U.S. patent application number 10/664798 was filed with the patent office on 2004-04-15 for methods of enhancing dyeability of polymers.
This patent application is currently assigned to University of Massachusetts, a Massachusetts corporation. Invention is credited to Fan, Qinguo, Ugbolue, Samuel C., Wilson, Alton R., Yang, Yiqi.
Application Number | 20040068807 10/664798 |
Document ID | / |
Family ID | 27732260 |
Filed Date | 2004-04-15 |
United States Patent
Application |
20040068807 |
Kind Code |
A1 |
Fan, Qinguo ; et
al. |
April 15, 2004 |
Methods of enhancing dyeability of polymers
Abstract
The invention relates to new methods of dyeing polymers. The
methods include dispersing nanomaterials into the polymers to form
polymer nanocomposites, and dyeing the polymer nanocomposites with
a dye. The invention also relates to dyed polymers thus obtained
and articles made from these dyed polymers.
Inventors: |
Fan, Qinguo; (North
Dartmouth, MA) ; Yang, Yiqi; (Lincoln, NE) ;
Ugbolue, Samuel C.; (New Bedford, MA) ; Wilson, Alton
R.; (North Dartmouth, MA) |
Correspondence
Address: |
FISH & RICHARDSON PC
225 FRANKLIN ST
BOSTON
MA
02110
US
|
Assignee: |
University of Massachusetts, a
Massachusetts corporation
The Board of Regents of the University of Nebraska, a Nebraska
corporation
|
Family ID: |
27732260 |
Appl. No.: |
10/664798 |
Filed: |
September 16, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10664798 |
Sep 16, 2003 |
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10068911 |
Feb 7, 2002 |
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6646026 |
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Current U.S.
Class: |
8/509 |
Current CPC
Class: |
C08F 8/00 20130101; C08F
20/00 20130101; C08F 10/00 20130101; C08F 8/00 20130101; Y10S
977/788 20130101; C08F 8/00 20130101 |
Class at
Publication: |
008/509 |
International
Class: |
D06P 003/52 |
Claims
What is claimed is:
1. A method of dyeing a polymer, the method comprising dispersing a
nanomaterial into the polymer to form a polymer nanocomposite, and
dyeing the polymer nanocomposite with a dye.
2. The method of claim 1, wherein the polymer is a polyvinyl, epoxy
resin, polyolefin, polyamide, aromatic polyamide, polyimide,
polyanhydride, acrylic polymer, polyester, polyimine,
polysaccharide, polypeptide, polylactone, or a random or block
copolymer thereof.
3. The method of claim 1, wherein the polymer is a polyolefin.
4. The method of claim 3, wherein the polyolefin is
polypropylene.
5. The method of claim 1, wherein the nanomaterial is nanoclay,
nanosilica, metal oxide, zeolite, or nanoparticles of a
polymer.
6. The method of claim 1, wherein a nanomaterial is pretreated with
a surfactant for improved compatibility with the polymer.
7. The method of claim 1, wherein a weight ratio of the
nanomaterial to the polymer is in the range of 0.01-20%.
8. The method of claim 1, wherein the weight ratio of the
nanomaterial to the polymer is in the range of 0.5-5%.
9. The method of claim 1, wherein the nanomaterial is intercalated
or exfoliated in the polymer.
10. A dyed polymer comprising a dye, a polymer, and a nanomaterial,
wherein the nanomaterial is dispersed in the polymer to form a
polymer nanocomposite, and the dye is linked to the
nanomaterial.
11. The dyed polymer of claim 10, wherein the polymer is a
polyvinyl, epoxy resin, polyolefin, polyamide, aromatic polyamide,
polyimide, polyanhydride, acrylic polymer, polyester, polyimine,
polysaccharide, polypeptide, polylactone, or a random or block
copolymer thereof.
12. The dyed polymer of claim 10, wherein the polymer is a
polyolefin.
13. The dyed polymer of claim 12, wherein the polymer is
polypropylene.
14. The dyed polymer of claim 10, wherein the nanomaterial is
nanoclay, nanosilica, metal oxide, zeolite, or nanoparticles of a
polymer.
15. The dyed polymer of claim 14, wherein the nanomaterial is
pretreated with a surfactant for improved compatibility with the
polymer.
16. The dyed polymer of claim 10, wherein the weight ratio of the
nanomaterial to the polymer is in the range of 0.01-20%.
17. The dyed polymer of claim 10, wherein the weight ratio of the
nanomaterial to the polymer is in the range of 0.5-5%.
18. The dyed polymer of claim 10, wherein the nanomaterial is
intercalated or exfoliated in the polymer.
