MXPA02005585A - Multiple substrate ply attachment utilizing a flexographic printing process to apply chemical adhesives onto tissue. - Google Patents

Abstract

The process of the present invention utilizes a flexographic magnetic printing roll (12) that is capable of applying either an ink, adhesive, and water mixture or an adhesive and water mixture onto a tissue (20) between the plies for ply attachment and artwork application. Thus, two or more ply tissues and towels made according to the present invention are printed with artwork and treated with an adhesive solution during one flexographic printing process.

Description

SUBJECTING THE LAYER OF MULTIPLE SUBSTRATES USING A PROCESS OF FLEXOGRAPHIC PRINTING TO APPLY ADHESIVES CHEMICALS ON A TISU Field of the Invention The present invention is directed to a process for joining together two or more printed layers of works of art through the use of an adhesive.

Background of the Invention Previously, most of the multilayer tissue products known in the medium have been defective because the multiple layers of the tissue are frequently inadequately bonded and the two layers frequently separate on the roll when being used. This results in the potential for the user to tear a sheet of tissue and use the back or back side. When the tissue layers are turned over, the consumer inadvertently uses the rough, rough and scraping side of the tissue instead of the soft, smooth side, thus causing dissatisfaction in the consumer.

In order to improve the quality of multilayer tissue products as it relates to the reverse side of the layer, improved layer bonding processes are needed. Such a bonding process optimally has a low operating cost, and low cost of ... i • - »_.- > ._. ^ ._ -.--. * ...? capital, and a minimum of negative impact on the product.

Typically, when two or more layers of tissue printed with works of art are joined by adhesive glue, two completely separate processes are required. It takes a process to mechanically apply the design printed in artwork ink on the tissue while a second process is necessary to apply a sticker to the tissue. The use of two separate processes results in increased production costs and maintenance costs as well as increased cleaning time of the machinery.

U.S. Patent No. 3,414,459 to Wells, for example, employs the steps of separately embossing each of the two sheets of paper and then bonding them together with adhesive to form a laminated paper structure. Similarly, U.S. Patent no. 5,858,554 to Neal et al. Is directed to a multi-layered paper product where the layers are bonded through the use of an aqueous adhesive composition. The specification of this patent reveals that the layers are enhanced, but such embossing is done after the layers have been formed but before the adhesive composition is applied on one or both layers.

In the same way, the Patent of the United States of America no. 5,874,157 to Robinson et al., Describes a laminated paper product consisting of a plurality of sheets that are bonded with a laminated adhesive. The sheets may have joint embossing or embossing sites, however, the embossing of the sheets is given before the joining process involving the lamination adhesive. Comparatively, WO 98/50482 to Nunes et al. Is directed to an adhesive composition for laminating a paper absorbent product and a method for making the same. This patent also claims the paper product wherein the embossed layers are laminated using this adhesive composition. However, the layers have been previously pre-embossed before being treated with the adhesive compound. Thus, these patents illustrate how the two processes of printing a work of art design on a tissue and applying an adhesive to the same tissue are traditionally separate processes.

Other methods than those employing an adhesive solution are known in the media to join layers of laminated fabric to form a single laminate. For example, U.S. Patent Nos. 4,806,418 and 4,867,831 to Sigl, both assigned to the assignee of the present invention, provide for a bonding of layers through the distribution of thermoplastic particles between the layers and the subsequent melting of those layers. particles to join the fibers of the layers.

Moreover, the United States Patent of l «ja_. _-._ i.-Li-Í --- ¿_- i- _, _ & É «-------. . ..-. tln. , - ..._. . ._.-. ._.__ .. .. -_ »-_," _.-, ____,? _ _ _ _-_ "._. < .-.-- St. - _.- i America núm. 5,143,776 to Givens is directed to a laminate of two laminated fabrics bonded with adhesive by hot melt adhesive. In this patent, the hot melt adhesive forms the pattern of a single longitudinal or transverse oriented web. The patent states that the adhesive strip is interposed between the sheets, but does not suggest that the application of the hot-melt adhesive can simultaneously involve the printing of an artwork design.

Also, the United States Patent of America no. 4,816,320 to St. Cyr describes a process in which the outer surface of a tissue layer is speckled or dotted with splashes or atomized drops of adhesive material sprayed thereon. The multiple layers are then joined to form integral sheets of improved tissue. Thus, the methods described for joining multiple layers of tissue to form a tissue laminate do not contemplate the combination of a process for applying an adhesive solution with a process for imparting a printed design of artwork to the same tissue layers.

