JP2009034308A - Toothbrush and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toothbrush which is an anchorless toothbrush having a head part of a thickness of 4 mm or less exhibiting a high operability in an oral cavity and enables moldability and durability to be sufficiently ensured while increasing the quality of its design by making its handle transparent, and to provide its manufacturing method. <P>SOLUTION: The toothbrush is made by forming molten lumps 4 at the base ends of bristle tufts 2 each of which is made of a bundle of several filaments. The bristle tufts 2 are fixed with their molten lumps 4 being buried in the head part 11. The thickness of the head part 11 is equal to or more than 1.5 mm and not more than 4 mm. Polyethylene terephthalate based resin exhibiting an intrinsic viscosity of 0.7 dl/g or less and a ductility of 200% or more is used as a material of the handle. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a toothbrush in which a hair bundle is implanted in a head portion of a transparent handle made of a synthetic resin material without using a flat wire, and a manufacturing method thereof.

  As a method of manufacturing a toothbrush, a molding space for molding a handle having a head portion in which a plurality of hair bundles are implanted, a handle portion as a handle, and a neck portion connecting the head portion and the handle portion is provided. Using a pair of molds, a plurality of hair bundles made by bundling a plurality of filaments are mounted at positions corresponding to the head part of one mold, and the base ends of the plurality of hair bundles are heated to form a base. After forming the molten lump at the end, with the mold closed, the molten resin is placed in the molding space, the synthetic resin material is injected into the molding space, and the handle is moved in the molding space. A so-called flat wire toothbrush manufacturing method in which a plurality of bristle bundles are integrally implanted in the head portion so as not to fall off is performed (see, for example, Patent Documents 1 and 2).

  Further, as the above flat wire toothbrush, a brush that improves the operability of the brush in the oral cavity by setting the thickness of the head part to 1.5 mm or more and 4 mm or less has been proposed (see Patent Document 3). .) Furthermore, in this Patent Document 3, a material using a thermoplastic resin having a tensile yield stress of 45 MPa or more and a flexural modulus of 1900 MPa or more is described as a handle material. As the thermoplastic resin, a polybutylene terephthalate resin, Polypropylene terephthalate resin, polyethylene terephthalate resin, polyethylene naphthalate resin, PCTA resin, PCTG resin and other polyester resins, polyacetal resin (homopolymer, copolymer), polycarbonate resin, aliphatic polyamide resin, aromatic polyamide resin The point which can employ | adopt resin which has resin as a main component is disclosed. When the handle of the toothbrush is made transparent, polyester resins such as polyethylene terephthalate resin, styrene resins such as methacryl styrene resin, ABS resin and AS resin, and polycarbonate resins are generally employed.

  On the other hand, in a toothbrush using a flat wire, after the handle is injection-molded, a flat wire is driven into the hair hole of the head portion together with the hair bundle, and the hair bundle is implanted in the head portion. A synthetic resin material that has toughness capable of preventing cracking at the portion where the flat wire is driven, has sufficient mechanical strength (durability) against repeated loads during brushing, and is harmless to the human body is employed. In addition, it has sufficient heat resistance so that the hair bundle does not easily come off even when the toothbrush is washed or disinfected with a hot water bath, and the handle may be altered or cracked under the influence of chemicals contained in the dentifrice. A synthetic resin material for the handle is selected in consideration of having chemical resistance so as not to cause it. In particular, when the thickness of the head portion is reduced, the hair pulling strength is reduced and the hair bundle is easily removed. Therefore, care must be taken in selecting the synthetic resin material constituting the handle.

JP 2003-9947 A JP 2003-102552 A Japanese Patent Laid-Open No. 2006-238928

  Since the technology related to the flat wire toothbrush is relatively newer than the flat wire toothbrush, the manufacturing technology of the flat wire toothbrush is mainly used. For example, the material of the handle and the filament is generally a material that can be used in the flat wire toothbrush. Is selected from. However, the mechanical characteristics required for the handle and the molding conditions of the handle are slightly different between the flat wire toothbrush and the flat wire toothbrush. There are not a few.

  For example, polyethylene terephthalate resin is used as the material for the transparent handle of the flat wire toothbrush. However, as described above, polyethylene can be used to ensure sufficient hair removal strength even when the toothbrush is washed or disinfected with a hot water bath. Among the terephthalate resins, those having a high heat resistance grade are used. However, since such a high heat resistance grade polyethylene terephthalate resin has a high intrinsic viscosity, when it is used for a flat wire toothbrush with a head portion thickness of 4 mm or less, it reaches the tip of the head portion. Resin material does not flow smoothly and molding defects are likely to occur. In order to force this to flow to the tip of the head part, if the molding temperature at the time of production is set high or the injection pressure is set high, the molten mass of the bristles in the flat wire toothbrush will melt. Production defects such as deformation and collapse of the hair bundle tend to occur. Even if the hair bundle does not fall down, the state in which the molten mass is deformed and becomes irregular is recognized by visual observation, so that the design is inferior. For this reason, it has been considered that polyethylene terephthalate resin can be used as a material for a transparent handle of a flat wire toothbrush but cannot be used as a material for a transparent handle of a flat wire toothbrush.

