CN112674460A - Tooth brush - Google Patents

Abstract

The invention provides a toothbrush which is easy to taper by mechanical grinding, can improve the cleaning performance of teeth crevice and the like, and can easily know which part of the teeth is being ground and brushed. A toothbrush (1) in which a plurality of bristles (10) made of synthetic resin filaments are implanted in a bristle base (2), the filaments are made of a resin material obtained by melt-mixing polybutylene terephthalate with polypropylene terephthalate, a tapered portion (11) formed by mechanical grinding is provided in a range of 30% to 70% of the length (H) of the bristles (10) from the tip (12) of the bristles (10) toward the bristle base (2), and the plurality of bristles (10) implanted in the bristle base (2) include bristles (10) such as: the arithmetic line roughness (Ra) in the 0.1mm region from the top end of the brush (10) to the hair setting base (2) side toward the hair setting base (2) side is more than 1.5 μm.

Description

Tooth brush

Technical Field

The present invention relates to a toothbrush using bristles having a tapered portion formed on a tip side portion thereof.

Background

As a toothbrush, the following toothbrushes have been widely put into practical use: in this toothbrush, by using bristles having tapered portions formed on the tip side portions thereof, the bristles are more easily inserted into and reach narrow portions (hereinafter, simply referred to as "slit portions") such as slits between teeth, a tooth neck portion at the boundary between a crown and a tooth root, and a cleavage groove portion of a molar portion, which are difficult to reach by the bristles, and plaque removing performance at the portions is improved.

As a method of forming a tapered portion in bristles, a method of forming a tapered portion by immersing tip portions of bristles in a chemical solution containing an alkaline agent (for example, see patent document 1) and a method of forming a tapered portion by mechanical polishing (for example, see patent documents 2 and 3) are proposed.

In the method described in patent document 1, since the tapered portion can be formed over the entire length of the brush from the bristle base to the tip end portion of the brush, the tip end side portion of the brush can be configured to be smaller in diameter as compared with the case where the tapered portion is formed by mechanical polishing, and the insertability and reach of the brush with respect to a narrow portion such as a slit portion can be improved, and the cleanability of the slit portion and the like can be improved.

However, in the method described in patent document 1, since the distal end portions of the bristles are formed into a sharp shape as compared with the case of forming the tapered portions by mechanical polishing, there are problems such as a case where gums are damaged during polishing, and a case where the stiffness (japanese: waist) of the bristles at the distal end side portions of the bristles is weak, and the cleaning property of the tooth surfaces is lowered, and therefore, recently, toothbrushes formed by forming the tapered portions by mechanical polishing as described in patent documents 2 and 3 have also received attention.

In the invention described in patent document 2, in order to ensure ease of manufacture and durability while ensuring tartar removal, the arithmetic line roughness Ra of the tapered portion is set to 0.5 μm to 1.5 μm, and in the invention described in patent document 3, since irregularities are generated on the bristle surface, stress during brushing tends to concentrate at a specific point, which may cause breakage of the bristles and decrease in durability, and further, may damage the gums, and thus the arithmetic line roughness Ra of the tapered portion is set to less than 0.5 μm.

On the other hand, a toothbrush has been proposed which uses a resin material obtained by melt-mixing polytrimethylene terephthalate and polybutylene terephthalate as a raw material of filaments constituting bristles and improves processability in mechanical polishing of a tapered portion while ensuring durability of the bristles (for example, see patent document 4).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2017-118939

Patent document 2: japanese laid-open patent publication No. 10-57149

Patent document 3: japanese patent No. 5090164

Patent document 4: japanese patent laid-open publication No. 2006 and 158842

Disclosure of Invention

Problems to be solved by the invention

As bristles for toothbrushes, in order to sufficiently secure the stiffness of bristles, bristles made of nylon or polybutylene terephthalate (PBT) having high rigidity are widely used. However, the bristles made of nylon and polybutylene terephthalate have problems that the processability of the tapered portion obtained by mechanical polishing is poor and the durability of the tapered portion is low.

The arithmetic line roughness Ra of the tapered portion formed by mechanical polishing is usually set to 1.5 μm or less as in the inventions described in patent documents 2 and 3, in consideration of easiness of tapering, durability, damage to the gum, and the like.

In the conventional toothbrush, the contact position of the brush with respect to the teeth can be grasped to some extent by the contact feeling of the brush with respect to the gum, the contact feeling of the brush with respect to the teeth, and the like, but since the arithmetic line roughness Ra of the surface of the brush is small, the feeling of use when the tip portion of the brush moves while rubbing the surface of the teeth is weak, and therefore, it is difficult for the user to clearly grasp which part of the teeth is being rubbed with the brush.

