Toothbrush having an inner cavity.

PATENT TITLE No. 350950

<td>Headlines):</td><td>THE PROCTER &amp; GAMBLE COMPANY</td>

<td>Address:</td><td>One Gillette Park, Boston, Massachusetts, 02127, USA</td>

<td>D nomination:</td><td>DENTAL BRUSH THAT HAS AN INTERNAL CAVITY.</td>

Classification: CIP: A46B9 / 04; A46B5 / 02

CPC: A46B9 / 04; A46B5 / 02

Inventor (s): CATHY WEN. MATTHEW LLOYD NEWMAN; ANDREAS BIRK; ANDREAS

BRESSELSCHMIDT: ANDREW JOSEPH HORTON. SIEGFRIED KURT MARTIN HUSTEDT; SCOTT JACKSON: JOCHEN KAWERAU: ULRICH PFEIFER; RICHARD DARREN SATTERFIELD; HEIDRUN ANNIKA SCHMELCHER: FRANZISKA SCHMID; JENS UWE STOERKEL: BENJAMIN JOHN WILSON: TILMANN WINKLER

<td></td><td>REQUEST</td>

<td>Number:</td><td>International Presentation Date:</td>

<td>MX / a / 2014/006105</td><td>November 21, 2012</td>

PRIORITY

Country: Date: Number:

US November 22, 2011 61 / 562,675

Validity: Twenty years

Expiration Date: November 21, 2032

Issue Date: September 26, 2017

The reference patent is granted based on articles 1^or, 2^or fraction V, 6th fraction III, and 59 of the Industrial Property Law.

In accordance with article 23 of the Industrial Property Law, this patent is valid for twenty years, non-extendable, counted from the date of filing the international application and will be subject to payment of the fee to keep the rights in force.

Whoever signs this title does so based on the provisions of articles 6® sections III and 7^or bis 2 of the Industrial Property Law (Official Gazette of the Federation (DO.F.) 06/27/1991. amended on 08/02/1994, 08/25/1996, 12/26/1999, 05/17/1999. 26 / 01/2004, 06/16/2005, 01/25/2006. 05/06/2009, 06/01/2010, 06/18/2010, 06/28/2010, 01/27/2012 and 04/09 / 2012); items 1^or, 3^or fraction V subsection a), 4th and 12th fractions I and III of the Regulations of the Mexican Institute of Industrial Property (DOF 12/14/1999, amended on 07/01/2002, 07/15/2004, 07/28 2004 and 7/09/2007), articles 1^or, 3^or, 4^or, 5^or Section V subsection a), 16 sections I and III and 30 of the Organic Statute of the Mexican Institute of Industrial Property (DOF 12/27/1999, amended on 10/10/2002, 07/29/2004, 08/04/2004 and 09/13/2007); 1®, 3^or and 5^or Subsection a) of the Agreement that delegates powers to the Deputy General Directors, Coordinator, Divisional Directors, Heads of Regional Offices. Divisional Deputy Directors, Departmental Coordinators and other subordinates of the Mexican Institute of Industrial Property. (DOF 12/15/1999, amended on 02/04/2000, 07/29/2004, 08/04/2004 and 09/13/2007).

This document is signed with an advanced electronic signature (FIEL), based on articles 7 BIS 2 of the Industrial Property Law; 3 of its Regulations, and 1 section III, 2 section V, 26 BIS and 26 TER of the Agreement establishing the guidelines for the use of the Payment and Electronic Services Portal (PASE) of the Mexican Institute of Industrial Property, in the procedures indicated.

THE DIVISIONAL DIRECTOR OF PATENTS

NAHANNY CANAL REYES

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MX / 2017/78571

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DENTAL BRUSH THAT HAS AN INTERNAL CAVITY * “..........

FIELD OF THE INVENTION

The present invention relates to toothbrushes having an internal cavity.

BACKGROUND OF THE INVENTION

Toothbrushes are typically manufactured using an injection molding process. Said injection molding process is characterized in that it provides a mold in the shape of the toothbrush and injects molten plastic through a hot runner nozzle into the mold. Afterwards, the toothbrush cools down and is ejected from the mold. For example, US Patent No. 5,845,358 shows a toothbrush made by injection molding. One of the limitations of conventional injection molding processes is that large diameter shanks and especially large shanks with substantial variation in cross-sectional area where the cross-sectional area both increases and decreases along the length or main axis of the brush, cannot be produced efficiently, due to the increased material cost and long cooling times that result from the increased masses of the material used.

Toothbrushes with increased shank diameters provide substantial advantages, for example, they can provide an increased grip area for children, which increases children's ability to manipulate and use toothbrushes; In addition, people with disabilities such

<img file="MX350950B_D0004.tif" />

^; * —Nrrmmni ·· ...... ................... '............. ...

Like arthritis, they sometimes have difficulty manipulating them due to the difficulty they have in flexing the joints in their hands. ............

Such difficulties are considerably alleviated by brushes having increased shank diameters. Additionally, handles with larger cross sections on toothbrushes are better for the user from an ergonomic point of view. Variations in cross-sectional area including smaller and larger cross-sectional areas along the length or main axis of the brush assist the user in grasping and manipulating the brush during use, when they must move, quickly , while it can also be wet and slippery.

In an attempt to overcome the difficulties associated with the use of injection molding to produce toothbrush handles that have increased diameters, it has been suggested to produce toothbrush handles that have a hollow body. For example, European patents no. EP 0 668 140 or EP 0 721 832 describe the use of air or gas assisted technology to manufacture toothbrushes having large cross section hollow handles. In the process described, the molten plastic is injected near the base of the toothbrush handle, where a hot needle is subsequently inserted into the molten plastic to blow gas into the molten plastic, which then expands towards the walls of the mold. injection. Similarly, US Patent No. 6,818,174 B2 suggests injecting a predetermined amount of molten plastic into the cavity to only partially fill the mold cavity and subsequently injecting a gas through a gas injection port formed in the injection mold to force the molten plastic to is in contact with the walls of the mold cavity. Patent No. CN102166064 describes a toothbrush having a hollow handle and a method for producing such a toothbrush. When molten plastic material is injected into the cavity of the toothbrush handle matrix, a blow hole is formed in

<img file="MX350950B_D0005.tif" />

the toothbrush handle, gas is blown into the center of the toothbrush handle through the blow hole, and the blow hole is sealed after forming the toothbrush handle. The toothbrush described in the present description has a hollow handle and a solid head made by a gas-assisted injection molding process. The hollow handle made by this method reduces the amount of material used by 10-50% compared to a solid toothbrush handle. Such injection molding processes that use additional air have substantial difficulty in forming hollow handle bodies of substantially uniform wall thickness, and thus the potential for optimizing a handle for maximum ergonomic function with minimum material weight is limited. . A further drawback for such injection molding processes is the creation of a vent hole for the gas. The vent hole is formed at the interface of molten plastic and high pressure gas (and not by molded steel) and therefore cannot be manufactured predictably or with high precision.

