HK1234371A1 - Methods for manufacturing a paint roller and component parts thereof - Google Patents

Description

Method of making paint roller and components thereof

The patent application of the invention is a divisional application of an invention patent application with the international application number of PCT/US2010/033734, the international application date of 5 months and 5 days 2010, the application number of 201080031052.5 entering the Chinese national stage and the invented name of a method for preparing a paint roller and parts thereof.

Priority of the present application claims priority from U.S. patent application No. 12/435,946 filed on 5/2009 and U.S. patent application No. 12/687,028 filed on 13/1/2010, the entire contents of which are incorporated herein by reference.

This application contains content which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent disclosure, as it appears in the patent and trademark office patent files or records, but otherwise reserves all copyright rights whatsoever.

Technical Field

The present invention relates to a method and apparatus for manufacturing paint rollers of the type used to paint walls and the like. More particularly, the present invention relates to methods and apparatus for making components used in paint roller manufacturing processes, and methods and apparatus for manufacturing paint rollers.

Brief description of the drawings

The accompanying drawings, which form a part of the specification, and in which like reference numerals designate like parts throughout the drawings:

FIG. 1 is a schematic view of a paint roller manufacturing apparatus that may be used according to one embodiment of the present invention.

Fig. 2 is a schematic diagram of an apparatus for forming a composite paint roller cover with a compound backing according to one embodiment of the present invention.

Fig. 3 is a schematic diagram of a multiple strip laminated paint roller manufacturing apparatus that may be used in accordance with one embodiment of the present invention.

Fig. 4 is a schematic view of another paint roller manufacturing apparatus that may be used in accordance with an embodiment of the present invention.

Fig. 5 is a schematic view of another paint roller manufacturing apparatus that may be used in accordance with an embodiment of the present invention.

Detailed description of the invention and its embodiments

Fig. 1 is a schematic diagram of a paint roller manufacturing apparatus 100. A strip 145 of material comprising polypropylene is helically wound around a mandrel 140 held on a base 150. The mandrel may be cooled by a cooler (not shown). An adhesive 135 comprising polypropylene is applied to the outer surface of the strip 145 by applicator 130. The cover 125 wraps around the first strip 145 and the adhesive 135 on the mandrel 150. A helical belt 120 driven by rollers 120a, 120b applies pressure to the cover material and pushes the tubular assembly 115 down the mandrel 150. A fly away cutter (fly away saw)105 cuts the tubular assembly into usable segments 110 or cuts for making the final paint roller.

Mixed adhesive

In one embodiment, the adhesive 135 is a compound of polypropylene and calcium carbonate, wherein the calcium carbonate content is 5 to 50 weight percent. In one embodiment, the adhesive compound contains at least 25% but not more than 45% calcium carbonate. In one embodiment, the adhesive compound contains at least 25% but not more than 33% calcium carbonate. In one embodiment, calcium carbonate is compounded with polypropylene to form a compounded adhesive 135, which calcium carbonate should be selected and/or processed to be relatively non-abrasive to processing equipment.

In one embodiment, the applicator 130 applies a compounded adhesive 135 formed from a twin screw extruder that thoroughly compounds calcium carbonate from a calcium carbonate source with polypropylene from a polypropylene resin source in pellet form (not shown). When a twin screw extruder is used, the calcium carbonate should be relatively non-abrasive to the extruder.

In one embodiment, the calcium carbonate compounded with polypropylene to form the compound adhesive 135 should be used in the form of a relatively fine powder. In one embodiment, the calcium carbonate may have a median particle size of 3 microns or less. In one embodiment, the calcium carbonate compounded with polypropylene to form the compound adhesive 135 may be surface treated.

The cost of calcium carbonate by weight is expected to be lower than the cost of polypropylene by weight, so that the use of the compound adhesive 135 can reduce the cost of making paint rollers.

The adhesive 135 is prepared from a compound of polypropylene and calcium carbonate having a calcium carbonate content of 5 to 50 weight percent, and its thermal conductivity is expected to be higher than that of adhesives prepared from polypropylene alone. Thus, adhesives 135 made from polypropylene and calcium carbonate compounds having calcium carbonate contents of 5 to 50 weight percent are expected to cool and set faster than adhesives made from polypropylene alone. Due to the higher thermal conductivity, when the plant 100 is operated with an adhesive 135 made from a compound of polypropylene and calcium carbonate having a calcium carbonate content of 5 to 50% by weight, the overall production capacity of the plant is expected to be higher than with an adhesive 135 comprising more than 95% polypropylene.

Mixed strip material

In one embodiment, the tape 145 is prepared from a compound of polypropylene and calcium carbonate having a calcium carbonate content of 5 to 50 weight percent. In one embodiment, the ribbon 145 contains at least 25% but no more than 45% calcium carbonate. In one embodiment, the ribbon 145 contains at least 25% but no more than 33% calcium carbonate.

In one embodiment, the calcium carbonate compounded with the polypropylene to form the tape 145 should be calcium carbonate in a relatively fine powder form. In one embodiment, the median particle size of the calcium carbonate compounded with the polypropylene to form the tape 145 should be 3 microns or less. In one embodiment, the calcium carbonate compounded with polypropylene to form the tape 145 may be surface treated.

The cost of calcium carbonate by weight is expected to be lower than the cost of polypropylene by weight, so that the use of the tape 135 made from a compound of polypropylene and calcium carbonate can reduce the cost of making a paint roller.

The thermal conductivity of the tape 145 made from a compound of polypropylene and calcium carbonate having a calcium carbonate content of 5-50 wt% is expected to be higher than the thermal conductivity of an adhesive made from polypropylene alone. Because the adhesive 135 has a higher thermal conductivity because of the use of a tape 145 made from a compound of polypropylene and calcium carbonate having a calcium carbonate content of 5-50% by weight, rather than using a tape 145 made from more than 95% polypropylene, it is expected to set more quickly, thereby allowing for a higher overall throughput of the apparatus 110 than if a tape 145 having a polypropylene content of more than 95% were used.

Covering material

In one embodiment, the cover 125 has a fabric back and a velour outer surface (e.g., a knitted or woven cover material), and the fabric back of the cover 125 contains interstitial pores through which the adhesive 135 can flow, particularly when compressed by the belt 120. In one embodiment, the cover is made of a microfiber material, which microfiber cover 125 also contains interstitial pores through which the adhesive 135 can flow, particularly when compressed by the belt 120.

In one embodiment, the cover 125 has a velour or microfiber outer surface and a smooth or uniformly imprinted back surface formed of polypropylene.

In one embodiment, the cover 125 has a velour or microfiber outer surface and a smooth or uniformly imprinted back surface formed from a compound of polypropylene and calcium carbonate having a calcium carbonate content of 5 to 50% by weight. In one embodiment, the cover 125 contains at least 25% but not more than 45% calcium carbonate. In one embodiment, the cover 125 contains at least 25% but not more than 33% calcium carbonate.

In one embodiment, the calcium carbonate compounded with the polypropylene to form the back of the cover 125 should be calcium carbonate in a finer powder form. In one embodiment, the median particle size of the calcium carbonate compounded with the polypropylene to form the back side of the cover 125 should be 3 microns or less. In one embodiment, the calcium carbonate compounded with the polypropylene to form the back side of the cover 125 may be surface treated.

