JPH0358831A - Reinforced sheet material for hermetic sealing - Google Patents

Abstract

PURPOSE: To enhance a tearing resistance by laminating a layer of a sealing material for bonding a reinforcing sheet material to a container, a layer of a material impermeable to air and moisture, and a layer of the reinforcing material, thereby increasing a strength of the sheet material. CONSTITUTION: The reinforcing sheet material 10 for sealing comprises a layer 12 of a sealing material (for example, a heat sealable film), a layer 14 of a material (e.g. a polyvinyl chloride, aluminum foil) substantially impermeable to air and moisture, and a layer 16 of a reinforcing material. The layer 16 is obtained by laminating at least two single layers made of uniaxially oriented films together by intersecting a strong direction of the one single layer to a weak direction of the other single layer to impart the same strength in all directions by increasing tearing and tensile strengths in a mechanical direction, its cross sectional direction and oblique direction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to containers, and more particularly to multilayer sheet materials for sealing containers. BACKGROUND OF THE INVENTION Sheets of multilayer materials have been used to make internal seals for sealing the openings of containers from air and contaminants. A simple internal seal consists of a sheet of metal foil with a heat-sealable layer for bonding the foil to the rim of the mouth of a container, such as a bottle.
The internal seal is typically die-cut from a sheet of multilayer material and heat sealed to the lip of the container. The inner seal can be made to have a tab extending outwardly from the outer periphery of the inner seal to assist a user in grasping the tab to peel the inner seal from the container. Internal seals with tabs are typically used on containers with threaded necks where threaded caps are used. The inner seal is die-cut from a multilayer sheet of metal foil with layers of heat-sealable materials as described above. The tab should be folded 180 degrees so that it fits within the cap but is in a position where it can later be used to peel the sealed inner seal from the rim of the container mouth.
III Geru. The inner seal is then inserted into the cap and the cap is screwed onto the neck of the container. The capped container is then heated by induction heating the aluminum foil, thereby melting the layer of heat-sealable material;
Join the inner seal to the container. Internal seals with tabs can also be used in containers with snap-on caps. U.S. Patent Nos. 4,047,473 and 4,155,4
No. 39 describes a method and apparatus for applying a sealing membrane with folded tension tabs to a container. These inventions describe an apparatus for cutting a sealing membrane from a sheet, folding a tab, and inserting the sealing membrane into a lid. Next, the lid assembly is attached to the container, making it airtight, and the sealing membrane is sealed to the container. U.S. Pat. No. 4,754,890 discloses a tamper evident safety seal having a tab of sheet material that is folded in a Z or S shape to form a double folded tab. Are listed. The safety seal may include a scrim to provide additional strength.

