toothbrush

Abstract

The present invention is to provide a toothbrush that maintains the shedding strength of the hair bundle, suppresses the breakage of the base and the poor appearance, and can achieve a further thinning of the head. The toothbrush is characterized in that the head is a thin head of 3.0 mm or less, which is obtained by molding a polyacetal resin with a weight average molecular weight of 130,000 or more. When the thickness of the above-mentioned hair-planting base, i.e., the base thickness, is set to T1 (mm), the hole depth of the hair-planting hole is set to U1 (mm), the depth from the hair-planting surface to the upper end of the implanted flat wire, i.e., the flat wire hair-planting depth, is set to H1 (mm), and the weight average molecular weight of the above-mentioned polyacetal resin is set to Mw, the following formula (1) is satisfied. (-18.5)+T1×7.0+U1×3.5+H1×(-10.0)+Mw×0.78×10 ‑5 ≥2.96···(1).

Description

Technical Field

[0001] The invention relates to a toothbrush formed by planting hair bundles by flat wires in a plurality of hair planting holes of a thin head. Background Art

[0002] The hair tufts are implanted in the hair implantation holes of the hair implantation base of the head of the toothbrush. In order to improve the operability in the oral cavity, the head and neck of the toothbrush have been thinned by studying the material of the resin or the specifications and shape of the hair implantation (for example, refer to Patent Document 1). Patent Document 1 proposes a scheme to thin the head by forming an appropriate combination of the length or width of the flat wire, the diameter and depth of the hair implantation holes, and the material of the resin.

[0003] However, it is also known from Patent Document 1 that when polyacetal resin (POM) is used as the resin material of the head, if the hair bundle is transplanted using a flat wire to maintain the shedding strength of the thin head, unfavorable conditions such as cracks (base cracking) or whitening may occur (see Example 8 in Table 2 of the document). That is, when POM is used as the head material, stable production cannot be performed unless the head thickness is set to be thick.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 5427486 Summary of the invention

[0007] Technical problem to be solved by the invention

[0008] Therefore, in view of the above situation, the technical problem to be solved by the present invention is to provide a toothbrush that can maintain the shedding strength of the bristle bundle, suppress the breakage of the base and the poor appearance, and achieve a further thinning of the head.

[0009] Technical solutions for solving technical problems

[0010] The present invention includes the following inventions.

[0011] [1] A toothbrush comprising a hair-planting base with hair-planting holes on the head, and hair bundles are implanted in each hair-planting hole of the hair-planting base by means of flat-wire hair-planting. The toothbrush is characterized in that the head is a thin head formed of a polyacetal resin having a weight-average molecular weight of 130,000 or more and having a thickness of 3.0 mm or less, and when the base thickness as the thickness of the hair-planting base is set to T1 (mm), the hole depth of the hair-planting holes is set to U1 (mm), the flat-wire hair-planting depth as the depth from the hair-planting surface to the upper end of the implanted flat wire is set to H1 (mm), and the weight-average molecular weight of the polyacetal resin is set to Mw, the following formula (1) is satisfied.

[0012] (-18.5)+T1×7.0+U1×3.5+H1×(-10.0)+Mw×0.78×10 -5 ≥2.96…(1)

[0013] [2] A toothbrush comprising a hair transplanting base with hair transplanting holes on the head, and hair bundles are transplanted in each hair transplanting hole of the hair transplanting base by means of flat wire hair transplanting. The toothbrush is characterized in that the head is a thin head formed of a polyacetal resin having a weight average molecular weight of 130,000 or more and having a thickness of 3.0 mm or less. When the thickness of the hair transplanting base is set to T1 (mm), the hole depth of the hair transplanting holes is set to U1 (mm), the flat wire hair transplanting depth as the depth from the hair transplanting surface to the upper end of the implanted flat wire is set to H1 (mm), and the weight average molecular weight of the polyacetal resin is set to Mw, the following formula (2) is satisfied.

