Multilayer soluble solid article containing a coating composition and method for preparing the same

Abstract

The present invention provides a soluble solid article including multiple layers of a flexible soluble porous sheet material, wherein a coating composition is present on at least one inner surface of at least one sheet in the solid article. The present invention also provides a method for preparing such a solid article.

Description

Technical Field

[0001] The present invention relates to a multi-layer soluble solid article comprising a coating composition and a method for preparing the same. Background Art

[0002] Flexible soluble sheets comprising surfactants and / or other active ingredients in a water-soluble polymer carrier or matrix are well known. Such sheets are particularly useful for delivering surfactants and / or other active ingredients when dissolved in water. Such sheets have better structural integrity, are more concentrated, and are easier to store, ship / transport, handle, and process compared to traditional particulate or liquid forms of the same product category. Such sheets are more flexible and less brittle compared to solid tablet forms of the same product category and have a better sensory appeal to consumers.

[0003] In order to deliver an amount of surfactant and / or other active ingredients sufficient to achieve the desired product function, it is desirable to use multiple layers of such flexible and soluble sheets, and it is also desirable to assemble such multiple layers into an integral soluble solid article, which can then be sold as an integral finished product. However, compared to single-layer structures, various challenges may be encountered when attempting to assemble multiple layers of such flexible and soluble sheets into an integral article, including a significantly slower dissolution rate in water. In some cases, the multi-layer sheet may encounter gelling problems. Specifically, due to the dissolution of the water-soluble polymer (e.g., PVA) and surfactant in the solid article, gelling occurs when the multi-layer sheet comes into contact with water. The presence of gelling may prevent water from penetrating into the multi-layer sheet, resulting in a reduced dissolution rate. There is also a risk that such multi-layer structures may not completely dissolve under certain stringent washing conditions (e.g., cold water or extremely hard water, or low water volume washing conditions) and may leave undissolved residues, which can be a major consumer "pain point".

[0004] To improve dissolution, some studies have developed porous sheets having an open-cell foam (OCF) structure, characterized by an open-cell percentage of about 80% to 100%. Although such OCF structures significantly improve the dissolution rate of the resulting porous sheets, it is desirable for consumers to obtain even further improved dissolution characteristics, including less gelling and / or less chance of leaving undissolved residues.

[0005] Accordingly, there has been a continuing need for multi-layer structures with improved dissolution rates. Summary of the Invention

[0006] The present invention uses a coating composition applied to one or both contact surfaces of adjacent layers of a multi-layer flexible soluble porous sheet to further improve the dissolution characteristics of the multi-layer structure. Prior to the present invention, it was believed that applying additional components (e.g., coating compositions) between the layers of a multi-layer flexible soluble porous sheet might have a negative impact on the flow of water through the porous sheet (e.g., clogging the porous structure), and thus might adversely affect the overall dissolution characteristics of the sheet. Surprisingly, the inventors of the present invention unexpectedly found that a multi-layer soluble solid article comprising the coating composition provides significantly improved dissolution characteristics.

[0007] In one aspect, the present invention relates to a method for preparing a soluble solid article, the method comprising the steps of: 1) providing two or more flexible porous soluble sheets and a coating composition, wherein each of the two or more sheets comprises a water-soluble polymer and a first surfactant, and is characterized by an open pore percentage content of 80% to 100% and an overall average pore size of 100 μm to 2000 μm, and wherein the coating composition comprises a second surfactant; 2) applying the coating composition to at least one surface of at least one of the two or more sheets; and 3) arranging the two or more sheets in a stack to form a soluble solid article such that the coating composition is not on any outer surface of the stack.

[0008] In another aspect, the present invention relates to a soluble solid article comprising two or more flexible porous soluble sheets, wherein each of the two or more sheets comprises a water-soluble polymer and a first surfactant, and is characterized by an open pore percentage content of 80% to 100% and an overall average pore size of 100 μm to 2000 μm; and wherein a coating composition comprising a second surfactant is present on at least one surface of at least one of the two or more sheets, provided that the coating composition is not on any outer surface of the soluble solid article. In another aspect, the present invention relates to a soluble solid article comprising two or more flexible porous soluble sheets, wherein each of the two or more sheets comprises a water-soluble polymer and a first surfactant, and is characterized by an open pore percentage content of 80% to 100%, an overall average pore size of 100 μm to 2000 μm and a density of 0.05 g / cm 3 to 0.17 g / cm 3 ; wherein a coating composition comprising a second surfactant is present on at least one surface of at least one of the two or more sheets, provided that the coating composition is not on any outer surface of the soluble solid article.

[0009] In another aspect, the present invention relates to a soluble solid article comprising two or more flexible porous soluble sheets, wherein each of the two or more sheets comprises a water-soluble polymer and a first surfactant, and is characterized in that the percentage of open pores is 80% to 100% and the overall average pore size is 100 μm to 2000 μm; a coating composition comprising a second surfactant and a solvent is present on at least one surface of at least one of the two or more sheets, provided that the coating composition is not on any outer surface of the soluble solid article; and wherein the solvent is selected from glycerol, propylene glycol, 1,3-propanediol, diethylene glycol, dipropylene glycol, ethanolamine, ethanol, water, and any combination thereof.

[0010] Preferably, the coating composition can be a liquid having a viscosity of about 1 cps to about 25,000 cps, preferably about 2 cps to about 10,000 cps, more preferably about 3 cps to about 5,000 cps, most preferably about 1,000 cps to about 5,000 cps, as measured at about 20 °C and 1 s -1 The preferred viscosity of the coating composition can provide an even better balance between dissolution characteristics and leakage.

[0011] An advantage of the soluble solid article according to the present disclosure is that, compared with a soluble solid article not having a coating composition, the soluble solid article comprising the coating composition applied therein exhibits significantly improved dissolution characteristics.

[0012] An advantage of the soluble solid article according to the present disclosure is that it can be used as a carrier for the active substances contained in the coating composition. More advantageously, two or more incompatible components can be present separately in the sheet and the coating composition. Compared with a soluble solid article not having a coating composition, the soluble solid article according to the present disclosure can have greater flexibility.

[0013] An advantage of the soluble solid article according to the present disclosure is that the coating composition can allow for a more compact product with the same amount of surfactant, because the coating composition has a relatively high density.

[0014] These and other aspects of the present invention will become more apparent when reading the following detailed description of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A convection-based heating / drying apparatus for preparing flexible porous soluble solid sheet articles by an intermittent method is shown.

[0016] Figure 2Shows a microwave-based heating / drying apparatus for preparing flexible porous soluble solid sheet products by an intermittent method.

[0017] Figure 3 Shows an impact oven-based heating / drying apparatus for preparing flexible porous soluble solid sheet products by a continuous method.

[0018] Figure 4 Shows a bottom conduction-based heating / drying apparatus for preparing flexible porous soluble sheets by an intermittent method according to one embodiment of the present invention.

[0019] Figure 5 Shows a rotary drum-based heating / drying apparatus for preparing another flexible porous soluble sheet by a continuous method according to another embodiment of the present invention.

[0020] Figure 6A Shows a scanning electron microscope (SEM) image of the top surface of a flexible porous soluble sheet containing a fabric care active substance, the flexible porous soluble sheet being prepared by a method using a rotary drum-based heating / drying apparatus. Figure 6B Shows a sheet containing Figure 6A An SEM image of the top surface of an alternative flexible porous soluble sheet containing the same fabric care active substance as the sheet shown, but the alternative flexible porous soluble sheet being prepared by a method using an impact oven-based heating / drying apparatus.

[0021] Figure 7A Shows an SEM image of the top surface of a flexible porous soluble sheet containing a hair care active substance, the flexible porous soluble sheet being prepared by a method using a bottom conduction-based heating / drying apparatus. Figure 7B Shows a sheet containing Figure 7A An SEM image of the top surface of an alternative flexible porous soluble sheet containing the same hair care active substance as the sheet shown, but the alternative flexible porous soluble sheet being prepared by a method using an impact oven-based heating / drying apparatus.

[0022] Figure 8A Shows an exemplary diagram of one embodiment of a soluble solid article having a plurality of flexible porous sheets according to the present disclosure, wherein a coating composition is applied in a central region on the contact surface of two adjacent intermediate sheets. Figure 8B Shows an exemplary diagram of another embodiment of a soluble solid article having a plurality of flexible porous sheets according to the present disclosure, wherein a coating composition is applied on the entire contact surface of any two adjacent sheets, each of the two adjacent sheets not being an outermost sheet.

[0023] Figure 9 shows the results of the gelling tests of solid articles containing the coating composition and solid articles without the coating composition. Figure 9A shows the peak shear modulus G' and the final shear modulus G'; and Figure 9B shows the total area.

[0024] Figure 10 shows only the solid sheet ( Figure 10A ) and a scanning electron microscope (SEM) image of a solid article containing the coating composition ( Figure 10B ). Detailed Description

[0025] I. Definitions

[0026] As used herein, the term "flexible" refers to the ability of an article to withstand stress without breaking or significantly rupturing when the article is bent 90° along a centerline perpendicular to its longitudinal direction. Preferably, such an article can undergo significant elastic deformation and is characterized by a Young's modulus of no more than 5 GPa, preferably no more than 1 GPa, more preferably no more than 0.5 GPa, and most preferably no more than 0.2 GPa.

[0027] As used herein, the term "soluble" refers to the ability of an article to completely or substantially dissolve in a sufficient amount of deionized water within eight (8) hours at 20 °C and atmospheric pressure without any stirring, leaving less than 5 wt% of undissolved residue.

[0028] As used herein, the term "solid" refers to the ability of an article to substantially maintain its shape (i.e., there is no visible change in its shape) at 20 °C and atmospheric pressure when the article is unrestricted and when no external force is applied to it.

[0029] As used herein, the term "sheet" refers to a non-fibrous structure having a three-dimensional shape, i.e., having a thickness, a length, and a width, where both the length-to-thickness aspect ratio and the width-to-thickness aspect ratio are at least about 5:1, and the length-to-width ratio is at least about 1:1. Preferably, both the length-to-thickness aspect ratio and the width-to-thickness aspect ratio are at least about 10:1, more preferably at least about 15:1, and most preferably at least about 20:1; and the length-to-width aspect ratio is preferably at least about 1.2:1, more preferably at least about 1.5:1, and most preferably at least about 1.618:1.

[0030] As used herein, the term "contact surface" of adjacent sheets refers to the two surfaces that contact each other when adjacent sheets are arranged in a stack, where the two surfaces are from two adjacent sheets respectively. For example, if two adjacent sheets are arranged vertically in a stack, the contact surface can be the lower surface of the upper sheet and the upper surface of the lower sheet.

[0031] As used herein, the term "bottom surface" refers to the surface of the flexible, porous, soluble solid sheet of the present invention that directly contacts the support surface on which the wet premix sheet inflated during the drying step is placed, and the term "top surface" refers to the surface of the sheet opposite the bottom surface. Additionally, such solid sheets can be divided along their thickness into three (3) regions, including a top region adjacent to its top surface, a bottom region adjacent to its bottom surface, and an intermediate region located between the top region and the bottom region. The top region, the intermediate region, and the bottom region have the same thickness, i.e., each region has a thickness that is about 1 / 3 of the total thickness of the sheet.

[0032] As used herein, the term "outermost sheet" refers to a sheet in the multi-layer soluble solid article of the present invention that is adjacent to only one other sheet.

[0033] As used herein, the term "open-cell foam" or "open-cell pore structure" refers to a polymer-containing solid continuous matrix that defines a network of spaces or pores that contain a gas, typically a gas (such as air), and the foam structure does not collapse during the drying process, thereby maintaining the physical strength and cohesiveness of the solid. The interconnectivity of the structure can be described by the percent open cell content, which is measured by Test 3 disclosed below.

[0034] As used herein, the term "water-soluble" refers to the ability of a material to completely dissolve or disperse in water without leaving visible solids or forming a distinct separate phase when at least about 25 grams, preferably at least about 50 grams, more preferably at least about 100 grams, and most preferably at least about 200 grams of the sample material is placed in one liter (1 L) of deionized water at 20 °C and stirred thoroughly at atmospheric pressure.

[0035] As used herein, the term "aerate (aerating or aeration)" refers to a method of introducing a gas into a liquid or paste composition by mechanical and / or chemical means.

[0036] As used herein, the term "heating direction" refers to the direction along which a heat source applies thermal energy to an article, which results in a temperature gradient in such article that decreases from one side of such article to the other. For example, if a heat source located at one side of an article applies thermal energy to the article to create a temperature gradient that decreases from one side to the opposite side, the heating direction is considered to extend from one side to the opposite side. If both sides of such article or different parts of such article are heated simultaneously without an observable temperature gradient across such article, the heating is performed in a non-directional manner and there is no heating direction.

[0037] As used herein, the term "substantially opposite" or "substantially offset" means an offset angle of 90° or greater between two directions or two lines.

[0038] As used herein, the terms "substantially aligned" or "substantially alignment" mean that there is an offset angle of less than 90° between two directions or two lines.

[0039] As used herein, the term "major heat source" means a heat source that provides more than 50%, preferably more than 60%, more preferably more than 70%, and most preferably more than 80% of the total thermal energy absorbed by an object (e.g., an inflated wet premix sheet according to the present invention).

[0040] As used herein, the term "controlled surface temperature" means relatively consistent, i.e., a surface temperature having a fluctuation of less than + / -20%, preferably less than + / -10%, and more preferably less than + / -5%.

[0041] The term "substantially free of" means that the indicated material is present at a very low level, not intentionally added to the composition or product, or preferably present in such a composition or product at a level that cannot be detected by an analytical method. It may include such a composition or product in which the indicated material is only an impurity in one or more of the materials intentionally added to such a composition or product.

[0042] II. Overview of the Method for Preparing Solid Sheets

[0043] WO2010077627 discloses a batch process for forming a porous sheet having an open-cell foam (OCF) structure characterized by an open-cell percentage of about 80% to 100% for improving dissolution. Specifically, a premix of raw materials is first formed, vigorously inflated, and then batch-heated and dried (e.g., in a convection oven or a microwave oven) to form a porous sheet having a desired OCF structure. Although such an OCF structure significantly improves the dissolution rate of the resulting porous sheet, there is still an apparently denser and less porous bottom region with thicker pore walls in such a sheet. Such a high-density bottom region may have a negative impact on the water flow through the sheet, thereby possibly adversely affecting the overall dissolution rate of the sheet. When multiple such sheets are stacked together to form a multi-layer structure, the "barrier" effect of multiple high-density bottom regions is particularly enhanced.

[0044] WO2012138820 discloses a method similar to WO2010077627, except that the continuous drying of the inflated wet premix is achieved by using, for example, an impact oven (instead of a convection oven or a microwave oven). The OCF sheets formed by such a continuous drying method are characterized by an improved uniformity / consistency of the pore structure over different regions thereof. Unfortunately, there are still rate-limiting factors in such OCF sheets, such as a top surface having relatively small pore openings and a top region having relatively small pores (i.e., a shell-like top region), which may have a negative impact on the flow of water therethrough and slow down its dissolution.

[0045] During the drying step in the above method, the OCF structure is formed under a simultaneous mechanism of water evaporation, bubble collapse, drainage of interstitial liquid from the thin film bubble surface layer to the platform boundaries between the bubbles (creating openings between the bubbles and forming open pores), and curing of the premix. Various processing conditions may affect these mechanisms, such as the solids content in the wet premix, the viscosity of the wet premix, gravity, and the drying temperature, as well as the need to balance such processing conditions in order to achieve controlled drainage and form the desired OCF structure.

[0046] The surprising and unexpected finding of the present invention is that, in addition to the above processing conditions, the direction of the thermal energy employed during the drying step (i.e., the heating direction) may also have a significant impact on the resulting OCF structure.

[0047] For example, if the thermal energy is applied in a non-directed manner (i.e., without a clear heating direction) during the drying step, or if the heating direction is substantially aligned with the direction of gravity (i.e., having an offset angle of less than 90° therebetween) during most of the drying step, the resulting flexible, porous, and soluble solid sheet tends to have a top surface with relatively small pore openings and a relatively large variation in pore size in different regions along its thickness direction. In contrast, when the heating direction is offset from the direction of gravity (i.e., having an offset angle of 90° or greater therebetween) during most of the drying step, the resulting solid sheet may have a top surface with relatively large pore openings and a reduced variation in pore size in different regions along the thickness of such sheet. Correspondingly, the latter sheet is more receptive to the flowing water and is thus more soluble than the former sheet.

[0048] Although not bound by any theory, it is believed that the alignment or misalignment between the heating direction and the direction of gravity during the drying step and their duration may significantly affect the drainage of interstitial liquid between the bubbles and, correspondingly, affect the pore expansion and pore openings in the cured premix and produce solid sheets having very different OCF structures. Such differences are more clearly illustrated by the following Figures 1 to 4 more clearly illustrates such differences.

[0049] Figure 1A convective-based heating / drying apparatus is shown. During the drying step, the mold 10 (which can be made of any suitable material such as metal, ceramic or prepared) is filled with an aerated wet premix, which forms a sheet 12 having a first side 12A (i.e., the top side) and an opposite second side 12B (i.e., the bottom side as it is in direct contact with the support surface of the mold 10). During the drying step, such a mold 10 is placed in a convection oven at 130 °C for about 45 to 46 minutes. The convection oven heats the sheet 12 from above, i.e., along the downward heating direction (as shown by the cross-hatched arrow), which creates a temperature gradient in the sheet 12 that decreases from the first side 12A to the opposite second side 12B. The downward heating direction is aligned with the direction of gravity (as shown by the white arrow), and this aligned position is maintained throughout the drying time. During drying, gravity drains the liquid premix downward to the bottom region, while the downward heating direction first dries the top region and finally dries the bottom region. As a result, a porous solid sheet is formed that has a top surface including many pores with small openings formed by bubbles that did not have the opportunity to fully expand. Such a top surface with smaller pore openings is not optimal for water to enter the sheet, which may limit the dissolution rate of the sheet. On the other hand, the bottom region of such a sheet is dense and less porous, with larger pores formed by fully expanded bubbles but a very small number, and the pore walls between the pores in such a bottom region are thick due to the downward liquid drainage caused by gravity. Such a dense bottom region with fewer pores and thick pore walls is a further rate-limiting factor for the overall dissolution rate of the sheet.

[0050] Figure 2A microwave-based heating / drying apparatus is shown. During the drying step, the mold 30 is filled with an aerated wet premix, which forms a sheet 32 having a first side 32A (top side) and an opposite second side 32B (bottom side). Such a mold 30 is then placed in a low-energy density microwave applicator (not shown) provided by Industrial Microwave System Inc. (North Carolina) and operated at a power of 2.0 kW, a belt speed of 1 foot per minute, and an ambient air temperature of 54.4 °C. During the drying step, the mold 30 is placed in such a microwave application for approximately 12 minutes. Such a microwave applicator heats the sheet 32 from the inside, without any distinct or consistent heating direction. Correspondingly, no temperature gradient is formed in the sheet 32. During drying, the entire sheet 32 is heated simultaneously, or almost simultaneously, although gravity (as shown by the white arrow) still causes the liquid premix to drain downward towards the bottom region. As a result, the cured sheet formed in this way has more uniformly distributed and more uniformly sized pores compared to a sheet formed by a convection-based heating / drying apparatus. However, the liquid drainage under gravity during the microwave-based drying step may still result in a dense bottom region with thick pore walls. Additionally, during the drying step, heating the entire sheet 32 simultaneously may still limit the pore expansion and pore opening on the top surface, and the resulting sheet may still have a top surface with relatively small pore openings. Furthermore, the microwave energy heats the water inside the sheet 32 and causes such water to boil, which may produce bubbles of irregular sizes and form unexpected dense regions with thick pore walls.

