Method Development for Producing Napkins and Femcare Absorbent Cores by Using an Airlaid Former

DEGREE PROJECT IN CHEMICAL SCIENCE AND ENGINEERING, SECOND CYCLE, 30 CREDITS STOCKHOLM, SWEDEN 2020

Method development for producing napkins and femcare absorbent cores by using an airlaid former

LINNEA KILEGRAN

KTH ROYAL INSTITUTE OF TECHNOLOGY SCHOOL OF ENGINEERING SCIENCES IN CHEMISTRY, BIOTECHNOLOGY AND HEALTH

Abstract

Fluff pulp is a renewable material consisting of pure cellulose fibers which are obtained during pulping. These fibers are commonly used to form Airlaid-nonwoven products such as napkins and wipes. Fluff pulp is also used in absorbent cores in femcare products, incontinence products and diapers. Some of these absorbent core structures (especially in ultrathin pads) are produced through airlaid. Airlaid is a manufacturing technique which forms a randomly oriented fiber structure by using an applied suction.

This degree project aimed at developing methods for producing napkins and femcare absorbent cores on a laboratory scale by using an airlaid former. Important properties such as grammage, thickness, density, bending length and liquid spreading were therefore measured on commercial napkins and femcare absorbent cores. Other analyses which were performed include tensile testing and SEM. Findings from these analyses were then used as a target reference during the method development.

Two methods were developed; one for producing a napkin structure and one for producing a femcare absorbent core structure. The different manufacturing steps included fiber defiberization, sample formation, pressing, embossing, latex spraying and curing. Napkin structures and femcare absorbent core structures were produced by using the developed methods, and their properties were analyzed and compared with the commercial products.

Analysis showed that the developed methods generated structures with grammages that corresponded well with the grammages in the commercial products. However, both developed structures were thicker and had lower density than the commercial products. This decreased density probably influenced the results in other analyses performed in this project. The developed napkin structure had a shorter bending length compared to the commercial napkins and the developed femcare structure had a better absorption capacity compared to the commercial femcare absorbent cores.

Both developed structures obtained nice surface finish which corresponded well with the surface finish in the commercial products. However, SEM analysis indicated that no latex managed to reach the center in the developed structures.

Keywords: Fluff pulp, nonwoven, airlaid, thermofiber, superabsorbent polymer, absorbent core, napkin, femcare

Sammanfattning

Fluffmassa är ett förnybart material bestående av cellulosafiber som utvinns under massakokning. Dessa fiber används för att tillverka olika absorberande produkter som till exempel servetter. Fluffmassa används även för att tillverka absorptionskärnor i damhygienprodukter, inkontinensprodukter och blöjor. Vissa av dessa absorptionskärnor (speciellt i ultratunna bindor) tillverkas med airlaid. Airlaid är en tillverkingsteknik som ger fiberstrukturer med slumpmässig orientering genom att applicera ett undertryck.

Syftet med detta examensarbete var att utveckla metoder för att tillverka servetter och absorptionskärnor till damhygienprodukter i laboratoriemiljö genom att använda en airlaid maskin i laboratorieskala. Detta utfördes genom att analysera viktiga egenskaper som exempelvis ytvikt, tjocklek, densitet, böjlängd och förmågan att absorbera vätska i kommersiella servetter och absorptionskärnor inom damhygien. Även dragprov och SEM- analys utfördes. Resultatet från dessa analyser användes som ett riktvärde under metodutvecklingen.

Två metoder utvecklades - en för att tillverka en servettstruktur och en för att tillverka en absorptionskärna för damhygien. De olika tillverkningsstegen inkluderar defibrering, formering, pressning, prägling, latexsprayning samt härdning. Båda strukturerna tillverkades, och dess egenskaper analyserades och jämfördes med de kommersiella produkterna.

Analyserna visade att de utvecklade metoderna genererade struktuer vars ytvikt stämde väl överrens med de kommersialla produkterna. Strukturerna var dock tjockare och hade en lägre densitet än de kommmersiella produkterna. Den minskade densiteten påverkade förmodligen resultatet från de andra analyserna som utfördes i detta projekt. Servettstrukturen hade en lägre böjlängd än de kommersiella servetterna och damhygienstrukturen hade bättre absorption än de kommersiella produkterna.

Båda strukturerna hade en ytfinish som överensstämmde väl med de kommersiella produkterna. Dock visade SEM-analysen att latex saknades i mitten av de båda tillverkade strukturerna.

Nyckelord: Fuffmassa, nonwoven, airlaid, termofiber, superabsorbent, absorptionskärna, servett, damhygien

Table of Content Abstract ...... i Sammanfattning ...... ii List of abbreviations ...... v 1. Introduction ...... 1 1.1 Aim ...... 1 1.2 Objectives ...... 1 2. Background ...... 2 2.1 Nonwoven...... 2 2.2 Airlaid ...... 2 2.2.1 Fluff pulp defiberizing ...... 3 2.2.2 Web formation ...... 3 2.2.3 Web bonding ...... 3 2.3 Fluff pulp ...... 4 2.4 Bicomponent fibers/thermofiber ...... 5 2.5 Superabsorbent polymer (SAP) ...... 6 2.6 Absorbent hygiene products and their layers...... 7 2.6.1 Top layer ...... 8 2.6.2 Acquisition and distribution layer ...... 8 2.6.3 Absorbent core ...... 8 2.6.4 Back sheet ...... 8 2.7 Airlaid napkin structure ...... 8 3. Experimental part ...... 9 3.1 Materials ...... 9 3.2 Selection of commercial products for analysis ...... 10 3.3 Analysis ...... 10 3.3.1 Grammage ...... 10 3.3.2 Thickness and density ...... 10 3.3.3 Bending length ...... 11 3.3.4 Liquid spread and absorption capacity ...... 11 3.3.5 Scanning Electron Microscope (SEM) ...... 11 3.3.6 Tensile testing ...... 12 3.4 Method development for producing airlaid structures ...... 12 4. Results and discussion ...... 13 4.1 Selected commercial products...... 13 4.2 Napkin structures ...... 14

iii

4.2.1 Developed napkin process ...... 14 4.2.2 Developed napkin structure ...... 14 4.2.3 Analysis of napkin structures ...... 17 4.3 Femcare absorbent core structures ...... 24 4.3.1 Developed femcare absorbent core process ...... 24 4.3.2 Developed femcare absorbent core structure ...... 25 4.3.3 Analysis of femcare absorbent core structures ...... 26 5. Conclusion ...... 32 6. Future recommendations ...... 33 7. Acknowledgements ...... 34 8. References ...... 35 Appendix ...... 37

List of abbreviations

Bico – Bicomponent fiber Femcare – Feminine care SAP – Superabsorbent polymer VAE – Vinyl acetate ethylene

1. Introduction Fluff pulp is an interesting material since it is completely biodegradable, renewable and cost effective. This makes it one of the most sustainable materials on earth and an excellent option in many products [1]. It is for example used in absorbent hygiene products within feminine care (femcare), baby diapers and incontinence products. Other areas include medical applications and different airlaid structures such as napkins and wipes [2].

Fluff pulp was introduced in the 1920s and has increased in popularity ever since. 5.8 million tons were consumed globally in 2017, and an annual increase of 3.7% is expected until 2022 [1]. One of the leading fluff pulp producers in Europe is Stora Enso [3] who offers a broad range of grades to their customers specially designed to suit their customers´ need [2]. Stora Enso therefore finds it interesting to understand what impacts a certain modification of the fluff pulp has on final products. To test this, the company needs to develop methods for producing napkins and femcare absorbent cores on a laboratory scale. These methods can then be used in future projects to investigate how certain properties are affected by a specific modification.

1.1 Aim The aim of this degree project is to develop methods for producing napkins and absorbent cores in ultrathin femcare products on a laboratory scale by using an airlaid former. These methods will be used in future projects to understand what impact certain fluff pulp modifications has on an end-use product.

1.2 Objectives • Examine important properties in commercial airlaid products such as napkins and absorbent cores in femcare products.