U.S. Pat. No. 4,625,875 describes a tamper evident safety seal having a cap and a tabbed sealing disc. Although sealing membranes, safety seals, sealing discs, and internal seals having tabs for ease of removal are known in the art, tabs have not led to widespread acceptance of tabbed internal seals in the marketplace. It has certain drawbacks that hinder it. When the inner seal is die cut, the inner seal adjacent to the tab may be damaged so that only a portion of the inner seal can be removed when the user pulls on the tab. If the internal seal has low internal strength, when the tab is pulled, only a narrow band of the internal seal that is substantially the same width as the tab can be removed.
In some cases, pulling on the tab may not remove the internal seal at all. Another problem occurring with the internal seals currently used on the market is the bend back (APR)
This is a problem called ingback). In most conventional inner seals, after the tab is bent to allow insertion of the inner seal into the cap, the tab springs back about 90' so that it is closed against that portion of the inner seal that covers the mouth of the container. Rather than lying flat, it stands almost perpendicular to the plane of the inner seal. After the inner seal is inserted into the cap, the unbending of the tab pushes the inner seal toward the outside of the cap, causing the inner seal to shift during sealing, creating an inadequate seal. Due to unbending of the tab, the internal seal may become dislodged from the cap, resulting in an unsealed container. Provides an inner seal having a tab that has great internal strength and further has a tab that bends back less than about 45 degrees from the plane of the inner seal once the tab is bent over the portion of the inner seal that covers the mouth of the container. That would be desirable.
As previously mentioned, conventional internal seals typically have a return of about 90'' from the plane of the internal seal. SUMMARY OF THE INVENTION In one aspect, the present invention provides a multiphase sheet material and The sheet material provides a sealing member for a shaped container from which the sheet material has increased strength, improved tear resistance, and the ability to double fold the material compared to currently available sheet materials. It shows a smaller unbending at time.
In another aspect, the present invention provides a multilayer closure member having a tab for use on a container. The sealing member of the present invention comprises: (a) a layer of sealing material for joining the sealing member to the container; (b) a layer substantially impermeable to air and moisture; and (c) a reinforcing material. A layer of six layers of sheet material can be formed from a suitable adhesive. The impermeable layer can be formed from a polymeric film, such as poly(vinyl chloride), or a metal foil, such as aluminum foil. Is the reinforcing layer made from uniaxially oriented film? the strong direction of one ply to the other such that the tear and tensile strength increases in the machine, transverse and diagonal directions to provide the same strength in all directions. It is a multilayer film consisting of single layers laminated together with their weak directions crossed. The sheet material of the present invention can be used to make internal seals for containers. The sheet material is particularly useful for making internal seals with tabs. The reinforcing layer material prevents the folded tab from bowing more than about 45 degrees, thereby reducing the problem of misalignment of the inner seal after it is placed into the cap, or of the inner seal falling out of the cap. It has been resolved. The sheet material of the present invention can also be used to produce sealing membranes for containers that do not require the use of caps. DETAILED DESCRIPTION With reference to FIG. ) a sealing material for bonding an internal seal or sealing membrane to the container;
<12), (b) a layer (14) of material impermeable to air and moisture, and (c) a layer (16) of reinforcing material.

