Abstract:
A membrane for covering the cut end of a tree trunk to prevent the tree from creating a seal after it has been cut. The membrane is attachable to the cut end surface of the tree trunk and includes a hydrating layer comprising a hydrogel. The hydrogel, made up primarily of water, adheres to the cut end surface of the tree trunk to continue hydrating the tree, and prevents air from reaching the tree&#39;s exposed transport tissue. In some embodiments, the membrane includes a backing layer and a release layer on opposite sides of the hydrating layer.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to preserving and maintaining trees, and more specifically to an apparatus and method for preserving the fresh cut characteristics of a tree base. 
       BACKGROUND OF THE INVENTION 
       [0002]    Trees absorb water through their roots and pass the water up the tree via transport tissue. In particular, xylem tissue, which forms part of the tree&#39;s trunk and may include tracheids, vessels, parenchyma cells, and woody fibers, transports water up the trunk and throughout the tree. 
         [0003]    When a tree is cut down, the xylem tissues tend to close up rapidly. The tree compartmentalizes and forms a seal on the cut surface after exposure to air. This creates a problem, particularly with Christmas trees, when any measurable time passes between cutting and placing the tree in a stand with water. By the time the cut tree is exposed to water again, its ability to draw up the water is limited or entirely prevented. 
         [0004]    The solution to this problem has historically been to make a fresh cut on the tree immediately before putting it into the tree stand. However, many consumers do not want to go through the trouble of re-cutting the tree and may not have the tools to do so. Thus, the lifespan of Christmas trees is often limited when a second cut is not done. 
       SUMMARY OF THE INVENTION 
       [0005]    An object of the present invention is to provide an improved solution to the problem of tree trunks sealing up after cutting that does not require re-cutting the tree base. A further object is to provide such a solution that also maintains hydration in the tree during and after transport, and also in the tree stand. 
         [0006]    These and other objects are achieved by providing a membrane attachable to a cut end surface of a tree trunk. The membrane includes a hydrated layer (e.g., hydrogel) with a high water content. The hydrogel layer preferably has adhesive qualities to attach to the cut end surface. However, in some embodiments, the membrane may include an adhesive layer adjacent to the hydrogel layer to aid in attachment to the tree. The membrane may also include a backing layer and a removable release layer on opposite sides of the hydrated layer. 
         [0007]    The hydrogel layer has 80% or more water content, and preferably 90% or more water content. In an even more preferred embodiment the hydrogel layer has 95% or more water content. The hydrogel may be electron beam cured and/or radiation cured. 
         [0008]    Further provided is a method of preserving a cut tree including the steps of cutting a tree down via a trunk of the tree, installing (e.g., immediately or soon thereafter) a membrane according to the present invention to a cut end of the trunk, inserting the tree into a tree stand, and filling the stand with water. In some embodiments, the tree is inserted into the stand with the membrane and a backing layer. In some embodiments, the method includes the step of removing the backing layer to allow water to more easily pass to the hydrating layer and/or removing the membrane. In some embodiments, the membrane is circular having a distal edge about a circumference of the membrane, wherein the step of installing the membrane includes adhering a central portion of the membrane to the cut end of trunk and adhering the distal edge to sides of the trunk. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIGS. 1A-1B  illustrate a membrane according to an exemplary embodiment of the present invention. 
           [0010]      FIG. 2  is a side view of a tree including a membrane according to an exemplary embodiment of the present invention. 
           [0011]      FIG. 3  is a bottom view of the tree shown in  FIG. 2 . 
           [0012]      FIG. 4  illustrates a membrane according to an exemplary embodiment of the present invention on a tree. 
           [0013]      FIG. 5  is a side view of a tree including a membrane according to an exemplary embodiment of the present invention mounted in a tree stand. 
           [0014]      FIG. 6  illustrates a membrane according to an exemplary embodiment of the present invention within sealed packaging. 
           [0015]      FIG. 7  illustrates a membrane according to an exemplary embodiment of the present invention within unsealed packaging. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0016]      FIGS. 1A-1B  illustrate a membrane  10  according to an exemplary embodiment of the present invention.  FIG. 1A  is an exploded view showing the various layers of the membrane  10 . In the exemplary embodiment, each of the layers are circular. 
