ABSORBENT PRODUCT AND METHOD OF MAKING THE SAME

Abstract: The absorbing material consists of a mixture of chemically produced cellulose (14) and ground paper of the type used in newspapers. The paper is ground, for instance in a hammer mill, so that a mixture of small pieces of paper (15) and relatively long fibers (16) is obtained. When the ground paper is mixed with the cellulose the pieces of paper are oriented parallel to the sheet of absorbing material whereas the long fibers are randomly orientated. The pieces of paper will impede the wetting-through of the material in just one place and divert the fluid parallel to the sheet. The long fibers will serve as wicks and distribute the fluid uniformly in the cellulose throughout the sheet.

Description: Absorbent product and method of making the same The present invention concerns a diaper or equivalent, such as ladies' sanitary towel, consisting of a filling material containing chemical cellulose or equivalent fibres, and this filling material being en ¬ closed within a skin layer. Another product equivalent to baby diapers and ladies' sanitary towels is the so-called chronic invalid's diaper, which also belongs within the scope of the present invention. As known in prior art, baby diapers or equivalent consist of a fil¬ ling which is in the manufacturing process deposited upon tissue paper, and pieces are cut from the combination web thus obtained. The said pieces are folded triple, and such a combination of tissue web and filling is enclosed in a bag made of non-woven web material. As filling in baby diapers of prior art is used chemical cellulose and mechanical pulp, which has been comminuted e.g. in a hammer mill from either sheet cellulose or groundwood pulp. Through the public Finnish patent application No. 1537/70 is known in prior art a sanitary towel or diaper containing in addition to fibrous cellulose pulp, a substance which is elastic in wet as well as dry condition. In the said application has been specified as said resilient substance, e.g. granular foamed plastic. The U.S. Patent No. 2,548,341 discloses a towel wherein as filling material component is used paper, ground very fine and to be lint-like. Since according to this reference the paper has been ground very fine and to be lint-like, in other words into single fibres, the effects aimed at in the present invention are not achieved thereby. It is a drawback of diapers and equivalent of prior art and of their filling materials that when cellulose fibres are used for filling OMPI f h WIPO „ * material the diaper cannot be made bulky (fluffy) enough, nor is any high enough resilience and permanence of shape achieved. It has further been a drawback that even though the diaper as a whole may be absorbent enough, local leakages can occur because the user's excretions do not nearly spread uniformly into the whole volume of the diaper, instead of which they are concentrated on a small area. Also that may be considered detrimental that chemical cellulose in itself is a comparatively expensive material, while on the other hand cellulose has rather good absorption properties. The above-mentioned drawbacks are partly due to the fact that in the manufacturing process the separate cellulose fibres are oriented in a given direction and hereby the bulkiness of the product is impaired and its elasticity reduced because a fibre network with substantially uniform orientation in every direction fails to form wherein bending of the fibres would give rise to elasticity and to permanence of shape and to bulk. With a view to eliminating the drawbacks mentioned, the invention is mainly characterized in that one uses, in addition to chemical cellu¬ lose or equivalent, for filling material component: fine-chopped newsprint and/or other equivalent paper, this latter being used as filling material component in such amount that the diaper's elasticity and/or bulk, absorbence and liquid spread-out are substantially improved. If the newsprint snip component were ground into completely single fibres, it would then conform to chemical cellulose, and by means of such a component one would not be able to increase the diaper's elasticity and/or bulk, absorbence and liquid spread-out over the whole diaper volume, which advantages are specifically implemented when there is used as filling material component, newsprint chopped into appropriate snips as taught by the inventon. According to the invention, the filling material component consists of newsprint or other equivalent paper chopped to snips and which is present in substantial quantity, this being understood to mean that there must be newsprint component amounting to a considerable proportion of the weight of the whole diaper and in such amount at O I all events that the aims envisioned in the main claim are reached. Preferably, the quantity of newsprint snip component is about 40 to 60% by weight, but the invention is not confined to this amount since in certain cases, primarily dependent on the intended use of diaper, the objects of the invention may also be attained with a diaper having a newsprint snip component either slightly less than 40% by weight or slightly more than 60% by weight. It is a substantial advantage afforded by the diaper of the invention that newsprint snip component brings about the result that liquid will spread out uniformly in the diaper owing to capillary phenomena, so that the diaper is wetted all the way up to its ends, and whereby the -full absorbing capacity of the diaper is utilized. It has been found in practice that the diaper of the invention when it becomes wet acquires a stratified structure so that local penetration of liquids is inhibited and so that even when wet the diaper possesses in all directions sufficient strength, with the result of reduced breaking of the diaper in wet condition. Also another advantage of the invention is obvious from the foregoing: that as generally the wetting effect acts on the diaper quite locally, the diaper will not begin to run at this point because thanks to the newsprint snip component liquids spread out more efficiently than before from one end to the other of the diaper. The invention is described in detail in the following, with reference being made to a certain embodiment example of the invention, presented in the figure of the attached drawing. Fig. 1 displays the cross section of a diaper of the invention in sub¬ stantially natural size. Fig. 2 shows a partial section, parallelling the plane of the diaper, of the diaper filling. Fig. 3 illustrates an apparatus by which diapers according to the invention are manufactured. Referring now to Figs. 1 and 2, the diaper 10 therein depicted, or equivalent such as a ladies' sanitary towel for instance, consists of a filling 14, which is by means of an apparatus such as Fig. 3 shows, when manufacturing diapers 10, conveyed onto a tissue web 11. From the combination web 11, 14 produced in the manner described, lengths are cut as known in itself in the art and these are folded to become a tri-ply part as shown in Fig. 1, and such an entity is enclosed in a bag consisting of a non-woven web 12, which is provided with a seam 13. It is substantially novel in the invention that the filling 14 of the diaper is not made in its entirety of loose cellulose fibres, but instead as material for the filling 14 is used newsprint or other equivalent paper or cardboard, which has been ground into suitable particles before its introduction in the filling. According to a favourable embodiment of the invention, one uses in the filling 14, between 40 and 60% by weight of newsprint, the other filling material component consisting of free, chemically manufactured cellulose fibres. Excellent preliminary experiences were gained with a diaper containing 50% newsprint and 50% cellulose, the newsprint having been comminuted in a hammer mill 22 (Fig. 3) partly to snips 15 and partly to fibres 16, which are rather long, above all when newsprint is used which has been made partially of mechanical groundwood, for instance of thermogroundwood. For the other component of the diaper filling one will use to advantage such newsprint or equivalent 2 which has a basis weight between 30 and 80 g per m . It is furthermore advantageous to use for said other component a paper web containing no fillers, or not much of them at least. When newsprint is being turned out on a paper machine, rather large quantities of such paper are produced which is lacking in quality for newspaper printing, but which is eminently suitable to be used to the purposes of the present invention. When newsprint or equivalent is being used for filling material of diapers as taught by the invention, the characteristics of the diapers improve, for the following reasons. Particularly newsprint made partly from thermogroundwood contains long fibres. These long fibres are partly separated in the grinding process in the newsprint and hammer mill, and the fibres increase the elasticity and bulk of the product. When the newsprint or equivalent is ground in such manner that newsprint snips are left in the filling which have a largest dimension substantially in the range of 3 to 10 mm, such snips will in the manufacturing process of the diapers, to be described later on, become oriented mainly parallel to the plane of the diaper, and snips so oriented contribute to better permanence of shape and elasticity of the diaper. The said snips increase the rigidity in bending of the diaper, this being evident in accentuated manner when the snips are subjected to bending in the folds of the diaper. Moreover, said snips inhibit the straight passage of excre¬ tions through the diaper courses, because they are somewhat less per- meable than the cellulose component proper, and thereby they direct the excretions to a wider area in the filling of the diaper. It is also an important advantage that newsprint is a substantially less expensive material than chemically manufactured cellulose. In the diaper of the invention, the cellulose component and the newsprint component may be substantially uniformly distributed in the filling of the diaper, but it may be advantageous in one instance to make stratified structures having at certain points mainly or exclusively paper component and at others, mainly or exclusively cellulose component material. In the following is briefly described an apparatus and a procedure by which diapers according to the present invention are manufactured. The apparatus applied in the procedure comprises a conveyor belt 21 moving over return wheels. At the front end of the conveyor 20, 21 has been disposed, within the loop of the wire-like and permeable conveyor band 21, a suction box 25, from which a suction connector 27 leads to a vacuum pump 26. Above said suction box 25 is located a chamber 24, into which filling material is supplied through the pipe 23 from a hammer mill 22 or equivalent. Into the hammer mill is from the reel 29 conducted a cellulose web 29', consisting of chemical cellulose. Into the same mill is conducted with higher speed, from the reel 28, a paper web 28', or a plurality of webs, so that an appropriate cellulose/paper component proportion is obtained. In the hammer mill 22 an appropriate sieve is employed so that an ex¬ pedient size distribution of the paper component is obtained as the cellulose component is ground down to separate fibres. Onto the conveyor belt 21 is supplied from the reel 31, a tissue paper web 31', upon which the filling material produced from the webs 28' and 29' is deposited with the aid of suction. Hereafter, the combination web thus obtained is cut into lengths and folded to have the form shown in Fig. 1, and the diaper blanks thus obtained are enclosed in bags formed from the non-woven web 30' co ing from the reel 30, so that a diaper 10 as shown in Fig. 1 is produced. The device disclosed above is provided with previously known auto- matisation and cutting means, which are not necessary to be specified in detail in this connection. Although in the foregoing mainly baby diapers have been discussed, other equivalent products, such as ladies' sanitary towels for instance, also fall within the scope of the present invention. In the following are presented the claims, different details of the invention being allowed to vary within the scope of the inventive idea thereby defined. OMP WIP

