MXPA97001952A - Constructions of adhesives sensitive to pressure without apresta - Google Patents

Abstract

The present invention relates to a removable, pressure-sensitive adhesive construction characterized in that it comprises: (a) a backing, (b) a permanent, pressure-sensitive adhesive layer in direct contact with a backing surface, (c) a removable, pressure sensitive adhesive layer in direct contact with the permanent pressure sensitive adhesive layer; and (d) a release surface in direct contact with the pressure sensitive adhesive layer, removable, the removable pressure-sensitive adhesive is present at a coating weight of at least about 50% by weight of the total coating weight, and in which the weight ratio of the pressure-sensitive adhesive coating, removable to the adhesive pressure sensitive, permanent, is at least 1: 1, and the combination of the adhesive layers have a total coating weight of approximately 18 to 25 g

Description

CONSTRUCTIONS OF ADHESIVES SENSITIVE TO PRESSURE, WITHOUT APRESTOR FIELD OF THE INVENTION The invention relates to tape constructions and labeling of pressure-sensitive, removable adhesives.

BACKGROUND OF THE INVENTION A pressure sensitive adhesive label construction comprises a laminate product of a seat or backing material, a layer of a pressure sensitive adhesive and a release liner that provides a release surface for the pressure sensitive adhesive. In tape constructions, a release is applied to the side of the seat or backing material opposite the side in contact with the pressure sensitive adhesive, to provide the release surface which allows the seat material and the adhesive sensitive to the pressure is released from an adjoining layer of seat material and adhesive. REF: 24356 Pressure sensitive adhesives (PSA) fall into one of two categories: permanent and removable. Permanent pressure sensitive adhesives are adhesives that have a level of adhesion that does not allow the removal of the label from the substrate to which it has been applied without considerable damage to the paper seating material such as ripping, or for materials of stronger seat such as polyester, the failure of the adhesive in the seat material, the cohesive failure in the body of the adhesive or leaving, by transfer, a significant amount of adhesive in the substrate. The adhesion of the removable pressure sensitive adhesives is considerably lower, allowing the removal of the seat material or label with adhesive from the substrate even after a prolonged period of contact. The removal is without significant damage to the seat or backing material. Typically, a reusable pressure-sensitive adhesive will have a bond of about 50 to about 300 N / m to stainless steel.

The limitation in the use of removable, pressure-sensitive adhesives for tape and label constructions is that a primer or primer is necessary to allow proper attachment to the seat material and, for some pressure sensitive adhesives, removable , to prevent fouling of paper seating materials. Traditionally, the primer has been deposited as a barrier coating from a solution of a polymer in an organic solvent such as toluene. Both styrenic and ethylene-vinyl acetate polymers have been used, both filled and unfilled. However, environmental considerations have led to a reduction in the amount of solvent used in the industry. Aqueous emulsifiers have been tried for the seat material, as replacements, but impart a ripple to the paper seat material. The ripple can be removed by rewetting the paper but at an additional cost. In addition, many papers have a glossy surface and rewetting reduces gloss and adversely affects the quality of the product. This is not acceptable in the industry. In addition, many machines that apply coatings do not have a dressing station on the dresser or an oven to dry the dresser coating. Therefore, it would be desirable to provide an alternative route to the provision of removable, pressure-sensitive adhesive constructions that did not involve the use of solvent-based primer systems. Both dual and multiple die coatings on substrates are well known in the art, and are described for example in U.S. Patent No. 3,573,965 incorporated herein by reference. US Patent No. 4,260,659 to Gobran, incorporated herein by reference, discloses a multi-layered, pressure-sensitive adhesive tape formed of a plurality of layers of pressure-sensitive adhesive, superimposed, the outer layers of which which are significantly softer than the immediately underlying extracts.

U.S. Patent No. 4,854,259 to Kuller, incorporated herein by reference, discloses a process for producing a pressure-sensitive adhesive tape, comprising a plurality of overlapping, concurrently coated layers, at least one outer layer of which is a layer of pressure-sensitive adhesive, with adjacent layers defining an inner phase therebetween, each layer comprising a photopolymerized matrix of polymer chains extending from the matrix of a layer through the interface to the matrix of an adjacent layer. As a consequence of the same, the layers can not be delaminated. The current method of manufacturing a removable, pressure sensitive adhesive label material is depicted in Figure 1. With reference thereto, a backing or continuous backing material is coated with a primer from a solvent and dried in an oven to form a continuous backing paper, sized. Contemporaneously, a release liner paper is coated with a removable, pressure sensitive adhesive that dries in the oven. The laminated product of the pressure-sensitive, removable adhesive and the release liner is combined with the seating material, sizing, formed, to form a final laminate of seat material, primer, pressure sensitive adhesive, removable and liner of liberation. It is also feasible to apply the removable PSA directly to the dresser and laminate this sub-assembly to the release liner. For tape constructions, the release liner is removed and a release agent is applied to the surface of the backing opposite the surface in contact with the removable, pressure sensitive adhesive. This is a multi-step and expensive process and it would be desirable to make the construction of the pressure sensitive adhesive product removable in a less costly manner without compromising the performance of the removable pressure sensitive adhesive. This is the object of the present invention.