  Further, as other synthetic resin materials, methacryl styrene resin, ABS resin and the like having high resin fluidity are known, and when such highly fluid resin is used, a transparent material having a head portion having a thickness of 4 mm or less is used. It is easy to mold the handle, but because these resins have low elongation, the handle has low mechanical strength (durability), and for chemical resistance, when polyethylene terephthalate resin is used Will be inferior. Therefore, a flat wire toothbrush having a head part with a thickness of 4 mm or less cannot use a transparent handle. It is opaque, but it is opaque, but it uses only polypropylene resin with good moldability and high mechanical strength. The actual situation is not.

  The object of the present invention is a flat wire toothbrush having a head part with a thickness of 4 mm or less that is excellent in operability in the oral cavity, while the handle is made transparent to enhance the design, and the moldability and durability It is providing a toothbrush which can fully secure property, and its manufacturing method.

  As a result of earnest research to realize a flat wire toothbrush with a thin head and a transparent handle, which has been thought to be difficult to adopt, the inventor has heretofore been unsuitable as a material for the handle of a flat wire toothbrush. It has been found that a specific polyethylene terephthalate-based resin, which has not been noticed, can be used as a material for a handle of a flat wire toothbrush, and the present invention has been completed.

  The toothbrush according to the present invention has a handle composed of a head portion in which a plurality of hair bundles are implanted, a handle portion as a handle, and a neck portion connecting the head portion and the handle portion, and the proximal end of the hair bundle A toothbrush in which a molten lump is formed in a portion, the bristle bundle is fixed in a state where the molten lump is embedded in the head portion, and the thickness of the head portion is 1.5 mm or more and 4 mm or less, and the material of the handle As described above, a polyethylene terephthalate resin having an intrinsic viscosity of 0.7 dl / g or less and an elongation of 200% or more is used and has a transparent handle. In the present specification, a transparent handle means that the transmittance is 80% or more.

  In this toothbrush, a plurality of bristle bundles are integrally planted in the head part in a state where the molten lump formed at the base end part of the bristle bundle is embedded in the head part. Can prevent problems such as cracking of the head part due to a flat wire and reduction in hair pulling strength due to thinning of the head part, and the head part can be made into a thin head having a thickness of 1.5 mm to 4 mm. By configuring, the operability of the brush in the oral cavity can be improved.

  In addition, since the handle is made of a polyethylene terephthalate resin having an intrinsic viscosity of 0.7 dl / g or less, the molding temperature is not set high even if the thickness of the head is 1.5 mm or more and 4 mm or less. The resin material can be filled up to the tip of the molding space of the head portion. Moreover, since the handle can be molded without setting the molding temperature high, it is possible to prevent the molten lump from being melted by the heat of the resin injected into the molding space, and to reliably prevent manufacturing defects caused by melting the molten lump. be able to.

  Furthermore, since the molded handle is transparent, it is possible to obtain a toothbrush that is excellent in design, and that the molten lump formed at the proximal end of the bristle bundle is in an orderly state that is not deformed. Can be confirmed.

  In addition, since the polyethylene terephthalate resin has an elongation of 200% or more, the durability as a toothbrush, that is, the durability against repeated loads during brushing can be sufficiently ensured.

  When the above-mentioned polyethylene terephthalate resin is used in a conventional flat toothbrush, the resin is finely deformed by heating such as a hot water bath, and the flat wire fixed to the flocked hole is likely to come off together with the hair bundle. Since this flat wire is not used, the hair bundle does not easily come off even if a fine deformation occurs.

  Thus, according to the present invention, there is provided a flat wire toothbrush having a head portion having a thickness of 4 mm or less, which can make the handle transparent and enhance the designability while ensuring sufficient moldability and durability. realizable.

  Here, it is a preferred embodiment that a crystalline polyethylene terephthalate resin is used as the material of the handle. Strictly speaking, such a crystalline polyethylene terephthalate resin is composed of a crystalline part and an amorphous part, and the proportion of this amorphous part is very small compared to an amorphous polyethylene terephthalate resin. It is a feature. Since this amorphous part tends to become a starting point of fatigue failure due to repeated loading of the resin, the crystalline polyethylene terephthalate resin has superior durability if the elongation is equal.

  A method for manufacturing a toothbrush according to the present invention is a molding for molding a handle having a head portion in which a plurality of hair bundles are implanted, a handle portion as a handle, and a neck portion connecting the head portion and the handle portion. Using a pair of molds with a space, the head part has a thickness of 1.5 mm or more and 4 mm or less, and a hair bundle formed by bundling a plurality of filaments corresponds to the head part of one mold A plurality of hair bundles are mounted at the positions where the base ends of the plurality of hair bundles are heated to form a molten lump at the base end, the mold is closed, and the molten lump is placed in the molding space. In this state, a polyethylene terephthalate resin having an intrinsic viscosity of 0.7 dl / g or less and an elongation of 200% or more is injected into the molding space to form a transparent handle in the molding space, and a plurality of hair bundles Is integrally installed in the head part so as not to fall off.

