Surface treating pad having a renewable surface

A surface treating pad having a renewable working surface comprises a base layer upon which is removably fastened at least one unitary stack comprising a plurality of thin layers of lofty nonwoven abrasive material. The layers on the stack are removably fastened together and to the base layer so that individual layers may be easily separated from the stack or from the base layer to expose a fresh surface treating working face without damage to the remainder of the pad. The pads are particularly suited for treating floors.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to surface treating pads, and, more specifically, to 
a novel layered treating pad of lofty low-density abrasive product having 
a plurality of renewable working surfaces. 
2. Prior Art 
The low-density abrasive products of the type defined in U.S. Pat. No. 
2,958,593 and sold under the registered trademark "Scotch-Brite" by the 3M 
Company of St. Paul, MN. have found great commercial success in use as 
floor treating pads. This type of abrasive product is typically formed of 
crimped staple fibers which have been formed into a mat and impregnated 
with resinous binder and abrasive. The pads are available in any of a wide 
variety of types to provide many functions. Some pads are extremely 
abrasive and are desirably used for wax stripping and cleaning floor 
surfaces which are heavily encrusted with soil. Others are mildly abrasive 
and are typically used for floor polishing, with or without the prior 
application of wax. 
The pads of this type are typically cut in a circular shape to be used in 
conjunction with a floor polishing machine. The pads may also be 
rectangular or of other shapes depending upon the equipment with which 
they are to be used. Such machines have a means for engaging or holding a 
pad thereon while rotating the pad against the surface being treated. One 
highly commercially successful engaging means is that described by 
Kleemeier et al is U.S. Pat. No. 3,527,001. 
When used, such pads become soiled on their working surfaces, either with 
soil removed from the surface being treated or because of a wax build-up 
on the working surface of the pad, if the floor pad is used in a spray 
cleaning operation, or a combination of these. Spray cleaning involves 
applying (e.g., by spraying with an aerosol or mechanical sprayer) small 
amounts of liquid cleaner-polish composition on the floor followed by 
passing the machine fitted with the pad over the applied liquid to cause 
cleaning, drying and polishing. After one side of the pad becomes soiled 
it is customary to merely invert the pad and use the opposite side which 
is typically of the same construction as the first side until it too 
becomes soiled. 
Thereafter, the pad is either discarded or attempts are made to rejuvenate 
it. Rejuvenation has been accomplished by washing the pad in a washing 
machine or by merely flushing out the debris of pad with high pressure 
fluids. Washing is not desirable since it weakens the pad and changes its 
performance. Flushing is also not completely desirable since it does not 
remove all of the debris and the pad will not perform after flushing for 
the same length of time or in the same manner as a new pad. 
SUMMARY OF THE INVENTION 
The present invention provides a layered surface treating pad having a 
renewable working surface. The pad of the invention comprises, in 
combination, a base layer and at least one unitary stack comprising a 
plurality of thin layers of lofty nonwoven abrasive material suited for 
use in treating surfaces, e.g., floors. The thin layers of lofty nonwoven 
abrasive material are removably fastened to at least one flat face of the 
base layer and to each other in the stack to provide a unitary layered 
structure which is capable of maintaining such unity during use and yet 
which permits each thin layer to be easily separated therefrom to expose a 
fresh treating surface of the next layer, when desired, without damage to 
the remainder of the pad. 
One preferred embodiment of the treating pad of the invention has a stack 
of thin layers removably fastened to both the top flat face and to the 
bottom flat face of the base layer. Another preferred embodiment of the 
treating pad of the invention includes only one stack of thin layers 
adhered to the bottom flat face of the base layer which most preferably 
has at least its top flat face marked to distinguish it from the working 
surface of the pad. 
Fastening may be by any conventional means which provide for the temporary 
attachment of the layers during and permits removal of individual layers 
after use. The most preferred means of removably fastening the layers 
together and the stack to the base layer is by means of an adhesive binder 
applied to that surface of each of the thin layers which faces toward the 
base layer. The adhesive is selected and applied so that it will be 
retained on the surface of the layer to which it was applied and so that 
it will not leave any significant residue upon the surface to which each 
layer is adhered, upon removal. Other fastening means are hereinafter 
disclosed.

DETAILED DESCRIPTION 
Referring to FIGS. 1 and 2 of the drawing, a surface treating pad according 
to the present invention in the form of a disc 10 is shown having a base 
layer 11 which has a top substantially flat face 12 and a bottom 
substantailly flat face 13 and stack 14 consisting of thin removably 
fastened together layers 15 of lofty nonwoven abrasive material removably 
fastened to bottom face 13. 
