Patent Publication Number: US-2018049531-A1

Title: Method of diffraction grating transfer to hair and fibers

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application Ser. No. 62/131,092, filed Mar. 10, 2015, the entirety of which is incorporated herein by reference. 
    
    
     FIELD 
     This disclosure is generally directed to imparting light diffracting patterns on fiber surfaces. 
     BACKGROUND 
     The practice of changing the color of fibers is known. For example, hair dying for cosmetic purposes has been around for several hundred years. Temporary hair dyes are applied on hair to change its appearance hiding graying hair or to stay in line with the latest fashion trends. Greeks and Romans used naturally occurring henna as a temporary hair dye while Arab authors described application of the paste formed by the mixture of PbO and slaked lime (Ca(OH) 2 ) in water on hair. Hair is presently colored with dyes, ground silica, or ground coated plastics (glitter). Adverse effects of these synthetic hair dyes often range from skin discoloration and allergic irritations to toxicity and cancer. 
     A non-chemical treatment for affecting the perceived color of fibers is environmentally attractive and needed in the art. 
     SUMMARY 
     In an embodiment, there is a method for treating a fiber, comprising: imparting a pattern from a diffraction grating onto a fiber surface, wherein the pattern is capable of diffracting incident polychromatic light into one or more dispersed visible colors, and wherein the fiber is not coated and the pattern is imparted directly onto the surface of the fiber. 
     In another embodiment there is a device for imparting a pattern onto a fiber comprising, a grating comprising a pattern that diffracts incident polychromatic light into dispersed visible colors; and a pressure application device to apply 1-100 psi to the grating. 
     Embodiments described herein provide for the nano-scale patterning of fibers, for cosmetic purposes, for example, by forming complex patterns on fibers in order to diffract incoming light so as to give the appearance that the fiber has been artificially colored but without the need for prior dye, chemical, glitter, or conditioner. In an embodiment, a polychromatic color dispersion is obtained. Benefits of embodiments described herein provide color treatment with effects lasting from, for example, days to weeks. 
     Other advantages of the embodiments will be set forth in part in the description which follows, and in part will be understood from the description, or may be learned by practice of the invention. The advantages will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed. 
     The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a perspective view of a device for imparting a pattern onto a fiber according to an embodiment. 
         FIG. 1B  illustrates a block configured with a nanopatterned surface that may be incorporated in the device of  FIG. 1A . 
         FIG. 2A-2E  illustrates a method of using a device, such as the device of  FIGS. 1A-1B  according to an embodiment. 
         FIG. 3  is a magnified view of the surface of a hair strand after patterning according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Reference will now be made in detail to the present embodiments, 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. 
     Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Moreover, all ranges disclosed herein are to be understood to encompass any and all sub-ranges subsumed therein. For example, a range of “less than 10” can include any and all sub-ranges between (and including) the minimum value of zero and the maximum value of 10, that is, any and all sub-ranges having a minimum value of equal to or greater than zero and a maximum value of equal to or less than 10, e.g., 1 to 5. In certain cases, the numerical values as stated for the parameter can take on negative values. In this case, the example value of range stated as “less that 10” can assume negative values, e.g. −1, −2, −3, −10, −20, −30, etc. 
     The following embodiments are described for illustrative purposes only with reference to the Figures. Those of skill in the art will appreciate that the following description is exemplary in nature, and that various modifications to the parameters set forth herein could be made without departing from the scope of the present invention. It is intended that the specification and examples be considered as examples only. The various embodiments are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments. 
     A method is disclosed for forming a nanoscale pattern on the surface of a fiber to change a color of the fiber as seen by a viewer. The fiber can be a natural fiber, for example, hair or fur, or a man-made fiber, for example, polymer, glass, etc. Accordingly, as used herein, the term “fiber” includes natural and synthetic fibers, tapes, and ribbons. In general, the fiber can also be any substrate that is softer than a surface that comprises a patterned surface, such as a diffraction grating, which may be pressed against the fiber in order to impart a complementary pattern on the surface of the fiber. No dyes are required for the fiber patterning process because the color results from diffraction of light caused by the pattern imparted on the fiber and not from any dye. Color can be “removed” or otherwise degraded by wetting or shampooing the treated hair. That is, wetting or shampooing the treated fiber, such as hair, may remove an impressed pattern that is formed according to methods described herein. 
