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 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 present 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 bristle bundles into the inside of the head portion, and among the impurities contained in calcium carbonate, in particular, lead can be released. This is presumably because when calcium carbonate coexists with a metal bristle retaining material (flat wire or round wire) in the head portion in water, calcium carbonate with a high ionization tendency elutes, 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 with respect to the lead content in a toothbrush highly filled with the inorganic substance powder, and have completed the present invention. More specifically, the present invention provides the following.

[0008] (1) A toothbrush comprising a head portion and a handle portion, For the implanting holes provided in a part of the surface of the head portion, the tufts of bristles are implanted 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 mainly 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 resin composition according to (1), wherein the content of the calcium carbonate is 80% by mass or more with respect to the inorganic substance powder.

[0011] (4) The toothbrush according to (1), wherein the inorganic substance powder contains heavy calcium carbonate.

[0012] (5) The toothbrush according to (1), wherein the arsenic content per 1 g of the inorganic substance powder is 3 μg or less.

[0013] (6) The toothbrush according to (4), wherein the heavy calcium carbonate has an average particle diameter of 0.7 μm or more and 6.0 μm or less as measured by the air permeability method according to JIS M-8511:2014.

[0014] (7) The toothbrush according to (1), wherein the head portion and the handle portion are injection molded products.

[0015] (8) The toothbrush according to (1), wherein the metal part is a flat wire or a round wire.

[0016] (9) 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

[0017] 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

[0018] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited thereto.

[0019] <Toothbrush> A toothbrush according to an embodiment of the present invention satisfies the following requirements. · It includes 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 mainly contains a polyolefin-based resin. · The inorganic substance powder contains calcium carbonate. · The lead content per 1 g of the inorganic substance powder is 20 μg or less.

[0020] A toothbrush usually has a head portion on which bristles are attached and a handle portion extending from the head portion. The bristles are attached to the head portion using a metal portion (flat or round wire) to form the bristles.

[0021] A user of a toothbrush, for example, grasps the handle, places the head in the mouth, and applies the bristles to the teeth, etc. to remove dirt. In many cases, toothbrushes are washed with water (tap water, etc.), naturally dried, and then reused.

[0022] On the other hand, in recent years, from the viewpoint of reducing the environmental load, etc., attempts have been made to mold toothbrush handles (heads and handles) from resin compositions highly filled with calcium carbonate.

[0023] The present inventors, while developing a toothbrush using a resin composition highly loaded with calcium carbonate, discovered that when the toothbrush is washed, water may penetrate from the bristle surface of the head through the bristles into the inside of the head, possibly releasing the lead contained in the calcium carbonate. Further investigation by the inventors led them to believe that such release was due to the dissolution of calcium carbonate, which has a high ionization tendency, in water when the metal part used in the head part coexists with calcium carbonate. The dissolution of calcium carbonate may also lead to the release of lead contained in the calcium carbonate. As mentioned above, toothbrushes are typically washed with water and then air-dried, which can result in the release of lead during the process. From the viewpoint of providing a safe toothbrush, the less lead released, the better.

[0024] Therefore, the present inventors have conceived the idea that in a resin composition containing calcium carbonate-containing inorganic substance powder, the lead content per gram of inorganic substance powder should be 20 μg or less.

[0025] In one embodiment of the present invention, "suppressing the release of lead" can be specified, for example, by the fact that the release of lead from the head portion of the toothbrush after washing with water is small or that there is no release at all. Specifically, it can be specified by the method shown in the examples.

[0026] In one embodiment of the present invention, "lead" includes lead derived from the inorganic substance powder (particularly calcium carbonate) used as a raw material of the toothbrush. The form of lead is not particularly limited, and it includes not only the single substance but also compounds (such as lead sulfide).

[0027] 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, a mode of not containing component B at all.

[0028] In one embodiment of the present invention, "mainly containing component A" means that the content of component A is more than half with respect to the whole of the predetermined components. For example, "mainly containing component A" includes that the content of component A is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, still more preferably 99% by mass or more, and most preferably 100% by mass with respect to the whole of the predetermined components.

[0029] Hereinafter, the configuration of the toothbrush according to one embodiment of the present invention will be described in detail.

