U.S. patent application number 14/913105 was filed with the patent office on 2016-07-21 for urethane resin composition, leather-like sheet, and method for producing the leather-like sheet.
The applicant listed for this patent is DIC CORPORATION. Invention is credited to Tomohiro TETSUI.
Application Number | 20160208432 14/913105 |
Document ID | / |
Family ID | 52628215 |
Filed Date | 2016-07-21 |
United States Patent
Application |
20160208432 |
Kind Code |
A1 |
TETSUI; Tomohiro |
July 21, 2016 |
URETHANE RESIN COMPOSITION, LEATHER-LIKE SHEET, AND METHOD FOR
PRODUCING THE LEATHER-LIKE SHEET
Abstract
Provided is an aqueous urethane resin composition with which a
fiber base can be impregnated, which is capable of thermal
coagulation, which does not detach from the fiber base due to water
or heat in the step of coloring the impregnated base, and which is
capable of forming a coating film having resistance to
discoloration which may occur with time and an excellent feeling,
that is, flexibility and resilience. The aqueous urethane resin
composition includes a urethane resin, a nonionic emulsifier, and
an aqueous medium, the urethane resin being produced by reacting a
polyol including a polyol including a carboxyl group with an
aromatic polyisocyanate and a chain extender, the content of urea
linkage in the urethane resin being 0.3 mol/kg or less. Also
provided is a leather-like sheet produced by impregnating a fiber
base with the aqueous urethane resin composition and subsequently
performing thermal coagulation of the urethane resin
composition.
Inventors: |
TETSUI; Tomohiro; (Osaka,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DIC CORPORATION |
Tokyo |
|
JP |
|
|
Family ID: |
52628215 |
Appl. No.: |
14/913105 |
Filed: |
August 7, 2014 |
PCT Filed: |
August 7, 2014 |
PCT NO: |
PCT/JP2014/070844 |
371 Date: |
February 19, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08G 18/0823 20130101;
D06M 15/572 20130101; C08G 18/4854 20130101; D06N 3/146 20130101;
C08G 18/6692 20130101; D06M 15/564 20130101; C08G 18/7657 20130101;
C08K 5/06 20130101; C08G 18/42 20130101; C08G 18/44 20130101; D06M
15/568 20130101; D06M 2101/32 20130101; C08G 18/3206 20130101; C08G
18/6659 20130101; C08G 18/348 20130101; C08K 5/06 20130101; C08L
75/04 20130101 |
International
Class: |
D06M 15/572 20060101
D06M015/572 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 6, 2013 |
JP |
2013-185015 |
Claims
1-7. (canceled)
8. A leather-like sheet produced by impregnating a fiber base with
an aqueous urethane resin composition and subsequently performing
thermal coagulation of the aqueous urethane resin composition, the
aqueous urethane resin composition including a urethane resin (A),
a nonionic emulsifier (B), and an aqueous medium (C), the urethane
resin (A) being produced by reacting a polyol (a1) including a
polyol (a1-1) including a carboxyl group with an aromatic
polyisocyanate (a2) and a chain extender (a3), the content of urea
linkage in the urethane resin (A) being 0.3 mol/kg or less.
9. The leather-like sheet according to claim 8, wherein the content
of aromatic ring in the urethane resin (A) is 0.3 to 5 mol/kg.
10. The leather-like sheet according to claim 8, wherein the
aromatic polyisocyanate (a2) is diphenylmethane diisocyanate or
toluene diisocyanate.
11. The leather-like sheet according to claim 8, wherein the polyol
(a1) includes at least one polyol selected from the group
consisting of a polyether polyol, a polyester polyol, and a
polycarbonate polyol.
12. The leather-like sheet according to claim 8, wherein the polyol
(a1-1) including a carboxyl group is 2,2'-dimethylolpropionic acid,
2,2'-dimethylolbutanoic acid, or 2,2'-dimethylolbutyric acid.
13. The leather-like sheet according to claim 8, wherein the chain
extender (a3) is ethylene glycol or 1,4-butanediol.
14. The leather-like sheet according to claim 8, wherein the
nonionic emulsifier (B) includes an oxyethylene group, the average
number of moles of the oxyethylene group included in the nonionic
emulsifier (B) being 1 to 50.
15. The leather-like sheet according to claim 8, wherein the amount
of the nonionic emulsifier (B) used is 0.1 to 30 parts by mass
relative to 100 parts by mass of the urethane resin (A).
16. The leather-like sheet according to claim 8, wherein the amount
of the polyol (a1-1) including a carboxyl group is 0.05% to 10% by
mass of the amount of the polyol (a1).
17. The leather-like sheet according to claim 8, wherein the amount
of the chain extender (a3) used is 0.5% to 20% by mass of the total
amount of the polyol (a1), the aromatic polyisocyanate (a2), and
the chain extender (a3).
Description
TECHNICAL FIELD
[0001] The present invention relates to an aqueous urethane resin
composition that can be used for producing leather-like sheets or
the like.
BACKGROUND ART
[0002] Aqueous urethane resin compositions produced by dispersing a
urethane resin in an aqueous medium have been widely used as a
material of leather-like sheets such as artificial leather and
synthetic leather, coating agents, adhesives, or the like, because
the aqueous urethane resin compositions cause a smaller
environmental load than the organic-solvent-based urethane resin
compositions of the related art.
[0003] In general, most of the leather-like sheets are constituted
by a base composed of nonwoven fabric or the like, an intermediate
layer including a porous layer, and a surface coating layer, and
the base is produced by impregnating a fiber base composed of
nonwoven fabric or the like with an aqueous urethane resin
composition and subsequently performing thermal coagulation of the
urethane resin composition in order to enhance the flex resistance
and feeling of the leather-like sheets.
[0004] As an aqueous urethane resin composition with which the
fiber base is impregnated, for example, there has been proposed a
urethane resin composition including a urethane resin, a nonionic
emulsifier, and an aqueous medium, the urethane resin being
produced by reacting a polyol including a polyol including a
carboxyl group with an alicyclic polyisocyanate and a chain
extender including an amino group (see, e.g., PTL 1).
[0005] However, this aqueous urethane resin composition is likely
to become discolored with time. Furthermore, goods produced using
the aqueous urethane resin composition are paper-like and do not
have resilience. Thus, the improvement of the feeling of goods
produced using the aqueous urethane resin composition has been
needed.
