AU603175B2 - Creación de Inventos y Patentes con Inteligencia Artificial

AU603175B2 – Polymeric multilayer sheet suitable for the manufacture of microwaveable containers
– Google Patents

AU603175B2 – Polymeric multilayer sheet suitable for the manufacture of microwaveable containers
– Google Patents
Polymeric multilayer sheet suitable for the manufacture of microwaveable containers

Download PDF
Info

Publication number
AU603175B2

AU603175B2
AU10283/88A
AU1028388A
AU603175B2
AU 603175 B2
AU603175 B2
AU 603175B2
AU 10283/88 A
AU10283/88 A
AU 10283/88A
AU 1028388 A
AU1028388 A
AU 1028388A
AU 603175 B2
AU603175 B2
AU 603175B2
Authority
AU
Australia
Prior art keywords
propylene polymer
sheet
layer
filled
container
Prior art date
1987-01-15
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.)

Ceased

Application number
AU10283/88A
Other versions

AU1028388A
(en

Inventor
Louis J. Marsella
Frederick C. Newman
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.)

Continental Can Co Inc

Original Assignee
Continental Can Co 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.)
1987-01-15
Filing date
1988-01-14
Publication date
1990-11-08

1988-01-14
Application filed by Continental Can Co Inc
filed
Critical
Continental Can Co Inc

1988-07-21
Publication of AU1028388A
publication
Critical
patent/AU1028388A/en

1990-11-08
Application granted
granted
Critical

1990-11-08
Publication of AU603175B2
publication
Critical
patent/AU603175B2/en

2008-01-14
Anticipated expiration
legal-status
Critical

Status
Ceased
legal-status
Critical
Current

Links

Espacenet

Global Dossier

Discuss

Classifications

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

B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives

B32B27/20—Layered products comprising a layer of synthetic resin characterised by the use of special additives using fillers, pigments, thixotroping agents

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

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

B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers

B32B27/302—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising aromatic vinyl (co)polymers, e.g. styrenic (co)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

B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins

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

B65D81/00—Containers, packaging elements, or packages, for contents presenting particular transport or storage problems, or adapted to be used for non-packaging purposes after removal of contents

B65D81/34—Containers, packaging elements, or packages, for contents presenting particular transport or storage problems, or adapted to be used for non-packaging purposes after removal of contents for packaging foodstuffs or other articles intended to be cooked or heated within the package

B65D81/3446—Containers, packaging elements, or packages, for contents presenting particular transport or storage problems, or adapted to be used for non-packaging purposes after removal of contents for packaging foodstuffs or other articles intended to be cooked or heated within the package specially adapted to be heated by microwaves

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

B32B2307/00—Properties of the layers or laminate

B32B2307/70—Other properties

B32B2307/724—Permeability to gases, adsorption

B32B2307/7242—Non-permeable

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

B32B2307/00—Properties of the layers or laminate

B32B2307/70—Other properties

B32B2307/732—Dimensional properties

B32B2307/734—Dimensional stability

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

B32B2323/00—Polyalkenes

B32B2323/04—Polyethylene

B32B2323/046—LDPE, i.e. low density polyethylene

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

B32B2323/00—Polyalkenes

B32B2323/10—Polypropylene

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

B32B2325/00—Polymers of vinyl-aromatic compounds, e.g. polystyrene

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

B32B2439/70—Food packaging

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]

Y10T428/1372—Randomly noninterengaged or randomly contacting fibers, filaments, particles, or flakes

Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC

Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

Y10T428/00—Stock material or miscellaneous articles

Y10T428/25—Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles

Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC

Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

Y10T428/00—Stock material or miscellaneous articles

Y10T428/31504—Composite [nonstructural laminate]

