EP2365129B1

EP2365129B1 - New material

Info

Publication number: EP2365129B1
Application number: EP10155520.9A
Authority: EP
Inventors: Thomas Lööb
Original assignee: Duni AB
Current assignee: Duni AB
Priority date: 2010-03-04
Filing date: 2010-03-04
Publication date: 2013-07-03
Anticipated expiration: 2030-03-04
Also published as: ES2428347T3; PL2365129T3; EP2365129A1

Description

The present invention relates to sheet material comprising tissue paper and filler, in particular such material intended for various table top applications such as napkins, banquet rolls, slip covers, table covers, table skirts, coasters, doyleys, and traymats, and also absorbent articles for female use, such as sanitary napkins, panty liners, and incontinence guards. The invention also relates to a method for the production of such material.
Sheet material of this kind is presently produced by various methods involving lamination two or more tissue layers, such as for instance as described in US 5,466,318 , which discloses a laminate of creped tissue paper, which is formed by applying an adhesive to a first tissue paper in patterns to form a first web, which is then laminated to another tissue paper web by means of a water-based adhesive mixed with a large amount of filler. Another method of this general kind is described in EP 617715 , which discloses a multistage process, in which one or two tissue layers, specifically of wet-laid cellulosic tissue, are coated with an aqueous binder composition - which may or may not contain filler - in the first step and further tissue layers are laminated on, after coating the prelaminate, in subsequent process steps.
For table top applications of the indicated kind it is generally desirable to provide so-called drape, i.e. that the material softly extends over edges and corners in a way which imitates textile fabric materials. This is conventionally accomplished by including a large amount of filler in the adhesive used for lamination.
One object of the present invention is to provide an alternative to these known sheet materials, which alternative offers improved drapability, specifically drapability within a range of about 2.8 to about 2.2 cm as measured by a Shirley stiffness tester M003B, an iinstrument for determining the stiffness of a fabric according to BS 3356 BS 9073 part 7 and ASTM D 1388 standards and for determination of the bending length (as the expression of the drapability). The bending length/drapability is determined by way of the following method:

A rectangular strip of fabric (2.5 mm wide and 20 mm long) is supported on a horizontal platform of the stiffness tester and extended in the direction of its length, so that an increasing part overhangs and bends under its own mass. When the tip of the specimen reaches a plane passing through the edge of the platform and inclined at an angle of 41.5° below the horizontal, the bending length is read off the scale of the apparatus. The mean of the face up, face down and results from both end of the specimen is calculated.

One advantage of the present sheet material is that it has improved drapability combined with improved thicknesses of up to about 0.5 mm, specifically about 0.2-0.5 mm, in particular about 0.2-0.4 mm. Another advantage of the present sheet material is that it provides for optimized usage of the raw materials from which it is made. A further advantage of the present sheet material is that it can be provided with a textile-like, specifically linen-like structure.
A part of this object is accomplished by one general embodiment of the present invention relating to a sheet material which comprises a tissue paper web coated with a 1^st combination of filler and a 1^st binder, which 1^st combination in turn is coated with a 2^nd combination of airlaid lignocellulosic fibres and a 2^nd binder, in which sheet material none of said tissue paper web and said 1^st and 2^nd combinations are laminated to each other.
It was surprisingly found that a sheet material built up according to the present invention, that is by way of a tissue paper web firstly coated with a mixture of filler and binder, and then coated with binder and strewed, sprinkled, or scattered with loose, air-entrained lignocellulosic fibres, could be provided with such improved drapability even at thicknesses of up to about 0.5 mm. The reason behind this would appear to be - although the inventors would not be bound by this theory - that another parameter influencing drapability (i.e. apart from the amount of filler in the binder used) would be the weight ratio between fibres and filler in the final product, such that a lower such ratio provides for better drapability, and that the air lying technique used according to the present invention allows said ratio to assume surprisingly low values.
Furthermore, a lower such ratio would also provide for better efficacy and efficiency in respect of the use of the filler.
It was found that the inventive sheet material could be produced with a fiber:filler weight ratio of from about 0.3 to about 1.5, specifically from about 0.4 to about 1.0.
Another general embodiment of the present invention relates to a method for manufacturing the inventive sheet material comprising:

(i) applying, in any suitable order, filler, a 1^st binder, and/or a combination thereof onto a tissue paper web;
(ii) optionally applying a 2^nd binder onto said tissue paper web;
(iii) air laying lignocellulosic fibres onto said tissue paper web;
(iv) optionally applying a 2^nd binder onto said tissue paper web;

