U.S. patent application number 13/494590 was filed with the patent office on 2012-12-20 for sandpaper with laminated non-slip layer.
This patent application is currently assigned to 3M Innovative Properties Company. Invention is credited to John G. Petersen.
Application Number | 20120322352 13/494590 |
Document ID | / |
Family ID | 47354035 |
Filed Date | 2012-12-20 |
United States Patent
Application |
20120322352 |
Kind Code |
A1 |
Petersen; John G. |
December 20, 2012 |
SANDPAPER WITH LAMINATED NON-SLIP LAYER
Abstract
A sheet of sandpaper includes a backing layer having opposed
first and second major sides, an adhesive make coat on the second
major side, abrasive particles at least partially embedded in the
make coat, thereby defining an abrasive surface, and an exposed
laminated non-slip layer on the first major side. Methods of making
and using such sandpaper are also provided.
Inventors: |
Petersen; John G.; (Center
City, MN) |
Assignee: |
3M Innovative Properties
Company
|
Family ID: |
47354035 |
Appl. No.: |
13/494590 |
Filed: |
June 12, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61498673 |
Jun 20, 2011 |
|
|
|
Current U.S.
Class: |
451/539 ;
51/297 |
Current CPC
Class: |
B24D 11/001 20130101;
B24D 11/02 20130101; B24D 3/002 20130101 |
Class at
Publication: |
451/539 ;
51/297 |
International
Class: |
B24D 11/02 20060101
B24D011/02; B24D 18/00 20060101 B24D018/00 |
Claims
1. A sheet of sandpaper, comprising: a flexible backing layer
having opposed first and second major sides; an adhesive make coat
on the second major side of the backing layer; abrasive particles
at least partially embedded in the make coat, thereby defining an
abrasive surface; and an exposed laminated non-slip layer of less
than about 600 microns in thickness, on the first major side of the
backing layer.
2. A sheet of sandpaper as defined in claim 1, wherein the non-slip
layer is in direct contact with a first major surface of the first
major side of the flexible backing layer.
3. A sheet of sandpaper as defined in claim 1, further comprising
at least one support layer at least a portion of which is between
at least a portion of the non-slip layer and a portion of the
backing layer.
4. A sheet of sandpaper as defined in claim 3, wherein the non-slip
layer is a hot-melt coating layer on the support layer.
5. A sheet of sandpaper as defined in claim 1, wherein the non-slip
layer comprises an embedded support layer.
6. A sheet of sandpaper as defined in claim 1, further comprising
at least one adhesion-enhancing layer at least a portion of which
is between at least a portion of the non-slip layer and a portion
of the backing layer, wherein the adhesion-enhancing layer is
chosen from the group consisting of a primer layer, a tie layer,
and a pressure-sensitive adhesive layer.
7. A sheet of sandpaper as defined in claim 1, wherein the non-slip
layer has an average tack level, as measured by ASTM D2979-88 using
a 10 second dwell time, and a probe removal speed of 1 cm/s of no
greater than about 250 grams.
8. A sheet of sandpaper as defined in claim 1, wherein the non-slip
layer has an average peak static coefficient of friction of at
least about 1 gram when measured according to ASTM D 1894-08.
9. A sheet of sandpaper as defined in claim 1, wherein the non-slip
layer has a thickness of less than about 100 microns.
10. A sheet of sandpaper as defined in claim 1, wherein the
non-slip layer comprises a generally planar exposed outer
surface.
11. A sheet of sandpaper as defined in claim 1, wherein the
non-slip layer comprises an amorphous base resin, and an effective
amount of a tackifying resin.
12. A method of making a sheet of sandpaper having a laminated
non-slip layer on the first major side thereof, comprising the
steps of: providing a flexible backing layer having opposed first
and second major sides; coating an adhesive make coat on the second
major side of the backing layer; at least partially embedding
abrasive particles in the make coat, thereby forming an abrasive
surface; and, laminating a non-slip layer onto the first major side
of the backing layer to form an exposed laminated non-slip layer of
less than about 600 microns in thickness on the first major side of
the backing layer.
13. The method of claim 12 wherein the non-slip layer is laminated
directly to a first major surface of the first major side of the
backing layer with no other layers being therebetween.
14. The method of claim 12 wherein one or more adhesive layers are
provided between at least a portion of the non-slip layer and a
portion of the backing layer.
15. The method of claim 12 wherein one or more tie layers or primer
layers are provided between at least a portion of the non-slip
layer and a portion of the backing layer.
16. The method of claim 12 wherein the non-slip layer is provided
on a support layer at least a portion of which, after the
lamination is completed, is positioned between at least a portion
of the non-slip layer and at least a portion of the backing
layer.
17. The method of claim 12 wherein the non-slip layer is delivered
to the first major side of the backing layer while residing on a
temporary liner, and wherein the temporary liner is separated from
the non-slip layer after the lamination is completed.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Patent Application No. 61/498,673, filed Jun. 20, 2011, the
disclosure of which is incorporated by reference herein in its
entirety.
BACKGROUND
[0002] The present invention relates generally to abrasive articles
for abrading a work surface such as, for example, flexible
sheet-like abrasive articles.
[0003] Sheet-like abrasive articles are commonly used in a variety
of sanding operations including, for example, hand sanding of
wooden surfaces. In hand sanding, the user holds the abrasive
article directly in his or her hand and moves the abrasive article
across the work surface. Sanding by hand can, of course, be an
arduous task.
[0004] Sheet-like abrasive articles include, for example,
conventional sandpaper. Conventional sandpaper is typically
produced by affixing abrasive material to a relatively thin,
generally non-extensible, non-resilient, non-porous backing (e.g.,
paper). The thin, flat, slippery nature of conventional sandpaper
backing materials makes conventional sandpaper difficult to grasp,
hold, and maneuver. Because of the slippery nature of conventional
sandpaper, to hold a sheet of sandpaper securely, a user will grasp
the sheet of sandpaper between his or her thumb and one or more of
his or her remaining fingers. Holding the sandpaper in this manner
is uncomfortable, can lead to muscle cramps and fatigue, and is
difficult to maintain for an extended period of time. In addition,
the thumb is typically in contact with the abrasive surface of the
sandpaper, which can irritate or damage the skin. Also, because the
thumb is positioned between the sandpaper and the work surface,
grasping the sandpaper in this manner also interferes with the
sanding operation. That is, due to the position of the thumb, a
portion of the sandpaper abrasive surface is lifted away from the
work surface during sanding. Because the lifted portion is not in
contact with the work surface, the full sanding surface of the
sandpaper is not utilized, and the effectiveness of the sandpaper
is, therefore, diminished.
[0005] During hand sanding, a user often applies pressure to the
sandpaper using his or her fingertips. Because of the thin nature
of the backing materials used in conventional sandpaper, the finger
pressure is concentrated in the regions where the finger pressure
is applied. This, in turn, causes the sandpaper to wear and/or load
unevenly, and produces an uneven sanding pattern on the work
surface.
[0006] Conventional sandpaper is typically sold in standard size
sheets, such as 9.times.11 inch sheets. To make sandpaper easier to
use, users often fold the sandpaper, thereby producing smaller
sheets that are easier to handle. Folding the sandpaper, however,
produces a jagged edge, and also weakens the sandpaper along the
fold line. During the rigors of sanding, the weakened fold line may
tear, thereby resulting in premature failure of the sandpaper.
SUMMARY
[0007] A sheet of sandpaper includes a backing layer having opposed
first and second major sides, an adhesive make coat on the second
major side, abrasive particles at least partially embedded in the
make coat, thereby defining an abrasive surface, and an exposed
laminated non-slip layer on the first major side. Methods of making
and using such sandpaper are also provided.
[0008] In one aspect, disclosed herein is a sheet of sandpaper,
comprising: a flexible backing layer having opposed first and
second major sides; an adhesive make coat on the second major side
of the backing layer; abrasive particles at least partially
embedded in the make coat, thereby defining an abrasive surface;
and an exposed laminated non-slip layer of less than about 600
microns in thickness, on the first major side of the backing
layer.
