PACKAGE FOR A DETERGENT BAR

Abstract

The invention provides a planar (1) stiffener for use in packaging of detergent bars, the stiffener having a machine-direction (MD) and perpendicular thereto a cross-direction (CD), characterised in that said stiffener has a plurality of ribs (2) along its cross-direction. The stiffeners when used in packaging soap or detergent bars are less prone to deformation along the lateral sides (6, 7) and edges of the package (3). This makes the stiffener characteristics more suitable for retaining the envelope wrapped shape of the package to a significant extent until the end consumer point.

Description

FIELD OF INVENTION

The present invention relates to packaging of detergent bars, more particularly to packaging of individual detergent or soap bars using stiffeners.

The invention has been developed primarily for use in packaging of detergent bars and will be described hereinafter with reference to this application. However, it will be appreciated that the invention is not limited to this particular field of use.

BACKGROUND AND RELATED ART

Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of the common general knowledge in the field.

Detergent bars, especially soap bars, are made in various fanciful shapes to attract consumers. Soap bars that essentially are rectangular can readily be wrapped in conventional packages having a combination of a stiffener and a wrapper. The stiffener is included to provide additional strength to the package. The soap bar normally fully supports the wrapper as the wrapper takes the shape of the soap bar. However, when the soap bar is not essentially rectangular, and has curved edges, the package parts usually must provide some of the shape to the package.

An individual bar of soap or detergent after being packaged in a wrapper is then packed in larger cartons before being despatched from the factories. These larger packs are generally referred to as “Corrugated Cartons for Local Delivery” (CLD). These cartons are then transported in bulk to retailing units. The cartons are generally transported in trucks.

During transportation and storage, the packaged soap bar is subjected to mechanical stress. Therefore, the individual packages undergo deformation and damage at several places before reaching the retailing outlets. Such deformed packs are not suitable for display and are generally not acceptable to consumers too. In packages where stiffeners are included, it is observed that the extent of deformation is comparatively lesser. However, it has also been observed by the present inventors that commercially available stiffeners have high stiffness along the machine-direction, but comparatively little stiffness along the cross-direction thereof, which results in packages or wrappers having crushed or deformed lateral sides and/or edges. This particularly is the case in the area of the ends of the soap bar package where there is a transition from a top, bottom and side surface to the folded end surfaces.

One way to solve this problem is by using thicker stiffeners, i.e. ones having higher grammage. Their benefits would normally be offset by the corresponding increase in cost. Another way is to use a corrugated sheet of paper as a stiffener. Their use would, however, lead to an increase in the overall bulk of the pack. In addition, stiffeners made of corrugated sheets may be prone to tear off at their open corrugated ends, after the package is deformed at the edges.

An attempt has been made in the past to solve this problem.

US 2005/0035008 (Colgate Palmolive) describes a wrapper for a soap bar made from a single sheet of material having gusseted end-folds to provide increased rigidity to the pack. This is produced by forming the gusseted end-folds where extra reinforcement is desired. The gussets produce a three layered structure and act as reinforcement bands that reduce deformation of the ends of the pack.

As can be seen here, US '008 relates to packages that essentially aim at achieving additional strength by using extra folds of the wrapper which would require modification of the process and would also lead to an increase the cost.

There exists the need for stiffeners having relatively higher stiffness along the cross-direction so that deformation of packages along the edges and ends that occur while transportation, storage and handling can be prevented or reduced.

OBJECT OF THE INVENTION

It is an object of the present invention to provide a stiffener that has relatively high stiffness along the cross direction.

Conventional single/multiple ply stiffeners used in envelope wrapped products such as soaps and detergent bars, have anisotropic stiffness in machine-direction (MD) and cross-direction (CD), where the stiffness in machine-direction is greater than stiffness in cross-direction due to grain direction of the stiffener. The present invention aims at modifying the cross-direction stiffness by suitable mechanical changes in the stiffener. This makes the stiffener characteristics more suitable for retaining the envelope wrapped shape of the package to a significant extent until the end consumer point. The present inventors have found that planar stiffeners having a plurality of ribs along the cross-direction surprisingly show relatively higher stiffness in the cross-direction, when compared to normal stiffeners. Such stiffeners when used in packaging soap or detergent bars would be less prone to deformation along the lateral sides and edges of the package.

SUMMARY OF THE INVENTION

According to an aspect the present invention relates to a planar stiffener for use in packaging of detergent bars, the stiffener having a machine-direction and perpendicular thereto, a cross-direction, characterised in that the stiffener has plurality of ribs along its cross-direction.