[0014] (-13.3)+T1×6.2+U1×2.1+H1×(-8.05)+Mw×0.36×10 -5 ≥3.33…(2)

[0015] Effects of the Invention

[0016] According to the present invention described above, it is possible to maintain the shedding strength of the hair bundles while suppressing the pedestal breakage and poor appearance, thereby achieving further thinning of the head. Specifically, by making the head into a thin head with a thickness of less than 3.0 mm, the operability in the oral cavity is improved. In addition, by configuring as follows: the head is molded from a polyacetal resin having a weight average molecular weight of more than 130,000, the thickness of the hair implantation pedestal, i.e., the pedestal thickness, is set to T1 (mm), the hole depth of the hair implantation hole is set to U1 (mm), the depth from the hair implantation surface to the upper end of the implanted flat wire, i.e., the flat wire hair implantation depth, is set to H1 (mm), and the weight average molecular weight of the above-mentioned polyacetal resin is set to Mw, the following formula (1) is satisfied, and the pedestal breakage can be suppressed.

[0017] (-18.5)+T1×7.0+U1×3.5+H1×(-10.0)+Mw×0.78×10 -5 ≥2.96…(1)

[0018] In addition, by configuring as follows: the head is molded from a polyacetal resin having a weight average molecular weight of more than 130,000, the thickness of the hair implanting base, i.e., the base thickness, is set to T1 (mm), the hole depth of the hair implanting hole is set to U1 (mm), the depth from the hair implanting surface to the upper end of the implanted flat wire, i.e., the flat wire hair implanting depth, is set to H1 (mm), and the weight average molecular weight of the above-mentioned polyacetal resin is set to Mw, the following formula (2) is satisfied, and cracks in the base and poor appearance (occurrence of bumps and depressions) can also be reliably suppressed.

[0019] (-13.3)+T1×6.2+U1×2.1+H1×(-8.05)+Mw×0.36×10 -5 ≥3.33…(2) BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a cross-sectional view of a head of a toothbrush according to a representative embodiment of the present invention.

[0021] Figure 2 It is an explanatory diagram showing the hair implantation portion of the same head. DETAILED DESCRIPTION

[0022] Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0023] The toothbrush 1 of the present invention is as follows Figure 1 As shown, the thin head includes a hair planting base 5 having a plurality of hair planting holes 20, and hair bundles 4 are planted in each hair planting hole 20 using flat wires. The toothbrush 1 of this example can be a manual toothbrush in which the head, neck and handle are integrally formed of synthetic resin, or an electric toothbrush in which a toothbrush cleaning body including a head and a neck is connected to the end side of the main body portion of the grip portion as a built-in drive mechanism, and of course, it can also be in other forms.

[0024] The head 2 can be integrally molded from a polyacetal resin having a weight average molecular weight of more than 130,000. The polyacetal resin can have not only an amorphous part but also a crystalline part, and can be a homopolymer or a copolymer. The higher the weight average molecular weight, the higher the degree of crystallinity, so it is not easy to break and has a good appearance. The head 2 is constructed as a head formed by a thin hair implantation base 5 with a thickness (thickness) T1 of less than 3.0 mm. It is preferably constructed as a thin head with a thickness of less than 2.9 mm, more preferably less than 2.6 mm, and further preferably less than 2.5 mm. Regarding the thickness of the hair implantation base 5, i.e., the lower limit of the thickness T1, it is preferably more than 2 mm, and more preferably more than 2.2 mm. If it is less than 2 mm, it is difficult to ensure sufficient shedding strength. The thickness T1 at least involves the part of the hair implantation surface where the hair bundles 4 are implanted.