The cost of calcium carbonate by weight is expected to be lower than the cost of polypropylene by weight, so that the use of the back side of the cover 125 made from a compound of polypropylene and calcium carbonate can reduce the cost of manufacturing a paint roller.

The thermal conductivity of the back side of the cover 125 made from a compound of polypropylene and calcium carbonate having a calcium carbonate content of 5 to 50 wt% is expected to be higher than the thermal conductivity of an adhesive made from polypropylene alone. Because the cover 125 uses a back side made from a polypropylene and calcium carbonate compound having a calcium carbonate content of 5-50 wt% rather than using a back side made from more than 95% polypropylene, the cover 125 has a higher thermal conductivity, and therefore the adhesive 135 is expected to set more quickly, resulting in a higher overall throughput of the device 110 than if the cover 125 were used with a back side comprising more than 95% polypropylene.

Use of compound materials

In accordance with the present invention, the apparatus 110 may be operated using an adhesive 135 made from a polypropylene and calcium carbonate compound having a calcium carbonate content of 5-50% by weight, using a tape 145 made from a polypropylene and calcium carbonate compound having a calcium carbonate content of 5-50% by weight, and/or using a cover 250 backed from a polypropylene and calcium carbonate compound having a calcium carbonate content of 5-50% by weight. When more than one part is made from a compound of polypropylene and calcium carbonate having a calcium carbonate content of 5 to 50 weight percent, the percentage of calcium carbonate in the compound forming the adhesive 135, the tape 145, and the back of the cover 250 can be the same or different from one another.

In any compound having a calcium carbonate content of 5 to 50 wt%, the calcium carbonate is not expected to melt when compounding the polypropylene with the calcium carbonate. As noted above, the resulting compound is expected to have a higher thermal conductivity. The scope of the present invention includes variations in the amount of calcium carbonate such that the thermal conductivity can be controlled to some extent, or the desired thermal conductivity or range of thermal conductivities can be achieved by varying the percentage of calcium carbonate in the compound, as is known to those skilled in the art.

The compound of polypropylene and calcium carbonate used in the adhesive 135, tape 145, and/or cover 125 is expected to achieve other properties, including enhanced rigidity, as compared to the use of polypropylene alone. The increased rigidity may make the paint roller feel stronger or harder, which may enhance its performance as a paint roller. In addition, in many cases, harder or stronger paint rollers have a higher selling price. The stiffness can be controlled to some extent or the desired stiffness or range of stiffness can be achieved by varying the percentage of calcium carbonate in the compound, as is known to those skilled in the art.

Fig. 2 illustrates an apparatus 200 for forming a composite paint roller cover 250 with a compound backing. The roller 220 may be advanced to the (stapled) shelf 230 using a spring, gravity, or other methods, as is known to those skilled in the art. The layer of compound adhesive 210 is dispensed onto a roller 220 by an applicator 205, moved between the roller 220 and a rack 230 (e.g., a trellis), or moved between the roller 220 and another roller (not shown). The layer of compound adhesive 210 dispensed onto the roller 220 can be 0.010 "-0.020". In one embodiment, the compound adhesive 210 is a polypropylene and calcium carbonate compound having a calcium carbonate content of 5 to 50 weight percent. In one embodiment, the adhesive compound contains at least 25% but not more than 45% calcium carbonate. In one embodiment, the adhesive compound contains at least 25% but not more than 33% calcium carbonate. The calcium carbonate should be relatively non-abrasive to the processing machinery.

The cover material 215 is pushed forward along the shelf 205 under the roller 220 with the pile side of the cover material 215 facing downward. The cover material 215 may have a pile side and a fabric backing that is porous and has sufficient porosity to allow penetration of the compound adhesive 210. The cover material 215 and the layer of compound adhesive 210 are brought together as they pass between the surface of the drum 220 and the frame 230. As adhesive layer 210 passes under roller 220, its roller side may be calendered or uniformly imprinted (e.g., embossed) by roller 220 to form a uniform or smooth adhesive layer surface 225.

In one embodiment, the roller 220 applies a pressure such that the compound adhesive 210 and the cover material 215 are held together. In one embodiment, the pressure is sufficient to force the compound adhesive 210 into the interstitial spaces on the fabric back side of the cover material 215. The resulting composite sheet material 235 may be cut with a cutter 240 to trim away any excess material to form a compounded composite cover material 250 having a non-porous backside.

In one embodiment, the drum 220 may be heated or cooled.

In one embodiment, the apparatus includes an applicator 205 that applies a compounded adhesive 210 formed from a twin screw extruder that thoroughly compounds calcium carbonate from a calcium carbonate source with polypropylene from a polypropylene resin source in pellet form (not shown). The calcium carbonate should be relatively non-abrasive to the twin screw extruder.

The positioning and angular orientation of the applicator 205 may be varied. In one embodiment, the applicator is angled between 30 and 60 degrees relative to a vertical axis, within a few inches of the middle of the drum 220. In another embodiment, the applicator 205 is positioned within 30 degrees (+/-) of a vertical axis for dispensing adhesive such that the adhesive layer 210 first contacts the upper half of the roller 220. In another embodiment, the applicator 205 is positioned within 30 degrees (+/-) of a horizontal axis for dispensing adhesive such that the adhesive layer 210 first contacts the lower half of the roller 220. Changes in the angular orientation of the applicator 205, as well as its distance from and orientation to the drum, are included within the scope of the present invention and are known to those skilled in the art.

Fig. 3 illustrates a paint roller manufacturing apparatus 300. A strip of material 345 comprising polypropylene is helically wound around the mandrel 340 held on the base 350. The mandrel may be cooled by a cooler (not shown). A second strip of material 348 comprising polypropylene is helically wound around the first strip 345. An adhesive 335 comprising polypropylene is applied to the outer surfaces of the strips 345, 348 by applicator 330. The cover 325 is also helically wrapped around the mandrel 350 over the strips 345, 348 and the adhesive 335. A helical belt 320 driven by rollers 320a, 320b applies pressure to the covering material and moves the tubular assembly 310 down the mandrel 350. A fly away cutter (fly away saw)305 may cut the tubular assembly 310 into usable segments (not shown) or further cut for making a final paint roller.

In one embodiment, the applicator 330 applies a compounded adhesive 335 formed from a twin screw extruder that sufficiently compounds calcium carbonate from a calcium carbonate source with polypropylene from a polypropylene resin source in pellet form (not shown). When a twin screw extruder is used, the calcium carbonate should be relatively non-abrasive to the extruder.

The apparatus 300 may be operated according to the present invention using an adhesive 335 made from a polypropylene and calcium carbonate compound having a calcium carbonate content of 5-50% by weight, using a strip 345 made from a polypropylene and calcium carbonate compound having a calcium carbonate content of 5-50% by weight, using a second strip 348 made from a polypropylene and calcium carbonate compound having a calcium carbonate content of 5-50% by weight, and/or using a covering 325 backed by a polypropylene and calcium carbonate compound having a calcium carbonate content of 5-50% by weight. When more than one part is made from a compound of polypropylene and calcium carbonate having a calcium carbonate content of 5 to 50 weight percent, the percentage of calcium carbonate in the compound forming the back of the adhesive 335, strip 345, second strip 348 and cover 325 may or may not be the same.

