MXPA01000210A - Paint roller with integrated core and cover and method and apparatus for production of same - Google Patents

Abstract

A reusable multi-strip laminate paint roller and method for manufacturing the same. The method comprising steps of advancing a first strip of polypropylene material about a mandrel (21);advancing a second strip of polypropylene about a mandrel in offset relation to the first strip (22);advancing a cover about the second strip of polypropylene (23);providing a first adhesive layer (preferably a liquefied polypropylene) between the first and second strips of polypropylene (6);providing a second adhesive layer between the second strip of polypropylene and the cover (6);and applying a compressing force upon the cover urging the cover toward the second strip and simultaneously urging the second strip toward the first strip (2, 23) thereby creating the continuous laminated paint roller. After forming of the continuous paint roller it is moved towards a cutter by a helical drive belt system (2). The continuously formed roller is then prefeably cut into lengths for movement to a finishing station, and then cut into finished sizepaint rollers.

Description

PAINT ROLLER WITH INTEGRATED NUCLEI AND COVER AND METHOD AND APPARATUS FOR ITS PRODUCTION Field of the Invention This invention relates to a method and apparatus for making paint rollers of the type used to apply paint to walls and the like. More specifically, the invention relates to a method and apparatus for making paint rollers having thermoplastic cores (and preferably polypropylene), which are formed in a continuous one-step process.

BACKGROUND OF THE INVENTION Previous Technique Professionals and novices widely use paint rollers to apply paint to walls, ceilings, and other surfaces. Typically the roller is used with an applicator having a handle terminating in a rotating member to which the roller is secured. The roller itself generally comprises an absorption and propagation cover, fixed to a generally cylindrical core. The covers can be made from materials such as wool or polyester, and other cover materials that are well known in the art.

Years ago the rollers were manufactured using a core of paper or cardboard. Some manufacturers still make those paper core paint rollers. The manufacture of these cores is well known. Those cores, however, and the paint rollers made from them, will often fall apart during use, or during cleaning, especially during cleaning with paint solvents (such as, for example, turpentine or mineral spirits, those solvents are well known in the art). It has always been desirable, and still desirable, to make the paint roller resistant to paint solvents. An advance was made to make paint rollers when the paper cores with phenolic cores were replaced, that is, kernels made of paper impregnated with phenolic. These paint rollers withstood exposure to paint solvents much better than their paper or cardboard counterparts. The process for making phenolic nuclei is also well known. For example, in accordance with a known technique, a disposable roll that can be reused is made by first feeding three strips of paper impregnated with phenolic at an angle to a mandrel for overlapping, helical winding to form a endless core. Typically, the phenolic strips are supplied in cylinders that can be mounted on spindles for continuous feeding, and a continuous thermal setting adhesive is applied to the outer surfaces of the strips, as they are fed out of the rollers, in such a manner that the strips adhere together as they are helically deformed to form the core. As the auger is driven down the line by band, the core is heated in a multistage Thfrared heater, after which a hot melt glue is applied to the outer surface of the core and a helical winding is wound continuous strip of the cover material, such as polyester, in the core, where it is secured by hot melt. All that remains is to cut the resulting auger into sizes that can be used, which is usually done in two steps, first using a cantilever cutter to cut, for example, a 65-inch raw material, and then using another cutter to Cut the raw material into lengths that can be used for, say, seven or nine inches. The obvious inconvenience of the reusable cores, formed in this way, is that they require a long assembly line, due to the need for a heater, and because the phenolic must be heated to a predetermined temperature , there is an obvious exchange between the number of stages of the heater and the speed of the line. Additionally, although the resulting rolls are called reusable because they do not separate when placed in paint solvents, any prolonged exposure to those solvents, results in the breakdown of the paint roller and / or the separation of the layers. On the other hand, the manufacturing process for making phenolic core rolls is not environmentally friendly. In U.S. Patent No. 4,692,975 issued to Garcia, another reusable roller is described, wherein the roll is formed using a preformed core, made of thermoplastic tubular raw material (e.g., polypropylene). In particular, the process described the assembly of a core previously formed on a rotating spindle, providing a moving cart in a direction parallel to the spindle, and providing a direct heat source in the cart and, at an angle to the spindle, a strip of continuous cloth. The described process consisted in turning on the direct heat source to start heating the external surface of the tubular raw material, and moving the cart parallel to the spindle in timed relation with the rotation of the spindle, in such a way that the strip of tea it is wound in the heated portion of the plastic core in a tight helix. By means of the same the heated portion of the plastic core was softened by heat just before the point where the strip of fabric was applied, in such a way that the fabric was stuck to the core as it wound on it. In effect, a portion of the surface of the polypropylene core was used as the bonding adhesive. One advantage of the roller described in the Garcia patent is that the bond formed between the cover and the core is a strong one, not easily subject to separation by exposure to paint solvents. Another advantage is that the manufacturing process does not require the application of a separate adhesive to attach the cover to the core. There are, however, inconveniences. For example, while the prior art techniques use rollers of, for example, cardboard or paper, the Garcia process requires preformed thermoplastic tubular cores, which are considerably bulkier than rollers, more expensive to transport, and more difficult. to handle. Another inconvenience is the anticipated speed limit of the Garcia process, dictated by the need for the heater, which advances along the core just in front of the fabric strip, to move slow enough to ensure core softening. of polypropylene, in the absence of which the fabric cover will not be bonded. In addition, the application of direct heat to the previously formed polypropylene core presents manufacturing hazards from the heat source, and from the vapors and / or chemicals that are released during the heating process.