BRIEF DESCRIPTION OF THE INVENTION It has now been found that in tape and label constructions based on the use of removable pressure-sensitive adhesives can be formed by the use of a permanent pressure-sensitive adhesive instead of the primer as a support and a layer of adhesive. barrier to ensure a layer of pressure sensitive adhesive, removable to a backing. The combination can also be used to adjust adhesion at any level between the adhesion of the permanent pressure sensitive adhesive and the removable pressure sensitive adhesive. The construction comprises a continuous backing paper or seat material in contact with a layer of a permanent pressure sensitive adhesive which in turn is in contact with a layer of a removable, pressure sensitive adhesive. The removable pressure-sensitive adhesive is in turn in contact with either a release liner release surface or a release surface on the opposite surface of the backing. In order to maintain the pressure sensitive, removable properties, it is necessary to limit the relative, used amount of the permanent pressure sensitive adhesive. For a typical total weight of pressure sensitive adhesive coating of 18-25 grams per square meter (gmc, herein), the coating weight of the removable, pressure-sensitive adhesive coating is at least about 50% of the weight of the adhesive. gmc and the coating weight ratio of the pressure-sensitive adhesive layer, removable to the permanent pressure-sensitive adhesive layer, is at least about 1: 1, more preferably about 3: 1, in the form even more preferred 4: 1 or more. At higher coating weight levels of the permanent adhesive, for example, about 50% of the coating thickness, the adhesiveness is close to that of the pressure sensitive adhesive., permanent. The layers of pressure-sensitive, removable and permanent adhesives are quickly applied to a continuous paper of seat material by co-extrusion from a dual die of the permanent, removable and permanent pressure sensitive adhesives, respectively, from emulsions. in the release liner or backing, drying the layers and laminating the sub-construction to a backing or release surface. The simultaneous, dual layer coating eliminates many steps of operation and significantly reduces the cost of construction of the tape and sheet material. The total thickness of the coating and the thicknesses of each layer are controlled by dosing the amount of pressure sensitive adhesives, permanent and removable, respectively discharged from each hole of the dual die.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 appended shows, in a block diagram, the current method of manufacturing a removable, pressure-sensitive adhesive label material construction; Figure 2 illustrates, in a block diagram, the method of manufacturing a removable, pressure-sensitive adhesive label material construction according to the present invention; Figure 3 is a schematic diagram of a dual die used to apply the adhesive formulations of the present invention.

Figure 4 is a schematic cross-sectional view showing the edge structure of the dual die of Figure 3 as it is applying two layers of adhesive.

Figure 5 is a schematic cross-sectional view showing an angled edge structure of the dual die as two layers of adhesive are applied.

Figure 6 is a schematic cross-sectional view of a dual die incorporating a beveled edge structure.

Figure 7 shows the rapid adhesiveness to glass, high density polyethylene (HDPE) and recycled cardboard using the compositions of the present invention and controls from 1 to 5; Figures 8, 9, 10, 11 and 12 show adhesion in the 90 ° release to vellum, glass, high density polyethylene (HDPE), cardboard and polyvinyl chloride (PVC) as a function of time for the compositions of the invention as compared to the controls from 1 to 5; Figures 13 and 14 show, respectively, the 90 ° peel and tackiness values in the stainless steel curl as a function of the relative weight of the coating compared to a commercial product that is Control 9.

Figure 15 shows 90 ° adhesion to steel for the composition of Example 4 and Control 9 as a function of time.

Figure 16 is another graph of the information as it is contained in Figure 15.

DETAILED DESCRIPTION The present invention relates to tape and label constructions employing removable, pressure-sensitive adhesives in which the removable, pressure-sensitive adhesive layer adheres to a permanent, pressure-sensitive adhesive layer that at its Adhere to the seat or backing material. The pressure sensitive adhesive constructions of the invention, when they are for label applications, are preferably prepared, with reference to Figure 2, by coating layers of pressure sensitive adhesive (PSA), removable and permanent, in a liner. of silicone release using a dual die. The adhesives contemplated for use are pressure sensitive, emulsion adhesives and are simultaneously pumped through adjacent holes in the dual die and coated on the release liner. However, the principle applies to solvent-based and hot-melt adhesives, the latter employing cooling of the melt instead of drying to harden the layers of pressure-sensitive adhesive. As shown, the laminate product of release liner, pressure sensitive adhesive, removable and permanent pressure sensitive adhesive is then passed, if necessary, through an oven to dry the applied layers. The temperature is approximately 82.2 ° C (180 ° F). After drying, the laminated release liner, pressure sensitive adhesive, removable and permanent pressure sensitive adhesive is laminated to a continuous paper of seat or backing material.