19. An article made of the dyed polymer of claim 10.
Description
TECHNICAL FIELD
[0001] This invention relates to methods of dyeing polymers, more
specifically, methods of enhancing the dyeability of polymers.
BACKGROUND
[0002] Dyeing polymers such as polyolefins (e.g., polypropylene)
has been a challenge to polymer and textile chemists for many
decades. Currently available approaches rely mainly on
copolymerization, polyblending, grafting, and plasma treatment
technologies. Examples of such polymers include
vinylpyridine/styrene copolymers; poly(ethylene/vinyl acetate)
blended with polypropylene for disperse dyeability; stearyl
methacrylate, dimethylaminopropylacrylamide, or basic imidized
styrene-maleic anhydride copolymer for acid and disperse
dyeability; stearyl methacrylate-maleic anhydride for basic and
disperse dyeability; and organo-metal-complexes for specially
selected dyes. See, e.g., Akrman et al, Journal of the Society of
Dyers and Colourists, 114, 209-215 (1998); Luc et al.,
International Dyer, 32-36 (1998); and U.S. Pat. Nos. 6,127,480,
6,039,767, 5,985,999, 5,576,366, 5,550,192, and 5,468,259.
[0003] One disadvantage of these technologies is that they
considerably increase the costs of the dyed products due to the
cost increase of the process and materials. Another disadvantage is
that some of these technologies are not suitable for producing fine
fibers used in clothing materials.
SUMMARY
[0004] The invention is based on the discovery that the dyeability
of polymers, such as polyolefins, can be significantly enhanced by
incorporating into the polymers a nanomaterial such as a nanoclay,
nanosilica, metal oxide (e.g., zinc oxide, silver oxide, calcium
oxide, platinum oxide), zeolite, or nanoparticles of polymers
(e.g., polysiloxanes). The term "dyeability" refers to a polymer's
ability to be dyed, the rate at which the polymer can be dyed, the
amount of dye that can be applied to the polymer (i.e., dye
exhaustion), and the fastness of the dyes on the dyed polymers.
[0005] Accordingly, the invention is related to methods of dyeing
polymers by first dispersing a nanomaterial into the polymer to
form a polymer nanocomposite, and then dyeing the polymer
nanocomposite with a dye.
[0006] A "nanomaterial" refers to a particulate inorganic or
organic compound or composition having a particle size in the range
of 1-1,000 nm (e.g., 50-200 nm or 200-600 nm). Nanomaterials thus
include nanoclay, nanosilica, metal oxides (e.g., zinc oxide,
silver oxide, calcium oxide, or titanium oxide), zeolites, and
nanoparticles of a polymer. Nanomaterials can be pretreated with
ionic surfactants (e.g., alkyl ammonium salts or fluoro-organic
compounds) for enhanced compatibility with the polymer (e.g.,
enhanced hydrophilicity, hydrophobicity, or amphiphilicity,
depending on the hydrophilicity or hydrophobicity of the polymers),
and subsequent improved (i.e., more even) dispersion, depending on
the polymers.
[0007] The new methods are applicable to all polymers that need to
be dyed including those polymers that may be difficult to dye using
known techniques. Such polymers include polyvinyls (e.g.,
polystyrene), epoxy resins, polyolefins (e.g., polypropylene),
polyamides (e.g., nylon 6), aromatic polyamide (e.g., aramid),
polyimides (e.g., polypyromellitimide), polyanhydrides (e.g.,
polymaleic anhydride), acrylic polymers (e.g., polymethyl
methacrylate), polyesters (e.g., poly(ethylene terephthalate)),
polyimines (e.g., polyethyleneimine), polysaccharides (e.g. rayon),
polypeptides (e.g., zein), polylactones (e.g., polycaprolatone),
and their random or block copolymers. Useful polymers also include
derivatives of polymers, e.g., polymers with ester derivatives on
side acidic groups. The molecular weights of the polymers can be in
the range of 15,000 to 150,000, and they can be amorphous or highly
crystalline.
[0008] The methods are particularly suitable for polymers which are
difficult to dye. Such polymers, which generally have no or very
limited dyeability, include polyolefins, polyvinyls, aromatic
polyamides, and epoxy resins.
[0009] Embodiments of the new methods include those in which the
polymers are polyvinyls, epoxy resins, polyolefins, polyamides,
aromatic polyamides, polyimides, polyanhydrides, acrylic polymers,
polyesters, polyimines, polysaccharides, polypeptides,
polylactones, or a random or block copolymers thereof; and those in
which the weight ratio of the nanomaterial to the polymer is in the
range of 0.01-20% (e.g., 0.1-10% or 0.5-5%).
[0010] The polymer nanocomposites thus obtained can be in the form
of fibers, films, membranes, tubes, or particles.