^nd

A substantive advantage of this inventive method is the absence of any lamination of two or more webs; the method is basically a one-step process, providing greatly improved productivity in relation to similar prior art methods.
It was surprisingly found that by way of the inventive method it is possible to obtain sheet materials with significantly higher drapability, and also that penetration of filler to the sheet surface - a problem burdening similar prior art methods, causing spots and discolorations - can be greatly avoided.
As used herein, the term "sheet material" means a material that is thin in comparison to its length and breadth. Generally speaking, the sheet material is intended to exhibit a relatively flat planar configuration and to be flexible to permit folding, rolling, stacking, and the like. Exemplary sheet materials include, but are not limited to, cloths, table-cloths, paper tissue, paper towels, napkins, banquet rolls, slip covers, table covers, table skirts, coasters, doyleys, and traymats; absorbent articles for female use, such as sanitary napkins, panty liners, and incontinence guards; and other fibrous or filamentary products.
As used herein, the term "tissue paper web" means a web of a soft thin, usually translucent, paper.
As used herein, the term "laminated" means "composed of thin sheets superimposed and bonded together by binder(s)".
As used herein, the term "filler" relates to substances in solid, particulate form, the function of which is substantially confined to providing weight and drapability.
As used herein, the term "binder" refers to materials which are capable of attaching themselves to a substrate or are capable of attaching other substances to a substrate, as well as to compositions of such materials.
As used herein, the term "coated" relates to the result of the act of coating a surface with a fluid or semifluid substance or mixture.
The difference between "coated" and "laminated" should be noted.
As used herein, the term "airlaid", as in for example "an airlaid web of lignocellulosic fibres", and the concept of "air lying", as in for example "air laying lignocellulosic fibres", both relate to a process involving deposition of loose, air-entrained fibers onto a surface. The fibers may be such as those from fluff pulp that have been separated from a mat of fibers, such as by a hammermilling process, and then entrained in a moving stream of air and deposited or collected on said surface.
It should be noted that the term "airlaid" is an adjective, not a noun; consequently the term "airlaid" used in isolation does not indicate an "airlaid web" or any similar artifact.
The invention will now be described in further detail below with reference to specific embodiments.
According to one specific embodiment of the present invention the sheet material essentially consists of a tissue paper web coated with a 1^st combination of filler and a 1^st binder, which 1^st combination in turn is coated with a 2^nd combination of airlaid lignocellulosic fibres and a 2^nd binder, in which sheet material none of said tissue paper web and said 1^st and 2^nd combinations are laminated to each other.
According to another specific embodiment the sheet material consists of a tissue paper web coated with a 1^st combination of filler and a 1^st binder, which 1^st combination in turn is coated with a 2^nd combination of airlaid lignocellulosic fibres and a 2^nd binder, in which sheet material none of said tissue paper web and said 1^st and 2^nd combinations are laminated to each other.
The airlaid lignocellulosic fibres are provided by way of deposition of loose, air-entrained fibers onto the surface of the tissue paper web. They may be accompanied by melt binder fibres of two-component type, for example bi-component fibres comprising a fiber sheath made of a polymer having a lower melting point than the polymer of the fiber core. One example of such a fiber is a two-component fiber comprising a polyester core and a polyethylene sheath.
According to one embodiment of the present invention the tissue paper web may be wet-strength-treated, for instance by means of a permanent wet-strength agent that may be chosen among aliphatic and aromatic aldehydes, urea-formaldehyde resins, melamine formaldehyde resins, and polyamide-epichlorohydrin resins, or by means of a temporary wet-strength agent that may be chosen among aliphatic and aromatic aldehydes, glyoxal, malonic dialdehyde, succinic dialdehyde, glutaraldehyde, dialdehyde starches, substituted or reacted starches, disaccharides, polysaccharides, polyethylene imine, chitosan, and reacted polymeric reaction products of monomers or polymers having aldehyde groups, or a combination thereof.
According to one embodiment of the present invention the filler may be a synthetic filler or a mineral fillers, in fibre or powder form, or a combination thereof; in one aspect of this embodiment of the filler may be chosen among molecular sieves such as for instance diatomite, and bentonite; clay, aluminum oxide, siliciumdioxide, polyacrylates, mica, glass fibers, carbon fibers, aramid polymers, graphite, dolomite, chalk, talc, barium sulphate, titanium dioxide, kaolin, wood meal, or any combination thereof.
