MXPA97003936A - Process of impression of a single substrate and of pasorepetido, and the substrates asi impre - Google Patents

Abstract

The present invention relates to a step-repeating, single-substrate printing process, comprising: providing a constantly moving substrate, passing a portion of a substrate that is constantly moving through a printing station only once without printing directly on it, re-pass the portion of the substrate that constantly moves through the printing station and again another portion of the substrate that moves constantly, which is a simple step through the printing station , and print the ink on the portion of the substrate that is constantly moving what is to pass repeatedly through the print station.

Description

PRINTING PROCESS OF A SINGLE SUBSTRATE AND OF A REPEATED PASSAGE, AND THE SUBSTRATES SO PRINTED The present invention pertains to a process for printing substrates and the substrates thus printed.

Ink printing on fabrics, such as woven and non-woven fabrics, with various patterns and colors, is well known. Then these woven fabrics are incorporated into different products, such as personal care products. Examples of personal care products include diapers, diapers, trainers, incontinence products and the like. Printed fabrics are used, mainly to improve, aesthetically, the appearance of the products.

A current problem in ink printing processes is that the ink or inks can be run, i.e., penetrate through the fabric, and particularly, into a low basic weight fabric. Low weight basic fabrics are generally thin, and inherently include a small number of voids, or a large number of smaller voids, through which ink can penetrate. The problem with the penetration of the ink is that the ink accumulates, for example, a printing cylinder of a printing apparatus. This buildup in the print cylinder results in poor print quality on the fabric, ink transfer at the back of the fabric and poor efficiency, due to the time it takes to stop the machine and to remove the accumulation of ink.

This problem is even more significant in high-speed printing environments, where the accumulation of ink accelerates and increases the number of times it takes to stop the machinery, to remove the accumulation. As the number of machine stops increases, so does the waste of material and ink associated with starting the machinery.

One attempt to solve ink buildup is to use scraper blades on the print roller or the like. Although the scraper blades remove ink buildup while the machinery is operating, its use causes premature wear of the surface of the cylinder or roller that supports the fabric. This, in turn, results in increased costs, due to the need to prematurely replace worn equipment.

Another attempt to eliminate the accumulation of ink is to run the layer of material between the fabric and the printing roller. The layer is designed to collect or absorb the ink that passes through the fabric and remove it. This has proven to be very expensive, either because the layer needs to be replaced with a new one, or because the layer must be wiped of ink before it is run again through the printing apparatus.

Therefore, it is an object of the present invention to provide a method of printing on a substrate which prevents ink from traversing and avoiding the disadvantages of prior art attempts, and such a printed substrate.

This object is solved by the method according to independent claim 1, and the substrates according to independent claims 13 and 15.

Further details, aspects and additional advantageous features of the invention are apparent from the appended claims, the description and the drawings. The claims are intended to be understood as a first, non-limiting, approach to the definition of the invention in general terms.

In one form of the present invention, a process for repeated step printing on a substrate is provided, which includes providing a constantly moving substrate; passing once a portion of the substrate that moves constantly through the printing station without printing therein; re-passing the portion of the substrate that is constantly moving again through the printing station and on top of another portion of a constantly moving substrate that is a simple step through the printing station; and the printing ink on the constantly moving portion of the substrate that is passed back through the printing station.

In another form of the present invention, a printing substrate is provided that includes a substrate having a pair of opposing surfaces and a pattern that is printed on one of the surfaces by means of the repeated step printing.

In yet another form of the present invention, a printed substrate is provided, which is made by means of a process that includes, providing a constantly moving substrate, passing once a portion of the substrate that moves continuously through a station. of printing without printing on it; re-passing the portion of the substrate that is constantly moving again through the printing station and on top of another portion of the constantly moving substrate which is a simple step through the printing station; and printing ink on the portion of the substrate that moves constantly, which is to repeat the step through the printing station.

The aforementioned method and other features, aspects and advantages of the present invention, and the manner of achieving them, will be more apparent and the invention itself will be better understood, in relation to the following description taken together with the accompanying drawings, wherein: Figure 1 illustrates a cross-sectional, fragmentary view through a portion of a prior art apparatus; Figure 2 illustrates a fragmentary view of a low weight basis substrate that is printed by means of the apparatus of Figure 1; Figure 3 illustrates, schematically, an apparatus that operates in accordance with the principles of the present invention; Figure 4 illustrates a cross-sectional, fragmentary view through a portion of the central printing cylinder in Figure 3; and Figure 5 illustrates a fragmentary view of a low weight basis substrate printed in accordance with the principles of the present invention.