     A device for imprinting fibers is also provided. The device can include a diffraction grating having one or more patterns disposed thereon, the one or more patterns having a pitch. The one or more patterns can be, but not limited to, sawtooth patterns, spiral patterns, ring patterns, Archimedean patterns, ellipsoidal patterns, patterns having hyperbolic rings, patterns having parabolic rings, and combinations thereof. As discussed above, the pitch of the one or more patterns can be about 100 microns or less, about 50 microns or less, or about 15 microns or less. The device can further include a device for applying pressure to the grating. The pressure can be a pressure sufficient to impart the one or more patterns of the grating onto the fiber, for example, a pressure of about 1-100 psi or. In an embodiment, the device for imprinting fibers can further include a heating device to heat the fiber, before or during application of the pressure to the grating. 
       FIG. 1A  is a perspective view of a device  110  for imparting a pattern onto a fiber, such as directly onto a surface of the fiber. The device includes a pattern  120  formed on a surface  117 . The pattern  120  may be a nanopatterned surface  122 . The device  110  includes press jaws  112 ,  113  and at least one heating element  114  for heating the press jaws  112 ,  113 . Each of press jaws  112 ,  113  may include a corresponding one of surface  116 ,  117 , respectively. At least one of an additional component may be disposed on each of press surface  116  and  117 . For example, a platen and/or a backing layer may be disposed on the press surfaces. While not limited to any particular embodiment, the backing layer may be selected from a layer of a heat-resistant, commercially available polymer, such as but not limited to TEFLON™ or aluminum foil. 
     The pattern  120  may be formed directly on one or both of surfaces  116 ,  117  of press jaw  112 ,  113  respectively. Alternatively, the pattern  120  may be formed on the surface of an interchangeable component. For example, as shown in  FIG. 1B , an interchangeable substrate  100 , such as a diffraction grating, may include pattern  120 . Another substrate (not shown) may include a different pattern. In other words, different patterned substrates may be used for imparting different corresponding patterns on the surfaces of the same or different fibers or on the same or different portions of the fiber surface, leading to different multiple color or image effects in the treated fiber(s). The interchangeable substrate may be configured for repeat use, may be stored for later use, or may be combined for simultaneous use with other ones of interchangeable substrates having the same or different patterns on a surface thereof. An embodiment device for treating hair includes a standard hair press with a nano-patterned thermal block inserted into the hair press. 
     The pattern  120  may be a nanopatterned surface  122  of the substrate  100 . The pattern  120  may be configured to come in contact with another surface, such as a fiber sample placed between press jaws  112  and  113 , such that it imparts a corresponding pattern on a surface of a fiber sample when the press jaws are pressed together. In other words, the fiber conforms to the shape of the pattern  120  as it is pressed between the press jaws  112  and  113 . 
     Each of press jaws  112 ,  113  may further include at least one heating element  114 , which may be resistive heating element that is energized with electric current. That is, electric current is sent to heating element  114 , which heats the press jaws  112 ,  113  so as to provide for hot pressing of all elements in between the jaws. 
       FIGS. 2A-2D  illustrate a method of imparting a pattern on a fiber, such as a hair, in, for example, a pressing device such as device  110 . At  FIG. 2A , an interchangeable substrate  100 , such as a diffraction grating that includes a pattern  120  may be placed in a corresponding slot  115  of press jaw  113 . The slot  115  is sized so as to receive substrate  100  and substantially prevent it from moving when press jaws are pressed together. At  FIG. 2B , press jaw  113  is positioned in working proximity to press jaw  112 . As shown in  FIG. 2C , a fiber  124  such as hair, is placed adjacent to the pattern  120 . The fiber  124  may be placed such that at least a surface thereof is in direct contact with the pattern or may be secured on a transfer substrate which is then placed over the pattern such that at least a surface of the fiber is in direct contact with the pattern. As shown in the inset of  FIG. 2C , the fiber  124  has at least a portion of surface  125  thereof in direct physical contact with the nanopatterned surface  125  of substrate  100 . 
       FIG. 2D  shows force (indicated by the arrows) being applied to press jaws  112 ,  113  in order to press them together, which squeezes together all elements in between the jaws (i.e. substrate  100  with nanopatterned surface  122 , sample fiber  124 , and press surface  116 ). As mentioned above, an electric current may be sent to heating element  114 , which heats the press jaws  112 ,  113  and the substrate  100  and makes the pressing a hot pressing, which provides for heating of the fiber  124  during the applying of the pressure provided by the force being applied to press jaws  112 ,  113 . 
