Business record having a multicolor imagable surface

0001This invention relates to a business record, such as a form, label, tag, or the like, in which different selected areas may be activated thermally More particularly, the invention relates to a sheet containing on its surface coatings of selected initially colorless color formers and color developers which, when subjected to heat, combine to form different colored areas on the sheet.

0002In the design and use of business forms, labels, tags, and the like, it is desirable to present information in an organized fashion so that information may be readily assimilated. For example, forms typically use headings or columns to identify different categories of information. Lines, rules, and screened areas are also used to delineate specific areas of information.

0003Color has also been used on business forms to delineate or differentiate information. For example, multipart forms, with each part being printed on different colored paper, have been in use for many years. The different color of each part of the form designates to whom that part is to be given or sent. Others have used different colored forms, labels, or tags to designate, for example, different methods of shipment of packages. As with multi-part forms, however, this method of designation requires that the user maintain an inventory of each different colored form, label, or tag.

0004To better differentiate categories of information, preprinted screened background areas are often printed in selected colors. One known method used for producing different colors is to apply colored inks during the printing process when the forms are being manufactured. However, such a process requires a separate printing station for each color of ink used. In addition, if the techniques of process color are used, different shades or hues of color can only be produced by printing two or more colors in a superimposed relationship onto selected areas of the form.

0005EP-A-343780 teaches a carbonless copy system and a method of producing multiple coloured copy images. The system includes a recording substrate (copy) and a transfer substrate (original), between which are sandwiched two or three image-forming components. The image-forming components may contain different colourless dye precursors encapsulated in microcapsules, such that impact on the transfer substrate will rupture the capsules to leave a coloured mark on the recording substrate. The image-forming components are arranged in a manner so that impact in one area will rupture the microcapsules in one component and provide a record in one colour, whereas impact in another area will release a second colour. A third colour may be obtained where the two components overlap so that impact causes the microcapsules to rupture in both component layers and the colours to mix.

0006In the field of product labelling, direct thermal printing has been a well-known means of non-impact printing. Direct thermal printers are capable of forming colored images by the application of heat to a substrate containing heat-reactive chemicals thereon. Typically, a substrate such as paper is coated with a coating of color forming and color developing reactants which, when heated, combine to form a visible color. When such a coated substrate passes under the print head of a thermal printer, selected areas containing the coating are activated by the heated print elements, forming colored images on the surface of the substrate. US-A-4,577,205 describes a releasable heat-sensitive label which can be printed upon using electron beam setting printing ink disposed in a pre-selected pattern such that exposure to an electron beam source sets the ink. Secondary (background) printing is carried out using a thermal head printer which activates a thermosensitive color forming layer (which includes leuco dye), provided on top of the substrate layer, to create a background pattern. The document also discloses covering the thermosensitive color-forming layer with a protective layer, and backing the substrate with adhesive.

0007Thermally imagable coatings provide a convenient method of providing computer generated data such as bar codes or serial numbers. Such information may be printed on business forms such as labels or tags. Thermally coated substrates have also been widely used as facsimile paper, bar code paper for point-of-sale (POS) systems, automatic ticket vending machines, and labels for food products. There are various compositions and methods of applying thermally sensitive coatings as described, for example, in U.S Patent Nos. 4,865,939, 4,861,749, and 4,894,359.

0008Another method of printing colored images is by applying heat at different temperatures or by applying different quantities of thermal energy to a coated substrate. For example, U.S. Patent No. 4,665,410 to Iiyama et al teach a multi-color thermosensitive recording material formed by applying three or more successively overlaid thermosensitive coloring layers to a support material with intervening decolorizing agent containing layers. Each coloring layer yields a different color depending on the quantity of thermal energy applied. However, such coatings must be applied separately. Also, it is believed that separate printing passes are needed to activate selected colors.

0009It is also possible to achieve colored images from the use of self-contained carbonless coatings which produce colored images upon the application of pressure such as that from an impact printer. Such coatings are well known, and typically contain dispersed color developers and initially colorless leuco dyes contained in solution within microcapsules. EP-A-297705 describes a laminate construction where the color-producing layer is sandwiched between two facing layers. Application of an imaging force activates the color compositions in the color-producing layer creating indicia which are printed on both facing sheets. The color compositions are also mixed with an adhesive so that once printing has finished, the laminate construction may be peeled apart leaving a non-tacky label and a backing sheet (containing a duplicate copy of the information printed on the label).

