Note: Descriptions are shown in the official language in which they were submitted.
CA 02524814 1996-08-08
ARCHIVAL PRESERVATION COATINGS AND ADHESIVES
Statement of Related Applications
The technology involved in this application is related
to that disclosed in the U.S. Patents No. 5,633,054 issued
on May 27, 1997, No. 5,693,384 issued on December 2, 1997,
and No. 5,525,296 issued on June 11, 1996.
Field of the Invention
This invention relates to archival preservation
coatings and adhesives. More specifically, this invention
relates to methods of preventing the physical degradation of
an archival article from exposure to environmental
impurities by using such coatings and adhesives.
Background of the Invention
Archival articles are generally defined as objects of
historical, aesthetic or sentimental significance, such as
papers and photographs. Several attempts have been made to
protect archival articles from the deleterious effects of
impurities in the environment_
For example, previous attempts have been made to
protect archival articles by storing them in containers
designed to protect the archival articles from the
deleterious effects of both impurities outside of the
container and from residual chemicals within the container
material. Cardboard containers have been coated with an
acid in order to protect the contents
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of the container from alkaline fumes emitted from the adhesive
used in container construction or sealing. Other containers
have an inner layer incorporating an organic amide and an
inorganic metal nitrate which inhibits metal corrosion.
Additionally, packages have been designed for photographic
film in which a container or wrapping is substantially free from
sulfur, ammon~'_a, and turpentine. Such a package may also have a
black, opaque outer layer and an inner layer which is inert
towards light-sensitive, photographic emulsions.
Boxboards are also known which include a first layer of
paperboard consisting of non-buffered, substantially pure .
alpha-cellulose and alkaline size, a second layer of a
paperboard comprising alpha-cellulose, an alkaline buffer and an
alkaline size and, between the first and second layers, a laye_
of water-impermeable elastic. The alkaline components may
neutrali2e the acidic impurities in the environment of the
archival article. The inner layer of the boxboard may be
nonbuffered in order to avoid damage to the contents stored
within the containers made from the boxboard. ,
However, the previous methods have not been sufficient to
protect archival articles from all of the impurities in the
environment of the archival articles. A wide variety of
eomnounds are known to damage archival articles. For example,
aixborne pollutants from the surrounding atmosphere and the
various by-products of deteriorating archival articles may
contact and damage an archival article. For example, oxides of
nitrogen may combine with moisture to.form pollutants, such as
nitric acid, which may contact and damage artifacts, such as
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photographs. Sulfur compounds may cause silver images, ~.c. is
photographs, microfilm, and microfiche, to fade by converting
the metallic silver in the photographic layers to silver
sulfide. Acids can also contact and damage photographs by
bleaching and lading the silver image and causing the paper and
gelatin support to become brittle. Peroxides, in concentrations
as low as one part in thirty million, may also cause image
oxidation and fading.
Previous studies have also detected degradation products
from the archival articles themselves which may further damage
archival articles. The degradation products nay be.mobile and
may b~ transferred from one article to another by surface or gas
phase diffusion. Deterioration may also produce by-products
such as organic acids, low molecular weight ketones, aldehydes
and phenols.
SUMMA..RY OP THE INVENTION
~he inventor has found that by incorporating.an adsorben t
and an alkaline buffer into coating compositions or adhesive
mixtures to be applied to substrates to be placed in proximity
to archival articles, many of the problems incurred due to
limitations and disadvantages of the related art are overcone.
In certain applications, only an adsorbent is used in the
coating or adhesive compositions which may be placed in
proximity to an alkaline buffer material. Such coating
compositions or adhesive mixtures can be used, for example, to
coat or paint walls and surfaces in collection rooms or
conservation labs, to coat artifacts themselves, to coat
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surfaces of exhibit cases or display units, to coat packing or
shipping crates, and to coat shelves, drawers, and other units
or containers holding artifacts to be protected from molecules
which may damage them or hasten their deterioration.