Variations in the amount of calcium carbonate are included within the scope of the present invention so that the thermal conductivity can be controlled to some extent, or the desired thermal conductivity or range of thermal conductivities can be achieved by varying the percentage of calcium carbonate in one or more of the compounds, as is known to those skilled in the art. The stiffness can be controlled to some extent or the desired stiffness or range of stiffness can be achieved by varying the percentage of calcium carbonate in these compounds, as is known to those skilled in the art.

Fig. 4 illustrates a paint roller manufacturing apparatus 400. A strip 448 of material comprising polypropylene is helically wound around a mandrel 440 held on a base 450. The mandrel may be cooled by a cooler (not shown). A second strip of material 445 comprising polypropylene is helically wound around the first strip 448. The heaters 460, 455 may employ heating elements or open flames to heat the outer surfaces of the strips 448, 445, respectively (as opposed to (vis-a-vis) wound mandrels). The heat generated by the heater 460 is sufficient to cause the outer surfaces of the strips 448, 445 to become tacky or liquefy or melt. (although shown as being a distance from the mandrel, in one embodiment, the heaters 460, 450 should be placed as close as possible to where the strips 448, 445 contact the mandrel.) the cover 415 is also wrapped helically around the outer surface of the second strip 445 on the mandrel 440. The helical belt drive 420 applies inward pressure to the cover material 415 and moves the assembly down the mandrel 440. A fly away cutter (fly away saw)405 may cut the assembly into usable segments (not shown) or further cut for making a final paint roller.

The apparatus 400 may be run according to the present invention using a strip 448 made from a polypropylene and calcium carbonate compound having a calcium carbonate content of 5-50 wt.%, using a second strip 445 made from a polypropylene and calcium carbonate compound having a calcium carbonate content of 5-50 wt.%, and/or using a cover 415 backed by a polypropylene and calcium carbonate compound having a calcium carbonate content of 5-50 wt.%. When more than one part is made from a compound of polypropylene and calcium carbonate having a calcium carbonate content of 5-50% by weight, the percentage of calcium carbonate in the compound forming the strips 448, 445 and the back of the cover 415 may or may not be the same.

Variations in the amount of calcium carbonate are included within the scope of the present invention so that the thermal conductivity can be controlled to some extent, or the desired thermal conductivity or range of thermal conductivities can be achieved by varying the percentage of calcium carbonate in one or more of the compounds, as is known to those skilled in the art. The stiffness can be controlled to some extent or the desired stiffness or range of stiffness can be achieved by varying the percentage of calcium carbonate in these compounds, as is known to those skilled in the art.

Fig. 5 illustrates an apparatus 500 suitable for preparing a paint roller having a preformed core. The apparatus 500 includes a rotating mandrel 510, a support 560 that runs on a fixed track 570 and supports a covering material guide 550, and a heater 530. A preform core 540 comprising polypropylene is placed adjacent to the mandrel 510. The heater 530 is activated to heat soften the outer surface of the preform core so that it can bond to the back of the cover 520. The cover 520 is helically wrapped around the core by rotation of the mandrel and movement of the support 560. The cover 520 is substantially completely wrapped around the preform core 540 by rotation of the mandrel 510 and movement of the support 560.

In accordance with the present invention, the apparatus 500 may be operated using a preform core 540 made from a polypropylene and calcium carbonate compound having a calcium carbonate content of 5 to 50 weight percent and/or using a cover 250 having a backside made from a polypropylene and calcium carbonate compound having a calcium carbonate content of 5 to 50 weight percent. When more than one part is made from a compound of polypropylene and calcium carbonate having a calcium carbonate content of 5 to 50% by weight, the percentage of calcium carbonate in the compound forming the back of the core 540 and the covering 520 may be the same or different from each other.

Variations in the amount of calcium carbonate are included within the scope of the present invention so that the thermal conductivity can be controlled to some extent, or the desired thermal conductivity or range of thermal conductivities can be achieved by varying the percentage of calcium carbonate in one or more of the compounds, as is known to those skilled in the art. The stiffness can be controlled to some extent or the desired stiffness or range of stiffness can be achieved by varying the percentage of calcium carbonate in these compounds, as is known to those skilled in the art.

A compound of polypropylene and calcium carbonate having a calcium carbonate content of 5-50% by weight may be used in place of polypropylene to make paint rollers without departing from the invention. Other methods of making paint rollers according to the present invention are known to those skilled in the art.

In certain embodiments of the invention, the benefits are: controlling the thermal conductivity of the compound material to accelerate throughput and/or accelerate set time; material properties such as rigidity are controlled to make stronger, more expensive paint rollers.

The above embodiments and preferred conditions are illustrative of the present invention. This patent is neither necessary nor intended to outline or define every possible combination or embodiment. The inventors have disclosed sufficient information to enable those skilled in the art to practice at least one embodiment of the invention, and disclose the invention in its best mode heretofore contemplated by the inventors. The foregoing description and drawings are merely illustrative of the invention, which may vary in composition, structure and steps without departing from the scope of the invention as defined in the appended claims.

Exemplary embodiments are shown in the drawings

In one embodiment, the present invention is a method of making a paint roller. A strip of material is helically wound around a mandrel to form a helically wound strip. The tape is formed from a compound of polypropylene and calcium carbonate having a calcium carbonate content of 5-50% by weight. The wound strip is pushed forward along the mandrel. An adhesive layer is applied to the outer surface of the wound strip. The wound strip and the adhesive layer are then helically wrapped with a strip of cover material to bond the cover material strip to the wound strip to form a paint roller.

In another embodiment, the present invention is a method of making a paint roller. A strip of material is helically wound around a mandrel to form a helically wound strip. The wound strip is pushed forward along the mandrel. The adhesive is formed by mixing polypropylene and calcium carbonate. The compound contains 5-50 wt% calcium carbonate. An adhesive layer is applied to the outer surface of the wound strip. The wound strip and the adhesive layer are then helically wrapped with a strip of cover material to bond the strip of cover material to the wound strip to form a paint roller.

In another embodiment, the present invention is a method of making a paint roller. A strip of material is helically wound around a mandrel to form a helically wound strip. The tape is formed from a compound of polypropylene and calcium carbonate having a calcium carbonate content of 5-50% by weight. The wound strip is pushed forward along the mandrel. The adhesive is formed by mixing polypropylene and calcium carbonate. The compound contains 5-50 wt% calcium carbonate. An adhesive layer is applied to the outer surface of the wound strip. The wound strip and the adhesive layer are then helically wrapped with a strip of cover material to bond the strip of cover material to the wound strip to form a paint roller.

In another embodiment, the present invention is a method of continuously making a multi-strip laminated paint roller. The inner and outer strips of material are helically advanced along the mandrel in offset relation to the mandrel. Wherein at least one of the tapes is formed from a compound of polypropylene and calcium carbonate having a calcium carbonate content of from 5 to 50% by weight. An adhesive layer is applied between the two strips and to the outer surface of the outer strip. The outer strip is wrapped with a cover and a pressure is applied to the cover before the liquid polypropylene layer hardens and sets, such that the cover and the two strips are held together along the mandrel to form a continuous laminated paint roller.

In another embodiment, the present invention is a method of continuously making a multi-strip laminated paint roller. The inner and outer strips of material are helically advanced along the mandrel in offset relation to the mandrel. The adhesive material is formed by compounding polypropylene with calcium carbonate, and the compound contains 5-50 wt% of calcium carbonate. An adhesive material is applied between the two strips and to the outer surface of the outer strip. The outer strip is wrapped with a cover and a pressure is applied to the cover before the adhesive material hardens and sets, such that the cover and the two strips are held together along the mandrel to form a continuous laminated paint roller.