Preferably the angle of the ribs with the cross-direction of the stiffener is from 0° to 45°, more preferably it is 0°. Preferably the distance between the adjacent ribs of the stiffener ranges from 0.5 mm to 2 mm.

According to another aspect the present invention relates to a package for a detergent bar comprising a planar stiffener according to the first aspect of the invention, that surrounds the bar along the longitudinal extent thereof. Preferably the package comprises a wrapper overlaying the stiffener.

According to another aspect the present invention relates to a packaged detergent bar comprising:

• • (i) a detergent bar;
  • (ii) a planar stiffener according to the first aspect of the invention, and
  • (iii) a wrapper overlaying the stiffener.

According to another aspect the present invention relates to a process for preparing a planar stiffener according to the first aspect of the invention, comprising the steps of:

• • (i) softening a tensioned sheet of paper, paper board or polycoated paper by contacting it with a softening agent;
  • (ii) passing the tensioned sheet between a pair of counter-currently rotating grooved rollers operating under pressure from 500 psi to 2000 psi to form a plurality of ribs along the cross-direction of the sheet, the rollers being disposed one of top of the other;
  • (iii) passing the sheet through a heating zone; and optionally,
  • (iv) cutting the sheet to required size.

According to another aspect the present invention relates to an apparatus for making a planar stiffener according to the invention comprising:

• • (i) a means for unwinding a sheet of paper, paper board or polycoated paper;
  • (ii) means for holding the sheet in a tensioned state as it passes through said apparatus, the means being located on either sides of a pair of grooved counter-currently rotating rollers through which the sheet passes in a tensioned state;
  • (iii) a means for spraying softening agent located before the rollers;
  • (iv) a means for heating the sheet located after the rollers; and optionally,
  • (v) a means for winding the sheet.

According to another aspect the present invention relates to use of a planar stiffener according to the first aspect of the invention, in packaging of a detergent bar.

The term “detergent bar” is used herein to indicate a bar or tablet of non-soap or soap-based detergents, which are primarily used for washing clothes, and a bar or tablet of soap, which is used for personal washing.

The terms “soap” and “detergent” have been used interchangeably in the specification.

Stiffener

The term planar is used to indicate that the stiffener is essentially flat, unlike a sheet of corrugated paper.

Preferably, the stiffener is made of coated or uncoated paper. It may also be made of coated or uncoated paper board. It may also be made of plastic or a laminate of paper and plastic, generally known as polycoated paper. More preferably, it is made from paper board, coated on one side with a Polyethylene coating. Polycoated papers are advantageous as in addition to providing strength, they also prevent or reduce loss of aroma/perfume and volatile components from the packaged bar.

Stiffeners have two directions based on the formation on the paper board manufacturing machines. These are known as the machine-direction (MD) and cross-direction (CD). Machine-direction refers to the direction in which the paper travels and it has higher stiffness (usually measured in Taber units) as compared to the cross-direction. The cross-direction is perpendicular to the machine-direction.

It is especially preferred that the stiffener is free from memory so that it does not unfold from a roll on which it was stored and so that it can be folded around the bar of soap, preferably around the entire peripheral longitudinal surface, of the detergent bar, after which the stiffener will remain in the folded condition so as to define a sleeve surrounding the bar. It is preferred that the stiffener entirely surrounds the detergent bar along its longitudinal extent, so as to define a sleeve of the stiffener, housing the detergent bar. It is preferred that the lateral sides of the bar of soap are not surrounded by the stiffeners, so that the bar can be easily removed for use.

It is preferred that the angle of the ribs with the cross-direction of the stiffener is from 0° to 45° and more preferably from 0° to 30°. It is most preferable that this angle is 0°.

Preferably the distance between two adjacent ribs ranges from 0.5 mm to 2 mm. More preferably the distance is 1 mm.

The cross-direction stiffness of the stiffener is from 10 to 40 Taber Units. Preferably it is from 15 to 30 Taber units.

It is preferred that the grammage of the stiffener is from 90 g/m² to 200 g/m², more preferably from 120 g/m² to 170 g/m². It is however most preferable to use low grammage stiffeners from 130 g/m² to 150 g/m². However, a higher grammage stiffener can be used if higher cross-direction strength is sought.