       FIG. 2C  shows a “before pressing” sketch of details of magnified fiber, such as hair, prior to pressing with device  110 ,  FIG. 2D  shows a “during-pressing” sketch of the fiber during pressing with device  110 , and  FIG. 2E  shows an “after-pressing” sketch of the fiber after pressing to form a modified fiber having a nanostructured pattern imparted on the fiber surface that diffracts light. The sketches are perspective close up views. The inset in  FIG. 2C  shows an individual fiber which does not have a coating on its surface  125 . Meanwhile,  FIG. 2D  illustrates imparting a pattern onto the fiber surface, for example, by hot pressing the fiber, such as hair, with the pressing device  110  under conditions suitable for forming a complementary nanopatterned surface on the hair. In other words, the shape of the fiber is transformed by imparting pattern  120  from substrate  100  onto the fiber surface. Said another way, as  FIG. 2E  shows, surface portions of the fiber surface are imprinted from the nanopatterned surface of substrate  100  that diffracts incident polychromatic light into dispersed colors. Thus, as the sample of fiber  124  is pressed between press jaws  112  and  113 , the surface of the fiber is imparted with a corresponding pattern, such as a complementary pattern to nanopattern  127  that complements the nanopatterned surface  122 . The pressing is continued at conditions, for example, for a suitable time, pressure, and temperature, until the fiber conforms to the nanopatterned surface  122  so that surface of the fiber having this nanopatterned surface diffracts incident polychromatic light into dispersed colors of light. Duration of the heat and pressure can each vary from seconds to minutes. 
     In the case in which the fiber is hair, the hair may have a glass transition temperature in the range of from about 180° C. to about 220° C. Accordingly, the heating element may be heated so that the hair is heated to a temperature above its glass transition temperature. Additionally, a force may be provided by the press jaws  112 ,  113  such that a resulting pressure in the range of from about 1 to about 100 psi is applied against the fiber to impart the pattern formed by the nanopatterned surface  122  onto the fiber. The pressing force may then be discontinued and the press jaws  112 ,  113  may be separated to expose the transformed fiber having a corresponding pattern imparted on a surface thereon, such as a nanopatterned surface  127  as shown in  FIG. 2E . The pressed fiber sample may then be removed from the device  110 . 
     As a result of the fiber  124  being imparted with a complementary pattern on its surface, such as with a nanopattern  127 , the fiber diffracts polychromatic light into dispersed visible colors. The color of the fiber as seen by a viewer will depend on the angle of incidence of a light source onto the fiber, the angle of the viewer to the fiber, and the pitch of the grating. Exemplary polychromatic light may be selected from the group consisting of white light, sunlight, theatrical light, and combinations thereof. 
     It is noted that although only a single fiber sample is shown in the figures, the invention is not so limited. In fact, the fiber may be at least one fiber, for example a plurality of fibers. As mentioned above, the fiber may be a synthetic fiber or may be a natural fiber, such as hair. 
     In another embodiment multiple different patterns can be imparted to the fiber. Each pattern should be capable of diffracting incident polychromatic light into one or more dispersed visible colors. Therefore, the step of imparting a pattern onto a fiber surface may include imparting a first portion of the pattern from a first surface pattern, such as that from a first diffraction grating, onto the fiber surface and imparting a second portion of the pattern from a second surface pattern, such as that from a second diffraction grating on to the fiber surface, for example at the same or a different location on the fiber surface. In an embodiment, the first portion of the pattern may be provided on a surface of a first substrate, such as a first diffraction grating and the second portion of the pattern may be provided on a surface of a second substrate, such as a second diffraction grating. For example, the first substrate and the second substrate may be the interchangeable substrate described above and may each be pressed against the fiber surface by repeating the steps described according to  FIGS. 2A-2E  above. While this embodiment describes first and second patterns and first and second substrates that comprise the pattern, the invention is not so limited and multiple combinations of patterns and substrates may be used to impart a pattern onto the fiber as needed in order to provide the desired diffraction of polychromatic light so as to achieve the desired perceived fiber color. 
     The substrate comprising a surface with the pattern may include a nano-patterned thermal block. An embodiment nano-patterned thermal block may be prepared using any known method and device for such as, but not limited to, focused ion beam (FIB), photonic lithography, e-beam lithography, tool machining, ruling engines, diamond turning devices, and any other method or device that can produce nanometer scale features. In an example, a metal block with a pattern may be formed using a scribe machine to mill the pattern into a metal blank. A soda-lime glass casting of the patterned metal may then be used as the nano-patterned thermal block. 