U.S. Patent No. 5,195,242, issued to the present inventor, solved many of the above problems by means of (i) forming the thermoplastic core on the fly, instead of using previously formed cores, and (ii) using the thermoplastic previously heated as a glue, both to form the core by applying it between the strips that form the core, and to fix the cover to the core by applying it to the outside of the core, before wrapping the cover to the same . The patent describes a process involving the wrapping of three strips of thermoplastic material (preferably polypropylene) around a material in overlapping relationship, to form a core, the strips that make up the core are joined together by the application of a liquefied thermoplastic material (again, preferably polypropylene) thereto, before wrapping them towards the mandrel. After the core is formed in this way, a liquefied thermoplastic is applied (again, preferably polypropylene) to the outer surface of the core, and a cover is wrapped thereon. All that remains, as is well known, is to cut the resulting auger into sizes that can be used, which, as described above, can be done in two steps, first, using a cantilever cutter to make longer lengths, and then using another cutter to cut the raw material into lengths that can be used. Although this process was capable of making high quality rolls, which were substantially unaffected by the paint solvents, the process involved the use of multiple strips of thermoplastic material and numerous application points for the liquefied thermoplastic. As a result, it was difficult to establish the process, and it required many continuous adjustments in its operation. U.S. Patent Number 5,468,207, issued to Bower, describes a continuous process such as that described in the '242 patent, except that Bower describes the use of direct heat to bond the surface of thermoplastic plastic strips, instead of applying the liquefied thermoplastic to the strips to join them together. Additionally, Bower describes the use of direct heat to the core surface to join the cover, rather than applying the liquefied thermoplastic before applying the cover. U.S. Patent No. 5,572,790, also issued to the present inventor, among other things, solved some of the complexity problems of the previous process. Under this process, which has become the de facto standard for the manufacture of rolls currently, instead of forming a core by wrapping a plurality of strips in overlapping relation to a mandrel, and then attaching a cover thereto, it was described winding only a single strip towards the mandrel, the adjacent edges placed, by the same, in a closely spaced or abutting relationship. A liquefied thermoplastic material (preferably polypropylene) is then applied to the exposed surface of the wound strip, and a roll is formed by helically winding the cover over the liquefied material, and the strip is wound with sufficient tension force, so that the cloth cover rests gently on it. Again, as with other endless roller manufacturing, a cantilever cutter can first be used to cut the product into longer lengths, and then those lengths can be cut to lengths that can be used. This process represented an advance over the previous method invented by the present inventor, because the entire paint roller was formed in a single step, which made the assembly line easier to handle, since there was only one strip of material and a single application of liquefied thermoplastic. The resulting roller, however, is somewhat inferior. More specifically, a defect present in all those rollers manifested itself as a weak point, frequent sticking out of the ends of a cut roller, or making the ends of a cut roller appear "out of curvature". This is the result of the high voltage memory of the strip, which tends to unwind or to "open" with the high tangential resistance. On the other hand, to achieve the desirable hardened feel of multilayer rolls, single strip rolls are generally made using a more cold plastic strip. The thicker the plastic strip used (especially in relation to the diameter of the core), the more pronounced the memory effect appears on the roller. In a very recently issued patent application, another process for manufacturing thermoplastic paint rollers was described. Specifically, U.S. Patent No. 5,862,591 discloses another method for forming a paint roller in a single step. In this process, thermoplastic strips are not used, and rather a fluidized polypropylene is applied directly to the mandrel, and a cover is placed on it. The application of fluidized polypropylene to a mandrel has concomitant complications in synchronization, and in the problems inherent in working with the consistency of application of a fluidized layer to form a polypropylene core. Like this process, other proposals have been made to place the pile fabric in a heated core, such as, for example, in French Patent Publication 2,093,060, in which the pile fabric is placed on a hot, freshly extruded core. It is believed, however, that no such system has gone into practical use, possibly due to the difficulties associated with controlling the variation of shrinkage that inevitably occurs in the coupling of what is essentially a heated core model through, or model of strip and a cold stack cloth (ie at room temperature, for example).

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved and less complex method for forming a reusable paint roller, comprising a laminated core and a fully integrated cover. It is another object of the present invention to provide a simplified process for manufacturing paint rollers having a laminated core formed from two polypropylene strips. It is another object of the present invention to provide a method and apparatus for the manufacture of high quality paint rollers, in an extremely compact assembly area. It is a further object of the present invention to provide a method by which paint rollers of small cross-sectional diameter can be easily constructed in a continuous process. Generally, the present invention comprises a method for producing a paint roller in a single continuous integrated operation. The method of the present invention comprises the steps of: helically advancing a first strip of thermoplastic material towards a mandrel; helically advancing a second strip of thermoplastic material towards the first strip of thermoplastic material, in phase relation with it; helically advancing a cover towards the second strip; providing an adhesive between the outer surface of the first strip and the inner surface of the second strip; providing an adhesive between the outer surface of the outer strip and the inner surface of the cover; and forming a continuous rolling paint roller by applying a compression force on the cover. In a preferred embodiment of the present invention, the cover strip and the adjacent adjacent adhered polypropylene strip are laterally offset from one another, whereby the cover strip extends the adjacent winding of the second polypropylene strip. This provides additional structural strength to maintain the rigidity of the roller. It is believed that this is a significant factor for making small diameter rolls, which could not be done practically by means of the single strip methods of the prior art of roller production.

