Patent Publication Number: US-2019168905-A1

Title: Beverage container with internal antimicrobial texture

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. provisional patent application No. 62,593,978 filed on Dec. 3, 2017, the entire content of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     This disclosure relates to flasks, and in particular, beverage containers. 
     Water bottles and other beverage containers typically comprise an internal compartment accessible only through a narrow opening sized to allow easy consumption of the contained beverage by mouth. This configuration makes cleaning of the interior of such containers difficult. Since the container contains water or other liquids supporting microbial growth, this cleaning difficulty presents a sanitary issue. 
     To address this sanitary issue, antibiotic chemical treatments to the interior surfaces of the beverage container have been utilized to inhibit microbial growth. However, such treatments expose the beverage to contamination by the antibiotic chemicals, leading to undesirable health effects and the promotion of antibiotic resistant microbes. Therefore, there exists a need to inhibit microbial growth in beverage containers without the use of chemical antibiotic treatments. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention meets the need identified above by providing a beverage container having an interior surface with an antimicrobial texture. Specifically, the invention recognizes the antimicrobial properties of surfaces texturized by exposure to a polarized femtosecond laser and applies this texture to the interior of a beverage container to solve the need discussed above. 
     In an embodiment, the beverage container has an interior surface, comprising a LIPSS texture, as defined herein. 
     In an embodiment, the beverage container has a beverage compartment entirely lined by a LIPSS texture. 
     In an embodiment, the beverage container contains a beverage in contact with a LIPSS texture on the interior surface of the beverage container. 
     In an embodiment, the beverage container has a vacuum insulation layer disposed between an interior surface and an exterior surface. 
     In an embodiment, the beverage container has an interior surface made of food grade 220 stainless steel with a LIPSS texture. 
     In an embodiment, the beverage container has an interior surface made of a polymer with a LIPSS texture. 
     In an embodiment, the beverage container has an interior surface made of a glass with a LIPSS texture. 
     In an embodiment, the antimicrobial beverage container is made by providing a beverage container with a beverage compartment and applying a LIPSS texture to an interior surface of that beverage compartment. 
     In an embodiment, the antimicrobial beverage container is made by providing a beverage container with a beverage compartment and applying a LIPSS texture to an interior surface of that beverage compartment by inserting a femtosecond laser applicator into the beverage compartment and etching the interior surface with the femtosecond laser applicator to form the LIPSS texture. 
     In an embodiment, the interior surface of the antimicrobial beverage container is steel, and its laser etching is performed with a Ti:sapphire laser amplifier system generating linearly polarized 30 femtosecond laser pulses at 1 kilohertz with a 790 nanometer central wavelength. 
     In an embodiment, the laser etching is performed by moving the beverage container relative to the femtosecond laser applicator to etch the entire interior surface of the beverage compartment. 
     In an embodiment, the antimicrobial beverage container is made by providing a beverage container with a beverage compartment and applying a LIPSS texture to an interior surface of that beverage compartment by inserting a milling head into the beverage compartment and milling the interior surface with the milling head to form the LIPSS texture. 
     In an embodiment, the milling is performed by moving the beverage container relative to the milling head to mill the entire interior surface of the beverage compartment. 
     In an embodiment, the LIPSS texture is added to the interior surface of the beverage compartment by additive manufacturing techniques. 
     In an embodiment LIPSS texture is added to the interior surface of the beverage compartment by injection molding a liner using a mold configured with a negative texture complementary to the LIPSS texture and bonding the liner onto the interior surface of the beverage compartment. 
     In an embodiment, an antimicrobial beverage container is made by providing a mold that is configured to cast an interior compartment of a beverage container lined with a LIPSS texture and casting the antimicrobial beverage container with the mold. 
     In an embodiment, a mold that is configured to cast an interior compartment of a beverage container lined with a LIPSS texture is created by providing a template beverage container, applying a LIPSS texture to an interior surface of the template beverage container to form a LIPSS textured template and casting the mold using the LIPSS textured template. 
     In an embodiment, the LIPSS texture can be applied to the interior of the template beverage container by inserting a femtosecond laser applicator into the template beverage container, and etching the interior surface with the femtosecond laser applicator to form a LIPSS texture on the interior surface, where the femtosecond laser applicator uses a Ti:sapphire laser amplifier system generating linearly polarized 30 femtosecond laser pulses at 1 kilohertz with a 790 nanometer central wavelength. 
