Language selection

Search

Patent 2245620 Summary

Third-party information liability

Some of the information on this Web page has been provided by external sources. The Government of Canada is not responsible for the accuracy, reliability or currency of the information supplied by external sources. Users wishing to rely upon this information should consult directly with the source of the information. Content provided by external sources is not subject to official languages, privacy and accessibility requirements.

Claims and Abstract availability

Any discrepancies in the text and image of the Claims and Abstract are due to differing posting times. Text of the Claims and Abstract are posted:

  • At the time the application is open to public inspection;
  • At the time of issue of the patent (grant).
(12) Patent: (11) CA 2245620
(54) English Title: METHOD FOR MEASURING THE QUANTITY OF A POLYMERIC OR PRE-POLYMERIC COMPOSITION
(54) French Title: PROCEDE DE MESURE QUANTITATIVE D'UNE COMPOSITION POLYMERE OU PRE-POLYMERE
Status: Deemed expired
Bibliographic Data
(51) International Patent Classification (IPC):
  • G01N 15/06 (2006.01)
  • G01N 27/00 (2006.01)
  • G01N 27/72 (2006.01)
  • G01N 33/44 (2006.01)
(72) Inventors :
  • YORKGITIS, ELAINE M. (United States of America)
  • CHAMBERLAIN, CRAIG S. (United States of America)
(73) Owners :
  • MINNESOTA MINING AND MANUFACTURING COMPANY (United States of America)
(71) Applicants :
  • MINNESOTA MINING AND MANUFACTURING COMPANY (United States of America)
(74) Agent: SMART & BIGGAR
(74) Associate agent:
(45) Issued: 2007-02-06
(86) PCT Filing Date: 1996-07-24
(87) Open to Public Inspection: 1997-09-12
Examination requested: 2003-07-22
Availability of licence: N/A
(25) Language of filing: English

Patent Cooperation Treaty (PCT): Yes
(86) PCT Filing Number: PCT/US1996/012197
(87) International Publication Number: WO1997/033162
(85) National Entry: 1998-08-05

(30) Application Priority Data:
Application No. Country/Territory Date
08/610605 United States of America 1996-03-08

Abstracts

English Abstract





A method for measuring the quantity of a polymeric or pre-polymeric
composition within a given volume that includes combining the
polymeric or pre-polymeric composition with a plurality of micro particles
having a non-ferromagnetic or non-ferrimagnetic core provided
with a coating that is ferromagnetic, ferrimagnetic, or conductive, to form an
admixture in which the microparticles are substantially
uniformly dispersed throughout the composition. The microparticles have a
detectable electromagnetic characteristic which correlates with
the amount of the composition within a given volume. The electromagnetic
characteristic of the microparticles is then measured to determine
the quantity of the composition within a given volume.


French Abstract

La présente invention concerne un procédé de mesure quantitative d'une composition polymère ou pré-polymère dans un volume donné. Ce procédé consiste à combiner la composition polymère ou pré-polymère à des microparticules dont le noyau, qui n'est ni ferromagnétique ni ferrimagnétique, est pourvu d'un enrobage ferromagnétique, ferrimagnétique ou conducteur, de façon à former un mélange de complément caractérisé par une dispersion sensiblement uniforme des microparticules dans toute la composition. Ces microparticules possèdent une caractéristique électromagnétique qui est en corrélation avec la quantité de la composition à l'intérieur du volume considéré. Le procédé consiste ensuite à mesurer la caractéristique électromagnétique des microparticules pour déterminer la quantité de composition à l'intérieur du volume considéré.

Claims

Note: Claims are shown in the official language in which they were submitted.





What is claimed is:

1. A method for measuring the quantity of a polymeric or pre-
polymeric composition within a given volume comprising the steps of:
(a) combining said polymeric or pre-polymeric composition with a
plurality of microparticles comprising a non-ferromagnetic or non-
ferrimagnetic core provided with a coating that is ferromagnetic,
ferrimagnetic, electrically conductive or a combination thereof to form
an admixture in which said microparticles are substantially uniformly
dispersed throughout said composition,
said microparticles having a detectable electromagnetic
characteristic which correlates with the amount of said composition
within a given volume; and
(b) measuring said electromagnetic characteristic of said
microparticles to determine said quantity of said composition within a
given volume.

2. The method of claim 1, wherein said core of said microparticles
is selected from the group consisting of glass bubbles, glass beads, glass
fibers,
fumed silica particles, fused silica particles, mica flakes, polymeric
particles, and
combinations thereof.

3. The method of claim 1 wherein said coating comprises an
electrically conductive coating.

4. The method of claim 1 wherein said coating comprises a
ferromagnetic or ferrimagnetic coating.

5. The method of claim 1 wherein said coating comprises stainless
steel.

-24-




6. The method of claim 1 wherein said microparticles comprise
metal-coated glass bubbles.

7. The method of claim 1 wherein said coating comprises a
ferromagnetic or ferrimagnetic composition selected from the group consisting
of
nickel, iron, cobalt, alloys thereof and oxides thereof.

8. The method of claim 1 comprising combining a first polymeric or
pre-polymeric composition with a second polymeric or pre-polymeric composition
to form a reaction mixture, said method comprising combining at least one of
said
polymeric or pre-polymeric compositions with said microparticles prior to
combining said first and second polymeric or pre-polymeric compositions
together.

9. The method of claim 8 wherein said microparticles in said first
polymeric or prepolymeric compositions are different from said microparticles
in
said second polymeric or prepolymeric composition.

10. The method of claim 1 comprising depositing said admixture on a
substrate and measuring the electromagnetic characteristic of said
microparticles to
determine the amount of said admixture deposited on said substrate.

-25-


Description

Note: Descriptions are shown in the official language in which they were submitted.