In another embodiment, the present invention is a method of continuously making a multi-strip laminated paint roller. An inner and outer strip of material offset from the mandrel are helically advanced along the mandrel, at least one of the strips being formed from a compound of polypropylene and calcium carbonate having a calcium carbonate content of from 5 to 50% by weight. The adhesive material is formed by compounding polypropylene and calcium carbonate. The compound contains 5-50 wt% calcium carbonate. An adhesive material is applied between the two strips and to the outer surface of the outer strip. The outer strip is wrapped with a cover and a pressure is applied to the cover before the liquid polypropylene layer hardens and sets, such that the cover and the two strips are held together along the mandrel to form a continuous laminated paint roller.

In another embodiment, the instant invention is a method of making a composite cover material. The pile material of the original width is moved. The pile material has a pile side and a fabric back, wherein the fabric back is porous, has interstitial spaces or interstices. The adhesive is formed by mixing polypropylene and calcium carbonate. The compound contains 5-50 wt% calcium carbonate. An adhesive layer is applied to the fabric back of the velour material. The adhesive layer is cured to form a composite sheet material having a soft pile face and a non-porous back face. The composite sheet material is cut longitudinally to form one or more strips of composite cover material having a second width. The composite cover material is formed having an inner surface and an outer surface, the outer surface comprising pile fibers and the inner surface comprising a non-porous layer bonded thereto.

In another embodiment, the present invention is a method of making a paint roller having a core comprised of one or more materials. The adhesive material is formed by compounding polypropylene and calcium carbonate. The compound contains 5-50 wt% calcium carbonate. An adhesive material is applied between the cover material and the one or more materials comprising the paint roller core. The binder material hardens and solidifies to form the paint roller.

In another embodiment, the instant invention is a method of making a laminated paint roller. A polypropylene-containing tape is helically wound about a mandrel to form a helically wound tape, the tape having an outer surface. The wound strip is pushed forward in a spiral along the mandrel. A layer of polypropylene-containing adhesive is applied to the outer surface of the wrapped strip. The wrapped tape and adhesive layer are then wrapped with a strip of composite cover material. The method of forming the composite cover material includes the following steps. A porous velour material having a velour face and a textile bottom face and having a width is provided. The pile material with a certain width is moved with the bottom surface of the fabric facing upwards. The back layer is formed by mixing polypropylene and calcium carbonate, and the mixture contains 5-50 wt% of calcium carbonate. Applying a backing layer to the moving fabric bottom surface of said pile material having a width such that the backing layer has one side in contact with the moving fabric bottom surface of the material and another side not in contact with the moving pile material, said layer being in a molten state at the time of application. Before the layer hardens and solidifies, pressure is applied to the other side of the layer to smooth the other side of the polypropylene layer and to hold the layer and the fabric bottom side of the pile material together, thereby forming a composite material having a smooth or uniformly imprinted non-porous side and a pile side, wherein the pile is firmly secured to the composite material. Once the back layer is no longer in a molten state, the composite material having a width is cut into strips, thereby forming a composite cover material having an inner surface of smooth or uniformly imprinted non-porous polypropylene and a pile side. The composite cover material prepared using the above method is then used to form a laminated paint roller. Applying a pressure from the side without the composite cover material such that the composite cover material, the adhesive layer, and the non-porous polypropylene material strip are held together, thereby laminating the smooth inner surface of the composite cover material to the outer surface of the non-porous polypropylene strip.

In another embodiment, the instant invention is a method of making a laminated paint roller. An inner strip of thermoplastic material is helically wound about a mandrel to form a helically wound inner strip, the inner strip having an outer surface. A second strip of thermoplastic material is helically wound about a mandrel offset from the inner strip to form a second helically wound strip, the second strip having an inner surface and an outer surface. The wound inner and second strips are pushed forward along the mandrel. The adhesive is formed by compounding polypropylene and calcium carbonate, and the compound contains 5-50 wt% of calcium carbonate. An adhesive layer is applied to the outer surface of the wrapped inner strip and the outer surface of the wrapped second strip. The wrapped second strip and the layer of adhesive applied to the wrapped second strip are then wrapped with a strip of composite cover material. The composite cover material has an inner surface and an outer surface, the outer surface comprising a pile fabric and the inner surface comprising a smooth, substantially non-porous, polypropylene-containing backing. Applying a pressure from the side without the composite cover material such that the composite cover material, the adhesive layer, the inner strip, and the second strip are held together, thereby laminating the inner surface of the composite cover material to the outer surface of the second strip and laminating the inner surface of the second strip to the outer surface of the inner strip.

In another embodiment, the present invention is a method of continuously making a multi-strip laminated paint roller. The inner and outer strips of material are helically advanced along the mandrel in offset relation to the mandrel. Wherein at least one of the tapes is formed from a compound of polypropylene and calcium carbonate having a calcium carbonate content of from 5 to 50% by weight. The outer surfaces of the inner and outer strips face away from the mandrel. The outer surfaces of the inner and outer bands are heated to liquefy one of the outer surfaces of the bands. The outer strip is wrapped with a cover and a pressure is applied to the cover before the liquefied layer hardens and solidifies, such that the cover and the two strips are held together along the mandrel to form a continuous laminated paint roller.

In another embodiment, the present invention is a cold core process for making a paint roller from a predetermined length of a hollow core of a chilled, preformed thermoplastic material wherein the chilled hollow core is forged with its associated cover to form a single unitary body. A chilled hollow core is provided. The chilled hollow core is formed from a blend of polypropylene and calcium carbonate having a calcium carbonate content of 5-50% by weight. A mandrel having an outer diameter is provided. The mandrel receives and contacts the chilled hollow core in a sliding manner. The chilled hollow core is rotated. The outer surface of the rotating cold-hard thermoplastic hollow core is heated to a sufficiently high temperature by applying a separate heat source to cause a subsequently applied covering to adhere to the outer surface. A cover is then placed over the outer surface of the heated thermoplastic hollow core such that the cover and the heated outer surface are bonded together to form the paint roller.

Results of further observations

In addition to the above discussion, experiments were conducted with different proportions and materials to obtain some further observations, and the following are inventions and other embodiments of this further observation. The experimental polypropylenes were 3462-US, 4920WZ-US and 6823MZ-US from Total Petrochemicals of Houston, Tex. The MFI of the polypropylene resins described herein is available from general petrochemicals.

Calcium carbonate

The use of unrefined calcium carbonate in combination with polypropylene, such as calcium carbonate that is not surface treated, enhances the strength of the resulting paint roller product relative to the combination of refined calcium carbonate and polypropylene. Thus, in one embodiment, the calcium carbonate mixed with the polypropylene to form the compound adhesive 135 (FIG. 1) may be unrefined calcium carbonate. In one embodiment, the unrefined calcium carbonate used is in the form of a relatively fine powder. In one embodiment, the calcium carbonate may have a median particle size of 3 microns or less.

In one embodiment, unrefined calcium carbonate and polypropylene may be mixed together using a twin screw extruder (not shown) to form the compound adhesive 135. The twin screw extruder may receive a supply of polypropylene resin in pellet form and a separate supply of calcium carbonate.

