U.S. patent number 3,772,136 [Application Number 05/135,682] was granted by the patent office on 1973-11-13 for fibrous products from thermoplastic polyamide polymers.
This patent grant is currently assigned to General Mills, Inc.. Invention is credited to Clayton E. Workman.
United States Patent |
3,772,136 |
Workman |
November 13, 1973 |
FIBROUS PRODUCTS FROM THERMOPLASTIC POLYAMIDE POLYMERS
Abstract
An air pervious, water repellent, self-supporting fibrous mat is
produced by spraying a mixture of polyamide polymer and a suitable,
rapidly evaporating compatible solvent. The fibrous mats are
suitable for use as fabrics, decorative applications, tamper-proof
bottle sealers, packaging materials, etc.
Inventors: |
Workman; Clayton E.
(Minneapolis, MN) |
Assignee: |
General Mills, Inc.
(Minneapolis, MN)
|
Family
ID: |
22469175 |
Appl.
No.: |
05/135,682 |
Filed: |
April 20, 1971 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
741433 |
Jul 1, 1968 |
|
|
|
|
Current U.S.
Class: |
428/395; 156/251;
450/93; 521/98; 521/185; 156/62.2; 264/205; 521/78; 521/184;
602/45 |
Current CPC
Class: |
C08G
69/34 (20130101); D04H 1/56 (20130101); C08G
69/36 (20130101); Y10T 428/2969 (20150115); Y10T
156/1054 (20150115) |
Current International
Class: |
D04H
1/56 (20060101); C08G 69/34 (20060101); C08G
69/00 (20060101); C08G 69/36 (20060101); B32b
005/02 (); D04h 001/00 () |
Field of
Search: |
;156/62.2,62.4,62.6
;161/169 ;264/205,29N ;260/404.5,32.6N,18N ;117/21 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lesmes; George F.
Assistant Examiner: Thibodeau; Paul J.
Parent Case Text
This application is a continuation-in-part of my earlier filed
application Ser. No. 741,433, filed July 1, 1968 and now abandoned.
Claims
Now, therefore, I claim:
1. An air pervious and water repellent polyamide fibrous mat
comprised of fibers which are essentially non-uniform in thickness
and length and which have along their length a number of
non-uniform totally enclosed air pockets, said fibrous mat having
been prepared by spraying a solution of a polyamide dissolved in a
solvent having an evaporation rate of 5.5 or less onto a support at
a gage pressure in excess of 3 lb., said polyamide being selected
from the group consisting of (1) copolymers of self-condensed
aminolactams or aminoacids or mixtures thereof and the condensation
products of dicarboxylic acids and diamines and (2) polymers of the
condensation products of polymeric fat acids and diamines and said
fibrous mat being further characterized as being self-supporting
when released from a support backing therefor.
2. The fibrous mat of claim 1 wherein the polymeric fat acid is
polymerized tall oil fatty acid.
3. The fibrous mat of claim 2 wherein the polymeric fat acid has a
dimer acid content of at least 80 percent by weight.
4. The fibrous mat of claim 1 wherein the diamine has the formula
of H.sub.2 N-R'-NH.sub.2 wherein R' is an aliphatic, cycloaliphatic
or aromatic hydrocarbon radical of 2-40 carbon atoms.
5. The fibrous mat of claim 1 wherein the polyamide is selected
from the group consisting of
a. the reaction product of polymerized tall oil fatty acid and
hexamethylene diamine,
b. the reaction product of polymerized tall oil fatty acid and
4,4'-diamino-3,3'-dimethyl (dicyclohexyl) methane,
c. a copolymer of polymerized tall oil fatty acid, azelaic acid,
hexamethylenediamine, and ethylenediamine,
d. a copolymer of epsilon-caprolactam, adipic acid and
hexamethylenediamine, and sebacic acid and hexamethylenediamine,
and
e. a copolymer of epsilon-caprolactam, adipic acid and
hexamethylenediamine, sebacic acid and hexamethylenediamine, and
11-aminoundecanoic acid.
6. The fibrous mat of claim 1 wherein the polyamide solution
contains at least five percent by weight of dissolved
polyamide.
7. The fibrous mat of claim 6 wherein the solvent is a chlorinated
hydrocarbon solvent.
8. The fibrous mat of claim 7 wherein the solvent is methylene
chloride.
9. The fibrous mat of claim 7 wherein the solvent is
chloroform.
10. The fibrous mat of claim 7 wherein the solvent is methyl
chloroform.
11. The fibrous mat of claim 6 wherein the solvent is a mixture of
solvents.
12. The fibrous mat of claim 11 wherein the solvent is a mixture of
tetrahydrofuran containing up to 0.3 parts by weight of methanol
per part of tetrahydrofuran.
13. A process of forming a bonded article which comprises
simultaneously shearing at least two layers of the fibrous mat of
claim 1 while the layers are in contact.
Description
This invention relates to fibrous products prepared from
polyamides. More specifically, this invention relates to
self-supporting fibrous mats which are prepared by spraying a
mixture of polyamide polymer and a fast evaporating compatible
solvent.
It has been known that decorative web-like effects can be obtained
by spraying veiling lacquers with a spray gun. In the past, these
effects were obtained by spraying a formulated colored
nitrocellulose to a previously painted base coat of contrasting
color. Similar effects have been obtained with the use of synthetic
rubbers and polyvinylidene chloride. However, these earlier sprayed
effects were not self-supporting nor did they appear to be water
repellent and air pervious. Likewise, they did not offer the
advantages of the polyamides. These earlier applications were used
almost exclusively as veiling lacquers sprayed over a substrate to
produce decorative effects.