0010EP-B-442732 describes a mailer comprising several layers which define an outgoing envelope, a ply including printed information and a return envelope. One of the layers of plies has a localised coating of self-imaging material on one side and a capsule coating on the other side which is used to impart variable data to an underlying ply via an impact printer.

0011However, these methods do not presently provide a means for achieving different selected colored areas on a form, label, tag or the like by printing in a single pass. Further, as the application of thermally sensitive coatings requires sophisticated coating equipment and techniques, it has heretofore been impractical to apply the coatings only in selected areas. Additionally, as thermally imagable coatings are typically applied to a high volume of substrates which are widely distributed for different end uses, manufacturers have produced fully coated webs or sheets to accommodate the greatest number of end uses of the products.

0012Accordingly, there still exists a need in the art for a business form, label, or the like having selected areas which produce selected colored areas when printed in a single pass through a direct thermal printer,

0013The present invention meets that need by providing a business record such as a form, label, or tag having coatings of initially colorless color formers and color developers on selected areas which may be activated to produce a selected color or colors when imaged in a thermal printer, The thermally imagable coatings may be applied in a cost effective manner by the manufacturer of the form, label, or tag on a selected area or areas of the form at the same time other routine operations are performed such as pre-printing information on the form or die-cutting the form to produce labels or tags.

0014In accordance with one aspect of the invention, an imagable business record such as a form, label or tag is provided comprising a substrate such as a sheet having first and second surfaces. Preferably, the sheet includes on selected portions of the first surface means for forming imaged areas comprising coatings of initially colorless color formers and color developers. The color formers and color developers combine and form a colored area upon application of a thermal imaging force. More than one different colored area may be formed.

0015In one embodiment, the color formers and color developers combine upon exposure to heat from a thermal print head to form colored visible areas including images, symbols, indicia, or the like on the sheet. Preferably, the color formers comprise initially colorless leuco dyes, while the color developers preferably comprise acidic phenolic compounds or resins. The color formers and developers are preferably contained in a binder matrix as separately dispersed particulate solids. Exposure of the coating to heat causes selected reactants to melt, permitting the color former and color developer to mix and react.

0016It is also possible in the embodiment using self-contained coatings to activate selected areas of the sheet so that only one color is produced. The self-contained coatings may be coated in a number of different patterns as described above.

0017While it is possible to activate several areas so that multiple colors are formed on a document, it is also within the scope of the invention to activate selected portions of the coated areas which produce only one color. The coatings may be applied to a form, label, tag or the like in a number of different patterns. For example, the coatings may be applied only around the peripheral edges of a sheet. Alternatively, if a bar code is to be thermally imaged on a label, the coating may be applied to one section of a label where the bar code is to be printed.

0018In one preferred embodiment of the invention, the outer peripheral area of the sheet is coated with a color former and color developer which form a first color, a middle peripheral area adjacent the outer peripheral area is coated with a color developer and color former which form a second color, and the inner peripheral area adjacent the middle peripheral area is coated with a color former and color developer which form a third color. In another embodiment of the invention, the different coatings may be coated in an alternating side-by-side relationship about the periphery of the record. By activating selected areas, the periphery can be made to show a selected color.

0019The substrate may be precoated to provide a smooth and non-porous base coat for the thermally imagable coating. The base coating may be applied to the entire surface of the substrate or only to the selected area of the substrate which is to receive the thermally imagable coating. The base coating may comprise any suitable water-based, solvent-based or ultraviolet radiation or electron beam cured polymer.

0020In another preferred embodiment of the invention, a protective coating is provided over the area or areas containing the thermally imagable coating to provide the subsequently printed thermal images with resistance to solvents, abrasion and fading due to exposure to light. The protective coating may be applied as a blend of electron beam curable oligomers and monomers, as a crosslinkable, water-based film forming prepolymer, or as a blend of ultraviolet radiation curable oligomers and monomers and a photocatalyst. The coatings are then cured or crosslinked to polymerize them.