Flexographic processes have been frequently used in the printing industry, and such flexographic printing processes have proven to have a negligible impact on the increase of the stiffness of the tissue layers.

Various products are known in the medium that can be used as flexo and / or magnetic printing plate assemblies. A European Patent, EP 0058737 / A1, describes a flexographic photosensitive element. The flexographic element in this reference consists of a layer of a photosensitive elastomeric composition attached to a flexible support. This element is useful in the preparation of flexographic printing plates.

Similarly, U.S. Patent no. 3,670,646 to Welch, Jr., Is directed to a flexible sheet metal / print chair assembly on which magnetic particles are incorporated to provide improved means for securing the printing plate to the printing press. Also, the Patent of the United States of America no. 3,824,927 to Pugh et al., Provides for a printing member in which the printing element is held in position on a conventional roller by magnetic means. Such printing assemblies are useful in the printing of designs of works on tissue laminates; however, they do not provide any means to simultaneously apply an adhesive solution to the tissue layers.

Therefore, there is currently a need for a single more efficient process that combines the application of a printed design in artwork ink to a tissue with the application of a tissue adhesive. ii -., -. a _-_ t-: i, fc-¿,, ..- < _ '., .- ..

Synthesis and Objectives of the Invention It is an object of the present invention to combine the process of applying a printed design in artwork ink to a tissue and the process of applying an adhesive to a tissue in a single, more efficient process.

This and perhaps other objects of the present invention are achieved through the use of a magnetic flexographic printing roller that applies both an ink, adhesive, and water mixture or an adhesive and water mixture to the tissue between the layers for the purpose to unite the layers and / or the application of works of art. In certain embodiments of the present invention, the magnetic flexographic printing roller is in the form of a desired work of art and uses the design of artwork to apply the chemical blend of adhesive onto the tissue.

In contrast to the processes and products described above, the process of the present invention does not involve a flexographic element covered with an elastomeric composition described in EP 0058737 / A1. The invention contemplated here, in fact, goes beyond the creation of both a new flexographic element or a new printing plate assembly and seeks to combine two traditionally separate processes (the application of a printed design of a work of art to a tissue). and the application of an adhesive to the tissue) in a single it I J.I.-Í_. more efficient process. The references to patents described above do not contemplate such a combination of two separate processes with the use of a flexographic printing roller.

In certain embodiments of this process, the chemical mixture is a part of water, a part of adhesive, and 0.0302 parts of ink completely concentrated. In other embodiments, a mixture of a single adhesive and water containing 1 part of adhesive and 1 part of water is used. These and other features, aspects and advantages of the present invention will be better understood with reference to the following description and the appended claims.

Brief Description of the Figures Figure 1 shows a schematic diagram of the flexographic printing process described herein.

Figure 2 shows an orchid printing pattern used in the flexographic process described here.

Figure 3 shows a mottled printing pattern with a low printing area used in the process of the present invention.

Figure 4 shows a mottled printing pattern with an average printing area used in the process of the present invention.

Detailed Description of Representative Incorporations Reference will now be made in detail to the embodiments of the invention, one or more examples of which are described below. Each example is provided as a means of explaining the invention, not limiting the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made in the present invention without departing from the scope and spirit of the invention. For example, features illustrated or described as part of an embodiment can be used in another embodiment to produce yet another embodiment.

Thus, it is intended that the present invention cover such modifications and variations as come within the scope of the appended claims and their equivalents. Other objects, descriptions and aspects of the present invention are described or are obvious from the following detailed description. It should be understood to anyone with ordinary skill in the art that the present description is a description only of exemplary embodiments, and is not intended as limiting the broad aspects of the present invention, the broad aspects of which are incorporated in exemplary constructions.

The process of the present invention joins two layers * * & * & of bath tissue using a magnetic flexographic printing roller to apply both an ink, adhesive and water mixture or an adhesive and water mixture on the tissue between the sheets for the purpose of joining layers with and without simultaneous application of works of art . This magnetic flexographic printing roller provides the desired artwork and uses its design capabilities of the artwork to apply this chemical blend to the tissue. Thus, the process combines two manufacturing processes in a more efficient process. This combination of two processes in one results in greater efficiency due to reduced production and maintenance costs. Also, the cleaning time of the machinery is reduced through this combination.

