DE2239227A1 - WATER-SOLUBLE CONTAINER AND METHOD FOR MANUFACTURING IT - Google Patents

Description

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Dl ".! - Vv '■ ·. I · 1.AMr-KECHT & Δ O Ό 4, Δ (

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65-19.234Ρ (19.235Η) August 9, 1972

ILIKON CORPORATION, NATICK (Massaehueetts), V.St.A.

Water soluble container and process for its manufacture

The invention relates to a multilayer plastic container with a thin removable outer protective * layer and a main layer made of water-soluble thermoplastic Material. The container can also have a thin inner layer.

The problem of the disposal of solid waste of all kinds has been considered in various industrialized countries in recent years has been recognized as extremely important. The elimination of solid waste that cannot naturally be converted into a state return, in which they can be assimilated by the environment, has become the subject of intense research. Containers made of various conventional materials have to be picked up individually as unwanted waste lying around will. Containers made of conventional material such as glass or aluminum are usually completely resistant to a Assimilation by the environment. "Tinplate" (i.e., steel) containers go over to iron oxide after a certain time, this process taking place extremely slowly and they

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represent "eyesores" at this time. Plastic containers show an extraordinarily high resistance to degradation or assimilation by the environment. A particular problem with the disposal of plastic containers made from various polymers is the fact that these container materials develop toxic or noxious gases when burned. As a result, the simple burn disposal method cannot be used.

Various proposals have been made so far for the development of weathering Plastic containers have been made, but these have generally remained in the experimental stage and have been extremely expensive.

According to one of these proposals, bacteria were introduced into the polymer plastics from which the containers were made. These bacteria started multiplying at known rates and after a predetermined period of time began the removal of the 3 container. Although this procedure is theoretically interesting, it has the problem of being accurate Predicting bacterial growth rates under various environmental conditions is a commercial one Use of such materials for containers - as far as known prevented.

Another known development uses plastic materials for containers that are under the influence of decompose ultraviolet rays of the sun. However, there are two difficulties with such weathered containers. The vast majority of storage rooms in which such containers are stored are provided with fluorescent lighting illuminates which emit significant amounts of ultraviolet energy. Therefore, the container might already be decompose on the shelves. In addition, the disposal of the container would also have to take place in an area where he from

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Sunlight is not reached; in this case would - yourself do not degrade such a container.

In recent months, a water-soluble thermoplastic material, hydroxypropyl cellulose, has come onto the market in sufficient quantities. This material, available under the trade name "Klucel", is manufactured by the "Cellulose & Protein Products Department of Hercules", Wilmington, Delaware.

This material can be easily made by conventional plastic molding processes of high capacity processed into containers i'.erden. However, such containers are of limited use commercial use. For example, atmospheric moisture will attack the outer surface of the container, them make it unsightly and allow the content to flow out. Furthermore, such containers could be a flow of water or Exposed to rain, which would cause them to dissolve.

It has been found that when such hydroxypropyl cellulose (hereinafter HPC ',? E-called) containers are provided with an inner and outer protective layer such as a thin polyethylene film, the product obtained is an extremely useful and practical container is well suited to absorb most liquid or solid materials. When the container has served its purpose, the äui3ere protective layer from the container "Dor degradation of the container" is dissolved cold water ^ird.: Thus, by removing the outer protective layer "may be removed and de" simply ^one main part of the container of HPC in dissolved "·. Until this dissolution, the container is not subject to any weathering. Furthermore, the once dissolved HPC container core is not environmentally harmful. In fact, HPC can be eaten by people without harmless effects. Containers of the 'foe's cM4l flat type can pass on conventional machines produced a number of processes

of which oines the same! :! t /, eitir; registered "procedures for forming multilayer articles "is. (See patent application - ITö Ser.No. 170 55C).

The invention is described in more detail below with reference to the drawing explained. Show it:

Fig. 1 is a partially cut side view of a container ge times, the invention,

Fig. ?. a cross section through the container along the section line 2-2 in FIG. 1.

As can be seen from FIG. 1, the container 10 is rrrnä,. < the inventor: designed as a simple bottle with a narrow neck 12, a bead I ^ ;; ur attachment of one not shown Lid and an enlarged part 16 y. To accommodate the Materials. It is composed of three layers of material. the inner and outer layers 18 and 20 are protective layers /.um Protecting the central core part 22. A pull-off extension 24 can be made in one piece with the outer layer, so that can be pulled on the extension 24 after use, thereby removing the outer protective layer 20 from the main part 22 is facilitated. -The structural component 22 is then unprotected and can easily be kept cold as described above Water to be dissolved.

