A multilayer female fastener in diapers and production method thereof

Abstract

The invention relates to a method for the production of a front part (a female fastener) used for connecting the front and back parts of diapers and, owing to the configurations it contains, eliminates the need for use of glue and consequently the application of gluing-curing processes, and to a front part obtained by this method.

Description

[0001] A MULTILAYER FEMALE FASTENER IN DIAPERS AND PRODUCTION METHOD THEREOF

[0002] TECHNICAL FIELD

[0003] The invention relates to a method for the production of a front part (a female fastener) used for connecting the front and back parts of diapers and, owing to the configurations it contains, eliminates the need for use of glue and consequently the application of gluingcuring processes, and to a front part obtained by this method.

[0004] PRIOR ART

[0005] One of the elements in baby diapers that helps to secure and close the diaper by wrapping around the waist of the babies is the front part (known as the frontal tape in the art). The front part ensures that the diaper remains securely in place and facilitates diaper change by opening and closing easily. During use, it wraps around waist of the baby and prevents the diaper from falling and slipping.

[0006] The front part can be manufactured especially from nonwoven, woven or knitted structures, depending on the structure of the product to be produced and the desired functions. The front parts obtained from these fabric types have advantages and shortcomings against each other.

[0007] The use of knitted structures in the manufacture of these front parts is known to be useful for obtaining an elastic and flexible front part structure. This feature can help the baby move freely and better adapt the diaper to the body shape. Also, knitted structures are usually soft and breathable, making it possible to design products that are more comfortable for the baby's skin.

[0008] In the present art, the manufacture of the front parts in baby diapers is carried out by combining a film preferably made of medium-density polyethylene material or polypropylene material and a knitted structure by means of glue. After the gluing process is carried out, curing processes are carried out so that the final product can have physical and chemical stability. Curing processes in the present art are carried out for a period of 1 to 3 days at previously determined temperature and humidity values.

[0009] Gluing processes used to combine film and knitted fabrics in the manufacture of the front part can create technical disadvantages such as the formation of insufficient adhesion, chemical stability problems of the chemicals in the glue, the formation of unsuitable adhesion forms and additional costs, and the lack of sensitivity to the environment. In addition, there are technical disadvantages such as carrying out unsuitable curing processes, additional costs, and time losses due to also carrying out curing processes after the gluing process.

[0010] Due to the technical problems mentioned, it has become a necessity for the relevant technical field to introduce a production method in which the need for the application of gluing and curing processes in manufacturing the front part is eliminated.

[0011] SUMMARY OF THE INVENTION

[0012] In the relevant technical field, the use of knitted structures as raw materials in the manufacture of the front parts of diapers is becoming widespread due to their unique technical solutions and advantages. In such manufacture of the front parts, it is necessary to carry out gluing and curing processes in order to combine at least one polymer-based film layer and at least one knitted structure. In order to eliminate the technical problems created by these process steps, experts in the relevant technical field carry out research and development activities.

[0013] The inventors of the present invention aim to introduce a method for manufacturing the front part which does not require gluing and consequently curing processes, in order to eliminate these technical problems in the relevant technical field and to provide additional technical solutions and advantages to the relevant technical field.

[0014] In addition to the technical solutions and advantages mentioned, the present invention introduces a method for manufacturing the front part, in which the production process durations are reduced. By reducing the duration of the production processes, it is also possible to reduce the costs of the production processes. In another aspect, the present invention introduces a front part that contains as raw materials the materials that eliminate the requirement for gluing and curing processes for its manufacture.

[0015] Glue, as is known, is a chemical composition. By not using said glue as a raw material, the use of less chemicals for the production of the front part will provide a technical solution and advantage for the environment-human health.

[0016] BRIEF DESCRIPTION OF DRAWINGS

[0017] Fig. 1 shows a representative view of the baby diaper showing the front part and adhesive tapes (hook-and-loop fastener or male fastening-closing element).

[0018] Fig. 2 shows a representative view of the front part of the invention together with its elements.

