WO1994006623A1 - Improvements to the patterning of tissue paper - Google Patents

Improvements to the patterning of tissue paper Download PDF

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Publication number
WO1994006623A1
WO1994006623A1 PCT/GB1993/001962 GB9301962W WO9406623A1 WO 1994006623 A1 WO1994006623 A1 WO 1994006623A1 GB 9301962 W GB9301962 W GB 9301962W WO 9406623 A1 WO9406623 A1 WO 9406623A1
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WO
WIPO (PCT)
Prior art keywords
paper
embossing
roller
liquid
tissue paper
Prior art date
Application number
PCT/GB1993/001962
Other languages
French (fr)
Inventor
David Wyn Bassett
Ivan Gbur
Brian Tomkinson
Original Assignee
J R Crompton Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GB929219605A external-priority patent/GB9219605D0/en
Priority claimed from GB939302646A external-priority patent/GB9302646D0/en
Application filed by J R Crompton Limited filed Critical J R Crompton Limited
Priority to AU48255/93A priority Critical patent/AU4825593A/en
Priority to GB9505242A priority patent/GB2286159B/en
Publication of WO1994006623A1 publication Critical patent/WO1994006623A1/en

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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B32LAYERED PRODUCTS
    • B32BLAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B38/00Ancillary operations in connection with laminating processes
    • B32B38/04Punching, slitting or perforating
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B31MAKING ARTICLES OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER; WORKING PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31FMECHANICAL WORKING OR DEFORMATION OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31F1/00Mechanical deformation without removing material, e.g. in combination with laminating
    • B31F1/0003Shaping by bending, folding, twisting, straightening, flattening or rim-rolling; Shaping by bending, folding or rim-rolling combined with joining; Apparatus therefor
    • B31F1/0006Bending or folding; Folding edges combined with joining; Reinforcing edges during the folding thereof
    • B31F1/0009Bending or folding; Folding edges combined with joining; Reinforcing edges during the folding thereof of plates, sheets or webs
    • B31F1/0019Bending or folding; Folding edges combined with joining; Reinforcing edges during the folding thereof of plates, sheets or webs the plates, sheets or webs moving continuously
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B31MAKING ARTICLES OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER; WORKING PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31FMECHANICAL WORKING OR DEFORMATION OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
    • B31F1/00Mechanical deformation without removing material, e.g. in combination with laminating
    • B31F1/07Embossing, i.e. producing impressions formed by locally deep-drawing, e.g. using rolls provided with complementary profiles
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B32LAYERED PRODUCTS
    • B32BLAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00Properties of the layers or laminate
    • B32B2307/70Other properties
    • B32B2307/726Permeability to liquids, absorption
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B32LAYERED PRODUCTS
    • B32BLAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2317/00Animal or vegetable based
    • B32B2317/18Cellulose, modified cellulose or cellulose derivatives, e.g. viscose