Rollers made in accordance with the present invention provide sufficient resistance against unfolding of the core material to a degree where small diameter rollers are made (roll core diameter of 0.5"as opposed to the more common 1.5" cores). ) with usable structural integrity and resistance against the final separation of the strips. In addition, as opposed to single strip rollers made in accordance with the prior art, the integral roller core and the cover material rollers of the present invention, when split lengthwise, do not open automatically, but rather rather they retain substantially their original configurations, demonstrating by the same the different product thus made. The core and the roll are formed in a single step, and become essentially complete almost immediately after being compressed on the cooled mandrel, to form the shape of the roll. The mandrel further provides a base for transporting the material of the roller towards a cantilever cutter to cut almost immediately the finished product of the specified length dimension. The variation in the diameter of the mandrel determines the diameter of the core of the roller, and its last dimensions of finished diameter. The upper rolls of the present invention are thus formed with a simplified assembly line and process, comprising: a) two feeders for the two polypropylene strips, b) a feeder for the cover strip, c) a heater for activating a layer of adhesive or an extruder to apply a layer of adhesive; d) a stationary cooled mandrel; e) a conveying means such as a helical driving belt, to form and advance the endless roller, and f) a cutter. The present invention comprises a novel combination using two strips of thermoplastic material, forming the laminated core and the paint roller simultaneously, to provide an unexpectedly efficient method and apparatus for making superior paint rollers. The objectives, features and advantages above and others of the present invention will be more apparent from the following discussion and drawings in which: BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a diagrammatic representation of an apparatus suitable for making rollers, in accordance with the present invention. Figure 2 is an enlarged diagrammatic representation of a first preferred configuration for making rollers in accordance with the present invention. Figure 2a is a cut-away of the diagrammatic representation shown in Figure 2. Figure 3 is an enlarged diagrammatic representation of a second preferred embodiment for making rollers in accordance with the present invention. Figure 4 is an enlarged diagrammatic representation of a third preferred configuration for making rollers in accordance with the present invention. Figure 5 is an enlarged diagrammatic representation of the fourth preferred configuration for making rollers in accordance with the present invention. Figure 6 is an enlarged diagrammatic representation of a fifth preferred configuration for making rollers in accordance with the present invention. Figure 7 is an enlarged diagrammatic representation of a sixth preferred configuration for making rollers in accordance with the present invention. Figures 8a and 8b are perspective views of rollers made in accordance with the prior art and the present invention, respectively, after having been longitudinally split.

DETAILED DESCRIPTION OF THE INVENTION AND THE PREFERRED MODALITIES With reference to the drawings, in Figure 1, a roller forming apparatus 10 comprises a stationary mandrel 1, cooled by the cooler 5, in which the roller 20 is formed, the driving belt helical 2 moves between the driving rollers 2a and 2b to rotate and move the endless roller 20 formed along the mandrel 1 to a cantilevered cutter 3. For ease of description in this application, the term "downstream" refers to the further direction throughout the roller manufacturing process, or closer to cantilever cutter 3, while the term "upstream" refers to the previous direction in the roller manufacturing process, or beyond the cantilever cutter 3.