[0051] Figure 3 A shock oven-based heating / drying apparatus is shown. During the drying step, the mold 40 is filled with an aerated wet premix, which forms a sheet 42 having a first side 42A (top side) and an opposite second side 42B (bottom side). Such a mold 40 is then placed in a continuous shock oven (not shown) under conditions similar to those described in Table 2 of Example 1 of WO2012138820. Such a continuous shock oven heats the sheet 42 from both the top and the bottom in relatively and offset heating directions (shown by two cross-hatched arrows). Correspondingly, no distinct temperature gradient is formed in the sheet 42 during drying, and the entire sheet 42 is heated almost simultaneously from both its top surface and its bottom surface. Similar to Figure 3 the microwave-based heating / drying apparatus described in Figure 4In such an impact oven-based heating / drying apparatus, gravity (as indicated by the white arrow) continues to cause the liquid premix to drain downward toward the bottom region. As a result, the cured sheet formed in this way has pores with a more uniform distribution and more uniform size compared to the sheet formed by a convection-based heating / drying apparatus. However, the liquid drainage under the action of gravity during the drying step may still result in a dense bottom region with thick pore walls. In addition, during the drying step, heating the sheet 42 from both sides almost simultaneously may still limit the pore expansion and pore opening on the top surface, and the resulting sheet may still have a top surface with relatively small pore openings.

[0052] In contrast to the above heating / drying apparatuses (convection-based, microwave-based, or impact oven-based), the present invention provides a heating / drying apparatus for drying an aerated wet premix, wherein the heating direction is purposefully configured to counteract / reduce the liquid drainage caused by gravity toward the bottom region (thereby reducing the density and improving the pore structure of the bottom region) and to allow more time for the bubbles near the top surface to expand during drying (thereby forming significantly larger pore openings on the top surface of the resulting sheet). These two features serve to improve the overall dissolution rate of the sheet and are therefore desirable.

[0053] Figure 4Shown is a bottom-conduction based heating / drying apparatus for preparing a flexible porous soluble sheet according to an embodiment of the present invention. Specifically, the mold 50 is filled with an inflated wet premix, which forms a sheet 52 having a first side 52A (i.e., the bottom side) and an opposite second side 52B (i.e., the top side). During the drying step, such a mold 50 is placed on a heating surface (not shown), for example, on top of a preheated Peltier plate having a controlled surface temperature of about 125 °C to 130 °C for about 30 minutes. Heat is conducted through the mold from the heating surface at the bottom of the mold to heat the sheet 52 from below, i.e., along an upward heating direction (as indicated by the cross-hatched arrow), which forms a temperature gradient in the sheet 52 that decreases from the first side 52A (bottom side) to the opposite second side 52B (top side). Such an upward heating direction is opposite to the direction of gravity (as indicated by the white arrow) and remains so throughout the drying time (i.e., the heating direction is opposite to the direction of gravity for almost 100% of the drying time). During drying, gravity still causes the liquid premix to drain downward towards the bottom region. However, the upward heating direction dries the sheet from the bottom upwards, and the water vapor generated by the heat at the bottom region rises upwards to escape from the solidified matrix, so the downward liquid drainage towards the bottom region is significantly restricted and "counteracted" / reduced by the solidified matrix and the rising water vapor. Correspondingly, the bottom region of the resulting dried sheet is less dense and includes many pores with relatively thin pore walls. In addition, since the top region is the last region to dry during the process, the bubbles in the top region have sufficient time to expand to form significantly larger open pores at the top surface of the resulting sheet, which is particularly effective for promoting water entry into the sheet. Additionally, the resulting sheet has a more uniform distribution of overall pore sizes in its different regions (e.g., top, middle, bottom).

[0054] Figure 5Shown is a rotary drum-based heating / drying apparatus for preparing a flexible porous soluble sheet according to another embodiment of the present invention. Specifically, the feed trough 60 is filled with an aerated wet premix 61. A heated rotatable cylinder 70 (also known as a drum dryer) is placed above the feed trough 60. The heated drum dryer 70 has a cylindrical heated outer surface, characterized by a controlled surface temperature of about 130 °C, and it rotates in a clockwise direction (as indicated by the thin curved arrow) to pick up the aerated wet premix 61 from the feed trough 60. The aerated wet premix 61 forms a thin sheet 62 on the cylindrical heated outer surface of the drum dryer 70, and this sheet 62 of the aerated wet premix is rotated and dried over a period of approximately 10 to 15 minutes. A leveling blade (not shown) can be placed near the slurry pickup location to ensure a consistent thickness of the sheet 62 thus formed, although the thickness of the sheet 62 can be simply controlled by adjusting the viscosity of the aerated wet premix 61 as well as the rotational speed and surface temperature of the drum dryer 70. Once dried, the sheet 62 can be picked up manually or by a doctor blade 72 at the end of the drum rotation.

[0055] As Figure 5 shown, the sheet 62 formed from the aerated wet premix 61 includes a first side 62A (i.e., the bottom side) that directly contacts the heated outer surface of the heated drum dryer 70 and an opposite second side 62B (i.e., the top side). Correspondingly, heat from the drum dryer 70 conducts in an outward heating direction to the sheet 62 to first heat the first side 62A (bottom side) of the sheet 62 and then the opposite second side 62B (top side). Such an outward heating direction forms a temperature gradient in the sheet 62 that decreases from the first side 62A (bottom side) to the opposite second side 62B (top side). When the drum dryer 70 rotates, the outward heating direction slowly and continuously changes, but along a very clear and predictable path (as Figure 4 shown by the multiple outwardly extending cross-hatched arrows in). The relative positions of the outward heating direction and the direction of gravity (as shown by the white arrow) also slow down and continuously change in a similarly clear and predictable manner. For less than half of the drying time (i.e., when the heating direction is below the horizontal dashed line), the outward heating direction is substantially aligned with the direction of gravity, with an offset angle of less than 90°. During most of the drying time (i.e., when the heating direction is flush with or above the horizontal dashed line), the outward heating direction is opposite or substantially opposite to the direction of gravity, with an offset angle of 90° or greater. Depending on the initial "start" coating position of the sheet 62, the heating direction can be opposite or substantially opposite to the direction of gravity for more than 55% of the drying time (if the coating starts at the very bottom of the drum dryer 70), preferably more than 60% of the drying time (if the coating starts at a higher position on the drum dryer 70, as Figure 5As shown). Thus, during most of the drying step, in a rotary drum-based heating / drying apparatus, this slowed rotation and altered heating direction can still serve to limit and "counteract" / reduce the liquid drainage in the sheet 62 caused by gravity, thereby resulting in an improved OCF structure of the sheet so formed. The resulting sheet dried by the heated drum dryer 70 is also characterized by a less dense bottom region with many more uniformly sized holes and a top surface with relatively larger hole openings. Additionally, the resulting sheet has a more uniformly distributed overall pore size in its different regions (e.g., top, middle, bottom).

[0056] In addition to employing the desired heating direction as mentioned above (i.e., a substantially offset relationship with respect to the direction of gravity), it may also be desirable and even important to carefully adjust the viscosity and / or solids content of the wet premix, the amount and speed of aeration (air supply pump speed, mixing head speed, air flow rate, density of the aerated premix, etc., which can affect the bubble size and amount in the aerated premix and correspondingly affect the pore size / distribution / amount / characteristics of the cured sheet), the drying temperature, and the drying time, so as to achieve the optimal OCF structure of the resulting sheet according to the present invention.

[0057] A more detailed description of the method for preparing flexible porous soluble sheets according to the present invention, as well as the physical and chemical characteristics of such sheets, is provided in the ensuring section.

[0058] III. Method for Preparing Solid Sheets

[0059] The present invention provides a new and improved method for preparing flexible porous soluble solid sheets, which comprises the following steps: (a) forming a premix comprising raw materials (e.g., water-soluble polymers, active ingredients such as surfactants, and optionally plasticizers) dissolved or dispersed in water or a suitable solvent, the premix being characterized by a viscosity of from about 1,000 cps to about 25,000 cps measured at about 40 °C and 1 s -1 under; (b) aerating the premix (e.g., by introducing a gas into the wet slurry) to form an aerated wet premix; (c) shaping the aerated wet premix into a sheet having opposite first and second sides; and (d) drying the formed sheet at a temperature of from 70 °C to 200 °C for a drying time of from 1 minute to 60 minutes along a heating direction that forms a temperature gradient decreasing from the first side to the second side of the formed sheet, wherein the heating direction is substantially offset from the direction of gravity for more than half of the drying time, i.e., the drying step is carried out under heating along a predominantly "anti-gravity" heating direction. Such a predominantly "anti-gravity" heating direction can be achieved in various ways, including but not limited to bottom-conduction-based heating / drying apparatuses and rotary drum-based heating / drying apparatuses, as described above respectivelyFigure 4 and Figure 5 as shown

[0060] Step (A): Preparation of the Wet Premix

[0061] The wet premix of the present invention is typically prepared by mixing the solids of interest, including water-soluble polymers, surfactants, and / or other beneficial agents, optional plasticizers, and other optional components, with a sufficient amount of water or other solvent in a premixing tank. A mechanical mixer can be used to form the wet premix. Mechanical mixers that can be used herein include, but are not limited to, pitched blade mixers or MAXBLEND mixers (Sumitomo Heavy Industries).

[0062] Of particular importance in the present invention is to adjust the viscosity of the wet premix such that it is within a predetermined range of about 1,000 cps to about 25,000 cps when measured at 40 °C and 1 s -1 . During the subsequent drying step, the viscosity of the wet premix has a significant effect on the pore expansion and pore opening of the aerated premix, and wet premixes with different viscosities can form flexible porous soluble solid sheets with very different foam structures. On the one hand, when the wet premix is too thick / viscous (e.g., having a viscosity above about 25,000 cps as measured at 40 °C and 1 s -1 ), aeration of such wet premix may become more difficult. More importantly, the drainage of interstitial liquid from the film bubble surface layer to the plateau boundary of the three-dimensional foam during the subsequent drying step may be adversely affected or significantly restricted. The drainage of interstitial liquid during drying is considered crucial for achieving pore expansion and pore opening in the aerated wet premix during the subsequent drying step. As a result, the flexible porous soluble solid sheet formed thereby may have significantly smaller pores and less interconnectivity between the pores (i.e., pores that are more "closed" than open pores), which makes it more difficult for water to enter and flow out of such sheets. On the other hand, when the wet premix is too thin / non-flowing (e.g., having a viscosity below about 1,000 cps as measured at 40 °C and 1 s -1 ), the aerated wet premix may not be stable enough, i.e., the bubbles in the wet premix may burst, collapse, or coalesce too quickly after aeration and before drying. Therefore, the resulting solid sheet may have significantly fewer pores and be denser than desired.

[0063] In one embodiment, as at 40 °C and 1 s -1Measured below, the viscosity of the wet premix is in the range of from about 3,000 cps to about 24,000 cps, preferably from about 5,000 cps to about 23,000 cps, more preferably from about 10,000 cps to about 20,000 cps. The premix viscosity value is measured using a Malvern Kinexus Lab+ rheometer with a cone and plate geometry (CP1 / 50SR3468 SS), a gap width of 0.054 mm, a temperature of 40 °C, and a shear rate of 1.0 s-1 for a period of 360 seconds.

[0064] In a preferred but non-essential embodiment, the solids of interest are present in the wet premix at a level of from about 15% to about 70%, preferably from about 20% to about 50%, more preferably from about 25% to about 45% by weight of the total weight of the wet premix. The solids percentage is the sum of the weight percentages of all solid components, semi-solid components, and liquid components other than water and any significantly volatile substances such as low-boiling alcohols, based on the weight of the total processed mixture. On the one hand, if the solids content in the wet premix is too high, the viscosity of the wet premix may increase to a level that will prevent or adversely affect the drainage of the interstitial liquid and prevent the formation of the desired primary open-cell porous solid structure as described herein. On the other hand, if the solids content in the wet premix is too low, the viscosity of the wet premix may decrease to a level that will result in bubble breakage / collapse / coalescence and a percentage (%) of shrinkage of the more porous structure during drying, which results in a significantly less porous and denser solid sheet.

[0065] In the solids of interest in the wet premix of the present invention, there may be present from about 1% to about 75% of a surfactant, from about 0.1% to about 25% of a water-soluble polymer, and optionally from about 0.1% to about 25% of a plasticizer, based on the total weight of the solids. Other active substances or beneficial agents may also be added to the premix.

[0066] Optionally, the wet premix is immediately preheated before and / or during the aeration process at a temperature above ambient temperature but below any temperature that would cause degradation of the components therein. In one embodiment, the wet premix is maintained at a high temperature in the range of about 40°C to about 100°C, preferably about 50°C to about 95°C, more preferably about 60°C to about 90°C, and most preferably about 75°C to about 85°C. In one embodiment, optional continuous heating is utilized prior to the aeration step. Additionally, additional heat may be applied during the aeration process to attempt to maintain the wet premix at such high temperatures. This can be achieved via conductive heating from one or more surfaces, steam injection, or other processing means. It is believed that the act of preheating the wet premix before and / or during the aeration step can provide a method for reducing the viscosity of the premix containing a higher solid percentage content for improving the introduction of air bubbles into the mixture and the formation of the desired solid sheet. It is desirable to achieve a higher solid percentage content as this can reduce the overall energy required for drying. Thus, an increase in the solid percentage may conversely result in a decrease in water content and an increase in viscosity. As described above, a wet premix with too high a viscosity is not desirable for the practice of the present invention. Preheating can effectively counteract such an increase in viscosity and thus allow for the manufacture of rapidly dissolving sheets even when using a premix with a high solid content.

[0067] Step (B): Aeration of the Wet Premix

[0068] The wet premix is aerated to introduce a sufficient amount of air bubbles into the wet premix, which will subsequently form an OCF structure therein upon drying. Once adequately aerated, the wet premix is characterized by a density significantly lower than that of the unaerated wet premix (which may contain some inadvertently trapped air bubbles) or the under-aerated wet premix (which may contain some air bubbles but at a much lower volume percentage and with significantly larger bubble sizes). Preferably, the aerated wet premix has a density in the range of about 0.05 g / ml to about 0.5 g / ml, preferably about 0.08 g / ml to about 0.4 g / ml, more preferably about 0.1 g / ml to about 0.35 g / ml, still more preferably about 0.15 g / ml to about 0.3 g / ml, and most preferably about 0.2 g / ml to about 0.25 g / ml.

[0069] Inflation can be achieved by physical or chemical methods in the present invention. In one embodiment, it can be achieved by mechanically stirring to introduce gas into the wet premix, for example, by using any suitable mechanical processing device, including but not limited to: rotor-stator mixer, planetary mixer, pressurized mixer, non-pressurized mixer, batch mixer, continuous mixer, semi-continuous mixer, high-shear mixer, low-shear mixer, submerged distributor, or any combination thereof. In another embodiment, it can be achieved via chemical methods, for example, by using a chemical blowing agent to provide in-situ gas formation via a chemical reaction of one or more components, including forming carbon dioxide (CO2 gas) through an effervescent system.

[0070] In a particularly preferred embodiment, it has been found that inflation of the wet premix can be cost-effectively achieved by using a continuous pressurized inflator or mixer conventionally used in the production of marshmallows in the food industry. The continuous pressurized mixer can be used to homogenize or inflate the wet premix to produce a highly uniform and stable foam structure with uniform bubble size. The unique design of the high-shear rotor / stator mixing head can produce uniform bubble size in the layer of open-cell foam. Suitable continuous pressurized inflators or mixers include Morton mixer (Morton Machine Co., Motherwell, Scotland), Oakes continuous automatic mixer (E.T.Oakes Corporation, Hauppauge, New York), Fedco continuous mixer (The Peerless Group, Sidney, Ohio), Mondo (Haas-Mondomix B.V., Netherlands), Aeros (Aeros Industrial Equipment Co., Ltd., Guangdong Province, China), and Preswhip (Hosokawa Micron Group, Osaka, Japan). For example, the Aeros A20 continuous inflator can be operated at a feed pump speed setting of about 300 to 800 (preferably about 500 to 700), where the mixing head speed setting is respectively about 300 to 800 (preferably about 400 to 600) and the air flow rate is about 50 to 150 (preferably 60 to 130, more preferably 80 to 120). Again, for example, the Oakes continuous automatic mixer can be operated at a mixing head speed setting of about 10 rpm to 30 rpm (preferably about 15 rpm to 25 rpm, more preferably about 20 rpm), where the air flow rate is about 10 liters per hour to 30 liters per hour (preferably about 15 L / hour to 25 L / hour, more preferably about 19 L / hour to 20 L / hour).

[0071] In another specific embodiment, the aeration of the wet premix can be achieved by using a spinning rod which is a part of a rotary drum dryer, more specifically a component of the feed trough, where the wet premix is stored before it is coated onto the heated outer surface of the drum dryer and dried. The spinning rod is typically used to agitate the wet premix to prevent phase separation or sedimentation in the feed trough during the waiting time before it is coated onto the heated rotating drum of the drum dryer. In the present invention, such a spinning rod can be operated at a rotational speed in the range of about 150 rpm to about 500 rpm, preferably about 200 rpm to about 400 rpm, more preferably about 250 rpm to about 350 rpm, to mix the wet premix at the air interface and provide sufficient mechanical agitation required to achieve the desired aeration of the wet premix.

[0072] As described above, the wet premix can be maintained at a high temperature during the aeration process to adjust the viscosity of the wet premix for optimizing aeration and controlling drainage during drying. For example, when aeration is achieved by using a spinning rod of a rotary drum, during the initial aeration of the spinning rod (when the rotary drum is stationary), the aerated wet premix in the feed trough is typically maintained at about 60 °C, and then, when the rotary drum is heated and starts to rotate, it is heated to about 70 °C.

[0073] The bubble size of the aerated wet premix helps to achieve a uniform layer in the OCF structure of the resulting solid sheet. In one embodiment, the bubble size of the aerated wet premix is about 5 microns to about 100 microns; and in another embodiment, the bubble size is about 20 microns to about 80 microns. The uniformity of the bubble size results in a consistent density of the resulting solid sheet.

[0074] Step (C): Sheet Formation

[0075] After sufficient aeration, the aerated wet premix forms one or more sheets having opposite first and second sides. The sheet forming step can be carried out in any suitable manner, such as by extrusion, casting, molding, vacuum forming, pressing, printing, coating, etc. More specifically, the aerated wet premix can be formed into a sheet by: (i) casting it into a shallow cavity or tray or a specially designed sheet mold; (ii) extruding it onto a continuous belt or screen of a dryer; (iii) coating it onto the outer surface of a rotary drum dryer. Preferably, the support surface on which the sheet is formed is made of or coated with: corrosion-resistant materials, materials that do not interact and / or adhere to each other, such as metals (e.g., steel, chromium, etc.), polycarbonate, HDPE, LDPE, rubber, glass, etc.

[0076] Preferably, the formed inflated wet premix sheet has a thickness in the range of from 0.5 mm to 4 mm, preferably from 0.6 mm to 3.5 mm, more preferably from 0.7 mm to 3 mm, still more preferably from 0.8 mm to 2 mm, and most preferably from 0.9 mm to 1.5 mm. Controlling the thickness of such formed inflated wet premix sheets may be important to ensure that the resulting solid sheet has the desired OCF structure. If the formed sheet is too thin (e.g., less than 0.5 mm in thickness), many of the air bubbles trapped in the inflated wet premix will expand during the subsequent drying step to form through-holes extending through the entire thickness of the resulting solid sheet. If too many, such through-holes may significantly impair both the overall structural integrity and the aesthetic appearance of the sheet. If the formed sheet is too thick, not only will it take longer to dry, but it will also result in a solid sheet having a greater variation in pore size between different regions (e.g., top region, middle region, and bottom region) along its thickness, because the longer the drying time, the more unbalanced the forces that may occur through bubble rupture / collapse / coalescence, liquid drainage, pore expansion, pore opening, water evaporation, etc. In addition, multiple layers of relatively thin sheets can be assembled into a three-dimensional structure of greater thickness to deliver the desired cleaning benefits or other benefits while still providing a satisfactory fast-dissolving pore structure and ensuring effective drying in a relatively short drying time.

[0077] Step (D): Drying under Anti-Gravity Heating

[0078] A key feature of the present invention is the use of a counter-gravity heating direction during the drying step for the entire drying time or at least for more than half of the drying time. Without being bound by any theory, it is believed that such a counter-gravity heating direction may reduce or counteract the excessive interstitial liquid drainage towards the bottom region of the formed sheet during the drying step. In addition, since the top surface is dried last, a longer time is allowed for the air bubbles near the top surface of the formed sheet to expand and form pore openings on the top surface (because once the wet matrix dries, the air bubbles can no longer expand or form surface openings). Thus, the solid sheet formed by drying with such counter-gravity heating is characterized by an improved OCF structure, which enables faster dissolution and other surprising and unexpected benefits.

