RU2779441C1 - Multilayer dissolvable solid arcticle for laundry care and for hair care with specific aspect ratio - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to improved dissolvable solid product for laundry care and for hair care with a set aspect ratio. Described is dissolvable solid product for laundry care and for hair care, containing 6 to 50 flexible dissolvable porous sheets, wherein each of the sheets comprises a water-dissolvable polymer constituting polyvinyl alcohol and a surface-active agent constituting a linear alkyl benzosulphonate, characterised by a 80% to 100% percentage of open cells and a total average pore size from 100 to 2,000 mcm, wherein said dissolvable solid product is characterised by a maximum size D and a minimum size z; wherein the D:z ratio is in the range from 1 to 10 and each of said sheets constitutes a solid sheet containing a top section adjacent to the top surface, a bottom section adjacent to the bottom surface, and a middle section located between said sections, and the relative standard deviation between the average pore size in the top, middle and bottom sections is 20% or less.

EFFECT: creation of a multilayer dissolvable solid product with an improved aspect ratio and/or shape, which is easier to manage and more aesthetically attractive to consumers, while being easily dissolvable in water.

12 cl, 8 dwg, 11 tbl, 2 ex

Description

FIELD OF THE INVENTION

The present invention relates to an improved soluble solid laundry and hair care product with a given aspect ratio.

BACKGROUND OF THE INVENTION

Flexible dissolvable sheets containing surfactant(s) and/or other active ingredients in a water-soluble polymeric carrier or matrix are well known. Such sheets are particularly suitable for delivering surfactants and/or other active ingredients when dissolved in water. Compared to traditional granular or liquid forms in the same product category, these sheets have better structural integrity, are more concentrated, and are easier to store, ship/transport, carry, and handle. Compared to the hard tablet form in the same product category, such sheets are more flexible and less brittle, while providing greater sensory appeal to consumers. However, a disadvantage of such flexible dissolvable sheets may be the significantly slower dissolution in water, especially when compared to the traditional granular or liquid form of the product.

To avoid further exacerbating the dissolution problem, such flexible dissolvable sheets have been made relatively thin (ie high aspect ratios of length/width to thickness) and are typically used as single/single layers. Even when multilayer structures are used, the overall thickness of such multilayer structures remains relatively small. The resulting multilayer structures retain a sheet-like shape with a high length/width to thickness ratio, which can be too soft and flexible to handle, such structures are difficult to separate from each other during use, and are not aesthetically pleasing to consumers.

Therefore, there remains a need for a multilayer soluble solid product with improved aspect ratio and/or shape that is easier to handle and more aesthetically pleasing to consumers, while still being readily soluble in water.

It would also be beneficial to provide a more cost-effective and easily scalable process for making the above improved multilayer soluble solid product.

SUMMARY OF THE INVENTION

In one aspect, the present invention provides a soluble solid article comprising two or more flexible soluble porous sheets, wherein said two or more sheets each comprise a water soluble polymer and a surfactant and have an open cell percentage of from about 80% to 100%, preferably from about 85% to 100%, more preferably from about 90% to 100%, and an overall average pore size from about 100 µm to about 2000 µm, preferably from about 150 µm to about 1000 µm, more preferably from about 200 µm to about 600 microns; while the specified soluble solid product is characterized by a maximum dimension D and a minimum dimension z; and wherein the D/z ratio is in the range of about 1 to about 10, preferably about 1.4 to about 9, more preferably about 1.5 to about 8, most preferably about 2 to about 7.

Preferably, the minimum dimension z of such a soluble solid product is in the range of about 3 mm to about 20 cm, preferably about 4 mm to about 10 mm, more preferably about 5 mm to about 30 mm.

More preferably, each of the above two or more flexible soluble porous sheets has a thickness ranging from about 0.5 mm to about 4 mm, preferably from about 0.6 mm to about 3.5 mm, more preferably from about 0.7 mm to about 3 mm, even more preferably from about 0.8 mm to about 2 mm, most preferably from about 1 mm to about 1.5 mm. The soluble solid product of the present invention may include from about 4 to about 50, preferably from about 5 to about 40, more preferably from about 6 to about 30 such flexible soluble porous sheets.

The soluble solid product may have a density in the range of from about 0.05 gram/cm ³ to about 0.5 gram/cm ³ , preferably from about 0.06 gram/cm ³ to about 0.4 gram/cm ³ , more preferably from about 0.07 gram/cm ³ to about 0.2 gram/cm ³ , most preferably from about 0.08 gram/cm ³ to about 0.15 gram/cm ³ .

In a preferred embodiment, at least one of the flexible soluble porous sheets comprises from about 10% to about 40%, preferably from about 15% to about 30%, more preferably from about 20% to about 25% of the aforementioned water-soluble polymer, based on the total weight of the sheet. , and/or from about 5% to about 80%, preferably from 10% to 70%, more preferably from 30% to 65% of the aforementioned surfactant, based on the total weight of said sheet. Additionally, said at least one sheet may comprise from about 0.1% to about 25%, preferably from about 0.5% to about 20%, more preferably from about 1% to about 15%, most preferably from about 2% to about 12% plasticizer based on the total weight of said sheet. In addition, said at least one sheet may include one or more additional ingredients selected from the group consisting of fabric care actives, dishwashing actives, hard surface cleaning actives, cosmetics actives and/ or skin care actives, personal care actives, hair care actives, oral care actives, feminine care actives, baby care actives, and any combinations thereof.

It is especially preferred that each of the flexible soluble porous sheets in the soluble solid product of the present invention has one or more of the following:

an average cell wall thickness of 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; and/or

a final moisture content of from about 0.5% to about 25%, preferably from about 1% to about 20%, more preferably from about 3% to about 10% by weight of said sheet; and/or

a basis weight of from about 50 grams/m ² to about 250 grams/m ² , preferably from about 80 grams/m ² to about 220 grams/m ² , more preferably from about 100 grams/m ² to about 200 grams/m ² ; and/or

density from about 0.05 gram/cm ³ to about 0.5 gram/cm ³ , preferably from about 0.06 gram/cm ³ to about 0.4 gram/cm ³ , more preferably from about 0.07 gram/cm 3 ³ to about 0.2 gram/cm ³ , most preferably from about 0.08 gram/cm ³ to about 0.15 gram/cm ³ ; and/or

specific surface area from about 0.03 m ² /g to about 0.25 m ² /g, preferably from about 0.04 m ² /g to 0.22 m ² /g, more preferably from about 0.05 m ² /g to about 0.2 m ² /g, most preferably from about 0.1 m ² /g to about 0.18 m ² /g.

These and other aspects of the present invention will become more apparent upon reading the following detailed description of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a multilayer soluble solid product in accordance with one embodiment of the present invention.

FIG. 2 is a prior art convection heating/drying scheme for making a flexible porous soluble solid sheet in a batch process.

FIG. 3 is a prior art microwave heating/drying scheme for making a flexible porous soluble solid sheet in a batch process.

FIG. 4 is a diagram of a heating/drying prior art forced hot air oven for making a flexible porous soluble solid sheet in a continuous process.

FIG. 5 is a diagram of conductive heating/drying from below for making a flexible porous soluble sheet having the features of the invention in a batch process in accordance with one embodiment of the present invention.

FIG. 6 is a rotary drum heating/drying scheme for making another flexible porous soluble sheet incorporating the features of the invention in a continuous process in accordance with another embodiment of the present invention.

FIG. 7A is a scanning electron microscope (SEM) image of the top surface of a flexible porous dissolvable sheet incorporating the inventive fabric care actives, which is made by a turntable heating/drying process.

FIG. 7B is an SEM image of the top surface of a comparative flexible porous soluble sheet containing the same fabric care actives as the sheet shown in FIG. 7A, but made by a method using a heating/drying oven with forced hot air jets.

FIG. 8A is an SEM image of the top surface of a flexible porous dissolvable sheet incorporating hair care actives, which is made by a method using a thermally conductive heating/drying scheme from below.

FIG. 8B is an SEM image of the top surface of a comparative flexible porous soluble sheet containing the same hair care actives as the sheet shown in FIG. 8A, but made by a method using a heating/drying scheme in a forced air jet oven.

DETAILED DESCRIPTION OF THE INVENTION

I. DEFINITIONS

As used herein, the term "soluble" refers to the ability of a product to completely or substantially dissolve in a sufficient amount of deionized water at 20°C and at atmospheric pressure for 8 (eight) hours without any agitation, leaving less than 5% of the mass. undissolved residues.

As used herein, the term "solid" refers to the ability of an article to substantially retain its shape (i.e., without any visible change in its shape) at 20°C and at atmospheric pressure, when it is not limited in space and when to it no external force is applied.

As used herein, the term "flexible" refers to the ability of an article to withstand stress without fracture or significant fracture when bent at an angle of 90° along a center line perpendicular to the longitudinal direction. Preferably, such an article is capable of undergoing significant elastic deformation and has a Young's modulus of at most 5 GPa, preferably at most 1 GPa, more preferably at most 0.5 GPa, most preferably at most 0.2 GPa.

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

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

As used herein, the term "open-cell foam" or "open-cell pore structure" refers to a solid, interconnected, polymer-containing matrix that forms a network of spaces or cells containing a gas, typically a gas (such as air), during the drying process no degradation of the foam structure occurs, and thus the physical strength and cohesion of the solid is maintained. Structure interconnectivity can be described as the percentage of open cells, which is measured using Test 3 below.

As used herein, the term “bottom surface” refers to the surface of the flexible porous soluble solid sheet of the present invention that is in direct contact with the support surface on which the aerated wet premix sheet is placed during the drying step, while the term “top surface” refers to the surface of said sheet opposite the bottom surface. In addition, such a solid sheet can be divided into 3 (three) regions according to its thickness, including an upper region adjacent to its upper surface, a lower region adjacent to its lower surface, and a middle region located between the upper and lower regions. The top, middle and bottom regions have the same thickness, i.e. the thickness of each of them is approximately 1/3 of the total thickness of the sheet.

As used herein, the term "aerating", "aerating" or "aeration" refers to a method of introducing a gas into a liquid or pasty composition by mechanical and/or chemical means.

As used herein, the term "direction of heating" refers to the direction in which a heat source applies thermal energy to an article, resulting in a temperature gradient in the article that decreases from one side of the article to the other side. For example, if a heat source located on one side of an article applies thermal energy to said article to create a temperature gradient decreasing from said one side to the opposite side, then the heating direction is considered to be from said one side to the opposite side. If both sides of such an article, or different parts of such an article, are heated simultaneously without an observable temperature gradient in such an article, then the heating is non-directional and there is no direction of heating.

As used herein, the term "substantially opposite" or "substantially deviated from" refers to two directions or two lines that have an angle of deviation of 90° or more.

As used herein, the term "substantially match" or "substantial match" refers to two directions or two lines that are less than 90° deviated.

As used herein, the term "primary heat source" refers to a heat source that provides more than 50%, preferably more than 60%, more preferably more than 70%, most preferably more than 80% of the total thermal energy absorbed by an object (e.g., a sheet of aerated wet preliminary mixtures according to the present invention).

As used herein, the term "controlled surface temperature" refers to a surface temperature that is relatively constant, i.e. less than +/-20% fluctuation, preferably less than +/-10% fluctuation, more preferably less than +/-5% fluctuation.

The term "substantially free" or "substantially free" means that the specified material at least has not been specifically added to the composition or product, or preferably is not present in such composition or product at a level that can be detected by analytical methods. It may include compositions or products in which said material is only present as an admixture of one or more materials specifically added to such compositions or products.

Conventional soluble solid products have relatively high length/width to thickness ratios, i.e. they are relatively thin to ensure that such articles dissolve quickly in water. Therefore, such soluble solids are typically in the form of relatively large but thin sheet products, which can be difficult to handle (e.g., too soft and flexible, easy to stick together, difficult to separate from each other during use) and which are not aesthetically pleasing to consumers. However, due to the limitations imposed by the requirement of solubility, there is little or no room for change or improvement in this product form.

The present inventors have surprisingly found that three-dimensional laminate structures formed by stacking multiple layers of flexible soluble porous hard sheets of the present invention (which have an open cell foam (OCF) structure defined by an open cell percentage of about 80 % to 100% and an overall average pore size of about 100 µm to about 2000 µm), together appear to be more soluble than a single layer structure that has the same aspect ratio. This allows such soluble solid products to be significantly expanded in the thickness direction to create three-dimensional product shapes that are easier to handle and more aesthetically pleasing to consumers (eg products in the form of thick mats or even cubes).

More specifically, in FIG. 1 shows a multi-layer soluble solid article 1 formed by stacking multiple layers of flexible soluble porous sheets 2, 4, 6 and 8 together characterized by a maximum dimension D and a minimum dimension z (which is perpendicular to the maximum dimension D), while the ratio D/z (hereinafter also referred to as "aspect ratio") is in the range from 1 to about 10, preferably from about 1.4 to about 9, preferably from about 1.5 to about 8, more preferably from about 2 to about 7 .

The multilayer soluble solid product of the present invention may have any suitable shape, regular or irregular, such as spherical, cubic, rectangular, polygonal, elongated, cylindrical, rod, leaf, flower, fan, star, disk, and the like. Shown in FIG. 1 the hexagonally shaped soluble solid product 1 has an aspect ratio of about 5.8-6. When the aspect ratio is 1, the soluble solid product is spherical. If the aspect ratio is about 1.4, the soluble solid product is cubic.

The multilayer soluble solid article of the present invention may have a minimum dimension z that is greater than about 3 mm but less than about 20 cm, preferably from about 4 mm to about 10 cm, more preferably from about 5 mm to about 30 mm.

The multilayer soluble solid article described above may comprise more than two such flexible soluble porous sheets. For example, it may contain from about 4 to about 50, preferably from about 5 to about 40, more preferably from about 6 to about 30 of these flexible soluble porous sheets. The improved OCF structures in flexible dissolvable porous sheets made in accordance with the present invention allow many sheets (eg 15-40) to be stacked on top of each other while still providing a satisfactory overall dissolution rate for the entire stack.

In a particularly preferred embodiment of the present invention, the multilayer soluble solid article comprises 15 to 40 layers of the flexible soluble porous sheets described above and has an aspect ratio in the range of about 2 to about 7.

Below are detailed descriptions of the compositions and processes for making such flexible soluble porous sheets, as well as methods for assembling them into a multilayer soluble solid product of the present invention.