Turning to the drawings, it can be seen that FIGS. 1-5 are
photomicrographs of portions of a self-supporting fibrous mat
prepared in accordance with this invention.
FIG. 6 shows the fibrous mat bonded to a substrate.
FIG. 7 shows a raincoat made from the fibrous mat.
FIGS. 8 and 9 show a beverage can having the fibrous mat as a
sanitary covering.
FIGS. 10 and 11 show a bottle having a tamper-proof seal of sprayed
polyamide fibrous mat.
FIGS. 12-15 show the packaging of an object using two layers of the
fibrous mat.
It has now been found that thermoplastic polyamides when dissolved
in an appropriate solvent can be sprayed onto a substrate to
produce a web-like effect. This web-like effect will hereinafter be
referred to as a fibrous mat since the sprayed mat can be removed
for a release type substrate and be self-supporting. The fibrous
mat is comprised of fibers essentially non-uniform in thickness (or
diameter) and length, alternating between areas having a solid
cross-section with areas whose cross-section is tubular. The fibers
thus have along their length a number of non-uniform totally
enclosed gas pockets (i.e., bubbles). Various of the fibers are
interconnected (or bonded) to each other to form air holes in the
mat.
As used herein, the term "polyamide polymer" is intended to include
thermoplastic polyamide resins made by the condensation
polymerization of lactams and/or amino acids along with
dicarboxylic acids and diamines including conventional dicarboxylic
acids such as adipic acid, sebacic acid, etc. as well as the
polymerized fatty acids. Polyamide polymers as used herein is also
intended to include the thermoplastic polyamide resins prepared by
the condensation polymerization of diamines and polymerized fat
acids or polymerized fat acids in combination with conventional
dicarboxylic acids.
When practicing this invention, one of the preferred embodiments
includes the dissolution of a polyamide, which is the reaction
product of a polymerized fatty acid and diamine as defined herein,
in an appropriate, rapid evaporating solvent such as chloroform,
methylene chloride, etc. This mixture is then sprayed under
pressure, preferably at least 3 lb. gage pressure, from a
conventional spray gun. Generally, the resin concentration in the
solvent will be about 5 to 25 percent, preferably 15 to 20 percent
by weight of resin. However, the resin content will vary with the
type of spray equipment, solvent, application, and solubility of
the polyamide in the solvent. When the above mixture is sprayed, as
indicated, onto a substrate or a release type support such as
tetrafluoroethylene fluorocarbon resin Teflon coated glass cloth, a
fibrous mat can be formed. This mat will be air pervious and water
repellent. It will be evident to those skilled in the art that
optimum spraying conditions, i.e., pressure, nozzle selection, mat
thickness, etc. will be readily apparent through a few optimum
spray testing patterns.
A number of uses for the sprayed polyamide fibrous mat are
illustrated in the drawings. The photomicrograph, FIG. 1, is
approximately a 12X enlargement of a portion of the self-supporting
fibrous mat as prepared in Example I. It can be seen that the mat
has fibers, 1, and a number of small openings, 2, which will allow
for the passage of air. Since the fibers are hydrophobic, the mat
is water repellent.
FIGS. 2-5 are further photomicrographs of portions of the fibrous
mat as prepared in Example I (enlargements of 150X, 250X, 250X and
1,000X, respectively). It can be seen that the mats have fibers, 1,
openings, 2, bubbles within the fibers, 3, interconnected fibers,
4, and air holes, 5, formed by the interconnection of the fibers.
In the photomicrographs of FIGS. 2-5, 1 mm. equals 6.6, 4, 4, and 1
micron, respectively. Thus the large bubble, 3, of FIG. 4 has a
longest dimension of 286 microns, the diameter of the smallest
fiber, 1, of FIG. 5 is 1 micron and the diameter of the smallest
bubble, 3, of FIG. 5 is also 1 micron.
FIG. 6 shows the sprayed fibrous mat, 6, bonded to a substrate,
7.
FIG. 7 is a drawing of a raincoat prepared from cotton cloth, 8,
onto which was sprayed the fibrous mat, 9, prior to cutting and
sewing of the raincoat.
FIG. 8 shows a beverage can, 10, which has the fibrous mat, 11,
sprayed over the top of the can to give a sanitary covering. In
FIG. 9, the fibrous mat, 11, is partially peeled from the top of
the can.
FIG. 10 shows a bottle, 12, which has been made tamper-proof by
having the cap and bottle neck sprayed with the fibrous mat, 13.
FIG. 11 shows the cap removed from the bottle and the tamper-proof
seal broken, leaving jagged fibers, 14, wherever the seal has been
broken.
FIG. 12 shows an object, 15, placed between two layers of the
fibrous mat, 16. FIG. 13 shows the shearing by means of a scissors,
17, of both layers of the fibrous mat enclosing the object. FIG. 14
shows the object, 15, totally enclosed by the sheared fibrous mat
layers, 16, which are joined by the shearing action along their
outer edges. FIG. 15 is an end view along line 18-18 of the
packaged object showing that the fibrous layers have a bond, 19,
due to the shearing action.
