JPH03646A - Container and manufacture thereof - Google Patents

Abstract

PURPOSE: To allow a degenerative product to be stored in a package for a long time by forming a container of an aluminum foil, an ethylene copolymer film and a laminate web therebetween comprising polyacrylic acid chromium complex primer and placing the film on the product side in the container. CONSTITUTION: Polyacrylic acid chromium complex primer of a monomolecular layer blended as alcoholic aqueous solution is deposited on a face of an aluminum foil substrate for coating. The coated foil is heated for substantially drying the primer, thereafter an ethylene copolymer film is extrusion-coated onto a surface coated with the primer, and a formed laminate is cooled to finish a web. Preferably, a temperature of copolymer melt is approximately 288 to 316 deg.C during the extrusion-coating process. Then a container is formed with the laminate web disposed on a product side of the film container. The ethylene copolymer has carboxylic acid or a carboxylate group as a side chain.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Background of the Invention Tubes and other containers made from laminated webs made from gold FI473 and layers of synthetic resin are widely used for packaging various products such as line drawing polishes and others. ing. For example, American Can Company in Greenwich, Connecticut, USA is GLA.
MINATE™ sells such tubular containers. By properly designing and constructing laminates, they can provide the oxygen and moisture barrier properties necessary for packaging many products. Similarly, desirable in tubular packaging is also the ability to heat seal and have the ability to be permanently creased. Generally, the product side of laminated web is
A metal layer is usually glued to the inner surface of the aluminum foil,
It consists of olefin polymers such as low density polyethylene, ethylene acrylic acid copolymers (EAA) or Surlyn ionomers.

Although containers constructed in this manner are quite adequate in most environments, the ingredients contained in some products have a tendency to degrade or attack the material of the container. , causing destruction of the container. As is well known, certain toothpaste products are difficult to package in such laminate web containers, particularly those containing stannous fluoride or sodium fluoride as anti-caries agents. In an acidic environment and/or in the presence of essential oils and detergents, line polish components have a strong tendency to migrate through the inner layer to the interface, thus promoting delamination and packaging in the web structure. Product deterioration will occur. Of course, it goes without saying that the longer the storage period, the greater the deterioration that occurs in the laminate web. Moreover, this deterioration is particularly significant when the packaged product is stored at relatively high temperatures.

Various measures have been taken in the past not only to increase the initial adhesion level between the plastic film and the foil, but also to improve the delamination resistance during long storage periods, i.e. to extend the shelf life. . These efforts include flame treatment of the foil, use of interlayers of various adhesive materials, and chemical priming of the metal to increase bond strength at the interface.

An important example of the latter method is the use of chromium polyacrylate complex products as foil primers to enhance adhesion to polyethylene.

Laminated structures produced in this way are used for packaging alcohol-soaked swabs.

Although the use of such primers appears to significantly increase the strength of the bond, it is still not entirely sufficient for long-term storage, and the use of polyethylene as a product-side surface layer is undesirable in this case. This is because this material is prone to environmental stress crabbing in the presence of certain products such as line polish.

Therefore, the main object of the present invention is to eliminate products made with a laminate web consisting of an aluminum foil and a layer of ethylene copolymer, acrylic acid or acrylic acid ester monomer between said layer and a core layer, which have deteriorating properties. An object of the present invention is to provide a new container suitable for long-term packaging and storage, and a method for manufacturing the same.

(2) Summary The above-mentioned object of the present invention is to provide an aluminum foil, a film of an ethylene copolymer having carboxylic acid or carboxylic acid ester groups as side chains in the molecule, and a polymer between the layer and the film. It has been found that this can be easily achieved by providing a container made of a laminate web consisting of a layer of chromium acrylate complex primer, with the film being on the product side of the container. In preferred embodiments of the web, the copolymer films include poly(ethylene/acrylic acid), poly(ethylene/methacrylic acid), poly(ethylene/methyl acrylate), poly(ethylene/methyl methacrylate), poly(ethylene/ vinyl acetate), and ionomer resins.

The primer coating must be at least a monolayer thick and the web usually includes at least one additional layer. That is, the web generally includes at least one synthetic resin polymer layer disposed on the foil surface opposite the side to which the primer is applied.

