Toothbrush

Abstract

To provide a technique for suppressing lead release from a toothbrush highly filled with inorganic substance powder.SOLUTION: A toothbrush includes a head part and a handle part, where bristle bundles fill bristle holes provided on a part of a surface of the head by driving a metal part. The head part is made of a resin composition containing a thermoplastic resin and inorganic substance powder, where a mass ratio of the thermoplastic resin to the inorganic substance powder is 50:50 to 10:90, the thermoplastic resin contains a polyolefin, the inorganic substance powder contains calcium carbonate, and a lead content per gram of the inorganic substance powder is 20 μg or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a toothbrush.

Background Art

[0002] In recent years, from the viewpoint of reducing environmental impact, attempts have been made to highly fill resin molded products with calcium carbonate (for example, Patent Document 1). Resin molded products highly filled with calcium carbonate generally have excellent mechanical properties and the like compared to the resin alone.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The resin molded products as described above can also be applied to daily necessities such as toothbrushes.

[0005] However, the inventor has found that in a toothbrush highly filled with calcium carbonate, water can penetrate from the bristle planting surface of the head portion through the tufts into the inside of the head portion, and among the impurities contained in calcium carbonate, especially lead can be released. This is presumably because when calcium carbonate coexists with the metal bristle retaining material (flat wire or round wire) of the head portion in water, calcium carbonate with a high ionization tendency dissolves, and along with this, lead is also released. Such elution and release can occur, for example, in the process from washing the head portion with tap water to natural drying.

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide a technique for suppressing the release of lead in a toothbrush highly filled with inorganic substance powder.

Means for Solving the Problems

[0007] The inventors of the present invention have found that the above problems can be solved by blending an inorganic substance powder that satisfies predetermined requirements regarding the lead content in a toothbrush highly filled with the inorganic substance powder, and have thus completed the present invention. More specifically, the present invention provides the following.

[0008] (1) A toothbrush comprising a head portion and a handle portion, bristle bundles are implanted into implantation holes provided in a part of the surface of the head portion by driving in a metal part, the head portion is made of a resin composition containing a thermoplastic resin and an inorganic substance powder, the mass ratio of the thermoplastic resin to the inorganic substance powder is 50:50 to 10:90, the thermoplastic resin contains a polyolefin resin, the inorganic substance powder contains calcium carbonate, the lead content per 1 g of the inorganic substance powder is 20 μg or less, Toothbrush.

[0009] (2) The toothbrush according to (1), wherein the polyolefin resin contains a polypropylene resin and / or a polyethylene resin.

[0010] (3) The toothbrush according to (1), wherein the inorganic substance powder contains heavy calcium carbonate.

[0011] (4) The toothbrush according to (1), wherein the arsenic content per 1 g of the inorganic substance powder is 3 μg or less.

[0012] (5) The toothbrush according to (3), wherein the heavy calcium carbonate is heavy calcium carbonate having an average particle diameter of 0.7 μm or more and 6.0 μm or less by the air permeability method according to JIS M-8511.

[0013] (6) The toothbrush according to (1), wherein the head portion and the handle portion are injection molded products.

[0014] (7) The toothbrush according to (1), wherein the metal part is a flat wire or a round wire.

[0015] (8) The toothbrush according to (1), wherein the metal part contains one or more metals selected from the group consisting of brass, aluminum, zinc, and stainless steel.

Advantages of the Invention

[0016] According to the present invention, a technique for suppressing the release of lead in a toothbrush highly filled with an inorganic substance powder is provided.

Embodiments for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited thereto.

[0018] <Toothbrush> The toothbrush according to one embodiment of the present invention satisfies the following requirements. · It includes a head part and a handle part. · Bristle bundles are implanted into the implantation holes provided on a part of the surface of the head part by driving in a metal part. · The head part is made of a resin composition containing a thermoplastic resin and an inorganic substance powder. · The mass ratio of the thermoplastic resin to the inorganic substance powder is 50:50 to 10:90. · The thermoplastic resin includes a polyolefin-based resin. · The inorganic substance powder includes calcium carbonate. · The lead content per 1 g of the inorganic substance powder is 20 μg or less.