First Modality In a first modality, shown in the Figure 1, a detail shown in Figure 2, and a cutout detail shown in Figure 2a, a continuous paint roller is manufactured from an inner strip of thermoplastic material 21, an outer strip of thermoplastic material 22 , a cover 23, and an adhesive 6 applied from one or more heads 4. The thermoplastic material is preferably polypropylene. The cover 23 can be a well-known cloth cover for a paint roller, which can be made of polyester. The inner strip 21 is helically advanced towards the mandrel 1. The term "helically", as used herein, means oriented towards a mandrel in order to allow the running edge under a given winding of a strip to be in closely spaced relationship or abutting the edge upstream of the preceding winding of the strip. As is well known in the art, a lubricant such as 5 percent mineral oil can be applied to the inner surface of the inner strip 21 prior to winding in the mandrel 1. The outer strip 22 is helically advanced towards the inner strip 21. Preferably, the edges of the outer strip 22 are offset from the edges of the inner strip 21, as the two strips are advanced along the mandrel 1. The offset between the outer strip 22 and the inner strip 21 causes the outer strip 22 to overlap the portion of the inner strip 21 where its edges upstream and downstream are in closely spaced or abutting relationship. It is believed that a stronger product is produced by having a lag between the inner strip 21 and the outer strip 22. It was found that a lag between one quarter and three quarters of the width of the inner strip 21 achieves acceptable results. The cover 23 is helically advanced towards the outer strip 22. The head 4 provides a layer of adhesive material 6 from a source of that material., the adhesive material 6 is preferably polypropylene. The source of adhesive material 7 is preferably an extruder, but can be any source of adhesive material, including a melter. The head 4 can be any type of head suitable for providing the adhesive material 6 from the source, such as a die or die. In a preferred embodiment, wherein the source 7 is an extruder, the head 4 is preferably a die. Before forming the roller, the two layers of adhesive material 6a, 6b must be applied. The first layer of adhesive material 6a is applied in such a way that it will advance between the inner strip 21 and the outer strip 22. The second layer of adhesive material 6b is applied in such a way that it will advance between the outer strip 22 and the cover 23 In a preferred embodiment, the first layer of adhesive material 6a is applied to the outer surface of the inner strip 21, and the second layer of adhesive 6b is applied to the outer surface of the outer strip 22. Both the first and the second adhesive layer 6a, 6b can be applied from a single head 4. A single head 4 is preferably placed in a position to allow the adhesive layers 6a, 6b to be applied to the strips 21, 22, as closely as possible to the cover 23. Preferably, the material is dosed from the head 4, with its width being parallel to the direction of the mandrel 1. Care must be taken to avoid any adhesive 6 having contact with the outer surface of the cover. ta 23. Although it is believed that the use of a single head provides the best arrangement, and produces the most consistent results, two or more heads can be used to apply the adhesive layers 6a, 6b. Before hardening and setting of the two layers of adhesive material 6a, 6b, the web driver 2 applies pressure to the outer surface of the cover 23, imparting forces inward on the component parts, and thereby forming the continuous roller towards the mandrel. In addition to forming the roller, the web driver 2 advances the endless roller thus formed along the mandrel, and continuously rotates the endless roller, also advancing the same by the strips 21, 22 and the cover 23 towards and around the mandrel. The width and thickness of the strips 21, 22 and the width and stack of the cover 23 can be those that are appropriate for the manufacture of the desired roller. For example, a typical high quality roller that has a core diameter of 1.5 inches and about 60 wall, can be manufactured with the following materials: Width Thickness Internal Strip 2.750"0.015" Adhesive Layer One 2.750"0.015" External Strip 2.750"0.015" Adhesive Layer Two 2.750"0.015" Deck 2.875"Desired Stack A typical high quality roller that has a core diameter of 1.5 inches and about 80 wall, can be manufactured with the following materials: Width Thickness Internal Strip 2.750"0.020" Adhesive Layer One 2.750"0.020" External Strip 2.750"0.020" Adhesive Layer Two 2.750"0.015" Deck 2.875"Desired Stack A typical high quality roller that has a core diameter of 1.5 inches and about 90 wall, can be manufactured with the following materials: Width Thickness Internal Strip 2.750"0.025" Adhesive Layer One 2.750"0.020" External Strip 2.750"0.025" Adhesive Layer Two 2.750"0.020" Deck 2.875"Desired Stack As used herein, the term "wall" or "thousand" means the thickness in thousandths of an inch. Those widths and thicknesses, and the methods for determining them are well known in the art. For one skilled in the art it will be apparent that an infinite cas variation is possible, depending on the characteristics of the desired roller. In addition to the well-known high-quality roller having a core diameter of 1.5 inches, it is desirable to manufacture rollers having a core of 0.5". It has been found that the manufacture of 0.5" core rollers using the technology of a single strip, such as U.S. Patent Number 5,572,790, does not produce a satisfactory result. On the other hand, it has been found that the present invention can be applied to rollers with a core of 0.5". A core roll of 0.5", 60 wall can be manufactured, for example, with the following materials: Width Thickness Internal Strip 1"0.015" Adhesive Layer One 1"0.015" External Strip 1"0.015" Adhesive Layer Two 1"0.015" Covers 1.125"Desired Stack As described above, in a preferred embodiment, a single head 4 can supply both layers of the adhesive 6a, 6b. The width and thickness of layers 6a, 6b may vary, but preferably the width should be substantially the same width as the strips 21, 22. The overall volume of the adhesive to be applied should be sufficient to allow the attachment of the inner strip 21 to the outer strip 22, and to allow attachment of the cover 23 to the outer strip 22. The amount of adhesive that is used in the second layer 6b must depend to some extent on the material of the cover 23. A head 4 that is significantly shorter can be used. than the preferred width. The use of that shorter head 4 can be accommodated by adjusting the speed of the flow, by means of shaping the die, by moving the die in one direction along its width or in other ways that are readily apparent for one of experience in the art. Similarly, the invention can be practiced with a head 4 that is significantly longer. The use of that longer head 4 can be achieved by means of shaping the die, or in other ways that are readily apparent to one of skill in the art. Although the invention accommodates a rather large variation in the width of the head 4, and therefore in the width of the material that is supplied by means of the head 4, it is believed that the use of a head 4 that provides the desired width of adhesive on the strips 21, 22, will provide the most consistent results. It is also possible, without departing from the invention, to use more than one head to apply the adhesive to advance between the strips 21, 22, and to advance between the cover 23 and the outer strip 22. Regardless of the width or the number of In order to produce a quality laminated continuous roller, inward pressure must be applied on the cover, before the two layers of polypropylene are allowed to harden and set. Orientation of food for strips 21, 22 and the cover 23, of the first embodiment, as shown in Figure 2, allows the cover 23 to advance towards the mandrel 1, adjacent and parallel to the outer strip 22. That placement allows the use of a single head 4 that the adhesive 6a, 6b can be applied to the outer surface of the inner strip 21, and to the external surface of the outer strip 22 simultaneously. Additionally this placement allows the adhesive 6a, 6b to be exposed uniformly and for a very short period, before being filed between the inner and outer strips 21, 22, or the outer strip 22 and the cover 23. Furthermore, this placement allows a very short assembly line for the continuous manufacturing process.

