U.S. patent application number 17/419635 was filed with the patent office on 2022-03-17 for waterborne polyurethane dispersion and method for preparing the same.
The applicant listed for this patent is Dow Global Technologies LLC, Dow Silicones Corporation. Invention is credited to Yanli Feng, Xiaolian Hu, Biao Ma, Lili Shi, Xiangyang Tai, Jiawen Xiong, Chao Zhang.
Application Number | 20220081588 17/419635 |
Document ID | / |
Family ID | 1000006035589 |
Filed Date | 2022-03-17 |
United States Patent
Application |
20220081588 |
Kind Code |
A1 |
Hu; Xiaolian ; et
al. |
March 17, 2022 |
WATERBORNE POLYURETHANE DISPERSION AND METHOD FOR PREPARING THE
SAME
Abstract
Provided is a waterborne polyurethane dispersion. The waterborne
polyurethane dispersion is prepared in the presence of a
hydrophilic amino siloxane compound and exhibits good
anti-stickiness while retaining superior mechanical properties. A
laminated synthetic leather article prepared with said waterborne
polyurethane dispersion as well the method for preparing the
synthetic leather article are also provided.
Inventors: |
Hu; Xiaolian; (Shanghai,
CN) ; Zhang; Chao; (Shanghai, CN) ; Tai;
Xiangyang; (Shanghai, CN) ; Feng; Yanli;
(Shanghai, CN) ; Shi; Lili; (Shanghai, CN)
; Xiong; Jiawen; (Shanghai, CN) ; Ma; Biao;
(Shanghai, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Dow Global Technologies LLC
Dow Silicones Corporation |
Midland
Midland |
MI
MI |
US
US |
|
|
Family ID: |
1000006035589 |
Appl. No.: |
17/419635 |
Filed: |
March 5, 2019 |
PCT Filed: |
March 5, 2019 |
PCT NO: |
PCT/CN2019/076936 |
371 Date: |
June 29, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08G 18/755 20130101;
B32B 2262/065 20130101; C08G 18/0866 20130101; B32B 2437/00
20130101; D06N 2209/10 20130101; B32B 2262/0276 20130101; B32B
2266/0278 20130101; B32B 5/245 20130101; C09D 175/08 20130101; B32B
5/024 20130101; C08G 18/4829 20130101; D06N 3/005 20130101; B32B
2601/00 20130101; C08G 18/4288 20130101; B32B 27/20 20130101; B32B
27/40 20130101; B32B 2307/732 20130101; B32B 5/026 20130101; D06N
2211/106 20130101; B32B 5/18 20130101; B32B 2262/0253 20130101;
B32B 2262/0223 20130101; B32B 5/02 20130101; B32B 27/12 20130101;
B32B 2437/02 20130101; C08G 18/4804 20130101; B32B 2262/0261
20130101; B32B 2262/0246 20130101; B32B 27/08 20130101; D06N
2211/14 20130101; B32B 2262/101 20130101; D06N 2211/10 20130101;
B32B 2262/10 20130101; C08G 18/24 20130101; B32B 2262/0238
20130101; B32B 5/022 20130101; C08G 18/4018 20130101; D06N 3/145
20130101; C08G 18/12 20130101; D06N 3/0095 20130101 |
International
Class: |
C09D 175/08 20060101
C09D175/08; C08G 18/12 20060101 C08G018/12; C08G 18/24 20060101
C08G018/24; C08G 18/48 20060101 C08G018/48; C08G 18/42 20060101
C08G018/42; C08G 18/40 20060101 C08G018/40; C08G 18/75 20060101
C08G018/75; C08G 18/08 20060101 C08G018/08; D06N 3/14 20060101
D06N003/14; D06N 3/00 20060101 D06N003/00; B32B 5/02 20060101
B32B005/02; B32B 27/12 20060101 B32B027/12; B32B 27/08 20060101
B32B027/08; B32B 27/40 20060101 B32B027/40; B32B 5/24 20060101
B32B005/24; B32B 5/18 20060101 B32B005/18 |
Claims
1. A waterborne polyurethane dispersion comprising polyurethane
particles dispersed in water, wherein the waterborne polyurethane
dispersion is derived from: (A) an isocyanate component comprising
one or more compounds having at least two isocyanate groups; (B) an
isocyanate-reactive component comprising one or more compounds
having at least two isocyanate-reactive groups; (C) a hydrophilic
amino siloxane compound represented by Formula I: ##STR00004##
wherein each R independently represents methyl, ethyl, n-propyl,
i-propyl, n-butyl, i-butyl, sec-butyl, t-butyl, n-pentyl, i-pentyl,
tert-pentyl, neo-pentyl, cyclohexyl, phenyl, vinyl, allyl or
--(OCH.sub.2CH.sub.2).sub.a--O--CH.sub.2--CH.dbd.CH.sub.2; R.sub.1
is --(CH.sub.2).sub.mNH.sub.2 or
--(CH.sub.2).sub.s--NH--(CH.sub.2).sub.tNH.sub.2; R.sub.2 is
--CH.sub.2CH.sub.2CH.sub.2O(CH.sub.2CH.sub.2O).sub.nH; and each of
R.sub.3, R.sub.4, R.sub.5, R.sub.6 and R.sub.7 is independently
selected from the group consisting of methyl, ethyl, n-propyl,
i-propyl, n-butyl, i-butyl, sec-butyl, t-butyl, n-pentyl, i-pentyl,
tert-pentyl, neo-pentyl, cyclohexyl and phenyl; wherein a is an
integer of 1 to 10; x is an integer of 20-500; y is an integer of
1-10; z is an integer of 1-10; m is an integer of 1-5; s is an
integer of 1, 2, 3, 4 or 5; t is an integer of 1, 2, 3, 4 or 5; and
n is an integer of 5-20; and wherein the content of the hydrophilic
amino siloxane compound (C) is from 2.0 wt % to 10 wt %, based on
the total weight of the isocyanate component (A), the
isocyanate-reactive component (B), and the catalyst (D); (D) a
catalyst; (E) a surfactant; (F) a chain extender; and (G)
water.
2. The waterborne polyurethane dispersion according to claim 1,
wherein there is no cationic or anionic hydrophilic pendant groups
or groups which can be converted into the cationic or anionic
hydrophilic pendant groups covalently attached to the backbone
chain of polyurethane in the polyurethane particles, and the
polyurethane is externally emulsified.
3. The waterborne polyurethane dispersion according to claim 1,
wherein the one or more compounds having at least two isocyanate
groups are selected from the group consisting of: a) C4-C12
aliphatic polyisocyanates comprising at least two isocyanate
groups, C6-C15 cycloaliphatic or aromatic polyisocyanates
comprising at least two isocyanate groups, C7-C15 araliphatic
polyisocyanates comprising at least two isocyanate groups, and a
combination thereof; and b) an isocyanate prepolymer prepared by
reacting one or more polyisocyanates of a) with one or more
isocyanate-reactive components selected from the group consisting
of C2-C16 aliphatic polyhydric alcohols comprising at least two
hydroxy groups, C6-C15 cycloaliphatic or aromatic polyhydric
alcohols comprising at least two hydroxy groups, C7-C15 araliphatic
polyhydric alcohols comprising at least two hydroxy groups,
polyester polyols having a molecular weight from 500 to 5,000,
polycarbonate diols having a molecular weight from 200 to 5,000,
polyetherdiols having a molecular weight from 200 to 5,000, C2 to
C10 polyamine comprising at least two amino groups, C2 to C10
polythiol comprising at least two thiol groups, C2-C10 alkanolamine
comprising at least one hydroxyl group and at least one amino
groups, and a combination thereof, with the proviso that the
isocyanate prepolymer comprises at least two free isocyanate
terminal groups.
4. The waterborne polyurethane dispersion according to claim 1,
wherein the content of the isocyanate component (A) is from 5 wt %
to 50 wt %, based on the total weight of the isocyanate component
(A), the isocyanate-reactive component (B) and the catalyst
(D).
5. The waterborne polyurethane dispersion according to claim 1,
wherein the one or more compounds having at least two
isocyanate-reactive groups are selected from the group consisting
of: C2-C16 aliphatic polyhydric alcohols comprising at least two
hydroxy groups, C6-C15 cycloaliphatic or aromatic polyhydric
alcohols comprising at least two hydroxy groups, C7-C15 araliphatic
polyhydric alcohols comprising at least two hydroxy groups,
polyester polyols having a molecular weight from 500 to 5,000,
polycarbonate diols having a molecular weight from 200 to 5,000,
polyetherdiols having a molecular weight from 200 to 5,000, C2 to
C10 polyamine comprising at least two amino groups, C2 to C10
polythiol comprising at least two thiol groups, C2-C10 alkanolamine
comprising at least one hydroxyl group and at least one amino
groups, vegetable oil having at least two hydroxyl groups, and a
combination thereof.