  In this production method, a polyethylene terephthalate-based resin having an intrinsic viscosity of 0.7 dl / g or less and an elongation of 200% or more is injected at a molding temperature of 220 ° C. or more and 250 ° C. or less, and is injected into the molding space. In the same manner as the toothbrush according to the present invention, the handle is made transparent to enhance the design, since the handle is molded and the plurality of hair bundles are integrally planted in the head part so as not to fall off. In addition, a flat wire toothbrush having a head portion having a thickness of 4 mm or less that can sufficiently ensure moldability and durability can be manufactured.

  According to the toothbrush and the manufacturing method thereof according to the present invention, the handle is formed by injecting the synthetic resin material into the molding space in a state where the molten lump formed at the proximal end portion of the bristle bundle is arranged in the molding space. At the same time, since a plurality of hair bundles are integrally planted in the head part so as not to fall off, the head part is cracked by the flat line and the head part is thin as in the case of planting the hair bundle using a flat line. It is possible to prevent problems such as a drop in the hair removal strength due to the conversion, and to improve the operability of the brush in the oral cavity by configuring the head part to have a thickness of 1.5 mm or more and 4 mm or less.

  In addition, since the handle is made of a polyethylene terephthalate resin having an intrinsic viscosity of 0.7 dl / g or less, the molding temperature is not set high even if the thickness of the head is 1.5 mm or more and 4 mm or less. The resin material can be filled up to the tip of the molding space of the head portion. Moreover, since the handle can be molded without setting the molding temperature high, it is possible to prevent the molten lump from being melted by the heat of the resin injected into the molding space, and to reliably prevent manufacturing defects caused by melting the molten lump. be able to.

  In addition, since the polyethylene terephthalate resin has an elongation of 200% or more, the durability as a toothbrush, that is, the durability against repeated load during brushing can be sufficiently secured.

  Thus, according to the present invention, there is provided a flat wire toothbrush having a head portion having a thickness of 4 mm or less, which can make the handle transparent and enhance the designability while ensuring sufficient moldability and durability. realizable.

 As shown in FIGS. 1 and 2, the toothbrush 1 includes a handle 10 that includes a head portion 11, a handle portion 12 as a handle, and a neck portion 13 that connects the head portion 11 and the handle portion 12. And bristles 3 composed of a plurality of bristles 2 planted in the head 11 of the head, and when the handle 10 is molded, a bristles 2 formed by bundling a plurality of filaments as shown in FIG. The molten lump 4 is formed at the base end of the mold, and the handle 10 is formed by injecting the synthetic resin material into the molding space 22 in a state where the molten lump 4 is disposed in the molding space 22 of the molds 20 and 21. At the same time, a plurality of hair bundles 2 are integrally planted in the head portion 11 so as not to fall off, and the brush portion 3 is integrally provided on the handle 10.

  As the material of the handle 10, a crystalline or amorphous polyethylene terephthalate resin having an intrinsic viscosity of 0.7 dl / g or less and an elongation of 200% or more is used. Polyethylene terephthalate resin is a resin mainly composed of terephthalic acid (TPA) and ethylene glycol (EG). By changing the blending ratio or adding additives such as cyclohexanedimethanol (CHDM) The resin has various physical properties, and a resin mainly composed of a resin selected from polyethylene terephthalate resin, PCTG resin, PETG resin, and PCTA resin is used. In particular, a polyester resin in which an intrinsic viscosity is lowered by adding an additive or a polyester resin in which the intrinsic viscosity is lowered by suppressing the degree of polymerization are preferable because the filling property into the molding space 22 is good. The PCTG and PETG resins are copolymers of an ester compound of EG and TPA and an ester compound of CHDM and TPA, and the PCTA resin is an ester compound of CHDM and TPA, CHDM and isophthalic acid (IPA). ). Here, the main component means that the resin is contained in a blended or alloyed mixture with another resin in a proportion of 50% by weight or more, or is used together with another resin. The polymer contains a repeating unit of polymer of the resin in a proportion of 50% by weight or more. Further, the handle 10 can be molded using such a polyethylene terephthalate resin as it is, but the handle 10 can also be molded by adding a colorant in order to improve the distinguishability of the toothbrush 1. Suitable resins of the present invention include those containing TPA and EG as main components and alcohols added, etc., Bell polyester products Belpet IS121B, IP120B, IP121A, IP121B, IP140B, IP142B, Toyobo Viropet EMC-1563A, EMC-1232, unitika polyester resin MA-1304P and the like are desirable. In the present invention, the handle 10 is made of polyethylene terephthalate resin, but saturated polyester resin such as polypropylene terephthalate resin, polyethylene naphthalate resin, polytrimethyl terephthalate resin, polycarbonate resin, aliphatic polyamide resin, aromatic polyamide resin, etc. Polyamide resins, styrene resins such as methacryl styrene resin and ABS resin, etc. are somewhat inferior in performance in terms of all or part of moldability, durability and chemical resistance, but can be used as a material for the handle 10. Is possible.

