JP7348539B2 - toothbrush - Google Patents

Description

The present invention relates to a toothbrush in which tufts of hair are planted in a plurality of bristle holes in a thin head using a flat wire.

The toothbrush has bristle bundles implanted in the bristle holes of the bristle table in the head. In order to improve operability in the oral cavity, efforts have been made to make the head and neck parts of toothbrushes thinner by considering the resin material, flocking specifications, shape, etc. (for example, Patent Document 1 reference.). Patent Document 1 proposes making the head portion thinner by appropriately combining the length and width of the flat wire, the diameter and depth of the tufting hole, the material of the resin, etc.

However, as can be seen from Patent Document 1, when polyacetal resin (POM) is used as the resin material for the head part, cracks occur when the hair strands are implanted into the thin head part while maintaining the pull-out strength using flat wires. Problems such as table cracking) and whitening occur (see Example 8 of Table 2). That is, when POM is used as the material for the head portion, stable production cannot be achieved unless the head thickness is set thick.

Patent No. 5427486

Therefore, in view of the above-mentioned situation, the present invention aims to provide a toothbrush that maintains the strength of hair bundle removal, suppresses cracking of the base and poor appearance, and allows the head portion to be made even thinner. It is in the point of doing.

The present invention includes the following inventions.
(1) A toothbrush having a tufting stand having tufting holes in the head part, in which bristle bundles are implanted by driving a flat wire into each tufting hole of the tufting stand, and the head part is made of polyacetal resin having a number average molecular weight of 50,000 or more. A toothbrush characterized in that the head is molded and has a thin head with a maximum thickness of 3.0 mm or less, and the thickness of the bottom of each tufting hole of the tufting stand is 0.15 mm or more and less than 0.5 mm.

(2) The toothbrush according to (1), wherein the thickness of the bottom of each tuft hole is 0.2 mm or more.

(3) The toothbrush according to (1) or (2), excluding those in which the maximum thickness of the tufting stand is 2.2 mm or less and the thickness of the bottom of the tufting hole is 0.25 mm or less.

(4) The toothbrush according to any one of (1) to (3), wherein the depth of each tuft hole is 1.95 mm or more.

According to the present invention as described above, while maintaining the strength of the hair bundle to come off, cracking of the base and poor appearance can be suppressed, and the head portion can be further made thinner.

1 is a plan view showing a toothbrush according to a typical embodiment of the present invention. Similarly, a side view of the toothbrush. Similarly, a cross-sectional view of the head portion of the toothbrush. FIG. 2 is an explanatory diagram showing the flocked portion of the head portion. Graph showing the single hair pulling strength and single hair pulling strength of each sample. Similarly, a graph showing the single hair pulling strength and single hair pulling strength of each sample. Similarly, a graph showing the single hair pulling strength and single hair pulling strength of each sample. Similarly, a graph showing the single hair pulling strength and single hair pulling strength of each sample. Similarly, a graph showing the single hair pulling strength and single hair pulling strength of each sample. Similarly, a graph showing the single hair pulling strength and single hair pulling strength of each sample. Similarly, a graph showing the single hair pulling strength and single hair pulling strength of each sample. Similarly, a graph showing the single hair pulling strength and single hair pulling strength of each sample. Similarly, a graph showing the single hair pulling strength and single hair pulling strength of each sample.

Next, embodiments of the present invention will be described in detail based on the accompanying drawings.

As shown in FIGS. 1 to 3, the toothbrush 1 according to the present invention has a thin head portion 2 and a bristle-planting stand 5 having a plurality of bristle-planting holes 20. was planted. The toothbrush 1 of this example is a manual toothbrush in which a head portion 2, a neck portion 11, and a handle portion 12 are integrally molded from synthetic resin. However, the present invention is not limited to such a manual toothbrush, but also includes an electric toothbrush in which a toothbrush cleaning body consisting of a head part and a neck part is connected to the distal end side of a main body part serving as a grip part that has a built-in drive mechanism. However, of course, other forms are also possible.

The head portion 2 is integrally molded together with the neck portion 11 and the handle portion 12 from polyacetal resin. The head portion 2 is configured as a head consisting of a thin flocking table 5 having a thickness (base thickness) T1 of 3.0 mm or less. The thin head is preferably 2.9 mm or less, more preferably 2.6 mm or less, and even more preferably 2.5 mm or less. The lower limit of the base thickness T1, which is the thickness of the flocking base 5, is preferably 2 mm or more, and more preferably 2.2 mm or more. If it is less than 2 mm, it will be difficult to ensure sufficient pull-out strength. The base thickness T1 relates to at least the part of the flocking surface where the hair bundles 4 are planted.

