US 3675015 A
A system for detecting the location and uniformity of a coating on a substrate is provided. The process comprises the steps of adding a fluorescent dye material to the coating material, coating the substrate with the fluorescent dye-containing coating material, and viewing the pattern obtained thereby under an ultraviolet light source. A gable-top container employing a non-heat sealing coating containing a fluorescent dye on a portion thereof is described. The fluorescent dye is used to aid in evaluating the location and uniformity of the coating.
Claims available in
Description (OCR text may contain errors)
I United States Patent n51 3,675,015
Geib July 4, 1972 [54) ABHESIVE PATTERN DETECTOR 3,341,705 9/]967 Alburgerm; ..250 7| T SYSTEM 3,510,653 5/1970 Holbrook..... ....250 s3.3 uv 2,63l,243 3/1953 Weber et al.. ..250/7] lnvemofl Thomas Ge"), Flonssam, 3,334,799 8/1967 Crawford ..229/17 0 7. W h C T W h. I a] Afslgnee eyer user ompany acoma as Primary Examiner-Archie R. Borchelt  Flledi Sept- 2, 1969 Att0meyChristensen & Sanborn  Appl. No.: 854,440  ABSTRACT  U 8 Cl 250/71R 229/3 1 229/17 G A system for detecting the location and uniformity of a coat- 250/71 i ing on a substrate is provided. The process comprises the steps  Int Cl G01 21/16 of adding a fluorescent dye material to the coating material,  Field 229/3 1 coating the substrate with the fluorescent dye-containing coat- 6 ing material, and viewing the pattern obtained thereby under an ultraviolet light source. A gable-top container employing a non-heat sealing coating containing a fluorescent dye on a  References Cited portion thereof is described. The fluorescent dye is used to aid UNITED STATES PATENTS in evaluating the location and uniformity of the coating.
3,] 18,060 H1964 Klein ..250/7l T 4 Claims, 2 Drawing Figures PATENTEDJuL 4 m2 INVENTOR. 77/0/ 145 5. 6. 75
Anne/Vim ABI-IESIVE PATTERN DETECTOR SYSTEM BACKGROUND OF THE INVENTION This invention relates to a process or system for determining the location and uniformity of a coating placed on a substrate. This invention further relates to a process of evaluating a coating by incorporating a fluorescent material in said coating and visually observing the location and uniformity of the coating under an ultraviolet light source. One particular embodiment of this invention provides a system for determining the location and consistency of an abhesive coating placed over a portion of the surface of a gable-topped container. The abhesive is necessary to facilitate opening the pouring spout of the carton but yet obtain an adequate seal to prevent loss of the material in the container before opening.
In the art of construction and use of gable-top type con tainers, such as are widely used in dairy and fruit juice industries, it is well known to utilize an abhesive material to facilitate in opening the top and exposing the pouring spout for dispensing of the contents. Such a container is thoroughly and carefully described in U.S. Pat. No. 3,116,002 to D. 1. Crawford et al., U.S. Pat. No. 3,270,940 to H. B. Egleston et al., and U.S. Pat. No. 3,334,799 to D. J. Crawford, and the disclosures of those patents are included herein by reference to define the state of the art. Abhesive materials are defined therein as an anti-adhesive or non-heat sealing material.
Use of the technology known to the prior art has resulted in containers which are easily opened by the consumer, but yet maintain a fluid-tight seal during shipping and handling. However, positioning of the abhesive material in proper registry with the carton blank has been a problem since very accurate positioning is required to obtain the desired amount of sealing effect in the gable top. The prior art methods of determining the location and uniformity of the abhesive coating have not found particular success, since they are destructive testing techniques and take a considerable length of time to perform. The best known method of evaluating the coating of abhesive is to remove from the production line representative carton blanks coated with a polymer such as polyethylene over their entire surface and then coated in the desired locations with an abhesive such as a silicone. The area of abhesive application is smeared with a dye or ink substance which stains or is retained upon the surface of the polymer coating to a different degree than on the surface of the abhesive coating. The pattern which then develops indicates the location of the abhesive material and the uniformity of the abhesive coating. This method is, of course, very time consuming and wasteful since with today's modern processing techniques many cartons would have produced with faulty abhesive coatings thereon in the time that it takes to perform this testing procedure.