Definitions

  • tissue paper which term is used herein to represent wet or dry laid paper having a basis weight between 6 and 50 g/m 2 preferably between 10 and 26g/m 2 and used for example as filtration bags used for the infusion of products such as tea or coffee.
  • This process commonly referred to as hot calendering also affords improved surface smoothness and moreover a reduction in opacity, and is most conveniently achieved by passing the tissue paper through the nip of hot rolls.
  • the given optical transmission values were obtained by a parallel beam of light from a first light source transmitted perpendicularly through the sample and recorded by a photocell whilst optical surface scatter was determined by the proportion of light from a second light source reflected back to a photocell placed close to a second light source and inclined at an angle of 45° to the paper surface.
  • the hot calendering was conducted on a commercial two plain steel roll stack over the full width of the paper at the given temperature with the nip pressure exerted by hydraulic rams.
  • embossing Such a process is commonly referred to as embossing which term is used herein to refer to any localised calendering technique resulting in a profile in the thickness of paper in the longitudinal or transverse direction of the paper between the affected areas. It is also recognised that the application of heat during the embossing process improves fibre compaction giving rise to the terminology "hot embossing".
  • hot embossing Experiments conducted with a commercial hot embossing unit further demonstrated that the hot calendering physical changes exemplified in Table 1 could be duplicated within the embossed regions as illustrated in Table 2. In these examples, the emboss consisted of a diamond shaped lined structure occupying 32% of total surface area.
  • a process for patterning tissue paper as herein defined by embossing a continuous strip of paper characterised in that embossing is carried out in the course of conversion of the strip into tissue paper products.
  • apparatus for converting tissue paper into patterned product comprising means for converting a continuous strip into said product, characterised in that embossing means is provided for embossing the strip in the course of such conversion.
  • a process for patterning tissue paper as herein defined comprising subjecting the paper to the action of a heated embossing roller coated with a liquid adapted to enhance the patterned effect obtained by the embossing operation and/or the strength of the paper in the embossed area.
  • apparatus for patterning tissue paper as herein defined comprising an embossing roller defining a nip with a coacting pressure roller, means for heating the embossing roller, means for guiding the paper into the nip, and means for coating the embossing roller with a liquid adapted to enhance the patterned effect obtained by the embossing operation.
  • Fig. 1 is a schematic view of one embodiment of apparatus in accordance with the invention.
  • Fig. 2 is a schematic view of one embodiment of tea bag conversion machine illustrating the invention
  • Fig. 3 is a schematic view of a second embodiment of tea bag conversion machine illustrating the invention.
  • Fig. 4 is a further embodiment of the invention incorporated in a schematically illustrated tea bag conversion machine.
  • a papermaking machine is indicated diagrammatically at PM and produces paper P which is guided by suitable guide means (not shown) through the nip of a roller pair in which the lower roller 1 provides a counter-surface for an upper, heated embossing roller 2 having a profiled surface including raised portions or projections indicated diagrammatically at 2a.
  • the papermaking machine produces tissue paper having a basis weight of 6 to 50 g/m 2 preferably 10-26 g/m 2 .
  • the papermaking machine may use a wet or dry laying process to produce tissue paper of the kind generally known as long fibred paper or non-woven material and the term "tissue paper" is used herein to include all of these materials.
  • a wet laid tissue paper may, for example, be made on a conventional inclined wire machine used for making long-fibred tissue paper suitable for conversion into infusion bags.
  • the tissue paper may have any desired fibre composition.
  • the paper may be made entirely from cellulosic fibres.
  • the paper may comprise a mixture of cellulosic fibres and synthetic plastics material which may be in the form of plastics, e.g. polypropylene, fibres.
  • tissue paper that may be treated by the process according to the invention has a layer (upper or lower) of predominantly synthetic plastics fibres, e.g. polypropylene, and a layer (lower or upper) of predominantly cellulosic fibres.
  • the projections 2a of the embossing roller 2 produce compressed areas in the paper which in the finished product reflect and/or transmit light differently from the remainder of the paper so as to achieve a patterned effect.
  • any desired patterning effect of the paper P may be achieved, e.g. geometric patterns, trade marks, company logos or other markings or combinations thereof so as to achieve an aesthetically pleasing effect.
  • the patterning produced by the embossing process is enhanced by the controlled application of an additive, e.g.
  • a synthetic plastics material such as polypropylene
  • a molten state to the compressed areas so as to fuse together the bulk web within these regions thereby enhancing the patterned effect.
  • This is achieved by a reduction in light scattering within the fibres of the web by the continuum of additives such as polypropylene surrounding the fibres and thereby enhancing the transmission of light.
  • a major advantage is that the strength of the paper within the compressed regions is enhanced by the additive.
  • the additive may be a clear or colourless material or, alternatively, it may be coloured to alter the light transmission and/or reflection characteristics of the compressed regions thereby further enhancing the patterned effect.
  • the colouring may be achieved by the use of dyes which may be encapsulated in known manner for physiological acceptability. Alternatively, colouring may be achieved by the use of fine particulate material or dust obtained from the infusion material, e.g. tea dust.
  • the molten additive is applied to the embossing roller 2 by a heated transfer roller 3 in rolling contact with the embossing roller 2 and a coating roller 4 which is partially immersed in a heated bath 5 of molten additive.
  • a doctor blade 6 in contact with the coating roller 4 ensures that a uniform layer of additive is picked up by the roller 4 and transferred via the transfer roller 3 to the projections of the embossing roller 2.
  • thermoplastic polyolefin granules of a thermoplastic polyolefin (hereafter referred to as hot melt) are melted in the metal reservoir using a hot plate located beneath the reservoir heated to 200°C.
  • the transfer rollers (3 and 4) are heated to approximately 120°C by small cartridge heaters mounted in their core.
  • the transfer rollers are set in motion while the doctor blade 6 is adjusted to provide an even coating of hot melt on the roller surfaces.
  • the coating roller 3 then transfers to the protrusions of the embossing roller which is heated to 120°C.
  • Sample paper from a coil is fed between the embossing roller and the lower roller at a speed of approximately 10 metres/min with a force of approximately 30N/mm being applied between them. It is observed that the hot melt from the protrusions of the embossing roller is impregnated into the paper where it rapidly solidifies.
  • the hot melt dose (coat application gsm) appears high it applies to the patterned areas which occupy a small proportion of the bulk area.
  • the patterning technique has been applied to paper in the final stage of manufacture. It will be appreciated that finished paper may be treated in the same way in which case the paper P will be supplied to the roller set 1, 2 from a reel or coil which may be prepared in dimensions suitable for use on the subsequent conversion machine for converting the tissue paper into the bag product.
  • a heated embossing die in the form of a disc 11 with equispaced image recesses 12 (each consisting of the word TEA) engraved onto its periphery is pressed against a plain roll 13 whilst tissue paper 14 from a reel is fed into the nip 15.
  • a threaded collar nut 16 locates the die which also facilitates convenient die pattern exchange.
  • the embossed paper 17 is then fed to folding 18, tea dosing 19, sealing 20 and cutting 21 stages of a
  • SUBSTITUTE SHEET standard tea bag conversion machine for example a single lane TEEPACK CONSTANTA machine for cellulosic paper or a multi-lane SIG heat seal conversion machine for heat sealable paper.
  • the embossing die 11 is pressed with a force of 10-50N/mm against the plain roll 13 whilst the tissue paper 14 is fed to the nip 15 to provide a transparent strip 22 in the tissue paper containing opaque imprints 23 of the engraved images 12 registered on the final product bag 26.
  • the embossing rolls 13, 24 are electrically heated to a temperature of 180°C by cartridge elements 25 mounted in their core, whilst the embossing die 11 is fixed to the roll 24 in heat exchanging relationship therewith by the threaded collar 16.
  • tissue paper comprising solely of long cellulosic wood fibres together with wet strength agents e.g. kymene (Hercules Chemicals Ltd) and sodium carboxy-methyl-cellulose, could be embossed to provide an adequate embossed transparent stripe interrupted by the discrete images. Similar results were achieved for tissue papers containing thermoplastics in their construction.
  • FIG. 3 illustrates the apparatus of Fig. 2 incorporating a device as shown in Fig. 1 with reference numerals increased by 100 for similar parts.
  • parts corresponding to those of Fig. 2 are given reference numerals increased by 200 and are not further described.
  • a thin strip 230 40 ⁇ m thick x 3mm wide of thermoplastic material e.g. polyamide is fed from a reel 231 into the nip 215 beneath the tissue paper 214 where it is laminated into the tissue paper by the action of the heated embossing die 211.
  • the invention is concerned broadly with changing the appearance of tissue paper products, particularly but not exclusively tea bags, by a pressing technique which has been referred to as localised calendering or embossing, these terms being used synonymously to mean a pressing operation resulting in deformation of the paper profile and a consequent change in the optical properties of the compressed area or areas.
  • embossing is a continuous strip extending lengthwise of a tea bag and having greater transparency than the remainder of the bag. Such a strip enables closer visual inspection of the tea bag contents than has hitherto been possible.
  • the strip may of course be replaced by discontinuous areas or a single embossed area serving the same purpose or intended merely as pattern or ornament.
  • the embossing or localised calendering may produce its useful and/or decorative effect by using an embossing die in which significant parts, such as letters, of the final pattern are provided by projections or recesses in the die with the background against which such significant parts are viewed being provided by recesses or projections respectively.
  • the embossing die of Fig. 3 produces a continuous stripe by localised calendering and the TEA characters, which are seen in the product against the background of this relatively transparent stripe, are produced by the recesses 22 and remain of the same opacity as the remainder of the paper.
  • embossing may be carried out simultaneously on a plurality of paper strips derived from a common paper web, for example in the multi-lane SIG machine mentioned above.