Proportion and composition of mixed adhesive

Experiments were carried out with respect to the proportion of calcium carbonate, which previously was considered to be preferably 5 to 50% by weight. As noted above, the cost by weight of calcium carbonate is generally lower than the cost by weight of polypropylene, and thus, as the proportion of calcium carbonate increases, the raw material cost of the compounded adhesive decreases. Today, polypropylene resins may typically cost $ 0.64/pound, while suitable calcium carbonates may cost $ 0.09/pound. Using these representative costs, the raw material cost required to make a compounded adhesive with a 5% calcium carbonate content by weight is about $ 0.6125/pound; the raw material cost required to make a compounded adhesive with a calcium carbonate content of 50 wt% is about $ 0.365/pound; the raw material cost required to make a compounded adhesive having a calcium carbonate content of 60% by weight is about $ 0.31/pound. However, the compounding process of the material itself has a cost, and the main factor of the savings is: (i) the cost of polypropylene resin is different from that of calcium carbonate; and (ii) the percentage of calcium carbonate that can be used.

Experiments using a compounded adhesive 135 (see fig. 1) made from a polypropylene resin having a calcium carbonate content of about 60 wt.% gave acceptable results. In one embodiment, the adhesive 135 is a compound of polypropylene and calcium carbonate having a calcium carbonate content of 50 to 66 weight percent. In one embodiment, the compound adhesive 135 contains at least 55% but not more than 65% calcium carbonate. In one embodiment, the compound adhesive 135 is a polypropylene and calcium carbonate compound having a calcium carbonate content of about 60% by weight.

Acceptable results were obtained using an experiment with a compounded adhesive 335 (see fig. 3) made from a polypropylene resin having a calcium carbonate content of about 56% by weight. In one embodiment, the adhesive 335 is a compound of polypropylene and calcium carbonate having a calcium carbonate content of at least 50% by weight but not more than 60% by weight. In one embodiment, the compound adhesive 335 is a polypropylene and calcium carbonate compound having a calcium carbonate content of about 56% by weight.

The pelletized polypropylene resin 6823MZ-US used to prepare the adhesive was first tested to have a melt flow index ("MFI") of about 32. For further testing, a 32MFI resin was compounded with a 60% calcium carbonate mixture to form a compounded adhesive 135. The MFI of the resulting compound adhesive 135 was about 14.4. Although the compounded adhesive may be extruded from the applicator 130, the low MFI makes the extrusion laborious and the extruded material has a high viscosity. The paint roller resulting from the above compound appears stronger when non-refined calcium carbonate is used instead of surface treated calcium carbonate. When the same 32MFI resin was compounded with the same 60% calcium carbonate mixture to form the adhesive 335 (see fig. 3), the MFI of the compounded adhesive 335 appeared to be too high to create a smooth flow from the applicator 330.

Polypropylene resin 4920WZ-US was tried. The pelletized polypropylene resin 4920WZ-US used to make the adhesive was then further tested to have a melt flow index ("MFI") of about 105. For the next test, a 105MFI resin was compounded with a 60% calcium carbonate mixture to form a compounded adhesive 135. The MFI of the resulting compound adhesive 135 was about 28.8. With a 105MFI resin, there is no significant pressure on the extruder when the compound adhesive 135 is extruded from the applicator 130 because the compound adhesive 135 has a viscosity suitable for use with the applicator 130. Also, when using unrefined calcium carbonate instead of surface treated calcium carbonate, the resulting paint roller is significantly stronger from the above compound. When the same 105MFI resin was compounded with the same 60% calcium carbonate blend to form a compounded adhesive 335 (see fig. 3), the MFI also appeared to be too high to form a smooth flow from the applicator 330.

Since the vendor does not have a polypropylene resin with an MFI higher than 105, for the next test, the 105MFI resin was mixed with a 56% calcium carbonate mixture to form a compound adhesive 335. The MFI of the resulting compounded adhesive 335 was about 32. With a 105MFI resin, there is no significant pressure on the extruder when the compound adhesive 335 is extruded from the applicator 330 because the compound adhesive 335 has a viscosity suitable for use with the applicator 330. As previously mentioned, the paint roller obtained from the above compound appears significantly stronger when non-refined calcium carbonate is used instead of surface treated calcium carbonate. As an alternative to reducing the proportion of calcium carbonate to 56%, acceptable results could be achieved using a polypropylene resin with a higher MFI (e.g. an MFI of about 120) and 60% calcium carbonate.

Composition of the strip

The strap material 145, 345, 348, 445, 448 may be prepared using a compound of polypropylene and calcium carbonate with a composite adhesive 135, 335. In one embodiment, a sheet material (not shown) made from a compound of polypropylene and calcium carbonate is cut longitudinally to produce strips 145, 345, 348, 445, 448. In one embodiment, the thickness of the sheet material is determined by a continuous roll. Due to the use of rollers to control thickness, the MFI of the polypropylene/calcium carbonate compound may be significantly lower than that required using the compound adhesive 135, 335. In one embodiment, the 4.1MFI polypropylene resin 3462-US is blended with about 60 weight percent calcium carbonate. The resulting polypropylene/calcium carbonate compound, having an MFI of about 2, was able to be brought to the desired thickness by means of a continuous roller. Almost any desired strip thickness can be achieved. In one embodiment, a sheet of material of polypropylene/calcium carbonate compound having a thickness of about 10 mils, 15 mils, 20 mils, or 25 mils may be cut longitudinally into one or more strips 145, 345, 348, 445, 448.

In one embodiment, the calcium carbonate used to prepare the sheet material that can be cut into strips is non-refined calcium carbonate.

Composite cover material

Returning to fig. 2, shown is an apparatus 200 for forming a composite paint roller cover 250 having a compound backing. The compounded adhesive layer 210 is dispensed through the applicator 205. The dispensed compounded adhesive layer 210 may be dispensed onto a roll 220 or directly onto a cover material 215. In one embodiment, the compound adhesive layer 210 is 0.010 "to 0.020". In one embodiment, the compound adhesive 210 is a polypropylene and calcium carbonate compound having a calcium carbonate content of at least 50% by weight but not more than 66% by weight. The MFI of the polypropylene/calcium carbonate compound can be varied by replacing polypropylene resins with higher or lower MFI, and also by varying the calcium carbonate ratio. The use of a polypropylene resin with a higher MFI results in a polypropylene/calcium carbonate compound with a higher MFI when the same proportion of calcium carbonate is used. Similarly, by reducing the percentage of calcium carbonate used in a polypropylene/calcium carbonate compound, the MFI of the resulting compound can be reduced. Based on the above, it is known to those skilled in the art how to change the MFI of the polypropylene/calcium carbonate compound layer 210 so that it can be properly dispensed by the applicator 205.

In one embodiment, the cover material 215 has a soft pile face and a fabric back that is porous and has sufficient interstitial spaces to allow compound adhesive 210 to penetrate. In one embodiment, the MFI of the compound adhesive 210 is greater than 2. In one embodiment, the MFI of the compound adhesive 210 ranges from 14 to 105. In one embodiment, the required MFI is about 70 or 70 to allow the compound 210 to fully penetrate to the fabric backside of the cover material 215. A 105MFI polypropylene resin was mixed with 25 wt% calcium carbonate to give a compound adhesive 210 with an MFI of about 70 or 70.

