JP7339490B2 - interdental cleaner - Google Patents

Description

The present invention relates to an interdental cleaning tool.

Interdental cleaning tools are widely used to prevent tooth decay and periodontal disease, for example, by removing food debris caught between teeth and plaque that causes tartar that tends to adhere mainly to the roots of teeth. used. The interdental cleaning tool includes, for example, an elongated shaft-shaped core base portion, a handle base portion connected to one end of the core base portion, and a soft portion covering the surface of the core base portion. An interdental cleaning tool equipped with such an interdental cleaning tool has been put into practical use (see Patent Documents 1 to 3). By gripping the handle base portion of the interdental cleaner with fingers and inserting the core base portion covered with the soft portion into the interdental portion and reciprocating mainly in the axial direction, plaque and food debris are removed. remove and massage the gums and gums to relieve inflammation.

Japanese Patent No. 4236571 Japanese Patent No. 3002668 Japanese Patent Publication No. 2001-506514

In conventional interdental cleaners, including the interdental cleaners described in Patent Documents 1 to 3, the core base portion is made of synthetic resin, and the soft portion that directly contacts the interdental portion is made of synthetic resin. are generally made of soft elastomer. Thermoplastic resins are mainly used for synthetic resins forming the core base material from the viewpoints of mechanical properties, flexibility, mass productivity, and the like. Moreover, in order to further improve the mechanical properties of thermoplastic resins, resin compositions containing inorganic fillers having a predetermined shape such as fibrous or flaky shapes are sometimes used. Hereinafter, the core base material portion and the soft portion covering the surface thereof will also be collectively referred to as a “cleaning portion”.

One reason for enhancing the mechanical properties of the synthetic resin forming the core base is that, for example, the elongated shaft-like core base is likely to break due to the force applied to the cleaning portion during interproximal cleaning. For example, when inserting the cleaning part into the interdental space, a large compressive force acts on the cleaning part in the axial direction. Also, when cleaning the interdental areas behind the molars (especially molars) and the front teeth on the mandibular side, the cleaning part inserted into the interdental area should be positioned so that the tip to the middle of the interdental cleaning tool is aligned with the axial center of the interdental cleaning tool. Since it is inserted and removed in a state in which it is bent by 60° to 90°, a large bending force acts on the cleaning portion. Therefore, even if the core base material is made of a synthetic resin having high mechanical properties, the core base material and the cleaning part are often broken or deformed without restoring during interdental cleaning.

Conventionally, it has been recognized that the core base material has sufficient apparent flexibility and elasticity because the core base material is molded to have a very small diameter that can be inserted into the interdental space. In order to prevent breakage of the core base material, it has been considered necessary to increase the mechanical strength of the synthetic resin forming the core base material rather than to increase flexibility and elasticity. . Therefore, as a countermeasure against breakage of the core base material, it has been mainly practiced to form the core base material from a resin composition obtained by adding an inorganic filler such as glass fiber to a synthetic resin such as a polypropylene resin. Ta.

In the course of research on how to prevent breakage of the core base material, the present inventors have focused on the viscosity of synthetic resins as a characteristic that leads to flexibility and elasticity of synthetic resins, contrary to conventional technical common sense. and breakage of the core base material.

SUMMARY OF THE INVENTION An object of the present invention is to provide an interdental cleaning tool having a core base portion that is resistant to breakage during interdental cleaning, has good durability, and is excellent in insertability into interdental areas.

The present invention provides the following interdental cleaners (1) to (10) as preferred embodiments.
(1) An interdental cleaning tool that includes an elongated shaft-like core base material and inserts the core base material into the interdental space to clean the interdental space, wherein the core base material is made of a thermoplastic material. An interdental cleaner comprising a resin composition containing a resin and an inorganic filler, wherein the thermoplastic resin has a weight-average molecular weight of 400,000 or more.
(2) The interdental cleaner according to (1) above, wherein the thermoplastic resin has a weight average molecular weight of 400,000 or more and a number average molecular weight of 78,000 or more.
(3) The interdental cleaner of (1) or (2) above, wherein the thermoplastic resin has a weight average molecular weight of 420,000 or more and a number average molecular weight of 80,000 or more. (4) The thermoplastic resin is an olefin. The interdental cleaning tool according to any one of the above (1) to (3), which is at least one selected from the group consisting of poly-based resins, polyamide-based resins, and polyester-based resins.
(5) The interdental cleaner according to any one of (1) to (4) above, wherein the thermoplastic resin is an olefin-based resin, and the olefin-based resin is a propylene-based resin. .
(6) The interdental cleaner according to any one of (1) to (5) above, further comprising a handle base portion connected to one end of the core base portion.
(7) The interdental cleaner according to any one of (1) to (6) above, further comprising a soft portion made of a material softer than the resin composition and covering the surface of the core base portion.
(8) The interdental cleaner according to any one of (1) to (7) above, wherein the resin composition further contains an elastomer compatible with the thermoplastic resin.
(9) The interdental space of (8) above, wherein the elastomer is at least one thermoplastic elastomer (TPE) selected from the group consisting of styrene elastomers, olefin elastomers, vinyl chloride elastomers, and amide elastomers. Cleaning tool.
(10) Any one of (1) to (9) above, wherein the inorganic filler is at least one selected from the group consisting of fibrous inorganic fillers, flaky inorganic fillers, and granular inorganic fillers. Interdental cleaner.