An additional drawback of hollow handle toothbrushes manufactured using gas assisted injection molding relates to the application or installation of a second, third or subsequent material to the toothbrush by injection molding, or overmolding, where the material overmolding can, in the process of sealing the necessary gas vent, substantially enter the hollow hole created in the first 3 gas injection stage, because there is nothing to stop it other than friction and pressure close to atmospheric pressure inside the hole. Finally, gas assisted injection molding does not substantially reduce the injection pressure or melt energy required to form a plastic article.

A conventional method of creating toothbrush handles that have increased cross sections, such as toothbrush handles • - ς&gt; · * ο /, '_.b?' '', and electromechanical, is to manufacture different parts of the handle separately by means of injection molding, then assembling these parts in a ^ lid ^ éparadande-meldecu-, without injection, or in a later stage of injection molding, through which parts other than the first stage or stages are inserted into an injection mold first and one or more materials are injected around them, creating a hollow multi-part body. This manufacturing method still has the drawbacks of: requiring the complete melting of plastic, high pressures and associated equipment involved with injection molding and may additionally have added labor costs associated with in-mold and out-of-the-box assembly. mold of molded parts differently. The use of injection molding to create multiple distinct parts has, furthermore, the disadvantage that each part must not contain any substantial undercut from which the core of the mold that forms a concave surface of the injection molded part cannot be removed. of the part after molding. Furthermore, the mold cores must typically contain some mechanism for cooling or removing heat, typically incorporated as an internal channel through which the chilled water passes, and therefore it would be difficult or impossible to elaborate an internal geometry for most manual toothbrushes which can have diameters of 10mm and lengths greater than 100mm. The absence of undercuts in distinct parts combined with the length and diameter of cores required to make handle parts without undercuts combined with the desire for multiple areas of variation in cross-sectional area in a toothbrush handle would require Therefore, any differently assembled handle that has multiple mating surfaces that would preferably require seals to keep barriers to moisture and debris under prolonged and repeated use.

Electromechanical toothbrushes are particularly susceptible to assembly problems, since they are necessarily hollow to include batteries, motors and associated electrical connections and acewr »mieftfortoó © 34e ^^ components must be placed inside with some degree of precision. To avoid the problems and expense of welding the plastic parts together and multi-stage assembly of a sealed outer sheet, it has been proposed to blow molding the handle for electromechanical toothbrushes. In assembling an electromechanical blow molded toothbrush it is necessary to leave the blow molded portion of the handle open at at least one end to accommodate the motor, batteries, and drive system components. In this process, the minimum diameter of at least one opening for the blow molded handle must be greater than the smallest linear dimension of each component to be inserted. A large opening could be a drawback on a non-electromechanical handle, which has no need to accommodate an internal component input, and would need an excessively large second part or cap to prevent intrusion or collection of water, paste, saliva, and other debris. conventional use. If this extremely large opening is located close to the head, it would substantially interfere with the ergonomic use of the brush. Additional restrictions to the geometry on the internal surface of the cavity, for example, to locate motors, housings, batteries, etc., which must be placed inside as precisely as possible to be rigidly fixed, will also be detrimental. for the general blow molding process, as most of the internal cavity surface of a blow molded part cannot be defined, directly, by steel on the mold surfaces and, instead, it is defined, indirectly, by steel on the outer surface of the handle combined with the wall thickness of the preform, blowing pressure, and stretch ratio of the end part to the original preform or preform thickness. Such restrictions on these process variables will necessarily limit the efficiencies of „« - -. : t · *.

manufacturing. '. .- / To accommodate the activation of the electrical components by means of a,_z t-wi _.............

standard button or mechanical switch, at least some portion of an electromechanical blow molded toothbrush must be made thin enough to flex substantially under pressure from a finger or compression from a hand. Said thin wall structure or film wall structure necessarily requires some reinforcing mechanism to ensure durability and rigidity during use. A frame or inner layer can be used, as described in patent application no. WO 2004/077996 to provide this necessary reinforcement mechanism in an electromechanical toothbrush, but it would be a drawback for a manual brush that does not require additional components to function properly, in additional expense, complexity and additional load bearing parts. Furthermore, due to the linear nature of the motor, power source, and drive shaft of electromechanical toothbrushes, there are no or minimal variations in the cross-sectional area of ​​the internal cavity; such that the walls of the internal cavity provide mechanical support to the internal components to reduce or eliminate unwanted movement or displacement.

An electromechanical toothbrush handle, manufactured by blow molding or injection molding, is typically manufactured with an opening at one end: at a distal end there is typically an opening to accommodate mechanical translation of energy through a drive mechanism to the toothbrush head, and at a proximal end there is typically an opening to accommodate insertion of components during manufacture and further possibly user insertion or removal of the battery. Such a second opening would be unnecessary for a manual toothbrush and would create inconvenience due to the

<img file="MX350950B_D0006.tif" />

need for additional seals and mechanical fasteners. In some blow molding processes, the formation of apertures at the proximal ends of the molded part is intrinsic to the process and would benefit the formation of a double aperture end handle, but would not be necessary for a double aperture handle. manual toothbrush.

There are several advantages to making lighter overall weight toothbrush handles, regardless of cross section or changes in size. Lighter handles could provide more tactile feedback of the forces transmitted from the teeth through the bristles to the brush head to the handle and to the brushing hand. Lighter toothbrush handles would also be shipped in volume more efficiently from manufacturing centers to retail centers where they are purchased by users. To reduce weight while maintaining rigidity, some toothbrush handles are made from bamboo or balsa wood; however, these materials have the disadvantage that they cannot be easily molded into complex three-dimensional shapes that can be comfortably gripped. Furthermore, these materials are anisotropic, which means that they have an elastic modulus and yield strength or ultimate strength that varies with the direction in which the load is applied. Carbon fiber composites and fiberglass injection molded plastics are other common examples of anisotropic materials that can be used to make lighter and stronger toothbrushes. Therefore, articles made from these materials must be formed with their strongest axis or 'grain' substantially aligned with the main axis of the article in order to resist fracture during commonly used bending forces. This creates an additional necessary step in the preparation of the material before forming or machining. This grain alignment can also present a ν .. í C .....

-. , Λ specific disadvantage for woods generally in the sense that the splintering of the material is more likely to occur in the direction of "more Forces" typical applied by the hand during planing.

To make toothbrushes and personal care items lighter without relying on anisotropic materials such as wood, the items can be made lighter through the use of inhomogeneous but isotropic materials, such as foamed plastics. Foamed plastics have an advantage in that they offer a higher strength-to-weight ratio than solid plastics regardless of material orientation. However, the total weight savings that are possible with foamed plastics may be limited, because the bubbles inside the plastic that create the weight savings also create stress concentrations that will severely reduce resistance. in tension. While foamed plastics can provide substantial compressive strength (and are used for exactly this purpose in applications such as packaging materials where weight is a critical issue) tensile weakness severely affects resistance to stress. flexing and prevents evenly foamed plastics from serving as load-bearing elements in articles that must maintain flexural strength and rigidity during normal use.

