EP2146600B1 - Toothbrush bristle with a tapering part and toothbrush with such bristles - Google Patents

Description

The present invention relates to a toothbrush bristle with a tapered portion and a toothbrush containing such bristles.

Classic bristles suitable for toothbrushes had a cylindrical cross-section. Since such bristles had an inadequate cleaning performance in the interndental space and tended to injure the gums, in the 90s of the last century, in part, the bristles were given a tapered end (see, for example, US Pat EP-A-0 596 633 ). Due to the smaller cross-section at the pointed end, the cleaning performance in the interdental space improved; at the same time, the bristle became more flexible, which reduced the risk of injury. On the other hand, the cleaning performance on the tooth surfaces decreased.

In the Korean patent KR 261658 (equivalent to US-A-6090488 ) has described a toothbrush bristle with a tapered portion, wherein the bristle at the end of the tapered portion has a diameter of 0.04 to 0.08 mm. The tapered part of this bristle was therefore no longer "sharpened" in the above sense. In the later EP-A-1 234 525 However, the same inventor describes a bristle with a tapered part, in which the diameter at the end of the tapered part is only 0.02 mm or less (this bristle resembles more or less the tapered bristles) EP-A-0 596 633 ). In support of the fact that he has reduced the diameter at the end of the bristle again, there the inventor suggests that the removal of tartar from periodontal pockets with the bristles of KR 261658 difficult. A toothbrush bristle with a tapered part was also used in JP2006158842 A described.

The present application has the object to provide an improved bristle with a tapered portion.

1. a) Einen zylindrischen Teil mit einem maximalen, konstanten Zylinderdurchmesser D_zyl;
2. b) einen sich an den zylindrischen Teil anschliessenden, ersten verjüngten Teil mit einem Borstenende und mit einer das Borstenende abschliessenden Stirnfläche, wobei sich der erste verjüngte Teil zum Borstenende hin verjüngt; und
3. c) eine durch den zylindrischen Teil und den ersten verjüngten Teil verlaufende gedachte Mittelachse, die die Stirnfläche an einem Durchstosspunkt durchstösst;

wobei der erste verjüngte Teil eine auf der Mittelachse und ab dem Durchstosspunkt gemessene Länge L von 10 mm oder weniger und mindestens 6 mm aufweist;
dadurch gekennzeichnet, dass der erste verjüngte Teil in einem auf der Mittelachse von dem Durchstosspunkt aus gemessenem Abstand X, der gleich gross ist wie der Zylinderdurchmesser D_zyl, einen Durchmesser D von 95 bis 140 µm aufweist.The object is achieved according to the invention by a bristle for a toothbrush, comprising:

1. a) A cylindrical part with a maximum, constant cylinder diameter D _zyl ;
2. b) a first tapered portion adjoining the cylindrical portion and having a bristle end and an end surface terminating the bristle end, the first tapered portion tapering towards the bristle end; and
3. c) an imaginary central axis extending through the cylindrical part and the first tapered part, which pierces the end face at a piercing point;

wherein the first tapered part has a length L of 10 mm or less and at least 6 mm measured on the central axis and from the piercing point;
characterized in that the first tapered part has a diameter D of 95 to 140 μm in a distance X measured on the center axis from the piercing point which is equal to the cylinder diameter D _zyl .

Preferred embodiments will be apparent from the dependent claims.

It was surprisingly found that the novel bristles have a longer life than the prior art tapered bristles: The pointed ends bend according to the findings of the applicant under the Tooth brushing occurring contact pressures, which leads over time to a fatigue breakage of the bristle tip; This is avoided by the invention merely tapered (not pointed) bristle ends. At the same time, it has been found that the bristles according to the invention are so mechanically stable that they show on the buccal tooth surfaces a cleaning performance which is comparable or even slightly superior to cylindrical bristles. The bristles according to the invention are also more suitable for cleaning interdental spaces and approximal tooth surfaces than bristles with non-tapered filament ends, since the bristles according to the invention can better reach approximal tooth surfaces.

