Filament for an oral care implement and oral care implement

Abstract

A filament for an oral care implement has a longitudinal axis and a multi-edged cross-sectional area extending in a plane substantially perpendicular to the longitudinal axis, the multi-edged cross-sectional area having at least 18 projections and at least 18 grooves, the projections and grooves being arranged in an alternating manner. Each projection has a peak, and a peak-to-peak distance is measured from one peak of a projection to a neighboring peak of another projection. Each groove has a bottom with a concave curvature formed by neighboring and converging projections, the concave curvature having a radius. A ratio of the peak-to-peak distance to the radius of the curvature of the groove is from about 2 to about 4, preferably about 3.

Description

FIELD OF THE INVENTION

[0001] The present disclosure is concerned with a filament for an oral care implement, the filament having a longitudinal axis and a multi-edged cross-sectional area extending in a plane substantially perpendicular to the longitudinal axis, the multi-edged cross-sectional area having at least 18 projections and at least 18 grooves, the projections and grooves being arranged in an alternating matter. The present disclosure is further concerned with a tuft comprising such filament and a head for an oral care implement with such tuft, as well as with an oral care implement comprising such head.BACKGROUND OF THE INVENTION

[0002] Tufts composed of a plurality of filaments for oral care implements, like manual or powered toothbrushes, are well known in the art. Generally, the tufts are attached to a bristle carrier of a head intended for insertion into a user's oral cavity. A grip handle is usually attached to the head, which handle is held by the user during brushing. The head is either permanently connected to or repeatedly attachable to and detachable from the handle.

[0003] In order to clean teeth effectively, appropriate contact pressure has to be provided between the free ends of the filaments and the teeth. Generally, the contact pressure depends on the bending stiffness and the displacement of the filaments, while the bending stiffness of a single filament depends on its length and cross-sectional area. Usually, filaments with greater length show lower bending stiffness as compared to shorter filaments. However, relatively thin filaments tend to flex away easily and the relatively low bending stiffness results in reduced plaque removal efficiency on teeth surfaces, as well as in less interproximal / interdental penetration properties and cleaning performance. In order to compensate said reduction in bending stiffness of longer filaments, the size of the cross-sectional area of a filament could be increased. However, relatively thick filaments may create an unpleasant brushing sensation and tend to injure the gums in the oral cavity. In addition, thicker filaments may show reduced bend recovery and usage of said filaments may generate a worn-out impression of the tuft pattern after a relatively short time of use.

[0004] Filaments having a profile along their length extension resulting in a non-circular cross-sectional area, e.g. a polygonal- or a cross-shaped cross-sectional area, are also known in the art. Such filaments shall improve cleaning properties of oral care implements during normal use. In particular, the profiled edges should provide a stronger scraping action during a brushing process to improve removal of plaque and other residuals on the teeth surfaces.

[0005] While toothbrushes comprising these types of filaments clean teeth adequately, they are sometimes perceived as being harsh on the gums. Furthermore, during manufacturing processes and during brushing actions cross-shaped filaments / bristles tend to easily catch amongst themselves which results in a worn-out appearance of the toothbrush, and difficulties during manufacturing / bristling processes.

[0006] It is an object of the present disclosure to provide a filament, a tuft and a head for an oral care implement which overcomes at least one of the above-mentioned drawbacks. It is also an object of the present disclosure to provide an oral care implement comprising such head.SUMMARY OF THE INVENTION

[0007] In accordance with one aspect, a filament for an oral care implement is provided, the filament having a longitudinal axis and a multi-edged cross-sectional area extending in a plane substantially perpendicular to the longitudinal axis, the multi-edged cross-sectional area having at least 18 projections and at least 18 grooves, the projections and grooves being arranged in an alternating manner, each projection having a peak, a peak-to-peak distance being measured from one peak of a projection to a neighboring peak of another projection, and each groove having a bottom with a concave curvature formed by neighboring and converging projections, the concave curvature having a radius, wherein a ratio of the peak-to-peak distance to the radius of the curvature of the groove is from about 2 to about 4, preferably about 3.

[0008] In accordance with one aspect, a tuft and a head for an oral care implement are provided comprising such filament.

[0009] In accordance with one aspect an oral care implement is provided that comprises such head.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The invention is described in more detail below with reference to various embodiments and figures, wherein:

[0011] FIG. 1 shows a schematic top-down view of an oral care implement comprising head with a plurality of filaments according to the present disclosure;

[0012] FIG. 2 shows a schematic top-down view of the head of FIG. 1;

[0013] FIG. 3 shows a schematic side view of the head of FIG. 2;

[0014] FIG. 4 shows a schematic perspective view of the filament of FIG. 1;

[0015] FIG. 5 shows a schematic cross-sectional view of the filament of FIG. 4;

[0016] FIG. 6 shows an enlarged view of a section of the cross-sectional view of FIG. 5;

[0017] FIG. 7 shows another enlarged view of a section of the cross-sectional view of FIG. 5;

[0018] FIG. 8 shows a schematic cross-sectional view of a filament according to the state of the art;

[0019] FIG. 9 shows a schematic perspective view of another filament according to the state of the art;

[0020] FIG. 10 shows a diagram in which brushing results of filaments according to FIG. 4 are compared with brushing results of filaments according to FIG. 9; and

[0021] FIG. 11 shows a diagram in which brushing results of filaments according to FIG. 4 are compared with brushing results of filaments according to FIG. 8.DETAILED DESCRIPTION OF THE INVENTION

[0022] A filament according to the present disclosure has a longitudinal axis which is defined by the main extension of the filament. In the following, the extension of the filament along its longitudinal axis may also be referred to as the “longitudinal extension of the filament”. The filament has a cross-sectional area which extends in a plane that is substantially perpendicular to the longitudinal axis. The shape of said cross-sectional area is multi-edged and comprises at least 18 projections and 18 grooves. The projections and grooves (which can also be described as channels) are arranged in an alternating manner. For example, the multi-edged cross-sectional area may have between 18 to 22 projections and respective grooves. Preferably, the multi-edged cross-sectional area may have 20 projections and 20 grooves, the projections and grooves being arranged in an alternating manner. Each projection of the multi-edged cross-sectional area comprises a peak lying on the outermost circumference, i.e. on an outer envelope circle. Further, each groove has a bottom with a concave curvature formed by neighboring and converging projections. In other words, a concave curvature with an inwardly curved radius is formed at the bottom of each groove.