[0030] (1) Structure of the toothbrush In one embodiment of the present invention, the toothbrush includes a head portion and a handle portion.

[0031] Each structure of the toothbrush can adopt any conventionally known structure.

[0032] In a preferred aspect of the present invention, the toothbrush satisfies the standard defined in "JIS S3016:1995". "JIS S3016:1995" discloses a toothbrush structure comprising a "handle" and "bristles" planted in a bristle part provided on the handle. The "handle" refers not only to the gripping part of the toothbrush but also to the whole including the bristle part. The "bristles" are planted by bending the bristles and inserting them into the bristle holes provided in the bristle part and pressing them with a wire or the like.

[0033] The head part and the handle part may have the same composition or different compositions from each other. However, at least the head part is made of the resin composition described later.

[0034] The head part and the handle part may be integrally molded products or combinations of separate molded products.

[0035] The molding method of the head part and the handle part is not particularly limited, but in a preferred embodiment, injection molding can be mentioned. A preferred embodiment of the present invention includes an embodiment in which both the head part and the handle part are injection molded products.

[0036] (1-1) Head part The head part has tufts of bristles planted on its surface. The user of the toothbrush rubs the tufts of bristles against teeth, gums, etc. to remove dirt.

[0037] The head part usually has a recess (bristle hole) provided on a part of its surface. The tufts of bristles are fastened to this recess using a metal part, and thus the tufts of bristles are planted on the head part. The metal part corresponds to a metal bristle-fastening material and usually fixes the tufts of bristles in the bristle holes by driving them in from above the tufts of bristles pushed into the bristle holes.

[0038] The size, shape, etc. of the bristle 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.

[0039] The length, material, etc. of the tufts are not particularly limited, and any configuration used for cleaning teeth, gums, etc. can be adopted.

[0040] 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 wire and round wire. 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.

[0041] (1-2) Handle part The handle part corresponds to the gripping part extending from the head part. The user of the toothbrush can apply the head part to a desired site by gripping the handle part.

[0042] The handle of the toothbrush may include a part called a "neck part" in addition to the head part and the handle part. In such an embodiment, the head part is connected to the handle part via the neck part. However, the neck part and the handle part may be clearly distinguishable parts from each other, or may be integrated parts with each other (that is, the boundary between the neck part and the handle part is not clear).

[0043] (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.

[0044] (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.

[0045] (2-1-1) Types of thermoplastic resin The thermoplastic resin contains at least a polyolefin resin and preferably consists of a polyolefin resin. Examples of the thermoplastic resin other than the polyolefin resin include polyester resins, polystyrene resins, and the like.

[0046] In one embodiment of the present invention, the "polyolefin resin" means a polyolefin resin mainly composed of olefin component units. "Mainly composed of olefin component units" means that the olefin component units are contained in the polyolefin 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). 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.

[0047] Examples of the polyolefin resin include polypropylene resins, polyethylene resins, and the like. 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.

[0048] (2-1-2) Polypropylene resin The polypropylene resin in the present invention includes resins 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.

[0049] Examples of the polypropylene resin include polypropylene homopolymers (propylene homopolymers), copolymers of propylene and other α-olefins (capable of copolymerizing with propylene), and the like. 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.).

[0050] Examples of the propylene homopolymer include linear or branched polypropylene and the like that exhibit various stereoregularities (isotactic, syndiotactic, atactic, hemi-isotactic, etc.).

[0051] The copolymer of propylene may be any of a polypropylene random copolymer (random copolymer), a polypropylene block copolymer (block copolymer), a binary copolymer, a terpolymer, etc. Specifically, an ethylene-propylene random copolymer, a butene-1-propylene random copolymer, an ethylene-butene-1-propylene random terpolymer, an ethylene-propylene block copolymer, etc. are included.

[0052] 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.

[0053] (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.

[0054] 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.

[0055] As the polyethylene-based resin, a resin containing high-density polyethylene and / or linear low-density polyethylene is preferable, and a resin composed of high-density polyethylene and / or linear low-density polyethylene is more preferable.

[0056] The high-density polyethylene preferably has an MFR (190 °C, 21.6 kg) according to JIS K 6922-1:2018 (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.