Preferably, D is in the range of 100 to 130 microns, more preferably in the range of 100 to 125 microns. Also preferably, the first tapered part of the bristle has a diameter of 120 to 160 μm in a distance of 1 mm measured from the piercing point on the center axis and a diameter of 90 to 135 μm in a distance of 0.1 mm measured in the same way on.

The bristle according to the invention is substantially (or as far as technically possible) rotationally symmetrical about the central axis.

The profile line of the tapered portion of the bristle (ie, the diameter of the tapered portion as a function of the decreasing distance from the piercing point of the centerline of the bristle through the face) is preferably monotonically decreasing toward the face. The term "monotonously decreasing" in the context of the present application has the usual meaning in mathematics. Rather preferred is the profile line of Tapered part in the mathematical sense to the point of penetration strictly monotone decreasing.

The length of the tapered part (or, in the case of a U-shaped bent bristle according to the invention with two tapered parts, the length of both tapered parts) is
in the range of 6 to 10 mm.

The end face of the end of the first tapered part has a surface normal at said piercing point, which is preferably inclined no more than about 30 ° C towards said center line. This is usually the case automatically when the end face is formed by trimming a pointed end (see below); it may also be effected by suitable rounding treatment of the end face and its edges adjacent to the lateral surface of the tapered part (see below).

1. i) eine Borste mit einem zylindrischen Teil, an den sich genau ein im wesentlichen rotationssymmetrischer verjüngter Teil von 10 mm oder weniger Länge anschliesst (d.h. analog zur einseitig zugespitzten Borste);
2. ii) eine Borste mit einem zylindrischen Teil und genau zwei verjüngten, im Wesentlichen rotationssymmetrischen Teilen von je von 10 mm oder weniger Länge, die sich an entgegengesetzten Seiten an den zylindrischen Teil anschliessen (d.h. analog zur zweiseitig zugespitzten Borste), insbesondere, wobei die beiden verjüngten Teile im Wesentlichen gleich ausgebildet sind, und
3. iii) eine Borste mit einem zylindrischen Teil, einem im Wesentlichen rotationssymmetrischen verjüngten Teil von 10 mm oder weniger Länge und einem im Wesentlichen rotationssymmetrischen zugespitzten Ende, wobei verjüngter Teil und zugespitzter Teil sich an entgegengesetzten Seiten an den zylindrischen Teil anschliessen.

Three particularly preferred types of bristles according to the invention are as follows:

1. i) a bristle having a cylindrical part to which exactly one substantially rotationally symmetrical tapered part of 10 mm or less length adjoins (ie analogous to the unilaterally tapered bristle);
2. ii) a bristle having a cylindrical part and exactly two tapered, substantially rotationally symmetric parts, each of 10 mm or less in length, which adjoin the cylindrical part on opposite sides (ie analogous to the double-pointed bristle), in particular, the two in essence, tapered parts are the same, and
3. iii) a bristle having a cylindrical portion, a substantially rotationally symmetrical tapered portion of 10 mm or less in length, and a substantially rotationally symmetrical tapered end, the tapered portion and tapered portion joining the cylindrical portion on opposite sides.

In all embodiments of the bristle according to the invention, any edges between the end face and the tapered part can be removed by rounding, as is customary in the case of cylindrical bristles. The rounding can be carried out by conventional methods, e.g. B. using a sandpaper.