Claims: Claims 1. A baby diaper or equivalent, such as a ladies' sanitary towel, consisting of a filling material containing chemical cellulose or equivalent fibres, and said filling material having been enclosed within a skin layer (12), characterized in that for filling material component is used, in addition to chemical cellulose or equivalent, newsprint, and/or equivalent paper chopped into snips, the latter filling material component being used in such quantity that the elasticity and/or bulk, absorbence and liquid spreading of the diaper will substantially improve. 2. Diaper according to claim 1, characterized in that of the component consisting of newsprint or equivalent there is in the filling (14) of the diaper about 40 to 60% by weight, the rest consisting mainly or totally of chemical cellulose. 3. Diaper according to claim 1 or 2, characterized in that as news¬ print component is used exclusively or mainly newsprint web so ground in a hammer mill (22) or equivalent that the filling material is in substantial part composed of newsprint snips having a size mainly about 3 to 10 mm. 4. Diaper according to claim 1, 2 or 3, characterized in that as newsprint component in the fillings (14) of the diaper is used such newsprint which has been made of pulp containing thermogroundwood or other mechanical pulp with comparatively long fibres. 5. Procedure according to claim 1,2,3 or 4, characterized in that the newsprint component and the filling material component consisting of chemical cellulose are substantially uniformly distributed in the fillings (14) of the diaper. 6. Diaper according to claim 1,2,3 or 4, characterized in that news¬ print component and cellulose component are found in stratified arrangement in the filling of the diaper. OMPI IPO

Inventors: NUORTIE R
Applicants: NUORTIE R
Application year: 1980
Main classification: A41B13
IPC codes: A61F13