A plurality of bottomed tuft holes 20 having a substantially circular cross section are formed on the ventral tuft surface 21 of the head portion 2 (the tufting table 5) from which the bristle bundles 4 are protruded. The number of tuft holes 20, arrangement form, etc. are not limited to this example, and may be appropriate depending on various conditions such as opening diameter, depth, longitudinal cross-sectional shape, number of filaments per tuft, and material. selected from a range. For example, the opening diameter (inner diameter D1) is appropriately determined to be about 1.2 to 2.4 mm. As shown in FIG. 4, the tufting hole 20 of this example is basically a straight hole with a circular cross section, and a truncated conical inclined surface with a reduced diameter is formed on the bottom peripheral wall.

The hole depth U1 of the tufting hole 20 is the depth from the opening of the tufting surface 21 to the bottom surface 200 of the tufting hole 20. In this specification, the bottom thickness T2, that is, the distance from the bottom surface 200 of the tufting hole to the back surface 22 of the head section (the tufting table 5), is referred to as "under the hole to under the table." Note that the tufted holes 20 may have other shapes.

A hair bundle made by bundling a plurality of filaments and folding them in half is planted in each hair planting hole 20 using a flat wire 3. The material of the flat wire 3 is not particularly limited, and may be any known material used in general toothbrushes, such as metal or hard synthetic resin. The thickness of the flat wire 3 is set to 0.1 mm or more and 0.2 mm or less, more preferably 0.15 mm or more and 0.185 mm or less. If the thickness is less than 0.1 mm, it will deform during driving and the pull-out strength cannot be maintained. If the thickness is 0.21 mm or more, there is a risk that the head portion will whiten or the base may crack, especially in the case of a thin head.

The hanging allowance of the flat wire 3 to the tufting hole 20 (the difference in the length L of the flat wire 3 in the lateral direction perpendicular to the driving direction with respect to the hole diameter D1 of the tufting hole 20) is preferably +0.35 mm or more and +0.6 mm or less, More preferably, it is set to +0.45 mm or more and +0.6 mm or less. If it is smaller than +0.35 mm, the amount of biting is small and the pull-out strength cannot be maintained. If it is larger than +0.6 mm, the flat wire will be deformed, and as a result, the pull-out strength of a hair bundle or a single filament will decrease. If each end in the length direction of the flat wire 3 is driven in by the same amount, each ends of the flat wire 3 will be driven into the peripheral wall of the tufting hole 20 by a length of preferably 0.175 mm or more and 0.3 mm or less.

The cross-sectional area taken along a plane perpendicular to the horizontal direction of the flat line 3 is set to 0.1 mm ² or more and less than 0.3 mm ² , more preferably 0.12 mm ² or more and 0.3 mm ² or less. If the cross-sectional area is smaller than 0.1 mm ² , the flat wire will be bent, and as a result, the pull-out strength of a hair bundle or a single filament will be reduced. In this example, the cross-sectional shape is elliptical, with curved surfaces on the base end side and the distal side in the driving direction, so as not to place any burden on the hair bundle 4. The thickness t of the flat wire 3 in this example is the thickness of the straight region excluding the curved portions at both ends.

The implantation of the flat line 3 is as shown in the imaginary line in FIG. In this specification, the distance H1 from the flocking surface 21 where the flocking holes open to the upper end of the driven flat wire 3 is referred to as "flat wire implantation depth." Similarly, the distance H2 from the flocked surface 21 to the lower end of the flat wire 3 that has been driven in is referred to as the driving depth that includes the vertical dimension of the flat wire 3, and is referred to as a "plus flat wire." Furthermore, the distance H3 from the lower end of the flat line to the bottom surface 200 of the tufting hole is referred to as "flat line to hole bottom."

The material of the filament is not particularly limited, and may be artificial hair made of a resin material such as nylon, polyester, or polyolefin, or natural hair such as pig hair. Alternatively, these may be combined. In addition, a wide range of known forms can be adopted, including the cross-sectional shape, cross-sectional size, length, and presence or absence of a tapered shape.

Although the embodiments of the present invention have been described above, the present invention is not limited to these forms in any way, and it goes without saying that the present invention can be implemented in various forms without departing from the gist of the present invention.

Below, Examples 1 to 40 of the toothbrush head according to the present invention and Comparative Examples 1 to 9 of the toothbrush head in which the molecular weight of the polyacetal resin as the material resin is relatively small are described below. In addition to preparing multiple samples with different depths (Examples 1 to 4 and Comparative Example 1, the flat wire driving depth was only 0.6 mm), we also examined the cracks in the flocking table for each sample of each Example and Comparative Example. , the results of evaluating the appearance, and the results of measuring the shedding strength of one hair bundle and the shedding strength of one filament, respectively, will be explained.