Particularly preferred profile lines of the first tapered part are approximately in accordance with the following profile tables 1 to 4. The diameters are given as a function of the distance from the piercing point of the center line through the end face (averages with scattering from 6 copies of the bristle). The extreme right column of each table _gives the maximum diameter of the cylindrical part (D _zyl ) of the bristle. According to the measurement definition according to the invention for the diameter D of the first tapered part, the corresponding diameter value is given in each table even at a distance X = D _zyl . Furthermore, in the profile tables 1 to 4, diameter values are also indicated at a distance of 0.1 mm from the end face in order to exemplify the preferred course of the first tapered part of the bristle in the vicinity of the end face according to the invention. Profile 1 Distance from the pointed end [mm] 0 0.1 0.202 1 2 3 4 5 6 7 8th 9 10 Diameter [mm] 0,107 (0,108) 0.113 0,117 0,147 0.172 0.183 0, 190 0.195 0.197 0,199 0.201 0,203 0.202 Diameter range [+/- mm] 0,012 0.019 0,021 0,020 0.019 0,014 0,014 0,014 0,012 0.011 0,010 Distance from the pointed end [mm] 0 0.1 0.209 1 2 3 4 5 6 7 8th 9 10 11 Diameter [mm] 0.086 (0.089) 0,095 0,101 0.140 0.172 0.185 0.192 0.198 0.201 0.204 0,205 0,205 0.208 0.209 Diameter range [+/- mm] 0,012 0,018 0,021 0,018 0,015 0,013 0,010 0.009 0,008 0,008 0,007 0,006 Distance from the pointed end [mm] 0 0.1 0.209 1 2 3 4 5 6 7 8th 9 10 Diameter [mm] 0.096 (0.098) 0,101 0.104 0,127 0,151 0,170 0.183 0.191 0,199 0.202 0.206 0.208 0.209 Diameter range [+/- mm] 0.009 0.009 0.009 0,008 0,007 0,006 0,008 0.005 0,006 0.005 0,003 Distance from the pointed end [mm] 0 0.1 0.166 1 2 3 4 5 6 7 8th 9 10 Diameter [mm] 0.112 (0.117) 0,119 0,122 0,137 0,150 0.156 0,159 0.162 0.163 0.164 0,165 0,165 0.166 Diameter range [+/- mm] 0,010 0.011 0.009 0.009 0,008 0,008 0,007 0,007 0,007 0,007 0,007

It may happen that in some embodiments of the bristle according to the invention, the diameter at the end face and at a small distance from the end face can no longer be reasonably measured. This is the case when the bristle end of the tapered part has been subjected to a subsequent rounding. This fillet may eventually form irregularly rugged shapes and uneven surfaces at the end of the bristle, making direct measurement of the diameter near the face impossible. It has now surprisingly also been found in the bristles according to the invention that in these cases the diameter close to or at the end face can be approximated by extrapolation by means of a parabola, wherein for the parabola the diameters of the bristles are in the distances of 1, 2 and 3 mm are taken from the front surface as support points. These interpolation points are given in bold in the tables above. To prove that this works, in the above profile tables at the distance 0 from the face, both the original, actually measured diameters of the bristle (as they were after trimming the end but before rounding) and below, in brackets, are given by this extrapolation certain diameter. The deviation between actual diameter and diameter determined by extrapolation is minimal. Such a simple extrapolation is possible with the bristles according to the invention because the curvature of the tapered part is less pronounced than in the previously known bristles.

The bristles according to the invention consist of a plastic suitable for toothbrush bristles. On the one hand, they may preferably be made of a polyester, in particular one Polyester obtainable from (C ₂ -C ₄ ) -1, ω-alkylene glycol and terephthalic acid. Rather preferably, the polyester is polyethylene terephthalate (PET) or polybutylene terephthalate (PBT), and particularly preferred is PBT. On the other hand, they may consist of a polyamide, in particular a polyamide obtainable from a (C ₂ -C ₈ ) -1, ω-diamine and from a (C ₂ -C ₈ ) -1, ω-dicarboxylic acid; Particularly preferred here is polyamide-6,6 (eg nylon).

For the production of bristles according to the invention, it can be assumed that commercially available bristles, which are tapered on one or two sides, or cylindrical bristles. At the filing date of the present application, for example, Pragma, Shinyoung, Whessen, Hylon, Sogo, Best Whasung or Cheil Jedang were manufacturers of such bristles.