FIG. 2 shows another embodiment of a pad of the invention in pad 20 which 
has a base layer 21 and stacks 22 and 23 consisting of removably fastened 
together layers 24 of lofty low-density abrasive material, with one stack 
removably fastened to each face of base layer 21. The top removable layer 
24a is shown in a partially removed position. 
The base layer is required in the pad of the invention to provide a 
sufficiently thick pad residue which will remain after removal of all or 
most of the lofty non-woven abrasive layers, as they become soiled. 
Several thin, lofty nonwoven abrasive layers may provide the base layer, 
but the preferred pad has a thicker base layer. If the pad were composed 
entirely of the thin layers of lofty nonwoven abrasive material, the last 
few layers would generally be unuseable since they would be too thin to 
use on conventional floor treating machines. Such conventional machines 
have engaging means which typically protrude into the floor treating pad 
to retain the pad on the machine during use. If such protrusions extend 
through the layer of lofty nonwoven abrasive materials they may mar the 
floor being treated and would also likely interfere with the performance 
of the abrasive material against the floor. Therefore, a base layer 
preferably is at least about 3 mm thick to avoid this situation. 
Typically, the base layer will be about 3 mm to about 13 mm thick, 
preferably about 3 mm to about 10 mm. The base layer should not be so 
thick so as to add unnecessary thickness to the pad, resulting in an 
unduly thick pad after the addition of the removable thin layers. The 
maximum thickness of the pad is typically dictated by the particular 
machine employed and generally does not go beyond 75 mm thick. 
The base layer may be composed of any suitable material upon which the 
removable layers of lofty nonwoven abrasive material may be fastened which 
permits engagement by the appropriate engaging means of the floor 
polishing machine. The base layer may be formed of felt, fibrous pads, 
mats of bonded crimped staple fibers, or lofty mats of nonwoven abrasive 
material. The preferred material for forming the base layer is a lofty 
nonwoven abrasive material which is a similar composition as the removable 
layers, thus providing a last renewed surface of the same construction as 
the removable thin layers, after the last layer is removed. 
The thin removable layers of lofty nonwoven abrasive material will have a 
thickness on the order of about 0.5 mm to about 20 mm, preferably from 
about 1 mm to about 5 mm. Typically, the number of layers of nonwoven 
material will be at least 3, otherwise it is generally not economical to 
produce a layered pad. The number of layers should not be so great as to 
make the pad unduly thick for the reasons stated above. Typically, the 
number of layers will be on the order of 5 to about 20. 
No particular modification of the lofty nonwoven abrasive material 
presently employed for treating floors is needed, other than producing it 
in the desired thickness. The product specifications of such lofty 
nonwoven abrasive material is well known in the floor treating art. The 
method of producing the loft nonwoven abrasive material of the invention 
is well described in assignee's U.S. Pat. No. 2,958,593, the disclosure of 
which is incorporated herein by reference for such teaching. 
A means of removably fastening the layers in the stack together and the 
stack to the base layer may include any of a wide variety of known 
fastening means. Suitable fastening means include adhesive bonding, e.g., 
by the application of adhesive films, either as a solid self-supporting 
layer of adhesive material or as adhesive coatings on either side of a 
backing layer, or by bonding or application of a coatable adhesive 
composition, ultrasonic/welding, flame bonding, mechanical means such as 
threads, hooks, staples, and the like. It should be noted that the use of 
adhesive films provides a particular advantage in that it does not permit 
migration of soil and other residues generated in cleaning through the 
layer being used to the unused layers of the treating pad. 
The most preferred fastening means is by the application of a suitable 
coatable adhesive at the interface of the layers to be fastened together, 
taking care that the adhesive is applied to the surface of the layer which 
will not become the treating surface. In that case, the adhesive should be 
such that it will be substantially retained on the surface of the layer to 
which it is applied and, upon removal, it will not leave any significant 
residue upon the surface to which the layer is adhered. If the adhesive 
separates or splits at the interface, it should be selected so that the 
residue will not interfere with the performance of the pad. The adhesive 
should also permit easy removal of each layer, when desired, without 
destruction of the remainder of the pad or any other adverse effect upon 
the newly exposed treating surface. 
