Abstract:
There is provided a sealable enclosure having a surface having a cyanoacrylate disposed thereupon, another surface having disposed thereupon an activator compound capable of inducing polymerization of the cyanoacrylate, the two surfaces being positioned or positionable in opposing relationship to one another. Other embodiments are also disclosed.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Ser. No. 62/044,996, filed Sep. 2, 2014 and entitled “SECURITY ENVELOPE AND METHOD”. The contents of said application are incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    Security envelopes, such as polyolefin security envelopes such as polyethylene (PE) or polypropylene (PP) security envelopes are known in the art. A typical example of a PE security envelope is shown in  FIGS. 1-3 . Envelope  10  is formed from a single sheet of polyethylene (PE)  12 , which has been folded over itself to provide bottom edge  14  and top edge  16 , and sealed at side edges  18  and  20 , for example by heat sealing. Back side  22  of envelope  10  is thus a continuous portion of sheet  12 . Front side  24  of envelope  10  is formed from portion  26  of sheet  12  which extends from bottom edge  14  toward top edge  16  to terminal edge  28 , and from portion  30 , also referred to as flap  30 , that extends from top edge  16  toward edge  14  and slightly beyond terminal edge  28 , where flap  30  terminates at terminal edge  32 , which is located between portion  26  and the inner surface of back side  22 . Thus slit  34  is formed in front side  24 . Optionally, the interior of envelope  10  may be lined with a material other than polyethylene. 
         [0003]    A ribbon  36  is affixed along portion  38  thereof to portion  26  of sheet  12  near terminal edge  28 , for example by a pressure sensitive adhesive (PSA) that adheres to polyethylene with sufficient strength that once attached to portion  26 , ribbon  36  cannot be removed without tearing or otherwise perceptibly deforming envelope  10 ; in  FIG. 2 , portion  38  is shown by hatching running to the left from bottom to top. Ribbon  36 , which is made of, for example, PE, polypropylene (PP), bioriented polypropylene (BOPP), bioriented polyethylene terephthalate (BOPET), combinations thereof and/or a laminate made from them, co-extruded polyethylene/polyacrylate (PE/PA), and the like, covers the entire width of envelope  10 , and is itself of sufficient width that it extends across slit  34 . The portion  40  of ribbon  36  facing flap  30  is also provided with a PSA (which may the same or different as the PSA used to attach portion  38  to portion  26  when a PSA is used for such purpose), but this PSA on portion  40  is covered by ribbon  42  which is also formed of, for example, PE, polypropylene (PP), bioriented polypropylene (BOPP), bioriented polyethylene terephthalate (BOPET), combinations thereof, co-extruded PE/PE, and the like, but which has a release coating to facilitate easy removal from the PSAS on portion  40  of ribbon  36 , and thus protects the PSA from moisture and/or oxygen and is only removed immediately prior to use. In  FIG. 2 , the area of overlap between ribbons  36  and  42  is shown by cross-hatching, and the part of ribbon  42  that does not overlap with ribbon  36  is shown by hatching running to the right from bottom to top. Once ribbon  42  is removed from ribbon  36  to reveal the PSA, portion  40  is pressed onto flap  30  so as to seal envelope  10 . Ribbon  36  is provided with a plurality of perforations  44  running across the length of ribbon  36 . The adhesive forces between ribbon  36  and envelope  10  are such that an attempt to remove ribbon  36  will result in tearing across at least a portion of the perforation, thus indicating that an attempt has been made to tamper with the envelope. 
       BRIEF DESCRIPTION OF EMBODIMENTS OF THE INVENTION 
       [0004]    There is provided, in accordance with an embodiment of the invention, a sealable enclosure having an opening defined therein, the sealable enclosure having
       (1) adjacent to a first side of said opening a first surface, said first surface having disposed thereon one of (a) a cyanoacrylate of the formula CH 2 ═C(CN)—COOR where R is alkyl and (b) an activator compound capable of inducing polymerization of said cyanoacrylate;   (2) adjacent to a second side of said opening a second surface, said second surface being positioned or positionable in opposing relationship to said first surface whereby, when said second surface is sealed to said first surface, said opening is substantially closed, said second surface having disposed thereupon either (i) an activator compound capable of inducing polymerization of said cyanoacrylate, if said cyanoacrylate is disposed on said first surface or (ii) a cyanoacrylate of the formula CH 2 ═C(CN)—COOR where R is alkyl, if said activator compound is disposed on said first surface,   wherein each of said first surface and said second surface is independently selected from the group consisting of polyolefin (PO), co-extruded polyolefin/ethylene acrylic acid copolymer (PO/EAA), plasma-treated PO, plasma-treated PO/EAA, and plasma-treated ethylene-vinylacetate (EVA).       
 