6. The waterborne polyurethane dispersion according to claim 1,
wherein the content of the isocyanate-reactive component (B) is
from 50 wt % to 95 wt %, based on the total weight of the
isocyanate component (A), the isocyanate-reactive component (B) and
the catalyst (D).
7. The waterborne polyurethane dispersion according to claim 1,
wherein the catalyst (D) is selected from the group consisting of:
organotin compound, organic dismuth compound, tertiary amine,
morpholine derivative, piperazine derivative, and combination
thereof; and wherein the content of the catalyst (D) is 1.0 wt % or
less, based on the total weight of the isocyanate component (A),
the isocyanate-reactive component (B) and the catalyst (D).
8. The waterborne polyurethane dispersion according to claim 1,
wherein the surfactant (E) is selected from the group consisting
of: poly(oxy-1,2-ethanediyl) .alpha.-sulfo-.omega.(nonylphenoxy)
salt, alkali metal oleates and stearates, alkali metal C12-C16
alkyl sulfates, amine C.sub.12-C.sub.16 alkyl sulfates, alkali
metal C.sub.12-C.sub.16 alkyl benzene sulfonates, amine
C.sub.12-C.sub.16 alkyl benzene sulfonates, fluorinated
C.sub.4-C.sub.16 alkyl esters, alkali metal C.sub.4-C.sub.16
perfluoroalkyl sulfonates, and the combination thereof; and wherein
the content of the surfactant (E) is 10 wt % or less, based on the
total weight of the isocyanate component (A), the
isocyanate-reactive component (B) and the catalyst (D).
9. The waterborne polyurethane dispersion according to claim 1,
wherein the chain extender (F) is selected from the group
consisting of: C.sub.2-C.sub.16 aliphatic polyamine comprising at
least two amine groups, C.sub.4-C.sub.15 cycloaliphatic or aromatic
polyamine comprising at least two amine groups, C.sub.7-C.sub.15
araliphatic polyamine comprising at least two amine groups; and
wherein the content of the chain extender (F) is from 1.0 wt % to
15 wt %, based on the total weight of the isocyanate component (A),
the isocyanate-reactive component (B) and the catalyst (D).
10. The waterborne polyurethane dispersion according to claim 1,
wherein the waterborne polyurethane dispersion has a solid content
of 5 wt % to 50 wt %, based on the total weight of the waterborne
polyurethane dispersion; and the polyurethane particles have a
volume average particle size of 20 nm to 5 .mu.m.
11. A method for preparing the waterborne polyurethane dispersion
according to claim 1, the method comprising (i) reacting the
isocyanate component (A) with the isocyanate-reactive component (B)
in the presence of the catalyst (D) to form a prepolymer; and (ii)
reacting the prepolymer with the hydrophilic amino siloxane
compound (C) and the chain extender (F) in the presence of the
surfactant (E) and water (G) to form the waterborne polyurethane
dispersion.
12. A synthetic leather article, comprising, from top to bottom: a
polyurethane skin film derived from the waterborne polyurethane
dispersion according to claim 1; a base layer derived from a 2k PU
composite composition; and an optional backing substrate, wherein
the polyurethane skin film directly contacts with the base layer,
and the backing substrate, when present, directly contacts with the
base layer.
13. A method for preparing a synthetic leather article comprising:
a) providing the waterborne polyurethane dispersion according to
claim 1; b) forming the polyurethane skin film with the waterborne
polyurethane dispersion; c) applying the 2k PU composite
composition onto one side of the polyurethane skin film to form the
base layer; and d) optionally, applying the backing substrate onto
one side of the base layer opposite the polyurethane skin film.
Description
FIELD OF THE INVENTION
[0001] The present disclosure relates to a waterborne polyurethane
dispersion and a method for preparing the same, a laminated
synthetic leather article comprising a skin film derived from the
waterborne polyurethane dispersion and a method for preparing the
same. The laminated synthetic leather article prepared by said
waterborne polyurethane dispersion exhibits superior
anti-stickiness and mechanical properties.
INTRODUCTION
[0002] Synthetic leather gets popular applications in people's
daily life, from clothes, footwear, bag and luggage, home
upholstery to seats in automobile. It provides similar performance
and hand feeling to natural leather with much better cost
advantage. Synthetic leather is fabricated by coating polymer(s) on
a fabric substrate or impregnating polymer(s) into a fabric
substrate, and the most commonly used polymer is polyurethane.
Traditional processes are performed with the solution of
polyurethane resin(s) in volatile organic solvents such as
dimethylformamide (DMF), methylethyl ketone (MEK) and toluene.
Porous structure of PU is created by precipitating PU polymer chain
in a controlled manner through leading the coated or impregnated
fabric substrate into water bath. Such a porous structure is very
critical and essential to endow the synthetic leather with a
similar hand feeling as that of natural leather. However, the
volatile organic solvents are very hazardous to plant operators,
consumers and environment. Therefore, synthetic leather industry is
pushed to solvent free fabrication process, to minimize the use of
volatile organic solvents in the manufacturing of PU synthetic
leather.
[0003] Waterborne polyurethane dispersion (PUD) is a green
alternative to PU solution in the volatile organic solvents such as
DMF. Currently, most of the waterborne PUD's are based on polyester
polyol and aliphatic isocyanates due to their good mechanical
properties (such as tensile strength and modulus). However,
polyester polyol based PUD's have many problems, e.g. poor
hydrolysis resistance, high cost and low dispersity in water due to
high viscosity of polyester prepolymer). Polyether polyol based
PUD's don't have such problems, but the mechanical properties and
anti-stickiness performance are poor due to the intrinsic softness
of polyether polyol. A newly developed technology for producing a
synthetic leather is to laminate a externally emulsified skin layer
derived from a polyurethane dispersion with a non-solvent 2k PU
foam layer, but the skin layer of the laminated synthetic leather
exhibits unfavorable anti-stickiness performance which cannot meet
the requirements of the synthetic leather application as any slight
stickiness in the skin film would not be acceptable to the
customer.
[0004] After persistent exploration, we have surprisingly found
that siloxane compound with both hydrophilic group and amine group
can be used in the preparation of said PUD and impart the resultant
synthetic leather article with significantly improved
anti-stickiness performance while maintaining good PUD film
mechanical properties like tensile strength, elongation and
modulus.
SUMMARY OF THE INVENTION
[0005] The present disclosure provides a unique waterborne
polyurethane dispersion and a laminated synthetic leather article
prepared by using the same.
[0006] In a first aspect of the present disclosure, the present
disclosure provides a waterborne polyurethane dispersion comprising
polyurethane particles dispersed in water, wherein the waterborne
polyurethane dispersion is derived from:
[0007] (A) an isocyanate component comprising one or more compounds
having at least two isocyanate groups;
[0008] (B) an isocyanate-reactive component comprising one or more
compounds having at least two isocyanate-reactive groups;
[0009] (C) a hydrophilic amino siloxane compound represented
Formula I:
##STR00001##
[0010] wherein each R independently represents methyl, ethyl,
n-propyl, i-propyl, n-butyl, butyl, sec-butyl, t-butyl, n-pentyl,
i-pentyl, tert-pentyl, neo-pentyl, cyclohexyl, phenyl, vinyl, allyl
or --(OCH.sub.2CH.sub.2).sub.a--O--CH.sub.2--CH.dbd.CH.sub.2;
[0011] R.sub.1 is --(CH.sub.2).sub.mNH.sub.2 or
--(CH.sub.2).sub.s--NH--(CH.sub.2).sub.tNH.sub.2;
[0012] R.sub.2 is
--CH.sub.2CH.sub.2CH.sub.2O(CH.sub.2CH.sub.2O).sub.nH, and
[0013] each of R.sub.3, R.sub.4, R.sub.5, R.sub.6 and R.sub.7 is
independently selected from the group consisting of methyl, ethyl,
n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, t-butyl, n-pentyl,
i-pentyl, tert-pentyl, neo-pentyl, cyclohexyl and phenyl;
[0014] wherein a is an integer of 1 to 10; x is an integer of
20-500; y is an integer of 1-10; z is an integer of 1-10; m is an
integer of 1-5; s is an integer of 1, 2, 3, 4 or 5; t is an integer
of 1, 2, 3, 4 or 5; and n is an integer of 5-20;
[0015] (D) a catalyst;
[0016] (E) a surfactant;
[0017] (F) a chain extender; and
[0018] (G) water.
[0019] According to a preferable embodiment of the present
disclosure, the waterborne polyurethane dispersion is an externally
emulsified polyurethane that does not comprise cationic or anionic
hydrophilic pendant group or a group which can be converted into
the cationic or anionic hydrophilic pendant group covalently
attached to the backbone chain of the polyurethane.
[0020] In a second aspect of the present disclosure, the present
disclosure provides a method for producing the waterborne
polyurethane dispersion of the first aspect, comprising (i)
reacting the isocyanate component (A) with the isocyanate-reactive
component (B) in the presence of the catalyst (D) to form a
prepolymer comprising free isocyanate groups; and (ii) reacting the
prepolymer with the hydrophilic amino siloxane compound (C) and the
chain extender (F) in the presence of the surfactant (E) and water
(G) to form the waterborne polyurethane dispersion.