Any suitable sealing material may be used. Heat-sealable films suitable for the present invention include polyethylene, polypropylene, ethylene-vinyl acetate copolymers, modified polyesters, and the like. The choice of heat sealing material depends on the composition of the container to be sealed. Generally, the heat sealable material should be similar to the material from which the container is manufactured. Containers made from polyethylene are made from polyethylene or ethylene.
Film or film made from vinyl acetate copolymer
Can be sealed with melt adhesive. Containers made from polypropylene can be sealed with films or hot-melt adhesives made from polypropylene or ethylene-vinyl acetate copolymers. Containers made from polyester and poly(vinyl chloride) can be sealed with modified heat-sealable polyester or acrylonitrile rubber. Other sealing materials include E. I. Trade name ``Surlyn'' from DuPont de Numers & Company.
Includes ionomer resins available commercially as J. Representative examples of commercially available films suitable for the encapsulation layer (IZ) include ScoLchpak, available from Minnesota Mining and Manufacturing Co., St. Ball, Minnesota;
”, EI of Wilmington, Delaware. dupont
Mylar 500 L-2 film and Mylar 50XM946 film available from De Numers & Company. The impermeable layer (14) is a metal foil such as aluminum foil,
or it can be a polymeric material such as poly(vinyl chloride), polyester, or a multilayer film, such as a laminate of poly(vinyl chloride) and polyester. The layer of reinforcing material (16) is a uniaxially oriented film. a multilayer film having at least two monolayers consisting of a multilayer film, the monolayers being layered in such a way as to improve the tear strength and tensile strength of the sheet in the machine direction, its transverse direction, and its diagonal direction. When single plies are used, they are held together in a stack with the strong direction of one ply crossing the weak direction of the other ply. The forming polymers may be the same or different. Suitable thermoplastic polymers for these monolayers of the laminate are, for example, homopolymers or copolymers of ethylene, polypropylene, polystyrene, poly(vinyl chloride). , polyvinylidene chloride, polyvinyl alcohol, and ethylene-vinyl acetate copolymers. Polyesters can also be used to make those monolayers of the laminate. The most preferred layer materials are polyvinylidene and high density polyethylene. The monolayers can be laminated together by conventional means such as heat sealing, ultrasonic welding, or by the use of laminating adhesives.Representatives of commercially available films suitable for the reinforcing materials of the present invention A typical example is the trade name “Valeron” (Va
Ieron) J, manufactured by Van Leer Plastics Co., Houston, Texas.
an Leer Plastics, Inc. ). Methods of manufacturing such reinforcing materials are described in U.S. Pat.
No. 4,785 (which is incorporated herein by reference). U.S. Pat. No. 4,243,463 describes a thermoplastic polymer film laminate consisting of two or more substantially uniaxially oriented layers, the orientation of each layer being W
an angle, preferably 45°, with respect to the longitudinal direction of the t-layer;
It forms a certain angle, preferably 90°, with respect to the orientation direction of adjacent N(s). Such laminates are commonly referred to as ``cross-laminates''.
) is called J. The layers of such a cross-laminate may be laminated by any suitable method, such as adhesives, spot welding, or extrusion lamination, i.e., a plurality of pre-formed layers squeezed into the gap between a pair of nib rolls from which the laminate is formed. (inserting a thin molten polymer film between the films). The manufacture of cross-laminates is described, for example, in British Patent No. 1,414,785. The reinforcing layer (16) serves to reinforce the internal seal.
The reinforcing layer (l6) is composed of an impermeable layer (14) and a sealing layer (12).
), or the impermeability 1 (14) may be placed between the reinforcement W (1B) and the sealing layer (12). For internal seals with tabs, an impermeable layer (1
4) is preferably placed between the reinforcing layer (16) and the sealing layer 1 (12). A preferred structure results in significantly less unbending of the tab after the tab is bent. Furthermore, if the impermeable layer (l4) is made of metal foil, less energy is required for induction heating if the impermeable layer (l4) is in contact with the sealing [(12)]. It would be fine. A surprising feature of the invention is that the folding back of the sheet (10) caused by the reinforcing layer (16) is less than in the case of multilayer sheets known in the art. One would think that the reinforcing layer would resist bending and give it a tendency to return to its initial unfolded state, but the reinforcing layer (16) can be easily folded and does not cause any effective return. ．． In conventional tabbed inner seals, i.e., tabbed inner seals made from oriented polymeric films, when the tab is folded across the direction of orientation of the polymeric film, the inner seal is no longer as strong as the inner seal of the present invention. It is not possible to increase the effect. Layers (12>, (14), and (l6>) can be bonded together by heat sealing or by a suitable laminating adhesive. Examples of laminating adhesives suitable for the present invention include Norton Thiokol Company of Chicago
iokol, Inc. Adeote J503A is a urethane adhesive with the trade name Adeote J503A available from Adeote J503A.
Other layers may be included along with the sheet material (10) previously described to provide a surface for printing. Materials that can be used for additional layers include paper,
Includes polymer films, non-woven fabrics, silk screen inks, etc. The internal seal using the sheet material of the present invention is
It can be cut from sheet material and applied to containers by known methods, which will not be detailed here. Briefly, regarding Figures 1, 2, and 3, tab (2)
2} and an inner seal (20) having a portion (24) covering the mouth of the container is cut into the desired shape from the sheet material (10) of the invention (see FIG. 1).

The tab (22) is bent so that its surface free of sealing material contacts the surface of the portion (24) free of sealing material. Next, attach the inner seal (20) to the container (28).
into the cap (26) applied to. The internal seal (20) has a sealing layer [i.e. layer (12)'1 in FIG.
is placed in the cap (26) so that it is in contact with the lip (30) of the container (28). Container (28)
may be a conventional bottle, typically formed from plastic or glass, having a body portion (32) and an upper end having an overhang (36) and a peripheral bead (38) defining the mouth of the container. It has a neck (34). Cap (26
) may be of conventional construction of metal or plastic, most preferably plastic, such as polyethylene or polypropylene. As is conventional, the cap (26) has an upper surface (40) and an internally threaded downwardly-sloping annular sidewall (42). Annular side wall (4
2) The outer surface of the container (
When removing or attaching the cap (28)
6) To make it easier to grasp, vertically extending peaks and/or grooves may be added, or jagged edges may be added. Then the cap (
26> onto the opening of the container (28) and tighten it onto the container. The internal seal (20) is then sealed to the mouth rim (30) by heating means, such as induction heating.