[0019] A toothbrush generally has a head part where bristle bundles are implanted and a handle part extending from the head part. The bristle bundles are fastened to the head part using a metal part (flat wire or round wire) to form an implantation part.

[0020] A user of a toothbrush, for example, holds the handle part, inserts the head part into the oral cavity, and removes dirt by applying the tuft to teeth or the like. In many cases, the used toothbrush is washed with water (such as tap water) and then naturally dried and reused.

[0021] On the other hand, in recent years, from the viewpoint of reducing environmental impact, etc., in a toothbrush, attempts have been made to mold the handle (the head part and the handle part), etc. with a resin composition highly filled with calcium carbonate.

[0022] The present inventor was also promoting the development of a toothbrush using a resin composition highly filled with calcium carbonate. However, when washing the toothbrush, the present inventor found that water might penetrate from the tuft implantation surface of the head part into the head part through the tuft, and lead contained in the calcium carbonate might be released. When the present inventor further examined, it was speculated that such release was due to the elution of calcium carbonate with a high ionization tendency in water in the co - existence of the metal part used for the head part and calcium carbonate. The elution of calcium carbonate can also lead to the release of lead contained in the calcium carbonate. As described above, since a toothbrush is usually naturally dried after being washed with water, lead release may occur during this process. From the viewpoint of providing a highly safe toothbrush, the less lead release is, the more preferable it is.

[0023] Therefore, the present inventor came up with the idea that in a resin composition containing an inorganic substance powder containing calcium carbonate, the lead content per 1 g of the inorganic substance powder should be 20 μg or less.

[0024] In one embodiment of the present invention, "suppressing the release of lead" can be specified, for example, by less lead release from the head part of the toothbrush after washing with water or no release at all. Specifically, it can be specified by the method shown in the examples.

[0025] In one embodiment of the present invention, "lead" includes lead derived from an inorganic substance powder (particularly calcium carbonate) used as a raw material for the toothbrush. The form of lead is not particularly limited, and includes not only the single substance but also compounds (such as lead sulfide).

[0026] In one embodiment of the present invention, "consisting of component A" means substantially not containing components other than component A. In one embodiment of the present invention, "substantially not containing component B" includes, for example, an aspect of not containing component B at all.

[0027] Hereinafter, the configuration of the toothbrush according to one embodiment of the present invention will be described in detail.

[0028] (1) Structure of the toothbrush In one embodiment of the present invention, the toothbrush includes a head portion and a handle portion.

[0029] Each structure of the toothbrush can adopt any conventionally known structure.

[0030] In a preferred aspect of the present invention, the toothbrush meets the standards defined in "JIS S3016". "JIS S3016" discloses, as the structure of the toothbrush, one having a "handle" and "bristles" planted in the bristle planting portion provided on the handle. The "handle" refers not only to the gripping portion of the toothbrush but also to the whole including the bristle planting portion. The "bristles" are planted by bending the bristles and inserting them into the bristle planting holes provided in the bristle planting portion and pressing them with a metal wire or the like.

[0031] The head portion and the handle portion may have the same composition or may have different compositions from each other. However, at least the head portion is made of the resin composition described later.

[0032] The head portion and the handle portion may be an integrally molded product or may be a combination of separate molded products.

[0033] The forming method of the head part and the handle part is not particularly limited, but in a preferred embodiment, injection molding may be mentioned. A preferred embodiment of the present invention includes an embodiment in which the head part and the handle part are all injection molded products.

[0034] (1-1) Head part The head part has tufts of bristles implanted on its surface. The user of the toothbrush rubs the tufts of bristles against teeth, gums, etc. to remove dirt.

[0035] Normally, a recess (bristle implantation hole) is provided in a part of the surface of the head part. By using a metal part to fasten the tufts of bristles to this recess, the tufts of bristles are implanted in the head part. The metal part corresponds to a metal bristle-fixing material. Usually, by driving it in from above the tufts of bristles pushed into the bristle implantation holes, the tufts of bristles are fixed in the bristle implantation holes.

[0036] The size, shape, etc. of the bristle implantation holes are not particularly limited and can be appropriately set according to the configuration of the head part, the characteristics of the toothbrush user, etc.

[0037] The length, material, etc. of the tufts of bristles are not particularly limited, and any configuration used for cleaning teeth, gums, etc. can be adopted.

