WO2009072747A1

WO2009072747A1 - Toothbrush and method of manufacturing the same

Info

Publication number: WO2009072747A1
Application number: PCT/KR2008/006412
Authority: WO
Inventors: Tae Yeon Kim
Original assignee: Tae Yeon Kim
Priority date: 2007-12-06
Filing date: 2008-10-30
Publication date: 2009-06-11
Also published as: KR20090060151A; EP2091384A1

Abstract

A toothbrush manufactured by injection molding and a method of manufacturing the toothbrush are disclosed. The toothbrush of the present invention includes a body part (110) which forms a handle of the toothbrush or is connected to a drive unit of an electric toothbrush, a head part (120) which extends from the body part, and bristles (130) which are supported on the head part and are brought into direct contact with teeth when brushing the teeth. Here, the bristles are manufactured by injection molding. In the present invention, because the bristles are formed by injection molding, unlike in the conventional techniques, the bristles are prevented from becoming removed from the toothbrush body, becoming worn, or being bent outwards. Thus, the teeth and the gums of a user are prevented from being injured by the bristles when brushing the teeth. Furthermore, it is easy to manufacture the toothbrush.

Description

TOOTHBRUSH AND METHOD OF MANUFACTURING THE

SAME

Technical Field

[1] The present invention relates, in general, to toothbrushes and methods of manufacturing the toothbrushes and, more particularly, to a method of manufacturing an integrated toothbrush through a single injection molding process or a double injection molding process, unlike a typical method in which bristles manufactured through a separate process are set into a head part of a toothbrush, and to a toothbrush manufactured by the method. Background Art

[2] Generally, toothbrushes include body parts, head parts and bristles, which come into direct contact with teeth when brushing to clean the teeth. Typically, in conventional techniques, such bristles are provided on the head parts by methods of setting the bristles into the head parts. However, unlike the conventional techniques, the present invention provides a method, in which bristles are formed along with a head part and a body part by injection molding or by double injection molding, and a toothbrush manufactured by the method.

[3] Recently, according to increasing interest in health and improving the quality of life, the public's interest in the health of teeth has increased. To improve the health of teeth, various kinds of toothbrushes have been developed and sold in the market. According to the development of techniques pertaining to toothbrushes, toothbrushes having several kinds of bristles have become widespread.

[4] FIGS. 1 and 2 are perspective views showing toothbrushes according to conventional techniques.

[5] As shown in FIG. 1, the toothbrush (Korean Utility Model Registration No.

20-0407515, entitled: toothbrush having increased cleaning ability) has bristles 3. An elastic member 4 is installed in a main body 2, in which the bristles 3 are set, so that the main body 2 has high elasticity. Thus, when the bristles 3 brush the outer surfaces of the teeth of a user, the main body 2 is bent inwards to correspond to the shapes of the teeth. When the bristles 3 brush the inner surface of the teeth, the main body 2 is bent outwards. As such, depending on the shapes and arrangement of the teeth, the main body 2 can be elastically bent, thus improving the ability to clean teeth.

[6] In this conventional toothbrush, the main body 2 extends from a handle 1, and the bristles 3 are set into the upper surface of the main body 2. The main body 2, in which the bristles 3 are set, is made of soft synthetic resin which is different from the material of the handle 1. The elastic member 4, which has predetermined elasticity and can be bent inwards or outwards and maintain the bent state, is installed in the main body 2. Thus, when brushing the inner surfaces or the outer surfaces of the teeth, the main body 2 can be bent inwards or outwards and maintain the bent state. Therefore, the advantage that the inner and outer surfaces of the teeth can be evenly cleaned is obtained.

[7] FIG. 2 illustrates a toothbrush according to another conventional technique (Korean

Utility Model Registration No. 20-0225409, entitled: toothbrush). In this technique, bristles 21 are set into a head part 20, which is provided on a front end of a toothbrush body 10. A handle part 12 and a neck part 11 are integrally coupled to the head part 20 in the longitudinal direction. A user holds the handle part 12 using his/her hand and brushes his/her teeth. Here, the head part 20 extends a predetermined length in a direction perpendicular to the longitudinal direction of the toothbrush body 10.