Second Mode It is believed that the provision of a phase shift between the outer strip 22 and the cover 23 can produce an even firmer product, a method that allows that phase shift is described. Turning now to the second embodiment, having a detail shown in Figure 3, a continuous paint roller is manufactured from an inner strip of thermoplastic material 21, an outer strip of thermoplastic material 22, a cover 23, and a adhesive 6 applied from one or more heads 4. The thermoplastic material is preferably polypropylene. The cover 23 can be a well-known cloth cover for a paint roller, which can be made of polyester. The second embodiment differs from the first in the orientation of the feed for the strips 21, 22 and the cover 23. In the second embodiment, the cover 23 is offset from the outer strip 22. The inner strip 21 is advanced helically towards the mandrel 1. As is well known, a lubricant can be applied to the inner surface of the inner strip 21 before winding it in the mandrel 1. The outer strip 22 is helically advanced towards the inner strip 21 in an out-of-phase relationship. The cover 23 is helically advanced towards the outer strip 22, in an out-of-phase relationship. The head 4 provides the adhesive material 6 from a source of that material 7, such as an extruder. Before forming the roller, the two layers of the adhesive material 6a, 6b are applied. The first layer 6a is applied in such a way that it is advanced between the inner strip 21 and the outer strip 22, and the second layer 6b is applied to advance between the outer strip 22 and the cover 23. Both the first one and the second one. second layer of adhesive 6a, 6b can be applied from a single head 4. A single head 4 is preferably placed in a position to allow the adhesive to be applied to the strips 21, 22, as close as possible to the location in where the cover 23 is wrapped towards the outer strip 22. Alternatively, two or more heads 4 may be used to apply the first and second adhesive layers 6a, 6b. Before hardening and setting of the two layers of adhesive material 6a, 6b, the web driver 2 applies pressure to the outer surface of the cover 23, imparting forces inward on the component parts, and thereby forming the continuous roller towards the mandrel. In addition to forming the roller, the belt impeller 2 advances the endless roller thus formed along the mandrel, and continuously rotates the endless roller, also advancing the same by the strips 21, 22 and the cover 23 to and around the mandrel. The assembly line for this mode is somehow longer than the assembly line for the first mode. The additional length of the assembly line, however, can be only one or two inches, or less, so this is not considered significant. The second embodiment causes non-uniform exposure of the adhesive layer 6 before being patterned. The importance of non-uniform exposure of the adhesive is unknown, however, if it proves to be a problem, a multi-head system can be used to solve it. For example, a head 4 can be used for the first layer 6a and a portion of the second layer 6b. A second head 4 can then be used to apply the remaining portion of the second layer of adhesive 6b at a slightly higher temperature, thus compensating for the difference in exposure. Turning now to a third embodiment, having a detail shown in Figure 4, a continuous paint roller is manufactured from an inner strip of thermoplastic material 21, an outer strip of thermoplastic material 22, a cover 23, and an adhesive (not shown) applied from two heads 4a and 4b. The thermoplastic material is preferably polypropylene. The cover 23 can be a well-known cloth cover for a paint roller, which can be made of polyester. The third embodiment differs from the first two in the orientation of the feed for the strips 21, 22 and the cover 23. The third embodiment consists of the shortest assembly line. The inner strip 21 is helically advanced towards the mandrel 1. As is well known, a lubricant can be applied to the inner surface of the inner strip 21 before winding it in the mandrel 1. The outer strip 22 is helically advanced towards the inner strip 21 in discarded relation. The cover 23 is helically advanced towards the outer strip 22, the cover can, but has to be in an out-of-phase relationship. Before forming the roller, two layers of the adhesive material are applied (not shown). Two heads 4a, 4b provide the adhesive material from a source of that material 7, such as an extruder. The head 4a applies a first layer of the adhesive to the inner surface of the outer strip 22, while the head 4b applies a second layer of the material to the outer surface of the outer strip 21. Prior to hardening and setting of the two layers of adhesive material, the web driver 2 applies pressure to the outer surface of the cover 23, imparting forces inwardly on the component parts, and thereby forming the continuous roller toward the mandrel. In addition to forming the roller, the belt impeller 2 advances the endless roller thus formed along the mandrel and continuously rotates the endless roller, also advancing the same by the strips 21, 22 and the cover 23 and around the mandrel.

Fourth Mode A fourth embodiment of the present invention will be described with reference to Figure 5, a continuous paint roller is manufactured from an inner strip of thermoplastic material 21, an outer strip of thermoplastic material 22, a cover 23, and a head 4. The thermoplastic material is preferably polypropylene. The cover 23 can be a well-known cloth cover for a paint roller, which can be made of polyester. A first adhesive layer 24 is present on the outer surface of the inner strip 21, and a second layer of adhesive 25 is present on the outer surface of the outer strip 22. The adhesive layers preferably comprise polypropylene. Although this embodiment is described as such, it is within the skill of the art to recognize that the first and second adhesive layers 24, 25 can also be placed on the inner surface of the outer strip 22, and on the inner surface of the cover 23, respectively. It is only important that the head 4 'is capable of engaging the adhesive layers 24, 25, and that the adhesive layers 24, 25 are between the inner strip 21 and the outer strip 22, and the outer strip 22 and the outer layer 22 cover 23, respectively. The inner strip 21 is advanced helically towards the mandrel 1. As is well known, a lubricant can be applied to the inner surface of the inner strip 21 before advancing it. The outer strip 22 is helically advanced towards the inner strip 21, in an out-of-phase relationship. The cover 23 is helically advanced towards the outer strip 22.

The head 4 'provides heat. The head 4 'can be an electric heater, it can be operated by gas, or it can be any other type of heater, suitable for activating the adhesive layers 24, 25 in the strips 21, 22. (One layer of adhesive is activated by means of being liquefied, that is, brought into a sticky, melted state). Before forming the roller, the head 4 'activates the two adhesive layers 24, 25. Both the first and the second adhesive layers 24, 25 can be activated from the single head 4'. The head 4 'is preferably placed in a position to allow the adhesive to be activated in the strips 21, 22, inside the region designated by the measurement A in Figure 2. Preferably, the head 4' is oriented parallel to the direction of the mandrel 1. Care must be taken to prevent the heat emanating from the head 4 'from heating the outer surface of the cover 23 to a degree that would melt, or otherwise adversely affect its properties. In order to avoid that damage to the cover 23, the cover 23 is advanced towards the outer strip 23 a winding downstream from the head 4 '. Alternatively, heat protection can be employed (not shown). Although it is believed that the use of a single head 4 'provides the easiest arrangement, and produces the most consistent results, two or more heat sources can be used to activate the adhesive layers.

Before hardening and setting of the two adhesive layers 24, 25, the web driver 2 is used to apply pressure to the outer surface of the cover 23, imparting forces inwardly on the component parts, and thereby forming the roller I continued towards the mandrel. In addition to forming the roller, the belt driver 2 advances the endless roller thus formed along the mandrel and continuously rotates the endless roller, also advancing the strips 21, 22 and the cover 23 to and through the same. around the mandrel.

Fifth Mode A fifth embodiment of the present invention will be described, with reference to Figure 6, a continuous paint roller is manufactured from an inner strip of thermoplastic material 21, an outer strip of thermoplastic material 22, a cover 23, and a head 4 '. The fifth embodiment differs from the fourth embodiment in which the cover 23 deviates from the outer strip 22. In this embodiment the cover 23 is spaced in a winding half of the head 4 '. It is believed that this has an advantage in that the cover 23 is closer to the head 4 ', but it is likely that no protection against heat is required.