Abstract

In a process for patterning tissue paper, e.g. for tea bags, a continuous strip of paper is embossed in the course of conversion of the strip into tissue paper products. Apparatus for converting the tissue paper into patterned product, has embossing means for embossing the strip in the course of such conversion. The invention further provides a process and apparatus for patterning tissue paper comprising subjecting the paper to the action of a heated embossing roller coated with a liquid adapted to enhance the patterned effect obtained by the embossing operation and/or the strength of the paper in the embossed area.

Description

IMPROVEMENTS TO THE PATTERNING OF TISSUE PAPER
This patent relates to the patterning of tissue paper which term is used herein to represent wet or dry laid paper having a basis weight between 6 and 50 g/m2 preferably between 10 and 26g/m2 and used for example as filtration bags used for the infusion of products such as tea or coffee.
There exists within the tea and coffee processing industries considerable interest in providing brand identification upon product bags for security and aesthetic appeal. This can take the form for example of patterning or discrete logo images introduced into the tissue paper at the production stage.
Commercial techniques in the past have centred upon water jet technology, a process whereby fibre distribution is disrupted at the papermaking formation stage to create regions of high and low fibre density which when viewed against the darker tea or coffee bag content provide a pattern by optical contrast.
However, it is recognised by those skilled in the art that the subsequent regions of low fibre density result in significant reductions in paper strength and moreover give rise to the loss of ingredient particles due to the occurrence of voids within these regions.
It is well known within the paper industry that the combined action of heat and pressure on a uniform tissue paper web results in a compaction of the fibres and a reduction in thickness.
This process commonly referred to as hot calendering also affords improved surface smoothness and moreover a reduction in opacity, and is most conveniently achieved by passing the tissue paper through the nip of hot rolls.
These properties as illustrated in Table 1 are achievable for tissue papers constructed from predominantly cellulosic fibres as well as mixtures of cellulosic, synthetic and thermoplastic fibre compositions.
Figure imgf000004_0001
TABLE 1: HOT CALENDERED TISSUE PAPERS
The given optical transmission values were obtained by a parallel beam of light from a first light source transmitted perpendicularly through the sample and recorded by a photocell whilst optical surface scatter was determined by the proportion of light from a second light source reflected back to a photocell placed close to a second light source and inclined at an angle of 45° to the paper surface.
The hot calendering was conducted on a commercial two plain steel roll stack over the full width of the paper at the given temperature with the nip pressure exerted by hydraulic rams.
A further advancement of the technique has been realised by the paper industry whereby the pressure rolls' smooth continuous surfaces are replaced by surfaces incorporating castellations or impressions which to all intents and purposes provide a localised calendering on discrete areas of the paper as it progresses through the nip.
Such a process is commonly referred to as embossing which term is used herein to refer to any localised calendering technique resulting in a profile in the thickness of paper in the longitudinal or transverse direction of the paper between the affected areas. It is also recognised that the application of heat during the embossing process improves fibre compaction giving rise to the terminology "hot embossing". Experiments conducted with a commercial hot embossing unit further demonstrated that the hot calendering physical changes exemplified in Table 1 could be duplicated within the embossed regions as illustrated in Table 2. In these examples, the emboss consisted of a diamond shaped lined structure occupying 32% of total surface area.
Figure imgf000005_0001
TABLE 2: HOT EMBOSSED TISSUE PAPERS
Enhanced optical transmission coupled with reduced optical backscatter resulted on visual inspection in a high degree of contrast between the embossed region and remaining bulk areas when viewed against a dark background such as tea or coffee.
Whilst the optical properties afford adequate contrast for pattern definition, the described processes unfortunately result in significant reductions in strength properties of the tissue as demonstrated also in Tables 1 and 2. However, depending upon the basis weight or substance of the tissue paper and the product into which the paper is to be converted, the reduction in strength may be acceptable.
According to a first aspect of the present invention there is provided a process for patterning tissue paper as herein defined by embossing a continuous strip of paper characterised in that embossing is carried out in the course of conversion of the strip into tissue paper products. According to a second aspect of the present invention there is provided apparatus for converting tissue paper into patterned product, comprising means for converting a continuous strip into said product, characterised in that embossing means is provided for embossing the strip in the course of such conversion.
According to a third aspect of the present invention there is provided a process for patterning tissue paper as herein defined comprising subjecting the paper to the action of a heated embossing roller coated with a liquid adapted to enhance the patterned effect obtained by the embossing operation and/or the strength of the paper in the embossed area.
According to a fourth aspect of the present invention there is provided apparatus for patterning tissue paper as herein defined, comprising an embossing roller defining a nip with a coacting pressure roller, means for heating the embossing roller, means for guiding the paper into the nip, and means for coating the embossing roller with a liquid adapted to enhance the patterned effect obtained by the embossing operation.
The invention will now be further described by way of example only with reference to the accompanying drawings, in which :-