  The shape of the head portion 11 of the toothbrush 1 is not particularly limited. However, in the illustrated embodiment, as shown in FIGS. 3 to 6, the shape of the head portion 11 is a substantially rectangular shape with four corners cut off, and the tip portion from the neck portion 13 side. The back surface side b of the flocked surface a in which the hair bundle 2 in the head portion 11 is implanted is substantially flush with the lower surface side of the neck portion 13. The flocked surface a side continues smoothly from the flocked surface a without a step, and is connected to the neck portion 13 via an arcuate inclined surface c that curves inward toward the neck portion 13 side.

  The thickness t of the head part 11 is 1.5 mm or more and 4 mm or less, preferably 1.5 mm or more and 3 mm or less. The arcuate inclined surface c preferably has a radius of curvature R slightly larger than the thickness t of the head portion 11 or substantially the same as the thickness t of the head portion 11, preferably 1.5 mm or more and 4 mm or less. More preferably, it is 1.5 mm or more and 3 mm or less.

  As described above, in the toothbrush 1, the radius of curvature R of the arcuate inclined surface c formed between the head portion 11 and the neck portion 13 is slightly larger than the thickness t of the head portion 11 or the thickness of the head portion 11. When the difference between the thickness T of the continuous portion d connected to the head portion 11 in the neck portion 13 and the thickness of the head portion 11 is substantially the same as the thickness t, the inclined surface c is the head portion. On the 11th side, it smoothly continues to the horizontal flocked surface a without a step, while the neck 13 side has a shape that stands substantially vertically. The head portion 11 and the neck portion 13 are connected via the inclined surface c having the shape as described above, so that the entire head portion 11 is formed uniformly thin, while the brush portion 3 and the neck portion 13 are formed. Even if it is bent repeatedly during brushing, it does not deform, has a waist, and has sufficient brushing properties.

  The length of the width w of the head portion 11 is not particularly limited, but if it is too wide, the operability in the oral cavity is impaired, and it is preferably about 5 mm to 15 mm, and more preferably 5 mm to 11. 5 mm or less. In addition, the thickness T of the portion d connected to the head portion 11 in the neck portion 13 is preferably at least 1.5 mm or more thicker than the thickness t of the head portion 11 and is approximately twice the thickness t of the head portion 11. . Accordingly, the thickness T of the portion d connected to the head portion 11 in the neck portion 13 is preferably 3 mm or more and 8 mm or less, and more preferably 3 mm or more and 6 mm or less. As the thickness t and width w of the head portion 11 and the thickness T of the portion d connected to the head portion 11 in the neck portion 13 are larger than the above range, the size of the periphery of the brush portion 3 in the toothbrush 1 is increased, and the operation in the oral cavity is performed. Reduce sex. On the other hand, a reduction in size beyond the above range is not preferable because the brush portion 3 becomes too small, leading to a reduction in the cleaning efficiency. If the head portion 11 is 1.5 mm or less, the hair removal strength of the hair bundle 2 is insufficient. The case comes out.

  Further, the material of the bristle bundle 2 to be implanted in the head portion 11 constituting the brush portion 3 is not particularly limited. For example, polyamide resin such as nylon or aramid resin, polyethylene terephthalate, polytrimethylene terephthalate Alternatively, polyester resins such as polybutylene terephthalate, polyolefin resins such as polypropylene, thermoplastic elastomer resins, and other conventionally known thermoplastic resin filaments can be used, and filaments having a diameter of 0.18 mm or less, and irregular filaments Soft filaments, composite filaments, and the like can also be used.

  The length of the hair bundle 2 from the flocked surface a, that is, the bristle length (H shown in FIG. 5) is not particularly limited, and may be the same as that of the normal toothbrush 1. When the hair length H of the hair bundle 2 is too long, the waist of the hair bundle 2 tends to be weak and the brushing property tends to be lowered. On the other hand, when the hair length H is too short, the waist becomes too strong and hard, and gums There is a possibility that irritation to the body becomes too strong. Therefore, although it depends on the material and thickness of the filament, it is 5 mm or more and 13 mm or less. However, in the toothbrush 1 of the present embodiment, the thickness t of the head portion 11 in which the bristle bundle 2 is implanted is substantially the same from the neck portion 13 side toward the tip portion, and the thickness t is the thickness of the neck portion 13. In addition to being as thin as 1.5 mm or more and 4 mm or less, which is about a half of T, the back surface side b of the flocked surface a is substantially flush with the lower surface side of the neck portion 13. That is, the flocked surface a is in a step-down state in which it is lowered from the upper surface side of the neck portion 13 by about one half of the thickness T of the neck portion 13, that is, as much as the thickness t of the head portion 11. For this reason, the length of the hair bundle 2 protruding from the upper surface side of the neck portion 13 (h shown in FIG. 5) is the same height as the upper surface of the neck portion 13 even if the hair length H of the hair bundle is the same. Compared to the conventional toothbrush 1, the amount of the stepped portion is shortened and the operability of the brush part 3 in the oral cavity is excellent. In addition, in the toothbrush 1 of the figure example, although the number of the hair | bristle bundle 2 which comprises the brush part 3 is 20, there is no limitation in particular. Moreover, there is no limitation in particular in the number of the filaments which comprise each hair | bristle bundle 2, It determines suitably with the material, thickness, etc. of a filament.