The inventors of the present application have made extensive studies on the practical use of a toothbrush having bristles with an arithmetic line roughness Ra of more than 1.5 μm, since the user can more clearly grasp the brushed portion and can reduce the non-brushed portion (japanese: grind き residue し) by the feeling of use of the non-smoothness caused by the bristles moving on the tooth surface during brushing when the arithmetic line roughness Ra of the tip portion of the tapered portion exceeds 1.5 μm. As a result, it was found that even in the case where the tapered portion is formed by machining so that the arithmetic line roughness Ra exceeds 1.5 μm, the easiness and durability of the tapering can be sufficiently ensured by selecting the raw material of the brush, and the formation of the tapered portion by machining can reduce the damage to the gum as compared with the case where the tapered portion is formed by a chemical solution, thereby completing the present invention.

The invention aims to provide a toothbrush which is easy to taper by mechanical grinding, can improve the cleaning performance of a slit part and the like, and can easily know which part of teeth is brushed.

Means for solving the problems

The present invention includes the following inventions.

(1) A toothbrush in which a plurality of bristles made of synthetic resin filaments are implanted in a bristle base, wherein the filaments are made of a resin material obtained by melt-mixing a polyester resin other than polytrimethylene terephthalate with polytrimethylene terephthalate, a tapered portion formed by mechanical polishing is provided in a range of 30% to 70% of the length of the bristles from the bristle base to the tip of the bristles from the tip of the bristles toward the bristle base, and the plurality of bristles implanted in the bristle base include bristles such as: the arithmetic line roughness Ra in the area of 0.1mm from the 0.1mm part of the top end of the bristle toward the bristle base side exceeds 1.5 μm. In the present specification, the term "tapered portion" refers to a structure including not only a case where the ground portion is formed over the entire circumference of the brush, but also a case where the ground portion is formed only partially in the circumferential direction of the brush.

(2) The toothbrush according to the item (1), wherein, among the plurality of bristles implanted in the central portion of the bristle base, an average value of the arithmetic line roughness Ra in a region of 0.1mm toward the bristle base side from a 0.1mm portion of a tip end of the bristle toward the bristle base side is 1.45 μm or more.

(3) The toothbrush according to the above (2), wherein the average value of the arithmetic line roughness Ra in a region of 0.5mm, 1mm and 2mm from the tip end of the bristle toward the bristle holder side in the plurality of bristles implanted in the central portion of the bristle holder is all in the range of 1.5 μm to 3.0 μm.

(4) The toothbrush according to the above (2) or (3), wherein the average values of the arithmetic line roughness Ra in the regions of 0.5mm, 1mm and 2mm from the tips of the bristles implanted in the central portion of the bristle holder toward the bristle holder side and 0.1mm toward the bristle holder side are in the ranges of 1.5 to 2.5 μm, 1.5 to 2.1 μm and 1.7 to 2.5 μm, respectively.

(5) The toothbrush according to any one of the above (1) to (4), wherein the plurality of bristles implanted in the implanting base include bristles that are: the diameters of the bristles at respective portions, which are spaced apart from the top ends of the bristles by distances of 0.1mm, 0.5mm, 1mm and 2mm, are within the ranges of 15% -35%, 35% -75%, 45% -95% and 65% -100% of the maximum diameter of the bristles, respectively.

(6) The toothbrush according to any one of the above (1) to (5), wherein an outer surface of the tapered portion is formed of a curved surface protruding outward.

(7) The toothbrush according to any one of the above (1) to (6), wherein tip portions of the plurality of bristles implanted in the implanting seat are rounded.

(8) The toothbrush according to any one of the above (1) to (7), wherein the lengths of the plurality of bristles implanted in the implant seat from the implant seat to the distal end portions of the bristles are 5mm to 12 mm.

(9) The toothbrush according to any one of the items (1) to (8), wherein the polyester-based resin is polybutylene terephthalate.

ADVANTAGEOUS EFFECTS OF INVENTION

In the toothbrush of the present invention, the filaments constituting the bristles are formed using a resin material obtained by melt-mixing a polyester resin other than polytrimethylene terephthalate with polytrimethylene terephthalate, and therefore, the stiffness of the bristles can be sufficiently ensured and sufficient durability can be ensured as compared with bristles formed only of polybutylene terephthalate. Further, the mechanical polishing processability of the bristle using the resin material is higher than that of a bristle made of only polybutylene terephthalate or only nylon, and the bristle can be easily tapered.

Further, since the tapered portion is provided in the range of 30% to 70% of the length of the brush from the tip end of the brush toward the bristle base to the tip end of the brush from the bristle base, the tapered portion formed by mechanical polishing can have a smaller diameter at the tip end side portion to the same extent as the tapered portion formed by the chemical solution, and the insertion and reaching properties of the brush with respect to the narrow portion such as the slit portion can be improved, and the cleaning properties including plaque removing performance at the slit portion can be improved. Further, since the distal ends of the brush staples are rounded, damage to the gum can be prevented unlike the tapered portion formed by the chemical solution.

