Composite foil

[54] [75]

COMPOSITE FOIL

Inventor: Roland K. Belz,

Leinfelden-Echterdingen, Fed. Rep. of Germany

[73] Assignee: RB Kunststoffpatent-Verwertungs

AG, Fed. Rep. of Germany

[21] Appl. No.: 688,331
[22] Filed: Jan. 3, 1985

Related U.S. Application Data

[63] Continuation-in-part of Ser. No. 645,508, Aug. 30, 1984, Pat. No. 4,551,369, which is a continuation of Ser. No. 221,288, Dec. 30, 1980, Pat. No. 4,469,728, which is a continuation-in-part of Ser. No. 393,485, Jun. 29, 1982, abandoned.

[30] Foreign Application Priority Data

Jan. 9, 1980 [DE] Fed. Rep. of Germany 3000516

Jul. 8, 1981 [DE] Fed. Rep. of Germany 3126797

[51] Int. CI.4 B05D 1/14

[52] U.S. a 428/90; 428/283;

428/284; 428/285; 428/913

[58], Field of Search 428/90, 283, 284, 285,

428/913

[56] References Cited

U.S. PATENT DOCUMENTS

3,625,794 12/1971 Arikawa et al 156/244

3,788,934 1/1974 Coppa 161/17

3,859,125 1/1975 Miller et al 117/155 UA

4,261,066 4/1981 Belz 4/222

FOREIGN PATENT DOCUMENTS

862500 11/1952 Fed. Rep. of Germany .

1228030 11/1966 Fed. Rep. of Germany .

1229833 12/1966 Fed. Rep. of Germany .

2629127 12/1970 Fed. Rep. of Germany .

2008939 9/1971 Fed. Rep. of Germany .

2158016 5/1972 Fed. Rep. of Germany .

2302963 8/1973 Fed. Rep. of Germany .

2425655 12/1975 Fed. Rep. of Germany .

2525992 1/1977 Fed. Rep. of Germany .

1753903 5/1977 Fed. Rep. of Germany .

2725736 12/1977 Fed. Rep. of Germany .

2639512 3/3978 Fed. Rep. of Germany .

2703005 7/1978 Fed. Rep. of Germany .

3000516 7/1981 Fed. Rep. of Germany .

3203195 9/1982 Fed. Rep. of Germany .

1348115 2/1963 France .

308388 7/1955 Switzerland .

844509 8/1960 United Kingdom .

861423 2/1961 United Kingdom .

937852 9/1963 United Kingdom .

960203 6/1964 United Kingdom .

960204 6/1964 United Kingdom .

OTHER PUBLICATIONS

"Kunststoff-Verarbeitung im Gesprach", BASF, AG (1971).

"Grundlagen der Kunststoffverarbeitung", Knappe (1970).

"Blatt fur Patent, etc.", 1/1935, p. 137. "Gewerblicher Rechtsschutz und Urheberrecht", 1/1979, p. 51.

"Blatt fur Patent, etc.", 1/1976, p. 24. "Gewerblicher Rechtsschutz Wettbeaevbsrecht, Urheberrecht", 12/1981, p. 500.

Heitz, "Fullstaffe als Qualitatsverbessernde Modifikatorer", 5/1975, p. 286.

Harrehs et al., "Die Hestellung von Mowiol-Weichmache-Blerd und Seine Verarbeitung im Blasextrusionsverfahren", 1981, p. 973.

Klein, "Extrusionsbeschichtung Bahnformtger Materialier", 1976.

"Full-und Verstarwungsstoffe fur Kurststoff", Gah, 7/1977.

Hancock, "Nevere Ertwicklurgen Bei Mineralischen Fullstoffen fur Kunststoffe", 1978.

Primary Examiner—James J. Bell

Attorney, Agent, or Firm—Steele, Gould & Fried

[57] - ABSTRACT

A composite foil having at least two layers in which the first layer is normally water soluble and the second layer contains a dissolving intermediary for the first layer for use as packing material.

24 Claims, 3 Drawing Figures

1

COMPOSITE FOIL

CROSS REFERENCES TO RELATED

APPLICATIONS 5

This application is a Continuation-in-Part of Ser. No. 645,508, filed Aug. 30, 1984 (U.S. Pat. No. 4,551,369), which is a Continuation of Ser. No. 221,288, Filed Dec. 30, 1980 (U.S. Pat. No. 4,469,728). This application is also a Continuation-in-Part of Ser. No. 393,485, filed 10 June 29, 1982, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a composite foil having at 15 least two layers in which at least one cover or sealing layer which is normally insoluble in water, is connected to a water-soluble reaction material of at least one layer, which contains a dissolving intermediary for the sealing cover layer. The cover layer is made free from pores by 20 its extrusion as a foil of thermoplastic material.