In one embodiment, the apparatus includes an applicator 205 for applying a compound adhesive 210 formed from a twin screw extruder that mixes calcium carbonate from a calcium carbonate source with polypropylene (not shown) from a polypropylene resin source in pelletized form sufficiently to produce a compound comprising at least 50% by weight calcium carbonate.

Exemplary paint roller

Returning to FIG. 1, in one embodiment, the tape 145 comprises polypropylene and has a thickness in the range of 10 mils to 40 mils. In one embodiment, the ribbon 145 has a thickness of about 10 mils, 15 mils, 20 mils, or 25 mils. In one embodiment, the strips 145 may be of other suitable thicknesses.

In one embodiment, the tape 145 is prepared from a polypropylene/calcium carbonate compound having a calcium carbonate content of at least 50% by weight but not more than 66% by weight. In one embodiment, the tape 145 is made from a polypropylene/calcium carbonate compound having a calcium carbonate content of about 60% by weight. For a tape 145 made from a polypropylene/calcium carbonate compound having a calcium carbonate content of at least 50 wt%, the thermal conductivity is expected to be higher than that of a tape made from polypropylene alone, or higher than that of a tape made from a polypropylene/calcium carbonate compound having a calcium carbonate content of less than 50 wt%. Because the tape 145 made from a compound of polypropylene and calcium carbonate having a calcium carbonate content of at least 50 wt.% is used has a higher thermal conductivity, the adhesive 135 is expected to set more quickly, resulting in a higher overall throughput of the apparatus 100 than if a tape 145 comprising more than 50% polypropylene were used.

In one embodiment, the adhesive 135 comprises polypropylene and is applied to a layer having a thickness of 10 mils to 40 mils. In one embodiment, adhesive layer 135 has a thickness of about 10 mils, 15 mils, 20 mils, or 25 mils. In one embodiment, adhesive layer 135 may be other suitable thicknesses.

In one embodiment, the adhesive 135 is prepared from a polypropylene/calcium carbonate compound having a calcium carbonate content of at least 50% by weight but not more than 66% by weight. In one embodiment, the adhesive 135 is prepared from a polypropylene/calcium carbonate compound having a calcium carbonate content of about 60% by weight. For adhesives 135 made from a polypropylene/calcium carbonate compound having a calcium carbonate content of at least 50 wt%, the thermal conductivity is expected to be higher than that of adhesives made from polypropylene alone, or higher than that of adhesives made from a polypropylene/calcium carbonate compound having a calcium carbonate content of less than 50 wt%. Because the adhesive 135 made from a compound of polypropylene and calcium carbonate having a calcium carbonate content of at least 50 wt.% is used has a higher thermal conductivity, it is expected to set more quickly, and thus, the apparatus 100 has a higher overall throughput than if an adhesive 135 containing more than 50% polypropylene was used.

In one embodiment, the back side of the composite overlay 125 comprises polypropylene, and the back side comprising polypropylene is on a layer having a thickness of 10 mils to 40 mils. In one embodiment, the thickness of the back layer of the composite overlay material 125 is about 10 mils, 15 mils, 20 mils, or 25 mils. In one embodiment, the back side of the composite cover material 125 can have other suitable thicknesses.

In one embodiment, the back side of the composite cover material 125 is formed from a polypropylene/calcium carbonate compound having a calcium carbonate content of at least 50% by weight but not more than 66% by weight. In one embodiment, the back side of the composite cover material 125 is formed from a polypropylene/calcium carbonate compound having a calcium carbonate content of about 60% by weight. The thermal conductivity of the back side of the composite cover material 125 formed from a polypropylene/calcium carbonate compound having a calcium carbonate content of at least 50 wt.% is expected to be higher than the thermal conductivity of a back side made from polypropylene alone, or higher than the thermal conductivity of a back side made from a polypropylene/calcium carbonate compound having a calcium carbonate content of less than 50 wt.%. Because the composite cover 125 used, having a back side formed from a compound of polypropylene and calcium carbonate having a calcium carbonate content of at least 50% by weight, has a higher thermal conductivity, the adhesive 135 is expected to set more quickly, resulting in a higher overall throughput of the apparatus 100 than if the composite cover 125 used, having a back side formed from a compound of polypropylene and calcium carbonate containing more than 50% polypropylene.

The following table shows exemplary paint rollers that will be used in the following discussion.

	Covering article	Adhesive agent	Strip tape
				Example A1	0/0％	10/0％	20/0％
Example A2	10/0％	10/0％	20/0％

The following table shows exemplary paint rollers that may be formed in accordance with the invention described herein. The "cover" column refers to the cover material 125 used in the embodiments, the "adhesive" column refers to the adhesive 135 used in the embodiments, and the "tape" column refers to the tape 145 used in the embodiments. For each column, the entries reflect the thickness in mils, and the percentage by weight of calcium carbonate compounded with polypropylene to form the part. The thickness in mils in the "cover" column reflects the thickness of the layer 135 used to form the composite cover 125, and the entry in the "cover" column showing a thickness of 0 reflects the use of a cover material rather than a composite cover material.

	Covering article	Adhesive agent	Strip tape
				Example B1	0/0％	10/60％	20/60％
Example B2	10/0％	10/60％	20/60％
				Example B3	10/25％	10/60％	20/60％

Examples a1 and B1 are paint rollers of the same thickness, however, the characteristics of paint roller B1 are significantly improved over a 1. Paint roller B1 is stronger and of better quality than paint roller a 1. In addition, the polypropylene used for paint roller B1, which was 30 mils thick, was only 40% of that used to make paint roller a1 (excluding any polypropylene in the cover stock).

Similarly, examples a2 and B2 are paint rollers of the same thickness, however, the characteristics of paint roller B2 are significantly improved over a 2. Paint roller B2 is stronger and of better quality than paint roller a 2. In addition, the polypropylene used for paint roller B2, which was 40 mils thick, was only 55% of the polypropylene used to make paint roller a2 (excluding any polypropylene in the cover stock). In fact, paint roller B1 was good compared to paint roller a2, which used only 30% polypropylene.

Notably, paint roller B3 was best seen in all embodiments, and used less than half as much polypropylene as roller a2, and just over half as much polypropylene as roller a 1.

Many other variations are possible. For example, compounded adhesives and strips formed from polypropylene compounded with calcium carbonate are not necessarily used. Furthermore, it is not necessary to use a composite cover material formed from a polypropylene/calcium carbonate compound. Using (i) a compounded tape, a (ii) compounded adhesive, or (iii) a composite cover material formed from a polypropylene/calcium carbonate compound, a stronger roll can be made with less polypropylene than using the same component formed from non-compounded polypropylene.

Returning to fig. 3, in one embodiment, the strips 345, 348 comprise polypropylene and each has a thickness of 10 mils to 40 mils. In one embodiment, the strips 345, 348 each have a thickness of about 10 mils, 15 mils, 20 mils, or 25 mils. In one embodiment, the strips 345, 348 may be of other suitable thicknesses. Each strip 345, 348 need not have the same thickness.