It is known to those of skill in the art to use extrusion blow molding to create lightweight portable items, such as children's toys, such as hollow plastic bats, golf clubs, or any large plastic item that benefits from having a lighter weight. While these articles can be both rigid and resistant to bending, they can also generally contain drawbacks that limit their general use in Class I semi-disposable medical devices, such as toothbrushes. First, such items typically contain / · 5 O rx¹ Ί '* ii. .

....... * -^98.-93=^(,1^¾^ * _{: 4} ; W JBf significant burr along parting lines, or anywhere the · ”· ** ____.

* · - »- s ™ -. ..

preform is larger in cross-sectional area than in the cavity to which it is blown. At these locations the preform folds into the cavity and a substantial flash is created, even in the absence of a cavity parting line. Second, most articles contain some significant trace of molding in the form of a hole, which can be formed accurately or inaccurately. Said trace would be considered a significant defect in a Class I medical device that must prevent the passage or entry of contaminants into a hollow interior that does not drain effectively. Third, the relative size of these items is large compared to the size of these defects, and the general function of the items is severely affected by these defects. In many cases, the size of the article itself facilitates the manufacturing process, with respect to minimizing defects. It is not difficult to extrude articles, containers or bottles into the common size range for manual cental brush handles if the plastic wall thickness can be minimized in proportion to the total cross section. Such items exist in the form of small, typically compressible tubes or bottles that actually benefit from having a very thin deformable wall that allows delivery of the internal content, rendering them useless as toothbrushes.

In addition, extrusion and injection blow molded handles are known for semi-disposable consumer items such as feather dusters and tape dispensers, but again these items would not meet the criteria for Class I semi-disposable medical devices, specifically with respect to sealing the Blow hole required against intrusion of water or other source of contamination, and in the case of extrusion blow molding, on the appearance of burrs on the articles in the areas that would be in direct contact or enter the mouth. These items are also generally very fragile.¹⁰ TV Λ F ~, and when a lot of force is applied they can break or split, producing sharp edges and making them unusable for use in the oral cavity. —--------------— ...............

It has also been proposed to manufacture manual toothbrushes by blow molding and, in fact, it should not be difficult to extrusion blow molding, injection blow molding or even injection stretch blow molding said article in the shape and size. general of a toothbrush or toothbrush handle; However, no description in the above material solves the problems of: flexural strength, stiffness during flexure, total stiffness, decreased burr or other acute defects, variations in cross-sectional area, and hole trace obstruction or sealing. blowing. Any of these defects in a blow molded toothbrush or toothbrush handle would severely affect the usefulness of the article and thus improvements are needed to allow a hollow article with material savings maximized by uniform wall thickness. be adequately resistant and rigid during bending without breaking during use and without leaks or defects that are uncomfortable for the user.

In view of these drawbacks in the prior art, it is an object of the present invention to provide an improved toothbrush having an internal cavity that avoids the drawbacks of the prior art.

BRIEF DESCRIPTION OF THE INVENTION

A toothbrush is provided comprising a head, a neck, a handle, a handle end, a head end, an external surface, an internal cavity, and a longitudinal axis; the internal cavity has a surface that defines a cross-sectional area; wherein the internal cavity has at least one area of

<img file="MX350950B_D0007.tif" />

• AJ n¡ I í S l * - ... '*' · '~ major cross-section, bounded by two smaller cross-sectional areas along the longitudinal axis of the toothbrush or by a cross-sectional area FIransveT ^^ bounded by two major cross-sectional areas along the longitudinal axis of the toothbrush. toothbrush; the outer surface defines a cross-sectional area of ​​the outer surface; a wall formed from the surface of the outer cavity and the surface of the inner cavity; wherein the toothbrush comprises a single unitary component along the entire length.

A toothbrush is provided comprising a head, a neck, a handle, a handle end, a head end, an external surface, an internal cavity, and a longitudinal axis; the internal cavity has a surface that defines a cross-sectional area; wherein the internal cavity has at least one larger cross-sectional area, bounded by two smaller cross-sectional areas along the longitudinal axis of the toothbrush or a smaller cross-sectional area bounded by two larger cross-sectional areas along the longitudinal axis of the toothbrush; the outer surface defines a cross-sectional area of ​​the outer surface; a wall formed from the surface of the outer cavity and the surface of the inner cavity; the toothbrush comprises a single unitary component; wherein the toothbrush comprises two or more layers of material.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 is a perspective view of a toothbrush in accordance with one embodiment of the present invention.

Figure 1A is a cross-sectional view of Figure 1 along section line 1A in accordance with one embodiment of the present invention.

' ,

Figure 1B is a cross-sectional view of Figure 1 along section line 1B in accordance with one embodiment of the present TéW &amp; Tf ^

Figure 2 is a perspective view of a toothbrush in accordance with one embodiment of the present invention.

Figure 3 is a representation of a cross-sectional view of a unitary toothbrush with an internal cavity.

Figure 4 is a table showing the variation in wall thickness of two toothbrushes having an internal cavity along the longitudinal axis.

Figure 5A is a table showing the variation of the mean, minimum and maximum wall thickness of any 2mm section of the toothbrush along the longitudinal axis of an embodiment with a thick handle.

Figure 5B is a table showing the minimum and maximum wall thickness percentage of the mean wall thickness of any 2mm section of the cental brush along the longitudinal axis of an embodiment with a thick handle.

Figure 6A is a table showing the variation of the mean, minimum and maximum wall thickness of any 2mm section of the toothbrush along the longitudinal axis of another embodiment with a thin handle.

Figure 6B is a table showing a minimum and maximum wall thickness percentage of the mean wall thickness of any 2mm section of the toothbrush along the longitudinal axis of another embodiment with a thin handle.

Figure 7 is a diagrammatic representation of an analysis method.

Figure 8 is a diagrammatic representation of an analysis method.

Figure 9 is a table illustrating the deflection in bending compared to specific gravity.

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DETAILED DESCRIPTION OF THE INVENTION

-IIÍHU »! W .-. I. .......—,. . „.

The present invention relates to personal care items having an internal cavity, such as a hollow toothbrush that may have different colors, materials, and surface decorations on one or both of the internal cavity or the external surface. The internal cavity varies in cross-sectional area along the length or longitudinal axis of the toothbrush, wherein the internal cavity is essentially open compared to an open or closed cell foam material. The unitary toothbrush is made of at least one continuous material that extends along the entire longitudinal axis of the toothbrush such that the head, neck and handle of the unitary toothbrush is essentially one part. This or more continuous material provides the structural length of the toothbrush. The unitary toothbrush can include separate non-structural elements, such as tags, grippers, bristles, etc. In certain embodiments the internal cavity is closed 15 with no opening towards the external surface of the toothbrush.

Personal care items are items used to store, dispense, apply, or deliver benefits for the health, beauty, consumer grooming, or other human body or biological system care, maintenance, or enhancement. Examples of personal care items include, but are not limited to toothbrushes, toothbrush handles, razors, razor handles, mop handles, vacuum cleaner handles, makeup or beauty care applicators, skin care applicators, feminine hygiene applicators, hair care applicators, hair color applicators, or hair care items.