The 1^st binder and the 2^nd binder may be essentially similar to each other; they may even be taken from one and the same batch. In the alternative they may be quite different from each other.
According to one embodiment of the present invention said 1^st binder and/or said 2^nd binder comprises about 10-80 parts by wt. of an aqueous dispersion of plastic, said dispersion having a solids content of about 30-70 % by wt. of polymers of one or more monomers chosen among acrylic acid esters, methacrylic acid esters, vinyl esters, olefins, vinyl halides, vinyl aromatics and ethylenically unsaturated carboxylic acids and their amides; in one aspect of this embodiment said 1^st binder and/or said 2^nd binder further comprises about 0-10 % by wt., relative to the total weight of the polymers, of N-alkylamides and/or N-alkoxyalkylamides of ethylenically unsaturated carboxylic acids.
Various table top applications may be produced from the inventive sheet material, such as for instance napkins, banquet rolls, slip covers, table covers, table-cloths, table skirts, coasters, doyleys, and traymats, and also absorbent articles for female use, such as sanitary napkins, panty liners, and incontinence guards.
The sheet material of the present invention, or any table top applications or absorbent articles produced thereof may be supplemented by an outer plastic foil, for instance serving as a barrier against moisture and/or dirt.
In one specific embodiment of said method for manufacturing the inventive sheet material the filler is applied onto said tissue paper web; followed by application of the 1^st binder onto said tissue paper web.
In another specific embodiment of said method the filler and the 1^st binder are combined before being applying onto the tissue paper web.
In a further specific embodiment of said method the 2^nd binder is applied onto the tissue paper web, followed by air laying the lignocellulosic fibres onto the tissue paper web; and then optionally applying a 2^nd binder onto the tissue paper web.
In another embodiment of the inventive method additional filler is supplied incorporated in said tissue paper web by way of fibres loaded with said additional filler. The filled fibers can be loaded by means of, for instance, the Lyocell process (see e.g. 12th International Symposium on Wood and Pulping Chemistry, June 9-12, Madison, Wisconsin, p. 305-308) or a stable fiber production process. In one embodiment said fibers may be of organic nature; in one aspect of this embodiment some or all of said fibres may be at least partly of polymeric nature.
In one aspect of this embodiment the said additional filler is of the same and/or similar kind as the filler supplied onto the tissue paper web, whereby the major part of the combined amount of filler is supplied incorporated in said tissue paper web by way of fibres loaded with said additional filler.
One advantage of providing filler incorporated in said tissue paper web by way of loaded fibres would be that any loss of filler during hydroentanglement treatment of the sheet material would be minimized.
One advantage of providing a major part of the combined amount of filler incorporated in said tissue paper web by way of loaded fibres would be to facilitate further converting of the material, such as e.g. embossing, as the binder stratum applied on the tissue paper web would be more flexible; a further advantage of providing a major part of the combined amount of filler incorporated in said tissue paper web would be that the effect of the filler could be amplified, that is similar effects can be achieved by a lower weight ratio of fiber:filler.
A yet further specific embodiment of said method includes a first optional application of the 2^nd binder onto the tissue paper web, followed by air laying the lignocellulosic fibres onto the tissue paper web; which is followed by application of the 2^nd binder onto the tissue paper web.
In each and every one of the embodiments of said method the 1^st and the 2^nd binder, or both, may be applied by any suitable way and means such as spraying or coating, for instance by way of gravure coating, reverse roll coating, knife over roll coating, metering rod coating, slot die coating, immersion coating, curtain coating, or air knife coating.
Another embodiment of the present invention relates to sheet material obtainable by any of the embodiments of said method.
A further embodiment of the present invention relates to table top applications that may be manufactured from the inventive sheet material, such as for instance napkins, banquet rolls, slip covers, table covers, table-cloths, table skirts, coasters, doyleys, and traymats.
Yet another embodiment of the present invention relates to absorbent articles for female use that may comprise the inventive sheet material, such as for instance sanitary napkins, panty liners, and incontinence guards.
The following non-limiting example serves to further illustrate the present invention.