• Develop methods for producing napkins and absorbent cores for ultrathin femcare products on a laboratory scale by using an airlaid former.

• Compare the developed napkin structure and the developed absorbent core structure with the commercial products.

2. Background

2.1 Nonwoven A nonwoven material is a randomly oriented fiber structure whose fibers are bonded together by either friction, cohesion or adhesion [4]. These fibers can be either natural or synthetic; some of the most commonly used fibers in a nonwoven material include cellulose, jute, flaw, wool, polyester, polyamide and rayon. Other less commonly used fibers in a nonwoven material are glass fiber, carbon fiber and nanofibers [5]. This broad range of different fibers generate nonwoven materials with completely different properties. Consequently, factors such as fiber length, fiber width, porosity and number of entanglements become key parameters to control during production [6].

Nonwoven materials are usually divided into different categories such as spunbund, airlaid, drylaid and wetlaid. All these nonwovens have the same four processing steps which include fiber selection, web formation, web bounding and finishing/converting. However, differences within each processing step generate properties suitable for different applications [3].

2.2 Airlaid Airlaid, or the airlaid pulping process, is one of the most commonly used nonwoven manufacturing techniques [3]. The process, which generates a randomly oriented fiber structure, uses air in order to form a web-like structure. Fibers are then pressed and bonded together by using different bonding techniques [7]. The airlaid process is commonly divided into three individual steps; fluff pulp defiberizing, web formation and web bonding [3]. Figure 1 shows an overview of the process.

Figure 1. Overview of an airlaid process from “The Future of Airlaid Nonwovens to 2022, P. Mango, Smithers and Pira, 2017” read from the right-hand side to the left-hand side. The process starts with the fluff pulp defiberizing followed by the formation step and the bonding step.

2.2.1 Fluff pulp defiberizing The cellulose fibers which are used in the airlaid process are commonly delivered from the pulp mill as compressed sheet in a roll. The sheets must therefore be separated into individual fibers to enable the processing steps which follows [6]. Fiber separation takes place in a process called fluff pulp defiberizing and is the first step in the airlaid process. This is commonly performed by using a hammermill where multiple rotating hammers tear the pulp apart [3]. A lot of energy is required to overcome the strength provided by the fibers [8]. The rotating hammers gradually transform the sheets into individual fibers or loose fiber entanglements known as fluff pulp. Fluff pulp is commonly used in absorbent hygiene products within femcare, incontinence and diapers. It is also used in different airlaid products such as napkins and wipes [9].

2.2.2 Web formation The second step in the airlaid process is called web formation. During web formation, fluff pulp is mixed with air and transferred to a moving belt or a “forming wire” by using an applied suction. This generates a randomly oriented structure with an extremely low density. A pressure is therefore applied to pack the fibers more closely and thus enable the bonding step which follows [7]. Web formation can also take place with addition of other components such as thermofibers [10] or superabsorbents [11].

2.2.3 Web bonding The last step in the airlaid process is called web bonding. This step binds the fibers together and is performed by using one of the available bonding techniques [3].

2.2.3.1 Latex bonding Latex bonding, LBAL is the most commonly used bonding technique. During LBAL, a “glue” or an adhesive such as a self-crosslinking copolymer is applied in order to bond the fibers together. One such example is vinyl acetate-ethylene, also referred to as VAE. Major strengths of using LBAL include the low raw material cost and the ease of adding different coloring. However, LBAL has limited ability to bind thicker products [3].

2.2.3.2 Thermal bonding Thermal bonding, TBAL is another bonding technique which uses heat to link the fibers. During TBAL, heat is applied until the fibers soften. The temperature is then reduced which causes the fibers to solidify and bond together. TBAL is inexpensive and generate structures with high qualities. However, the bonding technique has limited usage since it is only applicable on thermofibers. It also requires a careful temperature control since a too high temperature melts the fibers which destroys the airlaid structure [3].

2.2.3.3 Hydrogen bonding Hydrogen bonding, HBAL is another bonding technique which, according to litterture, use hydrogen bonds to link the fibers. However, this bonding technique most likely uses a combination of hydrogen bonds and Van der Waal interactions to link the fibers due to the formation of dipoles within the molecules. Even though each hydrogen bond is very weak, a strong bonding is still obtained since the total number of hydrogen bonding is enormous. HBAL has low processing costs and generates a material with a good wet strength. Drawbacks of using HBAL includes high temperature and high pressure which is required to facilitate the bonding [3].

2.2.3.4 Multiple bonding Multiple bonding, MBAL is the last bonding technique which is performed by combining at least two of the previously mentioned bonding techniques. Most MBALs includes a combination of LBAL and HBAL [3].

2.3 Fluff pulp Fluff pulp is a biodegradable material consisting of pure cellulose fibers which are obtained by pulping of different softwoods such as spruce or pine [12]. There are multiple contributing factors which explain why softwood fibers are considered a better raw material compared to hardwood fibers in many fluff pulp applications. Firstly, it is important to understand that softwood fibers and hardwood fibers have different fiber dimensions. While softwood fibers are approximately 3 mm in length and 30 µm in width, hardwood fibers are approximately 1 mm in length and 20 µm in width [13]. The differing fiber dimensions affect the fibers´ coarseness and the fibers´ ability to pack close. This in turn affects the absorption properties and generates different usage areas [1]. Softwood fibers also have a more uniform structure [13].

Fluff pulp usually benefits from certain modifications that enhance the properties of the product. One such example is addition of a debonder to prevent the formation of hydrogen bonding between the cellulose fibers. This reduces the energy consumption during defiberization. It also reduces the knot content which is preferable in products where fiber separation is important [14]. After the fluff pulp has experienced a certain modification, it is usually referred to as a certain treated grade. Figure 2 shows defiberized fluff pulp provided by Stora Enso.

Figure 2. Example of fiberized fluff pulp. Each cellulose fiber is approximately 2 mm x 30 µm.

Fluff pulp is used as a raw material in airlaid products such as napkins and wipes and in absorbent cores in femcare products, incontinence products and diapers [12]. Absorbent cores produced through airlaid usually contain additional materials such as bicomponent fibers [10] or superabsorbent polymers [11] to enhance the properties in the end product and to provide a better bonding.

2.4 Bicomponent fibers/thermofiber Bicomponent fiber, or bico, consist of two different thermoplastics which are extruded together in a fiber structure. This enables formation of fibers with a broad range of different properties and different cross sections. Depending on the appearance of the cross section, bicomponent fibers are divided into side-by-side, sheath-core, island-in-sea or segmented- pie-cross-section bicomponent fiber [15].

Surface-core bicomponent fibers are commonly added to hygiene absorbent cores to bind the structures. They are built up by a core of one polymer and are surrounded by an outer layer of another polymer [15]. Both these polymers contribute with different properties such as strength [16], reduced costs, stability and dyability [15]. Another benefit of these fibers is the possibility to combine two polymers with different melting temperatures. By using a polymer with a lower melting temperature in the surface and a polymer with a higher melting temperature in the core, one can use these differing melting temperatures to bind a nonwoven fiber structure. The curing temperature then needs to be adjusted to only melt the surface while the core stays intact. As the temperature is reduced, the surface polymer solidifies, and the structure is bonded together [15].

Bicomponent fibers are also referred to as thermofibers and the most common thermofiber consists of a combination of polyethylene and polypropylene [5]. However, other polymers such as polyethylene terephthalate, polylactic acid, polyurethane, polystyrene, polybutylene terephthalate, polyethylene naphtalate and Nylon 6.6 can be used as well [15]. Thermofibers are commonly added to absorbent hygiene products such as feminine pads to provide a better linking. They are usually found in thicker products since the largest drawback of using latex bonding is the inability to bind thicker products. Thermofibers can therefore be used as a complement to latex in order to provide a better bonding in a structure [3]. Figure 3 shows some PE/PP thermofibers.

Figure 3. PE/PP thermofibers.

