U.S. patent application number 12/377836 was filed with the patent office on 2010-09-16 for aqueous dispersion of polyamide rubber elastic body and method of producing the same.
Invention is credited to Hirofumi Fujita, Jun Sakata, Norihiro Sugihara.
Application Number | 20100234499 12/377836 |
Document ID | / |
Family ID | 39082047 |
Filed Date | 2010-09-16 |
United States Patent
Application |
20100234499 |
Kind Code |
A1 |
Sugihara; Norihiro ; et
al. |
September 16, 2010 |
AQUEOUS DISPERSION OF POLYAMIDE RUBBER ELASTIC BODY AND METHOD OF
PRODUCING THE SAME
Abstract
An aqueous dispersion of polyamide rubber elastic body, which
contains an aqueous medium and a polyamide rubber elastic body
emulsified and dispersed in the aqueous medium in the presence of a
surfactant. The surfactant is used in an amount of 1 to 20 parts by
weight based on 100 parts by weight of the polyamide rubber elastic
body, and is for example at least one member selected from the
group consisting of a polyoxyalkylene alkyl ether sulfate, a
dialkyl sulfosuccinate, a fatty acid salt and an ethylene
oxide/propylene oxide copolymer. This aqueous dispersion can
produce a molded article having the characteristics of the
polyamide rubber elastic body, particularly a molded article which
hardly suffers from bleeding of the surfactant and is excellent in
transparency.
Inventors: |
Sugihara; Norihiro; (Hyogo,
JP) ; Sakata; Jun; (Hyogo, JP) ; Fujita;
Hirofumi; (Hyogo, JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Family ID: |
39082047 |
Appl. No.: |
12/377836 |
Filed: |
July 10, 2007 |
PCT Filed: |
July 10, 2007 |
PCT NO: |
PCT/JP2007/064053 |
371 Date: |
February 17, 2009 |
Current U.S.
Class: |
524/156 ;
524/282; 524/538; 524/608; 524/81 |
Current CPC
Class: |
C08G 69/40 20130101;
C08J 2377/12 20130101; C08L 77/06 20130101; C08L 77/12 20130101;
C08J 3/05 20130101 |
Class at
Publication: |
524/156 ; 524/81;
524/282; 524/538; 524/608 |
International
Class: |
C08K 5/41 20060101
C08K005/41; C08K 5/101 20060101 C08K005/101; C08L 77/00 20060101
C08L077/00; C08G 69/48 20060101 C08G069/48 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 18, 2006 |
JP |
2006-222926 |
Claims
1. An aqueous dispersion of polyamide rubber elastic body,
comprising: an aqueous medium, and a polyamide rubber elastic body
emulsified and dispersed in the aqueous medium in the presence of a
surfactant, wherein the surfactant is used in an amount of 1 to 20
parts by weight based on 100 parts by weight of the polyamide
rubber elastic body.
2. The aqueous dispersion of polyamide rubber elastic body
according to claim 1, wherein the polyamide rubber elastic body is
one of copolymers among a polyether block amide copolymer and a
polyether ester block amide copolymer.
3. The aqueous dispersion of polyamide rubber elastic body
according to claim 1, wherein the surfactant is at least one member
selected from the group consisting of a polyoxyalkylene alkyl ether
sulfate, a dialkyl sulfosuccinate, a fatty acid salt and an
ethylene oxide/propylene oxide copolymer.
4. The aqueous dispersion of polyamide rubber elastic body
according to claim 1, further comprising a polymeric dispersion
stabilizer.
5. The aqueous dispersion of polyamide rubber elastic body
according to claim 1, wherein the average particle diameter of
particles of the emulsified and dispersed polyamide rubber elastic
body is 0.1 to 5 .mu.m.
6. A molded article of polyamide rubber elastic body obtained from
an aqueous dispersion of polyamide rubber elastic body comprising
an aqueous medium and a polyamide rubber elastic body emulsified
and dispersed in the aqueous medium in the presence of a
surfactant, wherein the surfactant is used in an amount of 1 to 20
parts by weight based on 100 parts by weight of the polyamide
rubber elastic body.
7. A method of producing an aqueous dispersion of polyamide rubber
elastic body, comprising the steps of: mixing an organic phase
containing a polyamide rubber elastic body dissolved in an organic
solvent, with an aqueous phase containing a surfactant dissolved in
an aqueous medium, to prepare an emulsion, and distilling the
organic solvent off from the emulsion, wherein the surfactant is
used in an amount of 1 to 20 parts by weight based on 100 parts by
weight of the polyamide rubber elastic body.
8. The method of producing the aqueous dispersion of polyamide
rubber elastic body according to claim 7, wherein the organic
solvent is a mixture of an aromatic hydrocarbon solvent or an
alicyclic hydrocarbon solvent and an alcohol solvent.