[8] In the case of this toothbrush, the head part 20 and the bristles 21 can easily access the molar teeth when brushing the molar teeth, which are disposed at the inside positions in the mouth of a user. Furthermore, when brushing the tongue or the inner or outer surfaces of the front teeth, the hand which holds the toothbrush body 10, the wrist and the arm can be stretched in a straight line, thus preventing the arm from being strained. Therefore, this toothbrush enables the old and the weak or a child to easily brush his/her teeth.

[9] However, in the case of the above-mentioned conventional techniques as well as in other conventional techniques, bristles are set into a head part of a toothbrush. Hence, as the toothbrush is used, some bristles may be removed from the head part or be undesirably bent outwards.

[10] The bristles come into direct contact with the teeth of the user in order to clean the teeth. However, in the case where some bristles are bent outwards or are removed from the head part when brushing the teeth, the gum may be injured by the bent bristles. Furthermore, there is a problem in that an effect of removing food remnants, trapped between the teeth, or dental plague is reduced, that is, the teeth cleaning ability is reduced. Moreover, when manufacturing the toothbrush, because the bristles are provided on the head part by a method of setting the bristles into the head part, the bristles may be easily removed from the head part or bent outwards, thus deteriorating the quality of the product. Disclosure of Invention Technical Problem

[11] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a method of manufacturing a toothbrush through an injection molding process, through which bristles along with a head part are formed, or through a double injection molding process, through which the head part and a body part are first formed by injection molding and then thin bristles are formed by injection molding, thus preventing the bristles from being undesirably bent or removed from the head part, unlike the conventional techniques, in which bristles are set into a head part of a toothbrush, and the object of the present invention is to provide a toothbrush manufactured by the method. Technical Solution

[12] In an aspect, the present invention provides a toothbrush, including: a body part for forming a handle of the toothbrush or to be connected to a drive unit of an electric toothbrush; a head part extending from the body part to support lower ends of bristles; and the bristles provided on the head part, the bristles being brought into contact with teeth when brushing the teeth, wherein the bristles are manufactured by an injection molding method.

[13] Preferably, the injection molding method may comprise an injection molding method, by which the body part, the head part and the bristles are formed at one time. Furthermore, the injection molding method may comprise a double injection molding method, in which the body part and the head part are first formed by injection molding and then the bristles are formed by injection molding. The double injection molding method may comprise a micro injection method. The injection molding method may comprise a double injection molding method, in which the body part, the head part and the bristles are formed by injection molding and then a rim of the head part is formed by injection molding.

[14] The injection molding method may comprise a double injection molding method, in which the body part and the head part are first formed by injection molding such that a resin injection hole, a plurality of bristle setting holes for forming the bristles and a hollow space is formed in the head part, the resin injection hole, the bristle setting holes and the hollow space being connected to each other, and then resin is injected into the resin injection hole such that the resin flows out of the head part through the bristle setting holes, connected to the hollow space, thus forming the bristles. The resin injection hole may be formed in an end of the head part. The bristles may comprise two or more kinds of bristles having different thicknesses. Each of the bristles may have a thickness ranging from 0.01mm to 0.2mm.

[15] The bristles may comprise two or more kinds of bristles having different lengths.

Each of the bristles may have a length ranging from 5mm to 20mm.

[16] The bristles may comprise two or more kinds of bristles having different angles, at which the bristles are inclined to a surface of the head part. The angles between the bristles and the head part may range from 70°to 110°. The bristles may contain an aromatic agent or an antibacterial agent. The bristles, formed on the head part, may be disposed at two or more of an upper surface, a lower surface, a left side surface and a right side surface of the head part.