  Further, the cross-sectional shape of the neck portion 13 is not particularly limited, but as shown in FIG. 7, the cross-sectional shape orthogonal to the axial direction of the handle 10 is substantially circular so that the operability in the oral cavity is improved. From the viewpoint, in particular, when the cross-sectional shape of the portion d connected to the head portion 11 shown in FIG. 7 is circular, the mechanical strength and durability of the connecting portion between the head portion 11 and the neck portion 13, and consequently the toothbrush 1. It is also preferable from the viewpoint of mechanical strength and durability. Therefore, the width W of the neck portion 13 on the head portion 11 side shown in FIG. 4 is not particularly limited, but, like the thickness T, it is preferably 3 mm or more and 8 mm or less, and more preferably 3 mm or more and 6 mm or less.

  Further, in the illustrated toothbrush 1, the cross-sectional shape is formed to be gradually square from the neck portion 13 toward the handle portion 12, for example, a quadrangular shape with rounded four corners. By the way, there are a scrubbing method, a bath method, etc. as a brushing method recommended by a dentist. The scrubbing method is a method for brushing teeth by causing the bristles of the toothbrush 1 to oscillate in small increments perpendicular to the tooth surface. The bath method is a method of brushing teeth by applying the toothbrush 1 diagonally and vibrating it in small increments. These toothbrushing methods are performed by grasping the toothbrush 1 with a pen grip, but in order to brush the teeth correctly by these methods, the brush portion 3 is provided on the back side of the toothbrush 1, that is, among the handle portions 12. It is said that it is good to brush the teeth by holding the side away from a certain head part 11 and lightly applying the brush part 3 to the tooth surface. In the toothbrush 1 of the present embodiment, as described above, the length of the hair bundle 2 protruding from the upper surface side of the neck portion 13 (h shown in FIG. 5) is such that the flocked surface is the same height as the upper surface of the neck portion 13. Compared to a conventional toothbrush 1, the length of the hair is shortened by a stepped portion, and when the bristles of the bristles 2 are strongly applied to the tooth surfaces, the top surface of the neck portion 13 is easy to hit the tooth surfaces, and the bristles 2 are more than necessary. Strong contact with the tooth surface is suppressed. Furthermore, in the toothbrush 1 in the illustrated embodiment, as shown in FIGS. 1 and 2, an annular groove 14 is formed at a substantially central portion in the length direction. The distant portion can be correctly gripped with a pen grip, and the brush portion 3 can be applied lightly to the tooth surface, and effective brushing by the scrubbing method and bath method can be performed.

  Next, the manufacturing apparatus of the toothbrush 1 will be briefly described. As shown in FIG. 8, a pair of molds 20 and 21 having a mating surface in the middle in the thickness direction of the handle 10 are provided. The handle 10 can be injection-molded in a molding space 22 formed by closing the molds 20 and 21. At a position corresponding to the head portion 11 of the first mold 20 for forming the brush portion 3 of the handle 10, a plurality of hair bundle holding holes 23 into which the hair bundle 2 can be loaded are disposed at the toothbrush 1. A pressing plate 24 is provided on the side opposite to the mating surface of the first mold 20 to press the end of the hair bundle 2 loaded in the hair bundle holding hole 23. A heat plate 25 containing a heater or the like (not shown) capable of controlling the temperature is provided on the mating surface side of the first mold 20 so as to face the proximal end portion of the hair bundle 2, and the first mold 20 A coating layer 26 made of a resin having non-adhesiveness with respect to the melted filament is formed on the surface of the hot plate 25 facing the surface.

Next, a method for manufacturing the toothbrush 1 using the manufacturing apparatus will be described.
First, as shown in FIG. 8A, a plurality of hair bundles 2 formed by bundling a plurality of filaments made of a thermoplastic resin are produced, and the plurality of hair bundles 2 are formed in each of the first molds 20. The hair bundle 2 is inserted into the hair bundle holding hole 23 and cut into a predetermined length, and then the tip end portion of the hair bundle 2 is pressed by the pressing plate 24, and the hair bundle 2 is protruded to the side opposite to the pressing plate 24.