9. The method of producing the aqueous dispersion of polyamide
rubber elastic body according to claim 7, wherein the aqueous phase
comprises a polymeric dispersion stabilizer.
10. A method of producing an aqueous dispersion of polyamide rubber
elastic body, comprising the steps of: preparing a mixture
containing a polyamide rubber elastic body, a surfactant and an
aqueous medium, and emulsifying the mixture at a temperature not
lower than the softening temperature of the polyamide rubber
elastic body, wherein the surfactant is used in an amount of 1 to
20 parts by weight based on 100 parts by weight of the polyamide
rubber elastic body.
Description
TECHNICAL FIELD
[0001] The present invention relates to an aqueous dispersion of
rubber elastic body and a method of producing the same and in
particular to an aqueous dispersion of polyamide rubber elastic
body and a method of producing the same.
BACKGROUND ART
[0002] A polymeric rubber elastic body essentially has either a
soft polymer structure or a structure consisting of a rigid polymer
system combined with a soft polymer system, and is used in a wide
variety of industrial fields because it has rubber elasticity at
ordinary temperatures and it can be mechanically molded due to its
plasticization at high temperatures similar to thermoplastics.
Typical polymeric rubber elastic bodies include those based on
styrene, olefin, polyester, polyurethane, polyvinyl chloride, and
polyamide. These polymeric rubber elastic bodies are usually
provided as molded articles produced by mechanical operation such
as extrusion molding, and when used in coating agents for various
materials, adhesives, binders, modifiers such as emulsions, or
binders for fibers, the polymeric rubber elastic bodies are used
desirably in the form of aqueous dispersions.
[0003] Aqueous dispersions of polymeric rubber elastic bodies have
been extensively examined, among which an aqueous dispersion of a
styrene rubber elastic body has been provided as a practical
product. The aqueous dispersion of a styrene rubber elastic body is
produced usually by mixing an organic phase containing a styrene
rubber elastic body dissolved in an organic solvent, with an
aqueous phase containing an emulsifier (surfactant) dissolved in an
aqueous medium, and emulsifying the mixture with a homomixer or the
like, followed by removing the organic solvent (see, for example,
JP 51-23532 A and JP 2003-253134 A).
[0004] However, molded articles obtained from the aqueous
dispersion of a styrene rubber elastic body are generally inferior
in abrasion resistance, flex resistance, oil resistance, and
weather resistance. A polyamide rubber elastic body, on the other
hand, can produce molded articles not only excellent in these
properties but also excellent in transparency, flexibility, impact
strength, tensile strength, chemical resistance, and heat
resistance, and further has an advantage that its molded articles
can be made thin-walled because it has higher stress upon
deformation than other polymeric rubber elastic bodies of the same
rigidity, and is thus useful for example as a material for
producing packaging films, automobile parts, sporting goods, and
medical devices. Accordingly, an aqueous dispersion of polyamide
rubber elastic body has been desired to be realized as there has
been no example of practical application thereof.
[0005] An object of the present invention is to realize an aqueous
dispersion of polyamide rubber elastic body capable of producing a
molded article having the characteristics of the polyamide rubber
elastic body, particularly a molded article which hardly suffers
from bleeding of a surfactant and is excellent in transparency.
DISCLOSURE OF THE INVENTION
[0006] An aqueous dispersion of polyamide rubber elastic body
according to the present invention contains an aqueous medium and a
polyamide rubber elastic body emulsified and dispersed in the
aqueous medium in the presence of a surfactant. In the aqueous
dispersion, the surfactant is used in an amount of 1 to 20 parts by
weight based on 100 parts by weight of the polyamide rubber elastic
body.
[0007] The polyamide rubber elastic body used in this aqueous
dispersion is, for example, one of copolymers among a polyether
block amide copolymer and a polyether ester block amide copolymer.
The surfactant used in this aqueous dispersion is, for example, at
least one member selected from the group consisting of a
polyoxyalkylene alkyl ether sulfate, a dialkyl sulfosuccinate, a
fatty acid salt and an ethylene oxide/propylene oxide copolymer.
This aqueous dispersion may further contain a polymeric dispersion
stabilizer. The average particle diameter of particles of the
polyamide rubber elastic body emulsified and dispersed in this
aqueous dispersion is usually 0.1 to 5 .mu.m.
[0008] As the amount of the surfactant in the aqueous dispersion of
polyamide rubber elastic body is controlled relative to the
polyamide rubber elastic body, the aqueous dispersion can produce a
molded article having the characteristics of the polyamide rubber
elastic body, particularly a molded article which hardly suffers
from bleeding of the surfactant and is excellent in
transparency.
[0009] The molded article of the polyamide rubber elastic body
according to the present invention is obtained from the aqueous
dispersion of polyamide rubber elastic body according to the
present invention.