CITATION LIST
Patent Literature
[0006] PTL 1: Japanese Unexamined Patent Application Publication
No. 11-335975
SUMMARY OF INVENTION
Technical Problem
[0007] An object of the present invention is to provide an aqueous
urethane resin composition with which a fiber base can be
impregnated, which is capable of thermal coagulation, which does
not detach from the fiber base due to water or heat in the step of
coloring the impregnated base, and which is capable of forming a
coating film having resistance to discoloration which may occur
with time and an excellent feeling, that is, flexibility and
resilience.
Solution to Problem
[0008] The present invention provides an aqueous urethane resin
composition including a urethane resin (A), a nonionic emulsifier
(B), and an aqueous medium (C), the urethane resin (A) being
produced by reacting a polyol (a1) including a polyol (a1-1)
including a carboxyl group with an aromatic polyisocyanate (a2) and
a chain extender (a3), the content of urea linkage in the urethane
resin (A) being 0.3 mol/kg or less.
[0009] The present invention also provides a leather-like sheet
produced by impregnating a fiber base with the above-described
aqueous urethane resin composition and subsequently performing
thermal coagulation of the aqueous urethane resin composition.
[0010] The present invention further provides a method for
producing a leather-like sheet, the method including impregnating a
fiber base with the above-described aqueous urethane resin
composition, and subsequently drying the resulting fiber base by
heat in order to perform thermal coagulation of the aqueous
urethane resin composition.
Advantageous Effects of Invention
[0011] The aqueous urethane resin composition according to the
present invention is a urethane resin composition with which a
fiber base can be impregnated, which is capable of thermal
coagulation, and which do not detach from the fiber base when the
impregnated base is, for example, colored. The aqueous urethane
resin composition according to the present invention is capable of
forming a coating film having resistance to discoloration which may
occur with time, flexibility, and an adequate degree of resilience
due to rubber elasticity. Thus, the aqueous urethane resin
composition according to the present invention may be suitably used
as a material of leather-like sheets such as artificial leather and
synthetic leather, coating agents, adhesives, or the like and
particularly suitably used as a material of leather-like
sheets.
DESCRIPTION OF EMBODIMENTS
[0012] The aqueous urethane resin composition according to the
present invention includes, as essential components, a urethane
resin (A), a nonionic emulsifier (B), and an aqueous medium (C).
The urethane resin (A) is produced by reacting a polyol (a1)
including a polyol (a1-1) including a carboxyl group with an
aromatic polyisocyanate (a2) and a chain extender (a3). The content
of urea linkage in the urethane resin (A) is 0.3 mol/kg or
less.
[0013] Examples of the polyol (a1-1) including a carboxyl group
include 2,2'-dimethylolpropionic acid, 2,2'-dimethylolbutanoic
acid, 2,2'-dimethylolbutyric acid, and 2,2'-valeric acid. The above
compounds may be used alone or in combination of two or more.
[0014] Since the urethane resin (A) includes the polyol (a1-1)
including a carboxyl group, the urethane resin (A) serves as an
anionic urethane resin including a carboxyl group. If the polyol
(a1-1) including a carboxyl group is not used as a raw material of
the urethane resin (A), the urethane resin (A) may detach from the
fiber base when a sheet produced by impregnating a fiber base with
the aqueous urethane resin composition according to the present
invention and subsequently performing thermal coagulation of the
urethane resin composition is, for example, colored.
[0015] The amount of the polyol (a1-1) is preferably 0.05% to 10%
by mass and is more preferably 0.1% to 7% by mass of the amount of
the polyol (a1).
[0016] Examples of polyols other than the polyol (a1-1) which may
be included in the polyol (a1) include polyether polyols, polyester
polyols, polycarbonate polyols, dimer diols, acrylic polyols, and
polybutadiene polyols. The above polyols may be used alone or in
combination of two or more.
[0017] The number-average molecular weight of the polyol is
preferably 500 to 8,000 and is more preferably 800 to 3,000 in
order to enhance the thermal coagulation property of the urethane
resin composition. The number-average molecular weight of the
polyol is measured by gel permeation column chromatography (GPC)
under the following conditions.
[0018] Measurement equipment: High-speed GPC system ("HLC-8220GPC"
produced by Tosoh Corporation)
[0019] Columns: The following columns produced by Tosoh Corporation
are connected in series.
[0020] "TSKgel G5000" (7.8 mm I.D..times.30 cm).times.1
[0021] "TSKgel G4000" (7.8 mm I.D..times.30 cm).times.1
[0022] "TSKgel G3000" (7.8 mm I.D..times.30 cm).times.1
[0023] "TSKgel G2000" (7.8 mm I.D..times.30 cm).times.1
[0024] Detector: RI (differential refractometer)
[0025] Column temperature: 40.degree. C.
[0026] Eluent: Tetrahydrofuran (THF)
[0027] Flow rate: 1.0 mL/min
[0028] Amount of injection: 100 .mu.L (tetrahydrofuran solution,
sample density: 0.4 mass %)
[0029] Reference samples: A calibration curve is prepared using the
following standard polystyrenes.
(Standard Polystyrenes)
[0030] "TSKgel Standard Polystyrene A-500" produced by Tosoh
Corporation
[0031] "TSKgel Standard Polystyrene A-1000" produced by Tosoh
Corporation
[0032] "TSKgel Standard Polystyrene A-2500" produced by Tosoh
Corporation
[0033] "TSKgel Standard Polystyrene A-5000" produced by Tosoh
Corporation
[0034] "TSKgel Standard Polystyrene F-1" produced by Tosoh
Corporation
[0035] "TSKgel Standard Polystyrene F-2" produced by Tosoh
Corporation
[0036] "TSKgel Standard Polystyrene F-4" produced by Tosoh
Corporation
[0037] "TSKgel Standard Polystyrene F-10" produced by Tosoh
Corporation
[0038] "TSKgel Standard Polystyrene F-20" produced by Tosoh
Corporation
[0039] "TSKgel Standard Polystyrene F-40" produced by Tosoh
Corporation
[0040] "TSKgel Standard Polystyrene F-80" produced by Tosoh
Corporation
[0041] "TSKgel Standard Polystyrene F-128" produced by Tosoh
Corporation
[0042] "TSKgel Standard Polystyrene F-288" produced by Tosoh
Corporation
[0043] "TSKgel Standard Polystyrene F-550" produced by Tosoh
Corporation
[0044] The aromatic polyisocyanate (a2) is essential for forming a
coating film having an excellent feeling (i.e., flexibility and
resilience). If the aromatic polyisocyanate (a2) is replaced with
another polyisocyanate, a paper-like coating film having poor
resilience, that is, a coating film having a poor feeling, is
formed. Examples of the aromatic polyisocyanate (a2) include
phenylene diisocyanate, tolylene diisocyanate, diphenylmethane
diisocyanate, naphthalene diisocyanate, polymethylene polyphenyl
polyisocyanate, and carbodiimidized diphenylmethane polyisocyanate.