[0021] In a third aspect of the present disclosure, the present
disclosure provides a synthetic leather article, comprising, from
top to bottom:
[0022] a polyurethane skin film derived from the waterborne
polyurethane dispersion of the first aspect;
[0023] a base layer derived from a 2k PU composite composition;
and
[0024] an optional backing substrate.
[0025] In a fourth aspect of the present disclosure, the present
disclosure provides a method for preparing the synthetic leather
article of the third aspect, comprising:
[0026] a) providing the waterborne polyurethane dispersion of the
first aspect;
[0027] b) forming the polyurethane skin film with the waterborne
polyurethane dispersion;
[0028] c) applying the 2k PU composite composition onto one side of
the polyurethane skin film to form the base layer; and
[0029] d) optionally, applying the backing substrate onto one side
of the base layer opposite the polyurethane skin film.
[0030] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory only and are not restrictive of the invention, as
claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] FIG. 1 is a schematic illustration of a cross-section of one
embodiment of a synthetic leather article described herein.
DETAILED DESCRIPTION OF THE INVENTION
[0032] Unless defined otherwise, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which the invention belongs. Also, all
publications, patent applications, patents, and other references
mentioned herein are incorporated by reference.
[0033] As disclosed herein, the term "composition", "formulation"
or "mixture" refers to a physical blend of different components,
which is obtained by mixing simply different components by a
physical means.
[0034] As disclosed herein, "and/or" means "and, or as an
alternative". All ranges include endpoints unless otherwise
indicated.
[0035] The Isocyanate Component
[0036] In various embodiments, the isocyanate component (A) has an
average functionality of at least about 2.0, preferably from about
2 to 10, more preferably from about 2 to about 8, and most
preferably from about 2 to about 6. In some embodiments, the
isocyanate component includes a polyisocyanate compound comprising
at least two isocyanate groups. Suitable polyisocyanate compounds
include aromatic, aliphatic, cycloaliphatic and araliphatic
polyisocyanates having two or more isocyanate groups. In a
preferable embodiment, the polyisocyanate component comprises
polyisocyanate compounds selected from the group consisting of
C.sub.4-C.sub.12 aliphatic polyisocyanates comprising at least two
isocyanate groups, C.sub.6-C.sub.15 cycloaliphatic or aromatic
polyisocyanates comprising at least two isocyanate groups,
C.sub.7-C.sub.15 araliphatic polyisocyanates comprising at least
two isocyanate groups, and combinations thereof. In another
preferable embodiment, suitable polyisocyanate compounds include
m-phenylene diisocyanate, 2,4-toluene diisocyanate and/or
2,6-toluene diisocyanate (TDI), the various isomers of
diphenylmethanediisocyanate (MDI), carbodiimide modified MDI
products, hexamethylene-1,6-diisocyanate,
tetramethylene-1,4-diisocyanate, cyclohexane-1,4-diisocyanate,
hexahydrotoluene diisocyanate, hydrogenated MDI,
naphthylene-1,5-diisocyanate, isophorone diisocyanate (IPDI), or
mixtures thereof.
[0037] Alternatively or additionally, the polyisocyanate component
may also comprise a isocyanate prepolymer having an isocyanate
functionality in the range of 2 to 10, preferably from 2 to 8, more
preferably from 2 to 6. The isocyanate prepolymer can be obtained
by reacting the above stated monomeric isocyanate components with
one or more isocyanate-reactive compounds selected from the group
consisting of ethylene glycol, 1,2-propanediol, 1,3-propanediol,
1,3-butanediol, 1,4-butenediol, 1,4-butynediol, 1,5-pentanediol,
neopentyl-glycol, bis(hydroxy-methyl) cyclohexanes such as
1,4-bis(hydroxymethyl)cyclohexane, 2-methylpropane-1,3-diol,
methylpentanediols, diethylene glycol, triethylene glycol,
tetraethylene glycol, polyethylene glycol, dipropylene glycol,
polypropylene glycol, dibutylene glycol and polybutylene glycols.
Suitable prepolymers for use as the polyisocyanate component are
prepolymers having NCO group contents of from 2 to 40 weight
percent, more preferably from 4 to 30 weight percent. These
prepolymers are preferably prepared by reaction of the di- and/or
poly-isocyanates with materials including lower molecular weight
diols and triols. Individual examples are aromatic polyisocyanates
containing urethane groups, preferably having NCO contents of from
5 to 40 weight percent, more preferably 20 to 35 weight percent,
obtained by reaction of diisocyanates and/or polyisocyanates with,
for example, lower molecular weight diols, triols, oxyalkylene
glycols, dioxyalkylene glycols, or polyoxyalkylene glycols having
molecular weights up to about 800. These polyols can be employed
individually or in mixtures as di- and/or polyoxyalkylene glycols.
For example, diethylene glycols, dipropylene glycols,
polyoxyethylene glycols, ethylene glycols, propylene glycols,
butylene glycols, polyoxypropylene glycols and
polyoxypropylene-polyoxyethylene glycols can be used. Polyester
polyols can also be used, as well as alkane diols such as butane
diol. Other diols also useful include bishydroxyethyl- or
bishydroxypropyl-bisphenol A, cyclohexane dimethanol, and
bishydroxyethyl hydroquinone.
[0038] Also advantageously used for the isocyanate component are
the so-called modified multifunctional isocyanates, that is,
products which are obtained through chemical reactions of the above
isocyanates compounds. Exemplary are polyisocyanates containing
esters, ureas, biurets, allophanates and preferably carbodiimides
and/or uretoneimines. Liquid polyisocyanates containing
carbodiimide groups, uretoneimines groups and/or isocyanurate
rings, having isocyanate groups (NCO) contents of from 12 to 40
weight percent, more preferably from 20 to 35 weight percent, can
also be used. These include, for example, polyisocyanates based on
4,4'- 2,4'- and/or 2,2'-diphenylmethane diisocyanate and the
corresponding isomeric mixtures, 2,4- and/or
2,6-toluenediisocyanate and the corresponding isomeric mixtures;
mixtures of diphenylmethane diisocyanates and PMDI; and mixtures of
toluene diisocyanates and PMDI and/or diphenylmethane
diisocyanates.
[0039] Generally, the amount of the isocyanate component may vary
based on the actual requirement of the synthetic leather article.
For example, as one illustrative embodiment, the content of the
isocyanate component can be from about 5 wt % to about 50 wt %,
preferably from about 10 wt % to about 40 wt %, preferably from
about 15 wt % to about 30 wt %, based on the total weight of all
the components for preparing the prepolymer in the first stage,
i.e., based on the total weight of the isocyanate component (A),
the isocyanate-reactive component (B) and the catalyst (D).
[0040] The Isocyanate-Reactive Component
[0041] In various embodiments of the present disclosure, the
isocyanate-reactive component comprises one or more polyols
selected from the group consisting of aliphatic polyhydric alcohols
comprising at least two hydroxy groups, cycloaliphatic or aromatic
polyhydric alcohols comprising at least two hydroxy groups,
araliphatic polyhydric alcohols comprising at least two hydroxy
groups, polyether polyol, polyester polyol, vegetable oil having at
least two hydroxyl groups and mixture thereof. Preferably, the
polyol is selected from the group consisting of C2-C16 aliphatic
polyhydric alcohols comprising at least two hydroxy groups, C6-C15
cycloaliphatic or aromatic polyhydric alcohols comprising at least
two hydroxy groups, C7-C15 araliphatic polyhydric alcohols
comprising at least two hydroxy groups, polyester polyols having a
molecular weight from 100 to 5,000, polyether polyols having a
molecular weight from 1,500 to 12,000, and combinations thereof.
According to a preferable embodiment, the polyol comprises a
polyether polyols (e.g., a polyether polyols as stated above), a
castor oil, or a mixture thereof.
[0042] In a preferable embodiment, the isocyanate-reactive
component comprises a mixture of two or more different polyols,
such as a mixture of two or more polyether polyols, a mixture of
two or more polyester polyols, a mixture of at least one polyether
polyols with at least one polyester polyols, a mixture of two or
more vegetable oils having at least two hydroxyl groups, or a
mixture of a polyether polyols and a castor oil.
[0043] In an alternative embodiment, the isocyanate-reactive
component is a polyether polyols having a functionality (average
number of isocyanate-reactive groups, particularly, hydroxyl group,
in a polyol molecule) of 1.0 to 3.0 and a weight average molecular
weight (Mw) of 1,500 to 12,000 g/mol, preferably from 2,000 to
8,000 g/mol, more preferably from 2,000 to 6,000 g/mol.
