DE4024053A1 - Absorbent products for use in hygiene e.g. pads - comprises various thermoplastic binding fibres made with specific densities over cross=section by air deposition, heating and compressing - Google Patents

Abstract

An absorbent article is for use in hygienic prods. made of thermoplastic binding fibres or mixts. of thermoplastic binders and viscose staple, cotton, flock and/or artificial fibres in the form of individual absorbent pads or sheets which have parts with different densities distributed over the cross-section. The article has three such parts making up one integral layer, namely two outer areas of density 0.005-0.1 g/cm3 and a centre area of density 0.05-0.3 g/cm3. Prefd. structures incorporate polyester/polyethylene staple fibres. USE/ADVANTAGE - For sanitary prods. The prod. has good liq. absorption and liq. distribution when its thickness is of the order of 1 or a few mm. In an example, a fabric of 150-500 g/m2 is made by aerodynamically depositing polyester-polyethylene staple fibres 20-100mm long with a titre of 1.7-20 dtex. This is heated with air at 150-250 deg.C and consolidated to about 1/4 original thickness, e.g. by cold rollers, etc. An originally 30mm thick material, heated 20 secs. in an air draught oven at 150 deg.C, is reduced to 13mm. While still warm this is pressed between steel plates with smooth finish and at room temp. Pressing for 26 secs. reduced the thickness further to 7mm. This was bonded to a sheet of non-woven fabric and reduced to 2mm thickness. The liq. absorption of the prod. was over 1.0g per article; its elasticity was 94% and porosity to air was above 10 1/10cm2 under 0.2 kpa pressure.

Description

The invention relates to an absorbent body for hygienic Fiber products made from thermoplastic binding fibers or Mixtures of thermoplastic binders with cellulose le, cotton, cellulose flakes and / or plastic company sern in the form of individual suction pads or webs that over the cross-section distributed different density ranges exhibit.

From the European patent specification 01 69 184 is a chamfer absorbent body for use in disposable products sen, known as diapers, sanitary napkins or the like, that of absorbent fibers and a heat acti suitable binders, preferably in the form of adhesive sern, exists. The absorption body is thus known records that the absorbent fibers and the binder tel form a homogeneous connection and that the Absorpti body as "a result of a gradually increasing The extent of fiber sticking and pressing together in one Direction perpendicular to its largest area "a continuous has a nuclear increase in density. Through this structure should have the highest possible liquid capacity and a good fluid distribution in the absorbent body can be achieved. The technological means by which the described Absorbent body structure, in particular the density ver division over the cross section is reached  in that initially a uniform mixture of Absorp laid fibers and binding fibers to a pile and this by supplying heat to the activation temperature of the binding fibers is heated. The train will then open cooled down to a temperature just below the Ak Activation temperature of the binder is. Subsequently the web is rolled in a second stage squeezed, one of which is cold, or at least at a temperature below the activation temperature binder is located, whereas the counter roller has a temperature which is the activation temperature of the Binder exceeds. Through these measures achieved that the binding effect in the direction of the hot Roll to cold roll decreases and the web after the pas sieren at least one such roller pair he mentioned density gradient.

Further studies on heated and post-compacted floras have shown that a different density distribution leads to deviating and surprising results, specifically when the absorbent body or the absorbent web has three density areas to form an integrated distribution layer, namely two outer areas, each with a density of 0.005-0.1 g / cm ³ and a medium range with a density of 0.05-0.3 g / cm ³ . A web or an absorbent body with such a density distribution also has remarkably good properties with regard to liquid absorption, liquid distribution and liquid storage capacity if the web is produced with only a small final thickness of, for example, the order of magnitude of one or a few millimeters. Before the parts are not limited to webs of small thickness be; rather, such webs or absorbent bodies can also be used advantageously where larger web thicknesses are required in view of the amounts of liquid to be absorbed.

The two outer density ranges of the proposed Absorbent body or the proposed absorbent sheet should each 10-40% of the total height and the middle Density range 20-80% of the total height of the absorbent or take the train. The desired properties zei are particularly suitable if the density ranges jump into each other and not like this the previously known European patent 01 69 184 of Case is continuous. To further improve the Properties can be the side of the body close to the body when used Absorbent have a structural embossing like this is known.

To manufacture the proposed absorbent with Neuar density distribution is first a pile by aero dynamic deposition of thermoplastic binding fibers or Mixtures of thermoplastic binders with cellulose le, cotton, cellulose flakes and / or plastic company formed. The pile will then be activated temperature of the binder or the binding fibers heated and then compacted.  

The procedure is such that the compression of the Activation temperature heated web or absorbent un without delay, that is, without intermediate cooling with the help of two a cold nip forming rolls, belts or Metal plates are made.