In many of the prior art processes for printing a substrate, portions of ink applied to the substrate can pass through the substrate and be deposited on the surface of, for example, a printing cylinder. This is what is meant by the term "trespass" and causes the ink to accumulate in the impression cylinder. The transfer and accumulation of ink is what results in a poor quality print on the substrate, the transfer of ink to the back of the substrate surface, and poor operating efficiency, due to the detention time required to remove the accumulation of ink. Moreover, the transfer of ink causes various undesirable graphic effects on the substrate, such as fuzzy colors, blurred pattern, defective registers, or the like. These unwanted effects are unpleasant for the consumer, and tend to cause a perception of a product of poor quality and performance.

Referring to Figures 1-2, there is illustrated a prior art printing technique in which a substrate 10 is supported and transported by a print center cylinder 12. The substrate 10 has a printing surface 14 and a support surface 16. An ink pattern 18 is printed on the printing surface 14 of the substrate 10 by a series of printing cylinders (not shown). Although Figure 1 illustrates, in order to facilitate the explanation, the substrate 10, the cylinder 12 and the ink pattern 18 while slightly separating, these are, in fact, in contact so that the support surface 16 of the substrate 10 is in contact with the cylinder 12, and the ink pattern 18 is in contact with the printing surface 14 of the substrate 10.

The ink 20 (Figure 1) is printed on the printing surface 14 in order to form an ink pattern 18. However, since the substrate 10 has an inherent propensity for the ink to pass through and accumulate in the ink apparatus. printing, the ink portions 20 can pass through the printing surface 14 and traverse the support surface 16. As a result of this, the ink can be deposited as ink accumulations 22 on the surface 24 of the central printing cylinder 12. This transfer of the ink is what results in poor printing quality on the substrate 10, ink transfer on the surface of the ink. support 16, and causes low operating efficiency due to the time it takes to stop the machinery to remove ink buildup in the cylinder 12. An example of a substrate 10 that has an inherent propensity for ink transfer is a substrate non-woven having a basic weight equal to or less than about 20 grams per square meter.

Figure 2 illustrates the results that may occur in the prior art printing by the accumulation of ink in the central printing cylinder 12. In Figure 2. the ink pattern 18 has the shape or design of a vehicle. The poor quality of the ink pattern 18 is illustrated by a visible effect of ink 20 which is deposited on the surface 24 of the cylinder 12, and transferred to the supporting surface 16 (Figure 1) of the substrate 10. The ink transfer can cause various graphic effects, such as fuzzy colors, fuzzy patterns, bad registration or similar. Clearly, these are highly undesirable effects that are not aesthetically pleasing, and tend to cause a perception that the product has poor quality and poor performance.

Figure 3 illustrates an apparatus 26, which can be operated in accordance with the principles of the present invention, to print a substrate by a repeated step process, such as a double-pass process, which practically eliminates ink build-up.

The term "substrate" includes, but is not limited to, woven or nonwoven webs, porous films, permeable ink films, paper or composite structures comprising a combination thereof. A nonwoven substrate is considered a "low basis weight" substrate, when its basis weight is equal to or less than about 20 grams per square meter (g / m2). Other substrates, other than nonwoven substrates, are considered to have an inherent propensity for ink transfer and cause accumulation of ink in the printing apparatus.

The term "pattern" when used in reference to ink printing herein includes, but is not limited to, any type of design, brand, figure, identification code, graphic, word, image, or the like.

Desirably, the present invention utilizes a flexographic printing process to provide the proper balance effectiveness, cost, high speed, and high quality. The printing process is suitable for printing substrates of low basic weight, such as non-woven networks of low basic weight, while maintaining the softness of the substrate. Flexography is a printing technology that uses a flexible protruding rubber or photopolymer plates to carry the pattern that will be given to the substrate. Flexible plates typically carry a low viscosity ink directly on the substrate. Examples of low viscosity inks include inks comprising a non-catalytic urethane block resin and a solvent mixture of up to about 50% by volume of acetate and up to about 75% by volume of glycol ether. The solvent mixture can also comprise up to about 10% by volume of alcohol.

The desired acetates include ethyl acetate, N-propyl acetate, N-butyl acetate, isopropyl acetate, isobutyl acetate, butyl acetate and mixtures thereof.

The desired glycols ethers include ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethyl glycol monoethyl ether, diethyl glycol monopropyl ether, propylene glycol monoethylene ether and mixtures thereof.

