CH715851A2 - Water soluble plastic article. - Google Patents

Abstract

In the case of a plastic product (1) with a plastic body (2) injection-molded or deep-drawn from water-soluble polyvinyl alcohol (PVOH), it is provided that the surface of the plastic body (2), which from the completion of the plastic product (1) up to and during the intended use Use of the plastic product (1) is exposed to ambient moisture or a water-containing substance, is completely coated with a continuous, water-impermeable and water-resistant protective layer (3), and that the plastic body (2) after the intended use of the plastic product (1) if a uncoated surface or after destruction of the continuous protective layer (3) is completely soluble in water and the protective layer (3) is applied so thin that it disintegrates after dissolution of the plastic body (2) or can be separated from the aqueous solution by filtration.

Description

Technical area

The invention relates to a plastic product with a water-soluble polyvinyl alcohol (PVOH) injection-molded or deep-drawn plastic body.

Technical background

There is an increasing need for environmentally friendly plastic products. In particular consumables, e.g. Disposable items such as plastic plates, cups or cutlery, but also plastic packaging containers such as food, luxury goods or pharmaceutical packaging, should increasingly be environmentally friendly or compostable.

For example, to produce compostable plastic products, compostable respectively. Biodegradable plastics such as starch-based polymers (starch blends), polylactide (PLA), polyhydroxyalcanoate (PHA), polyhydroxybutyrate (PHB), polyhydroxyvaleate (PHV), or cellulose materials made from chemically modified cellulose. After their usage phase, these materials are partially or completely broken down into water and carbon dioxide by microorganisms such as fungi and bacteria, but are sufficiently stable that they survive the necessary storage times until the end user.

In addition to compostability, plastic packaging containers should now have a barrier layer against oxygen in order to increase the shelf life of the contents. For this purpose, the plastic packaging containers are provided with a barrier layer which greatly reduces the gas permeability of commonly used plastics.

[0005] From WO2009030425 and EP1048746, for example, methods and devices for producing packaging parts (including injection molded parts) with a barrier layer with a good penetration barrier against water vapor and gases are known. The packaging parts are formed here by thermoforming flat film material, by injection molding or by a combination of injection molding and blow molding (injection blowmolding) or extrusion and blow molding (extrusion blowmolding) and are made of polyethylene (PE), polypropylene (PP), cycloolefin copolymer (COC), Cycloolefin polymer (COP), polyvinyl chloride (PVC), polyethylene terephthalate (PET) or polyamide (PA), with compostable polymers such as starch-based polymers (strong blends), polylactide (PLA), polyesters of the type polyhydroxyalcanoate (PHA), polyhydroxybutyrate ( PHB), polyhydroxyvaleate (PHV), or cellulose materials made from chemically modified cellulose. The packaging parts are then provided with a ceramic and / or metallic vacuum coating using a plasma CVD process or a sputtering process.

[0006] WO2015082982 describes a compostable plastic packaging container made of compostable polylactide (PLA) with a compostable barrier layer made of polyvinyl alcohol (PVOH). The plastic packaging container is manufactured by injection molding using a co-injection process in which a PVOH barrier layer a few micrometers thick is injected into a mold between two outer PLA layers. Such plastic packaging containers are indeed compostable, respectively. biodegradable, but their complete decomposition by microorganisms such as fungi and bacteria is usually only possible by means of industrial composting under defined conditions. Composting e.g. however, on the home compost would take many months to years.

WO9846668 describes a synthetic resin coating for biodegradable articles. The coating has irregularities, respectively. Have flaws, so that water can penetrate to the underlying, water-impermeable layer of the article. Alternatively, a hydratable coating is described which, upon contact with water, swells and tears, exposing the underlying, water-impervious layer of the article. However, the coating is not suitable for injection molded articles that have to have a long shelf life of several months to several years or that come into contact with aqueous liquids during storage.

Presentation of the invention

One object of the invention is to provide a plastic product which can be stored for several months to years and can be disposed of in an environmentally friendly manner in a simple manner after use as intended.

[0009] This object is achieved by a plastic product with the features of the independent claims. The plastic product has a plastic body which is injection-molded or deep-drawn from water-soluble polyvinyl alcohol (PVOH). The surface of the plastic body, which is exposed to ambient moisture or a water-containing substance from the completion of the plastic product up to and during the intended use of the plastic product, is completely coated with a continuous, waterproof and water-resistant protective layer. Furthermore, after the intended use of the plastic product, the plastic body can be completely detached if a non-coated surface is exposed or the continuous protective layer has been actively destroyed in water, preferably between 10 and 60 degrees Celsius.