[0044] The polyether polyols is generally prepared by
polymerization of one or more alkylene oxides selected from
propylene oxide (PO), ethylene oxide (EO), butylene oxide,
tetrahydrofuran and mixtures thereof, with proper starter molecules
in the presence of catalyst. Typical starter molecules include
compounds having at least 2, preferably from 4 to 8 hydroxyl groups
or having two or more primary amine groups in the molecule.
Suitable starter molecules are for example selected from the group
comprising aniline, EDA, TDA, MDA and PMDA, more preferably from
the group comprising TDA and PMDA, an most preferably TDA. When TDA
is used, all isomers can be used alone or in any desired mixtures.
For example, 2,4-TDA, 2,6-TDA, mixtures of 2,4-TDA and 2,6-TDA,
2,3-TDA, 3,4-TDA, mixtures of 3,4-TDA and 2,3-TDA, and also
mixtures of all the above isomers can be used. By way of starter
molecules having at least 2 and preferably from 2 to 8 hydroxyl
groups in the molecule it is preferable to use trimethylolpropane,
glycerol, pentaerythritol, castor oil, sugar compounds such as, for
example, glucose, sorbitol, mannitol and sucrose, polyhydric
phenols, resols, such as oligomeric condensation products of phenol
and formaldehyde and Mannich condensates of phenols, formaldehyde
and dialkanolamines, and also melamine. Catalyst for the
preparation of polyether polyols may include alkaline catalysts,
such as potassium hydroxide, for anionic polymerization or Lewis
acid catalysts, such as boron trifluoride, for cationic
polymerization. Suitable polymerization catalysts may include
potassium hydroxide, cesium hydroxide, boron trifluoride, or a
double cyanide complex (DMC) catalyst such as zinc
hexacyanocobaltate or quaternary phosphazenium compound. In a
preferable embodiment of the present disclosure, the polyether
polyol includes (methoxy) polyethylene glycol (MPEG), polyethylene
glycol (PEG), poly(propylene glycol) or copolymer of ethylene
epoxide and propylene epoxide with primary hydroxyl ended group and
secondary hydroxyl ended group.
[0045] In general, the content of the isocyanate-reactive component
used herein may range from about 50 wt % to about 95 wt %,
preferably from about 60 wt % to about 85 wt %, based on the total
weight of all the components for preparing the prepolymer in the
first stage, i.e., based on the total weight of the isocyanate
component (A), the isocyanate-reactive component (B) and the
catalyst (D).
[0046] Catalyst
[0047] Catalyst may include any substance that can promote the
reaction between the isocyanate group and the isocyanate-reactive
group. Without being limited to theory, the catalysts can include,
for example, glycine salts; tertiary amines; tertiary phosphines,
such as trialkylphosphines and dialkylbenzylphosphines; morpholine
derivatives; piperazine derivatives; chelates of various metals,
such as those which can be obtained from acetylacetone,
benzoylacetone, trifluoroacetyl acetone, ethyl acetoacetate and the
like with metals such as Be, Mg, Zn, Cd, Pd, Ti, Zr, Sn, As, Bi,
Cr, Mo, Mn, Fe, Co and Ni; acidic metal salts of strong acids such
as ferric chloride and stannic chloride; salts of organic acids
with variety of metals, such as alkali metals, alkaline earth
metals, Al, Sn, Pb, Mn, Co, Ni and Cu; organotin compounds, such as
tin(II) salts of organic carboxylic acids, e.g., tin(II) diacetate,
tin(II) dioctanoate, tin(II) diethylhexanoate, and tin(II)
dilaurate, and dialkyltin(IV) salts of organic carboxylic acids,
e.g., dibutyltin diacetate, dibutyltin dilaurate, dibutyltin
maleate and dioctyltin diacetate; bismuth salts of organic
carboxylic acids, e.g., bismuth octanoate; organometallic
derivatives of trivalent and pentavalent As, Sb and Bi and metal
carbonyls of iron and cobalt; or mixtures thereof.
[0048] Tertiary amine catalysts include organic compounds that
contain at least one tertiary nitrogen atom and are capable of
catalyzing the hydroxyl/isocyanate reaction. The tertiary amine,
morpholine derivative and piperazine derivative catalysts can
include, by way of example and not limitation, triethylenediamine,
tetramethylethylenediamine, pentamethyl-diethylene triamine,
bis(2-dimethylaminoethyl)ether, triethylamine, tripropylamine,
tributyl-amine, triamylamine, pyridine, quinoline,
dimethylpiperazine, piperazine, N-ethylmorpholine,
2-methylpropanediamine, methyltriethylenediamine,
2,4,6-tridimethylamino-methyl)phenol, N,N',N''-tris(dimethyl
amino-propyl)sym-hexahydro triazine, or mixtures thereof.
[0049] In general, the content of the catalyst used herein is
larger than zero and is at most 1.0 wt %, preferably at most 0.5 wt
%, more preferably at most 0.05 wt %, based on the total weight of
all the components for preparing the prepolymer in the first stage,
i.e., based on the total weight of the isocyanate component (A),
the isocyanate-reactive component (B) and the catalyst (D).
[0050] Hydrophilic Amino Siloxane Compound
[0051] The hydrophilic amino siloxane compound is a compound
comprising a silicon-oxygen back bone chain to which
nitrogen-containing side chain and hydrophilic side chain are
attached. The molecular structure of the hydrophilic amino siloxane
compound may be represented by Formula I:
##STR00002##
[0052] wherein each R independently represents methyl, ethyl,
n-propyl, i-propyl, n-butyl, butyl, s-butyl, t-butyl, n-pentyl,
i-pentyl, tert-pentyl, neo-pentyl, cyclohexyl, phenyl, vinyl, allyl
or --(OCH.sub.2CH.sub.2).sub.a--O--CH.sub.2--CH.dbd.CH.sub.2;
[0053] R.sub.1 is --(CH.sub.2).sub.mNH.sub.2 or
--(CH.sub.2).sub.s--NH--(CH.sub.2).sub.tNH.sub.2;
[0054] R.sub.2 is
--CH.sub.2CH.sub.2CH.sub.2O(CH.sub.2CH.sub.2O).sub.nH, and
[0055] each of R.sub.3, R.sub.4, R.sub.5, R.sub.6 and R.sub.7 is
independently selected from the group consisting of methyl, ethyl,
n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, t-butyl, n-pentyl,
i-pentyl, tert-pentyl, neo-pentyl, cyclohexyl and phenyl;
[0056] wherein a is an integer of 1 to 10; x is an integer of
20-200; y is an integer of 1-10; z is an integer of 1-10; m is an
integer of 1-5; s is an integer of 1, 2, 3, 4 or 5; t is an integer
of 1, 2, 3, 4 or 5; and n is an integer of 5-20.
[0057] Without being limited to theory, the amine group in R.sub.1
and the hydroxyl group in R.sub.2 may react with the remaining
isocyanate group in the prepolymer to produce a polyurethane
comprising the above siloxane structure in the polyurethane back
bone chain, thus significantly improve the anti-stickiness of the
resultant PU skin film.
[0058] According to one preferable embodiment of the present
disclosure, the hydrophilic amino siloxane compound has a structure
presented by Formula II:
##STR00003##
[0059] wherein R, R.sub.1, R.sub.2, x, y and z are as described
above.
[0060] In general, the content of the hydrophilic amino siloxane
compound used herein is from 2 wt % to 10 wt %, preferably from 2
wt % to 8 wt %, more preferably from 2 wt % to 5 wt %, based on the
total weight of all the components for preparing the prepolymer in
the first stage, i.e., based on the total weight of the isocyanate
component (A), the isocyanate-reactive component (B) and the
catalyst (D). It can be seen that the content of the hydrophilic
amino siloxane compound is calculated as an additional amount while
taking the total amount of the prepolymer as 100 wt %.
[0061] It's noted that the hydrophilic amino siloxane compound
should be firstly dissolved/dispersed in water via mixing to get an
aqueous solution and then degassed. In this invention, the amino
silicone oil was added during the dispersion stage and was not
added into polymer backbone during the prepolymer synthesis. The
reason is that some degree of polymer gel will be formed if the
siloxane was added during the prepolymer synthesis stage.
[0062] Surfactant
[0063] According to a preferable embodiment, the waterborne
polyurethane dispersion is an externally emulsified dispersion,
i.e., the waterborne polyurethane dispersion is preferably prepared
exclusively by using "external surfactant/emulsifier" and
substantially comprises no "internal surfactant/emulsifier".
[0064] The expression "externally emulsified polyurethane
dispersion" as described herein refers to a polyurethane dispersion
comprising limited amount of internally emulsifying ionic
components and thus mainly relying on the emulsifying function of
"external surfactant/emulsifier" [i.e. ionically or nonionically
emulsifiers that are not covalently bonded to the backbone chain
within the polyurethane particles dispersed in the liquid medium,
especially via the urethane bond derived from the reaction between
an isocyanate group and an isocyanate-reactive group (such as a
hydroxyl group)] so as to stabilize the polyurethane
dispersion.