The materials employed in the treating pad of the invention should, of 
course, be compatible for use in typical cleaning operations where, for 
example, detergent-containing aqueous solutions, waxing solutions and 
cleaning compositions are often used. The materials should be capable of 
withstanding some minor heat build-up as may be generated by the rotation 
or other movement of the pad against the surface being treated. 
The pad of the invention may be made by fastening together large sheets of 
the appropriate materials to form a laminated structure which then can be 
die cut to produce the desired shapes. The layers are generally compacted 
together to provide a compression of approximately 10 to 80 percent 
during the fastening step. Die cutting may be accomplished by use of 
conventional die cutting equipment such as a circular blade of the 
appropriate diameter. The pad of the invention may be made in any 
convenient diameter such as are typically employed for use in conventional 
rotary floor treating machines and for other machines which employ 
rotating pads of this type. 
The layers of lofty low-density abrasive product should be capable of being 
removed individually from the stack without damage to the pad. That is, 
the layer should peel away from the stack to expose the next underlying 
layer without causing any other layers to become delaminated or to 
disintegrate. The layer should be sufficiently fastened together, however, 
to prevent them from being displaced as they are rotated in use in a 
machine. Additionally, the layers should remain when the pad is handled, 
for example, in removing the pad from a shipping carton and placing it on 
the machine. 
Adhesive materials which have been found to be particularly suitable for 
use in fastening the layers of the pad of the invention together are 
conveniently applied by converting them to a liquid state, e.g., by 
melting or by mixing with a suitable compatible solvent, and coating them, 
using conventional coating techniques over one surface of a large sheet of 
the thin, lofty low-density abrasive product. Suitable coating techniques 
for such adhesive compositions include spray coating, dip coating, roll 
coating, e.g., using rotogravure rolls, and the like. The layers are then 
pressed together and permitted to dry, die cut into the appropriate shape 
and are ready for use. 
Suitable adhesive compositions for this purpose include urea-formaldehyde 
resins, phenol-formaldehyde resins, epoxide resins, polyurethane resins, 
and acrylate resins. A particularly satisfactory adhesive composition is 
provided by a 60:37:3 styrene -2- ethyl hexyl acrylate - acrylic acid 
terypolymer which may be dissolved in an aromatic solvent such as toluene 
to provide a coatable solution. A satisfactory coatable solution having a 
Brookfield viscosity of 20,000 cps is provided by a 65.8 weight percent 
solution of the terpolymer in toluene. Other adhesive compositions which 
will hold the layers together and permit release, when desired, will also 
be useful. 
Adequate adhesion between layers for maintaining the integrity of the pad 
in use and permitting release when desired will be possible if the force 
required to delaminate the layers is on the order of 9 to 450 grams per 25 
mm width. This force may be conveniently measured by pulling the layers 
apart, for example, by placing one segment of laminate in one jaw of an 
Instron tensile testing device and the other layer in the other jaw and 
pulling the two layers apart at an angle of 180.degree.. 
If the force is less than about 9 grams per 25 mm width, the layers may not 
remain laminated together during use. If the force is greater than about 
450 grams per 25 mm width, adhesion between layers may exceed the cohesive 
strength of the layer and one or more layers may suffer internal failure 
as removal is attempted. The force values are, of course, a function of 
the cohesive strength of the layers and, for a layer with a higher 
cohesive strength, the maximum adhesion may exceed 450 grams per 25 mm 
width. 
The amount of adhesive applied to the surface of the lofty nonwoven 
abrasive material will be sufficient to provide proper binding as 
described above yet permit separation of layers, where desired. The amount 
of adhesive will typically vary between about 0.5 mg/cm.sup.2 to 20 
mg/cm.sup.2. 
A light compaction, at least to hold individual layers in contact with one 
another during adhesion, may be necessary. Increased pressure is used when 
permanent compaction is desired. Pressure combined with heat results in a 
compressed pad which can retain the thickness to which it has been 
compressed. 
Various modifications may be made in the pad of the invention. For example, 
where the pad comprises a single stack of removable nonwoven abrasive 
layers bonded to only one side of the base layer, such as depicted by 
FIGS. 1 and 2, it may be convenient to mark the top of the base layer as 
the first working face of the stack of layers to distinguish the two sides 
of the pad so that a user will not be confused and commence use of the pad 
with the top surface of the base layer on the floor. For this purpose, it 
may be desirable to print "top" on the top or "bottom" on the bottom or 
some similar designation. Alternatively the entire base layer or its top 
surface may be colored differently from the thinner nonwoven abrasive 
layers. It may also be convenient to have alternate nonwoven abrasive 
layers of a different color, e.g., the uneven numbered layers are of one 
color such as red and the even numbered layers another color such as 
white, so that the user would not mistakenly remove two layers at once. 