The protective layer is applied so thin that it disintegrates after the dissolution of the plastic body or can be separated from the water. For example, the protective layer can respectively. the remaining parts of the protective layer are deposited from the aqueous solution containing PVOH, e.g. by filtration.

The protective layer preferably comprises parylene or an inorganic-organic hybrid polymer, which is known under the name ORMOCER and was developed by the Fraunhofer Institute for Silicate Research (DE).

Alternatively, the protective layer is made of a material with a melting temperature between 50 ° and 90 ° Celsius, preferably 60 ° to 85 ° Celsius. At temperatures above the melting temperature, the protective layer is destroyed and the exposed plastic body is accessible for dissolution in water.

The fusible protective layer comprises a material selected from shellac, wax such as e.g. Beeswax, carnauba wax or paraffin wax, or combinations thereof. Shellac approved for use in foods, preferably with a melting temperature between 65 to 85 ° C., is particularly suitable as shellac.

The plastic product thus has a shaping plastic body, which is formed from water-soluble polyvinyl alcohol (PVOH), and a thin water-resistant coating which collapses or crumbles after dissolution of the supporting plastic body. Surfaces of the plastic body which are only exposed to moisture or water after their intended use do not have to be coated. Such a plastic product is available from manufacture up to and during its intended use, i.e. from the completion of the plastic product or the article comprising the plastic product, through storage to the point in time at which the intended use of the product or article ends and this is possibly partially destroyed, stable and stable.

PVOH is a water-soluble thermoplastic material which, depending on the degree of polymerization and degree of hydrolysis, decomposes on contact with water within minutes to hours. dissolves. Because of its water solubility, PVOH has not been used as a load-bearing, shaping material for plastic products such as disposable items or packaging parts, except in applications in which the packaging is to be dissolved during use (e.g. water-soluble packaging of dishwasher tablets). In the plastic product according to the invention, however, the plastic body is made entirely of PVOH (injection molding, deep drawing, blow molding, etc.) and provided with a water-resistant protective layer. The protective layer guarantees the durability of the plastic product until it is used as intended, even in the presence of water. As soon as the plastic product is to be disposed of, the protective coating is partially removed, e.g. by breaking, cutting or shredding the plastic product, or an uncoated surface, is exposed at the end of the intended use, so that the plastic body made of water-soluble PVOH becomes accessible to water and can dissolve. The plastic body is therefore completely soluble in water and can, if necessary, after separation of coating residues in the water, be disposed of via a sewage treatment plant in which the PVOH dissolved in water is biodegraded.

On the surfaces that are exposed to ambient moisture or a water-containing substance from the completion of the plastic product up to and during the intended use of the plastic product, the water-resistant protective layer is complete and continuous, i.e. it has no defects or holes and completely covers this surface.

With a water-resistant protective layer is meant a layer which is neither hydrolyzable nor hydratable from the completion of the plastic product until and during the intended use of the plastic product. There is no degradation or dissolution by water.

In some embodiments, the PVOH can be moisture resistant so that it does not degrade from humidity alone. Dissolution only takes place in water or in an aqueous solution.

In some embodiments, the PVOH can be dissolvable at room temperature within 2 hours, preferably within 60 minutes, more preferably within 30 minutes.

In some embodiments, the PVOH can only be soluble in water from a temperature of at least 40 ° C., preferably above 50 ° C., within 2 hours, preferably within 60 minutes, more preferably within 30 minutes.

As plastic products come in particular consumables, respectively. Disposable items such as plastic plates, cups or cutlery, medical disposable items such as e.g. Syringes, syringe plungers and needle holders, or single-use laboratory items such as Reagent vessels and pipette tips, or plastic packaging containers, for example for food, luxury goods or pharmaceuticals are possible.

In some embodiments the plastic body can be a plastic packaging container that is provided with a closure part, e.g. in the form of a sealing film or a plastic closure, can be closed. Such a plastic packaging container has a particularly good barrier effect against e.g. Oxygen is excellent because it consists almost entirely of PVOH. The barrier effect is additionally increased with the protective layer.