The sheet material of the present invention can also be used to form a sealing membrane for containers without caps. Such sealing membranes are described, for example, in U.S. Pat. No. 4,264.
, No. 316 (which is included here for reference).

The following examples are intended to further illustrate the invention and are not to be construed as limiting the invention. Example 1 The first main surface of a 0.025zz (0.OO1in) thick aluminum foil was coated with 0.025zz (0.OO1in) thick adhesive using Adcoat 503A adhesive.
．． The inner seal was made from sheet material consisting of a laminate of 1021 JI (0.004 inch) thick Valeron film. The dry coating weight of the adhesive layer is approximately 83.7B7
The second major surface of the aluminum foil was laminated to the polyester side of the Scotchpak 115 film with Adcoat 503A adhesive.The other side of the Scotchpak 115 film was laminated with ethylene acetic acid. The dry coating weight of this adhesive layer was approximately 83.7z.
g/200c1 (1 grain/24in2).
This sheet material can be used as an internal seal for containers made from polyethylene or polypropylene.

Example 2 A 0.025 mz (0.0 OLin) thick white opaque polyester film was laminated to the exposed side of the Valeron film of the inner seal from Example 1 with Adcor 503A adhesive. Dry coverage weight of adhesive layer is approximately 83.7x
g/200c1 (1 grain/24in2). One such polyester film is described in US Pat. No. 3,154,461. The polyester film not only provided the internal seal with an aesthetically pleasing surface, but also provided additional reinforcing properties. Example 3 The interior was made from a sheet material consisting of a first major surface of 0.0254i+i+(0.001 in) thick aluminum foil laminated with 0.102zx (0.004 in) thick Valeron film with Adcote 503A adhesive. I made a sticker. Dry coating weight of adhesive layer is approximately 83.7m
g/200cx" (1 grain/24in"). The second main surface of the aluminum foil was coated with Adcoat 50.
Laminated to the polyester side of Mylar 50 XM946 film using 3A adhesive. Mylar 50 XM94
The other side of the 6 film was formed from an ethylene-vinyl acetate copolymer. The dry coating weight of this adhesive layer is approximately 83.7zg/200c1 (1 grain/24in2
)Met. This sheet material can be used as an internal seal for containers made from polypropylene, polyethylene, polyester, poly(vinyl chloride), and polystyrene. Example 4 0.025vz (0.OO1) as described in Example 2
in) The exposed side of the Valeron film of the inner seal from Example 3 was laminated with Adcote 503A adhesive to a thick white opaque polyester film.

