PH26324A

PH26324A - Casting method

Info

Publication number: PH26324A
Application number: PH37917A
Authority: PH
Inventors: Terry Instone; Richard Barrie Edwards
Original assignee: Unilever Nv
Priority date: 1987-12-15
Filing date: 1988-12-13
Publication date: 1992-04-29
Also published as: AU2681988A; JPH01207399A; TR24216A; MY104355A; JP2549903B2; BR8806607A; CA1323281C; AU606486B2; ZA889316B; EP0321179A1; KR890010182A; KR920002115B1; GB8729221D0; IN169447B

Description

CASTING METHOD

The present invention relates to a method of casting a material, such as s0ap, non-scap detergent or mixture thereof, in a liquid or semi-liguid state

Ti into a pack.

US 149188 describes a method of casting soap inte a pre-formed mould which is designed to serve as a package or container for the ready-to-use cake and subjecting the liquid mass in the mould to cooling whereby the mass solidifies into & cake having the te contour of the mould. The mould is airtightly sealed after casting. The moulds are preferably rigid or semi-rigid bodies whose shape determines the shape of the cake of soap. The mould can he plastic and can have flexible wall portions whose depression will facilitate the removal of the ready-to-use cake from the mould. The method is applicable to transparent soap and thus obviates the traditional open cast method of casting transparent z2oap into blocks and cutting the blocke into bars and overcomes the shrinkage, loss of perfume and surface deterioration problems associated with open cast bars.

Rather similarly, FR 9107256 describes a method of casting liquid seoap into a pre-formed mould which is retained as an envelope around the soap and thus delivered to the consumer. The mould should be suffi- ciently rigid to retain its shape when empty. = Dom

According to the present invention there is provided a method of casting material comprising scap, non—-eoap detergent or mixture thereof, the method comprising filling the material in a liquid or semi & liquid state into a pack made at least substantially of a flexible film, airtightly sealing the pack, allowing the material to set substantially and retaining the set material in the pack as an airtight storage means. .

The present invention thus provides a method of casting and simultaneously packing & material such as soap. Use of flexible film can be economical with regard to the initial cost of the pack material. The method can he carried cut on a continuous basis. More- over, a supply of empty packs can be stored in a flat 1& ar rolled form, or a supply of flexible film for mal ing packs can be stored and converted into packs only imme- diately prior to use. 1f desired forced cocling can be employed whilst the material is being allowed to set.

The present method can be carried out on a high speed packaging machine anslogous to a conventional machine for forming and filling sachets. The method can thus not only be performed at high speeds, but also pbhviates the need to form and store rigid three- dimensional packs prior to use. Moreover, the 2% invention enables a molten mixture to be made directly into a bar oF the like having rounded corners and edaes and of a pleasing shape. Thus unlike conventional casting of zoap mixture inte large slabs followed by cutting into blocks with prominent edges which require time consuming die stamping, the present method can readily and speedily produce suitably shaped bars or a3 the like.

The present method can allow the shape of the pack to be controlled by contact with the exterior of the pack during the setting of the material. Thus for example a filled and sealed pack made substantially from flexible film could, for example, be lightly moulded in a die and/or have a motif impressed on it.

A filled and sealed pack could be pressed between two surfaces in order to produce a bar or tablet-like shape. The surfaces could be flat or one or both of them could be, for esample, concave so as to produce a substantially "cushion" shaped bar. The control need only be exerted for as long as necessary for the mate- rial to assume a permanent shape. Fressures in the range 0.1 to 0.3kaf/em” are preferred, the actual pressure selected depending on the properties of the pack in each case.

In order to give an attractive appearance, it is very desirable that the pack should be a shkin-tight wrinkle-free fit over the cast material within. To accomplish this, it can be beneficial to shape the pack . hy distending it with internal pressure, which can be done in various ways.

Pressing the exterior of a filled and sealed pack between two surfaces to control its shape will tend to reduce the volume to surface ratio and so pressurize the incompressible material within the pack. The a internal pressure then distends and tensions the film material.

The pack may be of a heat-extendible material, i.e. a material which can stretch permanently when sufficiently hot. If stretching occurs at the temperature of the material filled into the pack, the pack will stretch and adjust its shape under the hydrostatic pressure of the hot material in the pack and/or pressure in that material arising from pressure on the pack exterior. Stretching of flat film to adjust ite shape to that of the filling of the pack will of course mean that the film is no longer flat.

Another possibility is to use a heat-shrinkable flenible film. As this shrinks onto the material in the pack it will pressurize this material which will accordingly stretch the shrinking film taut.

Yet another possibility is that the pack could be at least partially shaped prior to filling. This could * be carried out by blowing, e.g. into a mould, which is a further instance of shaping the pack by distending it 2% with internal pressure, and again stretching the film.