[0023] Further, each groove may have a groove depth. The depth of each groove is defined as a perpendicular distance extending between the bottom of the groove and a tangent extending between two neighboring peaks. Moreover, each projection / peak may have a peak height. The peak height of the projections is defined as a perpendicular distance between the peak of a projection and a tangent between two neighboring bottoms.

[0024] Surprisingly, it has been found out that dimensions and certain filament properties can be critical for ensuring that filaments and tufts composed thereof are durable, flexible, effective in cleaning, and comfortable to use. When considering the performance of filaments in the context of toothbrushes, specific parameters like peak-to-peak distance, groove radius, groove depth, and peak heights along with their ratios, may have significant implications for various aspects of the toothbrush's functionality.

[0025] By optimizing the claimed parameters of the filament, a filament can be provided that meets consumer needs and provides superior cleaning performance. Surprisingly, it has been found out that a filament geometry according to the present disclosure provides improved cleaning performance while maintaining brush comfort in the mouth (see data discussed in relation to FIGS. 10 and 11). In addition, it has been found out that such geometry helps to reduce the appearance of filament / tuft wear since there is less likelihood that the filaments get caught during brushing (as compared to e.g. cross-shaped filaments). Further, the manufacturability of such filaments during a toothbrush manufacturing / tufting process is improved.

[0026] A ratio of the peak-to-peak distance to the groove radius affects how the filaments interact with toothpaste and water, influencing how effectively the cleaning agents can penetrate and clean.

[0027] According to the present disclosure, a ratio of the peak-to-peak distance to the radius of the curvature of the groove is from about 2 to about 4, preferably about 3. It has been found out that such ratio provides a number of benefits as discussed below. Filaments with a ratio according to the present disclosure provide a user with more gentle brushing experience as compared to brushes having filaments with less, but more dominant projections, while maintaining good cleaning performance. The peaks of the projections can enter gaps and irregularities in the teeth structure more easily (as compared to other standard circular filaments or filaments having a higher number of edges) to remove plaque and debris more effectively. The peaks can provide a scraping effect so that plaque and other debris get loosened more effectively. The grooves can then capture the disrupted plaque and move it away from the teeth. The groove radius also influences how the filaments flex during brushing. Bristles that are too stiff may cause discomfort, while those that are too flexible may not provide effective cleaning. A filament according to the present disclosure has an optimum radius considering both extremes. Due to the specific geometry of the filament, i.e. peak-to-peak distance of the projections in relation to the radius of the curvature of the groove, the overall processability of the filament is improved as well. Surprisingly, it has been found out that such filaments intermingle less and do not catch amongst themselves easily during a brisling / manufacturing process.

[0028] A distance measured between one peak of a projection to a neighboring peak of another projection may be within a range from about 0.01 mm to about 0.05 mm, preferably from about 0.02 mm to about 0.045 mm. These peaks may generate relatively high concentrated stress on the tooth surfaces to disrupt and remove plaque.

[0029] Surprisingly, it has been found out that such peak-to-peak distance in combination with 20 projections / grooves further improves manufacturability significantly (as compared to filaments having less projections, e.g. cross-shaped filament). Dimensionally, such filaments come close to round filaments which supports processability as said filaments roll more easily into the fiber channel (as compared to filaments having less projections). Such filaments tend to interlock less, thereby maintaining a high throughput rate during bristling processes, similar to standard round filaments, while providing improved cleaning properties (see discussion of data below).

[0030] Further, the peak-to-peak distance influences the texture of the bristles. A smaller peak-to-peak distance creates finer filaments that can reach into tight spaces between teeth, improving cleaning efficiency. It also aids in the capillary action, provided by the grooves. Good capillary action can significantly enhance toothbrush performance by facilitating the effective dispersion and retention of toothpaste and water on the filament surface. This phenomenon allows the filament to draw toothpaste into their micro-structures, promoting even distribution across teeth and gums, which aids in dislodging plaque and food particles. The moisture retention provided by capillary forces also creates a lubricating effect, improving the comfort and efficiency of brushing while enhancing the activation of cleaning agents in the toothpaste.

[0031] According to the present disclosure, the radius of each groove is within a range from about 0.005 mm to about 0.03 mm, preferably from about 0.01 mm to about 0.02 mm. The depth of each groove may be within a range from about 0.002 mm to about 0.02 mm, preferably from about 0.005 mm to about 0.015 mm. The groove radius and groove depth influence how the bristles bend and flex under pressure during use. The filament geometry according to the present disclosure enhances the bristles' ability to withstand cyclic load by repeated bending without breaking, which is crucial for maintaining the bristles' effectiveness over time. The groove radius influences how the filaments flex during brushing. Bristles that are too stiff may cause discomfort, while those that are too flexible may not provide effective cleaning. A filament according to the present disclosure has an optimum radius considering both extremes.

[0032] Generally, softer filaments in toothbrushes are considered superior to harder ones for several reasons, particularly regarding oral health and user comfort. Softer filaments are gentler on the gums, reducing the risk of irritation, inflammation, and gum recession. Also, softer filaments can adapt better to the contours of teeth and gums, allowing for effective cleaning in hard-to-reach areas without causing harm. They also minimize the risk of enamel wear, vs. harder filaments that can exert excessive pressure, potentially leading to long-term damage. It has been found out that many users find softer bristles more comfortable, which encourages longer and more thorough brushing sessions, ultimately improving oral hygiene practices and routines. Furthermore, softer filaments create a gentle scrubbing action that disrupts plaque effectively without excessive abrasion. They are also easier to clean and rinse, helping to maintain hygiene by reducing bacterial buildup on the toothbrush. Also, softer filaments are particularly suitable for individuals with dental work, such as braces or crowns, as they provide effective cleaning without causing discomfort.