In the present specification, both the number average molecular weight and the weight average molecular weight are polystyrene equivalent values measured by GPC (gel permeation chromatography) using polystyrene standards. This measurement is performed, for example, using a GPC device and a GPC column under the conditions of measurement solvent: o-dichlorobenzene, oven temperature: 135°C, sample concentration: 0.2% (w/v), and detection with a differential refractometer. It is done by As the GPC apparatus, for example, trade name: HLC-8121GPC/HT (manufactured by Tosoh Corporation) and trade name: Prominence GPC System (manufactured by Shimadzu Corporation) can be used. As the GPC column, for example, a product name: Shodex GPC HT-806M (manufactured by Showa Denko KK) can be used.

The interdental cleaning tool of the present invention has a core base portion that is less likely to break during interdental cleaning, has good durability, and is excellent in insertability into interdental areas.

It is drawing which shows typically the external appearance of one form of the interdental cleaning tool of this embodiment. It is drawing which shows typically the external appearance of the other form of the interdental cleaning tool of this embodiment. FIG. 3 is a side view showing a test method of a fatigue test in a bending fatigue test; FIG. 3 is a side view showing a test method for a cantilever bending test in a bending fatigue test. It is a graph which shows the result of a bending fatigue test.

The interdental cleaning tool of the present embodiment has an elongated shaft-shaped core substrate portion that is inserted into the interdental space to clean it, and the core substrate portion is a thermoplastic material having a weight-average molecular weight of 400,000 or more. It is composed of a resin composition containing a resin and an inorganic filler. That is, in this embodiment, a resin composition containing a thermoplastic resin having a weight-average molecular weight of 400,000 or more and an inorganic filler is used as the material constituting the core base material. The interdental cleaning tool of the present embodiment is not particularly limited as long as it has the core base portion, and can adopt various conventionally known forms.

For example, the interdental cleaning tool of the first embodiment is composed of a core base portion. For example, it may be configured such that the proximal end portion of the core base portion can be gripped with fingers. By gripping the base end side of the core base portion with fingers, the tip portion of the core base portion can be easily inserted into and withdrawn from the interproximal space. Moreover, the form which has a core base material part and the shaft-shaped or plate-shaped support part provided with the insertion mechanism which can attach or detach the base end side edge part of a core base material part may be sufficient. Here, the support portion may have the same shape and dimensions as the handle base portion, which will be described later, except that a mechanism (or structure) for attaching and detaching the proximal end portion of the core base portion is provided. The mechanism (or structure) is, for example, a hole into which the proximal end of the core substrate is inserted, a fitting mechanism, a screw mechanism, or the like. In the fitting mechanism and the screw mechanism, both the proximal end portion of the core base portion and the mechanism provided on the support portion have predetermined structures.

The interdental cleaning tool of the second embodiment has a core base portion and a handle base portion connected to one end of the core base portion. The interdental cleaning tool of the third embodiment has a core base portion, a handle base portion connected to one end of the core base portion, and a soft portion covering the surface of the core base portion. The interdental cleaning tool of the fourth embodiment includes a core base portion, a handle base portion connected to one end of the core base portion, a soft portion covering the surface of the core base portion, and a surface of the soft portion. and one or more projections projecting outwardly from the. The soft part has a single or a plurality of protrusions on its surface, for example, from the viewpoint of enhancing the function of cleaning the interdental part and the function of massaging the gingiva. From the viewpoint of ease of molding, it is preferable that the protrusion is made of the same material as the soft portion. When a plurality of protrusions are provided, their arrangement may be regular or irregular, and the three-dimensional shapes of the protrusions may be the same or different. In the interdental cleaners of the third and fourth embodiments, the soft portion can partially or entirely cover the surface of the core base portion. Further, in the interdental cleaning tool of the fourth embodiment, the protrusion may be provided on the entire surface of the soft portion, or may be provided on a part of the soft portion such as the tip that reciprocates in the interdental portion. The interdental cleaning tool of the present invention is not limited to the first to fourth embodiments, and can include conventionally known interdental cleaning tool forms.

The core substrate portion, the core substrate portion coated with the soft portion, and the core substrate portion coated with the soft portion having protrusions on the surface are all inserted into the interdental portion and reciprocated in the axial direction thereof. By moving it, it has a function of removing food debris and dental plaque stuck between the teeth and a function of massaging the gums. Hereinafter, the core base material portion covered with the soft portion or the soft portion having the protrusions will also be referred to as the “cleaning portion”. By gripping the handle base portion with fingers, the core base portion or the cleaning portion is supported. With the handle base portion held by fingers, the core base portion or the cleaning portion is inserted into the interdental space and axially reciprocated to clean the interdental space and massage the gums.

