A process for obtaining a package containing mutually reactive particulate materials and a package containing such materials

Abstract: A process for obtaining a package containing at least two mutually reactive materials comprises the steps of introduc­ ing the reactive materials into an envelope suitable for vacuum packing, placing the reactive materials within said envelope in separate layers with at least one intervening separating layer of a material which is inert relative to the adjacent layer of a reactive material, evacuating and sealing the envelope.

Description: This invention relates to a process for providing a package containing at least two mutually reactive particulate photographic materials by arranging said particulate photographic materials in separate layers with at least one intervening layer of a solid particulate material which is inert relative to each adjacent layer of reactive material interposed therebetween, and to a package containing such materials. The development of exposed photographic films comprises the step of successively passing said films through developer and fixing baths consisting of aqueous solutions of substances which are solid at room temperature. During use, the efficiency of such baths gradually decreases and, therefore, fresh baths have to be prepared at certain intervals. Some of the solid materials which are used for the preparation of such developer and fixing baths tend to react with one another to form undesired reaction products if they are brought into direct contact with one another. Therefore, they cannot be shipped to the user in the form of a mixture. It has been customary to pack these substances or groups of substances in separate packages and to effect the mixing shortly before or in connection with the preparation of said baths. This has resulted in relative high packaging and transportation costs and has also caused problems for the user who is to prepare said baths. Thus, the user has to take extra care that the correct materials are used in the correct proportions. It has been attempted to avoid these problems by preparing concentrates of the desired solutions and to send these concentrates to the users, who then have to dilute the concentrates to make them suitable for use. This solution presents the serious disadvantage that a substantial amount of water has to be transported from the manufacturer to the user and that such concentrates cannot be sent as air freight because the airline companies normally are unwilling to transport solutions of chemical compounds. A further problem involved in the transportation of concentrates is that a precipitate which may be difficult to re-dissolve can be formed if the concentrate is cooled during such transport. In a known process of the above-referenced type (GB-A-6 652) the reactive layers and the interposed intervening layer are formed by pressing the materials in the shape of a tablet. Optionally encapsulation of such a tablet in a capsule or covering the tablet with a coating is provided in order to protect the tablet against the action of actinic light. The packing of the materials in the form of pressed tablets is, however, disadvantageous in that more time and/or energy is necessary to have the pressed tablets dissolved in water to make up a solution ready for use as compared to the dissolution of loosely packed particulate material. With the tablets enclosed in a capsule or covered by a coating it is moreover necessary to break the capsule or remove the covering prior to use, thereby introducing further inconveniences for the user at the time of processing the materials. In the altogether different field of preparing ready-for-use foodstuffs it has been proposed by US-A-4 081 560 to provide for an instant cream and sugar containing coffee combination in which the acid in the coffee is prevented from rendering the milk protein in the cream rancid. For this purpose it is alternatively proposed to either arrange the sugar component between the coffee and cream components in a bag containing the combination or to position the cream component directly adjacent to the coffee component while the bag enclosing the components is evacuated to subatmospheric pressure. In this latter case the powders of coffee and cream which are the reactive components of the combination are still in contact with each other at the border surface therebetween. It is an object of the invention to provide for a process and a package of the above-referenced type which allow for easier handling of the packaged photographic materials when making use in preparing the desired bath solutions. This object is attained in the process in accordance with the invention by introducing said layers in an envelope suitable for vacuum packing and evacuating and sealing said envelope. The package according to the invention is characterized by enclosing said layers in a sealed envelope, the pressure within said envelope being subatmospheric. In the package made in accordance with the invention the particles of a vacuum-packed solid material do not move substantially relative to one another, even if the package is subjected to rough handling and the two reactive materials forming the two separate layers in such in a vacuum package can be prevented from contacting one another by providing one or more separating layers between the layers of these materials. In addition to the above mentioned advantages the process of the invention presents the advantages which are obtained by conventional vacuum-packaging, viz. that atmospheric oxygen and moisture are excluded. An additional advantage is that the volume of the packed materials is as small as possible which is particularly significant as far as transportation costs are concerned. The term "inert" used herein means that the materials when physically contacted with one another do not react under the conditions prevailing in the package or that any reaction is insignificant. The inert material may be a substance which apart from being inert relative to the two mutually reactive materials is inactive as far as the intended use of the two active materials is concerned but can also be a substance which has to be used simultaneously with the two reactive materials. A typical developer bath is prepared from a developer substance, such as hydroquinone; sodium sulfite; borax; a strong base, such as sodium hydroxide; potassium bromide and one or more additives. Hydroquinone and sodium hydroxide react with one another in solid state and should consequently not be in direct contact during transportation and storage prior to the preparation of the developer bath. However, by providing in a vacuum package a layer of sodium sulfite and borax as a separating layer between a layer of hydroquinone and a layer of sodium hydroxide, these materials can be stored in the same package for long periods of time without any adverse effect on the developer bath subsequently prepared from said materials. The vacuum-packaging of the two mutually reactive substances and the intervening material or materials can be effected in a conventional manner. However, it is preferred to use separate means for successively supplying the materials to the envelope. The envelopes used are preferably bags prepared from an inactive, air-tight plastics film or a laminate of a plastics material and a metal foil. The invention also relates to a package comprising a sealed envelope comprising separate layers of at least two mutually reactive materials separated by at least one layer of a material which is inert relative to the material of the adjacent layer, the pressure within said envelope being subatmospheric. The invention will now be described in further detail with reference to the following example: EXAMPLE The following substances were introduced into a bag consisting of an aluminium foil coated with a plastics material and each substance was caused to form a layer on top of the substance previously introduced into the bag: Ethylene diamine tetraacetic acid 20 g Hydroquinone 312 g 1-Phenyl-3-pyrazolidone 8 g Sodium sulfite 1250 g Potassium bromide 75 g Borax 312 g Sodium hydroxide 168 g Total 2145 g . Subsequently, the bag was evacuated and sealed in a conventional manner. The bag was stored for 1½ months and was then opened and the contents dissolved in water. During use of the developer bath thus obtained it was found that its properties were similar to those of a freshly prepared developer bath.

Claims: A process for providing a package containing at least two mutually reactive particulate photographic materials by arranging said particulate photographic materials in separate layers with at least one intervening layer of a solid particulate material which is inert relative to each adjacent layer of reactive material interposed therebetween, characterized by introducing said layers in an envelope suitable for vacuum packing and evacuating and sealing said envelope. A process according to claim 1, characterized in that the envelope is made of a plastic film. A process according to claim 1, characterized in that the envelope is made of a laminate of a plastic material and an aluminium foil. A process according to anyone of the preceding claims, characterized in that the photographic materials are to be used in a photographic developer bath. A package containing at least two mutually reactive particulate photographic materials arranged in separate layers with at least one intervening layer of a solid particulate material which is inert relative to each adjacent layer of reactive material interposed therebetween, characterized by enclosing said layers in a sealed envelope, the pressure within said envelope being subatmospheric.

Inventors: NIELSEN KAJ, NIELSEN, KAJ
Applicants: DELTAGRAPH AS, DELTAGRAPH A/S
Application year: 1986
Main classification: B65D81
IPC codes: B65B31, G03C5, B65D77, B65D81, B65B29