[0038] The configuration of the metal part is not particularly limited, and any configuration used in conventional toothbrushes can be adopted. Typical metal parts include flat wires and round wires. Examples of the material of the metal part include those containing one or more metals selected from the group consisting of brass, aluminum, zinc, and stainless steel. In a preferred embodiment of the present invention, the metal part is made of one or more metals selected from the group consisting of brass, aluminum, zinc, and stainless steel.

[0039] (1-2) Handle part The handle part corresponds to a gripping part extending from the head part. By gripping the handle part, the user of the toothbrush can apply the head part to a desired site.

[0040] In addition to the head part and the handle part, the handle of the toothbrush may include a part called the "neck part". In such an aspect, the head part is connected to the handle part via the neck part. However, the neck part and the handle part may be clearly distinct parts from each other, or may be integrated parts (that is, a state where the boundary between the neck part and the handle part is not clear).

[0041] (2) Resin composition The head part is made of a resin composition containing a thermoplastic resin and an inorganic substance powder in a mass ratio of 50:50 to 10:90.

[0042] (2-1) Thermoplastic resin The thermoplastic resin is not particularly limited except that it contains a polyolefin-based resin, and a resin that can be usually blended in a resin molded product can be adopted. The thermoplastic resin may be used alone or in combination of two or more.

[0043] (2-1-1) Types of thermoplastic resin The thermoplastic resin contains at least a polyolefin-based resin, and preferably consists of a polyolefin-based resin. Examples of thermoplastic resins other than polyolefin-based resins include polyester-based resins and polystyrene-based resins.

[0044] In one embodiment of the present invention, the "polyolefin-based resin" means a polyolefin-based resin having an olefin component unit as a main component. "Having an olefin component unit as a main component" means that the olefin component unit is contained in the polyolefin-based resin in an amount of 50% by mass or more (preferably 75% by mass or more, more preferably 85% by mass or more, still more preferably 90% by mass or more). Incidentally, the method for producing the polyolefin resin used in the present invention is not particularly limited, and any method such as a method using a Ziegler-Natta catalyst, a metallocene catalyst, a radical initiator (oxygen, peroxide, etc.) may be used.

[0045] Examples of the polyolefin resin include polypropylene resins and polyethylene resins. From the viewpoint that the thermoplastic resin easily exhibits the effects of the present invention and further easily realizes a good appearance and the like, it preferably contains a polypropylene resin and / or a polyethylene resin, and more preferably consists of a polypropylene resin and / or a polyethylene resin.

[0046] (2-1-2) Polypropylene resin The polypropylene resin in the present invention includes a resin in which the propylene component unit is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, and most preferably 80% by mass or more.

[0047] Examples of the polypropylene resin include polypropylene homopolymers (propylene homopolymers) and copolymers of propylene and other α-olefins (capable of copolymerizing with propylene). Examples of the "other α-olefins" include α-olefins having 4 to 10 carbon atoms (ethylene, 1-butene, isobutylene, 1-pentene, 3-methyl-1-butene, 1-hexene, 3,4-dimethyl-1-butene, 1-heptene, 3-methyl-1-hexene, etc.).

[0048] Examples of the propylene homopolymer include linear or branched polypropylene showing various stereoregularities (isotactic, syndiotactic, atactic, hemi-isotactic, etc.).

[0049] The copolymer of propylene may be any of polypropylene random copolymer (random copolymer), polypropylene block copolymer (block copolymer), binary copolymer, terpolymer, etc. Specifically, ethylene-propylene random copolymer, butene-1-propylene random copolymer, ethylene-butene-1-propylene random terpolymer, ethylene-propylene block copolymer, etc. may be mentioned.

[0050] Among the above polypropylene-based resins, a resin containing a polypropylene block polymer is preferred, and a resin composed of a polypropylene block polymer is more preferred.

[0051] (2-1-3) Polyethylene-based resin The polyethylene-based resin in the present invention includes a resin in which the ethylene component unit is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, and most preferably 80% by mass or more.