Figure 1 shows one embodiment of a personal care item, i: .. '. , a toothbrush 10 having a head 20, neck 30, handle 40, a handle end .......

and a head end 22. The toothbrush 10 may be formed as a single piece and comprise an internal cavity 60 and an external surface 12, wherein the external surface 12 varies in cross-sectional area (OS_Ca), which is the total cross-sectional area as defined by the outer surface 12, along the longitudinal axis L of the toothbrush 10, as shown in Figure 1A; In this embodiment the handle 40 has a substantially hourglass shape. The internal cavity 60 has an internal cavity surface 62, wherein the internal cavity surface 62 varies in cross-sectional area (IC_AC) along the longitudinal axis L of the toothbrush. As shown in Figure 1, in certain embodiments the internal cavity of the toothbrush 10 has a larger cross-sectional area ICcag delimited along the longitudinal axis L of the toothbrush 10 by the cross-sectional areas IC_Cai&gt; IC_ACtwo having an area smaller than the largest cross-sectional area ICcag, to form a contour. An internal cavity 60 of toothbrush 10 may also have a smaller cross-sectional area IC_Cdelimited along the longitudinal axis L of the toothbrush 10 by the cross-sectional areas IC_CA3, ICcaa having an area greater than the minor cross-sectional area ICcal, to form a contour. In another embodiment, the cross-sectional area at the end of the brush handle is smaller than at least one or more of the other cross-sectional areas along the longitudinal axis L of the toothbrush 10. Furthermore, as shown in Figures 1, 1A and 1B, in certain embodiments the internal cavity surface 62 varies by the square root of the cross-sectional area (ICca) proportionally to the variations of the square root of the cross-sectional area ( YOU_Ca) of the external surface 12 along the longitudinal axis L of the toothbrush 10. In another embodiment, the cross-sectional area of ​​the wall of the toothbrush (thermoplastic material that forms the τ A &lt;η? - -

J Μ F «&lt;Ν ----- _Λ ' . ... .

toothbrush that is located between the surface of the internal cavity and the external surface of the toothbrush), which is the difference between the external cross-sectional area-sttpeff ^ - (os_Ca) and the internal cavity surface cross-sectional area (ICca) varies less than about 25%, 20%, 15%, 10%, 5% over at least%, 70%, 80%, 90% of the length of the internal cavity along the longitudinal axis of the toothbrush. This is the case when the thickness of the toothbrush wall in the inner cavity portion varies inversely with the average perimeter of the outer surface and the inner cavity along the longitudinal axis L of the toothbrush. In another embodiment, the thickness of the toothbrush wall in the inner cavity portion remains substantially constant along the longitudinal axis of the toothbrush. As shown in Figure 1, the head 20 and at least a portion of the neck 30 along the longitudinal axis L of the toothbrush 10 can be substantially solid or as shown in Figure 2 in a toothbrush 100 the internal cavity 160 may extend from handle 140 to neck 130 but does not pass first tuft hole 132 closer to handle end 142 of toothbrush 100. In certain embodiments, the percentage of void volume of air to the volume of the brush handle and neck ranges from about 50% to about 70%; or from about 55% to about 70%; This means that the same percentage of material is saved compared to a solid toothbrush of the same shape and size. In these embodiments, the amount of thermoplastic material can be reduced from 50% to 70% compared to the amount used in solid toothbrushes that have the same shape and size. A gas assisted injection molded hollow freezer door handle is documented to save a maximum of 27% material compared to a solid freezer door handle of the same shape and size. Virtually any gas-assisted injection molded toothbrush can save a maximum of 30% material compared to a solid 4a '' same shape and size toothbrush. —— ------—----—

A hollow toothbrush with a wide handle and internal cavity actually has a very high flexural strength-to-volume ratio. The thinner the wall thickness compared to the mean radius^r at any cross section, the ratio of structural strength to volume will be greater. Where the mean radius is defined as the mean perimeter of the hollow cross section divided by 2^π. The mean perimeter of the hollow cross section is defined as the average of the perimeter of the external surface and the internal cavity in that cross section. By simplifying an internal cavity toothbrush as a hollow cylindrical beam under flexural conditions as illustrated in Figure 3. It can be shown that the ratio of flexural strength to volume V of an internal cavity toothbrush varies positively with the ratio of mean radius ra thickness t. The higher the t ratio, the higher

Kb relation of v. A similar relationship will follow for a contoured, internal cavity non-cylindrical toothbrush. Therefore, the internal cavity unit toothbrush of the present invention has a ratio of mean radius to thickness t in the range of 3 to 10 in at least about 80% of the hollow portion along the longitudinal axis. In the transition from the hollow portion of the toothbrush to its solid portion, the wall thickness tends to increase and is excluded from the wall thickness measurement. On the other hand, the ratio of mean radius to thickness * of a solid cylindrical beam is Va. Whereas the ratio * of some other hollow handles of an existing toothbrush in the above matter such as gas assisted injection molded toothbrushes can be 0.7 to 2.

The toothbrush must also be rigid enough to resist

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a compressive force exerted by consumers. The radial stress of a hollow toothbrush under compression force or compression pressure is, furthermore, r directly proportional to t. By testing physical samples of hollow internal cavity toothbrushes it is found that as long as the toothbrush is thick enough and is less than 8 or even less than 10, the radial deformation under normal compression force will not be noticeable by the teeth. consumers.

Whereas the thickness variation of other hollow handles of a personal care item, such as a toothbrush of the above material, such as gas assisted injection molded toothbrushes will have significant wall thickness variation throughout. of the circumferential direction of a cross section, particularly at any sharp corner of the cross section. For example, in a gas assisted injection molded handle, the thickness ranges from 1.9mm to 4.3mm across a cross section. The cross section of the outer surface of the handle has an irregular shape with sharp corners. The internal cavity of the handle cannot follow the shape of the external surface. At the sharp corner, the thickness changes, abruptly, from 1.9mm to 4.3mm, which is an abrupt change from 2.4mm. This abrupt change in thickness would not occur in the internal cavity toothbrush of the present invention. Average thickness is about 3.1mm in cross section. The mean radius of the hollow cross section is 2.35 mm. The ratio of mean radius to thickness t is 0.76 which is much less than 3.

Now let's look at the distribution of the mean wall thickness of any cross section in the hollow portion along the longitudinal axis of the toothbrush.

In the anterior form of the hollow thin-handled toothbrush, the mean wall thickness in any cross section of a single toothbrush in

<img file="MX350950B_D0010.tif" />

% of the hollow portion along the longitudinal axis has a range of 0.9 to 1.2 mm, with a mean thickness of 1.07 mm. The wall thickness varies less than 15% from its mean wall thickness in 80% of the hollow portion along the longitudinal axis. The ratio of mean radius to thickness f ranges from 3.9 to 8.4 in 80% of the hollow portion along the longitudinal axis. This is a single toothbrush with a slim handle. The mean wall thickness of any cross section of the thin shank internal cavity unit toothbrush is furthermore a continuous function along the longitudinal axis of the toothbrush. This means that the change in mean wall thickness of any cross section from one cross section to the other is less than 0.5 mm, as shown in Figure 4.