II. OVERVIEW OF METHODS FOR MANUFACTURING SHEETS

To improve dissolution, WO 2010077627 describes a batch process for forming porous sheets of open-celled foam (OCF) having an open cell percentage of about 80% to 100%. Namely, a premix of raw materials is first formed, which is vigorously aerated and then thermally dried in batches (eg, in a convection oven or microwave oven) to form porous sheets with the desired OCF structures. Although such OCF structures significantly increase the dissolution rate of the resulting porous sheets, such sheets still leave a visually denser and less porous lower region with thicker cell walls. Such a lower high density region can adversely affect the flow of water through the sheets and thus adversely affect the overall dissolution rate of the sheets. If a plurality of such sheets are stacked on top of each other to form a sandwich structure, the "barrier" effect of the plurality of lower high density regions is particularly enhanced.

WO 2012138820 describes a process similar to that described in WO 2010077627, except that continuous drying of the aerated wet premix is achieved using, for example, a forced air jet oven (instead of a convection oven or microwave oven). OCF sheets formed by such a continuous drying process have improved uniformity/constancy of pore structures in different regions of the sheets. Unfortunately, in such OCF sheets, there are still rate-limiting factors such as a top surface with relatively smaller pore openings and a top area with relatively smaller pores (i.e., a crust-like top area), which can adversely affect water flow through the sheets and slow down their dissolution.

The OCF structures in the processes described above are formed at the drying stage with the simultaneous implementation of the mechanisms of water evaporation, bubble destruction, runoff of the intermediate liquid from the outer layers of thin-film bubbles to the boundaries of the plateau between the bubbles (which leads to the appearance of holes between the bubbles and the formation of open cells) and solidification of the pre-mixture. These mechanisms can be influenced by various process conditions, such as wet premix solids content, wet premix viscosity, gravity, and drying temperature, and the need to balance these process conditions to achieve controlled runoff and formation of the desired OCF structures.

It has been an unexpected and unexpected finding of the present invention that, in addition to the aforementioned process conditions, the resulting OCF structures can also be significantly influenced by the direction of thermal energy (ie the direction of heating) used in the drying step.

For example, if the heat energy is applied in a non-directional manner during the drying step (i.e., there is no clear direction of heating) or if the direction of heating substantially coincides with the direction of gravity (i.e., the deviation angle between them is less than 90°) for most of the time drying step, the resulting flexible porous soluble solid sheet typically has a top surface with smaller pore openings and large variations in pore size in different regions along the direction through its thickness. On the contrary, if the direction of heating deviates from the direction of gravity (i.e., the angle between them is 90° or more) during most of the time of the drying stage, the resulting solid sheet can have a top surface with larger pore openings and reduced variations in pore sizes in various areas along the direction through the thickness of such a sheet. Accordingly, the latter sheets are more receptive to water flowing through them and therefore more soluble than the first sheets.

Without being limited by any theory, it is believed that the coincidence or mismatch between the direction of heating and the direction of gravity during the drying step and the duration of this step can significantly affect the flow of the intermediate liquid between the bubbles, respectively, affecting the expansion of pores and the opening of pores in the solidified pre-blend to produce solid sheets with very different OCF structures. Such differences are more clearly illustrated in FIG. 2-5 below in this document.

FIG. 2 is a diagram of prior art convection heating/drying. In the drying step, the mold 10 (which may be made of any suitable materials such as metal, ceramic, or Teflon®) is filled with an aerated wet premix that forms a sheet 12 having a first side 12A (i.e., the top side) and the opposite second side 12B (i.e., the bottom side, since it is in direct contact with the abutment surface of the mold 10). In the drying step, such a mold 10 is placed in a convection oven at 130° C. for approximately 45-46 minutes. The convection oven heats the sheet 12 from above, i. e. in the direction of heating from top to bottom (shown by the shaded arrow), which forms a temperature gradient in the specified sheet 12, which decreases from the first side 12A to the opposite second side 12B. The direction of heating from top to bottom coincides with the direction of gravity (shown by the white arrow), and this coinciding position is maintained throughout the drying time. During drying, the liquid pre-mixture flows down by gravity to the lower region, while the direction of heating from top to bottom dries the upper region first and finally the lower region. As a result, a porous solid sheet is formed with an upper surface that contains numerous small-perforated pores formed by gas bubbles that have not had the opportunity to fully expand. Such a top surface with finer pore openings is not optimal for water penetration into the sheet, which can limit the rate of sheet dissolution. On the other hand, the lower region of such a sheet is dense and less porous, with larger pores formed by fully expanded gas bubbles, but in a very small amount, and the cell walls between the pores in such a lower region are thick due to the downward flow of liquid under the action of gravity. This dense lower region with fewer pores and thick cell walls is an additional factor limiting the overall dissolution rate of the sheet.

FIG. 3 is a diagram of prior art microwave heating/drying. In the drying step, a 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). This mold 30 is then placed in a low energy density microwave device (not shown) provided by Industrial Microwave System Inc. (North Carolina, USA) and operates at a power of 2.0 kW, a belt speed of 1 fpm and an ambient temperature of 54.4°C. Form 30 is placed in such a microwave device for approximately 12 minutes in the drying step. Such a microwave device heats the sheet 32 from the inside without any clear or constant direction of heating. Accordingly, no temperature gradient is generated in said sheet 32. During drying, the entire sheet 32 heats up at or near the same time, although gravity (indicated by the white arrow) still causes the liquid premixture to flow down to the lower region. As a result, the solidified sheet thus formed has pores with a more uniform distribution and a more uniform size compared to the sheet formed by the convection heating/drying scheme. However, gravity flow during the microwave drying step can still result in a dense bottom region with thick cell walls. In addition, simultaneous heating of the entire sheet 32 may still limit pore expansion and opening of pores on the top surface during the drying step, and the resulting sheet may still have a top surface with relatively finer pore openings. In addition, the microwave energy heats the water within the sheet 32 and causes such water to boil, which can lead to irregularly sized bubbles and unintended dense areas with thick cell walls.

FIG. 4 is a diagram of the heating/drying oven with forced hot air jets of the prior art. In the drying step, a mold 40 is filled with an aerated wet premix to form a sheet 42 having a first side 42A (top side) and an opposite second side 42B (bottom side). This mold 40 is then placed in a continuous forced hot air oven (not shown) under conditions similar to those described in WO 2012138820 (example 1, table 2). Such a continuous forced hot air jet oven heats the sheet 42 both from above and below in opposite and offset heating directions (shown by two cross-hatched arrows). Accordingly, no distinct temperature gradient is formed in said sheet 42 during drying, and the entire sheet 42 is heated almost simultaneously from both the top and bottom surfaces. Similar to the microwave heating/drying scheme shown in FIG. 3, the liquid pre-blend by gravity (indicated by the white arrow) continues to flow down to the bottom region in such a heating/drying pattern in the forced hot air oven shown in FIG. 4. As a result, the thus formed solidified sheet has pores with a more uniform distribution and a more uniform size compared to the sheet formed by the convection heating/drying scheme. However, gravitational runoff during the drying step can still result in a dense bottom region with thick cell walls. In addition, almost simultaneous heating of the entire sheet 42 from both may still limit pore expansion and opening of pores on the top surface during the drying step, and the resulting sheet may still have a top surface with relatively finer pore openings.

In contrast to the prior art heating/drying schemes described above, the present invention provides a heating/drying scheme for drying an aerated wet premix, in which the heating direction is purposefully configured to resist/reduce gravity runoff of liquid towards the lower region ( leading to reduced density and improved pore structures in the lower region) and with the possibility of allowing more time for air bubbles to expand near the top surface during drying (leading to the formation of much larger pore openings on the top surface of the resulting sheet). Both features serve to improve the overall dissolution rate of the leaf and are therefore desirable.

FIG. 5 is a thermally conductive bottom heating/drying scheme for making a flexible porous soluble sheet having the features of the invention, in accordance with one embodiment of the present invention. Specifically, the mold 50 is filled with an aerated wet premix, which forms a sheet 52 having a first side 52A (ie, bottom side) and an opposite second side 52B (ie, top side). In the drying step, such a mold 50 is placed on a heated surface (not shown), for example on top of a preheated Peltier element with a controlled surface temperature of about 125-130°C for about 30 minutes. Heat is transferred from the heated surface at the bottom of the mold 50 through the mold, heating the sheet 52 from below, i.e. in the direction of heating from bottom to top (shown by the shaded arrow), resulting in a temperature gradient in the specified sheet 52, which decreases from the first side 52A (bottom side) to the opposite second side 52B (upper side). This direction of heating from bottom to top is opposite to the direction of gravity (indicated by the white arrow), it is maintained throughout the entire drying time (i.e. the direction of heating is opposite to the direction of gravity for almost 100% of the drying time). During drying, the liquid premix still flows down to the lower region by gravity. However, the direction of heating from bottom to top dries the sheet from bottom to top, and the water vapor generated by heat in the lower region rises upwards and exits the solidifying matrix, so the flow of liquid down to the lower region is significantly limited and is "counteracted" / reduced by the solidifying matrix and ascending water vapor. Accordingly, the lower region of the resulting dry sheet is less dense and contains many pores with relatively thin cell walls. In addition, since the top region is the last area to be dried during this process, the air bubbles in the top region have sufficient time to expand to form significantly larger open pores on the top surface of the resulting sheet, which is particularly effective in facilitating water penetration into the sheet. Moreover, in the resulting sheet, the overall pore sizes are distributed more evenly across different regions (eg, top, middle, bottom).

FIG. 6 is a rotary drum heating/drying scheme for making a flexible porous soluble sheet having the features of the invention, in accordance with another embodiment of the present invention. In particular, a feed tray 60 is filled with an aerated wet premix 61. Above said feed tray 60 is a heated rotary cylinder 70 (also called a tumble dryer). Said heated tumble dryer 70 has a cylindrical heated outer surface that has a controlled surface temperature of about 130° C. and rotates clockwise (as shown by a thin curved arrow) to pick up aerated wet premix 61 from a supply chute 60. From an aerated wet premix mixture 61, a thin sheet 62 is formed on the cylindrical heated outer surface of the tumble dryer 70, which rotates and dries such aerated wet premix sheet 62 for approximately 10-15 minutes. A leveling knife (not shown) can be placed near the slurry pickup point to ensure a constant thickness of the sheet 62 being formed, although the thickness of the sheet 62 can be controlled by simply adjusting the viscosity of the aerated wet premix 61, the rotation speed, and the surface temperature of the tumble dryer 70. After drying, the sheet 62 can be grabbed manually or with a scraper 72 at the end of the rotation of the drum.

As shown in FIG. 6, the sheet 62 formed from the aerated wet premix 61 comprises a first side 62A (i.e., the bottom side) that is in direct contact with the heated outer surface of the heated tumble dryer 70 and an opposite second side 62B (i.e., the top side). ). Accordingly, heat from the tumble dryer 70 is transferred to the sheet 62 in the heating direction from the inside to the outside to heat first the first side 62A (bottom side) of the sheet 62 and then the opposite second side 62B (upper side). This direction of heating from the inside to the outside forms a temperature gradient in the sheet 62, which decreases from the first side 62A (bottom side) to the opposite second side 62B (upper side). The direction of heating from the inside to the outside changes slowly and constantly as the dryer 70 rotates, but along a very clear and predictable path (shown by the many outward hatched arrows in FIG. 6). The relative position of the direction of heating from the inside out and the direction of gravity (shown by the white arrow) also slows down and constantly changes in a similar clear and predictable way. For less than half the drying time (ie, when the direction of heating is below the horizontal dotted line), the direction of heating from the inside to the outside substantially coincides with the direction of gravity with an angle of deviation between them of less than 90°. During most of the drying time (i.e., when the direction of heating is at or above the horizontal dotted line), the direction of heating from the inside to the outside is opposite or substantially opposite to the direction of gravity with an angle of deviation between them of 90° or more. Depending on the initial "start" position of sheet 62 application, the direction of heating may be opposite or substantially opposite to the direction of gravity for more than 55% of the drying time (if application starts at the very bottom of the tumble dryer 70), preferably more than 60% of the drying time (if application starts from the higher position of the dryer drum 70 as shown in FIG. Therefore, during most of the drying stage, this slowing, rotating and changing direction of heating in the turntable heating/drying circuit can still serve to limit and "counteract"/reduce fluid runoff in the sheet 62 caused by gravity, resulting in improving the OCF structures in the sheet thus formed. The resulting sheet dried with the heated tumble dryer 70 also has a less dense bottom region with numerous, more uniformly sized pores and an upper surface with relatively larger pore openings. Moreover, in the resulting sheet, the overall pore sizes are distributed more evenly across different regions (eg, top, middle, bottom).

In addition to using the desired direction of heating (i.e. substantially deviated from the direction of gravity), as mentioned above herein, it may also be desirable and even important to carefully adjust the viscosity of the wet premix and/or its solids content, amount and aeration rate (air pump speed, mix head speed, air flow, aerated premix density, etc., which can affect the size and number of bubbles in the aerated premix and thus affect the size/distribution/amount/ characteristics of the pores in the cured sheet), drying temperature and drying time to achieve the optimal structure of OCF in the resulting sheet in accordance with the present invention.

More detailed descriptions of methods for making flexible porous soluble sheets having features of the invention, as well as the physical and chemical characteristics of such sheets, are given in the following sections.

III. METHOD FOR MANUFACTURING SOLID SHEETS IN ACCORDANCE WITH THE PRESENT INVENTION

The present invention proposes a new and improved method for making flexible porous soluble hard sheets, which includes the following steps: (a) forming a premix containing raw materials (for example, a water-soluble polymer, active ingredients such as surfactants, and optionally a plasticizer) , dissolved or dispersed in water or a suitable solvent, which has a viscosity of from about 1000 cP to about 25000 cP when measured at a temperature of about 40°C and 1 s ^-1 ; (b) aerating said premix (eg by introducing a gas into the wet slurry) to form an aerated wet premix; (c) forming said aerated wet premix into a sheet with opposite first and second sides; and (d) drying said formed sheet for a drying time of 1 minute to 60 minutes at a temperature of 70°C to 200°C along a heating direction that forms a temperature gradient decreasing from a first side to a second side of said formed sheet, wherein the direction heating is essentially deflected relative to the direction of gravity for more than half the drying time, i.e. the drying step is carried out with heating in the direction of heating generally "against gravity". This basically "against gravity" direction of heating can be achieved by various means, which include, but are not limited to, a thermally conductive bottom heating/drying circuit and a rotary drum heating/drying circuit, as shown herein above in FIG. 5 and 6, respectively.

Stage (A). Making a Wet Premix

The wet premix according to the present invention is generally prepared by mixing the solids of interest, including the water soluble polymer, surfactant(s) and/or other beneficial agents, optional plasticizer and other optional ingredients, with sufficient water or other solvent in the premix tank. The wet premix can be formed with a mechanical mixer. Mechanical mixers used in the present invention include, without limitation, inclined blade turbines or a MAXBLEND mixer (manufactured by Sumitomo Heavy Industries).