The dry coating weight of the adhesive layer is approximately 83.7B/200cz"
(1 grain/24in2). Example 5 The first main surface of a 0.025zz (0.OO1in) thick aluminum foil was coated with a
．． The internal seal was made from sheet material consisting of a laminate of 102zz (0.004 inch) thick Valeron film. The dry coating weight of the adhesive layer is approximately 83.7zg/20
The second major surface of the aluminum foil was laminated to the polyester side of the Mylar 500L-2 film with Adcoat 503A adhesive. The other side of the Mylar 50OL-2 film was heat sealable. The dry coating weight of this adhesive layer was approximately 83.7xy/200cz'<1 grain/24i+1). This sheet material can be used as an internal seal for containers made from polyester or poly(vinyl chloride). internal seal,
Tests were conducted to determine tear resistance, tear propagation resistance, and bend-back angle. The results of the test are listed in Table I. A commercially available internal seal material was used as a control. The following test method was used to evaluate the internal seal of the present invention. Tab - Quantity 2.86cm (1.125in) diameter circular body, width 0.635CI + (0.25in) x length 0.476
A tabbed inner seal with a tab size of cm (0.1875 in) was cut from the reinforcing sheet. The tip of the tab was rounded. Fold the tab 180° and contact it with the surface of the inner seal opposite the heat-sealing layer;
Rolled once with a 3.25 inch diameter steel roller weighing 4.5 lb. The roller is A S T M D
-3330-83. The amount of unbending was measured using a protractor. This test measures the amount of force required to tear a film that has already started tearing by making a small cut in the edge of the film with a knife. This test gives an indication of the film's tear resistance. ” ASTM D-1938-85 This test measures the amount of force required to initiate a tear in a plastic film and is a measure of the resistance to tear propagation in an initially uncut film. Soil tearing resistance Tear propagation (g) Resistance (y> MD moxibustion CDA★ MD&CD&# Bending return angle (°) Example 2 Example 4 Control゛2175 2195 3853 9632
31.62293 2156 4128
9013 29.5390 470
1651 2201 92.6★ The machine direction or longitudinal direction of the film as it is made.

★Direction perpendicular to the longitudinal direction of the film when moxibustion is made, that is, a direction intersecting it. Inslec, Aurora, Ontario, Canada
Insulec U-5. The data in Table 1 shows that the internal seal of the present invention significantly outperforms the commercially available control internal seal for the three properties tested. The internal seal was further tested in the following manner. Inner seals with tabs (diameter 38 cm) were cut from the sheets of Examples 2 and 4. The tab was bent so that the polyester surface of the tab was in contact with the polyester surface of the inner seal covering the mouth of the container. Each inner seal was placed into a polypropylene continuous threaded cap with the polyester surface of the inner seal facing toward the top of the cap. Next, attach the cap to 237zl (
8 oz.) capacity polyethylene bottle. 237zi in advance in the bottle! It was filled with (8 ounces) of water.

The cap was then placed by the Owens Illinois Glass Company in Toledo, Ohio.
196g・l (17in・l) using a spring torque tester available from Glass Company.
Tightened to b). The internal seal is 38.■ R level (Lepel) with tunnel coil.High frequency induction device, model number T-2.5-1-K C-AP-B
was coupled to the bottle by W at a rate of 60 fL/min. The power settings of the device were varied expressed as a percentage of the maximum value.
Table ■ shows the power setting range that can provide adequate sealing. The minimum value indicates the lowest setting that will yield an adequate seal. The f& large value indicates the value at which the user can still remove the inner seal in one piece. Although larger power designs will also provide adequate sealing,
The internal seal will become very difficult to remove. High power settings may result in burnt internal seals and an unsightly appearance. The seal test involved placing the water-filled container, with the threaded cap removed, on its side into a vacuum chamber that was pumped to a vacuum of approximately 25 inches of mercury gauge pressure. (A zero reading on the gauge indicates atmospheric pressure. As the gauge reading increases, the vacuum increases). For sealing to be considered adequate, at least 16
It must remain attached to the container even under the inHH vacuum. Revised t''% 2 70 - 82
4 71-85
Controls 70-82 The data in Tables ■ show that the internal seals of the present invention can be applied by conventional container sealing equipment. It will be apparent to those skilled in the art that various modifications and variations of this invention can be made without departing from the scope and spirit of this invention. It is to be understood that the invention is not unduly limited to the illustrative embodiments set forth herein.

[Brief explanation of drawings]

FIG. 1 is a schematic enlarged cross-sectional view of a standard material from which an internal seal or sealing membrane can be formed. FIG. 2 is a perspective view of one embodiment of the internal seal of the present invention when it has a tab. FIG. 3 is an exploded perspective view showing the bottle with the internal seal of FIG. 2; 10--Sheet material, 12-Sealing material layer, 14-
1. Impermeable layer, 16. Reinforcing layer, 2.1 internal seal,
22-tab, 26-cap, 28-bottle.