In some embodiments, the inner surface of the closed packaging container may not be provided with the protective layer. This is particularly the case when the contents of the package are completely dry. After opening and consuming the contents, the plastic body of the plastic product can respectively. Packaging container can simply be dissolved in water, since the inner surface of the plastic body is not coated.

The plastic packaging container can for example be designed in the shape of a cup with a circumferential sealing flange. The closure part can be a conventional aluminum foil that is applied to the flange. When used, the aluminum foil is removed and disposed of separately. The plastic body of the packaging container can then be dissolved in water.

In order to achieve a good seal, a sealing area of the flange can be free of the protective layer. This can be easily achieved by coating the plastic packaging container with the flange resting on a support with the protective layer. The support area does not receive a protective layer.

In some embodiments, at least the outer surface of the plastic packaging container, which is exposed to the outside environment in the closed state of the plastic packaging container, is coated with the protective layer. However, such a plastic packaging container is only suitable for dry contents. In the case of moist or liquid contents, the plastic packaging container is provided with a protective layer on the outside and inside.

In some embodiments, the plastic body can be a closure means for a plastic packaging container. This can be used together with the plastic packaging container described above. The closure means can be a sealing film which has no protective layer in the sealing area.

In some embodiments, the closure means can be a plastic closure which can be placed onto a plastic packaging container in a sealing manner.

In some embodiments, the plastic product can be a catering product, for example cutlery, a plate or a drinking vessel.

In some embodiments, the plastic product can be dimensionally stable and self-supporting.

In some embodiments, the protective layer can be 0.01 to 500 µm (micrometers), preferably 50 to 200 nm (nanometers) thick.

In some embodiments, the protective layer can be applied by means of vacuum coating processes.

The plastic body of the plastic product can be manufactured with the usual manufacturing processes, e.g. Injection molding, deep drawing, blow molding, extrusion, etc. can be manufactured.

In some embodiments or as an alternative solution, the plastic body can be made of cold water soluble PVOH, which is already in cold water, i. at temperatures below 20 ° C, is readily soluble, the surface of the plastic body, which is exposed to ambient moisture or a water-containing substance from the completion of the plastic product until and during the intended use of the plastic product, completely coated with a continuous protective layer, also made of PVOH is, which but only in warm water, ie is soluble at temperatures above 40 ° C, preferably above 50 ° C. The plastic body is after the intended use of the plastic product in the dissolution or. the destruction of the continuous protective layer completely soluble in warm water. The thinly applied protective layer is also completely loosened, which further facilitates environmentally friendly disposal. The plastic body can preferably be completely dissolved at 20 ° C. within 2 hours, more preferably within 60 minutes. The protective layer of warm water-soluble PVOH is preferably only soluble at temperatures above 40 ° C, more preferably above 50 ° C, and protects the easily soluble plastic body underneath from humidity and direct contact with “cold” aqueous substances. Only at high water temperatures is the protective layer finally destroyed and the plastic product dissolves completely in the water in a short time. This embodiment is particularly suitable for single-use products with shorter life cycles of a few months that come into contact with cold liquids when used as intended. Examples are e.g. Cups for cold drinks or containers for fresh products, e.g. Salad. This embodiment can also be viewed as an independent invention.

Brief explanation of the figures

The invention is to be explained in more detail below on the basis of exemplary embodiments in connection with the drawing (s). Show it: <tb> Fig. 1 <SEP> shows a sectional view of a plastic product in the form of a plate; <tb> Fig. 2 <SEP> shows a sectional view of a plastic product in the form of a packaging container closed with a sealing film; and <tb> Fig. 3 <SEP> shows a sectional view of a plastic product in the form of a packaging container closed with a plastic closure.

Ways of Carrying Out the Invention

Fig. 1 shows a plastic product 1 in the form of a plate. The plate has a plastic body 2 made of water-soluble polyvinyl alcohol (PVOH). In order to protect the plate from water and thus its decomposition respectively during the intended use. To protect dissolution, it is completely provided with a protective layer 3 impermeable to water vapor. The protective layer 3 preferably comprises parylene or an inorganic-organic hybrid polymer. In this way, the plastic body 2 made of PVOH is from decomposition, respectively. Dissolution protected by water until the PVOH underlying the protective layer, e.g. is at least partially exposed by breaking or cutting the plastic product 1.