2.5 Superabsorbent polymer (SAP) Superabsorbent polymers, or SAP, is another common addition to absorbent cores. A superabsorbent polymer can absorb several hundred times of water in relation to its own weight. SAP is an interesting addition in many absorbent hygiene products such as diapers, incontinence pads and femcare products [4]. However, it is important remember that body fluids such as blood and urine contain ions which binds to the hydrophilic groups in the polymer chains. This increases the debye screening length and hinders the water absorption which reduces the absorption capacity [17]. SAP also needs to maintain the absorbed liquid when it is exposed to a certain load [18], otherwise leakage could occur during wear.

One of the most commonly used superabsorbent polymer in absorbent hygiene products is sodium polyacrylate [19]. This is a crosslinked polymer whose repeating unit is illustrated in figure 4. Sodium polyacrylate is usually added to the fluff pulp as granules with a particle diameter of 400-800 µm [20].

Figure 4. Repeating unit in sodium polyacrylate.

Sodium polyacrylates has an extreme ability to absorb liquid that is related to the sodium carboxylate groups which are attached to the carbon main chain. As these groups meets water, sodium ions are detached which leaves the negatively charged carboxylic groups. The negative charge causes the polymer chains to unwind which allows the water absorption. A hydrogel with an extremely high molecular weight is formed due to the presence of crosslinks [19].

2.6 Absorbent hygiene products and their layers Absorbent hygiene products such as feminine pads, incontinence products and diapers have complex structures. All these products are built up by several layers where each layer is specially designed to fulfill specific requirements. All layers need to work together for the product to function. An absorbent hygiene product usually consists of four different layers which include a top layer, an acquisition and distribution layer, an absorbent core and a back sheet. The different layers are illustrated in Figure 5 [19].

Skin ------Top layer

Acquisition and distribution layer Absorbent hygiene product Absorbent core

Back sheet

Figure 5. The top layer, acquisition and distribution layer, absorbent core and the back sheet building up an absorbent hygiene product.

2.6.1 Top layer The top layer is the thin nonwoven layer located closest to the body in an absorbent hygiene product [19]. It usually consists of polyethylene or polypropylene fibers [21] held together in a porous structure. This allows the liquid to pass through the top layer and reach the other layers in the product where it is absorbed. It also prevents the fluid from having a prolonged skin contact which can cause irritation. Furthermore, a top layer also needs suitable wetting properties to prevent leakage [19].

2.6.2 Acquisition and distribution layer The next layer in an absorbent hygiene product is the acquisition and distribution layer. This sub-layer is used to distribute the fluid over a larger area to prevent the product from leakage. The layer also provides dryness to the skin by separating the wet pad from the top layer which contacts the skin [19].

2.6.3 Absorbent core The absorbent core is the heart of an absorbent hygiene product which main responsibility is to absorb the fluid. Large requirements are put on the absorbent core since it shall not absorb too slow or reach saturation since this would cause leakage [19]. Table 1 shows the average composition in a general femcare absorbent core produced through airlaid.

Table 1. Average composition for femcare absorbent cores produced through airlaid. Data is collected from “The Future of Airlaid Nonwoven, P. Mango, 2017”

Components Fluff pulp Bicomponent Superabsorb- Latex (if latex fibers ent polymer bonded) Femcare 65–80 wt% 7–15 wt% 20–40 wt% 4–6 wt% absorbent core

2.6.4 Back sheet The back sheet is a thin barrier at the bottom in an absorbent hygiene product. It usually consists of a polyethylene film that prevents leakage [21].

2.7 Airlaid napkin structure Airlaid structures such as napkins and wipes have a simpler structure compared to an absorbent hygiene product. These products only consist of a single layer of fluff pulp which is pressed and bonded together by using for example latex spraying [3].

3. Experimental part The experimental part was divided into four steps.

• Selection of commercial napkins and feminine hygiene products to investigate. The selected products were produced through airlaid.

• Analysis of the commercial products. Properties of interest were grammage, thickness, density, liquid spreading, bending length, composition and tensile testing.

• Method development for producing napkins and femcare absorbent cores in a laboratory scale by using an airlaid former. Average values from each analysis of the commercial products were used as the target during the method development.

• Production of napkins and femcare absorbent cores by using the developed methods. Analysis of the produced samples were thereafter performed.

3.1 Materials The following materials were used:

• Treated fluff pulp from Skutskär Mill, Stora Enso • 3 mm polyethylene/polypropylene thermofiber mixture from FiberVisions • Super absorbent of Sodium polyacrylate • Vinyl acetate ethylene (VAE) from Celanese • Synthetic blood from Hy-Tec

3.2 Selection of commercial products for analysis A broad range of different napkins, ultrathin menstrual pads and pantyliners from competing brands were purchased from food stores and pharmacies. All products were then ripped apart to determine which napkins and which femcare absorbent cores were produced through airlaid. Four napkins and four femcare products were selected for further studies.

3.3 Analysis The selected napkins and the selected femcare products were analyzed to investigate important properties of interest. All napkins were analyzed to determine the thickness, grammage, density, bending length, composition and mechanical properties. The selected femcare products were analyzed to determine the grammage, thickness, density, liquid spreading (spreading length and absorption capacity) and the composition. Before analysis, all femcare absorbent cores needed preparation by removing the absorbent cores from the other layers in the products to enable testing. Analyses were also performed on the developed napkin structure and the developed femcare absorbent core structure.

3.3.1 Grammage Samples were prepared according to the EDANA NWSP 130.1.R0 (15) standard testing procedure to measure the mass per unit area, also denoted grammage. Each napkin was cut into 20x25 cm pieces and each femcare absorbent core was cut into the largest rectangular piece possible. All samples were conditioned at 23°C and 50% relative humidity for 24 hours prior to analysis.

Each sample was weighed and the mass per unit area was calculated by using equation 1 where G is the grammage measured in g/m2, m is the mass measured in grams and A is the area measured in m2.

푚 퐺 = (1) 퐴

3.3.2 Thickness and density Samples were prepared according to the EDANA NWSP 120.6.R0 (15) standard testing procedure to measure the thickness. Each sample was cut into 5x5 cm pieces and conditioned at 23°C and 50% relative humidity for 24 hours prior to analysis. The thickness of each sample was measured three times by using a Messer Büchel micrometer model 49-56 with an applied pressure of 0.5 kPa.

The same samples were then used to determine the density of each product. Density was calculated by using equation 2 where ρ is the density measured in kg/m3, A is the area measured in m2 and h is the average thickness obtained from previous measurements.

푚 푚 휌 = = (2) 푉 퐴 ∗ ℎ

3.3.3 Bending length Samples were prepared according to the EDANA NWSP 090.5.R0 (15) standard testing procedure to determine the flexibility and softness of each sample by using a WIRA bending length tester. All samples were cut into 25 x 250 mm strips and conditioned at 23°C and 50 % relative humidity for 24 hours prior to analysis.

Bending length was determined by measuring the overhanging lengths in centimeters and using these values as the input in equation 3. Measurements were performed on both front and back side of each sample.

푂푣푒푟ℎ푎푛푔𝑖푛푔 푙푒푛푔푡ℎ (3) 퐵푒푛푑𝑖푛푔 푙푒푛푔푡ℎ = 2

3.3.4 Liquid spread and absorption capacity All samples were cut into rectangular pieces and conditioned at 23°C and 50 % relative humidity for 24 hours prior to analysis.

An inclined plexiglass plane of 30° was placed in a fluid reservoir. Synthetic blood was then added to the fluid reservoir until the testing level was reached. Each sample was weighed and placed on the inclined Plexiglas plane. Liquid spread was measured after 10 minutes, and the test species were weighed. Equation 4 was then used to calculate the grams absorbed per gram product to determine the absorption capacity for each sample.

푓𝑖푛푎푙 푤푒𝑖푔ℎ푡 − 푠푡푎푟푡𝑖푛푔 푤푒𝑖푔ℎ푡 (4) 푔푟푎푚푠 푎푏푠표푟푏푒푑 푝푒푟 푔푟푎푚 푝푟표푑푢푐푡 = 푠푡푎푟푡𝑖푛푔 푤푒𝑖푔ℎ푡

3.3.5 Scanning Electron Microscope (SEM) Samples were analyzed through Scanning Electron Microscope, SEM to determine the components in all commercial products and to see the latex spraying distribution in the developed structures.