Y10T428/31855—Of addition polymer from unsaturated monomers

Y10T428/31909—Next to second addition polymer from unsaturated monomers

Y10T428/31913—Monoolefin polymer

Description

S iN 1 0 DLLa AMy ENDME:NTS r ACC» IZD-‘ :i
AUSTRALIA
PATENTS ACT 1952 COMPLETE SPECIFICATION 03 175 Form
(ORIGINAL)
FOR OFFICE USE Short Title: Int. Cl: Application Number: Lodged: Complete Specification-Lodged: Accepted: Lapsed: Published: Priority: Related Art: 6 r ,r Br r TO BE COMPLETED BY APPLICANT Name of Applicant: Address of Applicant: CONTINENTAL CAN COMPANY, INC.
800 CONNECTICUT AVENUE
NORWALK,
CONNECTICUT 06856
USA
CLEMENT HACK CO., 601 St. Kilda Road, Melbourne, Victoria 3004, Australia.
Actual Inventor: Address for Service: p 0 Complete Specification for the invention entitled: POLYMERIC MULTILAYER SHEET SUITABLE FOR THE MANUFACTURE OF MICROWAVABLE CONTAINERS The following statement is a full description of this invention including the best method of performing it known to me:- 11 e POLYMERIC MULTILAYER SHEET SUITABLE FOR THE MANUFACTURE OF MICROWAVEABLE CONTAINERS Background of the Invention 1. Field of the Invention This invention relates to a multilayer sheet material suitable for the packaging of foodstuffs and more particularly to a polymeric multilayer sheet material particularly adapted S for use in making containers for food products to be cooked or reheated in microwave ovens.
I s 2. The Prior Art The widespread popularity of microwave ovens has initiated interest in a plastic container which can be used for the packaging of foods and which can withstand the temperature demands of cooking and reheating the food product in microwave ovens. Microwave ovens are popular with consumers because of the speed at which such ovens can cook or reheat food.
Containers used in microwave ovens are heated only by the heat conducted from the food being cooked. Although the temperature demands of microwave cooking are less than that of conventional ovens, the temperatures that are generated from the food product still deleteriously affect the dimensional stability of containers formed from single or multilayer plastic sheets thermoformed from polyolefinic materials such as propylene polymers and copolymers.
a: In addition to plastic containers made solely from polyolefinic materials as just described, the art also has under consideration containers for the packaging of oxygen-sensitive foods intended for storage under non-refrigerated conditions which can be subject to microwave conditions. These containers are formed from .multilayer sheets constructed of an inner barrier layer, juxtaposed adhesive layers on both sides of the barrier layer and outer layers of a polyolefin. For example, British patent No.
1,379,106 discloses a five-layer sheet comprised of an inner gas barrier layer formed of a copolymer of vinylidene chloride 0e S* and vinyl chloride, an ethylene/vinyl acetate copolymer *0 adhesive layer on either side of the barrier layer and an 9* outer layer of a polyolefin such as polyethylene, polypropylene or ethylene/propylene copolymer. The multilayer sheets are disclosed as being ideally suited for making containers of a variety of forms for products that are sensitive to oxygen.
The multilayer sheets of the prior art are conventionally made in a single process step by coextruding two or more polyolefinic layers and intermediate layers comprised of an s* adhesive tie layer material into a continuous sheet to form a unitary structure. In the case of multilayer gas barrier sheets, an inner layer of a gas barrier material is coextruded with the polyolefinic and adhesive layers.
A multilayer sheet structure having gas barrier properties which has been found particularly suitable for the manufacture of plastic containers used for the packaging of oxygen 3 sensitive food products is constructed of an inner gas barrier layer such as ethylene vinyl alcohol (EVOH) or vinylidene chloride polymer (SARAN), first and second adhesive tie layers applied to each side of the barrier layer, a first outer layer of low or high density polyethylene, bonded to the first adhesive layer and a propylene polymer or styrene polymer layer bonded to the second adnesive layer.
Containers thermoformed from such multilayer gas barrier sheet are utilized in the packaging of oxygen-sensitive food products which are intended for storage under non-refrigerated conditions. In such application, the containers are formed :I using a sterile multilayer gas barrier film, and while in a still heated state from the forming station are filled with sterile food product in a filling station inside a sterile enclosure. The filled containers are then sealed without it
S.
being possible for their contents to be contaminated by a non-sterile atmosphere with a lid sheet whereof at least the side of the lid facing the inside of the containers is sterile. A specific method which may be utilized for sterile packaging of the type generally described above is disclosed in U.S. 4,287,802.
Multilayer sheets of the non-barrier and gas barrier type can be converted to containers using conventional thermoplastic forming techniques such as thermoforming. In thermoforming, the multilayer sheet material is thermoformed by feeding the sheet from roll stock past a heating station where the sheet is heated, usually by passage through an oven or overhead radiant heaters or a conbination of both and the -rsl-cl– «u _iI_ i i 3 Iheated sheet passes directly to a thermoforming machine which forms the container. Any suitable thermoforming technique such as vacuum forming, pressure forming, plug assist or mechanical forming or any combination of such techniques can be used in the forming of the containers but in all cases the sheet material is preheated generally to temperature of about 375 0 F to about 425 0 F to effect a degree of softening of the material so that it can be easily thermoformed into containers having uniform sidewalls of the desired thickness.