[0052] Examples of the polyethylene-based resin include high-density polyethylene (HDPE), low-density polyethylene (LDPE), medium-density polyethylene (MDPE), linear low-density polyethylene (LLDPE), ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, ethylene-propylene-butene-1 copolymer, ethylene-butene-1 copolymer, ethylene-hexene-1 copolymer, ethylene-4-methylpentene-1 copolymer, ethylene-octene-1 copolymer, etc.

[0053] As the polyethylene-based resin, a resin containing high-density polyethylene and / or linear low-density polyethylene is preferred, and a resin composed of high-density polyethylene and / or linear low-density polyethylene is more preferred.

[0054] The high-density polyethylene preferably has an MFR (190 °C, 21.6 kg) according to JIS K 6922-1 (ISO1133) of 5 g / 10 min or more and 15 g / 10 min or less, and more preferably 7 g / 10 min or more and 13 g / 10 min or less.

[0055] The linear low density polyethylene preferably has an MFR (190 ° C, 2.16 kg) according to JIS K 6922-1 (ISO1133) of 0.5 g / 10 min or more and 1.5 g / 10 min or less, more preferably 0.7 g / 10 min or more and 1.3 g / 10 min or less.

[0056] In the resin containing high density polyethylene and linear low density polyethylene, the mass ratio of the two (high density polyethylene: linear low density polyethylene) is preferably 90:10 to 50:50, more preferably 92:8 to 50:50, still more preferably 94:6 to 50:50.

[0057] (2-1-4) Blending amount of thermoplastic resin The content of the thermoplastic resin can be appropriately set according to the blending amount of the inorganic substance powder and the like.

[0058] From the viewpoint of moldability and the like, the content of the thermoplastic resin is preferably 10% by mass or more, more preferably 15% by mass or more, still more preferably 20% by mass or more, based on the resin composition.

[0059] From the viewpoint that a sufficient amount of inorganic substance powder can be blended and good mechanical properties can be easily achieved, the content of the thermoplastic resin is preferably 50% by mass or less, more preferably 45% by mass or less, still more preferably 40% by mass or less, based on the resin composition.

[0060] (2-2) Inorganic substance powder By blending an inorganic substance powder that satisfies predetermined requirements together with the thermoplastic resin, the release of lead in the head portion obtained from the resin composition can be suppressed.

[0061] (2-2-1) Type of inorganic substance powder The inorganic substance powder is not particularly limited except that it contains calcium carbonate, and those contained in ordinary resin molded products and the like can be adopted. The inorganic substance powder may be used alone as one kind of substance or in combination of two or more kinds of substances. However, a preferred embodiment of the present invention includes an embodiment in which only calcium carbonate powder is included as the inorganic substance powder from the viewpoint that the effects of the present invention are easily achieved.

[0062] (2-2-2) Calcium carbonate powder As the calcium carbonate powder, any of heavy calcium carbonate powder and light calcium carbonate powder may be used, or a combination thereof may be used. "Heavy calcium carbonate" is calcium carbonate obtained by mechanically pulverizing (dry method, wet method, etc.) a natural raw material (such as limestone) having CaCO 3 as a main component. "Light calcium carbonate" is calcium carbonate prepared by a synthetic method (such as a chemical precipitation reaction). Therefore, heavy calcium carbonate and light calcium carbonate are clearly distinguished from each other.

[0063] The difference between heavy calcium carbonate and light calcium carbonate can be specified, for example, from the circularity calculated based on the analysis of SEM images. The circularity of heavy calcium carbonate powder is, for example, in the range of 0.50 or more and 0.95 or less. The circularity of light calcium carbonate powder is, for example, approximately 1.00.

[0064] In one embodiment of the present invention, "circularity" is a value represented by the following formula and is an index of the degree of irregularity of particles. The closer the circularity is to "1" (the maximum value), the closer it is to a perfect circle, and the lower the numerical value, the higher the degree of irregularity. "Circularity" = (projected area of particles) / (area of a circle having the same perimeter as the projected perimeter of the particles)

[0065] Due to its manufacturing method, the shape of heavy calcium carbonate is not constant. Despite its low cost, it is easy to stably impart good mechanical properties to resin molded products. Therefore, preferred embodiments of the present invention include embodiments in which calcium carbonate contains heavy calcium carbonate powder or embodiments in which calcium carbonate consists of heavy calcium carbonate powder.