Further, the bristles implanted in the hair-setting seat include bristles having an arithmetic line roughness Ra of more than 1.5 μm in a region of 0.1mm toward the hair-setting seat side from a portion of 0.1mm toward the hair-setting seat side from the tip end thereof, and therefore, the cleaning performance including plaque removal at the slit portion and the like can be improved by the physical scraping effect. Further, when the bristles having an arithmetic line roughness Ra of more than 1.5 μm are used to rub the tooth surfaces, vibration is transmitted to the cochlea of the user by bone conduction, and the user feels a feeling of use including sounds such as rustling and swishing (hereinafter, referred to as a "non-smooth feeling" in this specification) together with the vibration. Therefore, the user can more clearly grasp which part of which tooth is being brushed based on the non-smooth feeling, and by brushing so that the non-smooth feeling is obtained in all parts of all teeth, the number of non-brushed parts can be reduced.

Drawings

Fig. 1 is a top view of a toothbrush near the head.

Fig. 2 is a sectional view II-II of fig. 1.

Fig. 3 is a front view of the bristle.

Fig. 4 is a front view of a main portion of the bristle.

Fig. 5 is a side view of the buccal side of the jaw near the first large molar of the upper jaw in the jaw model.

Description of the reference numerals

1. A toothbrush; 2. a hair planting base; 2a, planting a hair surface; 3. a neck portion; 4. a toothbrush body; 5. hair bundles; 6. a hair-planting part; 7. planting pores; 10. brushing; 11. a tapered portion; 12. a top end; m, gum; t1, maxillary first molar.

Detailed Description

Embodiments of the present invention will be described below with reference to the drawings.

As shown in fig. 1 and 2, the toothbrush 1 includes: a toothbrush body 4 including a bristle base 2, a neck portion 3, and a handle portion (not shown); and a hair-planting portion 6 formed by a plurality of hair bundles 5 implanted in the hair-planting base 2. The structure of the toothbrush body 4 is not particularly limited, and any known structure can be adopted.

A plurality of hair implantation holes 7 are formed in the hair implantation seat 2 in a predetermined array, and the hair bundle 5 is implanted in the hair implantation holes 7 using a metal piece (not shown) (japanese: horizontal line). The number and arrangement of the implanted holes 7 can be configured to be other than those shown in fig. 1. In addition, as a method of implanting the hair bundle 5 into the hair-setting seat 2, a known implantation method using no metal sheet, such as an in-mold forming method or a thermal welding hair-setting method, may be employed in addition to the implantation method using a metal sheet.

As shown in fig. 2 and 3, the bundle of bristles 5 implanted in the bristle-implanting hole 7 is composed of a plurality of bristles 10, and the bristles 10 are formed of synthetic resin filaments. In order to obtain a moderate stiffness of the bristles, the diameter of the filaments, i.e. the maximum diameter Φ of the bristles 10, is preferably in the range of 0.1 to 0.3 mm. The bristle length H of the bristles 10 from the bristle-planted surface 2a of the bristle-planted base 2 to the bristle head of the bristles 10 is preferably 5mm or more in order to ensure a good feeling of use, and the bristle length H is preferably 12mm or less in order to ensure operability in the oral cavity. Further, the bristle length H is 8mm to 12mm in the case of a toothbrush for adults, and 5mm to 10mm in the case of a toothbrush for children.

The bristle 10 has a tapered portion 11 whose diameter decreases toward the distal end side. The tapered portion 11 is formed by switching the grindstone in a stepwise manner from a coarser grindstone to a finer grindstone (japanese: ディスク) and grinding the bristles 10 implanted in the bristle holder 2 in sequence by the grindstone.

Since the tapered portion 11 is formed by mechanical polishing using a grinding disc in this manner, the tip of the tapered portion 11 is formed into a hemispherical shape that is approximately round-headed. The width of the bristle head close to the hemisphere where the round head is processed is in the range of 10% to 35% of the maximum diameter Φ of the bristle 10. Therefore, the tip 12 of the tapered portion 11 is not excessively sharp, and damage to the gum from the tip 12 of the brush 2 can be prevented.

The tapered portion 11 is formed in a range of 30% to 70%, preferably 50% to 70%, of the bristle length H from the distal end 12 of the bristle 10 toward the bristle holder 2. By increasing the formation range of the tapered portion 11 in this manner, the angle formed between the longitudinal direction of the bristle 10 and the surface of the tapered portion 11 can be reduced, the diameter of the tip side portion of the tapered portion 11 can be reduced, the insertion length of the bristle 10 into the slit portion or the like can be increased, and plaque removal performance at the slit portion or the like can be improved.