The above aromatic polyisocyanates may be used alone or in
combination of two or more. Among the above aromatic
polyisocyanates, diphenylmethane diisocyanate is preferably used in
order to further enhance the feeling of the coating film.
[0045] The aromatic polyisocyanate (a2) may be used in combination
of other polyisocyanates as needed. Examples of the other
polyisocyanates include aliphatic and alicyclic polyisocyanates,
such as hexamethylene diisocyanate, lysine diisocyanate,
cyclohexane diisocyanate, isophorone diisocyanate,
dicyclohexylmethane diisocyanate, xylylene diisocyanate,
tetramethylxylylene diisocyanate, dimer acid diisocyanate, and
norbornene diisocyanate. The above polyisocyanates may be used
alone or in combination of two or more.
[0046] The chain extender (a3) may be, for example, a chain
extender including a hydroxyl group or a chain extender including
an amino group. The above chain extenders may be used alone or in
combination of two or more.
[0047] Examples of the chain extender including a hydroxyl group
include aliphatic polyol compounds such as ethylene glycol,
diethylene glycol, triethylene glycol, propylene glycol,
1,3-propanediol, 1,3-butanediol, 1,4-butanediol, hexamethylene
glycol, saccharose, methylene glycol, glycerin, and sorbitol;
aromatic polyol compounds such as bisphenol A,
4,4'-dihydroxydiphenyl, 4,4'-dihydroxydiphenyl ether,
4,4'-dihydroxydiphenyl sulfone, hydrogenated bisphenol A, and
hydroquinone; and water. The above chain extenders may be used
alone or in combination of two or more. Among the above chain
extenders, the aliphatic polyol compounds are preferably used from
the viewpoints of the availability of raw materials and a reduction
in the discoloration of the coating film which may occur with
time.
[0048] Examples of the chain extender including an amino group
include ethylenediamine, 1,2-propanediamine,
1,6-hexamethylenediamine, piperazine, 2-methylpiperazine,
2,5-dimethylpiperazine, isophoronediamine,
4,4'-dicyclohexylmethanediamine,
3,3'-dimethyl-4,4'-dicyclohexylmethanediamine,
1,2-cyclohexanediamine, 1,4-cyclohexanediamine,
aminoethylethanolamine, hydrazine, diethylenetriamine, and
triethylenetetramine. The above chain extenders may be used alone
or in combination of two or more.
[0049] The amount of the chain extender (a3) used is preferably
0.5% to 20% by mass and is more preferably 1% to 10% by mass of
total amount of the polyol (a1), the aromatic polyisocyanate (a2),
and the chain extender (a3) in order to further enhance the
durability of the coating film.
[0050] In the present invention, it is essential that the content
of urea linkage in the urethane resin (A) be 0.3 mol/kg or less. If
the content of urea linkage in the urethane resin (A) exceeds 0.3
mol/kg, the resulting coating film may become discolored with time
or the feeling of the coating film may be degraded.
[0051] The urea linkage is formed when an amino group included in
the chain extender (a3) and/or an amino group resulting from the
reaction of an isocyanate group with water react with a
polyisocyanate. Therefore, the content of urea linkage in the
urethane resin (A) can be controlled by adjusting the amount of the
chain extender including an amino group which is used as a chain
extender (a3), and by urethanizing all isocyanates before
emulsification is performed. The content of urea linkage is
calculated using General Formula (1) below.
Content of Urea Linkage (mol/kg)=[(Number of Moles of Amino
Group)+(Number of Moles of Isocyanate Group-Number of Moles of
Hydroxyl Group-Number of Moles of Amino Group)/2]/[Mass of Polyol
(a1)+Mass of Aromatic Polyisocyanate (a2)+Mass of Chain Extender
(a3)] (1)
[0052] The urethane resin (A) is produced by, for example, a method
in which the polyol (a1) is reacted with the aromatic
polyisocyanate (a1) to form a urethane prepolymer including an
isocyanate group and the urethane prepolymer is reacted with the
chain extender (a3); or a method in which the polyol (a1), the
aromatic polyisocyanate (a2), and the chain extender (a3) are mixed
together and reacted with one another at a time. The above
reactions are preferably conducted, for example, at 50.degree. C.
to 100.degree. C. for 3 to 10 hours.
[0053] The molar ratio of the amount of isocyanate group included
in the aromatic polyisocyanate (a2) to the total amount of hydroxyl
group included in the polyol (a1) and hydroxyl group and/or amino
group included in the chain extender (a3), that is, [(Isocyanate
Group)/(Hydroxyl Group and/or Amino Group)], is preferably 0.8 to
1.2 and is more preferably 0.9 to 1.1.
[0054] In the production of the urethane resin (A), an isocyanate
group remaining in the urethane resin (A) is preferably
deactivated. For deactivating such an isocyanate group, an alcohol
including one hydroxyl group, such as methanol, is preferably used.
When such an alcohol is used, the amount of the alcohol used is
preferably 0.001 to 10 parts by mass relative to 100 parts by mass
of the urethane resin (A).
[0055] In the production of the urethane resin (A), an organic
solvent may be used. Examples of the organic solvent include ketone
compounds such as acetone and methyl ethyl ketone; ether compounds
such as tetrahydrofuran and dioxane; ester compounds of acetic
acid, such as ethyl acetate and butyl acetate; nitrile compounds
such as acetonitrile; and amide compounds such as dimethylformamide
and N-methylpyrrolidone. The above organic solvents may be used
alone or in combination of two or more. The organic solvent is
preferably removed by distillation or the like when the aqueous
urethane resin composition is prepared.
