Abstract:
An apparatus and system for characterizing and quantifying certain attributes of antiperspirants and deodorants is provided, such as payout, friction, and flakeoff. The apparatus is capable of reproducibly applying antiperspirants and deodorant to a substrate.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a divisional application of U.S. Ser. No. 11/971,978, which claims priority to U.S. Application Ser. Nos. 60/976,527, filed on Oct. 1, 2007 and 61/015,852, filed on Dec. 21, 2007, all of which are incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    Antiperspirant or deodorant formulations have been developed with a range of different product forms. One of these is a so-called “stick” which is usually a bar of an apparently firm solid material held within a dispensing container and which retains its structural integrity and shape whilst being applied. When a portion of the stick is drawn across the skin surface, a film of the stick composition is transferred to the skin surface. Payout, of a deodorant stick, describes the weight lost to a surface from a typical application of the deodorant stick. This attribute and other rheological properties are considerations when developing new stick deodorant products. Therefore, a controlled method and device for measuring such properties is desirable. 
       BRIEF SUMMARY 
       [0003]    In an embodiment of the present invention, a system for measuring any or all of payout, static friction and kinetic friction is disclosed. The system includes at least one substrate positioned on an XYZ translational substrate bed. The system includes a sample holder for supporting a sample, wherein the sample holder and the sample are positioned perpendicular to the XYZ translational substrate bed. The system further includes a force device placing a predetermined weight onto the sample holder; the predetermined weight determines a contact force placed by the sample onto the substrate. The system also includes frictionless bearing table connected to the sample holder and a stationary frictionless bearing table positioned parallel to the XYZ translational substrate bed. The sample holder and the stationary frictionless bearing table are connected to a friction sensor. The system also includes a balance for obtaining a first substrate weight before movement of the XYZ translational substrate bed and a second substrate weight after movement of the XYZ translational substrate bed. 
         [0004]    The system further includes a controller operably coupled to the moving substrate bed and the friction sensor and configured to execute a machine readable program code containing executable instructions. 
         [0005]    In an embodiment of the present invention, a method for measuring payout is disclosed. The method comprises positioning a substrate of pre-known weight on an XYZ translational substrate bed; supporting a sample in a sample holder, wherein the sample is perpendicular to the XYZ translational substrate bed; placing a predetermined weight onto the sample holder so that the sample and substrate form a contact point; first moving the XYZ translational substrate bed at a first sweep speed in a first direction relative to the sample; second moving the XYZ translational substrate bed at a second sweep speed in a second direction relative to the sample; conducting the first moving and the second moving for a predetermined number of cycle(s); obtaining a second substrate weight of the substrate after the predetermined number of cycles; and determining a payout value based on the first substrate weight and the second substrate weight. 
         [0006]    In an embodiment of the present invention, a method for measuring one or more of static friction and kinetic friction is provided. The method comprises: positioning a substrate of pre-known weight on an XYZ translational substrate bed; supporting a sample in a sample holder, wherein the sample is perpendicular to the XYZ translational substrate bed; placing a predetermined weight onto the sample holder so that the sample and substrate form a contact point; first moving the XYZ translational substrate bed at a first sweep speed in a first direction relative to the sample; second moving the XYZ translational substrate bed at a second sweep speed in a second direction relative to the sample; conducting the first moving and the second moving for a predetermined number of cycle(s); during the first moving step and the second moving step, measuring one or more friction values at the contact point; analyzing one or more friction values generated at the sample contact point during the first moving step and the second moving step; and determining one or more of a static friction value and a kinetic friction value based on the one or more friction values. 
         [0007]    In an embodiment of the present invention, a method for measuring flakeoff is provided. The method comprises: providing a wool sample of a predetermined size; applying an initial weight of a material to the wool sample; attaching a first end of the wool to a stationary holder and a second end to a movable substrate bed; a stretching step comprising moving the movable substrate bed a predetermined distance and returning and then moving it to an opposite direction for the same predetermined distance and returning for 1 stretch; repeating the stretch step for a predetermined number of stretches; measuring the weight of the wool sample and material after the predetermined number of stretches; determining a weight loss of material from the wool sample as measured by an amount of material lost from the sample divided by the initial weight of material after the predetermined number of stretches. 
