Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65B—MACHINES, APPARATUS OR DEVICES FOR, OR METHODS OF, PACKAGING ARTICLES OR MATERIALS; UNPACKING
  • B65B11/00—Wrapping, e.g. partially or wholly enclosing, articles or quantities of material, in strips, sheets or blanks, of flexible material
  • B65B11/50—Enclosing articles, or quantities of material, by disposing contents between two sheets, e.g. pocketed sheets, and securing their opposed free margins

Definitions

• the invention relates to a process for producing a thermoformed package of the type comprising the steps of placing a first sheet of formable film over a forming die having a cavity, moulding the film into the cavity thereby forming a recess in the film, placing a composition in the thus formed recess, and sealing a second sheet of film across the recess to close the package.
• the invention relates to such a process for producing a water- soluble package containing a detergent composition.
• Detergent compositions for the machine washing of laundry are provided in many forms.
• Probably the most prevalent form of laundry detergent is washing powder or granules.
• a problem with the use of these forms of detergent is that the product needs to be dosed into the machine in such a way that the detergent is quickly and thoroughly dissolved in the wash water of the machine without coming into contact with the laundry in a solid form.
• many dosing devices which overcome this problem have been proposed.
• 0 343 070 and 0 343 069 teaches the use of a flexible fabric sock which holds the particulate detergent in the machine, the fabric of the sock being permeable to water so as to allow water enter the sock and carry the detergent out of the sock through the fabric walls in the form of an aqueous solution.
• More recently unit dose forms of detergent have been proposed in the form of compressed tablets of detergent powder.
• a problem encountered with the provision of detergent tablets is that the tablets need to be strong enough to withstand storage and transport, yet weak enough to disintegrate and dissolve quickly in the washing machine.
• a further problem is the need to prevent the tablets "posting" in the porthole and between the drums of conventional washing machines.
• thermoformed package of the above mentioned type the process being characterised in that the or each cavity in the forming die has a curved edge, wherein at least a portion of the curved edge is formed from a material which is less hard and more deformable than the material of the cavity.
• at least a portion of the curved edge comprises a resiliently deformable material.
• a predominant portion, and most preferably a whole, of the curved edge is formed of a resiliently deformable material.
• the curved edge comprises an annular gasket of resiliently deformable material, which gasket is mounted in a circumferential groove around the or each cavity. In such a case, the gasket should be dimensioned such that, when mounted in the groove, an exposed surface of the gasket should be flush with a surface of the cavity.
• the or each cavity is surrounded by a raised flange, wherein at least a portion, and ideally most or all, of the raised flange comprises resiliently deformable material.
• the curved edge and flange are preferably integrally formed.
• a single gasket preferably comprises the curved edge and the flange.
• a ratio of a width of the flange to a minor diameter of the cavity is between 1:50 and 1:10, preferably about 1:12.
• the resiliently deformable material is preferably silicone rubber, however other suitable material performing the same function are envisaged.
• the film is heated by a heating plate.
• This may be flat but preferably has at least one concave depression which in use overlies the at least one cavity, wherein the heating step involves the step of bringing the film into intimate contact with the or each depression.
• the use of a heating plate having concave depressions helps to ensure that the film when heated thermoforms uniformly which results in a package having less weak spots.
• intimate contact between the film and the concave depression is achieved by exerting a vacuum between the depression and the film.
• the depression may include holes through which the vacuum may be pulled.
• the heating plate may comprise a porous material.
• the vacuum should ideally comprise a pressure of up to 1 Bar, and preferably be less that 0.6 Bar.
• the film is forced into intimate contact with the concave depression by blowing air against it. Typically the pressure of the blown air will be less than 5 Bar, preferably less than 3 Bar.
• the heating plate preferably has a temperature in the region of 100 to 120 degrees C, and ideally is approximately 110 degrees C.
• the time the film contacts the heating plate depends to a large extent on the type of film used and the temperature of the heating plate, the time of contact between the film and the plate should be in the region 0.1 to 5 seconds, preferably 0.5 to lseconds, ideally approximately 700 milliseconds.
• the film is a water- soluble film.
• the package contains a liquid, gel or other type of fluent composition.
• the liquid comprises a detergent or any other type of active agent used in the machine washing of laundry or dishes .
• the package contains a bathing or shower gel composition or any other type of personal care composition.
• Fig 1 is a sectional view illustration portions of a forming die and heating plate for use with the process of the invention
• Fig 2 is a detailed sectional view of a concave depression of Fig 1 ;
• Fig 3 is a detailed sectional view of an edge of a forming cavity according to the invention.
• thermoforming process where a number of packages according to the invention are produced from a sheet of water soluble material, namely polyvinyl alcohol supplied under reference CC8534 from Chris Craft.
• recesses are formed in the sheet using a forming die having a plurality of cavities with dimensions corresponding generally to the dimensions of the packages to be produced.
• a single heating plate is used for moulding the film for all the cavities, and in the same way a single sealing plate is described.
• a first sheet of polyvinyl alcohol film is drawn over a forming die so that the film is placed over the plurality of forming cavities in the die, the details of which are described in further detail below. In order to maximise package strength, the film is delivered to the forming die in a crease free form and with minimum tension.
• the film is heated to 110 degrees C, for approximately 700 micro seconds.
• a heating plate 1 is used to heat the film, which plate is positioned to superpose the forming die 2.
• the plate includes a plurality concave depressions 3 (only one is shown) which correspond to the cavity 4 on the forming die 2.
• Each concave depression is generally circular having a diameter of approximately 50mm and a depth of about 5mm.
• An edge 5 of the depression 3 is radiussed as is the base 6, the radius of the base being about 50mm and the radius of the edge being about 30 mm.
• a vacuum is pulled through the pre-heating plate to ensure intimate contact between the film and the pre-heating plate 1, this intimate contact ensuring that the film is heated evenly and uniformly (the extent of the vacuum is dependant of the thermoforming conditions and the type of film used, however in the present context a vacuum of less than 0.6 bar was found to be suitable)
• Non-uniform heating results in a formed package having weak spots.
• the vacuum it is possible to blow air against the film to force it into intimate contact with the preheating plate. In such cases the air should be blown at a pressure of less than 3 Bar.
• thermoformed film is thus moulded into the cavities forming a plurality of recesses which, once formed, are retained in their thermoformed orientation by the application of a vacuum through the walls of the cavities. This vacuum is maintained at least until the packages are sealed.
• the composition in this case a liquid detergent is added to each of the recesses.
• a second sheet of polyvinyl alcohol film is then superposed on the first sheet covering the filled recesses and heatsealed thereto using a heating plate.
• the heat sealing plate which is flat, operates at a temperature of about 140 to 160 degrees centigrade, and contacts the films for 1 to 2 seconds and with a force of 8 to 30kg/cm2, preferably 10 to 20kg/cm2.
• each cavity 4 is generally dome shaped having a curved edge 10 with a radius of curvature.
• a raised flange 11 surrounds each cavity to ensure that the films are sealed together along the flange to form a continuous seal.
• the radiussed edge 10 and raised flange 11 are both formed a by a resiliently deformable material gasket 12 of silicone rubber. This results in reduced force being applied at the inner edge of the sealing flange to avoid heat/pressure damage to the film.
• the packages formed are separated from the web of sheet film using cutting means. At this stage it is possible to release the vacuum on the die, and eject the formed packages from the forming die. In this way the packages are formed, filled and sealed while nesting in the forming die. In addition they may be cut while in the forming die as well .
• the relative humidity of the atmosphere is controlled to ca . 50%. This is done to maintain the heat sealing characteristics of the film.
• it may be necessary to reduce the relative humidity ensure that the films have a relatively low degree of plasticisation and as such tend to be stiffer resulting in easier handling.
• the actual specific RH of the atmosphere needed will vary according to the temperature of the environment and the type of film used, however for temperatures in the region of 20 degrees C, the RH should be in the region of 30 to 50% depending on the thickness and elasticity of the film.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Containers And Plastic Fillers For Packaging (AREA)
• Packages (AREA)
• Wrappers (AREA)
• Paper (AREA)
• Moulds For Moulding Plastics Or The Like (AREA)
• Blow-Moulding Or Thermoforming Of Plastics Or The Like (AREA)
• Detergent Compositions (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=10849833