One drawback to the plastic containers formed from multilayer sheet of the types above described is that the containers are not microwaveable, i.e. the containers when filled with food product and exposed to heating in a microwave oven exhibit poor dimensional stability and often undergo distortion and shrinkage.
Summary of the Invention In accordance with the present invention there is provided P[s c Sa multilayer sheet suitable for the manufacture of 4c-Econtainers which can withstand exposureto microwave heating of the food productwithout significant loss of dimensional 1 W-5’ be s O eQst- oz stability, wherein the multilayer )sheet Le- comprised of A layer of a propylene polymer bonded to a styrene polymer layer, the propylene polymer having incorporated therein about cboOd to 40 percent by weight of an inorganic filler, the filled propylene polymer and styrene polymer layers having a melt flow substantially equal to the other and the filled propylene and styrene polymer layers having a thickness ratio in the range of about 60:40 to abeot 40:60.
Containers thermoformed from the multilayer sheet prepared in accordance with the present invention can withstand heating in microwave ovens without significant loss of dimensional stability.
Detailed Description of the Invention In accordance with the present invention the multilayer sheet structures hereof are conveniently made by lamination of the individual layers of the sheet simultaneously, as by coextrusion.
‘*o The term «propylene polymer» as used in the present application includes within its meaning homopolymers of propylene and copolymers of propylene with other ethylenically unsaturated monomers such as ethylene..
S
The propylene polymer layer may be from about 10 to I.:g mils thick and preferably about 15 to 25 mils thick.
The term «styrene polymer» includes the vinyl aromatic or styrenic polymers including substituted and unsubstituted styrene polymers and copolymers and high impact polystyrenes comprised of styrene/rubber blends and copolymers. A high impact styrene polymer available commercially under the trade 3 mark designation Mobil 4600 having a melt flow of about 2.7 S g/10 min. (ASTM test method D1238) has been found suitable as the styrene layer in the multilayer sheet constructions of the present invention. Generally high impact styrene polymers useful in the practice of the present invention have a melt flow in the range of about 1.5 to about 3.0 g/10 min. (ASTM test method D1238), and preferably about 2.0 to about 2.8 min.
It is critical to the practice of the present invention that the thickness ratio of the filled propylene polymer layer to the styrene polymer layer be about 60:40 to about 40:60 and preferably about 50:50.
The filler incorporated in the propylene polymer composition used in the manufacture of the multilayer sheet of the present invention generally comprises about 20 to about Spercent by weight of the propylene polymer composition. The filler has preferably a laminated structure and is preferably S* used in a finely divided form, i.e. an average particle size I of about 5 to about 15 microns. Suitable filler materials include silica and talc with talc being preferred. The propylene polymer compositions filled with about 20 to about 40 percent by weight filler useful in the. practice of the present invention have a melt flow in the range of about to about 3.0 g/10 min. (ASTM test method D1238) and preferably about 2.0 to 2.5 g/min.
Multilayer gas barrier sheet useful in the preparation of micorwavable plastic containers in accordance with the practice of the present invention are generally comprised of an inner gas barrier layer, an outer layer of a first h.
polyolefin composition bonded to one of the barrier surfaces, an outer layer of a propylene polymer bonded to the other surface of the barrier layer and a styrene polymer layer bonded to the propylene polymer layer, the propylene layer having incorporated therein about 20 to about 40 percent by weight of the filler, the filled propylene polymer and styrere polymer layers having a melt flow substantially equal to the other, both being in the range of about 1.5 to about 3.0 g/min (ASTM test method 01238) and the thickness ratio of the filled propylene polymer layer to the styrene polymer layer being in the range of about 60:40 to 40:60 and preferably about 50:50.
4* In the preparation of the multilayer gas barrier sheet the outer first polyolefin layer may be from about 5 to about S* mils thick and is preferably from about 8 to about 10 mils thick, By the term «polyolefin» as used herein is meant a 0 polyethylene, polypropylene and random copolymers of ethylene and/or propylene with less than 50 percent by weight of other ethylenically unsaturated monomer or block copolymers of ethylene and propylene with less than 50 percent by weight of the other copolymer. Polyethylene, either low or high density S polyethylene, is preferred as the composition of the first polyolefin outer layer.
A wide variety of barrier materials may be employed as the inner barrier layer of the multilayer gas barrier sheet in accordance with the present invention. Particularly advantageous and beneficial are compositions of vinylidene chloride polymers, wherein the polymers contain at least weight percent vinylidene chloride, the remainder being one or i i i i ~I~C~ more ethylenically unsaturated monomers copolymerizable therewith such as vinyl chloride. Ethylene vinyl alcohol copolymers are derivdd from hydrolyzed ethylene vinyl acetate copolymers containing from 15 to 65 mole percent ethylene and to 35 mole percent of vinyl acetate.
The inner barrier layer may be from about 2 to about mils in thickness and is most advantageously from about 3 to about 5 mils thick.
In constructing the multilayer barrier sheet of the 0. present invention the inner barrier layer, first polyolefin layer, propylene polymer layer and styrene polymer layer may be bonded by interposed layers of a suitable adhesive. The adhesive layers may vary in thickness from about 0.5 to about 2 mils, however, generally the preferred thickness of any adhesive layer is about 0.75 to about 1.5 mils.