The film will remain flexible, but the shaping of it will influence the shape which the pack takes vihen filled.

In order to achieve a shin-tight fit the material preferably cooupies substantially the whole internal wolume of the pack on being airtightly sealed. Contact between the material and air can thus be excluded which a could he of importance in achieving a long shelf life.

Buch an arrangement can also ensure that when the material is unpached immediately prior to use, due to the close contact between the material and the pack, the material is presented to the consumer having an untldemished and even surface APPEAR ance.

The flexible film ie preferably made of thermo- plastic material. The pack suitably comprises tao layers of its constituent film in the form of a bag or sachet having an open end into which to fill the 13 material. In dite wused far the pack material either performed into sachets or as separate sheets of film can therefore be stored flat ar for example in rolls as supplied from the manufacturers. .o

The two layers of film can, for example, be formed inte a bag or sachet by sealing them together along one

QF more seams so ae to define the flat (unfilled) shape of the pack while leaving an unsealed portion as the filling opening. The seal could extend around the total periphery of the pack or alternatively the pack 2% could be derived from a tube of flexible film material having & transverse seal at one end and being open at the cther end so as te allow the pack to be filled.

For a thermoplastic material the seal can conveniently he performed by heat welding. Any “skirt” of the film material projecting outwardly from the seam({s) can be trimmed away from the set product. flternatively a a nekirt” of film may be avoided by employing knife-edge . welding methods.

It is preferred that a film material is employed which allows the pack when filled to he airtightly sealed by heat welding through a slight excess of soap 140 ar the like at the opening to the pack. This can ensure that the material poocupies the whole internal volume of the pack, and ensures exclusion of any air from the pack.

Preferably the pack is formed immediately prior to 1% filling with both pperations carried out on the same machine. Where the pack is formed from two layers of ite constituent film, the pach can be filled with the . ce material and aivtightly sealed, with the sealing step conveniently forming at the same time at least a portion of the seam of the next pack to be filled. The precent process can thus readily lend itself to pperation on & continuous basis. For example a four cide sealed sachet/vertical fill process could be employed.

The flexible film can readily be removed from the bar ar the like immediately prior to use by a peeling action. 1 desired a tear strip(s) or the like can be wm 7 o= included integral with the flexible film or attached for example glued to the flexible film in order to help initiate removal of the film from the bar. Alterna- tively the film can be made of a water-soluble material

T which dissolves during the firet use of the bar or the like.

The actual film selected in Ny one case will depend on the circumstances of each case. Conveniently the film will be selected such that it can be heat- 1 sealed. A variety of heat-eealing methode are svailable and generally involve melting the film layers in contact. The available methods include radio frequency or dielectric, bar, band, impulse, hot wire or knife and ultrasonic welding. As mentioned above, the film may have properties such that it can extend and/or shrink around the material being packed so as to provide & skin-tight and wrinkle-free fit at the temperatures encountered on contact with the liquide or seEmi-liquid material and/or during the time that the material is wetting.

Suitable flexible film materials are commercially available. Euxamplesz include palyvinylohloride, polyvinylaleoohol, ralyethylene, Nylon (trade name for palyamide}, Surlyn (trade name for ethylene methacry- late copolymer) and polyethyleneterephthalate mistures thereaf. The thickness of the film selected mey depend inter alia on the degree of adiustment, if = gq = any. required in the film in order to provide a skin-tight and wrinkle—free fit. For palyvinylcholo- ride film for example the preferred thickness range ia from 10 to 60 pun, with a mare preferred thickness being from 30 to S90 pm. 14 desired laminated, co-extruded or other multi layer films can be employed. Far example a multitayer film could be employed which is designed to combine the goad heat-asealing characteristics of one polymer with the barrier/shigh melting point or other useful charac teristics for example ease of printing of anather. The

Film could for instance be printed with & motif, the product’ s name oF advertising. Irn =come applications it may bee preferable to employ transparent film so that 1% the cast zoap har or the like can be readily viewed.

The present method can be applicable to any castahle soap, NON-SGAap detergent or mixture thereof.

The soap and/or non-sbhap detergent being packed can of course include any additional materials conventionally found in toilet or laundry bars. In particular, however the method obviates the probleme encountered in | ” traditional pressing technigues as well as those jtemised in U.S. 31371683 having regard to transparent bars. The method can thus be especially applicable to transparent, translucent and low fatty matter soap bars.

It is to he understood that the present invention extends to bars, tablets, cakes, blocks ar the like of

EDAD, non-soap detergent or mixtures thereof airtightly sealed in a pack according to the present method.