The diameters of the tapered portions 11 at the portion a, the portion b, the portion c and the portion d, which are spaced from the tip 12 of the bristle 10 by 0.1mm, 0.5mm, 1mm and 2mm, respectively, are in the ranges of 15% to 35%, 35% to 75%, 45% to 95% and 65% to 100% of the maximum diameter Φ of the bristle 10, respectively, and the outer surface of the tapered portion 11 is formed of a curved surface protruding outward from the base end portion toward the tip end portion of the tapered portion 11. With this configuration, while the stiffness of the bristles of the tapered portion 11 is sufficiently ensured, the length of the bristles 10 inserted into the slit portion or the like can be increased, and the cleaning performance and the insertion performance including plaque removal in the slit portion or the like can be improved.

The bristles 10 implanted in the hair-planting base 2 include the following bristles: the arithmetic line roughness Ra of the bristles in a region A (shown by dots in FIG. 4) 0.1mm away from the portion 0.1mm away from the tip end 12 toward the hair setting seat 2 side exceeds 1.5 μm. In this manner, in the case of the bristles having the arithmetic line roughness Ra in the region a exceeding 1.5 μm, the vibration generated when the bristles are rubbed against the tooth surfaces is transmitted to the cochlea of the user by bone conduction. Therefore, the user can feel a feeling of use (non-smooth feeling) including sounds such as rusty or make a whine together with the vibration, and can more clearly grasp which part of which tooth is being brushed based on the non-smooth feeling. Therefore, by performing the brushing so that a non-smooth feeling is obtained in all the portions of all the teeth, the number of non-brushed portions can be reduced. Further, by inserting the tip side portion of the tapered portion 11 including the region a having the arithmetic line roughness Ra exceeding 1.5 μm into the slit portion or the like, the cleaning performance including plaque removal at the slit portion or the like can be improved.

The upper limit of the arithmetic line roughness Ra of the bristle 10 is not particularly limited, but is preferably 4 μm or less, and more preferably 3.8 μm or less, in order to prevent a reduction in the feeling of use due to the uneven feeling becoming too strong.

The most preferable range of all the bristles 10 implanted in the bristle base 2 is bristles having an arithmetic line roughness Ra in the region a exceeding 1.5 μm, but bristles having an arithmetic line roughness Ra in the region a of 1.5 μm or less are included in any case because of the formation of the tapered portion 11 by mechanical grinding using a grinding disc. However, when the number of bristles having such a small surface roughness is increased, a sufficient matte feeling cannot be obtained. Therefore, the bristles having an arithmetic line roughness Ra of more than 1.5 μm in the region a are preferably at least 40% or more, more preferably 60% or more, and still more preferably 80% or more, with respect to the total number of the bristles 10 implanted in the implanting seat 2.

The average value of the arithmetic line roughness Ra in the region A of the plurality of bristles implanted in the central region X shown by the imaginary line in FIG. 1 in the central portion of the bristle holder 2 is preferably 1.45 μm or more, more preferably 1.50 μm or more, and still more preferably 1.55 μm or more. The upper limit value of the arithmetic line roughness Ra in the region a of the bristles implanted in the central region X is not particularly limited, but is preferably 4 μm or less, and more preferably 3.8 μm or less, in order to prevent a reduction in the feeling of use due to an excessively strong non-smooth feeling. In the present embodiment, since the tapered portion 11 is formed by mechanical polishing using a millstone as described above, the tufts 5 implanted in the central portion of the bristle holder 2 are affected by the mechanical polishing using a millstone having the finest particle size, as compared with the tufts 5 implanted in the outer peripheral portion of the bristle holder 2, and the arithmetic line roughness Ra of the surface of the tapered portion 11 tends to be smaller as a whole. Therefore, a tendency is exhibited that the average value of the arithmetic line roughness Ra in the region a of the bristles implanted in the outer side portion of the bristle holder 2 is larger than the average value of the arithmetic line roughness Ra in the region a of the bristles implanted in the central portion of the bristle holder 2. Therefore, by setting the average value of the arithmetic line roughness Ra in the area a of the bristles set in the central portion of the bristle setting base 2 to 1.45 μm or more, the average value of the arithmetic line roughness Ra in the area a of the bristles set in each portion of the bristle setting base 2 can be set to 1.45 μm or more as a whole, and a sufficient feeling of non-smoothness can be obtained at the time of brushing.