Analysis was performed by attaching each sample on carbon tape and coat it with a thin layer of gold by using an AGAR Manual Gold Sputter Coater B7340. Each sample was then analyzed by using a FEI Quanta 250 Scanning Electron Microscope.

3.3.6 Tensile testing Samples were prepared according to the EDANA standard testing procedure NWSP 110.4.R0(15) specially designed to determine the breaking force and elongation of a nonwoven material. All test samples were cut into 25x150 mm strips and conditioned at 23°C and 50% relative humidity for 24 hours before analysis.

Measurements were carried out by using an INSTRON 5944 tensile testing machine model 2580107 with a test speed of 300 mm/min.

3.4 Method development for producing airlaid structures The findings from the analyses of the commercial products were used as a target reference during the method development. The developed methods contain 5 separate steps illustrated in figure 6. All these steps were optimized to obtain structures with suitable properties. The optimization included manipulation of different suctions, agitation and running times during formation. Other parameters which were controlled include the mixing procedure, the effect of compositional changes, the latex spraying setup and the curing procedure.

Figure 6. The different steps in the developed methods.

4. Results and discussion

4.1 Selected commercial products The commercial napkins the commercial femcare products selected for analyses are gathered in table 2.

Table 2. Commercial napkins and commercial femcare products selected for analysis.

Commercial napkins Commercial femcare products Product A Product E Product B Product F Product C Product G Product D Product H

4.2 Napkin structures This section gathers all results and discussion related to the developed napkin structure and the commercial napkins.

4.2.1 Developed napkin process A 32x32 cm nonwoven tissue was prepared and added to a sample frame and inserted to the airlaid former. Fluff pulp was separated in a barrel by using pressurized air before it was added in smaller portions to the airlaid former. The machine was running for one minute at 606 rpm with an applied pressure of 2.5 kPa.

Samples were placed inside a laboratory press and a load was applied for a few seconds. Each sample was then cut into 15x15 cm pieces and placed separately inside the press for embossing. This was performed by adding a plastic mesh screen inside the laboratory press.

Vinyl acetate ethylene was diluted with water until a solid content of 20 wt% was obtained. The diluted VAE was then added to a spraying gun and the samples were secured according to figure 7. Each sample was then sprayed with the diluted VAE from a distance of 40 cm. After spraying the samples were cured for 15 minutes at 130°C in a ventilated oven. Lastly, the nonwoven tissue was removed, and the spraying procedure and curing was repeated on the samples back side.

Figure 7. Latex spraying setup for the napkin structure.

4.2.2 Developed napkin structure Figure 8 shows the top side of the developed napkin structure. Figure 9 shows a close-up of the same structure to illustrate the embossing pattern more clearly. Figure 10 shows the back

side of the produced napkin structure. This side is more uneven and lacks the embossing pattern.

Figure 8. The top side of the developed napkin structure. The embossing pattern is visible in the front right corner.

Figure 9. Close-up of the developed napkin structure. The embossing pattern is clearly seen.

Figure 10. Back side of the produced napkin structure. This side is more uneven and has no embossing pattern.

The developed napkin structure obtained a nice surface finish. This is clearly seen in figure 9 since the embossing pattern looks like the pattern on the commercial products. The plastic mesh screen which was used during embossing is therefore highly recommended during pressing of an airlaid surface to mimic the existing pattern on a napkin.

During sample production, it was discovered that removal of the nonwoven tissue slightly affects the appearance of the developed structures. Even though the nonwoven tissue was removed carefully, a small amount of fluff pulp got stuck on the nonwoven surface. Yet, usage is still essential to facilitate sample transport before the structure is bonded together. The nonwoven removal consequently needs to be carefully performed to ensure a pleasant surface finish.

4.2.3 Analysis of napkin structures This section gathers all findings from the analyses of the commercial napkins and the developed napkin structure.

Table 3 shows the results from the grammage measurements, the thickness measurements, the density measurements and the bending length measurements. Each analysis reports the specific results from each commercial product together with their calculated average value and corresponding value of the developed napkin structure.

Table 3. Results from grammage measurements, thickness measurements, density measurements and bending length measurements.

Grammage Thickness Density Bending [g/m2] [mm] [kg/m3] length [cm] Product A 71.78 0.731 98.16 4.85

Product B 54.77 0.366 163.0 3.25

Product C 65.48 0.438 149.3 4.62

Product D 55.64 0.390 142.6 -

Average value, 61.92 ± 9.86 0.474 ± 0.257 138.4 ± 40.3 4.24 ± 0.99 commercial napkins Developed napkin 65.92 1.659 39.73 3.20 structure

4.2.3.1 Thickness and density measurements As seen in table 3, the developed napkin structure is considerably thicker compared to the commercial napkins. The commercial napkins have an average thickness of 0.474 mm while the developed napkin structure obtained a thickness of 1.659 mm. This deviation was obtained during latex spraying or during curing since the thickness of the developed napkin structure was measured and controlled in the previous manufacturing steps.

The developed napkin structure would therefore benefit from additional pressing which preferably is performed after the nonwoven tissue is removed and the samples have endured its first curing. This forms a napkin structure with a thickness that corresponds better with the thickness in a commercial product. Additional pressing also enables embossing on the back side of the samples if a plastic mesh screen is added to the press. This creates a napkin structure more similar to the commercial products on the market. Moreover, it also generates an improved stability since the current structure is relatively easy to tear apart. The increased thicknesses also affected the obtained the densities since the developed napkin structure obtained a density of 39.7 kg/m3 while the commercial napkins have an average density of 138.4 kg/m3.

4.2.3.2 Bending length Bending length analysis was performed to compare the flexibility and softness of the developed napkin structure with the commercial napkins. The results are gathered in table 3. No measurements were performed on product D since this product contained folds and hence did not fulfil the requirements of the EDANA NWSP 090.5.R0 (12) standard testing procedure. As seen in table 3, the developed napkin structure has a shorter bending length compared to all commercial products. However, the difference between the developed structure and product B is very small. It is therefore safe to say that the developed napkin structure has a slightly higher flexibility and softness compared to the commercial products.

4.2.3.3 SEM images Figure 11 shows a SEM image of product B. The napkin contains fluff pulp (cellulose fibers) and latex which are marked A and B respectively. SEM analysis shows that all commercial napkins contain these two components. However, figure 11 is only representative for product A, product B and product C since additional fibers were found in product D. Product D also contains thermofibers which is clearly seen in figure 12.

A B

Figure 11. SEM image of product B. Fluff fibers (A) and latex (B) are clearly seen.

B C

A D

Figure 12. SEM image of product D. Fluff fiber (A) and thermofibers (B) are clearly seen. C and D indicate presence of latex.

Thermofibers are commonly added as a complement beyond latex to bind a thicker absorbent hygiene structure. This makes thermofibers less common in a napkin structure and explains why most of the analyzed napkins do not contain any thermofibers. However, figure 12 clearly indicates that product D uses a combination of latex and thermofibers to bind the product. One can therefore conclude that this product uses multiple bonding to bind the structure.

Since latex was found in all commercial napkins, it was motivated as a suitable bonding technique during method development. SEM analysis of the developed structures shows that latex can be seen on the top of the developed structure (Figure 13), however it did not manage to reach the center of the structure (Figure 14). SEM analysis should have been performed on some samples during the spraying development to improve the end structure.

It is therefore advised to further analyze how the spraying procedure is best performed. One factor which could be of interest to analyze is the effect of placing the samples horizontally instead of vertically during the spraying. After spraying, droplets enter the structure by either wicking, gravity or suction. The droplets then fall apart which facilitates the bonding [3]. By adjusting the sample placement, it might become easier for the droplets to enter the structure which potentially could provide a better bonding. It would also be of interest to use a spraying nozzle which covers the whole sample area which would contribute to a more even latex distribution.

A B

Figure 13. SEM image of the top side of the developed napkin structure. Fluff fibers (A) and latex (B) are clearly seen.

Figure 14. SEM image of the center of the developed napkin structure. Fluff fibers (A) is clearly seen. No presence of latex is seen.