     In an embodiment, injection molding is used to create the antimicrobial beverage container from the mold. This can be performed by injection molding the entire final antimicrobial beverage container in one piece, or by injection molding a liner using the mold and bonding the liner to line the interior of a pre-existing beverage container. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a cross-section of the beverage container. 
         FIG. 2  is an electron micrograph showing an exemplar pattern and scale of LIPSS texture. 
         FIGS. 3 to 12  are flowcharts of methods of manufacturing the beverage container. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As seen in  FIG. 1 , the present disclosure sets forth a beverage container  1  with a beverage compartment  2  having an antimicrobial “LIPSS texture”  3  on the interior surface  4  of the beverage container  1  which defines the beverage compartment  2 . As used in this disclosure, “LIPSS texture” means the texture that results from etching a surface with a linearly polarized femtosecond laser as described below, and therefore the antimicrobial “LIPSS texture”  3  as shown in  FIG. 1  is not drawn to scale but rather is shown as enlarged symbolic projections indicating a surface having LIPSS texture. For clarity, the invention disclosed herein is not limited to textures directly formed by lasers, but includes any process that can recreate the LIPSS texture defined herein. 
     Femtosecond lasers create surface ripples in multiple types of material according to their femtosecond pulse duration and pulse frequency. The common term for these ripples is laser induced periodic surface structures (LIPSS) which is a description of the surface texture that results when energy is transferred to a surface through multiple bursts from a linearly polarized femtosecond laser with intra-burst delays in the 1-400 picosecond range, which can be further classified as “low spatial frequency” LIPSS (LSFL) having spatial periodicity (A) slightly lower than the laser wave length (λ) (typically λ/2≤Λ≤λ). It has been observed that LSFL surfaces effectively prevent the attachment and growth of bacteria and other microbes. The formation of LSFL surfaces has been ascribed to the interaction between scattered electromagnetic waves and incident laser pulses at surface defects, which are tiny imperfections at the nanoscale. The resulting surface is created due to inhomogeneous absorption of the laser&#39;s radiation by electrons in the irradiated material, which in turn modulates the energy concentration onto the material. For semiconductors and metals, the generation of LSFL with parallel orientation to the laser polarization has been shown to excite surface plasmons polaritons. In LSFL with parallel orientation to the incident light&#39;s polarization, the occurrence of radiation remnants or specific electromagnetic modes has been inferred. LSFL periodicity has also been inferred from mathematical modeling, which can predict periodicity based on multiple factors such as laser wavelength, angle of incidence, wave vector of the incident of irradiation and the roughness and permittivity of the surface. Ripples periodicity is another way to affect the final surface and can be set discretely by using the higher laser harmonics, or continuously varied by tuning the laser wavelength through optical parametric amplification. In an embodiment, the LIPSS texture comprises intersecting wave etchings with features in the range of 5-500 microns on the z and y axis. In a preferred embodiment, LIPSS texture is the texture created on food grade 220 stainless steel by a Ti:sapphire laser amplifier system generating linearly polarized 30 femtosecond laser pulses at 1 kilohertz with a 790 nanometer central wavelength. 
     Such etching creates a texture with microscopic features in a pattern and scale like the intersecting waves shown in  FIG. 2 . Specifically, certain surfaces created by these lasers can prevent microbial growth indefinitely due to the geometry of the surface. Thus, forming surfaces in this manner avoids the usage of chemicals to prevent microbial growth. 
     Returning to  FIG. 1 , the beverage container  1  may further comprise an insulating space  6  disposed between the interior surface  4  and an exterior surface  5  of the beverage container  1 . The insulating space  6  may be evacuated or may contain air or any other insulating material. The beverage container  1  may also comprise an opening  7  that may have a narrower cross-sectional dimension than the corresponding cross-sectional dimension of the beverage compartment  2 . 
     To form the interior surface that is antimicrobial, the interior surface may be directly etched with a laser. Preferably the interior surface of a reusable, vacuum-insulated bottle is used in this embodiment. Application of the laser etched LIPSS texture may be achieved by using a custom engineered platform and that allows the laser applicator to enter the mouth of the bottle and move with three degrees of freedom within the space formed by the body of the container. The container may be made from food grade 220 stainless steel. However, it should be understood that the container may be made of a polymer, glass, or any other material that is amenable to being etched by a laser to form the LIPSS texture necessary to make the interior of the container anti-microbial. 
