Source: https://patents.justia.com/patent/4486200
Timestamp: 2020-01-28 07:31:34
Document Index: 515440132

Matched Legal Cases: ['arts 74', 'arts 50', 'arts 2', 'arts 2', 'arts 35', 'arts 73']

US Patent for Method of making an abrasive article comprising abrasive agglomerates supported in a fibrous matrix Patent (Patent # 4,486,200 issued December 4, 1984) - Justia Patents Search
Justia Patents Impregnating Or Coating An Abrasive ToolUS Patent for Method of making an abrasive article comprising abrasive agglomerates supported in a fibrous matrix Patent (Patent # 4,486,200)
Sep 9, 1982 - Minnesota Mining and Manufacturing Company
A coating composition consisting of 43 parts of a 3:1 solution of methanol:polyamide (available under the trade designation "Elvamide" No. 8063 from the DuPont Company) and 57 parts of a resin composition consisting of 74% non-volatile base-catalyzed phenol-formaldehyde resin was knife coated onto one side of 0.08 mm thick Kraft paper to provide a dry coating thickness of 0.13 mm after heating for 3 minutes at 62.degree. C., 3 minutes at 50.degree. C. and 3 minutes at 95.degree. C. The opposite side of the paper was knife coated in the same manner and with the same composition to provide a 0.1 mm dry coating. The coated paper was then cut into 6 mm squares and a multiplicity of such squares were introduced into a "Rando-Webber" web forming machine with crimped 38 mm staple nylon fibers consisting of 90% 50 denier fibers and 10% 15 denier fibers. The crimped fibers and coated paper squares were formed by the web forming machine into a web weighing 165 g/m.sup.2 with the flakes being distributed throughout the web and covering about two-thirds of the area of the web.
The flake-bearing web was then roll coated with methanol to soften the paper coating and cause the flakes to conform to the fiber surfaces and dried at 65.degree. C. in a hot air oven to bond the flakes to the fibers. The resultant web was then again roll coated with methanol to make the adhered flakes tacky and the web was then passed under a mineral dropping device and 120 grit aluminum oxide mineral (average particle size 125 microns) was dropped into the web and permitted to adhere to the surface of the resin-coated flakes. A rotating beater bar in contact with the paper carrier caused the abrasive particles to be coated on all sides of the resin-coated paper flakes and the web was again passed through the oven at 95.degree. C. and thereafter spray coated with a size resin coating composition consisting of 890 parts diethylene glycol monoethyl ether (available under the trade designation "Carbitol"), 600 parts 74% non-volatile base-catalyzed phenol formaldehyde resin and 120 parts 50% aqueous sodium hydroxide solution. The resultant size-coated web was then passed into a curing oven heated at 150.degree. C. for 3 minutes. The web was then spray coated with the same size resin coating composition on the opposite side and cured at 150.degree. C. for 3 minutes. The resultant product contained 800 g/m.sup.2 abrasive and 235 g/m.sup.2 size resin (dry weight).
*Bonded Nonwoven Web. Fibers consisting of 90% by weight 50 denier and 10% by weight 15 denier 40 mm long crimped nylon staple fibers were air laid with a Rando-Webber machine to provide a web which weighed 167 g/m.sup.2. The web, carried on a paper backing, was roll coated with a resin binder consisting of 60 parts ketoxime-blocked poly-1,4-butylene glycol diisocyanate having a molecular weight of about 1500 (available under the trade designation "Adiprene" BL-16), 7.3 parts methylene dianiline and 32.3 parts 2-ethoxy ethyl acetate solvent (available under the trade designation "Cellosolve" acetate). The resin-coated web was cured by heating at a web speed of 5 m/min in an 18 meter, 2-zone oven having a first zone heated at 130.degree. C. and the second zone heated at 140.degree. C. (equal length zones) to provide 9 mm thick web having a dry resin add on weight of 84 grams per m.sup.2.