CA 02245620 1998-08-OS
WO 97/33162 PCT/U596/12197
METHOD FOR MEASURING THE QUANTITY OF A
POLYMERIC OR PRE-POLYMERIC COMPOSITION
Background of the Invention
The invention relates to measuring the quantity of a polymeric or pre-
polymeric composition within a given volume.
Processes for manufacturing polymeric compositions (e.g., adhesives such
as structural adhesives) often require adding or combining precise amounts of
pre-
polymeric components forming these compositions, particularly where these
components react together to form the composition. Devices dispensing these
components can malfunction periodically and/or systematically, resulting in
the
deposition of an incorrect mix of the components. These malfunctions can
significantly
affect the quality of the resulting products.
It is also desirable to be able to measure the quantity of polymeric or pre-
polymeric material in any given volume of an article incorporating the
material. For
example, in the case of a structural adhesive joining two substrates together,
it is
desirable to measure the thickness of the adhesive throughout the adhesi~,~e
joint to
determine whether the thickness is uniform. Non-uniformities can affect the
performance of the joint, causing it to under perform in some circumstances.
Summary of the Invention
In general, the invention features a method for measuring the quantity of a
polymeric or pre-polymeric composition within a given volume that includes
combining
the polymeric or pre-polymeric composition with a plurality of microparticles
having a
non-ferromagnetic or non-ferrimagnetic core provided with a coating that is
ferromagnetic, ferrimagnetic, or conductive, to form an admixture in which the
microparticles are substantially uniformly dispersed throughout the
composition. The
microparticles have a detectable electromagnetic characteristic which
correlates with
the amount of the composition within a given volume. The electromagnetic
-1-


CA 02245620 1998-08-OS
WO 97/33162 PCT/IJS96/12197
characteristic of the microparticles is then measured to determine the
quantity of the
composition within a given volume.
As used herein, a "pre-polymeric composition" refers both to compositions
whose molecular weight has not been su~ciently advanced to qualify as a
polymeric
composition (e.g., partially polymerized pre-polymeric syrups}, as well as
individual
reactants in the form of monomers or oligomers that react with themselves or
with
other reactants to form a polymeric composition.
In preferred embodiments, the core of the microparticles is selected from
the group consisting ofglass bubbles, glass beads, glass fibers, fumed silica
particles,
fused silica particles, mica flakes, polymeric particles, and combinations
thereof, with
glass bubbles being particularly preferred. The coating (which may be provided
over
substantially all or a portion of the surface of the core) is preferably a
ferromagnetic or
ferrimagnetic material. Examples of suitable ferromagnetic or ferrimagnetic
materials
include nickel, cobalt, iron, alloys thereof and oxides thereof Stainless
steel coatings
are particularly preferred. Other preferred coatings include electrically
conductive
coatings.
The dimensions of the microparticles preferably have a major dimension
between about 10 micrometers and about I millimeter. The average thickness of
the
coating preferably ranges from about 0.1 manometers to about 5 micrometers,
more
preferably from about 1 manometer to about 200 manometers. The amount of
microparticles provided in the admixture preferably ranges between about 0.01
and
50% by volume.
In one preferred embodiment, the method is used to measure the quantity
of a polymeric or pre-polymeric composition being dispensed, e.g., into a
reaction
mixture. According to this embodiment, the admixture containing the
microparticles
and pre-polymeric or polymeric composition is dispensed while measuring an
electromagnetic characteristic of the micropartictes to determine the quantity
of the
polymeric or pre-polymeric composition being dispensed.
-2-


CA 02245620 1998-08-OS
WO 97/33162 PCT/US96/12197
In yet another preferred embodiment, a first polymeric or pre-polymeric
composition and a second polymeric or pre-polymeric composition are combined
to
° form a reaction mixture. At least one of the polymeric or pre-
polymeric compositions
is combined with the microparticles prior to combining the first and second
polymeric
or pre-polymeric compositions together. In a preferred embodiment, the
electromagnetic characteristic of the microparticles in the reaction mixture
is
measured. The microparticles can be placed in both the first and second
polymeric or
pre-polymeric compositions. The microparticles in the first and second
polymeric or
pre-polymeric compositions can be different from each other. Another
embodiment
includes combining the microparticIes with one of the polymeric or pre-
polymeric
compositions and measuring the electromagnetic characteristic of the reaction
mixture
to determine the ratio of the first and second polymeric or pre-polymeric
compositions
to each other.
In another preferred embodiment (useful, e.g., for quality control
1 S rrsP~c~rPmP_n_tc)~ t_h_P ac~mi_xtur~~ det~O~ited On ~r between
aSubStraLe111dtllE
electromagnetic characteristic of the microparticles is measured to determine
the
amount of the admixture deposited on the substrate. In this way, for example,
variations in the thickness of the deposited material can be detected.
One example of a useful polymeric composition is an adhesive composition.
Specific examples of preferred polymeric compositions include epoxy resins
(e.g., base
cured epoxies, acid cured epoxies, and addition cured epoxies), polyurethanes,
acrylates, silicones, and phenolics.
The invention provides a low-cost, reliable method for measuring the
quantity of a polymeric or pre-polymeric composition within a given volume
using
microparticle "tags" having a detectable electromagnetic characteristic. The
microparticles are easily fabricated and are generally chemically inert and
stable over
reasonable periods of time.
Moreover, certain properties of the microparticles are very similar to their
uncoated counterparts. For example, metal-coated glass microbubbles impart
-3-


CA 02245620 1998-08-OS
WO 97/33162 PC~'/LTS96/12197
substantially the same rheological behavior and mechanical properties as their
uncoated
counterparts. Thus, the microparticles can be substituted virtually one-for-
one for
their uncoated counterparts on a volume basis without adversely affecting the
properties of the f nal composition.
Other features and advantages of the invention will be apparent from the
following description of the preferred embodiments thereof, and from the
claims.
Brief Description of the Drawings
Figure 1 is a plot of inductive reactance versus loading of coated
microparticles in percent volume fraction.
Figure 2 is a plot of inductive reactance versus coating thickness.
Figure 3 is a plot of permeability versus coating thickness.
Figure 4 is a plot of inductive reactance versus permeability.
Figure 5 is an Eddyscope scan of an aluminum-epoxy-aluminum structure.
Figure 6 is a plot of inductance versus coated microparticle loading in
percent volume fraction.
Figure 7 is a plot of capacitance versus coated microparticle loading in
percent volume fraction.
Figure 8 is an Eddyscope scan of a plastic tray.
Figure 9 is a physical map of the tray of Figure 8 made using the
Eddyscope readings.
Figure 10 is a plot of capacitance versus displacement along a width of the
tray of Figure 8 with a schematic of the cross section of the tray shown below
the plot.
Figure 1 i is an Eddyscope scan indicating the different reading obtained
with different ratios of one component of an adhesive mixed with a second
component
of an adhesive.
Figure 12 is an Eddyscope scan indicating the different readings obtained
from a volume of composition containing various loadings of coated
microparticles.
-4-