         [0008]    In some embodiments, the sealable enclosure is an envelope. In some embodiments, the PO is selected from polyethylene (PE) and polypropylene. In some embodiments, the PO/EAA is PE/EAA. In some embodiments, at least one of said first surface and said second surface is plasma-treated PO or plasma-treated PO/EAA. In some embodiments, the plasma-treated PO or PO/EAA is selected from the group consisting of plasma-treated PE, plasma-treated PP, and plasma-treated PE/EAA. In some embodiments, R is C 1-6  alkyl. In some embodiments, R is methyl. In some embodiments, R is ethyl. In some embodiments, the activator compound is an amine. In some embodiments, the amine is selected from the group consisting of triethylenetetramine, tetraethylenepentamine, diethylaminopropylamine, N-aminoethylpiperazine, m-xylylenediamine, m-phenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, isophoronediamine, 2,4,6-tris (dimethylaminomethyl) phenol, p-toluidine, N,N-diethylaniline, and 2,6-di-tert-butyl-4-methyl aniline, and mixtures thereof. In some embodiments, the amine is a derivative of aniline or a mixture of such derivatives. In some embodiments, the amine is selected from the group consisting of p-toluidine, N,N-diethylaniline, and 2,6-di-tert-butyl-4-methyl aniline, and mixtures thereof. In some embodiments, the activator compound is present in a concentration of 10 −9  mole/cm 2  to 10 −7  mole/cm 2 . In some embodiments, at least the surface upon which said cyanoacrylate is disposed is a plasma-treated surface. In some embodiments, the surface upon which the activator compound is disposed is a plasma-treated surface. In some embodiments, a first acid is mixed in said cyanoacrylate. In some embodiments, the first acid is present in a concentration of 50-100,000 ppm. In some embodiments, the first acid is present in a concentration of not more than 90,000 ppm, not more than 80,000 ppm, not more than 70,000 ppm, not more than 60,000 ppm, not more than 50,000 ppm, not more than 40,000 ppm, not more than 30,000 ppm, not more than 20,000 ppm, not more than 10,000 ppm, not more than 5,000 ppm, not more than 1,000 ppm, not more than 500 ppm, or not more than 100 ppm. In some embodiments, a second acid is mixed in said activator. In some embodiments, the second acid is present in a concentration of 50-100,000 ppm. In some embodiments, the second acid is present in a concentration of not more than 90,000 ppm, not more than 80,000 ppm, not more than 70,000 ppm, not more than 60,000 ppm, not more than 50,000 ppm, not more than 40,000 ppm, not more than 30,000 ppm, not more than 20,000 ppm, not more than 10,000 ppm, not more than 5,000 ppm, not more than 1,000 ppm, not more than 500 ppm, or not more than 100 ppm. In some embodiments, the second acid is the same as said first acid. In some embodiments, the surface upon which said cyanoacrylate is disposed is a polymeric surface which contains acid moieties. In some embodiments, the surface upon which said activator is disposed is a polymeric surface which contains acid moieties. In some embodiments, the acid moieties are carboxylic acid moieties. In some embodiments, the carboxylic acid moieties are present as part of coextruded PO/EAA. In some embodiments, the coextruded PO/EAA is coextruded PE/EAA, which optionally has been plasma treated. In some embodiments, the carboxylic acid moieties are present in a concentration of from 0.5 to 9 mol % of the EAA in the coextruded PO/EAA. In some embodiments, the second surface is a ribbon which is affixed to a second side of said opening and extends across said opening. In some embodiments, the ribbon is made of polyethylene PE, polypropylene (PP), bioriented polypropylene (BOPP), bioriented polyethylene terephthalate (BOPET), combinations thereof and/or a laminate made from them, or co-extruded PE/EAA copolymer. In some embodiments, the ribbon has been affixed to said second side of said opening by heat sealing. In some embodiments, the ribbon is affixed to said second side of said opening by a pressure-sensitive adhesive. In some embodiments, the cyanocacrylate is enclosed in a space formed by said first or second surface and a piece of material which is removably attached to said first or second surface. In some embodiments, the piece of material is formed from PE or co-extruded PE/EAA. In some embodiments, the space is formed by said second surface and said piece of material. In some embodiments, the piece of material is attached to said first or second surface so as to form a plurality of discrete spaces, at least two of which enclose cyanoacrylate therein. In some embodiments, the piece of material is removably attached to said first or second surface by heat sealing. In some embodiments, the piece of material is removably attached to said first or second surface by a PSA. In some embodiments, the piece of material is removably attached to said first or second surface by a combination of heat sealing and PSA. 
         [0009]    There is also provided, in accordance with an embodiment of the invention, a method for preparing an enclosure having an opening defined therein for sealing, comprising: 
         [0000]    (1) forming a cyanoacrylate-bearing first surface adjacent to a first side of said opening, the cyanoacrylate having the formula CH 2 ═C(CN)—COOR where R is alkyl; and
 