[0033] Further, due to the multi-edged geometry of the filament, each single filament is stiffer than a circular shaped filament, when made of the same amount of material. However, said higher stiffness is compensated by the relatively high number of projections and grooves, resulting in each single filament being perceived as being gentler as compared to e.g. cross-shaped filaments, or filaments having less edges than 18. This results in improved sensory experience during brushing while providing increased cleaning efficiency.

[0034] The multi-edged cross-sectional area of the filament has an outer diameter. In the context of the present disclosure the outer diameter is defined by the length of a straight line that passes through the center of the filament's cross-sectional area and whose endpoints lie on the most outer circumference of the cross-sectional area. In other words, the multi-edged cross-sectional area has an imaginary outer circumference in the form of a circle (i.e. outer envelope circle), and the outer diameter is defined as the longest straight-line segment of the circle passing through the center of the circle.

[0035] The outer diameter of the filament according to the present disclosure may be within a range from about 0.1016 mm (4 mil) to about 0.2286 mm (9 mil), preferably from about 0.1524 mm (6 mil) to about 0.2159 mm (8.5 mil), further preferably about 0.1778 mm (7 mil).

[0036] A ratio of a peak height to the depth of the groove may be from about 1 to about 2, preferably about 1.5. The peak height to groove depth ratio directly impacts the effectiveness, comfort, durability, and overall user experience when brushing teeth. A well-balanced ratio of about 1 to about 2, preferably about 1.5 may ensure that filaments effectively reach and clean teeth while providing a gentle yet firm brushing experience, being essential for maintaining oral hygiene. This well-balanced peak height to groove depth ratio affects how well the filament can reach and clean the surfaces of teeth and gums. If the peaks are too high relative to the groove depth, the filaments may not flex adequately, leading to reduced effectiveness in plaque removal. Conversely, if the grooves are too deep compared to the height of the peaks, the filament may not provide enough scrubbing action. The ratio according to the present disclosure ensures that the filaments are gentle enough for sensitive gums while still being effective at cleaning. Consumers often look for toothbrushes that strike a balance between effective cleaning and comfort. Additionally, the peak height to groove depth ratio influences the longevity of the bristles, preventing premature wear, and contributes to the aesthetic appeal and tactile feedback during use, resulting in higher consumer value.

[0037] Plaque removal tests were performed to compare cleaning effectiveness of standard cylindrical filaments, filaments comprising six projections and six grooves, and filaments according to the present disclosure. Higher plaque removal rates were observed for filaments according to the present disclosure (see discussion of data below). As shown in FIGS. 10 and 11 and further explained below, a tuft comprising a plurality of filaments according to the present disclosure provides improved plaque removal from the buccal, lingual, occlusal and interproximal surfaces as well as along the gumline as compared to a tuft composed of circular or conventional multi-edged filaments.

[0038] Moreover, in the past it has been observed that e.g. cross-shaped filaments (i.e. with four projections and grooves) have the disadvantage that these type of filaments can easily catch amongst themselves, both during manufacturing and brushing. Now, it has been surprisingly found out that the specific geometry / contour of the outer surface of the filament according to the present disclosure allows for improved manufacturability since there is significant less likelihood that the filaments get caught when a plurality of said filaments is combined to form one tuft during a so-called “picking process”. Also, with filaments according to the present disclosure, less filament damage occurs during the brush manufacturing process, e.g. when the filaments get picked and fixed on the mounting surface of the brush head during a stapling or hot tufting process. In the past, it has been observed that a relatively high number of conventional cross-shaped filaments get damaged during the picking process, in particular projections may break away from the filament or the filament gets spliced in the converging region at the bottom of a groove. Spliced filaments can provide relatively sharp edges which may harm / injure the oral tissue during brushing.

[0039] One critical barrier for producing multi-edged filaments is the selection of material choices. Most multi-edged filaments have a limitation of only being produced from polybutylene terephthalate (PBT). This is because the material is relatively rigid and, thus, can maintain integrity of the filament structure. If produced from polyamides (e.g. PA6, PA6.10 or PA6.12), the filaments with a geometry according to the art absorb water, and during the course of a single brushing cycle, the elastic properties of the material deteriorate, and the filaments tend to splay significantly. This typically reduces brushing performance as toothbrushes wear out quickly. However, it has now been surprisingly found out that a filament according to the present invention, can be extruded from both, PBTs and polyamides (e.g. PA6, PA6.10, PA6.12, PA10.10 or PA12) without losing the filament's structure during brushing. There is no limitation to PBT material.

[0040] Although being able to be made from a high number of different materials, including polybutylene terephthalate (PBT), the filament according to the present disclosure may be made from polyamide, e.g. PA6, PA6.10, PA6.12, PA10.10 or PA12, with or without an abrasive such as kaolin clay, and / or of polyamide indicator material, e.g. nylon indicator material, colored at the outer surface. The coloring on the polyamide indicator material may be slowly worn away as the filament is used over time to indicate the extent to which the filament is worn.

[0041] Filaments according to the present disclosure can be extruded from e.g. PA6, PA6.10, PA6.12, PA10.10 or PA12 material. Relatively low filament stiffness is obtained if PA12 is used.

[0042] This is due to its longer aliphatic chains, lower crystallinity, and reduced hydrogen bonding density, resulting in a lower Young's modulus and higher elongation at break. PA6.12 provides moderate flexibility and is stiffer than PA12, as its denser hydrogen bonding network contributes to increased rigidity, while still being more flexible than many traditional nylons. In contrast, PBT is the least flexible material of the aforementioned options, characterized by high crystallinity and strong intermolecular forces, leading to the highest stiffness and lowest elongation at break.

[0043] The ability to be extruded from polyamide, e.g. PA6, PA6.10, PA6.12, PA10.10, PA12, the filament according to the present disclosure exhibits several advantages, including enhanced filament flexibility, allowing the filaments to adapt to the contours of teeth and gums more easily, thereby ensuring effective cleaning without applying excessive pressure. The stiffness of such filament is lower as compared to a filament made from PBT as PBT is generally harder and more rigid. Reduced stiffness contributes to a gentler brushing experience, making the filaments suitable for users with sensitive gums.