[17] In another aspect, the present invention provides a method of manufacturing a toothbrush, including: the step of preparing a mold for manufacturing the toothbrush; the injection molding step; the step of cooling the mold; and the step of removing the toothbrush from the mold. The mold may comprise a micro mold.

[18] In another aspect, the present invention provides a method of manufacturing a toothbrush, including the steps of: preparing a mold for manufacturing the toothbrush; closing the mold; forming a body part and a head part of the toothbrush through an injection molding process; forming bristles through a double injection molding process; cooling the mold; and removing the toothbrush from the mold. The mold may comprise a micro mold. The bristles may be formed by injection molding.

Advantageous Effects

[19] In a method of manufacturing a toothbrush according to the present invention, bristles are formed by injection molding, unlike in the conventional techniques. Therefore, the bristles are prevented from being removed from the toothbrush body, being worn, or being bent outwards. Thus, the teeth or the gums of a user are prevented from being injured by the bristles when brushing the teeth. Furthermore, because the bristles are formed by injection molding and not by a method of setting them into the toothbrush body, there is an advantage in that it is easy to manufacture the toothbrush. Brief Description of the Drawings

[20] FIGS. 1 and 2 are perspective views showing toothbrushes manufactured according to conventional techniques;

[21] FIG. 3 is a flow chart of a method of manufacturing a toothbrush, according to a first embodiment of the present invention;

[22] FIG. 4 is a flow chart of a method of manufacturing a toothbrush, according to a second embodiment of the present invention;

[23] FIG. 5 is a perspective view of a toothbrush manufactured through an injection molding process of the method according to the first embodiment of the present invention;

[24] FIG. 6 is a perspective view showing a state of a toothbrush at a step before a double injection molding according to the second embodiment of the present invention;

[25] FIGS. 7 through 10 are views showing several examples of a toothbrush manufactured through injection molding processes according to the present invention; and [26] FIG. 11 is an assembly perspective view showing a toothbrush manufactured through an injection molding process according to another embodiment of the present invention. Best Mode for Carrying Out the Invention

[27] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

[28] FIG. 3 is a flow chart of a method of manufacturing a toothbrush, according to a first embodiment of the present invention. FIG. 4 is a flow chart of a method of manufacturing a toothbrush, according to a second embodiment of the present invention. FIG. 5 is a perspective view of a toothbrush manufactured through an injection molding process of the method according to the first embodiment of the present invention.

[29] As shown in the drawings, resin to be used for forming bristles 130, a body part 110 and a head part 120 of a toothbrush through an injection molding process, and a mold for forming the bristles 130, the body part 110 and the head part 120 are prepared (SlOO).

[30] After the mold is prepared, the mold is closed (S200). Thereafter, resin is injected into the mold to form the bristles 130, the body part 110 and the head part 120 at one time (S300).

[31] Here, as the injection molding process, an injection molding method using a micro mold may be used. In this injection molding method, a micro molding product can be rapidly formed by heating a mold. In detail, injected resin is evenly charged into the cavity in the mold by rapid heating and, thereafter, the mold is rapidly cooled, thus rapidly forming a product.

[32] Recently, according to an increase in demand for plastic products, a technique for forming a thin wall part, which has a thickness of lmm or less, or a thickness to length ratio of 1 : 100 or less, or a technique of forming a micro shaped part or of forming a micro pattern on a surface of a part is required. For this, injection molding conditions (temperatures of resin and a mold, an injection speed, an injection pressure and a holding pressure) must be precisely set, unlike when forming typical products. In the case of the micro injection mold, the above conditions can be met. Therefore, in the present invention, it is preferable that such a micro injection mold be used.

[33] After resin has been injected into the mold, the step of compressing the injected resin may be conducted to form a product into a desired shape. After the resin injection step has been conducted, a cooling step is conducted (S400). Subsequently, the mold is opened and a produced toothbrush is removed from the mold (S500).

