Abstract:
A method for producing a length of dental floss having a plastic part attached comprising the steps of providing a mould having a cavity; disposing a length of dental floss within the cavity; arranging the dental floss within the cavity such that the dental floss enters the cavity at a first location x and exits the cavity at a second location y and wherein the path length of the dental floss within the cavity is greater than the linear distance between the first location x and the second location y; and injecting a plastic material into the cavity to encapsulate the floss.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to dental floss comprising at least one bead attached via injection moulding and methods of producing said dental floss. 
       BACKGROUND OF THE INVENTION 
       [0002]    Dental floss is a well-known article used to promote oral hygiene by aiding in the removal of particles lodged in the interproxminal areas of the teeth. In interdental spaces, the tooth surfaces are best freed from plaque by means of dental floss. The surface of conventional dental floss is generally smooth and is sometimes waxed. This makes it difficult for an individual to hold the floss during use because it can not be tightly grasped and slips between the user&#39;s fingers. The handling of conventional dental floss is thus difficult. 
         [0003]    Often floss is purchased and packaged in a container/dispenser having an internal chamber for securely holding a large continuous length of floss wrapped around a spool or bobbin. A length of floss can be drawn and separated from the spooled portion remaining within the container. The floss emerges through a slit on the top of the container and can be separated from the bobbin by a cutting device. For a typical example see USD0339426. To floss the teeth, a person usually wraps the ends of the floss round the forefinger of each hand to be able to impose tension on a short length of the floss to thereby squeeze it between teeth and manipulate it to remove plaque. This can become painful if the floss is wrapped too tightly, or when the floss becomes taut during use. The resulting constriction of the fingers is unpleasant, and the fingers may remain constricted during the cleaning of a complete set of teeth. Furthermore, lack of control of the floss can lead to cutting of the gums. The chances of this happening increase when the floss is moistened by saliva as the friction between a user&#39;s fingers and the floss decreases if the surfaces are moistened. The dental floss can then slip. 
         [0004]    Accordingly, an object of the invention is the provision of a device that eliminates the need to wrap the floss round the fingers and which allows the user to effectively control the tension of the floss. It is known in the art to provide dental floss having protuberances along its length in order to improve the ability of the user to hold and use the floss. See for example U.S. Pat. No. 6,112,753, U.S. Pat. No. 5,305,768 and U.S. Pat. No. 4,016,892. However, a plastic part, such as a bead, fixed onto floss by injection moulding may slide on the floss, particularly when a traction force is applied between the plastic part and the floss. Sliding can occur easily when the floss passes through the plastic part in a straight line. It is therefore the object of the invention to reduce the sliding of the plastic part on the floss by deflecting the path of the floss within the plastic part, thus increasing the friction forces present and reducing the risk of the plastic part sliding on the floss. 
       SUMMARY OF THE INVENTION 
       [0005]    The invention relates to a method for producing a length of dental floss having a plastic part attached comprising the steps of providing a mould having a cavity; disposing a length of dental floss within the cavity; arranging the dental floss within the cavity such that the dental floss enters the cavity at a first location x and exits the cavity at a second location y and wherein the path length of the dental floss within the cavity is greater than the linear distance between the first location x and the second location y; and injecting a plastic material into the cavity to encapsulate the floss. The invention further relates to dental floss obtainable by this method. 
         [0006]    The invention further relates to dental floss comprising at least one plastic part wherein the dental floss enters the plastic part at a first location x and exits the plastic part at a second location y and wherein the path length of the dental floss within the plastic part is greater than the linear distance between the first location x and the second location y. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  shows a section in plane B-B of the mould shown in  FIG. 2   
           [0008]      FIG. 2  shows a section in plane A-A of the mould shown in  FIG. 1   
           [0009]      FIG. 3  shows a section in plane B-B of the mould shown in  FIG. 2  with a length of dental floss 