[0056] The content of aromatic ring in the urethane resin (A)
produced by the above-described method is preferably 0.3 to 5
mol/kg and is more preferably 0.3 to 3 mol/kg in order to further
increase the mechanical strength of the resulting coating film,
further reduce the discoloration of the coating film which may
occur with time, and further reduce the likelihood of the urethane
resin (A) detaching from the fiber base.
[0057] The nonionic emulsifier (B) is an essential component for
enhancing the water-dispersion stability of the urethane resin (A),
performing thermal coagulation of the urethane resin composition,
and reducing the likelihood of the urethane resin (A) detaching
from the fiber base. Examples of the nonionic emulsifier (B)
include nonionic emulsifiers including an oxyethylene group, such
as polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl
ether, polyoxyethylene distyrenated phenyl ether, polyoxyethylene
lauryl ether, polyoxyethylene oleyl ether, polyoxyethylene stearyl
ether, and polyoxyethylene sorbitol tetraoleate. The average number
of moles of the oxyethylene group included in the nonionic
emulsifier (B) is preferably 1 to 50, is more preferably 3 to 30,
and is further preferably 5 to 20 in order to further enhance the
thermal coagulation property of the urethane resin composition. The
above nonionic emulsifiers may be used alone or in combination of
two or more.
[0058] The amount of the nonionic emulsifier (B) used is preferably
0.1 to 30 parts by mass and is more preferably 1 to 10 parts by
mass relative to 100 parts by mass of the urethane resin (A) in
order to further enhance the water-dispersion stability of the
urethane resin (A) and the thermal coagulation property of the
urethane resin composition and reduce the likelihood of the
urethane resin (A) detaching from the fiber base.
[0059] Examples of the aqueous medium (C) include water, organic
solvents miscible with water, and a mixture of water and an organic
solvent miscible with water. Examples of the organic solvents
miscible with water include alcohol solvents such as methanol,
ethanol, n-propanol, and isopropanol; ketone solvents such as
acetone and methyl ethyl ketone; polyalkylene glycol solvents such
as ethylene glycol, diethylene glycol, and propylene glycol;
alkylether solvents of polyalkylene glycol; and lactam solvents
such as N-methyl-2-pyrrolidone. The above aqueous media may be used
alone or in combination of two or more. Among the above aqueous
media, water only and a mixture of water and an organic solvent
miscible with water are preferably used, and water only is more
preferably used from the viewpoints of safety and a reduction in
the environmental load.
[0060] The mass ratio [(A)/(C)] of the urethane resin (A) to the
aqueous medium (C) is preferably 10/80 to 70/30 and is more
preferably 20/80 to 60/40 in order to further enhance workability
and the feeling of the coating film.
[0061] The aqueous urethane resin composition according to the
present invention may optionally include a neutralizer and other
additives in addition to the urethane resin (A), the nonionic
emulsifier (B), and the aqueous medium (C) that are included as
essential components.
[0062] The neutralizer is an agent used for neutralizing a carboxyl
group included in the urethane resin (A). Examples of the
neutralizer include nonvolatile bases such as sodium hydroxide and
potassium hydroxide; and tertiary amines such as trimethylamine,
triethylamine, dimethylethanolamine, methyldiethanolamine, and
triethanol. The above neutralizers may be used alone or in
combination of two or more.
[0063] The amount of the neutralizer used is preferably controlled
such that the molar ratio of the neutralizer used to the carboxyl
groups included in the urethane resin (A) is 0.8 to 1.2.
[0064] Examples of the other additives include a coagulant, a
urethanization catalyst, a silane coupling agent, a filler, a
thixotropy-imparting agent, a tackifier, a wax, a heat stabilizer,
a light stabilizer, a fluorescent brightening agent, a blowing
agent, a pigment, a dye, a conductivity-imparting agent, an
antistatic agent, a moisture permeability improver, a water
repellent, an oil repellent, a hollow foam, a flame retardant, a
water absorbent, a desiccant, a deodorant, a foam stabilizer, an
antiblocking agent, and an antihydrolysis agent. The above
additives may be used alone or in combination of two or more. In
the production of the leather-like sheet in which thermal
coagulation of the aqueous urethane resin composition according to
the present invention is performed, a coagulant (D) is preferably
used among the above additives in order to enhance the thermal
coagulation property of the urethane resin composition.
[0065] Examples of the coagulant (D) include inorganic salts,
associative thickeners, and crosslinkers. The above coagulants may
be used alone or in combination of two or more.
[0066] Examples of the inorganic salts include metal salts such as
calcium nitrate, calcium chloride, zinc nitrate, zinc chloride,
magnesium acetate, aluminium sulfate, and sodium chloride. The
above inorganic salts may be used alone or in combination of two or
more.
[0067] Examples of the associative thickeners include cellulose
derivatives such as hydroxyethylcellulose, methylcellulose, and
carboxymethylcellulose; salts of polyacrylic acid,
polyvinylpyrrolidone, urethane compounds, and polyether compounds.
The above thickeners may be used alone or in combination of two or
more.
[0068] Examples of the crosslinkers include a carbodiimide
crosslinker, an isocyanate crosslinker, an epoxy crosslinker, and a
melamine crosslinker. The above crosslinkers may be used alone or
in combination of two or more.
[0069] The amount of the coagulant (D) used is preferably 0.1 to 20
parts by mass and is more preferably 0.5 to 10 parts by mass
relative to 100 parts by mass of the urethane resin (A).
[0070] The aqueous urethane resin composition according to the
present invention may be particularly suitably used for producing a
leather-like sheet including an impregnated base prepared by
impregnating a fiber base with a resin. The leather-like sheet may
be an impregnated base prepared by impregnating a fiber base with a
resin, that is, "suede" leather-like sheet. In another case, the
leather-like sheet may be produced by forming an intermediate layer
including a porous layer on the surface of the impregnated base as
needed, and forming a surface coating layer on the intermediate
layer, the impregnated base being formed by impregnating a fiber
base with a resin and performing thermal coagulation of the resin.
Thus, the aqueous urethane resin composition according to the
present invention may be suitably used as a resin composition with
which the fiber base is impregnated.