[0025] The hair implantation surface 21 on the ventral side of the protruding hair bundle 4 of the head 2 (hair implantation base 5) is formed with a plurality of hair implantation holes 20 with bottoms that are roughly circular in cross-section. The number and arrangement of the hair implantation holes 20 are not limited in any way in this example, and can be selected from an appropriate range based on various conditions such as the opening diameter, depth, longitudinal cross-sectional shape, the number of filaments in each hair bundle, and its material. For example, the opening diameter (inner diameter D1) is appropriately determined to be about 1.2 to 2.4 mm. The hair implantation holes 20 in this example are as follows: Figure 2 As shown, it is a straight cylindrical hole with a substantially circular cross section, and an inclined surface with a reduced diameter in a truncated cone shape is formed on the peripheral wall of the bottom.

[0026] The hole depth U1 of the hair implantation hole 20 is the depth from the opening of the hair implantation surface 21 to the bottom surface 200 of the hair implantation hole 20. The thickness T2 of the bottom, that is, the distance from the bottom surface 200 of the hair implantation hole to the back surface 22 of the head (hair implantation stand 5), is referred to as "under the hole ~ under the stand" in this specification. In addition, the hair implantation hole 20 can also be other shapes. From the perspective of maintaining good shedding strength of the hair bundle, it is preferred that the hole depth (U1) is set to be greater than 0.9 mm.

[0027] The distance between the hole and the platform (T2) is 0.15 mm or more, more preferably 0.2 mm or more, and even more preferably 0.25 mm or more. If the distance between the hole and the platform is 0.5 mm or more, the shedding strength of the hair bundle cannot be maintained in the thin head of the present invention, so the distance between the lower hole and the platform is preferably suppressed to less than 0.5 mm, and more preferably suppressed to less than 0.45 mm.

[0028] In each hair implantation hole 20, a plurality of filament bundles are tied and folded in half and then implanted using a flat wire 3. The material of the flat wire 3 is not particularly limited, and it can be a known material such as a metal or hard synthetic resin used in a normal toothbrush. The thickness of the flat wire 3 is set to be greater than 0.1 mm and less than 0.2 mm, and more preferably greater than 0.15 mm and less than 0.185 mm. If the thickness is thinner than 0.1 mm, it will deform during implantation and cannot maintain the shedding strength. If the thickness is greater than 0.21 mm, the head may be whitened or the base may be broken, especially in the case of a thin head.

[0029] The processing allowance of the flat wire 3 relative to the hair implantation hole 20 (the difference between the horizontal length L of the flat wire 3 orthogonal to the implantation direction and the hole diameter D1 of the hair implantation hole 20) is preferably set to be greater than +0.35mm and less than +0.6mm, and more preferably greater than +0.45mm and less than +0.6mm. If it is less than +0.35mm, the embedding amount is small and the shedding strength cannot be maintained. If it is greater than +0.6mm, it will cause deformation of the flat wire, and as a result, the shedding strength of the hair bundle or filament is reduced. If the flat wire 3 is implanted in a manner in which each end in the length direction is embedded only by the same amount, it becomes a state where the length is preferably greater than 0.175mm and less than 0.3mm relative to the peripheral wall of the hair implantation hole 20.

[0030] The cross-sectional area obtained by cutting the rectangular wire 3 at a plane perpendicular to the horizontal direction is set to 0.1 mm 2 Above and less than 0.3mm 2 , more preferably set to 0.12mm 2 Above 0.3mm 2 If the cross-sectional area is less than 0.1 mm 2, the flat wire bends. As a result, the shedding strength of one hair bundle or filament decreases. The cross-sectional shape is set to an oval shape in this example, with curved surfaces on the proximal end side and the distal end side in the implantation direction, and it is considered that no burden is imposed on the hair bundle 4. The thickness t of the flat wire 3 in this example is the thickness of the straight tube region of the portion excluding the curved surface portions at both ends.