[0009] In another aspect, disclosed herein is a method of making a
sheet of sandpaper having a laminated non-slip layer on the first
major side thereof, comprising the steps of: providing a flexible
backing layer having opposed first and second major sides; coating
an adhesive make coat on the second major side of the backing
layer; at least partially embedding abrasive particles in the make
coat, thereby forming an abrasive surface; and, laminating a
non-slip layer onto the first major side of the backing layer to
form an exposed laminated non-slip layer of less than about 600
microns in thickness on the first major side of the backing
layer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The present invention will be further described with
reference to the accompanying drawings, in which:
[0011] FIG. 1 is a cross sectional view of an exemplary sheet of
sandpaper according to the invention.
[0012] FIG. 2 is a cross sectional view of an exemplary particular
embodiment of a sheet of sandpaper.
[0013] FIG. 3 is a cross sectional view of another exemplary
particular embodiment of a sheet of sandpaper.
[0014] FIG. 4 is a cross sectional view of another exemplary
particular embodiment of a sheet of sandpaper.
[0015] FIG. 5 is a cross sectional view of another exemplary
particular embodiment of a sheet of sandpaper.
[0016] FIG. 6 is a cross sectional view of another exemplary
particular embodiment of a sheet of sandpaper.
DETAILED DESCRIPTION
[0017] Referring now to the drawings, FIG. 1 shows in exemplary
generic representation a flexible sheet-like abrasive article 10,
such as a sheet of sandpaper. As used herein, the expression
"sheet-like" refers generally to the broad, thin, flexible nature
of abrasive article 10. Article 10 comprises a flexible backing
layer 12 having opposed first and second major sides respectively
bearing first 12a and second 12b major surfaces, and comprises an
exposed laminated non-slip layer 14 on the first major side of
backing layer 12, an adhesive make coat layer 16 on the second
major side of backing layer 12, and a plurality of abrasive
particles 18 at least partially embedded in the make coat layer 16.
(The terms first major side (and e.g. first major surface thereof)
will in general denote the side and surface of backing 12 bearing
laminated non-slip layer 14 (i.e., the side opposite abrasive
particles 18), and the terms second major side (and e.g. second
major surface thereof) will in general denote the side and surface
of backing 12 thereof comprising abrasive particles 18.) The
condition that laminated non-slip layer 14 is "on" the first major
side of backing layer 12 (as well as the act of laminating non-slip
layer 14 "on" or "onto" the first major side of backing layer 12)
encompasses both cases in which layer 14 (e.g., major surface 14b
of layer 14) is in direct contact with major surface 12a of the
first major side of layer 12, and cases in which layer 14 is
separated from direct contact with major surface 12a, e.g. by one
or more adhesion-enhancing layers and/or support layers as
disclosed later herein.
[0018] As used herein, the term laminated non-slip layer denotes a
non-slip layer (optionally along with other layers as disclosed
herein) that exists in a pre-formed condition (e.g., as a film,
nonwoven web, etc.) with a pre-existing thickness and that is
delivered to the first major side of backing 12 in this pre-formed
condition and is laminated (e.g., bonded, e.g. by use of heat
and/or pressure) directly or indirectly to the first major side of
backing 12. A laminated non-slip layer thus does not encompass a
coated layer that is achieved by depositing a layer of flowable
material onto the first major side of backing 12 and solidifying
the material to form the coated layer in such manner that the
deposition and/or solidification process determines the thickness
of the coated layer. As used herein, the expression "layer" denotes
that the laminated layer of non-slip material is in the form of a
discrete stratum on backing layer 12 (i.e. the non-slip material
does not soak through the entire thickness of the backing layer
12). In some embodiments, laminated non-slip layer 14 consists of a
single layer of non-slip material (optionally with one or more
layers of other material being present between laminated non-slip
layer 14 and backing 12).
[0019] In some embodiments, laminated non-slip layer 14 (e.g.,
major surface 14b of layer 14) may be in direct contact with first
major surface 12a of backing layer 12 (as shown in generic
representation in FIG. 1 and in a specific exemplary embodiment in
FIGS. 4 and 6). In other embodiments, one or more optional
intermediate layers of material may be present between backing
layer 12 and laminated non-slip layer 14 (as shown in exemplary
specific embodiments in FIGS. 2, 3 and 5), for various purposes as
disclosed herein. Such intermediate layers may comprise e.g.
support layers and/or adhesion-enhancing layers. In various
embodiments, such intermediate layers may comprise an average
thickness of less than about 200 microns, less than about 100
microns, less than about 50 microns, less than about 25 microns, or
less than about 10 microns, and may be applied by any suitable
method including e.g. by coating, vapor deposition, etc. Such
intermediate layers may be continuous or discontinuous. In some
embodiments such intermediate layers may be comprised of dense
materials (e.g., lacking porosity). Such intermediate layers do not
encompass layers such as sponge layers, foam layers, synthetic
microporous membrane layers, and the like.
[0020] Laminated non-slip layer 14 is an exposed layer. By this is
meant that outer surface 14a of laminated non-slip layer 14 is an
exposed surface that makes up at least the majority of the
outermost surface of the first major side of abrasive article 10
when article 10 is in use. That is, the majority of outer surface
14a of article 10, as article 10 is provided to an end user, is not
covered, buried, or obscured by any other layer, except for,
optionally, such items as labels, stickers, price tags, temporary
protective sheets or liners, or the like, which are not permanently
attached to laminated non-slip layer 14 and which may be removed if
desired prior to use of article 10. Thus, a laminated layer which
bears a further-outward permanently attached layer (e.g., a hook
layer, a loop layer, a mechanical fastening layer, a
pressure-sensitive adhesive layer, etc.) over a majority of its
area, by definition does not comprise an exposed laminated non-slip
layer irrespective of the composition and/or properties of the
laminated layer. In various embodiments, at least about 50%, at
least about 75%, or at least about 90%, of outer surface 14a of
non-slip layer 14 is an exposed surface. In some embodiments, the
entirety of outer surface 14a of laminated non-slip layer consists
of an exposed surface.
[0021] As used herein, "non-slip" layers refer to layers that
increase the coefficient of friction of the backing layer surface
to which the non-slip material is applied. That is, if the surface
of the backing layer 12a to which a laminated non-slip layer is
applied has a coefficient of friction of "x" prior to when the
layer is laminated thereon, and the laminated layer--as applied to
the surface of the backing--provides a surface that has a
coefficient of friction that is greater than "x", then the layer is
a "non-slip" layer. Or stated another way, if the laminated layer
tends to increase the coefficient of friction of the backing
surface to which it is applied, then the laminated layer qualifies
as a "non-slip" layer.
[0022] In one embodiment, the laminated non-slip layer 14 has an
average peak static coefficient of friction of at least about 1.0
gram, at least about 1.25 grams, or at least about 1.5 grams when
measured according to ASTM D 1894-08 (Standard Test Method for
Static and Kinetic Coefficients of Friction of Plastic Film and
Sheeting) at 23.degree. C. using an IMASS slip/peel tester (SP2000,
commercially available from Instrumentors Inc., Strongsville,
Ohio), and/or an average kinetic coefficient of friction of at
least about 0.75 grams, at least about 1 gram, or at least about
1.25 grams.
[0023] In various embodiments, laminated non-slip layer 14 outer
surface 14a may have no tack, or may have a low level of tack. If
the non-slip layer is tacky, it may be desirable that the tack be
kept to a low level. By low level of tack, it is meant that the
non-slip layer has an average tack level, as measured by ASTM
D2979-88 (Standard Test Method for Tack of Pressure-Sensitive
Adhesives Using an Inverted Probe Machine) using a ten (10) second
dwell time, and a probe removal speed of one (1) cm/s, of no
greater than about 350 grams. A non-slip layer as defined and
disclosed herein (even if it comprises a low level of tack, as
opposed to no tack), comprises a sufficiently low level of tack
that by definition it may not be equated with conventional
pressure-sensitive adhesives e.g. as may sometimes be used to
attach sandpaper to sanding blocks, vibrating or orbital sanders,
and the like. In various embodiments, laminated non-slip layer 14
has an average tack level, as measured by ASTM D2979-88 (Standard
Test Method for Tack of Pressure-Sensitive Adhesives Using an
Inverted Probe Machine) using a ten (10) second dwell time, and a
probe removal speed of one (1) cm/s, of no greater than about 200
grams, no greater than about 250 grams, or no greater than about
300 grams.