2. Description of the Prior Art

U.S. Pat. No. 4,261,066 (corresponding to German Offenlegungsscrift 2 703 005) in the Applicant's name, discloses a foil adapted to be used once by being laid on 25 a toilet seat. In one embodiment the foil can take the form of a composite foil, a water-soluble layer being turned towards the user and the foil having on its side remote from the user a cover or sealing layer insoluble in water. This cover layer can be dissolved in an acid or 30 basic medium. To cause such dissolving, the water-soluble layer contains a corresponding basic or acid additive, so that when immersed in water the foil is soluble as a whole, but the composite foil is not caused to dissolve when water contacts only its cover layer. The 35 soluble layer is fibrous textile waste and the seal layer is synthetic material such as polyvinyl alcohol, applied very thinly by wetting the soluble layer with a dilute solution thereof in solvent, and evaporating away the solvent to leave the seal layer. 40

The described solvent-carried-solids method is rather complex and has certain drawbacks, such as the use of difficult to handle solvents and the need for equipment to accomplish the evaporating. Moreover, the resulting product is not entirely acceptable because pores form 45 upon evaporating the solvent that detract from the basic function of the sealing layer, namely to prevent ingress of moisture to the reaction layer.

Parent copending application Ser. No. 645,508 (corresponding to European Patent Application 80 108 50 243.9), also in the Applicant's name, is directed to a further development of this toilet seat covering and mentions that such a composite foil is also suitable as a packing material and for the making of carrier bags, sachets and the like. 55

The foil of the kind disclosed in this latter application is extremely suitable for many applications. The sealing and reaction layers can be formed as before, but preferably they are pre-formed flat sheets by joined adhesive bonding or welding, for example dissolving the surface 60 of the layer prior to bonding. Preferably, this foil comprises two layers of the same plastics material, but only one of them (i.e., the reaction layer) contains the solubilizers that dissolve both layers of the plastics material when exposed to water. 65

The foil of this general type has now also been found to be particularly useful as a packing material, not only in flexible form, but also in self-supporting form, more

2

particularly in the form of semi-rigid to rigid sheets. Mechanical support capacity and rigidity can be achieved if the polymers of the reaction and/or cover layer are themselves formulated of rigid material or the reaction layer and/or the cover layer are provided with fillers, more particularly mineral fillers and/or fibrous material. In this manner, the reaction layer of the composite foil can be constructed in the same structures as found in packings made of paper, cardboard, pasteboard or corrugated pasteboard. The binder used in the structures is water-soluble or dissolvable by the dissolving intermediary which is contained in the reaction layer, and the dissolving intermediary preferably is effective to cause dissociation of the cover layer. Furthermore, the reaction layer, as done in papermaking, can be produced by accumulating a sediment of the components from aqueous solution in an alkaline or acid medium. The finished composite foil can therefore take conventional forms of blanks for packing material, for example being pre-punched or provided with embossed lines for subsequent folding. The foil can also be pre-shaped into boxes, if necessary with lids. The composite foil is particularly suitable as a packing for items such as cigarettes and other goods whose packaging is frequently thrown away carelessly by consumers and will contaminate the environment, unless it dissolves or rots away quickly.

In one embodiment of the present invention, composite foil is printed on, more particularly in colors. Even use of the foil as an information medium or handbill causes no permanent environmental contamination because even if the packing material is simply thrown away by the consumer, it quickly decomposes upon penetration of moisture. If the reaction layer is produced separately from the cover layer, and since the reaction layer is preferably to be printed on, the capacity to function as a print medium can be aided or the printing process facilitated by the use of suitable fillers in the reaction layer.

SUMMARY OF THE INVENTION

The object of the invention is to provide a composite foil of the aforesaid type, but a foil that is more porefree than known foils and which can be manufactured more simply and cheaply for a variety of specific uses. According to the invention, this object is achieved in that at least the sealing layer of the foil is constructed in non-porous manner by extruding a thermoplastic material which is only soluble in water with the aid of a solubilizer. Preferably, the other layers of the foil are also produced by extrusion. Furthermore, the composite foil according to the invention is produced in a selfsupporting composite sheet that is at least semi-rigid. Mineral fillers and/or fibrous materials are incorporated in the reaction layer, and the overall foil is constructed in structures and with attributes suitable for conventional uses for packings of paper, cardboard, pasteboard or corrugated pasteboard. The foil can be shaped as required for these uses, for example, punched, folded, made into a box or printed upon. The reaction layer and/or sealing layer may include flocculation agents, or such agents may be produced upon dissociation of the layers when exposed to water. The layers can include plant-fertilizing compounds, or opaque metallic vapor coatings can be applied, as required for particular packaging uses.

BRIEF DESCRIPTION OF THE DRAWINGS

There are shown in the drawings the embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise 5 arrangements and instrumentalities shown in the drawings, wherein:

FIG. 1 is a cross-section through an embodiment of the invention in the form of a packaging for dry materials. 10

FIG. 2 is a schematic illustration of the embodiment of FIG. 1, after the package has been opened, demonstrating the entry of moisture.

FIG. 3 is a cross-section through another embodiment of the invention, having inner and outer sealing 15 layrs for packaging of moisture-containing materials.