Bristles according to the invention, which have exactly one first tapered end, can be obtained, for example, from a commercially available unilaterally tapered bristle by trimming the pointed end while simultaneously forming the tapered end and the end face. In order for the bristle to have a total length suitable for toothbrush bristles, the other, cylindrical end of the bristle may be cut to size.

Bristles of the invention having a second tapered portion adjacent the first tapered portion may typically be formed from commercially available cylindrical bristles of suitable length by chemically etching the ends to the appropriate tapered or tapered shape. This etching process has been in the field of tapered bristles since long known. Optionally, the tapered end may also be trimmed here to set a useful overall length of the bristle.

On the other hand, two-sided sharpened bristles are commercially available, which need only be suitably trimmed at both ends to obtain a bristle according to the invention with two tapered parts and a length suitable for toothbrushes (see Example 1).

In the chemical etching process, the bristles can first be trimmed to a uniform length. Thereafter, they can be etched vertically immersed in an etching liquid of typically 80 to 150 ° C. Examples of etching liquids are inorganic solutions, for example a strongly alkaline etching solution (for example a 25-50% strength by weight aqueous NaOH or KOH solution) or a strongly acidic etching solution (for example 60-98% strength by weight aqueous sulfuric acid solution). Examples of etching liquids are also organic solvents such as m-cresol, trifluoroacetic acid, o-chlorophenol, trichlorophenol, DMSO, DMF, and a mixture of phenol and tetrachloroethane. The duration of the immersion may typically be 10 to 20 minutes, with the bristles being optional during this Time can be gradually withdrawn from the etchant at a freely selectable, constant or time varying rate, whereby the profile of the etched end (ie, the monotony of the profile line) can be influenced. After etching, depending on the nature of the etching solution, the ends may be washed with water, dilute base, dilute acid or a suitable solvent at room temperature and dried.

On the one hand, the conditions of the etching (type and temperature of the etching liquid, duration of immersion) can be chosen such that the diameter D of the tapered part after etching is just in the range of 100 to 140 μm according to the invention. For this purpose, the etching is carried out in a shorter period of time than for the etching of the previously known sharpened bristles. Otherwise, the conditions of the etching may be selected to initially form a tapered end, which is then trimmed to obtain the end face and the tapered part.

If desired, after being etched in an alkaline or acidic solution, the ends of the bristles may be trimmed additionally before the ends are rounded. Whether the ends need to be trimmed can be determined simply by observing the condition of the ends with an enlarger after they have been removed from the solution.

The invention also provides a toothbrush with bristles according to the present invention. The novel bristles can be used analogously to the previously known one or two-sided sharpened bristles in the bristle carrier of a toothbrush. Bristles according to the invention with two tapered parts or with a tapered part and a sharpened part are in this case preferably bent in a U-shape and inserted in the bristle carrier by means of anchor plates. In contrast, bristles according to the invention with only just one tapered part and one cylindrical part are preferably inserted into the bristle carrier in unconverted form by means of the method known in the jargon as "Anchor-Free Tufting".

• Fig. 1 einen Querschnitt durch eine erfindungsgemässe Borste zeigt, wobei auch die erfindungswesentlichen Messparameter angegeben sind;
• Fig. 2, 3 und 4 drei Ausführungsformen der erfindungsgemässen Borste zeigen; und
• Fig. 5 und 6 Tests auf in vitro-Reinigungsleistung bei schwarzgefärbten, dann TiO₂-beschichteten Zähnen mit erfindungsgemässen und herkömmlichen zylindrischen Borsten zeigen.

The invention will now be further illustrated with reference to the examples and figures, wherein in FIGS

• Fig. 1 shows a cross section through a bristle according to the invention, wherein also the measurement parameters essential to the invention are indicated;
• Fig. 2, 3 and 4 show three embodiments of the inventive bristle; and
• FIGS. 5 and 6 Tests for in vitro cleansing performance in black colored, then show TiO ₂ -coated teeth with inventive and conventional cylindrical bristles.