The absorbent or webs to be produced can therefore made entirely of thermoplastic binding fibers, for example as polyethylene fibers, polypropylene fibers or Bi Component fibers consist of these two components. Furthermore, z. B. suitable bicomponent fibers, de a component made of polyester and its other compo nente consists of polyethylene or the like. Other on the one hand, it may be advantageous not to fill the absorbent body fully constantly from such thermoplastic binding fibers build, but instead mixtures of thermoplastic rule binders, for example the fibers mentioned with cellulose, cotton, cellulose flakes and / or Use plastic fibers.

Plastic fibers come from non-thermopla materials, z. B. polyurethanes or thermosets into consideration. However, fibers made of thermoplastic can also be used materials are used, their softening temperature temperature above the softening temperature of the bindemite tels lies.  

If such mixtures are used, the bin they do not necessarily have a fiber shape; in this case Particulate binders can also be used but then again around z. B. polyethylene, Po lypropylene or polyester copolymers. The one in the case of blends to be used in cellulose or cotton should preferably be a length of 10-40 mm as well have a titer of 1.7-8 dtex.

If plastic fibers are used, they should be one Length of 20-100 mm, preferably about 60 mm and a Ti ter of 1.7-20 dtex, preferably 3-4 dtex.

If binding fibers are used alone or in a mixture with cellulose, Cotton, cellulose flakes and / or plastic fibers used, they should have a length of 20-100 mm have a titer of 1.7-20 dtex.

A preferred method of making the proposal NEN absorbent body is characterized by the following steps draws:

• - Forming a pile of 150-500 / g / m ² by aerodynamically depositing polyester-PE bicomponent staple fibers in a length of 20-100 mm and a titer of 1.7-20 dtex;
• - Warm the pile by passing warm air through it a temperature of 150 ° C-250 ° C;  
• - Compress the warm pile to about a quarter of the original jump height by means of two form a press nip the cold rollers, strips or plates made of metal.

Another embodiment of the method is by fol marked steps:

• - Make a mixture of 20-30 percent by weight Sta Fibers made of cellulose or cotton (length of the fibers 10-40 mm; Titer 1.7-8 dtex) or cellulose flakes as well 70-80 weight percent polyester-PE bicomponent stack fibers with a length of 20-100 mm and a titer of 1.7-20 dtex;
• - Forming a pile of 150-500 g / m ² by aerodynamic deposition of the above mixture;
• - Warm the pile by passing warm air through it a temperature of 150 ° C-250 ° C;
• - Compress the warm pile to about a quarter of the original jump height by means of two form a press nip the cold rollers, strips or plates made of metal.

Particular importance is attached to the proposed Procedure to the compaction tools. These tools consist, as I said, of cold rolls, strips or  Plates of metal. Preferably two steel strips used, which is cooled by air to room temperature will. The thermal conductivity of the steel to be used is 15-70 J / s × m × K, where J is the amount of heat in joules, s the time in seconds, m the mass in kg and K the temp rature in Kelvin means.

The method proposed according to the invention is described in the fol genden explained in more detail using some exemplary embodiments tert.

A mixture of 25% cellulose (3.6 dtex; 30 mm fiber length) and 75% polyester-PP bicomponent fibers (3.3 dtex; 60 mm fiber length) was processed. The fiber mixture was opened via a card and aerodynamically laid to a pile with a basis weight of 170 g / m ² and a pile height of 30 mm. The pile was heat set in a forced air oven at 150 ° C. for 20 seconds, the thickness being reduced to approximately 13 mm. The still warm, thermally reinforced fabric was subjected to intermediate zone compression immediately after leaving the thermofixing unit, namely by squeezing between two steel plates cooled to room temperature with a smooth surface. The pressure treatment time was 26 seconds. The resulting product had a height of approximately 7 mm. It was then laminated with a nonwoven and calibrated to a final thickness of 2 mm.

The liquid retention capacity of the product so produced was determined to be over 1.0 g per absorbent. For ver same: the liquid was without a compressed intermediate zone holding capacity less than 0.5 g.

The resilience was determined to be 94%. The air permeability was greater than 20 l / 10 cm ² × min at a test pressure of 0.2 kpa.

Example 2

The process steps were the same as in Bei game 1. Instead of the fiber mixture used there, uses a pile that is 100% hydrophilic Bi component fibers existed.

The product produced had fluid retention of over 2.0 g per absorbent. The resilience and air permeability corresponded to the product which was obtained according to Example 1.

Example 3

The process is also suitable for the manufacture of menbands. The same process steps were carried out as described in Example 1. The fiber mixture used also corresponded to that from Example 1. Only the basis weight of the pile was 450 g / m ² . The final product produced was 17 mm thick.

The measured values were:
Liquid holding capacity approx. 110 g / absorbent body (120 × 220 mm).

For comparison

The liquid retention without compressed intermediate zo ne was approx. 34 g per absorbent.

The invention is described below with reference to the Drawing explained in more detail. They represent:

Figure 1 is a perspective view of an embodiment form of a thin absorbent body according to the invention.

Fig. 2 is an enlarged view of section II-II;

Fig. 3 is a schematic representation of the procedural run.