This container is manufactured as follows. In this method, at least a monolayer of a chromium polyacrylate complex primer, formulated as an aqueous alcohol solution, is deposited and coated on at least one side of an aluminum foil substrate. The coated foil is then heated to substantially dry the primer, after which a film of ethylene copolymer (as described above) is extrusion coated onto the primer coated surface, thus forming The laminate is then cooled to finish the web. Preferably,
In the extrusion coating process, the temperature of the copolymer melt is about 550 to 600F;
Most preferably about 302 to 310°C (about 575 to 5°C)
90F). The laminate web constructed as described above is then processed into a container 4 such that the film is placed on the product side of the container. Such containers are suitable for filling products with deteriorating properties. The greatest benefit in this regard is often obtained when the product being filled is a dentifrice containing a fluoride anti-caries agent and/or one or more essential oils.

Typically, such containers are tubular, with side walls made of laminate webs, and a headpiece coupled to one end of the tube. This headpiece is generally made of a polyolefin resin such as high density polyethylene.

(3) Detailed Description of the Preferred Embodiments As mentioned above, foil/ethylene copolymer laminate webs are conventionally used in container manufacturing. The present invention increases the adhesive strength between the foil and the copolymer layer on the product side.
It provides a means of significantly reducing susceptibility to components with degrading properties that can migrate to interfaces.

The chromium complex used to prime the aluminum foil surface is sold by Mica Corporation of Stamford, Conn. under the trade name MICAA-291. This is 7% of the chromium polyacrylate complex.
It is an aqueous solution. It is also acidic and has a viscosity of about 10 centipoise. MICA A-291
Instructions for use describe the use of polyethylene to adhere to aluminum foil for packaging and industrial uses requiring high adhesion and resistance to various difficult-to-package substances such as fluorides and essential oils. It is. However, heretofore, the use of such primers has not produced the results achieved by the present invention, namely the formation of a very durable bond between the aluminum foil and the extruded coating of a copolymer containing a carboxylic acid or carboxylic acid ester of ethylene. However, it is thought that the fact that this bond persists despite close contact with a product that is likely to have a significant degrading property was not recognized.

The chromium complexes mentioned above appear to be the most effective primers for use here, but other similar materials can be substituted if desired. For example, polyacrylic N! By varying the chain length, the proportion of acrylic acid moieties within the copolymer and the ratio of metal to organic portion of the complex can be varied. It is also possible in practice to replace chromium ions with other transition metals such as cobalt, copper, nickel, etc.

As previously mentioned: Primers are generally applied as dilute water/alcohol solutions. This is to maximize the leveling and wetting of the support, thereby maximizing the adhesion of the polymer layer to the support.

For the preparation of the working liquid, commercially available M[CA A29!
3 each with additional water and isopropyl alcohol
They can be appropriately mixed at a volume ratio of 0:60:10.

The solution thus obtained, when dry, weighs approximately 0.014 to 0.036 Kg per ream (i.e., 270 m" (3000 rL") surface area).
08 bond), preferably 0.016Kg (approximately 0.03
5 bond) is used in sufficient amount to form a complex solid. In all cases, the primer must be at least one molecule thick, and will generally be at least somewhat thicker, and will generally be heated at a suitable temperature (i.e., about 250 to 400°C). After drying the foil primer by passing it through an oven maintained at
8 to 66°C (approximately 100 to 150@F). The techniques used to extrusion coat ethylene copolymers onto aluminum foil are well known to those skilled in the art and need not be described in detail.

However, considering that the copolymer must not only strongly adhere to the foil but also retain tack (i.e., heat sealability) and adhesion to other parts of the final product container, It will be appreciated that temperature is critical to achieving optimal adhesion.

In particular, as mentioned above, the laminate web used in the present invention finds widest application in the manufacture of tubular containers. In that case, the web must be able to form side seams and must be able to be securely attached to the molded headpiece. While high melt temperatures are preferred for adhesion to foils, they also promote oxidation, which prevents formation of good bonds with other polymeric surfaces (eg, headpieces). Therefore (and depending on the size of the extrusion die lip gap width), FAA is generally extruded at temperatures of 288 to 316°C (550 to 600'°F) and The optimum balance of adhesion is usually achieved at a melt temperature of 302 to 310°C (575 to 590"F).
The AA or ionomer usually constitutes the product side layer of the laminate web, but other ethylene copolymers with carboxylic acid or carboxylic ester groups as side chains, such as acrylic or methacrylic acid, methyl acrylate, methyl methacrylate, and vinyl acetate, may also be used. Copolymers can also be used.

