ABRASIVE ARTICLE AND MANUFACTURING METHOD THEREFOR

Abstract

The present disclosure relates to an abrasive article with a cork backing layer. In addition, the present disclosure relates to a method for producing abrasive articles comprising a cork backing layer.

Claims

1. An abrasive article comprising: a cork backing layer and an abrasive layer.

2. The abrasive article of claim 1 wherein a tie coat layer is disposed onto the cork backing layer, wherein the tie coat layer is between the cork backing layer and the abrasive layer.

3. The abrasive article of claim 1 wherein the abrasive layer comprises abrasive particles and at least one first binder.

4. The abrasive article of claim 1 wherein the abrasive layer comprises a microreplicated abrasive layer.

5. The abrasive article of claim 1 wherein the cork in the cork backing layer backing is selected from natural cork and cork particles with at least one second binder.

6. The abrasive article of claim 5 wherein the second binder is selected from rubber, asphalt, gypsum, adhesives, polymers or a mixture thereof.

7. The abrasive article of claim 6 wherein the cork particles in the cork backing layer is rubber-bonded cork, preferably wherein the rubber-bonded cork comprises neoprene, nitrile or a mixture thereof.

8. The abrasive article of claim 1 wherein the cork backing layer has a thickness of at least 0.1 mm, preferably at least 0.5 mm.

9. The abrasive article of claim 1 wherein the abrasive article is an abrasive belt having a continuous backing layer.

10. The abrasive article of claim 1 wherein the abrasive article is an abrasive disc.

11. A method of making an abrasive article, the method comprising, introducing an abrasive slurry comprising abrasive particles onto a first surface of a cork backing layer at least partially curing the abrasive slurry.

12. The method of claim 11 wherein a tie coat layer is disposed onto the first surface to the cork backing layer before the abrasive slurry is introduced.

13. The method of claim 11 wherein the abrasive slurry further comprises at least one first binder.

14. The method of claim 11 wherein the abrasive slurry is introduced onto a production tool or the production tool is introduced onto the abrasive slurry and wherein the abrasive article and the production tool are separated.

15. The method of claim 14 wherein the production tool has microreplicated features.

Description

[0048] The disclosure will now be described, by way of example only, with reference to the following drawings, in which:

[0049] FIG. 1 is an enlarged cross-section of a coated abrasive article

[0050] FIG. 2 is a perspective of a coated abrasive belt

[0051] FIG. 3 is an enlarged perspective view of the backside of the spliced section of the coated abrasive belt

[0052] FIG. 4 is an enlarged cross-section of a coated abrasive disc

[0053] FIG. 1 illustrates a cross-section of a coated abrasive article 101. The abrasive article 101 comprises an abrasive layer 103. The abrasive layer 103 is an abrasive slurry comprising a plurality of precisely shaped abrasive composites 109, each composite having a predetermined shape and being disposed on a tie-coat layer 105 in a predetermined array. Abrasive composites 109 have a discernible precise shape (e.g., pyramidal) and comprise a plurality of abrasive particles dispersed in a binder. In this embodiment, the binder bonds abrasive composites 109 to a tie coat layer 105 which in turn ensures enhanced adhesion of the abrasive composites 109 to a cork backing layer 107.

[0054] The coated abrasive article 101 is produced by at least partially curing or solidifying the abrasive slurry while the slurry is being held within precisely shaped microreplicated recesses of a production tool. The precisely shaped recesses of the production tool function to mould the abrasive slurry to the desired precise shape. The binder precursor of the abrasive slurry must be at least partially cured or solidified while being held in the precisely shaped recesses so that that the abrasive slurry is “set” and does not lose its precise shape upon removal from the production tool.

[0055] Referring now to FIG. 2, a perspective view of an endless coated abrasive belt 201 is shown. The belt 201 comprises a continuous cork backing layer 203, an abrasive layer 207 and a tie coat layer (not seen). The belt also comprises a splice 205 comprising two ends 211, 213 of a coated abrasive sheet which are joined together to form a joint 209.

[0056] FIG. 3 is an enlarged perspective view of the back side of the spliced section of the coated abrasive belt 301. The ‘back side’ of the coated abrasive article refers to the side of the article not bearing the abrasive layer.

[0057] A splice 319 comprises two ends 315, 317 of a coated abrasive sheet according to the present invention, which are joined together to form a joint 309.

[0058] The coated abrasive sheet 321 comprising the cork backing layer 305 is first cut to a desired length, preferably ranging from 15 cm to about 500 cm. The end 315 is cut such that it is interlocking with end 317 when cut. The ends 315, 317 comprise shaped protrusions such as triangular, rectangular and recesses of corresponding shape to engage with these shaped protrusions. The two ends 315, 317 are preferably cut so that there is minimal gap between the two ends and it is preferred that the ends 315, 317 do not overlap at all.

