FI96625C - Method and calender apparatus for calendering an absorbent layer formed by dry forming technique - Google Patents

Description

96625

The present invention relates to a method and a calendering apparatus for calendering an absorbent layer formed of a fibrous material by a dry forming technique.

For example, in the manufacture of non-woven hygiene products, a dry forming technique is used to form an absorbent layer to which a binder or binder fibers are added which, under the action of heat, bind the formed web of material into a porous layer of material. The suction layer may also consist of several overlapping layers according to the desired thickness.

Layers of material made in this way are used in the manufacture of various diapers, women's menstrual pads and hospital wound pads. Hygiene products to which a superabsorbent has been added topically to improve absorbency are also known.

In various products, the desired result is usually achieved in terms of the operation of the products. However, e.g., providing areas of different absorbency to the same product generally requires different process steps, such as addition of superabsorbent particles, additional calendering, etc. Lower absorbency areas are most easily obtained by compacting them separately by calendering and have the advantage of transferring liquid to the product better and faster. .

On the other hand, as dry-formed products become more common in homes, for example in the form of kitchen towels and napkins, attention must be paid to properties other than absorption. Among other things, the appearance, "feel" and recognizability of products are important features in consumer-oriented products. Despite their good properties, the known dry-forming products for final consumers do not differ sufficiently from traditional paper products 2 96625 to make their higher price justified.

The object of the present invention is to provide a method and an apparatus for producing an absorbent layer by means of which dry-formed fibrous material can be easily made into both usefully patterned absorbent layers for e.g. hygiene products and individual, conventional paper products with different appearance, feel and properties. To achieve this, the method according to the invention is characterized in that the dry-formed web of material is introduced into a nip formed by calendar rolls by wires consisting at least on one side of the web of transfer wire and one or more patterning wires superimposed thereon, and that the web is calendered against an embossing pattern corresponding to the pattern of said one or more pattern wires is formed on the surface.

This provides an easy and flexible patterning of the patterned fish, which can be easily incorporated into existing paper machines, e.g. at the transfer wire of the forming part and the binding part. The patterned wire is easy to manufacture and easy to change as needed, which is an advantage especially in small series.

The various embodiments of the method according to the invention are characterized by what is stated in the following claims.

The calender device according to the invention is characterized in that the calender device consists of at least two opposite calender rolls, the nip formed by which a dry-formed material web can be fed, and on the other side of the material web at least one endless transfer wire and one or more that the surface of the calendered material path- Λ av I i: iii ii ΐϋ ·.

3,96625, an embossing pattern corresponding to the patterning of said one or more patterning wires is formed.

The invention will now be described in more detail by way of example with reference to the accompanying drawings, in which Figure 1 schematically shows a calender device according to the invention, Figure 2 shows a pattern wire of a calender device according to Figure 1, Figure 3 shows a cross section of 10 absorbent layers according to the invention.

Figure 1 shows a calender device according to the invention, in which a material web 2 is formed on a wire 1 in a conventional manner by means of forming boxes, i.e. formers (not drawn). The fibers forming the web may be a relatively long fibrous mechanical pulp which is bonded after calendering with either latex and heat. The fibers of the material web can also be formed partly or even completely from plastic fibers, whereby the material web is bonded after calendering in the so-called thermobonding process: 20 bridges. The plastic fibers can be of any suitable therapeutic quality, e.g. bicomponent fibers with a polypropylene core and a polyethylene sheath. The material web may contain 15-85% wood fiber (pulp fiber), 10-70% plastic fiber and 5-75% superabsorbent particles. The surface weight of the formed material-25 track can be of the order of 80 g / m2.

The calendered material web 3 is transferred to the binding and finishing steps (not drawn). The calender device according to the invention comprises two opposite calender rolls 4 and 5, of which the roll 4 is a rubber-coated roll and the roll 5 is a heated roll, the nip 8 formed by which is dry-formed. 'dated material path 2 is entered. It further comprises an endless smooth transfer wire 6 above the web of material and at least one endless patterning wire 7 placed on it. The patterning of the patterning wire is formed by making openings in it corresponding to the desired embossing of the web of material.

The purpose of the patterning may be to facilitate the passage of liquid to the desired locations on the product, thereby forming channels through which the liquid can travel more rapidly to all parts of the product, and / or to provide a decorative or "grip-friendly" patterning. Figure 2 shows a number of different openings, A and B and C, formed for the sake of simplicity 10 and formed on the same patterning wire 7, which represent different uses of the product according to the invention. Figure A is a fruit pattern suitable for e.g. napkins or similar products.

15 Figure B is a typical hygiene product, and Figure C is a dense pattern, for example suitable for household towels or the like. However, these should only be understood as examples, as the purpose and size of each product determines how it is cut from the material path. Thus, the figures shown in Figure 2 do not, as such, indicate the size of the products or their intended use. Thus, it is possible to form the pattern desired by the customer on a custom order on the wire 7, after which the product thus customized and individual is obtained by passing a web of material through the dry paper machine 25 completely according to the basic process.

Figure 2 clearly shows the basic idea of the manufacturing method according to the invention, according to which the dry-formed material web 2 is introduced into the nip formed by the calender rolls by means of wires 1, 6 and 7. The pattern is formed by a smooth transfer wire 6 and a pattern wire 7 placed on it. When the material web 2 is calendered against the wires 6 and 7, an embossing pattern corresponding to the pattern (A, B or C) of the material web 7 is formed. It is also possible to use more than one patterning wire, whereby step-35-like three-dimensional embossments can be obtained.

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5,96625

Figure 3 shows a cross-section of a suction layer 3 obtained according to the invention. The suction layer consists of a base layer 3a with a higher density and an embossing pattern 3b of the base layer having a higher porosity.

It will be apparent to those skilled in the art that the various embodiments of the invention are not limited to the examples set forth above, but may vary within the scope of the claims below.

Claims (4)

96625 A method for calendering an absorbent layer formed of fibrous material by a dry-forming technique, characterized in that the dry-formed material web (2) is applied to a nip (8) formed by calender rolls (4,5) by wires formed on a transfer wire (6) at least on one side of the web. and one or more patterning wires (7) superimposed thereon, and 10 that the web of material is calendered against the wires (6,7) so that the pattern (A, B, C) of said one or more patterning wires (7) is formed on the surface of the calendered web of material (3) corresponding embossing pattern (3b). Method according to Claim 1, characterized in that the pattern of the material web is formed by means of a substantially smooth transfer wire (6) and a pattern wire (7) placed on it, in which openings corresponding to the desired embossing of the calendered material web (3) are formed. B, C). : 20 Calender device for calendering an absorbent layer formed of fibrous material by a dry forming technique, characterized in that the calender device consists of at least two opposite calender rolls (4,5), the nip (8) formed by which the dry formed material web (2) can be fed, and on the other side of the web of material at least one endless transfer wire (6) and one or more endless patterning wires (7) placed on it, against which the web (2) can be calendered so that the surface of the calendered web (3) is formed by said one or more an embossing pattern (3b) corresponding to the patterning (A, B, C) of the patterning wire (7). Calender device according to Claim 3, characterized in that the pattern-forming wires consist of a substantially smooth transfer wire (6) 35 and a pattern wire (7) placed on it, in which openings (A, B, C) corresponding to the desired embossing of the calendered web (3) are formed. ). ; | Mii ltlU l ii SI i: i 96625