[0024] In some embodiments, laminated non-slip layer 14 may
comprise an adhesion to itself that is less than the cohesive
strength of the non-slip layer itself, and further may have an
adhesion to itself that is less than the "two-bond" adhesive
strength. As is known to those skilled in the art, the "two-bond"
adhesive strength is the adhesive strength between non-slip layer
14 and backing layer 12 to which the laminated non-slip layer is
applied. Thus, when non-slip layer 14 is folded over onto itself,
the areas of the surface of the non-slip layer that come into
contact with each other can be released from each other without
experiencing cohesive failure of the non-slip layers, and without
having any portion of laminated non-slip layer 14 detach from
backing layer 12.
[0025] In some embodiments, the non-slip layer provides a surface
that may be repeatably bonded to itself. In another somewhat
related aspect, non-slip layer 14 may be repositionable. As used
herein, "repositionable" refers to a non-slip layer that allows
repeated application, removal, and reapplication to and from itself
or a surface without damage to the non-slip layer or the
surface.
[0026] In addition, it is desirable that the adhesion of laminated
non-slip layer 14 to itself not build significantly over time. As
such, if abrasive article 10 is folded over onto itself such that
areas of the surface of the non-slip layer come into contact with
each other, abrasive article 10 may later be readily unfolded by
separating the contacted surface areas of laminated non-slip layer
14 without damaging non-slip layer 14 or backing layer 12.
[0027] In various embodiments, the laminated non-slip layer may
have a glass transition temperature of at least about -80 degrees
Celsius (.degree. C.), at least about -70.degree. C., and at least
about -65.degree. C., and a glass transition temperature of no
greater than about -5.degree. C., no greater than about -15.degree.
C., and no greater than about -25.degree. C.
[0028] In various embodiments, laminated non-slip layer 14 may
comprise a thickness (e.g., an average thickness as measured in
several locations) of at least about 10 microns, at least about 15
microns, at least about 20 microns, or at least about 25 microns.
In further embodiments, laminated non-slip layer 14 may comprise a
thickness of at most about 800 microns, at most about 400 microns,
at most about 200 microns, at most about 100 microns, at most about
50 microns, or at most about 40 microns.
[0029] In various embodiments, laminated non-slip layer 14 may
comprise an areal density (e.g., an average as measured in several
locations) of at least about 10 grams per square meter, at least
about 15 grams per square meter, at least about 20 grams per square
meter, or at least about 25 grams per square meter. In further
embodiments, laminated non-slip layer 14 may comprise an areal
density of at most about 200 grams per square meter, at most about
100 grams per square meter, at most about 60 grams per square
meter, or at most about 25 grams per square meter. In various
embodiments, the material of laminated non-slip layer 14 may
comprise a volumetric density of at least about 0.9 grams/cc, at
least about 0.95 grams/cc, or at least about 1.0 grams/cc.
[0030] In some embodiments, laminated non-slip layer 14 may be
comprised of an essentially dense material (e.g., without any
microscopic porosity or internal void volume other than the
occasional voids, free volume, etc., as are known to those of skill
in the art to be sometimes present in many polymeric materials),
irrespective of any macroscopic discontinuities (e.g.,
through-holes or the like) that may be present in some embodiments.
In some embodiments, laminated non-slip layer 14 may be comprised
of a fibrous material such as e.g. a nonwoven fibrous layer such as
a spunbonded web, a meltblown web, or a carded web; a woven web; a
knitted cloth; a polymeric netting; or the like. Laminated non-slip
layer 14 of an abrasive article 10 (e.g. sandpaper), as disclosed
herein, does not encompass a sponge or foam layer, whether open or
closed cell (e.g., of a so-called sanding sponge).
[0031] Laminated non-slip layer 14 may be continuous or
discontinuous, with the term discontinuous signifying the presence
of macroscopic (e.g., with a dimension of greater than about 100
microns) features such as through-holes and the like. Such
through-holes may comprise e.g. generally straight-through passages
achieved by perforation, punching or the like, or may be in the
form of somewhat tortuous passages of the type that may be
naturally present e.g. when laminated non-slip layer 14 is in the
form of a nonwoven fibrous material. In various embodiments, such
discontinuities may be present regular and/or repeating patterns,
in random, irregular or non-repeating patterns, or in any
combination of such patterns.
[0032] As mentioned, and as pictured in the embodiment illustrated
in FIG. 1, non-slip layer 14 defines an outer surface 14a on the
first major side of article 10, opposite make coat 16 and abrasive
particles 18. In some embodiments outer surface 14a may be a
generally planar surface that by definition does not include a
textured pattern or a visually observable three dimensional surface
topography. In other embodiments, the outer surface of non-slip
layer 14 may comprise a textured or patterned surface. This might
be achieved e.g. by manufacturing layer 14 in such manner as to
impart a non-smooth outer surface. Or, laminated non-slip layer 14
may comprise filler material or particles to provide the laminated
non-slip layer 14 outer surface 14a with a rough or randomly
textured surface. Such a rough, textured or patterned surface may
serve to enhance the non-slip properties of laminated non-slip
layer 14.
[0033] In some embodiments, laminated non-slip layer 14 may be
clear. In this manner, any information or indicia printed on
backing layer 12 will remain visible through laminated non-slip
layer 14. In addition, the appearance of the sandpaper may remain
similar to the appearance of conventional sandpaper, to which users
have become accustomed. In other embodiments, laminated non-slip
layer 14 may be colored, pigmented, etc., for any effect as
desired. In some embodiments, laminated non-slip layer 14 is
permanently bonded to backing 12 (either directly to surface 12a of
backing 12, or via one or more intermediate layers as discussed
herein).
[0034] In some embodiments, laminated non-slip layer 14 may
comprise at least one base resin. A base resin may comprise any
suitable polymeric material that provides mechanical integrity and
toughness to the non-slip layer, but that may not necessarily (in
the absence of the tackifying resin) supply the desired non-slip
properties disclosed herein. Suitable base resins for non-slip
layer 14 may include, for example: natural and synthetic rubbers
such as synthetic polyisoprene, butyl rubbers, polybutadiene,
styrene-butadiene rubber (SBR), carboxylated styrene-butadiene
rubber, block copolymers such as Kraton rubber,
polystyrene-polyisoprene-polystyrene (SIS) rubber,
styrene-butadiene-styrene (SBS) rubber, nitrile rubber (Buna-N
rubbers), hydrogenated nitrile rubbers, acrylonitrile-butadiene
rubber (NBR), chloroprene rubber, polychloroprene, neoprene, EPM
rubber (ethylene propylene rubber), EPDM rubber (ethylene propylene
diene rubber), ethylene-propylene-butylene terpolymers, acrylic
rubber, polyacrylic rubber, silicone rubber; copolymers such as
ethylene-vinyl acetate (EVA) copolymers, ethylene-(meth)acrylate
copolymers, ethylene-vinyl acetate-maleic anhydride and/or
ethylene-(meth)acrylate-maleic anhydride terpolymers; and other
polymeric materials such as polyvinyl acetates, grafted polyvinyl
acetates or EVA copolymers, polyamides, polyesters, thermoplastic
elastomers, thermoplastic vulcanizates such as Santoprene
thermoplastic rubber, thermoplastic polyurethanes, and
thermoplastic olefins and amorphous polyolefins.
[0035] In some embodiments, the at least one base resin may
comprise a poly(vinyl ether) polymer, e.g. an amorphous poly(alkyl
vinyl ether) polymer such as amorphous poly(methyl vinyl ether). In
some embodiments, the at least one base resin may comprise a
polyolefin, e.g. a polyethylene, polypropylene, polybutene, and/or
copolymers (including terpolymers) thereof. In certain embodiments,
such a polyolefin may comprise a grafted polyolefin, e.g. a
polyethylene with a saponification number of at least three, and
which may be grafted e.g. with polycarboxylic acids, anyhydrides,
esters thereof, or the like. In certain other embodiments, such a
polyolefin may comprise a metallocene (catalyzed) polyolefin, for
example a functionalized metallocene polyethylene polymer or
copolymer. Such polymers or copolymers may be functionalized e.g.
with acids such as acrylic acid, acetates, sulfonates, maleic
anhydrides, or the like.