The inventors of the present invention, in the course of research on the prevention of breakage of the core base material, have found thermoplastic resins having a weight average molecular weight of 400,000 or more, preferably having a weight average molecular weight of 400,000 or more and a number average molecular weight of 78,000. The inventors paid attention to the fact that the above resins not only have higher mechanical properties and rigidity than thermoplastic resins with relatively low molecular weights, but also have higher viscosity. As a result of further studies by the present inventors, in order to prevent breakage of the core base member which is molded into a unique shape of a shaft having an extremely small diameter, it is necessary to select a material that constitutes the core base member. We have found that it is important not only to have mechanical properties and rigidity, but also to have a certain level of stickiness. That is, the viscosity of the synthetic resin is the durability of the core base material as an ultra-thin shaft against compressive force from the tip direction of the core base material and bending force from the direction perpendicular to the core base material axial direction. It has been clarified by the studies of the present inventors that the resistance to bending is increased and the bending resistance is improved.

The stickiness here is considered not to be stickiness, but to be a characteristic such as viscoelasticity that raises the threshold when the core base material breaks in a direction intersecting with its axial direction, for example. As a result of using a thermoplastic resin having a weight-average molecular weight of 400,000 or more, the interdental cleaning tool of the present embodiment can be used without substantially impairing the insertability of the core base material into the interdental part. The breakage during interdental cleaning can be greatly reduced, and the durability is improved.

Since the core base material is formed by molding a thermoplastic resin into an elongated shaft shape, it has been thought to have sufficient apparent flexibility and/or elasticity. In the conventional core base material, when an external load such as a compressive force from the tip direction of the core base material or a bending force from a direction perpendicular to the axial direction of the core base material is applied, it easily bends or breaks easily. It has been thought that the reason for this is that the core base material has the aforementioned apparent elasticity and/or flexibility, so that the mechanical property threshold for withstanding these forces is low. In order to increase the threshold value, an inorganic filler such as glass fiber has been added to the thermoplastic resin to increase the mechanical strength. In other words, it has been thought that there is no particular correlation between the flexibility and elasticity of the material forming the core base material and the folding resistance of the core base material. However, research by the present inventors has revealed that not only the mechanical properties of the material forming the core base portion but also the flexibility, elasticity and stickiness are involved in the folding resistance of the core base portion.

The details of the interdental cleaning tool of this embodiment are as follows. The structure of the core base material and the material forming the core base material will be described.

The elongated shaft-shaped core base portion is a member common to the interdental cleaners of the first to fourth embodiments and other embodiments. For example, the core base portion of the present embodiment has a configuration in which the shaft extends substantially linearly as shown in FIG. As shown in , the entire shaft is curved from the root (hereinafter also referred to as the “base end”) to the tip of the handle base portion (for example, a curved interdental cleaner), and a predetermined (e.g., L-shaped interdental cleaner), tapered at the tip, gently tapered shape with a diameter decreasing toward the tip It includes a form in which the diameter gradually expands from the middle part of the core base part toward the side to be gripped with fingers, the support part side, or the handle base part side. The interdental cleaning tool shown in FIGS. 1 and 2 is included in the interdental cleaning tool of the third embodiment.

The core base material portion is formed in an elongated shaft shape and contains a thermoplastic resin having a weight average molecular weight of 400,000 or more (hereinafter sometimes simply referred to as "thermoplastic resin" unless otherwise specified) and an inorganic filler, It consists of a resin composition (A) that may contain an elastomer. Furthermore, the resin composition (A) can contain known additives contained in thermoplastic resin compositions for interdental cleaners.

The thermoplastic resin in the resin composition (A) has a weight average molecular weight of 400,000 or more, and preferably has a weight average molecular weight of 400,000 or more and a number average It has a molecular weight of 78,000 or more, more preferably a weight average molecular weight of 420,000 or more, and a number average molecular weight of 80,000 or more, more preferably a weight average molecular weight of 450,000 or more, and a number average molecular weight of 85,000 or more. is. The upper limits of the weight-average molecular weight and the number-average molecular weight can each be a value that allows injection molding. 120,000 or less or 150,000 or less.

As the thermoplastic resin, any thermoplastic resin commonly used in the field of interdental cleaners can be used without particular limitation, as long as the thermoplastic resin has a weight-average molecular weight of 400,000 or more. Examples include olefin-based resins and polyamide-based resins. , polyester-based resins, polymethyl methacrylate, cellulose propionate, thermoplastic polyurethane-based resins, polycarbonate-based resins, polyacetal-based resins, ABS (acrylonitrile-butadiene-styrene)-based resins, etc. One or two of these You can use more than From these thermoplastic resins, those having a predetermined weight average molecular weight or a predetermined weight average molecular weight and a predetermined number average molecular weight may be selected and used. The number-average molecular weight and/or weight-average molecular weight can be easily adjusted by those skilled in the art, for example, by selecting the degree of polymerization, monomer components, polymerization method, and the like.

Among the above thermoplastic resins, from the viewpoint of improving the folding resistance of the core base material, molding processability and mechanical properties, it is selected from the group consisting of olefin resins, polyamide resins, and polyester resins. is preferably at least one of the resins listed above, and more preferably an olefin-based resin. Specific examples of olefin resins include propylene polymers (homopolymers, random copolymers, block copolymers), ethylene polymers (homopolymers, random copolymers, block copolymers), and the like. Specific examples of polyester resins include saturated polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, and polycyclohexylene dimethylene terephthalate.