         [0008]    In each of the above methods, the methods are conducted on the above described system. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0009]    Reference will now be made in detail to embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
           [0010]      FIG. 1  illustrates an exemplary system to measure payout, static friction, kinetic friction, and combinations thereof. 
           [0011]      FIG. 2  illustrates an exemplary device to measure payout, static friction, kinetic friction, and combinations thereof. 
           [0012]      FIG. 3  illustrates an exemplary friction sensor. 
           [0013]      FIG. 4  illustrates a model for determining the friction coefficient. 
           [0014]      FIG. 5  illustrates an exemplary method using the systems described herein. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    As used throughout, ranges are used as a shorthand for describing each and every value that is within the range. Any value within the range can be selected as the terminus of the range. In addition, all references cited herein are hereby incorporated by reference in their entireties. In the event of a conflict in a definition in the present disclosure and that of a reference, the present disclosure controls. 
         [0016]    The present invention provides for systems and methods for measuring payout, static friction, kinetic friction or combinations thereof.  FIG. 1  illustrates an exemplary system  100  including a payout friction tester device  107 , a balance  106 , and a controller  101  having a machine readable program code  108  containing executable instructions. The device  107  for measuring payout, static friction, kinetic friction or combinations thereof can be operably linked to the controller  101  through a motor control unit  102 . The components of the exemplary system  100  illustrated in  FIG. 1  are described further below. 
         [0017]      FIG. 2  illustrates an exemplary payout friction device  107 . Device  107 , of system  100 , includes: at least one substrate  204  positioned on an XYZ translational substrate bed  209 ; a sample holder  201 ; a force device  224 ; a frictionless bearing table  211 ; a stationary frictionless bearing table  212 ; and a friction sensor  213 . Sample holder  201  supports sample  206  so that the sample  206  can be positioned perpendicular to the XYZ translational substrate bed  209  or so that the sample  206  contacts the substrate  204  perpendicularly. The sample holder  201  can also support the sample  206  such that the sample  206  contacts the substrate  204  at an angle that is less than 90°. 
         [0018]    Sample  206  can be any sample that can be analyzed for payout, static friction, kinetic friction or combinations thereof. Examples of samples include but are not limited to deodorants (e.g. a deodorant stick), antiperspirants, or combinations thereof. The sample  206  can be secured to the sample holder  201  using a screw  207 , such as a knurled thumbscrew, or other means for attachments, such as a clip or other means that can secure the sample  206  and assist in orienting its alignment. The sample clamp  210  can accept deodorant stick canisters  206  or other types of sample containers of various sizes and configurations. 
         [0019]    Substrate  204  may include materials such as copier grade paper, sandpaper (in differing grades of abrasion) or cloth may be used. In some embodiments, it is convenient to cut the substrate beforehand in bulk, for example, into approximately 13×25 centimeter strips so that single strips can be clamped in place before testing. 
         [0020]    Referring again to  FIG. 2 , the XYZ translational substrate bed  209  functions to move the XYZ translational substrate bed at a first sweep speed in a first direction and at a second sweep speed in a second direction relative to the sample  206 . The XYZ translational substrate bed  209  is operably coupled to a motorized screw table  202 . The motorized screw table  202  can be driven by an electronic drive unit  217 . The electronic drive unit  217  can operate in an automated mode or a manual mode. In the automatic mode, the electronic drive unit  217  can include a pulse width modulation speed control so to achieve precise speed control down to a zero velocity high torque condition. The motor  103  can be remotely driven by a velocity signal furnished by the controller  101 , for example by the controller&#39;s analog output channel. This allows precise control over the sweep rate and distance. In the manual mode, an operator manipulates the XYZ translational substrate bed  209  using controls of the electronic drive unit  207 . An example of an electronic drive unit  217  is, but not limited to, a Motamatic Drive Unit. 