[0036] In some embodiments, the base resin may comprise an
amorphous polymer. By amorphous is meant a polymer that displays
essentially no crystallinity, as evidenced by no, or at most a very
weak (i.e., barely discernible), melting point(s) on a Differential
Scanning calorimetry curve, as will be appreciated by those of
ordinary skill. In various specific embodiments, an amorphous
polymer may comprise an amorphous hydrocarbon polymer or copolymer
(such as, e.g., polyolefin polymers and/or copolymers containing
ethylene, propylene, higher alkenes, and/or copolymers thereof,
polymers and/or copolymers of higher order dienes, polymers and/or
copolymers of poly-alpha olefins, etc.); or, an amorphous
heteroatom polymer or copolymer (such as, e.g.
polyolefin-poly(meth)acrylate copolymers, polyolefin-EVA
copolymers, poly(vinyl ether) polymers and/or copolymers, and the
like). In some embodiments, the amorphous polymer may comprise
atactic polypropylene and/or copolymers thereof. In some
embodiments, the amorphous polymer is an aliphatic polymer (i.e.,
not comprising aromatic units). In some embodiments, the base resin
consists essentially of an amorphous polymer or copolymer or of
mixtures of amorphous polymers or copolymers. In some embodiments,
the amorphous polymer may comprise a poly-alpha-olefin hydrocarbon
copolymer (e.g., terpolymer) containing propyl, ethyl, and butyl
monomer units (e.g., obtained by the copolymerization of propylene,
ethylene, and 1-butene). In particular embodiments, the amorphous
polymer may comprise, or may consist essentially of, a
propylene-rich poly-alpha-olefin polymer, meaning a copolymer
containing at least about 70 mole % of propylene-derived monomer
units and from about 5 mole % to about 15 mole % of
1-butene-derived monomer units, with the balance being chosen from
any other suitable monomer units, e.g. ethylene.
[0037] The above list is meant to be representative, not
exhaustive. Blends, mixtures, etc. of any of the above base resins
may be used if desired.
[0038] In some embodiments, laminated non-slip layer 14 may
comprise an effective amount of at least one tackifying resin. A
tackifying resin may comprise any material (e.g., polymeric
material) that may not necessarily comprise acceptable mechanical
integrity by itself, but that when present at an effective amount
along with a base resin, supplies the combination of resins with
the desired non-slip properties disclosed herein. By an effective
amount of tackifying resin is meant an amount sufficient to
satisfactorily provide the non-slip properties disclosed herein
(e.g., whether measured quantitatively by way of a coefficient of
friction and/or tack test as disclosed earlier herein, or
qualitatively by way of manually handling and sanding with an
abrasive article comprising the non-slip layer). By an effective
amount is further meant an amount that is lower than a threshold
level that would cause the non-slip layer to be a conventional
pressure-sensitive adhesive.
[0039] Suitable tackifying resins for non-slip layer 14 may
include, for example: polymeric terpenes, hetero-functional
terpenes, coumarone-indene resins, rosin acids, esters of rosin
acids, disproportionated rosin acid esters, hydrogenated rosin
acids, C.sub.5 aliphatic resins, C.sub.9 aromatics, C.sub.9
hydrogenated aromatic resins, C.sub.5/C.sub.9 aliphatic/aromatic
resins, dicyclopentadiene resins, hydrogenated pinene polymers or
copolymers, hydrogenated hydrocarbon resins arising from
C.sub.5/C.sub.9 and dicyclopentadiene precursors, hydrogenated
styrene monomer resins, alpha-methyl styrene resins, hydrogenated
mixed aromatic tackifying resins, aliphatic/aromatic hydrocarbon
liquid tackifying resins; napthenic oils, mineral oils, alkyl
phenolic tackifying resins, and the like. Additionally potentially
suitable tackifying resins may include, for example:
alpha-methylstyrene; copolymers of alpha-methylstyrene and styrene;
hydrogenated cyclopentadienes, a rosin or a terpene resin of the
alpha-pinene, beta-pinene and d-limonene types; wood rosins or gum
rosins; rosin esters derived from either gum or wood rosin, such as
glycerol esters (ester gums), pentaerythritol esters, hydrogenated,
polymerized or disproportionated gum or wood rosins; polyhydric
alcohol derivatives of hydrogenated rosin, such as glycerol
derivatives or polyhydroalcohol derivatives of polymerized rosins;
e.g. ethylene glycol ester, glycerol esters, oxidized rosins,
hydrogenated oxidized rosin esters of oxidized rosin and the like.
Still other potentially suitable tackifying resins may include e.g.
hydrocarbon resins such as polyterpenes, synthetic polyterpenes,
and those materials obtained from the polymerization of olefins and
diolefins (e.g., the aliphatic olefin derived tackifying resins
available from the Sartomer Company of Exton, Pa. under the trade
designation Wingtack). Still other potentially suitable tackifying
resins include e.g. terpene polymers such as the polymeric,
resinous materials obtained by polymerization and/or
copolymerization of terpene hydrocarbons such as the alicyclic,
monocyclic, and bicyclic monoterpenes and their mixtures, including
allo-ocimene, carene, isomerized pinene, pinene, dipentene,
terpinene, terpinolene, limonene, turpentine, a terpene cut or
fraction, and various other terpenes. In some embodiments, the
tackifying resin(s) is a hydrocarbon material; in particular
embodiments, the tackifying resin(s) is an aliphatic hydrocarbon
material. Such materials may be e.g. branched hydrocarbon
polymers.
[0040] This list is meant to be representative, not exhaustive.
Blends, mixtures, etc., of any or all of the above-listed
tackifying resins can be used.
[0041] Laminated non-slip layer 14 may optionally comprise at least
one wax, by which is meant a relatively low molecular weight
material that may modify or enhance various properties of the
laminated non-slip layer. Any suitable natural (e.g., animal,
vegetable, mineral, or petroleum based) or synthetic wax may be
used. Such waxes may include e.g. hydrocarbon waxes, paraffin
waxes, microcrystalline waxes, fatty amide waxes, hydroxy
stearamide waxes, vinyl acetate-modified waxes, maleic
anhydride-modified waxes, high density low molecular weight (e.g.,
less than approximately 2500) polyethylene waxes, and the like.
[0042] Any other desirable ingredients may be included in laminated
non-slip layer 14 as long as they do not unacceptably affect the
non-slip property. Such additives may include e.g. processing aids,
extrusion aids, antioxidants, wetting agents, UV stabilizers,
nucleating agents, plasticizers, pigments, dyes, fillers, and so
on.
[0043] In some embodiments, laminated non-slip layer 14 consists
essentially of at least one base resin, at least one tackifying
resin, and at least one wax along with optional minor quantities of
additives such as processing aids, antioxidants and the like.
[0044] In some embodiments, laminated non-slip layer 14 may be
bonded directly to backing 12 with no other layer(s) therebetween;
i.e., major surface 14b of layer 14 may be bonded directly to major
surface 12a of backing 12. In such cases, at least major surface
14b of non-slip layer 14 may comprise a composition capable of
bonding to major surface 12a. For example, non-slip layer 14 may
comprise e.g. a heat-bondable composition, e.g. may be a
thermoactivatable web (which term encompasses both dense films, and
porous materials such as nonwoven webs, netting and the like).
Thermoactivatable webs are generally known, and may include e.g.
products available from ProTechnics, Cernay, France, under the
trade name Texiron. Any thermoactivatable web may be used as long
as it satisfies the conditions prescribed earlier herein (i.e.,
that layer 14 possesses suitable non-slip properties).
[0045] Configurations in which laminated non-slip layer 14 may be
bonded directly to backing 12 are shown in generic exemplary
representation in FIG. 1 and in a particular exemplary
configuration in FIG. 4, discussed later herein.