     The container or any component of the container may be directly laser etched, milled, created by additive manufacturing techniques, or molded through an injection molded process which includes a mold that may be machined or etched with a negative texture that is necessary for the surface of the molded component to replicate the LIPSS texture to achieve anti-microbial properties. A component etched, milled, additively created or molded with a LIPSS texture may be inserted, or secured into a housing component, or prefabricated vacuum sealed bottle and may act as the interior wall of the beverage container either permanently or temporarily. A component etched, milled, additively created or molded with a LIPSS texture acting as the interior wall of the bottle may be permanently secured into the housing unit using an ultrasonic welding press, vibration welder, staking press, or any form of mechanical or manual mending, melting or welding. A component etched, milled, additively created or molded with a LIPSS texture acting as the interior wall of the bottle may be permanently secured into the housing unit using any form of adhesive or sealant. 
     As seen in  FIG. 3 , the antimicrobial beverage container can be made a first step S 1  of providing a beverage container with a beverage compartment, and a second step S 2  of applying a LIPSS texture to an interior surface of that beverage compartment. 
       FIG. 4  shows an embodiment of step S 2  of  FIG. 3 . In this embodiment, the LIPSS texture is applied to an interior surface of that beverage compartment by a first substep S 2 . 1  of inserting a femtosecond laser applicator into the beverage compartment and a second substep S 2 . 2  of etching the interior surface with the femtosecond laser applicator to form the LIPSS texture. 
     In an embodiment, the interior surface of the antimicrobial beverage container is steel, and its laser etching is performed with a Ti:sapphire laser amplifier system generating linearly polarized 30 femtosecond laser pulses at 1 kilohertz with a 790 nanometer central wavelength. 
       FIG. 5  shows an embodiment of substep S 2 . 2  of  FIG. 4  denoted as substep S 2 . 2 . 1 , wherein the laser etching is performed by moving the beverage container relative to the femtosecond laser applicator to etch the entire interior surface of the beverage compartment. 
       FIG. 6  shows another embodiment of step S 2  of  FIG. 3 . In this embodiment, a first substep S 2 . 1  applies the LIPSS texture to the interior surface of that beverage compartment by inserting a milling head into the beverage compartment, followed by substep S 2 . 2  of milling the interior surface with the milling head to form the LIPSS texture. 
       FIG. 7  shows an embodiment of substep S 2 . 2  of  FIG. 6  denoted as substep S 2 . 2 . 1 , wherein the milling is performed by moving the beverage container relative to the milling head to mill the entire interior surface of the beverage compartment. 
     In an alternate embodiment, the LIPSS texture is added to the interior surface of the beverage compartment by additive manufacturing techniques such as photopolymerisation, material jetting or extrusion, powder bed fusion and sheet lamination. 
       FIG. 8  shows another embodiment of step S 2  of  FIG. 3 . In this embodiment, a first substep S 2 . 1  creates a liner by injection molding using a mold configured with a negative texture complementary to the LIPSS texture, followed by substep S 2 . 2  of bonding the liner onto the interior surface of the beverage compartment. 
       FIG. 9  shows an embodiment where the antimicrobial beverage container is made by a first step S 1  of providing a mold that is configured to cast an interior compartment of a beverage container lined with a LIPSS texture, and a second step S 2  of casting the antimicrobial beverage container with the mold. This step S 2  can be performed by injection molding the entire final antimicrobial beverage container in one piece, or by injection molding a liner using the mold and bonding the liner to line the interior of a pre-existing beverage container. 
       FIG. 10  details an embodiment of step S 1  of  FIG. 9 . In this embodiment, the mold is created by a first substep S 1 . 1  of providing a template beverage container, followed by a second substep S 1 . 2  of applying a LIPSS texture to an interior surface of the template beverage container to form a LIPSS textured template and a third substep S 1 . 3  of casting the mold using the LIPSS textured template. 
       FIG. 11  details an embodiment of step S 1 . 2  of  FIG. 10 . In this embodiment, the LIPSS texture can be applied to the interior of the template beverage container by a first substep S 1 . 2 . 1  of inserting a femtosecond laser applicator into the template beverage container, followed by a second substep S 1 . 2 . 2  of etching the interior surface with the femtosecond laser applicator to form a LIPSS texture on the interior surface, where the femtosecond laser applicator uses a Ti:sapphire laser amplifier system generating linearly polarized 30 femtosecond laser pulses at 1 kilohertz with a 790 nanometer central wavelength. 
       FIG. 12  details an embodiment of step S 2  of  FIG. 9 . In a first substep S 2 . 1  of this embodiment, injection molding creates the liner using the mold, followed by a second substep S 2 . 2  of bonding the liner to line the interior of a pre-existing beverage container. 
     In summary, the invention is a beverage container having an antimicrobial LIPSS texture lining its interior, and various methods of creating this beverage container.