It is preferred that the thickness of the stiffeners is from 120μ to 400μ. However it is preferred that the thickness is from 150μ to 300μ. It is most preferable to use stiffeners having thickness between 250μ and 270μ.

The term “ribs” as used herein is meant to include equivalent terms such as “knurlings”.

It is further preferred that the softening agent is low pressure steam.

It is preferred that the material of construction of the rollers is toughened/hardened steel or stainless steel with or without anti-stick coating.

Any suitable means of heating can be employed in the heating zone.

Generally, the heating zone has one or more heat radiators. Preferably the heating means is an electrical heater or an infrared heater.

Wrapper

The wrapper is a film material comprising a paper core coated on each surface with a plastics material. However, preferably the wrapper is a film material which is entirely of plastics material, more preferably thermoplastics material.

The film material of the wrapper preferably has a thickness of from 5 to 50 microns.

Preferably, the wrapper, when wrapped around the bar of detergent and stiffener, has edge portions in overlapping relationship with one another. This allows those edge portions to be secured to one another. This can be achieved by application of an adhesive between various respective opposite surface regions, for example, by coating the adhesive at various regions of the edge portions, folding the wrapper and applying pressure. However, preferably, edge portions are secured to one another by heat sealing so that at least outer layers of the film material of the wrapper are preferably of heat sealable plastics material. Moreover, the edge portions are preferably kept free of printing material.

Preferably, the film material of the wrapper comprises at least one layer of a Biaxially Oriented PolyPropylene (BOPP) capable of heat sealing. More preferably the film is a laminate of a Biaxially Oriented PolyPropylene (BOPP) layer with a low density polyethylene film.

Preferred examples of alternative constructions of the wrapper are:

• • (a) a laminate of a heat sealable film an internal face of which may bear print material and between which a laminating, for example hot melt, adhesive is applied;
  • (b) a special BOPP film which is capable of heat sealing; and
  • (c) a laminate of a PET (Polyethyleneterepthalate), nylon or low density polyethylene film adhered, for example with a hot melt adhesive, to a heat sealable film.

A package according to the invention containing a soap bar can be produced by a method comprising the steps of:

• folding around at least a longitudinal extent of the bar of soap, a stiffener, so that it is wrapped laterally around the bar; wrapping each of the bar of soap and stiffener with a wrapper in a manner such as entirely to surround each of the bar of soap and stiffener and to provide overlapping edge portions of the wrapper; and
• adhering together, preferably by heat sealing, at least respective parts of the overlapping edge portions to secure the wrapper in position.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

FIG. 1 is the front view of an embodiment of a stiffener according to the invention.

FIG. 2 is the front view of another embodiment of a stiffener.

FIG. 3 is the isometric view of a packaged detergent bar in accordance with the invention.

FIG. 4 is a schematic of a machine used for making the stiffeners according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In all the figures, like numerals have been used to indicate like parts, components or features.

Referring to FIG. 1, the rectangular stiffener 1 has is plurality of ribs 2 that run parallel to the cross-direction (CD) and perpendicular to the Machine direction (MD), which have been shown with the help of arrows. The angle of the ribs with the cross-direction of stiffener 1 is 0°.

FIG. 2 shows another embodiment of a stiffener 1. The angle of the ribs 2 with the cross-direction of the stiffener is 45°.

Referring now to FIG. 3 that shows the isometric view of a packaged detergent bar 3 according to the invention, the bar has longitudinal sides 4 and 5, and lateral sides 6 and 7. The wrapper 8 of the bar is folded over itself along the edges and is adhesively bonded to define the lateral flap 9. A portion of the wrapper is cut-away to show the plurality of ribs 2 on the stiffener 1 that lies beneath the wrapper 8.

