U.S. patent application number 10/749166 was filed with the patent office on 2004-07-22 for method for forming colored cellulosic materials.
Invention is credited to Szymanski, Matthew A..
Application Number | 20040139566 10/749166 |
Document ID | / |
Family ID | 32511757 |
Filed Date | 2004-07-22 |
United States Patent
Application |
20040139566 |
Kind Code |
A1 |
Szymanski, Matthew A. |
July 22, 2004 |
Method for forming colored cellulosic materials
Abstract
A method for applying a colorant to a cellulosic substrate to
improve the resistance of the colorant to removal from the
substrate by wetting or rubbing. The method is a two-step process
in which the colorant is applied to the substrate in a first step,
and in which an elastomeric overcoat is applied to the substrate
over the colorant in a second step. The colorant includes a
pigment, thickeners and water and can be applied to the substrate
in a manner similar to the application of the overcoat, i.e., by
any suitable on or off-paper machine process.
Inventors: |
Szymanski, Matthew A.;
(Pulaski, WI) |
Correspondence
Address: |
Mathew E Corr
BOYLE FREDRICKSON NEWHOLM STEIN & GRATZ S C
250 Plaze Suite 1030
250 East Wisconsin Avenue
Milwaukee
WI
53202
US
|
Family ID: |
32511757 |
Appl. No.: |
10/749166 |
Filed: |
December 30, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60437978 |
Jan 3, 2003 |
|
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Current U.S.
Class: |
8/518 |
Current CPC
Class: |
D21H 19/82 20130101;
D21H 21/28 20130101; D21H 23/70 20130101 |
Class at
Publication: |
008/518 |
International
Class: |
D06P 003/60 |
Claims
We hereby claim:
1. A method for coloring a substrate, the method comprising the
steps of: a) providing a cellulosic substrate; b) applying a
colorant to the substrate, the colorant including a pigment, a
thickener and a solvent; and c) applying an overcoat to the
substrate over the colorant.
2. The method of claim 1 wherein the substrate is selected from the
group consisting of: white-top linerboard, linerboard and
paper.
3. The method of claim 1 wherein the pigment is selected from the
group consisting of a basic fiber reactive dye, an anionic fiber
reactive dye, and dry coloring matter.
4. The method of claim 1 wherein the thickener is present in an
amount of between 1% and 40% by weight.
5. The method of claim 4 wherein the thickener is selected from the
group consisting of: natural thickeners, synthetic thickeners and
combinations thereof.
6. The method of claim 5 wherein the natural thickeners are
polysaccharides.
7. The method of claim 5 wherein the natural thickener is selected
from the group consisting of starch, carboxymethylcellulose and
combinations thereof.
8. The method of claim 7 comprising: a) starch in an amount of
between about 1% and 25% by weight of the colorant; and b)
carboxymethyl cellulose in an amount of between about 0% and 10% by
5 weight of the colorant.
9. The method of claim 1 wherein the pigment is present in an
amount of between about 1% and 50% by weight of the colorant.
10. The method of claim 9 wherein the pigment is present in an
amount of between about 1% and 30% by weight of the colorant.
11. The method of claim 1 wherein the step of applying the colorant
comprises dispensing the colorant at an application rate of between
about 1% to 40% by weight of the substrate.
12. The method of claim 1 wherein the overcoat is an elastomer.
13. The method of claim 12 wherein the overcoat is selected from
the group consisting of polybutadienes, polyisobutylenes,
polystyrenes, polyacrylates, and polyurethanes.
14. The method of claim 12 wherein the overcoat is a latex.
15. The method of claim 12 wherein the step of applying the
overcoat comprises dispensing the overcoat at an application rate
of between about 1% and 25% by weight of the substrate.
16. The method of claim 1 wherein the step of applying the colorant
is performed in a process selected from the group consisting of
off-paper machine applications or on-paper machine
applications.
17. The method of claim 1 wherein the step of applying the overcoat
is performed in a process selected from the group consisting of
off-paper machine applications or on-paper machine
applications.
18. A colored substrate formed by a process comprising the steps
of: a) providing a cellulosic substrate; b) applying a colorant to
the substrate, the colorant including a pigment, at least one
thickener selected from the group consisting of synthetic
thickeners, natural thickeners and combinations thereof, and water;
and c) applying an overcoat to the substrate over the colorant,
wherein the overcoat is an elastomer.