Suitable alcohols include ethyl alcohol, isopropyl alcohol, N-propyl alcohol and mixtures thereof.

A more detailed description of the inks suitable for use with the present invention is presented in the U.S. Patent Application Serial Number 08 / 171,309, filed December 20, 1993, which is assigned to the attorney in charge. the present invention, the content thereof is incorporated herein by reference.

Various flexographic printing processes can be used with the present invention, and two of these designs include the design of the central printing cylinder and the stylish stacking design.

The types of plates that can be used with the flexographic process include plates identified as DuPont Cyrel® HL, PQS, HOS, PLS, and LP, which can be obtained commercially from E.I. DuPont de Nemours & Company, Inc., of Wilmington, Delaware. Other suitable plates can be obtained commercially from BASF of Clifton, New Jersey, and W.R. Grace & Company of Atlanta, Georgia.

Although flexographic printing is desired, other printing apparatuses or combinations of these are also contemplated in the present invention. These other printing apparatuses include screen printing, gravure printing in which the engraved print roller is used and ink jet printing, in which the nozzles spray the ink drop by drop, which are selectively deflected by means of an electrostatic charge to form the desired pattern on the substrate. It is desirable that the inks used with this apparatus have a viscosity equal to or less than about 10 centipoise.

The one-step, dual-substrate printing process of the present invention is a process that continuously prints substrates of low basic weight. A feature of the present invention is that another substrate, which also requires printing of the ink patterns, serves as a "backing" material to substantially eliminate the accumulation of ink in the printing apparatus. Therefore, by eliminating the accumulation of ink in the apparatus, the present invention improves the quality of the printing pattern and reduces the manufacturing costs.

Referring to Figure 3, a continuous supply of a moving substrate 28 of a first unwind 30 is provided on the guide rollers 32, 34 to the steering section 36. The steering section 36 maintains proper lateral alignment of the substrate 28. with a printing station 38, and more particularly with a central printing cylinder 40. Of the steering section 35, the substrate passes close to a roller with clamping pressure 42 clamped or keeps the substrate 28 in contact with the surface 44 of the Central printing cylinder that turns 40.

After passing through the printing station 38, the substrate 28 continues to a tunnel 48 and on top of a series of steering rollers 90, 92, 94, 96, 98. In the tunnel 48, the substrate 28 is subjected to a suitable temperature and air flow to dry the substrate and the ink therein.

Alternatively or additionally, tunnel 48 may also be a radiation curing unit that is used in conjunction with radiation curable inks. Examples of radiation curing methods include ultraviolet cure, electron beam cure, infrared cure and the like.

After leaving the first tunnel 48, the substrate 28 continues through a pair of cooling rollers 100, 102, which cool in substrate 28 to reduce the temperature of the substrate at room temperature.

Then, the substrate 28 passes through a series of guide rollers 104 to a primary winding 106 which rerolls the surface 28 for subsequent transportation and handling.

Referring to Figure 5, the substrate is illustrated with an ink pattern 84 printed thereon. In contrast to the ink pattern 18 (Figure 2) with its visually perceptible ink accumulations 22. the present invention provides an ink pattern free of visually perceptible ink accumulations.

Depending on the ink used for printing in an ink pattern, and the material from which the substrate 28 is made, the transfer of the ink 88 (FIG. 4) into a single pass portion 46 may or may not be visually discernible to the ink. simple sight However, if the transfer of the ink 88 is visually perceived in a one-step portion 46, the compensating roller section 64 (FIG. 3) may record that the ink pattern has traversed through the single-pass portion 46. with an ink pattern 84 which will be printed directly on the portion 46 as it proceeds a second time through the printing station 38 as a double-pass portion 78. A handover of ink 88, together with its color or colors, it matches the directly printed ink pattern 84. By recording an ink transfer 88, the clarity and definition of the ink pattern 84 is preserved, and the undesirable ghost images are practically eliminated in non-printed areas.

As described above, the substrate 28 may be woven or nonwoven fabric, and desirably may be a polyolefin base network. Polyolefin-based nets include, but are not limited to, woven materials, nonwovens, fabrics, porous films employing polyolefin base polymers. Examples of these polyolefins are polypropylene and polyethylene, including low density polyethylene, high density and low linear density.