[0044] As polyamide materials facilitate water absorption / hydration of the filaments during use, the filaments can provide a gentler brushing sensation. Furthermore, filaments allowing for higher water absorption are relatively easy to dye, e.g. to provide “indicator” filaments. Over time and with regular use, the color of indicator filaments tends to fade away or change color characteristics, indicating that the filaments are wearing down and may no longer be effective for proper cleaning. This may serve as a reminder for users to replace their toothbrush according to dentists' recommendations (every three months), thereby ensuring optimal oral hygiene. Additionally, indicator filaments can help users to gauge their brushing technique. For instance, if filaments become worn out too quickly, this may suggest that the user applies too much pressure during brushing. Overall, such filaments can enhance user awareness and promote better dental care routines.

[0045] Also, filaments made from polyamide (e.g. PA6, PA6.10, PA6.12, PA10.10 or PA12) may simplify manufacturing / bristling processes. While PBT may create a significant amount of dust, thereby creating challenges at filament feeding and end rounding stations, filaments according to the present disclosure stay cleaner as they show less abrasion. The ability to smoothly end-round filament tips is important for comfort and safety. Further, the higher hardness of PBT filaments may also lead to increased wear and tear on trimming tools, requiring more frequent tool changes and maintenance.

[0046] The filament / the material from which the filament is made according to the present disclosure may comprise a component selected from fluoride, zinc, strontium salts, flavor, silica, pyrophosphate, hydrogen peroxide, potassium nitrate or combinations thereof. For example, fluoride may provide a mineralization effect and, thus, may prevent tooth decay. Zinc may strengthen the immune system of the user. Hydrogen peroxide may bleach / whiten the teeth. Silica may have an abrasive effect to remove dental plaque and debris more effectively. Pyrophosphate may inhibit the formation of new plaque, tartar and dental calculus along the gum line. A filament comprising pyrophosphate may offer lasting protection against inflammations of the gums and mucous membrane of the mouth. For example, if a plurality of such filaments are bundled together to form a tuft, they may be arranged in a manner that filaments at the tuft's outer lateral surface may comprise pyrophosphate to inhibit the formation of plaque, tartar and dental calculus along the gum line whereas filaments arranged in the center of the tuft may comprise fluoride to mineralize the teeth during a brushing process.

[0047] Also, the filament may comprise at least two segments of different materials. At least one segment may comprise polyamide, e.g. PA6, PA6.10, PA6.12, PA10.10 or PA12, with or without an abrasive such as kaolin clay, and / or a polyamide indicator material, e.g. a PA6, PA6.10, PA6.12, PA10.10 or PA12 indicator material, colored at the outer surface, while at least another segment may comprise a thermoplastic elastomer material (TPE), and / or polybutylene terephtalate (PBT) with or without an abrasive such as kaolin clay. These at least two segments may be arranged in a side-by-side structure or in a core-sheath structure which may result in reduced stiffness of the overall filament.

[0048] The filament according to the present disclosure may have a surface area to volume ratio from about 32 mm−1 to about 36 mm−1, preferably from about 33 mm−1 to about 35 mm−1. Such surface area to volume ratio is relatively high as compared to standard filaments having a multi-edged surface geometry (e.g. filaments comprising six grooves and six projections as discussed in relation to the Figures). The relatively high surface area to volume ratio enables a relatively high water uptake rate. When bundled together to form a tuft, the high surface to volume ratio of the filaments according to the present disclosure influences the way how the filaments can be packed within a tuft. When the filaments according to the present disclosure are packed and bundled together in a tuft, the neighboring filaments create a beneficially capillary effect, resulting in the aforementioned high water uptake rate.

[0049] A brush head comprising tufts composed of filaments according to the present disclosure may have a water uptake rate from about 0.3 g to about 0.5 g, preferably from about 0.4 g to about 0.45 g. Such water uptake is measured when the filament tufts are exposed to water over 30 seconds. Filaments according to the present disclosure, made from polyamide, e.g. PA6, PA6.10, PA6.12, PA10.10 or PA12, having a surface area to volume ratio from about 32 mm−1 to about 36 mm−1, preferably from about 33 mm−1 to about 35 mm−1 demonstrate superior moisture retention due to the specific surface structure and resulting capillary effects, further facilitating hydration of the filaments during use. More hydrated, and, thus, softer filaments tend to be gentler on gums, which can reduce irritations during brushing. A more comfortable brushing experience can result in more compliant brushing habits. Water-retaining filaments can also better conform to the contours of teeth and gums, allowing for more thorough cleaning in difficult-to-reach areas. Also, higher water content can lower friction between the filaments and teeth, leading to a smoother brushing experience while minimizing potential enamel wear. Further, increased water uptake can facilitate better lathering of toothpaste, thereby improving the spread of fluoride and other beneficial ingredients, enhancing the overall cleaning efficacy.

[0050] A tuft comprising a plurality of filaments according to the present disclosure and being attached to a head for an oral care implement may have a longitudinal axis and a cross-sectional area which extends in a plane that is perpendicular to said longitudinal axis. The plurality of filaments may be arranged in a manner so that the cross-sectional area of the tuft has a scaled up-shape of the respective shape of each individual filament which makes up the tuft. In other words, the tuft can be a scaled-up version of its filaments' shape, i.e. the shape of the cross-sectional area of the tuft may have substantially the same multi-edged cross-sectional area as each individual filament but in a larger size. In the context of this disclosure the term “cross-sectional area having a scaled-up shape” means a cross-sectional area comprising the same shape but in increased size. In other words, the type of shape may be the same, but the size of the cross-sectional area is different, i.e. enlarged. Any gaps, irregularities, reliefs or slots which may be present between two adjacent individual filaments at the outer circumference of the cross-sectional area of the tuft do not contribute to the substantial shape of said cross-sectional area and are, thus, to be neglected.

[0051] Such tuft may provide increased cleaning properties. The specific shape / geometry of the individual filaments has specific cleaning properties which differ from the properties of regular filaments. These specific cleaning properties may be enhanced by arranging the filaments in a manner so that they form a cross-sectional shape of the overall tuft which is a scaled-up version of the cross-sectional shape of each individual filament. In addition, as the specific geometry of each single filament may be generally not visible to the user, the tuft in accordance with the present disclosure may communicate the respective geometry to the user and, thus, the corresponding cleaning properties of the filaments which make up said tuft.