Embodiments of the present invention will now be described by way of example arly and with reference to

I] the accompanying drawings in which:

Fig. 1 shows a pack formed hy heat-sealing two sheets of flexible film;

Fige. 2a, 2b, 2c and 2d are side views of the pack seen in the direction of arrow IT of Fig. 1 showing progressive stages from filling to finished product

Fig. 3 diagrammatically illustrates the forming and filling of packs on a vertical forming and filling machine, and is a view on arrow [11 of Fig.d;

Fig. 4 iz a diagrammatic view of film being formed 13 and filled on the machine, seen in the direction of arrow IV of Fig. 3.

Referring first to Fig. 1 of the drawings. a } preformed pack 10 waz prepared hy averlaying two layers of flat polyvinylocholoride film, each laver having a 200 thickness of 130) micron, and radio frequency welding the two layers together along a seam 12 which is generally in the shape of a U narrowing at the top with a curvature substantially symmetrical to the closed bottom end of the U. Seam 12 defines a bag with a filling neck 14 at the top of the bag.

Q, .

Molten soap at a temperature of ahout 807°C was poured dows the neck 14 into this bag, so as to fill = 4) wm the bag to capacity and provide an edCess extending up the neck 14 to the line indicated at 1&. The pack was held upright and closed across itz top opening by heat-sealing through the soap composition along the

Se line 18.

The polyvinylcholoride material of the bag stretched at the temperature of the soap poured inte it co that a= the bag was filled it distended and slreteohed to the shape shown by Fig. Za. This shape ie little changed by sealing as shown by Fig. 2b.

After sealing the filled pack was shaped so that ite side view became as shown in Fig. 2d. One possibility for doing this was to place the pach in a mould completely currounding it and allow cooling in the mould until the soap had eet. Such a mould needed ‘ to be slightly larger than the filled pack so as to avoid destroying the pack hy attempting to confine it in a space which was too small.

The alternative to this, which was preferred, was to press the pach between twee plates 20 arranged substantially parallel to each ather and to a plane containing the welded =eam of the pack az shown in Fig. 2c. To do this, these plates and the filled pack were placed in & horizontal positicn. The upper plate ) 25 carried a weight 22 so as to apply & pressure on the pack of about o.2kaf/eme. The pressure =s0 applied was maintained until the soap in the pack had cocled and set. This pressure applied to the pack served to maintain a pressure within the pack and thus to distend the film of the pack.

The resulting product had an attractive a appearance, the cast bar being substantially "cushion shaped and the polyvinylochloride film being a skin—tight and wrinkle-free fit, any creases which originally formed around the seam disappearing due to the film stretching and accommodating itself in order to conform to the contours of the pressed bar. The neck 14 was cut away, and a “skirt” of film projecting around the seam 12 was also readily cut away in order ta improve the overall appearance of the product yet . further. }

Figs. 3 and 4 illustrate diagrammatically the continuous forming and filling of packs. The packs are formed from flexible film laminate comprising a supporting material and a heat-sealahle material at one face of the laminate. Two webs of the film laminate are drawn off from a pair of supply reels 30 so that the heat-sealable faces of the film laminates contact each other and become the inside surfaces of packs. At a first station 32, the two layers of film are sealed together along a pair of side seams 34 which extend generally vertically and have curved upper and lower end portions, as shown in Fig. 4. Fig. 3 shows station 32 just before the =eams 34 are formed at this stationg accordingly they are shown in chain dotted lines in

Fig. 4. After a pair of such seams x4 has been formed, the film is draw dewwmardly to bring the seams 24 to the positions indicated 34°. A filling nozzle 36 2 rrajects downwardly between these Seams. Horizontal sealing is carried out at a second station 42. Sealing at this station occurs across the line 44 shown chain dotted in Fig. 4. 1+ closes ane pack and simulta necusly forms the pattom af the next pack in sLCCEBE lon. fs shown by Fig. 4 the pack 44 which ie currently immediately below the station 42 has its bottom closed bey seam 44° frrmed in a previous cycle of operation.

Before sealing takes place at the station 42 this pach 86 ie filled with molten soap frou the nozzle 36.

Filling continues until an excess of soap partially fills the pack 48 above, e.@. Up to the level BO.

Sealing at the station 42 seals through the =oap atong the line 44 so forming an airtight seal to close the pack 4éb6. gimul taneously it forms the bottom seam far the pack 48 next in succession. The filled packs are separated hy shears 57 cutting horizontally through a previously formed seam 44".