As indicated above a variety of polyamide polymers are useful in
the present invention. These include the condensation products of
lactams and/or amino acids along with dicarboxylic acids and
diamines. Various of these products are readily commercially
available. They are normally defined by the weight percent content
of the condensates of their individual starting materials. Thus the
Elvamid resin used in Example XII is prepared by the condensation
polymerization of caprolactam, hexamethylene diamine, adipic acid
and sebacic acid with the resulting composition being defined as
follows:
% by weight nylon 6, (polycondensate of 46 caprolactam) nylon 6,6
(condensation of 27 hexamethylene diamine and adipic acid) nylon
6,10 (condensation of 27 hexamethylene diamine and sebacic
acid)
Likewise when 11-aminoundecanoic acid is used as a component, it is
identified as nylon 11 (i.e., the condensate of 11-aminoundecanoic
acid). These polyamides are prepared using known techniques which
include the use of heat to amide forming temperatures--i.e., above
about 100.degree. to 300.degree. C., such as
200.degree.-250.degree.C.
Suitable dicarboxylic acids have the general formula HOOC-R-COOH
where R is an aliphatic or cycloaliphatic radical having 3-48
carbon atoms. Simple dibasic acids include glutaric, pimelic,
adipic, sebacic, suberic, azelaic acid, etc. Diamines suitable in
preparing the polyamides useful in the present invention are also
illustrated hereinbelow following the description of the polymeric
fat acid based polyamides and the polymeric fat acid reactants.
Other suitable polyamides are the reaction products of diamines and
polymerized fatty acids or polymerized fatty acids in combination
with simple dibasic acids. The polymeric fat acids which may be
employed in preparing the polyamides are those resulting from the
polymerization of drying or semidrying oils or the free fat acids
or simple alcohol esters of these fat acids. The term "fat acids"
is intended to include saturated, ethylenically unsaturated and
acetylenically unsaturated, naturally occurring, and any synthetic
monobasic aliphatic acids containing from 16 to 24 carbon atoms.
The term "polymeric fat acid" refers to polymerized fat acids. The
term "polymeric fat radical" refers to the hydrocarbon radical of a
polymerized fat acid, and is generic to the divalent, trivalent,
and other polyvalent hydrocarbon radicals of dimerized fat acids,
trimerized fat acids and higher polymers of fat acids. The divalent
and trivalent hydrocarbon radicals are referred to herein as
"dimeric fat radical" and "trimeric fat radical" respectively.
The saturated, ethylenically unsaturated, and acetylenically
unsaturated fat acids are generally polymerized by somewhat
different techniques, but because of the functional similarity of
the polymerization product, they are generally referred to as
"polymeric fat acids."
Saturated fat acids are difficult to polymerize but polymerization
can be obtained at elevated temperatures with a peroxidic catalyst
such as ditertiarybutyl peroxide. Because of the generally low
yields of polymeric products, these materials are not current
commercially significant. Suitable saturated fat acids include
branched and straight acids such as caprylic acid, pelargonic acid,
capric acid, lauric acid, myristic acid, palmitic acid, isopalmitic
acid, stearic acid, arachidic acid, behenic acid, and lignoceric
acid.
The ethylenically unsaturated acids are much more readily
polymerized. Suitable polymerization methods are disclosed in U. S.
Pat. Nos. 3,256,304 and 3,157,681. The ethylenically unsaturated
acids can be polymerized using both catalytic or non-catalytic
polymerization techniques.
The preferred aliphatic acids are the mono- and polyolefinically
unsaturated 18 carbon atom acids. Representative of such acids are
4-octadecenoic, 5-octadecenoic, 6-octadecenoic (petroselinic),
7-octadecenoic, 8-octadecenoic, cis-9-octadecenoic (oleic),
trans-9-octadecenoic (elaidic), 11-octadecenoic (vaccenic),
12-octadecenoic and the like. Representative octadecadienoic acids
are 9,12-octadecadienoic (linoleic), 9,11-octadecadienoic,
10,12-octadecadienoic, 12,15-octadecadienoic and the like.
Representative octadecatrienoic acids are 9,12,15-octadecatrienoic
(linolenic), 6,9,12-octadecatrienoic, 9,11,13-octadecatrienoic
(eleostearic), 10,12,14-octadecatrienoic (pseudo-eleostearic) and
the like. A representative 18 carbon atom acid having more than
three double bonds is moroctic acid which is indicated to be
4,8,12,15-octadecatetraienoic acid. Representative of the less
preferred (not as readily available commercially) acids are:
7-hexadecenoic, 9-hexadecenoic (palmitoleic), 9-eicosenoic
(gadoleic), 11-eicosenoic, 6,10,14-hexadecatrienoic (hiragonic),
4,8,12,16-eicosatetraenoic, 4,8,12,15,18-eicosapentanoic
(timnodonic), 13-docosenoic (erucic), 11-docosenoic (cetoleic), and
the like.
The polymerization of the described ethylenically unsaturated acids
yields relatively complex products which usually contain a
predominant portion of dimerized acids, a smaller quantity of
trimerized and higher polymeric acids and some residual monomers.
The dimerized acids, generally containing 32 to 44 carbon atoms can
be obtained in reasonably high purity from the polymerization
products by vacuum distillation at low pressures, solvent
extraction, or other known separation procedures. It is preferred
to have a dimer acid content of at least 80 percent, more
preferably 90 percent. The polymerization product varies somewhat
depending on the starting fat acid or mixture thereof and the
polymerization technique employed--i.e., thermal, catalytic,
particular catalyst, conditions of pressure, temperature, etc.
Likewise, the nature of the dimerized acids separated from the
polymerization product also depends somewhat on these factors
although such acids are functionally similar.