         [0021]    In one embodiment, the XYZ translational substrate bed  209  also includes a heater  222 . In some embodiments, the heater  222  is capable of heating the substrate  204  to a temperature of about 26.7° C. to about 43.3° C. (about 80° F. to about 110° F.), about 32.2° C. to about 43.3° C. (about 90° F. to about 110° F.), about 32.2° C. to about 37.8° C. (about 90° F. to about 100° F.), about 35° C. to about 37.8° C. (about 95° F. to about 100° F.), about 36.7° C. to about 37.8° C. (about 98° F. to about 100° F.), 36.7° C. to about 37.2° C. (about 98° F. to about 99° F.), or about 37° C. (about 98.6° F.). 
         [0022]    Frictionless bearing table  211  is connected to the sample holder  201  permitting “frictionless” movement of the sample  206  supported by the sample holder  201 . In some embodiments, the frictionless bearing table  211  is positioned perpendicular to the XYZ translational substrate bed  209 . In other embodiments, the frictionless bearing table  211  is positioned vertically. The frictionless bearing table  211  functions to maintain an axis of pressure with testing and permits up and down movement of the sample holder  201 . The weight of the sample holder  201  can be counter balanced to zero force through counterweight  218  via the pulley tower  220  and cable  219 . Additional weight(s)  203  are placed on top of the sample holder  201  to define the magnitude of contact force (that which presses the sample against the surface). 
         [0023]    A stationary frictionless bearing table  212  is positioned parallel to the XYZ translational substrate bed  209 . In some embodiments, the stationary frictionless bearing table  212  is a horizontal frictionless bearing table. In other embodiments, the stationary frictionless bearing table  212  is positioned on internal rails supported by a plurality of ball bearings. The stationary frictionless bearing table floor  214  is part of the base  216  for device  107  and does not move permitting the measurement of force with respect to a solid reference. 
         [0024]    Friction sensor  213  is operably connected to the sample holder  201  and the stationary frictionless bearing table  212 . In one embodiment, friction sensor  213  can be mounted above the XYZ translational bed  209  on a bracket secured to the stationary frictionless bearing table floor  214 . Lateral friction is transmitted to the friction sensor  213  through a linkage  215  coupling arrangement. This linkage  215  can be oriented as close as practical to the plane of actual friction. Measuring friction at the sample contact point  223  requires that other friction points in the machine be eliminated or at least minimized as much as possible. To accomplish this, the stationary frictionless bearing table  212  supports the upper assembly completely. All of the assembly components can be bound together on a supporting structure  216  (shown as a sideways T in black). This “rides” as one piece on the stationary frictionless bearing table  212 . 
         [0025]    The friction sensor  213  can be any sensor that can be used to detect and determine friction. Transferring surface friction to the sensing element can be done by a mechanical linkage from the sample holder  201  to the friction sensor  213 . Referring to  FIG. 3 , the friction sensor  213  is operably coupled to a linkage  215  including a transmitter bar  301  and a linkage fork  303 . Transmitter bar  301  connects registered force at the sample contact point  223  ( FIG. 2 ) from the sample carriage mount  302  to the linkage fork  303 . The linkage fork  303  can be positioned between a pair of  0 -ring dampeners  306  and the pair of O-ring dampeners can be positioned between a pair of element stops  304 . The linkage fork  303  is suspended between two element stops  304  attached to the friction sensor probe  305 . When the linkage fork  303  pushes against a stop its force content is transferred to the friction sensor  213 . Physical contact at the stops is intentionally dampened by rubber “O” rings  306  which assist in smoothing out the elastic ringing that results from abrupt changes in force direction 
         [0026]    Referring again to  FIG. 2 , device  107  can include a force device  224  including a predetermined weight  203 , a counter weight  218 , a cord  219 , a pulley tower  220 , and two pulleys  221   a  and  221   b.  Force device  224  functions to place a predetermined weight  203  onto sample holder  201  where the predetermined weight  203  determines a contact force placed by the sample  206  onto the substrate  204 . The predetermined weight  203  and the counter weight  218  can be connected by the cord  219 . In some embodiments, the stationary frictionless bearing table  212  supports force device  224 . 
