Paper making and fiber liberation – Processes of chemical liberation – recovery or purification... – Waste paper or textile waste
Patent
1997-06-11
2000-08-01
Nguyen, Dean T.
Paper making and fiber liberation
Processes of chemical liberation, recovery or purification...
Waste paper or textile waste
162191, D21B 108
Patent
active
060961678
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL AREA
The present invention relates to a process of manufacture for a coloured fibre material, containing a certain proportion of cellulose fibres, such as paper or nonwoven, wherein a dyestuff is applied onto reel or sheet pulp either on the whole material or only on part of it. The invention further relates to a coloured fibre material manufactured according to the process.
BACKGROUND OF THE INVENTION
Nowadays paper is as a rule coloured with cationic direct dyes, which are water insoluble dyestuffs with strong affinity to cellulose fibres. The dyestuff is generally added to the fibre dispersion, i.e. the fiber dispersion in water which is applied onto the wire, but it can also be applied onto the completely formed paper sheet by means of various application methods. These colouring methods have in common that they give a dyeing of all pulp fibres containing reactive groups whereby a comparatively evenly coloured paper sheet is obtained. In manufacture of paper based on recycled fibres it occurs that coloured paper is reused and thereby a recycled paper pulp is obtained with an element of coloured fibres giving a paper with a mottled colour.
Coloured nonwoven materials can be manufactured in different ways, e.g. by addition of a certain proportion of coloured synthetic fibres. This is however comparatively expensive because of the high price involved with coloured fibres. A cheaper way of colouring nonwoven material is to apply dyestuff by means of some form of finishing treatment such as Foulard treatment or by printing of dyestuff possibly together with a binder. Both Foulard treatment and printing make great demands on accurate dyestuff dosing systems if a result pleasing to the eye is to be obtained.
In certain types of soft tissue paper, e.g. napkins and nonwoven material, a mottled colouring may be preferable because of aesthetic reasons, since a mottled colouring is associated with textile rather than paper.
It is known from U.S. Pat. No. 4,202,852 to manufacture a coloured drylaid nonwoven material by applying dyestuff onto reel or sheet pulp, which is thereafter dried to a moisture content of less than 15% and defibrated in a hammer mill. The fibres are airlaid onto a wire, whereupon a binder is added to the airlaid fibre web. After curing of the binder an evenly coloured drylaid fibre material is obtained.
OBJECT OF THE INVENTION AND MOST IMPORTANT FEATURES
The object of the present invention is to achieve a simple process for colouring of wetlaid or foamformed fibre materials, such as paper and nonwoven. The process should allow both a complete colouring of the material as well as a mottled colouring. According to the invention this has been achieved by applying a dyestuff onto reel or sheet pulp either on the whole material or only on part of it, whereupon the reel or sheet pulp is dispersed in a liquid or foam possibly together with other fibres, and that the fibre dispersion is applied onto a wire and dewatered, whereupon the formed fibre web, which contains a substantially even addition of coloured fibres, is subjected to possible further treatment steps before drying and reeling.
DESCRIPTION OF THE INVENTION
Either all reel or sheet pulp is dyed or only part of it. In partial dyeing the dyestuff is suitably continously applied in a streak along the reel pulp, whereby the width of the streak determines how large a portion of the pulp is coloured and the dyestuff concentration determines the colour strength of the coloured pulp fibres. In partial dyeing between 1 and 50% of the pulp fibres are suitably coloured. A multi-coloured material can also be obtained by applying several different colours in different streaks, which for example enables the manufacture of material which at a distance appears to be green but which in reality contains both yellow and green pulp fibres.
The dyestuff used should have strong affinity to cellulose so as to fix it to the pulp fibres without spreading or bleeding out to the water or foam when defibrating the pulp. Conventional cationic dire
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patent: 2905583 (1959-09-01), Feigley, Jr. et al.
patent: 3377235 (1968-04-01), Webster
patent: 3660226 (1972-05-01), McKeown
patent: 4202852 (1980-05-01), Pauls et al.
patent: 4243480 (1981-01-01), Hernandez et al.
Holm Ulf
Reiner Lennart
Nguyen Dean T.
SCA Hygiene Paper AB
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