  Next, as shown in FIG. 8 (b), the hair bundle is heated so that the hot plate 25 heated to a set temperature equal to or higher than the melting temperature of the filament is substantially perpendicular to the hair bundle 2 loaded in the hair bundle holding hole 23. 2 is arranged so as to face the proximal end portion of 2, and as shown in FIG. 8C, the hot plate 25 is brought close to the proximal end portion of the hair bundle 2 to form the molten mass 4 at the proximal end portion of the hair bundle 2. To do. For example, the thickness of the hot plate 25 adjusted to a set temperature of 450 ° C. or more and 700 ° C. or less is brought close to the proximal end of the hair bundle 2 for a set time of 2 seconds or more and 8 seconds or less, and the thickness is 0.2 mm or more. A molten mass 4 of 1 mm or less is formed.

  Next, as shown in FIG. 8 (d), after forming the molten mass 4 at the base end of the hair bundle 2, the hot plate 25 is removed, and the first mold 20 and the second mold 21 are closed. In a state where the molten mass 4 is arranged in the molding space 22, a polyethylene terephthalate resin having an intrinsic viscosity of 0.7 dl / g or less and an elongation of 200% or more is injected from a non-illustrated injection cylinder at a molding temperature. Is injected into the molding space 22 in a state where the temperature is set to 220 ° C. or higher and 250 ° C. or lower, the transparent handle 10 is molded in the molding space 22, and the plurality of hair bundles 2 are integrated with the head portion 11 so as not to fall off. To plant.

  Thus, after the handle 10 is injection-molded in the molding space 22, the molds 20 and 21 are opened to release the molded product, and the toothbrush 1 is obtained.

  In this manufacturing method, since the handle 10 is formed using a polyethylene terephthalate resin having an intrinsic viscosity of 0.7 dl / g or less, even if the head portion 11 is a thin head having a thickness of 1.5 mm or more and 4 mm or less. The resin material can be filled up to the tip of the molding space 22 of the head portion 11 without setting the molding temperature high. In addition, since the handle 10 can be molded without setting the molding temperature high, it is possible to prevent the molten mass 4 from being melted by the heat of the resin injected into the molding space 22, and manufacturing defects caused by the melting of the molten mass 4 are also caused. It can be surely prevented. Moreover, since the elongation is 200% or more, the durability as the toothbrush 1, that is, the durability against repeated load during brushing can be sufficiently secured.

Next, another embodiment in which the configuration of the toothbrush 1 is partially changed will be described. The same members as those in the above embodiment are given the same reference numerals, and detailed description thereof is omitted.
As in the toothbrush 1A shown in FIG. 9 and FIG. 10 (f), instead of the head portion 11, the head main body portion 30 integrally formed with the handle 10A and the handle 10A are made of different members. The head part 11A which consists of the cover member 31 provided in the laminated form on the flocked surface side of can also be provided. When the toothbrush 1A is molded, as shown in FIG. 10E, the cover member 31 is disposed in the molding space 22A for molding the head portion 11A, and the flock hole 32 of the cover member 31 is inserted. In the state where the hair bundle 2 formed by bundling a plurality of filaments is arranged, the molten mass 4 is formed at the proximal end of the hair bundle 2, and the molten mass 4 is arranged in the molding space 22A. The synthetic resin material is injected into the handle 10A, and the plurality of hair bundles 2 are integrally implanted in the head portion 11A so as not to drop off.

  In this toothbrush 1A, the synthetic resin material constituting the handle 10A and the filament can be the same as in the above embodiment. Further, as the material of the cover member 31, a synthetic resin or a thermoplastic elastomer can be employed, and in particular, a synthetic resin or a thermoplastic elastomer having compatibility with the material of the handle 10A can be suitably employed. If the thickness of the cover member 31 is too thin, the molten resin flows out of the cover member 31 through the gap between the filaments to cause molding defects, and if it is too thick, the operability of the brush part 3 in the oral cavity decreases. Therefore, it is preferable to set to 0.5 or more and 3.5 mm or less. In the toothbrush 1A, the thickness of the head main body 30 formed integrally with the handle 10A can be set to 1.5 mm or more and 4 mm or less, and the cover member 31 is more than the head 11A of the toothbrush 1A of the embodiment. The thickness of the head portion 11A increases by the thickness of the handle, but the cover member 31 ensures a sufficient planting depth of the molten mass 4 relative to the head portion 11A and maintains the uprightness of the hair bundle 2, while At the time of molding 10A, it is possible to prevent the synthetic resin material from leaking to the hair bundle holding hole 23A side formed in the molds 20A and 21A.

Next, the manufacturing method of the toothbrush 1A will be described.
As shown in FIG. 10, a set of molds 20A and 21A for molding the toothbrush 1A is provided, and a cover is provided at a position corresponding to the head part 11A of the first mold 20A for molding the brush part 3 side. A recess 40 for mounting the member 31 is formed, and a plurality of hair bundle holding holes 23A into which the hair bundle 2 can be loaded are formed corresponding to the arrangement of the hair bundles 2 in the toothbrush 1A. A cylindrical convex portion 41 that fits into the annular concave portion 42 of the flock hole 32 of the cover member 31 is formed around 23A.