The average value of the arithmetic line roughness Ra in the regions B to D (shown by dots in FIG. 4) of 0.5mm, 1mm and 2mm from the tip 12 toward the hair-setting seat 2 among the plurality of bristles implanted in the central region X is not particularly limited, but the average value of the arithmetic line roughness Ra is preferably in the range of 1.5 to 3.0 μm, the average value of the arithmetic line roughness Ra in the region B is preferably in the range of 1.5 to 2.5 μm, the average value of the arithmetic line roughness Ra in the region C is preferably in the range of 1.5 to 2.1 μm, and the average value of the arithmetic line roughness Ra in the region D is preferably in the range of 1.7 to 2.5 μm in all the regions. The surface roughness of the regions B to D also affects the matte feeling and the cleanability as in the region a, but the influence is smaller than that of the region a, and therefore, the surface roughness corresponding to the surface roughness of the region a can be configured.

The cross-sectional shape of the synthetic resin filament constituting the brush 10 is not particularly limited, and various cross-sectional shapes such as a circle, an ellipse, a triangle, and a quadrangle can be adopted. In the case of a cross-sectional shape other than a circular cross-section, the diameter of each portion of the filament refers to the diameter of a circumscribed circle of the cross-sectional shape of the filament at that portion.

The synthetic resin filaments constituting the brush bristles 10 are formed by using a resin material obtained by melt-mixing a polyester resin other than polytrimethylene terephthalate with polytrimethylene terephthalate, and are formed by melt-mixing a synthetic resin monofilament obtained by melt-mixing polytrimethylene terephthalate and another polyester resin having higher rigidity than polytrimethylene terephthalate, preferably polybutylene terephthalate. The mixing ratio of the polytrimethylene terephthalate is preferably 60 to 90% by weight, and more preferably 70 to 80% by weight. Since polytrimethylene terephthalate has excellent workability, the tapered portion 11 can be easily formed by mechanical polishing, and since polybutylene terephthalate has excellent rigidity, the stiffness of the bristles 10 can be sufficiently ensured while increasing the length of the tapered portion 11, and the insertability and reach to the slit portion and the like can be improved, thereby improving the cleanability. Further, since polytrimethylene terephthalate has bending recovery properties and flexibility, the bristles 10 are less likely to fall apart even after long-term use, and particularly when polybutylene terephthalate is blended, there is no risk of breakage of the bristles 10 even after long-term use, and a toothbrush 1 having excellent durability can be realized.

[ examples ] A method for producing a compound

Hereinafter, examples of the present invention will be described, but the present invention is not limited to these examples.

(example 1)

A synthetic resin filament having a diameter of 0.2mm was produced by using, as a resin component, a resin material obtained by melt-mixing polytrimethylene terephthalate and polybutylene terephthalate at a mixing ratio of 80/20 by weight.

Then, the synthetic resin filament was cut into a predetermined length, a bundle of bristles, which was bent at the center in the longitudinal direction of the cut synthetic resin filament, was implanted in the bristle-implanting holes of the bristle-implanting base in the order shown in fig. 1 using a metal piece, and then the distal end portions of the bristles were cut off so that the bristle length H became 10.5 mm. Next, the distal end side portion of the brush was tapered by mechanical grinding using a millstone, and the brush was tapered so that the length L of the tapered portion from the distal end portion of the brush was 4mm and the taper ratio L/H of the length L of the tapered portion to the length H of the brush was 38%, thereby producing the toothbrush of example 1 having a tapered portion in which the diameters at a 0.1mm portion a, a 0.5mm portion b, a 1.0mm portion c, and a 2.0mm portion d from the distal end of the brush toward the bristle base side were 0.06mm, 0.11mm, 0.14mm, and 0.17mm, respectively.

(example 2)

A toothbrush of example 2 was produced in the same manner as in example 1 except that mechanical polishing was performed so that the length L of the tapered portion formed in the bristles was 6mm, the taper ratio L/H was 57%, and the diameters of the portion a, the portion b, the portion c, and the portion d of the head portion were 0.05mm, 0.08mm, 0.09mm, and 0.13mm, respectively.

(example 3)

A toothbrush of example 3 was produced in the same manner as in example 2, except that the mechanical polishing was performed so that the diameters of the portion a, the portion b, the portion c, and the portion d formed in the head portion of the brush were 0.03mm, 0.08mm, 0.11mm, and 0.16mm, respectively.

(example 4)

A toothbrush of example 4 was produced in the same manner as in example 2, except that the mechanical polishing was performed so that the diameters of the portion a, the portion b, the portion c, and the portion d formed in the head portion of the brush were 0.07mm, 0.12mm, 0.16mm, and 0.18mm, respectively.

(example 5)

A toothbrush of example 5 was produced in the same manner as in example 1 except that the synthetic resin filaments were mechanically ground so that the diameters thereof were 0.15mm, and the diameters thereof at the site a, the site b, the site c and the site d formed in the head portion of the brush were 0.05mm, 0.11mm, 0.13mm and 0.15mm, respectively.