[0071] Examples of the fiber base include nonwoven fabric, woven
fabric, and knitted fabric. Examples of a material of the fiber
base include polyester fiber, nylon fiber, acrylic fiber,
polyurethane fiber, acetate fiber, rayon fiber, polylactic acid
fiber, cotton, hemp, silk, wool, and blendings of these fibers.
[0072] For impregnating the fiber base with the aqueous urethane
resin composition, for example, the fiber base is directly dipped
into a tank containing the aqueous urethane resin composition, and
excess is subsequently squeezed out using a mangle or the like.
[0073] The fiber base impregnated with the aqueous urethane resin
composition is subsequently dried by heat or steam at a temperature
(e.g., 50.degree. C. to 80.degree. C.) equal to or higher than the
thermal coagulation temperature of the urethane resin (A) in order
to perform coagulation of the urethane resin (A) and evaporate the
aqueous medium (B) included in the aqueous urethane resin
composition. Thus, a base that is a fiber base impregnated with the
urethane resin (A) can be produced. This impregnated base may be
suitably used for producing a leather-like sheet having excellent
flex resistance.
[0074] While heat drying and steam drying may be employed as
described above for drying the urethane resin (A) at a temperature
equal to or higher than the thermal coagulation temperature of the
urethane resin (A), it is known that, in general, a coating film
having a better feeling can be produced by steam drying. However,
steam drying requires large-scale facilities. On the other hand,
when the aqueous urethane resin composition according to the
present invention is used, it is possible to form a coating film
having an excellent feeling comparable to that of a coating film
formed by steam drying even when heat drying is employed, which is
a versatile method that does not require such facilities.
[0075] The leather-like sheet produced by the above-described
method may be used as, for example, a material of shoes, bags, or
clothing; a member of furniture such as a chair or a sofa; an
automotive interior material such as a material of a seat or a
handle; a breathable-waterproof material; a leather-like sheet such
as synthetic leather or artificial leather; a polishing material; a
back pad; or a core of felt-tipped pens.
[0076] Since the aqueous urethane resin composition according to
the present invention is capable of forming a coating film having
an excellent feeling, the aqueous urethane resin composition may
also be used as, for example, an agent for coating the surfaces of
various types of bases.
[0077] Examples of the bases include fiber bases composed of woven
fabric, nonwoven fabric, or the like; leather-like sheets; plated
steel sheets such as a galvanized steel sheet and an
aluminium-zinc-alloy plated steel sheet; metal bases such as an
aluminium sheet, an aluminium alloy sheet, a magnetic steel sheet,
a copper sheet, and a stainless steel sheet; plastic bases such as
a polycarbonate base, a polyester base, an
acrylonitrile-butadiene-styrene base, a polyacrylic base, a
polystyrene base, a polyurethane base, an epoxy resin base, a
polyvinyl chloride base, and a polyamide base; and a glass base.
Among the above bases, leather-like sheets such as synthetic
leather and artificial leather, which are used as a material of
shoes and bags, are preferably used, because it is possible to
produce leather-like sheets having an excellent appearance with
efficiency by bonding another member onto the surface of the
leather-like sheet with an adhesive or by applying putty or the
like onto the surface of the leather-like sheet.
[0078] It is possible to form a coating film with the aqueous
urethane resin composition according to the present invention by
applying the aqueous urethane resin composition directly onto the
surface of the base and drying the resulting coating film to
perform curing. It is also possible to form a coating film by
applying the aqueous urethane resin composition according to the
present invention onto the surface of a releasing paper, drying and
curing the resulting coating film, and subsequently stacking the
base on the surface of the releasing paper on which the coating
film has been deposited. In the case where a crosslinker is used as
a coagulant (D), it is preferable to mix the crosslinker with the
urethane resin (A) immediately before the aqueous urethane resin
composition is applied onto the surface of the base in order to
maintain ease of coating.
[0079] For applying the aqueous urethane resin composition to the
base, for example, spraying, curtain coating, flow coating, roll
coating, brush coating, and dipping may be employed.
[0080] For drying and curing the coating film, the coating film may
be maintained at ordinary temperature for about 1 to 10 days. In
order to cure the coating film quickly, it is preferable to heat
the coating film at 50.degree. C. to 250.degree. C. for about 1 to
600 seconds. In the case where a plastic base is used, which is
likely to become deformed or discolored at a relatively high
temperature, it is preferable to maintain the coating film at a
relatively low temperature of, for example, 30.degree. C. to
100.degree. C.
[0081] The thickness of the coating film, which is formed using the
urethane resin composition according to the present invention, can
be controlled appropriately depending on the application or the
like of the base and is preferably, for example, 0.5 to 100
.mu.m.
EXAMPLES
Example 1
Preparation of Aqueous Urethane Resin Composition (X-1)
[0082] In the presence of 3,281 parts by mass of methyl ethyl
ketone and 0.1 parts by mass of stannous octoate, 1,000 parts by
mass of polycarbonate polyol ("NIPPOLLAN 980R" produced by Nippon
Polyurethane Industry Co., Ltd., number-average molecular weight;
2,000) was reacted with 17 parts by mass of
2,2'-dimethylolpropionic acid, 47 parts by mass of ethylene glycol,
and 344 parts by mass of diphenylmethane diisocyanate at 70.degree.
C. until the viscosity of the reaction solution reached 20,000
mPas. Subsequently, 3 parts by mass of methanol was added to the
reaction solution in order to stop the reaction. Thus, a methyl
ethyl ketone solution of a urethane resin (A-1) was prepared. The
solution of a urethane resin was mixed with 70 parts by mass of
polyoxyethylene distyrenated phenyl ether (hydrophile-lipophile
balance [hereinafter, abbreviated as "HLB"]; 14, average number of
moles of oxyethylene group included; 10, hereinafter, abbreviated
as "(B-1)"), which served as a nonionic emulsifier (B), and 13
parts by mass of triethylamine. To the resulting mixture, 800 parts
by mass of ion-exchange water was added in order to perform phase
inversion emulsification. Thus, an emulsion containing the urethane
resin (A-1) dispersed in water was prepared.
[0083] Subsequently, methyl ethyl ketone was distilled away from
the emulsion to prepare an aqueous urethane resin composition (X-1)
having a nonvolatile content of 40% by mass.