[0010] The method of producing an aqueous dispersion of polyamide
rubber elastic body according to the present invention includes the
steps of mixing an organic phase containing a polyamide rubber
elastic body dissolved in an organic solvent, with an aqueous phase
containing a surfactant dissolved in an aqueous medium, to
preparing an emulsion, and distilling the organic solvent off from
the emulsion. In this method, the surfactant is used in an amount
of 1 to 20 parts by weight based on 100 parts by weight of the
polyamide rubber elastic body.
[0011] The organic solvent used herein is usually a mixture of an
aromatic hydrocarbon solvent or an alicyclic hydrocarbon solvent
and an alcohol solvent. The aqueous phase used in this production
method contains, for example, a polymeric dispersion
stabilizer.
[0012] The method of producing an aqueous dispersion of polyamide
rubber elastic body according to another embodiment of the present
invention includes the steps of preparing a mixture containing a
polyamide rubber elastic body, a surfactant and an aqueous medium,
and emulsifying the mixture at a temperature not lower than the
softening temperature of the polyamide rubber elastic body. In this
method, the surfactant is used in an amount of 1 to 20 parts by
weight based on 100 parts by weight of the polyamide rubber elastic
body.
[0013] Other objects and results of the present invention are
referred to in the following detailed description.
BEST MODE FOR CARRYING OUT THE INVENTION
[0014] An aqueous dispersion of polyamide rubber elastic body
according to the present invention contains an aqueous medium and a
polyamide rubber elastic body emulsified and dispersed in the
aqueous medium in the presence of a surfactant.
[0015] The aqueous medium used in the present invention is
essentially water. This water may be various kinds of water such as
tap water, industrial water, ion exchanged water, deionized water
and pure water, among which pure water is preferable. This water
may be appropriately compounded as necessary with a pH adjuster, a
defoaming agent, a viscosity modifier, an antifungal agent and an
antioxidant as long as the object of the present invention is not
hindered.
[0016] The polyamide rubber elastic body used in the present
invention, though not particularly limited, has for example a
structure wherein a rigid polymer system having a crystalline
polyamide block with a high melting point is combined with a soft
polymer system having a noncrystalline polyether block with a low
glass transition temperature. Constituent components of the
polyamide block possessed by the rigid polymer system include, for
example, lactam compounds such as caprolactam, capryllactam,
enantholactam and laurolactam, aminocarboxylic acid compounds such
as .omega.-aminocaproic acid, .omega.-aminoenanthic acid,
c.omega.-aminocaprylic acid, c.omega.-aminoperconic acid,
c.omega.-aminocapric acid and 11-aminoundecanoic acid, or salts
between a diamine compound such as ethylene diamine, triethylene
diamine, tetraethylene diamine or hexamethylene diamine and a
dicarboxylic acid compound such as oxalic acid, succinic acid,
glutaric acid, adipic acid, pimelic acid, sebacic acid,
terephthalic acid or isophthalic acid. Two or more of these
constituent parts may be used. Constituent components of the
polyether block possessed by the soft polymer system include, for
example, glycol compounds such as polyethylene oxide glycol,
polypropylene oxide glycol, polytetramethylene oxide glycol and
polyhexamethylene oxide glycol, and diamine compounds such as
polyether diamine. Two or more of these constituent parts may be
used.
[0017] Specific examples of the polyamide rubber elastic body as
described above include several types of elastic bodies different
in the molecular structure of a binding portion, that is, the
binding form between the polyamide block and the polyether block,
for example, a polyether block amide copolymer having a binding
form "(polyamide block) --CO--NH-- (polyether block)" and a
polyether ester block amide copolymer having a binding form
"(polyamide block) --CO--O-- (polyether block)".
[0018] The polyamide rubber elastic body used may be a commercial
one or a suitably produced one. The method of producing the
polyamide rubber elastic body includes, for example, a method
wherein at least one compound selected from a lactam compound, an
aminocarboxylic acid compound and a diamine compound is reacted
with a dicarboxylic acid to prepare a polyamide block, both the
terminals of which are substantially carboxyl groups, followed by
adding to this polyamide block a glycol compound such as
polyethylene oxide glycol or a diamine compound such as polyether
diamine and then heating the mixture.
[0019] Examples of the surfactant used in the present invention
include, but are not limited to, an anionic surfactant and a
nonionic surfactant.