[34] Meanwhile, as shown in FIG. 4, the toothbrush of the present invention may be man- ufactured by a method in which after the step of simultaneously injection-molding the body part 110 and the head part 120 is conducted (S310), a double injection molding step is conducted.

[35] The double injection molding means an injection molding method using two different kinds of materials. In detail, in such double injection molding, using two kinds of resins or two colors of resins, and using two injection molding apparatuses and injectors, which are constructed such that a rotating device is coupled to a driving plate, or cores or slide structures, a first intermediate product is formed using a mold that can be used for double injection molding, and a second resin is charged into a space defined between the first intermediate product and a second cavity, thus forming a final product.

[36] In such double injection molding, because the first and second cavities are precisely defined, restriction in shape is reduced and various designs are realized, so that it can be applied to various products. Furthermore, the injection molding is conducted through a single process, unlike the typical injection molding process, in which two kinds of intermediate products are formed through two steps and the intermediate products are thereafter produced into a final product by a secondary process, such as welding or coating. Accordingly, there are advantages in that the production cost is reduced, and various kinds of products can be produced.

[37] Therefore, as a molding method used to form the bristles 130 of the toothbrush, the injection molding method may be used.

[38] The injection molding method is a well known technique, and is one molding method that has been widely used. An example of the injection molding method used in the present invention will be briefly explained.

[39] First, the body part 110 and the head part 120 of the toothbrush are formed by injection molding (S310). Thereafter, the bristles 130 are formed using resin which is different from that of the body part 110 and the head part 120 (S320). Here, micro molds (not shown), each of which has a thin disk shape, surround the outer edge of the head part 120 and the body part 110, and, thereafter, the bristles 130 are formed by the micro molds.

[40] In detail, several micro molds (not shown) are stacked on top of one another in the longitudinal direction of the head part 120, so that a large number of bristles 130 can be formed at one time. Furthermore, the arrangement of the bristles 130 can be easily changed depending on the shape of the mold. The head part 120 itself may serve as a mold.

[41] As described above, the head part 120 and the body part 110 of the toothbrush and the bristles 130 are formed using different materials. In detail, preferably, the bristles 130 are made of soft material such that the bristles 130 are easily bent and are relatively soft, and are thus able to conduct the same functions as conventional bristles. The body part 110 and the head part 120 are preferably made of relatively hard material, such that they are relatively hard and thus are not easily bent when a user brushes his/her teeth.

[42] After the double injection molding has been conducted, a cooling step S400 and a mold opening step S500 are conducted in the same manner as depicted in FIG. 3.

[43] Meanwhile, as shown in FIG. 5, the toothbrush according to the first embodiment of the present invention includes the body part 110, which is held by the user when brushing his/her teeth, the head part 120, which extends from the body part 110 and supports the bristles 130, and the bristles 130, which is fixed to the upper surface of the head part 120.

[44] The body part 110 may have a linear shape or, alternatively, it may have other various shapes, for example, a wave shape, such that the user can conveniently hold the body part 110 using his/her hand.

[45] The head part 120, which extends from the body part 110, enters the mouth of the user when brushing the teeth, and supports the bristles 130, which come into contact with the teeth of the user. Generally, the head part 120 is made of the same kind of resin as that of the body part 110.

[46] As described in FIGS. 3 and 4, the bristles 130 are formed on the head part 120 by the injection molding method but are not provided by a method of fitting separate bristles into the head part 120. In other words, when the body part 110 and the head part 120 are formed by the injection molding method, the bristles 130 are simultaneously formed by the injection molding method. Alternatively, the bristles 130 may be formed by the double injection molding process, in which, after the body part 110 and the head part 120 are formed by the injection molding method, the bristles 130 are formed using resin which is different from that of the body part 110 and the head part 120.

[47] Particularly, in the case of the double injection molding, it is preferable that a part be made of hard material is formed first and a part to be made of soft material is formed thereafter. The hard part and the soft part are determined by the injected resin material. Furthermore, preferably, the part which is first formed by injection molding, is made of resin, such as polypropylene or PCTA, and the part which is later formed by injection molding is made of resin, such as nylon or polybutylene terephthalate (PBT).