In the present invention, it is especially important to adjust the viscosity of the wet premix so that it is within a predetermined range of about 1000 cps to about 25000 cps when measured at 40°C and 1 s ^-1 . The viscosity of the wet premix has a significant effect on the pore expansion and pore opening of the aerated premix during the subsequent drying step, and wet premixes with different viscosities can form flexible porous soluble solid sheets with very different foam structures. On the one hand, if the wet premix is too thick/viscous (eg, has a viscosity of more than about 25,000 cP when measured at 40° C. and 1 s ⁻¹ ), aeration of such a wet premix can be difficult. More importantly, runoff of the intermediate liquid from the outer layers of thin film bubbles to the plateau boundaries of the 3D foam during the subsequent drying step can be adversely affected or significantly limited. It is believed that runoff of the intermediate liquid during drying is essential to ensure that the pores expand and open the pores in the wet preblend during the subsequent drying step. As a result, the flexible porous soluble solid sheet thus formed can have significantly smaller pores and less interconnectivity between pores (i.e., more “closed” pores than open pores), making it difficult for water to enter and leave such a sheet. On the other hand, when the wet premix is too thin/fluid (eg, has a viscosity of less than about 1000 cP when measured at 40° C. and 1 s ^-1 ), the aerated wet premix may not be sufficiently stable, i. air bubbles can burst, collapse or stick together too quickly in a wet premix after aeration and before drying. Therefore, the resulting solid sheet may be much less porous and denser than desired.

In one embodiment, the viscosity of the wet premix is in the range of about 3000 cps to about 24000 cps, preferably about 5000 cps to about 23000 cps, more preferably about 10000 cps to about 20000 cps when measured at 40°C and 1 s ^{- 1} . The premix viscosities are measured using a Malvern Kinexus Lab+ cone and flat geometry rheometer (CP1/50 SR3468 SS), gap width 0.054 mm, at 40°C and a shear rate of 1.0 reciprocal second over a period of 360 seconds.

In a preferred, but not essential, embodiment, the solids of interest are present in the wet premix in an amount of from about 15% to about 70%, preferably from about 20% to about 50%, more preferably from about 25% to about 45% of the total weight of said wet premix. Percent solids is the sum of the weight percent of all solids, semi-solids, and liquids, excluding water and any apparently volatile materials such as low boiling alcohols, based on the total weight of the process mixture. On the one hand, if the solids content of the wet premixture is too high, the viscosity of the wet premixture may increase to a level that will prevent or adversely affect the intermediate liquid from flowing off and prevent the formation of the desired predominantly porous, open-celled solid structure as described. in this document. On the other hand, if the solids content of the wet premix is too low, the viscosity of the wet premix may decrease to a level that will cause bubble burst/collapse/caking and a greater percentage (%) of pore structure shrinkage during drying, resulting in that the resulting solid sheet is significantly less porous and more dense.

Of the solids of interest, the wet premix of the present invention may contain surfactant(s) in an amount of from about 1% to about 75%, a water-soluble polymer from about 0.1% to about 25%, and optionally a plasticizer - from about 0.1% to about 25% of the total solids. Other active ingredients or beneficial agents can also be added to the premix.

Optionally, the wet premixture is preheated just before and/or during the aeration process at a temperature above ambient temperature, but below any temperatures that may cause decomposition of its components. In one embodiment, the wet premix is maintained at an elevated temperature in the range of about 40°C to about 100°C, preferably from about 50°C to about 95°C, more preferably from about 60°C to about 90°C, most preferably from about 75°C to about 85°C. In one embodiment, optional continuous heating is applied prior to the aeration step. In addition, additional heat may be applied during the aeration process to attempt to maintain the wet premix at this elevated temperature. This can be achieved by conductive heating from one or more surfaces, steam injection, or other treatment means. It is believed that preheating the wet premix prior to and/or during the aeration step may provide a means to reduce the viscosity of higher solids premixes to improve bubble entry into the mixture and form the desired hard sheet. It is desirable to achieve a higher percentage of solids, since this can reduce the overall energy requirements for drying. Thus, increasing the percentage of solids can lead to a decrease in water content and an increase in viscosity. As mentioned above herein, wet premixes with too high viscosities are undesirable for the practice of the present invention. Preheating is able to effectively counteract this increase in viscosity and thereby allow the production of a fast dissolving sheet even when high solids premixes are used.

Stage (B). Aerating Wet Premix

Aeration of the wet pre-mix is carried out in order to introduce sufficient air bubbles into the wet pre-mix for subsequent formation of OCF structures in it after drying. After sufficient aeration, a wet premix has a density that is significantly lower than that of an unaerated wet premix (which may contain a few unintentionally trapped air bubbles) or an insufficiently aerated wet premix (which may contain some bubbles, but with a much lower volume percentage of bubbles and significantly larger). The aerated wet premix preferably 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, even more preferably from about 0.15 g/ml to about 0.3 g/ml, most preferably from about 0.2 g/ml to about 0.25 g/ml ml.

In the present invention, aeration can be carried out by physical or chemical means. In one embodiment, this can be accomplished by injecting gas into the wet pre-blend via mechanical agitation, for example using any suitable mechanical processing means, including but not limited to: rotary stator mixer, planetary mixer, pressurized mixer, non-pressurized mixer , batch mixer, continuous mixer, semi-continuous mixer, high shear mixer, low shear mixer, submerged aerator, or any combination thereof. In another embodiment, this can be achieved by chemical means, such as using chemical blowing agents to generate gas in situ through a chemical reaction of one or more ingredients, including the production of carbon dioxide (CO ₂ gas) by some sort of gassing system.

In a particularly preferred embodiment, it has been found that aeration of the wet pre-blend can be carried out cost-effectively with an aerator or continuous pressure mixer, which is traditionally used in the food industry in the production of marshmallows. Continuous pressurized mixers can homogenize or aerate a wet pre-mix to form foam structures of high uniformity and stability with uniform bubble sizes. The unique design of the high shear rotor-stator mixing head can produce bubbles of uniform size in open-cell foam layers. Suitable continuous pressure aerators or mixers include Morton masher (Morton Machine Co., Motherwell, Scotland), Oakes automatic continuous mixer (E.T. Oakes Corporation, Hauppauge, NY), Fedco continuous mixer (The Peerless Group). , Sydney, Ohio), Mondo (Haas-Mondomix B.V., Netherlands), Aeros (Aeros Industrial Equipment Co., Ltd., Guangdong, China) and Preswhip (Hosokawa Micron Group, Osaka, Japan). For example, an Eros A20 continuous aerator can operate with a feed pump speed set of about 300-800 (preferably about 500-700), a mixing head speed set of about 300-800 (preferably about 400-600) and an air flow of about 50- 150 (preferably 60-130, more preferably 80-120), respectively. In another example, an Oakes automatic continuous mixer may be operated at a set mixing head speed of about 10-30 rpm (preferably about 15-25 rpm, more preferably about 20 rpm) with an air flow of about 10-30 liters per hour (preferably about 15-25 l/h, more preferably about 19-20 l/h).

In another specific embodiment, the aeration of the wet pre-mix can be accomplished with a rotating rod that is part of the rotary tumble dryer, namely a feed tray component in which the wet pre-mix is stored prior to being applied to the heated outer surface of the tumble dryer and dried. The rotating rod is typically used to agitate the wet pre-blend to prevent phase separation or settling in the feed tray during the waiting time before being applied to the heated rotary drum of the dryer drum. In the present invention, such a rotating rod may be operated at a rotation speed in the range of about 150 to about 500 rpm, preferably about 200 to about 400 rpm, more preferably about 250 to about 350 rpm, to mix the wet premix. mixture at the interface with air and provide sufficient mechanical agitation necessary to achieve the necessary aeration of the wet pre-mix.

As mentioned above herein, the wet premix can be maintained at an elevated temperature during the aeration process to adjust the viscosity of the wet premix for optimized aeration and controlled runoff during drying. For example, when aeration is achieved by the use of a rotating tumbler rod, the temperature of the aerated wet premix in the feed pan is typically maintained at about 60°C during initial aeration by the rotatable rod (while the tumbler remains stationary) and then heated up to about 70°C when the turntable heats up and begins to rotate.

The size of the bubbles in the aerated wet pre-blend promotes uniform layers in the OCF structures of the resulting solid sheet. In one embodiment, the bubble size in the aerated wet premix is from about 5 to about 100 microns; and in another embodiment, the bubble size is from about 20 microns to about 80 microns. Due to the homogeneity of the bubble sizes, the resulting solid sheets have constant density values.

Stage C. Formation of the sheet

After sufficient aeration, the aerated wet premix is formed into one or more sheets with opposite first and second sides. The sheet forming step may be carried out by any suitable means, such as extrusion, casting, molding, vacuum forming, pressing, printing, coating, and the like. More specifically, the aerated wet premix sheet can be formed by: (i) casting the mixture into shallow cavities, or trays, or specially designed sheet molds; (ii) extruding the mixture onto a continuous belt or dryer screen; (iii) applying the mixture to the outer surface of the rotary dryer. The bearing surface on which the sheet is formed is preferably formed or coated with anti-corrosive, non-reactive and/or non-adhesive materials such as metal (e.g. steel, chromium, etc.), TEFLON®, polycarbonate, NEOPRENE®, HDPE, LDPE, rubber, glass, etc.

The formed sheet of aerated wet premix preferably has a thickness in the range of 0.5 mm to 4 mm, preferably 0.6 mm to 3.5 mm, more preferably 0.7 mm to 3 mm, even more preferably 0.8 mm to 2 mm, most preferably from 0.9 mm to 1.5 mm. Controlling the thickness of such a formed aerated wet premix sheet can be important to ensure that the resulting solid sheet has the desired OCF structures. If the formed sheet is too thin (eg, less than 0.5 mm thick), many of the air bubbles trapped in the aerated wet premix will expand during the subsequent drying step to form through holes through the entire thickness of the resulting solid sheet. Such through holes, if too many, can significantly compromise both the overall structural integrity and the aesthetic appearance of the sheet. If the formed sheet is too thick, not only does it require a longer drying time, but it also results in a hard sheet with large pore size variations between different regions (e.g., top, middle, and bottom regions) throughout the thickness, because the longer the drying time , the greater the imbalance of forces may occur due to rupture / destruction / adhesion of bubbles, liquid runoff, pore expansion, pore opening, water evaporation, etc.

More importantly, it is easier to assemble multiple layers of relatively thin sheets into the multilayer structures of the present invention with the desired aspect ratio, while still maintaining satisfactory pore structures for rapid dissolution as well as efficient drying in a relatively short drying time.

Stage (D). Drying by heating against gravity

A key feature of the present invention is the use of a direction of heating against gravity during the drying step, either for the entire drying time or for at least more than half of the drying time. Without being bound by any theory, it is believed that such direction of heating against gravity can reduce or counteract excessive runoff of the intermediate liquid to the bottom of the formed sheet during the drying step. Also, since the top surface dries last, this gives air bubbles near the top surface of the formed sheet more time to expand and form pore openings on the top surface (because once the wet matrix dries, air bubbles can no longer expand and form holes on the surface). Therefore, the solid sheet formed by drying under such heat against gravity is characterized by improved OCF structures which provide faster dissolution as well as other unexpected and unanticipated benefits.

In a specific embodiment, direction of heating against gravity is provided by a conductive heating/drying scheme that is identical or similar to that shown in FIG. 5. For example, an aerated wet premix can be molded to form a sheet with two opposite sides. The mold can then be placed on a hotplate, or a heated moving belt, or any other suitable heating device with a flat heated surface characterized by a controlled surface temperature from about 80°C to about 170°C, preferably from about 90°C to about 150°C. , more preferably from about 100°C to about 140°C. Thermal energy is transferred from the flat heated surface of the bottom surface of the aerated wet premix sheet by conduction, so that the solidification of the sheet starts from the bottom region and gradually moves upward until reaching the top region last. In order to ensure that the direction of heating is predominantly directed against gravity (i.e., substantially deviated from the direction of gravity) during this process, it is preferred that the heated surface is the primary heat source for said sheet during drying. If any other sources of heating are present, the general direction of heating can be changed accordingly. More preferably, the heated surface is the sole source of heat for such a sheet during drying.

In another particular embodiment, the direction of heating against gravity is provided by a rotary drum heating/drying scheme, which is also referred to as a drum dryer or roller dryer, similar to that shown in FIG. 6. Drum drying is one type of contact drying process that is used to remove liquids from a viscous raw material premix on the outer surface of a heated rotating drum (also called a roll or cylinder) at relatively low temperatures to form sheet products. This is a continuous drying process, which is especially suitable for drying large volumes. Because drying is carried out at relatively low temperatures by contact heating/drying, it is generally highly energy efficient and does not adversely affect the integrity of the composition of the raw materials.

The heated rotary cylinder used in the tumble dryer is internally heated, for example by steam or electricity, and driven at a predetermined speed by an electric drive mounted on a base bracket. The heated pivot cylinder or drum preferably has an outside diameter in the range of about 0.5 meters to about 10 meters, preferably about 1 meter to about 5 meters, more preferably about 1.5 meters to about 2 meters. It may have a controlled surface temperature from about 80°C to about 170°C, preferably from about 90°C to about 150°C, more preferably from about 100°C to about 140°C. In addition, such a heated rotary cylinder rotates at a speed of from about 0.005 rpm to about 0.25 rpm, preferably from about 0.05 rpm to about 0.2 rpm, more preferably from about 0.1 rpm to about 0.18 rpm.

Preferably, a non-tacky coating is applied to the outer surface of said heated rotary cylinder. The non-tacky coating may be applied to the outer surface of the heated rotary drum, or it may be attached to a carrier on the outer surface of the heated rotary drum. The carrier includes, without limitation, heat resistant nonwovens, heat resistant carbon fiber, heat resistant metal or non-metal mesh, and the like. The non-tacky coating can effectively protect the structural integrity of a sheet product from damage during sheet formation.

Also provided is a feed mechanism on the base bracket for supplying the aerated wet premix of raw materials as described above herein to the heated turntable, thereby forming a thin layer of viscous premix on the outer surface of the heated turntable. Thus, such a thin layer of pre-mixture is dried with a heated rotary drum by means of contact heating/drying. The feed mechanism includes a feed chute mounted on a base bracket, said feed chute being installed downstream of at least one (preferably two) feed bin(s), a visualization device to dynamically monitor the feed, and an adjustment device to adjust the position and angle of the hopper for submission. By using said adjustment device to adjust the distance between said supply hopper and the outer surface of the heated turntable, the need for different thicknesses of the formed sheet product can be met. The control device can also be used to set different feed hopper angles to meet material speed and quality requirements.
The feed chute may also include a rotating rod to agitate the wet premix therein to avoid phase separation and settling prior to applying the wet premix to the outer surface of the heated rotary cylinder. Such a rotating rod, as mentioned above in this document, can also be used to aerate the wet premix as needed.