Fig. 1 is a schematic view of one embodiment of apparatus in accordance with the invention;
Fig. 2 is a schematic view of one embodiment of tea bag conversion machine illustrating the invention;
Fig. 3 is a schematic view of a second embodiment of tea bag conversion machine illustrating the invention, and
Fig. 4 is a further embodiment of the invention incorporated in a schematically illustrated tea bag conversion machine.
Referring now to Fig. 1 of the drawings, a papermaking machine is indicated diagrammatically at PM and produces paper P which is guided by suitable guide means (not shown) through the nip of a roller pair in which the lower roller 1 provides a counter-surface for an upper, heated embossing roller 2 having a profiled surface including raised portions or projections indicated diagrammatically at 2a. The papermaking machine produces tissue paper having a basis weight of 6 to 50 g/m2 preferably 10-26 g/m2. The papermaking machine may use a wet or dry laying process to produce tissue paper of the kind generally known as long fibred paper or non-woven material and the term "tissue paper" is used herein to include all of these materials.
A wet laid tissue paper may, for example, be made on a conventional inclined wire machine used for making long-fibred tissue paper suitable for conversion into infusion bags.
The tissue paper may have any desired fibre composition. For example, the paper may be made entirely from cellulosic fibres. Alternatively, the paper may comprise a mixture of cellulosic fibres and synthetic plastics material which may be in the form of plastics, e.g. polypropylene, fibres. One example of tissue paper that may be treated by the process according to the invention has a layer (upper or lower) of predominantly synthetic plastics fibres, e.g. polypropylene, and a layer (lower or upper) of predominantly cellulosic fibres.
As the paper P passes through the nip of the roller pair 1, 2, the projections 2a of the embossing roller 2 produce compressed areas in the paper which in the finished product reflect and/or transmit light differently from the remainder of the paper so as to achieve a patterned effect. By changing the pattern of projections on the embossing roller 2 any desired patterning effect of the paper P may be achieved, e.g. geometric patterns, trade marks, company logos or other markings or combinations thereof so as to achieve an aesthetically pleasing effect. The patterning produced by the embossing process is enhanced by the controlled application of an additive, e.g. a synthetic plastics material such as polypropylene, in a molten state to the compressed areas so as to fuse together the bulk web within these regions thereby enhancing the patterned effect. This is achieved by a reduction in light scattering within the fibres of the web by the continuum of additives such as polypropylene surrounding the fibres and thereby enhancing the transmission of light. A major advantage is that the strength of the paper within the compressed regions is enhanced by the additive.
The additive may be a clear or colourless material or, alternatively, it may be coloured to alter the light transmission and/or reflection characteristics of the compressed regions thereby further enhancing the patterned effect. The colouring may be achieved by the use of dyes which may be encapsulated in known manner for physiological acceptability. Alternatively, colouring may be achieved by the use of fine particulate material or dust obtained from the infusion material, e.g. tea dust.
The molten additive, with or without colouring, is applied to the embossing roller 2 by a heated transfer roller 3 in rolling contact with the embossing roller 2 and a coating roller 4 which is partially immersed in a heated bath 5 of molten additive. A doctor blade 6 in contact with the coating roller 4 ensures that a uniform layer of additive is picked up by the roller 4 and transferred via the transfer roller 3 to the projections of the embossing roller 2. These projections deliver the additive in the course of creating the locally compressed areas in the paper.
By way of an example, granules of a thermoplastic polyolefin (hereafter referred to as hot melt) are melted in the metal reservoir using a hot plate located beneath the reservoir heated to 200°C. At the same time, the transfer rollers (3 and 4) are heated to approximately 120°C by small cartridge heaters mounted in their core. The transfer rollers are set in motion while the doctor blade 6 is adjusted to provide an even coating of hot melt on the roller surfaces. The coating roller 3 then transfers to the protrusions of the embossing roller which is heated to 120°C. Sample paper from a coil is fed between the embossing roller and the lower roller at a speed of approximately 10 metres/min with a force of approximately 30N/mm being applied between them. It is observed that the hot melt from the protrusions of the embossing roller is impregnated into the paper where it rapidly solidifies.
Fine tea dust added to the reservoir of hot melt as a suspension and to a concentration of 20% by weight, results in a coloured embossing pattern being impregnated into paper by encapsulating the dust into the thermoplastics material as it solidifies.
A further advantage has been realised by the significantly improved paper strength characteristics within the coated and compressed regions as demonstrated in Table 3.
Figure imgf000009_0001
TABLE 3: HOT COATED TISSUE PAPERS
Although the hot melt dose (coat application gsm) appears high it applies to the patterned areas which occupy a small proportion of the bulk area.
In the illustrated examples the patterning technique has been applied to paper in the final stage of manufacture. It will be appreciated that finished paper may be treated in the same way in which case the paper P will be supplied to the roller set 1, 2 from a reel or coil which may be prepared in dimensions suitable for use on the subsequent conversion machine for converting the tissue paper into the bag product.
It has been found that very accurate registration of discrete pattern images can be achieved by scaling down the embossing machinery to a size such that it can conveniently be integrated with the bag conversion machinery and which enables the embossing rolls to be synchronised with the sealing and slitting mechanism of such machinery.