[48] Moreover, the toothbrush of the present invention may be manufactured by a double injection molding method, in which the head part 120 and the bristles 130 are first formed by injection molding, and a rim 121 of the head part 120, which is frequently brought into contact with the teeth or gums of the user when brushing the teeth, is thereafter formed using soft material. In addition, a portion of the body part 110 which is held by the hand of the user may be formed using soft material through a double injection molding process. Here, thermoplastic elastomer is preferably used as the soft material, which forms the rim 121 of the head part 120 or the portion of the body part 110 that is held by the user.

[49] FIG. 6 is a perspective view showing a state of a toothbrush at a step before a double injection molding according to the second embodiment of the present invention.

[50] As shown in the drawing, in this embodiment, a head part 120 and a body part 110 of the toothbrush are formed by injection molding. A plurality of holes 124, each of which has a predetermined size, is formed in the upper surface of the head part 120, that is, a portion of the head part 120 on which bristles are formed. The head part 120 has a hollow space 123 therein. A resin injection hole 122 for double injection molding is formed in the end of the head part 120 or in the junction between the body part 110 and the head part 120. Here, the resin injection hole 122, the hollow space 123 and the bristle setting holes 124 are connected to each other.

[51] When resin is injected through the resin injection hole 122 into the head part 120, which serves as a mold, the resin flows out of the head part 120 through the bristle setting holes 124, which are formed through the upper surface of the head part 120, thus forming the bristles.

[52] In the case where some holes of the bristle setting holes 124 have relatively large diameters and the remaining holes have relatively small diameters, thick bristles and thin bristles can be formed at the same time. Furthermore, long bristles and short bristles may be formed at the same time by increasing or reducing the thickness of the medial portion of the hollow space 123. In addition, the bristle setting holes 124 may be formed in directions inclined relative to the upper surface of the head part 120 but not formed perpendicular to the upper surface of the head part 120. In this case, the bristles can be formed on the upper surface of the head part 120 at predetermined inclined angles.

[53] FIGS. 7 through 9 are views showing several examples of a toothbrush manufactured through injection molding processes according to the present invention.

[54] As shown in FIG. 7, a toothbrush may be manufactured such that thicknesses of bristles 140 and 141, which are formed by injection molding, differ from each other. The reason that the thicknesses of the bristles 140 and 141 differ from each other is to enable the teeth to be cleaned according to the shape or arrangement of the teeth. Although the toothbrush of FIG. 7 has been illustrated as having a structure such that thick bristles 140 are disposed on an outer portion of the head part 120 and thin bristles 141 are disposed on an inner portion of the head part 120, the arrangement of the bristles is not limited to such special arrangement, so long as the bristles have different thicknesses. Furthermore, although the toothbrush of FIG. 7 has been illustrated as two kinds of bristles in differing thicknesses, three or more kinds of bristles differing in thicknesses may be formed. In other words, the number of kinds of bristles in differing thicknesses can be freely changed depending on the shape of the mold or the shapes of the bristle setting holes of FIG. 6.

[55] Meanwhile, as shown in FIG. 8, bristles 150 and 151 may be formed by injection molding to have different lengths. The reason that the bristles are formed such that the lengths thereof differ from each other is to enable the teeth to be cleaned according to the shape or arrangement of the teeth. Although the toothbrush of FIG. 8 has been illustrated as having a structure such that long bristles 150 are disposed on an outer portion of the head part 120 and short bristles 151 are disposed on an inner portion of the head part 120, the arrangement of the bristles is not limited to such special arrangement, so long as the bristles have different lengths. As well, although the toothbrush of FIG. 8 has been illustrated as bristles of two different kinds of length, three or more kinds of different-length bristles may be formed. That is, the number of kinds of different- length bristles can be freely changed depending on the shape of the mold or the shapes of the bristle setting holes of FIG. 6.