[0011] The invention also relates to novel dyed polymer
nanocomposites, each containing dye molecules, a polymer, and a
nanomaterial dispersed in the polymer. The dyed polymer
nanocomposites can be prepared by first obtaining polymer
nanocomposites and then dyeing the polymer nanocomposites.
[0012] Also within the scope of the invention are articles made of
the novel dyed polymer nanocomposites.
[0013] Unless otherwise defined, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which this invention belongs. Although
methods and materials similar or equivalent to those described
herein can be used in the practice or testing of the present
invention, suitable methods and materials are described below. All
publications, patent applications, patents, and other references
mentioned herein are incorporated by reference in their entirety.
In case of conflict, the present specification, including
definitions, will control. In addition, the materials, methods, and
examples are illustrative only and not intended to be limiting.
[0014] The new methods and dyed polymers provide numerous
advantages. For example, the methods are relatively inexpensive and
easy to carry out. In addition, the dyed polymers can be easily
processed and have excellent mechanical strength, tensile strength,
gas impermeability, flame retardance, and heat resistance. The
dyeability of the resultant nanocomposites (e.g., dye exhaustion
rate and colorfastness) can be engineered based on the selection of
the nanomaterials and the modification of the process.
[0015] The details of several embodiments of the invention are set
forth in the description below. Other features, objects, and
advantages of the invention will be apparent from the description
and drawings, and the accompanying claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a graph showing build-up curves of an acid dye in
polypropylene nanocomposites.
[0017] FIG. 2 is a graph showing build-up curves of a disperse dye
in polypropylene nanocomposites.
[0018] FIGS. 3A to 3D are illustrations of a polypropylene
nanocomposite (nanoPP1) dyed in different dye bath concentrations,
each containing an acid dye. The amount of dye build-up in the
composite increased with an increase of the depth of shade in the
dye bath.
[0019] FIGS. 4A to 4C are illustrations showing another
polypropylene nanocomposite (nanoPP3) dyed in different dye bath
concentrations, each containing a disperse dye. The amount of dye
build-up increased with an increase of the depth of shade in the
dye bath.
[0020] FIGS. 5A to 5D are illustrations showing another
polypropylene nanocomposite (nanoPP6) dyed in different dye bath
concentrations, each containing a disperse dye. The amount of dye
build-up increased with an increase of the depth of shade in the
dye bath.
[0021] FIGS. 6A to 6D are illustrations showing another
polypropylene nanocomposite (nanoPP7) dyed in different dye bath
concentrations, each containing a disperse dye. The amount of dye
build-up increased with an increase of the depth of shade in the
dye bath.
DETAILED DESCRIPTION
[0022] The present invention provides methods of enhancing the
dyeability of a wide variety of polymers, such as polyvinyls (e.g.,
polystyrene), epoxy resins, polyolefins (e.g., polypropylene),
polyamides (e.g., nylon 6), aromatic polyamide (e.g., aramid),
polyimides (e.g., polypyromellitimide), polyanhydrides (e.g.,
polymaleic anhydride), acrylic polymers (e.g., polymethyl
methacrylate), polyesters (e.g., poly(ethylene terephthalate)),
polyimines (e.g., polyethyleneimine), polysaccharides (e.g. rayon),
polypeptides (e.g., zein), polylactones (e.g., polycaprolatone),
and their random or block copolymers. The methods include forming
nanocomposites of these polymers by using a nanomaterial, e.g.,
nanoclay (which contains montmorillonite (MMT)
Al.sub.2Si.sub.4O.sub.10(OH).sub.2), nanosilica, metal oxide,
zeolite, or nanoparticles of polymers such as polysiloxanes.
[0023] Preparation of Polymer Nanocomposites
[0024] The methods include first selecting a suitable nanomaterial
which is optionally treated with a surfactant (e.g., an anionic or
cationic surfactant such as an alkyl ammonium salt) to modify its
surface. After the surface modification, the nanomaterial can
become hydrophilic, hydrophobic, or amphiphilic, thereby enhancing
the accessibility of dye molecules to the polymer nanocomposite. A
polymer (e.g., a polyolefin), optionally dispersed (e.g.,
intercalated, or exfoliated) with a certain amount of the
nanomaterial is then heated to melt, or is dissolved in an organic
solvent, which is optionally heated. The nanomaterial is then
dispersed into the molten polymer or the polymer solution, giving a
polymer nanocomposite. Even dispersion of the nanomaterial in the
polymer or polymer solution can be achieved by methods known in the
art, e.g., by continuous stirring, ultrasonication, and/or
compounding (e.g., extrusion), optionally with the aid of
additional surfactants.
[0025] The dispersion of the nanomaterials within the polymers
creates dye sites for dyeing the polymers. Prior to the dispersion,
other components (e.g., fillers, which are water insoluble solids)
can also be added into the melted polymers or polymer solutions.