A wide variety of polymers and polymeric compositions are Suseful as adhesive layers to provide adhesion between the various layers of the sheet. Suitable polymers or polymeric compositions which may be employed are copolymers of ethylene and vinyl acetate, advantageously in proportions of from 14 weight percent to 40 weight percent vinyl acetate with from 86 weight percent to 60 weight percent ethylene, and copolymers of ethylene with isobutyl acrylate, advantageously in proportions of from 10 to 30 weight percent isobutyl acrylate with from 80 to 70 weight percent of ethylene.
It is also critical to the practice of the present invention that the propylene polymer used in the construction of the multilayer sheet have incorporated therein about 20 to about 40 percent by weight of a filler and that the filled propylene polymer layer and the styrene polymer layer have a melt flow ttha is suostantially equal to the other. Generally the melt flow of the filled propylene polymer and styrene polymer compositions is in the range of about 1.5 to about minutes (ASTM test method 01238) and preferably about to about 2.8 g/min.
As will hereinafter be illustrated, if concentrations of SO filler outside the ranges specified above are incorporated in the propylene polymer composition, and if the thickness ratio of the filled propylene polymer to styrene polymer is outside the range of 60:40 to 40:60, the multilayer sheet formed using these compositions will exhibit poor formability properties, a. such as wall thickness variation, poor conformity to the mold cavity and once thermoformed, the containers prepared .therefrom will exhibit distortion and excessive shrinkage when exposed to microwave conditions.
Tnis invention is illustrated by the following examples: EXAPLE 1.
A multilayer sheet was prepared by coextrusion of an inner barrier layer composed of about 82 weight percent vinylidene chloride and about 18 weight percent vinyl chloride, adhesive layers applied to opposite sides of the barrier layer comprised of an ethylene-vinyl acetate copolymer containing 28 IQ ~il~-l:~Cr -CYU /o weight percent vinyl acetate, an outer layer of a low density polyethylene bonded to one surface of the barrier layer through an intermediate adhesive layer, a propylene copolymer filled with 30 percent by weight talc (average particle size 8 microns) having a melt flow of 2.2 g/10 min. (ASTM test method D1238) bonded to the other surface of the barrier layer through an intermediate adhesive layer and a high impact polystyrene composition (Mobil 4600) having a melt flow of 2.7 g/min. adhered through an intermediate adhesive layer to the filled polypropylene layer. The polyethylene layer was mils thick. The filled polypropylene and high impact polystyrene layers were each 17 mils thick, the inner barrier layer was 4.0 mils thick, and ‘the adhesive layers were each 1.0 mil thick. The molten polymers were coextruded from a conventional extruder through a flat sheet die, the melt streams being combined in a coextrusion block prior to being *9 extruded from the die.
To prepare containers, the finished multilayer coextrudate was preheated to about 375 0 F and thermoformed into flanged eight ounce cups having a sidewall thickness of 12 18 mils, with the low density polyethylene layer forming the food contact side of the cup, using conventional thermoforming equipment.
The multilayer sheet exhibited excellent formability properties, namely, cups thermoformed from the sheet had uniform wall thickness and conformity to the mold cavity.
The thermoformed cups when filled with water and the water heated to boiling in a Litton microwave oven having an output of 1600 watts did not exhibit any distortion, shrinkage, or any other sign of dimensional instability. The cups fileo with water and sealed with a flexible plastic membrane also exhibited excellent abuse strength, when subjected to a Drop Test, i.e. the filled cup being dropped from an inclined surface (150 angle) of 41 inches in length striking a base plate at a 900 angle to the direction of fall, the cups did *not split or rupture.
.m By way of contrast when the procedure of Example 1 was repeated with the exception that the thickness of the filled polypropylene layer was 9 mils and the thickness of the high impact polystyrene layer was 25 mils or a thickness ratio of 74:26, the microwaveability of containers thermoformed from the multilayer sheet was significantly reduced, namely the containers distorted when subjected to exposure in a microwave oven. Abuse strength was poor, that is, many of the cups filled with water and sealed with a plastic membrane ruptured when subjected to the Drop Test.
By way of contrast when the procedure of Example 1 was repeated with the exception that the thickness of the polypropylene layer was 25 mils and the high impact polystyrene layer was 9 mils, or a thickness ratio of 26:74, containers formed from the multilayer sheet were difficult to thermoform and had non-uniform wall thickness.
without significant loss of dimensional stability, t; h. /2 By way of further contrast when the procedure of Example 1 was repeated with the exception that a talc concentration in excess of 40 percent by weight was incorporated in the polypropylene layer, the multilayer sheet exhibited poor formability during thermoforming operations.
Example 2.
The procedure of Example 1 was repeated with the exception that the polyethylene and barrier layers were absent from the multilayer structure and the multilayer sheet was constructed primarily of high impact polystyrene bonded to the filled polypropylene layer through an intermediate ethylene vinyl acetate copolymer adhesive layer. The thickness of the high impact polystyrene layer was 23 mils, the thickness of the EVA adhesive layer was 1 mil and the thickness of the filled polypropylene layer was 23 mils.
S»
The multilayer sheet was readily thermoformed into cups of uniform wall thickness and conformity to the mold cavity.
b 1 1 I 1