As a practical matter, the dimeric fat acids are preferably
prepared by the polymerization of mixtures of acids (or the simple
aliphatic alcohol esters--i.e., methyl esters) derived from the
naturally occurring drying and semi-drying oils or similar
materials. Suitable drying or semi-drying oils include soybean,
linseed, tung, perilla, oiticia, cottonseed, corn, sunflower,
dehydrated caster oil and the like. Also, the most readily
available acid is linoleic or mixtures of the same with oleic,
linolenic and the like. Thus, it is preferred to use as the
starting materials, mixtures which are rich in linoleic acid. An
especially preferred material is the mixture of acids obtained from
tall oil which mixture is composed of approximately 40-45 percent
linoleic and 50-55 percent oleic.
Reference has been made hereinabove to the monomeric, dimeric and
trimeric fat acids present in the polymeric fat acids. The amounts
of monomeric fat acids, often referred to as monomer, dimeric fat
acids, often referred to as dimer, and trimeric or higher polymeric
fat acids, often referred to as trimer, present in polymeric fat
acids may be determined analytically by gas-liquid chromatography
of the corresponding methyl esters. Unless otherwise indicated
herein, this analytical method was used in the analysis of the
polymeric fat acids employed in this invention. Another method of
determination is a micromolecular distillation analytical method.
This method is that of R. F. Paschke et. al., J. Am. Oil Chem.
Soc., XXXI (No. 1), 5, (1954), wherein the distillation is carried
out under high vacuum (below 5 microns) and the monomeric fraction
is calculated from the weight of product distilling at 155.degree.
C., the dimeric fraction calculated from that distilling between
155.degree. and 250.degree. C., and the trimeric (or higher)
fraction is calculated based on the residue. When the gas-liquid
chromatography technique is employed, a portion intermediate
between monomeric fat acids and dimeric fat acids is seen, and is
termed herein merely as "intermediate", since the exact nature
thereof is not fully known. For this reason, the dimeric fat acid
value determined by this method is slightly lower than the value
determined by the micromolecular distillation method. Generally,
the monomeric fat acid content determined by the micromolecular
distillation method will be somewhat higher than that of the
chromatography method. Because of the difference of the two
methods, there will be some variation in the values of the contents
of various fat acid fractions. Unfortunately, there is no known
simple direct mathematical relationship correlating the value of
one technique with the other.
The polymeric fat acid based polyamides useful in the present
invention are prepared by conventional amidification procedures,
usually heating the reactants to a temperature between 100.degree.
and 300.degree. C., preferably 225.degree.-250.degree. C. for a
time sufficient to complete the reaction, generally 2-8 hours.
Essentially molar equivalent amounts of carboxyl and amine groups
are employed in preparing the polyamide. As set forth above, the
resins may also include copolymerizing diacids and the diamine
component employed may be a single diamine or a mixture of two or
more different diamine reactants. In addition, small amounts of
monomeric, monocarboxylic acids may be present. With regard to any
of the acid components, any of the equivalent amide-forming
deriatives thereof may be employed, such as the alkyl and aryl
esters, preferably alkyl esters having from 1-8 carbon atoms, the
anhydrides or the chlorides.
The diamines which may be employed may be ideally represented by
the formula
H.sub.2 N - R' - NH.sub.2
where R' is an aliphatic, cycloaliphatic or aromatic hydrocarbon
radical preferably having from two to 40 carbon atoms. Likewise, R'
may contain both aliphatic and aromatic hydrocarbon groupings.
Illustrative polyamines are ethylenediamine, hexamethylenediamine,
tetramethylenediamine, and the like, bis (aminoethyl)benzene,
cyclohexyl bis(methyl) amine), dimeric fat diamine, etc. And as
indicated previously the diamine may be employed alone or in
mixtures of two or more. The most preferred diamines are the
alkylene diamines having two- six carbon atoms in the alkylene
group and mixtures thereof with dimeric fat amines.
The dimeric fat diamine, sometimes referred to as "dimer diamine",
"dimeric fat amine" or "polymeric fat acid diamine" are the
diamines prepared by amination of dimeric fat acids. A suitable
method of preparation is disclosed in U. S. Pat. No. 3,010,782.
The copolymerizing compounds commonly employed are aliphatic,
cycloaliphatic or aromatic dicarboxylic acids or esters defined by
the formulae:
R.sub.1 OOC - COOR.sub.1 and R.sub.1 OOC-R"-COOR.sub.1
where R" is an aliphatic, cycloaliphatic or aromatic hydrocarbon
radical preferably having from one to 20 carbon atoms and R.sub.1
is hydrogen or an alkyl group, preferably having one to eight
carbon atoms. Such acids include oxalic, malonic, adipic, sebacic,
suberic and the like.
When copolymerizing dicarboxylic acids are employed with the
polymerized fat acids, it is preferred that the carboxyl groups
from the polymeric fat acid should account for at least 50
equivalent percent of the total carboxyl groups. Likewise, in those
polyamides as previously described prepared from an aminoacid
and/or a lactam with a dibasic acid and a diamine wherein dimeric
fat acid is included, it is preferred that the carboxyl groups from
the dimeric fat acid should account for at least 50 equivalent
percent of the total carboxyl groups.