[0020] Examples of the anionic surfactant include a polyoxyalkylene
alkyl ether sulfate, a polyoxyalkylene alkyl phenyl ether sulfate,
an alkylbenzene sulfonate, an alkyl naphthalene sulfonate, an alkyl
diphenyl sulfonate, an .alpha.-olefin sulfonate, an alkyl sulfate,
a naphthalene sulfonate-formalin condensate, a dialkyl
sulfosuccinate, a polyoxyethylene alkyl ether acetate, a rosin acid
salt and a fatty acid salt. Among them, a polyoxyalkylene alkyl
ether sulfate, a dialkyl sulfosuccinate and a fatty acid salt are
preferable from the viewpoint of excellent emulsion dispersibility
and stability and of easy availability at low cost.
[0021] The polyoxyalkylene alkyl ether sulfate is a compound
represented by the following general formula (1):
R.sup.1/(AO).sub.nSO.sub.3X (1)
wherein X represents a sodium atom, a potassium atom, an amino
group or an ammonium group, R.sup.1 represents an alkyl or alkenyl
group having 5 to 24 carbon atoms, n is an integer of 2 to 50
indicative of the number of moles of AO added per molecule, and
(AO).sub.n is an atomic group represented by the following formula
(1-a):
(C.sub.2H.sub.4O).sub.h(C.sub.3H.sub.6O).sub.k (1-a)
wherein h and k each represent an integer of 0 to 50, and the sum
of h and k is n defined above. When both of h and k are not 0, the
order of the ethylene oxide unit ((C.sub.2H.sub.4O)) and the
propylene oxide unit ((C.sub.3H.sub.6O)) in the sequence is not
limited, and therefore (AO).sub.n can include the units in the form
of block or random.
[0022] Specific examples of the polyoxyalkylene alkyl ether sulfate
include polyoxyalkylene lauryl ether sulfates and polyoxyalkylene
oleyl ether sulfates. More specifically, the polyoxyalkylene lauryl
ether sulfates can be exemplified by sodium polyoxyalkylene lauryl
ether sulfates such as sodium polyoxyethylene lauryl ether sulfate
and sodium polyoxypropylene lauryl ether sulfate and ammonium
polyoxyalkylene lauryl ether sulfates such as ammonium
polyoxyethylene lauryl ether sulfate. The polyoxyalkylene oleyl
ether sulfates include sodium polyoxyalkylene oleyl ether sulfates
such as sodium polyoxyethylene oleyl ether sulfate and sodium
polyoxypropylene oleyl ether sulfate and ammonium polyoxyalkylene
oleyl ether sulfates such as ammonium polyoxyethylene oleyl ether
sulfate. Among them, polyoxyalkylene lauryl ether sulfates,
particularly sodium polyoxyalkylene lauryl ether sulfates are
preferable, and sodium polyoxyethylene lauryl ether sulfate is
particularly preferable.
[0023] The dialkyl sulfosuccinate is a compound represented by the
following general formula (2):
YO.sub.3SCH(CH.sub.2COOR.sup.2)COOR.sup.3 (2)
wherein Y represents a sodium atom, a potassium atom, an amino
group or an ammonium group, R.sup.2 and R.sup.3 each represent an
alkyl or phenyl group having 5 to 12 carbon atoms and may be the
same or different.
[0024] Specific examples of the dialkyl sulfosuccinate include
dioctyl sulfosuccinate, diethylhexyl sulfosuccinate, dialkylphenyl
sulfosuccinate and didodecyl sulfosuccinate. Among them,
dioctylsulfosuccinate is particularly preferable.
[0025] The fatty acid salt is a compound represented by the
following general formula (3):
R.sup.4COOM (3)
wherein R.sup.4 represents an alkyl or alkenyl group having 5 to 24
carbon atoms, and M represents a sodium atom, a potassium atom, an
amino group or an ammonium group.
[0026] Specific examples of the fatty acid salt include oleates,
stearates, laurates, myristates and palmitates. Among them, oleates
are preferable.
[0027] Examples of the nonionic surfactant include polyethylene
glycol, an ethylene oxide/propylene oxide copolymer, a
polyoxyethylene alkyl ether, a polyoxyethylene alkyl phenyl ether,
a polyoxyethylene alkyl thioether, a polyoxyethylene sorbitan fatty
acid monoester, a polyoxyethylene alkyl amide, and a polyglycerin
ester. Preferable among them are polyethylene glycol, an ethylene
oxide/propylene oxide copolymer, a polyoxyethylene alkyl ether, a
polyoxyethylene alkyl phenyl ether and a polyoxyethylene sorbitan
fatty acid monoester, among which an ethylene oxide/propylene oxide
copolymer is particularly preferable from the viewpoint of
excellent emulsion dispersibility and heat resistance.
[0028] The ethylene oxide/propylene oxide copolymer is a compound
represented by the following general formula (4):
HO(CH.sub.2CH.sub.2O).sub.p(CH.sub.2CH(CH.sub.3)O).sub.q(CH.sub.2CH.sub.-
2O).sub.rH (4)
wherein p, q and r each represent the number of moles of the
corresponding unit added per molecule and may be the same or
different. Here, p is an integer of 2 to 300, q is an integer of 10
to 150, and r is an integer of 2 to 300.