Family Applications (1)

Country Status (14)

Families Citing this family (21)

Family Cites Families (3)

• 1999
  • 1999-03-17 GB GBGB9906179.8A patent/GB9906179D0/en not_active Ceased
• 2000
  • 2000-02-29 DE DE60000684T patent/DE60000684T2/de not_active Expired - Lifetime
  • 2000-02-29 CN CN00805103.8A patent/CN1344210A/zh active Pending
  • 2000-02-29 AU AU29161/00A patent/AU2916100A/en not_active Abandoned
  • 2000-02-29 CA CA002360805A patent/CA2360805A1/en not_active Abandoned
  • 2000-02-29 WO PCT/EP2000/001647 patent/WO2000055044A1/en not_active Application Discontinuation
  • 2000-02-29 TR TR2001/02518T patent/TR200102518T2/xx unknown
  • 2000-02-29 AT AT00907646T patent/ATE226905T1/de not_active IP Right Cessation
  • 2000-02-29 CZ CZ20013334A patent/CZ20013334A3/cs unknown
  • 2000-02-29 RO ROA200101005A patent/RO118861B1/ro unknown
  • 2000-02-29 BR BR0009048-4A patent/BR0009048A/pt not_active IP Right Cessation
  • 2000-02-29 ES ES00907646T patent/ES2184696T3/es not_active Expired - Lifetime
  • 2000-02-29 EP EP00907646A patent/EP1161368B1/de not_active Expired - Lifetime
• 2001
  • 2001-06-20 ZA ZA200105054A patent/ZA200105054B/en unknown

Non-Patent Citations (1)

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