(example 6)

A toothbrush of example 6 was produced in the same manner as in example 5 except that the brush head portion formed by the bristles was mechanically ground so that the length L of the brush head portion was 6mm, the taper ratio L/H was 57%, and the diameters of the brush head portion at the site a, the site b, the site c, and the site d were 0.04mm, 0.08mm, 0.10mm, and 0.13mm, respectively.

(example 7)

A toothbrush of example 7 was produced in the same manner as in example 6, except that the mechanical polishing was performed so that the diameters of the portion a, the portion b, the portion c, and the portion d formed in the head portion of the brush were 0.03mm, 0.08mm, 0.12mm, and 0.14mm, respectively.

(example 8)

A toothbrush of example 8 was produced in the same manner as in example 6, except that the mechanical polishing was performed so that the diameters of the portion a, the portion b, the portion c, and the portion d formed in the head portion of the brush were 0.04mm, 0.11mm, 0.14mm, and 0.15mm, respectively.

Comparative example 1

A synthetic resin filament having a diameter of 0.19mm was produced using a resin containing polybutylene terephthalate (100%) as a resin component, and using this synthetic resin filament, a bundle of bristles was implanted in a bristle base in the same manner as in example 1, and the distal end portions of the bristles were cut off so that the bristle length H of the bristles became 11.5 mm. Next, the tip portions of the bristles were immersed in a chemical solution containing an alkaline agent, and the toothbrush of comparative example 1 having tapered portions in which the length L of the tapered portion from the tip portions of the bristles was 5mm, the taper ratio L/H of the length L of the tapered portion to the length H of the bristles was 43%, and the diameters of the bristles at the portion a, the portion b, the portion c, and the portion d were 0.02mm, 0.06mm, 0.08mm, and 0.10mm, respectively, was manufactured.

Comparative example 2

A toothbrush of comparative example 2 was produced in the same manner as in example 1 except that mechanical polishing was performed so that the length L of the tapered portion formed in the brush was 3mm, the taper ratio L/H was 29%, and the diameters of the portion a, the portion b, the portion c, and the portion d of the head portion were 0.10mm, 0.16mm, 0.19mm, and 0.20mm, respectively.

Comparative example 3

A toothbrush of comparative example 3 was produced in the same manner as in example 5 except that mechanical polishing was performed so that the length L of the tapered portion formed in the brush was 3mm, the taper ratio L/H was 29%, and the diameters of the portion a, the portion b, the portion c, and the portion d of the head portion were 0.09mm, 0.12mm, 0.14mm, and 0.15mm, respectively.

Comparative example 4

A synthetic resin filament having a diameter of 0.19mm was produced using a resin containing nylon (100%) as a resin component, and using this synthetic resin filament, a bundle of bristles was implanted in a bristle base in the same manner as in example 1, and the distal end portions of the bristles were cut so that the bristle length H of the bristles became 10.5 mm. A toothbrush of comparative example 4 was produced in the same manner as in example 1, except that the length L of the tapered portion formed in the bristles was 1mm, the taper ratio L/H was 10%, and the diameters of the bristles at the portion a, the portion b, the portion c, and the portion d were 0.12mm, 0.19mm, and 0.19mm, respectively, and that mechanical polishing was performed.

The toothbrushes of examples 1 to 8 and comparative examples 1 to 4 were examined for surface roughness, cleanability, feeling of use, and durability by the following methods. The results are shown in tables 1 to 3.

(1) Surface roughness

As shown in fig. 1, 4 bristles implanted into a central region X of the central portion of the hair setting base and an outer region Y of the outer portion of the hair setting base were extracted, respectively, and arithmetic line roughness Ra was measured in regions a to D of 0.1mm to the hair setting base from respective portions a to D of 0.1mm, 0.5mm, 1.0mm and 2.0mm from the tips of the bristles toward the hair setting base by a laser microscope, and the maximum value, the minimum value and the average value of the arithmetic line roughness Ra in the regions a to D of the bristles in the central region X and the outer region Y were obtained, respectively. In the toothbrush of comparative example 1, the tip end portions of the bristles are immersed in the chemical solution containing the alkaline agent to form the tapered portions, and therefore the arithmetic roughness Ra in the outer region Y and the arithmetic roughness Ra in the central region X are substantially the same value. Therefore, the measurement of the arithmetic roughness Ra of the outer region Y of the toothbrush is omitted in comparative example 1. In table 3, the portion indicated by "+" indicates no measurement value because the brush bristles include portions that are not shaved off over the entire circumference.