Example 2
Preparation of Aqueous Urethane Resin Composition (X-2)
[0084] In the presence of 3,281 parts by mass of methyl ethyl
ketone and 0.1 parts by mass of stannous octoate, 1,000 parts by
mass of polyether polyol ("PTMG2000" produced by Mitsubishi
Chemical Corporation, number-average molecular weight; 2,000) was
reacted with 17 parts by mass of 2,2'-dimethylolpropionic acid, 47
parts by mass of ethylene glycol, and 344 parts by mass of
diphenylmethane diisocyanate at 70.degree. C. until the viscosity
of the reaction solution reached 20,000 mPas. Subsequently, 3 parts
by mass of methanol was added to the reaction solution in order to
stop the reaction. Thus, a methyl ethyl ketone solution of a
urethane resin (A-2) was prepared. The solution of a urethane resin
was mixed with 70 parts by mass of (B-1) and 13 parts by mass of
triethylamine. To the resulting mixture, 800 parts by mass of
ion-exchange water was added in order to perform phase inversion
emulsification. Thus, an emulsion containing the urethane resin
(A-2) dispersed in water was prepared.
[0085] Subsequently, methyl ethyl ketone was distilled away from
the emulsion to prepare an aqueous urethane resin composition (X-2)
having a nonvolatile content of 40% by mass.
Example 3
Preparation of Aqueous Urethane Resin Composition (X-3)
[0086] In the presence of 3,281 parts by mass of methyl ethyl
ketone and 0.1 parts by mass of stannous octoate, 1,000 parts by
mass of polyester polyol ("PLACCEL 220" produced by Daicel
Corporation, number-average molecular weight; 2,000) was reacted
with 17 parts by mass of 2,2'-dimethylolpropionic acid, 47 parts by
mass of ethylene glycol, and 344 parts by mass of diphenylmethane
diisocyanate at 70.degree. C. until the viscosity of the reaction
solution reached 20,000 mPas. Subsequently, 3 parts by mass of
methanol was added to the reaction solution in order to stop the
reaction. Thus, a methyl ethyl ketone solution of a urethane resin
(A-3) was prepared. The solution of a urethane resin was mixed with
70 parts by mass of (B-1) and 13 parts by mass of triethylamine. To
the resulting mixture, 800 parts by mass of ion-exchange water was
added in order to perform phase inversion emulsification. Thus, an
emulsion containing the urethane resin (A-3) dispersed in water was
prepared.
[0087] Subsequently, methyl ethyl ketone was distilled away from
the emulsion to prepare an aqueous urethane resin composition (X-3)
having a nonvolatile content of 40% by mass.
Comparative Example 1
Preparation of Aqueous Urethane Resin Composition (X'-1)
[0088] In the presence of 3,723 parts by mass of methyl ethyl
ketone and 0.1 parts by mass of stannous octoate, 1,000 parts by
mass of polyether polyol ("PTMG2000" produced by Mitsubishi
Chemical Corporation, number-average molecular weight; 2,000), 130
parts by mass of "UNILUBE 75DE-60" (produced by NOF CORPORATION,
polyoxyethylene polyoxypropylene glycol having a number-average
molecular weight of 3,000), and 50 parts by mass of "UNILUBE 75
MB-900" (produced by NOF CORPORATION, polyoxyethylene
polyoxypropylene glycol monobutyl ether having a number-average
molecular weight of 3,400) were reacted with 57 parts by mass of
ethylene glycol and 360 parts by mass of diphenylmethane
diisocyanate at 70.degree. C. until the viscosity of the reaction
solution reached 20,000 mPas. Subsequently, 3 parts by mass of
methanol was added to the reaction solution in order to stop the
reaction. Thus, a methyl ethyl ketone solution of a urethane resin
(A'-1) was prepared. The solution of a urethane resin was mixed
with 79 parts by mass of (B-1). To the resulting mixture, 8,000
parts by mass of ion-exchange water was added in order to perform
phase inversion emulsification. Thus, an emulsion containing the
urethane resin (A'-1) dispersed in water was prepared.
[0089] Subsequently, methyl ethyl ketone was distilled away from
the emulsion to prepare an aqueous urethane resin composition
(X'-1) having a nonvolatile content of 40% by mass.
Comparative Example 2
Preparation of Aqueous Urethane Resin Composition (X'-2)
[0090] In the presence of 3,505 parts by mass of methyl ethyl
ketone and 0.1 parts by mass of stannous octoate, 1,000 parts by
mass of polycarbonate polyol ("NIPPOLLAN 980R" produced by Nippon
Polyurethane Industry Co., Ltd., number-average molecular weight;
2,000) was reacted with 50 parts by mass of
2,2'-dimethylolpropionic acid, 47 parts by mass of ethylene glycol,
and 407 parts by mass of diphenylmethane diisocyanate at 70.degree.
C. until the viscosity of the reaction solution reached 20,000
mPas. Subsequently, 3 parts by mass of methanol was added to the
reaction solution in order to stop the reaction. Thus, a methyl
ethyl ketone solution of a urethane resin (A'-2) was prepared. The
solution of a urethane resin was mixed with 38 parts by mass of
triethylamine. To the resulting mixture, 800 parts by mass of
ion-exchange water was added in order to perform phase inversion
emulsification. Thus, an emulsion containing the urethane resin
(A'-2) dispersed in water was prepared.
[0091] Subsequently, methyl ethyl ketone was distilled away from
the emulsion to prepare an aqueous urethane resin composition
(X'-2) having a nonvolatile content of 40% by mass.
Comparative Example 3
Preparation of Aqueous Urethane Resin Composition (X'-3)
[0092] In the presence of 3,749 parts by mass of methyl ethyl
ketone and 0.1 parts by mass of stannous octoate, 1,000 parts by
mass of polycarbonate polyol ("NIPPOLLAN 980R" produced by Nippon
Polyurethane Industry Co., Ltd., number-average molecular weight;
2,000) and 180 parts by mass of "UNILUBE 75 MB-900" (produced by
NOF CORPORATION, polyoxyethylene polyoxypropylene glycol monobutyl
ether having a number-average molecular weight of 3,400) were
reacted with 18 parts by mass of 2,2'-dimethylolpropionic acid, 49
parts by mass of ethylene glycol, and 362 parts by mass of
diphenylmethane diisocyanate at 70.degree. C. until the viscosity
of the reaction solution reached 20,000 mPas. Subsequently, 3 parts
by mass of methanol was added to the reaction solution in order to
stop the reaction. Thus, a methyl ethyl ketone solution of a
urethane resin (A'-3) was prepared. The solution of a urethane
resin was mixed with 13 parts by mass of triethylamine. To the
resulting mixture, 800 parts by mass of ion-exchange water was
added in order to perform phase inversion emulsification. Thus, an
emulsion containing the urethane resin (A'-3) dispersed in water
was prepared.