[0031] The implantation of the flat wire 3 becomes Figure 2 as shown by the imaginary line. In this specification, the distance H1 from the hair-implanting surface 21 where the hair-implanting hole opens to the upper end of the implanted flat wire 3 is referred to as the "flat wire hair-implanting depth". In addition, the distance H2 from the same hair-implanting surface 21 to the lower end of the implanted flat wire 3, which is the implantation depth including the longitudinal dimension of the flat wire 3, is referred to as the "plus flat wire". Further, the distance H3 from the lower end of the flat wire to the bottom surface 200 of the hair-implanting hole is referred to as the "flat wire - bottom of the hole". From the aspect of preventing the pedestal from cracking, maintaining excellent appearance, and hair removal strength, it is preferable that the flat wire hair-implanting depth (H1) is set to a value between 0.07 mm and 0.5 mm. In addition, regarding the flat wire - bottom of the hole (H3), from the aspect of preventing the pedestal from cracking and maintaining a good appearance, it is preferable to ensure that it is 0.5 mm or more, and more preferably 0.58 mm or more.

[0032] The material of the filament is not particularly limited, and it can be artificial hair formed of resin materials such as nylon, polyester, and polyolefin, or natural hair such as pig hair. In addition, combinations thereof are also possible. Furthermore, cross-sectional shapes, cross-sectional sizes, lengths, the presence or absence of tapered shapes, etc. can widely adopt well-known forms.

[0033] Regarding the head 2 of the toothbrush 1 according to the present invention, with respect to the pedestal thickness T1 (mm), the hole depth U1 (mm) of the hair-implanting hole, the flat wire hair-implanting depth H1 (mm), and the weight-average molecular weight Mw of the polyoxymethylene resin, it is configured such that the value of X1 in the following formula (3) is 2.96 or more. When X1 is less than 2.96, there is a possibility of the pedestal cracking.

[0034] (-18.5)+T1×7.0+U1×3.5+H1×(-10.0)+Mw×0.78×10 -5 =X1…(3)

[0035] In addition, regarding the head 2 of the toothbrush 1 according to the present invention, with respect to the pedestal thickness T1 (mm), the hole depth U1 (mm) of the hair-implanting hole, the flat wire hair-implanting depth H1 (mm), and the weight-average molecular weight Mw of the polyoxymethylene resin, it is configured such that the value of X2 in the following formula (4) is 3.33 or more. When X2 is less than 3.33, there is a possibility of the pedestal cracking or appearance defects (occurrence of unevenness). If it is set to 3.33 or more, pedestal cracking and appearance defects (occurrence of unevenness) can be reliably suppressed.

[0036] (-13.3)+T1×6.2+U1×2.1+H1×(-8.05)+Mw×0.36×10 -5 =X2…(4)

[0037] As mentioned above, although embodiment of this invention was described, this invention is not limited to these forms at all, It is needless to say that this invention can be implemented in various forms within the range which does not deviate from the summary of this invention.

[0038] Example

[0039] <Base cracking and appearance evaluation>

[0040] Next, the platform thickness T1, hole depth U1, flat wire implantation depth H1, hole bottom to platform bottom T2, and weight average molecular weight Mw of polyacetal resin were changed respectively to make samples of thin heads with a platform thickness of less than 3.0 mm obtained by molding polyacetal resin, and the evaluations of platform cracks and appearance (convexoconcavities) were obtained as shown in Tables 1 to 8.

[0041] (sample)

[0042] The thickness of the platform T1, the hole depth U1, the flat wire implant depth H1, the hole to the platform T2, the flat wire to the hole bottom H3, the weight average molecular weight Mw of the polyacetal resin, the value of X1 obtained in the above mathematical formula (3), and the types of polyacetal resin "P1" to "P6" are prepared as shown in Tables 1 to 4. The inner diameter (opening) of the implant hole is set to 1.5 mm.

[0043] The polyacetal resin "P1" is a 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 elastic modulus 2800 MPa, flexural elastic modulus 2550 MPa).

[0044] In addition, the polyacetal resin "P2" is a polyacetal homopolymer (number average molecular weight (Mn) 55400, weight average molecular weight (Mw) 130000, z average molecular weight (Mz) 261000, MFR 25g / 10min, tensile modulus 3300Mpa, flexural modulus 3000Mpa). In addition, the polyacetal resin "P3" is a polyacetal homopolymer (number average molecular weight (Mn) 58200, weight average molecular weight (Mw) 143000, z average molecular weight (Mz) 301000, MFR 15g / 10min, tensile modulus 3100Mpa, flexural modulus 3000Mpa).

