GB2191714A - Long-term desiccation in wrappings, packages and transport containers - Google Patents

Description

GB 2 191 714 A SPECIFICATION which by their permanent action ensure a

relativeair humidityof 50% according to TGL27 217 and even Method of and apparatus for long-term desiccation 40%according to DIN 55474 insidethe packing, in wrappings, packages and transport containers although significant corrosion does not start, in the 70 case of metal packaged goods, u ntil above 70% This invention relates to a method and an apparatus relative humidity, forthe long-term desiccation in wrappings, -the moisture difference that occurs, especially packages and transport containers containing during transport acrossthe equatoror in thetopics, moisture-sensitive goods or articles, such as between the environment and the interior of the precision measuring instruments, electronic and 75 package, on average around 40%, to which the optical products, chemicals, drugs and engineering increase in watervapour permeability of the barrier products, especially for storage and transport layerenvelope is directly proportional, in other overseas, in tropical and sub-tropical regions and words the watervapour permeability of the barrier when crossing the equator. layer envelope increases substantially with It is known, to protect moisture-sensitive goods 80 increasing moisture difference and temperature and and articles reliably againstthe effects of moisture therefore the desiccant inside the envelope is and its consequences, during storage and transport, prematurely consumed, this process being still bywelding orsealing in, gluing orsoldering in into further promoted bythe factthat due to the changing metal containers impermeable to watervapour. This airhumidities in the environmentand theextremely method is costly in working time and materials, and 85 low relative air humidity in the package, the water therefore expensive and uneconomic, expecially vapour basically diffuses only from the outside when used for protecting large goods and articles, inwards through the barrier layer envelope, for example machinetools. It is therefore utilized - damage to the barrier layer envelope which is onlyfor small packaged units and for special caused by slipping and tilting of the packaged transport situations. 90 material, by gnawing of animals and chewing by Afurtherform of protection of goods and articles insects or by leaky seams atthe sheets, and which from the effects of moisture, especially atmospheric can cause considerable loss of the packaged corrosion, is the application of protective coatings, material.

for example those based upon mineral oil, bitumen It isthe objective of this invention to increasethe and cellulose or plastic coverings, which are applied, 95 effectiveness with time of the moisture protection of in a manner permitting peeling-off, when thermally packaged goods, to utilize the desiccants employed softened or diluted with solvents directly onto the more rationally and effectively, and to increase the surface of the goods or articles. reliability of protection of packaged goods f rom This method suffers from the disadvantage that moisture damage and thus from losses.

the vapours of solvent-containing products are 100 The task of this invention is to create a method and combustible and/or harmful to health. Protective an apparatus, the effectiveness of which is based coatings that soften under heat are at risk if the upon the combination of barrier layer envelope, packed material is subjected to heat. When the desiccant container and desiccants, and which shall protective coatings are being removed, there is a risk achieve a lower consumption of desiccants, a longer of damaging the packaged materials. Furthermore, 105 protection against moisture and increased reliability the possibility of rusting underneath exists if water is of protection for the packaged goods.

enclosed beneath the coating when it is applied. According to the invention this task is achieved by Also known is the method of moisture protection a method for the long- term desiccation in by evaporating preparations, known as vapour wrappings, packages and transport containers, by phase inhibitors. When this method is used, it leads 110 using desiccants inside a largely water to the formation of a gas envelope around the va pou r-i m permeable barrier layer envelope packaged material, which prevents formation of rust surrounding the packaged material, inside which provided that no direct action of humidity on the envelope atthe position having the highest air packaged material occurs. humidity desiccants, such as zeoliths, silica gels or Adisadvantage of this method isthe need to 115 hygroscopic salts, are disposed in a virtually airtight, choose chemicals adapted to the particular sealed container, the solution to thistask being that packaged material, especially in the case of metal an automatic, intermittent desiccation of the air packaged surfaces. For some materials having enclosed inside the barrier layer envelope is carried surfaces such as metallic coatings of lead, zinc, out bythe desiccant as a function of the relative air magnesium orthe like, this method cannot be used. 120 humidity exceeding orfalling below an adjustable The form of moisture protection for packaged value which will endanger the packaged materials or materials and goods most commonly used today is articles, of, for example, 65%.

that of enclosing with virtuallywater This method is realized, according to this vapour-impermeable barrier layer envelopes, invention, bythe use of an apparatus for containing combined with watertight boxes and/or containers 125 the desiccants, characterized by a container and desiccants disposed inside the barrier layer consisting of a composite material of aluminium or envelope. plasticfoil on the inside and paper, cardboard, The decisive disadvantages of this method are: vulcanized fibres, pressboard or wood on the -The recommendation, based upon safety outside, in thewalls of which container incisions reasons, for the use of large quantities of desiccants, 130 formed as flaps are introduced in such a manner 2 GB 2 191 714 A 2 that,asa resultofthe intrinsic variations in area permitsa longer effectiveness of thedesiccantand andlorlength orrolling effectof thecontainer thus a more reliable moisture protection materials andlor by mechanisms attached to the accompanied by a reduction in the quantities of flaps, they automatically and intermittently control desiccant.