CA 02245620 1998-08-OS
WO 97/33162 PCTlUS96l12197
Description of the Preferred Embodiments
Materials
" The preferred microparticles have a non-ferromagnetic or non-
ferrimagnetic core and a coating that is ferromagnetic, ferrimagnetic, or
electrically
conductive. Generally, the microparticles can have a variety of shapes,
including
substantially spherical, elongated, or flat shapes. The shape may be selected
to impart
desired flow properties to the corresponding admixture given a selected
concentration
of microparticles in the admixture.
The dimensions of the microparticles can vary, but preferred microparticles
have a major dimension smaller than I centimeter and more preferably from 10
micrometers to 1 millimeter. The coating preferably will have an average
thickness
between about i nanometer and 5 micrometers, and more preferably between about
i
and 200 nanometers. The coating can, but need not, cover the entire surface of
the
non-metal core. For example, the coating can form islands on the surface of
the core,
1 S pr the rnatin~omatP_rial_ c_~,a~-n_ c_-.nve_r SuhBtatltially~?.I~ Qf
the~llrfa~e~Furthermore, t~le
microparticles can have multiple coatings, partial coatings, or combinations
thereof
having different metals.
Suitable cores include materials typically used as reinforcing agents,
rheology modifiers, or other additives in polymeric and pre-polymeric
compositions.
Examples include glass bubbles, glass beads, glass fibers, fumed silica
particles, fused
silica particles, mica flakes, polymeric particles, and combinations thereof.
Preferred
cores include hollow structures (e.g., in the form of bubbles) to minimize the
overall
amount of material added to the pre-polymeric or polymeric composition.
Preferred
core materials are glass microbubbles, e.g., commercially available from 3M
Company,
Saint Paul, Minnesota under the trade name Scotchlite'''3. Preferred core
materials
include materials that are already within the compositions of interest so that
the coated
microparticles can be substituted for the uncoated microparticles in the
composition.
In this way, the composition can be tagged without requiring reformulation of
the
composition to obtain the desired rheological properties.
-5-


CA 02245620 1998-08-OS
WO 97/33162 PCT/US96/I2197
The coating for the microparticles generally can be any ferromagnetic,
ferrimagnetic, or electrically conductive material that can be coated onto the
surface of
the microparticle core. A preferred coating should be chemically inert in the
relevant
compositions under the relevant conditions and stable with respect to
degradation and
leaching. Suitable ferromagnetic materials include iron, nickel, cobalt,
alloys including
one or more of these metals, and oxides including one or more of these metals.
Appropriate electrically conductive materials include coatable metals, metal
alloys and
metal compounds, such as carbides, oxides, nitrides and silicides. Preferred
conductive
metals for use in coatings include copper, aluminum, and silver. The preferred
material
for the coating is stainless steel, which is both electrically conductive and
ferromagnetic. if the coating material is ferromagnetic or ferrimagnetic, the
core can
be an electrically conductive, non-ferromagnetic, non-ferrimagnetic material,
in which
case the measurements will rely on the ferromagnetic or ferrimagnetic
properties of the
coating.
A variety of techniques can be used to apply the coating to the core. These
techniques include sputtering, vapor deposition, electroless plating, and
chemical vapor
deposition.
The microparticles are added to a polymeric or pre-polymeric composition
to form an admixture that is a tagged composition. The admixture will
preferably
include between about 0.01 and 50 percent by volume of the micropartieles, and
more
preferably between about 0.1 and 30 percent by volume of the microparticles.
A wide variety of pre-polymeric and polymeric compositions can be used in
conjunction with the microparticles. Preferred polymeric adhesive compositions
include crosslinked systems such as epoxies (including base-cured epoxies,
acid cured
epoxies, and addition cured epoxies}, polyurethanes, silicone resins, acrylate
polymers,
polysiloxanes, and phenolics, as well as blends of these types of systems. Hot
melt
adhesives include various polyolefins, polyesters, polyamides, polycarbonates,
polyvinylacetates, higher molecular weight waxes, and related copolymers and
blends.
Additionally, applicable adhesive compositions would be those which are formed
into


CA 02245620 1998-08-OS
WO 97/33162 PCTJLTS96/12197
films and tapes. Other useful polymeric compositions include sealants,
piastisols,
structural polymers used in gap filling and forming materials, coatings,
fibers, gaskets,
washers and laminates of various kinds. This invention is applicable to
polymer
compositions which are shaped by extrusion, molding, caiendering, casting, and
other
processes into three-dimensional forms.
One suitable class includes adhesive compositions such as structural
adhesives which include epoxy resins (e.g., derived from diglycidyl ethers of
Bisphenol
A or novolak resins). Structural adhesives are used in a variety of
manufacturing
situations including significant use in the automotive industry to bond parts
together to
reduce the need for welding. These materials, which are well-known, are
typically
prepared by reacting two or more pre-polymeric reagents with each other to
form an
intermediate "B-stage" resin, which is subsequently further cured to form the
final
product.
The pre-polymeric and polymeric compositions may contain various
adjuvants designed to enhance the properties of the resin before or after
curing,
including reactive and nonreactive diluents, plasticizers, toughening agents,
and
coupling agents. Other materials which can be added to the composition include
thixotropic agents to provide flow control {e.g., fumed silica), pigments,
fillers {e.g.,
talc, silica, magnesium, calcium sulfate, beryllium aluminum silicate), clays,
glass and
ceramic particles (e.g., beads, bubbles, and fibers), and reinforcing
materials (e.g.,
organic and inorganic fbers).
The above-described microparticles can be used in a variety of
measurement protocols. Measuring the electromagnetic properties of the
microparticles provides a measure of the number of microparticles. The
microparticles
can be present in a known concentration within the composition to be measured
to
provide the quantity determination of the composition. Similarly, the
microparticles
can be used in a fixed concentration, where the quantity of the composition
-7-