As indicated previously, the polyamide is dissolved in a solvent
which is capable of rapidly evaporating and sprayed from the
solution to form a fibrous mat of the appearance shown in FIGS. 1
through 6. The solvents useful in this invention are those which
dissolve the polyamide resin and have an evaporation rate of less
than 5.5, preferably less than 3.0. The term "evaporation rate" as
used herein is defined as the ratio of time required for a given
volume of the solvent to evaporate at 73.5.+-.2.degree. F. and
50.+-.4 percent relative humidity when compared to the same volume
of diethyl ether which is assigned the value of one. A suitable
testing procedure is given in the Paint Industry Magazine, Vol. 76,
No. 4, p. 15, April 1961. To determined whether or not a solvent
would dissolve the polyamide, the mixture of solvent and polyamide
was placed in a conventional paint shaker for 1 hour of shaking. If
at the end of that time, the resulting mixture was not clear, the
system was determined to be incompatible. It has been found that
chlorinated hydrocarbon solvents with a suitable evaporation rate
work most satisfactorily. Solvents can generally be classified into
three categories; very useful solvents having an evaporation rate
of less than 3.0, operable solvents having an evaporation rate of
about 5.5-3.0, and unsuitable solvents having an evaporation rate
of above 5.5. Illustrative of evaporation rates of some
representative solvents are listed as follows:
Group Solvent Evaporation Rate Control Diethylether 1.0 I Methylene
chloride 1.8 Tetrahydrofuran 2.0 Chlororform 2.2 Methyl chloroform
(1,1,1,-trichloroethane) 2.7 II Methanol 5.2 III Ethanol 7.0
n-propanol 7.8
Various mixtures of solvents can be used so long as they fall
within the suitable evaporation rate. For instance, small amounts
of solvents which by themselves would be within Groups II or III
can be mixed with larger amounts of Group I and still have an
evaporation rate of less than 5.5. It is therefore possible to have
binary solvent systmes. Suitable mixtures include tetrahydrofuran
with small amounts of methanol, and fluoronated hydrocarbons
(Freon) and other commercial propellants with small amounts of
alcohols which induce solubility and have the desired evaporation
rate.
When spraying the polyamide resins from the solvent mixtures as
described above, it has been found that the viscosity can
significantly influence the type of web effect obtained. Generally,
the viscosity of the resin is a function of the molecular weight
and is the determinant of solution viscosity and product
performance. The following shows the relation of the spray solution
viscosity ranges:
Low viscosity--0.5-10.0 centipoises
Medium viscosity--10.0-65.0 centipoises
High viscosity--65.0-100.0 centipoises
Generally, a low viscosity, e.g., 0.5-10.0 cp., produces a finely
divided fibrous spray which is solvent saturated when airborne in
the spray. Since a large percentage of the atomized solvent is
carried to and deposited on the substrate, the short resin fibers
are partially redissolved giving a mat surface of unusual
continuity. Generally, it is necessary to obtain an optimum balance
between solids content of the solution, discharge rate and solvent
evaporation rate. It is also known that as the viscosity increases,
the solvent solution containing the resin becomes more difficult to
discharge and atomize and the resulting fibrous texture of the mat
eventually resembles a spattering of individual globules. Likewise,
the bulk density of the mat increases with an increase in solution
viscosity. Also, as is shown in the examples, the higher viscosity
resins result in greater tensile strength and better
elongation.
In order to use the fibrous mats as a decorative substance, it is
desirable to be able to obtain various colors. It has been found
that various colorants may be included in the solvent-resin mixture
prior to spraying. Generally, hydrocarbon dyes are preferred over
pigments. Suitable dyes include the Solvent series of dyes as
listed in the "Colour Index," Society of Dyers and Colourists, 2nd
Ed., 1956. Among the useful dyes are those having azo groups,
xanthene groups, anthraquinone and triarylmethane groups.
Illustrative are the following: Solvent Red 26, C.I. 26, 120:
Solvent Green 3, C.I. 61, 565: Solvent Orange 7, C.I. 12, 140
wherein C.I. is the color index.
Various methods of spray application have been found to work
satisfactorily. These include air gun spraying, aerosol spraying,
air brush, and other conventional methods of spray application. The
optimum spraying conditions can be easily obtained by simple spray
testing techniques. An important element for an aerosol application
is proper selection of the valve assembly. A useful nozzle is a
Model 103 Newman-Green spray head having a 0.055 inch slot and a
0.060 inch orifice and a vapor tap hole in the capillary dip tube
enlarged to 0.050 inch. Other methods of application will be
readily apparent to those skilled in the art.
The spraying is preferably accomplished using solution temperatures
of about 50.degree. to 100.degree. F., and even more preferably
ambient room temperatures--i.e., about 70.degree.-80.degree. F.
Also as indicated previously the spraying is carried out employing
at least 3 lb. gage pressure. The spraying pressure varies as to
the type of equipment, solution viscosity, etc. and the upper range
may be quite high--i.e., 100 lb. gage pressure and higher. A
preferred range is 35 to 45 lb. gage pressure. At any rate a
sufficient pressure is needed for the sprayed composition to reach
the receiving surface. Likewise, the distance of the latter from
the spray orifice can vary widely. Thus, such surface is
sufficiently far away from the orifice to allow the formation of
the fibrous pattern or mat. Solvent evaporation is also facilitated
by increased distance. Preferably, the receiving substrate will be
from about 1 to 3.5 feet from the spray orifice with a distance of
14 to 30 inches being especially preferred.
As mentioned previously, the polyamide fibrous mat may be
self-supporting or sprayed onto a support which will form part of
the final article. When a self-supporting mat is desired, it must
be formed on a material of the type that would release the mat.
Such supports include Teflon, polished plate glass, metals, wire
screens, or smooth surfaces containing conventional release
coatings. Likewise, the polyamide may be sprayed onto various other
substrates including paper, wood, metal, cotton, plastic film,
synthetic fibers, etc.