(2) forming an activator-bearing second surface adjacent to a second side of said opening, which second surface is positioned or positionable in opposing relationship to said first surface whereby, when said second surface is sealed to said first surface, said opening is substantially closed, said activator being a compound capable of inducing polymerization of said cyanoacrylate,
 
wherein each of said first surface and said second surface is independently selected from the group consisting of polyolefin (PO), co-extruded polyolefin/ethylene acrylic acid copolymer (PO/EAA), plasma-treated PO, plasma-treated PO/EAA, and plasma-treated ethylene-vinylacetate (EVA).
 
         [0010]    There is also provided, in accordance with an embodiment of the invention, a method for preparing an enclosure having an opening defined therein for sealing, comprising: 
         [0000]    (1) forming an activator-bearing first surface adjacent to a first side of said opening, the activator being a compound capable of inducing polymerization in a cyanoacrylate of the formula CH 2 ═C(CN)—COOR where R is alkyl; and
 
(2) forming a cyanoacrylate-bearing second surface adjacent to a second side of said opening, which second surface is positioned or positionable in opposing relationship to said first surface whereby, when said second surface is sealed to said first surface, said opening is substantially closed, said cyanoacrylate being of the formula CH 2 ═C(CN)—COOR where R is alkyl,
 
wherein each of said first surface and said second surface is independently selected from the group consisting of polyolefin (PO), co-extruded polyolefin/ethylene acrylic acid copolymer (PO/EAA), plasma-treated PO, plasma-treated PO/EAA, and plasma-treated ethylene-vinylacetate (EVA).
 
         [0011]    There is also provided, in accordance with an embodiment of the invention, a method for preparing an enclosure having an opening defined therein for sealing, the enclosure having either
       (i) a cyanoacrylate-bearing first surface adjacent to a first side of said opening, the cyanoacrylate having the formula CH 2 ═C(CN)—COOR where R is alkyl, or   (ii); an activator-bearing first surface adjacent to a first side of said opening, the activator being a compound capable of inducing polymerization in a cyanoacrylate of the formula CH 2 ═C(CN)—COOR where R is alkyl;   the method comprising:   (a) if the enclosure has a cyanoacrylate-bearing first surface, forming an activator-bearing second surface adjacent to a second side of said opening, which second surface is positioned or positionable in opposing relationship to said first surface whereby, when said second surface is sealed to said first surface, said opening is substantially closed, said activator being a compound capable of inducing polymerization of said cyanoacrylate, or   (b) if the enclosure has an activator-bearing first surface, forming a cyanoacrylate-bearing second surface adjacent to a second side of said opening, which second surface is positioned or positionable in opposing relationship to said first surface whereby, when said second surface is sealed to said first surface, said opening is substantially closed, said cyanoacrylate being of the formula CH 2 ═C(CN)—COOR where R is alkyl;
 
wherein each of said first surface and said second surface is independently selected from the group consisting of polyolefin (PO), co-extruded polyolefin/ethylene acrylic acid copolymer (PO/EAA), plasma-treated PO, plasma-treated PO/EAA, and plasma-treated ethylene-vinylacetate (EVA).
       
 
         [0017]    There is also provided, in accordance with an embodiment of the invention, a method for preparing an enclosure having an opening defined therein for sealing, the enclosure having either
       (a) an activator-bearing second surface adjacent to a second side of said opening, which second surface is positioned or positionable in opposing relationship to a first surface adjacent to a first side of said opening whereby, when said second surface is sealed to said first surface, said opening is substantially closed, said activator being a compound capable of inducing polymerization of a cyanoacrylate of the formula CH 2 ═C(CN)—COOR where R is alkyl, or   (b) a cyanoacrylate-bearing second surface adjacent to a second side of said opening, which second surface is positioned or positionable in opposing relationship to said first surface adjacent to a first side of said opening whereby, when said second surface is sealed to said first surface, said opening is substantially closed, said cyanoacrylate being of the formula CH 2 ═C(CN)—COOR where R is alkyl;   the method comprising:   (i) if the enclosure has an activator-bearing second surface, forming a cyanoacrylate-bearing first surface adjacent to a first side of said opening, the cyanoacrylate having the formula CH 2 ═C(CN)—COOR where R is alkyl, or   (ii); if the enclosure has a cyanoacrylate-bearing second surface, forming an activator-bearing first surface adjacent to a first side of said opening, the activator being a compound capable of inducing polymerization in a cyanoacrylate of the formula CH 2 ═C(CN)—COOR where R is alkyl;
 
wherein each of said first surface and said second surface is independently selected from the group consisting of polyolefin (PO), co-extruded polyolefin/ethylene acrylic acid copolymer (PO/EAA), plasma-treated PO, plasma-treated PO/EAA, and plasma-treated ethylene-vinylacetate (EVA).
       