In one embodiment, at least one of the strips 345, 348 is made from a polypropylene/calcium carbonate compound having a calcium carbonate content of at least 50% by weight but not more than 66% by weight. In one embodiment, at least one of the strips 345, 348 is made from a polypropylene/calcium carbonate compound having a calcium carbonate content of about 60% by weight. For tapes 345, 348 made from a polypropylene/calcium carbonate compound having a calcium carbonate content of at least 50 wt.%, the thermal conductivity is expected to be higher than for tapes made from polypropylene alone, or higher than for tapes made from a polypropylene/calcium carbonate compound having a calcium carbonate content of less than 50 wt.%. Because the at least one strip 345, 348 made from a compound of polypropylene and calcium carbonate having a calcium carbonate content of at least 50% by weight is used has a higher thermal conductivity, the adhesive 335 is expected to set faster, resulting in a higher overall throughput of the apparatus 100 than if strips 345, 348 comprising more than 50% polypropylene were used.

In one embodiment, the adhesive 335 comprises polypropylene and is applied to a layer having a thickness of 10 mils to 40 mils. In one embodiment, the thickness of the adhesive layer 335 is about 10 mils, 15 mils, 20 mils, or 25 mils. In one embodiment, the adhesive layer 335 may have other suitable thicknesses.

In one embodiment, the adhesive 335 is prepared from a polypropylene/calcium carbonate compound having a calcium carbonate content of at least 50% by weight but not more than 66% by weight. In one embodiment, the adhesive 335 is prepared from a polypropylene/calcium carbonate compound having a calcium carbonate content of about 60% by weight. For adhesives 335 made from polypropylene/calcium carbonate compounds having a calcium carbonate content of at least 50 wt.%, thermal conductivity is expected to be higher than adhesives made from polypropylene alone, or adhesives made from polypropylene/calcium carbonate compounds having a calcium carbonate content of less than 50 wt.%. Because the adhesive 335 made from a compound of polypropylene and calcium carbonate having a calcium carbonate content of at least 50 wt.% is used has a higher thermal conductivity, it is expected to set faster, and thus, the apparatus 100 has a higher overall throughput than if an adhesive 335 containing more than 50% polypropylene was used.

In one embodiment, the back side of the cover 325 comprises polypropylene and the back side comprising polypropylene is on a layer having a thickness of 10 mils to 40 mils. In one embodiment, the thickness of the back layer of composite overlay material 325 is about 10 mils, 15 mils, 20 mils, or 25 mils. In one embodiment, the back side of the composite cover material 325 may have other suitable thicknesses.

In one embodiment, the back side of the composite cover material 325 is formed from a polypropylene/calcium carbonate compound having a calcium carbonate content of at least 50% by weight but not more than 66% by weight. In one embodiment, the back side of the composite cover material 325 is formed from a polypropylene/calcium carbonate compound having a calcium carbonate content of about 60% by weight. For a composite cover 325 having a back side formed from a polypropylene/calcium carbonate compound having a calcium carbonate content of at least 50 wt%, the thermal conductivity is expected to be higher than a back side made from polypropylene alone, or higher than a back side made from a polypropylene/calcium carbonate compound having a calcium carbonate content of less than 50 wt%. Because the composite cover 325 with the back side formed from a compound of polypropylene and calcium carbonate having a calcium carbonate content of at least 50% by weight is used has a higher thermal conductivity, the adhesive 335 is expected to set more quickly, resulting in a higher overall throughput of the apparatus 100 than if the composite cover 325 with the back side formed from a compound of polypropylene and calcium carbonate containing more than 50% polypropylene were used.

The following table shows exemplary paint rollers that will be used in the following discussion.

	Covering article	Adhesive agent	Strip 1	Strip 2
					Example C1	0/0％	10/0％	10/0％	10/0％
Example C2	10/0％	10/0％	10/0％	10/0％
					Example C3	10/0％	10/0％	20/0％	20/0％
Example C4	0/0％	10/0％	20/0％	20/0％

The following table shows exemplary paint rollers that may be formed in accordance with the invention described herein. The "cover" column refers to the cover material 325 used in the examples, the "adhesive" column refers to the adhesive 335 used in the examples, the "tape 1" column refers to the tape 345 used in the examples, and the "tape 2" column refers to the tape 348 used in the examples. As noted above, for each column, the entries reflect the thickness in mils, and the (weight) percentage of calcium carbonate compounded with polypropylene to form the part. The thickness in mils in the "cover" column reflects the thickness of the layer 335 used to form the composite cover 325, and the entry in the "cover" column showing a thickness of 0 reflects the use of a cover material rather than a composite cover material.

	Covering article	Adhesive agent	Strip 1	Strip 2
					Example D1	0/0％	10/56％	10/60％	10/60％
Example D2	10/0％	10/56％	10/60％	10/60％
					Example D3	10/25％	10/56％	10/60％	10/60％
Example D4	10/25％	10/56％	20/60％	20/60％

Examples C1 and D1 are paint rollers of the same thickness, however, the properties of paint roller D1 are significantly improved over C1. Paint roller D1 is stronger and of better quality than paint roller C1. In addition, the polypropylene used for the core of paint roller D1, which was 40 mils thick, was only 42% of that used to make paint roller C1 (excluding any polypropylene in the cover material).

Example D2 produced a paint roller with good properties and hardness. This roll is good compared to example D1 because it has an additional 10 mil thickness. In addition, example D2 was good not only compared to example C1, but also to example C2, even to example C3, the barrel core thickness of example C2 being the same (50 mils), whereas the barrel core of example C3 was 70 mils and twice as much polypropylene was used. Example D3 is an even better paint roller, while example D4 is a premium paint roller. It is noteworthy that, although the barrel core thickness of example D4 was the same as that of example C3, it used only 46% polypropylene.

As mentioned above, many other variations are possible. For example, compounded adhesives and tapes formed from polypropylene compounded with calcium carbonate are not necessarily used. In addition, both strips are not necessarily formed of compound adhesive. Furthermore, it is not necessary to use a composite cover material formed from a polypropylene/calcium carbonate compound. Using (i) a compounded tape, (ii) a compounded adhesive, or (ii) a composite cover material formed from a polypropylene/calcium carbonate compound, respectively, enables the use of less polypropylene to produce a stronger roller than using the same component formed from non-compounded polypropylene.

In addition, the dual-ribbon 60 mil core of example C4 was found to provide about the same mass as the single-ribbon 40 mil core of example A2, which used only about 37% polypropylene. Also of note is that the two-ribbon 50 mil core of example D2 provides a stronger roller than the two-ribbon 60 mil core prepared according to example C4.

Returning to fig. 4, in one embodiment, one or both of the strips 445, 448 may be prepared from a compound of polypropylene and calcium carbonate having a calcium carbonate content of at least 50% by weight but not more than 66% by weight. Similarly, in one embodiment, the cover 415 may have a back side made from a compound of polypropylene and calcium carbonate having a calcium carbonate content of at least 50% by weight but not more than 66% by weight. As noted above, the percentage of calcium carbonate used in the compound used to form the strips 448, 445 and the back side of the cover 415 may or may not be the same as each other.

In one embodiment, the strips 445, 448 are made from a polypropylene and calcium carbonate compound having a calcium carbonate content of about 60 wt.%, while the back surface of the cover 415 is made from a 105MFI polypropylene and unrefined calcium carbonate compound having a calcium carbonate content of about 25 wt.%.

Returning to fig. 5, the apparatus 500 may be operated according to the present invention using a preform core 540 made from a compound of polypropylene and calcium carbonate having a calcium carbonate content of at least 50% by weight but not more than 66% by weight and/or using a cover 520 backed from a compound of polypropylene and calcium carbonate having a calcium carbonate content of 5-66% by weight. When more than one part is made from a compound of polypropylene and calcium carbonate, the percentage of calcium carbonate in the compound forming the back of the core 540 and the covering 520 may be the same or different from each other. In one embodiment, the core 540 is made from a polypropylene and calcium carbonate compound having a calcium carbonate content of about 60% by weight, and the back of the cover is made from a polypropylene and calcium carbonate compound having a calcium carbonate content of about 25% by weight.