4.2.3.4 Mechanical properties Figure 15 shows the average stress-strain curves for all commercial napkins. Product A have a considerably lower ultimate tensile strength and Young´s modulus compared to the other commercial napkins as seen in table 4. There are multiple possible explanations to these observations. Firstly, product A have a grammage, thickness and density which deviate more from the calculated average values compared to the other commercial napkins. This could potentially affect the products´ ability to endure load. Secondly, fibrous materials usually endure a larger load in the fiber length orientation compared to in the transverse fiber orientation. Since a certain load is applied during formation on an industrial scale, some fiber orientation rearrangement will take place even though the structure is considered as a randomly oriented structure. This affects the products mechanical properties giving rise to different properties in different orientations. Consequently, there is a risk that the test species for product A were prepared in the least strong orientation which potentially could explain the lower values.

The stress-strain curves for the developed napkin structure have an irregular behavior as seen in Figure 16. Moreover, this structure has a considerably lower ultimate tensile strength compared to the commercial products. These results might be influenced by the load cell which was used during analysis. The load cell has an upper limit of 2 kN while the developed napkin structure has a breaking force of only 1.3 N. Consequently, only 0.056% of the total testing span was used. This could cause inaccurate results since there is not enough load for the data to stabilize itself during testing. Another possible explanation is related to the inhomogeneity in the developed structures. As previously mentioned, SEM analysis indicated that no latex managed to reach the center in the developed structure. It was therefore relatively easy to separate the developed structure into two separate sheets since there is no strong bonding provided within the structure. This could have allowed cracks to propagate in the regions which do not contain any latex while the areas that contain latex withstood the load. Another possible explanation is related to the lower densities in the developed structure. A less dense structure provides fewer binding points in a fiber network which makes it more difficult to obtain a proper effect provided by the latex.

Commercial napkins 1,4 Product A 1,2 Product B

1 Product C

0,8 Product D

0,6 Stress [MPa] Stress 0,4

0,2

0 0 0,05 0,1 0,15 0,2 0,25 0,3 0,35 0,4 Strain [mm/mm]

Figure 15. Tensile testing of the commercial napkins.

Napkin stucture 0,04 Sample 1 0,035 Sample 2 0,03 Sample 3 Sample 4 0,025 Sample 5 0,02 Sample 6

0,015 Sample 7 Stress [MPa] Stress

0,01

0,005

0 0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 Strain [mm/mm]

Figure 16. Tensile testing of the developed napkin structure.

As seen in table 4, the developed napkin structure obtained a lower Youngs modulus, breaking force and ultimate tensile strength compared to the commercial products. This is most likely connected to the factors mentioned above.

Table 4. Mechanical properties of the commercial napkins and the developed napkin structure.

Youngs Modulus Breaking force Ultimate tensile Elongation % [MPa] [N] strength [MPa] Product A 6.90 10.2 0.56 13.8

Product B 24.9 11.8 1.22 7.78

Product C 20.6 14.7 1.31 11.1

Product D 20.7 12.6 1.27 15.1

Average, 17.6 ± 10.7 12.3 ± 2.4 1.09 ± 0.53 11.9 ± 4.12 commercial napkins Developed napkin 0.18 1.3 0.031 23.1 structure

4.3 Femcare absorbent core structures This section gathers all results related to the developed femcare structure and the commercial femcare absorbent cores.

4.3.1 Developed femcare absorbent core process A 32x32 cm nonwoven tissue was prepared and added to a sample frame and inserted to the airlaid former. Fluff pulp, thermofibers and SAP were mixed in a barrel by using pressurized air. The fluff pulp mixture was then added in smaller portions to the airlaid former and the machine was running for one minute at 606 rpm with an applied pressure of 2.5 kPa.

Samples were placed inside a press and a load was applied for a few seconds. Each sample was cut into 15x15 cm pieces and placed separately inside the press and an additional load was applied for a few seconds.

Vinyl acetate ethylene was diluted with water until a solid content of 20 wt% was obtained. The diluted VAE was then added to a spraying gun and the samples were secured according to figure 17. Each sample was then sprayed with the diluted VAE from a distance of 40 cm. The samples were thereafter cured at 130°C for 15 minutes in a ventilated oven. Lastly, the nonwoven tissue was removed, and spraying procedure and curing was repeated on the samples back side.

Figure 17. Latex spraying setup for the developed femcare absorbent core.

4.3.2 Developed femcare absorbent core structure Figure 18 shows the top side of the produced femcare structure. The visible cavities were formed during pressing due to the presence of superabsorbent polymer. Figure 19 shows the back side of the same structure.

Figure 18. Top side of the produced femcare structure. The visible cavities were formed during pressing due to the presence of superabsorbent polymer.

Figure 19. Back side of the produced femcare structure. This side contains less cavities.

The developed femcare structure obtained a nice surface finish which show resemblance with the commercial products since the cavities seen in figure 18 appears close to the cavities on the commercial products.

During sample formation it was observed that the airlaid former tends to generate samples which are slightly thicker in the middle compared to the outer parts. This was mainly seen on the femcare structure since these samples are considerably thicker than the napkin structure.

4.3.3 Analysis of femcare absorbent core structures This section gathers findings from the analyses of the commercial femcare absorbent cores and the developed core structures.

Table 5 shows the results from the grammage measurements, the thickness measurements and the density measurements. Each analysis reports the specific results from each commercial product together with their calculated average value and corresponding value for the developed femcare absorbent core structure.

Table 5. Results from grammage measurements, thickness measurements and density measurements.

Grammage Thickness Density [g/m2] [mm] [kg/m3] Product E 192.6 1.624 110.4

Product F 224.2 2.285 169.1

Product G 141.4 1.067 120.9

Product H 256.0 2.302 109.8

Average, 203.6 ± 62.15 1.820 ± 0.753 127.5 ± 41.5 commercial products Developed femcare 212.69 3.337 63.73 structure

4.3.1 Grammage measurement Table 5 shows that the developed femcare structure obtained a grammage which corresponds well with the grammages in the commercial femcare absorbent cores. Similar observations are also seen in table 4 since the developed napkin structure also obtained a grammage which corresponds well with the grammages in the commercial napkin structures. This accuracy is possible due to the understanding of the material losses while running the airlaid former. During method development, it was established that the developed napkin method generated an average material loss of 5.3 ± 0.5 wt% and the developed femcare method generated an average material loss of 9.6 ± 0.24 wt%. The additional material losses in the femcare structure is almost exclusively superabsorbent polymer. During sample formation, it was established that an average SAP loss of 0.36 ± 0.08 g was obtained. This corresponds to 6.2% of the added amount.

4.3.2 Thickness and density Table 5 shows that the developed femcare structure are thicker than to the commercial femcare absorbent cores. This structure would therefore also benefit from additional pressing to obtain a thickness which corresponds even better to the commercial femcare absorbent cores. The developed femcare absorbent core also obtained a lower density compared the commercial products as seen in table 5. A density more similar to the commercial products could therefore be obtained by performing the additional pressing which were suggested to solve the increased thickness.

4.3.3 Liquid spread and absorption capacity Table 6 shows the results from the liquid spread measurements on the commercial femcare products and the developed femcare structure. The column “liquid spreading length” represents the height to which the testing liquid rose during the measurements.

Table 6. Starting weight, final weight, liquid spreading length and grams absorbed per gram product of the commercial femcare absorbent cores and the developed femcare absorbent core structure.

Starting Final weight Liquid Grams weight [g] [g] spreading absorbed liquid length [cm] per gram product [g/g] Product E 0.73 5.17 6.48 6.12

Product F 0.92 7.06 8.04 6.65

Product G 0.59 4.32 5.98 6.34

Product H 2.28 9.37 7.84 3.11

Overall average 1.13 ± 1.15 6.48 ± 2.48 7.09 ± 1.11 5.56 ± 2.45 commercial products Developed femcare 1.47 14.3 7.43 8.75 structure

The developed femcare structure has better absorbency than the commercial femcare absorbent cores as seen in table 6. There are multiple possible explanations to this observation. Firstly, it is important to remember that all investigated products may have different surface properties such as how hydrophilic the materials are. This has a large impact on the wettability and liquid spreading. Secondly, all structures have different thicknesses and different densities which also affects the liquid spreading and absorption capacity in a structure. Thirdly, the varying amount of SAP within each product is another possible explanation. Since SAP have a large capacity to absorb liquid in relation to its own weight [4], just a slight increase or decrease in the amount has a large impact on the absorption capacity. Moreover, product H did not even contain any SAP. This is most likely the explanation why this product performed significantly worse in the absorbency test.