The other components can be added directly (i.e., as solids) to the
melted polymers or the polymer solutions. These other components
can also be added as solutions in organic solvents. Additional
examples of the other components include plasticizers, different
types of polymers, or other agents as needed.
[0026] The dispersion of the nanomaterials in the polymers can be
controlled, e.g., by changing the duration, pulse, and amplitude of
the ultrasonication, the crystallinity of the polymer, or the
compatibility of the nanomaterial and polymer. For instance, better
dispersion (e.g., more even distribution of the nanomaterials in
the polymers) can be achieved by increasing the duration or
amplitude of the pulse of the ultrasonication. Under the same
conditions, nanomaterials can be better dispersed into polymers
that are more crystalline. Better dispersion can also be achieved
in nanocomposites that contain nanomaterials and polymers that are
more compatible (e.g., hydrophilic nanomaterials and hydrophilic
polymers) than in nanocomposites that contain less compatible
nanomaterials and polymers (e.g., hydrophilic nanomaterials and
hydrophobic polymers).
[0027] After the dispersion, the melted polymers or the polymer
solutions can be allowed to solidify for storage or further
processing. They can also be directly processed into a desired
form, e.g., film, fibers, particles, or cylinders, using standard
techniques.
[0028] The polymer nanocomposites thus obtained can be
characterized by methods known in the art. For instance, their
thermal properties can be determined by using Differential Scanning
Calorimetry (DSC). An injection molder can be used for mechanical
testing and for measuring the nanocomposites' dynamic moduli. See,
e.g., Hasegawa et al., J. Applied Poly. Sci., 67, 87-92, 1998. The
dispersity of the nanomaterial in the polymer can be evaluated by
using wide-angle X-Ray Diffraction (XRD) and Transmission Electron
Microscopy (TEM). See, e.g., Manias et al., Polymeric Materials,
Science & Engineering, 82, 282-283, 2000. Optical microscopy
studies can reveal how the polymer nanocomposites are dyed. Tests
of the tensile strength of the polymer nanocomposites can be
carried out with an Instron tensile tester.
[0029] Because of their mechanical strength, the polymer
nanocomposites can be used as bulk materials, e.g., for packaging.
They can also be made into fibers that can be used to manufacture
woven or non-woven fabrics.
[0030] Dyeing the Polymer Nanocomposites
[0031] The polymer nanocomposites obtained as described above can
be dyed using conventional methods. For instance, they may be dyed
in a dye bath using conventional ionic dyes (i.e., acid or basic
dyes) and disperse dyeing techniques.
[0032] Acid dyes (one type of anionic dyes) contain acidic groups,
such as --SO.sub.3H, and are used with polymer nanocomposites
containing basic groups that can interact with these acidic groups.
The most common structural types of acid dyes are monoazo and
anthraquinone dyes. Examples of acid dyes include C.I. (Color
Index) Acid Red 138, C.I. Acid Red 266, and C.I. Acid Blue 45.
Structures of these three dyes are shown below: 1
[0033] Basic dyes (also called cationic dyes) can be used for
dyeing polymer nanocomposites that carry anionic groups. Examples
of basic dyes include C.I. Basic Blue 3 and C.I. Basic Green 4,
with structures shown below: 2
[0034] Disperse dyes are nonionic and almost insoluble in water.
They are used as finely distributed aqueous dispersions. Like acid
dyes, the two most common types of disperse dyes are also monoazo
and anthraquinone dyes. Examples of disperse dyes include C.I.
Disperse Blue 183 and C.I. Disperse Blue 73, with their structures
shown below: 3
[0035] Additional ionic (i.e., acid and basic) and disperse dyes
useful in the new methods are listed in "Dyes and Pigments by Color
Index and Generic Names" in Textile Chemist and Colorist, 24 (7),
1992.
[0036] Generally, the dye is used in the form of a dye solution so
that it can be readily applied by dipping the polymer
nanocomposites into a container with the dye solution, by spraying
the dye solution onto the polymer nanocomposites, or by using a
cascading roll technique. The dye solution can also be in the form
of a print paste, which is typically used in roller printing or
screen printing, particularly on fabrics made from the polymer
nanocomposites. The polymer nanocomposites can be dyed multiple
times using one or more dyeing techniques.