[0052] The projections of the multi-edged filament may taper radially off in an outward direction, i.e. in a direction away from the center of the cross-sectional area and towards the outer circumference. Such tapered projections may assure access to narrow spaces and other hard to reach areas and may be able to penetrate into / enter interproximal areas more deeply and effectively.

[0053] The filament may be a substantially cylindrical filament, i.e. the filament may have a substantially cylindrical outer lateral surface. In other words, the shape and size of the multi-edged cross-sectional area of the filament along its longitudinal axis may not vary substantially, i.e. the shape and size of the cross-sectional area may be substantially constant over the longitudinal extension of the filament. In the context of this disclosure the term “outer lateral surface of a filament” means any outer face or surface of the filament on its sides. Cylindrical filaments are generally slowly worn away which may provide longer lifetime of the filaments.

[0054] The cylindrical filament may have a substantially end-rounded tip / free end to provide gentle cleaning properties. End-rounded tips may avoid that gums get injured during brushing. Within the context of this disclosure, end-rounded filaments would still fall under the definition of a substantially cylindrical filament.

[0055] Alternatively, the filament may comprise along its longitudinal axis a substantially cylindrical section and a tapered section, the tapered section tapering in the longitudinal direction towards a free end of the filament, and the cylindrical portion has a cross-sectional area according to the present disclosure. In other words, the filament may be a tapered filament having a pointed tip. Tapered filaments may achieve optimal penetration into areas between two teeth as well as into gingival pockets during brushing and may provide improved cleaning properties. The tapered filament may have an overall length extending above the mounting surface within a range from about 8 mm to about 16 mm, optionally about 12.5 mm, and a tapered portion within a range from about 5 mm to about 10 mm measured from the tip of the filament. The pointed tip may be needle shaped, may comprise a split or a feathered end. The tapering section may be produced by a chemical and / or mechanical tapering process.

[0056] A plurality of filaments according to the present disclosure may be bundled together to form a tuft attached to an oral care implement. The oral care implement may be a toothbrush comprising a handle and a head. The head extends from the handle and may be either repeatedly attachable to and detachable from the handle or the head may be non-detachably connected to the handle. The toothbrush may be an electrical or a manual toothbrush.

[0057] The head may comprise a bristle carrier having a substantially circular or oval shape. Such a bristle carrier may be provided for an electrical toothbrush which may perform a rotational oscillation movement. The bristle carrier of an electrical toothbrush can be driven to rotate about and to move axially along an axis of movement in an oscillating manner, wherein such axis of movement may extend substantially perpendicular to the plane defined by the upper top surface of the bristle carrier. One or more tuft(s) comprising a plurality of filaments according to the present disclosure may be attached to the bristle carrier. Said tuft(s) may allow the filaments projections to penetrate into interproximal areas and hard to reach regions more easily during the rotational oscillation movement of the head which may provide further improved cleaning properties of the head. Plaque and other residues may be loosened by the oscillating action of the filaments being substantially perpendicular to the tooth surfaces, whereas the rotational movement may sweep the plaque and further residues away.

[0058] A head for an oral care implement in accordance with the present disclosure may comprise a bristle carrier being provided with at least one tuft hole, e.g. a blind-end bore. A tuft comprising a plurality of filaments according to the present disclosure may be fixed / anchored in said tuft hole by a stapling process / anchor tufting method. This means, that the filaments of the tuft are bent / folded around an anchor, e.g. an anchor wire or anchor plate, for example made of metal, in a substantially U-shaped manner. The filaments together with the anchor are pushed into the tuft hole so that the anchor penetrates into opposing side walls of the tuft hole thereby anchoring / fixing / fastening the filaments to the bristle carrier. The anchor may be fixed in opposing side walls by positive and frictional engagement. In case the tuft hole is a blind-end bore, the anchor holds the filaments against a bottom of the bore. In other words, the anchor may lie over the U-shaped bend in a substantially perpendicular manner. Since the filaments of the tuft are bent around the anchor in a substantially U-shaped configuration, a first limb and a second limb of each filament extend from the bristle carrier in a filament direction. Filament types which can be used / are suitable for usage in a stapling process are also called “two-sided filaments”. Heads for oral care implements which are manufactured by a stapling process can be provided in a relatively low-cost and time-efficient manner. Due to the improved geometry of the filament according to the present disclosure, fewer filaments get damaged, e.g. by slicing, when the filaments get picked and fixed on the mounting surface of the brush head during the stapling process. Further, fewer filaments get caught on the outer surface of a neighboring filament when a plurality of filaments are picked to form one tuft.

[0059] Alternatively, the at least one tuft may be attached / secured to the head by means of a hot tufting process. One method of manufacturing the head of an oral care implement may comprise the following steps: Firstly, the at least one tuft may be formed by providing a desired amount of filaments according to the present disclosure. Secondly, the tuft may be placed into a mold cavity so that ends of the filaments which are supposed to be attached to the head extend into said cavity. Thirdly, the head or an oral care implement body comprising the head and the handle may be formed around the ends of the filaments extending into the mold cavity by an injection molding process, thereby anchoring the at least one tuft in the head. Alternatively, the tuft may be anchored by forming a first part of the head-a so called “sealplate”-around the ends of the filaments extending into the mold cavity by an injection molding process before the remaining part of the oral care implement may be formed. Before starting the injection molding process, the ends of the at least one tuft extending into the mold cavity may be optionally melted or fusion-bonded to join the filaments together in a fused mass or ball so that the fused masses or balls are located within the cavity. The at least one tuft may be held in the mold cavity by a mold bar having blind holes that correspond to the desired position of the tuft on the finished head of the oral care implement. In other words, the filaments of the at least one tuft attached to the head by means of a hot tufting process may be not doubled over a middle portion along their length and may be not mounted in the head by using an anchor / staple. The at least one tuft may be mounted on the head by means of an anchor-free tufting process. A hot tufting manufacturing process allows for complex tuft geometries. For example, the tuft may have a specific topography / geometry at its free end, i.e. at its upper top surface, which may be shaped to optimally adapt to the teeth's contour and to further enhance interproximal penetration. For example, the topography may be chamfered or rounded in one or two directions, pointed or may be formed linear, concave or convex. Due to the improved geometry of the filament according to the present disclosure, fewer filaments get damaged, e.g. by slicing, when the filaments get picked and fixed on the mounting surface of the brush head during the hot-tufting process. Further, fewer filaments get caught on the outer surface of a neighboring filament when a plurality of filaments are picked to form one tuft.