[0046] In other embodiments, one or more intermediate layers of
other material may be present between at least a portion of
non-slip layer 14 and at least a portion of backing 12. In
particular embodiments, such a layer or layers are present between
the entirety of non-slip layer 14 and backing 12. In some
embodiments, such intermediate layers may comprise
adhesion-enhancing layers, which category broadly encompasses any
layer which provides, facilitates, promotes, etc., the bonding of
non-slip layer 14 to backing 12.
[0047] In a particular exemplary embodiment depicted in FIG. 2,
adhesion-enhancing layer 20 comprises an adhesive layer that is
capable of bonding both to major surface 14b of non-slip layer 14,
and to major surface 12a of backing 12. Such an adhesive layer may
be comprised of any suitable adhesive composition, delivered to
article 10 by any suitable mechanism. In some embodiments, adhesive
layer 20 may be a laminating adhesive, e.g. a pressure-sensitive
adhesive. In specific embodiments, adhesive layer 20 may comprise a
hot-melt adhesive composition which may be deposited onto the
backside of backing 12 in a heated (flowable) state, with non-slip
layer 14 being brought into contact with an exposed surface of
adhesive layer 20 e.g. while layer 20 is still in a heated state in
which it is capable of bonding to non-slip layer 14. In such
manner, non-slip layer 14 can be laminated to backing 12. In other
embodiments, adhesive layer 20 may comprise a pre-formed layer
(e.g., film or web) which may be placed in between backing 12 and
non-slip layer 14 and heated so as to activate or promote bonding
between the major surfaces of adhesive layer 20 and the major
surfaces of backing 12 and non-slip layer 14. Various
thermoactivatable webs may be useful for such purposes, including
e.g. products available from ProTechnics, Cernay, France, under the
trade name Texiron (noting that in this particular configuration a
thermoactivatable web, not serving as a non-slip layer itself, may
not necessarily need to satisfy any particular non-slip criterion).
It should be noted that adhesive layer 20 does not necessarily need
to be a continuous layer, and can comprise such adhesive materials
as may be discontinuously deposited (e.g., sprayed) onto the first
major side of backing 12.
[0048] In further detail, adhesive layer 20 may comprise e.g. any
of a pressure-sensitive adhesive, a hot-melt adhesive, a hardenable
adhesive, a drying adhesive, and a photohardenable adhesive
(recognizing that some adhesive compositions may fall into more
than one of these categories). By a hardenable adhesive is meant an
adhesive that solidifies by a chemical reaction (with or without
liberation of small molecules), e.g. a moisture-cure silicone, an
epoxy, and the like. By a drying adhesive is mean an adhesive that
solidifies by the loss of a solvent and/or water, e.g. rubber
cement, a water-based glue, and the like. By a photohardenable
adhesive is meant one whose hardening is initiated or promoted by
radiation (such as visible light, UV radiation, etc.), e.g. the
well-known UV-curable adhesives and the like.
[0049] In other embodiments, adhesion-enhancing layer 20 may
comprise an adhesion-promoting layer, e.g. a tie layer, primer
layer, or the like, that is deposited, coated, or otherwise formed
atop major surface 12a of backing 12. The composition of such an
adhesion-promoting layer may be chosen in view of the composition
of non-slip layer 14 which is desired to be laminated to backing
12. For example, if non-slip layer 14 comprises polyolefin
components, a primer or tie layer may be disposed (e.g. coated)
onto major surface 12a of backing 12, that promotes bonding to such
polyolefin components. More than one adhesion-enhancing layer, of
any desired type, may be used, e.g. in combination. For example,
upon selecting a laminating adhesive that is well suited to bond to
a particular laminated non-slip layer 14, a tie layer may be coated
onto major surface 12a of backing 12, that is particularly suited
to be bonded by that same laminating adhesive. It should be noted
that, like an adhesive layer, an adhesion-promoting layer may or
may not be a continuous layer.
[0050] As illustrated in exemplary manner in FIG. 3, one or more
support layers 24 may be provided in between at least a portion of
laminated non-slip layer 14 and a portion of backing 12. Such a
support layer may be particularly useful in a case in which
non-slip layer 14 is sufficiently thin, and/or comprises
sufficiently delicate physical properties, as to make non-slip
layer 14 difficult to handle as a free-standing film or web. In
such circumstances, non-slip layer 14 may be provided on support
layer 24 which becomes part of the structure of the resulting
article 10. As such, a support layer 24 is defined herein as a
layer upon which non-slip layer 14 is already bonded to form a
multilayer structure, prior to layer 14 being laminated onto the
first major side of backing 12. In the exemplary embodiment of FIG.
3, article 10 comprises support layer 24 on which non-slip layer 14
is provided without the material of non-slip layer 14 penetrating
substantially into support layer 24. For example, non-slip layer 14
may comprise a hot-melt-coatable composition that is coated onto
surface 24a of support layer 24. The hot-melt-coatable composition
may then be cooled to form non-slip layer 14 (e.g., prior to
rolling up the multilayer construction of support layer 24 and
non-slip layer 14). Then, support layer 24 (bearing non-slip layer
14 thereupon) may be laminated to backing layer 12. In exemplary
embodiments of the general type depicted in FIG. 3, an
adhesion-enhancing layer 20 (e.g., a laminating adhesive) may be
used to bond support layer 24 to backing 12. In some embodiments,
support layer 24 may also function as an adhesion-enhancing layer,
in which case a separate adhesion-enhancing layer 20 may not
necessarily be needed.
[0051] If a support layer 24 is used, its composition may be chosen
so that non-slip layer 14 may be adhered satisfactorily to major
surface 24a of support layer 24. If desired, major surface 24a may
be treated, and/or a tie layer applied, so as to enhance the
ability of non-slip layer 14 to remain adhered to support layer 24.
Likewise, if an adhesion-enhancing layer 20 is used to bond support
layer 24 to the first major side of backing layer 12, surface 24b
of support layer 24 may be treated so as to enhance its ability to
be bonded by adhesion-enhancing layer 20.
[0052] Support layer 24 may be comprised of any suitable web,
encompassing both dense materials (e.g., films) and discontinuous
(e.g., porous) webs (e.g. nonwovens and the like), that has
adequate physical properties to render a multilayer combination of
support layer 24 and non-slip layer 14 able to be handled so as to
be laminated to backing 12. For example, support layer 24 may
comprise a film of polyester, polyethylene, polypropylene (e.g.,
oriented or biaxially oriented polypropylene), cellophane, or the
like. The thickness of support layer 24 may be likewise chosen to
provide sufficient handleability to the multilayer combination of
support layer 24, and non-slip layer 14, while preserving
acceptable flexibility of abrasive article 10. Thus, for example,
support layer 24 may comprise e.g. a film with thickness less than
about 12 microns, about 25 microns, about 38 microns, about 50
microns, or the like.
[0053] If support layer 24 comprises a dense film, non-slip layer
14 may not necessarily penetrate significantly thereinto. In other
embodiments, a support layer may comprise an at least partially
penetrable web 22. In various embodiments at least partially
penetrable web support layer 22 may comprise any fibrous material
including e.g. a nonwoven fibrous layer such as a spunbonded web, a
meltblown web, or a carded web; a woven web; a knitted cloth; a
polymeric netting; or the like. In some embodiments (and as
exemplified in FIG. 4) the material of non-slip layer 14 may
penetrate so completely into support web 22 as to result in web 22
being partially, or completely buried (embedded) within the
material of non-slip layer 14. FIG. 4 illustrates such an
embodiment in which non-slip layer 14 is of such composition that
it can be bonded directly to surface 12a of backing 12. FIG. 5
illustrates an embodiment in which embedded support layer 22 is
again present, but in which an adhesion-enhancing layer 20 is used
to bond non-slip layer 14 to backing 12.
[0054] Suitable materials for flexible backing layer 12 may include
any of the materials commonly used to make sandpaper including, for
example, paper, cloths (cotton, polyester, rayon), polymeric films
such as thermoplastic films, foams, and laminates thereof. The
backing layer 12 will have sufficient strength for handling during
processing, sufficient strength to be used for the intended end use
application, and the ability to have non-slip layer 14 laminated to
its first major surface, and make coat 16 applied to its second
major surface.
