WO2010021572A1

WO2010021572A1 - A tissue paper/nonwoven laminate product

Info

Publication number: WO2010021572A1
Application number: PCT/SE2008/000473
Authority: WO
Inventors: Daniel Solberg; Hannu Ahoniemi; Hans Wallenius; Sara LUNDSTRÖM; Urban Widlund
Original assignee: SCA Hygiene Products AB
Current assignee: Essity Hygiene and Health AB
Priority date: 2008-08-19
Filing date: 2008-08-19
Publication date: 2010-02-25
Anticipated expiration: 2011-02-19

Abstract

A tissue paper/nonwoven laminate comprising outer plies (12, 13) of tissue paper and an inner ply (11) of nonwoven material. The outer plies (12, 13) of tissue paper each have a basis weight between 12 and 20 g/m² and the inner ply (11) is a hydroentangled nonwoven fabric having a basis weight between 40 and 80 g/m² comprising between 30 and 90% by weight pulp fibers and between 10 and 70% by weight manmade fibers or filaments and/or natural fibers. The hydroentangled nonwoven fabric has a visible three-dimensional striped pattern of alternating ridges and valleys, caused by hydroentanglement water jets, wherein the distance between adjacent valleys is between 0.3 and 2 mm and the striped pattern is visible from the outside of the laminate through the tissue plies.

Description

A TISSUE PAPER/NONWOVEN LAMINATE PRODUCT

TECHNICAL FIELD The present invention refers to a tissue paper / nonwoven laminate comprising outer plies of tissue paper and an inner ply of nonwoven material. The laminate is especially adapted for products like premium table napkins, premium handwiping towels, facial tissue and the like.

BACKGROUND OF THE INVENTION

Premium table napkins are today usually made of textiles. These textile napkins are woven materials mainly consisting of cotton or linen. Airlaid webs of wood pulp fibers bonded by a bonding agent, for example latex, and which have a more textile feeling than wetlaid tissue, have also been used as table napkins in a quality range between textile napkins and paper napkins. However airlaid napkins sometimes tend to have a rather rough surface, which can feel somewhat synthetic or "rubbery" due to the latex addition. Airlaid napkins also suffer from an acid odour originating from the latex binder.

Laminates of tissue paper and nonwoven materials are further known in different types of applications, especially when higji strength is required, for example in wipes.

US-A-6,060,149 discloses a laminated wiping article comprising an apertured dry creped tissue layer and a nonwoven layer comprising synthetic fibers. The tissue layer is more extensible in a wetted state than the nonwoven layer. Selected portions of the tissue layer are adhesively bonded to the nonwoven layer.

EP-A-O 097 036 discloses a strong absorbent industrial wiper comprising a reinforcing centre ply of nonwoven, and outer plies of absorbent tissue. At least one of the outer plies of absorbent tissue alone has a basis weight between 30 and 90 g/m².

GB-A-1 242 572 discloses a laminated material comprising a thermoplastics-bonded nonwoven layer and on each face thereof a layer of soft tissue paper, which has been bonded to the nonwoven layer by heating the thermoplastics material in said layer. The basis weight of each tissue layer is between 20 and 50 g/m².

US-A-3,958,055 discloses a tissue/nonwoven laminate comprising outer plies of creped tissue and an inner ply of an isotropic, reinforcing textile length fiber web, such as a carded web. The plies are bonded together by adhesive.

DE-A-10 2004 024 551 discloses a tissue/airlaid laminate useful as table napkin, table cloth and the like. The laminate comprises at least one tissue layer having a basis weight between 10 and 35 g/m² and a specified dry strength, and an airlaid layer comprising thermoplastic binder fibers.

SUMMARY OF THE INVENTION An object of the present invention is to provide a tissue paper / nonwoven laminate with a sensory and aesthetic perception close to textiles. This has according to the invention been achieved by a laminate comprising outer plies of tissue paper and an inner ply of nonwoven material, wherein said outer plies of tissue paper each have a basis weight between 12 and 20 g/m² and the inner ply is a hydroentangled nonwoven fabric having a basis weight between 40 and 80 g/m² comprising between 30 and 90% by weight pulp fibers and between 10 and 70% by weight manmade fibers or filaments and/or natural fibers, wherein the hydroentangled nonwoven fabric has a visible three-dimensional striped pattern of alternating ridges and valleys, caused by hydroentanglement water jets, wherein the distance between adjacent valleys is between 0.3 and 2 mm and the striped pattern is visible from the outside of the laminate through the tissue plies.