[0060] According to the present disclosure, an oral care implement refers to a tool or device used for maintaining oral hygiene and taking care of teeth and gums. The oral care implement may encompass various features to clean, brush, and care for teeth and soft tissue in the mouth. The oral care implement according to the present disclosure can be an electrical i.e., powered driven toothbrush, or a manual toothbrush.

[0061] A manual toothbrush is a traditional oral care implement comprising a handle and a brush head with at least one tuft comprising a plurality of filaments according to the present disclosure. A manual toothbrush requires manual movement and brushing action by the user to remove plaque, food particles, and maintain oral hygiene. A manual toothbrush according to the present disclosure targets consumers who prefer traditional toothbrush options.

[0062] A powered toothbrush, also known as an electric toothbrush, is a toothbrush that incorporates mechanical movements to assist with the brushing process. Powered toothbrushes typically feature oscillating, rotating, or vibrating brush heads, which provide additional cleaning action compared to manual brushing. They often come with built-in timers and force sensors to ensure proper brushing technique and duration. The head or toothbrush refill of a powered oral care implement may comprise a disk having a circular shape and a mounting surface from which a number of filaments according to the present disclosure extends.

[0063] A head for a manual toothbrush or a vibrating toothbrush may have a longitudinal length extension extending between a proximal end and a distal end, the distal end being opposite the proximal end, the proximal end being closest to the handle. Again, the head of a manual toothbrush typically comprises a mounting surface from which a number of filaments according to the present disclosure extends. The head of a powered or manual oral care implement may be permanently attached to, or repeatedly attachable to and detachable from the handle.

[0064] The following is a non-limiting discussion of example embodiments of oral care implements and parts thereof in accordance with the present disclosure, where reference to the Figures is made.

[0065] FIG. 1 shows a schematic top-down view of an oral care implement 10, in the present case a manual toothbrush 10. Toothbrush 10 comprises a handle 12 and a head 14 extending from the handle 12 in a longitudinal direction. The head 14 is further shown in a top down and side view in FIGS. 2 and 3, respectively. The head 14 has a proximal end 41 close to the handle 12 and a distal end 40 furthest away from the handle 12, i.e. opposite the proximal end 41. The head 14 may have the shape of an oval with a length extension 52 and a width extension 51 substantially perpendicular to the length extension 52. A plurality of tufts 16 having a plurality of filaments 20 in accordance with the present disclosure may be secured to the head 14 by means of a hot tufting or stapling process. The tufts 16 may extend from a mounting surface 18 of the head 14 in a substantially orthogonal manner over a tuft length 17 of about 9 mm to about 12 mm.

[0066] The tufts 16 as illustrated in FIG. 3 comprise a plurality of filaments 20 according to the present disclosure, one of them being shown in FIGS. 4 and 5. Filament 20 may be made from polyamide material (e.g. PA6, PA6.10, PA6.12, PA10.10 or PA12).

[0067] The filament 20 has a longitudinal axis 22 (see FIG. 4) and a multi-edged cross-sectional area 24 extending in a plane substantially perpendicular to the longitudinal axis 22. FIG. 5 shows a schematic cross-sectional view of filament 20. The multi-edges cross-sectional area 24 of filament 20 has 20 projections 26 and 20 grooves 28. The projections 26 and grooves 28 are arranged in an alternating manner.

[0068] FIGS. 6 and 7 show enlarged views of different sections of the filament's cross-sectional area 24 shown in FIG. 5. Each projection 26 has a peak 30, and each groove 28 has a bottom 32 with a concave curvature 34 formed by neighboring and converging projections 26. The concave curvature 34 has a radius 36. The radius 36 of each groove 28 is within a range from about 0.005 mm to about 0.03 mm, preferably from about 0.01 mm to about 0.02 mm. Further, each groove 28 has a depth 38. Said groove depth 38 is defined as a perpendicular distance between the bottom 32 of the groove 28 and a tangent 42 between two neighboring peaks 30. The depth 38 of each groove 28 is within a range from about 0.002 mm to about 0.02 mm, preferably from about 0.005 mm to about 0.015 mm.

[0069] Each projection 26 has a peak height 50. The peak height 50 of a projection 26 is defined as a perpendicular distance between the peak 30 of a projection 26 and a tangent 52 between two neighboring bottoms 32. A ratio of the peak height 50 to the depth 38 of the groove 28 may be from about 1 to about 2, preferably about 1.5.

[0070] A distance 48 measured between one peak 30 of a projection 26 to a neighboring peak 30 of another projection 26 may be within a range from about 0.01 mm to about 0.05 mm, preferably within a range from about 0.02 mm to about 0.045 mm. A ratio of the peak-to-peak distance 48 to the radius 36 of the curvature 34 of the groove 28 may be from about 2 to about 4, preferably about 3.

[0071] The cross-sectional area 24 of filament 20 has an outer diameter 44 passing through the center 46 of the filament's cross-sectional area 24. The endpoints of the outer diameter 44 lie on the most outer circumference of the cross-sectional area 24. The outer diameter 44 may have as extension within a range from about 0.1016 mm (4 mil) to about 0.2286 mm (9 mil), preferably from about 0.1524 mm (6 mil) to about 0.2159 mm (8.5 mil), e.g. 0.178 mm (7 mil).

[0072] The filament 20 may have a surface area to volume ratio from about 32 mm−1 to about 36 mm−1, preferably from about 33 mm−1 to about 35 mm−1.

[0073] When exposed to water over 30 seconds, a water uptake rate of the filaments 20 (when bundled together to form tufts, attached to a brush head according to FIGS. 1 to 3) may be from about 0.3 g to about 0.5 g, preferably from about 0.4 g to about 0.45 g.