[0045] In addition, the polyacetal resin "P4" is a polyacetal homopolymer (number average molecular weight (Mn) 67100, weight average molecular weight (Mw) 184000, z average molecular weight (Mz) 471000, MFR 7g / 10min, tensile modulus 3300Mpa, flexural modulus 3100Mpa). In addition, the polyacetal resin "P5" is a polyacetal homopolymer (number average molecular weight (Mn) 85000, weight average molecular weight (Mw) 227000, z average molecular weight (Mz) 549000, MFR 2.5g / 10min, tensile modulus 3200Mpa, flexural modulus 3000Mpa). The polyacetal resin "P6" is a polyacetal copolymer (number average molecular weight (Mn) 24,800, weight average molecular weight (Mw) 141,000, z average molecular weight (Mz) 302,000, tensile modulus 2,850 MPa, flexural modulus 2,700 MPa).

[0046] Each hair bundle of the implanted hair has 21 to 23 filaments (22 on average), a diameter of 0.19 mm, a length of 29 mm, and is made of nylon. The implantation direction of the flat wire, i.e., the longitudinal length, is 1.2 mm, the transverse length orthogonal thereto is 2.0 to 2.05 mm (2.03 mm on average), and the thickness is 0.185 mm.

[0047] (Evaluation method of pedestal crack)

[0048] The pedestal cracks were visually determined on a 5-level scale. "5": No cracks. "4": There were holes with slightly visible shallow cracks. "3": Shallow cracks were visible in a large number of holes, but the holes were not connected. "2": Shallow cracks were observed in a large number of holes, and the holes were connected. "1": Cracks were visible (there were gaps between the cracks), or there were cracks that spanned multiple holes.

[0049] [Table 1]

[0050] Table 1: A01~A30 pedestal crack evaluation

[0051]

[0052] [Table 2]

[0053] Table 2: B01~B10 pedestal crack evaluation

[0054]

[0055] [Table 3]

[0056] Table 3: C01~C33 pedestal crack evaluation

[0057]

[0058] [Table 4]

[0059] Table 4: D01~D48 pedestal crack evaluation

[0060]

[0061] As shown in Tables 1 to 4, except for the case of P1 in which the weight average molecular weight Mw of the polyacetal resin was less than 130,000, the evaluation of the pedestal cracking could be maintained at "3" or higher as long as the value of X1 was 2.96 or higher.

[0062] In Tables 5 to 8, for the same samples, the value of X2 obtained by the above-mentioned mathematical formula (4) is shown instead of the value of X1, and the results of the appearance (concavity and convexity) evaluation are added in addition to the evaluation of the pedestal cracking.

[0063] (Appearance Evaluation Method)

[0064] Regarding the appearance, the appearance of the back of the head was judged according to the following 5-level criteria. "5": No unevenness. "4": Slightly visible unevenness. "3": Slight unevenness can be felt when touched with a finger. "2": Unevenness can be felt when touched with a finger. "1": There are unevenness to the extent that it can be felt when touched with a finger.

[0065] [Table 5]

[0066] Table 5: A01~A30 concave-convex evaluation

[0067]

[0068] [Table 6]

[0069] Table 6: Evaluation of cracks and unevenness of B01 to B10 pedestals

[0070]

[0071] [Table 7]

[0072] Table 7: Evaluation of cracks and unevenness of C01 to C33 pedestals

[0073]

[0074] [Table 8]

[0075] Table 8: Evaluation of cracks and unevenness of D01 to D48 pedestals

[0076]

[0077] As shown in Tables 5 to 8, except for sample P1 in which the weight average molecular weight Mw of the polyacetal resin was less than 130,000, as long as the value of X2 was 3.33 or more, the evaluation of the pedestal crack and the evaluation of the appearance (concavity and convexity) could be maintained at "3" or more.

