Soft, Functional Sanitary Paper Products
The term “tissue” encompasses toilet paper, facial tissues, napkins, cosmetic tissues, and paper towels for both home and commercial use. As much as these products may differ, they must all satisfy the same high expectations: they should be soft, economical, tear-resistant and of course hygienic; ideally they should support good skin care and feel pleasant to the touch. This can be accomplished through the use of additives and lotions.
Thanks to its LIOSIL® TS brand, WACKER offers an array of silicone products that deliver precisely this combination of properties, with a focus on the softness, sensory characteristics and hydrophilicity of the end product – TS, after all, stands for tissue softness. When added to any traditional sanitary paper products, LIOSIL® TS additives and lotions support gentle skin care, deliver outstanding softness and improve technical performance.
Raw Materials and Production
The quality of sanitary paper depends on the manufacturing process and on the raw materials used. Whereas cellulose from softwood trees primarily ensures tear resistance, cellulose from hardwood provides good absorbency. Fibers obtained by recycling used paper represent a sensible ecological alternative, but these can have a negative impact on the physical and sensory properties of sanitary paper products. LIOSIL® TS additives and lotions can counteract those effects.
Development and Documentation
At WACKER laboratories throughout the world, we are constantly developing new product solutions, which we review in terms of their application and processing properties. We also support our customers when it comes to regulatory questions. Some WACKER products for sanitary paper meet regulations governing paper for food contact (Germany’s Federal Institute for Risk Assessment), while others are suitable for cosmetic products and for INCI declarations of ingredients.
There are two basic ways of optimizing the quality of tissue products: either using additives incorporated during production, or using what are known as “tissue lotions,” which are applied to the dry tissue after production. Known as conversion, this process can be carried out using various application techniques.
This method involves feeding the dry tissue between two rollers. The bottom roller is coated with lotion, while the upper roller moves the tissue through the system. The more evenly the lotion is applied to the rollers, the better the result will be. The coating can also be adjusted by varying the speed of the rollers and the pressure they exert.
In this technique, the lotion is sprayed onto one or both sides of the sanitary paper using an automatic spray mechanism. The amount of lotion can be modified by varying the spray pressure: the higher the pressure, the more lotion is applied to the tissue. A few grams per square meter is usually all it takes to significantly improve tissue properties.
The compatibility of LIOSIL® products with application techniques is determined through material compatibility tests. WACKER also supports you throughout the entire product launch – from the first sensory test to industrial scale implementation.
Tissues with an Extra Dose of Personal Care
Facial tissues that pamper sore, runny noses with aloe vera or eye pads that revive tired eyes with vitamins: tissues enhanced with personal-care ingredients are trending. LIOSIL® TS lotions can be enriched with plant extracts and other substances specified by the customer. In this case, the lotion assists in distributing valuable actives evenly onto the sanitary paper.
The softer the better: this rule of thumb is especially applicable for tissues that come into contact with sensitive areas of skin. In order to make tissues feel softer, manufacturers can treat them with LIOSIL® TS lotion based on functionalized silicones. A distinction is drawn between surface softness and what is known as “bulk softness,” i.e., how soft the inside of the tissue feels when it is crumpled. Tests are available for determining both surface softness and bulk softness.
Panel Test for Determining Surface Softness
This panel test determines the subjective perception of softness of the tissue’s surface by having test panelists hold the tissue in both hands and run their fingers over it, comparing its softness to that of another tissue. The test requires at least 5 trained panelists.
Tissue Softness Test for Determining Surface Softness
Another method for determining softness is to use the emtec Tissue Softness Analyzer: this instrument measures the surface softness, roughness and stiffness of any kind of tissue. Unlike humans, this device delivers objective results and can assess each of the three parameters independently.
Panel Test for Determining Bulk Softness
WACKER also performs a panel test to determine the bulk softness of sanitary paper. In this method, panelists crumple a tissue in one hand and report the subjective softness and stiffness. The test is performed by at least 5 trained panelists. Panelists use the same hand to crumple each of the tissues, which they then sort according to softness and stiffness.
Whether you’re wiping up spills or drying your hands, hydrophilicity – absorbency, in other words – is one of the most important properties of many types of tissues. LIOSIL® TS lotions based on functionalized silicones can greatly increase how much water a tissue can absorb. Tissue absorbency can be determined through the use of a water drop test.
Determining Hydrophilicity Using the Water Drop Test
The water drop test is used for determining whether and how the use of LIOSIL® TS Lotion affects the hydrophilicity of a tissue. In this test, a drop of deionized water is released from a burette onto the tissue from a height of 5 cm. A stopwatch measures the amount of time it takes for the tissue to completely absorb the drop – the shorter the time, the better the hydrophilicity. The test is performed at least 5 times per tissue.
If the manufacturing process is to be efficient, a simple cleaning process must be in place for all of the tanks and plant components involved in production. Not only does this accelerate processes, but it also reduces the amounts of water and cleaning agents needed – and that helps conserve resources and save money. At WACKER we use the cleaning test to determine how well LIOSIL® TS products can be cleaned.
The Cleaning Test
The cleaning test simulates how much of a dried-on LIOSIL® TS lotion can be removed from a stainless steel vessel using water and cleaning agents. This is done by wetting a small stainless steel plate with the product and weighing it after the lotion has dried. Next, the plate is placed in water, sprayed and then treated with a cleaning agent. This cycle is repeated several times. Once this is complete, the weight of the residue is recorded and compared to the initial weight.
Defoamer Test for Determining Foaming Behavior
The defoamer test involves dispensing 200 g LIOSIL® TS lotion into each of several vessels and adding different defoaming agents to each. A device is then used to incorporate air into the lotion for 2 minutes. The amount of air introduced is then determined by weighing the product and comparing this to a reference product containing no defoamer. The less air is introduced, the more effective the defoaming agent. The test is repeated after an established time interval in order to test the long-term efficiency of the defoaming agent.
Although they need to be soft, sanitary paper products should also be stable and tear-resistant. The raw materials used represent one way of affecting these properties: whereas cellulose from softwood trees primarily ensures tear resistance, cellulose from hardwood provides good absorbency. Combining these types of cellulose therefore results in soft, tear-resistant tissues. Another way of modifying tear resistance is by adding LIOSIL® TS. We use the ball burst test to gauge its effect.
Determining Bursting Strength with the Ball Burst Test
The ball burst test determines the ability of a sanitary paper product to withstand mechanical force. To do this, a spherical measurement head presses on a sample with increasing force until it breaks through the tissue. The test can be performed on wet or dry tissue. Results are expressed in terms of the maximum force in Newtons. The higher the value, the greater the resistance.