Similarly, adhesive compositions containing an adsorbent and
alkaline buffer as described above can be used, for example, to
secure two or more. substrates together, such as in a multi-
layered container wall.
The invention is directed to a method for preventing the
physical degradation of an archival article due to exposure to
environmental impurities. The method, which effectively removes
both acids and other impurities or by-products having various
molecular sizes from the environment of an archival article,
includes the steps of applying to a substrate a coating
composition comprising (i) an alkaline buffer capable of
neutralizing acidic components from the environment of the
archival article; and (ii) an adsorbent capable of removing
chemical components from the environment of the archival
article; drying the composition on the substrate.to form a.
coated material; and preventing the physical degradation of the
archival article by positioning said coated material in
proximity to the archival article. The coating composition may
also be in the form of a powder to be sprayed or dusted onto a
surface; in this embodiment, there is no drying step.
The invention is also directed to a method for preventing
the physical degradation of an archival article using an
adhesive composition. This method comprises applying to a
substrate ar. adhesive composition containing (i) an alkaline
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buffer capable of neutralizing acidic components from the
environment of the archival article; and (ii) an adsorbent
capable of removing chemical components from the environment of
the archival article; adhering another substrate to the adhesive
composition; drying the adhesive composition between the
substrates; and preventing the physical degradation of the
archival article by positioning the adhered substrates in
proximity to the archival article.
The invention is further drawn to a method for preventing
the physical degradation of an archival article using both
adhesive and coating compositions. This method comprises
applying to a substrate an adhesive composition containing (i?
an alkaline buffer capable of neutralizing acidic components
from the environment of the archival article; and (ii? a,n
adsorbent capable of removing chemical components from the
environment of the archival article; adhering another substrate
to the adhesive composition; drying the adhesive composition
between the substrates; applying to the adhered substrates a
coating composition having an alkaline buffer and an adsorbent
as described above; drying the coating composit~'_on to form a
coated material; and preventing the physical degradation of the
archival article by positioning said coated material in
proximity.to the archival article.
Yet another embodiment of the present invention is directed
to a method for preventing the physical degradation of an
archival article comprising the steps of: applying to a
substrate a coating composition comprising an adsorbent capable
of removing chemical components from the environment of the
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archival article; drying the composition on the substrate to
form a coated material; bringing the coated material in
proximity to an alkaline buffer material as described above; and
preventing the physical degradation of the archival article by
positioning the coated material and the alkaline buffer material
in proximity to the archival article.
Still another embodiment of the present invention is drawn
to a coated substrate wherein the coating on the substrate
comprises-(i) an alkaline buffer capable of neutralizing acidic
components from the environment of the archival article; and
(ii) an adsorbent capable of removing chemical components from
the environment of the archival article.
Additional features and advantages of the invention will be
set forth in the description which follows, and in part will be
apparent from the description, or may be learned by practice of
the invention. The objectives and advantages of the invention
may be realized and obtained by means oL the materials znd
methods particularly pointed out in the written description and
claims.
DETAILED DESCRIPTION OF THE INVENTION
To achieve these and other advantages and in accordance with
the purpose of the invention as embodied znd broadly described
herein, a method for preventing the physical degradation. of an
archival article, particularly due to exposure to environmental
impurities or other deteriorating conditions is disclosed. One
method of the invention includes applying a coating composition
to a substrate, drying the composition to form a coated
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material, and positioning the coated material i~ sufficient
proximity to an archival article to prevent the article s
physical degradation. Prevention is hereby defined as
preventing or retarding, preferably significantly retarding,
physical degradation.
The coating composition of the invention can comprise an
alkaline buffer and an adsorbent, the alkaline buffer being
capable of neutralizing acidic components from the environment
of the archival article and the adsorbent being capable of
removing chemical components from the.environment of the
archival article. In certain applications, the coating
composition may comprise only an adsorbent, i.e., of the type
described above. A coating of this type may be used in
situations where the material coated with the adsorbent-
containing composition will be placed in proximity to an
alkaline bu=fer matezial as described above, e.g., alkaline
buffs=ed paper.