[0074] Dimensional ranges of the filament 20 according to the present disclosure are for 0.1524 mm (6 mil) to about 0.2159 mm (8.5 mil) diameter range as follows:

[0075] Peak to peak distance: 0.02 mm to 0.045 mm

[0076] Groove radius: 0.008 mm to 0.03 mm

[0077] Groove depth: 0.003 mm to 0.015 mm

[0078] A filament according to the present disclosure, provided in a diameter of 0.1524 mm (6 mil) has the following dimensions:

[0079] Number of projections: 20

[0080] Number of grooves: 20

[0081] Peak to peak distance: 0.027 mm+ / −0.006 mm

[0082] Groove radius: 0.0125 mm+ / −0.0028 mm

[0083] Groove depth: 0.006 mm+ / −0.0019 mm

[0084] Peak height: 0.008+ / −0.0019 mm

[0085] Cross sectional area: 0.0166029 mm2

[0086] Volume of filament: 0.182 mm3

[0087] Surface area to volume ratio: 34.12 mm−1

[0088] FIG. 8 shows a cross-sectional area 110 of a filament 100 according to the art. The filament 100 comprises six projections 120 and six grooves 130, the projections 120 and grooves 130 being arranged in an alternating manner. The filament 100 has a diameter 140 which can be the same as the diameter of filament 20. A depth 150 of the groove 130 as well as the radius 140 of the curvature of the groove 130 may be in accordance with the description below.

[0089] A filament 100 provided in a diameter of 0.1524 mm (6 mil) has the following dimensions:

[0090] Peak to peak distance: 0.0084 mm

[0091] Groove radius: 0.04 mm

[0092] Groove depth: 0.01 mm

[0093] Peak height: 0.018 mm

[0094] Cross sectional area: 0.0171560 mm2

[0095] Volume of filament: 0.188716 mm3

[0096] Surface area to volume ratio: 31 mm−1

[0097] FIG. 9 shows another filament 200 according to the art. The filament has a substantially circular cross-sectional area 210.COMPARISON EXPERIMENTSRobot Tests:

[0098] Brushing tests were performed to compare brushing performance and efficiency of plaque substitute removal on artificial teeth (typodonts) of the following filaments:

[0099] filaments according to FIGS. 4 to 7 (example embodiment 1),

[0100] filaments according to FIG. 8 (comparative embodiment 2), and

[0101] filaments according to FIG. 9 (comparative embodiment 3).

[0102] Filaments according to example embodiment 1, comparative embodiment 2 and comparative embodiment 3 were bundled in tufts and arranged on a mounting surface of a head according to FIGS. 1 to 3, respectively. To perform the brushing tests, a robot system KUKA 3 was used under the following conditions (cf. Table 1):TABLE 1program upperprogram lowerProductjawjawforcepower supplyAll tested productsEO_INDIEU_INDI3 Nnototal cleaning time60 s60 sprogram version9.11.09 Eng9.11.09 EngSYSTEC speed6060SYSTEC amplitude x / y20 / 020 / 0number of moves33Movementhorizontalused handle / mouldNo / noSpecification of the Filaments Tested:Example Embodiment 1Filament material: PA6.12Filament diameter: 0.178 mm (7 mil)

[0105] Number of projections: 20

[0106] Number of grooves: 20

[0107] Peak to peak distance: 0.0287 mm+ / −0.006 mm

[0108] Groove radius: 0.0145 mm+ / −0.0028 mm

[0109] Groove depth: 0.0094 mm+ / −0.0019 mm

[0110] Peak height: about 0.008+ / −0.0019 mm

[0111] Surface area to volume ratio: 32 mm−1 to about 36 mm−1

[0112] Tuft arrangement:

[0113] Brush head according to FIGS. 1 to 3, comprising 41 tufts:

[0114] Length of tuft: 10.5 mm+ / −0.9 mm

[0115] Circular cross-sectional shape

[0116] Diameter of tuft: 1.7 mm+ / −0.05 mmComparative Example 2Filament material: PA6.12

[0118] Filament diameter: 0.178 mm (7 mil)

[0119] Number of projections: 6

[0120] Number of grooves: 6

[0121] Peak to peak distance: about 0.0085 mm

[0122] Groove radius: about 0.04 mm

[0123] Groove depth: about 0.01 mm

[0124] Peak height: about 0.02 mm

[0125] Surface area to volume ratio: about 31 mm−1

[0126] Tuft arrangement:

[0127] Brush head according to FIGS. 1 to 3, comprising 41 tufts:

[0128] Length of tuft: 10.5 mm+ / −0.9 mm

[0129] Circular cross-sectional shape

[0130] Diameter of tuft: 1.7 mm+ / −0.05 mmComparative Example 3Filament material: PA6.12

[0132] Filament diameter (circular cross-sectional shape): 0.178 mm (7 mil)

[0133] Cross sectional area: 0.018145 mm2

[0134] Volume of filament: 0.199 mm3

[0135] Surface area to volume ratio: 26.46 mm−1

[0136] Tuft arrangement:

[0137] Brush head according to FIGS. 1 to 3, comprising 41 tufts:

[0138] Circular cross-sectional shape

[0139] Length of tuft: 10.5 mm+ / −0.9 mm

[0140] Diameter of tuft: 1.7 mm+ / −0.05 mm

[0141] FIG. 10 compares the amount of plaque substitute removal in % of example embodiment 1 with comparative example 3, each with respect to all tooth surfaces 78, buccal surfaces 80, lingual surfaces 82, lingual and buccal surfaces 84, occlusal surfaces 86, the gum line 88 and interproximal surfaces 90.

[0142] FIG. 11 compares the amount of plaque substitute removal in % of example embodiment 1 with comparative example 2, each with respect to all tooth surfaces 78, buccal surfaces 80, lingual surfaces 82, lingual and buccal surfaces 84, occlusal surfaces 86, the gum line 88 and interproximal surfaces 90.

[0143] FIGS. 10 and 11 clearly show that example embodiment 1 provides significant improved plaque removal properties with respect all tooth surfaces 78, buccal surfaces 80, lingual surfaces 82, lingual and buccal surfaces 84, occlusal surfaces 86, the gum line 88 and interproximal surfaces 90 as compared to comparative examples 2 and 3.