           [0010]      FIG. 4  shows a section in plane B-B of the mould shown in  FIG. 2  with a length of dental floss in an intermediate position as arranged by the pins 
           [0011]      FIG. 5  shows a section in plane B-B of the mould shown in  FIG. 2  with a length of dental floss in a final position as arranged by the pins 
           [0012]      FIG. 6  shows a section in plane B-B of the mould with the spherical part and floss shown in  FIG. 7   
           [0013]      FIG. 7  shows a section in plane A-A of the mould with the spherical part and floss shown in  FIG. 6   
           [0014]      FIG. 8  shows a section in plane D-D of the spherical part with floss shown in  FIG. 8  manufactured in the mould shown in  FIGS. 1-7   
           [0015]      FIG. 9  shows a section in plane C-C of the spherical part with floss shown in  FIG. 9 , manufactured in the mould shown in  FIGS. 1-7   
           [0016]      FIG. 10  shows a section of a mould with spherical part and floss 
           [0017]      FIG. 11  shows a section of the spherical part with floss, manufactured in the mould shown in  FIG. 10   
           [0018]      FIG. 12  shows a section of a mould with floss in the initial position 
           [0019]      FIG. 13  shows a section of the mould shown in  FIG. 12  with floss in an intermediate position 
           [0020]      FIG. 14  shows a section of the mould shown in  FIG. 12  with floss in an intermediate position 
           [0021]      FIG. 15  shows a section of the mould shown in  FIG. 12  with a spherical part and floss in the final position 
           [0022]      FIG. 16  shows a section of the spherical part with floss, manufactured in the mould shown in  FIGS. 12-15   
           [0023]      FIG. 17  shows a section of a mould with a spherical part and floss 
           [0024]      FIG. 18  shows a section of the spherical part with floss manufactured in the mould shown in  FIG. 17   
           [0025]      FIG. 19  shows a section of a mould with a spherical part and floss 
           [0026]      FIG. 20  shows a section of the spherical part with floss, manufactured in the mould shown in  FIG. 19   
           [0027]      FIG. 21  shows a section of the spherical part with floss shown in  FIG. 20   
           [0028]      FIG. 22  shows a section of an alternative spherical part with floss 
           [0029]      FIG. 23  shows a section of the spherical part of  FIG. 22  with a filling in the holes 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0030]    Referring first to  FIGS. 1 to 5 , in a first embodiment of the invention, a mould  101  for the injection moulding of a plastic part comprises a first mould half  102 , a second mould half  103  and a cavity  104 . The first mould half  102  comprises a core  105  within the cavity  104 . Preferably, and as illustrated in  FIG. 1 , the core is cylindrical. 
         [0031]    Pins  106  which may capable of movement by mechanical means can be placed over mould half  102 . A length of dental floss  107  is laid upon said pins. The length of dental floss can be fed from a spool that rotates around a spindle. Support rollers can guide and support the floss until it is directed to the pins and through the mould. Following injection and cooling, the floss comprising the moulded plastic parts can then be fed onto a second spool by support rollers. The floss is lightly tensioned by forces  108  by support rollers between the two spools. The pins  106  can be moved in a direction  109  by mechanical means. This results in the floss being deflected from a linear path and tensioned around the core  105  as illustrated in  FIGS. 4 and 5 . The floss is deflected into a groove within the mould half  102 . The second mould half  103  has a corresponding groove. The dental floss enters the cavity at a first location x and exits the cavity at a second location y. Due to the tensioning of the floss around the core  105  by the pins  106 , the path length of the dental floss  107  within the cavity  104  is greater than the linear distance between the first location x and the second location y. 
         [0032]    Referring to  FIGS. 6 to 9 , continuing the description of the first embodiment of the invention, after closure of the mould, a molten plastic material is injected into the cavity  104  of the mould  101 . On cooling, this results in a solid plastic part  110  which can be released by opening the mould. Preferably the plastic part is spherical (as illustrated in  FIGS. 6 to 9 ) or elliptical. Preferably the plastic part is spherical. This will avoid any sharp edges resulting which may cut the dental floss. The floss can remain tensioned by forces  108  and it lies in a channel  111  resulting from grooves in mould halves  102  and  103 . The plastic part is now attached to the floss. The dental floss enters the plastic part at a first location x and exits the plastic part at a second location y such that the path length of the dental floss within the plastic part is greater than the linear distance between the first location x and the second location y. The process can be repeated such that a series of plastic parts are moulded onto a length of dental floss preferably at a distance of from 200 to 400 mm apart. A length of dental floss comprising multiple plastic parts moulded upon it can be packaged into a dispenser such as that described in USD0339426. 