Figures 2 and 3 each show a closed plastic packaging container 4. The plastic packaging container 4 comprises a container body 6 and a sealing means 5 sealing the container body 6 a protective layer 3.

In the embodiment shown in FIG. 2, the container body 6 is cup-shaped and has a sealing flange 7, onto which a closure means 4 in the form of a sealing film is glued or welded. Depending on the type of sealing, the sealing flange 7 can be one which is not provided with the protective layer 3, i.e. have a sealing zone free of protective layers. The sealing foil can be a conventional sealing foil made of aluminum, which is disposed of separately after removal. Alternatively, the sealing film can also have a plastic body made of PVOH, which is provided with a protective layer 3 described above.

In the embodiment shown in Fig. 3, the container body 6 is designed in the shape of a bottle. The closure means 5 in the form of a plastic closure can be attached to the bottle neck in a sealing manner. The plastic closure generally has a plastic body 2 made of PVOH, which is provided with a protective layer 3 described above.

Designation list

1 plastic product 2 plastic body 3 protective layer 4 plastic packaging container 5 closure means 6 container body

Claims (14)

1. Plastic product (1) with a water-soluble polyvinyl alcohol (PVOH) injection-molded or deep-drawn plastic body (2), characterized in that the surface of the plastic body (2), which is from the completion of the plastic product (1) until and during the intended use of the plastic product (1) is exposed to ambient moisture or a water-containing substance, is completely coated with a continuous, water-impermeable and water-resistant protective layer (3), and that the plastic body (2) after the intended use of the plastic product (1) when a non-coated one is exposed Surface or after destruction of the continuous protective layer (3) is completely soluble in water; wherein the protective layer (3) is applied so thinly that it disintegrates after the dissolution of the plastic body (2) or can be separated from the water, and / or wherein the protective layer (3) has a melting temperature between 50 ° and 90 ° Celsius, preferably 60 ° to 85 ° Celsius. 2. Plastic product according to claim 1, characterized in that the protective layer (3) comprises parylene or an inorganic-organic hybrid polymer. A plastic product according to claim 1, characterized in that the protective layer (3) comprises a material selected from shellac, wax, e.g. Beeswax, carnauba wax or paraffin wax, or combinations thereof. 4. Plastic product according to claim 1 or 3, characterized in that the PVOH can be dissolved at room temperature within 2 hours, preferably within 60 minutes, more preferably within 30 minutes. 5. Plastic product according to claim 1 or 3, characterized in that the PVOH can only be dissolved in water from a temperature of at least 40 ° C, preferably above 50 ° C, within 2 hours, preferably within 60 minutes, more preferably within 30 minutes . 6. Plastic product according to one of the preceding claims, characterized in that the plastic product is a packaging container (4), in particular a food, luxury food or drug packaging. 7. Plastic product according to claim 6, characterized in that the inner surface of the closed packaging container (4) is not provided with the protective layer (3). 8. Plastic product according to claim 6, characterized in that the packaging container (4) is provided with the protective layer (3) only on the outside or on the outside and inside. 9. Plastic product (1) according to one of claims 6 to 8, characterized in that the packaging container (4) is closed with a closure means (5), preferably in the form of a sealing film or a plastic closure. 10. Plastic product according to one of the preceding claims, characterized in that the plastic product is a catering product, for example cutlery, a plate or a drinking vessel. 11. Plastic product according to one of the preceding claims, characterized in that the plastic product is dimensionally stable and self-supporting. 12. Plastic product (1) according to one of the preceding claims, characterized in that the protective layer (3) is 0.01 to 500 µm (micrometers), preferably 50 to 200 nm (nanometers) thick. 13. Plastic product according to one of the preceding claims, characterized in that the protective layer (3) is applied by means of a vacuum coating process. 14. Plastic product (1) with a cold-water-soluble polyvinyl alcohol (PVOH) injection-molded or deep-drawn plastic body (2), characterized in that the surface of the plastic body (2), which from the completion of the plastic product (1) until and during the intended use of the plastic product (1) is exposed to ambient moisture or a water-containing substance, is completely coated with a continuous protective layer (3) made of warm water-soluble polyvinyl alcohol (PVOH), and that the plastic body (2) after the intended use of the plastic product (1) upon dissolution resp. after the continuous protective layer (3) has been destroyed in warm water, preferably only at a water temperature above 40 ° C, more preferably above 50 ° C, is completely soluble.