         [0017]    The membrane  10  may include a backing layer  12 . The backing layer  12  may, for example, be made of a poly material such as a polyethylene film (e.g., a 9.8 Mil matte polyethylene acetate film). In one embodiment, the backing layer  12  is Mylar. The backing layer  12  may be impermeable to air and/or permeable to water. In some embodiments, the backing layer  12  (and/or the release layer  16 ) includes a tab  18  to facilitate removal. In some embodiments, no backing layer  12  is used. 
         [0018]    The membrane  10  further includes a hydrated layer  14 . In the exemplary embodiment, the hydrated layer  14  is a hydrogel which absorbs water. In some embodiments, the hydrated layer  14  has a thickness of at least 20 Mil or at least 30 Mil, such as 32 Mil. The hydrated layer  14  includes a water content of at least 80% and preferably 90% or more (e.g., 94%). 
         [0019]    In one embodiment, the hydrated layer  104  is formed from a hydrogel including polyethylene oxide (e.g., a 4% polyethylene oxide hydrogel) that is mixed as a liquid slurry, extruded to create a sheet, and then cross-linked to at least partially solidify the sheet using electron beam curing. In some embodiments, the hydrated layer  14  is a radiation cured hydrogel. Embodiments with at least 90% or more of water content, such as hydrogels created by electron beam curing, were found to last up to 72 hours or more and sufficiently prevent sealing of tree. Hydrated layers  14  with less than 80% or even less than 90% may not diffuse water into the tree at a fast enough rate and/or in a sufficient amount. 
         [0020]    In some embodiments, the hydrated layer  14  has sufficient cross-linking to avoid the hydrogel from being absorbed and/or passed into the tree during use. This is advantageous because applicant has discovered that absorbing hydrogel into the tree trunk can act to seal the tree trunk and/or reduce the amount of water absorption. A woven material may also be used as the foundation to the hydrogel layer, to help resist tearing. 
         [0021]    The membrane  10  further includes a release layer  16  that is adjacent to the hydrated layer  14  before use and removed immediately prior to use. The release layer  16  may be, for example, a Mylar liner or any other suitable material to releasably attach to the hydrated layer  14  such as a 3 Mil thick Mylar liner. The hydrogel has adhesive qualities which provide enough stickiness to hold the membrane  10  to the cut portion of the tree trunk and/or the adjacent bark. In some embodiments, the hydrated layer  14  may have an additional adhesive layer or adhesive application provided to aid in attaching the membrane  10  to a tree trunk. 
         [0022]      FIGS. 2-3  illustrate a tree  20  with a membrane  10  attached thereto. The tree  20  (e.g., a Christmas tree) is first cut down at tree farm or other location. A user then removes the release layer  16  and applies the membrane  10  by sticking the membrane  10  to the base of the tree trunk. The membrane  10  generally covers the entirety of the cut surface of the tree  20 . 
         [0023]    The membrane  10  may also be wrapped around and onto the sides of the trunk as shown in  FIG. 4 . This may aid in securing the membrane  10  to the tree  20 , and also ensure that the entirety of the cut surface is covered. Thus, the diameter of the membrane  10  may be equal to the diameter of the tree trunk, or greater (e.g., 1-3 inches greater than an average Christmas tree trunk) as shown in  FIG. 4 . For example, the membrane  10  may be offered in one or more standard sizes, such as a 6-inch diameter membrane and/or a 10-inch diameter membrane. Applying the membrane  10  prevents the tree base from naturally forming a seal (either a full seal preventing water uptake or a partial reducing water uptake) during transport. 
         [0024]      FIG. 5  shows the tree  20  mounted in a tree stand  30  with water  32 . When the tree  20  is placed in the tree stand  30 , the membrane  10  may be removed. Having been treated with the membrane  10  during transport, a seal does not form and the tree  20  is able to take up water which it would not have been able to fully do had the tree  20  formed a seal. 
         [0025]    In some embodiments, the membrane  10  can also remain on the tree  20 . This eliminates the need for the user to remove the membrane  10 . Also, the membrane  10  may continuously retain a deposit of water as a reserve in the event that the tree stand  30  dries out. Depending on the permeability of the backing layer  12  material, water may pass through the backing layer  10  or around the edges of the backing layer  12  to the membrane  10 . In some embodiments, the backing layer  12  is eliminated to allow water  32  to more easily diffuse through the hydrated layer  14 . 