[0079] In one specific embodiment, the counter-gravity heating direction is provided by a conduction-based heating / drying device, which is in Figure 4The same or similar as shown. For example, an inflated wet premix can be cast into a mold to form a sheet having two opposite sides. The mold can then be placed on a hot plate or a heated moving belt or any other suitable heating device having a planar heating surface, characterized by a controlled surface temperature of about 80°C to about 170°C, preferably about 90°C to about 150°C, more preferably about 100°C to about 140°C. Thermal energy is transferred via conduction from the planar heating surface to the bottom surface of the inflated wet premix sheet, such that the curing of the sheet starts from the bottom region and gradually moves upward to finally reach the top region. To ensure that the heating direction is mainly anti-gravitational (i.e., substantially offset from the direction of gravity) during this process, it is preferred that the heating surface is the main heat source for the sheet during drying. If there are any other heat sources, the overall heating direction can be changed accordingly. More preferably, the heating surface is the only heat source for the sheet during drying.

[0080] In another specific embodiment, the anti-gravitational heating direction is provided by a rotating drum-based heating / drying device, which is also known as drum drying or rotary drying, similar to Figure 5 shown. Drum drying is a contact drying method that is used to dry the liquid of a viscous premix from raw materials on the outer surface of a heated rotatable drum (also called a drum or cylinder) at a relatively low temperature to form a sheet-like product. This is a continuous drying method, especially suitable for large-volume drying. Since drying is carried out via contact heating / drying at a relatively low temperature, it generally has high energy efficiency and does not adversely affect the compositional integrity of the raw materials.

[0081] The rotatable cylinder for heating used in drum drying is heated internally, for example, by steam or electricity, and is rotated at a predetermined rotational speed by an electric drive mounted on a pedestal bracket. The heated rotatable cylinder or drum preferably has an outer diameter in the range of about 0.5 m to about 10 m, preferably about 1 m to about 5 m, more preferably about 1.5 m to about 2 m. It can have a controlled surface temperature of about 80°C to about 170°C, preferably about 90°C to about 150°C, more preferably about 100°C to about 140°C. In addition, such a heated rotatable cylinder rotates at a speed of about 0.005 rpm to about 0.25 rpm, preferably about 0.05 rpm to about 0.2 rpm, more preferably about 0.1 rpm to about 0.18 rpm.

[0082] The heated rotatable cylinder is preferably coated with a non-stick coating on its outer surface. The non-stick coating can cover the outer surface of the heated rotatable drum, or it can be fixed to the medium on the outer surface of the heated rotatable drum. The medium includes but is not limited to heat-resistant non-woven fabrics, heat-resistant carbon fibers, heat-resistant metal or non-metal meshes, etc. The non-stick coating can effectively maintain the structural integrity of the sheet-like product from being damaged during the sheet formation process.

[0083] An inlet mechanism is also provided on the base bracket for adding the above-described aerated wet raw material premix onto the heated rotatable drum, thereby forming a thin layer of viscous premix on the outer surface of the heated rotatable drum. Thus, such a thin layer of premix is dried by the heated rotatable drum via contact heating / drying. The inlet mechanism includes a feed chute mounted on the base bracket, and the feed chute has at least one (preferably two) feed hoppers mounted thereon, an imaging device for dynamically observing the feed, and an adjustment device for adjusting the position and tilt angle of the feed hoppers. By using the adjustment device to adjust the distance between the feed hoppers and the outer surface of the heated rotatable drum, the need for different thicknesses of the formed sheet-like product can be met. The adjustment device can also be used to adjust the feed hoppers to different tilt angles to meet the material requirements of speed and quality. The feed chute may also include a spinning bar for stirring the wet premix therein to avoid phase separation and sedimentation before the wet premix is coated onto the outer surface of the heated rotatable cylinder. As described above, such a spinning bar can also be used to aerate the wet premix as needed.

[0084] A heating hood can also be mounted on the base bracket to prevent rapid heat dissipation. The heating hood can also effectively save the energy required for the heated rotatable drum, thereby achieving reduced energy consumption and cost savings. The heating hood is of a modular assembly structure or an integrated structure and can be freely removed from the base bracket. A suction device is also mounted on the heating hood for sucking hot steam to prevent any condensed water from falling onto the forming sheet-like product.

[0085] An optional static scraping mechanism can also be mounted on the base bracket for scraping or shoveling up the sheet-like product that has been formed by the heated rotatable drum. The static scraping mechanism can be mounted on the base bracket or on one side thereof for conveying the already formed sheet-like product downstream for further processing. The static scraping mechanism can be moved automatically or manually closer to and away from the heated rotatable drum.

[0086] The preparation method of the flexible porous soluble solid sheet of the present invention is as follows. First, a heated rotatable drum with a non-stick coating on the base support is driven by an electric drive. Next, the adjusting device adjusts the feeding mechanism so that the distance between the feeding hopper and the outer surface of the heated rotatable drum reaches a preset value. At the same time, the feeding hopper adds an aerated wet premix containing all or some of the raw materials for preparing the flexible porous soluble solid sheet onto the outer surface of the heated rotatable drum to form a thin layer of aerated wet premix with a desired thickness as described in the previous part above. Optionally, the suction device of the heating hood sucks the hot steam generated by the heated rotatable drum. Next, the static scraping mechanism scrapes / shovels up the dried / cured sheet, which is formed from the thin layer of aerated wet premix after being dried by the heated rotatable drum at a relatively low temperature (e.g., 130 °C). In the absence of such a static scraping mechanism, the dried / cured sheet can also be peeled off manually or automatically and then rolled up by a roller bar.

[0087] The total drying time in the present invention depends on the formulation and solid content in the wet premix, the drying temperature, the heat energy inflow, and the thickness of the sheet to be dried. Preferably, the drying time is about 1 minute to about 60 minutes, preferably about 2 minutes to about 30 minutes, more preferably about 2 minutes to about 15 minutes, still more preferably about 2 minutes to about 10 minutes, and most preferably about 2 minutes to about 5 minutes.

[0088] During such a drying time, the heating direction is arranged such that it is substantially opposite to the direction of gravity for more than half of the drying time, preferably more than 55% or 60% of the drying time (e.g., in the heating / drying device based on a rotating drum as described above), more preferably more than 75% or even 100% of the drying time (e.g., in the heating / drying device based on bottom conduction as described above). In addition, the aerated wet premix sheet can be dried in a first heating direction for a first duration and then dried in a second opposite heating direction for a second duration, where the first heating direction is substantially opposite to the direction of gravity and the first duration is 51% to 99% of the total drying time (e.g., 55%, 60%, 65%, 70% to 80%, 85%, 90% or 95%). Such a change in the heating direction can be easily achieved by various other devices not shown herein, for example, by an elongated heating belt in a serpentine shape that can rotate along the longitudinal central axis.

[0089] IV. Physical Properties of the Solid Sheets

[0090] The flexible porous soluble solid sheet formed by the above processing steps is characterized by an improved pore structure that allows water to more easily enter the sheet and makes the sheet dissolve in water faster. Such an improved pore structure is mainly achieved by adjusting various processing conditions as described above, and they are relatively independent or less affected by the chemical agents or specific components used to prepare such sheets.

[0091] Generally, the characteristics of such solid sheets may be: (i) the percentage of open pores is about 80% to 100%, preferably about 85% to 100%, more preferably about 90% to 100%, as measured by Test 3 below; and (ii) the overall average pore size is about 100 μm to about 2000 μm, preferably about 150 μm to about 1000 μm, more preferably about 200 μm to about 600 μm, as measured by the Micro-CT method described in Test 2 below. The overall average pore size defines the porosity of the OCF structure of the present invention. The percentage of open pores defines the interconnectivity between the pores in the OCF structure of the present invention. The interconnectivity of the OCF structure can also be described by the star volume or structure model index (SMI) disclosed in WO2010077627 and WO2012138820.

[0092] Such solid sheets of the present invention have opposite top and bottom surfaces, and the top surface thereof may be characterized in that the surface average pore size is greater than about 100 μm, preferably greater than about 110 μm, preferably greater than about 120 μm, more preferably greater than about 130 μm, most preferably greater than about 150 μm, as measured by the SEM method described in Test 1 below. When compared with solid sheets formed by conventional heating / drying devices (e.g., convection-based, microwave-based, or impingement oven-based devices), the solid sheets formed by the improved heating / drying device of the present invention have a significantly larger surface average pore size at their top surface (as shown in Figures 6A to 6B and Figures 7A to 7B and described in detail in Example 1 below), because under the specially arranged directional heating of the present invention, the top surface of the formed inflated wet premix sheet is the last to be dried / cured, and the bubbles near the top surface have the longest expansion time and form larger pore openings at the top surface.

[0093] Furthermore, the solid sheet formed by the improved heating / drying (e.g., rotary drum-based heating / drying) device of the present invention is characterized by a more uniform pore size distribution between different regions along its thickness direction as compared to a sheet formed by other heating / drying devices (e.g., impact oven-based). Specifically, the solid sheet of the present invention includes a top region adjacent to the top surface, a bottom region adjacent to the bottom surface, and an intermediate region therebetween, with the top, intermediate, and bottom regions all having the same thickness. Each of the top, intermediate, and bottom regions of such a solid sheet is characterized by an average pore size, and the ratio of the average pore size of the bottom region to the average pore size of the top region (i.e., bottom-to-top average pore size ratio) is from about 0.6 to about 1.5, preferably from about 0.7 to about 1.4, preferably from about 0.8 to about 1.3, more preferably from about 1 to about 1.2. In contrast, a solid sheet formed by an impact oven-based heating / drying device can have a bottom-to-top average pore size ratio greater than 1.5, typically about 1.7 - 2.2 (as shown in Example 1 below). Additionally, the solid sheet of the present invention can be characterized in that the bottom-to-intermediate average pore size ratio is from about 0.5 to about 1.5, preferably from about 0.6 to about 1.3, more preferably from about 0.8 to about 1.2, most preferably from about 0.9 to about 1.1, and the intermediate-to-top average pore size ratio is from about 1 to about 1.5, preferably from about 1 to about 1.4, more preferably from about 1 to about 1.2.

[0094] Furthermore, the relative standard deviation (RSTD) between the average pore sizes in the top, intermediate, and bottom regions of the solid sheet of the present invention does not exceed 20%, preferably does not exceed 15%, more preferably does not exceed 10%, and most preferably does not exceed 5%. In contrast, a solid sheet formed by an impact oven-based heating / drying device can have a relative standard deviation (RSTD) between the top / intermediate / bottom average pore sizes that exceeds 20%, may exceed 25% or even exceed 35% (as shown in Example 1 below).

[0095] Preferably, the solid sheet of the present invention is further characterized in that the average pore wall thickness is from about 5 μm to about 200 μm, preferably from about 10 μm to about 100 μm, more preferably from about 10 μm to about 80 μm, as measured by Test 2 below.

[0096] The solid sheet of the present invention may contain a small amount of water. Preferably, it is characterized in that the final water content is 0.5% to 25%, preferably 1% to 20%, more preferably 3% to 10% by weight of the solid sheet, as measured by Test 4 below. The appropriate final water content in the resulting solid sheet can ensure the desired flexibility / deformability of the sheet and provide a soft / smooth sensory feeling for the consumer. If the final water content is too low, the sheet may be too brittle or too hard. If the final water content is too high, the sheet may be too sticky and its overall structural integrity may be impaired.

[0097] The solid sheet of the present invention may have a thickness in the range of about 0.6 mm to about 3.5 mm, preferably about 0.7 mm to about 3 mm, more preferably about 0.8 mm to about 2 mm, and most preferably about 1 mm to about 2 mm. The thickness of the solid sheet can be measured using Test 6 described below. The solid sheet after drying may be slightly thicker than the inflated wet premix sheet due to pore expansion and subsequent overall volume expansion.

[0098] The solid sheet of the present invention may also be characterized in that the basis weight is about 50 g / m 2 to about 500 g / m 2 、preferably about 150 g / m 2 to about 450 g / m 2 、more preferably about 250 g / m 2 to about 400 g / m 2 , as measured by Test 6 described below.

[0099] In addition, the solid sheet of the present invention may have a density in the range of about 0.05 g / cm 3 to about 0.5 g / cm 3 、preferably about 0.06 g / cm 3 to about 0.4 g / cm 3 、more preferably about 0.07 g / cm 3 to about 0.2 g / cm 3 、most preferably about 0.08 g / cm 3 to about 0.15 g / cm 3 range, as measured by Test 7 below. The density of the solid sheet of the present invention is lower than that of the inflated wet premix sheet, which is also due to pore expansion and subsequent overall volume expansion.

[0100] In some embodiments, the solid sheet of the present invention may have about 0.06 g / cm 3 to about 0.16 g / cm 3 、preferably about 0.07 g / cm 3 to about 0.15 g / cm 3 、more preferably about 0.08 g / cm3 to about 0.145 g / cm 3 of density. A solid article containing a sheet with such a relatively low density can achieve even more improved leakage performance.

[0101] In addition, the solid sheet of the present invention may be characterized in that the specific surface area is about 0.03 m 2 / g to about 0.25 m 2 / g, preferably about 0.04 m 2 / g to about 0.22 m 2 / g, more preferably 0.05 m 2 / g to 0.2 m 2 / g, most preferably 0.1 m 2 / g to 0.18 m 2 / g, as measured by Test 8 described below. The specific surface area of the solid sheet of the present invention can represent its porosity and can affect its dissolution rate. For example, the larger the specific surface area, the more pores the sheet has and the faster its dissolution rate.

[0102] In a preferred embodiment, the solid sheet according to the present disclosure and / or the soluble solid article according to the present disclosure is characterized in that:

[0103] · The percentage of open pores is 85% to 100%, preferably 90% to 100%; and / or

[0104] · The overall average pore size is 150 μm to 1000 μm, preferably 200 μm to 600 μm; and / or

[0105] · The average pore wall thickness is 5 μm to 200 μm, preferably 10 μm to 100 μm, more preferably 10 μm to 80 μm; and / or

[0106] · The final water content is 0.5% to 25% by weight of the solid sheet article, preferably 1% to 20%, more preferably 3% to 10%; and / or

[0107] · The thickness is 0.6 mm to 3.5 mm, preferably 0.7 mm to 3 mm, more preferably 0.8 mm to 2 mm, most preferably 1 mm to 1.5 mm; and / or

[0108] · The basis weight is about 50 g / m 2 to about 500 g / m 2 , preferably about 150 g / m 2 to about 450 g / m 2 , more preferably about 250 g / m 2 to about 400 g / m 2 ; and / or

[0109] · With a density of 0.05 g / cm 3 to 0.5 g / cm 3 Preferably 0.06 g / cm 3 to 0.4 g / cm 3 More preferably 0.07 g / cm 3 to 0.2 g / cm 3 Most preferably 0.08 g / cm 3 to 0.15 g / cm 3 ; and / or

[0110] · With a specific surface area of 0.03 m 2 / g to 0.25 m 2 / g, preferably 0.04 m 2 / g to 0.22 m 2 / g, more preferably 0.05 m 2 / g to 0.2 m 2 / g, most preferably 0.1 m 2 / g to 0.18 m 2 / g.

[0111] V. Formulation of the Solid Sheets

[0112] 1. Water-Soluble Polymer

[0113] As mentioned above, the flexible porous soluble solid sheet of the present invention can be formed from a wet premix comprising a water-soluble polymer and a first surfactant. Such water-soluble polymers can be used as film formers, structurants, and carriers for other active ingredients (e.g., surfactants, emulsifiers, builders, chelating agents, fragrances, colorants, etc.) in the resulting solid sheet.

[0114] Preferably, the wet premix can contain from about 3% to about 20% by weight of the water-soluble polymer based on the weight of the premix, in one embodiment from about 5% to about 15% by weight of the water-soluble polymer based on the weight of the premix, and in one embodiment from about 7% to about 10% by weight of the water-soluble polymer based on the weight of the premix.

[0115] After drying, it is preferred that the water-soluble polymer is present in the flexible porous soluble solid sheet of the present invention in an amount in the range of from about 5% to about 50%, preferably from about 8% to about 40%, more preferably from about 10% to about 30%, and most preferably from about 11% to about 25% based on the total weight of the solid sheet. In a particularly preferred embodiment of the present invention, the total amount of the water-soluble polymer present in the flexible porous soluble solid sheet of the present invention does not exceed 25% based on the total weight of such sheet.

[0116] Water-soluble polymers suitable for practicing the present invention can be selected from those having a weight-average molecular weight in the range of from about 50,000 Daltons to about 400,000 Daltons, preferably from about 60,000 Daltons to about 300,000 Daltons, more preferably from about 70,000 Daltons to about 200,000 Daltons, and most preferably from about 80,000 Daltons to about 150,000 Daltons. The weight-average molecular weight is calculated by summing the products of the average molecular weight of each polymer raw material and their respective relative weight percentages based on the total weight of the polymer present in the porous solid sheet. The weight-average molecular weight of the water-soluble polymers used herein can affect the viscosity of the wet premix, which in turn can affect the number and size of the bubbles during the gas injection step and the pore expansion / opening results during the drying step. In addition, the weight-average molecular weight of the water-soluble polymer can affect the overall film-forming properties of the wet premix and its compatibility / incompatibility with specific surfactants.

[0117] The water-soluble polymers of the present invention can include, but are not limited to, synthetic polymers, including polyvinyl alcohol, polyvinylpyrrolidone, polyalkylene oxides, polyacrylates, caprolactam, polymethacrylates, polymethyl methacrylate, polyacrylamides, polymethacrylamides, polydimethylacrylamides, polyethylene glycol monomethacrylate, copolymers of acrylic acid and methyl acrylate, polyurethanes, polycarboxylic acids, polyvinyl acetate, polyesters, polyamides, polyamines, polyethyleneimine, maleic acid / (acrylate or methacrylate) copolymers, copolymers of methyl vinyl ether and maleic anhydride, copolymers of vinyl acetate and crotonic acid, copolymers of vinyl pyrrolidone and vinyl acetate, copolymers of vinyl pyrrolidone and caprolactam, vinyl pyrrolidone / vinyl acetate copolymers, copolymers of anionic, cationic, and amphoteric monomers, and combinations thereof.

[0118] The water-soluble polymers of the present invention can also be selected from polymers derived from natural sources, including those of plant origin, examples of which include karaya gum, tragacanth gum, gum arabic, acetylmorphine, konjac glucomannan, acacia gum, dava gum, whey protein isolate, and soy protein isolate; seed extracts, including guar gum, locust bean gum, bayberry seeds, and psyllium seeds; seaweed extracts such as carrageenan, alginate, and agar; fruit extracts (pectin); those of microbial origin, including xanthan gum, gellan gum, pullulan, hyaluronic acid, chondroitin sulfate, and dextran; and those of animal origin, including casein, gelatin, keratin, keratin hydrolysates, sulfo-keratin, albumin, collagen, gluten, glucagon, glutenin, zein, and shellac.

[0119] Modified natural polymers can also be used as the water-soluble polymers of the present invention. Suitable modified natural polymers include, but are not limited to, cellulose derivatives such as hydroxypropyl methylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, methylcellulose, hydroxypropylcellulose, ethylcellulose, carboxymethylcellulose, cellulose acetate phthalate, nitrocellulose, and other cellulose ethers / esters; and guar gum derivatives such as hydroxypropyl guar gum.

[0120] The water-soluble polymers of the present invention may include starch. As used herein, the term "starch" includes naturally occurring or modified starch. Typical natural sources of starch may include grains, tubers, roots, legumes, and fruits. More specific natural sources may include corn, peas, potatoes, bananas, barley, wheat, rice, sago, amaranth, cassava, arrowroot, canna, sorghum, and their waxy or high-amylase varieties. Natural starch can be modified by any modification method known in the art to form modified starch, including physically modified starch such as shear starch or heat-inhibited starch; chemically modified starch such as those that have been cross-linked, acetylated, and organo-esterified, hydroxyethylated and hydroxypropylated, phosphorylated, and inorgano-esterified, their cationic, anionic, nonionic, amphoteric, and zwitterionic derivatives, and their succinate and substituted succinate derivatives; conversion products derived from any of the starches, including fluid starch or thin-boiling starch prepared by oxidation, enzymatic conversion, acid hydrolysis, heating, or acid dextrinization, products that have been heat-treated and / or sheared can also be used herein; and pregelatinized starch known in the art.