Various processes for making tissue are known in the medium. In particular, the Patent of the United States of America no. 5,129,988 to Farrington, Jr. , and the Patent of the United States of America no. 5,494,554 to Edwards et al., Describe various methods for making tissue and processes to form multilayers of paper tissues. Such patents are incorporated herein by reference in their entirety. These processes for making tissue and the resulting tissue products can be used in the process of the present invention to form the tissue layers which are then printed with works of art and joined by the flexographic printing roller described herein.

In addition, the processes for the formation of dry non-creped fabrics by air described in U.S. Pat. Nos. 5, 779,860 to Hollenberg et al., And 5,048,589 to Cook and others, both of which are assigned to the assignee of the present invention and both are hereby incorporated by reference in their entirety. In such processes, air drying is employed as shown in the Cook and other figures. As described and shown in them, a fabric is manufactured: 1) forming a supply of cellulose fibers, water, and a chemical debonder; 2) depositing the provision on a tape in foraminous movement, therefore forming a fibrous tissue on the tape in foraminous movement; 3) by subjecting the fibrous tissue to non-comprehensive drying to remove water from the fibrous tissue; and 4) removing the dry fibrous tissue from the foraminous moving tape. The process described here does not include creping and it is thus, referred to as non-creped through the air drying process.

The tissue products prepared by this non-creped process through air drying will typically possess relatively high levels of absorption capacity, absorption level and firmness. Additionally, because the process avoids the use of expensive creping steps, the tissue products formed in accordance with such processes will generally be more economical to produce than creped towels of similar composition and basic weight. _..., -.-_., ..., A process that produces a non-compressed sheet using possible drying that can be employed in the present invention is described in the US Pat.

America no. 5,336,373 to Scattolino et al., Which is incorporated herein by reference in its entirety.

Embodiments of the present invention are represented by the process contained in Figure 1. In such incorporations, the bonding of layers using an ink, adhesive and water mixture can be achieved by mixing 1 part water with 1 part adhesive and 0.0302 parts. of full ink concentrate to produce the final chemical solution. This adhesive solution is pumped to the reservoir or doctor chamber 8 and then applied on the counter roller 10 by the doctor chamber 8 using two doctor blades which keep the doctor chamber 8 sealed. The counter roller 10 operates in a similar manner to an engraving roller except that the counter roller 10 is more durable and has a longer productive life in commercial applications. The counter roll 10, used in certain embodiments of the present invention, is made by placing a cover (approximately 0.020 inches thick in some cases) of chromium oxide on the outer perimeter of a round steel roll. The chromium oxide can then be etched with a laser. The laser burns microscopic "cavities" called engraving cells on the surface of chromium oxide.

Therefore, these microscopic pores along the roller against closure 10 are filled with the above described mixture of ink, adhesive and water as the roller 10 is rotated on its center line. The adhesive solution is then mechanically transferred onto the flexographic printing roller 12. Now the filled microscopic cells or pores are rotated which come into contact with the rubber flexographic printing roller 12. A specific measured quantity of the chemical mixture is then transferred, due to capillary forces, out of the engraving cells on the roller against closure 10 and on the flexographic rubber roller 12.

This printing roller 12 has a highlighted pattern of artwork on its surface, and makes contact with the inside of the first sheet 20 of two sheets of tissue and applies or prints the mixture on the first sheet 20. This first sheet 20 , now it contains the mixture of ink, adhesive and water on its surface, it is then gathered by the untreated tissue sheet 22, and the two sheets 20 and 22 are "married" with the backing roller or the wedding roll 14. The two-layer sheet 24 then passes over another rubber roll 16 and can then be converted into additional processes.

Thus, the present invention produces a tissue product wherein the ink, the adhesive and the water mixture are between the layers and not outside as in the known products. i.4. --- _- '. < . In alternate embodiments of the present invention, the processes described above are developed with a mixture of adhesive alone and water, containing for example, a part of adhesive and a part of water.

In certain embodiments of the present invention, a towel may be the substrate rather than a tissue. The towel is equally capable of going through the flexographic printing process described above.

In an embodiment of the present invention, the highlighted engraved artwork design located on the flexographic roller includes floral designs such as orchids, which apply the chemical mixture of ink, adhesive and water or only of adhesive and water to the tissue or towel.