In other applications of the present invention, the coating
composition may be in the form of a powder to be sprayed or
dusted onto a surface. This embodiment involves no drying step.
The powder may be dusted or sprayed onto a surface or substrate
to which it adheres.
In another embodiment of the method of the present
invention, the alkaline buffer and adsorbent, or adsorbent only,
as described above are contained in an adhesive composition.
The adhesive composition is applied to a substrate and another
substrate is adhered to the adhesive composition. The
composition between the substrates is dried, preferably allowed
CA 02524814 1996-08-08
to dry on its own, and the adhered substrates are positioned in
sufficient proximity to an archival article to prevent its
physical degradation.
The application of the adhesive mixture can be repeated to
form multiple layers of substrates, if a mufti-layered material
is desired. The substrates can be identical to or different
from each other. .
In yet another embodiment of the inventive method for
preventing the physical degradation of an archival article,
particularly due to exposure to environmental impurities or
other deteriorating conditions, an adhesive composition as
described above is applied to a substrate and another substrate
is adhered to the adhesive composition. The composition between
the substrates is dried, preferably by allowing it to dry on its
own. Next, a coating composition as described above is appl?ed
to the adhered substrates. The coating composition is dried to
form a coated material, and the coated material is positionec in
sufficient proximity to the archival article to prevent its
physical degradation.
For the purposes of the invention, the term ~~archival
article" includes any article which it may be desirable to
preserve for a short or long period of time. In a preferred
aspect; an archival article includes any object of historic,
aesthetic, sentimental or scientific significance. More
preferably, an archival article is an article generally
preserved in a private collection, a museum, a library, a
historical society, an archive or an art gallery.
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For example, an archival article may be a paper, including a
document, a map, a paper currency, a stamp, a rare book, an
album page, an artist's paper, a custom paper or a mounting
board; a photographic image, including a film, a slide, a
videotape, a microfiche, a microfilm or a photograph; a metal,
including a coin, an ornament, or jewelry; a textile, including
clothing, an artists' canvas, or a furniture covering; a sound
recording, including a cassette tape, a record, or a compact
disk (CD); an electronic component; a mechanical component; a
computer _disk or diskette; a plant, animal or. mineral specimen,
including a herbarium, a fur or a bone or tissue sample; or a
fossil.
The archival preservation coating compositions and adhesive
mixtures of the invention may be applied to a substrate and
allowed to dry, leaving a surface that will neutralize acidic
components and remove chenical components fron the ~nviYonment
of any archival article the coated substrate is positioned in
sufficient proximity to. The substrate may be a packaging
material, container'or support that holds or envelops (either
completely or partially) an archival article, or the substrate
may even be the surface of an archival article itself.
The substrate may include at least one fibrous, woven or
nonwoven material,. including paper, alkaline-buffered paper;
canvas, a textile, wood, metal, glass cellulose, cotton,
plas~er, drywall, foam, plastic or combinations of these. The
substrate could also be a previously painted surface from which
the paint was not removed before applying the coating
composition of the present invention. For example, a
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combination of substrate materials may be selected based on the
desixed appearance, porosity or types of impurities to be
blocked, neutralized or absorbed.
The packaging material, preferably a paper, foam or cotton
material, may be a cushioning material, a shredded paper, a
barrier paper, a lining paper, an interleaving paper, a wrapping
paper, or an enclosure paper.
The container may be of any shape and made of any material
that is suitable to hold or envelop ieither completely or
partially) the archival article. The container may be, for
instance, a display case, a drawer, a shelf, a rare. book box, a
record or document case, a photographic storage box, a map o.
print box, a file folder, an album, a scrapbook, a plastic
enclosure, an envelope or a protective covering or fastener for
a reel of film, such as a button and string tie.
A preferred embodiment of the container is a picture frame.