 
         [0023]    There is also provided, in accordance with an embodiment of the invention, a method of sealing an enclosure having an opening defined therein, the enclosure having
       (1) adjacent to a first side of said opening a first surface, said first surface having disposed thereon one of (a) a cyanoacrylate of the formula CH 2 ═C(CN)—COOR where R is alkyl and (b) an activator compound capable of inducing polymerization of said cyanoacrylate;   (2) adjacent to a second side of said opening a second surface, said second surface being positioned or positionable in opposing relationship to said first surface whereby, when said second surface is sealed to said first surface, said opening is substantially closed, said second surface having disposed thereupon either (i) an activator compound capable of inducing polymerization of said cyanoacrylate, if said cyanoacrylate is disposed on said first surface or (ii) a cyanoacrylate of the formula CH 2 ═C(CN)—COOR where R is alkyl, if said activator compound is disposed on said first surface,
 
wherein each of said first surface and said second surface is independently selected from the group consisting of polyolefin (PO), co-extruded polyolefin/ethylene acrylic acid copolymer (PO/EAA), plasma-treated PO, plasma-treated PO/EAA, and plasma-treated ethylene-vinylacetate (EVA),
 
the method comprising bringing said cyanoacrylate and said activator into contact with each other while each is disposed on its respective surface.
       
 
         [0026]    In some embodiments, in any of the above-described methods, said enclosure is an envelope. In some embodiments, the PO is selected from polyethylene (PE) and polypropylene. In some embodiments, the PO/EAA is PE/EAA. In some embodiments, at least one of said first surface and said second surface is plasma-treated PO or plasma-treated PO/EAA. In some embodiments, the plasma-treated PO or PO/EAA is selected from the group consisting of plasma-treated PE, plasma-treated PP, and plasma-treated PE/EAA. In some embodiments, R is C 1-6  alkyl. In some embodiments, R is methyl. In some embodiments, R is ethyl. In some embodiments, the activator compound is an amine. In some embodiments, the amine is selected from the group consisting of triethylenetetramine, tetraethylenepentamine, diethylaminopropylamine, N-aminoethylpiperazine, m-xylylenediamine, m-phenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, isophoronediamine, 2,4,6-tris (dimethylaminomethyl) phenol, p-toluidine, N,N-diethylaniline, and 2,6-di-tert-butyl-4-methyl aniline, and mixtures thereof. In some embodiments, the amine is a derivative of aniline or a mixture of such derivatives. In some embodiments, the amine is selected from the group consisting of p-toluidine, N,N-diethylaniline, and 2,6-di-tert-butyl-4-methyl aniline, and mixtures thereof. In some embodiments, the activator compound is present in a concentration of 10 −9  mole/cm 2  to 10 −7  mole/cm 2 . In some embodiments, at least the surface upon which said cyanoacrylate is disposed is a plasma-treated surface. In some embodiments, the surface upon which said activator compound is disposed is a plasma-treated surface. In some embodiments, a first acid is mixed in said cyanoacrylate. In some embodiments, the first acid is present in a concentration of 50-100,000 ppm. In some embodiments, the first acid is present in a concentration of not more than 90,000 ppm, not more than 80,000 ppm, not more than 70,000 ppm, not more than 60,000 ppm, not more than 50,000 ppm, not more than 40,000 ppm, not more than 30,000 ppm, not more than 20,000 ppm, not more than 10,000 ppm, not more than 5,000 ppm, not more than 1,000 ppm, not more than 500 ppm, or not more than 100 ppm. In some embodiments, a second acid is mixed in said activator. In some embodiments, the second acid is present in a concentration of 50-100,000 ppm. In some embodiments, the second acid is present in a concentration of not more than 90,000 ppm, not more than 80,000 ppm, not more than 70,000 ppm, not more than 60,000 ppm, not more than 50,000 ppm, not more than 40,000 ppm, not more than 30,000 ppm, not more than 20,000 ppm, not more than 10,000 ppm, not more than 5,000 ppm, not more than 1,000 ppm, not more than 500 ppm, or not more than 100 ppm. In some embodiments, the second acid is the same as said first acid. In some embodiments, the surface upon which said cyanoacrylate is disposed is a polymeric surface which contains acid moieties. In some embodiments, the surface upon which said activator is disposed is a polymeric surface which contains acid moieties. In some embodiments, the acid moieties are carboxylic acid moieties. In some embodiments, the carboxylic acid moieties are present as part of coextruded PO/EAA. In some embodiments, the coextruded PO/EAA is coextruded PE/EAA, which optionally has been plasma treated. In some embodiments, the carboxylic acid moieties are present in a concentration of from 0.5 to 9 mol % of the EAA in the coextruded PO/EAA. In some embodiments, the second surface is a ribbon which is affixed to a second side of said opening and extends across said opening. In some embodiments, the ribbon is made of polyethylene PE, polypropylene (PP), bioriented polypropylene (BOPP), bioriented polyethylene terephthalate (BOPET), combinations thereof and/or a laminate made from them, or co-extruded PE/EAA copolymer. In some embodiments, the ribbon has been affixed to said second side of said opening by heat sealing. In some embodiments, the ribbon is affixed to said second side of said opening by a pressure-sensitive adhesive. In some embodiments, the cyanocacrylate is enclosed in a space formed by said first or second surface and a piece of material which is removably attached to said first or second surface. In some embodiments, the piece of material is formed from PE or co-extruded PE/EAA. In some embodiments, the space is formed by said second surface and said piece of material. In some embodiments, the piece of material is attached to said first or second surface so as to form a plurality of discrete spaces, at least two of which enclose cyanoacrylate therein. In some embodiments, the piece of material is removably attached to said first or second surface by heat sealing. In some embodiments, the piece of material is removably attached to said first or second surface by a PSA. In some embodiments, the piece of material is removably attached to said first or second surface by a combination of heat sealing and PSA. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]    Embodiments of the invention will be better understood through the following description and with reference to the drawings, in which: 
           [0028]      FIGS. 1-3  show an embodiment of a prior art polyethyelene security envelope; 
           [0029]      FIGS. 4A and 4B  show an embodiment of a polyethyelene security envelope in accordance with an embodiment of the invention; 
           [0030]      FIGS. 5A and 5B  show one way of sealing cyanoacrylate between two ribbons in accordance with an embodiment of the invention; 
           [0031]      FIGS. 6A and 6B  show another way of sealing cyanoacrylate between two ribbons in accordance with an embodiment of the invention; 
       