In one embodiment one or both outer plies of tissue paper has a basis weight between 13 and 18 g/m², preferably between 14 and 17 g/m².

In a further embodiment the inner ply of hydroentangled nonwoven fabric has a basis weight between 50 and 70 g/m².

In a still further embodiment the inner ply of hydroentangled nonwoven fabric comprises at least 40% by weight pulp fibers, preferably at least 50% by weight pulp fibers and the rest manmade fibers and/or natural fibers. In one aspect of the invention said manmade or natural fibers have a fiber length of at least 3 mm.

In further embodiment at least one of the plies of tissue paper is a through-air-dried tissue. In a further aspect both outer plies of tissue paper are through-air dried tissue.

In a still further embodiment one or both outer plies of tissue paper is/are a dry creped tissue.

In one aspect of the invention at least one of the outer plies of tissue paper, preferably both outer plies of tissue paper, is a multilayered tissue comprising at least one layer with at least 50% by weight hardwood fibers and at least one layer with at least 50% by weight softwood fibers.

In further embodiment the hydroentangled nonwoven fabric is wetlaid.

In one aspect of the invention the layers of tissue paper are adhesively bonded to the inner ply of hydroentangled nonwoven in a bonding pattern having a bonded area of between 2 and 15% and preferably between 5 and 10% of the surface area of the laminate. The bonding density is in a further aspect 20 and 100 bonding sites per cm².

In a further embodiment at least one ply of tissue paper is embossed. In a still further embodiment said embossing pattern comprising a plurality of embossing points configured so as to create a diagonal striped pattern extending obliquely across the striped pattern of the inner hydroentangled nonwoven web. This embossing pattern provides a textile-like aesthetic impression as well as an enhanced tactile feeling of the laminate.

DEFINITIONS

Tissue paper

A tissue paper is defined as a soft absorbent paper having a basis weight below 65 g/m² and typically between 10-and 50 g/m². The tissue paper plies in the laminate according to the invention each have a basis weight between 12 and 20 g/m². The density of tissue paper is typically below 0.60 g/cm³, preferably below 0.30 g/cm³ and more preferably between 0.06 and 0.20 g/cm³.

Tissue paper can be manufactured and dried in different ways. A method which is commonly used for drying tissue paper is so called yankee drying. At yankee drying the moist paper web is pressed against a steam-heated yankee cylinder, which can have a very large diameter. The paper web is usually creped against the yankee cylinder. This method may also be referred to as dry creping.

Another drying method is so called through-air-drying (TAD). In this method the paper is dried by means of hot air blown through the moist paper web, often without a preceding wet pressing. In connection with the TAD drying the patterned structure of the drying fabric is transferred to the paper web. This structure is essentially maintained also in wet condition of the paper, since it has been imparted to the wet paper web. The present invention refers to all types of tissue paper. The tissue paper may be creped or non-creped. The creping may take place in wet or dry condition. It may further be foreshortened by any other methods, such as so called rush transfer between wires.

The fibers contained in the tissue paper are mainly pulp fibers from chemical pulp, mechanical pulp, thermo mechanical pulp, chemo mechanical pulp and/or chemo thermo mechanical pulp (CTMP). The fibers may also be recycled fibers. The tissue paper may also contain other types of fibers enhancing e.g. strength, absorption or softness of the paper. These fibers may be made from regenerated cellulose or synthetic material such as polyolefins, polyesters, polyamides etc.

The tissue paper coming out from the tissue paper machine may comprise one or more layers. In the case of more than one layer this is accomplished either in a multi-layered headbox, by forming a new layer on top of an already formed layer or by couching together already formed layers. These layers can not or only with considerable difficulty be separated from each other and are joined mainly by hydrogen bonds. The different layers may be identical or may have different properties regarding for example fibre composition and chemical composition.