The picture frame is preferably mace of wood and has as part oL
its structure a rabbet. "Rabbet" is a term of art for a groove
cut all around the inside of the back oz a f came into which fits
the article to be displayed in the frame, e.g., artwork or
memorabilia. Alternatively, the rabbet may be cut to hold a
piece of.glass or plastic behind which the article to by
displayed is placed.
In this embodiment of the presen~ly_claimed invention,
therefore, the physical degradation of an archival article being
displayed in a picture frame having a rabbet is prevented. Whey
the article to be displayed is placed in the frame behind the
glass or plastic, the coating on the rabbet keeps harmful
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contaminants from getting into the frame and damaging the
article. The method of the invention includes applying to the
rabbet and the lip or the rabbet a coating composition
comprising an alkaline buffer and an adsorbent, as described
above; drying the composition on the rabbet and lip of the
rabbet to form a coated material; and preventing the physical
degradation of the archival article by positioning said archival
article in the picture frame. The composition of the present
invention is preferably coated inside the groove, or "rabbet,"
and on the lip of the rabbet, i.e., level with the back of the
frame. If alkaline matboard or alkaline paper is used ~n the
fram~'_ng of the article to be displayed, the coating composition
may contain an adsorbent only.
The support, for example, may be a matte or mounting board,
a foam-core board, a corrugated board, a franing or backing
board, or an archival containment board. The support may also
be a .:all, such as in a conservation laboratory, a hospital or
laboratory clean room, a collection room, a photographic
darkroom or even a home ox business in an area with dangerously
high ozone levels,-for example. Indeed, in an application
envisioned for the presently claimed invention, the coating
composition applied to the walls of a room could protect the
occupants of the room (e. g., people,'animals, mammals generally,
or other life forms such as vegetation, insects, or reptiles)
from the deleterious effects of pollutants or other harmful
substances such as pollen, bacteria, or germs. This embodiment
of the invention is directed to a method for maintaining, within
an enclosed area, an environment substantially free of
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impurities. An "enclosed area" is hereby defined as an area
which is partially or completely enclosed. The method incluoes
the steps of applying to the interior surface of the enclosed
area a coating composition comprising an alkaline buffer and
an adsorbent, as described above, and drying the composition to
form a coated surface on the interior of the enclosed area.
"Interior surface" is hereby defined as all or part of the
interior surface. In certain applications, only an adsorbent
may be used. The enclosed area maybe a photographic darkroom,
a hospital or laboratory clean room, a conservation laboratory,
a collection room, a museum exhibit case, a drawer, or a
shipping or packing crate.
In a preferred aspect of the invention, multiple alkaline
buffers and/or multiple adsorbents may be used in the coating
composition or adhesive mixture. Preferably, the composition
comprising an adsorbent and an alkaline buffer may be in a
solution, such as a slurry yr a colloidal solution, which may be
applied to a surface and dried. The coating composition may be,
for example, a paint.
The archival material of the present invention is made, in
one embodiment, by applying to a substrate a solution made up of
an alkaline buffer capable of neutralizing acidic components
from the environment of the archival article and an adsorbent
capable of removing chemical components from the environment o'
the archival article.
Another embodiment of the present invention is a coated
substrate, wherein the coating is comprised of the alkaline
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buffer and adsorbent described above. The substrate may be
coated using coating methods know in the art.
For the purposes of the invention, the term "alkaline
buffer" includes all compounds which are capable of reducing or
eliminating the effect of acidic~components in an environment,
i.e., deacidifying agents. The alkaline buffer to be,used in
the invention includes all known alkaline materials which are
compatible with the.articles which are to be preserved. The
alkaline buffer may neutralize acids and other impurities which
are in the environment of the archival article. The acids may
be present due to acidic material penetrating the containerlor
support holding the archival article, acidic materials
originally in the atmosphere of-a closed container, acidic
materials from the archival articles themselves, or acidic by-
products from the action 'of impurities in the environment of t:~e
archival article.