[0019] BRIEF DESCRIPTION OF REFERENCES

[0020] 10 Baby Diaper

[0021] 11 Front Part

[0022] 111 Knitted Structure

[0023] 1111 Polyester yarn

[0024] 1112 Polyolefin Yarn

[0025] 112 Film Layer

[0026] 113 Bonding Interface

[0027] 12 Hook-and-loop fastener

[0028] DETAILED DESCRIPTION OF THE INVENTION

[0029] In this detailed description, the subject of the invention relates to a method for manufacturing a front part suitable for use in diapers, and is described by way of nonlimiting examples only for a better understanding of the subject matter. The representative view of the baby diaper of the invention is shown in Fig. 1 . This view is a representative view, and the scope of protection of the invention is not limited to the design of the baby diaper shown in the drawing. The aim in this drawing is to show the position of the front part and adhesive tapes.

[0030] The front part is also known as the frontal tape in the art. The function of this element is to provide the connection between the front and back parts of the baby diapers. The front part ensures that the diaper remains securely in place and facilitates diaper change by opening and closing easily. During use, it wraps around waist of the baby and prevents the diaper from falling and slipping. In order to achieve this, the hook-and-loop fasteners are contacted to the front part element, as shown in Fig. 1 .

[0031] The front part of the present invention contains at least one knitted structure and at least one film layer. The resulting knitted structure must be reinforced with a film layer. The film layer aligns with the upper neighboring part of the baby diaper, forming a base for the knitted structure. In this way, it provides waterproofing, durability, flexibility for the front part, and adhesion surface for adhesives. It is shown as representation in Fig. 2.

[0032] In this invention, the knitted structure is preferably manufactured with an S-type knitted fabric style. Technical information on the manufacture of S-type knitted fabric is available in the relevant technical field.

[0033] In a preferred embodiment, a knitted weaving structure is manufactured with knitting processes in three axes, the solutions and advantages of which are known in the art. With the S-type knitted structure, knitting in 3 axes is meant and owing to this structure, it is ensured that the hook-and-loop fastener, which is the male fastener, is strongly attached to the front part and optimum working performance is obtained with repeated opening and closing action. Accordingly, it is possible to use at least three yarns as raw materials to obtain a three-dimensional knitted structure.

[0034] The main innovative technical solution and advantage that the present invention wants to introduce to the relevant technical field is the elimination of the technical problems in combining at least one knitted structure and at least polymer-containing film in manufacturing the front part by gluing and curing processes. In the present art, the necessity of applying gluing and curing processes to combine the knitted structure and polymer-containing film layer within the front part is due to including materials with very different chemical characterizations as raw materials in the knitted structure and film layer. In fact, while polyester yarns, polypropylene and polyamide yarns are generally used as raw materials in manufacturing knitted structures, medium density polyethylene, polypropylene or similar chemicals are commonly used as raw materials in the production of the film layer. Since particularly polyester and polyamide yarns in the knitted structure do not have similar chemical characterizations with the film layer made of polyethylene or polypropylene, it is necessary to use adhesives for their combination. Adhesive (e.g. polyurethane-based solvent-free lamination glue) allows this knitted structure and film layer with different chemical characterizations to be physically and chemically stable together in the front part.

[0035] In order to eliminate the aforementioned technical problem, the inventors of the present invention propose to use materials with similar chemical characterization as raw materials in manufacturing knitted structures and film layers. Firstly, the choice of yarns to be used for manufacturing knitted structures is critical. Accordingly, the inventors of the present invention use at least one polyolefin yarn and at least one polyester yarn as raw materials for manufacturing knitted structures.

[0036] As mentioned earlier, this invention involves the use of materials with similar chemical characterizations as raw materials in manufacturing film layers and knitted structures. In this way, a bonding interface is formed between the knitted structure and the film layer in the front part to be obtained. Said bonding interface is formed between the film layer raw material polyolefin material and the polyolefin-based yarns in the knitted structure which have similar chemical characterizations. The bonding interface provides a form for the front part in the same way as the adhesive obtained by gluing processes provides the physical and chemical stability between the film layer and the knitted structure.

[0037] In the preferred embodiment, the knitted structure comprises at least one polyester yarn and at least one polyolefin-based yarn as raw materials, while the film layer comprises at least one polyolefin-based material as raw material.