Ply

A paper comes out from the paper machine as a single-ply paper sheet, which later in the converting process can be combined with other plies by a lamination process, such as gluing and or embossing, to form a multi-ply material. The same applies to a nonwoven material. A single ply may comprise one, two or more layers, for example obtained by using a multi-layered headbox, by forming the web layers on top of each other in a sequential mode, or by forming each layer in a separate forming unit before couching the layers together in the paper machine while still in a wet condition.

Hydroentangled nonwoven fabric

Hydroentangling or spunlacing is a technique introduced during the 1970'ies, see e g CA patent no. 841 938. The method involves forming a fibrous web, which is either drylaid or wetlaid, after which the fibres are entangled by means of very fine water jets under high pressure. Several rows of water jets are directed against the fibre web which is supported by a movable fabric or perforated drum. The hydroentangled fibre web is then dried. The fibres that are used in the material can be synthetic or regenerated staple fibres, e.g. polyester, polyamide, polypropylene, rayon or the like, pulp fibres or mixtures of pulp fibres and staple fibres. The fibres or part of the fibers may also be in the form of continuous filaments, such as spunlaid or meltblown filaments. Combinations of continuous filaments with pulp fibers and/or staple fibers may further be used.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic cross section through an embodiment of a tissue paper / nonwoven laminate according to the invention.

Figure 2 is a schematic plan view of another embodiment of a tissue paper / nonwoven laminate according to the invention.

Figure 3 is a photo of a laminate according to the invention..

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The laminate 10 according to the present invention comprises three plies, an inner ply 11 of nonwoven material and two outer plies 12 and 13 of tissue paper, which are bonded together by adhesive. In other embodiments more than three plies may be present in the laminate, for example two or more inner plies.

The inner ply 11 is a hydroentangled nonwoven fabric comprising a mixture of pulp fibers and manmade fibers and/or natural fibers. The manmade fibers may be staple fibers and/or continuous filaments, such as spunbond or meltblown fibers. The content of pulp fibers in the hydroentangled nonwoven ply 11 should be between 30 and 90% by weight, while 10 to 70% by weight are manmade fibers or natural fibers. Manmade fibers may be made from synthetic polyolefins, such as polyethylene and polypropylene, polyamides, polyesters and polylactides. Manmade fibers may also be in the form of regenerated cellulose, such as viscose, rayon, lyocell and the like. As an alternative to manmade staple fibers, natural fibers with a relatively long fiber length can be used, e g at least 3 and preferably at least 6 mm, such as seed hair fibers, e g cotton, kapok and milkweed; leaf fibers e g sisal, abaca, pineapple, New Zealand hamp, or bast fibers, e g. flax, hemp, ramie, jute, kenaf.

The hydroentangled nonwoven may also comprise a mixture of pulp fibers, continuous filaments and staple manmade fibers or natural fibers. Preferably the staple fibers and natural fibers have a length of at least 3 mm and more preferably at least 6 mm. The pulp fibers may have a shorter length, even below 1 mm.

When producing a hydroentangled nonwoven fabric a fibrous web is formed either by wet forming (including foam forming) or dry forming. In wet forming the pulp and staple fibres are slurried in conventional way, either mixed together or first separately slurried and then mixed, and conventional papermaking additives such as wet and/or dry strength agents, retention aids, dispersing agents, may be added, to produce a well mixed slurry of pulp and staple fibres in water. After dewatering the fibrous web is hydroentangled by means of very fine water jets under high pressure. Several rows of water jets are directed against the fibre web which is supported on a forming fabric. When the jets of high-pressure water impinge on the fibres they will mix and entangle with each other. The fibrous web may be entangled from ones side or preferably from both sides. The entangling water is drained off through the forming fabric and the entangled web is dried in a drying station.

The hydroentangling station can include several transverse bars with rows of nozzles from which very fine water jets under very high pressure are directed against the fibrous web to provide an entangling of the fibres. The water jet pressure can then be adapted to have a certain pressure profile with different pressures in the different rows of nozzles.

Alternatively, the fibrous web can before hydroentangling be transferred to a second entangling fabric. In this case the web can also prior to the transfer be hydroentangled by a first hydroentangling station with one or more bars with rows of nozzles. In dry forming a fibrous web is formed by dry laying the fibres. The dry formed fibrous web is hydroentangled in a similar way as a wet formed web.

