a derivative thereof to high-density polyethylene (HDPE).
• one aspect of the invention is an improved resin comprising polyethylene terephthalate and High Density polyethylene modified with maleic anhydride (HDPE-g-MAH), wherein the polyethylene terephthalate comprises 90 to 98 percent of the composition, the modified polyethylene comprises 10 to 2 percent of the composition, and the maleic anhydride comprises from 0.5 to 5.0% percent by weight of the modified polyethylene.
• HDPE-g-MAH High Density polyethylene modified with maleic anhydride
• This new resin can be advantageously used in multilayer structures as it will allow the elimination of adhesive or tie layers.
• Barrier layers comprised of the resin of the invention will adhere much better to other layers, including polyolefinic support layers, eliminating the necessity of an adhesive or tie layer.
• the resin of the current invention allows 2 or three layer structures.
• adhesion between PET and a tie layer will be improved if the PET is first modified by the incorporation of high density polyethylene-grafted-maleic anhydride.
• another aspect of the invention is a multilayer plastic container comprising two layers, one of which is a gas-barrier layer, the other of which is a polyolefinic support layer, wherein the barrier layer includes an amount of modified high-density polyethylene, wherein the modified high-density polyethylene is prepared by grafting an unsaturated carboxylic acid or a derivative thereof to the high-density polyethylene, the modified high-density polyethylene being added in an amount such that the gas-barrier layer sufficiently adheres to the adjacent layer.
• another aspect of the invention comprises a method of improving the adherence properties of the barrier layer (which can be crystalline polyesters, crystalline polyamides, crystalline polyarylates and crystalline poly(ethylene-co-vinyl alcohol) resins) to polyolefinic materials comprising incorporating a modified polyethylene prepared by grafting an unsaturated 5 carboxylic acid or a derivative thereof to the polyethylene, wherein the modified polyethylene is added to the polyethylene terephthalate in an amount between 2% and 10% percent by weight, preferably in an amount between 3% and 8% by weight.
• the barrier layer which can be crystalline polyesters, crystalline polyamides, crystalline polyarylates and crystalline poly(ethylene-co-vinyl alcohol) resins
• the polyethylene material is preferably high density polyethylene and the modified polyethylene is a modified high density polyethylene.
• coextrusion blow-molding is the preferred method of manufacture for multilayered fabricated articles. This method requires a sufficient rheological match between the constituent materials in order to promote adequate layer uniformity within the annular parison dye.
• Conventional PET, as well as other conventional polyesters, such as poly(butylene terephthalate), poly (ethylene naphthalate), polylactic acid, polyester copolymers5 containing the terephthalate moiety, and liquid crystalline polyarylates exhibits fairly newtonian behavior in the melt whereas HDPE resins behave decidedly non-newtonianly.
• the improved barrier resin of the present invention comprises a base resin which can be crystalline polyesters, crystalline polyamides, crystalline polyarylates or crystalline poly(ethylene-co-vinyl alcohol) resins together with a minor amount of a modified high-density 5 polyethylene (HDPE).
• the HDPE is modified with unsaturated carboxylic acid or derivative thereof, such as maleic anhydride, acrylic acid etc.
• the improved barrier resin comprises 90 to 98 percent of the base resin, and 10 to 2 percent of the modified polyethylene.
• the modified polyethylene comprises from 0.5 to 5.0 percent by weight (preferably 0.5 to 1.4 percent) of the unsaturated carboxylic acid or derivative.
• the resin of the present invention exhibits improved adherence as compared to unmodified PET, while maintaining its barrier properties.
• the resin of the present invention can be advantageously used in multilayer plastic container having at least two layers, one of which is a gas-barrier layer, the other of which is a polyolefinic support layer.
• multilayer plastic container having at least two layers, one of which is a gas-barrier layer, the other of which is a polyolefinic support layer.
• Such containers are described in US-A-5,441,781.
• Suitable polyolefinic materials are described US-A-5,380,810, U.S. Pat application 08/857,817, or U.S. Pat. Application 08/857,816.
• the preferred material to be used in the support layer is HDPE.
• the containers of the present invention can consist of only two layers, but additional layers may advantageously be used. For example, it may be desired that two support layers surround the barrier layer such that the support layers are in contact both with the contents of the container and the outside environment to which the container is exposed.
• tie-layers allow tie-layers to be eliminated in most cases, in certain applications, superior adherence between the layers may be desired, in which case the use of a tie layer may still be preferred.
• the resins of the present invention improve the adherence of the barrier layer to a support layer, it will also improve the adherence of the barrier layer to a tie layer.