As long as it is not shown, if the release liner is removed, as in the case of tape making, then the layers of the permanent pressure sensitive adhesive and the removable pressure sensitive adhesive are coated with dual die one side of a continuous paper to be cut into strips and the inverted side is coated with a suitable release material to provide a release surface. The rolled product, formed of paper, sensitive adhesive, permanent and pressure sensitive adhesive, removable then rolled into a roll to be cut into tapes. The construction made in accordance with Figure 2 is normally processed and cut into labels with or without removal of the matrix. It will further be appreciated that the entire process of Figure 2 can be reversed and the layers of the pressure-sensitive, removable and permanent adhesive could be applied by a dual die directly to the seat material, the adhesive layer hardens by drying or cooling and then it is laminated to the release liner. Both the pressure sensitive, removable, emulsion adhesive and permanent pressure, emulsion adhesive used in the practice of the invention should be of sufficient viscosity such that the dual-forming layers of the adhesive sensitive to the pressure, removable and permanent will not spread significantly in their entrecaras. This ensures that the properties of the permanent pressure sensitive adhesive will not adversely impact, unless desired, the properties of the removable, pressure sensitive adhesive. However, it must be mutually compatible to allow the co-formation of discrete layers that will not delaminate. In general, to achieve a removable, pressure-sensitive adhesive, the coating weights of the permanent and removable pressure-sensitive adhesive layer combination will be from about 18 to about 25, preferably from about 20 to about 23. gmc, with at least 50% of the coating weight which is the removable pressure-sensitive adhesive. However, it is preferred that the relative weights of gmc coating of the permanently removable pressure sensitive adhesive be at least about 1: 1, preferably about 3: 1 and more preferably about 4: 1 or plus. This allows the use of the least amount of permanent pressure-sensitive adhesive and provides a pressure-sensitive adhesive liner, removable in contact with the pressure-sensitive adhesive coating, permanent with minimal influence of the adhesive sensitive to the pressure, permanent in the properties of pressure sensitive adhesive, removable. In the thicknesses of the permanent pressure sensitive adhesive, above 50% of the total thickness, the influence of the permanent pressure sensitive adhesive becomes significant and the level of adhesion increases significantly. This effectively allows the use of relative thicknesses of removable and permanent adhesives, to control adhesion to substrates. The pressure sensitive adhesives employed in the present invention can be any permanent, removable pressure sensitive adhesive of acrylic resin or rubber, in emulsion, which are sufficiently compatible to form two discrete layers with minimal diffusion between the layers. It is preferred in the present to employ emulsion-based pressure sensitive adhesives.

In construction, the permanent pressure sensitive adhesive will have sufficient aggression to the seat material to preferentially attach the pressure sensitive adhesive, removable to the seat material as opposed to allowing the transfer of adhesive to the normal substrates. These include paper, recyclable cardboard, polyolefins, polyvinyl chloride, glass, stainless steel, painted surfaces and the like. In addition, the permanent pressure-sensitive adhesive layer serves to aggressively fix the pressure-sensitive adhesive, removable to the backing, and when the backing is paper, it provides a barrier that prevents fouling of the paper. The use of a permanent, continuous, pressure-sensitive adhesive layer interspersed between the removable, adjoining pressure-sensitive adhesive layer and the seat material can be used to make a variety of constructions. For example, the permanent pressure sensitive adhesive layer may be a pressure sensitive adhesive, which can be pulped again and the removable pressure sensitive adhesive layer can be pulped again or pulp can not be made again. In any case, using a layer of pressure sensitive adhesive, permanent, which can be pulped again can allow the separation of a paper seating material as part of the recovery of the material. More significantly, the permanent pressure sensitive adhesive can be adapted to the nature of the seat material while the removable can be selectively adapted to the nature of the substrate to which the construction is designed to be applied. Preferred preferred removable pressure sensitive adhesive compositions comprise acrylic based emulsion polymers which exhibit low adhesion on release, preferably in the order of about 50 to about 300 N / m in stainless steel. The acrylic-based emulsion polymers for the removable and permanent pressure-sensitive adhesive comprise from about 75 to about 98% by weight of acrylic acrylate monomers, preferably about 85 to about 98% by weight. The amounts of alkyl acrylate monomers below 85% are not presently preferred except as part of a pressure sensitive adhesive, which can be pulped again, because the glass transition temperature resulting from the adhesive can be too high and adhesion loses stickiness. Polymers having more than about 98% alkyl acrylate monomers are not preferred because the polymers tend to exhibit insufficient cohesive strength and leave stains or debris when released from the substrates. Amounts from 85% to about 98% by weight of alkyl acrylate monomers are presently preferred for removable, pressure sensitive adhesives. The alkyl acrylate monomers preferably contain from 1 to 12 carbon atoms in the alkyl chain and more preferably the alkyl acrylate monomers contain from about 4 to about 8 carbon atoms in the alkyl chain. Diesters of alpha, beta-unsaturated dicarboxylic acids can also be used beneficially, especially for permanent, pressure-sensitive adhesives.