[0057] The linear low-density polyethylene preferably has an MFR (190 °C, 2.16 kg) according to JIS K 6922-1:2018 (ISO1133) of 0.5 g / 10 min or more and 1.5 g / 10 min or less, and more preferably 0.7 g / 10 min or more and 1.3 g / 10 min or less.

[0058] 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, and still more preferably 94:6 to 50:50.

[0059] (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.

[0060] 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, and still more preferably 20% by mass or more with respect to the resin composition.

[0061] From the viewpoint that a sufficient amount of the inorganic substance powder can be blended and good mechanical properties are easily exhibited, the content of the thermoplastic resin is preferably 50% by mass or less, more preferably 45% by mass or less, and still more preferably 40% by mass or less with respect to the resin composition.

[0062] (2-2) Inorganic substance powder By blending an inorganic substance powder that satisfies predetermined requirements together with a thermoplastic resin, it is possible to suppress the release of lead in the head portion obtained from the resin composition.

[0063] (2-2-1) Types of inorganic substance powder The inorganic substance powder is not particularly limited except that it mainly 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.

[0064] (2-2-2) Calcium carbonate powder The calcium carbonate powder may be any of heavy calcium carbonate powder and light calcium carbonate powder, or a combination thereof. "Heavy calcium carbonate" is calcium carbonate obtained by mechanically pulverizing (dry method, wet method, etc.) natural raw materials (such as limestone) having CaCO 3 as the 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.

[0065] The difference between heavy calcium carbonate and light calcium carbonate can be specified, for example, from the roundness calculated based on the analysis of the SEM image. The roundness of the heavy calcium carbonate powder is, for example, in the range of 0.50 or more and 0.95 or less. The roundness of the light calcium carbonate powder is, for example, approximately 1.00.

[0066] In one embodiment of the present invention, the "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 the particle is to a perfect circle, and the lower the numerical value, the higher the degree of irregularity. "Circularity" = (projected area of particle) / (area of a circle having the same perimeter as the projected perimeter of the particle)

[0067] Heavy calcium carbonate, due to its manufacturing method, does not have a constant shape, etc. However, despite its low cost, it can easily and stably impart good mechanical properties to resin molded products. Therefore, preferred embodiments of the present invention include embodiments in which the calcium carbonate contains heavy calcium carbonate powder or embodiments in which the calcium carbonate consists of heavy calcium carbonate powder.

[0068] (2-2-3) Inorganic substance powder other than calcium carbonate Examples of inorganic substance powders other than calcium carbonate include the following. Carbonates, sulfates, silicates, phosphates, or borates of metals (such as titanium, magnesium, aluminum, iron, zinc, etc.); Oxides of metals (such as titanium, calcium, magnesium, aluminum, iron, zinc, etc.); Hydrates of the above salts or oxides, etc.

[0069] Examples of inorganic substance powders other than calcium carbonate include titanium oxide, magnesium carbonate, zinc 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.

[0070] Among the above, from the viewpoint that the possibility of lead release is low and the effects according to the present invention can be more stably improved, as the inorganic substance powder other than calcium carbonate, a component containing neither lead nor arsenic as a constituent is preferable. As such a component, any one or more of titanium oxide, zinc oxide, alumina, clay, talc, kaolin, aluminum hydroxide, aluminum silicate, calcium silicate, aluminum sulfate, calcium sulfate, barium sulfate, silica sand, carbon black, zeolite, molybdenum, diatomaceous earth, sericite, shirasu, calcium sulfite, bentonite, and graphite is preferable, and titanium oxide (TiO 2 ) is more preferable.

[0071] The inorganic substance powder may be synthetic or may be derived from natural minerals.

[0072] In the present invention, when two or more kinds of inorganic substance powders are included, the combination ratio thereof is not particularly limited except that it mainly contains calcium carbonate powder, and can be appropriately set according to the effects to be obtained and the like.

[0073] In one aspect of the present invention, when two or more kinds of inorganic substance powders are included, the combination preferably includes a combination of calcium carbonate and one or more other inorganic substance powders, more preferably a combination of calcium carbonate and titanium oxide, and still more preferably a combination consisting of calcium carbonate and titanium oxide.