CA 02245620 1998-08-OS
WO 97/33162 PCT/US96/12197
incorporating the microparticIes is determined from a standard curve produced
using
material with the same fixed concentration.
If the microparticie-containing composition being measured is moving, the
measurement will provide information on the flow and, correspondingly, the
rate of
deposition. If the composition is fixed relative to a substrate or container,
the
measurements can provide information on the distribution of the composition
throughout the substrate or container.
One particularly useful application is in the context of dispensing polymeric
or pre-polymeric compositions such as adhesives and pre-adhesive compositions.
The
IO material being dispensed can be a single polymeric or pre-polymeric
composition that
may or may not be later polymerized or crosslinked. This single composition
would be
used to form the admixture including the microparticles.
Alternatively, the material being dispensed can include two or more
polymeric or pre-polymeric compositions that are mixed to form a curable
resin, e.g.,
I S an intermediate "B-stage" resin. One or more of the components within the
curable
resin can be combined with a given volume fraction of microparticles. The
electromagnetic properties of the microparticies can then be monitored to
measure the
amount of the reactants) dispensed into the reaction mixture. If one of two
components is provided with microparticles, the coated microparticles in the
reaction
20 mixture can be measured to determine the quantity of reaction mixture.
Based on the
quantity measurements of the component and the reaction mixture, it can be
determined if the two components were mixed in the proper ratio.
Alternatively, each component can be mixed with the same or different
microparticles. Then, each component can be measured, with or without an
additional
25 measurement of the curable resin mixture, to determine whether the
components have
been mixed together in the correct ratio. Any variation from the desired
amount can
be noted and/or used to adjust the amount being dispensed. If microparticies
with
different electromagnetic characteristics, e.g., one ferromagnetic and the
other non-
ferromagnetic, are placed in the two different components, measurements on the
two
_g_


CA 02245620 1998-08-OS
WO 97/33162 PCT/LTS96112197
components being dispensed can determine if the correct component is being
dispensed
from the particular dispenser.
Another application involves use of the microparticles in the non-
destructive testing of articles incorporating a polymeric or pre-polymeric
composition.
The measurements can be used to determine a variety of properties of the
composition
within the article, including thickness, integrity, orientation, and
continuity. Similarly,
a map can be obtained indicating the location of the composition. For example,
in the
case of structural adhesives forming a bond line to join two parts together,
the
properties of the bond line can be examined.
IO Either the electrical or the magnetic properties of the microparticles can
be
used to make the measurement. For example, in the case of ferromagnetic or
ferrimagnetic microparticIes, magnetic permeability can be measured. Magnetic
permeability is a function of the number of ferromagnetic microparticles and
the
amount of metal coating on the microparticles. It can be measured using an
a.c.
IS magnetic hysteresis Looper, e.g., a Gerard Electronic MH looperT''''
operating at a
frequency of IO kHz and an applied field strength of I O gauss. Typically, the
magnetic
field is applied with a frequency between 1 and 10 kHz.
Alternatively, inductive reactance can be measured using an eddy current
instrument (e.g., a Nortec l9ea Eddyscope ~, an impedance plane eddy current
20 instrument, equipped with a Nortec OD/100IcHzlAl0.682" probe) to measure
the
quantity of microparticies (and thus the quantity of pre-polymeric or
polymeric
composition) within a given volume. With proper calibration the vertical
response of
the eddyscope is proportional to the inductive reactance; this response is
hereinafter
referred to as the inductive reactance. The inductive reactance, i.e., the
eddyscope
25 response, is approximately proportional to the Loading of the
microparticles and
coating thickness on the individual microparticles.
Another way of performing the measurement is by measuring the dielectric
properties of the microparticles. Electrically conductive coatings on the
microparticles
increase the dielectric constant, which is related to microparticle loading.
This can be
_g_


CA 02245620 1998-08-OS
WO 97/33162 PCT/US96/12197
determined, for example, by measuring the capacitance of a parallel plate
capacitor
containing the microparticies. An advantage of the dielectric measurement
approach
over the magnetic permeability approach in certain applications is that the
magnetic
response is related to the amount of magnetic material coated onto the
microparticIes,
while the dielectric constant is approximately independent of coating
thickness.
Therefore, much thinner electrically conductive coatings can be used when the
dielectric measurements are used.
Other aspects of the electromagnetic properties can be exploited to perform
the measurements. For example, certain metals can scatter x-rays sufficiently,
so x-ray
I O transmission measurements can be used to quantify the amount of metal-
coated
microparticIes present within a material. Alternatively, coatings can be
selected to
minimize interference with x-ray transmission so that articles can be examined
with x-
rays with minimal interference by the coated microparticles.
In addition, microwave or inductive heating methods can be used to heat
the microparticles, after which the associated infrared emissions can be
measured to
quantify the amount of microparticles (and thus the amount of polymeric or pre-

polymeric composition).
The invention will now be described by way of the following examples.
EXAMPLES
Examgle 1
This example demonstrates that glass bubbles can be coated with a very
thin magnetic stainless steel coating.
K37 Scotchlite~ glass bubbles (sold by 3M, Saint Paui, Minnesota) were
sputter coated with 304 stainless steel according to the procedure described
generally
in U.S. Patent No. 4,6/8,525. In this specific case, a 304 stainless steel
target was do
magnetron sputtered for 7.0 hours at 8.0 KW at an argon sputtering gas
pressure of 5
millitorr onto 415 grams ofK37 Scotchlite glass bubbles. The 304 stainless
steel
sputter target was non-magnetic austenitic face centered cubic, but deposits
as the
- 10-