[0093] Subsequently, methyl ethyl ketone was distilled away from
the emulsion to prepare an aqueous urethane resin composition
(X'-3) having a nonvolatile content of 40% by mass.
Comparative Example 4
Preparation of Aqueous Urethane Resin Composition (X'-4)
[0094] In the presence of 3,320 parts by mass of methyl ethyl
ketone and 0.1 parts by mass of stannous octoate, 1,000 parts by
mass of polycarbonate polyol ("NIPPOLLAN 980R" produced by Nippon
Polyurethane Industry Co., Ltd., number-average molecular weight;
2,000) was reacted with 17 parts by mass of
2,2'-dimethylolpropionic acid, 47 parts by mass of ethylene glycol,
and 407 parts by mass of dicyclohexylmethane diisocyanate at
70.degree. C. until the viscosity of the reaction solution reached
20,000 mPas. Subsequently, 3 parts by mass of methanol was added to
the reaction solution in order to stop the reaction. Thus, a methyl
ethyl ketone solution of a urethane resin (A'-4) was prepared. The
solution of a urethane resin was mixed with 70 parts by mass of
(B-1) and 13 parts by mass of triethylamine. To the resulting
mixture, 800 parts by mass of ion-exchange water was added in order
to perform phase inversion emulsification. Thus, an emulsion
containing the urethane resin (A'-4) dispersed in water was
prepared.
[0095] Subsequently, methyl ethyl ketone was distilled away from
the emulsion to prepare an aqueous urethane resin composition
(X'-4) having a nonvolatile content of 40% by mass.
Comparative Example 5
Preparation of Aqueous Urethane Resin Composition (X'-5)
[0096] In the presence of 2,902 parts by mass of methyl ethyl
ketone and 0.1 parts by mass of stannous octoate, 1,000 parts by
mass of polycarbonate polyol ("NIPPOLLAN 980R" produced by Nippon
Polyurethane Industry Co., Ltd., number-average molecular weight;
2,000) was reacted with 17 parts by mass of
2,2'-dimethylolpropionic acid, 12 parts by mass of ethylenediamine,
and 216 parts by mass of diphenylmethane diisocyanate at 70.degree.
C. until the viscosity of the reaction solution reached 20,000
mPas. Subsequently, 3 parts by mass of methanol was added to the
reaction solution in order to stop the reaction. Thus, a methyl
ethyl ketone solution of a urethane resin (A'-5) was prepared. The
solution of a urethane resin was mixed with 62 parts by mass of
(B-1) and 13 parts by mass of triethylamine. To the resulting
mixture, 800 parts by mass of ion-exchange water was added in order
to perform phase inversion emulsification. Thus, an emulsion
containing the urethane resin (A'-5) dispersed in water was
prepared.
[0097] Subsequently, methyl ethyl ketone was distilled away from
the emulsion to prepare an aqueous urethane resin composition
(X'-5) having a nonvolatile content of 40% by mass.
[Method for Evaluating Water-Dispersion Stability]
[0098] An evaluation of "T" was given when the urethane resin was
able to be dispersed in the aqueous medium to form an aqueous
urethane resin composition by the method described in Examples and
Comparative examples. An evaluation of "F" was given when the
urethane resin was not able to be dispersed in the aqueous medium
and settled or gelated.
[Method for Preparing Impregnated Base]
[0099] With 100 parts by mass of a 2-mass % aqueous sodium chloride
solution, 100 parts by mass of each of the aqueous urethane resin
compositions prepared in Examples and Comparative Examples was
mixed, and the resulting mixture was stirred with a mechanical
mixer at 2,000 rpm for 2 minutes in order to prepare an aqueous
urethane resin composition for impregnation.
[0100] Nonwoven fabric sheets composed of polyester fiber having a
basis weight of 300 g/m.sup.2 (thickness: 1.5 mm) were each dipped
into a tank containing a specific one of the aqueous urethane resin
compositions for impregnation. The resulting nonwoven fabric sheets
were wrung with a mangle equipped with a rubber roller. Thus,
products impregnated with the respective aqueous urethane resin
compositions were prepared. The mass of the aqueous urethane resin
composition included in each product was equal to the mass of the
nonwoven fabric sheet used. The impregnated products were dried at
100.degree. C. for 10 minutes with a gear hot-air drying machine.
Thus, leather-like sheets including an impregnated base, which was
prepared by impregnating nonwoven fabric with a urethane resin,
were prepared.
[0101] Note that, in the case where the aqueous urethane resin
composition was coagulated at ordinary temperature after being
mixed with the 2-mass % aqueous sodium chloride solution, the
following evaluations were omitted and an evaluation of "-" was
given.
[Occurrence of Detachment of Urethane Resin from Leather-Like Sheet
in Coloring Step]
[0102] In the evaluation of occurrence of detachment of the
urethane resin from the leather-like sheet in the coloring step, a
surrogate test in which water containing no dye was used as a
coloring liquid was conducted. This evaluation method can be
employed as a substitute for a method for evaluating detachment of
the urethane resin in the coloring step, because the detachment of
the urethane resin is caused due to water and water
temperature.
[0103] In this testing method, the mass of each leather-like sheet
including the impregnated base was measured. Subsequently, the
leather-like sheet was immersed in water at 25.degree. C. and,
while stirring was performed at 60 rpm, the temperature was
increased to 130.degree. C. at 1.degree. C./min. After the
leather-like sheet was maintained at 130.degree. C. for 30 minutes,
the temperature was reduced to 25.degree. C. at 1.degree.
C./min.
[0104] After cooling was completed, the surface of the impregnated
base was washed with water and subsequently dried at 120.degree. C.
for 5 minutes with a gear hot-air drying machine. The mass of the
dried leather-like sheet was measured.