[0121] Preferred water-soluble polymers of the present invention include polyvinyl alcohol, polyvinylpyrrolidone, polyalkylene oxides, starch and starch derivatives, pullulan, gums, hydroxypropyl methylcellulose, methylcellulose, and carboxymethylcellulose. More preferred water-soluble polymers of the present invention include polyvinyl alcohol and hydroxypropyl methylcellulose.

[0122] The most preferred water-soluble polymer of the present invention is polyvinyl alcohol, which is characterized by a degree of hydrolysis in the range of about 40% to about 100%, preferably about 50% to about 95%, more preferably about 65% to about 92%, and most preferably about 70% to about 90%. Commercially available polyvinyl alcohols include those available under the trade name CELVOL from Celanese Corporation (Texas, USA), including but not limited to CELVOL 523, CELVOL 530, CELVOL 540, CELVOL 518, CELVOL513, CELVOL 508, CELVOL 504; under and POVAL TMThose with trade names obtained from Kuraray Europe GmbH (Frankfurt, Germany); and PVA 1788 (also known as PVA BP17), which is commercially available from various suppliers including Lubon Vinylon Co. (Nanjing, China); and combinations thereof. In a particularly preferred embodiment of the present invention, the flexible porous soluble solid sheet comprises from about 10% to about 25%, more preferably from about 15% to about 23%, by total weight of such article, of polyvinyl alcohol having a weight average molecular weight in the range of 80,000 daltons to about 150,000 daltons and a degree of hydrolysis in the range of about 80% to about 90%.

[0123] In addition to the polyvinyl alcohol mentioned above, single starches or starch combinations can be used as filler materials in an amount that reduces the total amount of water-soluble polymer required, provided that this helps to provide a solid sheet having the desired structure and physical / chemical properties as described herein. However, too much starch can compromise the solubility and structural integrity of the sheet. Thus, in a preferred embodiment of the present invention, it is desirable that the solid sheet comprises no more than 20%, preferably from 0% to 10%, more preferably from 0% to 5%, and most preferably from 0% to 1% starch by weight of the solid sheet.

[0124] 2. First Surfactant

[0125] In addition to the water-soluble polymers described above, the solid sheet of the present invention further comprises a first surfactant. The first surfactant can be used as an emulsifier during the aeration process to produce a sufficient amount of stable bubbles to form the desired OCF structure of the present invention. In addition, the first surfactant can be used as an active ingredient for delivering the desired cleaning benefits.

[0126] In a preferred embodiment of the present invention, the solid sheet comprises a first surfactant selected from the group consisting of: anionic surfactants, nonionic surfactants, cationic surfactants, zwitterionic surfactants, amphoteric surfactants, polymeric surfactants, and any combination thereof. Different surfactants can be selected depending on the desired application of such solid sheet and the desired consumer benefits to be achieved. One advantage of the present invention is that the OCF structure of the solid sheet allows for the incorporation of a high surfactant content while still providing rapid dissolution. Thus, highly concentrated cleaning compositions can be formulated into the solid sheet of the present invention to provide consumers with a new and superior cleaning experience.

[0127] As used herein, the first surfactant can include surfactants in the conventional sense (i.e., those that provide a foaming effect easily visible to the consumer) and emulsifiers (i.e., those that do not provide any foaming properties but are mainly used as processing aids for preparing a stable foam structure). Examples of emulsifiers used as the surfactant component herein include monoglycerides and diglycerides of glycerin, fatty alcohols, polyglycerol esters, propylene glycol esters, sorbitan esters, and other emulsifiers known or otherwise commonly used to stabilize the air interface.

[0128] The total amount of the first surfactant present in the solid sheet of the present invention can be in a wide range of about 5% to about 80%, preferably about 10% to about 70%, more preferably about 30% to about 65% based on the total weight of the solid sheet. Correspondingly, the wet premix can contain about 1% to about 40% surfactant by weight of the wet premix, in one embodiment about 2% to about 35% surfactant by weight of the wet premix, and in one embodiment about 5% to about 30% surfactant by weight of the wet premix.

[0129] In a preferred embodiment of the present invention, the solid sheet of the present invention contains about 30% to about 90%, preferably about 40% to about 80%, more preferably about 50% to about 70% of the first surfactant based on the total weight of the solid sheet. In this case, the wet premix can contain about 10% to about 40% surfactant by weight of the wet premix, in one embodiment about 12% to about 35% surfactant by weight of the wet premix, and in one embodiment about 15% to about 30% surfactant by weight of the wet premix.

[0130] Non-limiting examples of anionic surfactants suitable for use herein include alkyl sulfates and alkyl ether sulfates, sulfated monoglycerides, sulfonated olefins, alkyl aryl sulfonates, primary or secondary alkane sulfonates, alkyl sulfosuccinates, acyl taurates, acyl isethionates, alkyl glyceryl ether sulfonates, sulfonated methyl esters, sulfonated fatty acids, alkyl phosphates, acyl glutamates, acyl sarcosinates, alkyl sulfonates of sulfonic acid, acylated peptides, alkyl ether carboxylates, acyl lactates, anionic fluorinated surfactants, sodium lauroyl glutamate, and combinations thereof.

[0131] A class of anionic surfactants particularly suitable for the practice of the present invention includes C6-C 20 linear alkylbenzene sulfonate (LAS) surfactants. LAS surfactants are well known in the art and can be readily obtained by sulfonating commercially available linear alkylbenzenes. Exemplary C 10 -C 20 linear alkylbenzene sulfonates that can be used in the present invention include C10 -C 20 An alkali metal, alkaline earth metal or ammonium salt of linear alkylbenzene sulfonic acid, and preferably C 11 -C 18 or C 11 -C 14 The sodium, potassium, magnesium and / or ammonium salts of linear alkylbenzene sulfonic acid. More preferably C 12 and / or C 14 The sodium or potassium salt of linear alkylbenzene sulfonic acid, and most preferably C 12 and / or C 14 The sodium salt of linear alkylbenzene sulfonic acid, namely sodium dodecylbenzenesulfonate or sodium tetradecylbenzenesulfonate.

[0132] LAS provides excellent cleaning benefits and is particularly suitable for laundry detergent applications. It has surprisingly and unexpectedly been found in the present invention that when polyvinyl alcohol having a relatively high weight average molecular weight (e.g., from about 50,000 daltons to about 400,000 daltons, preferably from about 60,000 daltons to about 300,000 daltons, more preferably from about 70,000 daltons to about 200,000 daltons, most preferably from about 80,000 daltons to about 150,000 daltons) is used as a film-forming agent and carrier, LAS can be used as the main surfactant, i.e., present in the solid sheet in an amount greater than 50% by weight based on the total surfactant content, without adversely affecting the film-forming properties and the stability of the overall composition. Accordingly, in a specific embodiment of the present invention, LAS is used as the main surfactant in the solid sheet. When present, the amount of LAS in the solid sheet of the present invention can range from about 10% to about 70%, preferably from about 20% to about 65%, more preferably from about 40% to about 60% based on the total weight of the solid sheet.

[0133] Another class of anionic surfactants suitable for the practice of the present invention includes sodium trideceth sulfate (STS), which has a weight-average degree of alkoxylation in the range of from about 0.5 to about 5, preferably from about 0.8 to about 4, more preferably from about 1 to about 3, and most preferably from about 1.5 to about 2.5. Trideceth is a 13-carbon branched alkoxylated hydrocarbon which, in one embodiment, contains on average at least 1 methyl branch per molecule. The STS used in the present invention may include ST(EOxPOy)S, where EOx refers to repeating ethylene oxide units having a repeat number x in the range of 0 to 5, preferably 1 to 4, more preferably 1 to 3, and POy refers to repeating propylene oxide units having a repeat number y in the range of 0 to 5, preferably 0 to 4, more preferably 0 to 2. It should be understood that a material such as ST2S having a weight-average ethoxylation degree of about 2 may, for example, contain significant amounts of molecules having no ethoxylate, 1 mole of ethoxylate, 3 moles of ethoxylate, etc., and the distribution of ethoxylation may be broad, narrow or blocked, which still results in an overall weight-average ethoxylation degree of about 2. STS is particularly suitable for personal cleansing applications, and it has surprisingly and unexpectedly been found in the present invention that when polyvinyl alcohol having a relatively high weight-average molecular weight (e.g., from about 50,000 daltons to about 400,000 daltons, preferably from about 60,000 daltons to about 300,000 daltons, more preferably from about 70,000 daltons to about 200,000 daltons, and most preferably from about 80,000 daltons to about 150,000 daltons) is used as a film-forming agent and carrier, STS can be used as the primary surfactant, i.e., present in the solid sheet in an amount greater than 50% by weight of the total surfactant content, without adversely affecting the film-forming properties and the stability of the overall composition. Accordingly, in a specific embodiment of the present invention, STS is used as the primary surfactant in the solid sheet. When present, the amount of STS in the solid sheet of the present invention may be in the range of from about 10% to about 70%, preferably from about 20% to about 65%, more preferably from about 40% to about 60% by weight of the total weight of the solid sheet.

[0134] Another class of anionic surfactants suitable for the practice of the present invention includes alkyl sulfates. These materials have the corresponding formula ROSO3M, where R is an alkyl or alkenyl group of from about 6 to about 20 carbon atoms, x is from 1 to 10, and M is a water-soluble cation such as ammonium, sodium, potassium and triethanolamine. Preferably, R has from about 6 to about 18, preferably from about 8 to about 16, more preferably from about 10 to about 14 carbon atoms. Previously, due to the un-alkoxylated C6-C 20The compatibility of linear or branched alkyl sulfates (AS) with low molecular weight polyvinyl alcohols (e.g., those having a weight average molecular weight of no more than 50,000 daltons) in terms of film-forming properties and storage stability, such that the alkyl sulfates are considered preferred surfactants in soluble solid sheets, particularly as the main surfactant therein. However, the surprising and unexpected finding of the present invention is that when polyvinyl alcohols having a higher weight average molecular weight (e.g., from about 50,000 daltons to about 400,000 daltons, preferably from about 60,000 daltons to about 300,000 daltons, more preferably from about 70,000 daltons to about 200,000 daltons, most preferably from about 80,000 daltons to about 150,000 daltons) are used as film-forming agents and carriers, other surfactants such as LAS and / or STS can be used as the main surfactant in solid sheets without adversely affecting the film-forming properties and stability of the overall composition. Thus, in a particularly preferred embodiment of the present invention, it is desirable to provide solid sheets having no more than about 20%, preferably from 0% to about 10%, more preferably from 0% to about 5%, and most preferably from 0% to about 1% AS by weight of the solid sheet.

[0135] Another class of anionic surfactants suitable for practicing the present invention includes C6-C 20 linear or branched alkyl alkoxysulfates (AAS). In this class, particularly preferred are linear or branched alkyl ethoxysulfates (AES) having the corresponding formula RO(C2H4O) x SO3M, where R is an alkyl or alkenyl group of from about 6 to about 20 carbon atoms, x is from 1 to 10, and M is a water-soluble cation such as ammonium, sodium, potassium, and triethanolamine. Preferably, R has from about 6 to about 18, preferably from about 8 to about 16, and more preferably from about 10 to about 14 carbon atoms. AES surfactants are generally prepared as condensation products of ethylene oxide and monohydric alcohols having from about 6 to about 20 carbon atoms. The alcohols available can be derived from fats, such as coconut oil or tallow, or can be synthetic. Lauryl alcohol and linear alcohols derived from coconut oil are preferred herein. Such alcohols are reacted with from about 1 to about 10, preferably from about 3 to about 5, and especially about 3 molar portions of ethylene oxide, and the resulting mixture of molecular species (e.g., having an average of 3 moles of ethylene oxide per mole of alcohol) is sulfated and neutralized. Highly preferred AES are those that are mixtures of individual compounds having an average alkyl chain length of from about 10 to about 16 carbon atoms and an average degree of ethoxylation of from about 1 to about 4 moles of ethylene oxide. When present, the amount of AAS in the solid sheets of the present invention can range from about 2% to about 40%, preferably from about 5% to about 30%, and more preferably from about 8% to about 12% by total weight of the solid sheet.

[0136] Other suitable anionic surfactants include water-soluble salts of organic sulfuric acid reaction products having the general formula [R 1 -SO3-M], where R 1 is selected from straight-chain or branched saturated aliphatic hydrocarbon groups having from about 6 to about 20, preferably from about 10 to about 18 carbon atoms; and M is a cation. Preferred are the alkali metal salts and ammonium salts of sulfonated C 10-18 n-alkanes. Other suitable anionic surfactants include olefin sulfonates having from about 12 to about 24 carbon atoms. The α-olefins from which the olefin sulfonates are derived are monoolefins having from about 12 to about 24 carbon atoms, preferably from about 14 to about 16 carbon atoms. Preferably, they are straight-chain olefins.

[0137] Another class of anionic surfactants suitable for use in fabric and home care compositions are the β-alkoxyalkane sulfonates. These compounds have the formula:

[0138]

[0139] wherein R1 is a straight-chain alkyl group having from about 6 to about 20 carbon atoms, R2 is a lower alkyl group having from about 1 (preferably) to about 3 carbon atoms, and M is a water-soluble cation as described above.

[0140] Additional examples of suitable anionic surfactants are the reaction products of fatty acids esterified with hydroxyethanesulfonic acid and neutralized with sodium hydroxide, where the fatty acids are derived from, for example, coconut oil; the sodium or potassium salts of fatty acid amides of methyl aminoethanesulfonate, where the fatty acids are derived from, for example, coconut oil. Still other suitable anionic surfactants are the succinamates, examples of which include disodium N-octadecylsulfosuccinate; diammonium laurylsulfosuccinate; tetrasodium N-(1,2-dicarboxyethyl)-N-octadecylsulfosuccinate; dipentyl ester of sodium sulfosuccinate; dihexyl ester of sodium sulfosuccinate; and dioctyl ester of sodium sulfosuccinate.

[0141] The nonionic surfactants that can be included in the solid sheets of the present invention can be any conventional nonionic surfactants, including but not limited to: alkyl alkoxylated alcohols, alkyl alkoxylated phenols, alkyl polysaccharides (especially alkyl glucosides and alkyl polyglucosides), polyhydroxy fatty acid amides, alkoxylated fatty acid esters, sucrose esters, sorbitan esters and alkoxylated derivatives of sorbitan esters, amine oxides, etc. Preferred nonionic surfactants are those having the formula R 1 (OC2H4) n OH, where R 1 is C8-C 18an alkyl group or an alkylphenyl group, and n is from about 1 to about 80. Particular preference is given to C8-C having a weight-average ethoxylation degree of from about 1 to about 20, preferably from about 5 to about 15, more preferably from about 7 to about 10 18 alkyl ethoxylated alcohols such as those commercially available from Shell nonionic surfactants. Other non-limiting examples of nonionic surfactants that can be used herein include: C6-C 12 alkylphenol alkoxylates, where the alkoxylate units can be ethylene oxide units, propylene oxide units, or mixtures thereof; C 12 -C 18 alcohols and condensates of C6-C 12 alkylphenols with ethylene oxide / propylene oxide block polymers such as those from BASF C 14 -C 22 medium-chain branched alcohols (BA); C 14 -C 22 medium-chain branched alkyl alkoxylates, BAE x where x is from 1 to 30; alkyl polysaccharides, especially alkyl polyglycosides; polyhydroxy fatty acid amides; and ether-capped poly(alkoxylated) alcohol surfactants. Suitable nonionic surfactants also include those sold by BASF under the trade name Those sold.

[0142] In a preferred embodiment, the nonionic surfactant is selected from sorbitan esters and alkoxylated derivatives of sorbitan esters, including sorbitan monolaurate ( 20), sorbitan monopalmitate ( 40), sorbitan monostearate ( 60), sorbitan tristearate ( 65), sorbitan monooleate ( 80), sorbitan trioleate ( 85), sorbitan isostearate, polyoxyethylene (20) sorbitan monolaurate ( 20), polyoxyethylene (20) sorbitan monopalmitate ( 40), polyoxyethylene (20) sorbitan monostearate ( 60), polyoxyethylene (20) sorbitan monooleate ( 80), polyoxyethylene (4) sorbitan monolaurate ( 21), polyoxyethylene (4) sorbitan monostearate ( 61), polyoxyethylene (5) sorbitan monooleate ( 81), and combinations thereof.

[0143] The most preferred nonionic surfactants for use in the practice of the present invention include C6-C with a weight average degree of alkoxylation in the range of 5 to 15 20 linear or branched alkyl alkoxylated alcohols (AA), more preferably C with a weight average degree of alkoxylation in the range of 7 to 9 12 -C 14 linear ethoxylated alcohols. If present, the amount of one or more AA-type nonionic surfactants in the solid sheet of the present invention can be in the range of about 2% to about 40%, preferably about 5% to about 30%, more preferably about 8% to about 12% by total weight of the solid sheet.

[0144] Amphoteric surfactants suitable for use in the solid sheets of the present invention include those widely described as derivatives of aliphatic secondary and tertiary amines, wherein the aliphatic group can be linear or branched, and wherein one of the aliphatic substituents contains from about 8 to about 18 carbon atoms and one aliphatic substituent contains an anionic water-soluble group such as carboxyl, sulfonate, sulfate, phosphate or phosphonate. Examples of compounds falling within this definition are sodium 3-dodecyl-aminopropionate, sodium 3-dodecylaminopropanesulfonate, sodium lauroylsarcosinate, N-alkyl taurines (such as that prepared by the reaction of dodecylamine with sodium hydroxyethylsulfonate) and N-higher alkyl aspartic acids.

[0145] A class of amphoteric surfactants particularly suitable for incorporation into solid sheets having personal care applications (such as shampoos, facial or body cleansers, etc.) includes alkyl amphoacetates, such as lauroyl amphoacetate and coco amphoacetate. Alkyl amphoacetates can consist of monoacetates and diacetates. In some types of alkyl amphoacetates, the diacetate is an impurity or an unintended reaction product. If present, the amount of one or more alkyl amphoacetates in the solid sheet of the present invention can be in the range of about 2% to about 40%, preferably about 5% to about 30%, more preferably about 10% to about 20% by total weight of the solid sheet.

[0146] Suitable zwitterionic surfactants include those widely described as derivatives of aliphatic quaternary ammonium, phosphonium and sulfonium compounds, wherein the aliphatic group can be linear or branched, and wherein one of the aliphatic substituents contains from about 8 to about 18 carbon atoms and one aliphatic substituent contains an anionic group such as carboxyl, sulfonate, sulfate, phosphate or phosphonate. Such suitable zwitterionic surfactants can be represented by the following formula:

[0147]

[0148] wherein R 2an alkyl, alkenyl or hydroxyalkyl group containing from about 8 to about 18 carbon atoms, from 0 to about 10 ethylene oxide moieties, and from 0 to about 1 glycerol moiety; Y is selected from nitrogen, phosphorus and sulfur atoms; R 3 is an alkyl or mono-hydroxyalkyl group containing from about 1 to about 3 carbon atoms; when Y is a sulfur atom, X is 1, and when Y is a nitrogen or phosphorus atom, X is 2; R 4 is an alkylene or hydroxyalkylene of from about 1 to about 4 carbon atoms, and Z is a group selected from the following: carboxylate, sulfonate, sulfate, phosphonate and phosphate groups.

[0149] Other zwitterionic surfactants suitable for use herein include betaines, which include higher alkyl betaines such as coco dimethyl carboxymethyl betaine, cocoamidopropyl betaine, coco betaine, lauramidopropyl betaine, oleyl betaine, lauryl dimethyl carboxymethyl betaine, lauryl dimethyl α-carboxyethyl betaine, cetyl dimethyl carboxymethyl betaine, lauryl bis-(2-hydroxyethyl) carboxymethyl betaine, stearyl bis-(2-hydroxypropyl) carboxymethyl betaine, oleyl dimethyl γ-carboxypropyl betaine, and lauryl bis-(2-hydroxypropyl) α-carboxyethyl betaine. Sulfobetaines may be represented by: coco dimethyl sulfopropyl betaine, stearyl dimethyl sulfopropyl betaine, lauryl dimethyl sulfoethyl betaine, lauryl bis-(2-hydroxyethyl) sulfopropyl betaine, etc.; amido betaines and amido sulfobetaines, wherein the RCONH(CH2)3 group (wherein R is C 11 -C 17 alkyl) is attached to the nitrogen atom of the betaine and may also be used in the present invention.