[0144] Regular circular filaments (e.g. of comparative example 3) tend to slide over plaque easily. In contrast thereto, the geometry or texture of filaments according to example embodiment 1 allows the filaments to grip the plaque and pull it away. The projections of the filaments help in scooping the plaque off the tooth surfaces. The grooves between the projections act as carriers to store plaque and keep the projections fresh to attack the rest of plaque. A capillary action of the grooves, along with effectiveness of paste, transports the plaque away.Water Uptake Tests:

[0145] Further, water uptake was measured for a brush containing filaments according to example embodiment 1 and comparative example 2. The filaments according to example embodiment 1 and comparative example 2 were bundled together to form tufts. 41 tufts comprising such filaments were attached to a brush head as shown in FIGS. 1 to 3. Each tuft has a substantially circular cross-sectional area with a diameter of 1.7 mm+ / −0.05 mm, and a tuft length of 10.5 mm+ / −0.9 mm. Both brushes / filament types were subjected to water for 30 seconds. A significant higher water uptake was measured for the brush / filaments according to example embodiment 1 (water uptake: 0.413 g) versus for the brush / filaments according to example embodiment 2 (water uptake: 0.253 g). The higher water uptake improves cleaning efficacy while maintaining comfort to the user. It is believed that the higher water uptake of the brush / filaments of example embodiment 1 is enabled by the higher surface area to volume ratio of said filaments, providing superior capillary effects.

[0146] Also, lower stiffness values were observed for filaments according to example embodiment 1 as compared to comparative examples 2 and 3. Filaments with more edges are designed with a more complex geometry that can bend and flex more easily during use. This flexibility enables the filaments to adapt better to the contours of teeth and gums, leading to a softer brushing experience.

[0147] A filament according to the present disclose enhances toothbrush performance significantly versus standard circular filaments, or filaments having a lower number of projections and grooves, as demonstrated by the experimental data. Further, a filament according to the present disclosure is gentle to teeth and gums, while enabling mass production with limited capital investment. Moreover, a filament / brush according to the present disclosure shows relatively low wear as compared to filaments / brushes tested and discussed above. Flexibility of each filament is enhanced, and stiffness reduced, providing more comfort during brushing. The increased surface area allows for superior plaque removal while the projections enhance the filaments' ability to grip and scoop away plaque effectively.

[0148] In the context of this disclosure, the term “substantially” refers to an arrangement of elements or features that, while in theory would be expected to exhibit exact correspondence or behavior, may, in practice embody something slightly less than exact. As such, the term denotes the degree by which a quantitative value, measurement or other related representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue.

[0149] The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as “40 mm” is intended to mean “about 40 mm.”

[0150] Every document cited herein, including any cross referenced or related patent or application and any patent application or patent to which this application claims priority or benefit thereof, is hereby incorporated herein by reference in its entirety unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it alone, or in any combination with any other reference or references, teaches, suggests or discloses any such invention. Further, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern.

[0151] While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.

Claims

1. A filament (20) for an oral care implement (10), the filament (20) having a longitudinal axis (22) and a multi-edged cross-sectional area (24) extending in a plane substantially perpendicular to the longitudinal axis (22), the multi-edged cross-sectional area (24) having at least 18 projections (26) and at least 18 grooves (28), the projections (26) and grooves (28) being arranged in an alternating manner,each projection (26) having a peak (30),a peak-to-peak distance (48) being measured from one peak (30) of a projection (26) to a neighboring peak (30) of another projection (26), andeach groove (26) having a bottom (32) with a concave curvature (34) formed by neighboring and converging projections (26), the concave curvature (34) having a radius (36), whereina ratio of the peak-to-peak distance (48) to the radius (36) of the curvature (34) of the groove (28) is from about 2 to about 4, preferably about 3.

2. A filament (20) according to claim 1, wherein the multi-edged cross-sectional area (24) has 20 projections and 20 grooves.

3. A filament (20) according to claim 1, wherein the radius (36) of each groove (28) is within a range from about 0.005 mm to about 0.03 mm.

4. A filament (20) according to claim 3, wherein the radius (36) of each groove (28) is within a range from about 0.01 mm to about 0.02 mm.

5. A filament (20) according to claim 1, wherein the distance (48) measured from one peak (30) of a projection (26) to a neighboring peak (30) of another projection (26) is within a range from about 0.01 mm to about 0.05 mm.

6. A filament (20) according to claim 5, wherein the distance (48) measured from one peak (30) of a projection (26) to a neighboring peak (30) of another projection (26) is within a range from about 0.02 mm to about 0.045 mm.

7. A filament (20) according to claim 1, wherein the filament (20) has an outer diameter (44) within a range from about 0.1016 mm (4 mil) to about 0.2286 mm (9 mil.

8. A filament (20) according to claim 1, wherein each groove (28) has a depth (38), the depth (38) being defined as a perpendicular distance measured from the bottom (32) of the groove (28) to a tangent (42) between two neighboring peaks (30), and the depth (38) of each groove (28) is within a range from about 0.002 mm to about 0.02 mm.

9. A filament (20) according to claim 1, wherein a ratio of a peak height (50), the height (50) being defined as a perpendicular distance measured from the peak (30) of the projection (26) to a tangent (52) between to neighboring bottoms (32), to the depth (38) of the groove (28) is from about 1 to about 2.

10. A filament (20) according to claim 1, wherein the filament (20) has a surface area to volume ratio from about 32 mm−1 to about 36 mm−1.

11. A filament (20) according to claim 1, wherein the filament (20) is made from polyamide (PA).

12. A tuft (16) for an oral care implement (10), the tuft comprising a plurality of filaments (20) according to claim 1.

13. A head (14) for an oral care implement (10), the head (14) comprising a tuft (16) of filaments (20) according to claim 12.

14. A head (14) according to claim 13, wherein a water uptake rate measured when the filaments (20) are exposed to water over 30 seconds is from about 0.3 g to about 0.5 g.

15. An oral care implement (10) comprising a head (14) according to claim 14.

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