Among the above-described olefin resins, propylene polymers (or propylene resins) are more preferable from the viewpoints of preventing breakage of the core substrate portion and the cleaning portion, molding processability, and economic efficiency. is 150° C. or higher and at least a portion of the propylene-based polymer is crystalline. Propylene-based polymers are particularly preferred because they have a low molding temperature, can shorten cycle time and improve productivity, and have a low thermal load on molding equipment. When a thermoplastic resin having a melting point of 150°C or higher is used as the material for the interdental cleaner, the molding time of the intermediate molded product (the core base portion and the handle base portion connected thereto), especially the cooling time after molding, is shortened. can increase production efficiency. As a result, the productivity of the interdental cleaning tool of this embodiment can be improved, and the production cost can be reduced.

The propylene-based polymer (or propylene-based resin) includes, as described above, at least one selected from the group consisting of homopolymers (propylene homopolymers), random copolymers and block copolymers. A random copolymer is a copolymer of propylene and a compound copolymerizable therewith, such as a copolymer of propylene and an α-olefin. A copolymer of propylene and an α-olefin is, for example, a copolymer of propylene and ethylene and/or an α-olefin having 4 to 12 carbon atoms containing 50% by weight or more of structural units derived from propylene. , and preferably a propylene-ethylene random copolymer. Block copolymers include, for example, propylene-ethylene block copolymers. Similarly, ethylene-based polymers include homopolymers of ethylene, random copolymers and block copolymers of ethylene and α-olefins having 4 to 12 carbon atoms.

Examples of inorganic fillers in the resin composition (A) include fibrous inorganic fillers (hereinafter also referred to as "fibrous fillers"), flaky inorganic fillers (hereinafter also referred to as "flaky fillers"), and granular fillers. At least one selected from the group consisting of inorganic fillers (hereinafter also referred to as "particulate fillers") can be preferably used. The shape of these inorganic fillers can be determined by microscopic observation using a scanning electron microscope.

A fibrous filler is an inorganic compound having a long dimension (long dimension) in one direction. The shape is also called columnar or whisker-like in addition to fibrous, and the length dimension is mm order to μm order, and the fiber diameter dimension is mainly μm order. The aspect ratio (fiber length/fiber diameter) of the fibrous filler is preferably 2 or more, more preferably 5 or more, still more preferably 10 or more. The fibrous filler is not particularly limited, but from the viewpoint of safety to the human body and availability, glass fiber, wollastonite, titanium dioxide fiber, potassium titanate fiber, etc. can be preferably used. Taking into consideration, glass fiber and wollastonite are more preferred, and glass fiber is even more preferred. A fibrous filler is preferable to a flaky filler from the viewpoint of increasing the rigidity of the core base material, particularly the rigidity of the core base material in the axial direction. A fibrous filler can be used individually by 1 type or in combination of 2 or more types as needed.

A flaky filler is an inorganic compound having a thin dimension (thickness dimension) in one direction. The shape is also called scale-like or plate-like in addition to flake-like, and the size is on the order of μm. Although the flaky filler is not particularly limited, from the viewpoint of safety to the human body, availability, etc., glass flakes, mica, clay, talc, etc. are preferred, clay and talc are more preferred, and talc is even more preferred. A flaky filler can be used individually by 1 type or in combination of 2 or more types.

A particulate filler is an inorganic compound that does not belong to a fibrous or flaky shape and has a regular shape such as a substantially spherical shape, a substantially ellipsoidal shape, or an irregular shape when observed under a microscope. Its dimensions range from the order of μm to the order of mm, but those having dimensions of the order of μm are preferable in terms of application to the core base member of the present embodiment. Granular fillers are not particularly limited, but examples include calcium carbonate, barium sulfate, silica, fused silica, zeolite, aluminum hydroxide, and titanium oxide. A granular filler can be used individually by 1 type or in combination of 2 or more types.

Preferred forms of inorganic fillers include the use of fibrous fillers alone and the combined use of fibrous fillers and flaky fillers. When the fibrous filler is used alone, the folding resistance of the core substrate portion or the cleaning portion is remarkably improved due to the cooperation between the fibrous filler and the thermoplastic resin having a predetermined weight-average molecular weight. When a fibrous filler and a flaky filler are used in combination, the fibrous filler and the flaky filler are oriented in different directions in the core base material. In some cases, the mechanical properties and flexibility (elasticity) of the base material are compatible at a high level, thereby contributing to the improvement of the folding resistance of the core base material. Specific examples of the combined use include combined use of glass fiber and talc.

In the resin composition (A), the content of the inorganic filler is not particularly limited. % or in the range of 25-38% by weight, the balance being thermoplastic resin. When the content of the inorganic filler is within the above range, the folding resistance of the core substrate portion is improved by cooperation with the thermoplastic resin. If the content of the inorganic filler is too small, the insertability of the core base material into the interdental space may deteriorate, and the folding resistance of the core base material may be insufficiently improved. . If the content of the inorganic filler is too high, the dispersibility of the inorganic filler in the resin composition (A) may deteriorate, and the core base material may locally deteriorate in folding resistance. In the present invention, a commercially available compound obtained by blending a thermoplastic resin having a number average molecular weight of 400,000 or more with an inorganic filler such as glass fiber can be used.