CA 02245620 1998-08-OS
WO 97/33162 PCT/CTS96/12197
magnetic ferritic body centered cubic form. These materials have been
described in a
publication by T.W. Barbee, B.E. Jacobson and D.L. Keith, 63 Thin Solid Films
143
' i 50 ( 1979}.
The resulting stainless steel coated bubbles had an iron content of 7.86% by
weight (determined by inductively coupled plasma emission spectroscopy},
corresponding to 11.2% by weight stainless steel (which is 70% by weight
iron). The
surface area of the glass bubbles was determined by the B.E.T. method to be
0.55
square meters per gram. The density of the coated bubbles was measured using a
Beckman Model 930 air comparison pycnometer. The density of the uncoated
bubbles
was 0.36 g/cc, and that of the coated bubbles was 0.4 i g/cc.
The metal coating thickness can be calculated from the relevant relationship
described in U.S. Patent No. 5,409,968. In this case, the coating thickness
was
determined to be 29 nm.
Example 2
This example demonstrates the effect of volume loading of stainless steel
coated bubbles on inductive reactance.
Glass bubbles with a 29 nm thick stainless steel coating were used.
Devcon~ 5-minute epoxy {ITW Devcon, Danvers, Massachusetts) was used to
prepare samples with various volume loadings of coated bubbles. This mixture
was
placed in 80 mm long Pyrex glass tubes with 13.2 mm inner diameter and a 16.0
mm
outer diameter.
The inductive reactance was then measured using a Nortec Eddyscope.
Several variables can be optimized on the Eddyscope. For a given probe, these
are (1)
frequency, (2) gain, and (3) probe drive voltage. The rotation (','Rot" knob
on the
instrument) was used to calibrate the Eddyscope so that displacement along the
y-axis
provided a measure of inductive reactance. Inductive reactance in unscaled
units was
read from the Eddyscope display. Barium ferrite, which is magnetic but not
significantly electrically conductive, was chosen as a calibrating material.
With a
-lI-


CA 02245620 1998-08-OS
WO 97/33162 PCT/1JS96/12197
frequency fxed at I00 kHz, rotation was varied until introduction of the
barium fernte
sample resulted in a purely vertical response on the Eddyscape screen
(rotation = 311
degrees).
The Eddyscope settings included a gain of 76.0 dB with probe drive of
"Mid." Reactance versus microparticle loading is plotted in Figure I . This
illustrates
the linear relationship between the two variables. It shows that the reactance
can be
used as a good measure of the bubble content.
Example 3
This example demonstrates the effect of coating thickness on inductive
reactance.
Procedures similar to that in Example I were carried out to make stainless
steel coated glass bubbles with coating thicknesses of 59 and 86 manometers.
The
density for each of the coated bubble samples was 0.44 and 0.49 g/cc,
respectively. In
addition, glass bubbles with a 29 nm thick stainless steel coating prepared as
in
Example 1 were used.
The Eddyscope parameters were set as in Example 2 except that the gain
was 70.0 dB. Test samples in Devcon 5-minute epoxy were prepared at 10% volume
loading for each of the three samples of coated bubbles. The inductive
reactance was
measured and is plotted as a function of the stainless steel coating thickness
in Figure
2. The inductive reactance increases monotonically with stainless steel
thickness.
Example 4
In this example, the use of acicular particles is demonstrated.
Milled glass fibers (Type 731 DD 1/16 inch milled glass fibers) were
obtained from Owens/Corning Corporation (Anderson, South Carolina). They had
an
aspect ratio range of approximately 1 to 40, with a fiber diameter of I 5.8
microns.
Stainless steel was deposited onto 1570 grams of these fibers for 20 hours at
8.0 kW in
the manner previously described in Example i. '
- 12-


CA 02245620 1998-08-OS
WO 97/33162 PCT/LTS96/12197
The weight percent iron was determined to be 6.2%, corresponding to
8.9% by weight stainless steel. The surface area of the uncoated fibers was
0.10
' square meters per gram.
The stainless steel coated milled glass fibers were dispersed in Devcon 5-
minute epoxy at a volume loading of 10%. The mixture was placed in glass
tubes, as
described in Example 2. The Eddyscope was set to a gain of 68.0 dB with Probe
Drive on High. The inductive reactance was determined to be 8.9.
Example 5
In this example, the use of a magnetic cobalt coating is demonstrated.
Milled glass fibers were sputter coated with cobalt, as described in Example
1, using a MAK 3 inch Magnetron Sputtering Source (US Thin Film Products Inc,
Campbell, California). The weight percent cobalt was determined to be 5.6%,
corresponding to a coating thickness on the fibers of 67 nm.
The cobalt coated milled glass fibers were dispersed at 10% by volume in
Devcon 5 minute epoxy and loaded into a glass tube as described in Example 4.
The
Eddyscope was set to the same conditions as Example 4 except that the gain was
raised to a value of 80.0 dB. The inductive reactance was determined to be
9.6.
Example 6
In this example, flat, flake shaped particles were used. Silicone rubber,
rather than epoxy, was the polymer component. Stainless steel was deposited
onto
460 grams of 200HK Suzorite~ mica flakes (Suzorite Mica, Inc., Hunt Valley,
Maryland) for 13.5 hours at a power of 8.0 kW in the manner described in
Example 1.
The stainless steel-coated mica flakes were dispersed at a volume loading of
10% into RTV 615, a silicone rubber available from Dow Corning Corporation.
This was loaded into a glass tube as described in Example 3. The Eddyscope was
set
to the same conditions as Example 4 except that the gain was set to a value of
60Ø
' The inductive reactance was determined to be 8.4.
-13-