     It is envisioned that a commercially available heating hair iron, such as one made by CHI or BABYLISS, could be modified according to an embodiment of this invention, by replacing a heating block in the commercially available hair iron with a heating block suitably configured with a nanopattern such as the aforementioned sawtooth nanopattern or some other nanopattern. A nanopatterned heating block prepared by FIB milling, or by some other process for creating suitable nanopatterns, could be used to modify the heating block of the commercially available heating device. Alternatively, a blank heating block adapted to fit into the commercially available heating iron could be milled with a nanopattern suitable for heating solution-coated hair and imprinting a complementary nanopattern into the resulting film. It is envisioned that a commercially available heating iron, such as one made by CHI or BABYLISS, could be modified to produce an embodiment apparatus that could treat fluid-coated hair according to the aforementioned process for providing hair with a film imprinted with a nanopatterned surface that would diffract incident polychromatic light into dispersed colors. This way, a person could treat their own hair or another person&#39;s hair according to an embodiment of this invention and provide their own hair or another person&#39;s hair with a nanopattern-imprinted polymer-containing film that diffracts polychromatic light such as sunlight or theatrical light into dispersed colored light. 
     Example 
     A method of an embodiment was used for non-pigment based coloring of polymer fibers (e.g., hair) by diffraction of light. The method was conducted by imparting a blazed diffraction grating&#39;s pattern onto a fiber of hair. 
     The setup consisted of: a diffraction grating, two steel blocks, a larger steel block, a microscope slide, and hair samples. A blazed diffraction grating was used in this work. It had 600 lines/mm with a 500 nm blaze. Two steel blocks were used for alignment and application of a uniform pressure over a ½″×½″ area between the grating and the hair sample. A larger steel block was used as a mass to apply a known force to the previously mentioned steel blocks thereby generating a nominal 15 psi pressure. The microscope slide was used for holding the hair sample in place while the pressure is applied. 
     The methodology of pattern transfer was as follows. First, the diffraction grating and smaller steel blocks were heated in a furnace to between 180-220° C. Heated components were then transferred out of the furnace into the fixture described above. A small steel block was placed with groove side up and the diffraction grating was placed in the groove. At this point the microscope slide with hair was placed with the hair side on the diffraction grating. The other small steel block was placed upon this stack of items and finally the massive block was placed on top of all components, thereby applying a large enough pressure (approximately 14-16 psi) to transfer the nanoscale pattern. Additional information can be found in an article entitled” Nano-Patterning of Diffraction Gratings on Human Hair for Cosmetic Purposes (Journal of Cosmetics, Dermatological Sciences and Applications, 2014, 4, 173-178) the contents of which are hereby incorporated by reference in its entirety. 
     A pattern including lines from the diffraction grating was imparted onto the hair fiber as shown in  FIG. 3  which is at 40× magnification, using UV filtered light, of the surface of a hair strand after patterning. The pattern includes lines on the hair which are approximately 1.67 microns apart (center-to-center distance). The process was performed on individuated hair fibers and on groups of hair fibers. When placed in ambient light a polychromatic spectrum of brilliant colors was observed. These colors depended on the pattern on the hair and on the incident light 
     While the present teachings have been illustrated with respect to one or more implementations, alterations and/or modifications may be made to the illustrated examples without departing from the spirit and scope of the appended claims. For example, it will be appreciated that while the process is described as a series of acts or events, the present teachings are not limited by the ordering of such acts or events. Some acts may occur in different orders and/or concurrently with other acts or events apart from those described herein. Also, not all process stages may be required to implement a methodology in accordance with one or more aspects or embodiments of the present teachings. It will be appreciated that structural components and/or processing stages may be added or existing structural components and/or processing stages may be removed or modified. 
     Further, one or more of the acts depicted herein may be carried out in one or more separate acts and/or phases. Furthermore, to the extent that the terms “including,” “includes,” “having,” “has,” “with,” or variants thereof are used in either the detailed description and the claims, such terms are intended to be inclusive in a manner similar to the term “comprising.” The term “at least one of” is used to mean one or more of the listed items may be selected. Further, in the discussion and claims herein, the term “on” used with respect to two materials, one “on” the other, means at least some contact between the materials, while “over” means the materials are in proximity, but possibly with one or more additional intervening materials such that contact is possible but not required. Neither “on” nor “over” implies any directionality as used herein. The term “about” indicates that the value listed may be somewhat altered, as long as the alteration does not result in nonconformance of the process or structure to the illustrated embodiment. Finally, “exemplary” indicates the description is used as an example, rather than implying that it is an ideal. 
     Furthermore, as used herein, the phrase “one or more of”, for example, A, B, and C means any of the following: either A, B, or C alone; or combinations of two, such as A and B, B and C, and A and C; or combinations of three A, B and C. 
     Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.