[0074] In one aspect of the present invention, when calcium carbonate and one or more other inorganic substance powders are included, the lower limit of the content of the inorganic substance powder other than calcium carbonate is preferably 0.1% by mass or more, more preferably 1% by mass or more, and still more preferably 5% by mass or more based on the total inorganic substance powder. In one aspect of the present invention, when calcium carbonate and one or more other inorganic substance powders are included, the upper limit of the content of the inorganic substance powder other than calcium carbonate is preferably 20% by mass or less, more preferably 10% by mass or less based on the total inorganic substance powder.

[0075] Whether calcium carbonate is contained in the inorganic substance powder in the resin composition and its content can be specified by firing the resin composition and performing ash analysis on it. The method of ash analysis can be applied mutatis mutandis in accordance with JIS K 7250-1:2006.

[0076] (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.

[0077] (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.

[0078] (2-2-4-2) Other trace components The content of other trace components is not particularly limited, but the higher the purity of the inorganic substance powder, the easier it is to achieve the effects of the present invention.

[0079] 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.

[0080] (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, but examples thereof include the following. · Synthesis or collection of inorganic substance powder that meets the requirements of the present invention. · Blending of inorganic substance powder that does not meet any of the requirements of the present invention and inorganic substance powder that meets the requirements of the present invention.

[0081] (2-2-4-4) Method for measuring trace components The content of trace components contained in the inorganic substance powder is specified by the following method described in the 9th Edition of the Japanese Pharmacopoeia of Food Additives (Ministry of Health, Labour and Welfare, Consumer Affairs Agency). The amount of trace components specified by this method does not necessarily accurately include the trace components contained in the inorganic substance powder other than calcium carbonate powder in the inorganic substance powder. However, since calcium carbonate powder is the main component in the inorganic substance powder, it sufficiently reflects the properties of the entire inorganic substance powder.

[0082] Regarding the purity test of calcium carbonate, etc., the 9th Edition of the Japanese Pharmacopoeia of Food Additives (Ministry of Health, Labour and Welfare, Consumer Affairs Agency) has the following description (pages 748 - 749). “(3) Lead Pb: 3 μg / g or less (2.0 g, Method 5, comparison solution: 6.0 mL of lead standard solution, flame method) Add 20 mL of hydrochloric acid (1→4) to this product, cover with a watch glass, etc., and gently boil for 15 minutes. After cooling, add 30 mL of water to obtain a sample solution. In the case where the sample does not dissolve, evaporate to dryness, add 20 mL of hydrochloric acid (1→4) to the residue, cover with a watch glass, etc., and gently boil for 5 minutes. After cooling, add 30 mL of water to obtain a sample solution. However, change the amount of ammonium hydrogen citrate solution (1→2) shown in Method 5 to 50 mL, use 1 mL of bromothymol blue test solution as the indicator, and add aqueous ammonia until the yellow color of the solution changes to yellow - green.” “(6) Arsenic As: 3 μg / g or less (0.50 g, standard color: 3.0 mL of arsenic standard solution, Apparatus B) Weigh this product, moisten it with 1 mL of water, add 4 mL of hydrochloric acid (1→4) and dissolve it to obtain a test solution.”

[0083] Regarding the purity test of titanium oxide (titanium dioxide), etc., the 9th Edition of the Japanese Pharmacopoeia of Food Additives (Ministry of Health, Labour and Welfare, Consumer Affairs Agency) has the following description (pages 808 - 809). “(3) Lead Pb: 10 μg / g or less (4.0 g, comparison solution: 4.0 mL of lead standard solution, flame method) Add 50 mL of hydrochloric acid (1→20) to this product, cover with a watch glass or the like, boil for 20 minutes, then centrifuge to precipitate the insoluble matter. Filter the supernatant, wash the used container and the residue three times with 10 mL of hot water, and filter using the same filter paper. Further, wash the used filter paper with 10 - 15 mL of hot water, and combine the washing liquid with the filtrate. After cooling, add water to make 100 mL, and use it as the sample solution. Measure 10 mL of the sample solution, add 1 / 4 volume of hydrochloric acid, gently heat to evaporate to dryness. Add a small amount of nitric acid (1→100) to the residue and warm. After cooling, add more nitric acid (1→100) to make exactly 10 mL, and use it as the test solution. Separately, accurately measure the lead standard solution, add nitric acid (1→100) and make exactly 10 mL, and use it as the comparison solution. “(4) Arsenic As: 1 μg / g or less (10 g, standard color arsenic standard solution 3.0 mL, apparatus B) Weigh this product, put it into a 250 mL beaker, add 50 mL of hydrochloric acid (1→20), cover with a watch glass or the like, heat until boiling, and further boil gently for 15 minutes. Then centrifuge to precipitate the insoluble matter. Filter the supernatant, wash the used beaker and the residue three times with 10 mL of hot water each, and filter using the same filter paper. Further, wash the used filter paper with 10 - 15 mL of hot water, and combine the washing liquid with the filtrate. After cooling, add water to make 100 mL, and use it as the sample solution. Measure 15 mL of the sample solution and use it as the test solution.”