In addition, to prevent rapid heat loss, a thermal screen can be provided mounted on the base bracket. The thermal shield also effectively saves the energy required for the heated turntable, thereby reducing energy consumption and saving costs. The thermal screen is a modular assembly or one-piece design and can be freely detached from the base bracket. An aspiration device for sucking hot steam is also installed on the thermal screen in order to prevent water condensate from entering the formed sheet product.

An optional static scraper mechanism mounted on the base bracket may also be provided to scrape or grip the sheet product already formed with the heated turntable. A static scraper mechanism can be mounted on or on one side of the base arm to move the already formed sheet product downstream for further processing. The static scraper mechanism can be moved automatically or manually towards or away from the heated rotary drum.

The process for manufacturing a flexible porous soluble solid product in accordance with the present invention is as follows. First of all, the heated swivel drum with a non-stick coating on the base bracket is electrically driven. The control device then adjusts the feed mechanism so that the distance between the feed hopper and the outer surface of the heated rotary drum reaches a predetermined value. Wherein the supply hopper supplies an aerated wet premix containing all or some of the raw materials for producing a flexible porous soluble solid product to the outer surface of a heated rotary drum to form on it a thin layer of said aerated wet premix of the required thickness, as described above in the previous section of this document. The aspiration device of the thermal screen optionally removes the hot steam generated by the heated rotary drum. The static scraper mechanism then scrapes/grabs the dried/hardened sheet formed by a thin layer of aerated wet premix after it has been dried with a heated rotary drum at a relatively low temperature (eg 130°C). The dried/hardened sheet can also be separated manually or automatically without the use of such a static scraper mechanism and then rolled up using a roller bar.

The total drying time according to the present invention depends on the compositions and solids content of the wet preblend, the drying temperature, the heat input and the thickness of the sheet material to be dried. The drying time is preferably from about 1 minute to about 60 minutes, preferably from about 2 minutes to about 30 minutes, more preferably from about 2 to about 15 minutes, even more preferably from about 2 to about 10 minutes, most preferably from about 2 to about 10 minutes. about 5 minutes.

During such a drying time, the direction of heating is set to be 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., as in the heating/drying scheme described above. on a rotary drum), more preferably more than 75% or even 100% of the drying time (eg, as in the thermally conductive heating/bottom drying scheme described above herein). Further, the aerated wet premix sheet may be dried in a first heating direction for a first period of time and then in a second, opposite heating direction for a second period of time, the first heating direction being substantially opposite to the direction of gravity, and the first time period is 51% to 99% (eg, 55%, 60%, 65%, 70% to 80%, 85%, 90% or 95%) of the total drying time. Such reversal of heating direction can easily be achieved with various other configurations not shown here, such as an elongated, tortuously shaped heated belt that can be rotated along a longitudinal central axis.

IV. Physical Characteristics of Hard Sheets Including Features of the Invention

The flexible porous soluble solid sheet formed by the process steps described above is characterized by improved pore structures that allow water to more easily penetrate the sheet and dissolve the sheet in water more quickly. Such improved pore structures are achieved primarily by controlling various processing conditions as described herein above and are relatively independent or less influenced by the chemistry or specific ingredients used to make such a sheet.

In general, such a solid sheet may be characterized by: (i) an open cell percentage of from about 80% to 100%, preferably from about 85% to 100%, more preferably from about 90% to 100% as measured by Test 3 described below. in this document; and (ii) an overall average pore size of from about 100 µm to about 2000 µm, preferably from about 150 µm to about 1000 µm, more preferably from about 200 µm to about 600 µm, as measured by the CT scan method described in Test 2 hereinafter. document. The overall average pore size determines the porosity of the OCF structure of the present invention. The percentage of open cells determines the interconnectivity between the pores in the OCF structure of the present invention. The relationship of the OCF structure can also be described as a star volume (Star Volume) or structural model index (Structure Model Index - SMI) in accordance with the description in WO 2010077627 and WO 2012138820.

Such a solid sheet of the present invention has opposite top and bottom surfaces, wherein its top surface may have an average surface pore diameter of greater than about 100 μm, preferably greater than about 110 μm, more preferably greater than about 120 μm, even 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 herein. Compared to solid sheets formed using prior art heating/drying circuits (e.g., convection, microwave, or forced air jet ovens), a solid sheet formed using a heating/drying circuit according to the present the invention has a significantly larger average pore diameter on its upper surface (as shown in FIGS. 7A-7B and 8A-8B, which are described in detail in example 1 below), because with the specially designed directional heating of the present invention, the upper surface of the formed sheet is aerated wet the premix is dried/solidified last and the air bubbles near the top surface have the longest time to expand and form larger pore openings on the top surface.

In addition, the solid sheet formed by the heating/drying scheme of the present invention has a more uniform pore size distribution between different regions in its thickness direction compared to sheets formed by prior art heating/drying schemes. In particular, the solid sheet of the present invention comprises an upper region adjacent to the upper surface, a lower region adjacent to the lower surface, and a middle region located therebetween, wherein the upper, middle, and lower regions have the same thickness. Each of the top, middle, and bottom regions of such a solid sheet has an average pore size, wherein the ratio of the average pore size in the bottom region to the average pore size in the top region (i.e., the ratio of the average pore size in the bottom and top regions) is from about 0.6 to about 1.5, preferably about 0.7 to about 1.4, preferably about 0.8 to about 1.3, more preferably about 1 to about 1.2. In comparison, a solid sheet formed with a prior art forced hot air oven heating/drying scheme can have an average pore size ratio in the lower and upper regions of greater than 1.5, typically around 1.7-2.2 (as shown in example 1 below in this document). In addition, the solid sheet of the present invention may have a ratio of the average pore size in the lower region to the average pore size in the middle region 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 a ratio of the average pore size in the middle region to the average pore size in the upper region from about 1 to about 1.5, preferably from about 1 up to about 1.4, more preferably from about 1 to about 1.2.

Moreover, the relative standard deviation (RSD) between the average pore sizes in the top, middle and bottom regions of the solid sheet of the present invention is not more than 20%, preferably not more than 15%, more preferably not more than 10%, most preferably not more than 5%. In contrast, a solid sheet formed with a prior art forced hot air oven heating/drying scheme may have a relative standard deviation (RSD) between the average pore sizes in the top, middle, and bottom regions of more than 20%, probably , more than 25% or even more than 35% (as shown in example 1 below in this document).

Preferably, the solid sheet of the present invention is further characterized by an average cell wall thickness of 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 described below in this document.

The solid sheet of the present invention may contain a small amount of water. It preferably has a final moisture content of 0.5% to 25%, preferably 1% to 20%, more preferably 3% to 10% by weight of said solid sheet as measured by Test 4 described herein below. Appropriate final moisture content in the resulting solid sheet can provide the desired flexibility/deformability of the sheet as well as provide consumers with a soft/smooth sensory experience. If the final moisture content is too low, the sheet may be too brittle or stiff. If the final moisture content is too high, the sheet may be too sticky and its overall structural integrity may be compromised.

The solid sheet of the present invention may have a thickness in the range of from about 0.6 mm to about 3.5 mm, preferably from about 0.7 mm to about 3 mm, more preferably from about 0.8 mm to about 2 mm, most preferably from about 1 mm to about 1.5 mm. The thickness of a solid sheet can be measured using test 5, described later in this document. The solid sheet after drying may be slightly thicker than the aerated wet premix sheet due to the expansion of the pores, which in turn leads to an overall increase in volume.

The solid sheet of the present invention may further have a basis weight of from about 50 gram/m ² to about 250 gram/m ² , preferably from about 80 gram/m ² to about 220 gram/m ² , more preferably from about 100 gram/m ² to about 200 grams/m ² when measured using test 6, described below in this document.

In addition, the solid sheet of the present invention may have a density in the range of about 0.05 gram/cm ³ to about 0.5 gram/cm ³ , preferably from about 0.06 gram/cm ³ to about 0.4 gram/cm ³ , more preferably from about 0.07 gram/cm ³ to about 0.2 gram/cm ³ , most preferably from about 0.08 gram/cm ³ to about 0.15 gram/cm ³ when measured using test 7 described below in this document. The density of the solid sheet of the present invention is lower than that of the aerated wet premix sheet, also due to pore expansion which in turn leads to an overall increase in volume.

In addition, the solid sheet of the present invention may have a specific surface area of from about 0.03 m ² /g to about 0.25 m ² /g, preferably from about 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 as measured by Test 8 described herein below. The specific surface area of a solid sheet of the present invention can be indicative of its porosity and can affect the dissolution rate: for example, the greater the specific surface area, the more porous the sheet is and the faster its dissolution rate.

V. Solid sheet compositions having features of the invention

1. Water soluble polymer

As mentioned above herein, the flexible porous soluble solid sheet of the present invention may be formed from a wet preblend containing a water soluble polymer. Such a water-soluble polymer in the resulting solid sheet can function as a film former, a structurant, as well as a carrier for other active ingredients (eg, surfactants, emulsifiers, fillers, chelators, fragrances, coloring agents, etc.).

Preferably, the wet premix may contain from about 3% to about 20% water soluble polymer by weight of the premix, in one embodiment from about 5% to about 15% water soluble polymer by weight of the premix, in one embodiment from about 7% to about 10% water soluble polymer by weight premix.

After drying, it is preferred that the water soluble polymer be present in the flexible porous soluble solid sheet of the present invention in an amount in the range of about 10% to about 40%, preferably about 15% to about 30%, more preferably about 20% to about 25% of the total weight of the solid sheet. In a particularly preferred embodiment of the present invention, the total amount of water soluble polymer(s) present in the flexible porous soluble solid sheet of the present invention is not more than 25% of the total weight of such article.

Water-soluble polymers suitable for the practice of the present invention may be selected from polymers having a weight average molecular weight in the range of from about 50,000 to about 400,000 Daltons, preferably from about 60,000 to about 300,000 Daltons, more preferably from about 70,000 to about 200,000 Daltons, most preferably from about 80,000 to about 150,000 daltons. The weight average molecular weight is calculated by summing the average molecular weights of each polymeric feedstock multiplied by their respective relative weight percentages based on the total weight of the polymers present in the porous solid. The weight average molecular weight of the water soluble polymer used in the present invention can affect the viscosity of the wet preblend, which in turn can affect the number and size of bubbles in the aeration step, as well as the results of expansion/opening of pores in 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 certain surfactants.

The water-soluble polymers of the present invention may include, without limitation, synthetic polymers, including polyvinyl alcohols, polyvinyl pyrrolidones, polyalkylene oxides, polyacrylates, caprolactams, polymethacrylates, polymethyl methacrylates, polyacrylamides, polymethylacrylamides, polydimethylacrylamides, polyethylene glycol monomethacrylates, copolymers of acrylic acid and methyl acrylate, polyurethanes, polycarboxylic acids, polyvinyl acetates, polyesters, polyamides, polyamines, polyethyleneimines, copolymers of maleic anhydride/(acrylate or methacrylate), copolymers of methyl vinyl ether and maleic anhydride, copolymers of vinyl acetate and crotonic acid, copolymers of vinylpyrrolidone and vinyl acetate, copolymers of vinylpyrrolidone and caprolactam, copolymers of vinylpyrollidone/vinyl acetate, copolymers of anionic, cationic and amphoteric monomers and combinations thereof.

The water-soluble polymers of the present invention can also be selected from polymers of natural origin, including those of plant origin, examples of which include gum karaya, gum tragacanth, gum arabic, acemannan, glucomannan, gum arabic, gum ghatti, whey protein isolate, and soy protein isolate; seed extracts including guar gum, locust bean gum, quince seeds and psyllium seeds; seaweed extracts such as carrageenan, alginates and agar; fruit extracts (pectins); polymers of microbial origin, including xanthan gum, gellan gum, pullulan, hyaluronic acid, chondroitin sulfate and dextran; as well as animal-derived polymers including casein, gelatin, keratin, keratin hydrolysates, sulfonic keratins, albumin, collagen, glutelin, glucagons, gluten, zein, and shellac.

Modified natural polymers can also be used as water soluble polymers in the present invention. Suitable modified natural polymers include, without limitation, cellulose derivatives such as hydroxypropylmethylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, methylcellulose, hydroxypropylcellulose, ethylcellulose, carboxymethylcellulose, cellulose acetate phthalate, nitrocellulose, and other cellulose ethers or esters; and guar derivatives such as hydroxypropyl guar.

The water-soluble polymer of the present invention may include starch. As used herein, the term "starch" includes both naturally occurring starches and modified starches. Typical natural sources of starches may include grains, tubers, roots, legumes, and fruits. More specific natural sources may include corn, peas, potatoes, bananas, barley, wheat, rice, sago, amaranth, tapioca, arrowroot, canna, sorghum and their waxy or high amylase varieties. Natural starches can be modified by any modification method known in the art to form modified starches, including physically modified starches, sheared starches, or thermally inhibited starches; chemically modified starches, such as cross-linked, acetylated and organically esterified, hydroxyethylated and hydroxypropylated, phosphorylated and inorganically esterified, cationic, anionic, nonionic, amphoteric and zwitterionic, as well as their succinate and substituted succinate derivatives; the present invention may also use conversion products derived from any of the starches, including slurry starches obtained by oxidation, enzymatic saccharification, acid hydrolysis, thermal or acid dextrinization, heat treatment and shear products; and gelatinized starches known in the art.

Preferred water-soluble polymers of the present invention include polyvinyl alcohols, polyvinyl pyrrolidones, polyalkylene oxides, starch and starch derivatives, pullulan, gelatin, hydroxypropyl methylcelluloses, methylcelluloses, and carboxymethylcelluloses. More preferred water-soluble polymers of the present invention include polyvinyl alcohols and hydroxypropyl methylcelluloses.

The most preferred water soluble polymers of the present invention are polyvinyl alcohols which have a degree of hydrolysis of from about 40% to about 100%, preferably from about 50% to about 95%, preferably from about 70% to about 92%, preferably from about 80% to about 90%. Commercially available polyvinyl alcohols include those from Celanese Corporation (Texas, USA) under the brand name CELVOL, including, without limitation, CELVOL 523, CELVOL 530, CELVOL 540, CELVOL 518, CELVOL 513, CELVOL 508, CELVOL 504; from Kuraray Europe GmbH (Frankfurt, Germany) under the trademarks Mowiol® and POVAL™; and PVA 1788 (also known as PVA BP17) available in the market from various vendors including Lubon Vinylon Co. (Nanjing, China); and their combinations. In a particularly preferred embodiment of the present invention, the flexible porous soluble solid sheet comprises polyvinyl alcohol having a weight average molecular weight in the range of 80,000 to about 150,000 Daltons and a degree of hydrolysis in the range of about 80% to about 90% in an amount of from about 10% to about 25%. , more preferably from about 15% to about 23% of the total weight of such an article.