The hydroentangling water jets will create a visible striped pattern in the entangled web comprising a plurality of valleys 14 and ridges 15. The depth of the valleys 14, i.e. the distance from the top of a ridge to the bottom of a valley, is usually of the magnitude tenth of millimetres, i.e. between 0.1 and 0.9 mm. The distance between adjacent valleys 14 correspond to the distance between water jets in the entangling nozzles and is between 0.3 and 2 mm. This striped pattern resembles warp threads and will give a textile appearance to the hydroentangled nonwoven material.

It may in some cases be advantageous to have a slightly uneven distance, d, between the row of valleys 14 (entangling stripes), since this will reinforce the textile feel and warp thread resemblance. Such an uneven distance, d, between the entangling stripes can be achieved by having different spacing between the entangling nozzles or simply by having entangling nozzles that are a bit worn.

The hydroentangled nonwoven web has a basis weight between 40 and 80 g/m², preferably between 50 and 70 g/m². In a case where the inner ply comprises two or more plies of hydroentangled nonwoven material, the sum of the basis weights of these plies should be within the stated limits.

The density of the hydroentangled web will normally vary in cross machine direction and is higher in the valleys than on the ridges.

The hydroentangled nonwoven web or at least a part of the fibres used in said web may be coloured fibres.

The tissue plies 12 and 13 should be relatively thin with a basis weight each of between 12 and 20 g/m², preferably between 13 and 18 g/m² and more preferably between 14 and 16 g/m². This will ensure that the tissue plies 12 and 13 are sufficiently transparent to allow the striped pattern of the inner nonwoven ply 11 to be visible through the tissue plies. The tissue plies may be coloured, or at least a part of the fibres contained therein may be coloured. The tissue plies 12 and 13 can be made of an optional tissue paper such as conventional dry creped tissue or through-air-dried (TAD) tissue, the latter usually being softer and bulkier than dry creped tissue.

The sensory and aesthetic impression of the tissue plies can be further improved when producing them as a multiply tissue material. Each tissue ply may comprise two or more layers, wherein at least an outer layer comprises a fiber mixture with properties benefical for good sensory impression and the back layer (facing the hydroentangled nonwoven) and/or a middle layer comprises fibers with properties beneficial for strength and/or aesthetical impression.

A good sensory impression can be obtained by having a high proportion, which means at least 50% by weight and preferably at least 75% by weight, short fibers in the form of hardwood, such as eucalyptus, birch or acacia. It is preferred that these short fibers are only slightly or not at all refined, since such a fiber mixture will be beneficial for softness and smoothness.

The aesthetic impression can be enhanced with relatively strong fibers in the back and/or middle layer, for example by using a fiber mixture with a high proportion of long fibers in the form of softwood fibers, which means at least 50% by weight and preferably at least 75% by weight softwood, especially refined softwood. Such a fiber mixture will give strength to the tissue ply which helps to maintain an embossing pattern in the material, thus enhancing the aesthetic impression of the material.

The tissue plies 12 and 13 may be embossed with a macro- and/or micro embossment pattern for example designed to reinforce the textile appearance of the laminate. Macro- embossing is defined as an embossing pattern comprising less than 30 embossing elements per cm², while microembossing is defined as an embossing pattern comprising at least 30 embossing elements per cm². The embossing may occur on the tissue plies before laminating them to the hydroentangled nonwoven web 11 or on the combined plies.

Figure 1 shows no embossment of the tissue plies 12 and 13, while Figure 2 shows an embossing pattern in the form of a plurality of small points 16 configured so as to create a diagonal striped pattern extending obliquely across the striped pattern of the inner hydroentangled nonwoven web 11. This diagonal striped pattern reinforces the textile appearance of the laminate. The depth of the embossments should be at least 0.1 mm in order to provide a clearly visible effect.