Sixth Mode A sixth embodiment of the present invention is described with reference to Figure 7, a continuous paint roller is manufactured from an inner strip of thermoplastic material 21, an outer strip of thermoplastic material 22, a cover 23, and two heads 4a ', 4b'. A first adhesive layer 24 is present on the inner surface of the outer strip 22, and a second adhesive layer 25 is present on the outer surface of the outer strip 22. The adhesive layers preferably comprise polypropylene. The inner strip 21 is helically advanced towards the mandrel 1. The outer strip 22 is helically advanced towards the inner strip 21, in an out-of-phase relationship. The cover 23 is helically advanced towards the outer strip 22. Two heads 4a ', 4b' can be electric heaters, operated by gas, or any other type of heater suitable for activating the adhesive layers 24, 25 on the strips 21, 22. Before forming the roller, two layers of adhesive 24, 25 are activated by means of the heads 4a ', 4b'. The heads 4a ', 4b' are preferably positioned in a position to allow the adhesive layers 24, 25 to be activated at a point near where the outer strip 22 is advanced towards the inner strip 21. Preferably, the heads 4a ', 4b' are oriented in a direction perpendicular to the length of the outer strip 22. Care must be taken to prevent the heat emanating from the heads 4a ', 4b' from heating the cover 23 to a melting degree, or that would otherwise adversely affect its properties. A heat shield can be used (not shown). Before hardening and setting of the two adhesive layers 24, 25, the web driver 2 is used to apply pressure to the outer surface of the cover 23, imparting forces inwardly on the component parts, and thereby forming the roller I continued towards the mandrel. In addition to forming the roller, the web driver 2 advances along the mandrel the endless roller thus formed, and continuously rotates the endless roller, also advancing the same by the strips 21, 22 and the cover 23 towards and around the mandrel. Although it is believed that the proportion of both adhesive layers 24, 25 in the outer strip 22 provides the easiest arrangement, and produces the most consistent results, it is within the scope of the invention to provide and activate the first adhesive layer 24 in the external surface of the inner strip 21. It is also within the scope of the invention to divide the first layer of adhesive 24 between the inner surface of the outer strip 22 and the external surface of the inner strip 21. The adhesive layer 24 thus has departed. ,, either multiple heads 4a may be employed or, alternatively, a single head 4a1 may be located near the point where the inner strip 21 and the outer strip 22 make contact for the first time. In making the inventive paint roller using the process described herein, it is desirable to have the web impeller 2 closely after the point in the manufacturing process in which the cover is wrapped. Preferably, the belt impeller 2 immediately follows the jacket, thereby allowing the belt impeller 2 to impart physical force to the component parts, before the thermoplastic hardens and sets, thereby creating an endless roller 20. It has been found that allowing: the belt impeller 2 to act on the roller not yet fully set, provides an upper roller. As is well known in the art, the endless roller 20 can be cut with the cantilever saw 3 in lengths, after it has set sufficiently. In employing the present invention, the total length of the assembly line that is required to manufacture high quality paint rollers may have less than inches of mandrel 1, and less than 20 inches between the band 2 impeller and cantilever saw 3.

Apart from the rapidity in which finished rollers are formed with minimal line equipment, the rollers formed are of superior structural integrity. As seen in Figures 8a and 8b the split rollers 20 (present invention) and 20 '(prior art of a single strip) differ in shape. The prior art roller 20 ', with a longitudinal cut, experiences a reeling force retained by the roller and automatically opens to a curved surface section. This is indicative of the constant arcing forces operating against the core structure, causing the end sections 24 to separate from the adjacent section 26 in a non-visible manner. In addition, the high tonnage forces make the manufacture of single-strip rollers of smaller diameter, almost impossible in terms of integrity and proper construction. In contrast, the roller 20 of the present invention experiences little or no unfolding even with roller cores of smaller diameter. It is believed that this is the result, in part, of the rolling effect of the multiple usually thinner strips. An unexpected benefit of the present process is that the cost is significantly less than the cost to manufacture a comparable roller, using single strip technology, such as that of U.S. Patent Number 5,572,790. The benefit of the cost is the result of the fact that extruded polypropylene in the form of a strip is significantly more expensive per pound than polypropylene in the form of a pill, whose final form is used in an extruder to form the adhesive. With a laminated process, two layers of adhesive between 0.15"and 0.25" are applied, while with the single strip process the maximum adhesive layer is 0.25". Therefore, to make almost any roller, can reduce the amount of extruded polypropylene, and can produce a better but less expensive product.As the number of strips increase, so does the complexity of the process.According to the above, it is probably not feasible to manufacture products of four, five or more strips On the other hand, the present invention allows the use of a single head for the application of the adhesive A process having three or more strips of polypropylene requires at least two heads The above modalities and preferences are illustrative of the present invention It is not necessary, nor is it intended by means of this patent to delineate or define any combination or possible modality.The inventor has described sufficient information for allowing one skilled in the art to practice at least one embodiment of the invention, and has described the ways that the inventor now believes are the best ways to practice the invention. The most obvious variations to the present invention include the variation in the placement or orientation of the strips 21, 22 and the cover 23, and the variations in the placement of the head 4, 4 ', 4a, 4b. It is understood that the description and the foregoing drawings are merely illustrative of the present invention, and that changes in the components, structure and method are possible, without departing from the scope of the present invention, as defined in the following claims.