[0059] A splice adhesive may be added to the surface of the joint 309. This will increase strength of the joint 309.

[0060] A spliced medium 311 is placed over the joint 309. Polymeric films are preferred for splice media. Representative examples of polymeric films suitable for splice media include polyester film, polyamide film, polypropylene film, polyethylene film, polyimide film and polyurethane film. Preferably, the polymeric film is a hot-melt polyurethane film. An example of a suitable polyurethane film is “PU CLEAR HIGH MELT JOIN FILM” available from Habasit UK Ltd, Elland, West Yorkshire, UK. The two ends 315,317 are placed in a laminator such as “MAESTRO 300” available from Ammeraal Beltech, Alkmaar, The Netherlands, and the heated press holds the two ends in place. The heat causes the hot-melt polyurethane film to melt and secure the splice 309 whilst the pressure from the laminator ensures the ends 315, 317 stay interlocked at joint 309.

[0061] FIG. 4 shows an enlarged cross-section of an abrasive disc. The abrasive article 401 comprises an abrasive layer 403. The abrasive layer 403 is an abrasive slurry comprising a plurality of precisely shaped abrasive composites 409, each composite having a predetermined shape and being disposed on a tie-coat layer 405 in a predetermined array. Abrasive composites 409 have a discernible precise shape (i.e., pyramidal) and comprise a plurality of abrasive particles dispersed in a binder. In this embodiment, the binder bonds abrasive composites 409 to a tie coat layer 405 which in turn ensures enhanced adhesion of the abrasive composites 409 to a first surface 415 of a cork backing layer 407.

[0062] The coated abrasive article 401 is produced by at least partially curing or solidifying of the present invention while the abrasive slurry is being held within precisely shaped microreplicated recesses of a production tool. The precisely shaped recesses of the production tool function to mould the abrasive slurry to the desired precise shape. The binder precursor of the abrasive slurry must be at least partially cured or solidified while being held in the precisely shaped recesses so that that the abrasive slurry is “set” and does not lose its precise shape upon removal from the production tool.

[0063] A second surface 417 of the cork backing layer 407 comprises a double-sided adhesive tape 421 which is attached to a fabric 419 with integrally formed loops protruding therefrom. These loops will then provide the engagement between the cork backing layer 407 and a backup pad 411 that has a hook fabric 413 affixed thereto. The backup pad 411 may be attached a tool such as a random orbital sander.

EXAMPLES

[0064] The following non-limiting examples will further illustrate the invention, wherein all parts and percentages are by weight unless otherwise indicated.

Materials

[0065] “SR 351” is a trimethylolproprane diacrylate monomer available from Sartomer Company, Exton, Pa., USA.

[0066] “SR 368D” is an isocyanurate triacrylate available from Sartomer Company, Exton, Pa., USA.

[0067] ‘“SR 339C” is a 2-phenoxyethyl acrylate available from Sartomer Company, Exton, Pa., USA.

[0068] “IR-651” is a 2,2-dimethoxy-1,2-diphenyl ethan-1-one photoinitiator available under the trade designation IRGACURE® 651 from BASF Corp., Charlotte, N.C., USA

[0069] “IR-369” is a 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 UV curing agent available under the trade designation IRGACURE® 369 from BASF Corp., Charlotte, N.C., USA.

[0070] “IR-TPO-L” is a 2,4,6-trimethylbenzoylphenyl phosphinate photoinitiator available under the trade designation IRGACURE® TPO-L from BASF Corp., Charlotte, N.C., USA.

[0071] “A-174™” is a gamma-me thacryloxypropyltrimethoxysilane resin modifier available under the trade designation SILQUEST™ A-174™ silane from Witco Corporation, Greenwhich, Conn., USA.

[0072] “OX-50” is a fumed silicon dioxide available under the trade designation AEROSIL® OX 50 from Evonik Industries, Essen, Germany.

[0073] KBF.sub.4 is potassium fluoroborate available from Washington Mills, Manchester, UK.

[0074] “SC24000” is a polymeric dispersant available under the trade designation SOLSPERSE™ 24000 GR/SC from Lubrizol Ltd., Derby, UK.

[0075] “P180” is an aluminium oxide mineral available under the trade designation DURALUM GW 180 Washington Mills, Manchester, UK

[0076] “GC2500” is a green silicon carbide available under the trade designation GC2500 from Fujimi Corp., Elmhurst, Ill., USA.

[0077] “300LSE” is a double-sided adhesive tape available under the trade designation 3M™ Double Coated Tape 93010LE available from 3M Company, St Paul, Minn., USA.