Claims (1)

46. 0. go: a g 5 S S @650 S 9* S THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS: 1. A multilayer plastic sheet suitable for the manufacture of containers which can withstand exposure to microwave heating of product contained therein without significant loss of dimensional stability, the sheet being comprised of at least one layer of a propylene polymer bonded to a styrene polymer layer, the propylene polymer layer having incorporated therein about 20 to about 40 percent by weight of an inorganic filler, the filled propylene polymer and styrene polymer layers having melt flows substantially equal to the other and the thickness of the layers being at a ratio of about 60:40 to 40:60. 2. The sheet of claim 1 wherein the filler is talc. 3. The sheet of claim 1 wherein the propylene polymer is polypropylene. 4. The sheet of claim 1 wherein the styrene polymer is high impact polystyrene. S The sheet of claim 4 propylene polymer and in the range of about 6. The sheet of claim 4 propylene polymer and in the range of about wherein the melt flow of the filled the high impact polystyrene are both 1.5 to about 3.0 g/10 min. wherein the melt flow of the filled the high impact polystyrene are both 2.0 to about 2.8 g/10 min. as propylene polymers and copolymers.. 7. A plastic container which can withstand exposure to microwave heating of product contained therein without significant loss of dimensional stability, the container being formed from a multilayer sheet comprised of at least one layer of a propylene polymer bonded to a styrene polymer layer, the propylene polymer layer having incorporated therein about 20 to 40 percent by weight of an inorganic filler, the filled propylene polymer and styrene polymer layers having melt flows substantially equal to the other and the thickness of the layers being at a ratio of about 60:40 to 40:60. 8. The container of claim 7 wherein the filler is talc. OS S The container of claim 7 wherein the propylene polymer is polypropylene. S*00 10. The container of claim 7 wherein the styrene polymer is high impact polystyrene. 11. The container of claim 10 wherein the melt flow of the filled propylene polymer and the high impact polystyrene are both in the range of about 1.5 to about 3.0 g/10 min. 12. The container of claim 10 wherein the melt flow of the filled propylene polymer and the high impact polystyrene are in the range of about 2.0 to about 2.8 g/10 min. Dated this 9th day of July, 1990 CONTINENTAL CAN COMPANY, INC. By Its Patent Attorneys GRIFFITH HACK CO. Fellows Institute of Patent Attorneys of Australia. /^A v-i l^ n^/ i,