• Preferred tie layers to be used in the present invention include those described in the '781 patent.
• the multilayer containers which are an example of the present invention, may be produced by any means known in the art. This includes blow molding as well as coextruding sheets followed by thermoforming with or without welding of the two or more parts to form the containers. Blow molding methods, are generally preferred.
• resins for each layer can be separately plasticized in two or more extruders, introduced into the same die, laminated in the die while leveling each thickness to prepare a parison having the appearance of being one-layered. The parison can then be inflated in a mold by application of inner pressure of air so that the parison is brought into contact with the mold and cooled.
• Base polyesters which can be altered in this way include PET, poly (butylene terephthalate), poly (ethylene naphthalate), polylactic acid, polyester copolymers containing the terephthalate moiety, and liquid crystalline polyarylates.
• Long chain branching can be promoted by incorporating multifunctional monomers within the initial polymerization, or by post reactor modification such as reactive extrusion with a multi-functional branching agent.
• These processes are generally known in the art (see for example, US-A-5,536,793; US-A-5,556,926; US-A-5,422,381; US-A-5,362,763, and US-A-5,422,381).
• Potential branching agents known in the art include trimellitic anhydride, trimesic anhydride, phthalic anhydride, pyromellitic dianhydride (PMDA) and any monomers containing 3 or more hydroxyl groups. Reactive extrusion using PMDA is a preferred method of promoting long chain branches.
• the branching agent should be added at a level to avoid significant cross linking and/or gel formation. Less than 1% by weight of the branching agent is preferred.
• additives which are good nucleating agents may be used to promote the crystallization of the branched polyester, to help compensate for the fact that crystallization of branched materials are generally less thermodynamically favored compared to linear materials.
• Suitable nucleating agents are well known in the art (see, for example, US-A-4,572,852; US-A-5 ,431,972; US-A-5,843,545; or US-A-5,747,127).
• a particularly favored embodiment of the present invention comprises a multilayered article comprising at least a barrier layer and a support layer.
• the support layer is preferably HDPE
• the barrier layer comprises polyethylene terephthalate with long chain branching with a relatively small amount of HDPE to which a small amount of maleic anhydride has been grafted.
• the article in this particularly favored embodiment is prepared by coextrusion blow molding. Such an article would be especially well suited for use as a fuel tank compatible for use with oxygenated fuels.
• the barrier properties of the barrier layer are largely dependent upon the percent crystallinity (X c ) of the polymer which makes up the barrier layer.
• X c percent crystallinity
• the polymer in the finished container exhibit greater than 8 per cent, more preferably 21 percent and most preferably 34 percent crystallinity, and preferably no more than 50 per cent, more preferably no more than 40% as measured by Differential Scanning Calorimetry. It is expected that other barrier resins will exhibit similar relationship between barrier properties and amount of crystallinity. Crystallinity of these barrier resins can be altered by those means known in the art, such as controlling the cooling rate and or annealing.
• crystallinity can be affected by certain fuel components, such as methanol.
• Methanol is known to disrupt hydrogen bonding of EVOH and thereby reduce the barrier performance of EVOH.
• PET In the case of PET, however, we have discovered, that methanol can cause solvent-induced crystallization which raises the level of crystallinity and therefore further improves the barrier performance.
• the hydrogen bonding in EVOH is also known to be disrupted by moisture, whereas the barrier performance of PET is not effected by moisture. This has particular consequences in the overall construction and design of multilayer fuel container structures. EVOH should be precluded from being in direct contact with a fuel layer which contains moisture or methanol. PET, on the other hand, does not exhibit the same drawbacks, and can be in direct contact with the fuel.
• PET1 is conventional PET (LighterTM L90A from The Dow Chemical Company), having an inherent viscosity of 0.77, determined at 0.5% concentration (w/v) and 23 °C in phenol/ 1 ,2-dichlolobenzene solution (60/40 by weight) .
• PET2 is a modified PET prepared by reactively extruding PET1 with 0.45 % by weight pyromellitic dianhydride (PMDA), followed by solid state advancement for 14 hours at a temperature of 196°C.
• PMDA pyromellitic dianhydride
• GPC-DV was used to analyze the resulting polymer and it was determined that PET2 exhibited an increase in weight average molecular weight (from 46 to 135 kg/mol), a broader polydispersity index (from 1.9 to 5.3) as compared to PET 1.
• PET2 had an inherent viscosity of 2.28, determined at 0.5% concentration (w/v) and 23°C in phenol/1, 2- dichlolobenzene solution (60/40 by weight).