[0078] “Hookit™ II Laminating Backing” is one part of a 2-part fastening system comprising sheet material bearing on one side a multiplicity of erect stems that have flattened distal ends that is made according to U.S. Pat. No. 5,667,540 and manufactured by 3M Company of St. Paul, Minn. The flattened stems are engageable in a fabric material which provides the other part of 2-part fastening system, as described in U.S. Pat. No. 5,962,102.

Testing

[0079] The following materials were used in testing Examples 1-6 and Comparative Example A.

[0080] AOEM clear coated black painted cold roll steel test panels obtained from Advanced Coating Technologies Laboratories, Inc., Hillsdale, Mich. having dimensions of 18 inches by 24 inches.

[0081] Random orbital sander available under the trade designation “3M™ ELITE NON-VACUUM RANDOM ORBITAL SANDER, 28500” from 3M Company, St. Paul, Minn., USA.

[0082] Profilometer available under the trade designation “SURTRONIC S128” available from Taylor Hobson, Inc., Leicester, UK.

Water spray bottle

Stopwatch

[0083] The following materials were used in the testing Example 7 and Comparative Example B.

[0084] Stainless steel test panels obtained from Gtec Engineering Ltd, Atherstone, UK having dimensions of 50 cm by 50 cm with 0.5 cm depth.

[0085] Flat-bed sander available from Surface Technology Products Limited, Birmingham, UK under the trade designation “SURTECH MODEL L84” modified to accommodate a sanding pad.

[0086] Profilometer available under the trade designation “SURTRONIC S128” from Taylor Hobson, Inc., Leicester, UK.

[0087] Table 1 shows the cork backing materials obtained from Advanced Seals & Gaskets Ltd, Dudley, UK.

TABLE-US-00001 TABLE 1 Example Description Thickness (mm) 1 Neoprene-bonded cork 1.5 2 Nitrile-bonded cork 1.5 3 Natural cork 3 4 Neoprene-bonded cork 3 5 Nitrile-bonded cork 3 6 Neoprene-bonded cork 5

[0088] Table 2 shows the backings of Comparative Examples A and B.

TABLE-US-00002 TABLE 2 Example Backing Comparative Example A Latex-coated foam Comparative Example B Fabric

Examples 1-5

[0089] A tie-coat was prepared by mixing one-part IR-651, 39.6 parts SR 368D and 59.4 parts SR 351.

[0090] An abrasive slurry (AS1) was prepared by mixing 19.47 parts SR351, 12.94 parts SR 339, 3.08 parts SC24000, 1.93 parts A-174™, 1.08 parts TPO-L and 61.50 parts GC2500.

[0091] The tie coat was applied to a cork backing sheet and the abrasive slurry was applied to a polypropylene tool having a microreplicated surface, the surface being the reverse pattern of that desired for the shaped abrasive surface. The coated tool was applied to the tie-coat so that contact was established between the tie-coat and the slurry side of the tool. The tool side of the resulting lamination was then exposed to ultra-violet radiation by exposure to a D-bulb at 100% power while moving the backing at 22 meter/minute. The tool was then removed from the fully cured shaped abrasive coating on the tie-coated cork backing.

[0092] This process was repeated for each of Examples 1-5.

[0093] 6″ circular discs were cut from the cork backing sheet and Hookit™ II Laminating Backing ready for testing.

Comparative Example A

[0094] Comparative Example A was a 3M™ TRIZACT™ HOOKIT™ FOAM ABRASIVE DISC 443SA available from 3M Company, St. Paul, Minn., USA laminated to Hookit™ II Laminating Backing.

[0095] The test panels were prepared by first sanding their surfaces with a 3M™ HOOKIT™ FINISHING FILM ABRASIVE DISC 260L, grade P1200 available from 3M Company, St. Paul, Minn., USA. The random orbital sander was operated at 12,000 rpm using moderate but consistent downward pressure. Sanding was started in the upper left-hand corner of the test panel and moved back and forth across the panel from top to bottom. Initial finish (Rz) of the prepared panel was measured using the profilometer. Three to five readings were taken from the panel and an average of these readings was the initial Rz of the test panel. The initial panel weight was measured in grams.

[0096] The test pad was then mounted onto the random orbital sander and was used to finish the prepared panel. Water was sprayed over the panel in a sufficient amount to prevent sticking of the product to the panel. One test disc was used on each panel. Sanding once again started from the upper-left hand corner of the test panel and moved back and forth across the panel from top to bottom. Rz is the average of the highest vertical point to the lowest vertical point of each scratch indent, where four Rz measurements were taken for each sample. Rz was measured after 60 seconds and after 120 seconds. The panel was also weighed after 60 seconds and after 120 seconds to determine the difference in mass from the initial panel weight. The difference was abrasive cut in grams.