For the removal capacity, polymers with at least the majority of the alkyl acrylic monomers having from about 4 to about 8 carbon atoms in the alkyl chain are preferred herein since they provide the optimum balance of hardness, adhesion and removal capacity. Exemplary alkyl acrylates, suitable for use in the present invention, include 2-ethylhexyl acrylate, butyl acrylate, heptyl acrylate, octyl acrylate, isooctyl acrylate., isobutyl acrylate and the like. Butyl acrylate and 2-ethylhexyl acrylate are preferred herein. Up to about 15% of the monomers that make up the polymer can be hard monomers. Preferred hard monomers include vinyl acetate, styrene, vinyl methacrylate, vinylpyrrolidone and the like. The polymer composition may comprise up to about 25% of a polar monomer or mixtures of polar monomers to impart mechanical stability and cohesive strength or ability to pulp the polymer again. By the term "polar" monomer is meant organic carboxylic acids, amides and alcohols and the like. Examples of polar monomers include methacrylic acid, acrylic acid, itaconic acid, maleic acid, acrylamide, ethacrylamide, 2-hydroxyethyl acrylate, and the like. The polymer may comprise up to about 1% by weight of an internal crosslinking agent. The term "internal crosslinking agent" is intended to include polyfunctional compounds having at least two carbon-carbon double bonds, not conjugated per molecule, agent which becomes part of the polymer during polymerization. It has been found that the amount of the internal crosslinking agents should not exceed about 1%, since amounts greater than 1% tend to reduce the stability of the acrylate-based emulsion from which the polymers are prepared. This results in the coagulation of the emulsion particles during the preparation. An amount of the internal crosslinking agent above about 0.3% is not preferred since an additional benefit is typically not observed. Examples of suitable internal crosslinking agents include diallyl maleate, diallyl phthalate and multifunctional acrylates and methacrylates including polyethylene glycol diacrylate, hexanediol diacrylate, ethoxylated trimethylolpropane triacrylate, pentaerythritol triacrylate, and propylene glycol acrylate and trimethylolpropane trimethacrylate and Similar. The polymer systems may further comprise an external crosslinking agent that causes crosslinking after the polymerization in an amount of up to about 2% by weight, and preferably from about 0.1 to about 0.7% by weight. External crosslinking agents include metal salts such as zirconium ammonium carbonate, zinc ammonium carbonate, aluminum acetate, zinc acetate and chromium acetate. The amounts of the external crosslinking agent greater than about 2% are not generally employed due to the undesirable loss of adhesion. The acrylic, removable, pressure sensitive adhesives preferred herein are adhesives containing adhesive polymers formed from a mixture of about 98% by weight of 2-ethylhexyl acrylate or isooctyl acrylate and about 2% by weight of carboxylic acids in particular, acrylic and methacrylic acids. Permanent pressure-sensitive adhesives that serve as a fixing agent between the removable pressure-sensitive adhesive layer and the backing or seat material are preferably high-performance, acrylic-based, pressure-sensitive adhesive that they contain larger amounts of polar monomers. Aggressiveness can also be improved by the use of a tackifier. Some of these pressure sensitive adhesives are described in US Patent No. 5,164,444 incorporated herein by reference and generally containing from about 35 to 60% by weight of at least one alkyl acrylate, from about 15 to 35%. of at least one vinyl ester, from about 20 to 40% by weight of a diester of a dicarboxylic acid, preferably di-2-octyl maleate, or di-2-ethylhexyl fumarate and about 3% by weight weight of unsaturated carboxylic acid. The preferred manufacturing method in the present uses a dual or multilayer die 10 such as that illustrated in Figure 3 for the application of two layers of adhesives., contiguous, that is, removable and permanent, to the release surface of a continuous paper of a release liner substrate 12. The web 12 travels around a support roller 14 as it passes the distal end 10 of the multilayer die 10. As shown in Figure 3, it will be understood that both the die 10 and the continuous paper 12 have a substantially equal width such that the entire width of the substrate is coated in one pass by the fluid flowing out of the die 10 and over the continuous paper 12. In this case, two separate fluid layers of the manifolds 16 formed in the die and along the individual slots 20 that are defined by the surfaces 22 distant from the die are flowing out. The slots 20 each communicate with the interface between the continuous paper 12 and the tips 18 further from the die 10. These tips are referred to as the "die tips" 18 and are illustrated and described in more detail in conjunction with Figure 4 later. The multilayer die 10 is modular, thus allowing variations in the individual slots 20 and the edge configurations 18 without the need for modifications to the other slots and edges. In this way, these geometries can be adjusted in order to achieve successful lining. Other variables include the "coating separation" (e.g.,), and the "angle of attack" (a) of the die. As illustrated in Figure 3, the coating separation is the distance that the edges 18 are delayed from the web. The angle of attack (a) is the angle of the angular adjustment of the surfaces of the edges and of the complete die with respect to the normal external stress of the continuous paper as illustrated in Figure 5. Another variable is the speed of the continuous paper that can be vary between approximately 0.304-304 meters (5-1,000) feet per minute, and more. Any of the two die coating methods can be used. Coating with interference or coating by proximity. In the previous case, the edges 18 of the die are actually pressed forward in the direction of continuous paper 12, but do not make contact with the continuous paper, nor therefore, cause damage to it, because they slide as hydrofoil in a thin layer of adhesive coating material. However, the pressure can actually cause the support roller 14 (typically constructed from a hard rubber material) is deformed so as to release the die pressure against the edges 18. In the proximity coating, the edges 18 of the die 10 are placed at a precise distance from the continuous paper 12. and do not press forward towards the continuous paper. The support roller 14 is typically constructed of stainless steel which allows precision in the circumference of the roller and minimizes roll malfunction. In the coating process, very thin layers of high viscosity emulsion adhesive compositions are coated at relatively high web speeds. The process is carefully controlled. This control is achieved in the present multilayer die coating technique, in part by the geometry and configuration of die edges 18. With reference to Figure 4, a close-up view of the tips 22 further away from the multilayer die of Figure 3 is shown, which includes the edges 18 associated with each slot, showing the interface or separation of coating with respect to to the continuous paper 12. With respect to Figure 4, it should be noted that, for ease of illustration, the die 10 is shown rotated 90 ° from the position shown in Figure 3. In addition, the continuous paper 12 is shown in an arrangement horizontal, when in fact, it may be in a slight curvature to the continuous paper 12 and the support roll 14; however, the distances involved are thus short, so that a good approximation of the fluid dynamics can be achieved by assuming a horizontal continuous paper 12. By consistent reference, the individual edges 18 of the multilayer die 10 should be referenced with respect to the direction of travel of the continuous paper 12. For example, the edge 18a shown to the left of Figure 4 will be referred to as the "running edge". above ", while the 18c edge to the right should be referred to as the" downstream edge ". In this way, the "intermediate edge" 18b will have that same reference. Accordingly, the upstream and intermediate edges 18a, 18b define an upstream feed gap 24 through which an emulsion adhesive material 26 flows over the web 12 to form a layer 28 of pressure sensitive adhesive, removable, from the bottom, of a multilayer adhesive product. Similarly, the intermediate edge 18b and the downstream edge 18c together form a slotted feed gap 30 through which the emulsion adhesive material 32 flows at the top of the lower layer 28 as the web travels in one direction from left to right as illustrated in Figure 4. This forms a layer 34 of permanent pressure-sensitive adhesive from the top of the multilayer product. Again, for ease of