    
    
     DETAILED DESCRIPTION 
       [0032]      FIGS. 4A and 4B  show an embodiment of the presently claimed invention, as used in the case of a PE envelope like that shown in  FIG. 1 . Polyethylene envelope  110  is similar to envelope  10 , being formed from a single sheet of polyethylene (PE)  112 , which has been folded over itself to provide bottom edge  114  and top edge  116 , and sealed on side edges  118  and  120 , for example by heat sealing. Back side  122  of envelope  110  is thus a continuous portion of sheet  112 . Front side  124  of envelope  110  is formed from portion  126  of sheet  112  which extends from bottom edge  114  toward top edge  116  to terminal edge  128 , and from portion  130 , also referred to as flap  130 , that extends from top edge  116  toward edge  114  and slightly beyond terminal edge  128 , where flap  130  terminates at terminal edge  132 , which is located between portion  126  and the inner surface of back side  122 . Thus slit  134  is formed in front side  124 . 
         [0033]    As in  FIGS. 1-3 , a ribbon  136  (an example of which is shown in  FIGS. 5A and 5B ) is affixed along portion  138  of sheet  112  to portion  126  of sheet  112  near terminal edge  128 , for example by a pressure sensitive adhesive (PSA); in  FIG. 4B , portion  138  is shown by hatching running to the left from bottom to top. Ribbon  136 , which is made of PE or co-extruded PE/ethylene acrylic acid or the like, covers the entire width of envelope  110 , and is itself of sufficient width that it extends across slit  134 . However, the manner of sealing portion  140  of ribbon  136  facing flap  130  to flap  130  is different than the manner of sealing portion  40  of ribbon  36  to flap  30 . Disposed on portion  140  is a layer of cyanoacrylate (CA) monomer  150  of formula NC—C(═CH 2 )—COOR, where R is alkyl, e.g. a C 1-6  alkyl, for example methyl or ethyl. Monomer  150  is separated from the environment by a ribbon  142  or other means, as will be explained in greater detail below; like ribbon  136 , ribbon  142  may be made of PE or co-extruded PE/ethylene acrylic acid or the like. In  FIG. 4B , the area of overlap between ribbons  136  and  142  are depicted by cross-hatching. The layer of cyanoacrylate monomer may be of a thickness of 0.1 micron to 100 microns, e.g. 1 micron to 30 microns. In some embodiments, as will be explained below, the CA monomer may be present as a plurality of spaced-apart units, such as dots; in other embodiments, the CA monomer may be present as an essentially continuous body. 
         [0034]    Disposed on the part of flap  130  facing portion  140  is an activator compound  152  (represented in  FIG. 4A  by stippling) which will activate polymerization of the cyanoacrylate when brought into contact therewith. Whether the activator compound is anionic or neutral, it should be a nucleophile for the methylene carbon of the CA monomer, i.e. it should be able to readily provide an electron pair to form a bond at the methylene carbon of the CA monomer. See the figure below, which illustrates the process schematically for an anion and a neutral species: 
         [0000]    
       