  When manufacturing the toothbrush 1A, first, as shown in FIG. 10A, the flock holes 32 of the cover member 31 and the bristles holding holes 23A of the first mold 20A are matched to each other. The peripheral annular recess 42 and the cylindrical convex portion 41 around the hair bundle holding hole 23A are concavo-convexly fitted, and the cover member 31 is mounted in a close contact state in the flocked portion cover mounting concave portion 40 of the first mold 20A. Then, the cutting plate 43 is closely fixed to the mating surface side of the cover member 31. Then, as shown in FIG. 10B, the hair bundle 2 formed by bundling a plurality of filaments, the hair bundle insertion hole 44 of the cutting plate 43, the flock hole 32 of the cover member 31, and the hair bundle of the first mold 20A. The holding hole 23A is loaded.

  Next, as illustrated in FIG. 10C, the hair bundle 2 into the molding space 22 </ b> A is obtained by moving the cutter 45 along the outer surface of the cutting plate 43 and cutting each hair bundle 2 with the cutter 45. Align the protruding length of.

  Next, the cutting plate 43 is removed, and thereafter, the hot plate 25 is brought close to the base plate as shown in FIG. 10 (e), the first mold 20A and the second mold 21A are closed, and the molten mass 4 is disposed in the molding space 22A. From the injection cylinder, a polyethylene terephthalate resin having an intrinsic viscosity of 0.7 dl / g or less and an elongation of 200% or more is injected into the molding space 22A in a state where the molding temperature is set to 220 ° C. or more and 250 ° C. or less. In the molding space 22A, the handle 10A is molded, and the plurality of hair bundles 2 are integrally implanted in the head portion 11A so as not to drop off. After cooling the molded product, as shown in FIG. 20A and 21A are opened and the molded product is And the mold, thus obtaining a toothbrush 1A.

  In this manufacturing method, the handle 10A is formed using a polyethylene terephthalate resin having an intrinsic viscosity of 0.7 dl / g or less, as in the above embodiment, so that the thickness of the head body 30 is 1.5 mm or more and 4 mm. Even with the following thin shape, the resin material can be filled up to the tip of the molding space 22A of the head portion 11A without setting the molding temperature high. Moreover, since the handle 10A can be molded without setting the molding temperature high, the molten mass 4 can be prevented from being melted by the resin injected into the molding space 22A, and manufacturing defects caused by the melting of the molten mass 4 can be reliably ensured. Can be prevented. Moreover, since the elongation is 200% or more, the durability as the toothbrush 1 </ b> A, that is, the durability against repeated loads during brushing can be sufficiently ensured.

  As shown in FIG. 11A, after forming the molten mass 4 at the proximal end of the hair bundle 2, the hair bundle 2 is pushed in the direction of the arrow to bring the molten mass 4 into contact with the cover member 31. Thereafter, as shown in FIG. 11B, a synthetic resin material can be injected into the molding space 22A. In this case, at the time of the injection molding of the synthetic resin material, the molten mass 4 becomes a plug, and the molten resin can be effectively prevented from flowing into the flocked hole 32 side of the cover member 31, so that the molten resin is the hair bundle 2. It is possible to more effectively prevent molding defects caused by protruding from the outside. Further, as shown in FIG. 12 (a), the flocked portion cover mounting recess 40 formed in the first mold 20A is formed to have a slightly larger outer dimension than the cover member 31, and the toothbrush shown in FIG. 12 (b). As in the head portion 11B of 1B, it is preferable to integrally provide a coupling portion 33 that surrounds the outer peripheral portion of the cover member 31 in the head main body portion 30B because the coupling strength between the cover member 31 and the head main body portion 30B can be improved. .

  As a material for the handle 10, seven types of synthetic resin materials including four types of polyethylene terephthalate resin (PET), methacrylstyrene resin (MS), ABS resin (ABS), and polypropylene resin (PP) shown in Table 1 were used. Table 2 shows the physical properties of these synthetic resin materials. Further, as the hair bundle 2, a hair bundle 2 in which 50 filaments made of nylon having a diameter of 0.19 mm were bundled was used. Then, as shown in FIG. 8, a molten lump 4 having a diameter of 1.7 mm to 2 mm and a thickness of 0.2 mm to 1 mm is formed at the proximal end portion of the hair bundle 2, and the molten lump 4 is formed in the molding space 22. The synthetic resin material is injected into the molding space 22 at the molding temperature shown in Table 2 to form the handle 10, and the plurality of hair bundles 2 are integrated with the head portion 11 so as not to fall off. After planting, seven types of toothbrushes 1 having the shapes shown in FIGS. 1 to 8 and the dimensions of each part shown in parentheses in FIGS. 1 and 3 to 5 were produced. The molding temperature was set by performing molding at a plurality of different molding temperatures in advance so that a defective filling of the synthetic resin material does not occur at the tip of the head portion 11 and the molding temperature is as low as possible.