In the apparatus of Fig. 2 a heated embossing die in the form of a disc 11 with equispaced image recesses 12 (each consisting of the word TEA) engraved onto its periphery is pressed against a plain roll 13 whilst tissue paper 14 from a reel is fed into the nip 15. A threaded collar nut 16 locates the die which also facilitates convenient die pattern exchange. The embossed paper 17 is then fed to folding 18, tea dosing 19, sealing 20 and cutting 21 stages of a
SUBSTITUTE SHEET standard tea bag conversion machine (for example a single lane TEEPACK CONSTANTA machine for cellulosic paper or a multi-lane SIG heat seal conversion machine for heat sealable paper). In use, the embossing die 11 is pressed with a force of 10-50N/mm against the plain roll 13 whilst the tissue paper 14 is fed to the nip 15 to provide a transparent strip 22 in the tissue paper containing opaque imprints 23 of the engraved images 12 registered on the final product bag 26. The embossing rolls 13, 24 are electrically heated to a temperature of 180°C by cartridge elements 25 mounted in their core, whilst the embossing die 11 is fixed to the roll 24 in heat exchanging relationship therewith by the threaded collar 16.
It was found that in use of the apparatus of Fig. 2 the embossed image remained in a constant position on the tea bags manufactured. In a further experiment, a similar sample of paper was embossed using the same embossing unit but subsequently reeled to normal tension prior to converting separately into tea bags on the same tea bag machine. In this case the embossed image ran out of registration by 5mm after conversion of only 200 metres of paper. Bearing in mind that conversion paper lengths of 3000 metres are common, the requirement for precision registration of images is obviously of importance.
Surprisingly it was found that tissue paper comprising solely of long cellulosic wood fibres together with wet strength agents e.g. kymene (Hercules Chemicals Ltd) and sodium carboxy-methyl-cellulose, could be embossed to provide an adequate embossed transparent stripe interrupted by the discrete images. Similar results were achieved for tissue papers containing thermoplastics in their construction.
It was also found that paper strength characteristics in the machine direction was not reduced unduly by the embossing process since the transverse extent of the embossed pattern occupies only a small proportion of the total paper width.
Naturally a technique such as that described above by reference to Fig. 1 could be adapted to this paper processing on the conversion machine to enhance transparency and paper strength as shown in Table 3. Fig. 3 illustrates the apparatus of Fig. 2 incorporating a device as shown in Fig. 1 with reference numerals increased by 100 for similar parts. In a further embodiment illustrated schematically in Fig. 4, parts corresponding to those of Fig. 2 are given reference numerals increased by 200 and are not further described. A thin strip 230 40μm thick x 3mm wide of thermoplastic material e.g. polyamide is fed from a reel 231 into the nip 215 beneath the tissue paper 214 where it is laminated into the tissue paper by the action of the heated embossing die 211.
It was found that preferred results were obtained when the lower roll temperature was maintained at a temperature below the melting point of the thermoplastic strip (e.g. 60°C for polyamides) to facilitate release of the paper from the lower rolls. An impressively shiny transparent stripe together with an image emboss was achieved on the outside of the subsequently converted tea bags. It was also found that the strength of the laminated region was significantly greater than the remaining tissue paper as demonstrated in Table 4.
Figure imgf000011_0001
TABLE 4: HOT LAMINATED TISSUE PAPERS
By embossing the tissue paper in the course of conversion of a continuous strip into tea ba'gs or other paper products it is possible to avoid the registration problems that would inevitably occur as a result of stretching if embossing were carried out at an earlier stage, e.g. during paper manufacture or during subsequent reeling from machine rolls to coils of suitable width for use on standard conversion machines. As described above, such stretching causes a failure of registration of the embossed pattern with the final product. It will be appreciated that the invention is concerned broadly with changing the appearance of tissue paper products, particularly but not exclusively tea bags, by a pressing technique which has been referred to as localised calendering or embossing, these terms being used synonymously to mean a pressing operation resulting in deformation of the paper profile and a consequent change in the optical properties of the compressed area or areas. A simple example of such embossing is a continuous strip extending lengthwise of a tea bag and having greater transparency than the remainder of the bag. Such a strip enables closer visual inspection of the tea bag contents than has hitherto been possible. The strip may of course be replaced by discontinuous areas or a single embossed area serving the same purpose or intended merely as pattern or ornament. As described, the embossing or localised calendering may produce its useful and/or decorative effect by using an embossing die in which significant parts, such as letters, of the final pattern are provided by projections or recesses in the die with the background against which such significant parts are viewed being provided by recesses or projections respectively. For example, the embossing die of Fig. 3 produces a continuous stripe by localised calendering and the TEA characters, which are seen in the product against the background of this relatively transparent stripe, are produced by the recesses 22 and remain of the same opacity as the remainder of the paper.
Although the description has been confined to hot embossing it will be appreciated that similar effects may be achieved, possibly with application of greater pressure, alternative additions or embossing at ambient temperatures. Also, embossing may be carried out simultaneously on a plurality of paper strips derived from a common paper web, for example in the multi-lane SIG machine mentioned above.