4.3.4 SEM images Figure 20 shows a SEM image of product E. This femcare absorbent core clearly contains fluff pulp, latex and thermofiber which are marked A, B and C respectively. Yet, the other commercial absorbent cores are more difficult to interpret. They all clearly contain fluff pulp, but presence of latex is trickier to establish. However, latex might be present in all products, but it cannot be determined with SEM imaging. Further analysis is therefore required to determine if this was the true case. Moreover, none of product F, product G or product H

contain any thermofibers. This is interesting since thermofibers are commonly added to enhance the bonding by providing a multibonded structure.

Figure 20. SEM image of product E. Fluff fibers (A), latex (B) and thermofiber (C) are clearly seen.

Despite the lack of thermofibers in product F, product G and product H it was decided to use thermofibers in the developed femcare structure. Figure 21 and figure 22 shows SEM images of this structure. All components within this structure such as fluff pulp, latex and thermofiber are clearly marked. Unfortunately, no latex managed to penetrate into the center in the developed femcare structure. Since the same observation was seen in the developed napkin structure, both developed methods would benefit from an improved spraying procedure.

D B

Figure 21. SEM image of the top side of the developed femcare absorbent core structure. Fluff fibers (A) latex (B) and thermofiber (C) is clearly seen. The big lump (D) is a deformed thermofiber.

A B

Figure 22. SEM image of the center of the developed femcare absorbent core structure. Fluff fibers (A) and thermofiber (B) is clearly seen. No presence of latex is seen.

During sample production, a curing temperature of 130°C was used to bind the structures. This temperature is most likely enough to obtain a multibonded structure since the thermofibers have a core of polypropylene and a surface of polyethylene. These two polymers have a melting temperature of 100-145°C [22] and 140-170°C [23] respectively. The curing temperature therefore melts the surface which upon cooling provide a multibonded structure.

5. Conclusion

• Two methods were developed, one for producing a napkin structure and one for producing a femcare absorbent core structure.

• Both developed structures had grammages almost identical as the grammages in the commercial products.

• Both developed structures had thicknesses which were higher than the commercial products and densities which were lower than the commercial products. The decreased densities most likely influenced the results from other analysis performed in this project.

• The developed napkin structure has a slightly higher flexibility compared to the commercial napkins.

• The developed femcare structure had similar liquid spreading length and better liquid absorption capacity compared to the commercial products.

• The stress-stain curves of the developed napkin structure had an irregular appearance. This made it difficult to compare the mechanical properties between the developed napkin structure and the commercial napkins.

• No latex managed to penetrate into the center in the developed structures due to the application technique. The latex spraying procedure must be further developed for the methods to be used in future activities at Stora Enso.

• Both developed structures obtained a surface finish which show resemblance with the commercial products.

6. Future recommendations It is advised to further investigate possible latex spraying application techniques to improve the latex spraying procedure. It is also recommended to perform additional pressing to generate structures with more resemblance in thickness and densities with the commercial products.

Moreover, it is also recommended to perform new tensile testing measurements on the developed napkin structure to obtain data comparable with the commercial napkins.

Lastly, it could be of interest to further analyze the effect of adding thermofibers to the femcare structure and investigate if a curing temperature of 130°C is enough to obtain a multibonded structure.

7. Acknowledgements I want to express my deepest gratitude to my supervisors Helena Tufvesson and Caroline Duong for all support and guidance I have received throughout this project. I am forever thankful for obtaining this opportunity and for all the help I have received in the lab. My sincere gratitude also goes to Deniz Dayan and all other colleges at Stora Enso who have given me valuable advice.

I also want to thank Torbjörn Pettersson for being the examiner of this degree project and for taking his time by helping me when needed.

Thank you, Erik Jungstedt, all colleagues in Skutskär and all colleagues in Karlstad who have helped me with the analyses which could not be performed at the Innovation Center for biomaterials in Sickla.

My warmest thank you also goes to all colleges in Sickla who made me feel so welcomed and contributed to such an open-minded atmosphere.

8. References

[1] P. Mango, "The Future of Fluff Pulp to 2022," Smithers Pira, 2017.

[2] "Stora Enso", https://www.storaenso.com/en/products/market-pulp/fluff-pulp-for-hygiene- products. [Accessed 15 05 2020].

[3] P. Mango, "The Future of Airlaid Nonwovens to 2022," Smithers Pira, 2017.

[4] "edana", https://www.edana.org/nw-related-industry/what-is-sap. [Accessed 24 04 2020].

[5] Babaarslan, Nazan Avcioglu and Osman Kalebek , "Fiber Selection for the Production of Nonwovens," in Non-woven Fabrics, 2016.

[6] A. Wilson, "Applications of Nonwovens in Technical Textiles," in The formation of dry, wet, spunlaid and other types of nonwovens, Woodhead Publishing, 2010, pp. 3-17.

[7] D. Zhang, "Nonwovens for consumer and industrial wipes," in Applications of Nonwovens in Technical Textiles, Textile Research Associates, 2010, pp. 103-119.

[8] G. J. e. al., "Debonders for use in papermakin". Patent WO2010080958A1, 15 07 2012.

[9] Irwin M. Hutten, George C. Chase and Brad Kalil, Handbook of Nonwoven Filter Media, Butterworth-Heinermann, 2016.

[10] P. K. Chatterjee, "Products and Technology Perspective," Textile Science and Technology, vol. 13, pp. 447-477, 2002.

[11] M. Niaounakis, "The Problem of Marine Plastic Debits," in Management of Marine Plastic Debits Prevention, Recycling, and Waste Management, 2017, pp. 1-55.

[12] Söderhjelm, Jan-Erik Levin and Liva, "Pulp and Paper Testing," in Paper and Science technology, Tappi, 1999.

[13] Elisabeth Bränvall et. al., "The Ljungberg textbook Biofiber Chemistry," 2010, pp. 34-52.

[14] "Evonik," https://www.tissueadditives.com/product/tissue-additives/en/technical- information/fluff-pulp/debonders/. [Accessed 16 06 2020].

[15] "Bicomponent Fibers, Classification of Bicomponent Fibers, Production of Bicomponent Fibers, Application of Bicomponent Fibers," Textile learners, 2012.

[16] Muhammad Maqsood and Gunnar Seide, "Novel Bicomponent Functional Fibers with Sheath/Core Configuration Containing Intumescent Flame-Retardants for Textile Applications," Materials, pp. 1-19, 2019.

[17] Chenhao Zhao and Min Zhang, "Salt-Tolerant Superabsorbent Polymer with High Capacity of Water-Nutrient Retention Derived from Sulfamic Acid-Modified Starch," ACS Omega, vol. 4, no. 3, p. 5923–5930, 2019.

[18] Arn Mignona, Nele De Belie, Peter Dubruel, Sandra Van Vlierberghe, "Superabsorbent polymers: A review on the characteristics and applications of synthetic, polysaccharide-based, semi-synthetic and ‘smart’ derivatives," European Polymer Journal, vol. 117, pp. 165-178, 2019.

[19] J.R. Ajmeri, C.J. Ajmeri, "Developments in the use of nonwovens for disposable hygiene products," in Advances in Technical Nonwovens, Woodhead Publishing Series in Textiles, 2016, pp. 473-496.

[20] S.S. Cutie et.al, "Analysis of sodium polyacrylate absorbent dust using ultra-trace sodium analysis—a seven-company collaborative study," Analytica Chimica Acta, vol. 298, no. 13, pp. 351-361, 1994.