[56] As shown in FIG. 9, bristles 160 and 161, which are formed on the head part 120 by injection molding, may have different orientations. The reason that the bristles 160 and 161 have different orientations is also to enable the teeth to be cleaned according to the shape or arrangement of the teeth. Although the toothbrush of FIG. 9 has been illustrated as having a structure such that the bristles 160, which are disposed on an outer portion and the end of the head part 120, are inclined to the left when seen in the drawing, and the bristles 161, which are disposed on an inner portion of the head part 120, are inclined to the right when seen in the drawing, the arrangement of the bristles is not limited to such special arrangement, as long as the bristles have different orientations. In addition, although the bristles have been illustrated as being oriented in two directions, the bristles may be oriented in three or more directions. The orientations of bristles can be freely changed depending on the shape of the mold or the shapes of the bristle setting holes of FIG. 6.

[57] FIG. 10 is of front views and left side views showing several examples of arrangement of bristles of a toothbrush manufactured through injection molding processes according to the present invention.

[58] In the case of the conventional toothbrushes, bristles are typically set only in one surface of a head part of a toothbrush. However, in the toothbrush manufactured by the injection molding method according to the present invention, as well as the bristles being formed on the upper surface of the head part 120, the toothbrush may be manufactured such that bristles 170, 180, 190 are also formed on two or more of the lower side, left side and right side surfaces of the head part 120. Therefore, the present invention can manufacture toothbrushes having various shapes, in which bristles are spaced apart from each other at angular intervals of 90°, 180°, 270°or 360°.

[59] In the case of a toothbrush, which is manufactured by such a method such that the bristles extend from the head part in several directions, the teeth of the user can be more efficiently cleaned, compared to a conventional toothbrush, in which bristles are set only in one surface of the head part so that only one surface of each tooth is brushed at one brushing motion.

[60] FIG. 11 is an assembly perspective view showing a toothbrush manufactured through an injection molding process according to another embodiment of the present invention.

[61] As shown in the drawing, the present invention may be applied to an electric toothbrush as well as a toothbrush having a typical handle part.

[62] In other words, the injection molding method according to the present invention can be used to manufacture an electric toothbrush, that is, a toothbrush using an electric device.

[63] In detail, the toothbrush according to the present invention includes a drive unit, which vibrates bristles 130. The toothbrush further includes a body part 110, a head part 120 and the bristles 130 which are connected to the drive unit. Here, the bristles 130 may be formed by injection molding.

[64] In the case where the bristles 130 are formed by injection molding, the bristles 130 may be formed such that the lengths, thicknesses or orientations of the bristles differ from each other or such that bristles are formed on several surfaces of the head part, in the same manners those shown in FIGS. 5 through 10.

[65] Meanwhile, in the above-stated embodiments, if each bristle is too long, the bristle may be undesirably cut. If each bristle is too short, it is difficult to clean the teeth of the user. Therefore, the bristles must have appropriate lengths. In the case of the typical conventional toothbrushes, in which bristles are manufactured through a separate process and set into a head part, each bristle has a length ranging from 10mm to 13mm. However, the length of each bristle may be longer or shorter than that of the above-mentioned bristle. Preferably, each bristle has a length ranging from 5mm to 20mm.

[66] With regard to the thickness of each bristle, if the bristle is excessively thick, the cleaning ability thereof is reduced. If the bristle is excessively thin, it is difficult to manufacture the toothbrush, and there is a probability of the bristle being undesirably cut. Therefore, each bristle must have an appropriate thickness. Typically, in the case of the conventional toothbrushes, in which bristles are manufactured through a separate process and set into a head part, each bristle has a thickness ranging from 0. lmm to 0.2mm. However, in the case of the present invention using the double injection molding method, because each bristle can be formed such that it is relatively thin, the bristle can be manufactured to have a thickness ranging from 0.01mm to 0.2mm.