[0037] Aqueous dye baths typically have a pH value in the range
from about 2 to about 11, e.g., from about 2.5 to about 6.5 for
acid dyes, from about 8.5 to about 10.5 for reactive dyes, and from
about 4.5 to about 6.5 for disperse dyes and basic dyes. The pH may
be adjusted, if desired, using a variety of compounds, such as
formic acid, acetic acid, sulfamic acid, citric acid, phosphoric
acid, nitric acid, sulfuric acid, monosodium phosphate, trisodium
phosphate, sodium carbonate, sodium bicarbonate, ammonium
hydroxide, sodium hydroxide, or a combination thereof. A
surfactant, typically a nonionic surfactant, can also be used to
aid in dispersing sparingly water-soluble disperse dyes in a dye
bath. During the dyeing step, the dye bath is agitated to hasten
the dyeing rate. The dyeing step can be carried out at a variety of
temperatures, with higher temperatures generally promoting the rate
of dyeing.
[0038] The polymer nanocomposites can also be dyed by jet dyeing
(see Engineering in Textile Coloration edited by C. Duckworth, p.
56, Dyers Company Publications Trust, 1983), which permits
high-temperature dyeing and impingement of the dye onto moving
polymer nanocomposites (typically in the form of fabrics) through
use of a venturi jet system. Dye carriers permit faster dyeing of
the polymer nanocomposites, e.g., at atmospheric pressure and below
100.degree. C. Such dye carriers are typically organic compounds
that can be emulsified in water. Representative examples of such
carriers include aromatic hydrocarbons such as diphenyl and
methylnaphthalene, phenols such as phenylphenol, chlorinated
hydrocarbons such as dichloro- and trichloro-benzene, and aromatic
esters such as methyl salicylate, butyl benzoate, diethylphthalate,
and benzaldehyde. These carriers usually can be removed from the
dyed materials after dyeing. Dye carriers increase the rate of
dyeing by affecting both the polymer and the dye bath. The
absorption of typical carrier substances alters the viscoelastic
properties of the polymer nanocomposite in a manner consistent with
the view that carrier activity is associated with an increase in
polymer segmental mobility, at least in the more accessible region
of the polymer chain molecules. In addition to the use of carriers
in promoting the build-up of dyeing at the boil, small amounts of
carriers may be added in high-temperature dyeing processes to
promote the leveling of the more difficult disperse dyes.
[0039] During dyeing, the dyes are first adsorbed onto the surface
of the polymer nanocomposites, and subsequently attracted to the
dye sites created by the dispersion of the nanomaterials.
Ultimately, the dye molecules attach themselves to the
nanocomposites, thereby enhancing the dyeability of the polymer
nanocomposite. In some applications (e.g., thermosol dyeing), dry
heat may be applied to the polymer nanocomposites (after they are
removed from the dye baths) at a wide range of elevated temperature
to cause the dye to penetrate into, and become fixed in, the
polymer nanocomposites. The dye fixation step involves exposing the
dyed polymer nanocomposites to high temperature, wet or dry, e.g.,
in an oven. The temperature can vary up to 20 or 25.degree. C.
below the melting temperatures of the polymer nanocomposites.
Generally, higher drying temperatures result in shorter drying
times. Typically, the heating time is from about 1 minute to about
10 minutes. Residual dyes may then be removed from the polymer
nanocomposites, e.g., by rinsing with water or a reduction-clearing
bath.
[0040] Characterization of the Dyed Polymer Nanocomposites
[0041] A dyed polymer nanocomposite can be characterized, e.g., by
measuring the affinity between the dye and the polymer. The
dyeability can also be evaluated by determining the percentage
exhaustion of the dye in a dye bath, e.g., by measuring the
absorbance of the dye bath at the beginning and after dyeing, by
using a spectrophotometer.
[0042] The fastness against light, washing, rubbing, shampooing,
and dry cleaning of the novel dyed polymer nanocomposites can be
evaluated according to ISO procedures (e.g., ISO-B02:1994, ISO
105-CO1:1989, ISO 105-X12:1992, ISO document 473, and ISO
105-DO1:1993, respectively).
[0043] The efficiency of dyeing (i.e., dyeability) depends on the
type of dye and polymer, the size and structure of the
nanomaterial, and the weight ratio of the nanomaterial to the
polymer. A higher efficiency of dyeing can be achieved by adding a
higher amount of the nanomaterial into the polymers when the other
factors (i.e., the types of the dye and the polymer, and the size
and structure of the nanomaterial) are the same. In general, the
higher the compatibility between the nanomaterial and the polymer,
or the lower the crystallinity of the polymer, the higher the
dyeability of the polymer nanocomposite.
[0044] On the other hand, more even dyeing (improved color yield)
can be achieved in nanocomposites in which the nanomaterials are
more evenly distributed within the polymers. It can also be
achieved when a dye of smaller size is used.
[0045] Uses of the Dyeable Polymer Nanocomposites
[0046] The new dyeable polymer nanocomposites have improved
mechanical properties and tensile strength, and low permeability.