[0065] According to one embodiment of the present disclose, the
externally emulsified polyurethane dispersion is prepared by (i)
reacting one or more monomeric or prepolymeric polyisocyanates with
one or more compounds having at least two isocyanate-reactive
groups as stated above to form a prepolymer comprising an urethane
prepolymer chain and at least one, preferably at least two free
isocyanate groups per molecule; (ii) dispersing the prepolymer
obtained in step (i) in an aqueous solvent (e.g. water) with the
presence of the external emulsifier to form an emulsion and
optionally further adding the chain extender and the hydrophilic
amino siloxane compound into the emulsion to react with the
prepolymer obtained in step (i) and form the externally emulsified
polyurethane dispersion. According to one embodiment of the present
disclosure, the prepolymer prepared in the step (i) does not
comprise any ionic internal emulsifier or residual moieties of the
ionic internal emulsifier covalently bonded to the urethane
prepolymer chain. According to another embodiment of the present
disclosure, the polyurethane chain in the prepolymer prepared in
the step (i) does not comprise any cationic or anionic pendant
group.
[0066] The PUD prepared by using an internal surfactant/emulsifier
is known as an "internally emulsified PUD". According to the
knowledge of the prior art, a typical process for preparing an
internally emulsified PUD comprises the steps of (i) reacting an
monomeric isocyanate or a prepolymer of the monomeric isocyanate
with polyols and cationic or anionic precursor which has at least
one isocyanate-reactive groups (i.e., an ionic internal emulsifier)
to form a PUD prepolymer comprising pendant cationic or anionic
hydrophilic groups attached to the PU chain; (ii) dispersing the
PUD prepolymer into an aqueous solvent (e.g. water), with the
cationic or anionic hydrophilic group attached to the PU chain as
main emulsifier, optionally with the assistance of additional
external emulsifier in this step; and optionally (iii) reacting the
emulsion with additional chain extender to form the ionic
internally emulsified polyurethane dispersion. It can be clearly
seen that the externally emulsified PUD used in the present
disclosure is completely different from the ionic internally
emulsified PUD of the prior art both in the preparation process and
the composition of the resultant polyurethane particles. It shall
be clarified that the polyurethane particles prepared by the
present application comprise residual groups of the chain extenders
and the hydrophilic amino siloxane compound attached to the
polyurethane main chain, but these residual groups are different
from the above stated ionic internal emulsification function groups
at least in the charge neutrality and hence shall be excluded from
the definition of the ionic internal emulsifying function groups.
Besides, in a preferable embodiment, the emulsifying of the
polyurethane is conducted mainly or solely by using the external
emulsifier, and the chain extender and hydrophilic amino siloxane
compound are not added until an emulsion of PU has been formed.
That is why the PU dispersion of the present disclosure is
identified as an externally emulsified system.
[0067] In one embodiment of the present disclosure, the above
stated ionic internal emulsifying component (emulsifier) is not
added during the preparation of the externally emulsified PUD. In a
preferable embodiment of the present disclosure, the externally
emulsified polyurethane dispersion is free of anionic or cationic
salt group in the backbone chain of the polyurethane prepolymer
particles dispersed in the externally emulsified PUD.
[0068] The waterborne polyurethane dispersion of the present
disclosure may be prepared by using any anionic surfactant,
cationic surfactant, amphoteric surfactant or non-ionic surfactant.
Suitable classes of surfactant include, but are not restricted to,
sulfates of ethoxylated phenols such as
poly(oxy-1,2-ethanediyl).alpha.-sulfo-.omega.(nonylphenoxy) salt;
alkali metal fatty acid salts such as alkali metal oleates and
stearates; alkali metal C.sub.12-C.sub.16 alkyl sulfates such as
alkali metal lauryl sulfates; amine C.sub.12-C.sub.16 alkyl
sulfates such as amine lauryl sulfates, more preferably
triethanolamine lauryl sulfate; alkali metal C.sub.12-C.sub.16
alkylbenzene sulfonates such as branched and linear sodium
dodecylbenzene sulfonates; amine C.sub.12-C.sub.16 alkyl benzene
sulfonates such as triethanolamine dodecylbenzene sulfonate;
anionic and nonionic fluorocarbon emulsifiers such as fluorinated
C.sub.4-C.sub.16 alkyl esters and alkali metal C.sub.4-C.sub.16
perfluoroalkyl sulfonates; organosilicon emulsifiers such as
modified polydimethylsiloxanes. Preferably, the surfactant is one
that can react with a multivalent cation present in a neutral salt
to form an insoluble multivalent cation water insoluble salt of an
organic acid. Exemplary preferred surfactant includes disodium
octadecyl sulfosuccinate, sodium dodecylbenzene sulfonate, sodium
stearate and ammonium stearate.
[0069] According to an embodiment of the present disclosure, the
content of the surfactant is larger than zero and no more than 10
wt %, preferably no more than 5 wt %, more preferably no more than
3.5 wt %, based on the total weight of all the components for
preparing the prepolymer in the first stage, i.e., based on the
total weight of the isocyanate component (A), the
isocyanate-reactive component (B) and the catalyst (D). It can be
seen that the content of the surfactant is calculated as an
additional amount while taking the total amount of the prepolymer
as 100 wt %.
[0070] Chain Extender
[0071] According to one embodiment of the present disclosure, the
chain extender may be a diamine or an amine compound having another
isocyanate reactive group, but is preferably selected from the
group consisting of: an aminated polyether diol; piperazine;
aminoethylethanolamine; C.sub.2-C.sub.16 aliphatic polyamine
comprising at least two amine groups, e.g., ethylenediamine;
C.sub.4-C.sub.15 cycloaliphatic or aromatic polyamine comprising at
least two amine groups, such as cyclohexanediamine and
p-xylenediamine; C.sub.7-C.sub.15 araliphatic polyamine comprising
at least two amine groups; aminated C.sub.2-C.sub.8 alcohol, e.g.,
ethanolamine; and mixtures thereof. According to a preferable
embodiment, the chain extender is a polyamine having a
functionality of 2 and comprising primary amine group or secondary
amine group. Preferably, the amine chain extender is dissolved in
the water used to make the PU dispersion.
[0072] According to an embodiment of the present disclosure, the
content of the chain extender is from 1.0 wt % to 15 wt %,
preferably from 2 wt % to 10 wt %, more preferably from 3 wt % to 9
wt %, based on the total weight of all the components for preparing
the prepolymer in the first stage, i.e., based on the total weight
of the isocyanate component (A), the isocyanate-reactive component
(B) and the catalyst (D). It can be seen that the content of the
chain extender is calculated as an additional amount while taking
the total amount of the prepolymer as 100 wt %.
[0073] The Waterborne Polyurethane Dispersion
[0074] According to an embodiment of the present application, the
waterborne polyurethane dispersion is prepared by a two-stage
reaction. In the first stage, a prepolymer is prepared by reacting
the isocyanate groups in the isocyanate component (A) with the
isocyanate-reactive groups in the isocyanate-reactive component (B)
in the presence of the catalyst (D). A polyurethane back bone chain
can be formed in the prepolymer by the above stated reaction. In
the second stage, the prepolymer is mixed with the surfactant (E)
and reacts with the chain extender (F) and the hydrophilic amino
siloxane compound (C). The chain extender (F) and the hydrophilic
amino siloxane compound (C) comprise isocyanate-reactive groups,
e.g. amine group, which react with the free isocyanate groups
remained in the prepolymer, hence their structural moieties are
also introduced into the resultant polyurethane back bone chain.
During the second stage, the chain of the prepolymer is further
extended by the chain extender (F) and the hydrophilic amino
siloxane compound (C) so as to form the waterborne polyurethane
dispersion comprising polyurethane particles dispersed in water.
The waterborne polyurethane dispersion may be heated and dried to
form a skin film exhibiting superior improved anti-stickiness
performance while maintaining good PUD film mechanical
properties.
[0075] The waterborne polyurethane dispersion may have any suitable
solids loading of polyurethane particles, but the solids loading is
generally between about 1% to about 70% solids by weight of the
total dispersion weight, preferably at least about 2%, more
preferably at least about 4%, more preferably at least about 6%,
more preferably at least about 15%, more preferably at least about
25%, more preferably at least about 35%, most preferably at least
about 40%, to at most about 70%, preferably at most 68%, more
preferably at most about 65%, more preferably at most about 60% and
most preferably at most about 50% by weight.
[0076] The waterborne polyurethane dispersion may also contain a
rheological modifier such as thickeners that enhance the
dispersability and stability of the dispersion. Any suitable
rheological modifier may be used such as those known in the art.
Preferably, the rheological modifier is one that does not cause the
dispersion to become unstable. More preferably, the rheological
modifier is a water soluble thickener that is not ionized. Examples
of useful rheological modifiers include methyl cellulose ethers,
alkali swellable thickeners (e.g., sodium or ammonium neutralized
acrylic acid polymers), hydrophobically modified alkali swellable
thickeners (e.g., hydrophobically modified acrylic acid copolymers)
and associative thickeners (e.g., hydrophobically modified
ethylene-oxide-based urethane block copolymers). Preferably the
rheological modifier is a methylcellulose ether. The amount of
thickener is from at least about 0.2% to about 5% by weight of the
total weight of the waterborne polyurethane dispersion, preferably
from about 0.5% to about 2% by weight.