19. A colored cellulosic substrate comprising: a) a sheet of a
cellulosic substrate; b) a colorant applied to a surface of the
substrate, the colorant including a pigment, at least one thickener
selected from the group consisting of synthetic thickeners, natural
thickeners and combinations thereof, and water; and c) an overcoat
applied to the surface over the colorant, wherein the overcoat is
an elastomer.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from U.S. Provisional
Patent Application Serial No. 60/437,978, which was filed on Jan.
3, 2003.
FIELD OF THE INVENTION
[0002] The present invention relates to dyeing processes, and more
specifically to methods for dyeing paper and other cellulosic
materials.
BACKGROUND OF THE INVENTION
[0003] On many occasions, it is desired to utilize a cellulosic
material product, such as paper, linerboard, paperboard and/or
cardboard, that has a specific color for a particular use. For
example, when decorating for a special occasion, streamers of
various colors are often utilized to provide a festive appearance
to the location at which the occasion is being celebrated.
[0004] In order to form products formed of a cellulosic material
and having a desired color, many different dying techniques have
been utilized. While many of these dyeing techniques provided
adequate color to the cellulosic material being dyed when finished,
a significant problem remained in that the dye often times washed
out or bled from the cellulosic material either during the dying
process or when the material was contacted by a liquid or simply
rubbed against another surface.
[0005] In order to attempt to overcome the bleeding problem, a
number of different dyeing compositions and methods were developed.
For example, Reinhardt U.S. Pat. No. 4,502,807 discloses a dye
stuff that incorporates a thickening mixture including both a
synthetic thickening agent and a polysaccharide. The presence of
the thickening mixture with these components enhanced the ability
of the dye to remain in the proper location on the textile to which
the dye was applied. Further, Panto et al. U.S. Pat. No. 4,398,915
discloses a method of preparing bleed resistant colored cellulosics
utilizing a colored particle such as a dye/starch complex formed as
a reaction product of a starch with a reactive dye compound and a
chemical cross-linking agent. Further, Kiesewetter et al. U.S. Pat.
No. 5,384,585 discloses the printing of textiles using a dye
composition including a reactive dye and a methylcarboxymethyl
cellulose as a thickener.
[0006] However, these techniques, while initially providing the
paper, linerboard, paperboard or cardboard product with the desired
color and an increased level of resistance to bleed or color
migration, do not achieve the desired level of resistance to the
removal of the colored dye from the product. As a result, colored
products are still produced in which the color bleeds from the
product, or in which the color can be removed from the product by
wetting and/or rubbing a colored surface of the product.
[0007] Therefore, it is desirable to develop a method for dying or
otherwise coloring a cellulosic product in which the dye or color
added to the product is highly resistant to removal from the
product.
SUMMARY OF THE INVENTION
[0008] The present invention is an improved method for coloring
cellulosic material products in which the color is applied to the
product such that the color does not bleed and/or cannot be easily
removed from the product. The method or process involves two
separate steps which achieve the desired result of applying the
color or dye to the product such that the dye is highly resistant
to removal.
[0009] The first step in the method involves applying the colorant
to the cellulosic substrate in any of a number of well-known
application methods. The colorant applied to the cellulosic
substrate is formed as an aqueous solution of a thickener, a dye,
and water. The thickener can be virtually any suitable material
used to thicken and stabilize a dye composition, as will be
described. Also, a wide range of dyes can also be used in forming
the colorant, as will be described. The colorant formed by the dye,
thickener and water can be any suitable colorant used in the
printing or dyeing of cellulosic materials and/or textiles that is
able to be applied to the substrate in any of a number of
conventional dye application methods and that resists any spreading
or migration on the surface of the substrate after application.
[0010] In the second step, an overcoat material is applied to the
substrate over the colorant in order to form a protective film over
the colorant on the cellulosic material and increase the resistance
to removal of the colorant from the substrate. The overcoat
material essentially provides a barrier between the colorant and
any liquid and/or surface that prevents contact with the colorant,
thereby maintaining the colorant on the substrate.
DETAILED DESCRIPTION OF THE INVENTION
[0011] The present invention is an improved method for applying a
colorant to a cellulosic substrate in a two-step process which
greatly improves the resistance to removal of the colorant on the
substrate. While the method is applicable to the application of a
colorant or dye to virtually any number of different substrate
types, some of the preferred substrates which are capable of being
utilized in this method include cellulosic substrates such as
white-top linerboard, linerboard, and paper, among others.
[0012] In a particularly preferred embodiment of the method of the
invention, the substrate is a white-top linerboard that is defined
as a two-ply cellulosic web that has a basis weight of 20 pounds to
90 pounds per 1000 square feet. The base ply is comprised of a
virgin material, recycled material or any combination thereof. The
top ply of the cellulosic web is comprised of bleached or de-inked
cellulosic fiber with a GE brightness of at least 60.