                 
         
             
             
         
       
     
         [0035]    Preferably the activator is an amine such as for example triethylenetetramine, tetraethylenepentamine, diethylaminopropylamine, N-aminoethylpiperazine, m-xylylenediamine, m-phenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, isophoronediamine, and 2,4,6-tris (dimethylaminomethyl) phenol. Derivatives of aniline, such as p-toluidine, N,N-diethylaniline, and 2,6-di-tert-butyl-4-methyl aniline, and mixtures thereof, such as a 50:50 molar mixture of p-toluidine and N,N-diethyl aniline, have been found to be particularly useful. The activator may be applied to the surface of flap  130  by, for example, spraying or printing. Application by spraying may be achieved by dissolving the activator compound in a low boiling point solvent and spraying as necessary. For example, toluidine may be dissolved in hexane, acetone, or an appropriate fluorocarbon such as 1,2-difluoropropane. The presence of the activator on the envelope  10  may be detected for example using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) or Raman spectroscopy, which can be used online during production of a plurality of envelopes as part of a quality control procedure. 
         [0036]    Immediately prior to use, the cyanoacrylate is exposed by removal of ribbon  142 , and then the CA is brought into contact with the activator. At temperatures in the range of 18-30° C., this results in mixing of CA and activator and resultant polymerization of the CA, creating a strong bond between portion  140  of ribbon  136  and flap  130 , within a relatively short period of time, for example not more than ten minutes, not more than nine minutes, not more than eight minutes, not more than five minutes, not more than four minutes, not more than three minutes, not more than two minutes or not more than one minute from the time at which at the CA and activator are mixed. In some cases the polymerization and formation of the bond takes at least 15 second, at least 30 seconds, at least 45 second or at least 60 seconds. 
         [0037]    Cyanoacrylate has a higher surface energy than polyethylene. Thus, when ribbon  136  is made of PE, it desirable to increase the surface energy of the face of ribbon  136  on which the CA is present prior to placing the cyanoacrylate on that face, in order to improve the adhesion of the cyanoacrylate to the ribbon  136 . This may be achieved, for example, via plasma treatment, e.g. Corona treatment, in order to form oxidized groups on the PE surface, thus increasing its surface energy. Alternatively, if the ribbon  136  is made of co-extruded polyethylene/ethylene acrylic acid copolymer (PE/EAA), the cyanoacrylate will be attracted to the EAA. An additional advantage of using co-extruded PE and EAA is described below. Co-extruded PE/EAA may also itself be plasma treated to increase the concentration of acidic groups presented. In another variation, ethylene-vinyl acetate (EVA, the copolymer of ethylene and vinyl acetate) may be used, provided that it is plasma treated to facilitate adhesion of the CA to the EVA. 
         [0038]    It will be often be desirable to include an acid with the cyanoacrylate in order to stabilize this material, for example in a concentration of 50-100,000 ppm. Such acids may be Lewis acids or Bronsted acids. Examples of suitable acids are acetic acid, zinc chloride, citric acid, tartaric acid, phosphoric acid and mixtures thereof. In the case in which the CA is placed on co-extruded PE/EAA, the acrylic acid moieties may also act as a stabilizer for the CA. It will also be appreciated that if the surface on which the activator is present contains acrylic acid groups, e.g. co-extruded PE/EAA, the carboxylic acid groups may form salts with the activator, thus stabilizing it as well. 
         [0039]    Commercially available cyanoacrylates typically have a gel-like consistency at room temperature, due to the inclusion of one or more thickening agents in the mixture. Thus,  FIGS. 5A and 5B  show one way of enclosing the cyanoacrylate: the CA is deposited on part of ribbon  136 , and is enclosed between ribbon  136  and ribbon  142  by sealing of ribbon  142  to ribbon  136  along length-wise edges  136 A and  136 B as well as along width-wise edges  136 C and  136 D, in a manner that protects the CA from the outside (e.g. keeps out moisture) but facilitates removal of ribbon  142  when desired, for example by pulling on tab  142 A. As shown in  FIGS. 5A and 5B , portion  138  of ribbon  136 , which as shown in  FIG. 4B  is used to affix ribbon  136  to the envelope, is not covered by ribbon  142 , although it will be appreciated that other arrangements are possible. 
         [0040]    In an alternative embodiment, shown in  FIGS. 6A and 6B , a plurality of drops of CA  250  are disposed on ribbon  236  in a defined pattern, such as alternating rows, and ribbon  242  is releasably sealed thereover in a manner that entraps each drop between ribbons  236  and  242 , for example using a PSA along the lines denoted  260 A and  260 B, or by creating a heat seal along lines  260 A and  260 B which can be broken by pulling on ribbon  242 . Optionally, a releaseable seal may also be formed between ribbons  236  and  242  along edges  236 A,  236 B,  236 C and  236 D, for examples by use of a PSA or by heat sealing. Ribbon  242  is removed to expose the CA so that the CA may be brought into contact with the activator. It will be appreciated that although CA drops  250  are located between ribbons  236  and  242  and therefore their exact location is not necessarily visible to a person viewing these ribbons, for the sake of illustration in  FIGS. 6A and 6B  these drop are shown both when ribbon  242  is sealed to ribbon  236  and when ribbon  242  is partially removed from ribbon  236 . 