AU10283/88A
1987-01-15
1988-01-14
Polymeric multilayer sheet suitable for the manufacture of microwaveable containers

Ceased

AU603175B2
(en)

Applications Claiming Priority (2)

Application Number
Priority Date
Filing Date
Title

US003437

1987-01-15

US07/003,437

US4879147A
(en)

1987-01-15
1987-01-15
Polymeric multilayer sheet suitable for the manufacture of microwaveable containers

Publications (2)

Publication Number
Publication Date

AU1028388A

AU1028388A
(en)

1988-07-21

AU603175B2
true

AU603175B2
(en)

1990-11-08

Family
ID=21705869
Family Applications (1)

Application Number
Title
Priority Date
Filing Date

AU10283/88A
Ceased

AU603175B2
(en)

1987-01-15
1988-01-14
Polymeric multilayer sheet suitable for the manufacture of microwaveable containers

Country Status (6)

Country
Link

US
(1)

US4879147A
(en)

EP
(1)

EP0275102A3
(en)

JP
(1)

JPS63288748A
(en)

AU
(1)

AU603175B2
(en)

CA
(1)

CA1308873C
(en)

MX
(1)

MX167530B
(en)

Families Citing this family (19)

* Cited by examiner, † Cited by third party

Publication number
Priority date
Publication date
Assignee
Title

US5861201A
(en)

1994-02-15
1999-01-19
Owens-Illinois Labels Inc.
Multilayer label material

US5935847A
(en)

1994-10-28
1999-08-10
Baxter International Inc.
Multilayer gas-permeable container for the culture of adherent and non-adherent cells

ATE180716T1
(en)

1995-11-04
1999-06-15
Tetra Laval Holdings & Finance

PAPER-LIKE AND THERMOFORMABLE MULTI-LAYER BARRIER FILMS

US6117553A
(en)

1996-11-28
2000-09-12
Sumitomo Chemical Company, Limited
Multi-layer self-tack wrapping film

GB9705921D0
(en)

1997-03-21
1997-05-07
Courtaulds Packaging Ltd
Laminated materials and containers therefrom

SE519445C2
(en)

2000-08-28
2003-02-25
Tetra Laval Holdings & Finance

Packaging laminates comprising paper or cardboard backing layers and a mineral-filled polyolefin layer, and packaging containers made therefrom

US7168581B2
(en)

2001-12-21
2007-01-30
Rexam Medical Packaging Inc.
Closure for a retort processed container having a peelable seal

US20040164076A1
(en)

2002-06-18
2004-08-26
Baker Loren G.
Lidded container with linear brim segments and medial sealing beads