[0105] The proportion of urethane resin that detached from the
leather-like sheet was calculated from the measured values using
the following formula. Formula; 100.times.[Mass of Dried
Leather-Like Sheet/Initial Mass of Leather-Like Sheet]
[Thermal Coagulation Property (Method for Measuring Thermal
Coagulation Temperature)]
[0106] Adjustment was made such that each of the aqueous urethane
resin compositions prepared by the above-described method had a
nonvolatile content of 20% by mass.
[0107] Subsequently, the viscosity of each of the resulting aqueous
urethane resin compositions was measured with a
viscosity-viscoelasticity measurement system ("Reo Stress" produced
by HAAKE) while heating was performed at 1.degree. C./min. The
temperature at which the viscosity of each aqueous urethane resin
composition exceeded 100 mPas was considered to be the coagulation
temperature (.degree. C.) of the aqueous urethane resin
composition.
[Method for Evaluating Feeling of Leather-Like Sheet]
[0108] The feeling of each of the fiber multilayer bodies prepared
by the above-described method was evaluated in terms of flexibility
and resilience by touching the fiber multilayer body.
(Evaluation of Flexibility)
[0109] T: Flexible F: Hard
(Evaluation of Resilience)
[0110] T: Resilient F: Paper-like, not resilient
[Method for Evaluating Discoloration]
[0111] The color of the exterior of each of the fiber multilayer
bodies prepared by the above-described method was visually
inspected and evaluated subjectively.
[0112] T: White (no discoloration) F: Yellow
TABLE-US-00001 TABLE 1 Exam- Exam- Exam- ple 1 ple 2 ple 3 Aqueous
urethane resin composition X-1 X-2 X-3 Urethane resin (A) Polyol
(a1) Polyol including carboxyl group DMPA DMPA DMPA (a1-1) Other
polyols PC PEt PEs Aromatic polyisocyanate (a2) MDI MDI MDI Chain
extender (a3) EG EG EG Content of urea linkages in urethane 0 0 0
resin (A) (mol/kg) Content of aromatic rings in urethane 1.95 1.95
1.95 resin (A) (mol/kg) Nonionic emulsifier (B) B-1 B-1 B-1 Aqueous
medium (C) Ion- Ion- Ion- exchange exchange exchange water water
water Coagulant (D) Nacl Nacl Nacl Water-dispersion stability T T T
Thermal coagulation temperature 45 46 44 (.degree. C.) Proportion
of urethane resin lost 0.2 0.3 0.3 (mass %) Feeling Flexibility T T
T Resilience T T T Discoloration T T T
TABLE-US-00002 TABLE 2 Comparative Comparative Comparative
Comparative Comparative example 1 example 2 example 3 example 4
example 5 Aqueous urethane resin composition X'-1 X'-2 X'-3 X'-4
X'-5 Urethane resin (A) Polyol (a1) Polyol including carboxyl group
DMPA DMPA DMPA DMPA (a1-1) Other polyols PC PC PC PC PC UNILUBE
UNILUBE 75DE-60 75MB-900 UNILUBE 75MB-900 Aromatic polyisocyanate
(a2) MDI MDI MDI MDI Other polyisocyanates H12MDI Chain extender
(a3) EG EG EG EG EDA Content of urea linkages in urethane 0 0 0 0
0.32 resin (A) (mol/kg) Content of aromatic rings in urethane 1.80
2.16 1.80 0 1.39 resin (A) (mol/kg) Nonionic emulsifier(B) B-1 B-1
B-1 Aqueous medium (C) Ion- Ion- Ion- Ion- Ion- exchange exchange
exchange exchange exchange water water water water water Coagulant
(D) NaCl NaCl NaCl NaCl NaCl Water-dispersion stability T T T T T
Thermal coagulation temperature 50 -- 60 45 45 (.degree. C.)
Proportion of urethane resin lost 2 -- 5 0.3 0.3 (mass %) Feeling
Flexibility T -- T T T Resilience T -- T F F Discoloration T -- T T
F
[0113] The following abbreviations are used in Tables 1 and 2.
[0114] "DMPA"; 2,2'-Dimethylolpropionic acid
[0115] "PC"; Polycarbonate polyol
[0116] "PEt"; Polyether polyol
[0117] "PEs"; Polyester polyol
[0118] "EG"; Ethylene glycol
[0119] "MDI"; Diphenylmethane diisocyanate
[0120] "B-1"; Polyoxyethylene distyrenated phenyl ether
[0121] "H.sub.12MDI"; Dicyclohexylmethane diisocyanate
[0122] "EDA"; Ethylenediamine
[0123] "NaCl"; Sodium chloride
[0124] The aqueous urethane resin compositions prepared in Examples
1 to 3, which were the aqueous urethane resin compositions
according to the present invention, had excellent water-dispersion
stability and an excellent thermal coagulation property and hardly
detached from the fiber base. Furthermore, the coating films
prepared using the aqueous urethane resin compositions prepared in
Examples 1 to 3 did not become discolored and had an excellent
feeling, that is, flexibility and resilience.
[0125] On the other hand, the aqueous urethane resin composition
prepared in Comparative Example 1, which included, as a urethane
resin (A), a nonionic urethane resin prepared without using the
polyol (a1-1) including a carboxyl group, significantly detached
from the fiber base.
[0126] The aqueous urethane resin composition prepared in
Comparative Example 2, which did not include the nonionic
emulsifier (B), was coagulated at ordinary temperature after being
mixed with the coagulant (D). Therefore, it was not possible to
perform thermal coagulation of the urethane resin composition.
[0127] The aqueous urethane resin composition prepared in
Comparative Example 3, which was prepared as in Comparative Example
2 except that the type of urethane resin (A) used was changed,
significantly detached from the fiber base.
[0128] The aqueous urethane resin composition prepared in
Comparative Example 4, which was prepared using dicyclohexylmethane
diisocyanate instead of the aromatic polyisocyanate (a3), formed a
paper-like coating film having a poor feeling.
[0129] The aqueous urethane resin composition prepared in
Comparative Example 5, in which the content of urea linkage in the
urethane resin exceeded the limit specified in the present
invention, formed a paper-like coating film having a poor feeling.
In addition, discoloration of the coating film was severe.
* * * * *