0021In another embodiment of the invention, the sheet includes a plurality of columns, with each of the columns being coated with a color former and color developer which form a different selected color.

0022In an alternative embodiment of the invention, the substrate containing the thermally imagable coating comprises a series of labels where the second surface of the substrate is coated with an adhesive. The adhesive may be a permanent or repositionable pressure sensitive adhesive, a hot melt adhesive, or other suitable adhesive. A release liner is preferably adhered to the pressure sensitive adhesive so that the series of labels may be fed through a thermal printer for imaging.

0023In yet another embodiment of the invention, a continuous web for producing a series of thermally imagable business forms such as labels or tags is provided. The continuous web preferably includes first and second major surfaces, with the first surface of the web including a series of individual business records such as forms, tags, or labels, with each record including at least one selected area having a thermally imagable coating of initially colorless color formers, and the remaining areas of the individual records left uncoated. The web may also include on its second surface an adhesive. Where a pressure sensitive adhesive is used, the adhesive is covered by a release liner.

0024The present invention also provides a method of making a thermally imagable business record which includes the steps of printing indicia on selected portions of the first surface of the substrate and applying to at least one selected area of the substrate a thermally imagable coating of initially colorless color formers and color developers, leaving the remaining areas of the substrate uncoated. Alternatively, because the thermally-imagable coating of the present invention is applied as a high-solids content ink, the coating may be applied by conventional letterpress or offset gravure printing equipment.

0025In a preferred embodiment, the method includes the step of pre-coating the first surface of the substrate to provide a smooth and non-porous base coat prior to applying the thermally imagable coating. The method also preferably includes the step of applying a protective coating layer over the thermally imagable coating and then curing the coating. The coating may comprise a blend of electron beam curable oligomers and monomers, a crosslinkable, water-based film forming prepolymer, or a blend of ultraviolet radiation curable oligomers and monomers and a photocatalyst. The coatings are then cured or crosslinked to polymerize them.

0026In an alternative embodiment, the thermally imagable coating is applied to a series of areas on the substrate. The substrate is then die cut to form a series of labels. Preferably, the second surface of the substrate is coated with a pressure sensitive adhesive, and a release liner is adhered to the pressure sensitive adhesive.

0027Accordingly, it is a feature of the present invention to provide a business record such as a form, label, tag, or the like having on selected areas of its surface coatings of initially colorless color formers and color developers which, when exposed to a thermal imaging force, are activated to form one or more different colored visible areas. Other features and advantages of the invention will be apparent from the following description, the accompanying drawings, and the appended claims.

0028In order that the invention may be better understood, reference will now be made, by way of example, to the accompanying drawings, in which: <ul id="ul0001" list-style="none" compact="compact"><li>Fig. 1 is a plan view of a business form having selected activatable areas of color in accordance with the invention;</li><li>Fig. 2 is a plan view of a business form in accordance with another embodiment of the invention;</li><li>Fig. 3 is a perspective view of a continuous web of labels in accordance with the present invention;</li><li>Fig. 4 is a plan view of a business form in accordance with another embodiment of the invention; and</li></ul>

0029Fig. 5 is a plan view of a label having on a selected area of its surface a thermally imagable coating.

0030The coatings utilized in the present invention may be applied to any document or record including business forms, labels, tags, or other documents in which it is desirable to selectively designate colored and/or thermally imagable areas. The document may be paper or other printable material including plastic or synthetic fiber web or sheet material normally used for labels, tags, forms, etc.

0031Suitable color formers for use in the present invention include colorless chromogenic dye precursors known in the art such as triphenyl methanes, diphenyl methanes, leuco dyes, xanthene compounds, thiazene compounds, and spiropyran compounds such as those described in U.S. Patent No. 5,102,856. Many different shades or hues of color may be produced on a document by combining color formers which form blue, yellow, green and red colors. Black images may also be produced by using a combination of color formers. Preferably, the color formers comprise from about 4 to 18% by weight of the coating formulation and are prepared as a dispersion in water containing 45-55% solids.