CA 02245620 1998-08-OS
WO 97/33162 PCT/US96/12197
Example 7
This example illustrates the relationship between the measured magnetic
permeability and the stainless steel coating thickness on the glass bubbles.
The three stainless steel-coated bubble samples described in Example 3
were combined with Devcon 5 minute epoxy at a volume loading of 10%. The
material was used to fill tubes (straws) with a 5 mm internal diameter to a
depth of 70
mm. The permeability was determined from a hysteresis loop obtained using a
Gerard
Electronic MH looper operating at a frequency of 10 kHz and an applied field
strength
of 10 gauss. The permeability was calculated from the maximum applied field in
gauss
and the maximum magnetization in emuJcc. A BH looper could also be used.
The permeability is plotted versus stainless steel coating thickness in Figure
3. Permeability is seen to monotonically increase with coating thickness. This
demonstrates that these very thin magnetic coatings can provide significant
and
reproducible permeabilities. The higher coating thicknesses give higher
permeabilities.
Example 8
This example demonstrates that the inductive reactance for coated particles
is directly related to their magnetic permeability. Magnetic permeability is a
fundamental magnetic property of the coated microparticles incorporated into
an
adhesive. Magnetic permeability is related to the Eddyscope response, which is
the
inductive reactance. To demonstrate this relationship, the magnetic
permeability
measurements ofExampIe 7 are plotted in Figure 4 against the inductive
reactance
measurements ofExample 3 using the same coating thicknesses of stainless steel
on
glass bubbles. The inductive reactance is monotonic, and almost proportional
to the
permeability.
-14-


CA 02245620 1998-08-OS
WO 97!33162 PCT1US96112197
Example 9
This example demonstrates the use of the magnetic coated microparticles
within an adhesive for non-destructive testing. This could be used as a form
of non-
destructive testing to determine the continuity of the adhesive bondline.
Devcon 5 minute epoxy was used to make an adhesive having a 26%
volume loading of glass bubbles with a 29 nm thick stainless steel coating
prepared as
in Example 1. About 1% by volume of 60-100 micron diameter glass beads were
added as spacers. A bead of this material was Laid onto a strip of aluminum
measuring
0.61 mm thick, 19 mm wide, and 31 cm long. In the middle, the adhesive was
removed from a span of about 3 cm. An identical piece of aluminum was pressed
onto
the adhesive on the first piece to make an aluminum-epoxy-aluminum sandwich
structure. Adhesive which exuded from both edges of the structure was removed
after
the adhesive had cured.
A Nortec SPO-5781TT~ I kHz-50 kHz edge probe was used to scan the
I5 structure. The Eddyscope was set at 5 kHz with 0 degrees rotation and probe
drive
H't. The scan is presented as a screen print in Figure 5. The gap in the
adhesive
between the two aluminum pieces is clearly shown.
Example 10
This example demonstrates the use of a simple solenoid coil in place of an
eddy current instrument, such as an Eddyscope, to determine loading of coated
microbubbles.
A solenoid coil was prepared by winding size 36 (0.127 mm diameter)
insulated copper wire onto a 19.0 mm o.d. glass tube. The coil had 333 turns
in four
layers over a length of 3.0 cm. The two leads from the coil were connected to
a
Tenmark 72-370 digital LCR meter. An LCR meter is a hand-held device capable
of
' measuring inductance, capacitance, or resistance when attached to an
appropriate
sensing device. 80 mm long, 16.0 mm outer diameter glass tubes containing
Devcon
epoxy with various loadings of glass bubbles provided with 29 nm-thick
stainless steel
-15-


CA 02245620 1998-08-OS
WO 97/33162 PCT/US96/12197
coatings were inserted into a tube (centered in the coil region), which had a
16.5 mm
inner diameter.
The inductance was read off the LCR meter and is plotted versus volume
loading in Figure 6. The approximate linear relationship between inductance
and
loading demonstrates the fundamental relationship between the two. This also
shows '
that equipment other than an eddy current instrument can be used in sensing
loadings
in the adhesives containing the microparticles.
Example 11
This example demonstrates that capacitive, rather than inductive,
measurements can be used to determine microparticie loading in adhesives.
A two-plate capacitor was made for detecting the capacitance of an
adhesive material. Two pieces of adhesive-backed copper foil were cut to form
rectangles 2.0 cm wide x 3.0 cm long. These were axed to the outside of a
glass
tube of the same dimensions as the larger glass tube in Example I 0. They were
affixed
opposing one another so as to form a curved-plate rather than parallel-plate
capacitor.
Electrical leads from each plate were connected to the same LCR meter
described in
Example 10. This sensing apparatus was loaded with various samples of
adhesives
containing coated microparticles as described in Exampie 10.
The capacitance was read off the LCR meter and is plotted versus loading
of the coated microparticles in the adhesive in Figure 7. The approximate
linear
relationship between the two demonstrates that measurement of capacitance
provides
another means of determining concentration.
Example 13
This example demonstrates the ability of an object made with a material
incorporating microparticles to be mapped using an Eddyscope. It also
demonstrates w
the use of a thermoplastic, rather than thermoset, resin.
- 16-


CA 02245620 1998-08-OS
WO 97/33162 PCTlLTS96/12I97
A rectangular plastic tray was obtained from 3M Company, St. Paul, MN.
It is identified as Thin PQFPT"'t 132 21002-203. It is 32.3 cm wide by 0.8~ cm
thick.
° It contains 24% by volume stainless steel-coated milled glass fibers
dispersed in Mindel
SI000, a thermoplastic resin obtained from Amoco Chemical Company, Chicago,
iL.
A Nortec S-300 Hz-lOkHz/.62 surface probe was oriented vertically 1 mm above
the surface of the tray in such a manner as to allow the tray to be scanned
under it.
The Eddyscope was set with a frequency of 1.0 kHz, a gain of 90 dB, a probe
drive
"Hi," and rotation 18 degrees. The tray was manually scanned under the probe
with
inductive reactance versus time being recorded.
The scan (Figure 8) shows a map of the presence of high spots and voids in
the tray. A physical map of the tray from the top side is also given here for
comparison in Figure 9. The scan was made in a straight line from one end of
the tray
to the other on the second row from the top, as indicated by the horizontal
arrow.
Example 13
This example demonstrates the ability of a material incorporating
microparticles to be mapped using capacitance, rather than an Eddyscope.
A parallel-plate capacitor was set up for the purpose of scanning the tray of
Example 12. The top electrode was a rectangle measuring 1.4 cm by I .0 cm and
the
bottom electrode measured 15 cm by I S cm. The spacing between the electrodes
was
0.8 cm. The capacitance was measured using the meter described in Example 10.
The tray was moved through the sensing capacitor, with the capacitance
recorded at 0.5 cm increments. The capacitance map is shown in Figure 10 along
with
a schematic cross section of the tray. The voids, peaks, and valleys on the
surface of
the tray are clearly indicated in this scan {within the resolution of the top
electrode).
- Example 14
This example demonstrates how an off ratio mixing event can be detected
when the adhesive contains coated glass bubbles. The following two component
- 17-