Examples The present invention can be understood with reference to the following examples, without being limiting. Two experimental runs of test were performed in accordance with the present invention. These two experiments investigated the possibility of obtaining the bonding of layers for two non-creped layers through air drying of bath tissue using the flexographic bonding process described herein. Both the effectiveness of the process of - ná _._.; - .ifr __'- l-W-ft - M-- ttta? -? ? --.....-- - • --.-_--.:- -, ..-. ., -.__. ". - .--- adhesion as the effects on the quality of the tissue products. In both Examples, the process of the present invention was performed on bath tissue at a rate of 350 feet per minute, and a pilot scale plant equipment was used during these experiments.

Specific descriptions about the test runs and the results of each Example are broadly described below. Generally, the experiments 10 described in these examples show successful bonding of layers at conversion rates of 350 feet per minute. Also, the quality of the tissue products formed in accordance with the present invention proved to be comparable to the quality of the tissue products laminated together by other bonding methods. 15 layers such as the one used of a frizz wheel.

Example 1 During the Example, the adhesive used was product number 48037 manufactured by Reichold Chemicals, Inc. of Durnham, North Carolina. This adhesive is a starch base adhesive with a viscosity of approximately 70 centipoise. Even though this particular adhesive was used in these examples, any adhesive such as cellulose base, polyvinyl base, etc., may be employed. Additionally, adhesives having a viscosity from about 20 to about 200 centipoise generally meet the «N ^ - -JÉii t i -t > -t - i - «--. - .--? --.---- fc-- < -fa --- A- < requirements of a sufficient adhesive to bind to it the final glue or adhesive that was applied to the sheet during this Example which was 50 percent by volume of glue and 50 percent by volume of water mixture.

During this experimental test, ink was added to the glue and the water mixture. The ink used in the present was dark charcoal gray water based ink (product number 430-Z-4, "Butterfly Gray" color code) manufactured by Daw AJ Printing Co. of Appleton, Wisconsin. However, alternative water-base inks of any color and any level of concentration can be used in the process of the present invention. The ink was mixed with the glue and water as follows: 1.75 gallons of Reichold 48037 adhesive, 1.75 gallons of water, and 200 milliliters of gray ink. All the chemicals used were 100% water soluble.

A flexographic bonding process was carried out. The converter equipment used in this experiment was assembled in the following order: first unwind, second unwind, long roll calender, coater (modified to become a flexographic printer), small calender roll, and reel. The conversion rate was 350 feet per minute using two non-creped layers of air drying of bath tissue with a total weight of 20 pounds / 2880 square feet. The process was performed to laminate together two layers of bath tissue using the above-described water-soluble starch-based adhesive.

The process scenario for this Example is described below in Table 1: Table 1 The flexographic printing pattern used during this experiment was an orchid pattern, shown in Figure 2. This orchid pattern results in a high adhesion bond in relation to the tissue sheets because the pattern has a large contact area . Thus, an optimal balance between the concentration of solid liquid glue and the printing area was reached as the printing area increases, .------. fa- -t. _ i i i j the concentration of solid adhesives decreases and vice versa. It was found in the experiments carried out according to Example 1 that the addition of 5 percent solid weight glue in conjunction with the orchid printing pattern produces sufficient bonding of layers.

The test method used to determine the success of the bonding of the layer was Standard Test Method 814-W in which a slip / peel tester (manufactured by Instrumentors, Inc.) was used. The peeling tester was used in the maximum load placement.

In general, the results of the experiments performed in accordance with Example 1 resulted in high quality joining of layers at a machine speed of 350 feet per minute. Also, the total product quality of the resulting two-ply tissue product produced by the flexographic bonding process was comparable to the product quality of the tissue products produced using previous art control processes. For example, the tissue products formed in accordance with the flexographic process of the present invention have similar softness, stiffness, and hanging as the tissue products in which the bonding of layers was facilitated by a creping wheel. Furthermore, with the flexographic bonding process, it was found that the absorbency, volume, wet and dry resistance, opacity, and brightness did not seem to differ significantly from other prototypes made without the flexographic process. Thus, the adhesive flexographic process did not negatively impact the total quality of the products.

Tests were also conducted to compare the glued product produced in accordance with the present invention with a non-glued prototype. Various softness tests (such as hand quality and simulated use panel) showed that the prototypes formed in accordance with the present invention demonstrated comparable characteristics.

Example 2 During this Example, the adhesive used was a product number 18-1537 manufactured by National Starch and Chemical Co. of Bridgewater, New Jersey. This adhesive is also of starch base with a viscosity of approximately 70 centipoise and is 100% soluble in water. The final glue or adhesive that was applied to the sheet during this experiment was 70 weight percent glue and 30 weight percent water mixture. No ink was incorporated into the mixture used here.