In a preferred aspect, the alkaline buffer in the inventive
composition is an alkaline earth carbonate or bicarbonate, such
as calcium carbonate, magnesium carbonate or magnesium
bicarbonate. Zinc oxide or zinc carbonate may.also be a
suitable alkaline buffer. One or more alkaline buffers may be
used, for example, a combination of calcium carbonate, magnesium
carbonate, and zinc oxide.
The adsorbents to be used in the invention include all know
adsorbents which axe compatible with the archival articles to be
preserved. The adsorbents may adsorb, absorb_or react and
decompose a variety of impurities which are in the environment
o~ the archival article. The impurities may be present due to
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impurities penetrating a container holding the archival article,
impurities originally in the container material, impurities
originally in the atmosphere of a closed container, impurities
from the archival articles or by-products from impurities in the
environment of the archival article. For example, impurities
may be emitted from various sources such as interior building
components including wood and oil based paints, air pollution or
other archival artifacts, such as concentrations of pyrite
trapped in fossils. Potential impurities may include, for
example, oxidizing agents, hydrogen sulfide (H2S), hydrogen
peroxide (HZ02), sulfuric acid (H2S0~), ozone (03),
formaldehyde, nitrogen oxides (NOx), chlorine (C12), and sulfur
dioxide (S02), ketones, aldehydes, phenols, and their associated
acids.
In a preferred embodiment, the adsorbent in the coating
composition is an activated carbon (including modified activated
carbon), activated charcoal, or similar carbon-containing
adsorbent materials, a molecular sieve, silica; silicate gel,
activated alumina or combinations of these. The adsorbent may
also be todokorite, a form of manganese oxide which, like
molecular sieves, contains a network of tunnels that can adsorb
other compounds. Todokarite can exchange ions and contains
large tunnel diameters of 0.69 nm. Preferably, the adsorbent is
activated carbon or a molecular sieve, such as a zeolite.
Activated carbon may be defined as carbon (charcoal) treated
at high temperature with steam, air or carbon dioxide which
gives the carbon a porous internal structure and imparts
improved adsorbent qualities. The activated carbon may also be
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modified with other materials, such as copper, chromium, or
a caustic such as sodium hydroxide. The used activated
carbon may be regenerated. Activated carbons are
commercially available, such as PCB-G Pulverized, WPA, BL,
FCA (treated with Cu and Cr), and Sel Fu Sorb (treated with
Cu), produced by Calgon Carbon Corporation.
A molecular sieve includes a microporous structure,
such as crystalline aluminosilicates, belonging to a class
of materials known as zeolites, or crystalline
aluminophosphates derived from mixtures containing an
organic amine or quaternary ammonium salt. Molecular sieves
are known for their selective molecular separations based on
size and polar properties. Molecular sieves generally act
as adsorbents for those molecules that are small enough to
pass through the pores of the crystals to enter the cavities
and be adsorbed on the interior surface. Molecular sieves
such as the mesoporous materials referred to by Beck et al.,
American Chemical Society, December 30, 1992, may provide up
to about 700 or more square meters of surface area per gram.
The used molecular sieves may also be regenerated, for
example, by vacuum or a nitrogen sweep.
Zeolites are natural and synthetic compounds
characterized by an aluminosilicate tetrahedral framework.
Zeolites may have an aesthetic advantage over activated
carbon in preserving archival articles as contemplated
herein. Activated carbon generally will cause the
preservation article, i.e., the substrate on which the
coating compositions or adhesive mixtures of the present
invention are applied, to have a gray appearance
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and may leave a pencil-like mark on an archival article that it
contacts. ~~e zeolites are generally white and do not leave
marks on th= archival articles they contact. Zeolites are
commercially available, such as Purmol*3A (a synthetic sodium
aluminosilicate, pore size approximately 3 angstroms), Purmol*9A
(a synthetic sodium aluminosilicate, pore size approximately a
angstroms), ~urmol 5a (a synthetic calcium sodium
aluminosilicate, pore size approximately 5 angstroms) and Purmol*
13x (a synti-!~tic sodium aluminum silicate, pore size
approximately 10 angstroms), produced by ZeoChem. The zeolites
may be oretY=aced, .or example, by dehydration, ion exchange, or
impregnation with compounds suc~ as oxidants, including
potassi Lm p~=~argana~e, prior to beco;,ii ng part of the coating
co~~os : t i on .