The elastomer, which is an optional component contained in the resin composition (A), is not particularly limited, and may be thermoplastic elastomers (TPE) such as styrene, olefin, vinyl chloride, polyamide, silicone, urethane, A thermosetting elastomer such as a fluorine-based elastomer can be used. In particular, an elastomer compatible with the thermoplastic resin in the resin composition (A) constituting the core base portion is preferred, and an elastomer compatible with the olefinic resin is more preferred. As the elastomer compatible with the olefinic resin, the thermoplastic elastomers described above are preferable, styrene-based and olefinic-based elastomers are more preferable, and styrene-based elastomers are even more preferable. Elastomers can be used singly or in combination of two or more.

The content of the elastomer in the resin composition (A) is an amount that improves the folding resistance of the core base material, depending on the type of thermoplastic resin and inorganic filler, each content, and the type of the elastomer itself. It may be selected as appropriate and is not particularly limited. When the content of the elastomer is appropriate, the above-described effects of the present embodiment (improved folding resistance of the core base material, remarkable improvement in feeling during use, occurrence of warpage in the portion corresponding to the core base material of the intermediate molded product) , etc.) can be obtained. If the elastomer content is too low, the addition of the elastomer will not improve the folding resistance of the core base material sufficiently. There is a tendency for the insertability and usability of the device to deteriorate. Therefore, it is easy to select the content of the elastomer through a preliminary experiment or the like.

As a specific example of the elastomer content, for example, in a resin composition of one embodiment containing a propylene-based polymer, a thermoplastic elastomer and glass fibers, Accordingly, the amount of the thermoplastic elastomer can be 30 parts by weight or less, 25 parts by weight or less, 20 parts by weight or less, 15 parts by weight or less, or 10 parts by weight or less. Since the elastomer is an optional component, it is not necessary to set a lower limit. It can be parts by weight or 5 parts by weight. It should be noted that these numerical ranges may also be applicable when a thermoplastic resin other than a propylene-based polymer having a number average molecular weight of 400,000 or more and/or an inorganic filler other than glass fiber is used.

In the present embodiment, the resin composition (A ) can be contained in

The axial dimension (diameter) and length dimension of the core base material of the present embodiment are not particularly limited, but from the viewpoint of facilitating the operation of the interdental cleaning tool as a whole, the axial dimension (diameter) is set to 0.3 mm, for example. Select from the range of ~2 mm or 0.4 mm to 2 mm and select the length dimension from the range of 20-75 mm or 20-50 mm. In addition, in a form in which the tip portion of the core base portion is tapered, for example, the axial dimension of the tip portion is selected from the range of 0.3 mm to 0.6 mm, and the axial dimension of the portion other than the tip portion is 0.8 mm to 2 mm. Select from a range. When the core base portion is curved from the middle portion or the root, the angle (the imaginary axis when the core base portion is assumed to extend linearly and the position where the perpendicular to the imaginary axis in the curved portion is the longest) The angle formed by a straight line connecting the boundary positions of the core base portion and the handle base portion on the imaginary axis line can be appropriately selected according to the design of the interdental cleaning tool.

The handle base portion used in the interdental cleaning tools of the second to fourth embodiments and other embodiments supports the core base portion and grasps the handle base portion with fingers to remove the core base portion. It is inserted between teeth to clean. Therefore, from the viewpoint of bonding strength between the handle base portion and the core base portion, it is preferable that the handle base portion is integrally formed with the core base portion. The material portion is composed of the resin composition (A) in the same manner as the core substrate portion. However, the present invention is not limited to this, and the handle base portion may be composed of a resin material other than the resin composition (A). In this specification, the core base material portion and the handle base material portion may be collectively referred to as the base material portion.

As the three-dimensional shape of the handle base portion of the present embodiment, any shape that is commonly used in the field of interdental cleaners can be appropriately adopted as long as it is a shape that can be easily gripped with fingers. be. The cross-sectional shape of the shaft-shaped handle base portion may be circular, oval (elliptical, elliptical, rounded rectangular, oval, oval, bale-shaped, etc.), teardrop-shaped, polygonal, or rounded corners. Square etc. are mentioned. The length dimension in the axial direction (the axial direction of the core base portion) of the handle base portion, the length dimension in the width direction perpendicular to the axial direction, and the thickness dimension are not particularly limited, but for example, the length dimension in the axial direction is It can be appropriately selected from ranges of 10 mm to 25 mm, a length dimension in the width direction of 4 mm to 10 mm, and a thickness dimension (shaft diameter dimension in the case of a shaft shape) of 0.5 mm to 3 mm.

The soft portion used in the interdental cleaners of the third to fourth embodiments and other embodiments is, for example, a tip portion inserted into at least a part of the surface of the core base portion or the interdental portion of the core base portion. and is composed of a material softer than the resin composition (A) (hereinafter simply referred to as "soft material"). The soft material is not particularly limited. a second form consisting of a single type or two or more elastomers; a fourth form consisting of a single type or two or more types of rubber; and a fifth form consisting of a mixture of an elastomer and a rubber. Here, the rubber includes styrene butadiene rubber, butadiene rubber, chloroprene rubber, isoprene rubber, butyl rubber, ethylene propylene rubber, acrylonitrile butadiene rubber, silicone rubber, fluororubber, acrylic rubber, urethane rubber, polysulfide rubber, chlorinated butyl rubber, Synthetic rubbers such as shrimp chlorohydrin rubber and natural rubbers can be mentioned.