It is an object of this invention to provide a rapid, nondestructive testing technique for evaluating the location and uniformity of an abhesive coating on a substrate. It is a further object of this invention to provide a method of evaluating the location and uniformity of a normally transparent coating on a substrate by incorporating a fluorescent material in the coating formulation prior to placing the coating formulation upon the substrate and viewing the coated object under ultraviolet light.
FIGURES FIG. 1 shows a perspective view of a dispensing container having a pouring spout to which the present invention has been applied.
FIG. 2 shows a fragmentary portion of the inside surface of a flat blank of the material from which the container shown in FIG. 1 can be erected.
DESCRIPTION OF THE PREFERRED EMBODIMENT A representation of one form of the applicants preferred embodiment of this invention is shown in FIGS. 1 and 2. In FIG. I, a tubular container 7 is shown surmounted by the usual gable top I. The pouring spout 6 shown in FIG. I is folded out in position to dispense the contents of the container 7. FIG. 2 shows a portion of the paperboard blank from which the carton shown in FIG. 1 is erected. The entire surface of both sides of the blank has been coated with a thermoplastic resin such as polyethylene or the like which acts to prevent liquid penetration of the carton and when heated, pressed together and cooled, serves as the adhesive sealant to keep the container bottom and gable top closed after filling. To assist in opening the gable top, an abhesive material 3 is coated on a carefully controlled area of the pouring spout portion of gable top 1. This abhesive coating must be properly located on each blank in exact registry with the pouring spout 6 to facilitate opening of the gable top when it is desired to dispense the contents and yet permit an adequate heat seal to be achieved. The abhesive material 3 must be positioned on the carton blank so that the seal areas 4 can provide a liquid seal along the ridge 2 of the gable top 1 but yet permit easy opening of the pour spout 6 with little damage to the pouring edge 5. By combining a fluorescent dye with the abhesive coating material prior to application to the blanks, a nondestructive evaluation of the coating uniformity and location can be obtained by exposing the abhesive coated surface to ultraviolet light. Any fluorescent compound may be employed which is compatible with the particular coating material being used. Particularly useful fluorescent dyes include the organic substances capable of fluorescing and emitting visible light when exposed to radiations having wavelengths between 2,500 Angstroms and 4,500 Angstroms and preferably in the range of 3,600 to 3,800 Angstroms. Some of the typical fluorescent organic substances which are suitable for use in, for example, polymer-containing coating formulations include the following:
Meta diethylaminophenol phthalein hydrochloride Meta diethylaminophenol succin hydrochloride Meta aminophenol phthalein hydrochloride The ethyl ester of meta monobutylaminophenol phthalein Meta aminophenol phthalein hydrochloride Di (para dimethylaminophenyl) ketone hydrochloride 2, 3 diphenyl N-phenyl quinox-alonium sulphate p,p' di[paminobenzoyl-amino) benzoylamino] stilbene 0,0 di[sodium sulphonate] Meta mono-ethylaminophenol phthalein Meta monoethylaminophenol phthalein hydrochloride Diamino stilbene-di-sulphonic acid (Sodium salt) 2, amino, 9(4' aminophenyl) acridonium nitrate 4, amino 1,8 naphthal p-xenyl-imide 2,[4' amino 8' carboxynaphthyl (1')] benzimidazole sodium sulfonate Di(dimethylaminophenyl) phenylamino naphthyl methane chloride 4 methyl, 7 hydroxy coumarin sodium salt Many of the organic fluorescent materials which may be used in the practice of this invention are sold commercially in various forms under trademarks such as Calcofluor (American Cyanamide Company, Wayne, N.J.), Zyglo (by the Zyglo Company) or Uvitex WNA (CIBA Chemical and Dye Co., Fairlawn, N.J.). The abhesive materials utilized in the preferred embodiment may be any material which imparts a nonstick characteristic to the surface of the container being sealed at the desired locations and which prevents fusion of the thermoplastic polymer coating on the surface of the carton when heated. Suitable materials for this purpose include, among others, high molecular weight polysiloxane gum such as dimethyl siloxane polymers of the general formula (Cl-I S 0 Such siloxane gums typically have a molecular weight exceeding 150,000, and capable of being cured or crosslinked. Such organo siloxane gums are marketed by various manufacturers including, for instance, the Silicone Products Division of the General Electric Company. Other abhesive materials such as lacquer-type may be used.