A slight modification of the invention may be practiced by
thermally treating the fibrous mat. If the polyamide is heated to a
temperature slightly less than that at which the mat continuity is
changed, the tensile strength and percent elongation are improved.
Generally, this temperature is different for each polymer but
common laboratory testing techniques will be readily apparent to
those skilled in the art. As shown in Example X, a suitable thermal
treating temperature for the resin of Example X is approximately
85.degree. C. It is also possible for the fibrous mat to serve as
an adhesive by heating the fibers to near or above the melting
point of the polymer. Various colored sections of the mat may thus
be attached to each other giving a checkerboard, decorative
effect.
The sprayed polyamide fibrous mat of this invention may be useful
as a textile material. For example, it has been found that the
fibrous mat may be sprayed onto a cloth substrate. FIG. 7 shows a
raincoat prepared from such material. Other uses include a coating
for bottle caps to give a tamper-proof seal, paneling, decorative
panels, creative art media, spary molded fabrics, wall covering,
lampshades, decorative packages and papers, surgical dressings,
protective covering for cans, water proofing agent, etc. The
fibrous mat may also be used to produce a cover for the tops of
wine bottles thus eliminating the need of a more expensive metal
cover. Additionally, the fibrous mats have insulative and
accoustical properties.
The fibrous mats of the invention also have the unique property of
forming a bond when two or more layers thereof are simultaneously
severed using a shearing action such as when cut employing a common
scissors. This property is illustrated by FIGS. 12-15 wherein an
object is packaged by placing same between two layers of the
fibrous mat and simultaneously severing the two layers on all sides
of the object. The bond strength is usually less than the strength
of the fibrous mat facilitating clean separation when desired at
the point or length of the said bond. Where the shearing apparatus
is heated above ambient room temperature such that the point of
contact thereof with the fibrous mat layers during the shearing is
above about 150.degree. F., the strength of the newly formed bond
between the two layers is increased. Decorative effects can be
achieved by utilizing different colored layers of the fibrous mat
with the simultaneous shearing being in a pattern, predetermined or
otherwise.
This invention is further illustrated by the following Examples
which are not to be considered as limiting.
EXAMPLE I
A polyamide was prepared from polymeric fat acids (polymerized tall
oil fatty acids) and hexamethylenediamine by charging 111.5 lbs. of
the polymeric fat acid into a flask along with 32.51 lbs. of
hexamethylenediamine. The polymeric fat acid had the following
properties:
Monomer--0.9 percent
Intermediate--4.6 percent
Dimer--93.4 percent
Trimer--1.0 percent
Acid Value--193
Saponification Value--196
Iodine Value--9.1
In addition to the above reactants, it is also possible to add an
antifoaming agent as well as a color remover such as a 10 percent
solution of phosphoric acid. In this example, 100 grams of the acid
and 10 grams of a commerically available antifoaming agent were
added to the reactants. The above reactants were heated to
250.degree. C. over a period of 2 hours and the temperature was
held at about 250.degree. C. for 3.25 hours. The resulting
polyamide had the following analysis:
Acid Value (meq./kg.)--7.6
Amine Value (meq./kg.)--35.8
Tensile Strength, psi--3,529
Yield Strength, psi--1,151
Percent Elongation--571
Melt Index at 175.degree. C.--19.66 gm.
The melt index was determined according to ASTM D-1238-65T. A 10
gram sample of the above polyamide resin was then mixed with 90
grams of chloroform. The mixture was shaken in a paint mixer until
a resulting clear solution was obtained, approximately 30
minutes.
The mixed solution was then charged to a type CM501 DeVilbiss spray
gun. The spray gun pressure was set at 50 lb.+ gaged pressure and
the mixture (at ambient temperature) was sprayed onto a Teflon
coated glass cloth approximately 20 inches from the spray orifice.
The evaporation rate of the solvent resulted in the polymer being
deposited on the cloth as a stringy, tacky solid. The tackiness
formed a continuity which renders a dry tissue-like film. The film
is in the form of a fibrous mat which can be readily separated from
the cloth and serves as a self-supporting fibrous mat. The fibrous
mat had a density approximately 75 percent of that of a solid
extruded film of the same polyamide.
EXAMPLE II
A polyamide polymer was prepared as follows with a polymeric fat
acid having the following analysis:
Monomer--1.6 percent
Intermediate--1.9 percent
Dimer--95.6 percent
Trimer--1.0 percent
Acid Value--191
Saponification Value--195
Iodine Value--8.9
The fat acid, in an amount of 125.0 pounds, was reacted with 52.5
pounds of 4,4'-diamino-3,3'-dimethyl(dicyclohexyl)methane.
The above reactants were heated to 250.degree. C. for 3 hours and
the temperature was maintained at 250.degree. C. for 1 hour. A
vacuum of 3 mm Hg was then applied and the temperature held at
250.degree. C. for 5 hours under vacuum.
The resulting polyamide resin had the following analysis:
Acid Value--13.3
Amine Value--44.4
Tensile Strength, psi--4,998
Yield Strength, psi--4,219
Percent Elongation--205
Inherent Viscosity--0.583
The inherent viscosity is the natural logarithm of the relative
viscosity divided by grams of the polyamide, generally 0.50 gm per
100 ml. of solvent, chlorophenol.
The spray procedure of Example I was repeated and similar results
were obtained.
EXAMPLE III
A polyamide was prepared as follows using a polymeric fat acid
having the following analysis:
Monomer--0.6 percent
Intermediate--4.3 percent
Dimer--92.5 percent
Trimer--2.6 percent
Acid Value--194
Saponification Value--196
Iodine Value--10.1
The fat acid, in an amount of 30 pounds, was reacted with the
following:
Azelaic acid--1.308 lbs.