[0029] The weight-average molecular weight of the ethylene
oxide/propylene oxide copolymer, although not particularly
restricted, is preferably 3,000 to 30,000, more preferably 6,000 to
25,000, particularly preferably 8,000 to 20,000. The content of
ethylene oxide in the ethylene oxide/propylene oxide copolymer is
not particularly limited, but is preferably 40 to 95% by weight,
more preferably 45 to 90% by weight, particularly preferably 50 to
85% by weight.
[0030] The surfactant in the present invention may be a mixture of
two or more surfactants. In this case, an anionic surfactant and a
nonionic surfactant may be simultaneously used.
[0031] The amount of the surfactant used in the aqueous dispersion
of polyamide rubber elastic body according to the present invention
is preferably 1 to 20 parts by weight, more preferably 1 to 12
parts by weight, based on 100 parts by weight of the polyamide
rubber elastic body. When the amount of the surfactant used is
lower than 1 part by weight, a stable aqueous dispersion may not be
obtained. On the other hand, when the amount of the surfactant is
higher than 20 parts by weight, emulsification is facilitated so
that a stable aqueous dispersion can be obtained, but in a molded
article formed from the resulting aqueous dispersion of the
polyamide rubber elastic body, there may be a possibility of
deteriorations in various physical properties that can be expected
from the polyamide rubber elastic body. Particularly, there is a
possibility of bleeding of the surfactant on the surface of the
molded article, or of deterioration in transparency that is a
feature of a molded article made of a polyamide rubber elastic
body.
[0032] As long as the object of the present invention is not
hindered, the aqueous dispersion of polyamide rubber elastic body
according to the present invention may as necessary contain
polymeric dispersion stabilizers such as polyvinyl alcohol,
hydroxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose,
polyacrylates, polyacrylic ester salts and sodium alginate. By
using these polymeric dispersion stabilizers, emulsification is
facilitated so that a more stable aqueous dispersion can be
obtained.
[0033] In the aqueous dispersion of polyamide rubber elastic body
according to the present invention, the average particle diameter
of the polyamide rubber elastic body is preferably 0.1 to 5 When
the average particle diameter is smaller than 0.1 .mu.m, the static
stability of the aqueous dispersion is improved, but because of
increased viscosity, handling, in particular, production of a
molded article may be made difficult. On the other hand, when the
average particle diameter is greater than 5 .mu.m, the static
stability and mechanical stability of the aqueous dispersion may be
deteriorated. This average particle diameter is determined by a
laser diffraction particle size analyzing method.
[0034] The aqueous dispersion of polyamide rubber elastic body
according to the present invention can be produced by a method of
emulsifying and dispersing a polyamide rubber elastic body in an
aqueous medium in the presence of a surfactant. The aqueous
dispersion can be produced for example by the following two
methods:
Production Method 1
[0035] In this production method, first, an organic phase
containing a polyamide rubber elastic body dissolved in an organic
solvent is mixed with an aqueous phase containing a surfactant
dissolved in an aqueous medium to prepare an emulsion. The organic
solvent used in preparation of the organic phase is not
particularly limited. Examples of the organic solvent include
aromatic hydrocarbon solvents such as toluene, xylene, ethyl
benzene and tetralin, alicyclic hydrocarbon solvents such as
cyclohexane and decalin, aliphatic hydrocarbon solvents such as
hexane and heptane, halogenated hydrocarbon solvents such as
chloroform and 1,2-dichloroethane, and alcohol solvents such as
methanol, ethanol, isopropyl alcohol and t-butanol. These organic
solvents can be used as a mixture of two or more thereof.
[0036] As the organic solvent, a mixed solvent of an aromatic
hydrocarbon solvent or an alicyclic hydrocarbon solvent and an
alcohol solvent is preferably used, since the solubility of the
polyamide rubber elastic body is good in such a mixed solvent.
Although the mixing ratio of the alcohol solvent to the aromatic
hydrocarbon solvent or the alicyclic hydrocarbon solvent in the
mixed solvent is not particularly limited, the amount of the
alcohol solvent is set in the range of preferably 25 to 100 parts
by weight, more preferably 40 to 60 parts by weight, based on 100
parts by weight of the aromatic hydrocarbon solvent or the
alicyclic hydrocarbon solvent.
[0037] The amount of the organic solvent used in preparation of the
organic phase is not particularly limited, but it is preferable
that the concentration of the polyamide rubber elastic body in the
organic phase is to be set at 3 to 30% by weight. When the
concentration of the polyamide rubber elastic body in the organic
phase is higher than 30% by weight, there is the possibility that
the polyamide rubber elastic body is hardly uniformly dissolved in
the organic phase, so that the particle diameter of the polyamide
rubber elastic body in the intended aqueous dispersion of polyamide
rubber elastic body is increased. It is uneconomical when the
concentration of the polyamide rubber elastic body is lower than 3%
by weight, because any result corresponding to the amount of the
organic solvent used cannot be obtained.