The thermoplastic resin used in the soft material of the second form is the thermoplastic resin contained in the resin composition (A), or at least one selected from olefin resins and polyamide resins, or olefin resins, or It is a propylene polymer. The elastomer is an elastomer contained in the resin composition (A), an elastomer requiring compatibility with a thermoplastic resin, an elastomer having compatibility with an olefin resin, a styrene elastomer, an olefin elastomer, a vinyl chloride elastomer, and At least one thermoplastic elastomer or styrene elastomer selected from the group consisting of amide elastomers.

The elastomer used in the soft materials of the third and fifth modes is not particularly limited, and thermoplastic elastomers (TPE) such as styrene, olefin, vinyl chloride, polyamide, silicone, urethane, A thermosetting elastomer such as a fluorine-based elastomer can be used.

In the interdental cleaners of the third and fourth forms, when the core base material portion is made of the resin composition (A1) containing an elastomer, the elastomer contained in the soft material of the first to third and fifth forms is An elastomer different from the elastomer in the resin composition (A1) or an elastomer softer than the elastomer in the resin composition (A1) can be used. By configuring in this way, the hardness of the surface of the soft portion (softness during use) is emphasized independently, and the feeling of use is further improved.

The soft portion made of the soft material of the first to fifth forms may cover the entire surface of the core base material, but may cover a predetermined region from the tip to the middle of the core base material. preferable. Specifically, for example, it is preferable to cover a range of 10 mm to 25 mm or 12 mm to 22 mm from the tip of the core base portion with the soft portion. The thickness of the soft portion is selected, for example, from the range of 0.05 mm to 0.5 mm, 0.1 mm to 0.3 mm, or 0.1 mm to 0.2 mm.

In addition, the soft portion, which is used in the interdental cleaning tool of the fourth embodiment, is made of the first to fifth (or third or fourth) soft materials and has a plurality of protrusions erected on the surface, A plurality of projections are spaced apart from each other along the length and circumference of the flexible portion. The cross-sectional area of the projection on the surface of the soft portion is selected, for example, from the range of 0.03 mm ² to 1.5 mm ² . The height of the protrusion from the soft portion surface is selected, for example, from a range of 0.5 mm to 4.0 mm. The number of protrusions in the soft portion is selected, for example, from a range of 20 to 100, but may be smaller or larger than the range. The distance between one protrusion and another adjacent protrusion is selected, for example, from the range of 0.5 mm to 1.5 mm, but may be less or greater than the range. The three-dimensional shape of the protrusion is not particularly limited, but examples thereof include a conical shape, a pyramidal shape, a columnar shape, a prismatic shape, an axially flattened plate shape, and a tapered shape. Moreover, the cross-sectional shape of the protrusion includes a circular shape, an oval shape, a teardrop shape, a polygonal shape, and the like.

In another form, the soft portion covers the entire surface of the core base portion, and the side of the core base portion connected to the handle base portion is a covered soft portion having no projections on the surface. A protruding soft portion having a protrusion on the surface may extend from the end opposite to the handle base portion to the tip of the core base portion. The soft portion of this form can be used in the interdental cleaners of the third and fourth embodiments.

As described above, in the interdental cleaner of the present embodiment, at least the core base portion is made of the resin composition (A). There are no restrictions. Specific examples of interdental cleaners include interdental cleaners 1 and 2 shown in FIGS. The interdental cleaners 1 and 2 include core substrate portions 10A and 10B made of the resin composition (A), and handle substrate portions 11A and 11B connected to one ends of the core substrate portions 10A and 10B, respectively. , soft portions 12A and 12B covering the surfaces of the core base portions 10A and 10B, and a plurality of protrusions 13A and 13B projecting outward from the surfaces of the soft portions 12A and 12B. A cleaning tool. In any form of interdental cleaning tool, the core base material parts 10A and 10B are made of the resin composition (A), whereby the folding resistance of the core base material parts 10A and 10B is remarkably improved. It is also easy to insert into. The interdental cleaning tool 1 has a core base material portion 10A extending in one direction, and the interdental cleaning tool 2 has a core base material portion 10B extending in a curved manner.

The interdental cleaner of the present embodiment is manufactured, for example, by two-color molding using the resin composition (A) and first and second molds for molding conventional interdental cleaners. More specifically, for example, the resin composition (A) is melt-kneaded, the obtained melt-kneaded product is supplied into the first molding die, and an intermediate molded product (for example, a core base portion and it Interdental cleaning tool of the second embodiment consisting of a handle base portion) is obtained, and if necessary, the intermediate molded product is mounted in the second mold, and any one of the first to fourth embodiments is obtained. By supplying the melted and kneaded soft material into the second molding die, it is possible to obtain the interdental cleaners of the third and fourth embodiments having the soft portion on the surface of the core base portion. In addition, when obtaining the interdental cleaning tools of the first and second embodiments, it is not necessary to carry out two-color molding, and they can be manufactured by one-time molding.

In the interdental cleaning tool of the present embodiment (first to fourth embodiments and other embodiments), for example, a plurality of interdental cleaning tools are detachably connected one by one in the width direction. It may be in the form of an assembly of cleaning tools, or in a form in which a plurality of interdental cleaning tools are housed in a container or bag in a separate state (individually independent state).