CA 02245620 1998-08-OS
WO 97/33162 PCT/US96/12I97
adhesive formulation was prepared using glass bubbles with a 29 nm stainless
steel
coating:
-18-


CA 02245620 1998-08-OS
WO 97/33162 PCT/US96/12197
O~ M M O Ov Q~ ~ O vp 00 ~ ~ G1 C~
>I~~N~~~Ni
~ h
U


U



~ ~


t~ O~ ' O ~ ~ 00 N
O 00 ~ N rt ~ ~ O O O --~N


v m- m..-'N N C d



H


N I~ ~' G~V ~ ~D 00 ~ M ~
Oa1..0000 N M 0 ~ 11. O~O


N v


C' Ts
~ cQ U CJ
.~N~ 04 G . .O'
4 0 c N U
'O :-.N ~n '~ ~ ~
'o O Q vo in
00 ~. ~ ~ ~n o ~~ '-
~ E w-~~ R :a ~ ~ ,~
?, N ~ E t~C cC 0 .--
N p~~"~ ~ ~' ~ ~ E~ (/~0..
O Er E" C O
x O C7 N Gs.. x Q E-
~ C~
I-'


-19-


CA 02245620 1998-08-OS
WO 97/33162 PCT/US96/12197
Epon 828TT~ is a diglycidyl ether of bisphenol A available from Shell
Chemical Company. Heloxy I 07 is a diglycidyl ether of cyclohexane available
from
Shell Chemical Company. TS-720 is a hydrophobic fumed silica available from
Cabot Corporation. The glass beads have a nominal diameter of 0.01 inches,
available from Cataphote, Inc. GP-71~ is an amorphous silicon dioxide
available
from Harbison-Walker Corporation. The glass bubbles are hollow glass
microspheres available from 3M Corporation. The polyamidoamine is an amine-
terminated polyamide. H221 is 4,7,10-trioxatridecane 1, 3-diamine available
from
BASF. Ancamine K54 is 2, 4, 6-trimethyaminomethyl phenol available from Air
Products Chemical, Inc. ATBN 1300x16 is acrylonitrile-terminated butadiene
liquid rubber available from B. F. Goodrich Company.
The proper mix ratio of this adhesive by weight is 146.7/87 or 1.69 B:A,
obtained by dividing the formula weight of Part B by the formula weight of
Part A.
(By volume, by a similar procedure, the volume mix ratio is I 5 I .05/75.54 or
2.0
B:A). By increasing or decreasing 1.69 by 10%, it can be determined that a B:A
mix ratio of 1.86:1.00 represents a plus 10% off ratio while I .52:1.00
represents a
minus 10% off ratio.
Mixtures of the above Part B and Part A were prepared at B:A by
weight mix ratios of 1.52:1.00, 1.69:1.00, and I .86:1.00; degassed while
being
mixed; and pulled by vacuum into three separate half inch static mixing
nozzles.
After being filled, the nozzles were inserted into the eddy current probe as
described
in Example 2.
The response of the Eddyscope was somewhat more consistent when the
mixing elements were removed from the static mix nozzles because filling of
the
nozzles is more uniform without the mixing elements. In a dynamic situation
where
many gallons of mixing adhesive are pumping through a given nozzle, a steady-
state
response could be achieved.
To simulate this dynamic response, the nozzle is moved back and forth '
in the probe. As Figure 11 demonstrates, the Eddyscope responses corresponding
to adhesives mixed under the proper (control) mix ratio, -10% off ratio, and
+10%
off ratio are readily differentiated from each other. The measured responses
can
-20-

CA 02245620 1998-08-OS
WO 97/33162 PCT/LTS96/12197
provide a process window within which mix ratio can be established and
maintained
using an adhesive containing coated glass bubbles.
Example 15
This example demonstrates the substitutiion of varying amounts of
coated glass bubbles for already present plain glass bubbles.
A two component adhesive (16-1) was made using uncoated glass
bubbles, and corresponding versions were made (16-2 through 16-6) by
substituting
for some or all of the plain glass bubbles in the B adhesive component with
stainless
steel coated glass bubbles having a 29 nm stainless steel coating. The B
adhesive
component contained a 0.35 volume fraction of glass bubbles.
-21 -

CA 02245620 1998-08-OS
WO 97/33162 PCTlUS96/12197
Parts by Weisht !e) in B Component
16-11 16-2 I6-3 I6-4 16-S 1~-6
Epon 828 DGEBA 80 80 80 80 80 80
Heloxy 107 epoxy diluent 20 20 20 20 20 20
TS-720 fumed silica 2 2 2 Z 2 2
0.25-mm glass beads 3 3 3 3 3 3
GP-71 fused silica 20 20 20 20 20 20
K37 glass bubbles 19.6 19.4 18.6 17.6 9.8 0
SS-coated bubbles
(29 nm coating) 0 0.2 1.I 2.2 10.9 21.7
Total formula weight (g) 144.6 144.6 144.7 144.8 145.7 146.7
B:A by Weight 1.66:1 L66:1 1.66:1 1.66: I 1.67:1 1.69: i
B:A by Volume 2:1 2: i 2:1 2:1 2:1 2:1
Total Volume Fraction
Bubbles on B Side 0.35 0.35 0.35 0.35 0.35 0.35
Volume Fraction of Coated
Bubbles 0.0 0.0035 O.OI75 0.035 0.175 0.35
Substitution Level Based
on Total Bubble
Volume
(percent) 0 I S 10 SO 100
Part A is as given below and is used in the given mix ratio with each of
the above Part Bs to form a 2:1 mixture by volume. The nature of the
ingredients
of the A and B compositions are described further in Example 14.
Pa-Pa-rt AA
Polyanudoame 40
H221 amine 6
Ancamine K54 Tertiary Amino 8
ATBN 1300x16 Liquid Rubber 10
TS-720 Fumed Silica 3
GP-7I Fused Silica 20
Total 87
The volume fraction of total glass bubbles was kept as close as possible r
to a constant value for ail B components using calculations involving the 0.37
g/cc
density of the uncoated glass bubbles and the 0.41 g/cc density of the
stainless steel
coated glass bubbles. The parts of all bubble components were rounded to the
nearest 0.1 g.
-22-