Additionally, alternate nonwoven abrasive layers may be of different 
abrasiveness. For example, the odd numbered layers may be of a coarser 
abrasive grade for wax removal and the even numbered layers may be of a 
finer abrasive grade for polishing. Other modifications are also possible. 
EXAMPLES 
The invention is further illustrated by the following examples, wherein all 
parts are by weight unless otherwise specified. 
The specific components of Examples 1-10 are described in Tables 1 and 2. 
The base layer in each of the examples was a nonwoven web having the same 
composition as the thin removable layers. The nonwoven webs were formed of 
a web of crimped fibers employing a "Rando Webber" web forming machine, 
roll coating the web with the designated prebonding resin, curing the 
prebonding resin by passing the coated web through a forced air oven 
heated at a temperature in the range of about 125.degree. C. to about 
160.degree. C. with a residence time of approximately 3 to 10 minutes. The 
coated web was then passed under a spraying device where the working face 
of the web was spray coated with the designated top coating and then 
passed into a forced air oven for curing at a temperature between 
125.degree. C. and 160.degree. C. for a residence time of 6 to 10 minutes. 
After the top coating has been applied and cured, a layer to layer bonding 
resin or bonding material was applied. Such application was either by roll 
coating or by spray coating, but in all cases, the layer to layer bonding 
resin was applied to the nonworking face of the layer. In those examples 
which employed a film or tape bonding layer, the films or tapes were 
simply laid over the nonworking face of the individual layers. The other 
layers were then stacked with the adhesive coated sides facing toward the 
base layer, the stack placed between two aluminium plates and compressed 
to their final desired thickness by employing bolts deployed in holes 
located adjacent the corners of each of the plates to compress the stack 
to the desired thickness, until curing of the adhesive was accomplished. 
Certain of the pads prepared were tested for utility under normal working 
conditions against a conventional solid disc-shaped pad of approximately 
the same abrasiveness. The conventional test pad was sold by the 3M 
Company under the trade designation "Scotch-Brite" 51 Line "Red Buffer" 
pad. This pad normally cleans from about 50 to about 100 square meters, 
before loading with soil so as to become no longer useful because of 
adverse effects. Of the pads tested, each layer of the test pads of the 
examples provided substantially the same utility, when tested under the 
same conditions. 
3 TABLE 1 
Example No. (cm)Diameter(cm)ThicknessAveragePAD BaseExcludingNumb 
er ofAverageThickness(cm)LAYERS 
##STR1## 
##STR2## 
##STR3## 
##STR4## 
1 21 3.5 10 0.5 P.sup.1 50 5 6.3 A-red 2.7 B-red 2.5 rubber base 
adhesive.sup.4 0.34 2 30.5 2.8 9 0.3 " " " 2.1 " 0.8 " 1.7 rubber 
base adhesive.sup.4 1.1 3 45.7 5 20 0.8 " " " 5.2 C-red 2.9 D-red 3.8 
rubber base adhesive.sup.4 1.3 4 9.5 2.5 6 0.8 " " " 5.2 " 2.9 " 
3.8 double coated carpet tape -- 5 35.6 2.5 7 0.8 " " " 5.2 " 2.9 " 