[0077] Generally, the waterborne polyurethane dispersion has a
viscosity from at least about 10 cp to at most about 10,000 cp,
preferably, from at least about 20 cp to at most about 5000 cp,
more preferably, from at least about 30 cp to at most about 3000
cp.
[0078] In an embodiment of the present disclosure, the dispersion
of the PU particles in the waterborne polyurethane dispersion can
be promoted by the surfactant and high shear stirring action,
wherein the shear force and stirring speed can be properly adjusted
based on specific requirement.
[0079] According to one embodiment of the present disclosure, the
waterborne polyurethane dispersion may further comprise one or more
pigment, dyes and/or colorant, all of which are generally termed as
"color masterbatch" in the present disclosure. For example, the
color masterbatch may be added so as to impart a transparent or
translucent film with a desired color. Examples of pigments dyes
and/or colorants may include iron oxides, titanium oxide, carbon
black and mixtures thereof. The amount of the pigment, dyes and/or
colorant may be 0.1% to 15%, preferably 0.5-10%, more preferably 1%
to 5% by weight, based on the total weight of the waterborne
polyurethane dispersion. Suitable commercially available black
pigments useful in the present invention may include for example
EUDERM.TM. black B-N carbon black dispersion available from Lanxess
Deutschland GmbH.
[0080] The Laminated Synthetic Leather Article
[0081] FIG. 1 is a schematic illustration of a cross-section of one
embodiment of the synthetic leather article described herein. In
one embodiment of the present disclosure, the synthetic leather
article comprises, from top to bottom, a top skin film formed by
the waterborne polyurethane dispersion, a 2K PU foam base layer,
and a backing substrate (e.g. a textile fabric cloth). Please note
that the leather article is not necessarily shown in actual
proportion, and the dimensions of one or more layers may be
exaggerated so as to clearly show the configuration thereof.
[0082] The 2K PU foam used in the present disclosure is preferably
a non-solvent PU foam and comprises a continuous PU matrix that
defines a plurality of pores and/or cells therein. As disclosed
herein, the terms "solvent free", "solventless" or "non-solvent",
can be used interchangeably for describing the PU foam or any other
dispersion, mixture, etc., and shall be interpreted that the
mixture of all the raw materials used for preparing the PU foam or
PU dispersion comprise less than 3% by weight, preferably less than
2% by weight, preferably less than 1% by weight, more preferably
less than 0.5% by weight, more preferably less than 0.2% by weight,
more preferably less than 0.1% by weight, more preferably less than
100 ppm by weight, more preferably less than 50 ppm by weight, more
preferably less than 10 ppm by weight, more preferably less than 1
ppm by weight of any organic or inorganic solvents, based on the
total weight of the mixture of raw materials. As disclosed herein,
the term "solvent" refers to organic and inorganic liquids whose
function is solely dissolving one or more solid, liquid or gaseous
materials without incurring any chemical reaction. In other words,
although some organic compounds, e.g. ethylene glycol and propylene
glycol, and water, which are generally considered as "solvent" in
the polymerization technology, are used in the preparation of the
2k PU foam, none of them belongs to "solvent" since they mainly
function as isocyanate-reactive functional substance, chain
extending agent or foaming agent, etc. by incurring chemical
reactions.
[0083] According to one embodiment of the present disclosure, the
2k PU foam layer has a thickness in the range from 0.01 .mu.m to
2,000 .mu.m, preferably in the range from 0.05 .mu.m to 1,000
.mu.m, more preferably in the range from 0.1 .mu.m to 750 .mu.m and
more preferably in the range from 0.2 .mu.m to 600 .mu.m.
[0084] According to one embodiment of the present disclosure, the
foamed polyurethane in the polyurethane foam layer is prepared with
a solvent-free polyurethane system comprising (i) one or more
second isocyanate components, (ii) one or more second
isocyanate-reactive components, (iii) one or more foaming agent,
second catalyst and any other additives. The second isocyanate
component (i) includes one or more polyisocyanates and/or
isocyanate prepolymers which are used for the isocyanate component
(A). The second isocyanate-reactive components (ii) comprise
compounds having two or more isocyanate-reactive groups selected
from OH groups, SH groups, NH groups, NH.sub.2 groups and
carbon-acid groups, for example (3-diketo groups. According to one
embodiment of the present application, the isocyanate-reactive
components (ii) comprise those used for (B). In one preferred
embodiment of the present disclosure, the second isocyanate
components (i) and second the isocyanate-reactive components (ii)
react with each other in the presence of a foaming/blowing agent,
and the foaming agent is used in combination with the
isocyanate-reactive components. Useful foaming agents include
commonly known chemically or physically reactive compounds.
Physical blowing agents may be selected from one or more of a group
consisting of carbon dioxide, nitrogen, noble gases,
(cyclo)aliphatic hydrocarbons having from 4 to 8 carbon atoms,
dialkyl ethers, esters, ketones, acetal and fluoroalkanes having
from 1 to 8 carbon atoms. The chemically reactive blowing agent
preferably comprises water, which is preferably contained as a
constituent of the blend with the isocyanate-reactive components
(ii). The amount of the foaming agent is in the range from 0.05 to
10%, preferably in the range from 0.1 to 5%, more preferably from
0.1 to 2%, and most preferably from 0.1 to 0.5% by weight, based on
the overall weight of all the raw materials used for preparing the
2k PU foam layer. The 2K PU layer typically has a density of 0.3 to
1.1 kg/liter and preferably has a density of 0.4 to 0.9
kg/liter.
[0085] In an embodiment of the present disclosure, the second
isocyanate components (i) reacts with the second
isocyanate-reactive components (ii) in the presence of a catalyst
selected from organotin compounds, such as tin diacetate, tin
dioctoate, dibutyltin dilaurate, and/or strongly basic amines such
as diazabicyclooctane, triethylamine, triethylenediamine or
bis(N,N-dimethylaminoethyl) ether in an amount from 0.01% to 5% by
weight, preferably from 0.05% to 4% by weight, more preferably from
0.05% to 3% by weight, based on the overall weight of all the raw
materials used for preparing the 2k PU foam layer.
[0086] In an embodiment of the present disclosure, the categories
and molar contents of the second isocyanate components (i) and the
second isocyanate-reactive components (Bii) are particularly
selected so that the overall equivalence ratio of NCO groups to
NCO-reactive hydrogen atoms (e.g. hydrogen atom in the hydroxyl
group) is in the range from 0.9:1 to 1.8:1, preferably from 0.92:1
to 1.6:1, preferably in the range from 0.95:1 to 1.5:1, and more
preferably in the range from 1:1 to 1.45:1, more preferably in the
range from 1.05:1 to 1.4:1, and more preferably in the range from
1.10:1 to 1.35:1.
[0087] Release Layer
[0088] Suitable release layers are typically known in the prior art
as "release paper". Examples of suitable release layers include
foils of metal, plastic or paper. In one preferred embodiment of
the present disclosure, the release layer is a paper layer
optionally coated with a plastic membrane. Preferably, the paper
layer disclosed herein is coated with a polyolefin, more preferably
polypropylene. Alternatively, the paper layer is preferably coated
with silicone. In an alternative embodiment, the release layer used
herein is a PET layer optionally coated with plastic membrane.
Preferably, the PET layer can be is coated with a polyolefin, more
preferably polypropylene. Alternatively, the PET layer is
preferably coated with silicone. Examples of suitable release
layers are commercially available. The release layers used in the
present disclosure may have a flat, embossed or patterned surface
so that corresponding or complementary surface profile can be
formed on the outermost surface of the synthetic leather article.
Preferably, the release layer is textured in the mode of leather
grain so as to impart the synthetic leather article with good
haptic property comparable with that of high grade natural leather.
The release layer generally has a thickness of 0.001 mm to 10 mm,
preferably from 0.01 mm to 5 mm, and more preferably from 0.1 mm to
2 mm.
[0089] The material and the thickness of the release layer can be
properly adjusted, as long as the release layer is able to endure
the chemical reaction, mechanical processing and thermal treatments
experienced during the manufacturing procedures and can be readily
peeled from the resultant synthetic leather without bringing about
the delamination between the skin film and the 2k PU foam base
layer.
[0090] Auxiliary Agents and Additives The PU skin film and the 2K
PU foam base layer may independently and optionally comprise any
additional auxiliary agents and/or additives for specific
purposes.
[0091] In one embodiment of the present disclosure, one or more of
the auxiliary agents and/or additives may be selected from the
group consisting of fillers, cell regulators, release agents,
colorants/pigments, surface-active compounds, handfeeling agents,
dullers, thickeners, crosslinkers and stabilizers.
