Patent Application
20160063900
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
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
There is provided, in accordance with an embodiment of the invention, a sealable enclosure having an opening defined therein, the sealable enclosure having
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 C1-6 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/cm2 to 10−7 mole/cm2. 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.
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:
(1) forming a cyanoacrylate-bearing first surface adjacent to a first side of said opening, the cyanoacrylate having the formula CH2═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).
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:
(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 CH2═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 CH2═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).
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
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
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
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 C1-6 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/cm2 to 10−7 mole/cm2. 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.
Embodiments of the invention will be better understood through the following description and with reference to the drawings, in which:
As in
Disposed on the part of flap 130 facing portion 140 is an activator compound 152 (represented in
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.
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.
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.
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.
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,
In an alternative embodiment, shown in
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.
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.
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.
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.
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.
The bonding of a cyanoacrylate-based adhesive (polymerized NC—C(═CH2)—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.
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.
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.
| Number | Date | Country | |
|---|---|---|---|
| 62044996 | Sep 2014 | US |