Claims

CLAIMS:
1. A process for patterning tissue paper as herein defined by embossing a continuous strip of paper characterised in that embossing is carried out in the course of conversion of the strip into tissue paper products.
2. A process as claimed in claim 1, wherein the embossing is carried out simultaneously on a plurality of said strips derived from a common paper web.
3. A process as claimed in claim 2, wherein the embossing is effected by a pair of cooperating rollers.
4. A process as claimed in claim 3, wherein at least one of said rollers is heated.
5. A process as claimed in any one of the preceding claims, wherein the paper is made predominantly of cellulosic fibres.
6. A process as claimed in any one of the preceding claims, wherein a narrow band of thermoplastics material is applied to the or each paper strip in the embossing region so as to become laminated thereto by pressure and/or heat.
7. A process as claimed in any one of the preceding claims, wherein the paper is made at least partially of thermoplastics fibres.
8. A process as claimed in any one of claims 1 to 5, wherein a liquid adapted to enhance the strength and/or appearance of the embossed area of the paper is added to said area in the course of embossing.
9. A process as claimed in any one of claims 1 to 5, wherein the embossing produces a continuous strip or discrete areas which are relatively more transparent than the surrounding paper so as to permit improved inspection of the contents of the product, for example tea in a tea bag.
10. Apparatus for converting tissue paper into patterned product, comprising means for converting a continuous strip into said product, characterised in that embossing means is provided for embossing the strip in the course of such conversion.
11. Apparatus as claimed in claim 10, wherein means is provided for slitting a common web into a plurality of said strips and the embossing means is adapted to emboss said plurality of strips simultaneously.
12. Apparatus as claimed in claim 10 or 11, wherein means is provided for supplying to the embossing means a liquid adapted to enhance the strength and/or appearance of the embossed area of the paper.
13. A process for patterning tissue paper as herein defined comprising subjecting the paper to the action of a heated embossing roller coated with a liquid adapted to enhance the patterned effect obtained by the embossing operation and/or the strength of the paper in the embossed area.
14. A process as claimed in claim 13, wherein the paper comprises a first layer of predominantly synthetic plastics fibres and a second layer of predominantly cellulosic fibres.
15. A process as claimed in claim 13 or 14, wherein the liquid is transferred to the embossing roller by means of a heated transfer roller which receives the liquid from a molten source e.g. a roller rotating in a bath containing the liquid.
16. A process as claimed in any one of the preceding claims, wherein the liquid is a molten synthetic material, e.g. polypropylene.
17. A process as claimed in any one of the preceding claims, wherein colouring is added to the liquid to further enhance the patterned effect.
18. A process as claimed in claim 17, wherein the colouring is a dye.
19. A process as claimed in claim 17, wherein the colouring is provided by tea dust.
20. Apparatus for patterning tissue paper as herein defined, comprising an embossing roller defining a nip with a coacting pressure roller, means for heating the embossing roller, means for guiding the paper into the nip, and means for coating the embossing roller with a liquid adapted to enhance the patterned effect obtained by the embossing operation.
PCT/GB1993/001962 1992-09-16 1993-09-16 Improvements to the patterning of tissue paper WO1994006623A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AU48255/93A AU4825593A (en) 1992-09-16 1993-09-16 Improvements to the patterning of tissue paper
GB9505242A GB2286159B (en) 1992-09-16 1993-09-16 Improvements to the patterning of tissue paper filtration bags