[0092] Examples of suitable fillers comprise glass fibers, mineral
fibers, natural fibers, such as flax, jute or sisal for example,
glass flakes, silicates such as mica or glimmer, salts, such as
calcium carbonate, chalk or gypsum. The fillers are typically used
in an amount from 0.5% to 60% by weight, preferably from 3% to 30%
by weight, and more preferably from 3% to 10% by weight, based on
the overall dry weight of the skin film or the 2K PU foam base
layer.
[0093] Backing Substrate
[0094] In an embodiment of the present disclosure, the backing
substrate has a thickness of in the range from 0.01 mm to 50 mm,
preferably in the range from 0.05 mm to 10 mm and more particularly
in the range from 0.1 mm to 5 mm. The backing substrate may
comprise one or more selected from the group consisting of fabric,
preferably woven or nonwoven fabric, impregnated fabrics, knit
fabric, braid fabric or microfiber; foil of metal or plastic, e.g.
rubber, PVC or polyamides; and leather, preferably split
leather.
[0095] The backing substrate can be made of a woven or nonwoven
textile. Preferably, the textile is a nonwoven textile. The textile
may be made by any suitable method such as those known in the art.
The textile may be prepared from any suitable fibrous material.
Suitable fibrous materials include, but are not limited to,
synthetic fibrous materials and natural or semi synthetic fibrous
materials and mixtures or blends thereof. Examples of synthetic
fibrous materials include polyesters, polyamides, acrylics,
polyolefins, polyvinyl chlorides, polyvinylidene chlorides,
polyvinyl alcohols and blends or mixtures thereof. Examples of
natural semi-synthetic fibrous materials include cotton, wool and
hemp.
[0096] Manufacture Technology
[0097] The waterborne polyurethane dispersion may be applied by
conventional coating technologies such as spraying coating, blade
coating, die coating, cast coating, etc.
[0098] The skin film can be either partially or completely dried
before the application of the next layer. Preferably, the skin film
is completely dried so as to minimize the moisture entrapped
therein, and then the next layer is applied thereon. In an
alternative embodiment of the present application, only part of the
moisture is removed from the skin film on the release layer, then
the skin film is completely dried together with the 2K PU foam
layer applied thereon.
[0099] According to one embodiment, the second isocyanate component
(i) and the second isocyanate-reactive component (ii) for the 2K
non-solvent PU foam are mixed together, applied to the skin film,
and pre-cured by being heated in an oven at a temperature of e.g.
from 70.degree. C. to 120.degree. C., preferably from 75.degree. C.
to 110.degree. C. for a short duration of 10 seconds to 5 minutes,
preferably from 30 seconds to 2 minutes, more preferably from 45 to
90 seconds. Then the backing substrate (e.g. a textile fabric) is
applied to the pre-cured 2k PU foam layer with the assistance of a
pressing roller, followed by being post cured at a higher
temperature of e.g. from 100.degree. C. to 160.degree. C.,
preferably from 110.degree. C. to 150.degree. C. for a longer
duration of 3 to 20 minutes, preferably from 3 to 15 minutes, more
preferably from 4 to 10 minutes. The above stated two-step curing
process aims to ensure high adhesion strength between the pre-cured
2k PU foam and the backing substrate.
[0100] According to a preferable embodiment of the present
disclosure, the release layer is removed after the 2k PU foam has
been fully cured. The release layer can be peeled off via any
ordinary technologies.
[0101] According to a preferable embodiment of the present
disclosure, after the removal of the release layer, a top finishing
layer can be applied onto the surface of the synthetic leather
(i.e. on the outermost surface of the skin film) and dried to form
a protection film layer. The presence of the finishing layer can
further increase abrasion resistance of the multilayer synthetic
leather. The protection film layer may be formed by using any
suitable raw materials and technologies. The finishing layer may
optionally comprise additives such as wetting agent, crosslinking
agent, binder, matting agent, hand-feel modifier, pigments and/or
colorants, thickener or other additives used for the skin film. The
synthetic leather disclosed herein can further comprise one or more
than one optional additional layer such as a color layer between
the skin film and the finishing layer. Other suitable optional
additional layers can be selected from a water repellent layer, UV
protective layer and tactile (touch/feel) modification layer. The
process of the present invention may be carried out continuously or
batchwise.
[0102] The multilayer structure synthetic leather disclosed herein
can be cut or otherwise shaped so as to have a shape suitable for
any desired purpose, such as shoe manufacturing. Depending on the
intended application, the synthetic leathers can be further treated
or post-treated similarly to natural leathers, for example by
brushing, filling, milling or ironing. If desired, the synthetic
leathers may (like natural leather) be finished with the customary
finishing compositions. This provides further possibilities for
controlling their character. The multilayer structure disclosed
herein may be used in various applications particularly suitable
for use as synthetic leather, for example, footwear, handbags,
belts, purses, garments, furniture upholstery, automotive
upholstery, and gloves. The multilayer structure is particular
suitable for use in automotive applications.
EXAMPLES
[0103] Some embodiments of the invention will now be described in
the following Examples, wherein all parts and percentages are by
weight unless otherwise specified.
[0104] The information of the raw materials used in the examples is
listed in the following table 1:
TABLE-US-00001 TABLE 1 Raw materials used in the following examples
Raw Material Description Supplier Isophorone diisocyanate (IPDI)
Aliphatic isocyanate, functionality = 2 Evonik T12 Catalyst
(organic tin) Air Product Voranol 222-056 polyol Ether polyol, Mw =
2000, EO capped, EO Dow Chemical content = 12 wt. %, Functionality
= 2 Voranol 4000LM polyol Ether polyol, Mw = 4000, Functionality =
2 Dow Chemical Voranol 4240 polyol Ether polyol, Mw = 4000, EO
capped, EO Dow Chemical content = 16.9 wt. %, Functionality = 2
Castor oil Polyol, with a OH value of 163 mg -- KOH/g,
Functionality = 2.7 MPEG1000 Ether polyol, Mw = 2000, Functionality
= 1 Sinopharm. Piperazine chain extender, functionality = 2
Sinopharm. Sodium dodecyl benzene Surfactant Sinopharm sulfonate
(SDBS) Deionized water Medium N.A. OFX-7700 a hydrophilic amino
siloxane compound Dow Chemical of the present application OFX-8209
a hydrophobic amino siloxane compound Dow Chemical Euderm Black B-N
Black color master batch Lanxess Acrysol RM 825 Thickener Dow
Chemical 1,2-Propanediol (PG) Fast drying agent Sinopharm A2
additive A mixture of silicone and fluorine based Dow/DuPont
slipping agent Polyol in 2k PU composite See, Table 2 Dow Chemical
Prepolymer in 2k PU composite Voralast* GE 143 ISO Dow Chemical
[0105] The 2K non-solvent PU foam is prepared by combining the
isocyanate prepolymer (Voralast.TM. GE 143 ISO) shown in table 1
and the raw materials listed in table 2.
TABLE-US-00002 TABLE 2 Raw Materials used in 2k PU copmposite
Materials Content/% Vendor SPECFLEXTM .TM. NC 701 28 Dow Chemical
VORANOL .TM. CP 6001 46 Dow Chemical VORANOL .TM. 4240/EP 1900 18
Dow Chemical Dipropylene glycol 4 Dow Chemical Ethylene glycol 3
Dow Chemical WATER 0.22 N.A. Dow Corning 193 0.5 Dow Chemical
Polycat SA2LE 0.2 Evonik Polycat SA-1 0.04 Evonik Niax C-225 0.02
Evonik Mixing ratio Above polyol formulation/Voralast .TM. GE 143
ISO 100/54
[0106] In the following Inventive and Comparative Examples,
synthetic leather articles comprising a skin film derived from the
waterborne polyurethane dispersion and a 2k PU foam base layer were
prepared by the following Steps 1) to 4). [0107] 1) Preparation of
Two Prepolymers for the Waterborne Polyurethane Dispersion
[0108] A. The Prepolymer H1
[0109] Voranol 222-056 (317.5 g), castor oil (27.5 g) and MPEG1000
(10 g) were charged into a 1000 ml three neck flask and dehydrated
at 115.degree. C. under 76 mmHg pressure for one hour, then
naturally cooled down to a temperature of about 72.degree. C. IPDI
(145 g) was poured into the dehydrated polyol mixture at about
72.degree. C. under the protection of nitrogen (N.sub.2) flow and
mechanical stirring, then the catalyst T12 (0.03 g) was added into
the flask. The reaction lasted for one hour at about 72.degree. C.,
and then was heated to a temperature of about 82.degree. C. and
continued for additional 2.5 hours. The product (prepolymer H1) was
packaged in a plastic bottle and stored hermetically under nitrogen
protection. It was measured that the prepolymer H1 had a NCO % of
7.3%.