Cycle   Weight Loss (g)
No.     Example 1 Control 1  Control 2
1       1.64      1.3        0.36   0.25
2       1.36      1.09       0.58   0.11
3       1.14      0.96       0.65   0.10
4       0.9       0.62       0.38   0.11
5       0.9       0.45       0.65   0.15
6       0.92      0.32       0.32   0.05
7       0.84      0.28       0.13   0.08
8       1.22      --         0.18   0.07
9       0.76      0.4        0.12   0.09
10      0.96      0.3        0.11   0.05
11      0.78      0.28       0.13   0.13
12      0.62      0.32       0.08   0.1
13      0.78      0.2        0.13   0.08
14      0.78      0.38       0.13   0.05
Example    Product Type       Factor
Control 1  set up disc        1.36
Control 2  coated abrasive    1.30
Control 3  nonwoven abrasive  1.49
Example 1  fibrous matrix with abrasive
3M Type "C" coated abrasive
(120 grit aluminum oxide)
nonwoven    3M "Scotch-Brite" cutting and
polishing nonwoven abrasive
disc (180 grit aluminum oxide)
nonwoven    3M "Scotch-Brite" Clean N'Strip
nonwoven abrasive disc (36
grit silicon carbide)
Example No.     Cut (grams) SWF
Control 2       2.42        1.22
Control 3       0.79        2.6
Control 4       1.94        4.08
Example 1       10.54       1.47
Ingredients               Weight
polyurethane prepolymer (available under the
trade designation "Adiprene" BL-16)
methylene dianiline        410
amino functional silane (available under
the trade designation "Z 6020" from the
Dow Corning Corp.)
solvent (available under the trade designation
"Cellosolve" acetate)
The needles were positioned above the conveyor with the needles pointing downward and at an angle of 45.degree. with respect to the direction of web travel. The resin-coated web was conveyed under the needles on a paper carrier at the rate of 1.5 mm per minute and the pump adjusted so that the drops were spaced 1.5 to 3 mm apart in the direction of travel. The resin drops penetrated into the web slightly, substantially retaining their shape and encapsulating filaments in the areas within the web in which they were located. Thereafter 50 grit (300 micron average particle size) aluminum oxide mineral was dropped onto the resin-containing web to impregnate the resin droplet with the abrasive mineral, with the balance of the mineral falling through the web. The web was then cured in a 185.degree. C. oven. The web, hereinafter referred to as "Web 2", contained 265 g of dry resin and 1390 g mineral per m.sup.2. The resulting agglomerates had a major dimension of approximately 5 mm and were roughly spherical in shape.
An abrasive wheel hereinafter referred to as "Example 2" was prepared by first cutting eight 230 mm diameter discs having 16 mm diameter center holes of Web 2 and one disc of Bonded Nonwoven Web as described above with the eight discs directed with their agglomerate-impregnated surfaces in the same direction and the Bonded Nonwoven Web overlying the agglomerate-impregnated surface of the end disc, placing the cut discs on an arbor and dipping the discs in a solution consisting of 12 parts ketoxime-blocked polyurethane prepolymer (available under the trade designation "Adiprene" L-315 blocked with methylethyl ketoxime), 1.8 parts methylene dianiline and 7.7 parts 2-ethoxy-ethyl acetate solvent (available under the trade designation "Cellosolve" acetate). The discs were then rotated on the arbor at 800 rpm to remove excess resin, leaving a dry add on resin weight of 8.7%. The discs were then pressed to a thickness of 25 mm and partially cured under pressure for one hour at 135.degree. C. and completely cured, after removal from the press, by heating at 130.degree. C. for an additional hour. When cooled, the wheel was die cut to provide a diameter of 215 mm with a 32 mm center hole.
A second wheel, hereinafter referred to as "Example 3", was prepared in the same manner utilizing six 230 mm diameter discs of Web 3 by placing the discs on an arbor, dipping the discs into a mixture containing 10.4 parts ketoxime-blocked polyurethane prepolymer (available under the trade designation "Adiprene" L-315 blocked with methylethyl ketoxime, 4.5 parts 35% methylene dianiline in 2-ethoxy-ethyl acetate solvent (available under the trade designation "Cellosolve" acetate) and 0.4 parts lithium stearate, spinning the discs to remove excess adhesive mixture and pressing to a 25 mm thickness and curing by heating in a press for 45 minutes and then without pressure in an oven at 105.degree. C. for 5 hours.
