|Title of Invention||
WATER CONTACT INDICATOR
|Abstract||The present invention discloses an adhesive article. The adhesive article comprises a first layer comprising a fluid transport substrate, comprising a low molecular weight hydrophilic polymer resin, the first layer having a first major surface and a second major surface. The adhesive article additionally comprises a second layer comprising a fluid transportable ink, the second layer being associated with the second major surface of the second layer. The adhesive article also comprises an adhesive layer.|
WATER CONTACT INDICATOR
Field of the Invention
The present invention relates to adhesive articles having the capability to detect fluid, especially water, exposure.
Background of the Invention
An adhesive article, for example a tape or a label that indicates fluid exposure is desirable for many uses. For example, such an adhesive article may help detect minor leaks in water tight pipes. Additionally, these adhesive articles may be useful for detecting water exposure of electronics, especially hand-held electronics. For example, an adhesive article that indicates water exposure would be useful for manufacturers of electronic devices, for example cellular phones, personal digital assistants, hand held computers, battery chargers, or small electric appliances, to help determine functional failure. The adhesive article may be placed on the electronic device, either within the electronic portion of the device or on an external casing. If the device had been immersed or a sensitive component contacted with a fluid, such as water, the warranty could be voided or the cause of failure determined.
Some adhesive articles used for fluid indication describe a layer of ink on a substrate. The ink is displayed in a pattern that is altered upon exposure to water. For example, the ink may be in stripes or dots, which blur upon exposure to water. Some additional adhesive articles have a transparent cover film to prevent smudging of the ink prior to water exposure. Other adhesive articles utilize an ink that changes color upon the exposure to water.
Summary of the Invention
Some commercially available adhesive articles indicate too easily under high humidity conditions. Some additional commercially available adhesive articles may not indicate water contact at all after exposure to high humidity conditions. What is desired is a water indicating adhesive article that will indicate upon sustained water exposure, but does not indicate in a high humidity environment
Another embodiment of the invention is illustrated in Figure 2. Figure 2 is the same embodiment as shown in Figure 1 with the exception that the transparent layer 26 has been removed.
The fluid indicating adhesive article of the present invention includes a substrate capable of fluid transport ("fluid transport substrate".) A fluid transport substrate will transport fluid through the substrate. For example, the substrate may comprise a microporous film as described in U.S. Patent No. 5,238,623 to Mrozinski. Generally, the fluid transport substrate comprises a porous layer. In many embodiments, the fluid transport substrate comprises a fibrous substrate. The fibrous substrate is generally capable of absorbing a fluid. However, the fibrous substrate generally will not saturate in a high humidity environment. In certain embodiments, the substrate is a water absorbent substrate. The water absorbent substrate is generally made of a material that maintains a cohesive form when wet. Suitable substrates include paper, such as cellulose based paper, for example paper towels and copy grade paper.
Additionally, woven and nonwoven fabrics and polyolefms may be suitable substrates. Polyolefins may be treated to enhance fluid absorbance, for example by treating with a hydrophilic coating or blending the polyoleftn with a hydrophilic fiber. However, any coating used to make the polyolefin hydrophilic should be chosen so it will not interfere with, or react negatively to the adhesive chosen. Melt-blown or spunbond techniques can be employed to make such nonwoven webs. Nonwoven webs can also be prepared, for example, on a RANDO WEBBER (Rando Corporation, Macedon, NY) air-laying machine or on a carding machine.