Example 1: Production of bristles with two identical tapered parts according to the above profile tables 1 to 4

It was assumed that four commercial two-sided sharpened bristles, which were as follows: output bristle trimmed at a distance from the tips [mm] For above profile table no. Pragma 0.18 x 28 mm 033004 A-BBC 2 1 Pragma 0.19 x 28 mm 033004 A-BBC 1 2 Shinyoung 0.20 x 28 mm 2 3 Whose 0.18 x 24 mm 2 4

Each of the initial bursts was trimmed at the two peaks in intervals as indicated above in the middle column. The ends of the thus-obtained tapered portions of the bristles were rounded using a TR89 Bristle Rounding Machine (manufactured by Tsujimura Co., Japan) with 240 mesh emery paper.

FIG. 1 shows an end with tapered portion of a bristle according to the invention. On the right, the cylindrical part (1) is indicated, whose constant diameter at the same time means the maximum diameter D _{zyl of} the bristle. The cylindrical part (1) is adjoined by a tapered part (21), the taper of which begins at a distance L from the piercing point (6) of the central axis (5) through the end face (4) and decreases strictly monotonously to the end ( 3) extends. The end face (4) of the end (3) is shown here after an idealized rounding, that is formed approximately hemispherical; due to trimming and subsequent real rounding, this face could also be rather flat, but with more or less irregular or rugged edges. It is also shown that the diameter D essential to the invention is measured at a distance X from the piercing point (6), the distance X being equal to the said maximum _{diameter of} the cylindrical part, D _cyl .

Figures 2-4 show three inventive bristles. In all of these figures, the bristle is shown bent in a U shape, like the bristles in particular of FIGS. 2 and 3 in the bristle face of a toothbrush would be planted. The bend is done in the cylindrical part (1) which is then bent itself U-shaped. In FIG. 2 a bristle according to the invention with two tapered parts (21, 22) is shown; in figure 3 a bristle according to the invention is shown with a first tapered part (21) and a pointed end (7); and in FIG. 4 a bristle according to the invention is shown with only just a tapered part (21), the remainder of the bristle being formed by a cylindrical part (1). This latter bristle could, unlike in FIG. 3 shown, even in non-bent form in the bristle carrier of a toothbrush head are used.

1. (A) Bürsten mit erfindungsgemässen zweiseitig verjüngten, rotationssymetrischen, U-förmig umgebogen in die Bürste eingesetzten Borsten (siehe Figur 2) mit einer Borstenfeldhöhe von 11,5 mm, mit einem maximalen Durchmesser D_zyl von etwa 0,21 mm und einem Durchmesser D von etwa 0,104 mm in einem Abstand X = D_zyl (diese Borsten entsprachen etwa dem vorstehend tabellarisch exemplifizierten Profil 3); und
2. (B) Bürsten mit herkömmlichen zylindrischen, U-förmig umgebogen in die Bürste eingesetzten Borsten mit Durchmesser

FIGS. 5 and 6 show tests on cleaning performance achieved in vitro on black-colored, then TiO ₂ -coated teeth. Tested were:

1. (A) brushes according to the invention with two-sided tapered, rotationally symmetrical, U-shaped bent bristles used in the brush (see FIG. 2 ) having a bristle field height of 11.5 mm, a maximum diameter D _zyl of about 0.21 mm and a diameter D of about 0.104 mm at a distance X = D _zyl (these bristles corresponded approximately to profile 3 exemplified above in tabular form); and
2. (B) brushes with conventional cylindrical, U-shaped bent into the brush used bristles with diameter