It is noted that the inner protective layer 18 and the outer protective layer 20 meet at the mouth or inlet of the container 26. Such a connection between the two layers is necessary to completely surround the structural core 22 with the protective layers and thereby prevent any degradation to prevent the desired time.

It is understandable that the strengths of layers 18 and 20 are opposite the thickness of the core part 22 are drawn enlarged for the purpose of illustration.

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The actual thickness depends on the method used to apply the protective layers. If, for example, the bottle is produced by injection blow molding with successive casting of the layers 22 and 20 on a molding of the layer 18 - according to the above-mentioned patent application .... - then the smallest thickness of the blown film 20 on the bottle is approx 0.0 ^ 8 mm. If other manufacturing methods described below are used, the protective layers can be thinner than those described. The strength of the core depends on the appropriate conditions, which are determined by the materials to be picked up. For example, if the container is to be used for carbonated beverages, it must be thick enough to prevent bridging caused by the internal pressures of carbonation. It is important to note that the strength of the container is determined almost entirely by the core and that the outer and inner layers serve primarily as protective layers.

In the containers of the present invention, the water-soluble core portion takes up about 85 to 95% of the total volume of the container materials a.

HPC is not soluble in oily substances. Therefore, the inner protective layer 18 of the container can be omitted if the material to be packaged is dry or an oily substance such as vegetable oil.

As stated above, the preferred material for the container core 22 is HPC. It was found that (3 this material can easily be processed into extremely good containers on conventional injection-blow molding machines, with fine details showing up in the manufacturing process. The technical properties of the material are detailed in 61 '! Hercules Chemist "pp. 9-15 (1970) and in "Package Engineering", July 1971, pp. 54 - 57. As in these publications

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executed, the material is In cold water, Lh. at approx. 40 ° C, easily soluble. The solution time depends on the material thickness and the type and amount of additives for water below ¹ K) ⁰ C. It is insoluble in water above 45 ⁰ C. The addition of inert fillers such as talc or starch generally accelerates the dissolution of the material in water, such fillers being expediently added to them during the manufacture of the articles. It has been found that high quality water-soluble bottles can be manufactured from HPC by injection blow molding processes when the HPC is added with at least 50 wt .- # talc (ie about 1/2 HPC and 1/2 talc weight) and the temperature of the heated mixture is approx. 135 ° C.

Other water-soluble thermoplastic polymers used for Formation of the container core part according to the invention are suitable, contain Polyäthyloxide, a product of "Union Carbide Inc." and are sold under the trademark "Polyox", as well as polylactic acids (polylactic acid) from Dynatech Corporation, Cambridge, Massachusetts.

The material for the protective layers must naturally be suitable for the formation of a water-insoluble film. It is therefore necessary when the coated container is manufactured by injection molding, blowing or injection-blow molding that the protective material can be processed in the same temperature range as the core material. Another requirement for at least the outer protective layer is that it is removable from the core material, even when it is fixed to him in the container manufacture. If the complete container is produced in an injection-blow molding process, the shrinkage of the materials must be the same. For the injection blow molding process typical protective layer materials should have a processing temperature in the range of 127 - 160 ° C and a mold shrinkage of 0.2 to 1.0 % , if.

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HPC is used as the core material. Suitable materials for the protective layers contain f.-η polyethylene, acrylonitrile-ethyl acrylate copolymer (which are available under the trade name "Bare * 21θ" from the Vistron Division of Standard Oil of Ohio "), polyvinylidene chlorides (which are available from the Dow -Chemical Company under the trade name "Saran"), the celluloses contain ethyl cellulose, cellulose acetate, cellulose acetate butyrate and cellulose propioiates. Other materials ^: are aluminum foil, cellophane and waxed paper. These materials are applied as a coating in the final molding stage, whereby the mold It has been found that polyethylene is the most suitable material for the protective cover.