[0013] Another preferred substrate is linerboard which is defined
as a two-ply cellulosic web that has a basis weight of 20 pounds to
90 pounds per 1000 square feet. The base ply is comprised of virgin
material, recycled material, or any combination thereof. The top
ply of the cellulosic web is comprised of recycled or virgin
cellulosic fiber.
[0014] Still another preferred substrate is paper which is defined
as a cellulosic web that has a basis weight of 20 pounds to 160
pounds per 3000 square feet. The web may also include filler
materials including, but not limited to, clay, calcium carbonate,
titanium dioxide, and/or sizing agents.
[0015] When applying the colorant to the desired substrate, in the
first step, the colorant is added to the substrate in a suitable
printing or dyeing process, such as either a conventional off-paper
machine application, or an on-paper machine application, including
via a size press or water box. Some suitable off-paper machine
application processes can include, but are not limited to,
flexographic application, rod application, and/or processes
utilizing air-knife coaters.
[0016] The colorant is most preferably comprised of a solution of a
thickener, the pigment, and/or dye stuff, and water in the
following proportions:
[0017] 1-30% by weight dye stuff and/or pigment;
[0018] 1-15% by weight a first thickener;
[0019] 1-5% of an optional second thickener (in lieu of or in
addition to the first thickener) for rheology modification; and
[0020] the balance, water.
[0021] With particular regard to the dye stuff or pigment, the dye
stuff for the purposes of this disclosure is defined as any
compound within the class of either basic dyes or anionic direct or
fiber reactive dyes, or a pigment that can impart a color to a
cellulosic material such as a dry coloring matter, usually an
insoluble powder to be mixed with water, oil or another base to
produce paint in similar products. More particularly, in one aspect
of the present invention, there is thus provided a colorant
comprising, as a direct dye, a compound represented by the
following formula (1): 1
[0022] wherein, ring A represents a benzene ring which may have a
substituent or may further be cyclocondensed with another aromatic
ring;
[0023] B represents an aryl group which may have a substituent or
may be coupled with R.sup.2 to form a heterocyclic structure which
will be described later, or a heterocyclic group which may have a
substituent or may be coupled with R.sup.2 to form a heterocyclic
structure which will be described later,
[0024] D represents a nitrogen atom or a group CR.sup.4 (in which
R.sup.4 represents a hydrogen atom or a C.sub.1-6 alkyl group);
[0025] E represents a group NR.sup.5, CR.sup.6R.sup.7 or
CR.sup.6.dbd.CR.sup.7 (in which R.sup.5 represents a C.sub.1-6
alkyl group which may have a substituent, a C.sub.2-6 alkenyl group
which may have a substituent or an aryl group which may have a
substituent, or forms, when taken together with R.sup.2, a ring
which will be described later, and R.sup.6 and R.sup.7 each
independently represents a hydrogen atom or a C.sub.1-6 alkyl
group), an oxygen atom or a sulfur atom;
[0026] R.sup.1 represents a C.sub.1-6 alkyl group which may have a
substituent, a C.sub.2-6 alkenyl group which may have a substituent
or an aryl group which may have a substituent;
[0027] R.sup.2 represents a divalent group bonded to B or forms,
when taken together with R.sup.3 or R.sup.5, a ring which will be
described later,
[0028] R.sup.3 forms, when taken together with R.sup.2, a ring
which will be described later;
[0029] n stands for 0 or 1, with the proviso that when n=0, R.sup.2
and R.sup.5, when taken together with N--C--C, form a 5- to
7-membered nitrogen-containing heterocyclic structure which may
have a substituent, or R.sup.2 is bonded to B, thereby forming a 6-
or 7-membered heterocyclic structure which may have a substituent
and may contain a hetero atom other than D and when n=1, R.sup.2
and R.sup.3, when taken together with C=D-N, form a 5- to
7-membered nitrogen-containing heterocyclic structure which may
have a substituent, and
[0030] X.sup.- represents an anion.
[0031] In the formula (1), examples of the substituent which the
ring A may have include alkyl groups, aryl groups, alkoxy groups,
amino groups, hydroxy groups, cyano groups, nitro groups and
halogen atoms, more specifically, methyl group, ethyl group,
methoxy group, ethoxy group, chlorine atom and bromine atoms.
Examples of the aromatic ring with which the ring A may be
cyclocondensed include a benzene ring.