[0066] (2-2-3) Inorganic substance powder other than calcium carbonate Examples of the inorganic substance powder other than calcium carbonate include the following. Carbonates, sulfates, silicates, phosphates, or borates of metals (such as magnesium, aluminum, titanium, iron, zinc, etc.); Oxides of metals (such as calcium, magnesium, aluminum, titanium, iron, zinc, etc.); Hydrates of the above salts or oxides, etc.

[0067] Examples of the inorganic substance powder other than calcium carbonate include magnesium carbonate, zinc oxide, titanium oxide, silica, alumina, clay, talc, kaolin, aluminum hydroxide, magnesium hydroxide, aluminum silicate, magnesium silicate, calcium silicate, aluminum sulfate, magnesium sulfate, calcium sulfate, magnesium phosphate, barium sulfate, silica sand, carbon black, zeolite, molybdenum, diatomaceous earth, sericite, shirasu, calcium sulfite, sodium sulfate, potassium titanate, bentonite, graphite, etc.

[0068] The inorganic substance powder may be synthetic or derived from natural minerals.

[0069] (2-2-4) Trace components in the inorganic substance powder As described above, the main technical feature of the present invention lies in using, as the inorganic substance powder, one having a content of trace components within a predetermined range.

[0070] (2-2-4-1) Lead In one embodiment of the present invention, the content of lead per 1 g of the inorganic substance powder is 20 μg or less. The lower the content of lead, the easier it is to achieve the effects of the present invention. Per 1 g of the inorganic substance powder, it is preferably 18 μg or less, more preferably 15 μg or less. The lower limit of the lead content is not particularly limited, but per 1 g of the inorganic substance powder, it is preferably 0 μg or more.

[0071] (2-2-4-2) Other trace components The content of other trace components is not particularly limited. However, the higher the purity of the inorganic substance powder, the easier it is to achieve the effects of the present invention.

[0072] For example, when the content of arsenic per 1 g of the inorganic substance powder is preferably 3 μg or less, more preferably 2 μg or less, the safety of the present invention is likely to be enhanced.

[0073] (2-2-4-3) Method for adjusting the content of trace components The method for adjusting the content of trace components is not particularly limited. For example, the following can be mentioned. · Synthesis or collection of inorganic substance powder that satisfies the requirements of the present invention. · Blending of inorganic substance powder that does not satisfy any of the requirements of the present invention and inorganic substance powder that satisfies the requirements of the present invention.

[0074] (2-2-4-4) Method for measuring trace components The content of trace components contained in the inorganic substance powder can be specified by the method described in the 9th Edition of the Japanese Pharmacopoeia of Food Additives (Ministry of Health, Labour and Welfare, Consumer Affairs Agency) shown in the examples.

[0075] (2-2-5) Other conditions of the inorganic substance powder The inorganic substance powder can be in any form as long as it satisfies the above conditions for trace components.

[0076] The average particle size of the inorganic substance powder can be appropriately set according to the moldability of the toothbrush to be obtained, etc. However, from the viewpoint of easily realizing stable dispersibility and easily exhibiting homogeneous mechanical properties, the average particle size of the inorganic substance powder by the air permeability method according to JIS M-8511 is preferably 0.7 μm or more and 6.0 μm or less, more preferably 1.0 μm or more and 5.5 μm or less. The average particle size of the inorganic substance powder only needs to satisfy the above requirements for the whole inorganic substance powder.

[0077] In order to enhance the dispersibility and reactivity of the inorganic substance powder, the surface of the inorganic substance powder may or may not be surface-modified in advance according to a conventional method. Examples of the surface modification method include physical treatment methods (such as plasma treatment) and chemical treatment methods (such as methods using coupling agents or surfactants).

[0078] The shape of the inorganic substance powder is not particularly limited and may be any of particulate (spherical, irregular shape, etc.), flaky, granular, fibrous, etc.

[0079] (2-2-6) Blending amount of inorganic substance powder From the viewpoint of facilitating the enhancement of mechanical properties, the lower limit of the content of the inorganic substance powder is preferably 50% by mass or more, more preferably 52% by mass or more, still more preferably 54% by mass or more, and even more preferably 56% by mass or more with respect to the resin composition. From the viewpoint of moldability and the like, the upper limit of the content of the inorganic substance powder is preferably 90% by mass or less, more preferably 85% by mass or less, still more preferably 80% by mass or less, and even more preferably 75% by mass or less with respect to the resin composition.