Machinery for carrying out the process illustrated a 2% by Figs. 3 and 4 can he derived from conventional machinery for forming and filling four sided sealed ceachets. Figs 3 and 4 illustrate a process carried out down & single vertical column but it is feasible to have a number of such columns arranged side by side. Ce

Far carrying cut a process as illustrated by Figs. oan 4 & suitable film material is 50 micron Mylon

GD {polyamide) laminated with a 40 micron layer of Surlyn which is & heat-sealable cross-linked ethylene methacrylate copalymer. The Nylon does not stretech at the temperature (aoc) of the molten soap.

In & development of this process & further station ie included at which the heat-sealable laminate is heated and stretched to a desired shape (while remaining flexible) by introducing air pressure between the twee layers of film before a pack is filled with

EE. = {4 == ‘a

Claims

1. A method of casting a material comprising soap. & honosaap detergent ar a minture thereof into colid bar form, the method comprising? partially forming a pack hy sealing together o two layers of flexible film to define a pack with a bottom seam, & pair of cide edges and & top . CRE ing, . filling the material in & liquid or semi liquid state and at an elevated temperature into said pack, airtightly sealing the pack while the material is still liquid or semi--1iguid allowing the material to cool and set to & substantially walid bar, and retaining the hav of 15% cet material in the pack as an airtight storage Means, wherein the distance between the sides of the pack narrows adjacent hoth ends of the pack vihere- bry the corners of the solid bar formed inn the pack are shaped by the narrowing between aaid sides of the pack. 2 Method as claimed in claim 1 wherein the material ccoupies substantially the whole internal volume cf the pad ko. 2% =. Method a= claimed in claim 1 wherein sealing of the pack is effected by sealing throuah the material.

4. Method as claimed in claim 1 including forming the pack immediately prior to filling. Te 5. Method as claimed in claim 4 wherein the sealing step defines at the same time at least a portion of the next pack to be filled.

“. Method as claimed in claim 1 wherein sealing of the pack is effected by sealing through an excess of : 1 the material to form a seam which seals the pack wholly filled with the material and defines & portion of the boundary of the next pach to be filled.

7. Method as claimed in claim 1 including ’ distending the pack with internal pressure to shape the pack Tor ochtaining & close fit to the material filled therein.

7. Method as claimed in claim 1 wherein the pach ie heat-extendible.

9. Method a= claimed in claim 1 wherein the pach 2: ie heat-shrinkable.

19. Method as claimed in claim 1 including at least partly shaping the pack prior to filling.

11. Method as claimed in claim 1 including | ’ contacting the exterior of the pack to control the shape of the pack during the setting of the material.

12. Rar, tablet, block, cake or the like of soap. non-soap detergent or mixture thereof, and cast to = Lh = shape and airtightly sealed in a pack by & method as claimed in claim 1.

1%. A method of casting a material comprising snap, a Nnon-eEcap detergent or a mixture thereof into ” = enlid bar form, the method comprising: partially forming & pack by sealing together two layers of flexible $ilm to define a pack with a bottom seam, a pair of side edges and a top opening. . filling the material in & liquid or sem— liquid state and at an elevated temperature inta said pack, airtiahtly sealing the pack while the mate rial is =till liguid or semi-liqguid, allowing the material to cool and set to a substantially sclid bar, and retaining the bar of cet material in the pack &s an airtight storage MEANS , wherein the flexible film is heat-extensihle ar heat-shrinkable so as to defarm while the material therein is still liquid or cemi—-liguid, thereby to shape the salid bar formed in the pack.

14. Method as claimed in claim 13 wherein sealing af the pack is effected hy =zealing through an excess of the material to form a seam which seals the pack wholly filled with the material and defines a portion of the boundary of the nest pach to be filled.

1%. Rar, tablet, block, cake or the like of soap, non-soap detergent or mixture thereof, cast to shape and airtightly sealed in a pack by a method as claimed = in claim 13.

16. A method of casting a material comprising soar, a non-scap detergent or a mirture thereof into z=olid bar form, the method comprising: partially forming a pack by sealing together two layers of flexible film to define a pack with a bottom seam, a pair of side edges and a top Qper ing, filling the material in a liguid or semi- liquid state and at an elevated temperature into satd pack, airtightly sealing the pack while the mate- rial is still liquid or semi-liquid, allowing the material to cool and set to a substantially solid bar, contacting selected areas orn either side of the pack as the material therein conls, sa as to pressurize the material and distend the pack, and retaining the har of set material in the pack as an airtight storage means. 2% 17. Method as claimed in claim 14 wherein sealing af the pack is effected by sealing through an excess of the material to form a Seam which seals the pack wholly : filled with the material and defines a portion of the boundary of the next pack ta be filled.

18. Har, tablet, block, cake or the like to soap. & non—-soap detergent or minture thereof, cast to shape . and airtightly sealed inn & pack by a method as claimed in claim Lé&. TERRY IMBTONE and RICHARD BARRIE EDWARDS Inventors '