         [0027]    Referring to both  FIG. 1  and  FIG. 2 , system  100  may also include a controller  101 . for monitoring and controlling the desired variables. Any type of controller can be used to operate the system. Installed in the controller is a multi-functional AID converter card (DAQ) providing the necessary interface to the system to the various components. Controller  101  is operably coupled to the XYZ translational substrate bed  209 , the balance  106 , and the friction sensor  213  and configured to execute the machine readable program code  108 . Controller  101  is configured to execute machine readable program code  108  to perform various functions. In some embodiments, the functions include, but are not limited to configuring the balance  106  to obtain the first substrate weight before movement of the XYZ translational substrate bed  209  and the second substrate weight after movement of the XYZ translational substrate bed  209 . Controller  101  also configures the XYZ translational substrate bed  209  to move the XYZ translational substrate bed  209  at a first sweep speed in a first direction and at a second sweep speed in a second direction relative to the sample  206 . Controller  101  also analyzes one or more friction values, measured by the friction sensor, generated at the sample contact point  223  located between the sample  206  and the substrate  204  during movement of the XYZ translational substrate bed  209 . Controller  101  is further configured to determine a static friction value and a kinetic friction value based on the one or more friction values or determine a payout value based on the first substrate weight and the second substrate weight. 
         [0028]    The system of the present invention can also be configured to execute machine readable code containing executable program instructions to perform a variety of functions. In some embodiments, the system is configured to perform methods for measuring one or more of the following: payout, static friction and kinetic friction. One embodiment for measuring one or more of the following: payout, static friction and kinetic friction is illustrated in  FIG. 5 . In step  501 , a first substrate weight of a substrate is obtained. In one embodiment, a fresh piece of substrate  204  is placed into the balance  106  to be weighed. A continuous reading from the balance  106  is displayed in the window as the balance  106  is loaded. Once a stable reading is noted it can be “acquired” by pushing an on screen button labeled “Get weight”. The substrate  204  is then removed from the balance  106  and secured to the XYZ translational bed  209  with clamping plates  208  on the longitudinal sides. 
         [0029]    In step  502  the substrate is positioned on an XYZ translational substrate bed after obtaining the first substrate weight. In step  503  a sample is supported in a sample holder, wherein the sample is perpendicular to the XYZ translational substrate bed. In step  504  a predetermined weight is placed onto the sample holder so that the sample and substrate four a contact point. 
         [0030]    In step  505  the XYZ translational substrate bed  209  is first moved at a first sweep speed in a first direction relative to the sample. In step  506  the XYZ translational substrate bed is second moved at a second sweep speed in a second direction relative to the sample. In one embodiment, controller  101  begins the sweeping process when permission is given by an operator. In another embodiment, controller  100  begins the sweeping process based on an automated process where permission is not needed but instead the process begins when the sample  206  and the substrate  204  are secured. The sweeping steps  505  and  506 , are performed by a motorized screw table that is driven by an electronic drive unit. The electronic drive unit can have a pulse width modulation speed control. In some embodiments, the first moving step and the second moving step are repeated a predetermined number of times. In some embodiments, the first moving step and the second moving step are performed 1-50, 1-40, 1-30, 1-20, 1-10, 5-10, 5-15, 5, or 10 times. 
         [0031]    The distance moved in the first direction or the second direction by the XYZ translational substrate bed  209 , during the sweep steps  505  and  506  can be varied. In some embodiments, the distance of the first direction or the second direction is about 5 to about 50 cm, about 5 to about 40 cm, about 5 to about 30 cm, about 5 to about 20 cm, about 5 to about 10 cm. In some embodiments, distance of the first direction or the second direction is about 5, about 10, about 15, about 20, about 25, about 30, about 35, about 40, or about 50 cm. 
         [0032]    In step  507  during the first moving step and the second moving step, one or more friction values at the contact point is measured. In some embodiments, lateral friction can be measured directly as the XYZ translational substrate bed  209  sweeps in the first and second directions. In one embodiment, each response from the friction sensor  213  can be displayed in real time at controller  101 , as the sweeping continues. 