In another embodiment, the wall thickness of a unitary toothbrush in 80% of the hollow portion along the longitudinal axis has a range of 1.55 to 2.07 mm, with an average thickness of 1.76 mm. The wall thickness varies less than 17% from its mean wall thickness in 83% of the hollow portion along the longitudinal axis. The ratio of mean radius T to thickness t ranges from 3 to 4.7 in 80% of the hollow portion along the longitudinal axis. This is a single toothbrush with a thick handle. The change in mean wall thickness of any cross section from one cross section to the other is less than 0.5 mm, as shown in Figure 4.

In the above two embodiments of internal cavity unit toothbrushes, the toothbrushes have the structure and flexural strength required by consumers to brush their teeth effectively.

The wall thickness can vary along the longitudinal axis of the toothbrush by controlling the thickness profile of the preform in an extrusion blow molding process. There are three modes that are convenient:

τ '* r τ * τ

I Μ. α I

In one embodiment, the cross-sectional area pefffláükóOonWMe? '' '' In 80% of the hollow portion along the longitudinal axis of the toothbrush. In ..... this .________ mode, the wall thickness varies inversely with the mean radius of the toothbrush along the longitudinal axis.

In one embodiment, it is desirable that the average thickness of the toothbrush remains constant over 80% of the hollow portion along the longitudinal axis of the toothbrush. In this embodiment, the cross-sectional area of ​​the toothbrush will vary proportionally to the mean radius of the toothbrush along the longitudinal axis.

In still another embodiment, it is desirable that the mean thickness varies proportionally to the mean radius of the toothbrush along the longitudinal axis, that is, * remains constant and can be any value from 3 to 10. In this mode, the section area The cross section of the toothbrush will vary proportionally to the square of the mean radius of the toothbrush along the longitudinal axis. The benefit of this modality is that the toothbrush remains constant in flexural strength and stiffness along the longitudinal axis.

Referring again to Figure 1, the handle 40 is connected to the head 20 through a neck 30, which, compared to the handle 40, or the head 20 has a smaller cross-sectional area. As illustrated in Figure 1, the head 20 of the toothbrush 10 supports a plurality of cleaning elements, such as bristles or tufts of bristles. The bristles or tufts of bristles can comprise nylon, PBT, and TPE.

In addition to bristles or tufts of bristles, the toothbrushes of the present invention may include any suitable cleaning element that can be inserted into the oral cavity. Some suitable cleaning supplies' · '' “, *. . ...... ..

«·,. '' ,, '&gt; ί include elastomeric massage elements, elastomeric cleaning elements,' massage elements, tongue cleaners, soft tissue cleaners, hard surface elements, combinations thereof, and the like. The head can comprise a variety of cleaning elements. For example, the head may comprise bristles, abrasive elastomeric elements, elastomeric elements in a particular orientation or arrangement, for example pivoting fins, dental prophy cups, or the like. Some suitable examples of elastomeric cleansing and / or massage elements are described in US Patent Application Publication Nos. 2007/0251040; 2004/0154112; 2006/0272112; and in US Patent Nos. 6,553,604; 6,151,745. The cleaning elements can be tapered, notched, wavy, dimpled, or the like. Some suitable examples of these cleansing elements and / or massaging elements are described in US Patent Nos. 6,151,745; 6,058,541; 5,268,005; 5,313,909;

4,802,255; 6,018,840; 5,836,769; 5,722,106; 6,475,553; and US Patent Application Publication No. 2006/0080794. In addition, the cleaning elements can be arranged in any suitable way or pattern on the toothbrush head.

In certain embodiments of the present invention, a personal care item, such as a toothbrush, can be made of more than one material or layer. In certain embodiments, a toothbrush may comprise a primary component or layer that forms the majority of the toothbrush and a secondary layer that forms the least of the toothbrush, wherein the second layer, in certain embodiments, may have a thickness less than about 0.4mm and greater than about 1cm² in area. In particular, a multi-component extrusion process can be used, wherein the different portions of the personal care article are formed of different materials. For example, on a brush

<img file="MX350950B_D0011.tif" />

dental, the portions of the contact surface that come into contact with the thumb or fingertips can be made of soft plastic, so that they feel soft or easy to hold, while the remaining portions of the toothbrush can be made of hard plastic to give the toothbrush sufficient rigidity. In one embodiment, the soft plastic should not be slippery or have a high coefficient of friction when wet, so that when teeth are brushed and the handle becomes wet, the user can easily grasp it without losing control of the brush handle. Plastic elastomer (TPE) can be used for soft plastic. In another embodiment, the head and neck portion of a toothbrush may have two layers where the outer layer is a soft plastic that provides softness and the inner layer is a hard plastic to provide rigidity and support to the tufts. In yet another embodiment, part or a strip of the toothbrush parallel to the longitudinal axis of the toothbrush may have two layers of material, wherein the outer layer has a different color than the rest of the toothbrush. In still another embodiment of the toothbrush, one part of the toothbrush, for example the neck, may have two layers of different materials, while other parts of the toothbrush, such as the handle, have only one layer of the material; which creates a different color grip, feel or decoration on different parts of the toothbrushes. The two layers can be manufactured by supplying a multi-layer preform into the mold. By controlling the presence of a second layer in the preform in both the longitudinal direction and the circumferential direction, the presence of the second layer in the toothbrush can be controlled in both the longitudinal direction and the circumferential direction. In certain embodiments, a separate part can be inserted at one position in the mold, and can be held in place on one side of the wall of the mold cavity either by vacuum suction or by the natural dimensional curvature of the mold. One or more separate parts can be further inserted into the mold and attached to the wall of the mold cavity in the same way. These parts joined in the mold can be made of different material with different colors or surface texture or 3D texture . In certain embodiments, this part may be a thin TPE film label of different color or thickness that provides color differentiation as well as a soft, wet grip. In certain embodiments, it may be a small electronic part that colors a timer and display to indicate a predetermined brushing time. In certain embodiments, it can be a small electronic part that plays a sound or musical melody for two minutes. In still more embodiments, it can be made of a color-changing material that changes with pressure, temperature, humidity, or time. In yet another embodiment, it can be a 3D textured textile or openwork made of TPE or ethylene vinyl acetate (EVA) that provide additional decoration to the toothbrush.

In certain embodiments, a toothbrush having an internal cavity may have a center of gravity closer to the head than to the geometric center of the external surface of the toothbrush than is normally possible with a conventionally shaped solid toothbrush. which can provide improved dexterity or ergonomics while brushing, or the center of gravity can be positioned further from the head than is possible with a solid homogeneous brush, for example, by placing permanently mounted weights within the hollow portion of the handle, which can provide, for example, an improved tactile response of the forces transmitted from the teeth to the head to the handle. Such manipulation of the center of gravity can provide additional benefits in handling during planing or storage without compromising design elements such as - »üja.» »Ι | - '

VA Τ '. »'-Λ *; , TO^} । . i · * '·.' • i í V · t. ..