         [0041]    It will be appreciated that envelopes such as envelope  110  may be manufactured in a continuous process, as is well-known in the art. In such a case, depending on the manufacturing process used, it may be desired to for a ribbon such as ribbon  136  or  236  to be made in a continuous process that is conducted in tandem with the formation of envelope  110 , so that ribbon  136  or  236  is attached to envelope  110  as envelope  110  is formed; or alternatively it may be desired to utilize pre-formed ribbons  136  or  236 , either pre-cut or on a roll ready for synchronous cutting with the formation of the envelope  110 . Likewise, if for some reason it is desired to first form a plurality of envelopes  110  and afterward attach the CA-bearing ribbons thereto, ribbon  136  or  236  may likewise be pre-formed, either pre-cut or on roll ready for cutting as each envelope  110  has a ribbon  136  of  236  attached thereto; or ribbon  136  or  236  may be formed in a continuous process and attached to the envelope as ribbon  136  or  236  is formed. Furthermore, in some embodiments, it may prove most cost-efficient to utilize a third ribbon (not shown_, to attach ribbon  136  or  236  to the envelope; this third ribbon may be e.g. a polyolefin ribbon such as PE or PP having a PSA disposed on both sides, so that this third ribbon (which would then effectively act as a piece of double-sided tape) is attached directly to the envelope and ribbon  136  or  236  is attached to the third ribbon. 
         [0042]    It will be appreciated that in some embodiments, a ribbon  136  or  236  need not be employed. Instead, the portions of envelope  10  to which the CA and activator are to be applied may be plasma treated and then the CA and activator directly applied thereto, with the CA being sealed in place by a removable ribbon  342  (not shown). Alternatively, a co-extruded layer of PE/EAA, or EVA (which is then plasma treated), may be applied to sheet  112  at the location where it is desired to dispose the CA and optionally at the location where it is desired to dispose the activator; such a co-extruded layer may be of for example 1-100 micrometers thickness, e.g. 3-100 micrometers thickness. 
         [0043]    It will also be appreciated that although in the figures, the activator is shown as being located on flap  130  near slit  134  of envelope  110  and the CA on the ribbon  136  or on the interior of portion  124  of envelope  110  near slit  134 , in principle the positions of the activator and CA may be reversed. Similarly, instead of being located near one end of the envelope, slit  134  could be located elsewhere, for example closer to the middle of the envelope, or the slit could be located at an edge so that the envelope could simply have a flap that folds over the slit. The envelope could also be formed without a flap but with opposed surfaces on which the CA and activator are disposed. In addition, while the drawings shown herein depict a substantially flat envelope, the envelope could instead be of a different shape. 
         [0044]    The seal formed by the polymerization of the CA is such that if an attempt is made to break the seal, this will be evident to an observer, as the area of the envelope around the seal will be deformed or torn. Furthermore, it will be appreciated that by manufacture of the area around the seal with a material having, for example, a softening temperature lower than the softening temperature of the polymerized CA (or of a PSA seal, if one more PSAs are used to hold ribbons on which the CA and/or activator are disposed), or if the material has a significant lower viscosity than the polymer CA or PSA at this temperature, then the opening of a polymerized CA or PSA seal by heat will not be possible without detection, since this will result in deformation of the envelope in at least the vicinity of envelope adjacent to the polymerized CA or PSA seal. 
         [0045]    While the discussion above focused on a PE envelope, in principle a different polyolefin, such as PP, could be used. Moreover, although envelope  110  is shown as a single piece of material, this need not necessarily be the case. For example, the envelope could be made from different materials, e.g. the front portion could be made from a polyolefin such as PE or PP, but the back portion could be made from a different polyolefin, or the back could be made from a mesh material, such as a non-woven or woven mesh. Part of the envelope may be opaque in the visible light spectrum, and part of the envelope may be transparent in the visible light spectrum. It will also be appreciated that the envelope may be made primarily from a material other than polyolefin, provided that the portions of the envelope (or the ribbons) on which the CA and the activator are disposed are themselves polyolefins, co-extruded PO/EAA, or EVA, appropriately treated, if necessary (for example by plasma treatment) to ensure sufficient adhesion between the CA- and activator-bearing portions when these portions are brought into mutual contact. In another variation, the envelope, or parts of it, may be made from a heat-sealable laminate, which has an outer layer of polyolefin, co-extruded polyolefin/EAA, such as co-extruded PE/EAA, or EVA, plasma treated as necessary. Such a laminate may include in its inner layers other polymers or materials, such as polymers which alone may be unsuitable as a material on which to place the CA monomer or the activator, for example because of high hygroscopicity, but which can be used in embodiments of the present invention by virtue of the presence of a polyolefin or co-extruded polyolefin/EAA, or plasma-treated EVA, interposed between the layer of unsuitable polymer(s) and the CA monomer or activator. 
       Example 1 
       [0046]    The bonding of a cyanoacrylate-based adhesive (polymerized NC—C(═CH 2 )—COOR, wherein R is ethyl to an activated PE surface was compared to the bonding of two “fast-curing” adhesives, an acrylic-based “No Mix” adhesive from Henkel (Loctite 330, which according to its Material Safety Data Sheet contains primarily tetrahydrofurfuryl methacrylate (30-60 wt. %), as well as 5-10 wt. % methacrylic acid, 5-10 wt. % unspecified alkyl methacrylate, 1-5 wt. % unspecified epoxy resin, 1-5 wt. % unspecified methacrylate monomer, 0.1-1 wt. % talc, 0.1-1 wt. % cumene hydroperoxide, and 0.1-1 wt. % 1,1,2-trichloroethane) and an epoxy adhesive from Huntsman (Bostic Araldite Rapid Resin, containing primarily bisphenol A-epichlorohydrin epoxy resin (60-100 wt. % and butanedioldiglycidyl ether (5-10 wt. %). In each case, two strips of PE were coated with EEA copolymer and the resulting product was plasma-treated. The adhesive was then applied to one strip and the activator or hardener (if required) applied to the other strip, and the two strips were brought together and pressed together for a few seconds using manual pressure. Bond strength was tested by seeing how easily, if at all, the two strips could be manually separated. The results are presented in Table 1 below. 
         [0000]    
       