0032The color developers may be selected from acidic color developers known in the art such as zinc salicylate, acetylated phenolic resins, salicylic acid modified phenolic resins, zincated phenolic resins, novolac type phenolic resins, and other monomolecular phenols such as bisphenol A, 4,4'-isopropylidene diphenol, 4,4'-sulfonyl diphenol, p,p'(1-methyl-n-hexylidene)diphenol, p-tert-butyl phenol, and p-phenyl phenol. The color developer is preferably present in the coating formulation from about 7 to 15% by weight and is also preferably prepared as a dispersion in water containing 45-55% solids.

0033In addition, the coating contains from about 40-70% by weight water, and from about 5 to 25% by weight of a sensitizer. Such sensitizers are low melting point solids which, when subjected to heat, melt and become solvents for the color forming and developing reactants. Suitable sensitizers include B-naphthol benzyl ether, p-benzyl biphenyl, ethylene glycol-m-tolyl ether, m-Terphenyl, Bis [2(4-methoxy) phenoxy] ether, and dibenzyl oxalate.

0034A binder is also included in the coatings to improve the rheological properties of the coating for better printability and to promote good adhesion of the coatings to the sheet surface. Suitable binders include starch, casein, polyvinyl alcohol, polyvinyl pyrrolidone, acrylamide/acrylate copolymers, carboxylated styrene butadiene latex, styrene acrylic latex, and mixtures thereof. Preferred for use in the present invention is a starch solution in water containing 12-40% solids, and a solution of a water soluble polymer or copolymer in water containing 30-35% solids. The starch solution comprises 15-35% by weight of the coating, and the polymer solution comprises 5-20% by weight of the coating.

0035The coating formulation may also optionally include from about 5 to 30% by weight of a pigment such as calcined clay, calcium carbonate, or plastic pigments. Other optional ingredients include from about 5 to 25% by weight of a lubricant and from about 1 to 10% by weight of an anti-fading agent. Suitable lubricants include zinc stearate, stearamide, and wax. The anti-fading agent may comprise hindered phenols of the antioxidant class such as 1,1,3-tris(2-methyl-4-hydroxy-5-cyclohexylphenyl) butane.

0036The coatings are generally applied to the business record substrate by any suitable coating or printing process including flexographic, letterpress, or gravure printing techniques. However, any suitable coating or printing process may be used including direct gravure or screen processes. The coatings may be applied in selected areas which can form blocks of background color, or they may be applied so as to form images, symbols, stripes, borders, and the like when passed through a thermal printer. Coatings which produce different colors are preferably coated or printed separately on each desired portion of the document. The coatings are preferably applied at a dry coating weight of between about 0.50 and 2.50 lbs/17"x22"x500 sheet ream (1.9 to 9.5 gm/m²), and may be selectively printed or coated on the surface of stock papers during the manufacturing process.

0037The substrate is preferably pre-coated to provide a smooth and non-porous base coat for the thermally imagable coating. The base coat comprises any suitable water-based, solvent-based, or ultraviolet light or electron beam curable polymer which may be applied in liquid form. Examples of such suitable base coating compositions are taught in commonly-assigned published PCT International Application No. WO 90/13064, published November 1, 1990.

0038If desired, the color former and color developer coatings may be overcoated with a protective coating composition which provides the subsequently printed colored areas on the substrate with resistance to solvents, abrasion and fading from exposure to light. An example of such a composition is disclosed in Mehta, U.S. Patent No. 4,999,334.

0039With reference to the drawings, it must be appreciated that requirements for solid black line drawings on a white surface make illustration of some of the subtleties of our invention relating to different colors difficult by the required drawings alone. Reference to the following detailed description of the illustration will make full appreciation of the drawings and our invention possible.

0040As can be seen in the drawing figures, the color former and color developer coatings may be printed on one or more selected portions of a document in a number of patterns, depending on the desired application. It should be appreciated that many different combinations for placement of the coatings on a document are possible and are within the scope of this invention.

0041Referring now to Fig. 1, a business record 10 is shown comprising a sheet having first and second surfaces. The first surface of the sheet includes selected portions 12, 14, and 16 around the periphery of the record containing coatings of initially colorless color formers and color developers. The outer peripheral area 12 of the sheet is coated with a color former and color developer which form a first color, the middle peripheral area 14 adjacent the outer peripheral area is coated with a color developer and color former which form a second color, and the inner peripheral area 16 adjacent the middle peripheral area is coated with a color former and color developer which form a third color.