Claims (21)

[Claims] (1) A reinforced sheet material for sealing a container comprising: (a) a layer of sealing material for bonding said sheet material to the container; (b) a layer substantially impermeable to air and moisture; and (c) at least two monolayers of uniaxially oriented film brought together in a laminate with the strong direction of the at least one monolayer intersecting the weak direction of the other monolayer. A sheet material with a reinforcing layer. 2. The sheet material of claim 1, wherein the impermeable layer is disposed between the sealing material and the reinforcing layer. 3. The sheet material of claim 1, wherein the reinforcing layer is disposed between the impermeable layer and the layer of sealing material. (4) at least one monolayer consisting of a uniaxially oriented film is made of ethylene homopolymers and copolymers, polypropylene, polystyrene, poly(vinyl chloride), polyvinylidene chloride, polyvinyl alcohol, ethylene/vinyl acetate copolymers, A sheet material according to claim 1, wherein the sheet material is made from a polymer that is one of the group consisting of: and polyester. (5) The sheet material according to claim 1, further comprising a fourth layer. (6) an inner seal having a tab extending from an outer periphery, comprising: (a) a layer of sealing material for coupling said inner seal to a container; (b) a material substantially impermeable to air and moisture; and (c) at least two monolayers of uniaxially oriented film brought together in a laminate with the strong direction of at least one of the monolayers intersecting the weak direction of the other monolayer. layer, inner seal with . 7. The internal seal of claim 6, wherein the impermeable layer is disposed between the layer of sealing material and the reinforcing layer. 8. The internal seal of claim 6, wherein the reinforcing layer is disposed between the impermeable layer and the layer of sealing material. (9) at least one monolayer consisting of a uniaxially oriented film is made of ethylene homopolymers and copolymers, polypropylene, polystyrene, poly(vinyl chloride), polyvinylidene chloride, polyvinyl alcohol, ethylene/vinyl acetate copolymers, 7. The inner seal of claim 6, wherein the inner seal is made from a polymer that is one of the group consisting of: and polyester. 10. The internal seal of claim 6 further comprising a fourth layer. (11) A container having a cap and an internal seal, the internal seal comprising: (a) a layer of sealing material for bonding the internal seal to the container; (b) substantially impermeable to air and moisture; a layer of transparent material; and (c) at least two monolayers of uniaxially oriented film brought together in a laminate with the strong direction of the at least one monolayer intersecting the weak direction of the other monolayer. A container having a reinforcing layer consisting of. 12. The container of claim 11, wherein the impermeable layer is disposed between the layer of sealing material and the reinforcing layer. 13. The container of claim 11, wherein the reinforcing layer is disposed between the impermeable layer and the layer of sealing material. (14) at least one monolayer consisting of a uniaxially oriented film is made of ethylene homopolymers and copolymers, polypropylene, polystyrene, poly(vinyl chloride), polyvinylidene chloride, polyvinyl alcohol, ethylene/vinyl acetate copolymers, 12. The container of claim 11, wherein the container is made from a polymer that is one of the group consisting of: and polyester. (15) The container according to claim 11, further comprising a fourth layer. 16. The container of claim 11, wherein the internal seal includes a tab. (17) A sealing membrane made from the sheet material according to claim 1. 18. The sealing membrane of claim 17, wherein the impermeable layer is disposed between the layer of sealing material and the reinforcing layer. 19. The sealing membrane of claim 17, wherein the reinforcing layer is disposed between the impermeable layer and the layer of sealing material. (20) at least one monolayer consisting of a uniaxially oriented film is made of ethylene homopolymers and copolymers, polypropylene, polystyrene, poly(vinyl chloride), polyvinylidene chloride, polyvinyl alcohol, ethylene/vinyl acetate copolymers, 18. The sealing membrane of claim 17, wherein the sealing membrane is made from a polymer that is one of the group consisting of: and polyester. (21) The sealing membrane according to claim 17, further comprising a fourth layer.