(sample)
The structure of the head portion (fleeting stand) of the Examples and Comparative Examples was the structure of the typical embodiment shown in FIGS. 1 to 4, and five types of polyacetal resins (POM) were used as the material of the head portion.
Specifically, Examples 1, 5, 9, 13, 17, 21, 25, 29, 33, and 37 were polyacetal homopolymers (number average molecular weight (Mn) 55400, weight average molecular weight (Mw) 130000, z average In Examples 2, 6, 10, 14, 18, 22, 26, 30, 34, and 38, polyacetal homopolymer ( Number average molecular weight (Mn) 58200, weight average molecular weight (Mw) 143000, z average molecular weight (Mz) 301000, MFR 15 g/10 min, tensile modulus 3100 Mpa, flexural modulus 3000 Mpa).

In addition, Examples 3, 7, 11, 15, 19, 23, 27, 31, 35, and 39 are polyacetal homopolymers (number average molecular weight (Mn) 67100, weight average molecular weight (Mw) 184000, z average molecular weight (Mz ) 471000, MFR7g/10min, tensile modulus 3300Mpa, flexural modulus 3100Mpa). Comparative Examples 1 to 9 used polyacetal copolymer ( Number average molecular weight (Mn) 24900, weight average molecular weight (Mw) 122000, z average molecular weight (Mz) 247000, MFR 27 g/10 min, tensile modulus 2800 Mpa, flexural modulus 2550 Mpa).

The dimensions of the thickness of the flocking table (base thickness) and the thickness of the bottom of the flocking hole (from the bottom of the hole to the bottom of the table) of each example and comparative example are as described in Tables 1 to 10 (Tables 11 to 20). It was set to The difference between these dimensions is the depth of the tufted hole. Further, the inner diameter (opening) of the tufted hole was 1.5 mm.

The number of filaments per hair bundle to be transplanted was 21 to 23 (average 22), the diameter was 0.19 mm, the length was 29 mm, and the material was nylon. The length of the flat wire used for driving in the vertical direction, which is the driving direction, is 1.2 mm, the length in the horizontal direction perpendicular to this is 2.0 to 2.05 mm (average 2.03 mm), and the thickness is 0.185 mm. And so. The driving depth of the flat wire was 0.4 mm/0.5 mm/0.6 mm/0.7 mm/0.8 mm as shown in Tables 1 to 10 (Tables 11 to 20).

(Base cracking, appearance evaluation)
Each of the samples of the above Examples and Comparative Examples was visually evaluated for cracking and appearance. Base cracking is determined using the following five criteria. "5": No crack. "4": There are holes with slightly thin cracks. "3": Thin cracks are seen in many holes, but the holes are not connected. "2": Thin cracks were observed in many holes, and the holes were connected. "1": Cracks (there are gaps between cracks) are visible, or there are cracks that span multiple holes. The evaluation results are shown in Tables 1 to 10.

The appearance is judged using the following five criteria. "5": No unevenness. "4": Slight unevenness is visible. "3": Slight unevenness is felt when touched with a finger. "2": When touched with a finger, unevenness is felt. "1": There is unevenness to the extent that you can feel it getting caught when you touch it with your finger. The evaluation results are shown in Tables 11 to 20.

(Measurement of pull-out strength of one hair bundle/one filament)
The shedding strength of one hair bundle was determined by grasping the hair bundle per tuft hole with a special instrument for samples with specific flat wire implantation depths of each of the Examples and Comparative Examples shown in Tables 21 to 29. The maximum tensile stress (N) until the hair bundle comes off from the tufting hole was measured using an Autograph manufactured by Co., Ltd. (at a tensile speed of 20 mm/min) (n=15), and the values were taken as the average value. The measurement results are shown in Tables 21 to 29 and FIGS. 5 to 13.

In addition, the pull-out strength of a single filament was determined by grasping one filament with a special instrument for samples with specific flat wire implantation depths of each of the Examples and Comparative Examples shown in Tables 21 to 29, and using an Autograph also manufactured by Shimadzu Corporation. The maximum tensile stress (N) until one filament comes out from the tufted hole was measured (at a tensile speed of 20 mm/min) (n=15), and the values were taken as the average value. The measurement results are shown in Tables 21 to 29 and FIGS. 5 to 13.