In Fig. 1, a panty liner is shown as an embodiment, which is designated as a whole with 1 . The A layer consists of a thin, about 2 mm thick fiber gel ge, which has been subjected to the intermediate zone compression according to the invention. The use surface 2 shown in the drawing (body-near side) has a nonwoven layer 3 and shows on the one hand a line embossing 4 and on the other hand a dot embossing 5 . The dot embossing 5 extends over the entire Ge surface 2 ; only for the sake of simplicity, only a portion of the point embossments is shown in FIG. 1.

Fig. 2 shows that the product is made up of a total of three zones of different density, namely two outer regions 6 and 7 , each with a relatively low density of 0.005 to 0.1 g / cm ³ and a central region 8 with a higher Density 0.05-0.3 g / cm ³ . The areas 6 , 7 and 8 merge into one another in leaps and bounds and nevertheless form a coherent system due to the intimate fiber interlacing, in which the central area 8 acts as an integrated distribution layer.

In the upper area of FIG. 2, the laminated nonwoven layer 3 can be seen as well as the line embossing 4 .

In Fig. 3 the sequence of the manufacturing process of the absorbent body or webs is shown schematically. The unit 10 is used for fiber dissolution and, if necessary, mixing. The output fibers are fed to this unit. The aggregate can be described as a whole as a fiber processing plant.

From the fiber processing system 10 , the fibers get into the unit 11 , where they aerodynamically body to individual suction or are deposited to an absorbent web. The unit 11 is a card.

After laying, the absorbent or the web for heat-setting get into the convection oven 12 . From here, the product is immediately passed on without intermediate cooling into the intermediate compression apparatus 13 , for the symbolic representation of which the two air-cooled compression bands 14 and 14 'were chosen.

The compressed product is then covered with a nonwoven web 16 , which is drawn off from a supply roll 17 . Both webs are then fed to the embossing calender 18 , where they are laminated on the one hand and embossed on the other. The finished product leaves the plant at 19 and can, if it is a web, be rolled up; but it can also be divided into individual suction bodies, for example panty liners or the like.

Reference symbol list

1 panty liner (absorbent body)
2 user surface
3 nonwoven layer
4 line embossing
5 point embossing
6; 7 outer areas
8 middle area
9 -
10 fiber processing plant
11 card
12 convection oven
13 intermediate compression
14; 14 ′ compression bands
15 product
16 nonwoven web
17 supply roll
18 embossing calender
19 finished product

Claims (7)

1. Absorbent body for hygienic fibrous products made of thermoplastic binding fibers or mixtures of thermoplastic binders with cellulose, cotton, cellulose flakes and / or plastic fibers in the form of individual suction pads or webs that have different density ranges distributed across the cross section, thereby characterized in that the absorbent body ( 1 ) has three density areas to form an integrated distributor layer, namely two outer areas ( 6 ; 7 ) each with a density of 0.005-0.1 g / cm ³ and a central area ( 8 ) with a density from 0.05-0.3 g / cm ³ . 2. Absorbent body according to claim 1, characterized in that the two outer density areas ( 6 ; 7 ) each 10-40% of the total height and the middle density area ( 8 ) 20-80% of the total height of the absorbent body ( 1 ) men. 3. Absorbent body according to claim 1 or 2, characterized in that the density areas ( 6 , 8 , 7 ) jump into one another. 4. Absorbent body according to claim 1, 2 or 3, characterized in that the side of the absorbent body ( 1 ) close to the body in use has a structural embossing. 5. A method of manufacturing an absorbent after of claims 1-4 by aerodynamic placement of thermoplastic binding fibers or mixtures of ther plastic binders with rayon, cotton, Cellulose flakes and / or plastic fibers, heating of the pile thus formed to the activation temperature of the Binder or the binding fibers and subsequent Condense, characterized, that the compression of the activation temperature he warmed the web or absorbent immediately, i.e. without Intermediate cooling with the help of two one press nip forming cold rolls, strips or plates made of Me tall. 6. The method according to claim 5, characterized by the following steps:

• - Formation of a 150-500 g / m ² heavy pile by aero dynamic deposition of polyester-PE-bicomponent staple fibers with a length of 20-100 mm and a Ti ter of 1.7-20 dtex;
• - heating the pile by passing warm air at a temperature of 150 ° C-250 ° C;
• - Compress the warm pile to about a quarter of the original height by means of two cold rollers, strips or plates made of metal forming a press nip.

7. The method according to claim 5, characterized by the following steps:

• - Manufacture a mixture of 20-30 percent by weight staple fibers made of cellulose or cotton (length of the fibers 10-40 mm; titer 1.7-8 dtex) or cellulose flakes and 70-80 percent by weight polyester-PE bi-component staple fibers (length 20-100 mm; titre 1.7-20 dtex);
• Formation of a pile of 150-500 g / m ² by aerodynamically depositing the aforementioned mixture,
• - heating the pile by passing warm air at a temperature of 150 ° C-250 ° C;
• - Compress the warm pile to about a quarter of the original height by means of two cold rollers, strips or plates made of metal forming a press nip.