Representative examples polyolefins include, for example, polypropylene, polyethylene, high density polyethylene, low density polyethylene, linear low density polyethylene, and linear ultra low density polyethylene, and polybutylenes. Additional materials that may be useful for the substrate of the present invention include nylon, polyester (e.g., polyethylene terephthalate), vinyl copolymers, such as polyvinyl chlorides, both plasticized and unplasticized, and polyvinyl acetates; olefinic copolymers, such as ethylene/methacrylate copolymers, ethylene/vinyl acetate copolymers, acrylonitrile-butadiene-styrene copolymers, and ethylene/propylene copolymers; acrylic polymers and
Optionally, various fillers or additives may be incorporated into the substrate to control or contribute to the overall color and/or opacity of substrate. Such fillers or additives may include clay, talc, diatomaceous earth, calcium carbonate, calcium sulfate, barium sulfate, iron oxide, titanium oxide, zinc oxide, zinc sulfide, aluminum silicate, organic pigments or a mixture thereof.
Fluid Transportable Ink
Fluid transportable ink is coated onto one surface of the fluid transport substrate to form an ink layer. In embodiments comprising a hydrophilic resin layer, the ink may be coated on the hydrophilic resin layer as depicted in the figures. Ink is defined as a dispersion of a pigment or a dye solution produced as a fluid, paste or a powder. Upon exposure to a fluid, the fluid transportable ink is mobilized and flows with the fluid through the substrate. In some embodiments, a hole in the substrate exposes the ink and assists in the displacement of the ink in the event of fluid exposure.
For example, a water soluble ink is suitable for the present invention. In specific embodiments, the ink may be HP Ink Jet cartridge 51649a printed blue ink, commercially available from Hewlett Packard Co., Boise, Idaho. Other examples include blue dye-powder sold under the tradename HE)ACID AZURE Blue dustless 20DA2228 commercially available from B.F. Goodrich, Cincinnati, Ohio and red dyes sold under the tradenames FASTUSOL Red 43LN and BASACED RED NB 391L, both commercially available from BASF Corp. of Mount Olive, New Jersey.
The ink may be dispersed on the substrate. In other embodiments, the ink is dispersed on the adhesive layer, which is then brought into contact with the substrate. The ink may be dispersed using various coating and printing techniques chosen to be suitable for a particular ink. For example, the ink may be dispersed using an ink jet printer, gravure printing, flexographic printing, letter press printing or powder coating techniques. The ink may be dispersed on the substrate in a variety of coverage, for example a predetermined pattern, a random pattern, or complete coverage.
An adhesive layer is applied, for example coated or laminated, onto the surface of the ink layer. The adhesive may be any adhesive, for example a thermally bondable (hot-
pyrrolidone, (meth)acrylamide, a vinyl ester, a fumarate, a styrene macromer, or combinations thereof. Generally, the poly(meth)acrylic pressure sensitive adhesive is derived from between about 0 and about 20 weight percent of acrylic acid and between about 100 and about SO weight percent of at least one of isooctyl acrylate, 2-ethyl-hexyl acrylate or n-butyl acrylate composition, preferably isooctyl acrylate. A suitable embodiment for the present invention is derived from between about 2 and about 10 weight percent acrylic acid and between about 90 and about 98 weight percent of at least one of isooctyl acrylate, 2-ethyl-hexyl acrylate or n-butyl acrylate composition.
The adhesive layer is applied onto the ink layer using any suitable coating or laminating technique. For example, the adhesive layer may be formed by continuous forming methods, including hot melt coating, drawing or extruding, the adhesive composition from the elongating shear force device (e.g. a draw die, a film die, or a rotary rod die) and subsequently contacting the drawn adhesive composition to a moving web (e.g. plastic) or other suitable substrate. A related continuous forming method involves extruding the adhesive composition and a co-extruded backing material from a film die and cooling the layered product to form an adhesive tape. Other continuous forming methods involve directly contacting the adhesive composition to a rapidly moving web or other suitable preformed substrate. Using this method, the adhesive composition is applied to the moving preformed web using a die having flexible die lips, such as a rotary rod die. The adhesive layer may additionally be formed by any non-continuous coating method.
Alternatively, the adhesive may be prepared by dissolving the components of the adhesive composition in a solvent such as toluene and casting over the substrate.