(Test example 1)
An evaluation test of the interdental cleaning tool was carried out.
[Production of interdental cleaning tool]
A polypropylene resin having the following number average molecular weight and weight average molecular weight was prepared.
(a) weight average molecular weight 458000, number average molecular weight 87700
(b) weight average molecular weight 565000, number average molecular weight 111000
(c) weight average molecular weight 427000, number average molecular weight 85000
(d) weight average molecular weight 406000, number average molecular weight 85200
(e) weight average molecular weight 349000, number average molecular weight 73200
(f) weight average molecular weight 397000, number average molecular weight 75900

Each of the polypropylene resins (a) to (f) described above and glass fiber or talc as an inorganic filler are dry-mixed, and the content of glass fiber or talc is 15 to 30% by weight of the whole, and the balance is the above. A resin composition, which is a polypropylene resin having a predetermined weight-average molecular weight and number-average molecular weight, was prepared.

Using each of the obtained resin compositions, the total length is 48 mm, the dimensions of the handle base portion are 15 mm (maximum width) x 6.5 mm, and the side of the core base portion connected to the handle base portion is the first shaft portion. A second shaft portion extends from the end portion of the first shaft portion away from the handle base portion to the tip of the core base portion. The dimensions of the first shaft are 18 mm in length and 1.2 mm in diameter. The second shaft portion had a tapered shape that gradually decreased in diameter toward the tip side, and the diameter of the tip portion was 0.45 mm. A polystyrene-based elastomer was coated over the entire periphery of the core base material to form a soft part with a thickness of 0.2 mm. No projections were formed on the portion of the soft portion covering the first shaft portion, and a plurality of projections (conical shape with a height of 1 mm) were provided on the portion covering the second shaft portion. Thus, the interdental cleaning tool of the third embodiment was produced.

Each of the obtained interdental cleaners was subjected to the following evaluation tests. Table 1 shows the test results.
[90° bendable number test]
(1) The handle base portion of the interdental cleaner is held between a pair of fixing devices, and the interdental cleaner is vertically supported so that the tip of the cleaning portion faces vertically upward. The base of the cleaning part is the fulcrum of bending.
(2) Bend the tip of the cleaning part by 90° in one direction and maintain it for 3 seconds. This operation is 1 count.
(3) After the tip of the cleaning part is returned to its original position, it is bent 90° in the other direction and maintained for 3 seconds. This operation is 1 count. In addition, the one direction of (2) and the other direction here are adjusted so as to be substantially on a straight line.
(4) The operations of (2) and (3) are alternately repeated, and the number of counts until the cleaning part breaks or cannot be restored to its original state is counted.
(5) This test was carried out 10 times, and the values obtained by arithmetically averaging the counts of each time and rounding off to the second decimal place are shown in Table 1. In addition, in Table 1, Mw shall show a weight average molecular weight and Mn shall show a number average molecular weight. Also, the polypropylene-based resin is referred to as a PP-based resin.

[Vertical bending test strength]
The interdental cleaning tool and the compression jig are arranged such that the tip of the cleaning part of each interdental cleaning tool thus obtained faces upward and the tip vertically contacts the compression jig. Then, a compression test was performed using an autograph (manufactured by Shimadzu Corporation) at a compression speed of 10 mm/min to measure the maximum strength at which the cleaning portion was bent and fractured. In the test, 5 specimens were measured at each level, and the arithmetic mean value was taken as the vertical bending strength of the interdental cleaner. Table 1 shows the results.

[Bending fatigue test]
The bending fatigue resistance of the cleaned part was evaluated by the following test. After subjecting the interdental cleaners obtained in Examples 1 to 5 and Comparative Examples 1 to 4 to the following fatigue test (a), the following cantilever bending test (b) was performed.

(a) Fatigue test (1) A fatigue test model shown in FIG. 3 was prepared. A testing machine 30 is installed, a shallow jig storage case 35 with an open top is installed below the testing machine 30, and three cylindrical jigs 31 with a diameter of 10 mm are placed horizontally on the bottom surface of the jig storage case 35. The interdental part model 33 was produced by arranging and clamping and fixing them. The handle base portion 21 of the interdental cleaner 20 is clamped and fixed by the two divided lower ends 32 of the tester 30, and the tip of the cleaning portion 22 of the interdental cleaner 20 to the lower end 32 of the tester 30 is held. The interdental cleaning tool 20 was suspended vertically so that the length was 35 mm and a region of 5 mm from the tip of the cleaning part 22 was in contact with the cylindrical jig 31 in the middle of the interdental part model 33. .
(2) The testing machine 30 was rotated leftward on the paper surface, and the interdental cleaning tool 20 was fixed at position A at 45° to the left with respect to the vertical direction.
(3) Rotate from the state of (2) to the right side of the paper surface to move the interdental cleaning tool 20 from position A to position B, which is 45° right in the vertical direction, and then rotate the testing machine 30 to the left side of the paper surface, The interdental cleaning tool 20 was returned to the position A. The movement of the interdental cleaning tool 20 from position A to position B and from position B to position A was defined as one cycle, and was repeated a predetermined number of times. The rotation speed of the testing machine 30 was 30±3 cycles/1 minute.