  Then, for these seven types of toothbrushes 1A, evaluation of whether or not molding was possible and durability were evaluated. The evaluation of the formation failure was made by visually checking the molded toothbrush 1, where the bristle bundle 2 did not fall and the melted mass 4 did not melt and deformed was judged “OK”, and the bristle bundle 2 was fallen or melted. The thing which the lump 4 melt | dissolved and deform | transformed was made into "impossible". The durability was evaluated by conducting the following durability test. That is, with the handle portion 12 fixedly held and the handle 10 supported in a substantially horizontal cantilever shape, 1 kg of stress is applied to the center of the head portion 11 at a cycle of 4 times per second, Finally, the number of stresses applied until the neck 13 breaks is measured, and the number of times until the neck 13 breaks is defined as “x” when the number is 30000 times or less, and “△” when the number exceeds 30000 times and 60000 times or less. "," Over 60000 times was marked "O". Further, when the evaluation of moldability was “impossible”, the product could not be used as a product, and thus the durability test was not performed. Table 2 shows the moldability, durability test results, and durability evaluation.

  As shown in Table 2, even with the same polyethylene terephthalate resin, PET (C) and PET (D) are higher in molding temperature than 250 ° C compared to PET (A) and PET (B). Since it was necessary to set, the molten lump 4 melted and deformed at the temperature of the injected molten resin and the bristle bundle 2 collapsed, and only a toothbrush that was not realized as a product could be molded. For this reason, it is preferable to set the molding temperature to 250 ° C. or lower, and it can be set to 250 ° C. or lower and 220 ° C. or higher.

  Furthermore, PET (A) made of crystalline polyethylene terephthalate resin is the most preferred embodiment because it is superior in durability to PET (B) made of amorphous polyethylene terephthalate resin. I understand.

Toothbrush front view Top view of toothbrush Enlarged front view of the main part from the head part to the neck part of the toothbrush The enlarged plan view of the principal part from the head part of the toothbrush to the neck part Cross-sectional view taken along line V-V in FIG. Sectional view taken along line VI-VI in FIG. Sectional view taken along line VII-VII in FIG. (A)-(d) is explanatory drawing of the manufacturing method of a toothbrush Perspective view of toothbrush with other configuration (A)-(f) is explanatory drawing of the manufacturing method of the toothbrush (A), (b) is explanatory drawing of the manufacturing method of the toothbrush of another structure. (A), (b) is explanatory drawing of the manufacturing method of the toothbrush of another structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Toothbrush 2 Hair bundle 3 Brush part 4 Molten lump 10 Handle 11 Head part 12 Handle part 13 Neck part 20 1st metal mold 21 2nd metal mold 22 Molding space 23 Hair bundle holding hole 24 Holding plate 25 Heat plate 26 Coating layer a Flocking Surface b Back side c Inclined surface d Continuous portion 1A Toothbrush 10A Handle 11A Head portion 21A First mold 22A Molding space 23A Hair bundle holding hole 30 Head body portion 31 Cover member 32 Flocking hole 1B Toothbrush 11B Head portion 30B Head body portion 33 coupling part 40 concave part 41 cylindrical convex part 42 annular concave part 43 cutting plate 44 hair bundle insertion hole 45 cutter

Claims (4)

It has a handle consisting of a head part in which a plurality of hair bundles are implanted, a handle part as a handle, and a neck part that connects the head part and the handle part, and forms a molten mass at the proximal end of the hair bundle. And fixing the hair bundle in a state where the molten mass is embedded in the head part, and the toothbrush having a thickness of the head part of 1.5 mm or more and 4 mm or less,
As the handle material, a polyethylene terephthalate resin having an intrinsic viscosity of 0.7 dl / g or less and an elongation of 200% or more was used.
A toothbrush with a transparent handle.   The toothbrush according to claim 1, wherein a crystalline polyethylene terephthalate resin is used as a material of the handle.   A pair of molds provided with a molding space for molding a handle having a head portion in which a plurality of hair bundles are implanted, a handle portion as a handle, and a neck portion connecting the head portion and the handle portion. A plurality of hair bundles each having a thickness of the head portion of 1.5 mm to 4 mm and bundling a plurality of filaments are mounted at positions corresponding to the head portion of one mold, After heating the proximal end portion of the hair bundle to form a molten lump at the proximal end portion, the intrinsic viscosity is 0.7 dl / with the mold closed and the molten lump placed in the molding space. g and below, a polyethylene terephthalate resin having an elongation of 200% or more is injected into the molding space, and a transparent handle is molded in the molding space. A method for producing a toothbrush characterized by being planted. The method for manufacturing a toothbrush according to claim 3, wherein a crystalline polyethylene terephthalate resin is used as a material of the handle.

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