         [0033]    The core  105  results in the presence of a hole  112  in the plastic part  110  as illustrated in  FIGS. 8 and 9 . Use of the dental floss  107  generates traction forces  113  between the plastic part  110  and the dental floss  107 . As a result, the floss crosses through the hole  112 . Where the floss makes contact with the edge of the hole  112 , friction forces will be present thus reducing the sliding of the plastic part on the floss. 
         [0034]    In a second embodiment of the invention the cavity  204  may comprise multiple cores  205  as shown in  FIGS. 10 and 11 . This will result in multiple holes  212  in the plastic part  210 . Use of the dental floss  207  generates traction forces  213  between the plastic part  210  and the dental floss  207 . As a result, the floss crosses through the holes  212 . Where the floss makes contact with the edge of the holes  212 , friction forces will be present thus reducing the sliding of the plastic part on the floss. Increasing the number of cores will increase the frictional forces present and thus reduce the sliding of the plastic part on the floss. 
         [0035]    Referring to  FIGS. 12 to 16  and to a third embodiment of the invention, the first mould half  302  comprises two cores  305  within the cavity  304 . Prior to injecting the encapsulating plastic material into the mould, the dental floss can be tensioned by forces  308  and manipulated around the cores  305  until the floss is in the position of  FIG. 15 . During use, when traction forces  313  are applied, the dental floss  307  will make multiple points of contact around the open holes  312  thus increasing the frictional forces present and reducing the sliding of the plastic part  310  on the floss. 
         [0036]    Referring to  FIGS. 17 and 18  and to a fourth embodiment of the invention, the first mould half  402  comprises two cores  405  within the cavity  404 . Prior to injecting the plastic material into the mould, the dental floss can be tensioned by forces  408  and manipulated around the cores  405  until the floss is in the position of  FIG. 17 . During use, when traction forces  413  are applied, the dental floss  407  will make multiple points of contact around the open holes  412  thus increasing the frictional forces present and reducing the sliding of the plastic part  410  on the floss. 
         [0037]    Referring to  FIGS. 19 to 21  and to a fifth embodiment of the invention, the first mould half  502  does not comprise a core. Instead, three pins  506 , placed over the mould half  502 , are used to support the floss whilst it is tensioned by forces  508 . This will result in a solid plastic part  510  which does not comprise any holes. As such, the plastic part  510  can be smaller than those manufactured utilising a mould comprising a core. When traction forces  513  are applied between the plastic part  510  and the floss  507 , the floss will make contact with the edge of the plastic part  510 . Friction forces will be present thus reducing the sliding of the plastic part on the floss. 
         [0038]    Referring to  FIGS. 22 and 23  and to a sixth embodiment of the invention, the first and second mould halves may comprise multiple cores which the floss  607  is wrapped around, such that after the mould is injected with a plastic material, a plastic part according to  FIG. 22  is formed. The plastic part  610  will comprise holes  612 . These holes may be closed with plastic fillers  614 . 
         [0039]    The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as “40 mm” is intended to mean “about 40 mm ” 
         [0040]    Every document cited herein, including any cross referenced or related patent or application, is hereby incorporated herein by reference in its entirety unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it alone, or in any combination with any other reference or references, teaches, suggests or discloses any such invention. Further, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern. 
         [0041]    While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention. 
       DESCRIPTION OF REFERENCE NUMERALS 
       101  Mould   
       [0042]      102 ,  302 ,  402 ,  502  First mould half
 
 103  Second mould half
 
         104 ,  204 ,  304 ,  404  Cavity 
       105 ,  205 ,  305 ,  405  Core 
       106 ,  506  Pin 
       [0043]      107 ,  207 ,  307 ,  407 ,  507 ,  607  Length of dental floss
 
 108 ,  308 ,  408 ,  508  Tension forces
 
         109  Direction 
       110 ,  210 ,  310 ,  410 ,  510 ,  610  Plastic Part 
       111  Channel 
       112 ,  212 ,  312 ,  412  Hole 
       [0044]      113 ,  213 ,  313 ,  413 ,  513  Traction forces 
         614  Fillers 
       [0045]    x First location
 
y Second location