Further, when the amount of a nanomaterial is within a certain
range (e.g., less than 5%), the polymer nanocomposites are also
easy to process. Thus, these new dyeable polymer nanocomposites can
be widely used for making fibers, fabrics, films, plates, sheets,
and bulk materials such as toys, utensils, appliances, furniture,
and plastic tools as well as packaging materials.
[0047] The invention is further described in the following
examples, which are only illustrative and do not in any way limit
the scope of the invention described in the claims.
EXAMPLES
Example 1:
[0048] Preparation of Polypropylene Nanocomposites with Nanoclays
by Ultrasonication
[0049] Isotactic polypropylene chips (Philips Sumika Polypropylene
Company, Houston, Tex.), xylene (J.T Baker Company, Philipsburg,
N.J.), and a nanoclay (Cloisite 15A, Southern Clay Company,
Gonzales, Tex.) were mixed in a stainless steel container. The
nanoclay contains a natural montmorillonite (MMT) modified with a
quaternary ammonium salt having a structure shown below: 4
[0050] wherein HT in the formula specifies hydrogenated tallow of
C.sub.18 (approx. 65%), C.sub.16 (approx. 30%) and C.sub.14
(approx. of 5%).
[0051] Other specifications for Cloisite 15A, as provided by the
manufacturer, are shown in Table 1.
1TABLE 1 Physical properties of Cloisite 15A Particle Size Color
Less than 10% Less than 50% Less than 90% Density, g/cc Off 2.mu.
6.mu. 13.mu. 1.66 White
[0052] The container was placed in a sand bath insulated by
glass-fiber fabrics. A thermocouple probe was tucked in the sand
bath to check the temperature. The transducer of an ultrasonic
homogenizer (750 W) was immersed in the stainless steel
container.
[0053] This system was heated on a hot plate and the temperature
was gradually increased to the boiling point of xylene
(130-140.degree. C.) at which the polypropylene started to
dissolve.
[0054] The ultrasonic homogenizer was started for a set period of
time. The pulsation rate (i.e., the time for which the ultrasonic
is ON and OFF) and the amplitude of the ultrasonic waves were
pre-set before the start of ultrasonic action as indicated in Table
2 below. The temperature was maintained in the range of
130-140.degree. C. during the sonication time. In some cases, a
controlled amount of xylene was added during the homogenization
process to prevent the nanocomposite from solidifying. After this
homogenization process, the ultrasonic device was switched off and
the transducer was removed. The remaining xylene was allowed to
evaporate at its boiling temperature until the polymer
nanocomposite solidified.
[0055] Table 2 shows the detailed specifications of the
nanocomposites (owp stands for on weight (or by weight) of
polypropylene):
2TABLE 2 Composition of nanoclay polypropylene (PP) nanocomposites
Weight Ultra- of sonic Ampli- Sample Nanoclay Xylene (g), PP time
Pulse tude ID (g), % owp % owp (g) (min) (s) (%) PP0 -- 40 g, 500%
8 g 20 3 on 50% 5 off nanoPP1 0.4 g, 5% 40 g, 500% 8 g 7 3 on 50% 5
off nanoPP2 0.6 g, 20% 60 g, 2000% 3 g 15 3 on 70% 3 off nanoPP3
0.3 g, 2% 50 g, 500% 15 g 30 3 on 70% 3 off nanoPP4 0.75 g, 5% 50
g, 500% 15 g 30 3 on 70% 3 off nanoPP5 0.75 g, 5% 30 g, 200% 15 g
30 con- 70% tin- uous nanoPP6 1.50, 10% 75 g, 500% 15 g 15 3 on 70%
3 off
Example 2:
[0056] Dyeing the Nanoclay Polypropylene Nanocomposites
[0057] The nanoclay polypropylene nanocomposites prepared in
Example 1 were molded into films by using a hot laboratory press,
which was heated to the melting point of the nanoclay polypropylene
nanocomposites (i.e., 170.degree. C.), to obtain very fine, thin
layers of the polypropylene nanocomposites.
[0058] The nanoclay polypropylene nanocomposite films thus obtained
were dyed in an aqueous dye bath containing an acid dye C.I. Acid
Red 266, or an aqueous dye bath containing a disperse dye C.I.
Disperse Red 65.
[0059] Acid Dyeing
[0060] Aqueous dye baths containing 1, 2, and 4% by weight of C.I.
Acid Red 266 (i.e., 1, 2, and 4% depth of shade) were first
prepared. The pH of the dye bath was 3.5. For even dyeing, the dye
bath also contained an anionic leveling agent, Orco Nyasol Leveler
AA-50, at a concentration of 10 g/l.