[0055] In the illustrated embodiment, backing layer 12 is formed of
paper. Paper is a desirable material for backing layer 12 because
it is readily available and is typically low in cost. Conventional
sandpaper, however, which has a paper backing layer, has limited
durability, and has a smooth slippery surface that makes
conventional sandpaper difficult to move over a work surface and,
therefore, makes sanding difficult. Paper backings are available in
various weights, which are usually designated using letters ranging
from "A" to "F". The letter "A" is used to designate the lightest
weight papers, and the letter "F" is used to designate the heaviest
weight papers.
[0056] In the illustrated embodiment of FIG. 1, backing layer 12 is
continuous. That is, backing layer 12 does not contain holes,
openings, slits, voids, or channels extending there through in the
Z-direction (i.e. the thickness or height dimension) that are
larger than the randomly formed spaces between the material itself
when it is made. The backing may also contain openings (i.e. be
perforated), or contain slits. Backing layer 12 is also generally
non-extensible. Non-extensible refers to a material having an
elongation at break of typically no greater than about 25%, no
greater than about 10%, or no greater than about 5%.
[0057] In certain embodiments, e.g. when backing layer 12 is formed
of paper, backing layer 12 may be relatively thin, and typically
has a thickness of no greater than about 1.5 mm, no greater than
about 1 mm, or no greater than about 0.75 mm. In such embodiments,
the backing layer 12 is generally not resilient. The backing layer
12 may be porous or non-porous. In some embodiments, backing layer
12 consists of a single layer.
[0058] In some embodiments, backing layer 12 may be formed of a
cloth material or film, such as a polymeric film. Cloth materials
may be desirable because they are generally tear resistant and are
generally more durable than paper and film materials. In addition,
cloth backings tolerate repeated bending and flexing during use.
Cloth backings are generally formed of woven cotton or synthetic
yarns that are treated to make them suitable for use as a coated
abrasive backing As is the case with paper backings, cloth backings
are available in various weights, which are usually designated
using a letter ranging from "J" to "M" with the letter "J"
designating the lightest weight cloth, and the letter "M"
designating the heaviest weight cloths.
[0059] Suitable film materials for the backing layer 12 may include
polymeric films, including primed films, such as polyolefin film
(e.g., polypropylene including biaxially oriented polypropylene,
polyester film, polyamide film, cellulose ester film).
[0060] In various embodiments, backing layer 12 (as well as any
other layers of sandpaper 10) may be comprised of specially chosen
materials, and/or may be treated, so as to be easily foldable
and/or tearable, e.g. hand-tearable. For example, one or more lines
of weakness (e.g., a line of partial- or through-perforations) may
be provided to facilitate easy folding and/or tearing by hand.
[0061] In general, any adhesive make coat 16 may be used to adhere
the abrasive particles 18 to the backing layer 12. "Make coat"
refers to the layer of hardened resin over the backing layer 12 of
the sandpaper 10. Suitable materials for the adhesive make coat 16
include, for example, phenolic resins, aminoplast resins having
pendant .alpha.,.beta.-unsaturated carbonyl groups, urethane
resins, epoxy resins, ethylenically unsaturated resins, acrylated
isocyanurate resins, urea-formaldehyde resins, isocyanurate resins,
acrylated urethane resins, acrylated epoxy resins, bismaleimide
resins, fluorene-modified epoxy resins, and combinations thereof.
The make coat 16 may be coated onto the backing layer 12 by any
conventional technique, such as knife layer, spray layer, roll
layer, rotogravure layer, curtain layer, and the like. The
sandpaper 10 may also include an optional size coat (not shown).
The make coat 16 and/or an optional size coat may contain optional
additives, such as fillers, fibers, lubricants, grinding aids,
wetting agents, thickening agents, anti-loading agents,
surfactants, pigments, dyes, coupling agents, photo-initiators,
plasticizers, suspending agents, antistatic agents, and the like.
Possible fillers include calcium carbonate, calcium oxide, calcium
metasilicate, alumina trihydrate, cryolite, magnesia, kaolin,
quartz, and glass. Fillers that can function as grinding aids
include cryolite, potassium fluoroborate, feldspar, and sulfur. The
amounts of these materials are selected to provide the properties
desired, as is known to those skilled in the art.
[0062] In some embodiments, adhesive make coat 16 consists of a
single layer that is in direct contact with surface 12b of backing
layer 12. In such embodiments, the combination of backing layer 12
and adhesive make coat 16 does not encompass configurations
involving three or more layers, e.g. a backing layer bearing a
binder layer thereupon, which binder layer bears an adhesive layer
thereupon.
[0063] In general, abrasive particles 18 of any suitable size
(e.g., diameter or equivalent diameter in the event of
substantially nonspherical particles) may be used with this
invention. In some embodiments, abrasive particles 18 may have a
FEPA P grade, as outlined by the Federation of European Producers
of Abrasives and as tested in accordance with the ISO 6344
standard, of P100 or lower (with a lower grade corresponding to
larger particles). In various embodiments, the abrasive particles
and the abrasive article comprising the abrasive particles, may
comprise an FEPA grade of P80, of P60, or of P40.
[0064] Suitable abrasive particles may include, for example, fused
aluminum oxide, heat treated aluminum oxide, alumina-based
ceramics, silicon carbide, zirconia, alumina-zirconia, garnet,
emery, diamond, ceria, cubic boron nitride, ground glass, quartz,
titanium diboride, sol gel abrasives and combinations thereof. The
abrasive particles 18 can be either shaped (e.g., rod, triangle, or
pyramid) or unshaped (i.e., irregular). The term "abrasive
particle" encompasses abrasive grains, agglomerates, or multi-grain
abrasive granules. The abrasive particles can be deposited onto
make coat 16 by any conventional technique such as electrostatic
coating or drop coating.
[0065] In general, abrasive article (sandpaper) 10 may be made by
providing a backing layer 12 (e.g., a paper backing), coating an
adhesive make coat 16 on one major surface of the backing layer, at
least partially embedding abrasive particles 18 in the make coat,
thereby forming an abrasive surface, and laminating a non-slip
layer 14 onto the first major side of the backing layer opposite
the make coat. These operations may be performed in any suitable
order; the choice of the most convenient order and/or technique may
depend e.g. on the particular configuration and materials of
non-slip layer 14 and/or backing 12.
[0066] In cases in which non-slip layer 14 has suitable properties
to be handled as a free-standing film or web (defined as meaning a
film or web that is not residing on a support layer 24 that is
permanently incorporated into article 10, but not excluding that
the film or web may be delivered to a lamination process on a
temporary liner, as disclosed elsewhere herein), non-slip layer 14
may be brought into proximity to the first major side of backing 12
while in such free-standing form, and laminated thereto. If
non-slip layer 14 has a composition that facilitates bonding
directly to surface 12a of backing 12, layer 14 may be bonded
directly thereto, e.g. producing a structure of the general type
illustrated in FIG. 1. Alternatively, an adhesion-enhancing layer
20 may be used to enhance, or to perform, the adhering of non-slip
layer 14 to backing 12, e.g. producing a construction of the
general type exemplified in FIG. 2. Layer 20 may comprise an
adhesion-promoting layer (e.g. a primer layer, tie layer, or the
like) which might be applied e.g. to major surface 12a of backing
layer 12, to major surface 14b of non-slip layer 14, or both. In
some instances, layer 20 may comprise an adhesive layer, e.g. a
laminating adhesive (whether thermoactivatable, or a
pressure-sensitive adhesive). If desired, multiple
adhesion-enhancing layers 20 (e.g., one or more adhesive layers and
one or more tie or primer layers) may be used.
[0067] By way of other examples, in order to make an article 10
e.g. of the general type illustrated in FIG. 3, in which non-slip
layer 14 is provided as part of a multilayer structure comprising a
support layer 24 (which multilayer structure is laminated to
backing 12), non-slip layer 14 may first be deposited or formed
upon support layer 24 by any suitable method. For example, non-slip
layer 14 may comprise any suitable hot melt coatable, solvent-born,
water-borne, or polymerizable composition, which may be deposited
(e.g., coated) upon support layer 24. This process may be performed
in-line with the laminating of the resulting multilayer structure
to backing 12; or, the multilayer structure may be rolled up and
stored until laminated to backing 12 in a separate operation. The
coating of non-slip material upon support layer 24 may be performed
by any suitable method. For example, the materials making up
non-slip layer 14 may collectively comprise a hot-melt coatable,
100% solids mixture (e.g., with little or no solvent, water, etc.).