Lamination is preferably done by adhesive, such as glue. The glue pattern can be full- coated or preferably covering only part of the surfaces of the plies. A suitable glue pattern is a pattern of small glue sites in the form of dots, lines or spots, including any geometrical or decorative shapes. The glue pattern may have a bonding area of between 2 and 15%, preferably between 5 and 10% calculated as the part of the surface area of the laminate that is occupied by the glue sites.

The bonding pattern and embossment pattern can be the same if the glue lamination occurs in connection with the embossing, for example glue is applied on the tops of the embossments, after which the respective tissue ply is laminated to the nonwoven material.

Besides bonding area also the bonding density will effect the properties of the laminate, such as drapability and softness. Boding density is defined as the number of bonding sites, e.g. glue sites, per area unit. It is preferred that the glue pattern has a bonding density of between 20 and 100 bonding sites per cm². Preferably it has a bonding density of between 30 and 80 and more preferably between 30 and 50 bonding sites per cm². With a high bonding density the laminate becomes less drapable and soft.

It is pointed out that by relatively large bonding sites, for example in the form of lines, a relatively large bonding area may be provided with a relatively small number of bonding sites, as compared to a bonding pattern of small bonding sites, for example in the form of dots, which have to arranged tighter in order to provide the same bonding area as for a pattern of larger bonding size. Thus both bonding area and bonding density are important.

Other ways of laminating the plies are by thermal bonding, wherein at least some of the plies contain thermoplastic material or alternatively a thermoplastic material is added between the plies. The thermal bonding may take place by heat bonding between patterned heated rolls, by ultrasonic welding etc. EXAMPLE

Three laminates according to the invention has been produced having the following compositions:

5

Laminate A:

Two outer plies, each consisting of TAD tissue, basis weight 15 g/m², formed with a 3- layered headbox and comprising: layer 1 (hood layer): Eucalyptus, unrefined; layer 2 (middle layer): softwood pulp, refined 40 kWh/t, 2 kg/ton wet strength agent; layer 3 10 (Yankee layer) Eucalyptus, unrefined. The proportion of basis weights of the three layers were: 40% in layer 1 and 30% each in layers 2 and 3.

One inner ply consisting of wetlaid hydroentangled nonwoven, basis weight 55-57 g/m², with the following fibre composition: 8.0 weight% PP or PET staple fibres (1.7 dtex x 18 15 mm PP or 1.4 dtex x 20 mm PET); 8.0 weight% PP or PET staple fibres (1.7 dtex x 6 mm PP or 1.4 dtex x 6 mm PET); 27.5 weight% PP spunlaid filaments (polypropylene resin, 25MFR); 56.5 weight% cellulose fluff pulp.

When producing the hydroentangled nonwoven material the spunlaid filaments and 20 wetlaid cellulose and synthetic staple fibres were mixed and bonded together by hydroentanglement in two steps of five manifolds each. The first step of manifolds used a pressure of 40 to 100 bars and the second step of manifolds used a pressure of 60 to 100 bars. The spacing between the hydroentangling nozzles were in each manifold was 0.6 mm.The hydroentanglement was done from only one side. The machine speed was 170 25 m/min.

Laminate B:

Two outer plies, each consisting of TAD tissue, basis weight 17 g/m² formed with a two- layered headbox and comprising: layer 1 (hood layer): 80% by weight softwood pulp and 30 20% by weight broke, layer 2 (Yankee layer): 100% hardwood pulp. The proportion of basis weights of the two layers were: 40% in layer 1 and 60% in layer 2.

One inner ply consisting of wetlaid hydroentangled nonwoven, basis weight 55-57 g/m², with the same fibre composition as for laminate A. 35 Laminate C:

Two outer plies, each consisting of dry creped tissue, basis weight 14.5 g/m², with the following fibre composition: 10 weight% softwood sulphate pulp, 30 weight% softwood sulphite pulp, 60 weight% eucalyptus pulp. One inner ply consisting of wetlaid hydroentangled nonwoven, basis weight 55-57 g/m², with the same fibre composition as for laminate A.

In all laminates the plies were laminated together by PVA glue. The bonding pattern contained 42 glue sites per cm². The bonding area was 7.5%.