[0084] (2 - 2 - 5) Other conditions for the inorganic substance powder The inorganic substance powder can be in any form as long as it satisfies the above conditions for trace components.

[0085] 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 viewpoints of easily achieving 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 - 8511:2014 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.

[0086] 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 (methods using coupling agents or surfactants).

[0087] The shape of the inorganic substance powder is not particularly limited, and it may be any of particulate (spherical, irregular shape, etc.), flaky, granular, fibrous, etc.

[0088] (2-2-6) Blending amount of inorganic substance powder From the viewpoint of easily enhancing the 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, based on 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, based on the resin composition.

[0089] From the viewpoint that even if the content of calcium carbonate powder 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, based on the inorganic substance powder. The upper limit of the content of calcium carbonate powder is not particularly limited, but it is preferably 100% by mass or less, more preferably 99% by mass or less, based on the inorganic substance powder.

[0090] From the viewpoint that even if the content of calcium carbonate powder 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, based on the resin composition. The upper limit of the content of calcium carbonate powder is not particularly limited, but it is preferably 90% by mass or less, more preferably 80% by mass or less, based on the resin composition.

[0091] Whether the inorganic substance powder contains calcium carbonate and its content can be specified by firing the resin molded product and performing its ash analysis.

[0092] (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 a range that does not inhibit the effects of the present invention.

[0093] As the other components, any components that can be usually blended in the resin molded product can be adopted. Examples of such components include colorants, lubricants, dispersants, antistatic agents, antioxidants, heat stabilizers, ultraviolet absorbers, and the like. The types and amounts of these components can be appropriately set according to the effects to be obtained and the like.

[0094] The resin composition in the preferred embodiment of the present invention includes those composed only of a thermoplastic resin and an inorganic substance powder.

[0095] (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 more than that, it becomes easier to exhibit the effect of improving the mechanical properties by the inorganic substance powder.

[0096] (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 and use of the resin composition and the like.

[0097] 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, and a kneading machine (such as a twin-screw kneading machine).

[0098] 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

[0099] Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0100] <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.

[0101] (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.

[0102] (1-1) Inorganic Substance Powder The following were prepared as inorganic substance powders. · Calcium carbonate particles (heavy calcium carbonate particles): The average particle diameter by the air permeability method according to JIS M-8511:2014 for the calcium carbonate particles was 2.0 μm. · Titanium oxide particles: The average particle diameter by the air permeability method according to JIS M-8511:2014 for the titanium oxide particles was 0.6 μm.

[0103] Only calcium carbonate particles were used to prepare the following "inorganic powder 1" to "inorganic powder 4". 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 for Food Additives (Ministry of Health, Labour and Welfare, Consumer Affairs Agency). This pharmacopoeia stipulates the measurement methods for trace components (lead, alkali metals and magnesium, hydrochloric acid-insoluble substances, and free alkali, etc.) contained in calcium carbonate.