However, it should be appreciated that the present invention is not limited to these types of polyolefins, but covers all types of polymers, copolymers and natural fibers. In woven material applications, these materials can be made into continuous fibers, which in turn are woven into a fabric. In non-woven applications, the fibers may be long, generally continuous fibers, such as fibers for non-woven fabrics made of fused filaments, or may be fibers of shorter length, such as those commonly used in carded networks . The fibers can also be melted to form the desired network. These polymers and copolymers can be extruded, melted, or blown into films for subsequent use in accordance with the present invention, including air screening, wet screening, a solution for spun fiber networks, or the like.

The fibers that are used according to the present invention can be "straight" fibers in that they have the same general polymer or a copolymer composition through. The fibers may also be multipolymer or multicomponent fibers, for example, bicomponent fibers in which at least one component is a polyolefin, such as a polyolefin coating and a polypropylene core fiber or a polyethylene coating and a core fiber Of polyester. Additionally, to the coating or core fiber configurations, other examples of desired fiber cross-sections are the side-by-side, sea-in-island and eccentric fiber configurations. In addition, fibers with a non-circular cross-section such as "Y" and "X" can be used.

The fibers and / or the networks may have other components and / or treatments. For example, adhesives, waxes, flow modifiers, processing aids and other additives that can be used during the formation of fibers or networks. In addition, pigments can be added to the fibers to change the color and other additives can be incorporated into the compositions for making fibers or elastic webs. Finally, mixtures of fibers, as well as one-component or two-component fibers can be combined to form woven or non-woven networks suitable for use with the present invention.

The printed substrate can be used by itself, or in a multiple layer configuration such as a sheet of one or more films and / or woven or non-woven layers. Examples of these multiple layer configurations include film / non-woven laminates, or non-woven / non-woven laminates such as spunbond / spin-cast / spin-layered three-layer laminate. By using the multilayer configurations, a variety of properties can be imparted to the laminate including permeability or impermeability.

When a nonwoven is formed, such as fibrous webs of non-woven polyolefin, the size of the fiber and the basic weight of the material may vary according to the particular use. In personal care products and medical fabrics, the typical size of the fiber will vary from about 0.1 to about 10 denier.

While the present invention was described as having a preferred embodiment, it will be understood that it is capable of further modifications. Therefore, it is intended that this application covers any variations, equivalents, uses or adaptations of the invention followed by the general principles thereof, and including variations of the present that result or may result from the known and customary practice in the technique, to which the invention belongs and falls within the limits of the appended claims.

Claims (15)

CLAIMS 1. A process of repeated step printing, and simple substrate, comprising: provide a constantly moving substrate, passing once a portion of a substrate that is constantly moving through a printing station without printing directly on it, re-passing the portion of the substrate that moves constantly through the printing station and again another portion of the substrate that moves constantly, which is a simple step through the printing station, and
1. Print the ink on the portion of the substrate that is constantly moving what is to repeatedly pass through the print station.
2. 2. The process, as claimed in clause 1, characterized in that it also comprises collecting in the single pass portion the ink passing through the repeated step portion.
3. 3. The process, as claimed in clause 1 or 2, characterized in that it also comprises recording the repeated step portion and the single pass portion.
4. 4. The process, as claimed in any of the previous clauses, characterized in that it also comprises the lateral alignment of the substrate in constant movement with the printing station.
5. 5. The process, as claimed in any of the preceding clauses, characterized in that it also comprises drying the substrates.
6. 6. The process, as claimed in any of the preceding clauses, characterized in that it also comprises the cooling of the substrates.
7. 7. The process, as claimed in any of the preceding clauses, characterized in that it also comprises radiation curing of the substrates.
8. 8. The process, as claimed in any of the previous clauses, characterized in that the printing is a flexographic printing.
9. 9. The process, as claimed in any of the previous clauses, characterized in that the printing is a rotofotogravure printing.
10. 10. The process, as claimed in any of the preceding clauses, characterized in that the printing is an inkjet print.
11. 11. The process, as claimed in any of the previous clauses, characterized in that the substrate has a basic weight equal to or less than about 20 grams per square meter.
12. 12. The process, as claimed in any of the previous clauses, characterized in that the substrate is a nonwoven fibrous network.
13. 13. A printed substrate, comprising: a substrate comprising a pair of opposing surfaces, and an ink pattern directly printed on surfaces by repeated step printing.
14. 14. The substrate, as claimed in clause 13, characterized in that the substrate has a basic weight equal to or less than about 20 grams per square meter.
15. 15. A printed substrate, as specifically claimed in clause 13 or 14, characterized in that it is obtained by means of the process according to any of claims 1 to 12.