For economic reasons and practical advantages, extrusion coating is a commonly used technique for producing foil/copolymer composites, although other techniques may be appropriate or necessary in some circumstances. If you have it, you can use it. In general, the product side polymer thickness should be approximately 25.4 to 10
2μ (approximately 1.0 to 4.0 mils) and more commonly 38°1 to 76.2μ (1.5 to 3.0 mils).

As far as the foil components are concerned, as a practical matter thin (approximately 7.2
4 to 76 μ (0.285 to 3.0 mil)) aluminum is commonly used, but foils of other metals may be substituted for certain applications. Laminated webs typically include additional polymer layers for various purposes and typically include paper layers for convenient printing or article decoration. A typical laminate cross section consists of (from the outside) polyethylene, paper,
Polyethylene, FAA, foil, primer, and EAA
This structure consists of (foil, primer FAA
(apart from the lower-level combinations of) and are conventionally used, and are not essential aspects of the present invention. Similarly, methods for making containers from laminate webs (e.g., fabricating and sealing tubes by head splicing, side seaming, and end sealing) are conventional and well known to those skilled in the art. . Therefore, detailed explanation is not necessary. However, it should be mentioned that in the form of side seams, the ends of the web are usually overlapped.

It will be appreciated that it is advantageous to prime both sides of the foil in accordance with the present invention since both sides of the laminate will then be in contact with the product.

The following examples serve as a detailed illustration of the invention.

The web of material for the container was manufactured using a subassembly consisting of a layer of polymer and paper adhered to 18μ (0.7 mil) aluminum foil.

The total thickness of this subassembly is approximately 259μ (approximately 10°2 mils). The exposed surface of the foil was undercoated using a gravure cylinder so that the chromium polyacrylate complex formed a layer that was somewhat thicker than a monomolecular layer. At this time,
A solution of MICA A-291:water:isopropyl alcohol in a ratio of 30:60:10 was used. Then about 1
Dry with forced air in an open air at 21"C (approximately 250°F).

The first laminate was 19.
It was manufactured by extrusion coating with 7 Kg (43.5 bond) low density polyethylene. The extrudate temperature is about 316°C (about 600°F). This laminate will be referred to as A below.

A second laminate B was made by extrusion coating the primed foil side with the same thickness of EAA copolymer containing 3.5% acrylic acid monomer. Again, the melt temperature is about 316°C (about 600°F). A third laminate C was also made in the same manner using an FAA copolymer containing 8.0% acrylic acid content instead of the 3.5% resin.

The aforementioned laminate is 2.54X14.3cm (1x
56/@inch) into a small container and store it in a commercially available toothpaste (Brocter & Gamble CrtEsT).
After filling with line drawing polish), I sealed it. Several containers made with each of the three laminates were held at a controlled temperature for periods ranging from two weeks to six months, after which time the condition of the web was examined. Specifically, five containers of each specimen were held at temperatures of 24°C and 41°C (75'F and 105°F), and three containers of each specimen were held at a temperature of 49°C (120"F). was held at

These were evaluated at 2, 4, 8, 12 and after 26 weeks. The results are shown in Table 1.

The symbols E, G, F, and P used in this table indicate that the web condition was determined to be excellent, good, fair, and poor, respectively. A dash indicates that the test was not conducted under the indicated conditions. To be rated as excellent, the adhesion force must be such that the polymer layer stretches against the force that tends to separate it from the foil. In the case of good adhesion, separation occurs, but the bond is barely adhered. The adhesion is considered acceptable if the laminate shows a fairly strong resistance to separation, and poor if the til1 layer easily occurs.

As shown in No. 11, the adhesion strength when the laminating polymer is polyethylene (laminate A) is higher than that when the EAA film is laminated to the primed foil (laminate B).
and C) provide very high adhesive strength. More specifically, after 4 weeks of storage at 49°C (120°F),
8 or I2 at 41”C (150”F)
After weeks of storage, both laminates containing EAA exhibit good to excellent adhesion, while laminates containing polyethylene exhibit only fair adhesion. This is the first
The table also shows that in all examples, the laminates containing FAA are universally superior to the laminates containing low density polyethylene, which is the most significant difference seen.

In addition to the delamination tests described above, the environmental stress crabbing of three laminate webs was evaluated by hand squeezing appropriately selected containers. After a six week storage period at 41'C (105F), containers made from webs containing polyethylene were found to be significantly susceptible to crabking when squeezed by hand. On the other hand, F
Webs containing AA showed satisfactory durability to such handling under the same conditions.