3.8 rubber-base adhesive.sup.4 1.7 6 40.6 3.8 10 1.2 " 75% 50 5.6 8.0 
E-white 8.2 F-red 6.1 rubber-base adhesive.sup.4 1.7 25% 15 3.8 7 
40.6 4.1 10 1.1 N.sup.2 75% 50 5.3 9.0 G-white 3.4 H-red 
6.5 rubber-base adhesive.sup.4 1.0 25% 15 3.8 8 43 3.9 10 1.1 
P.sup.1 75% 50 5.6 6.3 I-gold 3.2 J-gold 6.5 styrene-2-ethylhexyl 1.5 
25% 15 3.8 acrylate-acylic acid terpolymer " 
75% 50 5.6 3.4 E-red 1.7 F-red 5.9 styrene-2-ethylhexyl 1.5 25% 
15 3.8 acrylate-acrylic acid terpolymer 9 21 2.5 10 
0.8 N.sup.2 80% 200 5.5 8.6 K-black 5.7 L-black 13.4 rubber-base 
adhesive.sup.4 -- 20% 15 3.8 10 43 2.6 10 0.4 P.sup.1 75% 50 5.6 
2.5 E-white 1.3 F-red 6.7 rubber-base adhesive.sup.4 0.6 25% 15 
3.8 
.sup.1 P = crimped polyester staple; 
.sup.2 N = crimped nylon staple; 
.sup.3 See Tbl. II for compositions identified 
.sup.4 Tackified divinyl benzene crosslinked styrene butadiene rubber sol 
under the trade designation "Spray Adhesive No. 77" by the 3M Company 
TABLE II 
__________________________________________________________________________ 
Top Top Top Top Top Top 
Prebond 
Coat 
Prebond 
Coat 
Prebond 
Coat 
Prebond 
Coat 
Prebond 
Coat 
Prebond 
Coat 
RAW MATERIALS 
(A) (B) 
(C) (D) 
(E) (F) 
(G) (H) 
(I) (J) (K) (L) 
__________________________________________________________________________ 
Xylol 1.4 -- -- -- -- -- -- -- 1.36 -- -- -- 
Saturated Polyester 
1.2 -- 6.1 -- 24.1 -- -- -- 2.4 -- -- -- 
Desmophene 1770 
Trimethylol propane and 
0.05 -- 0.25 -- 1.0 -- -- -- 0.1 -- -- -- 
Glycerol (1:1) 
Talc 0.62 1.8 
3.2 3.2 
12.7 18.4 
-- 9.5 
1.27 0.84 
-- -- 
Red pigment solution I 
0.064 
-- 0.318 
-- -- -- -- -- -- -- -- -- 
(22 parts red pigment: 
78 parts vehicle) 
Polyisocynate sold under 
1.035 
-- 5.2 -- 21 -- -- -- 2.1 -- -- -- 
the trade designation 
"Mondur" CB-75 
Antifoam agent 
.0004 
-- -- -- -- -- .014 -- -- -- .245 
-- 
Silica 400 mesh 
.241 0.68 
1.36 1.13 
5.4 6.4 
-- 3.2 
0.54 0.317 
-- -- 
Ethyl "Cellosolve" 
-- 2.3 
-- 3.9 
-- 9.5 
-- 2.7 
-- 0.95 
-- -- 
Phenolic resin 
-- 7.3 
-- -- -- -- -- -- -- 3.72 
3.5 4 
Red pigment solution II 
-- 0.45 
-- 0.68 
-- 8.2 
-- 4.1 
-- -- -- -- 
(10 parts red pigment: 
90 parts vehicle) 
Ca CO.sub.3 -- 0.9 
-- 1.6 
-- 9.1 
-- 4.5 
-- 0.45 
0.57 -- 
"Cellosolve" acetate 
-- -- 6.8 -- 38 -- -- -- -- -- -- -- 
AL.sub.2 O.sub.3 (180/600) 
-- -- -- -- -- -- -- -- -- -- -- 5.7 
Water -- -- -- 3.2 
-- 31.3 
9 14.5 
-- 0.95 
1.36 1.35 
Phenolic resin 
-- -- -- 12.3 
-- 74 31 37.2 
-- -- -- -- 
10% solution dibutyl- 
-- -- -- -- .004 -- -- -- -- -- -- -- 
tindilaurate 
Isopropyl alcohol 
-- -- -- -- -- -- 2.7 -- -- -- 0.34 0.23 
Antifoam agent sold under 
-- -- -- -- -- -- 3 g -- -- -- -- -- 
the trade designation 
"Eldefoam" 
Gold pigment - I 
-- -- -- -- -- -- -- -- 127 gm 
-- -- -- 
(3 parts brown:12 
parts yellow:85 parts 
pigment vehicle) 
Gold pigment - II 
-- -- -- -- -- -- -- -- -- 0.23 
-- -- 
(10 parts gold pigment: 
90 parts vehicle) 
Black dye -- -- -- -- -- -- -- -- -- -- 0.23 0.11 
Black pigment 
-- -- -- -- -- -- -- -- -- -- 0.11 -- 
Flint (360 mesh & finer) 
-- -- -- -- -- -- -- -- -- -- 2.6 -- 
AL.sub.2 O.sub.3 (280 mesh & finer) 
-- -- -- -- -- -- -- -- -- -- 2.6 -- 
__________________________________________________________________________