illustration, layer 34 of the upper part is shown as a colored, darkened material, but this may not necessarily be the case in actual production; for example, various colors or labels can be used such as fluorescent dye, ultraviolet, to facilitate the measurement of the thicknesses of the individual layer. The coating of the viscous adhesives at these web speeds can comprise a number of problems. For example, recirculations in the flow of both the bottom and top adhesive layers can result in certain defects in the multilayer final product. These recirculations can occur, if the point of separation of either the liquid adhesive with respect to the edges 18 of the die occurs in an inappropriate location. In addition, the extreme pressure gradient results in upstream leakage of liquid to the area of the coating gap, again causing defects in the final product due to non-uniform thicknesses of the adhesive layer, etc. further, these and other bad effects result in the diffusion of one layer in the other, since they are being coated simultaneously in the liquid state. This diffusion compromises the integrity and performance of the resulting product. In this way, it has been found, with respect to the multilayer die coating described herein, that it is very important to control the pressure gradients of the adhesives under each edge. In particular, the top layer should be separated from the intermediate edge at the corner downstream of this edge. In order to achieve this coating control, it is pointed out from FIG. 4 that the edge 18 of each die section is staggered or separated from the continuous paper 12 in the downstream direction. This allows the edges to generate the proper pressure gradient and ensure a smooth flow of adhesive and uniform layer thicknesses. The adjustment of a number of run parameters are necessary in order to achieve this goal. For example, the coating separations at the edges 18b and 18c should be approximately in the range of 1 to 3 times the thicknesses of the composite wet film of the layers fed from upstream of the edge. Under the upstream edge 18a, the net flow velocity is necessarily zero, and a turn around the flow is the only possibility. In this way, the coating separation under this edge is adjusted only in order to prevent leakage of liquid outwardly from the coating gap in the upstream direction. In addition, the upstream step, defined as dimension A in Figure 4, and the downstream step, defined as dimension B, may vary anywhere from 0 to approximately 0.106 mm (4 mils (0.004 in)). Feed separations (defined as dimensions C and D in Figure 4) can also be adjusted anywhere from approximately 0.1016 mm (1 mil) to approximately 0.381 mm (15 mil) (OR d01 inch to 0.015 inch )), preferably not exceeding five times the thickness of the wet film of their corresponding layers. In addition, the length of the edges 18 in the direction of web travel plays an important role in achieving the proper pressure gradient. In this manner, the upstream edge 18a should be approximately 2 millimeters in length, or more, as necessary to seal the head as noted above. The downstream edge 18c and the intermediate edge 18b can fall within the range 0.1-3 mm in length. It will be recognized that one skilled in the art can adjust these various parameters in order to achieve the proper dynamics of the fluid for the uniform coating of the layers. Of course, people of more skill in the art can adjust the parameters of the die and the run in a more precise way, in order to achieve good results. However, these people are not always easily available among production teams. Therefore, it is advantageous to provide a die geometry that will increase the window size of the multilayer coating operation, successful. This can be achieved by certain adjustments in the orientation of the edges of the die. In this way, Figure 5 illustrates the die 10 of Figure 4 rotated slightly in the clockwise direction, representing an "angle of attack a". By consistent reference, the angle of attack (a) shown in Figure 4 represents a negative angle of attack, or a convergent orientation of the downstream edge 18c with respect to the continuous paper 12. This converging edge orientation provides a negative pressure gradient. (in the direction of travel of the web), along the downstream edge 18c, which is beneficial in the prevention of a coating defect well-known as "ripple", a design for regular striations in the sense of Continuous paper trip in the movie. The fact that the intermediate and upstream edges 18a and 18c also achieve a convergent orientation is not particularly beneficial. Although the angle of attack of the die can be varied widely, in order to achieve these advantages, it has been found at angles in the range of 0o to -5o are appropriate. A successful, additional, uniform operation window can be achieved with additional modifications to the edges. A variation of the edge configuration of Figure 5 illustrating "beveled" edges is shown in Figure 6. In this configuration, the downstream edge 18c is angled or bevelled to have a convergent profile, similar to that shown in Figure 5. However, the intermediate edge 18b is positioned to be flat or parallel with respect to the continuous paper 12. The upstream edge 18a, on the one hand, is bevelled so that it is divergent from the web 12 in the downstream direction. Again, this configuration provides the proper pressure gradient under the individual edges to prevent recirculation and upstream leakage. In addition, if disturbances occur in the coating conditions, (such as due to roll malfunction, foreign objects in the web, variations in ambient pressure), the convergent configuration of the upstream edge 18a shown in the FIG. 6 will produce a damping effect in the flow conditions, so that defects in the coating layers will not occur. In this way, the multilayer coating drop acts as a non-linear spring to dampen unwanted events in order to return to the safe state. The die 10 can then be adjusted according to the normal variations of the angle of attack, to achieve favorable coating conditions. Because the edges 18 are biased or beveled in a favorable orientation, adjustment of the angle of attack as well as coating separation is not as accurate. In this way, persons skilled in the art or even less skilled can successfully achieve good coating results. In the following examples and controls, Rl is a removable, pressure sensitive adhesive deposited from a high viscosity emulsion of an acrylic copolymer formed of 98% by weight of 2-ethyl hexylacrylate and 2% by weight of a mixture of acrylic and methacrylic acid. The emulsion uses an anionic surfactant. The solids content is 66 to 65% and the emulsion is thickened with an organic thickener. R-2 is the same emulsion as R-1 but without the thickener. R-3 is an 61-63% solids emulsion of a plasticized copolymer of 98% 2-ethyl hexyl acrylate and 2% by weight of a mixture of acrylic and methacrylic acids. P-1 is an emulsion copolymer, acrylic, enhanced in tack, formed in the presence of an anionic surfactant. P-2 is an emulsion polymer formed from 2-ethylhexyl acrylate / di-2-octyl maleate / vinyl acetate / acrylic acid / methacrylic acid in a relative weight ratio of 48/29/21 / 1.5 / 0.5 and formed in the presence of dodecyl mercaptan. The basic tests were carried out in the evaluation of the performance of the adhesive, the fast adhesion and the adhesion in the detachment at 90 °. The rapid tackiness was carried out according to the FINAT No. 9 test method (FTM 9), and the adhesion on the 90 ° release according to the FINAT No. 2 test method (FTM 2). The FTM 9 measures the tackiness of a pressure sensitive adhesive and allows the comparison of the "initial grip" or "stickiness of application" of the adhesives. The value of fast adhesiveness is expressed as the force in Newtons per meter (N / M) required to separate, at a specific speed, a curl of material with adhesive that gives out, which has been put in contact with a specific area of a standard or test surface. Using a tension tester, a curl of a sample approximately 25 mm wide was lowered to be immediately removed from the test surface. The speed is 300 mm per minute. The contact area is approximately 25 mm by 25 mm. The FTM 2 also uses a 25 mm wide sample. Its adhesive coating surface is applied to a selected test surface with light finger pressure and wound with a FINAT test roller, normal, to obtain optimum contact between the mass of the adhesive and the surface of the substrate. After a predetermined period of time, recorded, the test strip is detached from the surface at an angle of 90 ° to the surface at a speed of 300 mm per minute reported in Newtons per meter. Both tests are carried out at a temperature of 23 ° ± 2 ° C and a relative humidity of 50% ± 5% RH.