[0038] The organic phase can be prepared by adding the polyamide
rubber elastic body to an organic solvent and dissolving it. The
temperature at the time of preparation, although not particularly
restricted, is preferably controlled usually to 100.degree. C. or
less.
[0039] The aqueous phase can be prepared by adding a surfactant to
an aqueous medium and dissolving it. The amount of the surfactant
added to the aqueous medium is not particularly limited, but it is
preferable that the concentration of the surfactant in the aqueous
medium is to be set at 0.1 to 50% by weight.
[0040] When the organic phase is mixed with the aqueous phase to
prepare an emulsion, the mixing ratio of the organic phase to the
aqueous phase should be set such that the ratio of the surfactant
to the polyamide rubber elastic body is in the range defined above.
Generally, the amount of the aqueous phase is set preferably in the
range of 20 to 500 parts by weight, more preferably 25 to 200 parts
by weight, based on 100 parts by weight of the organic phase. When
the amount of the aqueous phase is lower than 20 parts by weight,
there are cases where emulsification is infeasible or the viscosity
of the resulting emulsion becomes too high. On the other hand, when
the amount of the aqueous phase is higher than 500 parts by weight,
such a manner tends to lack practicality due to low productivity of
the intended emulsion while emulsification is feasible.
[0041] The method of mixing the organic phase with the aqueous
phase to prepare an emulsion is not particularly limited. For
example, it is possible to use a method of mixing the organic phase
with the aqueous phase under stirring with an emulsion machine such
as a homomixer or a colloid mill or a method of mixing the organic
phase with the aqueous phase by dispersion with an ultrasonic
disperser or the like, among which the former is usually
preferable. Although the temperature in preparation of the emulsion
is not particularly limited, it is preferable that the temperature
is usually set in the range of 5 to 70.degree. C.
[0042] To mix the organic phase with the aqueous phase by means of
an emulsion machine, an ultrasonic disperser or the like, the
number of revolutions of a stirrer, the stirring time and
temperature are regulated appropriately such that the average
particle diameter of the polyamide rubber elastic body comes to be
in the range mentioned above. The average particle diameter of the
polyamide rubber elastic body can be set in the above-mentioned
range not only by regulating the number of revolutions of the
stirrer, the stirring time and the like, but also by selection of a
surfactant used or control of the amount of the surfactant.
[0043] Then, the organic solvent is distilled off from the emulsion
prepared in the above step. The aqueous dispersion of polyamide
rubber elastic body according to the present invention is thereby
obtained. The organic solvent can be distilled off from the
emulsion by a usual method of, for example, removing the organic
solvent by heating the emulsion under reduced pressure. The
resulting aqueous dispersion of polyamide rubber elastic body may
be concentrated as necessary by operation such as concentration
under heating, centrifugation or wet separation, whereby the
concentration of the polyamide rubber elastic body can be regulated
depending on intended use.
[0044] When a polymeric dispersion stabilizer-containing aqueous
dispersion of the polyamide rubber elastic body is prepared, the
manner of adding the polymeric dispersion stabilizer is not
particularly limited. For example, the polymeric dispersion
stabilizer may be added during preparation of the aqueous phase by
adding a surfactant to an aqueous medium or may be added to the
aqueous dispersion obtained by distilling an organic solvent
off.
Production Method 2
[0045] In this production method, first, a polyamide rubber elastic
body, a surfactant and an aqueous medium are introduced into a
container to prepare a mixture thereof. The ratio of the surfactant
to the polyamide rubber elastic body is set as described above. The
amount of the aqueous medium used, although not particularly
limited, is set preferably in the range of 40 to 1,000 parts by
weight, more preferably 50 to 150 parts by weight, based on 100
parts by weight of the polyamide rubber elastic body. When the
amount of the aqueous medium used is lower than 40 parts by weight,
an aqueous dispersion excellent in dispersion stability and the
like may not be obtained. When the amount of the aqueous medium
used is higher than 1,000 parts by weight, an aqueous dispersion
excellent in dispersion stability and the like can be obtained, but
such a manner tends to lack practicality due to low productivity of
the intended aqueous dispersion.
[0046] The container used in preparation of the mixture described
above is preferably a pressure-resistant container provided with a
heating means for heating the mixture at a temperature not lower
than the temperature at which the polyamide rubber elastic body is
softened in the aqueous medium and with a stirring means capable of
giving shear strength to the content. For example, a
pressure-resistant autoclave provided with a stirrer, or the like
is preferably used.