The material of non-slip layer 14 may be hot-melt coated onto
support layer 24 using, for example, roll coating, hot melt
coating, spray coating, drop die coating, etc. In one embodiment, a
roller used to apply the coatable non-slip material is a foam
roller, which may impart a surface texture to the non-slip layer.
Alternatively, a foam roller may be used to post treat the non-slip
layer 14 after it has been coated onto support layer 24, thereby
imparting the non-slip layer with a surface texture.
[0068] In another approach, an aqueous emulsion or aqueous
dispersion of a non-slip coating material may be coated onto
support layer 24. In another approach, a solution (e.g., in an
organic solvent or solvent mixture) of a non-slip coating material
may be coated onto support layer 24 and the solvent evaporated. In
still another approach, a non-slip coating material precursor
(e.g., comprising a mixture of polymerizable components that may be
reacted so as to form the non-slip coating) may be coated onto
support layer 24 and caused to react, causing the precursor to be
transformed into the non-slip coating.
[0069] The multilayer structure comprising support layer 24 and
non-slip layer 14 coated thereupon may be laminated to the first
major side of backing 12 (with major surface 14a of non-slip layer
14 facing outward) by any suitable method. For example, in the
exemplary embodiment shown in FIG. 3, a laminating adhesive 20 may
be used to bond to major surface 24b of support layer 24 and to
major surface 12a of backing 12. In embodiments in which support
layer 24 is of suitable composition to serve as an adhesive layer,
surface 24b of support layer 24 may be bonded directly to major
surface 12a of backing 12.
[0070] In some cases, it may be convenient to deliver non-slip
layer 14 (or a multilayer construction of non-slip layer 14 and
support layer 24) to the lamination process, on a temporary
supporting liner 26 as exemplified in FIG. 6. Such a temporary
supporting liner may be separated from non-slip layer 14 and
discarded (or re-used) once non-slip layer 14 is laminated in place
on the first major side of backing 12. (FIG. 6 shows abrasive sheet
10 with temporary support liner 26 partially removed). Optionally,
liner 26 may be retained in place, either during the rolling up of
abrasive article 10 as a roll good, or even after abrasive article
10 is separated (cut) into individual sheets of sandpaper, in which
case it may be removed by an end user prior to the use of the
sheets of sandpaper. Although not shown in FIG. 6, a temporary
supporting liner 26 may also be used in the case that non-slip
layer 14 is supported on a support layer 24 that becomes part of
final product 10. In fact, it may be convenient to use a temporary
support liner 26 in any of the configurations and embodiments
disclosed herein.
[0071] By way of still further example, constructions of the
general type exemplified in FIGS. 4 and 5 may be made by depositing
the material of non-slip layer 14 (e.g., as a molten,
solvent-borne, or water-borne material) onto support web 22. The
material of non-slip layer 14 may then flow at least partially into
the interior of support web 22. In the particular exemplary
embodiments of FIGS. 4 and 5, this was performed such that support
web 22 is completely buried within major surface 14a and 14b of
non-slip layer 14. However, this does not necessarily have to be
the case. In some embodiments, first major surface 22a of support
web 22 may protrude at least partially through portions of major
surface 14a of non-slip layer 14, as long as such protruding
portions of support web 22 do not unacceptably affect the non-slip
properties of non-slip layer 14. Likewise, in some embodiments,
second major surface 22b of support web 22 may protrude at least
partially through portions of major surface 14b of non-slip layer
14, as long as such protruding portions do not unacceptably affect
the ability of non-slip layer 14 to bond (either directly to
surface 12a of backing 12 in the configuration of FIG. 4, or to
surface 20a of adhesion-enhancing layer 20 in the configuration of
FIG. 5).
[0072] In general, non-slip layer 14 may be provided on backing 12
according to any suitable procedure and configuration described
herein. That is, layer 14 may be bonded directly to backing 12 if
its composition facilitates this. Or, non-slip layer 14 may be
provided on the first major side of backing 12, by use of any
convenient combination of the herein-disclosed adhesion-enhancing
layers (whether adhesive layers or adhesion-promoting layers, or
both), and/or support layers. In some embodiments, the only layer
present between non-slip layer 14 and backing 12 is an adhesive
layer. In other embodiments, exactly one adhesive layer and exactly
one adhesion-promoting tie layer or primer layer are present
between non-slip layer and backing 12. In other embodiments,
exactly one support layer and exactly one adhesive layer are
present between non-slip layer 14 and backing 12. In still other
embodiments, exactly one support layer, exactly one adhesive layer,
and exactly one adhesion-promoting tie layer or primer layer, are
present between non-slip layer 14 and backing 12.
[0073] In general with regard to the herein-discussed lamination
processes, by lamination is meant bonding of sheet-like substrates
or layers to each other, as achieved by bringing the surfaces of
the layers (or any adhesion-enhancing layer as might be present
thereon, as discussed elsewhere herein) into contact with each
other, optionally facilitated by heat and/or pressure, e.g.
depending on the type of adhesive and bonding mechanism. For
example, if non-slip layer 14 comprises a heat-bondable
composition, and/or if adhesion-enhancing layer 20 comprises a
heat-bondable composition, the laminating process may comprise
heating the compositions up to appropriate temperatures e.g. by
placing the layers between one or more pairs of heated surfaces
(e.g., of nip rollers or of heated platens) that press the layers
against each other. If adhesion-enhancing layer 20 comprises a
pressure-sensitive adhesive composition, such pairs of pressing
surfaces (e.g. nip rolls) may still be used; however the laminating
process may not necessarily require significantly elevated
temperatures (although at least some slightly elevated temperature
may be preferred in order to promote optimal wet-out of the
pressure-sensitive adhesive).
[0074] In many cases, it may be convenient to provide at least
backing 12 as a roll good, and likewise to provide at least
non-slip layer 14 (or, a multilayer construction comprising at
least non-slip layer 14 and a support layer 24) as a roll good, and
to perform the lamination by way of passing the components through
one or more pairs of nip rollers, as will be familiar to those of
ordinary skill. However, if desired discrete sheets rather than
roll goods may be used; such sheets may be passed piecewise through
nip rolls, or may be laminated between (non-rotating) platens,
again as will be familiar to those of ordinary skill.
[0075] In many instances, it may be convenient to provide backing
layer 12, make coat 16, and abrasive particles 18 in the form of a
pre-formed (i.e. otherwise complete) abrasive sheet (whether
discrete sheets or as a roll good) and then laminate non-slip layer
14 thereto, by any of the methods disclosed above.
[0076] Any suitable pre-formed abrasive (whether sheet or roll
good) may be used, comprising a wide variety of commercially
available conventional sandpaper constructions having a wide
variety of backing materials (e.g. papers, films, cloths), weights
(e.g. A, B, or C weight paper), and abrasive particles.
Representative examples of suitable pre-formed abrasive articles
include various products available from 3M Company (e.g., under the
Sand Blaster or Pro Grade trade designations) with FEPA ratings
ranging from e.g. P40 to P2500.
[0077] In a specific embodiment, sandpaper 10 as disclosed herein
may be provided to an end user as a standard 9.times.11 inch sheet.
In other embodiments, the sandpaper 10 may have a width of about 3
to about 4 inches, or of about 5 to about 6 inches, and a length of
about 8 to about 10 inches, or about 10 to about 12 inches. In
another aspect, the present invention provides a package of
sandpaper including a stack of sheets of sandpaper. The stack may
include at least 2 sheets, at least about 6 sheets, or at least
about 10 sheets. Optionally, disposable liners, protective films,
etc. may be provided in between the sheets, if desired. In some
embodiments, sandpaper 10 may be provided to an end user as a roll
good which may be used in this form or from which individual sheets
may be separated as desired.