,) M ' ¹ 'v /

H, PM '-.

K, L. * 'shape, material or color that appears on the outside of the handle. Additionally, in certain embodiments, a toothbrush that has a cavity may have an equivalent density of less than 0.60 g / cm³, or less than 0.20 g / cm³ in plastic or C. 10 g / cm³ in metal while maintaining sufficient modulus or strength to resist flexing even during heavy brushing regardless of the particular alignment or arrangement of any raw material or load-bearing element (as opposed to materials that have a grain, such as wood or carbon fibers) which is difficult to achieve in a toothbrush whose handle is substantially solid and is manufactured from common homogeneous and isotropic materials such as plastic or metal. An equivalent density is defined as the ratio of the entire total mass to the total volume defined by the outer surface of the toothbrush. In certain embodiments, the equivalent density of the internal cavity toothbrush is from about 0.2 g / cc to about 0.5 g / cc. In certain embodiments, the handle of both brushes does not deform when compressed with the fingers.

The toothbrush material can be any thermoplastic resin that has one or more properties suitable for a hollow toothbrush, such as flow properties that allow blow molding, chemical resistance, and sufficient impact resistance. Examples of typical materials include but are not limited to impact modified polypropylene or high density polyethylene (HDPE). Examples of the materials used for the outer layers can be a TPE material with different hardness. The toothbrush may further have a secondary decorative material such as a thin TPE layer on a small part of the toothbrush such as the thumb rest or thumb grip area. In certain embodiments when a toothbrush is formed through the use of extrusion blow molding, due to²⁴ ... .

_FK · 'the large tension of the semi-cast preform in the compression mold δη the portion. Of the brush head to form the large number of small tuft holes j&gt; rofurido.§_ tightly compacted, The primary base thermoplastic resin that is supplied in the blow molding machine in a pellet form can have a melt flow index (MFI) in a range from about 1 g / 10 min to about 4 g / 10 min at 230 ° C and 2.16 kg of force measured with ASTM D1238 standard test method. The MFI should not be very small, for example &lt;1 g / 10 min, because a resin with &lt;1 g / 10 min MFI forms a preform that is too viscous to flow freely to fill the deep and narrow gap between the holes of plume with great tension. The temperature of the preform can be increased to reduce the viscosity to some degree. The normal temperature range for an extrusion blow molding process is 176-232 ° C. If the temperature is set too high, it can burn the resin and result in inconsistent property of the molten resin. For example, for a polypropylene (PP) resin with an MFI of 0.37 and 0.47 flow, the temperature has to be set above 246 ° C to form a toothbrush with tuft holes, but the quality of the part is poor. and very inconsistent. However, when the MFI is very high, for example when the MFI of the resin is greater than 3 g / 10 min, the preform becomes too loose and cannot support itself and may collapse before it is held in place. mold. Lowering the temperature of the preform can reduce the viscosity of the preform to support itself, but lowering the temperature can make the performance of the preform very inconsistent from one feed to the next. To form a preform that can be used to form a unitary toothbrush, in certain embodiments, the temperature is from about 199 ° C to about 221 ° C and the MFI is from about 1.5 to about 2.5 MFI. The MFI of the dye is also important. Although the mixing ratio (percentage of the colorant by weight that is mixed γ * 5 Τ »I r - '« · «- ~ / i ** in the base thermoplastic resin) of the colorant is usually about 2 to

5%, but at 30 MFI compared to 15 MFI, the viscosity - ^ 4a-pfeformandedasndü?

Colored resins can have significantly different performance.

The unitary toothbrushes of the present invention having an internal cavity can help reduce the amount of excessive force that is applied to the toothbrush during brushing, such as when using a typical solid manual toothbrush or an electromechanical toothbrush. It is known to those of skill in the art that sustained, repeated brushing with a standard bristle manual toothbrush with a force greater than approximately 5.0 N can cause gum tissue loss over time. For example, there are electromechanical toothbrushes with built-in feedback systems to warn users when this force is exceeded during use. This suggests that a significant fraction of toothbrush users apply forces of up to 5.0 N across the toothbrush head. An illustrative uniform, rectangular cross-sectional toothbrush made of a solid, homogeneous, isotropic material can be shaped into the grip as shown in Figure 7. The deviation of the toothbrush head in this grip during flexion during use can be inferred, analytically, from the equation used to calculate the flexural modulus of a flat bar of material in a three-point flexion as shown in Figure 8. , and as described in ASTM D 790.

The materials used to form a unitary toothbrush of the present invention having an internal cavity (hollow toothbrushes) should provide flexural strength, or stiffness, when a normal load is applied to the longitudinal axis. Toothbrush materials that do not meet this criteria bend severely during normal use, resulting in a negative experience or providing insufficient force to properly clean teeth. For • Μ »·» »··» ⁷»·· *** ι · * · w ··. «»,. »♦&gt;⁷ ~ . - ,- .- .

Evaluating candidate materials for constructing a toothbrush in as lightweight a modality as possible, the present description defines,., a, lation-for .la. flexural strength of the handle at its full specific gravity as a measured deflection under specific load described in Figure 8. The table in Figure 9 illustrates this relationship applied to a simple rectangular beam approach of solid handles made of homogeneous and isotropic materials; handles made of non-isotropic, composite or non-homogeneous materials; and hollow handles made of other homogeneous and isotropic materials. The results in the table are obtained from the analytical bending equation for the apparatus in Figure 8 or from the predicted bending in a finite element analysis of materials not analytically soluble, such as anisotropic materials. It is clear from this table that solid shanks made of homogeneous and isotropic materials cannot achieve a flexural strength-to-weight ratio that can be achieved with hollow, homogeneous, isotropic, engineered shanks.

Not all hollow articles have sufficient flexural strength to withstand 5 N of force applied in flexion normal to the main axis at a typical distance such as that applied to a toothbrush between the balance point of the thumb and the brush head. Definitely, not all blow molded articles can withstand such forces: many blow molded containers such as water bottles must be filled before being stacked on pallets because their walls are thin enough to deform significantly under compression even under high pressure. weight of a few empty bottles on top of them. It is possible to make toothbrushes in a similar way, by using generally weak materials or by making extremely thin walls, such that they appear strong, possibly due to the use of opaque materials or other decoration. The toothbrushes made of a »·. «A - '» · * · - · 0 »· these handles would not collapse under the influence of gravity or gentle forces, and might appear sturdy during packaging or on display, but in reahdacT would be unpleasant or impossible to use as intended, or to release sufficient brushing force to maintain oral health. Generally, brushes that deform more than 20 mm under an applied force of 5.0 N as determined by ASTM D 790 would not be desirable in use. In certain embodiments, the unitary toothbrush of the present invention deforms less than about 20 mm under an applied force of 5.0 N as determined by ASTM D 790. In certain embodiments, the unitary toothbrush of the present invention deforms less than about 10 mm under an applied force of 5.0 N as determined by ASTM D 790.