Examples 1 and 2 and Controls from 1 to 5 An emulsion of a permanent pressure sensitive pressure sensitive adhesive, and removable, pressure-sensitive adhesive emulsions, Rl and R-2, were provided for evaluation purposes of the invention. The adhesives were formed on board using a dual die. and dried to form a rolled vellum product, permanent pressure sensitive adhesive, and removable pressure sensitive adhesive. These rolled products are Example 1 (Ex-1) and the Example 2 (Ex-2). These constructions were compared to a removable, commercial construction (Control 1), two constructions in which R-2 was formed in a primed vellum (Controls 2 and 3), a construction where Rl was formed in an untapped vellum (Control 4). ) and one where R-2 was formed on an unfit vellum (Control 5). The coating weights for each construction are shown in Table 1.

TABLE 1-Coating Weight Developed by Square Meter (95 M) The performance and adhesion of the constructions were evaluated for fast adhesiveness to several substrates (Figure 7), 90 ° adhesion to vellum (Figure 8), 90 ° adhesion to glass (Figure 9), 90 ° adhesion ° to high density polyethylene (Figure 10), adhesion to 90 ° to cardboard (Figure 11), and adhesion to 90 ° to polyvinyl chloride (PVC) (Figure 12). The removal capacity was evaluated under natural aging conditions (23 ° C) at a relative humidity of 50% with up to one month in several substrates). In vellum and cardboard, Figures 9 and 11, three of the constructions, controls 4 and 5 and Example 2 failed, with adhesive transfer occurring almost immediately after application (20 minutes). This occurs when the R-2 adhesive was coated without using a primer and when a laminated product of R-2 in P-1 was employed. In the glass, high density polyethylene and polyvinyl chloride, adhesive transfer was observed for the unstyled constructions (Cont. 4 and 5) after two weeks. The other constructions of R-l gave good removable properties. The best properties were given for the pre-prepared vellum base material for the dual die coated material prepared using R-1 in a thin layer (4 gmc) of P-1. The results of this study established that it was feasible to prepare a removable adhesive using a dual die coating system where the coating of the primer was replaced by a permanent, pressure-sensitive adhesive coating that was simultaneously deposited on the top of the adhesive pressure sensitive, removable, on a release surface and then transferred to the vellum. This is the construction of Examples 1 and 2. It also became clear that the R-2 adhesive gave unacceptable properties when it was coated without using a primer, and, when it was formed using a dual die with a permanent adhesive, it gave too much aggression in the adhesion as possibly due to some mixing of the permanent adhesive with the removable adhesive when it is formed with the dual die and possibly because the permanent adhesive achieves an effective thickness too high. The differences can also be attributed to the fact that the apparatus was different from that used to form the composition of Example 1. In any case, the study confirms that it was feasible to use a dual die technique to form a laminate product of a sensitive adhesive. pressure, permanent and a pressure sensitive adhesive, removable to obtain good bonding to a seat or backing material to preserve the properties of the removable pressure sensitive adhesive and its adhesive bond to a backrest.