[0047] Next, the mixture is heated with stirring to a temperature
not lower than the softening temperature of the polyamide rubber
elastic body, thereby emulsifying the mixture. Then, the emulsion
thus obtained is cooled to room temperature, to yield the intended
aqueous dispersion of the polyamide rubber elastic body. In this
method, the number of revolutions of the stirrer, the stirring time
and temperature are regulated appropriately such that the average
particle diameter of the polyamide rubber elastic body comes to be
in the range mentioned above. The average particle diameter of the
polyamide rubber elastic body can be set in the above-mentioned
range not only by regulating the number of revolutions of the
stirrer, the stirring time and the like, but also by selection of a
surfactant used or control of the amount of the surfactant.
[0048] When a polymeric dispersion stabilizer-containing aqueous
dispersion of polyamide rubber elastic body is prepared, the manner
of adding the polymeric dispersion stabilizer is not particularly
limited. For example, the polymeric dispersion stabilizer may be
added during preparation of the mixture of a polyamide rubber
elastic body, a surfactant and an aqueous medium, or may be added
to the emulsion cooled to room temperature.
[0049] The aqueous dispersion of polyamide rubber elastic body
according to the present invention has excellent static stability
and moldability and is thus useful as a material for producing
various molded articles. For example, the aqueous dispersion of
polyamide rubber elastic body according to the present invention,
when applied onto a base material or cast in a molding box and
dried (that is, water is removed), is formed into molded articles
of various forms such as coating, film and sheet, containing the
surfactant and the polyamide rubber elastic body. The drying
temperature is not particularly limited, but is usually preferably
set in the range of 40 to 200.degree. C.
[0050] In the aqueous dispersion of polyamide rubber elastic body
according to the present invention, the polyamide rubber elastic
body is excellent in compatibility with the surfactant. Therefore,
the molded article obtained as described above is substantially
free from bleeding of the surfactant, is superior in outward
appearance with extremely excellent transparency, and is free from
deteriorations in various properties inherent in the polyamide
rubber elastic body, that is, flexibility, impact strength, tensile
strength, vibration resistance, abrasion resistance, weather
resistance, gas barrier properties, chemical resistance and heat
resistance.
[0051] Accordingly, the aqueous dispersion of polyamide rubber
elastic body according to the present invention can be utilized in
various applications as a material for producing packaging films,
automobile parts, sport-related products and medical devices; a
coating agent for nylon fibers and polyester fibers used in
clothing materials, carpets and air-bags; a coating agent and a gas
barrier agent for paper and film; a raw material for foam rubber; a
binder for fiber materials such as synthetic fibers, natural fibers
and glass fibers; and a material for producing hoses, tubes, belts,
gaskets and packing.
EXAMPLES
Example 1
[0052] A 500-ml separable flask was charged with 16 g of a
polyether ester block amide copolymer (trade name: Pebax 2533SA01,
melting point 134.degree. C., manufactured by Arkema, Ltd.), 123 g
of toluene and 61 g of isopropyl alcohol, and the copolymer was
dissolved at 80.degree. C. under stirring for 4 hours. To the
resulting organic phase solution was added an aqueous solution
prepared by dissolving 5.3 g of sodium polyoxyalkylene lauryl ether
sulfate (trade name: Trax ET-314, 30 wt % active ingredient,
manufactured by NOF Corporation) in 100 g of water. The resulting
mixture was stirred and mixed for 2 minutes by means of a homomixer
(trade name: TK Homomixer Type M, manufactured by Tokushu Kika
Kogyo Co., Ltd.) to give an emulsion. The number of revolutions and
temperature during stirring and mixing were set at 12,000 rpm and
40.degree. C., respectively. The resulting emulsion was heated to
40 to 70.degree. C. at a reduced pressure of 40 to 90 kPa thereby
distilling off toluene and isopropyl alcohol, to yield an aqueous
dispersion of polyamide rubber elastic body.
Example 2
[0053] An aqueous dispersion of polyamide rubber elastic body was
obtained in the same manner as in Example 1 except that an aqueous
solution prepared by dissolving 4.3 g of sodium polyoxyalkylene
lauryl ether sulfate (trade name: Trax ET-314, wt % active
ingredient, manufactured by NOF Corporation) and 0.3 g of polyvinyl
alcohol (trade name: Gosenol GH-20, manufactured by Nippon
Synthetic Chemical Industry Co., Ltd.) in 100 g of water was added
to the organic phase solution.
Example 3
[0054] An aqueous dispersion of polyamide rubber elastic body was
obtained in the same manner as in Example 1 except that 2.0 g of
sodium dioctylsulfosuccinate (trade name: Rapisol A-80, 80 wt %
active ingredient, manufactured by NOF Corporation) was used in
place of 5.3 g of sodium polyoxyalkylene lauryl ether sulfate
(trade name: Trax ET-314, 30 wt % active ingredient, manufactured
by NOF Corporation).