CA 02245620 1998-08-OS
WO 97/33162 PCT/US96/12197
Using the listed mix ratios and a multiplication factor of 30, samples of
the B components 16-1 through 16-6 were mixed under vacuum with the
appropriate amount of the A component and deposited into flat-bottomed plastic
weighing dishes. The component mixtures were allowed to cure at room
temperature into a solid mass about 2.5 inches in diameter and at least 0.5
inches
thick. After cure, the dish was peeled off of each hardened adhesive to
present a
flat surface which was interrogated using a fiat surface probe, Nortec
#954769,
S/lkHz-50kHz/0.31. The Eddyscope was set at a frequency of 50 kHz, a gain of
67.0, and a rotation of 64 degrees.
Nulling in air and setting the surface probe against the flat bottoms of
each of the molded samples containing coated glass bubbles in turn produced
the
results shown in Figure I2. {The signal for the 16-2 material is weak due to
the
desire to fit data for all samples on the same screen/chart but could be
increased by
setting gain higher than 67Ø} The data clearly shows the systematic fashion
in
which the signal increases with increasing substitution of coated bubbles for
uilcoated bubbiej wit h, iir cxaWpie, the ~~g:.al ~r 1-~°:.
~'~..'~'~taSa:L'3':-being
approximately twice that for 5%, the signal for 50% being approximately five
times
that for 10%, and so on. The sample made using 16-I mixed with Part A gave no
measurable Eddyscope response.
Esc uivalents
Various modifications and alterations to this invention wilt become
apparent to those skilled in the art without departing from the scope and
spirit of
this invention. It should be understood that this invention is not intended to
be
unduly limited by the illustrative embodiments and examples set forth herein
and
that such examples and embodiments are presented by way of example only with
the
scope of the invention intended to be limited only by the claims set forth
herein as
° follows.
- 23 -

Representative Drawing
A single figure which represents the drawing illustrating the invention.
Administrative Status

For a clearer understanding of the status of the application/patent presented on this page, the site Disclaimer , as well as the definitions for Patent , Administrative Status , Maintenance Fee  and Payment History  should be consulted.

Administrative Status

Title Date
Forecasted Issue Date 2007-02-06
(86) PCT Filing Date 1996-07-24
(87) PCT Publication Date 1997-09-12
(85) National Entry 1998-08-05
Examination Requested 2003-07-22
(45) Issued 2007-02-06
Deemed Expired 2010-07-26

Abandonment History

There is no abandonment history.

Payment History

Fee Type Anniversary Year Due Date Amount Paid Paid Date
Registration of a document - section 124 $100.00 1998-08-05
Application Fee $300.00 1998-08-05
Maintenance Fee - Application - New Act 2 1998-07-24 $100.00 1998-08-05
Maintenance Fee - Application - New Act 3 1999-07-26 $100.00 1999-07-05
Maintenance Fee - Application - New Act 4 2000-07-24 $100.00 2000-07-05
Maintenance Fee - Application - New Act 5 2001-07-24 $150.00 2001-07-05
Maintenance Fee - Application - New Act 6 2002-07-24 $150.00 2002-07-10
Maintenance Fee - Application - New Act 7 2003-07-24 $150.00 2003-07-08
Request for Examination $400.00 2003-07-22
Maintenance Fee - Application - New Act 8 2004-07-26 $200.00 2004-07-05
Maintenance Fee - Application - New Act 9 2005-07-25 $200.00 2005-07-05
Maintenance Fee - Application - New Act 10 2006-07-24 $250.00 2006-07-04
Final Fee $300.00 2006-11-22
Maintenance Fee - Patent - New Act 11 2007-07-24 $250.00 2007-07-03
Maintenance Fee - Patent - New Act 12 2008-07-24 $250.00 2008-06-30
Owners on Record

Note: Records showing the ownership history in alphabetical order.

Current Owners on Record
MINNESOTA MINING AND MANUFACTURING COMPANY
Past Owners on Record
CHAMBERLAIN, CRAIG S.
YORKGITIS, ELAINE M.
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.
Documents

To view selected files, please enter reCAPTCHA code :



To view images, click a link in the Document Description column. To download the documents, select one or more checkboxes in the first column and then click the "Download Selected in PDF format (Zip Archive)" or the "Download Selected as Single PDF" button.

List of published and non-published patent-specific documents on the CPD .

If you have any difficulty accessing content, you can call the Client Service Centre at 1-866-997-1936 or send them an e-mail at CIPO Client Service Centre.


Document
Description 
Date
(yyyy-mm-dd) 
Number of pages   Size of Image (KB) 
Cover Page 1998-10-29 1 47
Abstract 1998-08-05 1 54
Description 1998-08-05 23 949
Claims 1998-08-05 2 60
Drawings 1998-08-05 7 93
Representative Drawing 2007-01-30 1 6
Cover Page 2007-01-31 1 42
PCT 1998-08-05 9 331
Assignment 1998-08-05 4 230
Prosecution-Amendment 2003-07-22 1 49
Correspondence 2006-11-22 1 39