Wheel Examples 2 and 3 were evaluated for abrasiveness against a commercially available nonwoven abrasive 25 mm by 200 mm wheel (hereinafter designated "Control 5") available from the 3M Company under the registered trademark "Scotch-Brite" Cutting and Polishing Wheel, coarse grade having 50 grit (average particle size 300 microns) aluminum oxide abrasive. The test involved employing a floor stand polishing lathe which rotated the wheel against the 50.times.350 mm face of a 6 mm thick 1018 cold rolled steel workpiece which was by means of an attachment fastened to the lathe and forced against the peripheral surface of the wheel at a controlled constant force between the wheel and the workpiece while the workpiece was oscillated 150 mm in the vertical direction and 6 mm in the horizontal direction at a frequency of 50 and 25 cycles per minute respectively and while maintaining the wheel at a constant surface speed throughout the 12 minute cycles. The preweighed workpiece was weighed after each 12 minute cycle to determine the weight loss and the 12 minute abrading operation was repeated for the number of cycles set forth in Table V. The surface temperature of the workpiece was measured after each cycle. For the samples noted in Table V, the surface speed was maintained at 1525 meters per minute and the force at 6.8 kg. Results are shown in Table V below.
Wheel    Cycle   Cut/12 min. (g)
1       4.7          195
2       5.6          190
3       4.7          195
4       4.1          195
1       13.8         195
2       13.4         187
3       13.8         not measured
4       13.4         195
1       42.8         225
2       50.0         215
3       53.6         225
4       57.0         215
Discs having a diameter of 230 mm with a center opening having a diameter of 16 mm were cut from each of the webs and converted to wheels. In each case, 8 discs were placed on an arbor, dipped into the polyurethane prepolymer coating solution described in Examples 2 and 3, spun at about 800 rpm to remove excess resin, pressed to a thickness of 25 mm, cured in a press at 130.degree. C. for one hour and then removed from the press and cured in an oven heated at 140.degree. C. for 21/2 hours. After cooling, the center openings were cut to 32 mm and the wheels hereinafter respectively referred to as "Wheel 4", "Wheel 5" and "Wheel 6", weighed respectively in grams as follows: 352, 375, 355.
Force    Grams Metal
(kg)     Removed    Efficiency
4        2.3      nil        nil       nil
4        4.5       0.05      5         nil
4        6.8      1.3        6.5       1.66
4        9.1      2.2        5.5       1.61
5        2.3      nil        nil       nil
5        4.5      0.1        0.5       1.69
5        6.8      1.1        5.5       1.58
5        9.1      1.4        3.5       1.64
6        2.3      0.8        4         1.33
6        4.5      1.6        4         1.37
6        6.3      3.7        9.25      1.36
6        9.1      5.0        5.55      1.51
2000 Rev.              Metal Removed
Cycle No. Disc No.     (grams)      W.F.
1         4            0.31         2.27
2         "            0.01         2.95
3         "            0.06         2.95
1         5            0.27         1.89
2         "            0.19         1.89
3         "            0.14         1.89
1         6            0.75         1.36
2         "            0.44         1.34
3         "            0.44         1.52
1         4            1.06         1.96
2         "            0.58         2.05
3         "            0.47         1.83
1         5            0.97         1.47
2         "            0.46         1.49
3         "            0.29         1.44
1         6            1.81         1.3
2         "            1.58         1.29
3         "            1.43         1.27
The size of the abrasive agglomerates of abrasive webs 4, 5, and 6 was determined by burning off the fibers of 77 cm.sup.2 segments of each of the webs in a 480.degree. C. oven for approximately 10 minutes, leaving only the phenolic resin and abrasive mineral. The residual of each web was vibrated gently to remove sharp edges, and seived through a series of progressively smaller screens. Table IX shows the percentage of agglomerates in each size range as compared to the particle size distribution of the 100-150 grit (125 micron) abrasive granules used to make the agglomerates.