In a pre_erYed aspect, the alk2line 5ufier or co~mbi-~ation o.
bu_=ers ar,d :.~e adsorbent or co~~bination o. adsorbents, and the
anount o. als~line buffer and 2dSOrD°nt to be used are selected
based on the type of impurities expected to be present in the
environ;,ent o_ the archival article. For example FCA (treated
with Cu and Cr) may adsorb or react with sulLides or peroxides;
Sel Fu Sorb (treated with Cu) may adsorb or react with peroxide
and sul~ides; Purmol*~A and Purmol*5A may adsorb or react with
peroxides, sulfides, sul~ur dioxide and nitrogen oxides; and
zinc oxide may adsorb or react with sulfides. Activated carbon
may adso=b or react with low molecular weight materials, such as
acetic acid and formic acid. Preferably, activated carbon may
adsorb compounds having molecular weights of 60 or more.
* trade-mark
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CA 02524814 1996-08-08
ACtiVested Carbon may cdSOrb Or r2cCt With ChlOr?ne, OZCn?,
peroxides, and possibly formaldehyde.
~n anotieer preferred 2t~l~Odimer.t, the adsorbent is a
moleculaY sieve which Pas the characteristics o~ being
organophilic, hydrophobic, and/or acid-resistant. Such
molec~~ar sieves are commercially avaiOable, e.g., Purmol 5A-1
and ?ur~noh'SA-2, both o_ which are expected to be acid-resistant
and hydrophobic and are proouced by ZeoChem; MHSZ-173 and MHSZ-
X20, which are expected to be acid-resistant and hydroprobic and
are produced by UO? Co.; anc AW 300 and A41 500, which are
expected to be acid-resistant and are produced by IiOP Co.
~w0 Or more 2a50r'DentS Ti~cy be COiilbli ed, OartlCUlarly li the
d3IIe?'°i7t cClSOrb°ntS al'e S°~2Cte4 t0 r2mOVe Q?
i_2rent lTiOUrlt3eS
~rOm t~e e:?V11"On~°nt Oi the c?'Ch! Val crt3C12. ='Or
°_XSi'~lD~e,
Z20~ ? t25 O. O__ ~ 2ront pyre criZeS O'_' COi3J1Pdt10~S OF Ze01 l t2 (S)
Znd cCt? VotCd Cn=~O:? (S~ 1ZV a° m? %ed tOgethe= 1~? OiOer t0
CaptL=? 03" r?cCt V11 C. h nol ecu?'S O. WarY3:'.g 5? Ze5 .
COmb1'?ctl0n O. zn al s211~ ° Dlli ~ 21' and an aasor~'Ja:lt
aCCOr42ng t0 the lnsl°ni.ion may alSO eXhlblt a SynerglSt?C
e~iect. For example, the adsorbent may capture various
impurities and prevent them =rpm contac~ing and damaging the
archival article. !-towever, tae captured impurity may react with
another compound and release a product which may contact and
damage the ~=chival article. For example, sulur dioxide (S02)
which is trapped on an adsorbent may react with moisture and
oxygen. to produce sul~uric acid (:~2SOa) which may contact and
damage the archival article. Howwer, in the invention, the
alkali:~2 buy=er will neutralize acidic compounds, including
* trade-mark
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sulfuric acid (H~SOQ). Therefore, the combined action of the
alkaline buffer and the adsorbent may have a synergistic effect.