US20050011898A1
(en)

2002-06-18
2005-01-20
Van Handel Gerald J.
Sealable portion cups and lids therefor

US7644902B1
(en)

2003-05-31
2010-01-12
Rexam Medical Packaging Inc.
Apparatus for producing a retort thermal processed container with a peelable seal

US7798359B1
(en)

2004-08-17
2010-09-21
Momar Industries LLC
Heat-sealed, peelable lidding membrane for retort packaging

JP4569272B2
(en)

2004-11-12
2010-10-27
タカタ株式会社

Airbag device

US7780024B1
(en)

2005-07-14
2010-08-24
Rexam Closures And Containers Inc.
Self peel flick-it seal for an opening in a container neck

US8100277B1
(en)

2005-07-14
2012-01-24
Rexam Closures And Containers Inc.
Peelable seal for an opening in a container neck

US8251236B1
(en)

2007-11-02
2012-08-28
Berry Plastics Corporation
Closure with lifting mechanism

USD645737S1
(en)

2010-08-30
2011-09-27
Dixie Consumer Products Llc
Sealable snack container

USD645339S1
(en)

2010-08-30
2011-09-20
Dixie Consumer Products Llc
Sealable snack container

US9474420B2
(en)

2010-08-30
2016-10-25
Dixie Consumer Products Llc
Sealable snack container

MX2019002450A
(en)

2018-03-05
2019-09-06
Dart Container
Polyolefin-based composition for a lid and methods of making and using.

Citations (3)

* Cited by examiner, † Cited by third party

Publication number
Priority date
Publication date
Assignee
Title

US3589976A
(en)

1967-03-24
1971-06-29

Hercules Inc

Composite films of polyolefins and polystyrene

GB1420612A
(en)

1971-12-03
1976-01-07

Unilever Ltd

Laminated plastics film

US4464439A
(en)

1981-03-12
1984-08-07

Montefina S.A.

Co-extruded laminate consisting of at least one sheet of polypropylene and at least one sheet of polymeric material based on high-impact polystyrene

Family Cites Families (3)

* Cited by examiner, † Cited by third party

Publication number
Priority date
Publication date
Assignee
Title

US4080359A
(en)

1975-07-18
1978-03-21
Mitsubishi Petrochemical Co., Ltd.
Talc containing polyolefin compositions

NO793292L
(en)

1978-11-02
1980-05-05
Expanded Metal Company Ltd The

HETE PROTECTION BARRIER.

US4440824A
(en)

1981-10-23
1984-04-03
Composite Container Corporation
Thermoformable coextruded multilayered structure

1987

1987-01-15
US
US07/003,437
patent/US4879147A/en
not_active
Expired – Lifetime

1988

1988-01-13
CA
CA000556432A
patent/CA1308873C/en
not_active
Expired – Lifetime

1988-01-14
JP
JP63006741A
patent/JPS63288748A/en
active
Pending

1988-01-14
AU
AU10283/88A
patent/AU603175B2/en
not_active
Ceased

1988-01-14
EP
EP88100457A
patent/EP0275102A3/en
not_active
Withdrawn

1988-01-15
MX
MX010117A
patent/MX167530B/en
unknown

Patent Citations (3)

* Cited by examiner, † Cited by third party

Publication number
Priority date
Publication date
Assignee
Title

US3589976A
(en)

1967-03-24
1971-06-29
Hercules Inc
Composite films of polyolefins and polystyrene

GB1420612A
(en)

1971-12-03
1976-01-07
Unilever Ltd
Laminated plastics film

US4464439A
(en)

1981-03-12
1984-08-07
Montefina S.A.
Co-extruded laminate consisting of at least one sheet of polypropylene and at least one sheet of polymeric material based on high-impact polystyrene

Also Published As

Publication number
Publication date

EP0275102A3
(en)

1989-03-15

US4879147A
(en)

1989-11-07

AU1028388A
(en)

1988-07-21

EP0275102A2
(en)

1988-07-20

MX167530B
(en)

1993-03-29

CA1308873C
(en)

1992-10-20

JPS63288748A
(en)

1988-11-25

Información de contacto