(2) Cleaning (teeth integration)

The simulated plaque was attached to the upper first molar T1 of the jaw model, the jaw model was attached to the brushing simulator, and the toothbrush was attached to the brushing simulator so that the tip end portions of the bristles contacted the upper first molar T1. Then, the area including the first maxillary molar T1 was brushed at a stroke width of 20mm for a stroke in the longitudinal direction of the toothbrush with a stroke width of 20mm at a speed of 150 reciprocations for 1 minute for 2.5 seconds using a brushing simulator. Thereafter, as shown in fig. 5, the upper first molar tooth T1 of the jaw model was photographed from the cheek side, the photographed image was subjected to image analysis, the area of the simulated plaque was measured and calculated, and the ratio of the area on the tooth surface from which the simulated plaque was removed to the area on which the simulated plaque was previously attached was found as the plaque removal rate. Then, the case where the plaque removal rate was 95% or more was marked as "o" indicating good cleaning performance, the case where the plaque removal rate was 85% or more and less than 95% was marked as "Δ" indicating not so good cleaning performance, and the case where the plaque removal rate was less than 85% was marked as "x" indicating poor cleaning performance.

(3) Cleaning property (dental seam part)

Using the images captured as described above, the area of the simulated plaque in the region IP shown in fig. 5 by hatching, including the interdental portion between the upper first large molar tooth T1 and the two teeth on the right and left sides thereof, was measured and calculated, and the ratio of the area from which the simulated plaque was removed to the area of the region IP was determined as the plaque removal rate. Then, the case where the plaque removal rate was 70% or more was marked as "o" indicating good cleaning performance, the case where the plaque removal rate was 60% or more and less than 70% was marked as "Δ" indicating not so good cleaning performance, and the case where the plaque removal rate was less than 60% was marked as "x" indicating poor cleaning performance.

(4) Insertability (dental neck)

After the brushing as described above, in the region between the teeth and the gum, as shown in fig. 5, the length of the longest portion from which the plaque simulant is removed from the boundary (the neck portion) between the tooth T1 and the gum M toward the gum M is measured and determined as the insertability of the brush. The case where the longest length is 2.0mm or more is indicated by "o" which indicates good insertability, the case where the longest length is 1.5mm or more and less than 2.0mm is indicated by "Δ" which indicates not so good insertability, and the case where the longest length is less than 1.5mm is indicated by "x" which indicates poor insertability.

(5) Feeling of use (feeling of insertion, non-smoothness, tingling)

The 10 test subjects were brushed by a usual brushing method which was performed daily, the feeling of use was evaluated in 3 grades, the case where the feeling of use was strongly felt was evaluated as "o", the case where the feeling of use was ordinarily felt was evaluated as "Δ", the case where the feeling of use was not felt was evaluated as "x", and the grade which was evaluated the most was regarded as the feeling of use of the toothbrush. The insertion feeling is a feeling that the tip of the brush is inserted into a gap between the neck part of the tooth, the slit part, or the like at the time of brushing. The matte feel is as described above. Smooth feel means that when the teeth are touched with the tongue or the like after brushing, plaque, dirt, or the like is removed and the surface of the teeth is smooth. The tingling sensation is a sensation of a stimulation such as a tingling when the gum is touched by the distal ends of the brush hairs during brushing.

(6) Durability

In this case, the number of bristles extracted from 3 arbitrary bristle planting holes of the toothbrush (a) and the number of bristles in a state where the tips of the bristles are bent or crushed (B) were measured by immersing the toothbrush in hot water at 37 ℃ and applying a load of 300g while reciprocating the toothbrush 1 ten thousand, and the bristle durability index was calculated by the following formula, and a case where the bristle durability index was 0% or more and less than 10% was designated as "o", which indicates sufficient durability, a case where the bristle durability index was 10% or more and less than 25% was designated as "Δ", which indicates slightly poor durability, and a case where the bristle durability index was 25% or more was designated as "x", which indicates poor durability.

Hair durability index (%) - (B)/(a) ] x 100

[ TABLE 1 ]

[ TABLE 2 ]

[ TABLE 3 ]

As is apparent from tables 1 to 3, in the toothbrushes of examples 1 to 8, since the bristles are formed of filaments made of a resin material obtained by melt-mixing polybutylene terephthalate with polypropylene terephthalate, the durability of the bristles can be improved as compared with the toothbrush of comparative example 1 in which the bristles are formed of filaments of polybutylene terephthalate (100%).

Further, it is understood that when the tapered portion is formed by immersing the distal end portion of the brush in the chemical as in comparative example 1, the sharp distal end portion causes a strong tingling sensation and a reduced feeling of use, whereas when the tapered portion is formed by mechanical polishing as in examples 1 to 8, the rounded distal end portion of the brush causes a weak tingling sensation and a good feeling of use can be obtained.