[0061] Into each of these dye baths was added a polypropylene
nanocomposite film described above at a weight ratio of 1:20
(polymer nanocomposite: dye bath). The dyeing process was conducted
in Ahiba Polymat Laboratory dyeing machine.
[0062] The dye bath was heated in a sealed stainless steel dyeing
with a temperature increase from 30C. to 100.degree. C. at a rate
of 2.degree. C./minute. The temperature was then kept constant for
60 minutes. Finally the dye bath was cooled to 40.degree. C. The
samples were extracted and washed with cold running water for 5
minutes.
[0063] Disperse Dyeing
[0064] Aqueous dye baths containing 1, 2, and 4% (by weight) of
C.I. Disperse Red 65 were prepared. The dye baths had pH values
that were weakly acidic. The dye baths further contained, as
auxiliaries, 80% acetic acid at a concentration of 1 g/l, Irgasol
DAM (a dispersing agent) at a concentration of 2 g/l, and Albatex
FFC (a leveling agent) also at a concentration of 2 g/l.
[0065] The polypropylene nanocomposite films were placed into the
dye baths, also at a weight ratio of 1:20. The dyeing process was
conducted in an Ahiba Polymat Laboratory dyeing machine.
[0066] Dyeing was performed by raising the dye bath temperature
from 40 to 130.degree. C. at 1.5.degree. C./minute, holding at this
temperature for 45 minutes, and cooling to 60.degree. C. at
3.degree. C./minute. The dyed polymer nanocomposite films were
rinsed in running water for 5 minutes with hand agitation.
Reduction clearing was done by placing the dyed films for 10
minutes at 60-70.degree. C. in a solution containing 6 ml/l 30%
caustic soda and 4 g/l hydrosulfite at a weight ratio of
approximately 1:40 (dyed polymer nanocomposite:solution). The
samples were then rinsed for at least 5 minutes with cold
(15-25.degree. C.) running water. Finally, the dyed polypropylene
composite films were neutralized with 1.2 ml/l 99.9% acetic acid
for 2 minutes and then rinsed with cold (15-25.degree. C.) running
water for at least 5 minutes.
Examples 3:
[0067] Preparation of Silica Polypropylene Nanocomposites
[0068] An organo silica dispersed in methyl ethyl ketone (MEK)
(Nissan Chemical Industries, Ltd., Tarrytown, N.J.) was used to
prepare a silica polypropylene nanocomposite following the
procedure described in Example 1. Specifications of the silica and
the composition of the silica polypropylene nanocomposite are
listed below in Tables 3 and 4, respectively:
3TABLE 3 Physical properties of silica SiO.sub.2 Water Particle
size Viscosity Dispersant (wt %) (wt %) (nm) S. Grav. (mPa
.multidot. s) MEK 30 <0.6 10-20 0.98 <5
[0069]
4TABLE 4 Composition of PP nanocomposites Ultra- weight sonic
Ampli- weight of os xylene (g), of time Pulse tude Sample (g), %
owp % owp PP (g) (min) (s) (%) nanoPP6 1.50, 10% oc 75 g, 500% 15 g
15 3 on 70% 3 off nanoPP7 2.5, 5% oc 250 g, 500% 50 g 30 3 on 70% 3
off (owp = on weight (or by weight) of polypropylene; os = organo
silica-MEK)
Example 4:
[0070] Dyeing of Silica Polypropylene Nanocomposite
[0071] The silica polypropylene nanocomposite obtained from Example
3 was molded into film by using a hot laboratory press heated to
185.degree. C. A square template was placed between the jaws of the
press. For an even thickness, the films were removed when the
temperature of the press cooled down to 80.degree. C.
[0072] The silica polypropylene nanocomposite films thus obtained
were dyed in an aqueous dye bath containing an acid dye C.I.
Mordant Black 17, or an aqueous dye bath containing a disperse dye
C.I. Disperse Blue 102. The acid dye bath and the disperse dye bath
were of the same compositions and concentration as those described
in Example 2, except that the dyes were different.
Example 5:
[0073] Dyeing of Polypropylene Films
[0074] For comparison, films of virgin polypropylene (i.e.,
propylene without any modifications) were prepared and dyed
according to the procedures described in Example 1 and Example
2.
Example 6:
[0075] Washfastness Test
[0076] Color fastness is the resistance of the color of textiles to
the different agents and environments to which these materials may
be exposed during manufacture and their subsequent applications.
The dyed polypropylene nanocomposite films obtained in Examples 2
and 4, and the dyed polypropylene films obtained in Example 5, were
tested for their fastness against washing by the following
procedure:
[0077] A wash solution was first prepared by dissolving 4 g of
AATCC (the American Association of Textile Chemists and Colorists)
standard detergent WOB in 1 liter of distilled water. The dyed film
samples were then put into the test container and 50 ml of the
above washing solution was added. After the lid of the container
was secured, the Launder-ometer (Atlas Electric Devices, Co.,
Chicago, Ill.) was allowed to run for 30 minutes at 60.degree. C.