(b) Cantilever bending test A test apparatus 40 shown in FIG. 4 was used. The test apparatus 40 includes a fixing jig 41 , a fulcrum jig 42 and a pressure device 43 . The fixing jig 41 is erected on the support plate 50 and horizontally supports the interdental cleaner 20 so that the cleaning portion 22 of the interdental cleaner 20 is exposed. The fulcrum jig 42 is a quadrangular prism member having a triangular shape with an acute apex angle when viewed in cross section in the longitudinal direction orthogonal to the width direction. The fulcrum jig 42 has its vertex (or edge line=acute-angled tip) 51 abuts on the lower surface at a position 7 mm from the tip of the cleaning part 22 of the interdental cleaning tool 20 fixed by the fixing jig 40. , projecting from the support plate 50. As shown in FIG. The pressurizing device 43 is supported by a support member (not shown) so as to be able to move vertically, and presses from above a position 3 mm from the tip of the cleaning portion 22 of the interdental cleaning tool 20 fixed by the fixing jig 41, while pressing the cleaning portion. 22 is provided so as to be able to display the pressure applied to it as a numerical value. In this test, the descending speed of the pressurizing device 43 was set to 20 mm/min.

Interdental cleaning tool 20 that has not been subjected to the fatigue test of (b) above (hereinafter referred to as "untested product") and interdental cleaning tool 20 that has been subjected to the fatigue test of (b) above (hereinafter referred to as "implemented product") ), using the test device 40 shown in FIG. The strength of the portion 22 was used. Then, the strength retention rate (%) of the implemented product relative to the non-implemented product was calculated from the following formula. In addition, the strength retention rate was obtained for each of the products that were subjected to one cycle of (a) and (3) above 3 times, 5 times, and 10 times, and the results are shown as a graph in FIG. The results of 10 runs are shown in Table 1 below.
Strength maintenance rate (%) of implemented product = (strength of implemented product / strength of unimplemented product) x 100

[Breaking resistance and interdental insertability due to repeated use]
10 expert panelists evaluated the breakage resistance and interdental insertability of the obtained interdental cleaners due to repeated use in all interdental areas in the oral cavity. The evaluation criteria by each expert panel are as follows.

<Evaluation Criteria for Folding Resistance Due to Repeated Use>
◎…Can be used repeatedly 5 times or more ○…Repeatedly used 3 to 4 times ×…Broken after one use

<Evaluation Criteria for Interdental Insertability>
◎…No flexion during insertion among 10 panelists ○…3 or less flexion during insertion among 10 panelists ×…5 or more flexion during insertion among 10 panelists

As can be seen from Table 1, when a polypropylene-based resin (PP-based resin) having a weight average molecular weight of less than 400,000 is used, the folding resistance of the core substrate portion, particularly the cleaning portion, is very low. In addition, when a polypropylene-based resin having a weight average molecular weight of 400,000 or more is used, in addition to obtaining a remarkable improvement in folding resistance, vertical bending strength (N), 90 ° bending number (times) , the bending fatigue property of the cleaning part, and the interdental insertability are all improved, and the improvement in the interdental insertability is particularly remarkable.

Reference Signs List 1, 2, 20 interdental cleaner 10A, 10B core base material 11A, 11B, 21 handle base material 12A, 12B soft part 13A, 13B projection 22 cleaning part 30 testing machine 31 cylindrical jig 32 lower end of testing machine Part 33 Interdental part model 35 Jig storage case 40 Testing device 41 Fixing jig 42 Fulcrum jig 43 Pressurizing device 50 Support plate 51 Fulcrum jig apex (tip)

Claims (9)

An interdental cleaning tool that includes an elongated shaft-shaped core base material and cleans interdental areas by inserting the core base material into interdental areas,
The core base portion is made of a resin composition containing a thermoplastic resin and an inorganic filler, and the thermoplastic resin has a weight average molecular weight of 400,000 or more and a number average molecular weight of 78,000 or more. Cleaning tool. The interdental cleaner according to claim 1 , wherein the thermoplastic resin has a weight average molecular weight of 420,000 or more and a number average molecular weight of 80,000 or more. The interdental cleaner according to claim 1 or 2 , wherein said thermoplastic resin is at least one selected from the group consisting of olefin resins, polyamide resins and polyester resins. The interdental cleaning tool according to any one of claims 1 to 3 , wherein the thermoplastic resin is an olefin-based resin, and the olefin-based resin is a propylene-based resin. The interdental cleaner according to any one of claims 1 to 4 , further comprising a handle base portion connected to one end of the core base portion. The interdental cleaning tool according to any one of claims 1 to 5 , further comprising a soft portion made of a material softer than the resin composition and covering the surface of the core base portion. The interdental cleaner according to any one of claims 1 to 6 , wherein the resin composition further contains an elastomer compatible with the thermoplastic resin. Interdental cleaning according to claim 7 , wherein the elastomer is at least one thermoplastic elastomer (TPE) selected from the group consisting of styrene elastomers, olefin elastomers, vinyl chloride elastomers, and amide elastomers. equipment. The tooth according to any one of claims 1 to 8 , wherein the inorganic filler is at least one selected from the group consisting of fibrous inorganic fillers, flaky inorganic fillers, and granular inorganic fillers. Cleaning tool.

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