0042As shown in Fig. 4, the coatings may also be applied in alternating side-by-side relationship about the periphery of the record. For example, block 46 is coated with a color former and color developer which form a first color, block 48 is coated with a color former and color developer which form a second color, and block 50 is coated with a color former and color developer which form a third color. Such an arrangement allows one color to be selectively activated around the boundary of the form to provide an indication of how the form is to be processed.

0043Direct thermal printers currently in use in the art include print heads or print bars with small heated elements which are individually addressable by digital input from a controlling computer. When the record is passed under the print head or print bar of a thermal printer, selected heated elements are activated and heat selected areas on the record. The coating in the selected areas is heated, causing at least one component of the coating to melt and permit the color formers and color developers to combine to form a visible color. For example, portion 12 of the document may include a coating which produces a red color, portion 14 may include a coating which produces a blue color, and portion 16 may include a coating which produces a yellow color. The thermal printer can be programmed to activate all of the colors, or only selected colors. Both the colored areas and printed information on the record can be formed in a single printing pass. Thus, by selecting which colored area to activate, one can produce a color-coded document which imparts information to an end user. For example, the color of the document may be used as an indication of which department in an organization to which the document is to be routed. Additionally, the document may be in the form of a tag or label which is attached to an article or package, with the color providing an indication of method of shipment. The possible uses of the invention are many and varied.

0044Fig. 2 illustrates another embodiment of the invention in which a business record 18 includes columns 20, 22 and 24 which are color activatable areas. The first column 20 is coated with a color former and color developer which form a first color, the second column 22 is coated with a color former and color developer which form a second color, and the third column 24 is coated with a color former and color developer which form a third color. In this manner, different categories or types of information can be emphasized or delineated without having to use preprinted colored screened areas.

0045In another embodiment of the invention illustrated in Fig. 3, a continuous form 38 is shown which contains a series of labels which are coated in selected areas to create different colored areas when printed with a thermal printer. If desired, the web may be preprinted with nonvariable, repetitive information by automated equipment and then coated in accordance with the present invention so that variable information may be printed in the color activatable areas. For example, as shown in Fig. 3, areas 44 contain preprinted information, area 40 is coated with a color former and color developer which forms a first color, and area 42 is coated with a color former and color developer which form a second color. Alternatively, the entire surface of the continuous form may be coated with self-contained coatings and printed using an impact printing device.

0046Referring now to Fig. 5, a label 10 is shown comprising an substrate having first and second surfaces. The first surface of the sheet includes a selected area 12 containing a thermally imagable coating of initially colorless color formers and color developers and an uncoated area 14 which contains preprinted indicia. As shown, the thermally coated area 12 has been imaged to provide variable information as well as bar coded information on the label.

0047Direct thermal printers currently in use in the art include print heads or print bars with small heated elements which are individually addressable by digital input from a controlling computer. When the record is passed under the print head or print bar of a thermal printer, selected heated elements are activated and heat selected areas on the record. The coating in the selected areas is heated, causing at least one component of the coating to melt and permit the color formers and color developers to combine to form a visible color. For example, the thermal printer can be programmed to print varied information in one selected area as shown in Fig. 5.

0048The invention provides the advantage that one form may be printed with several different activatable color combinations instead of using multi-ply labels or forms which require a different color for each ply. In addition, the invention provides a means of emphasizing or designating different categories of information on a form without having to use preprinted colored screened areas which require separate printing stations. As the coatings are initially colorless, the entire record, form, label, or tag may be initially white, and only the information and colors required for that particular form can be activated. This permits the user to print color customized records as needed.

0049The invention also provides the significant advantage that a business form may be provided with a thermally imagable coating only in those areas which are to be subsequently imaged. In addition, the method is convenient and cost-effective because the coating is a high-solids content ink which can be applied in line at the same time other steps are being performed such as preprinting information, die-cutting labels, etc. For example, a preferred process of making the business records of the present invention includes printing fixed or variable indicia on the substrate, followed by application of the thermally imagable coating to one or more selected areas or to the entire surface of the substrate, then die-cutting the substrate, and perforating and folding the die cut labels.