         [0026]    In embodiments of the membrane  10  employing a release layer  16 , the user removes the release layer  16  to expose the hydrating layer  14  and applies the hydrating layer  14  directly to the cut surface of the tree trunk  22 . The hydrogel of the hydrating layer  14  may provide sufficient adhesiveness to adhere to the tree trunk  22 . Alternatively, the hydrating layer  14  may include an additional adhesive or an adhesive layer. In some embodiments, the hydrating layer  14  is impermeable to air. The backing layer  12  may be impermeable to air and/or permeable to water. In some embodiments, the backing layer  12  is impermeable to both air and water. 
         [0027]    In embodiments, the hydrating layer  14  and backing layer  12  can be left on the tree trunk  22  when it is placed in the tree stand  30  and water  32  is added. The hydrating layer  14  continues to provide water to the tree trunk  22  while absorbing and diffusing more water from the water  32 . This allows the user the convenience of not having to remove the membrane  10  before installing the tree  20  into the stand  30 . In embodiments where neither the hydrating layer  14  nor the backing layer  12  are permeable to water, both should be removed before installing the tree  20  into the stand  30 . In embodiments where only the hydrating layer  14  is permeable to water and the backing layer  12  is impermeable to water, the backing layer  12  should be removed before installing the tree  20  into the stand  30 . In some embodiments, tab  18  is provided to assist removing the backing layer  12 . 
         [0028]    A preferable embodiment of the membrane  10  employs a release layer  16 , an air and water permeable hydrating layer  14 , and an air and water impermeable backing layer  12 . To use this embodiment, the user removes the release layer  16 , preferably using a tab  18 , and applies the hydrating layer  14  to the cut end of the trunk  22  of the tree  20 , preferably immediately or shortly after the tree  20  was cut down. The user can then transport the tree  20  to the location he or she wishes to display it, and the air impermeable backing layer  12  prevents air from reaching the cut end of the tree trunk  22 . Once the tree  20  arrives at the desired location, the user can remove the backing layer  12 , preferably using a tab  18 , and place the tree  20  in the stand  30  leaving the water permeable hydrating layer  14  on the cut end of the tree trunk  22 . The user can then fill the tree stand  30  with water  32  and the tree  20  will be able to draw the water  32  into the tree trunk  22  through the water permeable hydrating layer  14 . 
         [0029]    The membrane  10  according to the present invention advantageously both reduces or blocks exposure of the cut portion of the tree trunk to the air and continuously hydrates the tree. Experiments have shown that only keeping air out is not sufficient. 
         [0030]    A Christmas tree that receives a second cut immediately prior to being put in a tree stand typically takes up at least five gallons of water in two to three weeks. Without a second cut, the water take up is often significantly less. Embodiments of the present invention were tested on Christmas trees that were allowed to sit for at least two days after being cut and before being placed in water. Trees on which the membrane were applied were able to achieve similar results to a tree that had received a second cut. 
         [0031]      FIGS. 6 and 7  illustrate an advantageous embodiment of packaging  40  for the membrane  10 . The packaging  40  preferably forms an airtight seal around the membrane  10  to keep the membrane  10  from drying out. In some embodiments, the packaging  40  employs slots or notches  42  to facilitate tearing and removal of the packaging top  44  to access the membrane  10 . In such embodiments, the user can remove the packaging top  44  using one or more slots  42  and remove the membrane  10  from the packaging  40  through an opening created by removal of the packaging top  44 . 
         [0032]    In some preferable embodiments, as illustrated in  FIG. 7 , the packaging may employ a separable first section  46  and second section  48  to help facilitate removal of the membrane  10 . The user can peel the first section  46  away from the second section  48  after removal of the packaging top  44  using the one or more slots  42 , leaving the membrane  10  laying upon the second section  48 . The user can then simply pick up the membrane  10  and employ it on a tree  20  as desired. 
         [0033]    Although the invention has been described with reference to a particular arrangement of parts, features and the like, these are not intended to exhaust all possible arrangements or features, and indeed many modifications and variations will be ascertainable to those of skill in the art.