• PET3 is a nucleated PET (VersatrayTM 12822 from Eastman Chemical Company), having an inherent viscosity of 0.89, determined at 0.5% concentration (w/v) and 23°C in phenol/tetrachloroethane solution (60/4,0 by weight).
• the following examples were prepared to demonstrate the improved cohesiveness of multilayer articles where the barrier layer includes a modified polyolefin according to the present invention.
• the multilayer bottles were prepared on a Bekum BM-502 Blow Molding machine, running at a production rate of approximately 42 pounds per hour. Bottle weight was approximately 60 g (total shot weight 85-90 g).
• the PET barrier layer was the inner layer, and in all cases exhibited a melt temperature of approximately 254°C.
• the support layer in each case was HDPE (LupolenTM 4261 A HDPE obtained from BASF).
• the tie layer if present was ADMERTM SF-700, an EVA base adhesive obtained from Mitsui Petrochemicals. The results of these evaluations are shown in table I.
• the melt viscosity of HDPE (LupolenTM 4261A HDPE obtained from BASF), PET1, PET2 and PET3 were then characterized using a Rheometrics RMS800 equipped with a parallel plate fixture and configured to operate in the linear viscoelastic regime.
• the data is reproduced in figure 1 and indicates that PET2, exhibits similar rheology to HDPE, and substantially different than PET1 or PET3.
• the permeability of Fuel CM 15 through free standing films of the barrier materials is measured at 41°C (+/-1°C) using the following procedure.
• a test film, 4 inch diameter disk with a thickness between 1 and 100 mil, is mounted between the two chambers of the test cell.
• Fuel CM15 (mixture comprising 42.5/42.5/15 volume % of toluene/isooctane/methanol, 95 mL) is added to the upper chamber, layering on top of the test specimen film, and helium flowing at 10 mL/min is passed through the lower chamber.
• helium flowing at 10 mL/min is passed through the lower chamber.
• As fuel permeates through the barrier film into the lower chamber it is swept in a helium stream from the test cell and through an injector loop of a gas chromatograph (GC).
• GC gas chromatograph
• the contents of the injector loop are injected onto the front end of a 25 m, 0.53 mm ID, Chrompack Poraplot-U capillary column operating at 140°C using a helium flow of 10 mL/min as the carrier gas.
• the GC separates, identifies by retention time, and quantifies the fuel components which have permeated through the specimen film.
• the date and time of the injection, permeant identities and peak raw area counts of the permeated components are stored in a computer file for further analysis.
• 16 helium sample streams are monitored by the GC; each stream is tested for fuel component content at an eight-hour interval. Fifteen of the 16 sample streams are connected to specimen film permeation cells.
• the sixteenth stream is from a gas cylinder containing a reference mixture of 50 ppm each of toluene, isooctane, and methanol, with a make up of helium.
• the reference gas data is used to calibrate the GC raw area counts data to determine the ppm levels of the fuel components in the sample streams from the permeation cells.
• the specimen test films were prepared by compression molding using a 6 inch by 6 inch by 5 mil thick mold in a Pasadena Hydraulics, Inc. Press.
• the EVOH material was EvalTM F101A, with 32 mol percent ethylene.
• the EVOH was compression molded using the following conditions: 1) melt resin in the mold for 4 minutes at 1000 pounds applied pressure at 210°C; 2) press resin for 6 minutes at 40,000 pounds applied pressure at 210°C; and 3) cool the mold slowly, over one hour, to 50°C under 40,000 pounds applied pressure.
• the PET resins were molded under similar conditions except that in step 1, the mold was heated to 280°C.

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• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Mechanical Engineering (AREA)
• Laminated Bodies (AREA)
• Containers Having Bodies Formed In One Piece (AREA)

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• 2001
  • 2001-05-11 WO PCT/US2001/015431 patent/WO2001092007A2/en not_active Application Discontinuation
  • 2001-05-11 KR KR1020027016156A patent/KR20030007740A/ko not_active Application Discontinuation
  • 2001-05-11 BR BR0111663-0A patent/BR0111663A/pt not_active Application Discontinuation
  • 2001-05-11 MX MXPA02011932A patent/MXPA02011932A/es not_active Application Discontinuation
  • 2001-05-11 CN CN01810282A patent/CN1431954A/zh active Pending
  • 2001-05-11 CA CA002408229A patent/CA2408229A1/en not_active Abandoned
  • 2001-05-11 EP EP01935425A patent/EP1289753A2/en not_active Withdrawn
  • 2001-05-11 AU AU2001261524A patent/AU2001261524A1/en not_active Abandoned
  • 2001-05-11 JP JP2001588001A patent/JP2003534946A/ja active Pending

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