[0032] Examples of the aryl group represented by B include phenyl,
1-naphthyl and 2-naphthyl groups, while those of the heterocyclic
group include 2-benzthiazolyl and 3-indolyl groups, each of which
may be substituted with a chlorine atom, bromine atom, nitro group,
cyano group, C.sub.1-4 alkyl group, phenyl group, benzyl group,
C.sub.1-4 alkoxy group, hydroxy group, phenoxy group, benzyloxy
group, C.sub.1-4 alkylsulfonyl group, phenylsulfonyl group,
benzylsulfonyl group, aminocarbonyl group, mono- or di-(C.sub.1-4
alkyl)aminocarbonyl group, aminosulfonyl group, C.sub.1-4
alkylcarbonyl group, C.sub.1-4 alkylcarbonylamino group,
benzoylamino group, phenylazo group, and a group NR.sup.8R.sup.9
(in which R.sup.8 and R.sup.9 each independently represents a
hydrogen atom, C.sub.1-4 alkyl group, aryl group, aralkyl group,
unsubstituted or mono- or di-(C.sub.1-4 alkyl)-substituted
amino(C.sub.1-4 alkyl) group, amino(C.sub.1-4 alkyl) group
substituted by a group of the formula (1) from which one hydrogen
atom has been removed, or (C.sub.1-4 alkoxy) (C.sub.1-4 alkyl)amino
group). The number of these substituents is 1 to 3. The
cycle-constituting atom may be coupled with the above-exemplified
substituent to form another cyclic structure.
[0033] Examples of the C.sub.1-6 alkyl group represented by R.sup.4
in the case where D represents a group CR.sup.4 or by R.sup.6 or
R.sup.7 in the case where E represents a group CR.sup.6R.sup.7 or
CR.sup.6.dbd.CR.sup.7 include methyl, ethyl, propyl, isopropyl and
cyclohexyl groups. Preferred examples of R.sup.4, R.sup.6 or
R.sup.7 include hydrogen atom and methyl groups.
[0034] Examples of the C.sub.1-6 alkyl group represented by R.sup.5
in the case where E represents a group NR.sup.5 include methyl,
ethyl, propyl, isopropyl and cyclohexyl groups; those of the
C.sub.2-6 alkenyl group include ethenyl and propenyl groups; and
those of the aryl include phenyl and naphthyl groups, each of which
may be substituted with an aryl, alkoxy, amino, hydroxy or cyano
group, or a halogen atom.
[0035] Examples of the C.sub.1-6 alkyl group represented by R.sup.1
include methyl, ethyl, propyl, isopropyl and cyclohexyl groups,
those of the C.sub.2-6 alkenyl group include ethenyl and propenyl
groups, and those of the aryl group include phenyl and naphthyl
groups, of which the alkyl group is preferred as R.sup.1. Examples
of the group which may be a substituent for them include aryl
groups, cyano group, halogen atoms, hydroxy group, C.sub.1-4 alkoxy
groups, NR.sup.10R.sup.11 (in which R.sup.10 and R.sup.11 each
independently represents a hydrogen atom, C.sub.1-4 alkyl group,
aryl group, aralkyl group, unsubstituted or mono- or di(C.sub.1-4
alkyl)substituted amino(C.sub.1-4 alkyl) group, or (C.sub.1-4
alkoxy) (C.sub.1-4 alkyl)amino group) and a group of the formula
(1) from which one hydrogen atom has been removed.
[0036] Examples of the R.sup.5--R.sup.2 or R.sup.2--R.sup.3 in the
case where a 5- to 7-membered nitrogen-containing heterocyclic
structure which may have a substituent is formed by R.sup.2 and
R.sup.5 when they are taken together with N--C--C at n=0, or by
R.sup.2 and R.sup.3 when taken together with C=D-N at n=1, include
groups represented by --(CR.sup.12R.sup.13).sub.m-- (in which
R.sup.12 and R.sup.13 each independently represents a C.sub.1-4
alkyl group and m stands for an integer of 2 to 4).
[0037] Examples of the divalent group, as R.sup.2, bonded to B in
the case where a 6- or 7-membered heterocyclic structure which may
have a substituent and may have a hetero atom other than D is
formed by bonding of R.sup.2 to B when n=0 include groups
--CH.dbd.N-- and --Co--O--.
[0038] Examples of the anion represented by X.sup.- include
chloride ions, bromide ions, iodide ions, trichlorozincic acid
ions, tetrachlorozincic acid ions, sulfuric acid ions,
hydrosulfuric acid ions, methyl sulfate ions, phosphoric acid ions,
formic acid ions and acetic acid ions.