(microns)  Particles     Web 4   Web 5 Web 6
6730       --            --      --    9.8
4760       --            --      --    78.1
2380       --            --      --    3.6
1680       --             0.9     0.3  0.5
1190       --             2.9     4.0  0.5
710        --            18.9    21.4  4.6
590        --            23.2    20.4  0.9
300        --            26.1    23.3  0.5
210        --            15.5    17.9  0.3
150        --             6.3     6.9  0.3
150        --             5.5     5.5  0.9
175         2            --      --    --
125        41            --      --    --
100        26            --      --    --
90        17            --      --    --
90        14            --      --    --
A mat of coiled integrated nylon-6 fibers having a weight of 92 grams per m.sup.2, a filament diameter of 280 microns and a thickness of 16 mm made according to the disclosure of U.S. patent application Ser. No. 847,922, filed Nov. 11, 1977, was roll coated with a urethane prepolymer resin solution consisting of 8.9 parts blocked polyurethane prepolymer (available under the trade designation "Adiprene" BL-16), 2.9 parts a 35% solution of methylene dianiline in 2-ethoxy-ethyl acetate solvent (available under the trade designation "Cellosolve" acetate), 0.177 parts amino functional silane (available under the trade designation Z6020 from the Dow Corning Co.), and 1.4 parts xylol. Porous abrasive-containing resin spheres larger than 12 mesh and smaller than 6 mesh (average particle size 1.5 to 3.5 mm), made by dropping granular phenolic resin (available under the trade designation "Varcum" 5485) into hot* tumbling 50 grit (average particle size 300 micron) Al.sub.2 O.sub.3. The resultant abrasive-containing spheres, containing 91% mineral and 9% phenolic resin, were dropped into the adhesive-coated web which was then cured at 150.degree. C. for 6 minutes. The resultant coated web contained 2,430 grams per m.sup.2 abrasive spheres and 30 grams per m.sup.2 polyurethane resin. The web was then sprayed first on one side and then on the other side with an adhesive mixture consisting of 7.7 parts blocked polyurethane prepolymer (available under the trade designation "Adiprene" BL-16), 2.5 parts of a 35% solution of methylene dianiline in 2-ethoxy-ethyl acetate, 0.008 parts amino functional silane (Z6020), 0.61 parts of a mixture of 50% lithium stearate in 50% solvent (available under the trade designation "Cellosolve" acetate), and 2.5 parts xylol, resulting in a dry coating weight of 400 grams per m.sup.2 on one side and 500 grams per m.sup.2 on the other side.
*200.degree.-315.degree. C.
Nine 230 mm diameter discs having 16 mm diameter center holes were cut from the abrasive coated web, placed on an arbor, and dipped in the same adhesive composition to bond the spheres to the web. The discs were spun at 300 rpm to remove excess resin and the nine discs were compressed to 28 mm in a heated press at 140.degree. C. for one hour and removed from the press and heated an additional hour at 135.degree. C. to produce a wheel hereinafter referred to as "Example 7".
The resultant abrasive wheel was evaluated for abrasiveness against a commercially available low-density abrasive wheel made by the assignee of the present application and sold under the trade designation "Scotch-Brite" brand Cutting and Polishing coarse wheel containing 50 grit (300 micron) Al.sub.2 O.sub.3 abrasive mineral hereinabove referred to as "Control 5". The wheels were evaluated on the polishing lathe described above rotating at 1525 surface meters per minute with a 9.1 kg force for four 12 minute test periods, using a new workpiece for each test. The surface temperature of the workpiece was monitored at the center of the abrading area and the amount of metal cut from the workpiece was measured. Results are reported in Table X below.
Wheel    Test    Cut/12 Min. (g)
Workpiece (.degree.C.)
1       7.59          220
2       8.11          223
3       8.28          226
4       7.51          226
1       14.0          188
2       17.0          190
3       17.85         202
4       17.7          202
The Bonded Nonwoven Web described above was conveyed at 1 meter per minute under the needle manifold dropping device described above. In this case all of the needles were bent and secured so that two adjacent needles would deposit one combined drop of resin into the same location on the bonded web. The resin consisted of 10 parts 73% solids base catalyzed thermosetting phenol-formaldehyde resin, 0.2 parts of a 50% aqueous sodium hydroxide solution and 2-ethoxy-ethanol solvent (available under the trade designation "Cellosolve") to reduce the viscosity to 150 cps. About 270 grams per m.sup.2 of cured resin was applied in enlarged drops spaced about 9 mm apart in the cross direction and about 9 mm apart in the machine direction.