In addition to polyvinyl alcohols, as mentioned above herein, any single starch or combination of starches may be used as filler material in such an amount as to reduce the total amount of water soluble polymers required, provided that it helps to provide the solid sheet with the desired structure and physical properties. - chemical characteristics as described in this document. However, too much starch may compromise the solubility and structural integrity of the sheet. Thus, in preferred embodiments of the present invention, it is desirable that the solid sheet contains no more than 20%, preferably 0% to 10%, more preferably 0% to 5%, most preferably 0% to 1% starch by weight of said solid. sheet.

2. Surfactants (surfactants)

In addition to the water-soluble polymer described above, the solid sheet product of the present invention contains one or more surfactants. Surfactants can act as emulsifiers during the aeration process to create enough stable bubbles to form the desired structure of the OCF of the present invention. In addition, surfactants can act as active ingredients to provide the desired cleansing effect.

In a preferred embodiment of the present invention, the solid sheet contains one or more surfactants selected from the group consisting of anionic surfactants, nonionic surfactants, cationic surfactants, zwitterionic surfactants, amphoteric surfactants, polymeric surfactants, or combinations thereof. Depending on the desired application of such a solid sheet and the desired benefit to the user, various surfactants can be selected. One of the advantages of the present invention is that solid sheet OCF structures can include a high content of surfactants while still providing fast dissolution. Therefore, highly concentrated cleansing compositions can be incorporated into the solid sheets of the present invention to provide consumers with new, superior cleansing experiences.

Surfactants used in the present invention may include both surfactants in the traditional sense (i.e. substances that provide a noticeable foaming effect to the consumer) and emulsifiers (i.e. substances that are not intended to provide any - or foaming efficiency, and are primarily intended as an aid in the technological process when creating a stable foam structure). Examples of emulsifiers for use as a surfactant component in the present invention include mono- and diglycerides, fatty alcohols, polyglycerol esters, propylene glycol esters, sorbitan esters, and other emulsifiers known or otherwise commonly used to stabilize air interfaces.

The total amount of surfactants in the solid sheet product of the present invention may range from about 5% to about 80%, preferably from about 10% to about 70%, more preferably from about 30% to about 65% of the total weight of said solid sheet product. Accordingly, the wet premix may contain from about 1% to about 40% surfactant by weight of the wet premix, in one embodiment from about 2% to about 35% surfactant by weight of the wet premix, in one embodiment from about 5% to about 30% surfactant by weight of the wet premix.

In a preferred embodiment of the present invention, the solid sheet product of the present invention is a cleaning product containing from about 30% to about 80%, preferably from about 40% to about 70%, more preferably from about 50% to about 65% of one or more surface -active substances based on the total weight of said solid sheet product. In such cases, the wet premix may contain from about 10% to about 40% surfactant by weight of the wet premix, in one embodiment from about 12% to about 35% surfactant by weight of the wet premix, in one embodiment from about 15%. up to about 30% surfactant by weight of the wet premix.

Non-limiting examples of anionic surfactants suitable for use in the present invention include alkyl and alkyl ether sulfates, sulfated monoglycerides, sulfonated olefins, alkylaryl sulfonates, primary or secondary alkane sulfonates, alkyl sulfosuccinates, acyl taurates, acyl isethionates, alkyl glyceryl ether sulfonate, sulfonated methyl esters, sulfonated fatty acids, alkyl phosphates, acyl glutamates, acyl sarcosinates, alkyl sulfoacetates, acylated peptides, alkyl ether carboxylates, acyl lactylates, anionic fluorinated surfactants, sodium lauroyl glutamate, and combinations thereof.

One category of anionic surfactants particularly suitable for the practice of the present invention includes C ₆ -C ₂₀ linear alkylbenzene sulphonate (LAS) surfactants. Surfactants based on LAS are well known in the art and can be easily obtained by sulfonation of commercially available linear alkyl benzenes. Examples of C ₁₀ -C ₂₀ linear alkylbenzenesulfonates that can be used in the present invention include alkali metal, alkaline earth metal or ammonium salts with C ₁₀ -C ₂₀ linear alkylbenzenesulfonic acids, preferably sodium, potassium, magnesium and/or ammonium salts of C ₁₁ - C ₁₈ or C ₁₁ -C ₁₄ linear alkylbenzenesulfonic acids. More preferred are the sodium or potassium salts of C ₁₂ and/or C ₁₄ linear alkylbenzenesulfonic acids (LAS), and most preferred is the sodium salt of C ₁₂ and/or C ₁₄ linear alkylbenzenesulfonic acids, ie. sodium dodecylbenzenesulfonate or sodium tetradecylbenzenesulfonate.

LAS provides an excellent cleaning effect and is particularly suitable for applications in laundry detergent applications. It has been surprisingly and unexpectedly found within the scope of the present invention that when using polyvinyl alcohol having a higher weight average molecular weight (e.g., about 50,000 to about 400,000 daltons, preferably about 60,000 to about 300,000 daltons, more preferably about 70,000 to about 200,000 daltons, most preferably about 80,000 to about 150,000 daltons) as film former and carrier LAS can be used as the base surfactant, i. e. present in an amount of more than 50% by weight of the total surfactant content in the solid sheet, without adversely affecting the film-forming ability and stability of the entire composition as a whole. Accordingly, in a specific embodiment of the present invention, LAS is used as the main surfactant in the solid sheet. If present, the amount of LAS in the solid sheet of the present invention may range from about 10% to about 70%, preferably from about 20% to about 65%, more preferably from about 40% to about 60% of the total weight of the solid sheet.

Another category of anionic surfactants suitable for the practice of the present invention includes sodium trideceth sulfates (STS) having a weight average alkoxylation degree ranging from about 0.5 to about 5, preferably from about 0.8 to about 4 , more preferably from about 1 to about 3, most preferably from about 1.5 to about 2.5. Tridecet is a branched alkoxylated hydrocarbon with 13 carbon atoms, containing in one embodiment, on average, at least 1 branch of the methyl group per molecule. The STS used in the present invention may include ST(EOxPOy)S, where EOx refers to ethylene oxide repeat units with a repeat number x ranging from 0 to 5, preferably 1 to 4, more preferably 1 to 3, and POy refers to repeating propylene oxide units with a repeating number y ranging from 0 to 5, preferably from 0 to 4, more preferably from 0 to 2. It will be understood that a material such as ST2S with a weight average ethoxylation degree, for example about 2, may contain a significant number of molecules ethoxylate-free, 1 mole ethoxylate, 3 mole ethoxylate, etc., while the ethoxylation distribution can be wide, narrow, or truncated, still resulting in an overall weight average ethoxylation degree of about 2. STS is particularly suitable for use in areas related to personal hygiene, and in the framework of the present invention, it was found in an unexpected and unforeseen way that when using floor and vinyl alcohol having a higher weight average molecular weight (e.g., about 50,000 to about 400,000 Daltons, preferably about 60,000 to about 300,000 Daltons, more preferably about 70,000 to about 200,000 Daltons, most preferably about 80,000 to about 150,000 Daltons) in as a film former and carrier, STS can be used as the main surfactant, i.e. present in an amount of more than 50% by weight of the total surfactant content in the solid sheet, without adversely affecting the film-forming ability and stability of the entire composition as a whole. Accordingly, in a particular embodiment of the present invention, STS is used as the base surfactant in the solid sheet. If present, the amount of STS in the solid sheet of the present invention may range from about 10% to about 70%, preferably from about 20% to about 65%, more preferably from about 40% to about 60% of the total weight of the solid sheet.

Another category of anionic surfactants suitable for the practice of the present invention includes alkyl sulfates. These materials have the corresponding formulas ROSO ₃ M, where R is an alkyl or alkenyl containing from about 6 to about 20 carbon atoms, x = from 1 to 10, and M is a water-soluble cation such as ammonium, sodium, potassium, and triethanolamine . Preferably, R contains from about 6 to about 18, preferably from about 8 to about 16, more preferably from about 10 to about 14 carbon atoms. Non-alkoxylated C ₆ -C ₂₀ linear or branched alkyl sulfates (AS) have previously been considered the preferred surfactants in soluble solid sheets, especially as the main surfactant in them, due to compatibility with low molecular weight polyvinyl alcohols (for example, with a weight average molecular weight of not over 50,000 daltons) in terms of film-forming ability and storage stability. However, it has been surprisingly and unexpectedly found within the scope of the present invention that when using polyvinyl alcohol having a higher weight average molecular weight (e.g., about 50,000 to about 400,000 Daltons, preferably about 60,000 to about 300,000 Daltons, more preferably about 70,000 to about 200,000 daltons, most preferably about 80,000 to about 150,000 daltons) as film former and carrier, other surfactants such as LAS and/or STS can be used as the base surfactant in the solid sheet without adversely affecting film forming ability and stability the entire composition as a whole. Therefore, in a particularly preferred embodiment of the present invention, it is desirable to provide a solid sheet containing alkyl sulfates in an amount of not more than about 20%, preferably from 0% to about 10%, more preferably from 0% to about 5%, most preferably from 0% to about 1% by weight of said solid sheet.

Another category of anionic surfactants suitable for the practice of the present invention includes C ₆ -C ₂₀ linear or branched alkylalkoxy sulfates (AAS). Among this category, particularly preferred are linear or branched alkylethoxy sulfates (AES) having the corresponding formulas RO(C ₂ H ₄ O) _x SO ₃ M, where R is alkyl or alkenyl containing from about 6 to about 20 carbon atoms, x = 1 to 10 and M is a water soluble cation such as ammonium, sodium, potassium and triethanolamine. Preferably, R contains from about 6 to about 18, preferably from about 8 to about 16, more preferably from about 10 to about 14 carbon atoms. AES surfactants are typically prepared as condensation products of ethylene oxide and monohydric alcohols containing from about 6 to about 20 carbon atoms. Suitable alcohols can be obtained from fats, such as coconut oil or tallow, or they can be synthetic. In the present invention, lauryl alcohol and straight chain alcohols derived from coconut oil are preferred. Such alcohols are reacted with ethylene oxide in molar proportions from about 1 to about 10, preferably from about 3 to about 5, and especially about 3, and the resulting mixture of chemical compounds, containing, for example, an average of 3 moles of ethylene oxide per mole of alcohol, is sulfated and neutralize. The most preferred AES are those containing a mixture of individual compounds, said mixture having an average alkyl chain length of from about 10 to about 16 carbon atoms and an average degree of ethoxylation from about 1 to about 4 moles of ethylene oxide. If present, the amount of AAS in the solid sheet of the present invention may range from about 2% to about 40%, preferably from about 5% to about 30%, more preferably from about 8% to about 12% of the total weight of the solid sheet.

Other suitable anionic surfactants include water-soluble salts of organic reaction products with sulfuric acid with the general formula [R ¹ -SO ₃ -M], where R ¹ is selected from the group consisting of straight or branched saturated aliphatic hydrocarbon radicals containing from about 6 up to about 20, preferably from about 10 to about 18 carbon atoms; and M is a cation. C _10-18 n-paraffins with alkali metal and ammonium are preferred. Other suitable anionic surfactants include olefin sulfonates containing 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.

Another class of anionic surfactants suitable for use in household and tissue care formulations are the β-alkyloxyalkane sulfonates. These compounds have the following formula:

,

,

where R ₁ is a linear alkyl group containing from about 6 to about 20 carbon atoms, R ₂ is a lower alkyl group containing from about 1 (preferably) to about 3 carbon atoms, and M is a water-soluble cation according to described above in this document.

Further examples of suitable anionic surfactants are the reaction products of fatty acids esterified with isethionic acid and neutralized with sodium hydroxide, where, for example, the fatty acids are derived from coconut oil; sodium or potassium salts of methyltauride fatty acid amides, in which the fatty acids are, for example, derived from coconut oil. Other suitable anionic surfactants are succinamates, examples of which include disodium N-octadecylsulfosuccinamate; diammonium lauryl sulfosuccinamate; tetrasodium N-(1,2-dicarboxyethyl)-N-octadecylsulfosuccinamate; sodium salt of diamyl ester of sulfosuccinic acid; sodium salt of dihexyl ester of sulfosuccinic acid; and sodium salt of dioctyl ester of sulfosuccinic acid.

Non-ionic surfactants that may be included in the solid sheet of the present invention may be any conventional non-ionic surfactants, including, without limitation: alkyl alkoxylated alcohols, alkyl alkoxylated phenols, alkyl polysaccharides (especially alkyl glucosides and alkyl polyglucosides), fatty amides polyhydroxy acids, alkoxylated fatty acid esters, sucrose esters, sorbitan esters and alkoxylated sorbitan ester derivatives, amine oxides, and the like. Preferred non-ionic surfactants are compounds of the formula R ¹ (OC ₂ H ₄ ) _n OH, where R ¹ is a C ₈ -C ₁₈ alkyl group or an alkylphenyl group and n is from about 1 to about 80. Particularly preferred are C ₈ - C ₁₈ alkyl ethoxylated alcohols having a weight average degree of ethoxylation of about 1 to about 20, preferably about 5 to about 15, more preferably about 7 to about 10, such as NEODOL® nonionic surfactants commercially available from Shell. Other non-limiting examples of non-ionic surfactants used include: C ₆ -C ₁₂ alkylphenol alkoxylates, in which the alkoxylate units may be ethyleneoxy units, propyleneoxy units, or mixtures thereof; C ₁₂ -C ₁₈ alcohol and condensation products of C ₆ -C ₁₂ alkylphenol with ethylene oxide/propylene oxide block polymers such as Pluronic® from BASF; C ₁₄ -C ₂₂ medium chain branched alcohols; C ₁₄ -C ₂₂ branched medium chain alkyl alkoxylates, BAE _x , where x is from 1 to 30; alkyl polysaccharides, in particular alkyl polyglycosides; polyhydroxy fatty acid amides; and surfactants based on polyoxyalkylated alcohol with ether end groups. Suitable non-ionic surfactants also include those sold under the brand name Lutensol® from BASF.

In a preferred embodiment, the non-ionic surfactant is selected from sorbitan esters and alkoxylated sorbitan ester derivatives, including sorbitan monolaurate (SPAN® 20), sorbitan monopalmitate (SPAN® 40), sorbitan monostearate (SPAN® 60), sorbitan tristearate (SPAN® 65), sorbitan monooleate (SPAN® 80), sorbitan trioleate (SPAN® 85), sorbitan anisostearate, polyoxyethylene (20) sorbitan monolaurate (Tween® 20), polyoxyethylene (20) sorbitan monopalmitate (Tween® 40), polyoxyethylene (20) sorbitan monostearate (Tween® 60), polyoxyethylene (20) sorbitan monooleate (Tween® 80), polyoxyethylene (4) sorbitan monolaurate (Tween® 21), polyoxyethylene (4) sorbitan monostearate (Tween® 61), polyoxyethylene (5) sorbitan monooleate (Tween® 81), all manufactured by Uniqema, and their combinations.