D _zyl of 0.175 mm and a bristle field _height of 11.5 mm. In these tests, the teeth of a maxillary sextant model (with 3 molars, 2 prebend teeth and 1 canine) were first stained black and then whitewashed with a TiO ₂ paste (25 g in 75 ml of 26% ethanol). After a standardized brushing operation with the bristle field to be tested of 1 min duration with 250 g coating weight, the proportion of the tooth surfaces which had been freed from the TiO ₂ paste was determined. This process is by default for each bristle field to be tested, each with horizontal, performed vertical and rotating brushing movements and repeated four times for each bristle field to be tested and each brushing movement. For horizontal cleaning (the white parts of the bars in the figures), the standardized brushing operation consisted of 60 reciprocating movements with an amplitude of 30 mm; during vertical cleaning (in the figures the hatched parts of the beams) it consisted of 60 movements up and down with an amplitude of 8 mm; and in the circular cleaning (in the figures the dotted parts of the beams) it consisted of 60 circles of radius 4 mm with simultaneous 16 horizontal reciprocating movements with amplitude of 30 mm. In the FIGS. 5 and 6 the measured cleaning powers, ie the proportion of removed TiO ₂ , are given in arbitrary units.

FIG. 5 shows the sum of the average values of the cleaning performance after horizontal, vertical and circular cleaning movements with the bristles according to the invention (bar A) and with the conventional cylindrical bristles (bar B) in the case of the buccal tooth surfaces.

FIG. 6 shows the sum of the average values of the cleaning performance after horizontal, vertical and circular cleaning movements with the bristles according to the invention (bar A) and with the conventional cylindrical bristles (bar B) in the mesial / distal tooth surfaces, ie in the tooth surfaces facing the interdental spaces.

Out FIG. 5 It can be seen that the inventive bristles despite lower mechanical strength in horizontal and vertical cleaning movements on buccal Tooth surfaces are slightly superior to conventional bristles. Out FIG. 6 It can be seen that the bristles according to the invention are clearly superior to the conventional bristles, especially in the horizontal and vertical brushing movement on mesial / distal tooth surfaces.

Claims (10)

1. A bristle for a toothbrush, comprising:

   a) a cylindrical part (1) with a maximum constant cylinder diameter D_zyl ;

   b) adjacent to the cylindrical part (1) a first tapered part (21) with a bristle end (3) and an end face (4) delimiting the bristle end (3), wherein the first tapered part (21) tapers towards the bristle end (3); and

   c) an imaginary central axis (5) which runs through the cylindrical part (1) and the first tapered part (21) and which pierces the end face (4) at a piercing point (6); wherein the first tapered part (21) has a length L of 10 mm or less and at least 6 mm, as measured on the central axis (5) starting from the piercing point (6);

   characterized in that the first tapered part (21) has a diameter D of 95 to 140 µm, as measured on the central axis (5) starting from the piercing point (6) at a distance X being equal to the cylinder diameter D_zyl .
2. The bristle according to claim 1, characterized in that D is in the range of 100 to 130 µm, preferably 100 to 125 µm.
3. The bristle according to claim 1 or 2, characterized in that the first tapered part (21) has a diameter of 120 to 160 µm, as measured on the central axis (5) at a distance of 1 mm from the piercing point (6) and has a diameter of 90 to 135 µm at a distance of 0,1 mm, as measured in the same way.
4. The bristle according to any of the claims 1 to 3, characterized in that the bristle further comprises a second tapered part (22) adjacent to the cylindrical part (1) on a side opposed to the first tapered part (21).
5. The bristle according to claim 4, characterized in that the second tapered part (22) has essentially the same shape as the first tapered part (21).
6. The bristle according to any of the claims 1 to 3 characterized in that the bristle further comprises a pointed end (7) adjacent to the cylindrical part (1) on the side opposed to the first tapered part (21).
7. A bristle according to any of the claims 1 to 6, characterized in that the cylinder diameter D_zyl is in the range of 150 to 170 µm or in the range of 180 to 210 µm.
8. A bristle according to any of the claims 1 to 7 consisting of polyester or a polyamide.
9. A bristle according to any of the claims 1 to 8 consisting of polyethylene terephthalate, polybutylene terephthalate or polyamide-6,6.
10. A toothbrush comprising one or more bristles according to any of the claims 1-9.

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