Hexamethylenediamine--6.027 lbs.
Ethylenediamine--1.483 lbs.
The above reactants were heated to 250.degree. C. for 3 hours and
the temperature was maintained at 250.degree. C. for 1 hour. A
vacuum of 3 mm Hg was then applied and the temperature held at
250.degree. for 5 hours under vacuum.
The resulting polyamide resin had the following analysis:
Acid Value--1.3
Amine Value--2.1
Tensile Strength, psi--2,102
Yield Strength, psi--719
Percent Elongation--595
Brookfield viscosity at 225.degree. C.--317 poise
(No. 5 spindle at 4 rpm)
The spray procedure of Example I was repeated and similar results
were obtained.
EXAMPLE IV
Example I was repeated except that the solvent used for the
spraying application was methylene chloride. Results similar to
those of Example I were obtained.
EXAMPLE V
The following solution, Solution A, was prepared:
Polyamide from Ex. I--170 gms.
Dichloromethane--600 gms.
Tetrahydrofuran--220 gms.
Methanol--10 gms.
Gardner Viscosity at 25.degree. C.--32 cps
The ingredients to prepare Solution A were placed in a paint shaker
for 1 hour. Due to heat and pressure generated from the shaking, it
was necessary to cool the mixing container and contents to room
temperature before opening.
After cooling the above mixture, three 98.0 gram samples were
withdrawn and placed into four 6 oz. glass jars. A separate 2 gm.
10 percent dye solution was placed into each glass jar and the
respective dyes and Solution A were mixed on the paint shaker for
15 minutes. The three dyes were as follows:
Solvent Red 26, Color Index 26120
Solvent Green 3, Color Index 61565
Solvent Orange 7, Color Index 12140
Each of the three mixtures were sprayed at 40 lb. gage pressure
with the spray gun as in Ex. I, onto a separate piece of Kraft
wrapping paper. A decorative, artistic, colored, fibrous mat was
obtained which remained adhered to the paper.
EXAMPLE VI
A tamper-proof container was prepared by first preparing the
following spray solution:
Polyamide Resin of Ex. I--15 gms.
Dichloromethane--25 gms.
Tetrahydrofuran--60 gms.
Methanol--1 gm.
Gardner Viscosity--32 cps
The above ingredients were shaken in a paint shaker until a clear
solution resulted, the solution was sprayed around the cap of a
one-ounce bottle. The solution was sprayed with a Model H, Paasche
Airbrush at 25-40 psig. A tamper-proof seal was obtained similar to
that shown in FIG. 10. The seal can be easily broken but cannot be
resealed by melting, heating or by other means without a complete
re-spraying.
EXAMPLE VII
The following spray solution was prepared:
Polyamide Resin of Ex. I--17 gms.
Dichloromethane--60 gms.
Tetrahydrofuran--22 gms.
Methanol--1 gm.
Gardner Viscosity--32 cps
The spray solution was prepared in in Ex. VI and sprayed with an
air gun as in Example I. The spray solution was applied to the top
of a beverage can to form a sanitary covering as shown in FIG. 8.
The covering was easily removed without the use of a release
agent.
The same formula was used to spray a paper except that TiO.sub.2 in
an amount of 10 percent of the weight of the total solution was
added for a white base. A decorative paper was thus obtained.
The spray solution of this Example was applied directly to a molded
lampshade to give a fibrous mat effect to the lampshade.
The spray solution was also applied to a brassiere form in which
the cups were formed from filament-spray, fibrous mat. The straps
and fastenings were of conventional construction.
EXAMPLE VIII
A piece of highly sized cotton material of the type commercially
available in a yard goods store was sprayed with the polyamide
solution of Example VII. The spray solution was applied with an air
gun as in Example I. Coverage of the spray was such that 114 grams
of the dryed sprayed solution covered 2 square yards of the fabric.
The sprayed cotton fabric was then cut and made into a raincoat as
shown in FIG. 7. The raincoat was water repellent.
EXAMPLE IX
The following Example will illustrate the relative tensile
strengths and percent elongation of the fibrous mat for various
viscosity polymers. The polyamide resin used was that of Example I
except that the viscosity for the three samples was varied as
indicated below. The spray solution was prepared as indicated in
the Table below. Each solution was prepared by weighing 100 gram
samples into a 6 ounce glass jar, tightly sealed, and then placed
in a paint shaker for 1 hour. The solutions were then sprayed onto
Teflon coated glass cloth with the spray gun as used in Example I.
The pressure was set at 35 psig and the spray gun was held
approximately 20 inches from the substrate and a spraying stroke of
about 18 inches used to apply the solution. All of the sample was
sprayed onto the substrate. The mat was removed from the substrate
and cut into strips 1 inch .times. 3 inch. The cut strips were then
weighed amd the mat weight determined in gram/sq. in. To determine
the tensile strength, the strips were placed between the jaws of an
Instron Tester, Model TM, Instron Eng. Corp., Canton, Mass. The
strips were placed so as to have exactly 1 inch of mat between the
jaws, i.e., a jaw gap of 1 inch. The tester was set at a crosshead
speed of 0.5 inch/min. The tensile strength is defined as the
maximum load in grams for failure of the mat per mat weight in
grams/area, i.e., gm/in.sup.2. Therefore, the tensile strength will
have the units gms/gm/in.sup.2. The elongation becomes a direct
reading of the distance of travel. The results are summarized in
Tables I and II below. The mat weights marked with an asterisk
indicates that 50 gram samples were sprayed rather than 100 gram
samples.