The most preferred non-ionic surfactants for the practice of the present invention include C ₆ -C ₂₀ linear or branched alkyl alkoxylated alcohols having a weight average alkoxylation degree in the range of 5 to 15, more preferably C ₁₂ -C ₁₄ linear ethoxylated alcohols having a weight average alkoxylation degree in the range of 7 to 9. If present, the amount of non-ionic surfactant(s) such as alkyl alkoxylated alcohols in the solid sheet of the present invention may range from about 2% to about 40%, preferably from about 5% to about 30%, more preferably from about 8% to about 12% of the total weight of the solid sheet.

Amphoteric surfactants suitable for use in the solid sheet of the present invention include compounds that are broadly described as derivatives of aliphatic secondary and tertiary amines, in which the aliphatic radical may be straight or branched, and wherein one of the aliphatic substituents contains from about 8 to about 18 carbon atoms, and one contains an anionic group that promotes dissolution in water, such as carboxyl, sulfonate, sulfate, phosphate or phosphonate. Examples of compounds meeting this definition are sodium 3-dodecyl aminopropionate, sodium 3-dodecylaminopropanesulfonate, sodium lauryl sarcosinate, N-alkyltaurines, for example the compound obtained from the reaction of dodecylamine with sodium isethionate and higher N-alkylaspartic acids.

One category of amphoteric surfactants particularly suitable for incorporation into solid sheets for personal care applications (eg, shampoo, cleanser or body wash, and the like) includes alkylamphoacetates such as lauroamphoacetate and cocoamphoacetate. Alkylamphoacetates may consist of monoacetates and diacetates. In some types of alkylamphoacetates, diacetates are impurities or unintended reaction products. When present, the amount of alkylamphoacetate(s) in the solid sheet of the present invention may range from about 2% to about 40%, preferably from about 5% to about 30%, more preferably from about 10% to about 20% of the total weight. hard sheet.

Suitable zwitterionic surfactants include compounds that are broadly described as derivatives of aliphatic quaternary ammonium, phosphonium, and sulfonium compounds in which the aliphatic radicals may be straight or branched, and where one of the aliphatic substituents contains from about 8 to about 18 carbon atoms, and one contains an anionic group, such as a carboxyl, sulfonate, sulfate, phosphate or phosphonate group. Such suitable zwitterionic surfactants can be represented by the formula:

,

,

where R ² is an alkyl, alkenyl or hydroxyalkyl radical with from about 8 to about 18 carbon atoms, from 0 to about 10 ethylene oxide functional groups and from 0 to about 1 glyceryl functional group; Y is selected from the group consisting of nitrogen, phosphorus and sulfur atoms; R ³ is an alkyl or monohydroxyalkyl group containing from about 1 to about 3 carbon atoms; X = 1 if Y is a sulfur atom and 2 if Y is a nitrogen or phosphorus atom; R ⁴ is an alkylene or hydroxyalkylene of about 1 to about 4 carbon atoms, and Z is a radical selected from the group consisting of carboxylate, sulfonate, sulfate, phosphonate, and phosphate groups.

Другие цвиттерионные ПАВ, подходящие для использования в настоящем изобретении, включают бетаины, включая высшие алкилбетаины, такие как кокодиметилкарбоксиметилбетаин, кокоамидопропилбетаин, кокобетаин, лауриламидопропилбетаин, олеилбетаин, лаурилдиметилкарбоксиметилбетаин, лаурилдиметилальфакарбоксиэтилбетаин, цетилдиметилкарбоксиметилбетаин, лаурил-бис-(2-гидроксиэтил)карбоксиметилбетаин, стеарил-бис -(2-hydroxypropyl)carboxymethylbetaine, oleyldimethyl-gamma-carboxypropylbetaine and lauryl-bis-(2-hydroxypropyl)alpha-carboxyethylbetaine. Sulfobetaines may be cocodimethylsulfopropyl betaine, stearyl dimethyl sulfopropyl betaine, lauryl dimethyl sulfoethyl betaine, lauryl bis-(2-hydroxyethyl) sulfopropyl betaine, and the like; in the present invention it is also possible to use amidobetaines and amidosulfobetaines, in which the radical RCONH(CH ₂ ) ₃ where R is C ₁₁ -C ₁₇ alkyl attached to the nitrogen atom of betaine.

Cationic surfactants can also be used in the present invention, especially in products such as fabric softeners and hair conditioners. When used to make products containing cationic surfactants as base surfactants, such cationic surfactants are preferably 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% up to about 15% of the total weight of the solid sheet.

Cationic surfactants may include diamide quaternary ammonium (DEQA) compounds, which encompasses the description of diamide actives as well as actives with mixed amide and ester linkages. Preferred DEQA compounds are typically prepared by reacting alkanolamines such as methyldiethanolamine (MDEA) and triethanolamine (TEA) with fatty acids. Some materials commonly formed from such reactions include N,N-di(acyloxyethyl)-N,N-dimethylammonium chloride or N,N-di(acyloxyethyl)-N,N-methylhydroxyethylammonium methylsulfate, in which the acyl group is derived from animal fats, unsaturated and polyunsaturated fatty acids.

Other suitable active substances for use as a cationic surfactant include the reaction products of fatty acids with dialkylenetriamines, for example with a molecular ratio of about 2:1, and these reaction products contain compounds with the formula:

R ¹ -C (O) -NH-R ² -NH-R ³ -NH-C (O) -R ¹ ,

where R ¹ , R ² are defined as above, and each R ³ is a C _1-6 alkylene group, preferably an ethylene group. Examples of these active substances are the reaction products of tallow acid, canola oil acid or oleic acids with diethylenetriamine in a molecular ratio of about 2:1, said mixture of reaction products containing N,N"-dithalloildiethylenetriamine, N,N"-dicanolaoildiethylenetriamine or N,N "-dioleoildiethylenetriamine, respectively, with the formula:

R ¹ -C (O) -NH-CH ₂ CH ₂ -NH-CH ₂ CH ₂ -NH-C (O) -R ¹ ,

where R ² and R ³ are divalent ethylene groups, R ¹ is as defined above, and acceptable examples of this structure when R ¹ is the oleoyl group of commercially available oleic acid derived from plant or animal sources include EMERSOL® 223LL or EMERSOL® 7021 supplied by Henkel Corporation.

Another active substance for use as a cationic surfactant has the formula:

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

where R, R ¹ , R ² , R ³ and X ^are defined as above. Examples of such an active substance are a fatty diamidoamine emollient having the formula:

[R ¹ -C (O) -NH-CH ₂ CH ₂ -N (CH ₃ ) (CH ₂ CH ₂ OH) -CH ₂ CH ₂ -NH-C (O) -R ¹ ] ⁺ CH ₃ SO ₄ ^- ,

where R ¹ -C(O) is an oleoil group, a fusible tallow group or a hardened tallow group, available commercially from Degussa under the trademarks VARISOFT® 222LT, VARISOFT ® 222 and VARISOFT ® 110, respectively.

A second type of DEQA compound (DEQA(2)) suitable as an active agent for use as a cationic surfactant has the general formula:

[R ₃ N ⁺ CH ₂ CH(YR ¹ )(CH ₂ YR ¹ )] X ^- ,

where Y, R, R ¹ , and X ^- in each case have the same meanings as above. An example of a preferred DEQA compound (2) is a quaternary ammonium "propyl" ether used as an active agent as a fabric softener, which has the formula 1,2-di(acyloxy)-3-trimethylammoniopropane chloride.

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, silicone polyesters, silicone copolyol esters, diquaternary polydimethylsiloxanes and co-modified amino/polyether silicones.

3. Plasticizers

In a preferred embodiment of the present invention, the flexible porous soluble solid sheet of the present invention further comprises a plasticizer, preferably in an amount ranging from about 0.1% to about 25%, preferably from about 0.5% to about 20%, more preferably from about 1 % to about 15%, most preferably 2% to 12% of the total weight of said solid sheet. Accordingly, the wet premix used to form such a solid sheet may contain from about 0.02% to about 20% by weight of said wet premix, in one embodiment from about 0.1% to about 10% by weight of said wet premix. premix, in one embodiment, from about 0.5% to about 5% by weight of the wet premix.

Suitable plasticizers for use in the present invention include, for example, polyols, copolyols, polycarboxylic acids, polyesters, dimethicone copolyols, and the like.

Examples of useful polyols include, without limitation: glycerol, diglycerol, ethylene glycol, polyethylene glycol (especially 200-600), propylene glycol, butylene glycol, pentylene glycol, glycerol derivatives (such as propoxylated glycerol), glycidol, cyclohexanedimethanol, hexanediol, 2,2,4 -trimethylpentan-1,3-diol, pentaerythritol, urea, sugar alcohols (such as sorbitol, mannitol, lactitol, xylitol, maltitol and other mono- and polyhydric alcohols), mono-, di- and oligosaccharides (for example, fructose, glucose, sucrose, maltose, lactose, high fructose corn syrup solids and dextrins), ascorbic acid, sorbates, ethylenebisformamide, amino acids, and the like.

Examples of polycarboxylic acids include, without limitation, citric acid, maleic acid, succinic acid, polyacrylic acid, and polymaleic acid.

Examples of suitable polyesters include, without limitation, glycerol triacetate, acetylated monoglyceride, diethyl phthalate, triethyl citrate, tributyl citrate, acetyl triethyl citrate, acetyl tributyl citrate.

Examples of suitable dimethicone copolyols include, without limitation, PEG-12 dimethicone, PEG/PPG-18/18 dimethicone, and PPG-12 dimethicone.

Other suitable plasticizers include, without limitation, alkyl and allyl phthalates; naphthalates; lactates (eg sodium, ammonium and potassium salts); sorbet-30; urea; lactic acid; sodium salt of pyrrolidonecarboxylic acid (pyrrolidone carboxylic acid - PCA); sodium hyaluronate or hyaluronic acid; soluble collagen; modified protein; L-monosodium glutamate; alpha and beta hydroxy acids such as glycolic acid, lactic acid, citric acid, maleic acid and salicylic acid; glyceryl polymethacrylate; polymeric plasticizers such as polyquaterniums; proteins and amino acids such as glutamic acid, aspartic acid and lysine; hydrogenated starch hydrolysates; other low molecular weight esters (eg esters of C ₂ -C ₁₀ alcohols and acids); and any other water-soluble plasticizer known to those skilled in the food and plastics industry; and their mixtures.

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

4. Additional ingredients

In addition to the ingredients described above, for example the water soluble polymer, surfactant(s) and plasticizer(s), the solid sheet of the present invention may contain one or more additional ingredients depending on its intended use. Such one or more additional ingredients may be selected from the group consisting of fabric care actives, dishwashing actives, hard surface cleaning actives, cosmetic and/or skin care actives, personal care actives. hygiene, hair care actives, oral care actives, feminine care actives, baby care actives, and any combination thereof.

Suitable fabric care actives include, without limitation: organic solvents (branched or branched C ₁ -C ₈ lower alcohols, diols, glycerols or glycols; lower amine solvents such as C ₁ -C ₄ alkanolamines and mixtures thereof; more specifically , 1,2-propanediol, ethanol, glycerol, monoethanolamine and triethanolamine), carriers, hydrotropes, bulking agents, chelating agents, dispersing agents, enzymes and enzyme stabilizers, catalytic materials, bleaches (including photobleachers) and bleach activators, fragrances (including encapsulated aromatics or microcapsules with aromatics), colorants (such as pigments and dyes, including color pigments), brighteners, dye transfer inhibitors, clay soil removers/anti-re-deposits, texturizers, rheology modifiers, foam suppressors, technological additives, softeners tissues, antimicrobial agents, and the like.

Suitable hair care actives include, but are not limited to: class II moisture control materials for smoothing hair (salicylic acids and derivatives, organic alcohols and esters), cationic surfactants (particularly insoluble in water, having solubility in water at 25°C preferably less than 0.5 g/100 g water, more preferably less than 0.3 g/100 g water), high melting point fatty compounds (e.g. fatty alcohols, fatty acids and mixtures thereof with a melting point of 25°C or higher , preferably 40°C or higher, more preferably 45°C or higher, even more preferably 50°C or higher), silicone compounds, conditioning agents (such as hydrolyzed collagen with the trade name Peptein 2000 available from Hormel, vitamin E with the trade name Emix-d supplied by Eisai, panthenol supplied by Roche, panthenyl ethyl ether supplied by Roche, hydrolysed keratin, proteins, vegetable extracts and nutrients), preservatives (such as benzyl alcohol, methylparaben, propylparaben, and imidazolidinyl urea), pH adjusters (such as citric acid, sodium citrate, succinic acid, phosphoric acid, sodium hydroxide, sodium carbonate), salts (such such as potassium acetate and sodium chloride), coloring agents, fragrances or perfumes, complexing agents (such as disodium ethylenediaminetetraacetate), ultraviolet and infrared protection agents (such as octyl salicylate), hair bleaching agents, hair curling agents, hair fixatives, anti-dandruff agents, antimicrobial agents, hair growth or regrowth agents, co-solvents or other co-solvents, and the like.

Suitable active ingredients for cosmetics and/or skin care include materials approved for use in cosmetics and described in reference books such as the CTFA Cosmetic Ingredient Handbook, Second Edition, The Cosmetic, Toiletries, and Fragrance Association, Inc. 1988, 1992. Additional non-limiting examples of acceptable active ingredients for cosmetics and/or skin care include preservatives, fragrances or perfumes, colorants or dyes, thickeners, humectants, emollients, pharmaceutical actives, vitamins or nutrients. , sunscreens, deodorants, sensing agents, herbal extracts, nutrients, astringents, cosmetic particles, absorbent particles, fibers, anti-inflammatory agents, skin lightening agents, skin color improver (which serves to improve overall skin color and may contain vitamin B3 compounds, sugar amines, hexamidine compounds, salicylic acid, 1,3-dihydroxy-4-alkylbenzene such as hexylresorcinol and retinoids), tanning agent, exfoliating agents, moisture retaining agents, enzymes, antioxidants, free radical scavengers, active Components anti-wrinkle agents, anti-acne agents, acids, bases, minerals, suspending agents, pH modifiers, pigment particles, antimicrobials, insect repellents, shaving lotions, co-solvents or other co-solvents, and the like.

The solid sheet of the present invention may additionally contain other optional ingredients that are known in the art or otherwise suitable for use in the compositions, provided that such optional materials are compatible with the selected essential materials described herein or do not otherwise degrade the quality of the product. .