[67] Furthermore, it is preferable that an angle of each bristle relative to the head part 120 be within a predetermined angle. If the angle of each bristle relative to the head part 120 is too small, that is, if the bristle, which extends outwards from the head part 120, is excessively slant to one side, it is difficult to manufacture the toothbrush, and it is inconvenient to use it. Therefore, an angle of each bristle relative to the head part 120 must be appropriately set and, preferably, it ranges from 70°to 110°.

[68] Meanwhile, when the bristles 130 through 161 are formed through the above- mentioned methods according to the present invention, antibacterial agent or aromatic agent may be mixed with the resin used to form the bristles, such that the bristles can contain antibacterial agent or aromatic agent.

[69] Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

[1] A toothbrush, comprising: a body part for forming a handle of the toothbrush or to be connected to a drive unit of an electric toothbrush; a head part extending from the body part to support lower ends of bristles; and the bristles provided on the head part, the bristles being brought into contact with teeth when brushing the teeth, wherein the bristles are manufactured by an injection molding method.

[2] The toothbrush according to claim 1, wherein the injection molding method comprises an injection molding method, by which the body part, the head part and the bristles are formed at one time.

[3] The toothbrush according to claim 1, wherein the injection molding method comprises a double injection molding method, in which the body part and the head part are first formed by injection molding and then the bristles are formed by injection molding.

[4] The toothbrush according to claim 3, wherein the double injection molding method comprises a micro injection method.

[5] The toothbrush according to claim 1, wherein the injection molding method comprises a double injection molding method, in which the body part, the head part and the bristles are formed by injection molding and then a rim of the head part is formed by injection molding.

[6] The toothbrush according to claim 1, wherein the injection molding method comprises a double injection molding method, in which the body part and the head part are first formed by injection molding such that a resin injection hole, a plurality of bristle setting holes for forming the bristles and a hollow space is formed in the head part, the resin injection hole, the bristle setting holes and the hollow space being connected to each other, and then resin is injected into the resin injection hole such that the resin flows out of the head part through the bristle setting holes, connected to the hollow space, thus forming the bristles.

[7] The toothbrush according to claim 6, wherein the resin injection hole is formed in an end of the head part.

[8] The toothbrush according to claim 1, wherein the bristles comprise two or more kinds of bristles having different thicknesses.

[9] The toothbrush according to claim 8, wherein each of the bristles has a thickness ranging from 0.01mm to 0.2mm.

[10] The toothbrush according to claim 1, wherein the bristles comprise two or more kinds of bristles having different lengths.

[11] The toothbrush according to claim 10, wherein each of the bristles has a length ranging from 5mm to 20mm.

[12] The toothbrush according to claim 1, wherein the bristles comprise two or more kinds of bristles having different angles, at which the bristles are inclined to a surface of the head part.

[13] The toothbrush according to claim 12, wherein the angles between the bristles and the head part range from 70°to 110°.

[14] The toothbrush according to claim 1, wherein the bristles contain an aromatic agent.

[15] The toothbrush according to claim 1, wherein the bristles contain an antibacterial agent.

[16] The toothbrush according to claim 1, wherein the bristles, formed on the head part, are disposed at two or more of an upper surface, a lower surface, a left side surface and a right side surface of the head part.

[17] A method of manufacturing a toothbrush, comprising: a step of preparing a mold for manufacturing the toothbrush; an injection molding step; a step of cooling the mold; and a step of removing the toothbrush from the mold.

[18] The method according to claim 17, wherein the mold comprises a micro mold.

[19] A method of manufacturing a toothbrush, comprising the steps of: preparing a mold for manufacturing the toothbrush; closing the mold; forming a body part and a head part of the toothbrush through an injection molding process; forming bristles through a double injection molding process; cooling the mold; and removing the toothbrush from the mold.

[20] The method according to claim 19, wherein the mold comprises a micro mold.

[21] The method according to claim 19, wherein the bristles are formed by injection molding.