[21] Kara E.Woeller and Anne E.Hochwalt, "Safety assessment of sanitary pads with a polymeric foam absorbent core," Regulatory Toxicology and Pharmacology, vol. 73, no. 1, pp. 419-424, 2015.

[22] K. Albahily et. al., "Metallocene Alkene Polymerization Catalysts," Polymer Science: A Comprehensive Reference, vol. 3, pp. 673-697, 2012.

[23] Jonahira Rodriguez-Arnold, Anqiu Zhang and Stephen Z.D. Cheng, "Crystallization, melting and morphology of syndiotactic polypropylene fractions," Polymer, vol. 35, no. 9, pp. 1884-1895, 1993.

Appendix

APPENDIX A

Table 7. Complete documentation of all collected data during the thickness measurements of the commercial products.

Measur- Product Product Product Product Product Product Product Product Sample ement A [mm] B [mm] C [mm] D [mm] E [mm] F [mm] G [mm] H [mm] 1 1 0.73 0.36 0.44 0.38 1.49 2.53 1.06 2.27 2 0.74 0.38 0.44 0.39 1.49 2.44 1.01 2.26 3 0.74 0.38 0.44 0.38 1.45 2.42 1.01 2.26 Average 0.74 0.37 0.44 0.38 1.48 2.47 1.03 2.26 2 4 0.73 0.35 0.44 0.41 1.68 2.33 1.14 2.31 5 0.73 0.35 0.44 0.40 1.69 2.33 1.02 2.25 6 0.72 0.35 0.44 0.41 1.59 2.32 1.12 2.26 Average 0.72 0.35 0.44 0.41 1.65 2.33 1.09 2.27 3 7 0.73 0.36 0.43 0.41 1.59 2.33 0.90 2.27 8 0.72 0.36 0.43 0.40 1.58 2.19 0.90 2.24 9 0.72 0.36 0.43 0.39 1.64 2.39 1.10 2.24 Average 0.72 0.36 0.43 0.40 1.60 2.30 0.97 2.26 4 10 0.72 0.37 0.45 0.40 1.59 2.18 1.08 2.37 11 0.75 0.37 0.45 0.38 1.63 2.13 1.08 2.39 12 0.75 0.37 0.45 0.34 1.62 2.16 1.00 2.27 Average 0.74 0.37 0.45 0.39 1.62 2.16 1.06 2.34 5 13 0.75 0.37 0.44 0.37 1.78 2.15 1.18 2.38 14 0.74 0.37 0.43 0.36 1.78 2.18 1.20 2.38 15 0.74 0.37 0.43 0.37 1.78 2.19 1.21 2.38 Average 0.74 0.37 0.43 0.37 1.78 2.17 1.20 2.38 Overall Average 0.731 0.366 0.438 0.390 1.624 2.285 1.067 2.302

Table 8. Complete documentation of all collected data during the thickness measurements of the developed napkin structure and the developed femcare structure.

Sample Measurement Developed Developed Napkin structure Femcare structure [mm] [mm] 1 1 1.81 3.31 2 1.78 2.90 3 1.76 3.62 Average 1.78 3.10 2 4 1.63 3.10 5 1.60 2.94 6 1.67 3.68 Average 1.63 3.24 3 7 1.74 3.51 8 1.59 3.06 9 1.68 3.31 Average 1.67 3.29 4 10 1.70 3.18 11 1.78 3.21 12 1.82 3.71 Average 1.77 3.37 5 13 1.39 3.76 14 1.53 3.30 15 1.43 3.48 Average 1.45 3.51

Overall average 1.66 3.34

APPENDIX B

Table 9. Complete documentation of all collected data during grammage measurements of the commercial products.

Sample Measu- Product Product Product Product Product Product Product Product rement A B C D E F G H [g/m2] [g/m2] [g/m2] [g/m2] [g/m2] [g/m2] [g/m2] [g/m2] 1 1 72.0 54.6 65.0 54.2 191.7 231.4 160.1 198.8 2 72.2 54.4 64.6 54.2 191.7 233.8 157.9 198.8 3 72.2 54.4 64.8 54.2 194.3 236.2 161.0 198.8 4 72.2 54.6 65.0 54.2 191.7 233.8 158.0 198.8 5 72.2 54.6 64.8 54.4 191.7 233.8 158.0 195.3 2 6 72.2 53.2 67.4 56.0 192.0 226.6 146.4 252.1 7 72.0 53.2 67.4 56.0 192.0 228.9 146.4 252.1 8 72.2 53.2 67.2 56.2 194.6 226.5 144.1 252.1 9 72.2 53.2 67.2 56.0 194.6 229.0 146.5 248.6 10 72.2 53.0 67.2 56.2 192.0 229.0 144.1 252.1 3 11 72.4 54.8 64.8 58.4 190.1 236.2 125.0 299.8 12 72.4 55.0 64.8 58.4 192.7 238.6 125.0 299.8 13 72.4 55.0 65.0 58.2 192.7 238.6 125.0 299.8 14 72.4 55.0 64.8 58.4 192.7 238.6 125.0 295.6 15 72.4 55.0 64.8 58.4 12.71 238.6 125.0 299.8 4 16 71.2 55.0 66.2 52.6 198.6 192.8 123.9 245.6 17 71.2 55.0 66.4 52.6 198.6 192.8 124.0 249.6 18 71.2 55.0 66.2 52.6 198.6 192.8 126.1 249.6 19 71.2 54.8 66.2 52.6 201.3 192.8 126.1 249.6 20 71.2 55.0 66.2 52.8 198.6 192.8 126.1 245.6 5 21 71.0 56.2 64.2 56.8 184.3 229.0 150.0 278.9 22 71.0 56.2 64.2 57.0 187.0 229.0 152.8 285.1 23 71.0 56.2 64.2 57.0 187.0 229.0 152.8 283.4 24 71.0 56.2 64.2 56.8 187.0 226.6 152.8 283.4 25 71.0 56.4 64.2 56.8 187.0 226.6 153.0 287.7 Average value [g/m2] 71.78 54.77 65.48 55.64 192.6 224.2 141.4 256.0

Table 10. Complete documentation of all collected data during grammage measurements of the developed napkin structure and the developed femcare structure.

Sample Measurement Grammage Grammage developed developed napkin structure femcare [g/m2] structure [g/m2] 1 1 63.91 216.6 2 63.91 216.6 3 63.31 217.2 4 63.91 216.6 5 63.31 217.1 2 1 66.27 220.1 2 66.27 220.7 3 65.68 220.7 4 65.68 220.7 5 66.27 220.7 3 1 60.36 195.9 2 60.36 195.9 3 60.95 195.9 4 60.36 195.3 5 60.36 195.3 4 1 71.01 220.7 2 71.01 220.7 3 71.01 220.7 4 70.41 220.7 5 70.41 220.7 5 1 68.64 209.5 2 68.64 210.2 3 68.64 210.1 4 68.64 209.5 5 68.64 209.5 Overall average 65.917 212.69

APPENDIX C

Table 11. Complete documentation of all collected data during density measurements of the commercial products.