Non-limiting examples of embodiments of the type of product that can be formed from the solid sheet of the present invention include laundry detergents, fabric softening products, hand cleaning products, hair shampoos or other hair care products, cleaning products. body products, shaving products, dishwashing products, personal care substrates containing pharmaceutical or other active ingredients for skin care, moisturizing products, sun protection products, cosmetic or skin care products, deodorant products, cavity care products mouth care products, feminine hygiene products, baby care products, perfumed products, etc.

VI. Assembling a plurality of sheets into multilayer soluble solid articles

After forming the flexible soluble porous solid sheets as described herein above, two or more such sheets can be further assembled into multilayer soluble solid articles of the present invention with the desired aspect ratio (ie D/z ratio).

The multilayer soluble solid articles of the present invention may have any desired three-dimensional shape, including, but not limited to, spherical, cubic, rectangular, polygonal, elongated, cylindrical, rod, leaf, flower, fan, star, disk, and the like. Sheets can be combined and/or processed by any means known in the art, examples of which include, without limitation, chemical means, mechanical means, and combinations thereof. Such combination and/or processing steps are collectively referred to herein as a "transformation" process, i.e. a process that serves to convert two or more flexible soluble porous sheets of the present invention into a soluble solid product of the desired three-dimensional shape.

As noted above herein, it has been surprisingly and unexpectedly found within the scope of the present invention that the multi-layer soluble solid articles of the present invention, formed by stacking a plurality of the above-described flexible soluble porous sheets, are more soluble than single-layer solid articles with the same aspect relationship. This allows such solid products to be significantly expanded in the thickness or z direction to create three-dimensional product shapes that are easier to handle and more aesthetically pleasing to consumers (eg products in the form of thick mats or even cubes).

More specifically, the multilayer soluble solid articles of the present invention have an aspect ratio 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.

The multilayer soluble solid article of the present invention may have a minimum dimension z that is 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.

The multilayer soluble solid article described above may comprise more than two such flexible soluble porous sheets. For example, it may contain from about 4 to about 50, preferably from about 5 to about 40, more preferably from about 6 to about 30 of these flexible soluble porous sheets. The improved OCF structures in flexible dissolvable porous sheets made in accordance with the present invention allow many sheets (eg 15-40) to be stacked on top of each other while still providing a satisfactory overall dissolution rate for the entire stack.

In a particularly preferred embodiment of the present invention, the multilayer soluble solid article comprises 15 to 40 layers of the flexible soluble porous sheets described above and has an aspect ratio in the range of about 2 to about 7.

The multilayer soluble solid product of the present invention may comprise individual sheets of various colors that are visually visible from the outer surface (eg, one or more side surfaces) of such product. Such visible sheets of various colors are aesthetically pleasing to consumers. In addition, the different colors of the individual sheets may provide visual cues indicating the various beneficial agents contained in the individual sheets. For example, the multilayer soluble solid product may comprise a first sheet having a first color and containing a first benefit agent and a second sheet having a second color and containing a second benefit agent, the first color providing a visual cue of the first benefit agent and the second color providing a visual cue. clue about the second beneficial agent.

The multilayer soluble solid product of the present invention also offers the advantage of ease of use and handling. A single sheet can be soft and difficult to use. In comparison, multilayer structures can be easier to capture and manipulate.

The three-dimensional structure (multi-layer) also has visual appeal compared to the two-dimensional structure (single sheet).

In the present invention, it is particularly desirable to include incompatible beneficial ingredients in different sheets so that such incompatible beneficial ingredients are separated and isolated from each other. For example, it is possible to separate and isolate aldehyde/ketone containing ingredients (such as aromatics) from nucleophilic amine containing ingredients (such as amino silicones and pyroctonolamine) to avoid unwanted interactions between them. In a specific embodiment of the present invention, the multi-layer soluble solid product may comprise a first sheet containing aromatics and a second sheet containing an antimicrobial agent, such as pyroctonolamine, such first and second sheets preferably having different colors so that they can be easily visually distinguished from each other. from friend. Another advantage of coloring is the potential masking of possible discolouration during the shelf life of the product. More preferably, such a multi-layer soluble solid product contains between the first and second layers at least one additional sheet, and said at least one additional sheet does not contain any aromatics or pyroctonolamine. Most preferably, such first and second sheets are placed as outer sheets on opposite sides of the multilayer soluble solid article.

In addition, one or more functional ingredients can be placed between individual sheets of a multi-layer soluble solid article (sandwich type), as described above in this document, for example, by spraying, spraying, spraying, coating, spreading, dipping, injecting, or even depositing from the vapor phase. To avoid overlapping of such functional ingredients at a split seam or edge seam at the periphery of individual sheets, it is preferable to place such functional ingredients in the central region between two adjacent sheets, which is defined as the region that is separated from the periphery of such adjacent sheets by a distance of at least 10%. from the maximum size D. Suitable functional ingredients may be selected from the group consisting of cleaning actives (surfactants, free fragrances, encapsulated fragrances, fragrance microcapsules, silicones, emollients, enzymes, bleaches, dyes, fillers, rheology modifiers, pH modifiers, and combinations thereof) and personal care active ingredients (eg, emollients, humectants, conditioning agents, and combinations thereof).

TEST METHODS

Test 1. Scanning electron microscopy (SEM) method for determining the average pore diameter of a sheet product.

A Hitachi TM3000 tabletop microscope (s/n: 123104-04) is used to take SEM micrographs of samples. Samples of the solid sheet products of the present invention are approximately 1 cm x 1 cm and are cut from larger sheets. Images are obtained at 50x magnification, the device is operated at 15 kV. At least 5 photomicrographs are obtained from randomly selected locations on each sample, resulting in a total area analyzed of approximately 43.0 mm ² , from which the average pore diameter is estimated.

The SEM micrographs are then first processed using the Image Analysis Toolkit in Matlab. If necessary, images are converted to grayscale. For a given image, a histogram of intensity values for each individual pixel is generated using the Matlab 'imhist' function. Typically, two separate distributions are apparent from such a histogram, corresponding to the pixels of the brighter leaf surface and the pixels of the darker areas within the pores. A threshold value is selected corresponding to the intensity value between the peak value of these two distributions. Then, all pixels having an intensity value below this threshold value are assigned an intensity value of 0, and pixels having a higher intensity value are assigned a value of 1, and thus a binary black and white image is obtained. The binary image is then analyzed using the ImageJ program (https://imagej.nih.gov, version 1.52a) to study both the pore area fraction and the pore size distribution. The scale mark of each image is used to determine the pixel/mm scaling factor. For analysis purposes, automatic thresholding and particle analysis functions are used to isolate each pore. The output of the analysis function includes the area fraction for the overall image, as well as the pore area and pore perimeter for each individual pore detected.

The average pore diameter is defined as D _A 50: 50% of the total pore area consists of pores having the same or smaller hydraulic diameters than the average diameter D _A 50.

Hydraulic diameter = '4 * Pore area (m ² ) / Pore perimeter (m)'.

It represents the equivalent diameter calculated taking into account that not all pores are round.

Test 2: Computed microtomography (µCT) method for determining total or regional average pore size and average cell wall thickness for Open Cell Foams (OCF)

Porosity is the ratio of the volume of void space to the total volume of space occupied by the OCF. Porosity can be calculated from µCT scans by segmenting the void space by defining thresholds and determining the ratio of the number of void voxels to the total number of voxels. Similarly, solid volume fraction (SVF) is the ratio between the volume of space occupied by solid matter and the total volume of space, and the SVF value can be calculated as the ratio of the number of occupied voxels to the total number of voxels. Both porosity and SVF are average scalars that do not provide structural information such as the pore size distribution in the height direction of the OCF or the average cell wall thickness of the OCF struts.

Швейцария), работающий со следующими настройками: уровень энергии 45 кВп при 133 мкА; 3000 проекций; поле зрения 15 мм; время интегрирования 750 мс; усреднение 5; и размер вокселя 3 мкм на пиксель. После завершения сканирования и последующей реконструкции данных сканер создает набор 16-битных данных, называемый «файлом ISQ», в котором уровни серого отражают изменения в затухании рентгеновского излучения, что, в свою очередь, относится к плотности материала. Затем файл ISQ преобразуют в 8 бит с использованием коэффициента масштабирования.To characterize the 3D structure of the OCF, samples are imaged with an X-ray microCT scanner capable of obtaining a high isotropic spatial resolution dataset. One example of a suitable instrument is the SCANCO Model 50 MicroCT Scanner (Scanco Medical AG,

Switzerland) operating with the following settings: energy level 45 kVp at 133 µA; 3000 projections; field of view 15 mm; integration time 750 ms; averaging 5; and a voxel size of 3 µm per pixel. Once the scan is complete and the data is then reconstructed, the scanner creates a 16-bit data set called an "ISQ file" in which the gray levels reflect changes in X-ray attenuation, which in turn relates to material density. The ISQ file is then converted to 8 bits using a scaling factor.

Scanned OCF samples are typically prepared by punching through a core approximately 14 mm in diameter. The embossed OCF sample is laid horizontally on low attenuation foam, then mounted in a 15 mm diameter plastic cylindrical tube for scanning. Sample scans are obtained such that the data set includes the entire volume of the entire installed cut sample. From this larger dataset, a smaller sub-sample dataset is extracted from the total scanned open cell foam (OCF) cross section to create a 3D data layer where pore quality can be assessed without edge/boundary effects.

To characterize the pore size distribution in the height direction and the size of the struts, a Local Thickness Map (LTM) algorithm is run on the sub-volume data set. The LTM method starts with Euclidean Distance Mapping (EDM), which assigns gray level values equal to the distance each empty voxel is from the nearest boundary. Based on the EDM data, a 3D empty space representing pores (or a 3D solid space representing struts) is tessellated with spheres whose dimensions correspond to the EDM values. Voxels covered by spheres are assigned the value of the radius of the largest sphere. In other words, each empty voxel (or solid voxel for struts) is assigned the radial value of the largest sphere that fits into the empty pore space boundary (or solid voxel for struts) and includes the assigned voxel.

The output of a 3D labeled sphere distribution from a scan of the LTM data can be viewed as a stack of two 2D images in the height (or Z) direction and used to estimate the change in the sphere diameter from slice to slice as a function of OCF depth. The strut thickness is considered as a 3D data set and the average value can be estimated for the whole subvolume or its parts. Calculations and measurements were performed using AVIZO Lite (9.2.0) software from Thermo Fisher Scientific and MATLAB (R2017a) from Mathworks.

Test 3. Percentage of open cells in a sheet product

The percentage of open cells is measured using gas pycnometry. Gas pycnometry is a common analytical technique that uses the gas displacement method to accurately measure volume. Inert gases such as helium or nitrogen are used as a displacing medium. A sample of the solid sheet product of the present invention is hermetically sealed in an apparatus compartment of known volume, an appropriate inert gas is supplied, and then expanded to another precision internal volume. The pressure before and after expansion is measured and used to calculate the volume of the product sample.

The ASTM D2856 Standard Test Method describes a procedure for determining open cell percentage using an older model air reference pycnometer. This device is no longer manufactured. However, you can conveniently and accurately determine the percentage of open cells by testing using the Micromeritics AccuPyc Pycnometer. The ASTM D2856 procedure describes 5 methods (A, B, C, D, and E) for determining the percentage of open cells in foams. For these experiments, samples can be analyzed with an Accupyc 1340 pycnometer using nitrogen gas and ASTM Foampyc software. Method C of the ASTM procedure should be used to calculate the percentage of open cells. This method simply compares the geometric volume determined with a thickness gauge and standard volume calculations with the open cell volume measured with an Accupyc pycnometer according to the following equation:

Open Cell Percentage = Sample Open Cell Volume / Geometric Sample Volume * 100

It is recommended that these measurements be performed by Micromeritics Analytical Services, Inc. (One Micromeritics Dr, Suite 200, Norcross, GA 30093). More information about this technique is available on the Micromeritics Analytical Services websites (www.particletesting.com or www.micromeritics.com) and published in the book Analytical Methods in Fine Particle Technology by Clyde Orr and Paul Webb.

Test 4 Final Moisture Content of Sheet Product

The final moisture content of the solid sheet product of the present invention is obtained using a Mettler Toledo HX204 moisture analyzer (s/n B706673091). At least 1 g of the dried sheet product is placed on the measuring tray. Then a standard program is performed with additional program settings: analysis time 10 minutes, temperature 110°C.

Test 5. Sheet thickness

The thickness of the flexible porous soluble solid sheet product of the present invention is obtained using a micrometer or thickness gauge, such as a Mitutoyo Corporation Digital Disk Stand Micrometer Model No IDS-1012 E (Mitutoyo Corporation, 965 Corporate Blvd, Aurora, IL, USA 60504). The micrometer has a 1 inch diameter plate weighing about 32 grams that measures thickness at a down pressure of about 0.09 psi. inch (6.32 g/cm ² ).

The thickness of a flexible porous soluble solid sheet product is measured by lifting the plate, placing a portion of the sheet product on a stand under the plate, gently lowering the plate until it contacts the sheet product, releasing the plate, and measuring the thickness of the sheet product in millimeters from a digital readout. The sheet product must be fully extended to all edges of the plate to allow for thickness measurement at the lowest possible surface pressure, except in the case of stiffer substrates that are not flat.

Test 6. The main mass of the sheet product

The basis weight of the flexible porous soluble solid sheet product of the present invention is calculated as the weight of the sheet product per area (grams/m ² ). The area is calculated as the area projected onto a flat surface perpendicular to the outer edges of the sheet product. The solid sheet products of the present invention are cut into 10 cm×10 cm square specimens, so the area is known. Each of these square samples is then weighed and then the resulting mass is divided by a known area of 100 cm ² to determine the corresponding basis mass.

For an irregularly shaped product, if it is a flat object, the area is calculated from the area contained within the outer perimeter of such an object. For a spherical object, the area is calculated from the average diameter as 3.14×(diameter/2) ² . For a cylindrical object, the area is calculated from the mean diameter and the mean length as diameter x length. For a three-dimensional irregularly shaped object, the area is calculated from the side with the largest external dimensions, projected onto a flat surface oriented perpendicular to this side. This can be done by carefully marking the outer dimensions of the object on scaled paper with a pencil and then calculating the area by roughly counting the squares and multiplying by the known area of the squares, or by photographing the plotted area (shaded for contrast), including a scale, and applying image analysis techniques.

Test 7. Density of a sheet product

The density of the flexible porous soluble solid sheet product of the present is determined by the equation: Estimated density = basis weight of the porous solid product / (thickness of the porous solid product × 1000). The basis weight and thickness of the soluble porous solid product is determined in accordance with the methods described above in this document.

