Technical Field

The present invention relates to an absorbent core layer which is obtained by pressing method and which homogeneously distributes SAP (super absorbent polymer) and PULP, both of which forms said absorbent core layer, and smoothly delivers fluid coming onto said layer to front and back parts of the absorbent article and thereby allows the strength of integrity of the absorbent core to increase even in the wet state.

Prior Art

The absorbent core layer of the diaper product generally consists of two main raw materials; These raw materials are SAP (Super Absorbent Polymer) and PULP. There is a non-woven fabric structured material surrounding these two components together. In order to hold these two components together, a hot melt adhesive is applied on this non-woven fabric structure. The fluid coming to the hygienic product is trapped in the absorbent core layer with the mixture of these two components. Homogeneous distribution of SAP (Super Absorbent Polymer) and/or PULP and ensuring that the incoming fluid is properly transferred to the front and back of the diaper is very important in terms of the integrity of the absorbent core layer.

In the commonly used techniques, the mixture of SAP and PULP is mixed homogeneously into the drum equipment and fed into the system at the same density or at the rates determined by the manufacturer in each part of the drum mold. When the usage habits of the consumers are evaluated, it is seen that they tend to change the diaper of their babies before the urine reaches the front and back ends of the diaper. In this case, since the diaper is not used at full capacity, the front and back ends of the absorbent core layer remain dry. The mixture of SAP and PULP wetted in the absorbent core layer breaks off the unwetted mixture in pieces and the integrity of the absorbent core layer is damaged. In the wet absorbent area layer parts, depending on the movement of the baby, the strength of adhesive weakens in the wet state and clumps of lumps occur in the diaper. These cause the problem of sagging downward in the diaper when the baby continues to urinate. Since the integrity of the absorbent core (SAP and PULP mixture) of the sagging and/or clumped diaper is disrupted, leakage in the absorbent core layer is likely to cause rash problems.

It is known that there are studies regarding the subject matter of the invention in the prior art. US8568566B2 is one of the patents in the patent literature on this subject. According to the claim of this patent, with the channel technology, the urine is absorbed quickly and distributed smoothly to the front and back of the diaper, so that fluid accumulation is prevented in the middle (mesh) part of the absorbent core layer of the diaper and the diaper capacity is used effectively. According to this patent, the absorbent core layer of the diaper is obtained from the dual drum system. According to this system, SAP is fed into the first air/vacuum-proof drum with channels/gaps on the particles. SAP particles are placed onto these channels with the effect of the vacuum applied. Hot melt adhesive is applied onto a non-woven fabric surface and fed into a second drum. At the intersection of the first and second drums, SAP particles coming out of the channels in the first drum adhere to the adhesive applied to the non-woven fabric surface. During holding, SAP positioning is fixed on non-woven fabric in the form of a channel with the effect of the channels in the first drum. Hot melt adhesive is applied to this compound coming out of the intersection of the drums, and the second non-woven layer is adhered thereon and the C-shaped absorbent area (absorbent core) structure is obtained.

Another study is US patent publication no. US20150073366A1 in the patent literature. According to the claim of this patent publication, a structure with one or more channels is formed in the vertical plane in the absorbent core layer of the diaper containing approximately 80% SAP, thereby ensuring the presence of effective fluid diffusion and distribution throughout the diaper. The channels consist of gaps with no SAP. The absorption and distribution layer ADL (Acquisition and Distribution Layer) and similarly other intermediate layers between the absorbent core layer and the upper layer (the top layer of the diaper that touches the baby's skin) are not found in the areas where the channels are located. It also claims that there may also be shorter small channels in the front and back regions of the diaper.