[0080] From the viewpoint that even if the content is large, the release of lead can be suppressed, the content of calcium carbonate powder is preferably 90% by mass or more, more preferably 95% by mass or more with respect to the inorganic substance powder. The upper limit of the content of calcium carbonate powder is not particularly limited, but is preferably 100% by mass or less, more preferably 99% by mass or less with respect to the inorganic substance powder.

[0081] From the viewpoint that even if the content is large, the release of lead can be suppressed, the content of calcium carbonate powder is preferably 50% by mass or more, more preferably 60% by mass or more with respect to the resin composition. The upper limit of the content of calcium carbonate powder is not particularly limited, but is preferably 90% by mass or less, more preferably 80% by mass or less with respect to the resin composition.

[0082] Whether the inorganic substance powder contains calcium carbonate and its content can be determined by firing the resin molded product and performing ash analysis on it.

[0083] (2-3) Other components In the resin composition, other components other than the inorganic substance powder and the thermoplastic resin may or may not be blended within the range that does not inhibit the effects of the present invention.

[0084] As other components, any components that can be usually blended in a resin molded product can be adopted. Examples of such components include colorants, lubricants, dispersants, antistatic agents, antioxidants, heat stabilizers, ultraviolet absorbers, etc. The types and amounts of these components can be appropriately set according to the effects to be obtained.

[0085] The resin composition in a preferred embodiment of the present invention includes those composed only of a thermoplastic resin and an inorganic substance powder.

[0086] (2-4) Ratio of thermoplastic resin to inorganic substance powder In the resin composition, the mass ratio of the thermoplastic resin to the inorganic substance powder (thermoplastic resin: inorganic substance powder) is preferably 50:50 to 10:90, more preferably 45:55 to 15:85, and still more preferably 40:60 to 20:80. Thus, by making the ratio of the inorganic substance powder to the thermoplastic resin equal to or higher, it becomes easier to exhibit the effect of improving the mechanical properties by the inorganic substance powder.

[0087] (2-5) Manufacturing method of resin composition As the manufacturing method of the resin composition, conventionally known methods and conditions can be adopted according to the form, use, etc. of the resin composition.

[0088] The resin composition can be obtained, for example, by mixing, melt-kneading, etc. the constituent components. The machine for manufacturing the resin composition can be selected according to the form and use of the resin composition, etc., and examples include an extruder, a kneader, a Banbury mixer, a kneading machine (such as a twin-screw kneading machine).

[0089] The form of the resin composition is not particularly limited, and any form that can be formed into a desired resin molded product (such as a sheet, a container, etc.) can be adopted.

Examples

[0090] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0091] <Manufacture and Evaluation of Toothbrush> A toothbrush was manufactured by the following method, and the presence or absence and degree of release of lead, etc. were evaluated.

[0092] (1) Manufacture of Toothbrush Body By injection molding (integral molding), a toothbrush body having a head portion and a handle portion having the compositions shown in Tables 2 and 3 was manufactured. The toothbrush body has a structure defined in JIS S 3016:1995. Each material used in this example is as follows.

[0093] (1-1) Inorganic Substance Powder As the inorganic substance powder, calcium carbonate particles (heavy calcium carbonate particles) were used. The average particle diameter of the calcium carbonate particles by the air permeability method according to JIS M-8511 was 2.0 μm.

[0094] First, three types with different trace component contents (calcium carbonate purity) recovered from different mines were blended in various ratios to prepare inorganic powders 1 to 4 (Table 1). These inorganic powders 1 to 4 were used in the amounts shown in Tables 2 and 3. The content of trace components in calcium carbonate particles was measured in accordance with the section on "Calcium Carbonate" (pages 748 - 749) of the 9th Edition of the Japanese Pharmacopoeia of Food Additives (Ministry of Health, Labour and Welfare, Consumer Affairs Agency). This pharmacopoeia stipulates the methods for measuring trace components (lead, alkali metals and magnesium, hydrochloric acid-insoluble substances, and free alkali, etc.) contained in calcium carbonate.