Test 8. Specific surface area of a sheet product

The specific surface area of the flexible porous soluble solid sheet product is measured by the gas adsorption method. Surface area is a measure of the exposed surface of a solid sample on a molecular scale. The BET theory (Brunauer, Emmet and Teller) is the most popular model used to determine surface area and is based on gas adsorption isotherms. The gas adsorption method uses physical adsorption and capillary condensation to measure the gas adsorption isotherm. The methodology can be briefly described as the following steps; the sample is placed in a sample tube and heated under vacuum or in a gas stream to remove contaminants from the surface of the sample. The mass of the sample is obtained by subtracting the mass of the empty sample tube from the total mass of the degassed sample and the sample tube. Then the tube with the sample is placed in the hole for analysis and start the analysis. The first step in the analysis process is to evacuate the tube and then measure the headspace in the tube using helium gas at liquid nitrogen temperature. Then, vacuuming is carried out a second time to remove gaseous helium. The instrument then begins to determine the adsorption isotherm by adding gaseous krypton at user-defined intervals until the desired pressure measurement is achieved. The samples can then be analyzed using the ASAP 2420 system with krypton gas adsorption. It is recommended that these measurements be performed by Micromeritics Analytical Services, Inc. (One Micromeritics Dr, Suite 200, Norcross, GA 30093). More information about this technique is available on the Micromeritics Analytical Services websites (www.particletesting.com or www.micromeritics.com) and published in the book Analytical Methods in Fine Particle Technology by Clyde Orr and Paul Webb.

Test 9. Dissolution rate

The dissolution rate of soluble sheets or solid articles of the present invention is measured as follows:

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

2. A magnetic stirrer element 23 mm long and 10 mm thick is placed in water and the rotation speed is set to 300 rpm.

3. The Mettler Toledo S230 Conductivity Meter is calibrated to 1413 µS/cm and the sensor is placed in a beaker of water.

4. For each experiment, the number of samples is chosen so that at least 0.2 g of the sample is dissolved in water.

5. Run the data logging function on the conductivity meter and lower the samples into the beaker. A flat steel plate with a diameter close to that of a glass beaker is used to submerge the samples below the surface of the water and prevent them from floating to the surface for 5 minutes.

6. Conductivity is recorded for at least 10 minutes until a steady state value is reached.

7. To calculate the time required to reach 95% dissolution, first a 10 second running average is calculated from the conductivity data. The time taken for the moving average to exceed 95% of the final steady state conductivity value is then estimated and taken as the time required to reach 95% dissolution.

EXAMPLES

Example 1 Different OCF Structures in Hard Sheets Produced with Different Heating/Drying Schemes

Wet premixes were prepared with the following surfactant/polymer compositions for the laundry care and hair care products described in Table 1 and Table 2 below, respectively.

The viscosity of the wet premix composition shown in Table 1 is about 14309.8 cps. After aeration, the average density of such an aerated wet premix is about 0.25 g/cm ³ .

The viscosity of the wet premix composition shown in Table 2 is about 19254.6 centipoise. After aeration, the average density of such an aerated wet premix is about 0.225 g/cm ³ .

The flexible porous soluble solid sheets A and B according to the present invention are prepared from the above wet premixes described in Tables 1 and 2 using a continuous aerator (Aeros) and a rotary dryer with the following settings and conditions given in Table 3 below. .

The flexible porous soluble solid sheet C according to the present invention is also made from the above wet premix described in Table 2 using a continuous aerator (Oakes) and a mold placed on a hot plate (which provides conductive heating from below) with the following settings and conditions given in Table 4 below.

In addition, comparative flexible porous soluble hard sheets I and II were prepared from the above wet premixes described in Tables 1 and 2 using a continuous aerator (Oakes) and a mold placed in a forced hot air oven with the following settings and the conditions given in Table 5 below.

Tables 6-9 below show various physical parameters and pore structures measured for hard sheets A-C according to the present invention and comparative hard sheets I-II made using the wet premixes and drying methods described above.

The above data shows that the solid sheets of the present invention have predominantly open cells and that the solid sheets of the present invention made in accordance with the methods of the present invention have an average pore diameter on the top surface of more than 100 microns, while the comparative solid sheets do not. In particular, in FIG. 7A shows a scanning electron microscope (SEM) image of the upper surface of sheet A of the present invention, and FIG. 7B shows a SEM image of the top surface of Comparative Solid Sheet I. FIG. 8A shows a SEM image of the top surface of the sheet C of the present invention, and FIG. 8B shows a SEM image of the top surface of comparative solid sheet II.

In addition, the above data show that the solid sheets of the present invention have significantly less variation in average pore size across regions than comparative solid sheets, and especially significantly lower ratios of mean pore size in the lower region to mean pore size in the upper region.

Example 2 Comparative Dissolution Rates of Single Layer and Multilayer Soluble Solids

First, flexible dissolvable porous sheets of the composition described below were made using the process steps described above herein.

More specifically, a wet premix containing the ingredients disclosed above and additional water was first prepared to give a total solids content of about 35% by weight (i.e., the total water content of the slurry is about 65% by weight). The following suspension preparation method was used:

1. First, water and glycerin were added together in a glass beaker and stirred at 200 rpm using an overhead stirrer.

2. With continued stirring, the polyvinyl alcohol was slowly added to the beaker containing water and glycerin, avoiding foaming of the solution or clumping of the polyvinyl alcohol.

3. Then the beaker was placed in a water bath and heated to 80°C with constant stirring. The beaker was covered with cling film or foil to reduce water evaporation and left to continue stirring for at least 1.0 hour more.

4. Weigh the rest of the ingredients and add them all together in a separate glass beaker. The required amount of water was added to the same beaker to obtain a total water content of the suspension of 65%.

5. This beaker was placed in a water bath at 80° C. and its contents were stirred using an overhead stirrer at 500 rpm for at least 30 minutes.

6. After the specified mixing time in both beakers, their contents were combined in one glass beaker, followed by stirring at 500 rpm and maintaining the temperature at 80° C. for at least 30 more minutes.

The wet pre-blend thus obtained has a viscosity of about 19,254.6 cps. Then it was aerated as follows:

1. An Eros A20 continuous aerator, consisting of a jacketed feeder (model JCABT10) and an A20 mixing head, was preheated to 80°C using a water bath and a pump.

2. Then the previously prepared suspension was placed in the feeder. The aerator module was then turned on and the mixing head speed, pump speed, and air flow were set to 600, 500, and 100, respectively.

3. The aerated slurry was collected at the outlet of the downcomer and its density was measured by filling a measuring cup of known volume and weighing the aerated slurry. With the aerator settings described above, an aerated slurry density of about 0.225 g/cm ³ is achieved.

A set of 15 cm x 15 cm aluminum alloy plates was used to dry the aerated wet premix, each having an internal cavity of a given depth (eg, 1, 3, 5, or 10 mm). The thickness of the lower part of each plate in the area of the cavity is at least 5 mm. The aerated slurries were then dried as follows:

1. A 50 cm x 20 cm heating plate was heated to 130°C.

2. An aluminum alloy plate with the desired cavity depth was placed on the heating plate and heated for at least 30 minutes.

3. The aerated slurry was then poured into the cavity of the aluminum alloy plate until the cavity was filled.

4. Then use a 30 cm steel ruler as a scraper on the top surface of the cavity to remove excess slurry and equalize the thickness of the slurry layer and the depth of the cavity.

5. The aerated slurry was then left to dry for at least an hour until it was dry to the touch.

6. Then, the dried sheet was removed from the cavity of the aluminum alloy plate and placed in a plastic bag to reduce the effect of environmental humidity.

In addition to the sheets made using the above-described aluminum alloy plates, flexible and porous hard sheets with a thickness of about 0.8-1.2 mm were also made using a rotary tumble dryer drying process as follows:

1. A rotary dryer (with a drum diameter of about 1.5 m) was heated to about 130°C.

2. The aerated slurry collected at the outlet of the Eros A20 aerator was placed into the feed trough of the dryer drum.

3. After placing the slurry in the feeder, the drying drum was started to rotate at such a speed that the residence time of the slurry on the hot drum was about 15 minutes.

4. After drying, the flexible and porous sheets thus formed were separated from the surface of the drum and placed in a plastic bag.

Below are the respective dimensions and aspect ratios of all single-layer and multi-layer soluble solid products made using sheets obtained in accordance with the above technological steps; their respective dissolution rates were measured using Test 9 as described above herein:

The above data shows that multi-layer soluble solid products of the present invention have a higher dissolution rate than single-layer products with a comparable aspect ratio. Surprisingly and unexpectedly, it was observed that the more layers in such solid products, the higher their rate of dissolution.

The dimensions and values described herein should not be understood as being strictly limited to the exact numerical values listed. On the contrary, unless otherwise indicated, each such dimension shall mean both the indicated value and a functionally equivalent range within which that value falls. For example, a size described as "40 mm" implies "about 40 mm".

Each document referred to in this specification, including any related or cross-referenced patent or application and any patent application or patent claiming priority or advantage in this application, is incorporated herein by reference in its entirety if any of the documents not expressly excluded or otherwise limited. Mention of any document is not an admission that it is prior art with respect to any invention described or claimed herein, or that any such invention is presented, proposed or described in itself or in any combination with any other reference or references. In addition, if any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated herein by reference, the meaning or definition assigned to that term in this document shall prevail.

While specific embodiments of the present invention are shown and described herein, those skilled in the art will appreciate that various other changes and modifications are possible without departing from the spirit and scope of the invention. Thus, the appended claims are intended to cover all such changes and modifications within the scope of the present invention.

Claims (20)

1. Soluble solid product for laundry care and hair care, containing from 6 to 50 flexible soluble porous sheets, each of these sheets contains a water-soluble polymer, which is polyvinyl alcohol, and a surfactant, which is a linear alkylbenzosulfonate, and is characterized by a percentage of open cells from 80% to 100% and a total average pore size from 100 μm to 2000 μm, and while the specified soluble solid product is characterized by a maximum dimension D and a minimum dimension z; and wherein the D/z ratio is in the range from 1 to 10, and wherein each of these sheets is a solid sheet containing an upper region adjacent to the upper surface, a lower region adjacent to the lower surface, and a middle region located between them, and the relative standard deviation between the average pore size in the upper, middle and lower regions is not more than 20%. 2. A soluble solid product according to claim 1 wherein the D/z ratio is in the range of 1.4 to 9, preferably 1.5 to 8, more preferably 2 to 7. 3. A soluble solid product according to claim 1 or 2, wherein the minimum dimension z is in the range of 3 mm to 20 cm, preferably 4 mm to 10 cm, more preferably 5 mm to 30 mm. 4. A soluble solid article according to any one of the preceding claims, wherein each of said sheets has a thickness in the range of 0.5 mm to 4 mm, preferably 0.6 mm to 3.5 mm, more preferably 0.7 mm to 3 mm, even more preferably 0.8 mm to 2 mm, most preferably 1 mm to 1.5 mm. 5. A soluble solid article according to any one of the preceding claims, comprising 4 to 50, preferably 5 to 40, more preferably 6 to 30 of said flexible soluble porous sheets. 6. Soluble solid product according to any one of the preceding claims, which has a density in the range from 0.05 g/cm ³ to 0.5 g/cm ³ , preferably from 0.06 g/cm ³ to 0.4 g/cm ³ , more preferably from 0.07 g/cm ³ to 0.2 g/cm ³ , most preferably from 0.08 g/cm ³ to 0.15 g/cm ³ . 7. A soluble solid article according to any one of the preceding claims, wherein at least one of said flexible soluble porous sheets contains 10% to 40%, preferably 15% to 30%, more preferably 20% to 25% of said polyvinyl alcohol. from the total mass of the specified sheet; and/or wherein said at least one sheet further comprises 5% to 80%, preferably 10% to 70%, more preferably 30% to 65% of said linear alkyl benzene sulfonate, based on the total weight of said sheet. 8. The soluble solid product of claim 7 wherein said at least one sheet further comprises 0.1% to 25%, preferably 0.5% to 20%, more preferably 1% to 15%, most preferably from 2% to 12% of a plasticizer based on the total weight of said sheet; and wherein optionally said at least one sheet further comprises one or more additional ingredients selected from the group consisting of fabric care actives, dishwashing actives, hard surface cleaning actives, cosmetics actives, and /or skin care, personal care actives, hair care actives, oral care actives, feminine care actives, baby care actives, and any combinations thereof. 9. A soluble solid article according to any one of the preceding claims, wherein each of said flexible soluble porous sheets is characterized by: an open cell percentage of 85% to 100%, preferably 90% to 100%; and/or a total average pore size of 150 µm to 1000 µm, preferably 200 µm to 600 µm; and/or an average cell wall thickness of 5 µm to 200 µm, preferably 10 µm to 100 µm, more preferably 10 µm to 80 µm; and/or a final moisture content of 0.5% to 25%, preferably 1% to 20%, more preferably 3% to 10% by weight of said product; and/or a thickness of 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 basis weight from 50 g/m ² to 250 g/m ² , preferably from 80 g/m ² to 220 g/m ² , more preferably from 100 g/m ² to 200 g/m ² ; and/or density from 0.05 g/cm ³ to 0.5 g/cm ³ , preferably from 0.06 g/cm ³ to 0.4 g/cm ³ , more preferably from 0.07 g/cm ³ to 0.2 g/cm ³ , most preferably from 0.08 g/cm ³ to 0.15 g/cm ³ ; and/or specific surface area from 0.03 m ² /g to 0.25 m ² /g, preferably from 0.04 m ² /g to 0.22 m ² /g, more preferably from 0.05 m ² /g to 0 .2 m ² /g, most preferably from 0.1 m ² /g to 0.18 m ² /g. 10. A soluble solid article according to any one of the preceding claims, wherein said flexible soluble porous sheets comprise a first sheet of a first color and a second sheet of a second different color, and wherein said first and second sheets are visible from the outer surface of said soluble solid article. 11. Soluble solid product according to claim 10, in which the specified first sheet contains the first beneficial agent; wherein the second sheet contains a second other beneficial agent; and wherein said first color gives a visual cue about said first benefit agent and said second color gives a visual cue about said second benefit agent. 12. A soluble solid article according to any one of the preceding claims, comprising at least one functional ingredient placed in a central region between two adjacent flexible soluble porous sheets, said at least one functional ingredient being selected from the group consisting of cleaning actives, active ingredients for personal care and their combinations; and wherein the cleaning actives are selected from the group consisting of linear alkyl benzene sulfonate, free fragrances, encapsulated fragrances, fragrance microcapsules, silicones, emollients, enzymes, bleaches, dyes, fillers, rheology modifiers, pH modifiers, and combinations thereof ; and wherein the personal care actives are selected from the group consisting of emollients, humectants, conditioning agents, and combinations thereof.

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