[0150] Cationic surfactants may also be used in the present invention, especially in fabric softener and hair conditioning products. When used in the preparation of products containing a cationic surfactant as the main surfactant, it is preferred that such cationic surfactants be present in an amount in the range of from about 2% to about 30%, preferably from about 3% to about 20%, more preferably from about 5% to about 15% by weight of the total weight of the solid sheet.

[0151] Cationic surfactants may include DEQA compounds, which include descriptions of diamido active substances and active substances having a mixture of amide and ester bonds. Preferred DEQA compounds are usually prepared by the reaction of alkanolamines such as MDEA (methyldiethanolamine) and TEA (triethanolamine) with fatty acids. Some substances usually produced by such reactions include N,N-bis(acyloxyethyl)-N,N-dimethylammonium chloride, or N,N-bis(acyloxyethyl)-N,N-methylethyl hydroxyethyl methyl sulfate ammonium, wherein the acyl groups are derived from animal fats, unsaturated and polyunsaturated fatty acids.

[0152] Other suitable active substances for use as cationic surfactants include reaction products of fatty acids with di-alkylenetriamines in a molar ratio of, for example, about 2:1, the reaction products comprising compounds of the formula:

[0153] R 1 -C(O)-NH-R 2 -NH-R 3 -NH-C(O)-R 1

[0154] wherein R 1 and R 2 are as defined above, and each R 3 is an alkylene group, preferably a diethylene group. Examples of these active substances are the reaction products of tallow acid, rapeseed oleic acid or oleic acid with diethylenetriamine in a molar ratio of about 2:1, the reaction product mixtures comprising N,N"-ditallowoyl diethylenetriamine, N,N"-dirapeseed oleoyl diethylenetriamine or N,N"-dioleoyl diethylenetriamine of the formula: 1-6

[0155] R 1 -C(O)-NH-CH2CH2-NH-CH2CH2-NH-C(O)-R 1

[0156] wherein R 2 and R 3 are divalent ethylene groups, R 1 is as defined above, and when R 1 is an oleoyl group from commercially available oleic acid of plant or animal origin, acceptable examples of this structure include 223LL or 7021 from Henkel Corporation.

[0157] Another active substance that can be used as a cationic surfactant has the formula:

[0158] [R 1 -C(O)-NR-R 2 -N(R)2-R 3 -NR-C(O)-R 1 + X -

[0159] wherein R, R 1 and R 2 and R 3 and X - are as defined above. An example of this active substance is a softener based on di-fatty amidoamine of the formula:​

[0160] [R 1 -C(O)-NH-CH2CH2-N(CH3)(CH2CH2OH)-CH2CH2-NH-C(O)-R 1 + CH3SO4 -

[0161] wherein R 1 -C(O) is an oleoyl group, a tallow group or a hardened tallow group obtained commercially from Degussa under the trade names 222LT, 222 and 110, respectively.

[0162] A second class of DEQA ("DEQA(2)") suitable for use as an active substance as a cationic surfactant has the general formula:

[0163] [R3N + CH2CH(YR 1 )(CH2YR 1 )]X -

[0164] where each Y, R, R 1 and X - has the same meaning as above. An example of a preferred DEQA(2) is the "propyl" ester quaternary fabric softening agent active substance having the formula 1,2-bis(acyloxy)-3-trimethylpropylammonium chloride.

[0165] Suitable polymeric surfactants for use in the personal care compositions of the present invention include, but are not limited to, block copolymers of ethylene oxide and fatty alkyl residues, block copolymers of ethylene oxide and propylene oxide, hydrophobically modified polyacrylates, hydrophobically modified celluloses, siloxane polyethers, siloxane copolyol esters, polydimethylsiloxane bisquaternary salts, and co-modified amino / polyether siloxanes.

[0166] In a preferred embodiment, the first surfactant may be selected from C6-C 20 linear alkylbenzene sulfonates (LAS), C6-C 20 linear or branched alkyl alkoxysulfates (AAS) having a weight average degree of alkoxylation in the range of 0.5 to 10, C6-C 20 linear or branched alkyl alkoxylated alcohols (AA) having a weight average degree of alkoxylation in the range of 5 to 15, C6-C 20 linear or branched alkyl sulfates (AS), and any combination thereof.

[0167] 3. Plasticizer ​

[0168] In a preferred embodiment of the present invention, the flexible porous soluble solid sheet of the present invention may further comprise a plasticizer in an amount preferably in the range of from about 0.1% to about 25%, preferably from about 0.5% to about 20%, more preferably from about 1% to about 15%, and most preferably from 2% to 12% based on the total weight of the solid sheet. Correspondingly, the wet premix for forming such solid sheets may comprise from about 0.02% to about 20% of a plasticizer by weight of the wet premix, from about 0.1% to about 10% of a plasticizer by weight of the wet premix in one embodiment, and from about 0.5% to about 5% of a plasticizer by weight of the wet premix in one embodiment.

[0169] Suitable plasticizers for use in the present invention include, for example, polyols, copolyols, polycarboxylic acids, polyesters, polydimethylsiloxane copolyols, and the like.

[0170] Examples of polyols that can be used include, but are not limited to: glycerol, diglycerol, ethylene glycol, polyethylene glycol (especially 200 to 600), propylene glycol, butylene glycol, pentylene glycol, glycerol derivatives (such as propoxylated glycerol), glycidol, cyclohexanedimethanol, hexanediol, 2,2,4-trimethylpentane-1,3-diol, pentaerythritol, urea, sugar alcohols (such as sorbitol, mannitol, lactitol, xylitol, maltitol and other monohydric and polyhydric alcohols), monosaccharides, disaccharides and oligosaccharides (such as fructose, glucose, sucrose, maltose, lactose, high fructose corn syrup solids and dextrin), ascorbic acid, sorbate, ethylenedimethanamide, amino acids, and the like.

[0171] Examples of polycarboxylic acids include, but are not limited to, citric acid, maleic acid, succinic acid, polyacrylic acid, and polymaleic acid.

[0172] Examples of suitable polyesters include, but are not limited to, glyceryl triacetate, acetylated monoglycerol, diethyl phthalate, triethyl citrate, tributyl citrate, acetyltriethyl citrate, and acetyltributyl citrate.

[0173] Examples of suitable polydimethylsiloxane copolyols include, but are not limited to, PEG-12 polydimethylsiloxane, PEG / PPG-18 / 18 polydimethylsiloxane, and PPG-12 polydimethylsiloxane.

[0174] Other suitable plasticizers include, but are not limited to, alkyl phthalates and allyl phthalates; naphthalene esters; lactates (such as sodium, ammonium, and potassium salts); polyoxyethylene sorbitan-30; urea; lactic acid; sodium pyrrolidone carboxylate (PCA); sodium hyaluronate or hyaluronic acid; soluble collagen; modified proteins; monosodium L-glutamate; α and β-hydroxy acids, such as glycolic acid, lactic acid, citric acid, maleic acid, and salicylic acid; polyglyceryl polymethacrylate; polymeric plasticizers, such as polyquaternium; proteins and amino acids, such as glutamic acid, aspartic acid, and lysine; hydrogenated starch hydrolysates; other low molecular weight esters (such as esters of C2-C 10 alcohols and acids); and any other water-soluble plasticizers known to those skilled in the food and plastics industries; and mixtures thereof.

[0175] Particularly preferred examples of plasticizers include glycerol, ethylene glycol, polyethylene glycol, propylene glycol, and mixtures thereof. The most preferred plasticizer is glycerol.

[0176] 4. Additional Ingredients

[0177] In addition to the above ingredients such as water-soluble polymers, surfactants, and plasticizers, the solid sheet of the present invention may contain one or more additional ingredients depending on its intended application. Such one or more additional ingredients may be selected from fabric care active substances, dishwashing active substances, hard surface cleaning active substances, beauty and / or skin care active substances, personal cleaning active substances, hair care active substances, oral care active substances, feminine care active substances, baby care active substances, bittering agents, and any combination thereof. In a preferred embodiment, the solid sheet of the present invention may contain a bittering agent.

[0178] Suitable fabric care active substances include, but are not limited to: organic solvents (linear or branched lower C1-C8 alcohols, diols, glycerol, or ethylene glycol; lower amine solvents, such as C1-C4 alkanolamines, and mixtures thereof; more specifically 1,2-propanediol, ethanol, glycerol, monoethanolamine, and triethanolamine), carriers, hydrotropes, builders, chelating agents, dispersants, enzymes and enzyme stabilizers, catalytic materials, bleaching agents (including photo-bleaching agents) and bleach activators, fragrances (including encapsulated fragrances or fragrance microcapsules), colorants (such as pigments and dyes, including tone dyes), optical brighteners, dye transfer inhibitors, clay soil removal / anti-redeposition agents, structurants, rheology modifiers, defoamers, processing aids, fabric softeners, antimicrobial agents, etc.

[0179] Suitable hair care active substances include, but are not limited to: class II moisture control materials for reducing curl (salicylic acid and derivatives, organic alcohols and esters), cationic surfactants (especially the water-insoluble type having a solubility in water preferably below 0.5 g / 100 g of water, more preferably below 0.3 g / 100 g of water at 25 °C), high melting point aliphatic compounds (e.g., fatty alcohols, fatty acids and mixtures thereof having a melting point of 25 °C or higher, preferably 40 °C or higher, more preferably 45 °C or higher, still more preferably 50 °C or higher), silicone compounds, conditioning agents (such as hydrolyzed collagen sold under the trade name Peptein 2000 by Hormel, vitamin E sold under the trade name Emix-d by Eisai, panthenol from Roche, panthenol ethyl ether from Roche, hydrolyzed keratin, proteins, plant extracts and nutrients), preservatives (such as benzyl alcohol, methyl paraben, propyl paraben and imidazolidinyl urea), pH regulators (such as citric acid, sodium citrate, succinic acid, phosphoric acid, sodium hydroxide, sodium carbonate), salts (such as potassium acetate and sodium chloride), colorants, fragrances or odorants, polyvalent chelating agents (such as disodium ethylenediaminetetraacetate), UV and infrared shielding and absorbing agents (such as octyl salicylate), hair bleaches, hair waving agents, hair setting agents, antidandruff agents, antimicrobial agents, hair growth or restorative agents, cosolvents or other additional solvents, etc.

[0180] Suitable beauty and / or skin care active substances include those materials recognized for use in cosmetics and described in reference books such as the "CTFA Cosmetic Ingredient Handbook", 2nd Edition (The Cosmetic, Toiletries, and Fragrance Association, Inc. 1988, 1992). Additional non-limiting examples of suitable beauty and / or skin care active substances include preservatives, fragrances or odorants, colorants or dyes, thickeners, humectants, emollients, pharmaceutical active substances, vitamins or nutrients, sunscreens, deodorants, sensates, plant extracts, nutrients, astringents, cosmetic particles, absorbent particles, fibers, anti-inflammatory agents, skin lightening agents, skin color correctors (which act to improve the overall skin tone and may contain vitamin B3 compounds, glycosamines, hexamidine compounds, salicylic acid, 1,3-dihydroxy-4-alkylbenzenes such as hexylresorcinol and retinoids), skin tanning agents, exfoliants, wetting agents, enzymes, antioxidants, free radical scavengers, anti-wrinkle active substances, anti-acne agents, acids, bases, minerals, suspending agents, pH regulators, pigment particles, antimicrobial agents, insect repellents, shaving lotions, cosolvents or other additional solvents, etc.

[0181] Suitable bittering agents include denatonium salts or derivatives thereof. In one aspect, the bittering agent is a denatonium salt selected from the following: denatonium chloride, denatonium citrate, denatonium saccharide, denatonium carbonate, denatonium acetate, denatonium benzoate, and mixtures thereof. In one aspect, the solid sheet contains a first denatonium salt, and the coating composition contains a second denatonium salt different from the first denatonium salt.

[0182] A particularly preferred bittering agent is denatonium benzoate, also known as ammonium phenylmethyl-[2-[(2,6-dimethylphenyl)amino]-2-oxoethyl]-diethylbenzoate, CAS number 3734-33-6. Denatonium benzoate is commercially available under the trade name and is purchased from Macfarlan Smith, Edinburgh, Scotland, UK.

[0183] In some aspects, the bittering agent is a natural bitter substance. In some aspects, the bittering agent has a bitterness value of about 1000 to about 200000. In some aspects, the bittering agent is a natural bitter substance having a bitterness value of about 1000 to about 200000, wherein the natural bitter substance is selected from glycosides, isoprenoids, alkaloids, amino acids, and mixtures thereof. For example, suitable bittering agents also include quercetin (3,3',4',5,7-pentahydroxyflavone); naringin (4',5,7-trihydroxyflavanone-7-rhamnoglucoside); aucubin; amygdalin; dihydrofoliamentin; gentiopicroside; gentiopicrin; swertiamarin; sweroside; gentioflavosid; centaurosid; methiafolin; adenoside; centapikrin; salicin; conduritol; absinthin; anabsinthin; cynaropicrin; lactucin; lactucopicrin; sonchusin; α-thujone; β-thujone; deoxylimonene; limonin; ichangin; iso-obacunoic acid; obacunone; obacunoic acid; nomilin; ichangin; nomilinoic acid; marrubiin; pramarrubin; salvigenin; salvianolic acid; quassin; quinine hydrochloride; quinine sulfate; quinine dihydrochloride; columbine; caffeine; threonine; methionine; phenylalanine; tryptophan; arginine; histidine; valine; aspartic acid; sucrose octaacetate; and mixtures thereof. Other suitable bittering agents include quinine bisulfate and hop extract (e.g., humulone).

[0184] The solid sheet may comprise from about 0.00001% to about 1%, or from about 0.0001% to about 0.5%, or from about 0.001% to about 0.25%, or from about 0.01% to about 0.1% by weight of the solid sheet of a bittering agent. In some aspects, the solid sheet comprises an amount of bittering agent sufficient to provide a bitter taste.

[0185] The solid sheet of the present invention may also comprise other optional ingredients known to be used in or useful in a composition, provided that such optional substances are compatible with the selected basic substances described herein or do not unduly impair the performance of the product.

[0186] Non-limiting examples of types of products that can be formed from the solid sheet of the present invention include laundry detergent products, fabric softening products, hand cleaning products, shampoo or other hair treatment products, body cleaning products, shaving preparation products, dish cleaning products, personal care substrates containing drugs or other skin care actives, moisturizing products, sunscreen products, beauty or skin care products, deodorant products, oral care products, feminine cleaning products, baby care products, scented products, and the like.

[0187] VI. Formulation of the Coating Composition

[0188] The coating composition according to the present disclosure (also referred to herein as "juice") may comprise a second surfactant. The coating composition may have a viscosity of from about 1 cps to about 25,000 cps, preferably from about 2 cps to about 10,000 cps, more preferably from about 3 cps to about 5,000 cps, and most preferably from about 1,000 cps to about 5,000 cps as measured at about 20 °C and 1 s -1 The viscosity value is measured using a Malvern Kinexus Lab+ rheometer with a cone plate geometry (CP1 / 50SR3468 SS), a gap width of 0.054 mm, a temperature of 20 °C, and a shear rate of 1.0 s-1 for a period of 360 seconds.

[0189] 1. Second Surfactant

[0190] The second surfactant can be used as an active ingredient for delivering the desired cleaning benefits. In some embodiments, the second surfactant can be the same as the first surfactant. In other embodiments, the second surfactant can be different from the first surfactant. The second surfactant can be selected from anionic surfactants, nonionic surfactants, cationic surfactants, zwitterionic surfactants, amphoteric surfactants, polymeric surfactants, and any combination thereof. Different surfactants can be selected according to the desired application of the solid article and the desired consumer benefits to be achieved. In a preferred embodiment of the present invention, the second surfactant can include a nonionic surfactant.

[0191] Any of the anionic surfactants, nonionic surfactants, cationic surfactants, zwitterionic surfactants, amphoteric surfactants, and / or polymeric surfactants or any combination thereof listed in the "First Surfactant" section can be used as the second surfactant.

[0192] In a preferred embodiment, the second surfactant can be selected from C6-C 20 linear alkylbenzene sulfonates (LAS), C6-C with a weight-average degree of alkoxylation in the range of 0.5 to 10 20 linear or branched alkyl alkoxysulfates (AAS), C6-C with a weight-average degree of alkoxylation in the range of 5 to 15 20 linear or branched alkyl alkoxylated alcohols (AA), C6-C 20 linear or branched alkyl sulfates (AS), and any combination thereof; and

[0193] In a more preferred embodiment, the second surfactant can include C6-C with a weight-average degree of alkoxylation in the range of 5 to 15 20 linear or branched alkyl alkoxylated alcohols (AA), preferably C with a weight-average degree of alkoxylation in the range of 7 to 9 12 -C 14 linear ethoxylated alcohols.

[0194] Specifically, the coating composition can contain 1% to 95%, preferably 1% to 85%, more preferably 10% to 80%, such as 1%, 2%, 3%, 4%, 5%, 8%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or any range therebetween of the second surfactant based on the total weight of the coating composition.

[0195] 2. Solvent

[0196] The coating composition may further comprise a solvent, which may preferably be selected from glycerol, propylene glycol, 1,3 - propanediol, diethylene glycol, dipropylene glycol, ethanolamine, ethanol, water, and any combination thereof. The solvent may be an organic solvent.

[0197] Specifically, the solvent may be selected from glycerol, diethylene glycol, dipropylene glycol, ethanol, water, and any combination thereof. More specifically, the solvent may be dipropylene glycol. The presence of the solvent in the coating composition may form even more improved dissolution characteristics.

[0198] Specifically, the coating composition may comprise from 0.1% to 99%, preferably from 1% to 70%, more preferably from 2% to 30%, for example 1%, 2%, 3%, 4%, 5%, 8%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or any range therebetween of the solvent based on the total weight of the coating composition.

[0199] Preferably, the coating composition may comprise less than 30%, preferably less than 25%, more preferably less than 20%, still more preferably less than 10%, still more preferably less than 5%, still more preferably less than 3%, still more preferably less than 1%, most preferably less than 0.5%, for example 0.01%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 1%, 2%, 3%, 4%, 5% or any range therebetween of water based on the total weight of the coating composition. The presence of an appropriate amount of water may bring additional beneficial effects, such as to promote attachment between sheets and / or to change rheology and / or to even further improve dissolution.

[0200] 3. Rheology Modifier

[0201] The coating composition may further comprise a rheology modifier, which may preferably be selected from: cellulose and derivatives; guar gum and guar gum derivatives; polyethylene oxide, polypropylene oxide, and POE - PPO copolymers; polyvinylpyrrolidone, crosslinked polyvinylpyrrolidone, and derivatives; polyvinyl alcohol and derivatives; polyethyleneimine and derivatives; finely divided inorganic particles such as sodium carbonate and sodium sulfate; silica; water - swellable clay; and gums. The presence of the rheology modifier may help to change rheology, such as viscosity.

[0202] Specifically, the coating composition may comprise from 0.1% to 95%, preferably from 0.5% to 85%, more preferably from 1% to 50%, such as 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or any range therebetween of a rheology modifier based on the total weight of the coating composition.

[0203] In another embodiment, the rheology modifier may be cellulose and derivatives, non-limiting examples of which include microcrystalline cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, ethyl cellulose, nitrocellulose, cellulose sulfate, cellulose powder, and hydrophobically modified cellulose.

[0204] In one embodiment, the rheology modifier may be guar gum and guar gum derivatives, non-limiting examples of which include hydroxypropyl guar gum and hydroxypropyl guar gum hydroxypropyltrimethylammonium chloride.

[0205] In one embodiment, the rheology modifier may be polyethylene oxide, polypropylene oxide, and POE-PPO copolymers.

[0206] In one embodiment, the rheology modifier may be polyvinylpyrrolidone, crosslinked polyvinylpyrrolidone, and derivatives.

[0207] In another embodiment, the rheology modifier may be polyvinyl alcohol and derivatives.

[0208] In another embodiment, the rheology modifier may be polyethyleneimine and derivatives.