Example 1.

An embodiment of the method of the present invention is carried out as follows:

A wet-strength-treated tissue paper web having a weight per unit area of 25 g/m² is unwound from a reel stand;
an adhesive is applied onto the tissue paper web by way of roller application or spraying, which adhesive has the following composition:
- 40 parts by weight of an aqueous plastics dispersion having a solids content of 52% by weight and based on a terpolymer comprising 70% by weight of vinyl acetate, 25% by weight of ethylene and 5% by weight of N-methylolacrylamide;
- 0.2 parts by weight of an ammonium salt of a polycarboxylic acid 0.033 parts by weight of a silicone antifoam;
- 0.033 parts by weight of polyacrylic acid;
- 55 parts by weight of a filler consisting of barytes having an average particle size of 1 µm;
the binder having a solids content of 76% by weight and a viscosity of 1500 mPa.s (Brookfield 20 rpm, 20°C.) and a pH value of 4.5;
a pulp sheet is separated into individual fibers by unwinding the pulp sheet from a roll and forwarding it by means of driven rolls to a picker roll;
the individual fibers are conveyed through a forming duct and onto the tissue paper web in an amount of 35 g/m²;
an air stream in combination with a vacuum box creates a downwardly moving stream of air which assists in collecting the fibers on the tissue paper web;
the thus treated tissue paper web is then brought through a nip, for example a roller nip, whereafter the web is dried by a dryer.

Although the invention has been described with regard to certain embodiments, including the best mode presently known to the inventors, it should be understood that various changes and modifications as would be obvious to one having the ordinary skill in this art may be made without departing from the scope of the invention as set forth in the claims appended hereto.

Claims

Sheet material, comprising a tissue paper web coated with a 1^st combination of filler and a 1^st binder, which 1^st combination in turn is coated with a 2^nd combination of airlaid lignocellulosic fibres and a 2^nd binder, in which sheet material none of said tissue paper web and said 1^st and 2^nd combinations are laminated to each other.
Sheet material according to claim 1, wherein additional filler is supplied incorporated in said tissue paper web by way of fibres loaded with said additional filler.
Sheet material according to claim 2, wherein said additional filler is of the same and/or similar kind as the filler supplied onto the tissue paper web, whereby the major part of the combined amount of filler is supplied incorporated in said tissue paper web by way of fibres loaded with said additional filler.
Sheet material according to any preceding claim, wherein said 1^st binder and/or said 2^nd binder comprises about 10-80 parts by wt. of an aqueous dispersion of plastic, said dispersion having a solids content of about 30-70 % by wt. of polymers of one or more monomers chosen among acrylic acid esters, methacrylic acid esters, vinyl esters, olefins, vinyl halides, vinyl aromatics and ethylenically unsaturated carboxylic acids and their amides
Sheet material according to claim 4, wherein said 1^st binder and/or said 2^nd binder further comprises about 0-10 % by wt., relative to the total weight of the polymers, of N-alkylamides and/or N-alkoxyalkylamides of ethylenically unsaturated carboxylic acids.
Table-cloth made of the sheet material according to any preceding claim.
Absorbent article for female use, such as a sanitary napkin, a panty liner or an incontinence guard, comprising the sheet material according to any preceding claim.
A method for manufacturing sheet material comprising:
(i) applying, in any suitable order, filler, a 1^st binder, and/or a combination thereof onto a tissue paper web;

(ii) optionally applying a 2^nd binder onto said tissue paper web;

(iii) air laying lignocellulosic fibres onto said tissue paper web;

(iv) optionally applying a 2^nd binder onto said tissue paper web;
provided that said 2^nd binder is applied onto said tissue paper web either in (ii) or (iv) or both of them.
A method according to claim 8, in which additional filler is supplied incorporated in said tissue paper web by way of fibres loaded with said additional filler.
A method according to claim 9, in which said additional filler is of the same and/or similar kind as the filler supplied onto the tissue paper web, whereby the major part of the combined amount of filler is supplied incorporated in said tissue paper web by way of fibres loaded with said additional filler.
A method according to claim 8, in which (i) comprises:
(a) applying said filler onto said tissue paper web; followed by

(b) applying said 1^st binder onto said tissue paper web.
A method according to claim 8, in which said filler and said 1^st binder are combined before applying in (i) onto said tissue paper web.
A method according to claim 8, comprising:
(i) applying, in any suitable order, filler, a 1^st binder, and/or a combination thereof onto a tissue paper web;

(ii) applying a 2^nd binder onto said tissue paper web;

(iii) air laying lignocellulosic fibres onto said tissue paper web; and

(iv) optionally applying a 2^nd binder onto said tissue paper web.
A method according to claim 8, comprising:
(i) applying, in any suitable order, filler, a 1^st binder, and/or a combination thereof onto a tissue paper web;

(ii) optionally applying a 2^nd binder onto said tissue paper web;

(iii) air laying lignocellulosic fibres onto said tissue paper web; and

(iv) applying a 2^nd binder onto said tissue paper web.
Sheet material obtainable by a method according to any one of claims 8-14.
Table-cloth made of the sheet material according to claim 15.
Absorbent article for female use, such as a sanitary napkin, a panty liner or an incontinence guard, comprising the sheet material according to claim 15.