The total flexographic process used in the Example 2 was identical to that used in Example 1 except the use of a different adhesive without the addition of an ink. The process scenario for this experiment is described below in the Table II: Table II One of the flexographic printing patterns used in this Example was the orchid printing pattern, shown in Figure 2. It was determined during the process of this Example that the level of the added glue relative to the tissue sheet should be approximately 5. percent of weight of solids to obtain an acceptable union of layers when the orchid printing pattern is used.

Attempts were made during the process of this Example to use two other flexographic printing plates with several printing areas. These other printing plates were used to minimize the bonding glue relative to i - ^ '' 'i, -., -) - ...: the tissue sheets reducing the contact area of the flexographic printing plates. A pattern of speckle printing with a low print area (see Figure 3) and a mottled print pattern with a medium print area (see Figure 4) was used. The specks printed on the tissue sheets in both Figures 3 and 4 were 3/64 inches in diameter. The pattern with the low print area has speckles spaced 1 inch and in a 45 degree diamond pattern. The print pattern with the average print area has flecks spaced ½ inch also in a 45 degree diamond pattern.

These and other modifications and variations to the present invention may be practiced by those skilled in the art, without departing from the spirit and scope of the present invention, which is more particularly described in the appended claims. Additionally, it should be understood that aspects of several incorporations can be exchanged both in their entirety and in part. Moreover, those skilled in the art will appreciate that the foregoing descriptions are merely as an example, and that it is not intended to limit the invention more broadly described in the appended claims. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained herein. Í, l-i-l: «.«, T. _ ti

Claims (13)

R E I V I N D I C A C I O N S

1. A method for forming a tissue product having a printed design on at least one of its surfaces, said method comprises: provide a first sheet of tissue, provide a second sheet of tissue; applying a mixture of adhesive to one of said first or second tissue sheets with a flexographic printing roller having a pattern highlighted on its surface to print said pattern on one of the tissue sheets; Y then compressing said first and second tissue sheets together to form a multi-layer tissue having said design printed thereon.

2. The method as claimed in clause 1, characterized in that said adhesive mixture also comprises an ink.

3. The method as claimed in clause 1, characterized in that said adhesive mixture comprises an adhesive and water in sufficient quantities to allow said tissue sheets to be formed in a tissue of Í_l-_fc-AA -.- - .. faith ---._-.- multiple layers.

4. The method as claimed in any of clauses 1 or 2, characterized in that said highlighted design is a floral design.

5. The method as claimed in any one of clauses 1 or 2, characterized in that said adhesive solution comprises an adhesive with a viscosity in the range of from about 20 to about 200 centipoise.

6. A multi-layer tissue laminate that is joined by a flexographic printing process wherein the interior of a layer of said laminate has been printed with a design and treated simultaneously with an adhesive mixture by means of a flexographic printing roller, said flexographic printing roller has said design on its surface, said design being a highlighted design.

7. A two-layer laminate as claimed in clause 6, characterized in that said adhesive mixture comprises an adhesive and water in sufficient quantities to enable said layers to be formed in a multilayer laminate.

8. A laminate of two layers as claimed in clause 6, characterized in that said mixture _to_--_. adhesive comprises an adhesive and an ink.

9. A laminate of two layers as claimed in any of clauses 6 or 7, characterized in that said highlighted design is a floral design.

10. A laminate of two layers as claimed in any of clauses 6 or 7, characterized in that said adhesive solution used to treat one of said layers of said laminate comprises an adhesive with a viscosity of between about 20 cp and 200 cp .

11. A laminate of two layers as claimed in any of clauses 6 or 7, characterized in that said laminate is a tissue product.

12. A laminate of two layers as claimed in any of clauses 6 or 7, characterized in that said laminate is a towel.

13. A laminate of two layers as claimed in any of clauses 6 or 7, characterized in that said laminate is a tissue product chosen from the group of tissue for bathroom or facial tissue. E U M N The process of the present invention utilizes a flexographic magnetic printing roller which is capable of applying either an ink, adhesive and a mixture of water or an adhesive and a mixture of water on a tissue between the layers for the layer and the substrate. application of an artistic work. Therefore, towels and tissues of two or more layers made according to the present invention are printed with an art work and treated with an adhesive solution during a flexographic printing process.