An embossing of the tissue plies also takes place in connection with the glue lamination. The laminates had the following characteristics:

Figure 3 is a photo of laminate in which the striped pattern of the inner hydroentangled nonwoven is clearly visible. In the photo the embossing pattern of an outer tissue ply is also clearly visible. This embossing pattern is in the form of a plurality of small points 16 configured so as to create a diagonal striped pattern extending obliquely across the striped pattern of the inner hydroentangled nonwoven web. This diagonal striped pattern reinforces the textile appearance of the laminate. The depth of the embossing points should be at least 0.1 mm in order to provide a clearly visible effect. All laminates A, B and C had a sensory and aesthetic perception close to textiles, due to their drapability, soft surface and visible striped pattern of the hydroentangled nonwoven middle ply. The diagonal embossing pattern caused by the lamination reinforced the textile appearance. They had a surface softness close to mangled textiles and both surface softness and bulk softness were similar to what is found in textile napkins. The laminates had a feeling like single ply materials, due to the rather dense lamination pattern in the form of a plurality of glue points.

Claims

1. A tissue paper / nonwoven laminate comprising outer plies (12,13) of tissue paper and an inner ply (11) of nonwoven material, characterized in that said outer plies (12, 13) of tissue paper each have a basis weight between 12 and 20 g/m² and the inner ply (11) is a hydroentangled nonwoven fabric having a basis weight between

40 and 80 g/m² comprising between 30 and 90% by weight pulp fibers and between 10 and 70% by weight manmade fibers and/or natural fibers, wherein the hydroentangled nonwoven fabric has a visible three-dimensional striped pattern of alternating ridges and valleys, caused by hydroentanglement water jets, wherein the distance between adjacent valleys is between 0.3 and 2 mm and the striped pattern is visible from the outside of the laminate through the tissue plies.

2. A laminate as claimed in claim 1 , characterized in that one or both outer plies (12,13) of tissue paper has a basis weight between 13 and 18 g/m², preferably between 14 and 17 g/m².

3. A laminate as claimed in claim 1 or 2, characterized in that the inner ply (11) of hydroentangled nonwoven fabric has a basis weight between 50 and 70 g/m².

4. A laminate as claimed in any of the preceding claims, characterized in that the inner ply (11 ) of hydroentangled nonwoven fabric comprises at least 40% by weight pulp fibers, preferably at least 50% by weight pulp fibers and the rest manmade fibers or filaments and/or natural fibers.

5. A laminate as claimed in any of the preceding claims, characterized in that said manmade or natural fibers have a fiber length of at least 3 mm.

6. A laminate as claimed in any of the preceding claims, characterized in that at least one of the outer plies (12, 13) of tissue paper, preferably both outer plies of tissue paper, is/are through-air-dried tissue.

7. A laminate as claimed in any of claims 1-5, characterized in that one or both outer tissue paper plies is/are a dry creped tissue.

8. A laminate as claimed in any of the preceding claims, characterized in that at least one of the outer plies (12, 13) of tissue paper, preferably both outer plies of tissue paper, is a multilayered tissue comprising at least one layer with at least 50% by weight hardwood fibers and at least one layer with at least 50% by weight softwood fibers.

9. A laminate as claimed in any of the preceding claims, characterized in that the hydroentangled nonwoven fabric (11) is wetlaid.

10. A laminate as claimed in any of the preceding claims, characterized in that the layers of tissue paper are adhesively bonded to the inner ply of hydroentangled nonwoven.

11. A laminate as claimed in claim 10, characterized in that the layer in the laminate are adhesively bonded together in a bonding pattern having a bonded area of between 2 and 15%, of the surface area of the laminate.

12. A laminate as claimed in claim 10, characterized in that the layer in the laminate are adhesively bonded together in a bonding pattern having a bonded area of between 5 and 10%, of the surface area of the laminate.

13. A laminate as claimed in claim 11 or 12, characterized in that said bonding pattern has a bonding density of between 20 and 100 bonding sites per cm².

14. A laminate as claimed in any of the preceding claims, characterized in that at least one ply (12, 13) of tissue paper is embossed.

15. A laminate as claimed in claim 14, characterized in that said embossing pattern comprises a plurality of embossing points (16) configured so as to create a diagonal striped pattern extending obliquely across the striped pattern of the inner hydroentangled nonwoven web.