[0097] Results are shown in Table 3. It can be seen Examples 1-5 are comparable in both cut and Rz to Comparative Example A. The products were found to be surprisingly easy to handle, with relatively little stiction, i.e. the tendency for the abrasive coating to stick to the workpiece with unwanted results. The cork samples felt more sturdy and secure owing to the strength and rigidity of the cork backing.

TABLE-US-00003 TABLE 3 Average Average Rz Rz cut, cut, (micro- (micro- g after g after meter) meter) Example 60 s 120 s after 60 s after 120 s 1 0.30 0.12 0.8 0.8 2 0.30 0.12 0.7 0.7 3 0.34 0.16 0.8 0.8 4 0.28 0.14 0.7 0.8 5 0.33 0.14 1.0 0.9 Comparative 0.36 0.15 0.7 0.8 Example A

Example 7

[0098] A tie-coat was prepared by mixing one-part IR-651, 39.6 parts SR 368D and 59.4 parts SR 351.

[0099] A first mixture was prepared using mixing 56.49 parts of SR 351 and SR 368D, 1.99 parts OX-50, 1.99 parts A-174 and 38.57 parts KBF.sub.4 in a paddle mixer.

[0100] 42 parts of the first mixture were then mixed with 58 parts of P180 with the paddle mixer. The tie coat was spread across a cork backing of dimensions with a 20 micrometer bar. The slurry was then poured directly onto the cork backing sample of dimension 100 cm by 20 cm and the slurry was spread as evenly as possible with a flat metal spreader bar. A matching length of polypropylene tool was placed on the abrasive slurry such that the reverse microreplicated pattern of that desired for the shaped abrasive surface was facing the abrasive slurry. The cork backing and polypropylene tool were taped together using adhesive masking tape available under the trade designation “3M 501E SPECIALITY HIGH TEMPERATURE MASKING TAPE” from 3M Company, St. Paul, Minn., USA A roller was adopted to push downwards on to the tooling and spread the slurry underneath by hand. A quartz plate was then placed over the top of the tooling and the whole sampled exposed twice to ultra-violet radiation by exposure to a D-bulb at 100% power. The polypropylene tool was removed to leave a microreplicated abrasive surface on the cork backing.

[0101] Samples were cut into sheets measuring 16×10 cm and the samples adhered to a sanding pad using “300LSE”.

Comparative Example B

[0102] Comparative Example B was a 3M™ TRIZACT™ CLOTH BELT 307EA available from 3M Company, St. Paul, Minn., USA. The belt was cut to a 16 cm length and two 5 cm width belt sheets were adhered side by side to a sanding pad using “300LSE”.

[0103] Three abrading steps were conducted each for 1 minute. Sanding was done in one direction from top to bottom across the panel. Rz of the panel was measured after step 2 and step 3 using the profilometer. 3 readings were taken from the panel and an average of these readings was the Rz of the test panel. The initial panel weight was measured in grams. The panels were then weighed after each step to determine the difference in mass from the initial panel weight. The difference was abrasive cut in grams.

[0104] The panels were rotated by 90° after each step such that the sanding lines were adjacent to the previous step. This was so that ridges, from scratches, from the abrasive at each step could be countered more effectively at the next step.

[0105] Step 1: The test panels were sanded with 3M™ CUBITRON™ II CLOTH BELT 947A available from 3M Company, St. Paul, Minn., USA cut to 16 cm by 10 cm and adhered to a sanding pad with “300LSE.

[0106] Step 2: The test panels were sanded with either Example 6 or Comparative Example B.

[0107] Step 3: The test panels were sanded with 3M™ TRIZACT™ CLOTH BELT 307EA A45 available from 3M Company, St. Paul, Minn., USA cut to 16 cm by 10 cm and adhered to a sanding pad with “300LSE.

[0108] Step 1-3 were repeated 3 times for each of Example 6 and Comparative Example B. The average cut results are depicted in Table 4 and average finish results are depicted in Table 5. Cut is higher for Example 6 as the cork provides higher cutting aggression due to its rigidity and relative hardness. Finish is smoother for Example 6 due to the cushioning effect of the cork backing, whereas the thin cloth of Comparative Example B causes a deeper scratch.

TABLE-US-00004 TABLE 4 Average Average Average cut, cut, cut, g after g after g after Example Step 1 Step 2 Step 3 6 0.46 0.3  0.06 Comparative 0.46 0.14 0.2  Example B

TABLE-US-00005 TABLE 5 Rz (micro- Rz (micro- meter) meter) Example after Step 2 after Step 3 6  3.7 6.7 Comparative 11.5 3.3 Example B

[0109] Various modifications and alterations of this invention may be made by those skilled in the art without departing from the scope and spirit of this invention, and it should be understood that this invention is not to be unduly limited to the illustrative embodiments set forth herein.