[0104] Furthermore, the following "inorganic powder 5" was prepared using calcium carbonate particles and titanium oxide particles. The purchased titanium oxide particles and calcium carbonate particles were blended at a mass ratio of titanium oxide particles:calcium carbonate particles = 10:90 to prepare "inorganic powder 5". "Inorganic powder 1" was used as the calcium carbonate particles. The content of trace components in titanium oxide particles was measured in advance in accordance with the section on "Calcium Carbonate" (pages 748 - 749) of the 9th Edition of the Japanese Pharmacopoeia for Food Additives (Ministry of Health, Labour and Welfare, Consumer Affairs Agency). As a result, all trace components contained in titanium dioxide were below the detection limit. Therefore, the amount of trace components contained in the inorganic substance powder used in this example is consistent with the amount of trace components contained in the calcium carbonate powder.

[0105] In Table 1, each trace component content 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)

[0106]

Table 1

[0107] (1 - 2) Thermoplastic resin Any of the following thermoplastic resins (all corresponding to polyolefin-based resins) was used. Polypropylene-based resin (PP): Polypropylene block copolymer (melting point 160 °C) Polyethylene-based resin (PE): Blend of HDPE and LLDPE (HDPE:LLDPE (mass ratio) = 70:30) In addition, the MFR (190 °C, 21.6 kg) of the above HDPE according to JIS K 6922-1:2018 (ISO1133) is 7.5 g / 10 min. The MFR (190 °C, 2.16 kg) of the above LLDPE according to JIS K 6922-1:2018 (ISO1133) is 0.8 g / 10 min.

[0108] (2) Preparation of toothbrush In the implantation holes provided in the head portion 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.

[0109] (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 portion or only the handle portion 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 confirm the presence or degree of lead release in the tap water and evaluate it according to the following criteria. The results are shown in the "Release" column of Tables 2 and 3.

[0110] <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.

[0111] <Evaluation criteria for arsenic release test> A: No arsenic release was observed in any of the 50 toothbrushes. B: Among 50 toothbrushes, arsenic release was observed in 2 or fewer.

[0112]

Table 2

[0113]

Table 3

[0114] As shown in the table, in the toothbrush satisfying the requirements of the present invention, lead release was suppressed.

[0115] Furthermore, when the arsenic content per 1 g of the inorganic substance powder was 3 μg or less, arsenic release was more stably suppressed.

[0116] As the inorganic substance powder, together with heavy calcium carbonate powder, other inorganic substance powders (in this example, titanium oxide) were used, and results of the same tendency as above were obtained. Also, in the same manner as “inorganic powder 5”, when titanium oxide particles:calcium carbonate particles (mass ratio) = 10:90 were blended for “inorganic powder 2” to “inorganic powder 4”, results of the same tendency as when using only “inorganic powder 2” to “inorganic powder 4” were obtained respectively. From this, it was found that using the inorganic substance powder to satisfy the requirements of the present invention does not significantly affect the result itself of the type of the inorganic substance powder.

[0117] In this example, heavy calcium carbonate was adopted as the inorganic substance powder, but the same tendency as above was also observed for other inorganic substance powders (light calcium carbonate, talc, etc.).

[0118] In this example, a flat wire made of brass was used, but the same tendency as above was also observed for a flat wire made of any of aluminum, zinc, and stainless steel.

Claims

1. A toothbrush comprising a head portion and a handle portion, The hair bundle is implanted into the hair implantation hole provided on a part of the surface of the head by driving a metal part into the hair implantation hole, 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 powder is 50:50 to 10:90; the thermoplastic resin includes a polyolefin resin, The inorganic substance powder mainly contains calcium carbonate, The lead content per gram of the inorganic powder is 20 μg or less. toothbrush.

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

3. The resin composition according to claim 1 , wherein the content of the calcium carbonate is 80 mass % or more based on the inorganic substance powder.

4. 2. The toothbrush of claim 1, wherein said powdered inorganic material comprises ground calcium carbonate.

5. 2. The toothbrush of claim 1, wherein the inorganic powder has an arsenic content of 3 μg or less per gram of the inorganic powder.

6. The toothbrush according to claim 4, wherein the heavy calcium carbonate has an average particle size of 0.7 μm or more and 6.0 μm or less as measured by an air permeation method in accordance with JIS M-8511:2014.

7. 10. The toothbrush of claim 1, wherein said head portion and said handle portion are injection molded.

8. 2. The toothbrush of claim 1, wherein the metal portion is a flat wire or a round wire.

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

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