the air exchange directly and/or assisted by levers 70 This example of embodiment serves for explaining between the desiccant and the air enclosed inside the invention, but does not in any way limitthe the barrier layer envelope, as a function of the numerous possible ways of constructing the relative air humidity. desiccant package, especially in regard to the sizes The present invention will be explained by and shapes of the flaps 9 and the optimum use of reference to an example of embodiment. The 75 materials, withoutthereby needing to departfirom associated drawings show: the scope of this invention.

Figure 1 Desiccant container readyfor use,

Claims (4)

1. Figure2 Section through an opened desiccant CLAIMS container.

   On the inside wails of anytransport container3, 80 1. Method for longterm desiccation in hooks 4 are mounted in the roof zone, from which wrappings and transport containers, using hooks a cylindrical desiccant container 1 is desiccants inside a barrier layer envelope which is suspended by means of a suspension cord 2 inside a largely impermeable to water vapour with materials tightlysealed polyethylene sheet 5. placed in it, characterized in thatthe desiccants The desiccant container 1 consists of vulcanized 85 zeoliths, silica gels or hygroscopic salts are disposed fibres 1.5mirn thick, on the inside of which 0.01 mm in a virtually airtight, closed container in such a thick aluminium foil is giued. U-shaped incisions mannerthat an automatic, intermittent desiccation having an inclination of 300to 600to the container of the air enclosed beneath the barrier layer surface areformed in thewall of the desiccant envelope takes place as a function of the relative air container 1, thus producing flaps 9. When the 90 humidity only when this relative humidity exceeds or relative humidity inside the transport container 3 is fails below an adjustable value, of for example 65%, <60%, the flaps 9 remain closed. which endangers the packed materials.

   If the relative air humidity inside the transport
2. 2. Apparatus forthe method according to Claim container 3 rises above 60%, the moisture 1, characterized by a vessel consisting of a absorption of the vulcanized fibres surface also 95 composite material of al u m iniu m or plastic foil on increases, which leads to expansion of the the inside and paper, cardboard, vulcanized fibres.

   vulcanized fibres, the hydrophobic aluminium layer pressboard or wood on the outside for containing remaining unchanged. The one-sided change in desiccants, in the walls of which incisions formed as length of the vulcanized fibres of approximately 1 %, flaps are introduced so that, as a result of the intrinsic which occurs when the relative air humidity inside 100 increase in area and/or length or rolling effect of the the transport container3 rises from 60% to 75%, container materials andior by mechanisms fitted to brings aboutthe so-called rolling effect atthe flaps 9. the flaps, they automatically and intermittently The flaps 9 bend towards the interior of the dessicant regulate the air exchange directly and/orwith the container and cause the moist air beneath the help of levers between the desiccant and the air polyethylene sheet 5 to penetrate into the desiccant 105 enclosed inside the barrier layer envelope as a container 1, in which a cylindrical paper bag 6, which function of the relative air humidity.

   is filled with silica gel 7, is so arranged thatan
3. 3. Method as claimed in Claim 1 substantially as intermediate space of about 1Omm width exists described herein.

   between thewall of the desiccant container and the
4. 4. Apparatus as claimed in Claim 2 substantially paper bag 6, this space being produced by spacer 110 as described with reference to the accompanying pieces 8, which are fitted to the inner wall of the drawing.

   desiccant container 1.

   In this way, when the flaps 9 are opened, the humid air entering the container 1 can flow around the paper bag 6 and silica gel 7. A portion of the air Printed for Her Majesty's Stationery Office by Croydon Printing Company (UK) Ltd, 11187, D8991685.

   humidity is thus adsorbed bythe silica gel 7, causing Published byThe Patent Office, 25 Southampton Buildings, London, WC2A lAY, the relative air humidity inside the sheet 5 to from which copies may be obtained.

   decrease. This process continues until 60% relative air humidity is again reached in the transport container 3. Since the vulcanized fibre material also gives up moisture again, itshrinks and causesthe flaps 9to close again, so thatthe airaccessto the silica gel 7 is largely interrupted and a further lowering of the relative humiditydown tothe equilibrium humidity abovethe silica gel 7, and therefore also a high partial pressure drop of the watervapour inside and outside thetransport container3, basically causing premature saturation of the desiccant, are avoided.

   The use of the solution according to this invention