The water indicating adhesive article of the present invention optionally has a transparent layer comprising a transparent film on the fluid transporting substrate. The transparent layer is on the substrate surface opposite the ink layer. The transparent layer may extend beyond the edge of the substrate, or maybe the same size as the substrate. Generally such a layer may be waterproof. Such a layer protects the water indicating adhesive article from moisture during human handling and from dew/condensation. Additionally, the additional layer may protect the water indicating adhesive article during
comprise a release liner, such as silicone coated paper or film, adhered to the adhesive until the tape is ready to be adhered to a surface.
If the tape is sold in a roll, it may be beneficial to add a release material (e.g., low adhesion backsize) to the side of the tape opposite the adhesive.
Method of Manufacture
The water indicating adhesive article of the present invention is manufactured generally by coating a fluid transport substrate, either single or multilayer as described, with a fluid transportable ink. In certain embodiments, the fluid transport substrate comprises a porous substrate and a hydrophilic resin layer. The hydrophilic resin layer may be coated on the porous substrate. In some embodiments, the hydrophilic resin layer comprises an additive (e.g. titanium dioxide). Other additional layers may also be coated to form the fluid transport substrate. The substrate may be in the form of a sheet, or may be a long strip suitable for rolling the final product into a roll of tape. The ink may be coated to completely cover the substrate, or may be coated in segments or a design. The ink must be coated so that the ink does not bleed through the substrate. For example, the ink may be coated onto a release liner, and then transferred to the substrate.
Adhesive is then applied to the ink as described above. The substrate and the ink may then be completely coated with the adhesive, or may be coated with segments of adhesive. Such a segmented adhesive may be desirable in embodiments where the substrate may have a coating that may be affected by the adhesive. The adhesive is then covered with a release liner if desired.
In other embodiments, the adhesive can be made into a transfer tape by coating the adhesive composition, either completely or in segments, on a liner, or between two liners, coated with a release coating. If the transfer tape is made by coating between two liners, one of the liners of the transfer tape can be removed to expose the adhesive surface. The adhesive surface may then be applied to the ink layer, or the adhesive surface may be coated with the fluid transportable ink and then laminated to the substrate. The remaining release liner aids in transferring the adhesive to the substrate.
Individual labels may be created by converting the sheets into individual labels, for example by die cutting the sheet. The sheet may be die cut into any size or shape, such as circles or squares. For example, the sheet may be die cut into a circle with a diameter
Additional water dispersible solutions (coatings) were formulated for the preparation of Examples 5-11.
Examples 5-11 were prepared using Coatings #5 - #11, respectively, coated onto separate pieces of Absorbent Substrate C in the same manner, and equipment as Examples 1-4. Red Dye and Transfer adhesive were also applied to the coated side of Examples #5 - #11 in the same manner as Examples 1-4. A Transparent Protective Film was not laminated to the non-coated/dyed side of the Substrate C. Several small circles with a diameter of 14 mm were die cut from the prepared sheets of Examples 5-11 and applied to a polyester holding sheet for indicator testing.
Examples 5-11 were exposed to temperature and humidity conditions of 55°C/95% RH for 7 days. This exposure testing was performed to determine if the samples indicated a false positive for water contact under such extreme conditions of temperature and humidity.
laminated to the coated/dyed side of each sheet of Examples 12-15. To the non-coated/dyed side of the Absorbent Substrate B? of Examples 14 and 15 was laminated a Transparent Protective Film. Several small circles with a diameter of 14 mm were die cut from the prepared sheets of Examples 12-15 and applied to a polyester holding sheet for indicator testing. Examples 12-15 were exposed to temperature and humidity conditions of 55°C/95% RH for 7 days. Like Examples 5-11, none of the Examples 12-15 indicated false positives for water contact exposure. Although, all of the Examples 12-15 did show a very slight color indication, but not enough to be considered exposed to water contact. Additionally, after prolonged temperature and humidity exposure, Examples 12-15 were subjected to the "One Minute Water Contact Test." All samples gave a positive water contact indication except Example 13. See Figure 3 for the appearance of Examples 12 and 13 under various pre-test and post-test conditions.