[0110] B. The Prepolymer H2
[0111] Voranol 4000LM polyol (130 g), Voranol 4240 polyol (207.5
g), castor oil (27.5 g) and MPEG1000 (10 g) were charged into a
1000 ml three neck flask and dehydrated at 115.degree. C. under 76
mmHg pressure for one hour, then naturally cooled down to a
temperature of about 72.degree. C. IPDI (125 g) was poured into the
dehydrated polyol mixture at about 72.degree. C. under the
protection of nitrogen (N.sub.2) flow and mechanical stirring, then
the catalyst T12 (0.03 g) was added into the flask. The reaction
lasted for one hour at about 72.degree. C., and then was heated to
a temperature of about 82.degree. C. and continued for additional
2.5 hours. The product (prepolymer H2) was packaged in a plastic
bottle and stored hermetically under nitrogen protection. It was
measured that the prepolymer H2 had a NCO % of 7.1%.
[0112] 2) Preparation of the Waterborne Polyurethane Dispersion
[0113] 100 gram of the prepolymer H1 or H2 was poured into a 500 ml
plastic cup and stirred with a cowles mixer. 13 g of a 23 wt % SDBS
aqueous solution was gradually added into the prepolymer under a
mixing speed of 4000 rpm. After stirring for additional several
minutes, ice water was dropwisely added into the prepolymer under a
mixing speed of 4000 rpm.
[0114] Phase reversion happened upon the addition of ice water and
an oil-in-water emulsion was formed. The mixing speed was then
lowered down to .about.1500 rpm. Aqueous solutions of the amino
siloxane compound (the hydrophilic OFX-7700 or the hydrophobic
OFX-8209) and the piperazine was dropwisely added into the
emulsion. Once all the solution was added, mechanical stirring was
continued for additional 12 minutes. Finally, a polyurethane
dispersion with .about.40% solid content was obtained and stored in
a plastic container with cover.
[0115] 3) Preparation of the PUD Skin Film
[0116] 22.5 gram of the polyurethane dispersion prepared in 2) was
weighed and diluted with equal amount of deionized water. The
diluted PUD was transferred into a vacuum oven and degassed for
.about.10 minutes. Then the degassed PUD was poured into a plastic
surface petri dish. The dish filled with PUD was transferred into
an oven and heated at 48.degree. C. for 24 hours, after which the
film was peeled from the dish, reversed and continuously dried for
another 24 hours. The film was cooled down to room temperature for
tensile and tear testing.
[0117] 4) Fabrication of the Synthetic Leather Article
[0118] The waterborne polyurethane dispersion prepared in 2) was
mixed with color masterbatch, thickener, slipping agent and
fast-drying agent as shown in table 3 at high speed
(1000.about.3000 rpm) for several minutes. The formulated PUD was
coated on a release paper to a wet film thickness of 150 .mu.m. The
coated release paper was dried in oven at 100.degree. C. for 3 min
and then at 130.degree. C. for 2 min. The release paper with dried
PU skin layer was taken out of the oven and cooled down to ambient
temperature. The formulated 2k PU composite was coated on the dried
PU skin film on the release paper to a wet film thickness of 300
.mu.m. The release paper with the PU skin film and the coated 2k PU
composite was transferred into a 100.degree. C. oven and precured
for 75 seconds. A backing substrate (textile fabric cloth) was then
carefully applied onto the 2k PU foam layer and pressed with a 3.5
kg roller for 2 times. The specimen was put into a 140.degree. C.
oven and post-cured for 5 minutes, and then taken out and cooled
down.
TABLE-US-00003 TABLE 3 The raw materials used in Step 4) Material
Dosage (phr) PUD 93 Euderm Black B-N 5 PG (1,2-Propanediol) 5
Acrysol RM 825 2 A2 additive 0.5
[0119] Technologies for Characterizing the Products
[0120] (a) Mechanical Properties of the PUD Skin Film Formed in
Step 3)
[0121] The tensile strength, elongation at break, modulus at 100%
elongation and tear strength of the PUD skin films obtained in Step
3) were characterized according to the standard ASTM D412-15a.
[0122] (b) Anti-Stickiness Performance Property of Synthetic
Leather Article Prepared in Step 4)
[0123] The anti-stickiness of the synthetic leather articles
prepared in above Step 4) were characterized according to the
standard GB/T 8948-2008. In particular, two 90 mm.times.60 mm
samples of the synthetic leather article were pasted together face
to face under a pressure of 1 kg and heated in an oven at
85.degree. C. for 3 h. The anti-stickiness was ranked from 1 to 5
according to the degree of stickiness between the two samples
during detaching of the two samples at room temperature:
[0124] Rank 1: not sticky completely;
[0125] Rank 2: can be detached with a little force;
[0126] Rank 3: can be detached with a certain force, and the
surface is not destroyed;
[0127] Rank 4: can be detached with a large force and incomplete
damage occurs on the surface; and
[0128] Rank 5: cannot be detached.
[0129] The formulations and characterization results of the
Comparative Examples 1-2 and the Inventive Examples 1-2 were
summarized in Table 4. The prepolymer H1 was prepared with a
polyether polyol having a Mw of 2,000 and was used in the Inventive
Example 1 and Comparative Example 1. The prepolymer H2 was prepared
with a polyether polyol having a Mw of 4,000 and was used in the
Inventive Example 2 and Comparative Example 2. The difference
between the inventive examples and the comparative examples is that
a hydrophilic amino siloxane compound (OFX-7700) was used in the
inventive examples. Particularly speaking, in the inventive
examples, a small amount of the OFX-7700, 2.5 wt % of the
prepolymer weight, was added during the PUD preparation, while the
comparative examples do not comprise said hydrophilic amino
siloxane compound. Since the equivalent molecule weight of the
hydrophilic amino siloxane (3700 g/mol) is significantly higher
than that of piperazine (43 g/mol), the influence of the
hydrophilic amino siloxane on chain extension coefficient can be
ignored, thus the inventive example and comparative example had
almost same chain extension coefficient (.about.88%).
[0130] The formulations and characterization results of the
Comparative Examples 1-2 and the Inventive Examples 1-2
TABLE-US-00004 Comparative Comparative Inventive Inventive Example
1 Example 2 Example 1 Example 2 PUD formulation Prepolymer-1 80 80
Prepolymer-2 80 80 SDBS 10.4 10.4 10.4 10.4 (23% aqueous) Ice/water
(50/50) 76 77.5 61 62.5 OFX-7700 0 0 20 20 (10% aqueous) Piperazine
52.6 50.8 52.6 50.8 (10% aqueous) Solid content 40% 40% 40% 40% PUD
film mechanical properties Tensile strength 29.9 17.7 27.6 17.8
(MPa) Elongation (%) 749 757 807 719 Modulus at 100% 4.3 3.8 4.1
4.0 Elongation (MPa) Synthetic leather see Table 3 skin layer
formulation Anti-stickiness rank 3 3 1 1 Tactility Moderate
Moderate Good Good
[0131] The comparison between the Inventive Example 1 and
Comparative Example 1 clearly shows that the incorporation of 2.5
wt % of hydrophilic amino siloxane compound can significantly
improve the anti-stickiness performance of the PUD synthetic
leather derived from a polyether polyol having a Mw of 2,000 from
rank 3 to rank 1. Only anti-stickiness performance with rank 1 can
be qualified for different applications by the synthetic leather
manufacturer. The greatly improved anti-stickiness performance
leads to much better tactility of the synthetic leather. Besides,
it can be found that the good mechanical properties of PUD film
such as tensile strength, elongation (>500% is required for
synthetic leather application) and modulus at 100% elongation
(>2.5 MPa is required for synthetic leather application) can be
maintained.
[0132] The same conclusion can be drawn based on the comparison
between the Inventive Example 2 and the Comparative Example 2 which
were conducted by using a polyether polyol having a Mw of
4,000.
Comparative Example 3 and Inventive Examples 3 to 4
[0133] Comparative Example 3, Inventive Example 3 and Inventive
Example 4 were performed by repeating the procedures of the
Inventive Example 1, except that the content of the hydrophilic
amino siloxane compound (OFX-7700) was adjusted to 1.25 wt %, 3.75
wt % and 5.0 wt %, respectively, and the anti-stickiness rank were
as follows:
TABLE-US-00005 TABLE 5 The formulations and anti-stickiness ranks
of the Comparative Example 3 and Inventive Examples 3 to 4
Comparative Inventive Inventive Example 3 Example 3 Example 4
OFX-7700 1.25 wt % 3.75 wt % 5.0 wt % Anti-stickiness rank 2 1
1
Comparative Example 4
[0134] The Comparative Example 4 was performed by following the
procedures of the Inventive Example 1, except that the OFX-7700 was
replaced with a hydrophobic amino siloxane compound (OFX-8209). It
was found that there were many bulges on the PUD film, implying
that some gels were formed during the forming of the PUD. Since we
cannot get a homogeneous and transparent PUD film via this
hydrophobic amino siloxane, we did not prepare a synthetic leather
with this PUD for further evaluation.
* * * * *