The droplet-coated web supported on a paper carrier was then passed under a mineral dropping device which had two application stations with the second station directly over a series of four 25 mm square bars rotating at 375 rpm. At the first mineral dropping station, porous abrasive spheres of 50 grit aluminum Al.sub.2 O.sub.3 were dropped onto the liquid resin droplets. These porous spheres were made by dropping 30-40 mesh granules of phenolic resin (available under the trade designation "Varcum" 5485) into heated 150 grit aluminum oxide particles contained in a 105.degree.-135.degree. C. heated rotary kiln and then adding calcium carbonate to the rotary kiln. The resultant porous abrasive spheres contained 28% phenolic resin, 43% aluminum oxide mineral and 37% calcium carbonate. At the second mineral dropping station, 180 grit (85 micron) Al.sub.2 O.sub.3 individual particles were dropped onto the web. The rotating square bars caused the abrasive particles and the porous abrasive spheres that had passed through the web and were laying on the paper carrier to re-enter the web. Some of these particles and spheres adhered to the resin droplets which already contained some abrasive material. At the first mineral dropping station, 1150 grams per m.sup.2 of the 150 grit (100 micron) porous spheres were added. At the second mineral dropping station, 400 grams per m.sup.2 of the 180 grit particulate mineral were added. The web was then cured by heating in an oven at 150.degree. C. for 7 minutes. The resulting agglomerates had a major dimension of approximately 6 mm and were roughly spherical in shape.
Ingredients                 Weight
Base catalyzed thermosetting phenol-formaldehyde
resin (73% solids)
50% Aqueous sodium hydroxide solution
2-ethoxy ethanol solvent (available under the
trade designation "Cellosolve"
Colloidal silica (available under the trade desig-
nation "Cab-O-Sil" M-5 from the Cabot Corp.)
Aluminum oxide mineral (Grit 180, average particle
size 85 micron)
The mixed slurry was placed in a pressure tank with an agitator, air pressure was utilized to force the slurry inside the perforated screen cylinder, while passing the Bonded Nonwoven Web described above therebelow at 9 meters per minute while rotating the perforated screen cylinder to produce cylindrical shaped agglomerates approximately 6 mm long and 3 mm in diameter at a coating weight of 1015 g per m.sup.2. The resin was then cured in an oven heated at 150.degree. C. for 7 minutes.
Wheel           W.F.   Cut (g)
Control 6       1.65   0.33
Control 7       1.39   1.35
Wheel 8         1.20   2.74
Wheel 9         1.15   1.77
forming within a lofty web comprising undulated filaments bonded at points of mutual contact by depositing in a pattern with an appropriate printing or extruding device a plurality of separated agglomerates formed of a mixture of uncured liquid curable bonding agent and abrasive particles, said agglomerates having an average particle size of at least 2 mm to provide an agglomerate-impregnated web; and
curing said bonding agent to convert said agglomerates to abrasive agglomerates comprising abrasive particles bonded together with said bonding agent, said bonding agent and said abrasive particles being selected to provide an abrasive particle to bonding agent weight ratio of about 1:1 to 20:1.
2. The method of claim 1 also including the steps of cutting segments of the agglomerate-impregnated web to a desired size, stacking the cut segments to form an assembled pile, contacting the assembled pile under pressure with a compacting force, adhering the compacted pile together in a manner which permits retention of the compacted shape after removal of the compacting force, and removing the compacting force.
2284715 June 1942 Benner
2986455 May 1961 Sandmeyer
3127253 March 1964 Smith
3377151 April 1968 Lanham
3871139 March 1975 Rands
3955324 May 11, 1976 Linstrom
3982359 September 28, 1976 Elbel
230115 July 1959 AUX
Patent number: 4486200
Inventors: Raymond F. Heyer (Saint Paul, MN), William R. Lovness (Saint Paul, MN)
Application Number: 6/416,366
Current U.S. Class: Impregnating Or Coating An Abrasive Tool (51/295); 51/400