[0209] In another embodiment, the rheology modifier may be silica, non-limiting examples of which include fumed silica, precipitated silica, and silica surface-treated with siloxane.

[0210] In one embodiment, the rheology modifier may be water-swellable clay, non-limiting examples of which include synthetic hectorite, bentonite, montmorillonite, greensand, and lithium montmorillonite.

[0211] In one embodiment, the rheology modifier may be gums, non-limiting examples of which include xanthan gum, guar gum, hydroxypropyl guar gum, gum arabic, tragacanth gum, galactan, yardlong bean gum, karaya gum, and locust bean gum.

[0212] 4. Fragrance

[0213] The coating composition may further comprise a fragrance (e.g., free fragrance, encapsulated fragrance). Preferably, the fragrance may be a free fragrance, a fragrance microcapsule, or any combination thereof. Specifically, the coating composition may comprise from 1% to 99%, preferably from 5% to 90%, more preferably from 10% to 80%, such as 1%, 2%, 3%, 4%, 5%, 8%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or any range therebetween of the fragrance, based on the total weight of the coating composition.

[0214] In some embodiments, the weight ratio of the second surfactant to the fragrance in the coating composition may be from about 1:50 to about 50:1, preferably from about 1:20 to about 20:1, more preferably from about 1:1 to about 10:1, most preferably from about 2:1 to about 8:1, such as 1:10, 1:9, 1:8, 1:7, 1:6, 1:5, 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 15:1, 20:1 or any range therebetween.

[0215] In some embodiments, at least 50%, preferably at least 70%, more preferably at least 90%, most preferably at least 99% of the fragrance in the solid article according to the present disclosure is present in the coating composition. This may result in improved fragrance properties, such as shelf life, fragrance stability, deposition or release benefits.

[0216] 5. Additional Ingredients

[0217] In addition to the above ingredients, the coating composition of the present invention may comprise one or more additional ingredients, depending on its intended application. Such one or more additional ingredients may be selected from fabric care active substances, dishwashing active substances, hard surface cleaning active substances, beauty and / or skin care active substances, personal cleaning active substances, hair care active substances, oral care active substances, feminine care active substances, baby care active substances, bittering agents, and any combination thereof.

[0218] Specifically, the coating composition may further comprise additional ingredients selected from the following: silicones, softeners, bleaches, enzymes, antibacterial agents, antioxidants, optical brighteners, color dyes, polymers, personal care active substances (e.g., emollients, humectants, and conditioners), and any combination thereof.

[0219] The coating composition may comprise from 0.0001% to 99%, preferably from 1% to 95%, more preferably from 10% to 80%, for example 0.001%, 0.01%, 0.1%, 1%, 2%, 3%, 4%, 5%, 8%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or any range therebetween of additional components, based on the total weight of the coating composition.

[0220] VII. Conversion of Multiple Solid Sheets and Coating Composition into a Multilayer Soluble Solid Product Containing the Coating Composition Product

[0221] Once the flexible soluble porous solid sheet of the present invention is formed as described above, two or more such sheets in the sheet can be further combined and / or processed by applying the coating composition to form a soluble solid article of any desired three-dimensional shape, including but not limited to: spherical, cubic, rectangular, oval, cylindrical, rod, sheet, flower-shaped, fan-shaped, star-shaped, disc-shaped, etc. The sheets can be combined and / or processed by any method known in the art, examples of which include but are not limited to chemical methods, mechanical methods, and combinations thereof. Such combination and / or processing steps are collectively referred to herein as the "transformation" process, i.e., it is used to transform two or more flexible soluble porous sheets of the present invention into a soluble solid article comprising the coating composition.

[0222] The surprising and unexpected discovery of the present invention is that the three-dimensional multi-layer solid article comprising the coating composition has significantly improved dissolution characteristics compared to a multi-layer solid article having the same amount of total surfactant but not having the coating composition.

[0223] Furthermore, the multi-layer soluble solid article of the present invention may be characterized by a maximum dimension D and a minimum dimension z (which is perpendicular to the maximum dimension), and the ratio of D / z (hereinafter also referred to as the "aspect ratio") is in the range of 1 to about 10, preferably about 1.4 to about 9, preferably about 1.5 to about 8, more preferably about 2 to about 7. It should be noted that when the aspect ratio is 1, the soluble solid article has a spherical shape. When the aspect ratio is about 1.4, the soluble solid article has a cubic shape. The multi-layer soluble solid article of the present invention may have a minimum dimension z greater than about 3 mm but less than about 20 cm, preferably about 4 mm to about 10 cm, more preferably about 5 mm to about 30 mm.

[0224] The above-described multi-layer soluble solid article may include more than two such flexible soluble porous sheets. For example, it may include from about 4 to about 50, preferably from about 5 to about 40, more preferably from about 6 to about 30 flexible soluble porous sheets. The improved OCF structure of the flexible soluble porous sheets prepared according to the present invention allows many sheets (e.g., 15 to 40) to be stacked together while still providing a satisfactory overall dissolution rate for the stack.

[0225] In a particularly preferred embodiment of the present invention, the multi-layer soluble solid article includes 15 to 40 layers of the above-described flexible soluble porous sheets and has an aspect ratio in the range of about 2 to about 7.

[0226] Specifically, the coating composition can be applied between individual sheets of the multi-layer soluble solid article by any suitable method, such as by spraying, spraying, dusting, coating, spreading, dipping, injection, rolling or even vapor deposition. More specifically, the coating composition can be applied to one or both of the contacting surfaces in the contacting surfaces of adjacent sheets in the stack. In a preferred embodiment, in order to avoid the coating composition interfering with the cut seal or edge seal near the outer periphery of the individual sheets, the coating composition can be applied to the central region in each coated surface of the corresponding sheet, which central region is preferably defined as a region spaced apart from the outer periphery of such adjacent sheets by a distance that is at least 5%, preferably at least 10%, more preferably at least 15%, most preferably at least 20% of the maximum dimension D. In an alternative preferred embodiment, the coating composition is applied to the entire coated surface of the corresponding sheet, preferably wherein the coated area accounts for at least 90%, preferably 95%, more preferably 98%, most preferably 99% of the total area of the coated surface.

[0227] In a preferred embodiment, the coating composition can be applied to one or both of the contacting surfaces of any adjacent sheets in the solid article. In another preferred embodiment, the coating composition can be applied to one or both of the contacting surfaces of the two middle sheets in the stack. In another preferred embodiment, the coating composition can be applied to one or both of the contacting surfaces in the contacting surfaces of any two adjacent sheets in the stack, except for the two outermost sheets.

[0228] As used herein, the term "middle two sheets" means two adjacent sheets located in the middle of a sequence of sheets stacked together. Specifically, if the total number of sheets is odd (e.g., 7), the middle two sheets include the middle sheet and any one of its two adjacent sheets (e.g., the 3rd sheet and the 4th sheet or the 4th sheet and the 5th sheet); and if the total number of sheets is even (e.g., 6), the middle two sheets include the two middle sheets (e.g., the 3rd sheet and the 4th sheet).

[0229] The multi-layer soluble solid article may contain 0.1% to 90%, preferably 1% to 80%, more preferably 5% to 70%, and most preferably 10% to 60%, such as 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90% or any range therebetween of the coating composition, based on the total weight of the article.

[0230] The multi-layer soluble solid article may contain 10% to 99.9%, preferably 20% to 99%, more preferably 30% to 95%, and most preferably 40% to 90%, such as 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99% or any range therebetween of the solid sheets, based on the total weight of the article.

[0231] The multi-layer soluble solid article of the present invention may include individual sheets of different colors that may be seen from the outer surface (e.g., one or more side surfaces) of such an article. Such visible sheets of different colors are aesthetically pleasing to consumers. In addition, the different colors of the individual sheets may provide visual cues indicating different beneficial agents contained in the individual sheets. For example, the multi-layer soluble solid article may include a first sheet having a first color and containing a first beneficial agent and a second sheet having a second color and containing a second beneficial agent, where the first color provides a visual cue indicating the first beneficial agent and the second color provides a visual cue indicating the second beneficial agent.

[0232] Test Methods

[0233] Test 1: Scanning Electron Microscopy (SEM) Method for Determining the Average Surface Pore Size of the Sheet Product

[0234] SEM micrographs of the samples were obtained using a Hitachi TM3000 benchtop microscope (S / N: 123104-04). Samples of the solid sheet products of the present invention had a sample area of approximately 1 cm × 1 cm and were cut from larger sheets. Images were collected at a magnification of 50×, and the unit was operated at 15 kV. At least 5 micrograph images were collected from randomly selected positions on each sample, resulting in a total analysis area of approximately 43.0 mm 2 to estimate the average pore size on each sample.

[0235] The SEM micrographs were then processed first using the Image Analysis Toolbox in Matlab. If needed, the images were converted to grayscale. For a given image, the "imhist" Matlab function was used to generate a histogram of the intensity values of each individual pixel. Typically, from such histograms, two distinct distributions are evident, corresponding to pixels of the brighter sheet surface and the darker regions within the pores. A threshold was selected corresponding to the intensity value between the peaks of these two distributions. Then all pixels having intensity values below this threshold were set to an intensity value of 0, while pixels having higher intensity values were set to 1, resulting in a binary black and white image. The binary image was then analyzed using ImageJ (https: / / imagej.nih.gov, version 1.52a) to examine both the pore area fraction and the pore size distribution. The scale bar of each image was used to provide the pixel / mm scale factor. For the analysis, the auto-thresholding and Analyze Particles functions were used to isolate each pore. The output of the analysis function included the area fraction of the overall image as well as the pore area and pore perimeter of each individual pore detected.

[0236] The average pore size is defined as D A 50: 50% of the total pore area is composed of pores having a hydraulic diameter equal to or smaller than the D A 50 average diameter.

[0237] Hydraulic diameter = "4 * pore area (m 2 ) / pore perimeter (m)".

[0238] It is an equivalent diameter, and not all of the calculated pores are circular.

[0239] Test 2: Microcomputed Tomography (μCT) Method for Determining the Overall or Regional Average Pore Size and Average Pore Wall Thickness of Open-Cell Foam (OCF) Calculation

[0240] Porosity is the ratio between the void space and the total space occupied by the OCF. Porosity can be calculated from μCT scans by segmenting the void space via a threshold and determining the ratio of void voxels to total voxels. Similarly, the solid volume fraction (SVF) is the ratio between the solid space and the total space, and the SVF can be calculated as the ratio of occupied voxels to total voxels. Both porosity and SVF are average scalar values that do not provide structural information such as the pore size distribution in the height direction of the OCF or the average pore wall thickness of the OCF struts.

[0241] To characterize the 3D structure of the OCF, a μCT X-ray scanning instrument capable of acquiring datasets with high isotropic spatial resolution is used to image the samples. An example of a suitable instrument is the SCANCO system model 50 μCT scanner (Scanco Medical AG, Brüttisellen, Switzerland), which operates at the following settings: an energy level of 45 kVp at 133 μA; 3000 projections; a 15 mm field of view; a 750 ms integration time; an average of 5; and a voxel size of 3 μm per pixel. After the scan and subsequent data reconstruction are complete, the scanner system creates a 16-bit dataset, called an ISQ file, where the gray levels reflect the variation in X-ray attenuation, which in turn is related to the material density. The ISQ file is then converted to 8 bits using a scale factor.

[0242] Scanned OCF samples are typically prepared by punching cores with a diameter of approximately 14 mm. The OCF punch is placed flat on a low-attenuation foam and then mounted in a 15 mm diameter plastic cylindrical tube for scanning. A scan of the sample is acquired such that the entire volume of all the mounted cut samples is included in the dataset. From this larger dataset, a smaller sub-volume of the sample dataset is extracted from the total cross-section of the scanned OCF, creating a 3D data slab where the pores can be qualitatively evaluated without edge / boundary effects.

[0243] To characterize the pore size distribution and strut size in the height direction, a local thickness map algorithm or LTM is implemented on the sub-volume dataset. The LTM method begins with an Euclidean distance map (EDM) that assigns a gray level value equal to the distance of each empty voxel from its nearest boundary. Based on the EDM data, the 3D void space representing the pores (or the 3D solid space representing the struts) is tessellated into spheres with sizes matching the EDM values. The voxels enclosed by the spheres are assigned the radius value of the largest sphere. In other words, each empty voxel (or solid voxel of the strut) is assigned the radial value of the largest sphere that both fits within the void space boundary (or the solid space boundary of the strut) and includes the designated voxel.

[0244] The 3D labeled sphere distribution output from the LTM data scan can be considered a stack of two-dimensional images in the height direction (or Z-direction) and is used to estimate the change in sphere diameter from slice to slice as a function of the OCF depth. The strut thickness is considered a 3D dataset, and the average value of all or part of the sub-volume can be evaluated. Calculations and measurements are performed using AVIZO Lite (9.2.0) from Thermo Fisher Scientific and MATLAB (R2017a) from Mathworks.

[0245] Test 3: Percentage of Open Cells in the Sheet Product

[0246] The open-cell percentage is measured via gas pycnometry. Gas pycnometry is a common analytical technique for precisely measuring volume using the gas displacement method. An inert gas such as helium or nitrogen is used as the displacement medium. A sample of the solid sheet product of the present invention is sealed in an instrument compartment of known volume, an appropriate inert gas is introduced, and then expanded to another precise internal volume. The pressures before and after expansion are measured and used to calculate the volume of the sample product.

[0247] ASTM standard test method D2856 provides a procedure for determining the open-cell percentage using an older air pycnometer model. This device is no longer manufactured. However, the open-cell percentage can be conveniently and precisely determined by performing tests using a Micromeritics AccuPyc pycnometer. ASTM procedure D2856 describes five methods (A, B, C, D, and E) for determining the open-cell percentage of foam materials. For these experiments, nitrogen and ASTM foampyc software can be used with an Accupyc 1340 to analyze the samples. Method C in the ASTM procedure is used to calculate the open-cell percentage. This method simply compares the geometric volume determined by measuring the thickness and standard volume with the open-cell volume measured by the Accupyc according to the following equation:

[0248] Open-cell percentage = Open-cell volume of the sample / Geometric volume of the sample * 100

[0249] These measurements are preferably made by Micromeretics Analytical Services, Inc. (One Micromeritics Dr, Suite 200, Norcross, GA 30093). Additional information related to this technology can be found on the Micromeretics Analytical Services website (www.particletesting.com or www.micromeritics.com), or published in “Analytical Methods in Fine particle Technology” by Clyde Orr and Paul Webb.

[0250] Test 4: Final Water Content of the Sheet Product

[0251] The final moisture content of the solid sheet product of the present invention was obtained by using a Mettler Toledo HX204 moisture analyzer (S / N B706673091). At least 1 g of the dried sheet product was placed on the measurement tray. Then a standard procedure was performed, with an additional procedure setting of 10 minutes analysis time and a temperature of 110 °C.

[0252] Test 5: Thickness of the Sheet Product

[0253] The thickness of the flexible, porous, dissolvable solid sheet product of the present invention was obtained by using a micrometer or thickness gauge such as a bench-mounted digital micrometer, Mitutoyo Corporation model IDS-1012E (Mitutoyo Corporation, 965 Corporate Blvd, Aurora, IL, USA 60504). The micrometer has a platen with a diameter of 1 inch and weighs approximately 32 grams, which measures the thickness under a pressure of approximately 0.09 psi (6.32 gm / cm 2 ) pressure.

[0254] The thickness of the flexible, porous, dissolvable solid sheet product was measured by raising the platen, placing a portion of the sheet product on the base under the platen, carefully lowering the platen to contact the sheet product, releasing the platen, and measuring the thickness of the sheet product in millimeters according to the digital readout. The sheet product should extend completely to the entire edge of the platen to ensure measurement of the thickness at the lowest possible surface pressure, unless in the case of a more rigid substrate that is not flat.

[0255] Test 6: Basis Weight of the Sheet Product

[0256] The basis weight of the flexible, porous, dissolvable solid sheet product of the present invention was calculated as the weight per unit area of the sheet product (grams / m2 )。 The area is calculated as the area projected onto a flat surface perpendicular to the outer edge of the sheet product. The solid sheet product of the present invention is cut into 10 cm × 10 cm sample squares, so this area is known. Then each of such sample squares is weighed, and then the resulting weight is divided by the known area of 100 cm 2 to determine the corresponding basis weight.

[0257] For an article of irregular shape, if it is a flat object, the area is calculated based on the area enclosed within the outer perimeter of such an object. Thus, in the case of a spherical object, the area is calculated based on the average diameter as 3.14 × (diameter / 2) 2 . Thus, in the case of a cylindrical object, the area is calculated based on the average diameter and the average length as diameter × length. For an irregularly shaped three-dimensional object, the area is calculated based on the side projected onto a flat surface perpendicularly oriented to the side having the largest external dimension. This can be achieved by carefully tracing the external dimensions of the object with a pencil onto a piece of paper, then by roughly counting the number of squares and multiplying by the known area of the square, or by taking a photograph of the traced area including a scale (shaded for contrast) and using image analysis techniques to calculate the area.

[0258] Test 7: Density of the Sheet Product

[0259] The density of the flexible, porous, soluble solid sheet product of the present invention is determined by the following formula: calculated density = basis weight of the porous solid / (porous solid thickness × 1,000). The basis weight and thickness of the soluble porous solid are determined according to the methods described above.

[0260] Test 8: Specific Surface Area of the Sheet Product

[0261] The specific surface area of a flexible, porous, dissolvable solid sheet product is measured via gas adsorption techniques. Surface area is a measure of the exposed surface of a solid sample at the molecular level. The BET (Brunauer, Emmet, and Teller) theory is the most popular model used to determine surface area and it is based on gas adsorption isotherms. Gas adsorption uses physical adsorption and capillary condensation to measure gas adsorption isotherms. The technique is outlined by the following steps; the sample is placed in a sample tube and heated under vacuum or flowing gas to remove contaminants on the sample surface. The sample weight is obtained by subtracting the weight of the empty sample tube from the total weight of the degassed sample and sample tube. The sample tube is then placed in the analysis port and analysis is started. The first step in the analysis method is to evacuate the sample tube and then measure the free space volume of the sample tube using helium at liquid nitrogen temperature. The sample is then evacuated a second time to remove the helium. The instrument then starts collecting the adsorption isotherm by quantitatively introducing krypton gas at user-specified intervals until the desired pressure measure is achieved. The sample can then be analyzed using an ASAP 2420 and krypton gas adsorption. These measurements are recommended to be performed by Micromeretics Analytical Services, Inc. (One Micromeritics Dr, Suite 200, Norcross, GA 30093). More information related to this technique can be found on the Micromeretics Analytical Services website (www.particletesting.com or www.micromeritics.com), or published in the book “Analytical Methods in Fine Particle Technology” by Clyde Orr and Paul Webb.

[0262] Test 9: Dissolution Rate of the Sheet Product

[0263] The dissolution rate of the dissolvable sheet or solid product of the present invention is measured as follows:

[0264] 1. Add 400 ml of deionized water at room temperature (25 °C) to a 1 L beaker and then place the beaker on a magnetic stirrer plate.

[0265] 2. Place a magnetic stir bar with a length of 23 mm and a thickness of 10 mm in the water and set it to rotate at 300 rpm.

[0266] 3. Calibrate a Mettler Toledo S230 conductivity meter to 1413 μS / cm and place the probe in the water in the beaker.

[0267] 4. For each experiment, select the number of samples such that at least 0.2 g of the sample dissolves in the water.

[0268] 5. Activate the data recording function on the conductivity meter and drop the sample into the beaker. Within 5 seconds, submerge the samples below the water surface using a flat steel plate with a diameter similar to that of the glass beaker and prevent them from floating to the surface.

[0269] 6. Record the conductivity for at least 10 minutes until a steady-state value is reached.

[0270] 7. To calculate the time required to achieve 95% dissolution, first calculate the 10-second moving average based on the conductivity data. Then estimate the time when this moving average exceeds 95% of the final steady-state conductivity value and take it as the time required to achieve 95% dissolution.