The amount of fluorescent material added to the abhesive or other coating material is, of course, not critical for purposes imine ethylester of detecting the location and uniformity of the coating. It is necessary only to add enough fluorescent material to permit an observer to see the coating material containing the fluorescent dye when viewed under ultraviolet light. Typically, the dye concentration varies from 1 part per million up to approximately 1 percent by weight of the coating material. Lower amounts are, of course, preferred to minimize cost of the abhesive coating.
EXAMPLE An abhesive coating material containing fluorescent dye was formulated as follows: 0.04 parts of American Cyanamids Calcofluor White RWP Concentrate was added to 100 parts of General Electric abhesive SS-4076 and thoroughly mixed therein. The above abhesive formulation was coated upon standard polyethylene coated paperboard milk cartons in the manner taught in the above-cited patents to Crawford and Egleston. When viewed under ultraviolet light, the pattern and location of the abhesive was clearly apparent. In this manner the registry, location, shape and uniformity of the abhesive coating may be quickly and effortlessly determined for purposes of making a correction, with little or no waste of the finished carton products.
This process may, of course, be automated by providing suitable light-activated apparatus designed to evaluate the fluorescent dye-containing coating. For example, a photocell placed above a set of opaque patterns having an outline of the desired shape of the abhesive coating could readily evaluate the presence and possible the extent of abhesive coating outside that area covered by the opaque patterns. A photocell having a small area scanning apparatus would indicate areas which have no fluorescence indicating lack of presence of the coating material.
Many other modifications of and applications for the process will occur to one skilled in the art. These modifications might include for example the use of the fluorescent dye in a clear adhesive material when it is desired to accurately pattern the adhesive material on a substrate.
1. In the manufacture of paperboard containers from an elongated array of successive blanks of flat foldable paperboard material having a thermoplastic resin coating thereon, by the steps of applying an applicator to localized resin coated surfaces of the blanks which are inwardly spaced from edges of the blanks, and overlaying a coating of abhesive material on each of the surfaces with the applicator, and thereafter folding each blank into the configuration of a container, and hot pressing together other resin coated surfaces of each such folded blank to effect a plastic-to-plastic bond between the latter resin coated surfaces in each container, while the aforesaid localized resin coated surfaces of the blanks resist adhesion in the containers due to the abhesive overlays thereon, the improvement wherein the abhesive material has an agent incorporated therein which emits fluorescent light under the influence of ultraviolet light, and the presence of the abhesive material outside the aforesaid localized resin coated surfaces of the blanks, is determined byirradiating a selected blank with ultraviolet light between the aforesaid abhesive applying and folding steps, and monitoring the blank for the emission of fluorescent light from the spaces between the aforesaid localized resin coated surfaces and edges, and the applicator and the blanks successive to the selected blank in the array, are positioned in relation to one another so that the overlays are offset from the edges at a distance or distances prescribed for the same.
2. The process according to claim 1 wherein gable top liquid containers are fabricated from the blanks, and the abhesive overlays are inwardly spaced from pouring edges of the pouring spouts of the same, as well as from fold lines of the spouts transverse said pouring edges.
3. The process according to claim 1 wherein the agent is an organic dye which emits visible li ht under the influence of ultraviolet ight irradiated at wave engths between 2,500 angstroms and 4,500 angstroms.
4. The process according to claim 1 wherein the blanks have a polyethylene resin coating on both sides thereof.