The production of the aforementioned and commonly used diapers with one or more channels causes the absorbent area layer containing a high amount of SAP to swell when it encounters urine, causing this structure to harden suddenly and this makes it difficult for the diaper to adapt to the baby's body. In addition, due to the space allocated to the channels in the absorbent layer, the usage capacity of the diaper decreases due to the decrease in the amount of absorbent material and this leads to leakage complaints. When the use of the capacity of the channeled absorbent area exceeds 50%, the absorbent layer gains a hard touch with the effect of the swollen SAP particles, this may make it difficult for the diaper to sit on the baby anatomically and cause it to be uncomfortable. There has not been found a technology of baby diaper systems, which has a high absorption capacity and anatomical compatibility with fast absorption of body waste being ensured, and does not cause sagging during the baby’s use in absorbent hygienic articles with an absorbent core layer containing a SAP & PULP mixture.

Objective of the Invention

The present invention has been developed in a way to eliminate the above mentioned disadvantages. The present invention provides a homogeneous distribution of the SAP (super absorbent polymer) and/or the pulp materials that make up the absorbent core layer in absorbent hygienic products. The invention relates to a new pressing method (mechanical, ultrasonic, thermal, etc.) that increases the performance of absorbent hygienic products and the absorbent core layer obtained by this printing method.

The object of the present invention is that the fluid coming onto and accumulates in the middle area of the said absorbent core layer is compressed and thereby smoothly distributed onto the front and back parts thereof by the newly developed pressing method and the absorbent core layer obtained by this method.

A further object of the present invention is to prevent any tears and ruptures in the absorbent core layer, which may occur due to the weight of the accumulated fluid, by preventing the accumulation of fluid coming into the said absorbent core layer.

A further object of the invention is to prevent accumulation of the fluid coming to the said absorbent core layer in the middle (mesh) part of the diaper and to thereby ensure the integrity of the absorbent core layer even when it is wet, thanks to the pressing method developed and the absorbent core layer obtained by this method.

A further object of the present invention is to increase the product performance and the duration of product use by conveying the fluid coming into the absorbent core layer to all regions in the absorbent core layer, thanks to the pressing method developed and the absorbent core layer obtained by this method.

Brief Description of the Drawings

Figure 1 : Perspective view of the drum.

Figure 2: Perspective view of the pressing system.

Figure 3: Perspective view of the pressing roller and the compressing roller in operation.

Figure 4: Top view of the absorbent core layer on which pressing is applied.

Figure 5: Top view of the absorbent core layer, on which pressing is applied, in contact with the ADL layer.

Figures 6, 7, 8, 9, 10: Different mold form applications of the absorbent core layer on which pressing is applied. Reference Numbers

A. Pressing System

10. Forming roller

11. Mold form

12. Compressing roller y. The direction of rotation of the forming roller z. The direction of rotation of the compressing roller w. Production line flow direction of the absorbent core layer

B. Drum

X. Drum Rotation Direction 20. Drum Mold

30. Absorbent Core Layer

31. Topsheet

32. Backsheet

33. Absorption and Distribution Layer (ADL) 34. SAP (Super Absorbent Polymer)

35. PULP

36. SAP feeding chamber

37. PULP feeding chamber

Detailed Description of the Invention In a diaper production line, the raw materials of SAP (super absorbent polymer) (34) and/or PULP (pulp) (35) contained in the absorbent core layer (30) are transferred to a structure resembling a round wheel called drum (B) and then mixed (Figure 1).

As seen in Figure 1 , there are more than one drum molds (20) on the drum (B). Each drum mold (20) alone carries a mixture of SAP and/or PULP (34), (35) forming the absorbent core layer (30) of one diaper.

SAP and/or PULP (34, 35) are fed into the drum (B) from separate places. Said SAP and PULP (34, 35) are filled into the drum mold (20) with vacuum. Meanwhile, a predetermined ratio of SAP and pulp (34, 35) is mixed to form the absorbent core layer (30). The vacuum values in the drum molds (20) on the drum (B) that make rotational movement (whose rotation direction is (x)) vary according to the positions of the said drum molds (20). In the applications of the commonly used technique, the mixture of SAP and pulp (34, 35) is expected to be homogeneous and to be fed to the drum mold (20) at the same density in every region of the said drum mold (20).

The absorbent core layer (30) is formed by covering the periphery of the SAP and pulp (34, 35) mixture with a non-woven fabric. Said absorbent core layer (30) is in long and continuous form that can move along the line and absorbent core layers (30) are formed in desired sizes by cutting.

The working principle of the drum (B) used in forming the absorbent core layer (30) is as follows;

- While the SAP (34) material is poured from the SAP feeding chamber (36) in the upper part of the drum (B), the PULP (35) material is poured into the drum mold (20) at the same time so that the desired mixing ratio is obtained from the PULP feeding chamber (37) (Figure-1).

- Preferably, a high vacuum is created for the drum mold (20) to be filled properly and completely.

- As the drum (B) rotates (in the direction of rotation (X) direction) as shown in Figure-1 , the drum molds (20) thereon move on the drum diameter axis from top to bottom and from bottom to top. - When the drum mold (20) reaches the lowest region, the vacuum value here is minimized and the mixture of SAP and PULP (34, 35) in the drum mold (20) is left on the non-woven fabric surface which creates and surrounds the absorbent core layer (30) and to which special absorbent core adhesive has been applied. The drum mold (20), which is then emptied, moves upwards again to take the mixture of SAP and PULP (34, 35) materials and this cycle continues as long as the process runs.

- In this way, the absorbent core layer (30) is formed, which is covered with a non-woven fabric at the bottom and top, and contains a mixture of SAP and PULP (34, 35) material, which are bonded to each other with special absorbent core adhesive.

- The pressing method is applied to this absorbent core (30) layer produced by means of the pressing system (A).

The pressing system (A) consists of forming roller (10) having a mold form (11) thereon and making a rotational movement in the direction (y) (the rotational direction of the forming roller) and compressing rollers (12) rotating in the direction (z) (in the direction of rotation of the compressing roller). The pressing system (A) can be subsequently integrated into the existing production line.

Although the mechanical pressing system (A) is herein given as an example in applying the pressing method, said pressing method can be applied onto the absorbent core layer (30) also by ultrasonic, thermal etc. pressing systems. In the pressing method, hot or cold press can be applied for better retention of the pressing on the absorbent core layer (30).

The preferred mechanical working principle of the pressing system (A) that enables the pressing method to be applied to the absorbent core layer (20) is as follows:

- After the absorbent core layer (30) is formed, it is sent to the pressing system (A) integrated into the production line moving in the direction (w) (production line flow direction of the absorbent core layer) (Figure 3). - The absorbent core layer (30) is passed between the forming roller (10) having the mold form (11) and the compressing roller (12) in the pressing system (A), wherein the absorbent core layer (30) is compressed to take the shape on the mold form (11 ) (Figure 2, 3).

- The absorbent core layer (30) compressed according to the shape of the mold form (11) by means of the pressing method, which here applied as a mechanical pressing system (A), continues in the production line and is sent to other production processes.

Although the shape on the mold form (11) is given as a diamond pattern in this example, it can be in many different shapes as shown in Figures 6, 7, 8, 9, 10. Although the pressing method is applied along the length of the absorbent core layer (30) (L), this pressing method can alternatively be applied to the back face and/or front face of the absorbent core layer (30) as well as can be applied entirely or regionally on the absorbent core layer (30). This pressing method can also be applied to the topsheet (31) of the diaper that touches the skin first (in such a way that the topsheet material remains on the top), after the absorbent core layer (30) is connected with ADL (33) as seen in Figure 5.

Another alternative of the invention is that this pressing method can be applied externally, after the absorbent core layer (30) is combined with the backsheet (32) material, which is the outermost layer of the diaper.

As a result, the integrity of the absorbent core layer (30) consisting of SAP and/or PULP (34, 35) materials mixed in desired proportions is protected by the developed pressing method, whereby the hygienic absorbent articles having the incoming fluid homogeneously distributed to the front and back parts, having no sagging or clumping, having high absorbency capacity, and being anatomically fitting have been made.