As noted above, variations in the amount of calcium carbonate are included within the scope of the present invention, whereby the thermal conductivity can be controlled to some extent, or the desired thermal conductivity or range of thermal conductivities can be achieved by varying the percentage of calcium carbonate in one or more compounds, as is known to those skilled in the art. The stiffness can be controlled to some extent or the desired stiffness or range of stiffness can be achieved by varying the percentage of calcium carbonate in these compounds, as is known to those skilled in the art.

A compound of polypropylene and calcium carbonate having a calcium carbonate content of 50-60 wt% may be used in place of polypropylene to make paint rollers without departing from the invention. Other methods of making paint rollers according to the present invention are known to those skilled in the art.

In certain embodiments of the invention, the benefits are: controlling the thermal conductivity of the compound material can increase production speed and/or shorten setting time; controlling the properties of the material, such as rigidity, allows for stronger, more expensive paint rollers to be made.

The above embodiments and preferred conditions are illustrative of the present invention. This patent is neither necessary nor intended to outline or define every possible combination or embodiment. The inventors have disclosed sufficient information to enable those skilled in the art to practice at least one embodiment of the invention, and disclose the invention in its best mode heretofore contemplated by the inventors. The foregoing description and drawings are merely illustrative of the invention, which may vary in composition, structure and steps without departing from the scope of the invention as defined in the appended claims. Thus, while the invention has been particularly shown and described with reference to embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention. The above embodiments are illustrative of the present invention. This patent is neither necessary nor intended to outline or define every possible combination or embodiment.

Claims (19)

1. A method of making a paint roller, comprising the steps of:

helically winding a strip of material around a mandrel to form a helically wound strip, said strip being formed from a blend of polypropylene and calcium carbonate, wherein the calcium carbonate is present in an amount of from 5% to 66% by weight;

advancing the wound strip along the mandrel;

applying a layer of adhesive to the outer surface of the wound strip;

the wound strip and the adhesive layer are then helically wrapped with a strip of cover material to bond the strip of cover material to the wound strip to form a paint roller.

2. The method of making a paint roller according to claim 1, wherein the strip is formed from a compound of polypropylene and calcium carbonate having a calcium carbonate content of at least 50% but not more than 66% by weight.

3. The method of making a paint roller according to claim 1, wherein the strip is formed from a compound of polypropylene and calcium carbonate having a calcium carbonate content of at least 5% but not more than 50% by weight.

4. A method of making a paint roller, comprising the steps of:

helically winding a strip of material around a mandrel to form a helically wound strip;

pushing the wound strip forward along the mandrel;

compounding polypropylene and calcium carbonate into an adhesive to form a compound containing at least 5% but not more than 66% calcium carbonate by weight;

applying a layer of adhesive to the outer surface of the wound strip;

the wound strip and the adhesive layer are helically wrapped with a strip of cover material to bond the strip of cover material to the wound strip to form a paint roller.

5. The method of making a paint roller according to claim 4, wherein the compound comprises at least 50% but not more than 66% calcium carbonate by weight.

6. The method of making a paint roller according to claim 4, wherein the compound comprises at least 5% but not more than 50% calcium carbonate by weight.

7. The method of making a paint roller according to claim 4, wherein the step of compounding is performed by a twin screw extruder.

8. A method of continuously making a multi-strip laminated paint roller, comprising the steps of:

helically winding inner and outer strips of material along a mandrel, the inner and outer strips being offset from one another, wherein at least one strip is formed from a compound of polypropylene and calcium carbonate having a calcium carbonate content of at least 5% but not more than 66% by weight;

applying a layer of adhesive between the two strips and on the outer surface of the outer strip;

the outer strip is wrapped with a cover and a pressure is applied to the cover before the liquid polypropylene layer hardens and sets, such that the cover and the two strips are held together along the mandrel to form a continuous laminated paint roller.

9. The method of continuously making a multiple strip laminated paint roller according to claim 8, wherein the strips are formed from a compound of polypropylene and calcium carbonate having a calcium carbonate content of at least 50% by weight but not more than 66% by weight.

10. The method of continuously making a multiple strip laminated paint roller according to claim 8, wherein the strips are formed from a compound of polypropylene and calcium carbonate having a calcium carbonate content of at least 5% by weight but not more than 50% by weight.

11. A method of continuously making a multi-strip laminated paint roller, comprising the steps of:

helically winding inner and outer strips of material along a mandrel, the inner and outer strips being offset from one another;

compounding polypropylene and calcium carbonate into an adhesive material to form a compound containing at least 5% but not more than 66% calcium carbonate by weight;

applying an adhesive material between the two strips and on the outer surface of the outer strip;

the outer strip is wrapped with a cover and a pressure is applied to the cover before the adhesive material hardens and sets, such that the cover and the two strips are held together along the mandrel to form a continuous laminated paint roller.

12. The method of continuously making a multiple-strip laminated paint roller according to claim 11, wherein the compound contains at least 50% but not more than 66% calcium carbonate by weight.

13. The method of continuously making a multiple-strip laminated paint roller according to claim 11, wherein the compound contains at least 5% but not more than 50% calcium carbonate by weight.

14. The method of continuously making a multiple strip laminated paint roller according to claim 11, wherein the compounding step is performed by a twin screw extruder.

15. A method of continuously making a multi-strip laminated paint roller, comprising the steps of:

helically winding inner and outer strips of material along a mandrel, the inner and outer strips being offset from one another, wherein at least one strip is formed from a compound of polypropylene and calcium carbonate having a calcium carbonate content of at least 5% but not more than 66% by weight;

compounding polypropylene and calcium carbonate into an adhesive material, the compound containing at least 5% but not more than 66% by weight carbonate;

applying an adhesive material between the two strips and on the outer surface of the outer strip;

the outer strip is wrapped with a cover and a pressure is applied to the cover before the liquid polypropylene layer hardens and sets, such that the cover and the two strips are held together along the mandrel to form a continuous laminated paint roller.

16. The method of continuously making a multiple strip laminated paint roller according to claim 15, wherein the compounding step is performed by a twin screw extruder.

17. A method of continuously making a multi-strip laminated paint roller, comprising the steps of:

helically winding inner and outer strips of material along a mandrel, the inner and outer strips being offset from one another, wherein at least one of the strips is formed from a compound of polypropylene and calcium carbonate having a calcium carbonate content of at least 5% by weight but not more than 66% by weight, the outer surfaces of the inner and outer strips facing away from the mandrel;

heating the outer surfaces of the inner and outer bands to liquefy one of the outer surfaces of the bands;

the outer strip is wrapped with a cover and a pressure is applied to the cover before the liquefied layer hardens and sets, such that the cover and the two strips are held together along the mandrel to form a continuous laminated paint roller.

18. The method of continuously making a multiple-strip laminated paint roller according to claim 17, wherein the compound contains at least 50% but not more than 66% calcium carbonate by weight.

19. The method of continuously making a multiple strip laminated paint roller according to claim 17,

the compound contains at least 5% but not more than 50% by weight calcium carbonate.