(Consideration)
From the evaluation results of the cracking and appearance of each sample of Examples 1 to 8 and Comparative Examples 1 and 2 (Tables 1, 2, and 12), the higher the number average molecular weight of the polyacetal resin, the harder it is to crack. It can be seen that the appearance also improves. In addition, if Examples 1 to 8 molded from polyacetal resin with a number average molecular weight of 50,000 or more have a depth of 0.15 mm or more from the bottom of the hole to the bottom of the table even if the table is thin, it is sufficient to withstand commercialization with an evaluation of "3" or higher. It is possible to achieve a product with few cracks (Example 4), and it is possible to ensure an appearance of "3" or higher.

In particular, as shown in Table 2, if the distance from the bottom of the hole to the bottom of the table is 0.25 mm or more, the samples of Examples 5 to 8 with a number average molecular weight of 50,000 or more will have a high table crack rating of "4" or more. As for the evaluation and the shedding strength, as shown in Table 21 and Figure 5, the hair pulling strength per plant is 20N or more, and the single hair pulling strength is 2.5N or more (Example 7). It can be seen that in a thin head having a thickness of 3.0 mm or less, the thickness of the bottom of each tufting hole of the tufting table is 0.15 mm or more, more preferably 0.2 mm or more, and still more preferably 0.25 mm or more.

In addition, as can be seen from Tables 3 to 10 and Tables 13 to 20, if the base thickness is 2.30 mm or more and the distance from the bottom of the hole to the bottom of the base is 0.25 mm or more, all the examples with a number average molecular weight of 50,000 or more can be obtained. A rating of "5" is obtained for both the cracking of the base and the appearance. However, if the distance from the bottom of the hole to the bottom of the stand is 0.5 mm or more, the hair pulling strength per plant falls below 20N in all Examples (Examples 33 to 40), so if the distance from the bottom of the hole to the bottom of the stand is less than 0.5 mm, Preferably, it is suppressed to 0.45 mm or less.

In the case of a thin head like the one of the present invention, if the distance from the bottom of the hole to the bottom of the stand is 0.5 mm or more, it becomes impossible to ensure the depth of the tufted holes, and it is found that the hair pulling strength cannot be maintained. Specifically, as can be seen from the results in Tables 24 to 29 and Figures 8 to 13, if the hole depth is 0.95 mm or more, sufficient pull-out strength can be maintained for each hair bundle/filament. (Hair pulling strength per hair is 20N or more, single hair pulling strength is 2.5N or more).

Regarding the flat wire driving depth, good results are obtained in terms of cracking, appearance, and hair removal strength when the flat wire driving depth is between 0.4 mm and 0.8 mm. ~It is preferable to ensure that the bottom of the hole is 0.2 mm or more, more preferably 0.25 mm or more, in order to prevent cracking and maintain a good appearance.

1 Toothbrush 2 Head part 3 Flat wire 4 Hair bundle 5 Hair transplanting stand 11 Neck part 12 Handle part 20 Hair transplanting hole 21 Hair transplanting surface 22 Back surface D1 Hole diameter of the tufting hole H1 Depth from the bristle surface to the top of the flat wire ("Flat wire driving"depth")
H2 Depth from the flocked surface to the bottom of the flat line (“plus flat line”)
H3 Distance from the bottom of the flat line to the bottom of the tufting hole (“flat line to hole bottom”)
T1 Thickness of the head (flocking table) (“stand thickness”)
T2 Thickness at the bottom of the tufting hole (“under the hole to under the stand”)
U1 Depth of tufted hole L Horizontal length of flat wire

Claims (3)

A toothbrush having a tufting stand having tufting holes in the head part, in which bristle bundles are implanted by driving a flat wire into each tufting hole of the tufting stand,
The head portion is a thin head molded from a polyacetal homopolymer having a number average molecular weight of 50,000 or more and has a thickness of 2.3 mm or more and 3.0 mm or less,
The thickness of the bottom of each tufting hole of the tufting table is 0.2 mm or more and less than 0.5 mm,
The thickness of the flat wire is 0.1 to 0.2 mm,
The length of the flat wire is +0.35 mm or more and +0.6 mm or less,
The opening diameter (inner diameter) of the tufting hole is 1.2 mm or more and 2.4 mm or less,
The horizontal length of the flat wire perpendicular to the driving direction is 1.55 mm to 3 mm,
The hair pulling strength of one plant is 20N or more,
A toothbrush that also satisfies the following (a) and (b) .
(a) The driving depth of the flat wire, which is the distance from the flocked surface to the upper end of the flat wire, is 0.8 mm or less.
(b) The driving depth including the vertical dimension along the driving direction of the flat wire, which is the distance from the flocked surface to the lower end of the flat wire, is 2.0 mm or less . The toothbrush according to claim 1, having a single hair pulling strength of 2.5 N or more. The toothbrush according to claim 1 or 2, wherein the depth of each tufting hole is 1.95 mm or more.

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