Sample Measure- Product Product Product Product Product Product Product Product ment A B C D E F G H [kg/m3] [kg/m3] [kg/m3] [kg/m3] [kg/m3] [kg/m3] [kg/m3] [kg/m3] 1 1 162.5 98.46 148.2 138.9 117.0 171.7 123.6 85.84 2 161.9 98.73 147.3 138.9 111.8 170.4 123.3 86.97 3 161.9 98.73 147.8 138.9 116.9 172.5 121.0 87.51 4 162.5 98.73 148.2 138.9 107.6 170.0 115.2 87.12 5 162.5 98.73 147.8 139.5 108.6 170.7 109.9 88.62 2 6 158.3 98.73 153.7 143.6 111.5 178.8 128.7 110.3 7 158.3 98.45 153.7 143.6 112.3 179.2 133.0 112.3 8 158.3 98.73 153.3 144.1 110.1 178.3 129.9 112.2 9 158.3 98.73 153.3 143.6 109.4 181.2 127.1 111.7 10 157.7 98.73 153.3 144.1 107.3 182.5 123.1 114.4 3 11 163.1 99.00 147.8 149.7 104.2 176.5 96.03 129.0 12 163.7 99.00 147.8 149.7 106.7 179.4 102.2 130.0 13 163.7 99.00 148.2 149.2 107.8 180.8 102.4 130.7 14 163.7 99.00 147.8 149.7 111.5 180.2 102.2 128.9 15 163.8 99.00 147.8 149.7 112.9 180.8 100.4 131.0 4 16 163.8 97.36 151.0 134.8 117.2 141.0 124.8 98.90 17 163.8 97.36 151.4 134.8 114.9 142.9 123.4 101.9 18 163.7 97.36 155.0 134.8 113.3 140.7 125.9 101.3 19 163.1 97.36 151.0 134.8 114.2 139.0 126.9 100.9 20 163.7 97.36 151.0 135.4 112.5 140.7 125.5 99.50 5 21 167.3 97.09 146.4 145.6 108.9 171.5 129.8 116.8 22 167.3 97.09 146.4 146.1 111.1 177.5 134.8 119.4 23 167.3 97.09 146.4 146.1 107.8 175.2 131.5 119.2 24 167.3 97.09 146.4 145.6 107.0 170.1 130.3 119.4 25 167.9 97.09 146.4 145.6 107.9 174.7 131.0 121.4 Average value [kg/m3] 163.0 98.16 149.3 142.6 110.4 169.0 120.9 109.8

Table 12. Complete documentation of all collected data during density measurements of the developed napkin structure and the developed femcare structure.

Sample Measurement Density Density developed developed napkin structure femcare [g/m3] Structure [g/m3] 1 1 38.52 64.89 2 38.52 64.89 3 38.17 65.07 4 38.52 64.89 5 38.17 65.07 2 1 39.95 65.96 2 39.95 66.13 3 39.59 66.13 4 39.59 66.13 5 39.95 66.13 3 1 36.38 58.69 2 36.38 58.69 3 36.74 58.69 4 36.38 58.51 5 36.38 58.51 4 1 42.80 66.13 2 42.80 66.13 3 42.80 66.13 4 42.45 66.13 5 42.45 66.13 5 1 41.38 62.76 2 41.38 62.94 3 41.38 62.94 4 41.38 62.76 5 41.38 62.76 Overall average 39.73 63.73

APPENDIX D

Product A 1,6 Sample 1 1,4 Sample 2 1,2 Sample 3 Sample 4 1 Sample 5 0,8

0,6 Stress [MPa] Stress 0,4

0,2

0 0 0,05 0,1 0,15 0,2 0,25 0,3 0,35 0,4 Strain [mm/mm]

Figure 23. Tensile testing of product A.

Product B 1,6 Sample 1 1,4 Sample 2 Sample 3 1,2 Sample 4 1 Sample 5 Sample 6 0,8 Sample 7

Stress [MPa] Stress 0,6

0,4

0,2

0 0 0,05 0,1 0,15 0,2 0,25 0,3 0,35 0,4 Strain [mm/mm]

Figure 24. Tensile testing of product B.

Product C 1,6 Sample 1 1,4 Sample 2 1,2 Sample 3 Sample 4 1 Sample 5 0,8 Sample 6 Sample 7

0,6 Stress [MPa] Stress 0,4

0,2

0 0 0,1 0,2 0,3 0,4 Strain [mm/mm]

Figure 25. Tensile testing of product C.

Product D 1,6 Sample 1 1,4 Sample 2 Sample 3 1,2 Sample 4 1 Sample 5 0,8 Sample 6 Sample 7

0,6 Stress [MPa] Stress

0,4

0,2

0 0 0,1 0,2 0,3 0,4 0,5 Strain [mm/mm]

Figure 26. Tensile testing of product D.

APPENDIX E

Figure 27. SEM image of product A. Fluff (A) and latex (B) is clearly seen.

A B

Figure 28. SEM image of product B. Fluff (A) and latex (B) is clearly seen.

Figure 29. SEM image of product C. Fluff (A) and latex (B) is clearly seen.

B C

A D

Figure 30. SEM image of product D. Fluff fibers (A) and thermofiber (B) is clearly seen. (C) and (D) indicates presence of latex.

A C

Figure 31. SEM image of product E. Fluff fibers (A), thermofiber (B) and latex (C) is clearly seen.

Figure 32. SEM image of product F. Fluff fibers (A) are clearly seen. (B) indicates possible presence of latex.

Figure 33. SEM image of product G. Fluff fibers (A) is clearly seen. (B) indicates possible presence of latex.

Figure 34. SEM image of product H. Fluff fibers (A) are clearly seen. (B) indicates possible presence of latex.

APPENDIX F

Table 13. Complete documentation of all collected data during liquid spread measurement.

Sample Starting Finishing Weight Grams Length weight [g] weight [g] difference absorbed/ [cm] [g] gram product Product E 1 0.74 5.06 4.32 5,84 6.40 2 0.72 5.02 4.30 5,97 6.50 3 0.73 5.04 4.31 5,90 6.40 4 0.75 5.08 4.33 5,77 6.60 5 0.69 5.63 4.94 7,16 6.50 Average 0.73 5.17 4.44 6,13 6.48 Product F 1 0.96 7.59 6.630 6,91 7.90 2 0.94 6.94 6.00 6,38 8.10 3 0.98 7.11 6.13 6,26 7.70 4 0.79 6.18 5.39 6,82 8.20 5 0.94 7.46 6.52 6,94 8.30 Average 0.92 7.06 6.13 6,66 8.04 Product G 1 0.64 5.31 4.67 7,30 6.20 2 0.60 4.75 4.15 6,92 6.30 3 0.58 3.97 3.39 5,84 6.70 4 0.57 3.64 3.07 5,39 5.40 5 0.55 3.92 3.37 6,13 5.30 Average 0.59 4.32 3.73 6,31 5.98 Product H 1 2.19 9.59 7.40 3,38 7.80 2 2.21 9.49 7.28 3,29 7.90 3 2.37 9.35 6.98 2,96 7.90 4 2.33 9.36 7.03 3,01 8.00 5 2.29 9.04 6.75 2,95 7.60 Average 2.28 9.37 7.09 3,11 7.84 Developed 1 1.48 15.0 13.5 5,55 7.40 Femcare 2 1.41 14.6 13.2 9,11 7.60 structure 3 1.50 14.1 12.6 9,33 7.70 4 1.69 16.6 14.9 8,40 7.40 5 1.53 14.5 12.9 8,80 7.20 6 1.19 11.2 10.0 8,44 7.30 Average 1.47 14.3 12.84 8,40 7.43

APPENDIX G

Table 14. Complete documentation of all collected data during bending length testing.

Sample Measurement Product Product B Product C Product D Developed A [cm] [cm] [cm] [cm] Napkin structure [cm] 1 Front 4.90 3.30 4.55 - 3,05 Back 4.75 3.20 4.80 - 2,9 2 Front 5.05 3.15 4.60 - 3,15 Back 4.85 3.25 4.75 - 2,75 3 Front 5.15 3.35 4.90 - 3,4 Back 4.90 3.25 4.80 - 3,5 4 Front 4.95 3.40 4.65 - 3,35 Back 4.75 3.30 4.80 - 3,35 5 Front 4.70 3.35 4.85 - 3,3 Back 4.75 3.25 4.90 - 3,4 6 Front 5.00 3.30 4.85 - 3,2 Back 4.95 3.40 4.95 - 3,05 7 Front 4.70 3.10 4.30 - - Back 4.55 3.15 4.35 - - 8 Front 4.45 3.30 4.35 - - Back 4.50 3.20 4.40 - - 9 Front 4.45 3.05 4.30 - - Back 4.65 3.10 4.35 - - 10 Front 4.70 3.15 4.60 - - Back 5.10 3.30 4.50 - - 11 Front 5.15 3.20 4.40 - - Back 5.15 3.35 4.65 - - 12 Front 5.25 3.25 4.70 - - Back 5.10 3.40 4.55 - - Overall 4.85 3.25 4.62 - 3.2 Average [mm]