TABLE I
Resin A B C Resin Viscosity (Brookfield 250 p 180 p No. 5 spindle,
4 rpm, 205.degree.C.) Melt INdex at 175.degree.F. 19.66 gm. Resin
Amt. (gms.) 15 15 10 Dichloromethane (gms.) 60 60 60 Methanol
(gms.) 1 1 1 Tetrahydrofuran (gms.) 24 24 29 Gardner Viscosity, of
the solvent mixture -- 25.degree.C., cps 22 14.4 14.4
TABLE II
Mat Wt. Tensile Strength Resin gm/in.sup.2 gm/gm/in.sup.2 %
Elongation A 0.06* 1258 16.0 B 0.06* 1647 20.0 C 0.05* 2356 33.0 A
0.16 2220 40.0 B 0.16 2025 35.0 C 0.13 3179 90.0
example x
resin B of Example IX was tested to determine the effect of
thermally treating the sprayed fibrous mat. The sprayed fibrous mat
comprised of Resin B in Example IX was cut into 1 inch .times. 3
inche pieces and each piece weighed. The samples were then
subjected to thermal treating by heating the samples to 50.degree.
C., 75.degree. C., 80.degree. C., and 85.degree. C. respectively
for 1 hour at the various temperatures. The effect on the tensile
strength and percent elongation is summarized in Table III. It was
found that the fibrous mat was generally destroyed at 90.degree. C.
or above.
TABLE III
Sample Sample Tensile Strength Elongation .degree.C. Wt. gms
gm/gm/in.sup.2 % Control 0.2060 1100 27 50.degree.C. 0.2035 1073 19
75.degree.C. 0.2045 1214 16 80.degree.C 0.2030 1379 26 85.degree.
0.2055 1281 35
it can been seen that generally heat treatment increases the
tensile strength.
EXAMPLE XI
The following spray solution was prepared for aerosol
application:
Polyamide Resin, Ex. I--18.0 gms.
Dichloromethane--40.0 gms.
Tetrahydrofuran--27.0 gms.
Methanol--15.0 gms.
Gardner Viscosity of the
solvent mixture at 25.degree. C.--32.1 cps
This solution was prepared by charging the materials into a 6 ounce
glass jar and placed in a paint shaker for 1 hour. A 60 gram sample
of the solution was weighed into a standard 10 ounce tinplate
aerosol container. The container was sealed with a Newman-Green
valve having the following description: Model R-70-118, with a
0.030 inch capillary tubing, Epon (B 5.0) and a 0.060 inch vapor
tap hole, 70 Durometer Buna gasket and a stainless steel spring.
The container was injection filled with 40 grams of
dichlorodifluoromethane (Freon-12) which pressurized the container
to 40 psig. The spray head was a Model 103 Newman-Green sprayhead
having a 0.055 inch slot and a 0.060 inch orifice. The solution was
sprayed onto a paper substrate and a fibrous mat was formed on the
substrate.
EXAMPLE XII
The following nylon copolymer spray solution was prepared:
Nylon copolymer resin*--10 gms.
Dichloromethane--45 gms.
Tetrahydrofuran--10 gms.
Methanol--40 gms.
Gardner Viscosity at 25.degree. C.--32.1 cps
The nylon copolymer was a commercially available nylon resin having
the following composition:
nylon 6 (polycondensate of caprolactam)--46 percent
nylon 6,6 (condensation of hexamethylenediamine and adipic
acid)--27 percent
nylon 6,10 (condensation of hexamethylenediamine and sebacic
acid)--27 percent
The spary solution was prepared in a paint shaker as in Example I
and sprayed onto a tetrafluoroethylene coated glass cloth support.
Results were similar to those of Example I.
EXAMPLE XIII
Example XII was repeated except that the following solution was
prepared:
Nylon copolymer resin--12.5 gms.
Dichloromethane--40.0 gms.
Tetrahydrofuran--10.0 gms.
Methanol--37.5 gms.
Gardner Viscosity at 25.degree. C.--85 cps
The nylon copolymer resin of this example was
nylon 6-- 50 percent
nylon 6,6--20 percent
nylon 6,10--20 percent
nylon 11 (made from
11-aminoundecanoic acid)--10 percent
Results similar to Example XII were obtained.
EXAMPLE XIV
Self-supported fibrous mats as prepared in Example I were tested
for the formation of bonds by laying two 1 inch by 3 inch strips
face to face and then severing the same by cutting across the width
of one end of the two layers (approximately 1 inch from the end)
using a scissors, either at ambient temperature (77.degree. F.) or
at 160.degree. F. (the scissors were heated by soft soldering a 1/4
inch by 4 inch, 100 watt cartridge heater to each blade using a
powerstat regulated to produce a line voltage of 25-28 volts). The
cutting produced in each instance two bonded strips having lengths
of approximately 2 and 4 inches (half of the length being
contributed by each layer). The bond strength was measured using an
Instron Tensile instrument at a crosshead speed of 0.5 inches/min.
and a gap space between the positioning jaws of 1 inch. The
strength of the bond formed using the scissors at room temperature
was 217 grams (load at failure). The 160.degree. F. heated scissors
bond had a strength of 353 grams (load at failure).
This invention offers a very economical self-supporting or
supported fibrous mat which has multiple uses including textile
materials, decorative uses, and any other number of applications
which will be readily apparent to those skilled in the art. Since
the mats are extremely drapable, they will be useful in many types
of complex applications.
* * * * *