[0095] In Table 1, the content of each trace component means the following. · Lead: The content of lead per gram of inorganic substance powder (unit: μg) · Arsenic: The content of arsenic per gram of inorganic substance powder (unit: μg)

[0096] [Table 1]

[0097] (1 - 2) Thermoplastic resin Any of the following thermoplastic resins (all corresponding to polyolefin resins) was used. Polypropylene resin (PP): Polypropylene block copolymer (melting point 160°C) Polyethylene resin (PE): Blend of HDPE and LLDPE (HDPE:LLDPE (mass ratio) = 70:30) Note that the MFR (190°C, 21.6 kg) of the above HDPE according to JIS K 6922 - 1 (ISO1133) is 7.5 g / 10 min. The MFR (190°C, 2.16 kg) of the above LLDPE according to JIS K 6922 - 1 (ISO1133) is 0.8 g / 10 min.

[0098] (2) Preparation of toothbrush In the implant holes provided in the head part of the toothbrush body, flat wires made of brass were driven in according to a conventional method, and tufts of hair (nylon bristles) were implanted to obtain a toothbrush.

[0099] (3) Release test Fifty toothbrushes of the same composition were prepared and subjected to the following release test. First, tap water (pH 5.8) was prepared. Only the entire head part or only the handle part of each toothbrush was immersed in tap water for 10 seconds and then pulled out of the tap water and left standing at room temperature for 2 hours. After standing, a water quality test kit was used to check for the presence and degree of lead release in the tap water, and it was evaluated according to the following criteria. The results are shown in the "Release" column of Tables 2 and 3.

[0100] <Evaluation Criteria for Lead Release Test> A: No lead release was observed in any of the 50 toothbrushes. B: Lead release was observed in 2 or fewer of the 50 toothbrushes. C: Lead release was observed in 3 or more of the 50 toothbrushes.

[0101] <Evaluation Criteria for Arsenic Release Test> A: No arsenic release was observed in any of the 50 toothbrushes. B: Arsenic release was observed in 2 or fewer of the 50 toothbrushes.

[0102]

Table 2

[0103]

Table 3

[0104] As shown in the table, in the toothbrush that meets the requirements of the present invention, lead release was suppressed.

[0105] Furthermore, when the arsenic content per 1 g of the inorganic substance powder was 3 μg or less, arsenic release was more stably suppressed.

[0106] In this example, heavy calcium carbonate was used as the inorganic substance powder, but the same tendency was observed with other inorganic substance powders (light calcium carbonate, talc, etc.).

[0107] In this example, flat wires made of brass were used, but the same tendency was recognized even for flat wires made of any of aluminum, zinc, and stainless steel.

Claims

1. A toothbrush comprising a head portion and a handle portion, wherein tufts are implanted into implantation holes provided in a part of the surface of the head portion by driving in a metal part, the head portion is made of a resin composition containing a thermoplastic resin and an inorganic substance powder, the mass ratio of the thermoplastic resin to the inorganic substance powder is 50:50 to 10:90, the thermoplastic resin contains a polyolefin-based resin, the inorganic substance powder contains calcium carbonate, the content of lead per 1 g of the inorganic substance powder is 20 μg or less, a toothbrush.

2. The toothbrush according to claim 1, wherein the polyolefin-based resin contains a polypropylene-based resin and / or a polyethylene-based resin.

3. The toothbrush according to claim 1, wherein the inorganic substance powder contains heavy calcium carbonate.

4. The toothbrush according to claim 1, wherein the content of arsenic per 1 g of the inorganic substance powder is 3 μg or less.

5. The toothbrush according to claim 3, wherein the heavy calcium carbonate is heavy calcium carbonate having an average particle diameter of 0.7 μm or more and 6.0 μm or less by an air permeability method according to JIS M-8511.

6. The toothbrush according to claim 1, wherein the head portion and the handle portion are injection molded products.

7. The toothbrush according to claim 1, wherein the metal part is a flat wire or a round wire.

8. The toothbrush according to claim 1, wherein the metal part contains one or more metals selected from the group consisting of brass, aluminum, zinc, and stainless steel.

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