[0039] The thickener utilized in the formation of the colorant may
be selected from both synthetic and natural thickeners. More
specifically, the composition of the thickeners used in the
formation of the colorant can vary between a proportion of 0% for
the synthetic thickener and 100% by weight for the natural
thickener, and vice versa, depending upon the response of the
products used to the disburse dye stuffs used. Mixtures which are
more preferable regarding the dispersion stability of the dye
stuffs contain between 1 to 30% by weight of the natural
thickeners, and most preferably between 1 to 15%, and 1 to 10% by
weight of the synthetic thickeners, and most preferably between 1
to 5%.
[0040] The synthetic thickenings are preferably carboxyl containing
synthetic thickenings and the natural thickenings are based on
polysaccharides in preferred embodiments of the invention. Examples
of suitable carboxyl-containing synthetic thickenings which can be
used according to the invention are aqueous solutions or
gel-forming dispersions of polymerized low molecular weight
monoethylenically or polyethylenically unsaturated monocarboxylic
or dicarboxylic acids, such as polyacrylic acid and its homologs,
for example products of polymerizing methacrylic acid or crytonic
acid, and polymers of carboxyalkylderivatives, such as idaconic or
teraconic acid, similarly aqueous solutions of or dispersions of
polymerized maleic acid or its anhydride and fumaric acid and of
its homologs, such as, for example, citriconic acid or mesaconic
acid, further of copolymers of olefins, for example, ethylene,
propylene or butadiene or of lowelalkylacrylates, optionally
substituted acrylamids, vinyl alcohols, vinyl ethers, vinyl
esthers, vinyl chloride, vinyl edene chloride, styrene,
acrylonitrile, and analogous alkyl compounds and the
above-mentioned monomers. These examples also include the reaction
products of the polymers and copolymers described, with polyhydric
alcohols and amines, or amino alcohols, and combinations of highly
polymerized products with less highly polymerized products.
[0041] The polysaccharides used preferably as the natural
thickeners according to the invention embrace optionally degraded
and/or etherified natural products such as high molecular weight
carob bean flour or guar flour and starch or cellulose ethers. In a
particularly preferred embodiment, the thickener is formed only of
material thickeners including carboxymethyl cellulose and
starch.
[0042] While the components of the colorant can be mixed to form
the colorant in any suitable manner, a particularly preferred
method is ______.
[0043] After the colorant has been formed and applied to the
selected surface of the cellulosic substrate, the substrate may be
slightly dried to allow for a limited set of the colorant on the
substrate and to prevent the smearing of the colorant from the
substrate. Further, the colorant application rate can vary
depending upon the color shade depth desired on the surface of the
substrate. For example, in a preferred embodiment the application
rate of the colorant is 140% by weight of the substrate and more
preferably 1-15% by weight of the substrate.
[0044] After the application of the colorant to the substrate, in
the second step of the method, a film of a suitable overcoat
material is applied as an overcoat to the colored cellulosic
substrate to impart the requisite wet and dry rub fastness for the
colorant reacted onto the substrate. The application methods for
the overcoat material are similar to printing or dyeing methods
used for the application of the colorant and can include, but are
not limited to, off-paper machine application methods, such as
flexographic, rod, and/or knife air coaters. Further, with regard
to the overcoat material the material is a natural or synthetic
rubber formed from various compounds, including but not limited to
polybutadiene, polyisobutylenes, polystyrenes, polyacrylates and
polyurethanes. In a preferred embodiment the material is a latex,
which for the purposes of this invention is defined as any material
within the class of modified styrene butadiene-based polymers or
modified styrene acrylate polymers with provisions for changes in
polymer TG value or polymer combination. More preferably, the
overcoat may be a 50% solids latex product which is used as a
"varnish" layer over the substrate, to provide wet and dry rub
fastness and to add a gloss or matte finish to the substrate.
Further, the overcoat application rate to the substrate can vary
depending upon the level of fastness and the gloss level required
for the substrate, with greater fastness properties and higher
gloss achieved with a higher overcoat application rate. More
specifically, in a preferred embodiment the application rate for
the overcoat will be within a range of 1% to 25% by weight of the
substrate and more preferably between 1% and 5% by weight of the
substrate.
[0045] Colored linerboard produced as described may be used in any
corrugated application, e.g. point of purchase displays or
corrugated containers. Application of the overcoat material
enhances printability of the material and ensures that the print
medial does not bleed into the underlying dyed substrate
[0046] Various alternatives are contemplated as being within the
scope of the following claims particularly pointing out and
distinctly claiming the subject matter regarded as the
invention.
* * * * *