Example 4
[0055] An aqueous dispersion of polyamide rubber elastic body was
obtained in the same manner as in Example 1 except that an aqueous
solution prepared by dissolving 1.6 g of potassium oleate in 150 g
of water was used in place of the aqueous solution prepared by
dissolving 5.3 g of sodium polyoxyalkylene lauryl ether sulfate
(trade name: Trax ET-314, 30 wt % active ingredient, manufactured
by NOF Corporation) in 100 g of water.
Example 5
[0056] A 1-liter pressure-resistant autoclave provided with a
turbine type stirring blade of 50 mm in diameter was charged with
160 g of a polyether block amide copolymer (trade name: UBESTA
XPA9044.times.2, melting point 150.degree. C., manufactured by Ube
Industries, Ltd.), 224 g of deionized water, and 16 g of an
ethylene oxide/propylene oxide copolymer (trade name: Pluronic
F108, weight-average molecular weight of 15,500, ethylene oxide
content of 80% by weight, manufactured by Asahi Denka Kogyo K.K.),
and then closed. Then, the stirrer was started up to stir the
mixture at a revolution number of 500 rpm, while the temperature in
the autoclave was increased to 180.degree. C. While the internal
temperature was kept at 180.degree. C., the mixture was stirred for
another 15 minutes and then cooled to room temperature, to give an
aqueous dispersion of polyamide rubber elastic body.
Comparative Example 1
[0057] An aqueous dispersion of polyamide rubber elastic body was
obtained in the same manner as in Example 1 except that sodium
polyoxyalkylene lauryl ether sulfate (trade name: Trax ET-314, wt %
active ingredient, manufactured by NOF Corporation) was used in an
amount of 16 g.
Comparative Example 2
[0058] When the same procedure was carried out as in Example 1
except that sodium polyoxyalkylene lauryl ether sulfate (trade
name: Trax ET-314, 30 wt % active ingredient, manufactured by NOF
Corporation) was used in an amount of 0.3 g, massive solids were
formed while toluene and isopropyl alcohol were distilled off, and
an aqueous dispersion of polyamide rubber elastic body could not be
obtained.
Evaluation
[0059] The aqueous dispersions obtained in Examples 1 to 5 and
Comparative Example 1 were measured for their average particle
diameter, and molded articles obtained from these aqueous
dispersions were evaluated for their transparency and surfactant
bleeding. The measurement method and evaluation method in each item
are as follows. The results are shown in Table 1.
(Average Particle Diameter)
[0060] A laser diffraction particle size analyzer (trade name:
SALD-2000J, manufactured by Shimadzu Corporation) was used in
measurement.
(Transparency)
[0061] Each aqueous dispersion was applied by the use of a bar
coater onto a polyester sheet so that a coating thereof reaches 30
.mu.m in thickness after drying, and then dried at 170.degree. C.
for 1 hour. The state of a molded article thus obtained in the form
of a coating was evaluated under the following criteria by visual
observation.
.largecircle.: The coating is transparent. x: The coating is
clouded.
(Bleeding)
[0062] Each coating obtained in the evaluation of transparency was
evaluated for its surfactant bleeding under the following criteria
by visual observation.
.largecircle.: There is no bleeding of the surfactant from the
surface of the coating. x: There is slight bleeding of the
surfactant from the surface of the coating.
TABLE-US-00001 TABLE 1 Average particle diameter (.mu.m)
Transparency Bleeding Examples 1 0.7 .largecircle. .largecircle. 2
0.5 .largecircle. .largecircle. 3 0.7 .largecircle. .largecircle. 4
1.2 .largecircle. .largecircle. 5 1.9 .largecircle. .largecircle.
Comparative 1 0.6 .largecircle. X Examples 2 -- -- --
[0063] From Table 1, it can be seen that the aqueous dispersions of
polyamide rubber elastic bodies obtained in Examples 1 to 5 have a
small average particle diameter, and the molded articles obtained
therefrom are excellent in transparency and free from surfactant
bleeding. On the other hand, the aqueous dispersion of polyamide
rubber elastic body obtained in Comparative Example 1 had a small
average particle diameter, but the molded article obtained
therefrom was recognized to generate surfactant bleeding although
having transparency.
[0064] The present invention can be carried out in other various
forms without departure from the spirit and scope of the present
invention. Accordingly, the embodiments and examples described
above are merely illustrative in any aspects and are not to be
construed as restrictive. The scope of the present invention is
defined by the claims and is not restricted in any sense by the
description of the specification. Any variations and modifications
that fall within equivalence of the claims are intended to fall
within the scope of the present invention.
* * * * *