Controls 6, 7, 8 and 9 and Examples 3 and 4 A study was made to show the effect of the weight ratios of the permanent pressure-sensitive adhesive coating on the removable pressure-sensitive adhesive, where the total weight of the coating was approximately 21 gmc. For evaluation purposes, a silicone-coated release liner manufactured and sold by Rhinelander was used as the release liner. With reference to Table 2, Control 6, for this purpose, was a construction where the only adhesive used was the permanent adhesive P-2. Control 7 was formed using a dual die but still at a low weight of removable, pressure-sensitive adhesive coating. The coating weight of the pressure sensitive, permanent adhesive to the pressure sensitive, removable adhesive was 14: 7. The thickness of the removable, pressure-sensitive adhesive was too low for the product to make a removable one, but this shows the ability to select adhesion by varying the relative coating weights of the pressure-sensitive adhesives, removable to permanent. For Control 8 only the permanent pressure sensitive adhesive was applied to the high gloss paper. Control 9 was a removable, pressure-sensitive adhesive coated with a removable dual die, commercially available in a high-gloss, sizing paper. Examples 3 and 4 provide the ratio of the R-3 adhesive coatings on the permanent P-2 applied to the high gloss paper to the relative coating weights of 10.5 to 10.5 gmc, and 17 to 4 gmc. Table 2 shows the values of detachment and curl to stainless steel. Figure 13 appended shows in a block diagram the relative adhesion of the constructions coated with dual die of control 7 and examples 3 and 4 and control 9 to stainless steel, the test being a 90 ° detachment for 10 minutes, while Figure 14 shows the tackiness of the curl for the same construction. It is clear that the construction closest to control 9 was that where the total level of the removable was 17 gmc and the permanent 4 me, that is, Example 4. Table 3 compares the detachment to 90 ° after 40 days of steel aging for the composition of Example 4 as compared to Control 9. The same data is also plotted in Figures 15 and 16. It is clear that in the construction of Example 4 it goes well with the construction of control 9. While the invention It has been illustrated in terms of an individual of a permanent pressure sensitive adhesive and a single layer of a removable pressure sensitive adhesive, it will be appreciated that any given layer can be a composite material of several layers or mixtures of polymers in emulsion while one acts effectively as a pressure sensitive, permanent adhesive and the other as a removable, pressure sensitive adhesive.

Table 2 - 10 Minute Release Test and Curl Tack Testing, Stainless Steel Substrate Table 3 It is noted that in relation to this date, the best method known by the applicant to carry out the present invention is that which is clear from the present description of the invention. Having described the invention as above, the content of the following is claimed as property:

Claims (24)

1. A removable, pressure-sensitive adhesive construction characterized in that it comprises: (a) a backing; (b) a layer of a permanent pressure sensitive adhesive in contact with a backing surface; (c) a layer of a pressure-sensitive adhesive, removable in contact with the permanent pressure-sensitive adhesive layer, and (d) a release surface in contact with the removable pressure-sensitive adhesive layer, the removable, pressure-sensitive adhesive that is present in a coating weight of at least about 50% by weight of the total weight of the coating and in which the weight ratio of the pressure-sensitive adhesive coating, removable to the sensitive adhesive At the pressure, permanent is at least 1: 1.

2. The construction according to claim 1, characterized in that the release surface is provided by a release liner.

3. A construction according to claim 1, characterized in that the release surface is provided on a backing surface opposite the surface in contact with the permanent pressure sensitive adhesive.

4. A construction according to claim 1, characterized in that the ratio of the coating weight of the removable pressure sensitive adhesive to the permanent pressure sensitive adhesive is at least about 3: 1.

5. A construction according to any one of claims 1 to 3, characterized in that the coating weight ratio of the pressure sensitive adhesive, removable to the permanent pressure sensitive adhesive is at least about 4: 1.