[0078] In some end use applications, the sheet-like abrasive
article (e.g., sandpaper)10 may be used for hand sanding a work
surface, such as a wooden surface or work piece. That is, the
abrasive article 10 may be used to remove material from a surface
by holding the abrasive article 10 directly with one's hand (i.e.
without the aid of a tool, such as a sanding block), and moving the
abrasive article 10 against the work surface. Thus in this context
hand sanding is distinct from operations in which sandpaper is held
and motivated by a device such as a polishing shoe, vibrating or
orbital sander, and the like. However, it will be recognized that
the abrasive articles disclosed herein may also be used with
manually-operated sanding tools and sanding blocks, or with powered
equipment, as may be desired.
[0079] In use, users may often fold an abrasive article (e.g.,
sandpaper), thereby producing sheets that are easier to handle by
hand. Folding the sandpaper, however, may weaken the sandpaper
along the fold line, particularly if, during sanding, the sections
of the folded sandpaper slip relative to each other so that the
fold line traverses (moves) along the sandpaper. Such moving of a
fold line along an abrasive article may e.g. cause the backing to
weaken, crack, etc. over portions of the article, and may thus
reduce the working life of the abrasive article. It has been
discovered that the use of a non-slip layer on the first major side
of an abrasive article may minimize or prevent such slippage from
occurring. That is, in hand sanding with an abrasive sheet that is
folded upon itself so that areas of the non-slip layer of the
article first major side are adjacent each other in closely facing
relation, even in the presence of loose particulates the non-slip
layer areas may be able to maintain contact with each other, and to
resist slipping relative to each other, so that the sheet remains
largely in the originally folded configuration rather than the
areas slipping relative to each other such that the fold in the
sheet traverses along the sheet. This may be advantageous and may
e.g. prolong the working life of the abrasive sheet. Such
discoveries, and further details of non-slip layers, are discussed
in further detail in U.S. Patent Application Publication
2009/0325470 to Petersen, entitled Sandpaper With Non-Slip Coating
Layer, which is incorporated by reference in its entirety
herein.
[0080] In some instances, (e.g., with particularly coarse grades of
sandpaper, e.g., with FEPA grades of P100, P80, P60, or P40, and/or
in situations in which large amounts of particulate debris may be
present), it may be advantageous for non-slip layer 14 to comprise
certain compositions, e.g. chosen from those comprising at least
one base resin and at least one tackifying resin. Such compositions
and uses thereof are described in further detail in U.S.
Provisional Patent Application Ser. No. 61/451,680 to Petersen et
al., filed Mar. 11, 2011, entitled Sandpaper With Non-Slip Layer,
and in U.S. Provisional Patent Application Ser. No. 61/451,678 to
Petersen et al., filed Mar. 11, 2011, entitled Coarse Sandpaper
With Non-Slip Coating layer, both of which are incorporated by
reference in their entirety herein.
[0081] In some cases, laminated non-slip layer 14 may comprise a
fibrous layer as mentioned herein. Further details of such
laminated fibrous non-slip layers (as well as other configurations
of fibrous non-slip layers) are described in further detail in U.S.
Provisional patent application Ser. No. ______ (Attorney Docket No.
67614US002) to Petersen, filed evendate with the present
application, and entitled Sandpaper With Fibrous Non-Slip Layer,
and which is incorporated by reference in its entirety herein.
[0082] It will be apparent to those skilled in the art that the
specific exemplary structures, features, details, configurations,
etc., that are disclosed herein can be modified and/or combined in
numerous embodiments. All such variations and combinations are
contemplated by the inventor as being within the bounds of the
conceived invention. Thus, the scope of the present invention
should not be limited to the specific illustrative structures
described herein, but rather extends at least to the structures
described by the language of the claims, and the equivalents of
those structures. To the extent that there is a conflict or
discrepancy between this specification and the disclosure in any
document incorporated by reference herein, this specification will
control.
List of Exemplary Embodiments
Embodiment 1
[0083] A sheet of sandpaper, comprising: a flexible backing layer
having opposed first and second major sides; an adhesive make coat
on the second major side of the backing layer; abrasive particles
at least partially embedded in the make coat, thereby defining an
abrasive surface; and an exposed laminated non-slip layer of less
than about 600 microns in thickness, on the first major side of the
backing layer.
Embodiment 2
[0084] A sheet of sandpaper as defined in embodiment 1, wherein the
non-slip layer is in direct contact with a first major surface of
the first major side of the flexible backing layer.
Embodiment 3
[0085] A sheet of sandpaper as defined in embodiment 1, further
comprising at least one support layer at least a portion of which
is between at least a portion of the non-slip layer and a portion
of the backing layer.
Embodiment 4
[0086] A sheet of sandpaper as defined in embodiment 3, wherein the
non-slip layer is a hot-melt coating layer on the support
layer.
Embodiment 5
[0087] A sheet of sandpaper as defined in any of embodiments 1-2,
wherein the non-slip layer comprises an embedded support layer.
Embodiment 6
[0088] A sheet of sandpaper as defined in any of embodiments 1 and
3-5, further comprising at least one adhesion-enhancing layer at
least a portion of which is between at least a portion of the
non-slip layer and a portion of the backing layer, wherein the
adhesion-enhancing layer is chosen from the group consisting of a
primer layer, a tie layer, and a pressure-sensitive adhesive
layer.
Embodiment 7
[0089] A sheet of sandpaper as defined in any of embodiments 1-6,
wherein the non-slip layer has an average tack level, as measured
by ASTM D2979-88 using a 10 second dwell time, and a probe removal
speed of 1 cm/s of no greater than about 250 grams.
Embodiment 8
[0090] A sheet of sandpaper as defined in any of embodiments 1-7,
wherein the non-slip layer has an average peak static coefficient
of friction of at least about 1 gram when measured according to
ASTM D 1894-08.
Embodiment 9
[0091] A sheet of sandpaper as defined in any of embodiments 1-8,
wherein the non-slip layer has a thickness of less than about 100
microns.
Embodiment 10
[0092] A sheet of sandpaper as defined in any of embodiments 1-9,
wherein the non-slip layer comprises a generally planar exposed
outer surface.
Embodiment 11
[0093] A sheet of sandpaper as defined in any of embodiments 1-10,
wherein the non-slip layer comprises an amorphous base resin, and
an effective amount of a tackifying resin.
Embodiment 12
[0094] A method of making a sheet of sandpaper having a laminated
non-slip layer on the first major side thereof, comprising the
steps of: providing a flexible backing layer having opposed first
and second major sides; coating an adhesive make coat on the second
major side of the backing layer; at least partially embedding
abrasive particles in the make coat, thereby forming an abrasive
surface; and, laminating a non-slip layer onto the first major side
of the backing layer to form an exposed laminated non-slip layer of
less than about 600 microns in thickness on the first major side of
the backing layer.
Embodiment 13
[0095] The method of embodiment 12 wherein the non-slip layer is
laminated directly to a first major surface of the first major side
of the backing layer with no other layers being therebetween.
Embodiment 14
[0096] The method of embodiment 12 wherein one or more adhesive
layers are provided between at least a portion of the non-slip
layer and a portion of the backing layer.
Embodiment 15
[0097] The method of any of embodiments 12 and 14 wherein one or
more tie layers or primer layers are provided between at least a
portion of the non-slip layer and a portion of the backing
layer.
Embodiment 16
[0098] The method of any of embodiments 12 and 14-15 wherein the
non-slip layer is provided on a support layer at least a portion of
which, after the lamination is completed, is positioned between at
least a portion of the non-slip layer and at least a portion of the
backing layer.
Embodiment 17
[0099] The method of any of embodiments 12 and 14-16 wherein the
non-slip layer is delivered to the first major side of the backing
layer while residing on a temporary liner, and wherein the
temporary liner is separated from the non-slip layer after the
lamination is completed.
Embodiment 18
[0100] A method of hand sanding a work surface comprising the steps
of: providing a sheet of sandpaper as defined in any of embodiments
1-11; manually engaging the laminated non-slip layer with a human
hand; and manually moving the sandpaper in a plurality of
directions over the work surface.
Embodiment 19
[0101] A method of hand sanding a work surface comprising the steps
of: providing a sheet of sandpaper made by a method as defined in
any of embodiments 12-17; manually engaging the laminated non-slip
layer with a human hand; and manually moving the sandpaper in a
plurality of directions over the work surface.
* * * * *