[0271] Test 10: Gelation Test of the Sheet Product

[0272] The foam gelling during the dissolution of soluble solid sheets or articles is measured by rheometer oscillation testing as follows:

[0273] Use a Malvern Kinexus Lab+ rheometer with a 40 mm flat stainless steel spindle (PU40 SR4067 SS) and a flat stainless steel substrate (PLS61S2837 SS). Load the standard oscillation test "Measure_0033Single frequency strain controlled" in the Kinexus software with the following parameters: 1 Hz oscillation frequency, 1% strain, and a total measurement time of 10 minutes. Then modify the test program by deleting the temperature setting step from the software and adding a "Set gap" step, where the gap setting value is 1 mm. The data recording frequency is set to 1 data point per second. These modifications are made so that once started, the program immediately goes to set the gap and starts measuring as soon as the set gap is reached, and the foam comes into contact with the water. Before starting the experiment, set the substrate temperature to a constant set value of 20 °C.

[0274] With the spindle inserted into the rheometer and after running the calibration program to zero the spindle for the substrate gap measurement, stack a 40 mm diameter solid sheet disc onto the rheometer spindle by gently flattening the bottom side of the sheet stack against the flat spindle surface. No adhesive is added as the sheets have sufficient adhesion to stay attached to the spindle surface.

[0275] Once most of the sheet discs are attached to the spindle, dispense 0.62 g of deionized water onto the center of the substrate using an adjustable pipette for exhausting air. The same mass of 0.62 g of water is always added for all tests. Then start the modified oscillation test program.

[0276] Perform at least 3 replicate experiments for each sample type. Then export the experimental time and experimental shear modulus (elastic component) data to Microsoft excel and calculate the following parameters: The peak shear modulus is the maximum observed value of the shear modulus measured in the experiment. The final shear modulus is the average of the last 60 data points measured within 10 minutes of the experimental time (for all experiments, the relative standard deviation of this average is less than 1.0%. If this is not the case, the average should not be considered a correct estimate of the final shear modulus). The total area is the area under the shear modulus vs. time curve and is calculated using the well-known trapezoidal rule. A higher value of any of these three parameters indicates a relatively slower dissolution of the sample.

[0277] Test 11: Visual Scoring Test for Leakage of the Coating Composition

[0278] The visual score of the leakage of the coating composition applied to the soluble sheet is measured as follows:

[0279] Once the samples are obtained (i.e., after cutting and sealing), a visual scoring test is performed to evaluate the degree of dye leakage on the top and bottom surfaces of the cut and sealed multi-layer samples. First, store each sample in a separate polyethylene zipper bag for three days. Keep all samples separated to avoid any compressive force on the samples.

[0280] After three days, remove the samples from the polyethylene bags for measurement. Use a hollow circular metal disc with a radius in the range of 0.5 cm to 2.5 cm to quantify the leakage on the bottom and top surfaces of each sample by assigning a score from 0 to 5 as follows:

[0281] Score value = 0 – No obvious signs of leakage

[0282] Score value = 1 – The leakage area can be surrounded by a disc with an inner radius of 0.5 cm

[0283] Score value = 2 – The leakage area can be surrounded by a disc with an inner radius of 1.0 cm

[0284] Score value = 3 – The leakage area can be surrounded by a disc with an inner radius of 1.5 cm

[0285] Score value = 4 – The leakage area can be surrounded by a disc with an inner radius of 2.0 cm

[0286] Score value = 5 – The leakage area can be surrounded by a disc with an inner radius of 2.5 cm

[0287] If staining occurs at multiple separate locations, the above method will be applied to each separate stained location. Sum the scores for each separate location and use as the final overall score.

[0288] Test 12: Viscosity

[0289] The viscosity value of the liquid juice was measured using a Malvern Kinexus Lab+ rheometer with a cone-plate geometry (CP1 / 50SR3468 SS), a gap width of 0.054 mm, a temperature of 20 °C, and a shear rate of 1.0 s-1 for a period of 360 seconds.

[0290] Examples

[0291] Example 1: Different OCF Structures in Solid Sheets Prepared by Different Heating / Drying Devices

[0292] Wet premixes having the following surfactant / polymer compositions as described in Tables 1 and 2 below were prepared for use in laundry care sheets and hair care sheets, respectively.

[0293] Table 1

[0294] (Laundry Detergent Care Preparation)

[0295]

[0296] The viscosity of the wet premix composition as described in Table 1 was approximately 14309.8 cps. After aeration, the average density of such aerated wet premix was approximately 0.25 g / cm 3 .

[0297] Table 2

[0298] (Hair Care Preparation - Shampoo)

[0299]

[0300] The viscosity of the wet premix composition as described in Table 2 was approximately 19254.6 cps. After aeration, the average density of such aerated wet premix was approximately 0.225 g / cm 3 .

[0301] Flexible porous soluble solid sheets A and B were prepared from the above wet premixes as described in Tables 1 and 2 using a continuous aerator (Aeros) and a rotary drum dryer, with the following settings and conditions as described in Table 3 below:

[0302] Table 3

[0303] (Tumble Drying)

[0304]

[0305] Using a continuous aerator (Oakes) and a mold placed on a hot plate (which provides bottom-conduction heating), prepare flexible porous soluble solid sheet C from the above wet premix as described in Table 2, using the following settings and conditions as described in Table 4 below:

[0306] Table 4

[0307] (Hot Plate Drying)

[0308]

[0309] In addition, using a continuous aerator (Oakes) and a mold placed on an impact oven, prepare flexible porous soluble solid sheets I and II from the above wet premix as described in Tables 1 and 2, using the following settings and conditions as described in Table 5 below:

[0310] Table 5

[0311] (Impingement Oven Drying)

[0312]

[0313] Tables 6 - 9 below summarize various physical parameters and pore structures measured for solid sheets A - C and solid sheets I - II prepared from the above wet premix and drying process.

[0314] Table 6

[0315] (Physical Parameters)

[0316]

[0317] Table 7

[0318] (Overall Pore Structure)

[0319]

[0320] Table 8

[0321] (Surface and Regional Pore Structure)

[0322]

[0323] Table 9

[0324] (Variation between Regional Pore Structures)

[0325]

[0326] The above data indicate that the solid sheet of the present invention, which is mainly open-celled, and the solid sheet prepared by the rotary drum drying method have an average pore size on the top surface greater than 100 μm, while this is not the case for the solid sheet prepared by the impact oven method. Specifically, Figure 6A shows a scanning electron microscope (SEM) image of the top surface of Sheet A, while Figure 6B shows an SEM image of the top surface of Solid Sheet I. Figure 7A shows an SEM image of the top surface of Solid Sheet C, while Figure 7B shows an SEM image of the top surface of Solid Sheet II.

[0327] In addition, the above data indicate that the regional variation in the average pore size of the solid sheet prepared by the rotary drum drying method is significantly smaller than that of the solid sheet prepared by the impact oven drying method, especially the ratio of the bottom average pore size to the top average pore size is significantly smaller.

[0328] Example 2: Improved Dissolution Characteristics of a Solid Product Containing Juice Compared to a Solid Product without Juice

[0329] 1) Preparation of a Solid Product Containing Juice and a Solid Product without Juice

[0330] A soluble solid product containing a coating composition (hereinafter referred to as a solid product containing juice) and a soluble solid product without a coating composition (hereinafter referred to as a solid product without juice) are prepared as follows.

[0331] First, a large solid sheet (minimum area of 1.0 × 1.0 m) is prepared according to the method in the method for manufacturing a solid sheet in Part III.

[0332] Specifically, a wet premix containing the components of the solid sheet and additional water is first prepared to obtain a total solid content of about 35% by weight (i.e., the total water content in the slurry is about 65% by weight).

[0333] The slurry preparation method is as follows:

[0334] 1. First, water and glycerol are added to a glass beaker and stirred at 200 rpm using a overhead stirrer.

[0335] 2. Then, while continuing to stir, polyvinyl alcohol is slowly added to the beaker containing water and glycerol, ensuring that there is no foaming of the solution or agglomeration of the polyvinyl alcohol.

[0336] 3. Then the beaker is placed in a water bath and heated to 80 °C while continuing to stir. The beaker is covered with a sticky film or a metal sheet to reduce water evaporation, and mixing is continued for at least 1.0 hour.

[0337] 4. Weigh the remaining components and add them together to a separate glass beaker. Also add the remaining water required to achieve a total water content of 65% in the slurry to this beaker.

[0338] 5. Place the beaker in a water bath at 80 °C and stir its contents at 500 rpm using a overhead stirrer for at least 30 minutes.

[0339] 6. Once the predetermined mixing time has been reached in both beakers, add the contents of both together to a single glass beaker, then continue stirring at 500 rpm and maintain the temperature at 80 °C for at least another 30 minutes.

[0340] The viscosity of the wet premix thus formed is approximately 19254.6 cps. Then inflate as follows:

[0341] 1. Use a water bath and a pump to preheat an Aeros A20 continuous inflator consisting of a jacketed hopper (model JCABT10) and an A20 mixing head to 80 °C.

[0342] 2. Then add the previously prepared slurry to the hopper. Then turn on the inflation device and set the mixing head speed, feed pump speed, and air flow rate to 600, 500, and 100 respectively.

[0343] 3. Collect the inflated slurry from the inflator outlet and measure its density by filling a density cup of known volume and weighing the mass of the inflated slurry. At the above inflator settings, an inflated slurry density of approximately 0.225 g / cm 3 was achieved.

[0344] Prepare a flexible porous solid sheet with a thickness of approximately 0.8 mm - 1.5 mm using a rotary drum dryer method as follows:

[0345] 1. Preheat a rotary drum dryer (drum diameter is approximately 1.5 m) to approximately 130 °C.

[0346] 2. Add the inflated slurry collected from the Aeros A20 outlet to the feed trough of the drum dryer.

[0347] 3. Once added, the rotation of the drum dryer starts and is set at a rotational speed such that the residence time of the slurry on the heated drum is approximately 15 minutes.

[0348] 4. Once dried, peel the flexible porous sheet thus formed from the drum surface and place it in a plastic bag.

[0349] Then, the solid sheets were stored at an ambient relative humidity of 50 ± 2% and a temperature of 23 ± 1 °C for 24 hours (i.e., the conditioning step). The average thickness of all sheets 1 was 1.2107 mm, with a standard deviation of 0.0464. After the above initial conditioning step, first, discs with a diameter of 4 cm were cut from the large solid sheet using a 4 cm hollow punch. Then, if a coating composition was required, the coating composition was added according to Coating Method A described below.

[0350] In Coating Method A, droplets of the coating composition were dispensed onto a single location on the surface of the solid sheet using a pipette. This location was always the very center point of the total foam mass. Figure 8A An exemplary solid article obtained by using Coating Method A is shown. For example, if a single solid sheet was required in the experiment, the droplet was dispensed onto the very center point on the bottom surface of the solid sheet. If multiple solid sheets were required in the experiment, half of the sheets were first stacked in a head-to-foot configuration, then the coating composition was dispensed onto the very center point of the top sheet, and then the remaining sheets were stacked on top. For a single sheet or multiple stacked sheets, the sheets were always oriented such that the coating composition was dispensed onto the bottom side of the sheet. The solid sheet was placed on a mass balance and the mass was balanced to zero, and droplets were continuously added until the desired mass of the coating composition was obtained.

[0351] Then, after adding the coating composition, the samples were stored for another 24 hours under the same humidity and temperature conditions (50 ± 2% and 23 ± 1 °C).

[0352] The sheets and the coating composition had the formulations shown in the following table:

[0353] Table 10 (Sheet Formulation)

[0354]

[0355] Table 11

[0356] (Juice Formulation)

[0357]

[0358] Three types of samples: Articles 1 to 3 were prepared as shown in the following table (three parallel samples of each type).

[0359] Table 12

[0360]

[0361] Specifically, article 1 is formed by stacking three layers of sheet 1 without applying any coating composition; article 2 is formed by adding juice 1 to one layer of sheet 1 using coating method A mentioned above and then adding another layer of sheet 1 on top to form a 2-layer stack; and article 3 is formed by adding juice 2 to one layer of sheet 1 using coating method A and then adding another layer of sheet 1 on top to form a 2-layer stack. Finally, for all samples, the amount of coating composition added is calculated such that the total mass of surfactant (from the sheet and the juice) in the sample is equal to approximately 0.42 grams.

[0362] 2) Measurement of Foam Gelation

[0363] Due to the dissolution of water-soluble polymers (e.g., PVA) and surfactants in the solid article, when the solid article according to the present disclosure comes into contact with water, gelation occurs. The presence of gelation may prevent water from penetrating into the solid article through the OCF structure, resulting in a reduced dissolution rate. In addition, once a hard gel is formed, further dissolution of the solid article will be very slow, which may lead to residues on the clothes if the solid article is used for laundry. Therefore, if the degree of gelation is reduced, the dissolution characteristics are improved.

[0364] The gelation of the solid article without juice (article 1) and the solid articles with juice (articles 2 and 3) were determined according to Test 10. The results are shown below.

[0365] Table 13

[0366]

[0367] The above data show that significantly higher values of the three measured parameters (peak shear modulus G', final value of G', and total area) were observed for the sample of only solid sheets, indicating poor dissolution. The results of the gelation test are also shown in Table 9. Completely surprisingly, the solid articles with juice (e.g., articles 2 and 3) showed improved dissolution characteristics compared to the solid articles without juice (e.g., article 1), because it was believed that before the filing of the present disclosure, the loading of the coating composition on the solid article according to the present disclosure might affect dissolution by clogging the OCF structure.

[0368] In addition, a significant reduction in the peak shear modulus was also observed for the sample containing the coating composition with added solvent (article 3) compared to the sample without solvent in the juice (article 2), indicating that including a solvent in the coating composition can result in even more improved dissolution characteristics (e.g., even less gelation).

[0369] Example 3: Juice Loading Capacity of a Leak-Free Solid Product

[0370] 1) Preparation of Two Series of Multilayer Sheets Containing Different Amounts of the Coating Composition

[0371] Two series of multilayer sheets containing different amounts of coating compositions applied by different coating methods were prepared, where Series 1 was prepared from Sheet 1 and Juice 1 as mentioned in Example 2, and Series 2 was prepared from Sheet 1 and Juice 3 (containing silica as a rheology modifier) as shown in the table below. The mass of the juice added in these samples was in the range of about 2 g to 12 g. The average estimated sheet density of these multilayer samples was 0.169 g / cm 3 .

[0372] Table 14

[0373] (Juice Formulation)

[0374]

[0375]

[0376] The preparation of these two series of multilayer sheets was the same as in Example 2, except that after the initial conditioning step, the large solid sheet was first cut into 10 x 10 cm sheets using a paper cutter, and then the coating composition was added according to Coating Method A as mentioned in Example 2 or Coating Method B as follows.

[0377] In Coating Method B, a plastic roller (roller width 10 cm and diameter 2 cm) was used to spread the coating composition onto the 10 x 10 cm solid sheet. First, the roller was rolled on a flat surface larger than 10 x 10 cm and containing a liquid pool in a walled container. Then, by gently shaking the roller, the excess liquid was removed. Then the roller was rolled over the entire 10 x 10 cm sheet at least 10 times, where the initial contact point between the roller and the sheet and the rolling direction were randomly assigned to help prevent uneven coating. The coating composition was always rolled on the bottom side of the sheet. The 10 x 10 cm solid sheet was placed on a mass balance and the mass was balanced to zero, and this step was repeated on the bottom side of the sheet until the desired mass of the coating composition was spread on the sheet surface. However, no juice was applied to the top and bottom sheets of the stack to act as a buffer against leakage, as Figure 8B shown.

[0378] All of the multilayer samples prepared by Coating Method A in this example consisted of eighteen stacked layers of 10×10 cm solid sheets, and all of the multilayer samples prepared by Coating Method B in this example consisted of thirteen stacked layers. For this example, the coating composition contained 0.1 wt% dye (Liquitint Violet 129), and the content of the fragrance was correspondingly reduced by 0.1 wt%. In addition, once the coating composition was added, a Chhong 1 metric ton CH217 hydraulic press (S / N HP170726TJ01) was used to cut the multilayer stack, and the cutting angle was in the range of about 20° to about 50°. The cutting blade for cutting the seal was an irregular closed shape with an internal area of 3182 mm2. The mass of each sheet after cutting was weighed as 0.57 g, and the standard deviation was 0.019 g. For the cut-sealed samples, the final mass of the added coating composition was estimated by the following formula: Coating composition mass = Total mass of the cut-sealed samples - 18 * 0.57. This formula was used to account for some samples with a high coating composition load where excessive leakage occurred and some of the added coating composition mass leaked onto the cut-sealing equipment.

[0379] 2) Measurement of Leakage Score

[0380] Then, the leakage score was determined according to Test 11. The results are shown in the following table.

[0381] Table 15a

[0382]

[0383] Table 15b

[0384]

[0385] This indicates that a significant mass of the coating composition can be applied without significant leakage. Specifically, regarding Series 1, the results show that when the added juice was less than 4.0 g, there was no significant leakage (i.e., the score was less than 1). And, regarding Series 2, the results clearly show that for Coating Method A, no leakage was observed when the added liquid juice was below 4.0 g (i.e., the score was 0), and for Coating Method B, no leakage was observed when the added liquid juice was below 6.0 g. Additionally, the results show that the leakage score of Coating Method B was consistently lower throughout the range of the added juice mass.

[0386] Furthermore, the results show that the preferred coating composition (e.g., Juice 3) brings even more improved anti-leakage performance.

[0387] Example 4: Effect of Foam Structure on Juice Leakage

[0388] 1) Preparation of High-Density and Low-Density Multilayer Sheets Containing the Coating Composition

[0389] By changing the target density of the aerated wet premix on the continuous aerator to 0.3 g / cm 3 and 0.4 g / cm 3 for lower and higher density sheets, respectively, sheets with the same composition (as shown in Table 16 below) and different densities were prepared from the same wet premix. The average estimated foam density of the higher density sheets was 0.177 g / cm 3 and the average density of the lower density sheets was 0.135 g / cm 3 .

[0390] Table 16

[0391] (Sheet Formulation)

[0392]

[0393] Multilayer sheets containing the coating composition were prepared from the higher density or lower density sheets as mentioned above, with added juice 3 as mentioned in Example 3. Specifically, 3 samples of multilayer sheets were prepared, each sample containing thirteen layers of higher density sheets and with juice 3 added according to coating method B as mentioned in Example 3, which is referred to herein as article 4. Similarly, 3 samples of multilayer sheets were prepared, each sample containing eighteen layers of higher density sheets and with juice 3 added according to coating method B as mentioned in Example 3, which is referred to herein as article 5. By modifying the average thickness of each sheet, the total thickness of articles 4 and 5 was maintained at 20 mm.

[0394] 2) Measurement of Leakage Score

[0395] Then, the average leakage score of articles 4 and 5 was determined according to Test 11. The results are shown in the table below.

[0396] Table 17

[0397]

[0398]

[0399] The results showed that article 5 prepared from the lower density sheets did not show significant leakage (score = 0.67), while article 4 prepared from the higher density sheets experienced leakage of the juice (score = 4.67), indicating that the density of the sheets is important for preventing leakage. Specifically, the lower density sheets can hold more juice before leakage occurs.

[0400] Example 5: Juice Does Not Significantly Block the OCF Structure

[0401] 1) Preparation of a Single-Layer Sheet Containing the Coating Composition

[0402] The single-layer product 6, as mentioned in Example 2, is prepared solely from the sheet 1 and does not contain any added juice. Another single-layer product 7, as mentioned in Examples 2 and 3, is prepared from the sheet 1 and the juice 3. Specifically, according to Coating Method B, the juice 3 is added to the sheet 1, except that the liquid juice is rolled onto the top side of the sheet 1 instead of the bottom side. Since the top side is even more porous than the bottom side, the top side will be more suitable for showing whether the juice causes significant pore blockage. An average of 2.8 grams of liquid juice is added, with a standard deviation of 0.3 grams.

[0403] 2) SEM Test

[0404] SEM tests were conducted according to Test 1 to visualize the top surfaces of products 6 and 7. Figure 10A The top surface of product 6 is shown. Figure 10B The top surface of product 7 is shown. It is evident that even after applying a high juice load (about 2.8 g), the OCF structure of product 7 is not significantly damaged (i.e., not blocked by the juice).