         [0033]    In step  508  a second substrate weight of the substrate after the first moving step and the second moving step is obtained. When the requested number of sweep steps has occurred the computer can re-display the “Get weight” window. The impregnated material, i.e. substrate  204 , can be removed from the lower bed and placed back into the balance  106  to be post-weighed. Payout is determined from the change in weight of the substrate  204 . 
         [0034]    In step  509  one or more friction values generated at the sample contact point during the first moving step and the second moving step is analyzed. In step  510  a static friction value and a kinetic friction value based on the one or more friction values are determined. In some embodiments the friction values are determined using the formula described herein. In step  511  a payout value based on the first substrate weight and the second substrate weight is determined. 
         [0035]    The present invention also provides for determining friction coefficients as the substrate and sample pass against one another. Using the systems described herein the sample moves or glides across the substrate in a pattern that involves acceleration and de-acceleration unlike the previous assumption that the motion occurs with uniform speed. Therefore, the following model based on Newton&#39;s second law was employed to calculate the coefficient of friction between the sample and the substrate.  FIG. 4  illustrates a model configuration of the substrate and sample passing against one another where F N  is the normal force applied to the skin  408 , F L  is the net lateral force across the skin  408 , a is the angle between the product  410  and the skin  408  at any given time. Based on the configuration displayed in  FIG. 4 , the friction coefficient at any given time can be express as following: 
         [0036]    Driving force=F L  sin (α)−F N  cos (α); Friction Force=μ*[F L  cos (α)+F N  sin (α)]; Newton&#39;s second law: F L  sin (α)−F N  cos (α)−μ*[F L  cos (α)+F N  sin (α)]=m*a; μ={F L  sin (α)−F N  cos (α)−m*a}/[F L  cos (α)+F N  sin (α)]; where m*a is the inertia of the (carriage+sample) times acceleration (a). 
         [0037]    The device  107  can also be used to measure flakeoff. Flakeoff is a measure of weight loss of material from a sample that has been stretched. It is a measure of how well a material (such as an antiperspirant/deodorant composition) will remain on a substrate. In one embodiment, a predetermined amount of material (for example, 0.65+0.03 g) to be tested is applied onto a piece of wool (Style #530 from Testfabrics, Inc.) of a predetermined size (for example, 7.6 cm×15.2 cm (3 in.×6 in.)). The wool is stretched a predetermined distance (for example 6 cm) and returned and then stretched to the opposite direction for the same predetermined distance and returned as one stretch. The weight of the wool and material is measured after a predetermined number of stretches (for example 50, 150, and/or 450 stretches). The percent weight loss of the material from the wool is recorded as a measure of flake-off. In one embodiment, the results from four samples can be averaged to give an averaged result. In device  107 , one end of the wool is attached to a stationary holder, which is attached to the frictionless bearing table  211  as replacement of sample holder  201 , and the other end of the wool is attached to substrate bed  209 ; oriented across the 15.2 cm length. The wool is thus perpendicular to the substrate bed  209 . Substrate bed  209  is then moved to stretch the wool. 
       EXAMPLES  
     Example 1 
     Payout/Glide on Sample 
       [0038]    Payout on a sample is measured using the system described herein. The system holds the deodorant stick flush to the substrate and moves the stick with a set speed over a distance of 100 mm with 500 g of force. The payout program measures the amount of the product applied to a cotton substrate after ten strokes, whereas the glide program measures the friction to move the stick across the substrate during one stroke. Immediately prior to payout analysis, three sticks of each experimental stick are cut flat and then the stick surface was is further flattened or conditioned on the instrument using a speed of 30 mm/sec for twenty cycles. In order to determine the payout, the cotton substrate is tared on a balanced and then clamped down on the substrate bed. The stick is passed over the substrate ten times at a speed of 20 mm/sec, and then the substrate is removed and returned to the balance to obtain the weight of the product on the substrate. The payout is measured three times on a stick and the average of the three results is calculated. The friction coefficient for the first and tenth strokes is recorded.