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GB9219605.4 1992-09-16
GB929219605A GB9219605D0 (en) 1992-09-16 1992-09-16 A process and apparatus for patterning tissue paper
GB939302646A GB9302646D0 (en) 1993-02-10 1993-02-10 Improvements in or relating to the patterming of tissue paper
GB9302646.6 1993-02-10

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WO1994006623A1 true WO1994006623A1 (en) 1994-03-31

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US5549790A (en) * 1994-06-29 1996-08-27 The Procter & Gamble Company Multi-region paper structures having a transition region interconnecting relatively thinner regions disposed at different elevations, and apparatus and process for making the same
US5556509A (en) * 1994-06-29 1996-09-17 The Procter & Gamble Company Paper structures having at least three regions including a transition region interconnecting relatively thinner regions disposed at different elevations, and apparatus and process for making the same
US5580423A (en) * 1993-12-20 1996-12-03 The Procter & Gamble Company Wet pressed paper web and method of making the same
WO1997020107A1 (en) * 1995-11-30 1997-06-05 Fort James France Absorbent paper sheet marked with pattern simulating watermark, method and device for the marking thereof
US5837103A (en) * 1994-06-29 1998-11-17 The Procter & Gamble Company Web patterning apparatus comprising a felt layer and a photosensitive resin layer
US5855739A (en) * 1993-12-20 1999-01-05 The Procter & Gamble Co. Pressed paper web and method of making the same
US5861082A (en) * 1993-12-20 1999-01-19 The Procter & Gamble Company Wet pressed paper web and method of making the same
US5871887A (en) * 1994-06-29 1999-02-16 The Procter & Gamble Company Web patterning apparatus comprising a felt layer and a photosensitive resin layer
DE10110873A1 (en) * 2001-03-07 2002-09-19 Metsae Tissue Oyj Device for the production of at least two-layer products from tissue and / or tissue-like material
EP1362953A1 (en) * 2002-05-14 2003-11-19 Georgia-Pacific France Process for marking a paperweb, paperweb having a watermark pattern
US6913673B2 (en) 2001-12-19 2005-07-05 Kimberly-Clark Worldwide, Inc. Heated embossing and ply attachment
EP1696076A1 (en) * 2005-02-23 2006-08-30 J R Crompton Ltd. Beverage package
US7311800B2 (en) 2004-02-17 2007-12-25 The Procter & Gamble Company Deep-nested embossed paper products
US7314665B2 (en) 2003-09-29 2008-01-01 The Procter & Gamble Company Embossed multi-ply fibrous structure product and process for making same
US7374638B2 (en) 2003-09-29 2008-05-20 The Procter & Gamble Company High bulk strong absorbent single-ply tissue-towel paper product
US7413629B2 (en) 2004-05-21 2008-08-19 The Procter & Gamble Company Process for producing deep-nested embossed paper products
US7435313B2 (en) 2004-05-21 2008-10-14 The Procter & Gamble Company Process for producing deep-nested embossed paper products
US7435316B2 (en) 2005-06-08 2008-10-14 The Procter & Gamble Company Embossing process including discrete and linear embossing elements
US7524404B2 (en) 2005-06-08 2009-04-28 The Procter & Gamble Company Embossing process including discrete and linear embossing elements
US7785696B2 (en) 2005-06-08 2010-08-31 The Procter & Gamble Company Embossed product including discrete and linear embossments
USD630441S1 (en) 2007-05-02 2011-01-11 The Procter & Gamble Company Paper product
US8152959B2 (en) 2006-05-25 2012-04-10 The Procter & Gamble Company Embossed multi-ply fibrous structure product
CN109866261A (en) * 2019-03-18 2019-06-11 世源科技(芜湖)新材料有限公司 A kind of process line for high impermeable medical equipment tray paper