The amount of alkaline buffer and adsorbent in the inventive
composition may vary, depending on factors such as the
configuration of the archival article and the coated or adhered
material, the sensitivity of the archival article to the
components of the coating or adhesive, the impurities expected
to be in the environment of the archival article and the length
of time for preservation. In a preferred embodiment, the
coating or adhesive may preferably contain an amount of alkaline
buffer or buffers which ranges from about 1 to about 20~, and
more preferably from about 2 to about S~, and most preferably
from about 3 to about 5i by weight based on the total weight of
the coating or adhesive composition. In a further preferred
embodiment, the coating or adhesive composition may preferably
contain an amount of adsorbent or adsorbents which ranges fron
about ? to about 50s, more preferably =rom about.5 to about 35~,
and most preferably from about 15 to about 35s by weight based
on the total weight of the composition.
A coating composition based on the present invention can be
made, for example, by suspending activated carbon and calciun
carbonate into a colloidal suspension with the use of bentonite,
a colloidal clay which is composed chiefly of montmorillonite,
an aluminosilicate c?ay with a high cation exchange capacity.
Bentonite forms gelatinous suspensions at low concentrations and
exchanges the surface charge. The coating composition nay also
include latex or other binders used in paints, emulsions, anc
coatings.
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Paper may be coated by using a mixture comprising clay and
adhesives. The coating can be applied during the manufacturing
process or after the paper is made. Alkaline buffers and
adsorbents according to the present invention can be used in
partial or complete replacement of the clay normally used to
coat paper and/or can be mixed with the adhesive. The alkaline
buffers and adsorbents can be mixed with solid, liquid, or gas
(e. g., aerosol) phase adhesives.
Other methods can be used to produce a coating or adhesive
based on the present invention: Those of ordinary skill in the
art will recognize other methods of producing a coating or
adhesive.
The following examples are illustrative o. ~he invention,
but are not intended to limit it.
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CA 02524814 1996-08-08
E PLES
Example 1
Photographic negatives were placed inside two paperboard
boxes, each box having three holes drilled in two opposing
sides. Hox #1 was coated inside with a coating composition of
the present invention comprising .about 1~ bentonite, 3s acrylic
latex, 3~ calcium carbonate, 34. ex activated carbon, and water.
The pH of the composition was 9.5. The viscosity of tZe
composition was 535 centipoise, measured with a Brookfield
Viscometer LVF. Hox n2 was not coated.
2000 ppm H202 was then released into the environment of the
boxes. The negatives in Box #2, the uncoated box, were heavily
damaged. However, the negatives in Box rl, the coated box, were
totally undamaged, despite the fact that there wexe six holes
drilled in the sides of the box, potentially allowing
environmental impurities to enter.
ExamnlP
Newspaper, off paper, and a piece of shiny copper were placed
inside two paperboard boxes. Box #1 was coated inside with a
coating composition of the present invention as in Example 1.
Box #2 was. not coated.
Both boxes were placed together in a chamber with 2000 ppm
No2. In Box #2, the uncoated box, the pH paper registered
acidic, the newspaper was heavily damaged and yellowed, and the
copper was severely tarnished. In Box #1, the coated box, the
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newspaper was totally undamaged, the copper remained shiny, and
the pH paper did not register a change, i.e., it did not become
acidic.
Examn~"e 3
Newspaper and pH paper were placed under two sheers of
alkaline buffered 0.010 tan paper which had been laminated
together with an adhesive composition comprising polyvinyl
alcohol and an adsorbent. The amount of alkaline buffer in the
buffered paper was about 3.5~. The amount of adsorbent is shown
in the table below. 2000 ppm N02 were then released into the
environment of the paper. The results are shown in Table 1
below.
Table 1: Adsorbent in Adhesive Composition
~OR3=N'T ('s IN ADziFSIVB) NEWSDAPER o~I PAPER
Zeolite (20'x) no change no cha.-.ge
Activated carbon (20s) yellowing becoming acidic
Zeolite (lOx) yellowing becoming acidic
Activated carbon (1os) yellowed acidic
No adsorbent yellowed acidic
As can be seen, better results were obtained, i.e.,.newspaper
remained white and pH paper remained purple (neutral?, when
zeolite was used as the adsorbent in an amount of 20~.
-21-