From this table it appears that inhomogeneous and isotropic materials are also candidates for lightweight toothbrushes. However, these materials are inherently brittle as a result of stress concentrations due to bubbles that result from the foaming process. As described above, the table illustrates only the predicted or theoretical deflection under load and does not take into account the ultimate strength of the materials. Toothbrushes made from the foams shown would fracture on the surface under stress while flexing under loads less than those used during typical brushing.

Generally, a hollow toothbrush with a wall thickness ^on virtually uniform provides desired flexural strength with minimal material usage by selectively placing the material at the outermost diameter, or farthest from the flex axis, where it can withstand the maximum bending moment with minimal resistance necessary. This selective material placement naturally reduces the normal stress applied to the material elements, caused by the bending moments and results in less stress per material element per unit of applied normal force or bending moment than if the handle is manufactured solid material or has material placed primarily on the neutral axis. An I-beam is a common example of selective placement of material as far as possible from a neutral axis. However, an I-beam resists bending very differently when flexed around different axes. A hollow part that is substantially round in cross section, such as a hollow toothbrush, will provide adequate flexural strength around a variety of axes, which is necessary for a personal care item such as a toothbrush that is held by hand and is used regularly in many different orientations and must withstand loads around almost any axis of flexion.

However, not all toothbrush designs provide sufficient flexural strength, as defined by the deflection ratio to specific gravity described above. Instead, it is easier to manufacture an extrusion molded toothbrush with a very thin flexible wall than it is to manufacture a toothbrush so that its wall is thick enough to provide adequate flexural strength. For all extrusion molded articles, there is an upper limit on wall thickness that can be created without creating significant creases or flash lines on the outer surface of the article. This upper limit is governed by the smallest outer circumference of the portion of the article to be hollowed out, the initial thickness of the extrudate prior to blowing, and the ratio of the initial circumference of the blown section to the final circumference of the blown section. . As the wall thickness of the starting material increases, a larger fraction of it can become trapped between the surfaces of the mold that are intended to mate, thereby creating a flat section around all or a portion of the molded article, commonly known as a burr. A hollow toothbrush with small amounts of burr would be unpleasant to use, especially if the burr becomes or feels sharp to the touch, even if it is very

<img file="MX350950B_D0012.tif" />

small. ....................................

The elasticity and strength of materials are also a factor in flexural strength: for example, a blow molded toothbrush that is stiff enough and is made of a relatively strong material, such as

PET-G, can be too weak to be considered useful in the same geometry and wall thickness of LDPE or polypropylene. Even between LDPE and polypropylene, a polypropylene toothbrush can be sufficiently stronger than an LDPE toothbrush and be perceived as stiffer by a user.

In certain embodiments of the invention, a polypropylene toothbrush whose length is between 100 mm and 2000 mm, and has a weight between 7.0 g and 13.0 g with material substantially uniformly distributed around the wall of the hollow portion, has a gravity total specific less than 0.5 g / cm³.

In addition to flexural strength, rigidity, and convenience in manufacture, a hollow toothbrush is advantageous because it allows the empty internal volume to be used to accommodate some useful or decorative item. Such elements can include elements common to assembled hollow brushes such as primary electronic systems, electromechanical systems, primary mechanical systems, and decorative elements.

) Electronic elements, such as batteries, timers, alarms, transducers, accelerometers, lights, speakers, amplifiers, resistors, capacitors, coils, transistors, circuits, circuit boards, printed electronic elements, electronic ink and substrates, solder alloy, Cables and similar components can be pre-assembled into working or partially functioning systems and installed in the empty area on a hollow toothbrush. These * . »,« ·

... '.. · systems may make particular use of undercuts in the hollow portion of the toothbrush, for example by virtue of placement or position against^-^ near ^ a 'coffe · skewed to provide restriction on movement. These systems can also take advantage of an inner layer of a multilayer system to provide electrical insulation or conductivity or semiconductivity between elements integrated into the system, or elements outside the toothbrush cavity. An example of this would be an inductive charging system that captures energy from an external electric field by positioning and activating coils of wire placed inside the handle. This is a common method by which electric toothbrushes recharge when not in use. Specific modalities for these systems and elements include, but are not limited to ε: a timer to provide feedback to a user during tooth brushing, a force sensor to discourage excessive use of force during brushing, an indicator element that informs the user when the lifespan of a toothbrush is reached, lights or sounds that play a song or game during brushing, use of the geometric properties of the hollow void to resonate or attenuate certain sounds generated inside, an electrostatic generator to charge the system with a high or low potential voltage, creating an electronic pet ”or tamagotchi, which will thrive if good brushing habits are maintained and will suffer or die if good brushing habits are not maintained, and Similary.

Electromechanical systems, such as rotary motors, linear motors, direct current permanent magnet motors, piezoelectric transducers, buttons, toggle switches, temporary switches, magnets, reed switches can be used, independently, or more likely in combination with electrical elements. and systems to provide additional benefits and feedback to users Examples include but are not limited to: The use of

<td></td><td>³¹ I Μ ΡI; a motor to create a tactile vibration feedback, the uéV^TO®yes ^ ' piezoelectric or inductive electrical systems to capture eneajiaj »ecáji¡ £ a.yxQ ^ in electrical energy during brushing, the use of switches to activate and deactivate electrical or electromechanical systems, the use of magnets as elements in systems</td>

<td> 5</td><td>inductive or to provide sensing to an external electrical system, the use of strain gauges to measure and feedback, or the use of vibration inducing motors or weight compensated motors to create a pleasant tactile sensation at any point on the brush. For the use of mechanical switches, it can additionally provide an advantage to selectively thin the brush wall</td>

<td> 10</td><td>dental in some areas but not all for the purpose of creating a deformable region that can allow deflection through the solid wall of an internally mounted switch without creating a hole that must be sealed in an additional stage. Primary mechanical systems, such as solids, liquids, gases, colloids, magnets, living or organic elements, phase change elements or elements</td>

<td> 15</td><td>Chemical transition elements, color change elements, thermochromic elements, and the like can be installed within the internal cavity of a unitary toothbrush, either permanently or with the intention of later supply, for consumption. Examples of filling items that can be consumed include, but are not limited to: Toothpaste, mouthwash, whitening agents, breath fresheners. Examples of solids include, but are not limited to: articles molded and designed to add weight to a device, such as iron, zinc, or other metals in solid form; Silica, or other granular material, in a single color or multiple colors. Articles made of liquids may include, but are not limited to: water, oils, gels or combinations thereof, including emulsions, mixtures, solutions and combinations of those mentioned above, the</td>

<td> 25</td><td>which can be easily separated, such as oil and water. The magnets placed in</td>

.w ~

'..·.’ · .&gt;

A device can add storage or connection / interaction advantages to ferrous materials or items, for example cabinet accessoriesrt) Tefrigéfáddr or doors of household devices. The magnets can also be positioned internally so that they interact with the magnets outside the toothbrush to hold the toothbrush upright on one end to prevent the head from contacting any surface in the bathroom or storage area. Phase change or color change elements or systems set to temperatures slightly lower than the human body can be included in a hollow toothbrush with transparent outer layers, for example, to create a non-electric timer, which would allow the Toothbrush changes color after holding it in your hand long enough.