Example 2 Commercial household cement (DuPont DUCO™ Cement) was encapsulated in a pouch made of a laminate with 3.5% EAA or ionomer on aluminum foil. In all cases the polymer and foil thicknesses are each 5
1μ (2,0 mil) and 8.4μ (0,332 mil)
It is. Two versions of each laminate were produced. That is, there are two types of foil: one where the foil was surface treated with MICA A291 primer and one where the foil was not surface treated. The pouches were sealed and stored at 41'C (+05°F). Separate pouches were opened after a storage period of 1 month and 2 months, respectively, and the magnitude of the adhesion between the polymer layer and the foil was evaluated.

After a one month storage period, webs made with aluminum foil as the base coat showed good adhesion regardless of whether the polymer layer was FAA or ionomer. On the other hand, webs using unprimed aluminum foil showed either delamination (for FA A) or poor adhesion (for ionomer). The results were the same for a storage period of 2 months.

In the above specific examples, the deterioration effects of fluoride line polishing and household cement containing highly active organic solvents were investigated.
Although the laminated web containers of the present invention have been shown to be extremely durable, it should be understood that the webs of the present invention can be effectively used for packaging many other products that may be difficult to package. be. For example, the web of the present invention includes NOXEMA™ Plushless Shave Cream (Tuxel Corporation), Helena
Rubenstein Ski, N Leitner (Tele)
na RubensLeinSkinLight
waterless hand cleaner VAG I NEX™ Cream (Schmidt Laboratories), Plymouth Citrus Products Industrial Waterless Hand Cleaner, TURTLE WA
X (trademark) Auto Polish Glaze, ARTRA
(Trademark) Skin Tone Cream (Plough Incorporated), Union Carbide Corporation Car Polish, AnSOr! l31NE R
UB™ (W, F, Young Incorporated), Red Glazing Patty (Ooty Company), LX845 Auto Glaze (Petrolite)
corporation), and two-pull tube (Sou
pletube) (France) Product No.

It showed satisfactory resistance to the deterioration effects of No. 3.

As will be clear to those skilled in the art, in all examples the magnitude of the resistance to delamination is at a very good level;
The particular results achievable with any particular product will of course vary. Furthermore, the commercial products listed above are merely illustrative, and the laminated web containers made in accordance with the contemplation of the present invention can be used equally effectively for many other products. It should be understood that

As explained below, the present invention is made of a laminate made of aluminum foil and a layer of copolymer of ethylene with acrylic acid or acrylic acid ester monomers and used for the packaging of products with degrading properties over long periods of time. It provides a new container suitable for The present invention also provides a new method for manufacturing such a new container.

Claims (8)

[Claims] (1) Consisting of an aluminum foil, a film of an ethylene copolymer having carboxylic acid or carboxylic acid ester groups as side chains in the molecule, and at least a monomolecular layer of a chromium polyacrylate complex primer between the foil and the film. Container for a product having properties that degrade the container material, made of a laminated web, characterized in that the film is on the product side within the container. (2) A packaging container consisting of the container according to claim 1, which packages a product that has the property of deteriorating. (3) The packaging container according to claim 2, wherein the product is a toothpaste containing a fluoride caries preventive agent. (4) The packaging container according to claim 3, wherein the laminate web is processed into a tubular structure, and a head piece is fixed to one end of the tubular structure. (5) The packaging container according to claim 4, wherein the head piece is made of high-density polyethylene. (6) coating at least a monolayer of a chromium polyacrylate complex primer as an aqueous alcohol solution on at least one side of an aluminum foil substrate; heating the coated substrate to substantially dry the primer; ;A film of ethylene copolymer having carboxylic acid or carboxylic acid ester groups as side chains in the molecule, about 2
extrusion coating onto at least one primer coated side of the foil at a melt temperature of 88 to 316°C (approximately 550 to 600°F); cooling the laminate so formed to form a web; A method for producing a container for a product having properties that degrade the container material, characterized in that the web is processed so that the film of the copolymer is on the inside to obtain a container structure. (7) Processing the web into a tubular structure, and further
bonding a headpiece to one end of the tubular structure, the melting temperature being about 302 to 310°C (about 57°C);
7. The method of claim 6, wherein the temperature is between 5 and 590 degrees Fahrenheit. (8) The method according to claim 7, wherein the headpiece is made of high-density polyethylene.