[0038] In this invention, at least one of the polyethylene and / or polypropylene yarns is preferred as the raw material of polyolefin-based yarn in manufacturing knitted structures. Similarly, at least one of the polyethylene and / or polypropylene materials from the polyolefin group is preferred as raw material for producing the film layer. In this way, it is ensured that the yarns used as raw materials in the film layer and knitted structure have similar chemical characterizations, and the need for applications that will provide additional stability (gluing and curing, etc.) will be eliminated with the strong bond interaction obtained.

[0039] In the preferred embodiment, polyester and polypropylene yarns are used as yarn raw materials in manufacturing knitted structures, while polypropylene material is used as the raw material of the film layer.

[0040] In a preferred embodiment, polyethylene terephthalate yarn is used as polyester yarn in manufacturing knitted structures.

[0041] In another preferred embodiment, the knitted structure is obtained by three-dimensional knitting processes. Accordingly, the knitted structure contains three yarns. At least one of these yarns is polypropylene yarn, and the film raw material also consists of polypropylene material.

[0042] In this invention, the technical teaching is the use of film layer and knitted structure containing materials with similar chemical characterization properties as raw materials in manufacturing the front part. In accordance with this technical teaching, polyamide yarn and polyamide-based film layer can also be used as raw materials in manufacturing the front part. However, mostly polyolefin-based materials are preferred as raw materials due to the technical difficulties of using polyamide materials as raw materials in lamination coating processes for obtaining film layers. However, the skilled person in the art will be able to easily obtain the front part in which polyamide yarn and polyamide film layer are used as raw materials with the teachings characterized in the present invention.

[0043] With the technical teachings subject to the invention, the necessity of applying gluing and curing processes for manufacturing the front part containing at least one knitted structure and at least one film layer is eliminated. The process steps applied for manufacturing the front part as characterized in the invention are detailed in the following lines. Obtaining a knitted structure

[0044] In order to provide the innovative aspect of the invention, the material selection of the yarns to be used particularly in obtaining the knitted structure is critical. In order to ensure the similarity of chemical characterization between the knitted structure and the film layer, the material from which the film layer will be produced and at least one yarn in the knitted structure must have similar chemical characterizations.

[0045] In the preferred embodiment of the invention, the knitted structure is manufactured from at least two yarns. At least one of said yarns is the yarn obtained from the polyolefin material group.

[0046] In a preferred embodiment, at least one of the polyolefin yarns used in manufacturing knitted structures is polypropylene yarn.

[0047] In a preferred embodiment, at least one of the yarns used in manufacturing knitted structures is polyester yarn.

[0048] In a preferred embodiment, polyethylene terephthalate (can be abbreviated as PET) yarn is used as polyester yarn used in manufacturing knitted structures.

[0049] In the most preferred embodiment, the knitted structure is obtained by three-axis knitting processes; for this reason, it contains three yarns as raw materials. While one of these three yarns is polypropylene (can be abbreviated as PP) yarn; the other two yarns are polyester (can be abbreviated as PES) yarn.

[0050] In order for the knitted structure to be obtained to have the targeted mechanical properties, the denier values of the yarn raw materials used in its manufacture are crucial. As is known in the art, the "denier" unit is the unit of measurement that expresses the length of the yarn weighing one gram.

[0051] Accordingly, in obtaining a knitted structure, polyolefin-based yarns should have a higher denier value compared to polyester yarns. The denier value of the polyolefin yarn used in obtaining the knitted structure in this invention is a value in the range of 30 to 60.

[0052] The denier value of the polyester yarn used in obtaining the knitted structure in this invention is a value in the range of 10 to 50.

[0053] In the art, the term "gsm" is an abbreviation of grams per square meter. This unit of measurement can be used to evaluate whether fabrics are light or heavy.

[0054] The knitted structure obtained by the composition of the raw materials configured in this invention is at a value between 15 to 30 gsm in a preferred embodiment. In a preferred embodiment, this value is a value between 18 to 25 gsm. The mentioned "gsm" values are a parameter that determines the shear stress adhesion and peel force values expected from the final product front part with hook-and-loop fastener (male fastener). In order to obtain the mentioned parameters, it is critical that the gsm values of the knitted structure are at the specified values.

[0055] Performing the lamination coating process

[0056] In this process step, the choice of raw materials for manufacturing film layer is critical. The film layer contains at least one polyolefin material as raw material.

[0057] In this process step, the polyolefin material is coated onto the knitted structure surface, which was obtained independently in the previous process step, so that thermal fusion occurs between the raw materials. This coating process is referred to as the lamination coating process. With the application of the lamination coating process, a bonding interface is formed between the knitted structure and the film layer after the polyolefin material is coated onto the knitted structure surface at the specified temperatures and flow rate. Said bonding interface is formed between the polyolefin material and at least one polyolefin yarn within the knitted structure. The bonding interface is shown as representation in Fig. 2.

[0058] The bonding interface is achieved by the chemical interaction between the polyolefin yarn and the polyolefin material. In this way, physical and chemical stability can be achieved between the knitted structure and the film layer. For the mentioned lamination coating process, the coating temperature of the polyolefin material towards the knitted structure is an important parameter. In a preferred embodiment, the coating temperature from the screw feed zone in the extruder where the coating process is performed to the zone where the polyolefin material leaves the extruder head is a temperature in the range of 210 °C to 280 °C. These temperature values are the parameters determined to obtain homogeneous distribution of the polyolefin material on the base to be coated at the optimum flow rate in the coating extruder.

[0059] Another important parameter is the determination of the flow rate of the polyolefin material for lamination coating processes on the surface of the knitted structure. The melt flow index (also known as MFI) in lamination coating processes of the mentioned polyolefin material is a value from 7 g / 10 min to 25 g / 10 depending on the characterized values of gsm and coating temperature, the flow rate in lamination coating processes of the polyolefin material is a value from 15 g / 10 min to 24 g / 10 depending on the characterized values of gsm and coating temperature.

[0060] After the coating process step is completed, the knitted structure and film layer are subjected to the pressing process at the specified values. Known means in the art can be used for the pressing process. The pressure / compression value applied here is a value between 2 to 5 bar. The preferred pressure value is a value of 3 or 4 bar. With these values, it can be ensured that the flow / coating product polyolefin material is fixed on the knitted structure to create a homogeneous, flat film layer.

[0061] In a preferred embodiment, at least one of the polyethylene and / or polypropylene material is used as the raw material of the film layer.

[0062] In another preferred embodiment, a mixture of at least one of the polyethylene and / or polypropylene group with at least one of the ethylene acrylic ester and / or maleic anhydride group is used as the raw material of the film layer.

[0063] In another preferred embodiment, polyethylene-polypropylene-ethylene acrylic estermaleic anhydride mixture can be used as a film layer raw material. The film layer applied by transfer processes has a value between 10 to 30 gsm in the front part. In this preferred embodiment, the film layer is at a value between 12 to 21 gsm in the front part. Said gsm values are the values developed and determined for obtaining the strength values expected from the final product and other targeted technical properties.

[0064] Performing slicing processes

[0065] As a result of the previous processes, the front part configured with polyolefin materials is subjected to slicing processes with the methods and tools known in the art in order to obtain the targeted dimensions to be mounted on baby diapers.

[0066] In the most preferred embodiment, the front parts containing s-type knitted fabric and film and configured with the use of polyolefin material as raw material have a value between 25 to 50 gsm.

[0067] The bonding interface formed with the production method characterized in the present invention and the use of raw materials eliminates the need to perform any gluing and curing processes for manufacturing the front part.

[0068] In addition to the aforementioned technical solutions and advantages, the present invention also introduces a method for producing front parts in which the production process durations are reduced. By reducing the duration of the production processes, it is also possible to reduce the costs of the production processes.

[0069] Glue, as is known, is a chemical composition, by not using said glue as a raw material, the use of less chemicals for the production of the front part will provide a technical solution and advantage for the environment-human health.

[0070] The inventors of the present invention have also performed certain tests on the obtained front part. In these tests, the knitted structure is obtained by the S-type knitting style, in which two yarns are polyester and one yarn is polypropylene yarn. The film layer consists of polypropylene material. The test results of the front part obtained in this way are detailed in the following lines.

[0071] Table 1. Comparison of longitudinal tensile and elongation at break, transverse tensile force and elongation strength values between the front part of the invention and the front part in the present art.

[0072] Table 2. Comparison of T -peel and T -shear values between the front part of the invention and the front part in the present art.

[0073] When the strength values shared in Table 1 and Table 2 were examined, it was determined that the strength values between the front part of the present invention and the front part in the present art were close to each other. In this way, even in cases where gluing and curing processes are not applied as mentioned in the present invention, it is possible to manufacture the front part with the values in the present art.

[0074] The scope of protection of the invention is specified in the appended claims and cannot be limited to what is described for illustrative purposes in this detailed description. It is clear that a person skilled in the art can produce similar embodiments in the light of what is explained above, without deviating from the main theme of the invention.

Claims

CLAIMS1 . A method for the production of a front part providing the connection between the front and back parts of diapers, characterized in that it comprises the process steps of;- obtaining a knitted structure as a result of performing S-type knitting type knitting processes with at least one polyester yarn and at least one polyolefin yarn,- coating at least one polyolefin-based material with similar chemical characterization to said knitted structure to form a film layer on at least one side of the knitted structure,- obtaining a physically and chemically stable front part as a result of the formation of a bonding interface by achieving thermal fusion between at least one polyolefin yarn in the knitted structure and the polyolefin-based material in the coated film layer.

2. A method according to claim 1 , characterized in that said polyolefin yarn has a denier value in the range of 30 to 60.

3. A method according to one of the preceding claims, characterized in that said polyester yarn has a denier value in the range of 10 to 50.

4. A method according to one of the preceding claims, characterized in that polyolefin yarn is at least one of the polyethylene and / or polypropylene yarn group.

5. A method according to claim 4, characterized in that the polyolefin yarn is a polypropylene yarn.

6. A method according to one of the preceding claims, characterized in that the knitted structure obtained has a value in the range of 15 to 30 gsm.

7. A method according to one of the preceding claims, characterized in that the coating temperature of the polyolefin-based material to which said lamination coating process is applied has a value between 210 °C to 280 °C.

8. A method according to one of the preceding claims, characterized in that in the lamination coating process, the melt flow index of the polyolefin-based material is at a value between 7 g / 10 mins to 25 g / 10 mins under the condition of 230 C / 2.16 kg.

9. A method according to one of the preceding claims, characterized in that in the lamination coating process, pressing processes are performed after the transfer of polyolefin material to knitted fabrics.

10. A method according to claim 8, characterized in that said pressing process is performed at a pressure at a value in the range of 2 to 5 bar.11 . A method according to one of the preceding claims, characterized in that the polyolefin material used in the lamination coating process is at least one of polyethylene and / or polypropylene material.

12. A method according to claim 11 , characterized in that the polyolefin material is polypropylene material.

13. A method according to one of the preceding claims, characterized in that the film layer obtained by applying the lamination coating process has a value in the range of 10 to 30 gsm.

14. A method according to one of the preceding claims, characterized in that the front portion obtained after transferring the film layer to the knitted fabric by coating / flow method is subjected to slicing processes.

15. A front part providing the connection between the front and back parts of baby diapers, characterized in that it contains a knitted structure and a film layer,- said knitted fabric contains at least one polyester yarn and at least one polyolefin yarn,- said film layer contains at least one polyolefin-based material that provides the bonding interface by having similar chemical characterization on at least one side of the knitted fabric.

16. A front part according to claim 15, characterized in that said knitted structure contains at least one of polyethylene and / or polypropylene yarn group as a polyolefin yarn.

17. A front part according to claim 16, characterized in that the knitted structure contains at least one polypropylene yarn as a polyolefin yarn.

18. A front part according to one of claims 15-17, characterized in that the knitted structure contained therein has a value in the range of 15 to 30 gsm.

19. A front part according to one of claims 15-18, characterized in that the polyolefin- based material contained therein is at least one of polyethylene and / or polypropylene material.

20. A front part according to claim 19, characterized in that the polyolefin-based material is polypropylene material.

21. A front part according to one of claims 15-20, characterized in that the film layer contained therein has a value in the range of 10 to 30 gsm.

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