In addition to the installed elements and an advantage of an internal cavity unit toothbrush is the ability to decorate a translucent or transparent toothbrush on an internal surface that is isolated from contact with the user by the toothbrush body. In these embodiments, there would be an advantage in isolating the decorative layer from human contact, for example to create a delay in the temperature rise of the insulated layer, that is, for thermochromic paint that can change color after approximately some time. settled down. Furthermore, a reduction in the appearance of wear would be advantageous, as opposed to surfaces that are painted or etched on the outer surface and are subject to mechanical wear or chemical attack.

Examples

Example 1:

, '' ^ Cm *. Υ i ί. ,,,. ...

Table 1 shows that the toothbrush walls of^lthe invention pw having an internal cavity have a deviation rnlfflrtm? rrt »t · ^^ of the length of a toothbrush: where (1) the wall thickness of the hollow portion of the unitary toothbrush is determined by the distance shorter between the outer surface of the toothbrush and the surface of the inner cavity at the point of measurement; (2) the average wall thickness is the average of the entire thickness measured along the circumferential direction of the cross section at the chosen point; (3) the average wall thickness to the toothbrush in the inner cavity portion is the average of the thickness of each cross section; (4) the percentage of air void.

Table 1

<td></td><td>Sample 1</td><td>Sample 2</td><td>Sample 3</td>

<td>Average wall thickness (mm)</td><td> 1.0</td><td> 1.8</td><td> 1.4</td>

<td>Maximum thickness (mm)</td><td> 2.4</td><td> 3.4</td><td> 2.6</td>

<td>Minimum wall thickness (mm)</td><td> 0.60</td><td> 0.9</td><td> 0.3</td>

<td>Standard wall thickness (mm)</td><td> 0.2</td><td> 0.4</td><td> 0.2</td>

<td>Standard / Average (mm)</td><td> 25.3 %</td><td> 23.9 %</td><td> 13.8 %</td>

<td>Air void percentage</td><td> 66 %</td><td> 44.6 %</td><td> 61.5 %</td>

As shown in Sample 1, the wall thickness of the hollow portion of the unitary toothbrush can be distributed, evenly, and can be as thin as about 0.6 mm, with an average wall thickness of the hollow portion of the toothbrush of 1.0 mm and a standard deviation in wall thickness of about 0.25mm, which is only about 25.3% of the average thickness, illustrating only a minor deviation in wall thickness. Sample 2 shows that the wall thickness of the hollow portion ranges from about 1.8 to about 3.4mm, with a standard deviation of the wall thickness of about 44mm, which is only about 23.4% of the average thickness of 1.8mm. Sample 3 shows that the wall thickness of the hollow portion ranges from 0.3 mm to 2.6 mm, with a standard deviation of 0.2 mm, which is only about 13.8% of the average thickness of 1.4. The results mentioned above show that the walls of the toothbrush of the present invention have minimal deviation in thickness along the length of the toothbrush.

Example 2:

To determine whether the unitary toothbrush of the present invention with an internal cavity has a uniform wall thickness along the circumferential direction of each cross section, a toothbrush sample was first micro-scanned, and then approximately 1000 wall thickness measurements within each 2mm length section in 80% of the hollow portion along the longitudinal axis of the micro-CT scan and the statistics are calculated. The mean thickness in each 2 mm section of the toothbrush was further calculated along the longitudinal axis of the toothbrush. Internal cavity toothbrush samples have significant undercut and contour. The cross section of the internal cavity toothbrush is not circular but has a rounded triangular shape. The wall thickness of the toothbrush along the longitudinal or axial direction is more than one^#continuous anointing. The curvature and shape of the internal cavity can follow the curvature and shape of the external surface in any cross section of the toothbrush. There is no abrupt change in wall thickness from one point to another point next to it. The change in wall thickness from one point to another adjoining point is less than

1 mm or even less than 0.5 mm.

<img file="MX350950B_D0013.tif" />

Example 2A:

In a sample of the toothbrush with a thick handle, the ..... grosocxfo—. The wall in each 2mm length section varies 70% to 170% of the mean wall thickness of the same 2mm section, as shown in Figure 5B. The absolute wall thickness ranges from 0.6mm to 2.3mm in 80% of the hollow portion of the toothbrush as shown in Figure 5A. The mean wall thickness of each 2mm section along the longitudinal axis of the toothbrush is in the range of 0.9mm to 1.2mm. These are really nasty variations in wall thickness. The ratio of the standard deviation of the wall thickness to the mean wall thickness is less than 30%. The cross-sectional area of ​​this toothbrush sample remains constant at approximately 45mm² in 80% of the hollow portion of the toothbrush. The change in wall thickness from one point to another neighboring point is less than 0.5 mm. In contrast, the cross-sectional area of ​​a solid toothbrush with the same outer surface varies greatly from 120mm² at 210 mm² in the same portion of the handle. This hollow toothbrush with a slim handle saves 66% of the material of a solid toothbrush with the same shape and size.

Example 2B:

In another sample of the toothbrush with a thin handle, the wall thickness in each 2mm section varies 65% to 180% of the mean wall thickness of that 2mm section, as shown in Figure 6B. While the absolute wall thickness varies from 1.2mm to 2.8mm, as shown in Figure 6A. The mean wall thickness of each 2mm section along the longitudinal axis of the toothbrush is in the range of 1.5mm to 2mm. The ratio of the standard deviation of the wall thickness to the mean wall thickness is less than 23%. The cross-sectional area of ​​this toothbrush sample³⁶ ' *.

.Λ.

,. _. ...... - X remains constant at approximately 70 mm² in 80% of the hollow portion of the toothbrush as shown in Figure 6. In contrast, the cross-sectional area of ​​a solid toothbrush with the same outer surface varies greatly from 120 mm² at 210 mm² in the same portion of the handle. This hollow toothbrush with a slim handle saves 47% of the material of a solid toothbrush with the same shape and size.

The dimensions and values ​​described in the present description are not to be understood as strictly limited to the exact numerical values ​​mentioned. Instead, unless otherwise specified, each of those dimensions will refer to both the mentioned value and a functionally equivalent range that comprises that value. For example, a dimension expressed as 40mm '' will be understood as approximately 40mm.

All documents cited in the present description, including any cross-references or related applications or patents, are incorporated in their entirety in the present description by reference unless they are expressly excluded or limited in any other way. Mention of any document is not an admission that it constitutes prior matter with respect to any invention described or claimed in the present description or that by itself, or in any combination with any other reference or references, it teaches, suggests or describes said invention. . Furthermore, to the extent that any meaning or definition of a term in this document contradicts 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.

Although particular embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of: / _; ι '~ -' .. * '' ^s * í ^ invention. By eilo. In the appended claims it is intended to cover all modifications and changes that are within the scope of this TO ^ n: