U.S. patent application number 08/971851 was filed with the patent office on 2001-12-13 for surface tension relieved mounting material.
This patent application is currently assigned to Minnesota Mining and Manufacturing Company. Invention is credited to HORNBACK III, LOYD R, PEISERT, JOSEPH C..
Application Number | 20010051116 08/971851 |
Document ID | / |
Family ID | 25518870 |
Filed Date | 2001-12-13 |
United States Patent
Application |
20010051116 |
Kind Code |
A1 |
HORNBACK III, LOYD R ; et
al. |
December 13, 2001 |
SURFACE TENSION RELIEVED MOUNTING MATERIAL
Abstract
The present invention provides a mounting article having reduced
or relieved surface tension for pollution control devices which
utilize a monolith structure within a metal housing. The mounting
article comprises a sheet material having major top and bottom
surfaces, a thickness, a length and a width, said sheet material
having at least one score-line in a surface of said sheet material.
The present invention also provides a pollution control device
comprising a housing, a pollution control element disposed within
the housing, and a mounting article of the invention disposed
between the pollution control element and the housing.
Inventors: |
HORNBACK III, LOYD R; (ST
PAUL, MN) ; PEISERT, JOSEPH C.; (ST PAUL,
MN) |
Correspondence
Address: |
SCOTT A BARDELL
3M OFFICE OF INTELLECTUAL PROP COUNSEL
PO BOX 33427
ST PAUL
MN
551333427
|
Assignee: |
Minnesota Mining and Manufacturing
Company
|
Family ID: |
25518870 |
Appl. No.: |
08/971851 |
Filed: |
November 17, 1997 |
Current U.S.
Class: |
422/179 ;
422/180 |
Current CPC
Class: |
F01N 3/2864 20130101;
F01N 3/2857 20130101; F01N 3/2853 20130101 |
Class at
Publication: |
422/179 ;
422/180 |
International
Class: |
F01N 003/28 |
Claims
What is claimed is:
1. A mounting article for mounting a pollution control element
within a pollution control device, said mounting article comprising
a sheet material useful for mounting a pollution control element in
a housing, said sheet material having major top and bottom
surfaces, a thickness, a length and a width, and having at least
one score-line in a surface of said sheet material.
2. The mounting article of claim 1 wherein said score-line is
disposed across the width of a surface of the sheet material.
3. The mounting article of claim 1 wherein said score-line is
disposed across the length of a surface of the sheet material.
4. The mounting article of claim 2 wherein the score-line extends
across the entire width of the sheet material.
5. The mounting article of claim 3 wherein the score-line extends
across the entire length of the sheet material.
6. The mounting article of claim 3 wherein said score-line has a
length that is less than the length of the sheet material.
7. The mounting article of claim 2 wherein the score-line is
perpendicular to the length of said sheet material.
8. The mounting article of claim 3 wherein the score-line is
perpendicular to the width of the sheet material.
9. The mounting article of claim 1 wherein said sheet material has
at least two score-lines in a surface of the sheet material.
10. The mounting article of claim 9 wherein the depth of the
score-lines ranges from about 5 to about 90 percent of the
thickness of the sheet material.
11. The mounting article of claims 1 or 9 wherein the sheet
material is an intumescent sheet material.
12. A pollution control device comprising: a housing; a pollution
control element disposed within the housing; and a mounting article
disposed between the pollution control element and the housing,
said mounting article comprising a sheet material useful for
mounting a pollution control element having major top and bottom
surfaces, a thickness, a length and a width, said sheet material
having at least one score-line in a surface of said sheet
material.
13. The pollution control device of claim 12 wherein said sheet
material has at least two score-lines in a surface of the sheet
material.
14. The pollution control device of claim 13 wherein said
score-lines extend across the entire width of the sheet
material.
15. The pollution control device of claim 14 wherein said
score-lines are perpendicular to the length of the sheet
material.
16. The pollution control device of claim 15 wherein the depth of
the score-lines ranges from about 5 to about 90 percent of the
thickness of the sheet material.
17. The pollution control device of claim 12 wherein the score-line
extends across the length of the sheet material.
18. The pollution control device of claim 12 wherein said sheet
material has said score-line in the top surface of the sheet
material.
19. The pollution control device of claim 13 wherein the sheet
material is intumescent.
20. The pollution control device of claim 13 wherein the sheet
material is intumescent, the score-lines extend across the entire
width of the top surface of the sheet material and perpendicular to
the length of the sheet material and wherein the depth of the
score-lines is about 50 percent of the thickness of the sheet
material.
21. A method of making a mounting article for a pollution control
element comprising the steps of: providing an intumescent or a
non-intumescent sheet material having dimensions suitable for use
as a mounting for a pollution control element; and providing at
least one score-line in a surface of said sheet material.
22. The method of claim 21 wherein at least two score-lines are
provided in a surface of the sheet material.
23. The pollution control device of claim 12 wherein the monolith
has a round shape and the sheet material has a plurality of
score-lines in the top surface of the sheet material and the top
surface of the sheet material faces the housing.
24. The pollution control device of claim 12 wherein the sheet
material has at least one score-line in the bottom surface and the
bottom surface faces the pollution control element.
25. The pollution control device of claim 24 wherein the bottom
surface of the sheet material has a plurality of score-lines
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a mounting article for use
in mounting monolithic structures for use in pollution control
devices. More specifically, the present invention relates to a
sheet material having reduced surface tension that is used to mount
and support monoliths used in pollution control devices.
BACKGROUND OF THE INVENTION
[0002] Intumescent sheet materials are typically used in pollution
control devices to mount and support a fragile monolith within a
housing. The monoliths are typically made of ceramic but may also
be made of metal such as stainless steel. The housings are also
typically made of metal and preferably are made of stainless steel.
Metal housings typically have coefficients of thermal expansion
that are much greater than the thermal expansion coefficients of
ceramic monoliths. The intumescent sheet materials are disposed
between the monolith and the housing to protect the monolith from
damage and to prevent the exhaust gases from bypassing the monolith
and exiting untreated. Typically, the catalysts that are supported
on the monolith do not effectively treat the exhaust gases until
the monolith and the catalyst reaches the optimum operating
temperature. One way of reducing the time required for the monolith
and catalyst to reach the optimum operating temperature is to move
the catalytic converter closer to the engine, which also results in
higher operating temperatures. Because of the higher operating
temperatures, thicker mounting mat materials are required. The
thicker mounting mats keep the housing relatively cool while
maintaining a high temperature gradient across the mounting mat
which is beneficial for the monolith holding performance of the
mounting mat. However, the types of converter monoliths that are
typically used for these applications have relatively smaller
monolith cross-sections, making it difficult to wrap the thicker
mounting materials around the smaller contours of the monolith
without cracking or breaking the sheet material.
SUMMARY OF THE INVENTION
[0003] The present invention provides a mounting article having
reduced or relieved surface tension for pollution control devices
which utilize a monolith structure within a metal housing. The
mounting article comprises a sheet material suitable for mounting a
pollution control; element within a housing having major top and
bottom surfaces, a thickness, a length and a width, said sheet
material having at least one score-line in a surface of said sheet
material. In a preferred embodiment, the sheet material has two
score-lines across the width of the sheet material. In another
preferred embodiment, the sheet material is an intumescent sheet
material.
[0004] The present invention also provides a pollution control
device comprising a housing, a pollution control element disposed
within the housing, and a mounting article of the invention
disposed between the pollution control element and the housing. One
of the advantages of the mounting articles of the invention is that
the invention allows the use of relatively thicker sheet materials
in pollution control devices without undesirable cracking or
breaking of the sheet material.
[0005] As used herein a "score-line" means a controlled and
intended discontinuity in a surface of the sheet material which
does not penetrate the entire thickness of the sheet material used
to mount a pollution control element.
[0006] As used herein "intumescent sheet material" means a sheet
material useful for mounting a pollution control device within a
housing that contains an intumescent material that swells, foams,
or expands when subjected to sufficient thermal energy.
[0007] As used herein, a "non-intumescent sheet material" means a
substantially inorganic, fibrous sheet material which does not
contain an intumescent material and which does not expand beyond
the amount expected from the inherent coefficient of thermal
expansion of the non-intumescent materials when subjected to
thermal energy.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is perspective exploded view of a catalytic converter
showing the mounting article of the present invention.
[0009] FIG. 2 is another view of the catalytic converter of FIG. 1
showing the mounting article of the present invention peeled away
from the monolith.
[0010] FIG. 3A is a plan view of an embodiment of the mounting
article of the invention and FIG. 3B is a front view of an oval
monolith wrapped in the mounting article of FIG. 3A.
[0011] FIG. 4A is a plan view of an embodiment of the mounting
article of the invention and FIG. 4B is a front view of an oval
monolith wrapped in the mounting article of FIG. 4A.
[0012] FIG. 5A is a plan view of an embodiment of the mounting
article of the invention and FIG. 5B is a front view of an oval
monolith wrapped in the mounting article of FIG. 5A.
[0013] FIG. 6A is a plan view of a sheet material having a
plurality of score-lines and FIG. 6B is a front view of a round
monolith wrapped in the mounting article of FIG. 6A.
[0014] FIG. 7A is a cross-sectional view of a sheet material having
a plurality of score-lines and FIG. 7B is a front view of a round
monolith wrapped with the mounting article of FIG. 7A.
[0015] FIG. 8A is a plan view of a sheet material having a
plurality of score-lines on both surfaces and FIG. 8B is a front
view of a round monolith wrapped in the sheet material of FIG.
8A.
[0016] FIGS. 9 and 10 are plan views of other embodiments of the
mounting article of the invention.
[0017] FIG. 11 is a perspective view of a die for making an
embodiment of the mounting articles of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] Although the mounting articles of the present invention are
suitable for use in a variety of pollution control devices, such as
catalytic converters and diesel particulate filters, elements, or
traps, their use is described herein in connection with a catalytic
converter. The description is intended to be illustrative of the
use of the mounting articles of the present invention and should
not be construed as limiting the use of the mounting articles to
catalytic converters.
[0019] Referring to FIGS. 1 and 2, catalytic converter 10 comprises
a metallic housing 12 with generally conical inlet 14 and outlet
16. The housing, which is also known as a can or casing, can be
made from suitable materials known in the art for such use and is
typically made from metal. Preferably, housing 12 is made from
stainless steel. A monolithic catalytic element 18 is disposed
within the housing 12 and is made from a honeycombed monolithic
body of either ceramic or metal. Suitable catalytic elements, also
known as monoliths, are known in the art and include those made
from ceramic or metal. In this embodiment, monolith 18 is generally
oval shaped in cross-section and has areas of maximum or larger
radius of curvature 19 and areas of minimum or smaller radius of
curvature 13. Monolith 18 is used to support the catalyst materials
for the converter. A useful monolith is disclosed, for example, in
U.S. Pat. No. RE 27,747 (Johnson). Monolith has a plurality of gas
flow channels 21 therethrough. The catalyst materials coated onto
the catalytic converter monoliths include those known in the art,
for example, metals such as ruthenium, osmium, rhodium, iridium,
nickel, palladium, and platinum and metal oxides such as vanadium
pentoxide and titanium dioxide. Useful catalytic coatings are
described in more detail in, for example, U.S. Pat. No. 3,441,381
(Keith et al.).
[0020] For purposes of the invention, the monolith may be any shape
that can be wrapped with a sheet material. Examples of such shapes
include those having the cross-sectional shape of a circle,
ellipse, trapezoid, square, rectangle, triangle and polygon.
[0021] Surrounding monolith 18 is surface tension relieved mounting
article 20. Mounting article 20 comprises a sheet material 22
useful for mounting catalytic converters having surface
discontinuities or score-lines 24 into top surface 23 of the sheet
material. Top surface 23 is the surface of the sheet material that
is adjacent to the housing when sheet material 22 is mounted within
a catalytic converter. Bottom surface 25 is the surface of the
sheet material that is adjacent to the monolith when the sheet
material is mounted within a catalytic converter.
[0022] As seen more clearly in FIGS. 3A and 3B, score-lines 24
adjacent each end of sheet material 22 extend transversely and in
parallel across the width and perpendicular to the length of the
sheet material 22. FIG. 3B illustrates a sheet material 22
surrounding an oval shaped monolith 18 and demonstrates how
score-lines 24 relieve surface tension in the sheet. In this
embodiment, score-lines 24 are preferably placed in the top surface
23 of the sheet material 22 at the point or within the area of the
surface which corresponds to the smallest radius of curvature 13 of
the monolith when the sheet material is wrapped around the
monolith. As shown in FIG. 3B, score-lines 24 provide openings 26
in the sheet material 22 that are predictable in location, depth
and width. Predictable openings are advantageous because they can
be taken into account when designing the housing for the catalytic
converter. For example, since the openings in the sheet materials
are predictable, a single converter housing design could be used to
prevent the by-passing of polluting exhaust gases through the
predictable openings and the housings can be easily reproduced in
the quantity desired.
[0023] FIGS. 4A and 5A illustrate other embodiments of the tension
relieved mounting article of the invention. The sheet material 22
of FIG. 4A has two pairs of scores lines 24 in top surface 23 which
corresponds to the smallest radius of curvature of the monolith. As
shown in FIG. 4B, when the sheet material 22 is wrapped around an
oval shaped monolith 18, two predictable openings 26 in the area of
highest tension are formed. FIGS. 5A and 5B show an embodiment of
the mounting article of the invention having three pairs of
score-lines 24 in the top surface 23 of the sheet material 22 and
the resulting predictable openings 26 formed after the monolith 18
is wrapped in the sheet material. One of the advantages of a sheet
material having a plurality or multiple score-lines in areas of
high surface tension is that the length of sheet material required
to wrap a given monolith is reduced by each additional score-line
added to a surface of the sheet material.
[0024] FIGS. 6A and 6B show mounting article 20 comprising a sheet
material 22 having a plurality of score-lines 24 over the top
surface 23 of the sheet material. As shown in FIG. 6B, the
plurality of score-lines 24 provide predictable openings 26 in the
surface of the sheet material. A sheet material having a plurality
of score-lines over the surface of the sheet material is preferred
for round monoliths having relatively small diameters.
[0025] FIG. 7A shows a mounting article 30 comprising a sheet
material 22 having a plurality of score-lines 24 formed by
attaching strips 32 of a mounting material onto a sheet material
layer 34 such that the strips 32 are adjacent one another. The
strips 32 are attached adjacent one another so to provide
score-lines 24 in the surface of the sheet material 22. The
score-lines provide predictable openings 26 in the surface of the
sheet material after the sheet material is wrapped around a round
monolith 18 as shown in FIG. 7B. The strips 32 may be attached to
the sheet material layer by stitching, staples, adhesives and the
like. The width of the score-lines may be determined by the
placement of the strips on a layer of the sheet material. Strips 32
and sheet material layer 34 may be made from the same materials as
those described for sheet materials 22 below. It is also
contemplated that the sheet material layer may also comprise strips
of mounting material that are adhered to strips in a staggered
fashion to provide alternating score lines in both surfaces of a
mounting article.
[0026] FIGS. 8A and 8B illustrate a mounting article 20 of the
invention comprising a sheet material 22 having score-lines 24 on
both surfaces of the sheet material. The score-lines 24 on the
inside surface 25 of sheet material 22 preferably have a greater
width than corresponding score-lines 24 on the outer surface 23 of
the sheet material 22 so to allow for compression of the inner
surface of the sheet material.
[0027] As illustrated in FIGS. 9 and 10, the score-lines 24 may be
provided in the surface of the sheet material 22 in any pattern as
long as the openings created in the sheet material after wrapping a
monolith are predictable and do not provide further undesirable
cracking or propagation of the opening. The score-lines are
preferably straight or linear in form.
[0028] The score-lines can be present across the width or the
length of the sheet material, or both. The score-lines can extend
across the entire width and/or length of the sheet material or the
score-lines can extend across a portion of either or both length
and width. For example, the score-lines may be made such that they
are centered within the length or the width of the sheet material.
The score-lines may also begin at one edge and then extend
partially across the length or width of the sheet material.
Preferably, the score-lines extend across the entire width of the
sheet material.
[0029] Sheet material 22 may be any resilient sheet that is useful
for mounting monoliths, filter elements, or traps within a housing.
The sheet material may comprise non-intumescent materials,
intumescent materials or a combination thereof. The sheet material
may be mutilayered in structure, for example, two or more
relatively thin intumescent or non-intumescent sheet materials
adhered or laminated together to form a uniform, thicker sheet
material. Useful adhesives include web adhesives and hot melt
adhesives. A preferred adhesive is a web adhesive.
[0030] Examples of useful non-intumescent sheet materials include
those made from ceramic fibers. Useful ceramic fibers include
alumina-boria-silica fibers, alumina-silica fibers,
alumina-phosporous pentoxide fibers, zirconia-silica fibers,
zirconia-alumina fibers, and alumina fibers. Commercially available
fibers include those under the trademarks FIBERMAX, available from
Unifrax, SAFFIL LD, available from ICI Chemicals and Polymers,
ALCEN alumina fibers, available from Denka, and MAFTECH fibers,
available from Mitsubishi.
[0031] The fibers are typically formed by blowing or spinning using
methods known in the industry. The fibers are formed into a sheet
by various known methods including blowing the fibers onto a
collection screen as is practiced in the nonwoven industry.
Non-intumescent sheet materials may also be made by wet-laid or
papermaking techniques. Non-intumescent sheets made of ceramic
fibers are generally compressed and held in the compressed state to
facilitate handling during the canning process. Compression
techniques include resin bonding, stitch bonding, or vacuum
packing.
[0032] Preferably, sheet material 22 comprises a resilient,
flexible intumescent sheet comprising from about 5 to about 65
percent by weight of unexpanded vermiculite particles or flakes,
such flakes being either untreated or treated by being ion
exchanged with an ammonia compound such as ammonium dihydrogen
phosphate, ammonium carbonate, ammonium chloride, or other suitable
ammonium compound as described in U.S. Pat. No. 4,305,992 (Langer
et al.), incorporated herein by reference; from about 10 to about
60 percent by weight of inorganic fibers including aluminosilicate
fibers, glass fibers, zirconia-silica, and crystalline alumina
fibers; from about 3 to about 25 percent by weight of an organic
binder, for example, natural rubber latices, styrene-butadiene
latices, butadiene acrylonitrile latices, latices of acrylate or
methacrylate polymers and copolymers and the like; and up to about
40 percent by weight of inorganic filler material such as expanded
vermiculite, hollow glass microspheres, and bentonite and other
clays and the like. Useful intumescent sheet materials also include
those described in U.S. Pat. No. 5,523,059 (Langer), incorporated
by reference herein.
[0033] Further examples of useful intumescent sheet materials
include those described in U.S. Pat. Nos. 3,916,057 (Hatch et al.),
4,305,992 (Langer et al.), 4,385,135 (Langer et al.), 5,254,410
(Langer et al.), 4,865,818 (Merry et al.), 5,151,253 (Merry et
al.), and 5,290,522 Rogers et al.), all of which are incorporated
by reference herein. Useful commercially available intumescent mats
and sheets include those sold under the INTERAM trademark by
Minnesota Mining & Manufacturing Company of St. Paul, Minn.
[0034] Available single layer intumescent sheet materials typically
range in thickness from about 0.5 mm to about 15 mm. If two
intumescent sheets are attached together, by mechanical means such
as adhesive, staples or stitches and the like, then the thickness
of the sheet materials typically range from about 1 mm to about 30
mm. Preferably, the thickness of the sheet material used in the
present invention ranges from about 0.8 mm to about 20 mm and more
preferably from about 6 mm to about 20 mm.
[0035] The score-lines may be placed in or cut into either surface
or both surfaces of the sheet material and are preferably placed
into the surface of the intumescent sheet material which is
adjacent to the can or casing of the catalytic converter, the top
surface. The score-lines are also preferably placed into the
surface of the intumescent sheet material such that they correspond
to the minimum radius of curvature of the monolith. The only
limitation to the depth of a score-line into the surface of the
sheet material is such that the score-line does not go completely
through the entire width of the sheet material or otherwise is cut
to such a depth that when the sheet material is wrapped around the
monolith and placed under stress, the score-line does not tear or
propagate completely through the sheet material.
[0036] On the other hand, the score-line should not be so shallow
so that when the sheet material is wrapped around the monolith and
placed under tension, that the score-line results in unpredictable
tearing or propagating which results in an undesirable depth, width
or direction of the score-line. The depth of the score-lines is
also related to the radius of curvature of the monolith which is
directly related to the amount of surface tension placed on the
sheet. As the radius of curvature decreases, the amount of surface
tension in the corresponding region of the sheet increases. The
limit of the depth of the score-lines for any particular end use
can easily be determined by one skilled in the art without undue
experimentation.
[0037] Preferably, the depth of the score-line may range from about
20 to about 90 percent of the thickness of the sheet material. More
preferably, the depth of the score-lines is about 50 percent of the
thickness of the sheet material.
[0038] The width of the score-lines when the sheet material is flat
is not limited as long as the resulting gap or opening in the
surface of the sheet material is repeatable and predictable in
depth and width when the sheet material is wrapped around a
monolith. Useful cross-sectional shapes for score-lines include
vertical line shaped, "V"-shaped, "U"-shaped, triangular shaped,
and square shaped. Generally, the widths of the score-lines may be
up to about 20 mm. Preferably, the width of the score-line ranges
from 0 (die cut) to about 5 mm.
[0039] The distance between adjacent multiple score-lines will
depend on the particular end use. Accordingly, the distance between
score-lines should be such that the tension in the surface of the
sheet is relieved without undesirable propagating or tearing of the
score-line and which results in a predictable opening when the
sheet material is wrapped around a monolith. Generally, the
distance between adjacent score-lines ranges from about 1 mm to
about 100 mm with a distance between adjacent multiple score-lines
being from about 1 mm to about 30 mm being preferred.
[0040] The score-lines may be formed or placed into the surface of
the sheet material by any means known in the art. Useful score-line
producing means include cutting, such as die cutting and forming
the score-lines, for example by attaching spaced strips to a layer
of sheet material or by other forming means.
[0041] Preferably, the score-lines are cut into a surface of an
intumescent or non-intumescent sheet material by any convenient
cutting means, such as by a utility knife, a razor and the like.
More preferably, the score-lines can be cut into the surface of the
sheet material simultaneously when the sheet material is die cut
from a large sheet (not shown) to a predetermined size and shape.
FIG. 11 shows die 40 having a base 42 and a cavity 44 defined by
die perimeter 46. Within cavity 44 are two scoring die rules 48 and
a foamed ejection material 50. Die perimeter 46 and scoring dies 48
are typically made of metal, such as steel or stainless steel, and
the base can be any rigid substrate, such as wood, plastic or metal
and the like.
[0042] The thickness or height of scoring die rules 48 corresponds
to the desired depth of the resulting score-lines and is less than
the height of the perimeter die. The various heights of the scoring
dies and the perimeter die may be adjusted depending on the
thickness of the particular sheet material being cut. Of course the
length of the sheet material is determined by the circumference of
the monolith to be wrapped. The sheet materials of the invention
have a length such that the two ends of the wrapped sheet material
meet without overlapping and have no visible gap between the
ends.
[0043] In use, a sheet of intumescent or non-intumescent mounting
material is placed on top of die 40, pressure is applied onto the
sheet material from a die cutter (not shown) and a scored and
die-cut mounting article may be easily removed from the die due to
foamed and resilient ejection material 50.
[0044] In use, the scored sheet materials of the invention are
disposed between the monolith and the housing in similar fashion
for either a catalytic converter of a diesel particulate filter.
This may be done by first wrapping the monolith with a mounting
article of the invention making sure that the score-lines are
positioned at the points of minimum or smallest radius of curvature
of the monolith (if the monolith is a shape other than round), as
shown in FIGS. 3-5, inserting the wrapped monolith into a housing,
and then welding or otherwise closing the housing. Preferably, the
sheet materials of the invention have an interlocking tab 27 and
notch 29 as shown, for example, in FIG. 3A to assure a gas seal
despite minor variations in monolith circumference.
[0045] The score-lines of the invention provide an economical and
simple means to relieve the surface tension in intumescent and
non-intumescent sheet materials encountered during wrapping of
monoliths. The sheet materials of the invention may be of any
thickness with the score-lines having particular use and utility in
thicker (greater than about 6 mm) and/or less flexible intumescent
and non-intumescent sheet materials. The score-lines also offer the
advantage of allowing for the use of shorter pieces of intumescent
sheet material than would otherwise be required without the
score-lines. This results in a more efficient use of raw materials
and a lower cost of manufacture.
[0046] Objects and advantages of this invention are further
illustrated by the following examples, but the particular materials
and amounts thereof should not be construed to unduly limit this
invention. All parts and percentages are by weight unless stated
otherwise.
EXAMPLES
Examples 1-3 and Comparative Example C1
[0047] Two 685.8 mm by 685.8 mm layers of intumescent sheet
material (INTERAM brand Type 100 Mat, 3100 g/m2, available from
Minnesota Mining & Manufacturing Company) were laminated
together using a web adhesive to form a sheet material having a
total thickness of about 9.8 mm. Four 100 mm by 500 mm sheets were
cut using a utility knife. Example 1 was made by cutting about
halfway through the thickness of the sheet material with a utility
knife across the width of the sample intumescent sheet. Two
score-lines corresponding to the small radii of the monolith were
cut into the sample sheet material. Examples 2 and 3 were made as
described above, except for having 2 and 3 score-lines (4 and 6
total), respectively, corresponding to each small radius of
curvature of the monolith. Comparative example C1 was a 100 mm by
500 mm sheet material as described above without score-lines.
[0048] Each of Examples 1, 2, and 3 and the comparative example C1
were wrapped around a ceramic monolith having dimensions of 3.18 in
(8 cm) (minor axis).times.6.68 in (17 cm) (major axis) (from
Corning, Corning, N.Y.) to determine the actual length necessary to
achieve a complete wrap of the monolith. A "complete wrap" of the
monolith for purposes of the Examples means that the two ends of
the wrapped sheet material meet without overlapping and have no
visible gap between the ends.
[0049] The lengths needed for each sample to completely wrap the
monolith were as follows:
1 Control (C1) 461 mm no score-lines Example 1 456 mm 2 score-lines
Example 2 455 mm 4 score-lines Example 3 453 mm 6 score-lines
[0050] The above data demonstrate that the intumescent sheet
materials of the invention require less intumescent sheet material
to completely wrap a monolith than a sheet material wherein no
surface tension is relieved.
Example 4
[0051] A scored sheet material of the invention was made using a
die illustrated in FIG. 11. The die had a die rule perimeter height
(above the base) of 0.5 in (1.27 cm) and a scoring die rule height
(above the base) of about 0.302 in (0.77 cm) and was made of steel.
The width or gauge of the die perimeter and the scoring dies was
about 0.042 in (1.07 mm) and 0.028 in (0.71 mm) respectively. The
ejection material was a 0.375 in (0.95 cm) thick soft elastomeric
material.
[0052] A sample of the laminated sheet material described above in
Examples 1-3 was die cut with the die using a ROTOMATIC II brand
die cutter, available from Ampak, Inc., Anderson, S.C. The die cut
and scored sheet material could be easily removed from the die
without cracking or breaking. The scored sheet material was flexed
by hand to simulate the wrapping of a monolith. The two score-lines
formed openings in the sheet material which had uniform widths and
depths without undesirable cracking or propagating.
Example 5 and Comparison Sample C2
[0053] Two INTERAM brand type 100 intumescent mats were laminated
together with a web adhesive to form a sheet material having a
basis weight of about 6200 g/m.sup.2. The sheet material was cut
into two approximately 97 mm.times.400 mm sheet materials for
wrapping a ceramic oval monolith having a major axis of 5 in (12.7
cm), minor axis of 2.5 in (6.35 cm) and a length of 4.37 in (11.1
cm). The monolith was initially wrapped with the sheet material for
sizing and the excess length was cut away. The monolith was wrapped
with the sized sheet material C2 (no score-lines) and random
surface cracks appeared in the areas of smallest radius curvature
(major axis).
[0054] Two score-lines were cut into the other 97 mm.times.400 mm
sheet material and were spaced such that each score-line would
correspond to areas of smallest radius of curvature. The
score-lines extended into the sheet material to a depth of about
50% of the thickness of the sheet material and extended across the
total width of the sheet. The sheet material was cut to the
appropriate length and the monolith was wrapped. Uniform openings
in the areas of the score-lines were observed with no additional
random surface cracking observable.
Example 6 and Comparative Example C3
[0055] Sheet materials were prepared as in Example 5 above except
that the Example 6 sheet material had eight evenly spaced
score-lines in its surface. Each of the score-lines extended
completely across the width of the sheet. Each of the above sheet
materials were wrapped around a round ceramic monolith having a
diameter of 2.66 in (6.76 cm) and a length of 4 in (10.2 cm). A
random crack in the surface of the comparison sheet material
extended across the width of the sheet. The sheet material of
Example 6 provided uniform openings in the area of the score-lines
without any additional random cracking.
Example 7
[0056] A sheet of INTERAM brand Type 100 intumescent mounting sheet
was cut into nine 4 in (10.2 cm).times.1 in (2.54 cm) strips. These
strips were adhered (Case Sealing Adhesive, Minnesota Mining and
Manufacturing Company) to the surface of a 4 in (10.2 cm).times.9
in (22.9 cm) sheet of INTERAM brand Type 100 intumescent sheet
material, the strips contacting one another. The sheet material was
wrapped around the round monolith as in Example 5 such that the
score-lines provided openings that faced away from the monolith.
The openings were predictable and uniform. No additional random
cracks were observed.
* * * * *