Referring now to FIG. 4 that shows a schematic of an apparatus and a process of making the planar stiffeners having plurality of ribs along its cross-direction, a roll of normal (un-ribbed) stiffener made of paper, paper board or polycoated paper is loaded on the mandrel of the unwinder 10 and the same is unwound and pulled by a motor (14) controlled pair of rubber pinch roller 11a and a steel roller 12a. This pair keeps the sheet in a tensioned state. The intended frictional traction force to create the required pull is achieved by friction coefficient of the pair of rollers 11a and 12a, which is decided by the material of construction of the roller pair and normal force on rollers generated by the spring 13a. The sheet so unwound then passes through humidifying arrangement 15a and 15b where low-pressure steam is sprayed on the sheet, which acts as the softening agent. This prepares the sheet for ribbing. Ribbing is achieved by a specially profiled and spring loaded pressurized pair of counter-currently rotating grooved rollers 16a and 16b, pressurized by cylinder 17. The tangential speed of these rollers is decided by a separate driving gear pair (not shown). The stiffener then enters a heating zone where a pair of heaters 18a and 18b supply intense heat by use of Infrared radiators to dry-up and stabilize the deformation added to the stiffeners surface. The next pair of pinch roller 11b and steel roller 12b pulls the stiffener gently without causing any appreciable stretch, which is achieved by motor 19 controlled feedback loop which is part of the process. This loop monitors and controls the take-up velocity of the pair of rollers. Finally the winder 20 operates on tension control principle and tightly rewinds the stiffener. This is then sent to the wrapping machines. The entire operation is controlled with the control means 21.

The invention will now be explained with the help of following non-limiting examples.

EXAMPLES

The Taber stiffness values of Stiffeners made according to the invention, as well as comparative stiffeners, i.e. without ribs were measured. The values have been compiled in tables 1-4 below. In all the tables, MD and CD represent the stiffness in Taber units of the Stiffeners in the Machine direction and Cross direction respectively.

TABLE 1
130 g/m2 stiffeners (without ribs)
PLAIN	MD	CD	POLYCOATED	MD	CD
SAMPLE-1	17	8	SAMPLE-1	13	8
SAMPLE-2	18	6	SAMPLE-2	18	8
SAMPLE-3	20	6	SAMPLE-3	15	6
SAMPLE-4	13	8	SAMPLE-4	15	6
SAMPLE-5	15	8	SAMPLE-5	15	6
AVERAGE	16.6	7.2	AVERAGE	15.2	6.8
*Average Thickness of 130 g/m2 stiffeners: PLAIN - 196μ; POLYCOATED - 208μ

TABLE 2
150 g/m2 stiffeners (without ribs)
PLAIN	MD	CD	POLYCOATED	MD	CD
SAMPLE-1	35	10	SAMPLE-1	25	13
SAMPLE-2	25	17	SAMPLE-2	28	10
SAMPLE-3	35	20	SAMPLE-3	25	12
SAMPLE-4	25	20	SAMPLE-4	28	15
SAMPLE-5	25	17	SAMPLE-5	25	13
AVERAGE	29	16.8	AVERAGE	26.2	12.6
*Average Thickness of 150 g/m2 stiffeners: PLAIN - 233μ; POLYCOATED - 239μ

TABLE 3
175 g/m2 stiffeners (without ribs)
PLAIN	MD	CD	POLYCOATED	MD	CD
SAMPLE-1	40	25	SAMPLE-1	37	15
SAMPLE-2	40	25	SAMPLE-2	28	15
SAMPLE-3	40	25	SAMPLE-3	33	18
SAMPLE-4	38	23	SAMPLE-4	30	15
SAMPLE-5	42	20	SAMPLE-5	33	18
AVERAGE	40	23.6	AVERAGE	32.2	16.2
*Average Thickness of 150 g/m2 stiffeners: PLAIN - 277μ; POLYCOATED - 283μ.

Stiffness Values of Stiffeners According to the Invention.

TABLE 4
130 g/m2 polycoated stiffeners
	SAMPLE	MD	AVERAGE	CD	AVERAGE
	SAMPLE-A	30	30	20	20
	(500 psi)	40		20
		25		20
		25		20
	SAMPLE-B	20	24	10	12.5
	(400 psi)	30		15
		30		15
		15		10
	SAMPLE-C	15	15	10	12.5
	(300 psi)	15		10
		15		10
		15		20

The average thickness of 130 g/m² (Ribbed) stiffeners was 260μ. Distance between adjacent ribs was 1 mm. The angle of ribs was 0° with respect to the cross direction of the stiffener. The pressure of the grooved rollers through which the stiffeners were passed has been indicated in brackets.

The stiffeners were made of Rough cartridge board paper which can be obtained from Andhra Pradesh Paper Mills, Star Paper Mills or Century Paper Mills.

The paper was then extrusion coated with Polyethylene (10μ) by processes generally known in the art.

Thus it can be readily appreciated that the Cross Direction stiffness of the Stiffeners according to the invention (table 4, Sample-A) is relatively higher than stiffeners of table 1 to 3. It can also be appreciated that the stiffness increases as the pressure is increased. This therefore means that at a lower grammage, it is possible to have a stiffener that has relatively higher Taber stiffness in the cross-direction.