[0405] Example 6: Exemplary Solid Product Containing Juice

[0406] The following are examples of solid products containing juice. Sheets a to e were prepared similarly to sheet 1 in Example 2 (see Table 18). Then, by applying juices a to e (see Table 19) to sheets a to e according to Coating Method A or B, and then stacking the corresponding sheets to form multilayer structures each having 10 - 20 layers, solid products containing juice were formed. Such products can be used for laundry and personal cleansing care or hair care (PCC / hair), respectively.

[0407] Table 18

[0408] (Sheet Formulation)

[0409]

[0410]

[0411] Table 19

[0412] (Juice Formulation)

[0413]

[0414] The dimensions and values disclosed herein should not be construed as being strictly limited to the exact numerical values recited. On the contrary, each such dimension is intended to represent that value and the range that is functionally equivalent around that value, unless otherwise indicated. For example, a dimension disclosed as "40 mm" is intended to represent "about 40 mm".

[0415] Unless expressly excluded or otherwise limited, each document cited herein, including any cross-referenced or related patent or patent application and any patent application or patent to which this application claims priority or benefits therefrom, is hereby incorporated by reference in its entirety. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein, or that it alone or in any combination with any one or more other references teaches, suggests, or discloses any such invention. Further, when any meaning or definition of a term in this invention conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to the term in this invention shall govern.

[0416] Although specific embodiments of the invention have been illustrated and described, it will be apparent to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, it is intended that all such changes and modifications that fall within the scope of the invention be covered by the appended claims.

Claims

1. A method for preparing a soluble solid article for laundry care or hair care, the method comprising the steps of: 1) Provide two or more flexible porous soluble sheets and a coating composition, wherein each of the two or more sheets comprises a water-soluble polymer and a first surfactant, and is characterized by a percentage of open pores of 80% to 100% and an overall average pore size of 100 µm to 2000 µm, wherein the coating composition is a liquid having a viscosity of 3 cps to 5,000 cps measured at 20 °C and 1 s -1 and wherein the coating composition comprises a second surfactant; 2) applying the coating composition onto at least one surface of at least one of the two or more sheets; and 3) arranging the two or more sheets in a stack to form the soluble solid article such that the coating composition is not on any outer surface of the stack.

2. The method according to claim 1, wherein at least one of the two or more sheets comprises 5% to 50% by total weight of the sheet of the water-soluble polymer.

3. The method according to claim 2, wherein the water-soluble polymer has a weight average molecular weight of 50,000 to 400,000 daltons.

4. The method according to claim 2, wherein the water-soluble polymer is polyvinyl alcohol characterized by a degree of hydrolysis in the range of 40% to 100%.

5. The method according to claim 1, wherein at least one of the two or more sheets comprises 30% to 90% by total weight of the sheet of the first surfactant.

6. The method according to claim 1, wherein the first surfactant is selected from: anionic surfactants, nonionic surfactants, cationic surfactants, zwitterionic surfactants, and any combination thereof.

7. The method according to claim 1, wherein the first surfactant is selected from C6-C 20 linear alkylbenzene sulfonates (LAS), C6-C with a weight-average degree of alkoxylation in the range of 0.5 to 10 20 linear or branched alkyl alkoxysulfates (AAS), C6-C 20 linear or branched alkyl sulfates (AS), C6-C with a weight-average degree of alkoxylation in the range of 5 to 15 20 linear or branched alkyl alkoxylated alcohols (AA), and any combination thereof.

8. The method according to claim 1, wherein the second surfactant is selected from: anionic surfactants, nonionic surfactants, cationic surfactants, zwitterionic surfactants, and any combination thereof.

9. The method according to claim 1, wherein the second surfactant comprises a nonionic surfactant.

10. The method according to claim 1, wherein the second surfactant comprises a C6-C linear or branched alkyl alkoxylated alcohol (AA) having a weight-average degree of alkoxylation in the range of 5 to 15. 20 ​ 11. The method according to claim 1, wherein the coating composition further comprises a solvent, wherein the solvent is selected from glycerol, propylene glycol, diethylene glycol, dipropylene glycol, ethanolamine, ethanol, water, and any combination thereof.

12. The method according to claim 1, wherein the coating composition further comprises a rheology modifier, the rheology modifier being selected from: cellulose and derivatives; guar gum and guar gum derivatives; polyethylene oxide, polypropylene oxide, and POE-PPO copolymers; polyvinylpyrrolidone, crosslinked polyvinylpyrrolidone, and derivatives; polyvinyl alcohol and derivatives; polyethyleneimine and derivatives; finely divided inorganic particles; silica; water-swellable clays; gums; and any combination thereof.

13. The method according to claim 12, wherein the rheology modifier is selected from sodium carbonate, sodium sulfate, silica, water-swellable clays, and any combination thereof.

14. The method according to claim 1, wherein the coating composition further comprises a fragrance, the fragrance being selected from: free fragrances, fragrance microcapsules, and any combination thereof.

15. The method according to claim 14, wherein the weight ratio of the second surfactant to the fragrance in the coating composition is from 1:50 to 50:

1.

16. The method according to claim 1, wherein the coating composition comprises: 1) from 1% to 95% of said second surfactant, based on the total weight of the coating composition; and / or 2) from 0.1% to 99% of a solvent, based on the total weight of the coating composition; and / or 3) from 0.1% to 99% of a rheology modifier, based on the total weight of the coating composition; and / or 4) from 1% to 99% of a fragrance, based on the total weight of the coating composition.

17. The method according to claim 1, wherein the coating composition further comprises additional components selected from softeners, bleaches, enzymes, antibacterial agents, antioxidants, optical brighteners, and any combination thereof.

18. The method according to claim 1, wherein the coating composition further comprises additional components selected from siloxanes, colorant dyes, and any combination thereof.

19. The method according to claim 1, wherein the coating composition further comprises additional components selected from personal care actives.

20. The method according to claim 1, wherein the coating composition comprises less than 30% water, based on the total weight of the coating composition.

21. The method according to claim 1, wherein the coating composition is applied in an amount from 0.1% to 90%, based on the total weight of the soluble solid article.

22. The method according to claim 1, wherein the coating composition is applied on one or both of the contact surfaces of the middle two sheets in the stack.

23. The method according to claim 1, wherein the coating composition is applied on one or both of the contact surfaces of any two adjacent sheets in the stack, excluding the two outermost sheets.

24. The method according to claim 1, wherein the coating composition is applied in the central region of each coated surface of the respective sheet, the central region being defined as a region spaced apart from the outer periphery of the respective sheet by a distance of at least 5% of the maximum dimension D.

25. The method according to claim 1, wherein the coating composition is applied on the entire coated surface of the respective sheet.

26. The method according to claim 1, wherein the ratio of the average pore size of the bottom region to the average pore size of the top region of each sheet of the two or more sheets is from 0.6 to 1.

5.

27. A soluble solid article for laundry care or hair care, the soluble solid article for laundry care or hair care comprising two or more flexible porous soluble sheets, wherein each of the two or more sheets comprises a water-soluble polymer and a first surfactant, and characterized in that the percentage of open pores is 80% to 100%, the overall average pore size is 100 µm to 2000 µm, and the density is 0.05 g / cm 3 to 0.17 g / cm 3 ; wherein the coating composition comprising the second surfactant is present on at least one surface of at least one of the two or more sheets, provided that the coating composition is not on any outer surface of the soluble solid article, and wherein the coating composition is a liquid having a viscosity of from 3 cps to 5,000 cps measured at 20 °C and 1 s -1 under.

28. The soluble laundry or hair care solid article according to claim 27, wherein each of the two or more sheets is characterized by a density of 0.06 g / cm 3 to 0.16 g / cm 3 .

29. The soluble laundry care or hair care solid article according to claim 27, wherein at least one of the two or more sheets comprises from 5% to 50% of the water-soluble polymer, based on the total weight of the sheet.

30. The soluble laundry care or hair care solid article according to claim 27, wherein the water-soluble polymer has a weight average molecular weight of from 50,000 to 400,000 daltons.

31. The soluble solid article for laundry care or hair care according to claim 27, wherein the water-soluble polymer is polyvinyl alcohol characterized by a degree of hydrolysis in the range of 40% to 100%.

32. The soluble solid article for laundry care or hair care according to claim 27, wherein at least one of the two or more sheets contains 30% to 90% of the first surfactant based on the total weight of the sheet.

33. The soluble solid article for laundry care or hair care according to claim 27, wherein the first surfactant is selected from: anionic surfactants, nonionic surfactants, cationic surfactants, and any combination thereof.

34. The soluble laundry or hair care solid article according to claim 27, wherein the first surfactant is selected from C6-C 20 linear alkylbenzene sulfonates (LAS), C6-C with a weight-average alkoxylation degree in the range of 0.5 to 10 20 linear or branched alkyl alkoxysulfates (AAS), C6-C with a weight-average alkoxylation degree in the range of 5 to 15 20 linear or branched alkyl alkoxylated alcohols (AA), C6-C 20 linear or branched alkyl sulfates (AS) and any combination thereof.

35. The soluble solid article for laundry care or hair care according to claim 27, wherein at least one of the two or more sheets further contains 0.00001% to 1% of a bittering agent based on the total weight of the sheet; wherein the bittering agent is selected from: denatonium salts or derivatives thereof; quercetin (3,3',4',5,7-pentahydroxyflavone); naringin (4',5,7-trihydroxyflavanone-7-rhamnoglucoside); aucubin; amygdalin; sweroside; gentiopicroside; swertiamarin; sweroside; gentioflavosid; centaurosid; methiafolin; picroside; centapikrin; salicin; conduritol; absinthin; artabsin; lactucin; lactucopicrin; sonchusin; salonitenolid; α-thujone; β-thujone; deoxylimonene; limonin; citronin; isobaculinic acid; obacunone; obacunonic acid; nomilin; citronin; nomilinic acid; lagopicrin; pramarrubin; carnosol; carnosic acid; quassin; quinine hydrochloride; quinine sulfate; quinine dihydrochloride; columbine; caffeine; threonine; methionine; phenylalanine; tryptophan; arginine; histidine; valine; aspartic acid; sucrose octaacetate; quinine bisulfate; hop extract; and mixtures thereof.

36. The soluble solid article for laundry care or hair care according to claim 27, wherein the second surfactant is selected from: anionic surfactants, nonionic surfactants, cationic surfactants, and any combination thereof.

37. The soluble solid article for laundry care or hair care according to claim 27, wherein the second surfactant comprises a nonionic surfactant.

38. The soluble laundry or hair care solid article according to claim 27, wherein the second surfactant comprises a C6-C 20 linear or branched alkyl alkoxylated alcohol (AA).

39. The soluble solid article for laundry care or hair care according to claim 27, wherein the coating composition further contains a solvent, wherein the solvent is selected from glycerol, propylene glycol, diethylene glycol, dipropylene glycol, ethanolamine, ethanol, water, and any combination thereof.

40. The soluble laundry or hair care solid article according to claim 27, wherein the coating composition further comprises a rheology modifier selected from: cellulose and derivatives; guar gum and guar gum derivatives; polyethylene oxide, polypropylene oxide and POE-PPO copolymers; polyvinylpyrrolidone, crosslinked polyvinylpyrrolidone and derivatives; polyvinyl alcohol and derivatives; polyethyleneimine and derivatives; finely divided inorganic particles; silica; water-swellable clays; gums; and any combination thereof.

41. The soluble laundry or hair care solid article according to claim 40, wherein the rheology modifier is selected from sodium carbonate, sodium sulfate, silica, water-swellable clays and any combination thereof.

42. The soluble laundry or hair care solid article according to claim 27, wherein the coating composition further comprises a fragrance selected from: free fragrances, fragrance microcapsules or any combination thereof.

43. The soluble laundry or hair care solid article according to claim 42, wherein the weight ratio of the second surfactant to the fragrance in the coating composition is from 1:50 to 50:

1.

44. The soluble laundry or hair care solid article according to claim 27, wherein the coating composition comprises: 1) from 1% to 95% of the second surfactant, based on the total weight of the coating composition; and / or 2) from 0.1% to 99% of a solvent, based on the total weight of the coating composition; and / or 3) from 0.1% to 99% of a rheology modifier, based on the total weight of the coating composition; and / or 4) from 1% to 99% of a fragrance, based on the total weight of the coating composition.

45. The soluble laundry or hair care solid article according to claim 27, wherein the coating composition further comprises additional components selected from softeners, bleaches, enzymes, antibacterial agents, antioxidants, optical brighteners and any combination thereof.

46. The soluble laundry or hair care solid article according to claim 27, wherein the coating composition further comprises additional components selected from silicones, color dyes and any combination thereof.

47. The soluble laundry or hair care solid article according to claim 27, wherein the coating composition further comprises additional components selected from personal care actives.

48. The soluble laundry or hair care solid article according to claim 27, wherein the coating composition further comprises less than 30% water, based on the total weight of the coating composition.

49. The soluble laundry or hair care solid article according to claim 27, wherein the article comprises from 0.1% to 90% of the coating composition, based on the total weight of the article.

50. The soluble laundry or hair care solid article according to claim 27, wherein each of the two or more sheets is characterized in that: • The percentage of open pores is from 85% to 100%; and / or • The overall average pore size is from 150 µm to 1000 µm; and / or • The average pore wall thickness is from 5 µm to 200 µm; and / or • The final water content is from 0.5% to 25% by weight of the sheet; and / or • The thickness is from 0.6 mm to 3.5 mm; and / or • Basis weight is 50 g / m 2 to 500 g / m 2 ; and / or • The specific surface area is from 0.03 m 2 / g to 0.25 m 2 / g.

51. The soluble laundry care or hair care solid article according to claim 27, wherein the ratio of the average pore size in the bottom region to the average pore size in the top region of each of the two or more sheets is from 0.6 to 1.

5.

52. A soluble solid article comprising two or more flexible porous soluble sheets, wherein each of the two or more sheets comprises a water-soluble polymer and a first surfactant, and characterized in that the percentage of open pores is from 80% to 100% and the overall average pore size is from 100 µm to 2000 µm; wherein a coating composition comprising a second surfactant and a solvent is present on at least one surface of at least one of the two or more sheets, provided that the coating composition is not on any outer surface of the soluble solid article; and wherein the solvent is an organic solvent, and wherein the coating composition is a liquid having a viscosity of 3 cps to 5,000 cps measured at 20 °C and 1 s -1 under.

53. The soluble solid article according to claim 52, wherein the solvent is selected from glycerol, propylene glycol, diethylene glycol, dipropylene glycol, ethanolamine, ethanol, and any combination thereof.

54. The soluble solid article according to claim 52, wherein the solvent is selected from glycerol, diethylene glycol, dipropylene glycol, and any combination thereof.

55. The soluble solid article according to claim 52, wherein the solvent is dipropylene glycol.

56. The soluble solid article according to claim 52, wherein at least one of the two or more sheets comprises from 5% to 50% of the water-soluble polymer by total weight of the sheet.

57. The soluble solid article according to claim 52, wherein the water-soluble polymer has a weight-average molecular weight of from 50,000 to 400,000 daltons.

58. The soluble solid article according to claim 52, wherein the water-soluble polymer is polyvinyl alcohol characterized by a degree of hydrolysis in the range of 40% to 100%.

59. The soluble solid article according to claim 52, wherein at least one of the two or more sheets comprises from 30% to 90% of the first surfactant by total weight of the sheet.

60. The soluble solid article according to claim 52, wherein the first surfactant is selected from: anionic surfactants, nonionic surfactants, cationic surfactants, and any combination thereof.

61. The soluble solid article according to claim 52, wherein the first surfactant is selected from C6-C 20 linear alkylbenzene sulfonates (LAS), C6-C with a weight-average alkoxylation degree in the range of 0.5 to 10 20 linear or branched alkyl alkoxysulfates (AAS), C6-C with a weight-average alkoxylation degree in the range of 5 to 15 20 linear or branched alkyl alkoxylated alcohols (AA), C6-C 20 linear or branched alkyl sulfates (AS), and any combination thereof.

62. The soluble solid article according to claim 52, wherein at least one of the two or more sheets further comprises from 0.00001% to 1% of a bittering agent by total weight of the sheet; Wherein the bittering agent is selected from: denatonium salts or derivatives thereof; quercetin (3,3',4',5,7-pentahydroxyflavone); naringin (4',5,7-trihydroxyflavanone-7-rhamnoglucoside); aucubin; amygdalin; swertiamarin; gentiopicroside; amarogentin; sweroside; Gentioflavosid; Centaurosid; Methiafolin; picroside; Centapikrin; salicin; conduritol; absinthin; artemisin; artemisin lactone; cirsimarin; lactucin; lactucopicrin; Salonitenolid; α-thujone; β-thujone; deoxylimonene; limonin; citrusin; isobacchalcone acid; obacunone; obacunone acid; nomilin; citrusin; nomilinic acid; marrubiin; Pramarrubin; salvigenin; rosmarinic acid; quassin; quinine hydrochloride; quinine sulfate; quinine dihydrochloride; columbine; caffeine; threonine; methionine; phenylalanine; tryptophan; arginine; histidine; valine; aspartic acid; sucrose octaacetate; quinine bisulfate; hop extract; and mixtures thereof.

63. The soluble solid article according to claim 52, wherein the second surfactant is selected from: anionic surfactants, nonionic surfactants, cationic surfactants, and any combination thereof.

64. The soluble solid article according to claim 52, wherein the second surfactant comprises a nonionic surfactant.

65. The soluble solid article according to claim 52, wherein the second surfactant comprises a C6-C straight-chain or branched-chain alkyl alkoxylated alcohol (AA) having a weight-average degree of alkoxylation in the range of 5 to 15. 20 ​ 66. The soluble solid article according to claim 52, wherein the coating composition further comprises a rheology modifier selected from: cellulose and derivatives; guar gum and guar gum derivatives; polyethylene oxide, polypropylene oxide, and POE-PPO copolymers; polyvinylpyrrolidone, crosslinked polyvinylpyrrolidone, and derivatives; polyvinyl alcohol and derivatives; polyethyleneimine and derivatives; finely divided inorganic particles; silica; water-swellable clays; gums; and any combination thereof.

67. The soluble solid article according to claim 66, wherein the rheology modifier is selected from sodium carbonate, sodium sulfate, silica, water-swellable clays, and any combination thereof.

68. The soluble solid article according to claim 52, wherein the coating composition further comprises a fragrance selected from: free fragrances, fragrance microcapsules, or any combination thereof.

69. The soluble solid article according to claim 68, wherein the weight ratio of the second surfactant to the fragrance is from 1:50 to 50:

1.

70. The soluble solid article according to claim 52, wherein the coating composition comprises: 1) 1% to 95% of the second surfactant based on the total weight of the coating composition; and / or 2) 0.1% to 99% of a solvent based on the total weight of the coating composition; and / or 3) 0.1% to 99% of a rheology modifier based on the total weight of the coating composition; and / or 4) From 1% to 99% of a perfume, based on the total weight of the coating composition.

71. The soluble solid article according to claim 52, wherein the coating composition further comprises additional components selected from plasticizers, bleaching agents, enzymes, antibacterial agents, antioxidants, brightening agents, and any combination thereof.

72. The soluble solid article according to claim 52, wherein the coating composition further comprises additional components selected from siloxanes, colorant dyes, and any combination thereof.

73. The soluble solid article according to claim 52, wherein the coating composition further comprises additional components selected from personal care actives.

74. The soluble solid article according to claim 52, wherein the coating composition further comprises less than 30% water, based on the total weight of the coating composition.

75. The soluble solid article according to claim 52, wherein the article comprises from 0.1% to 90% of the coating composition, based on the total weight of the article.

76. The soluble solid article according to claim 52, wherein each of the two or more sheets is characterized by: • a percentage open area of from 85% to 100%; and / or • an overall average pore size of from 150 µm to 1000 µm; and / or • an average pore wall thickness of from 5 µm to 200 µm; and / or • a final water content of from 0.5% to 25% by weight of the sheet; and / or • a thickness of from 0.6 mm to 3.5 mm; and / or • Basis weight is 50 g / m 2 to 500 g / m 2 ; and / or • Density is 0.05 g / cm 3 to 0.5 g / cm 3 ; and / or • The specific surface area is from 0.03 m 2 / g to 0.25 m 2 / g.

77. The soluble solid article according to claim 52, wherein the ratio of the average pore size in the bottom region to the average pore size in the top region of each of the two or more sheets is from 0.6 to 1.5.

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