Examples 16-24 were prepared as described for Examples 1-4 with the following modifications. Coating solutions 16-24, shown in TABLE 7, were prepared and applied to Absorbent Substrate C. Results of the "One Minute Water Contact Test" for Examples 16-24 are provided in TABLE 8.
Various modifications and alterations that do not depart from the scope and spirit of this invention will become apparent to those skilled in the art. This invention is not to be unduly limited to the illustrative embodiments set forth herein.
What is Claimed is:
1. An adhesive article comprising
a first layer comprising a fluid transport substrate, the fluid transport substrate comprising a low molecular weight hydrophiliqpolymer resin, the first layer having a first major surface and a second major surface;
a second layer comprising a fluid transportable ink, the second layer being associated with the second major surface of the first layer; and
an adhesive layer.
2. The adhesive article of claim 1 wherein the fluid transport substrate is a multilayer
3^ The adhesive article of claim 1 wherein the low molccuLu weight liydiupliiliu
polymer resin is a hydrophilic vinyl pol)rmer resin.
J X. The hydrophilic vinyl polymerresiiK>f claim,? wherein the hydrophilic vinyl polymer resin comprises polyvinyl pyrrolidone.
V $. The adhesive article of claim 1 wherein the low molecular weight hydrophilic polymer resin has a molecular weight of less than 10,000.
ST &. The adhesive article of claim 1 wherein the fluid transport substrate further comprises an opacity enhancing additive.
£ t. The adhesive article of claim ^wherein the opacity enhancing additive comprises titanium dioxide.
?*^. The adhesive article of claim & wherein the low molecular weight hydrophilic
polymer resin further comprises an opacity enhancing additive.
fSf. The adhesive article of claim 1 comprising a transparent layer on the first major surface of the fluid transport layer, low molecular weight hydrophilic polymer resin
) PQ. The adhesive article of claim 1 wherein the fluid transport substrate comprises a porous layer.
0 X. The adhesive article of claim £Q wherein the porous layer is a fibrous layer.
1 ^. The adhesive article of claim 1 wherein the fluid transport substrate is water
Z &£• The adhesive article of claim 1 wherein the fluid transport substrate is a cellulose-based paper.
*3 l1^. The adhesive article of claim 1 wherein the adhesive layer is associated with the second layer.
V 3^- The adhesive article of claim 1 wherein the fluid transportable ink comprises a water soluble ink.
C t&. The adhesive article of claim 1 comprising a fluid transport substrate between the second layer and the adhesive layer.
?* )#. A method of indicating fluid contact, comprising providing the adhesive article comprising
a first layer comprising a fluid transport substrate, the fluid transport substrate comprising a low molecular weight hydrophilic polymer resin, the first layer having a first major surface and a second major surface;
a second layer comprising a fluid transportable ink, the second layer being associated with the second major surface of the second layer; and
an adhesive layer; and exposing the adhesive article to a liquid;
wherein the fluid transportable ink migrates through the fluid transport substrate to cause a substantial color change.
n The method of claim wherein the adhesive article is exposed to a vapor of the liquid prior to exposure to the liquid.
T . The method of claim lS wherein the ink migrates through the fluid transport substrate after exposing the adhesive article to the liquid.
|Indian Patent Application Number||1653/CHENP/2006|
|PG Journal Number||03/2012|
|Date of Filing||12-May-2006|
|Name of Patentee||3M INNOVATIVE PROPERTIES COMPANY|
|Applicant Address||3M Center, Post Office Box 33427, Saint Paul, Minnesota 55133-3427|
|PCT International Classification Number||C09J7/02,G01N31/22,G09F3/02,3/10|
|PCT International Application Number||PCT/US2004/037909|
|PCT International Filing date||2004-11-11|