As already stated, a method for shaping the inventive Containers with protective layers made of a thermoplastic material are described in the aforementioned parallel application. It states that it is in an injection molding machine a relatively thin molding of the protective layer is first sprayed onto a mandrel mold in a first station, which is then opened and the mandrel on which the molding has been formed is pivoted to a second station, where the material forming the structural core of the container is injected over the first molding. In a third molding station the outer protective sheet material is placed over the assembled one The molding is injected and this is inflated to the desired shape by introducing air through a channel in the mandrel Forming containers in a further blow molding station. The manufactured article is cooled and in a fifth station carried out. If an inner protective layer is not required, only four stations would be required.

Another method of manufacture using a Injection molding 3 blow molding machine consists in the use of preformed Bags or semi-finished products made of the protective material ^ An inner

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Bag is pulled over the mandrel form before the structural core material injected into a mold with the mandrel at its center. The mold is then opened and a second one outer bag slipped over the pin. The entire kit is then placed in a blow mold, in which the blowing of the container takes place to its final shape. The first, inner bag can be omitted if an inner protection does not exist is required. The outer bag can be decorated or labeled beforehand so that the container is already accordingly is decorated when it comes off the injection molding machine. It was found that a polyethylene film of about 0.075 mm Thickness adheres very well to HPC containers to form the desired protective layer. The films after blowing one typical containers are extremely thin, e.g. 0.0075 0.015 mm thick. They adhere well to the HPC material and due to Due to their small volume, they can be easily heated to the blowing temperature by the heat in the HPC molding.

In some designs, especially where an inner layer is not required, the containers can be made from a thermoplastic, water soluble material prepared by any conventional method and thereafter with a film forming polymer can be sprayed to form the desired outer protective layer. In other examples, depending on the shape of the container, It is also possible to coat the inside of the container by spraying on or another treatment such as soaking.

The shape in which the container is blown can also be made using materials such as cellophane, Aluminum foil or waxed paper, which materials adhere to the blown article and the Form an outer protective layer.

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It can be seen that an improved container having a structural core made from a water soluble thermoplastic "Material and at least one relatively thin protective layer on its outer surface to prevent accidental destruction of the holder was created in use. When the container has served its purpose, the thin outer protection can be used layer removed and most of the remaining volume of the container simply dissolved in cold water , whereby the container is easily destroyed.

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Claims (9)

Patent claims 1 Λ container from a relatively thick core part from a water-soluble thermoplastic material, thereby characterized in that the core part (22) on at least one of its outer surfaces is coated with a relatively thin, water-insoluble film, which on peelably adhered to the outer surface of the core part (22). 2. Container according to claim 1, characterized in that the core part (22) on its inner and outer surfaces (18 or 20) has relatively thin, water-insoluble films (18, 20) adhering to the core part, at least the outer surface of the container covering film (20) is easily peelable from the core part (22). 3. Container according to claim 1, characterized in that the Core material is selected from the group consisting essentially of hydroxypropyl cellulose, polyethylene oxide and polylactic Contains polylaetic acid. 4. Container according to claim 1, characterized in that the core material is hydroxypropyl cellulose. 5. Container according to one of the preceding claims, characterized in that «the water-insoluble film on the outer surface of the core part consists of a material from the group which are essentially polyethylene, acrylonitrile-ethyl acrylate copolymer, polyvinylidene chloride, ethyl cellulose, cellulose acetate, Cellulose acetate butyrate, cellulose propionate, aluminum foil / Contains cellophane and waxed paper. 6. Container according to one of the preceding claims, characterized in that the water-insoluble film on the outer surface of the core part is polyethylene. 309803/0290 7. Container according to one of the preceding claims, characterized in that the material of the core is made of hydroxypropyl cellulose and the water-insoluble film on the outer surface of the core is made of polyethylene. 8. Method of manufacturing a multilayered container by. Injection blow molding characterized by the following Process stages: (1) Injection molding a molding on a mandrel mold on which the container can be blown, (2) Open the injection mold and coat the molding with it a bag made of a relatively thin film of thermoplastic material, closed at one end, (3) Placing the coated molding in an open blow mold and closing the mold. (4) blowing the container in the blow mold and (5) Eject the blown container from the mold. 9. The method according to claim 8, characterized in that the Mandrel shape is covered with a bag closed on one side before the molding is sprayed on, the bag consists of a relatively thin film of thermoplastic material. 309 80 8/0290 .c / i ι ; (■ ί Ο "■ · ι! Ί;! Ί IM .: Γ BAD ORIGINAL