Claims (50)

1. CLAIMS 1. A method for producing a paint roller in a single continuous integrated operation, comprising the steps of: a. initially feeding angularly a first strip of polypropylene to a mandrel support member, and thereafter, with a phase shift of the angular feed of the polypropylene strip, angularly feeding a second polypropylene strip on an external surface of the first polypropylene strip, and angularly feeding a strip of paint roller cover, onto an outer surface of the second polypropylene strip. b. after the initial feeding of the respective strips to the mandrel, move the respectively fed strips both in a rotational direction towards the mandrel, and simultaneously along the length of the mandrel, while continuously applying a layer of adhesive to the first and second ones strips, the adhesive layer extending over at least a portion of an exposed external surface of a. winding the second polypropylene strip, adjacent thereto, with the adhesive layer without having contact with an outer surface of the cover strip; wherein the movement and application of the adhesive layer to the adjacent windings of the first and second polypropylene strips effect a continuous adhesion between the first and second polypropylene threads, and between the second polypropylene strip and the cover strip, to continuously form the core and the cover of the paint roller.
2. 2. The method of claim 1, wherein the cover strip and the adjacent adjacent adhered polypropylene strip are laterally offset from one another, whereby the cover strip extends over the adjacent winding of the second layer. polypropylene strip, providing by the same additional structural strength to maintain the rigidity of the roller.
3. 3. A paint roller made in accordance with the method of claim 2, wherein the diameter of the core is no more than 0.5"
4. 4. An assembly line for the continuous manufacture of paint rollers, comprising: a a stationary mandrel, b) two feeders for the first and second polypropylene strips to a mandrel, a feeder for a cover strip to an external surface of the second polypropylene strip, an element for dosing a width of liquefied polypropylene, which extends over at least part of the width of the adjacent winding portions of the first and second polypropylene strips, and a transport element for advancing and rotating the roller as it is being formed. continuously in the mandrel, and f) a cutter for cutting roller segments to predetermined sizes
5. 5. An assembly line as claimed in claim 4, characterized in that it also turn on a cooling system to cool the stationary mandrel.
6. 6. A method for continuously producing a paint roller rolled into multiple strips, comprising the steps of: feeding a first strip of polypropylene material towards a mandrel; advancing the first strip of polypropylene material along the mandrel, while simultaneously rotating the first strip of polypropylene material towards the mandrel, to helically wind the first strip; feeding a second strip of polypropylene material to the first strip of polypropylene material, in continuous offset relation thereto, with an inner surface of the second polypropylene strip having a liquid film of polypropylene material thereon; feeding a cover strip to the second polypropylene strip, to the cover strip having a layer of adhesive that has been applied to an inner surface of the cover strip, thereby creating a paint roller laminated into multiple strips.
7. 7. A method for producing a paint roller rolled in multiple strips in a continuous manner, comprising the steps of: feeding a first strip of thermoplastic material towards a mandrel; feeding a second strip of thermoplastic material towards the first strip of thermoplastic material, in phase relation with it; applying adhesive on, at least: a portion of the outer surface of a winding of the first strip, an adjacent portion of the outer surface of a subsequent winding of the first strip, and substantially the entire outer surface of a winding of the second strip; feed a cover to the second strip; and applying a compression force on the cover, pushing the cover towards the second strip, and simultaneously pushing the second strip towards the first strip, creating by means of the same the paint roller rolled in multiple continuous strips.
8. The method claimed in claim 7, characterized in that it also comprises the step of: applying on the cover a rotating force and a linear force parallel to the mandrel, pushing through it the paint roller rolled into multiple continuous strips, so that it rotates towards, and move along the mandrel.
9. 9. The method claimed in the claim 8, wherein the compression force, the rotating force and the linear force are all imparted through a helical band system.
10. The method claimed in claim 9, characterized in that it also comprises the step of: cutting the rolled paint roller into multiple continuous strips in lengths.
11. The method claimed in claim 7, characterized in that it also comprises the step of: cutting the paint roller rolled into multiple continuous strips in lengths.
12. 12. The method claimed in claim 7, wherein the thermoplastic material is polypropylene.
13. The method claimed in claim 12, wherein the adhesive is liquid polypropylene.
14. The method claimed in claim 13, wherein the second strip is offset from the first strip by between 1/4 and 3/4 of the first strip.
15. 15. The method claimed in claim 14, wherein the cover is wound in an offset relationship with the second strip.
16. 16. The method claimed in claim 15, wherein the cover is offset from the second strip by between 1/4 and 3/4 of the second strip.
17. 17. The method claimed in the claim 13, characterized in that it also comprises the steps of: applying on the cover a rotary force and a linear force parallel to the mandrel, pushing through the same the paint roller rolled in multiple continuous strips, so that it turns towards, and moves to along the mandrel.
18. 18. The method claimed in claim 17, wherein the compressive force, rotational force and linear force are imparted through a web system.
19. The method claimed in claim 17, characterized in that it also comprises the steps of: cutting the paint roller formed continuously into substantially equal lengths; and cutting the substantially equal lengths into lengths that can be used.
20. 20. The method claimed in the claim 7, wherein the cover is wound in an offset relationship with the second strip.
21. 21. The method claimed in claim 7, wherein the diameter of the mandrel varies between 0.5 inches and 1.5 inches.
22. 22. The method claimed in claim 7, wherein the diameter of the mandrel is approximately 0.5 inches, thereby forming a roller with an internal diameter of approximately 0.5 inches.
23. 23. A paint roller made in accordance with the method of claim 22.
24. 24. A paint roller comprising: an internal strip of helically wound polypropylene, having an internal diameter of about 0.5 inches; an external strip helically wound, laminated to the inner strip, the lamination formed by means of liquid polypropylene hardened and set between the inner and outer strips; a helically wound cover, fixed to the outer strip of liquid polypropylene medium hardened and set between the outer strip and the cover.