0050Further, the invention has the advantage that both information and the colored areas on the document may be achieved by printing in a single pass through a thermal printer.

0051Other uses for the present invention include airline tickets or event tickets. For example, different colors could be activated on an airline ticket to designate first class or coach seating. The invention could also be used for shipping labels in which different colors are activated to designate the method or location of shipment. Other potential uses for the present invention will be apparent to those skilled in the art.

0052In order that the invention may be more readily understood, reference is made to the following examples which are intended to illustrate the invention, but not limit the scope thereof.

Example 1

0053The following materials were combined to produce a preferred coating formulation: <tables id="tabl0001" num="0001"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><thead valign="top"><row rowsep="1"><entry namest="col1" nameend="col1" /><entry namest="col2" nameend="col2" align="center">Weight %</entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">Color former¹</entry><entry namest="col2" nameend="col2" align="char" char=".">11.5</entry></row><row><entry namest="col1" nameend="col1" align="left">Color developer²</entry><entry namest="col2" nameend="col2" align="char" char=".">12.0</entry></row><row><entry namest="col1" nameend="col1" align="left">Sensitizer³</entry><entry namest="col2" nameend="col2" align="char" char=".">7.5</entry></row><row><entry namest="col1" nameend="col1" align="left">Binder⁴</entry><entry namest="col2" nameend="col2" align="char" char=".">3.5</entry></row><row><entry namest="col1" nameend="col1" align="left">Water</entry><entry namest="col2" nameend="col2" align="char" char=".">46.5</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">Pigment⁵</entry><entry namest="col2" nameend="col2" align="char" char=".">20.0</entry></row></tbody></tgroup><tgroup cols="2" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><tbody valign="top"><row><entry namest="col1" nameend="col2" align="justify">¹OBD-2 from Nagase America Corporation</entry></row><row><entry namest="col1" nameend="col2" align="justify">²Bisphenol A from Nagase America Corporation</entry></row><row><entry namest="col1" nameend="col2" align="justify">³m-Terphenyl from Nagase America Corporation</entry></row><row><entry namest="col1" nameend="col2" align="justify">⁴Polyvinyl alcohol from Air Products Company</entry></row><row><entry namest="col1" nameend="col2" align="justify">⁵Calcium carbonate from J.M. Huber Company</entry></row></tbody></tgroup></table></tables>

Example 2

0054The following materials were combined and blended by mild agitation to produce a preferred thermally imagable coating formulation: <tables id="tabl0002" num="0002"><table frame="all"><tgroup cols="2" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><thead valign="top"><row rowsep="1"><entry namest="col1" nameend="col1" /><entry namest="col2" nameend="col2" align="center">Weight %</entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">Color former¹</entry><entry namest="col2" nameend="col2" align="center">8</entry></row><row><entry namest="col1" nameend="col1" align="left">Color developer²</entry><entry namest="col2" nameend="col2" align="center">13</entry></row><row><entry namest="col1" nameend="col1" align="left">Sensitizer³</entry><entry namest="col2" nameend="col2" align="center">12</entry></row><row><entry namest="col1" nameend="col1" align="left">Binder⁴</entry><entry namest="col2" nameend="col2" align="center">20</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">Water</entry><entry namest="col2" nameend="col2" align="center">47</entry></row></tbody></tgroup><tgroup cols="2" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="78.75mm" /><colspec colnum="2" colname="col2" colwidth="78.75mm" /><tbody valign="top"><row><entry namest="col1" nameend="col2" align="justify">¹ Black 305 from Nagase America</entry></row><row><entry namest="col1" nameend="col2" align="justify">² Bis(3-allyl-4-hydroxyphenyl) sulfone from Nagase America</entry></row><row><entry namest="col1" nameend="col2" align="justify">³ P-benzyl biphenyl from Nagase America</entry></row><row><entry namest="col1" nameend="col2" align="justify">⁴ Starch solution and polyvinyl alcohol from Penford Products</entry></row></tbody></tgroup></table></tables>

0055While certain representative embodiments and details have been shown for purposes of illustrating the invention, it will be apparent to those skilled in the art that various changes in the methods and apparatus disclosed herein may be made without departing from the scope of the invention, which is defined in the appended claims.