DESCRIPTION OF THE PREFERRED
EMBODIMENTS

A number of details regarding the construction and 20 use of composite foils, including products and processes, can be found in parent applications Ser. No. 645,508, filed Aug. 30, 1984, and Ser. No. 393,485, filed June 29, 1982. The disclosures of these applications and of U.S. Pat. Nos. 4,469,728 and 4,261,066, are incorpo- 25 rated herein by reference.

The objective of preparing a composite foil having a water-insoluble layer and a reaction layer that releases a solubilizer upon exposure to water, inherently requires certain properties. The sealing layer must be substan- 30 tially waterproof and continuous, or moisture on the sealing layer side will have access to the reaction layer, and cause the foil to deteriorate prematurely. Therefore, one might be led to production of thick sealing layers or production of separate sealing layers that are 35 thereafter joined to reaction layers. On the other hand, a thinner sealing layer will deteriorate more quickly when the eventual exposure to moisture occurs upon the packing being discarded. Moreover, use of a reaction layer in the form of a textile surface or a matt of 40 individual fibers, could lead one toward applying a sealing layer in a flowable liquid form such that interstices in the textile material or fibers would be engaged. According to the invention, all these interests can be accommodated. 45

The cover layer and/or the reaction layer can have on their free surfaces a textile coating of individual fibers which are anchored in the top side of the foil or are glued thereto. The length of the fibers, which are preferably felted with one another to a limited extent, 50 can be in the range of about 0.01 to 2 mm or longer. These fibers reinforce the foil mechanically and prevent sticking as the result of any electrostatic charges. Even if fibers are used in the composition of the foil, the foil will dissolve completely since although the fibers are to 55 some extent felted to one another, they are not permanently interconnected. The fibers preferably used are cellulose, more particularly cotton fibers. Other fibrous materials are also suitable.

The cover layer and the adjacent reaction layer and 60 any further layers are preferably interconnected, or more particularly, welded together over their whole surfaces. They can also be affixed by partly dissolving one and/or the other surface, or by means of an adhesive. The cover layer and reaction layer are preferably 65 made of the same plastics, normally insoluble in water with the reaction layer also containing dissolving intermediary additives for itself and the cover layer. These

additives can be uniformly distributed in the reaction layer or can be localized in higher concentration, for example at the boundary with the cover layer. As a rule the placement of the additives depends on the thickness of the reaction layer and the facility with which the dissolving intermediary can convert water-insolubility into solubility. If the foil has a layer made of a water-soluble material, such as hydroxy-propyl cellulose, this layer need not contain dissolving intermediary additives itself. Instead, the foil can have on the side facing the cover layer an additional intermediate layer which contains the dissolving intermediary additives for the cover layer. The moisture will pass through the soluble layer to the reaction layer.

Since the cover or sealing layer need not be self-supporting, if the reaction layer performs the supporting function, the former is as a rule thinner than the latter. The cover layer can be very thin, much thinner than required to achieve a dependable seal by such processes as the multiple applications of solvent-carried plastic materials known in the art, since it has been found that due to the characteristics of the subject film when produced by extrusion, even a layer thickness of 1 to 5 m, more particularly 2 to 3 mm, is fully adequate to achieve the required density. As a rule, therefore, the thickness of the cover layer is kept less than 10 mm. The thickness of the reaction layer depends upon how many further layers the composite foil contains, and what mechanical loadings they are required to withstand. The reaction layer thickness is at least 10 to 50 mm, and can have the thickness and typical structural shapes of paper, cardboard or pasteboard. The thickness of the reaction layer or layers can be up to 0.5 mm or even 1 mm or more, as required for the particular package. In the case of the reaction layer, there are no limits. Reinforcements can also be inserted into the layers or between the layers, preferably taking care that the reinforcements themselves readily decompose during the dissolution process, as is the case, for example, with individual fibers. The reaction layer can also be porous and even have the openwork structure of corrugated cardboard or pasteboard, more particularly a structure of corrugated pasteboard with a fine corrugation (E-corrugation) and/or a double corrugation. The composite foil can have thicknesses up to 5 mm and above.

If the mechanical loadability of the cover layer is important for a given package, it can be as thick as, or thicker than the reaction layer. For some packages, the cover layer is required to withstand some deterioration or scratching without endangering its resistance to water. In that case, the cover layer can be thicker, or even self-supporting to rigid, so that essentially the only purpose of the polymer of the reaction layer is to act as a carrier or binder for the dissolving intermediary, and not to act as the structural support.

If the thickness of the cover layer is of the order of magnitude of the thickness of the reaction layer, or the cover layer is even thicker than the reaction layer, then reaction layer is preferably so structured and formulated that it dissolves relatively slowly after having absorbed as much moisture as possible. As a result, the dissolving intermediary in the reaction layer can go into solution, and can cause the dissolution of the cover layer before the reaction layer is itself dissolved and the intermediary physically carried away by the dispersal of the reaction layer material. Otherwise there is a risk that the dissolving intermediary will be washed away before the cover layer is dissolved. For this purpose binders