6. A construction according to any one of claims 1 to 5, characterized in that the layers of the permanent pressure sensitive adhesive and the removable pressure sensitive adhesive are layers of acrylic, co-deposited pressure-sensitive adhesives. .

7. A construction according to any of claims 1 to 5, characterized in that the layers of permanent pressure sensitive adhesive and removable pressure sensitive adhesive are layers of acrylic pressure sensitive adhesives co-deposited to from aqueous emulsions.

8. A method for the production of a removable pressure-sensitive adhesive construction, characterized in that it comprises: (a) depositing on a release surface provided by a support, from a dual die, a layer of an adhesive sensitive to the pressure, removable next to a layer of a pressure sensitive adhesive, permanent co-deposited in the layer of pressure-sensitive, removable adhesive; (b) hardening the layers of the permanent pressure sensitive adhesive and the pressure sensitive adhesive, removable on the support release surface; and (c) laminating to a backing construction the laminate formed from the permanent pressure sensitive adhesive of the removable pressure sensitive adhesive and the support providing the release surface, the pressure sensitive adhesive layer, removable that is applied to a coating weight of at least about 50% by weight of the total coating weight of the pressure sensitive adhesives and a coating weight ratio of the pressure sensitive adhesive, removable to the pressure sensitive adhesive , permanent of at least about 1: 1.

9. A method according to claim 8, characterized in that the support for the release surface is the backrest.

10. A method according to claim 8, characterized in that the support for the release surface is provided by a continuous release liner paper and in which the laminate product of the permanent pressure sensitive adhesive of the pressure sensitive adhesive , removable and release liner are laminated to a separate continuous backing paper.

11. A method according to any of claims 8 to 10, characterized in that the layer of permanent and removable pressure-sensitive adhesives is each deposited from an emulsion.

12. A method according to claim 11, characterized in that the permanent and removable pressure sensitive adhesives are each acrylic pressure sensitive adhesive.

13. A method for the production of a removable pressure-sensitive adhesive construction, characterized in that it comprises: (a) depositing on a continuous backing paper from a dual die, contiguous layers of a permanent pressure sensitive adhesive, of acrylic, in emulsion, and a co-deposit in it of a layer of a pressure sensitive adhesive, removable, acrylic, and emulsion; (b) hardening the layers of the pressure sensitive, permanent adhesive and the pressure sensitive adhesive, removable in the backing; and (c) laminating to a release surface the formed construction of the removable, pressure sensitive adhesive of the permanent pressure sensitive adhesive and backing; the removable, pressure sensitive adhesive layer that is applied to a coating weight of at least about 50% by weight and the total coating weight and a coating weight ratio to the permanent pressure sensitive adhesive of at least approximately 1: 1.

14. A construction according to claim 13, characterized in that the backrest provides the release surface.

15. A method according to claim 13, characterized in that the release surface is provided by a continuous paper of a release liner.

16. A method for the production of a construction of adhesives controlled by pressure controlled adhesion, characterized in that it comprises: (a) deposit on a release surface provided by a support from a dual die, a layer of pressure sensitive adhesive , reravible that has a first adhesiveness; (b) co-depositing on the removable, pressure-sensitive adhesive layer a layer of a permanent pressure-sensitive adhesive having a second adhesiveness greater than the first adhesiveness; (c) hardening the deposited layers of the permanent pressure sensitive adhesive and the pressure sensitive adhesive, removable on the release surface of the support to form a pressure sensitive adhesive having a final adhesive between the first and second adhesivities and controlled by the thickness of the first and second layers; and (d) laminating to a backing the formed construction of the permanent pressure sensitive adhesive of the removable pressure sensitive adhesive and of the support that provides the release surface.

17. A method according to claim 16, characterized in that the support for the release surface is provided by the backrest.

18. A method for the production of a construction of pressure sensitive adhesives of controlled adhesives, characterized in that it comprises: (a) depositing on a continuous backing paper from a dual die a layer of a permanent pressure sensitive adhesive first adhesiveness, adjacent to a co-deposited layer of a pressure-sensitive adhesive, removable from a second adhesiveness, lower than the first adhesiveness. (b) drying the layers of the permanent pressure sensitive adhesive and the pressure sensitive adhesive, removable in the backing; and (c) laminating to a release surface the formed construction of the pressure-sensitive adhesive, the permanent pressure sensitive adhesive and the backing removable; the adhesivities of the first and second co-deposited layers of adhesive that are between the adhesiveness of the removable and permanent pressure-sensitive adhesives, and in proportion to the thickness of the two layers.

19. A construction according to claim 18, characterized in that the backrest provides the release surface.

20. A method according to claim 18, characterized in that the release surface is provided by a continuous paper of a release liner.

21. A method according to any of the previous claims, characterized in that the support for the release surface is provided by a continuous release liner paper and in which the laminate product of the permanent pressure sensitive adhesive of the adhesive sensitive to The pressure, removable and release liner are laminated to a separate continuous backing paper.

22. A method according to any of claims 8 to 21, characterized in that the coating weight ratio is at least about 3: 1.

23. A method according to any of claims 8 to 21, characterized in that the coating weight ratio is at least about 4: 1.

24. A method according to claim 17, characterized in that the coating weight ratio is at least about 3: 1.