         
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
               
               
                   
                 Activator/ 
                 Bond strength 
               
             
          
           
               
                 Adhesive 
                 Hardener 
                 after 5 min 
                 after 30 min  
                 after 5h 
                 after 24h 
               
               
                   
               
               
                 Modified 
                 MOBIZ-1 
                 No peeling 
                 No peeling 
                 No peeling 
                 No Peeling 
               
               
                 Cyanoacrylate 
                 Amine Type 
                   
                   
                   
                   
               
               
                 Adhesive 
                 Activator* 
                   
                   
                   
                   
               
               
                 Loctite 330 
                 Loctite 7387 
                 Very easy 
                 Easy peeling  
                 Can be 
                 Can be 
               
               
                 Acrylic No- 
                 Activator 
                 peeling 
                   
                 peeled out by  
                 peeled out by 
               
               
                 Mix Adhesive 
                   
                   
                   
                 hands 
                 hands 
               
               
                 Araldite 
                 Araldite 
                 Very easy 
                 Very easy 
                 Easy peeling 
                 No peeling 
               
               
                 Rapid Epoxy 
                 Rapid, Fast 
                 peeling 
                 peeling 
                   
                   
               
               
                 Adhesive 
                 Setting 
                   
                   
                   
                   
               
               
                   
                 hardener 
               
               
                   
               
               
                 *4-N,N-trimethyl aniline, 2% in hexane 
               
             
          
         
       
     
         [0047]    Although the foregoing invention has been described in some detail for purposes of illustration, it will be readily apparent to one skilled in the art that changes and modifications may be made without departing from the scope of the invention described herein.