Upon completion, the dyed film samples were rinsed twice for 1
minute in water at 40.degree. C. The rinsed samples were subject to
visual, spectral, and microscopic (SEM) analysis.
[0078] The results show that dispersion of a nanomaterial into the
polypropylene increased its dyeability as compared to the virgin
polypropylene, which was not dyeable with an acid dye and was only
dyed to a very low extent with a disperse dye. Varying the quantity
of nanomaterials in the nanocomposites had a noticeable effect on
the exhaustion of the dye.
[0079] The results further show that nanocomposites containing
higher amounts of nanomaterials are dyed more evenly than those
containing lower amounts of nanomaterials. For instance, nanoPP1,
nanoPP4, and nanoPP5 (all of which were prepared with 5% add-on of
nanoclay) had improved color yield (i.e., more even dyeing) as
compared to nanoPP3 (which was prepared with 2% add-on of
nanoclay). The comparison of K/S (Kubelka-Munk coefficient) values
at 2% depth of shade indicates that nanoPP1 (5% nanoclay add-on)
had a slightly better color yield than nanoPP3 (2% nanoclay add-on)
when they were dyed with a disperse dye bath at 4% depth of shade.
NanoPP2 (20% nanoclay add-on) dyed with acid and disperse dye baths
also showed much more even dyeing than nanoPP3 and nanoPP4 (2% and
5% nanoclay add-ons, respectively).
[0080] A longer duration of ultrasonication also results in a more
even dye distribution. In the case of acid dyeing, a comparison
between dyed nanoPP1 (7 minutes) and dyed nanoPP4 (30 minutes)
showed that the dye had exhausted more on dyed nanoPP4 than
nanoPP1.
[0081] The nature of the build-up curves, among other factors, was
influenced by the chemical structure of the dye and the available
dye sites in the nanocomposites. The build-up curves were also
affected by the depth of shade (i.e., dye concentration) in the dye
bath. As shown in FIG. 1 and FIG. 2, there is an increase in the
color yield from 1 to 4% depth of shade except for nanoPP1 and
nanoPP5 where the curve is almost flat from 2 to 4% depth. This,
however, may be related to the unavailability of dye sites
(nanoclay) in proportion to the amount of dye in the dyebath. This
effect was observed in all the nanocomposite samples that were
disperse dyed. In other words, the disperse dye on polypropylene
nanocomposites reaches saturation at higher dye concentration.
However, high color yield on disperse dyed samples was observed
with increased concentration of dyes without a noticeable
difference between the dyed nanocomposites with varying amount of
nanoclay.
[0082] The results also indicate that dye exhaustion increased with
the increase of depths of shades of dye baths. As shown in FIGS.
3A-3D, 4A-4C, 5A-5D, and 6A-6D, the dye exhaustion increased with
the increase of the depths of shades in dye baths, i.e., 1% to 4%,
in all the tested nanocomposites.
Example 7:
[0083] Lightfastness Test The fabrics and polypropylene
nanocomposite films are cut into the dimension of 70.times.120 mm.
The specimens are then stapled on the white card and one part of
the sample is exposed (55.times.25 mm) which is called the 20-hour
sample. The white cards with the samples are mounted on the frames.
The fading apparatus is arranged by clamping one full (cored) and
another half (solid) carbon electrodes and enclosing them in a
glass bulb. A Fade-ometer (Atlas Electric Devices, Co., Chicago,
Ill.) is set to the operating conditions specified in the AATCC
Test Method 16-Option A. The specimen rack is filled with the
framed white cards and the required black thermometer unit. A
thermostat is used to maintain the chamber temperature to the test
specifications (63.degree. C.). The chamber drum is filled with
water to maintain the required value of humidity (30%). The timer
is adjusted and the machine is run for 20 hours after which it
stops automatically. The frames (with samples) are removed and the
exposed area is compared with the unexposed part of the sample. The
samples are evaluated according the AATCC Gray Scale Rating.
Example 8:
[0084] Dyeing Nanocomposites of Polyacrynitrile
[0085] Nanocomposites of polyacrylnitrile are prepared and dyed
according to the procedures described in Examples 1 and 2, except
that N,N-dimethylformamide (DMF) is used, instead of xylene.
OTHER EMBODIMENTS
[0086] It is to be understood that while the invention has been
described in conjunction with the detailed description thereof, the
foregoing description is intended to illustrate and not limit the
scope of the invention, which is defined by the scope of the
appended claims. Other aspects, advantages, and modifications are
within the scope of the following claims.
* * * * *