25. 25. A method for continuously producing a paint roller laminated into multiple strips, comprising the steps of: helically advancing a first strip of polypropylene material towards a mandrel, the first strip having an internal and an external surface; applying an adhesive to the external surface of the first strip, in a location where the inner surface of the first strip is in contact with the mandrel; helically advancing a second strip of polypropylene material towards the first strip, covering therewith the adhesive on the outer surface of the first strip, the second strip being helically wound in an offset relation to the first strip, and the second strip having a internal surface and an external one; applying an adhesive to the external surface of the second strip; helically advancing a cover strip towards the second strip, thereby covering the adhesive on the outer surface of the second strip; applying a compression force on the cover, pushing the cover towards the second strip, and simultaneously pushing the second strip towards the first strip, creating by means of the same the continuous laminated paint roller.
26. 26. The method claimed in the claim 25, characterized in that it also comprises the step of: applying on the cover a rotary force and a linear force parallel to the mandrel, pushing through the same the paint roller rolled into multiple continuous strips, so that it turns towards, and moves along of the mandril.
27. 27. The method claimed in the claim 26, wherein the compression force, the rotating force and the linear force are all imparted through a helical band system.
28. 28. The method claimed in claim 25, wherein the diameter of the mandrel is approximately 0.5 inches, thereby forming a roller with an internal diameter of approximately 0.5 inches.
29. 29. A paint roller made in accordance with the method of claim 28.
30. 30. A method for continuously producing a paint roller rolled into multiple strips, comprising the steps of: advancing helically an internal and external strips of material polypropylene towards a mandrel, in outdated relation; apply a layer of liquid polypropylene material between the two strips, and on the outer surface of the outer strip; before allowing the liquid polypropylene layer to harden and set, wrap a cover around the outer strip, and apply a compressive force on the cover, pushing the cover and the two strips towards the mandrel, creating by the same the roller of continuous laminated paint.
31. 31. The method claimed in claim 30, characterized in that it also comprises the step of: applying to the cover a rotary force and a linear force parallel to the mandrel, pushing through the same the paint roller rolled into multiple continuous strips, so that it rotates towards, and move along the mandrel.
32. 32. The method claimed in claim 31, wherein the compression force, the rotational force and the linear force are all imparted through a helical band system.
33. 33. The method claimed in claim 30, wherein the mandrel diameter is approximately 0.5 inches, thereby forming a roller with the internal diameter of approximately 0.5 inches.
34. 34. A paint roller made in accordance with the method of claim 33.
35. 35. A continuous process for producing a multi-stripe, endless rolled paint roller comprising the steps of: advancing a first strip of polypropylene material towards a mandrel, the first strip having a first adhesive layer ds along its outer surface; advancing a second strip of polypropylene material laces the first strip in phase-to-phase relationship with it, the second strip having a second layer of adhesive along its outer surface; advancing a cover towards the second strip; and continuously activating the advance of the first layer of adhesive at a point in the process, before the location where the advance of the second strip contacts the first strip; and continuously activating the advancement of the second layer of adhesive at a point in the process, before the location where the cover contacts the second strip; applying a compression force on the cover, pushing the cover towards the second strip, and simultaneously pushing the second strip towards the first strip, creating by means of the same the paint roller rolled in multiple continuous strips.
36. 36. The process claimed in the claim 35, wherein the adhesive is liquid polypropylene.
37. 37. The process claimed in claim 36, wherein the compression force is imparted through a helical band system.
38. 38. The process claimed in claim 37, wherein the second strip is offset from the first strip by between 1/4 and 3/4 of the first strip.
39. 39. The process claimed in the claim 36, characterized in that it also comprises the steps of: cutting the paint roller formed continuously into substantially equal lengths; and cutting the substantially equal lengths into lengths that can be used.
40. 40. The process claimed in claim 36, wherein the diameter of the mandrel is approximately 0.5 inches, thereby forming a roller with an internal diameter of approximately 0.5 inches.
41. 41. A paint roller made in accordance with the process of claim 40.
42. 42. A method for continuously producing a paint roller rolled into multiple strips, comprising the steps of: helically advancing a first strip of material from polypropylene towards a mandrel, the first strip having an internal and an external surface, and a first layer of adhesive on its external surface; continuously activating the first layer of adhesive at a location on the first strip where the inner surface of the first strip is in contact with the mandrel; helically advancing a second strip of polypropylene material towards the first strip, onto the first activated adhesive layer, the second strip being helically advanced in an offset relationship to the first strip, the second strip having an internal and an external surface, and a second layer of adhesive on its external surface; continuously activating the second adhesive layer at a location on the second strip where the inner surface of the second strip is in contact with the first adhesive layer; helically advancing a cover strip towards the second strip, thereby covering the adhesive on the outer surface of the second strip; applying a compression force on the cover, pushing the cover towards the second strip, and simultaneously pushing the second strip towards the first strip, creating by means of the same the continuous laminated paint roller.
43. 43. The method claimed in the claim 42, wherein the first and second adhesive layers are activated by a single heating element in an adjoining location.
44. 44. The method claimed in the claim 43, wherein the compression force is imparted through a helical band system.
45. 45. The method claimed in claim 42, wherein the diameter of the mandrel is approximately 0.5 inches, thereby forming a roller with an internal diameter of approximately 0.5 inches.
46. 46. A paint roller made in accordance with the method of claim 45.
47. 47. A method for continuously producing a paint roller laminated into multiple strips, comprising the steps of: helically advancing internal and external strips of material polypropylene and a cover, towards a mandrel, in out-of-phase relationship, wherein at least one of the outer surface of the inner strip and the inner surface of the outer strip comprises a first layer of adhesive, and wherein at least one of the surface external of the outer strip and the inner surface of the cover comprises a second layer of adhesive; activating the first and second adhesive layers; and before allowing the first and second adhesive layers to harden and set, apply a compressive force on the cover, pushing the cover and the two strips toward the mandrel, thereby creating the continuous laminated paint roller.
48. 48. The method claimed in claim 47, wherein the compression force, rotational force and linear force are all imparted through a helical band system.
49. 49. The method claimed in the claim 47, wherein the diameter of the mandrel is approximately 0.5 inches, forming by the same a roller with the internal diameter of approximately 0.5 inches.
50. 50. A paint roller made in accordance with the method of claim 49.