[0078] Explanation of symbols

[0079] 1 toothbrush

[0080] 2 Head

[0081] 3 Flat wire

[0082] 4 hair bundles

[0083] 5 hair transplanting pedestal

[0084] 20 Pore transplantation

[0085] 21 Hair transplanted surface

[0086] 22 Back

[0087] D1 The diameter of the implant hole

[0088] H1 Depth from the tufting surface to the top of the flat wire ("flat wire tufting depth")

[0089] H2 Depth from the hair-planting surface to the bottom of the flat line ("additional flat line")

[0090] H3 Distance from the bottom of the flat line to the bottom of the implant hole ("flat line ~ hole bottom")

[0091] T1: Thickness of the head (hair transplanting base) (“base thickness”)

[0092] T2 Thickness of the bottom of the transplanted pore ("under the pore ~ ​​under the stage")

[0093] U1 hole depth of implant hole

[0094] L is the horizontal length of the flat wire.

Claims

1. A toothbrush, comprising a hair planting base with hair planting holes on the head, wherein hair bundles are planted in each hair planting hole of the hair planting base by flat wire hair planting, wherein the toothbrush is characterized in that: The head is a thin head formed of polyacetal resin having a weight average molecular weight of 130,000 or more and having a thickness of 3.0 mm or less. The depth of the implant hole is more than 0.9mm. The flat wire implantation depth, which is the depth from the implantation surface to the upper end of the implanted flat wire, is 0.07 mm to 0.5 mm. The distance from the bottom of the hair transplant hole to the back of the head is 0.15mm or more and less than 0.5mm. The distance from the bottom of the flat wire to the bottom of the implant hole is more than 0.5mm. The thickness of the flat wire is 0.1mm or more and 0.2mm or less. The processing allowance of the flat wire for implanting holes is more than +0.35mm and less than +0.6mm. The cross-sectional area of ​​the flat wire cut at a plane perpendicular to the horizontal direction is 0.1 mm 2 Above and less than 0.3mm 2 , When the thickness of the hair implantation base is set to T1, the hole depth of the hair implantation hole is set to U1, the flat wire hair implantation depth is set to H1, the weight average molecular weight of the polyacetal resin is set to Mw, and the values ​​of T1, U1 and H1 are expressed in units of mm, the following formula (1) is satisfied: (-18.5)+T1×7.0+U1×3.5+H1×(-10.0)+Mw×0.78×10 -5 ≥2.96 …(1)。 2. A toothbrush comprising a hair planting base with hair planting holes on the head, wherein hair bundles are planted in each hair planting hole of the hair planting base by flat wire hair planting, wherein the toothbrush is characterized in that: The head is a thin head formed of polyacetal resin having a weight average molecular weight of 130,000 or more and having a thickness of 3.0 mm or less. The depth of the implant hole is more than 0.9mm. The flat wire implantation depth, which is the depth from the implantation surface to the upper end of the implanted flat wire, is 0.07 mm to 0.5 mm. The distance from the bottom of the hair transplant hole to the back of the head is 0.15mm or more and less than 0.5mm. The distance from the bottom of the flat wire to the bottom of the implant hole is more than 0.5mm. The thickness of the flat wire is 0.1mm or more and 0.2mm or less. The processing allowance of the flat wire for implanting holes is more than +0.35mm and less than +0.6mm. The cross-sectional area of ​​the flat wire cut at a plane perpendicular to the horizontal direction is 0.1 mm 2 Above and less than 0.3mm 2 , When the thickness of the hair implantation base is set to T1, the hole depth of the hair implantation hole is set to U1, the flat wire hair implantation depth is set to H1, the weight average molecular weight of the polyacetal resin is set to Mw, and the values ​​of T1, U1 and H1 are expressed in units of mm, the following formula (2) is satisfied: (-13.3)+T1×6.2+U1×2.1+H1×(-8.05)+Mw×0.36×10 -5 ≥3.33 …(2)。

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