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US5846379A (en) * 1993-12-20 1998-12-08 The Procter & Gamble Company Wet pressed paper web and method of making the same
US5904811A (en) * 1993-12-20 1999-05-18 The Procter & Gamble Company Wet pressed paper web and method of making the same
US5580423A (en) * 1993-12-20 1996-12-03 The Procter & Gamble Company Wet pressed paper web and method of making the same
US5861082A (en) * 1993-12-20 1999-01-19 The Procter & Gamble Company Wet pressed paper web and method of making the same
US5855739A (en) * 1993-12-20 1999-01-05 The Procter & Gamble Co. Pressed paper web and method of making the same
US5637194A (en) * 1993-12-20 1997-06-10 The Procter & Gamble Company Wet pressed paper web and method of making the same
US5871887A (en) * 1994-06-29 1999-02-16 The Procter & Gamble Company Web patterning apparatus comprising a felt layer and a photosensitive resin layer
US5837103A (en) * 1994-06-29 1998-11-17 The Procter & Gamble Company Web patterning apparatus comprising a felt layer and a photosensitive resin layer
US5709775A (en) * 1994-06-29 1998-01-20 The Procter & Gamble Company Paper structures having at least three regions including a transition region interconnecting relatively thinner regions disposed at different elevations, and apparatus and process for making the same
US5609725A (en) * 1994-06-29 1997-03-11 The Procter & Gamble Company Multi-region paper structures having a transition region interconnecting relatively thinner regions disposed at different elevations, and apparatus and process for making the same
US5549790A (en) * 1994-06-29 1996-08-27 The Procter & Gamble Company Multi-region paper structures having a transition region interconnecting relatively thinner regions disposed at different elevations, and apparatus and process for making the same
US5556509A (en) * 1994-06-29 1996-09-17 The Procter & Gamble Company Paper structures having at least three regions including a transition region interconnecting relatively thinner regions disposed at different elevations, and apparatus and process for making the same
US5776312A (en) * 1994-06-29 1998-07-07 The Procter & Gamble Company Paper structures having at least three regions including a transition region interconnecting relatively thinner regions disposed at different elevations, and apparatus and process for making the same
WO1997020107A1 (en) * 1995-11-30 1997-06-05 Fort James France Absorbent paper sheet marked with pattern simulating watermark, method and device for the marking thereof
DE10110873A1 (en) * 2001-03-07 2002-09-19 Metsae Tissue Oyj Device for the production of at least two-layer products from tissue and / or tissue-like material
US6913673B2 (en) 2001-12-19 2005-07-05 Kimberly-Clark Worldwide, Inc. Heated embossing and ply attachment
EP1362953A1 (en) * 2002-05-14 2003-11-19 Georgia-Pacific France Process for marking a paperweb, paperweb having a watermark pattern
US6824647B2 (en) * 2002-05-14 2004-11-30 Georgia-Pacific France Method for marking a sheet of paper and sheet with a watermark
USRE43095E1 (en) * 2003-09-29 2012-01-10 The Procter & Gamble Company Embossed multi-ply fibrous structure product and process for making same
US7314665B2 (en) 2003-09-29 2008-01-01 The Procter & Gamble Company Embossed multi-ply fibrous structure product and process for making same
US7314664B2 (en) 2003-09-29 2008-01-01 The Procter & Gamble Company Embossed multi-ply fibrous structure product and process for making same
US7314663B2 (en) 2003-09-29 2008-01-01 The Procter + Gamble Company Embossed multi-ply fibrous structure product and process for making same
US7374638B2 (en) 2003-09-29 2008-05-20 The Procter & Gamble Company High bulk strong absorbent single-ply tissue-towel paper product
US7311800B2 (en) 2004-02-17 2007-12-25 The Procter & Gamble Company Deep-nested embossed paper products
US7413629B2 (en) 2004-05-21 2008-08-19 The Procter & Gamble Company Process for producing deep-nested embossed paper products
US7435313B2 (en) 2004-05-21 2008-10-14 The Procter & Gamble Company Process for producing deep-nested embossed paper products
EP1696076A1 (en) * 2005-02-23 2006-08-30 J R Crompton Ltd. Beverage package
US7524404B2 (en) 2005-06-08 2009-04-28 The Procter & Gamble Company Embossing process including discrete and linear embossing elements
US7785696B2 (en) 2005-06-08 2010-08-31 The Procter & Gamble Company Embossed product including discrete and linear embossments
US7887676B2 (en) 2005-06-08 2011-02-15 The Procter & Gamble Company Embossing process including discrete and linear embossing elements
US7918972B2 (en) 2005-06-08 2011-04-05 The Procter & Gamble Company Embossing process including discrete and linear embossing elements
US8007640B2 (en) 2005-06-08 2011-08-30 The Procter & Gamble Company Embossing process including discrete and linear embossing elements
US8083893B2 (en) 2005-06-08 2011-12-27 The Procter & Gamble Company Embossing process including discrete and linear embossing elements
US7435316B2 (en) 2005-06-08 2008-10-14 The Procter & Gamble Company Embossing process including discrete and linear embossing elements
US8152959B2 (en) 2006-05-25 2012-04-10 The Procter & Gamble Company Embossed multi-ply fibrous structure product
USD630441S1 (en) 2007-05-02 2011-01-11 The Procter & Gamble Company Paper product
CN109866261A (en) * 2019-03-18 2019-06-11 世源科技(芜湖)新材料有限公司 A kind of process line for high impermeable medical equipment tray paper

Also Published As

Publication number Publication date
GB2286159A (en) 1995-08-09
AU4825593A (en) 1994-04-12
GB9505242D0 (en) 1995-05-10
GB2286159B (en) 1997-03-19

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