In the toothbrushes according to examples 1 to 8, the ratio L/H of the length L of the tapered portion to the bristle length H is 30% or more, and is larger than the ratio L/H of the bristles in the toothbrushes according to comparative examples 2 to 4, so that the ratios of the diameters of the portion a, the portion b, the portion c, and the portion d on the tip end side portion of the bristles to the diameter of the filament (the maximum diameter Φ of the bristles) are smaller than the ratios of the diameters of the same portion a, the portion b, the portion c, and the portion d to the diameter of the filament in the toothbrushes according to comparative examples 2 to 4, respectively. This demonstrates that the insertion feeling can be obtained while ensuring high insertability to the slit part and the like and high cleanability to the slit part and the neck part. On the other hand, in the toothbrush of comparative example 1, the length L of the tapered portion was 30% or more of the bristle length H, but the ratio of the diameter at the portion a, the portion b, the portion c, and the portion d to the maximum diameter Φ was too small, the stiffness of the bristles at the tip portions of the bristles was weak, and the cleaning property of the neck portion and the insertion feeling were able to be obtained as in the toothbrushes of examples 1 to 8, but the cleaning property of the entire teeth and the crevice portion were lower than those of the toothbrushes of examples 1 to 8.

In the toothbrushes according to examples 1 to 8, the average value of the arithmetic line roughness Ra of the bristles implanted in the region X in the central portion of the bristle base is 1.45 μm or more, while the bristles implanted in the region X in the central portion of the bristle base are bristles having an arithmetic line roughness Ra in the region a closest to the tip side exceeding 1.5 μm, in the toothbrushes according to comparative examples 1 to 4, the maximum value of the arithmetic line roughness Ra in the region a is 1.50 μm as compared with comparative example 3, and the maximum value of the average value of the arithmetic line roughness Ra is 1.44 μm as compared with comparative example 2, for the bristles implanted in the region X in the central portion of the bristle base and the region Y in the outer portion of the bristle base. As described above, it is understood that the toothbrushes according to examples 1 to 8 have a relatively large arithmetic line roughness Ra in the region a, compared with the toothbrushes according to comparative examples 1 to 4, and thus have a sufficient matte feeling.

While the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and it goes without saying that the configuration can be changed within a range not departing from the gist of the present invention.

Claims (9)

1. A toothbrush in which a plurality of bristles made of synthetic resin filaments are implanted in a bristle base, characterized in that,

the filaments are formed by using a resin material obtained by melt-mixing a polyester resin other than polytrimethylene terephthalate,

a tapered portion formed by mechanical grinding is provided in a range of 30% to 70% of the length of the brush from the bristle base to the tip end portion of the brush from the tip end of the brush toward the bristle base,

the plurality of bristles implanted in the implanting seat include the following bristles: the arithmetic line roughness Ra in the area of 0.1mm from the 0.1mm part of the top end of the bristle toward the bristle base side exceeds 1.5 μm.

2. The toothbrush of claim 1,

among the plurality of bristles implanted in the central portion of the bristle base, the average value of the arithmetic line roughness Ra in a region 0.1mm away from a portion 0.1mm away from the tip of the bristle toward the bristle base is 1.45 [ mu ] m or more.

3. The toothbrush of claim 2, wherein,

the average value of the arithmetic line roughness Ra of the plurality of bristles implanted in the central part of the bristle base in the region of 0.1mm toward the bristle base from the 0.5mm, 1mm and 2mm points of the tips of the bristles toward the bristle base is all in the range of 1.5 to 3.0 [ mu ] m.

4. The toothbrush of claim 2 or 3,

the average value of the arithmetic line roughness Ra in the area of 0.1mm toward the hair-planted seat side from the 0.5mm portion, 1mm portion and 2mm portion of the top end of the bristle toward the hair-planted seat side is in the range of 1.5 to 2.5 μm, 1.5 to 2.1 μm and 1.7 to 2.5 μm, respectively, for the plurality of bristles implanted in the central portion of the hair-planted seat.

5. The toothbrush according to any one of claims 1 to 4,

the plurality of bristles implanted in the bristle base include the following bristles: the diameters of the bristles at respective portions, which are spaced apart from the top ends of the bristles by distances of 0.1mm, 0.5mm, 1mm and 2mm, are within the ranges of 15% -35%, 35% -75%, 45% -95% and 65% -100% of the maximum diameter of the bristles, respectively.

6. The toothbrush according to any one of claims 1 to 5,

the outer surface of the tapered portion is formed of a curved surface protruding outward.

7. The toothbrush according to any one of claims 1 to 6,

the tip end portions of the plurality of bristles implanted in the bristle holder are rounded.

8. The toothbrush according to any one of claims 1 to 7,

the length of the bristles implanted in the bristle base from the bristle base to the tip end portions of the bristles is 5mm to 12 mm.

9. The toothbrush according to any one of claims 1 to 8,

the polyester resin is polybutylene terephthalate.

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