It will be appreciated that the illustrated examples, provide for a stiffener that has relatively high stiffness along the cross direction.

Although the invention has been described with reference to specific embodiments, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.

Claims

1. A planar stiffener for use in packaging of detergent bars, the stiffener having a machine-direction and perpendicular thereto a cross-direction, characterised in that said stiffener has plurality of ribs along its cross-direction.

2. A planar stiffener as claimed in claim 1 wherein the angle of said ribs with the cross-direction of said stiffener is from 0° to 45°.

3. A planar stiffener as claimed in claim 2 wherein said angle is from 0° to 30°.

4. A planar stiffener as claimed in claim 3 wherein said angle is 0°.

5. A planar stiffener as claimed in any one of the preceding claims, wherein the distance between the adjacent ribs ranges from 0.5 mm to 2 mm.

6. A planar stiffener as claimed in claim 5 wherein said distance is 1 mm.

7. A planar stiffener as claimed in any one of the preceding claims wherein the cross-direction stiffness of said stiffener is from 10 to 40 Taber Units.

8. A planar stiffener as claimed in claim 7 wherein said stiffness is from 15 to 30 Taber units.

9. A planar stiffener as claimed in any one of the preceding claims, wherein the grammage of said stiffener is from 90 g/m2 to 200 g/m2.

10. A planar stiffener as claimed in claim 9 wherein said grammage is from 120 g/m2 to 170 g/m2.

11. A planar stiffener as claimed in claim 10 wherein said grammage is from 130 g/m2 to 150 g/m2.

12. A planar stiffener as claimed in any one of the preceding claims, wherein the thickness of said stiffener is from 120μ to 400μ.

13. A planar stiffener as claimed in claim 12 wherein said thickness is from 150μ to 300μ.

14. A planar stiffener as claimed in any one of the preceding claims, wherein said stiffener is made of paper, paper board, or polycoated paper.

15. A package for a detergent bar comprising a planar stiffener as claimed in any one of the preceding claims that surrounds said bar along longitudinal extent thereof.

16. A package as claimed in claim 15 wherein said package comprises a wrapper, overlaying said stiffener.

17. A packaged detergent bar comprising: (i) a detergent bar;(ii) a planar stiffener as claimed in any one of the preceding claims 1 to 14, and(iii) a wrapper overlaying said stiffener.

18. A process for preparing a planar stiffener as claimed in any one of the preceding claims 1 to 14, comprising the steps of: (i) softening a tensioned sheet of paper, paper board or polycoated paper by contacting it with a softening agent;(ii) passing said tensioned sheet between a pair of counter-currently rotating grooved rollers operating under pressure from 500 psi to 2000 psi to form a plurality of ribs along the cross-direction of said sheet, said rollers being disposed one of top of the other;(iii) passing said sheet through a heating zone; and optionally,(iv) cutting said sheet to required size.

19. A process as claimed in claim 18 wherein softening agent said is low pressure steam.

20. A process as claimed in claim 18 or 19 wherein said heating zone comprises one or more heat radiators.

21. An apparatus for making a planar stiffener as claimed in any one of the preceding claims 1 to 14 comprising: (i) a means for unwinding a sheet of paper, paper board or polycoated paper;(ii) means for holding said sheet in a tensioned state as it passes through said apparatus, said means being located on either sides of a pair of grooved counter-currently rotating rollers through which said sheet passes in a tensioned state;(iii) a means for spraying softening agent located before said rollers;(iv) a means for heating said sheet located after said rollers; and optionally,(v) a means for winding said sheet.

22. An apparatus as claimed in claim 21 wherein the means for holding said sheet in a tensioned state includes two pairs of rollers, each said pair comprising a rubber pinch roller and a steel roller.

23. An apparatus as claimed in claim 21 wherein said softening agent is low pressure steam.

24. An apparatus as claimed in claim 21 wherein said means for heating comprises one or more heat radiators.

25. Use of a planar stiffener as claimed in any one of the preceding claims 1 to 14 in packaging of a detergent bar.

26. A package substantially as herein described with reference to the accompanying examples and figures.

27. A planar stiffener substantially as herein described with reference to the accompanying examples and figures.

28. A process substantially as herein described with reference to the accompanying examples and figures.

29. An apparatus substantially as herein described with reference to the accompanying figures and examples.

30. A packaged detergent bar substantially as herein described with reference to the accompanying figures.