U.S. patent application number 09/784060 was filed with the patent office on 2001-10-18 for microcellular polyurethane elastomer, and method of producing the same.
Invention is credited to Chikamoto, Takuya, Kuwamura, Goro, Nishiguchi, Daisuke, Ueno, Kaoru, Usaka, Kazuto, Yamasaki, Satoshi.
Application Number | 20010031797 09/784060 |
Document ID | / |
Family ID | 26585534 |
Filed Date | 2001-10-18 |
United States Patent
Application |
20010031797 |
Kind Code |
A1 |
Kuwamura, Goro ; et
al. |
October 18, 2001 |
Microcellular polyurethane elastomer, and method of producing the
same
Abstract
The microcellular polyurethane elastomer of the present
invention has (1) an overall density (D) of 100 kg/m.sup.3 or more
but 900 kg/m.sup.3 or less, and (2) overall density (D) and
compression set (CS2, unit: %) satisfying the relationship shown by
the following equation (1): and
CS2.ltoreq.0.00008*D.sup.2-0.091*D+42 (1) overall density (D) and
cell diameter (X, unit: .mu.m) on the skin surface satisfying the
relationship shown by the following equation (2):
X.ltoreq.120e.sup.-0.0015.sup..sup.D (2)
Inventors: |
Kuwamura, Goro;
(Sodegaura-shi, JP) ; Nishiguchi, Daisuke;
(Sodegaura-shi, JP) ; Yamasaki, Satoshi;
(Sodegaura-shi, JP) ; Chikamoto, Takuya;
(Sodegaura-shi, JP) ; Usaka, Kazuto;
(Sodegaura-shi, JP) ; Ueno, Kaoru; (Sodegaura-shi,
JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Family ID: |
26585534 |
Appl. No.: |
09/784060 |
Filed: |
February 16, 2001 |
Current U.S.
Class: |
521/155 |
Current CPC
Class: |
C08G 2110/0008 20210101;
C08G 2110/0066 20210101; C08G 18/10 20130101; C08G 18/4866
20130101; C08G 18/632 20130101; C08G 2110/0083 20210101; C08G
65/2675 20130101; C08G 18/10 20130101; C08G 18/6564 20130101 |
Class at
Publication: |
521/155 |
International
Class: |
C08J 009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 17, 2000 |
JP |
2000-39213 |
May 9, 2000 |
JP |
2000-135632 |
Claims
What is claimed is:
1. A microcellular polyurethane elastomer, having (1) an overall
density (D) of 100 kg/m .sup.3 or more but 900 kg/m.sup.3 or less,
and (2) overall density (D) and compression set (CS2, unit: %)
satisfying a relationship shown by the following equation (1):
CS2.ltoreq.0.00008*D.su- p.2-0.091*D+42 (1) and having overall
density (D) and average cell diameter (X, unit: .mu.m) observed on
a skin surface satisfying a relationship shown by the following
equation (2): X.ltoreq.120e.sup.-0.00- 15.sup..sup.D (2).
2. The microcellular polyurethane elastomer as claimed in claim 1,
wherein its overall density is 200 kg/m.sup.3 or more but 700
kg/m.sup.3 or less.
3. The microcellular polyurethane elastomer as claimed in claim 1,
containing the cells having an average diameter of 1 .mu.m or more
but 200 .mu.m or less.
4. The microcellular polyurethane elastomer as claimed in claim 1
or 2, wherein its overall density and compression set satisfy a
relationship shown by the following equation (3):
CS2.ltoreq.0.00008*D.sup.2-0.091*D+4- 0 (3)
5. The microcellular polyurethane elastomer as claimed in any one
of claims 1 to 3, wherein its average cell diameter (X, unit:
.mu.m) observed on the skin surface satisfies a relationship shown
by the following equation (4): X.ltoreq.110e.sup.-0.0015.sup..sup.D
(4)
6. A microcellular polyurethane elastomer having an overall density
(D) of 100 kg/.sup.3 or more but 900 kg/m.sup.3 or less obtained by
reacting a polyol with a polyisocyanate compound, wherein said
polyol contains 50 wt. % or more of at least one polyoxyalkylene
polyol having a hydroxyl value of 2 to 200 mg-KOH/g, an overall
degree of unsaturation of 0.001 to 0.07 meq./g and a head-to-tail
linkage selectivity of 95 mol % or more for that of the
polyoxyalkylene polyol produced by addition polymerization of
propylene oxide.
7. The microcellular polyurethane elastomer as claimed in claim 6,
wherein said polyoxyalkylene polyol is produced in the presence of
a compound having a P.dbd.N bond as a catalyst.
8. The microcellular polyurethane elastomer as claimed in claim 1,
obtained by reacting a polyol with a polyisocyanate compound,
wherein said polyol contains 50 wt. % or more of at least one
polyoxyalkylene polyol having a hydroxyl value of 2 to 200
mg-KOH/g, an overall degree of unsaturation of 0.001 to 0.07 meq./g
and a head-to-tail linkage selectivity of 95 mol % or more for that
of the polyoxyalkylene polyol produced by addition polymerization
of propylene oxide.
9. The microcellular polyurethane elastomer as claimed in claim 8,
wherein said polyoxyalkylene polyol is produced in the presence of
a compound having a P.dbd.N bond as a catalyst.
10. The microcellular polyurethane elastomer as claimed in claim 8,
wherein said polyol contains 0.5 to 50 wt. % of polymer-dispersed
polyol containing 1 to 50 wt. % of polymer micro particles produced
by polymerization of at least one monomer containing an
ethylenically unsaturated group.
11. The microcellular polyurethane elastomer as claimed in claim
10, wherein said polymer-dispersed polyol is produced by
polymerization of at least one monomer containing an ethylenically
unsaturated group in at least one polyoxyalkylene polyol having a
hydroxyl value of 2 to 200 mg-KOH/g, an overall degree of
unsaturation of 0.001 to 0.07 meq./g and a head-to-tail linkage
selectivity of 95 mol % or more for that of the polyoxyalkylene
polyol produced by addition polymerization of propylene oxide.
12. The microcellular polyurethane elastomer as claimed in claim 10
or 11, wherein said polymer-dispersed polyol contains 10 to 45 wt.
% of said polymer micro particles.
13. The microcellular polyurethane elastomer as claimed in any one
of claims 10 to 12, wherein said monomer containing an
ethylenically unsaturated group is one or more types of monomers
selected from the group consisting of acrylonitrile, styrene,
acrylamide and methyl methacrylate.
14. The microcellular polyurethane elastomer as claimed in any one
of claims 10 to 13, wherein said monomer containing an
ethylenically unsaturated group contains 30 wt. % or more of
styrene.
15. The microcellular polyurethane elastomer as claimed in any one
of claims 1 to 14, which is obtained by reacting an
isocyanate-terminated prepolymer with a polyol, said prepolymer
being obtained by reacting an aromatic polyester polyol with a
polyisocyanate.
16. A shoe sole which is made of the microcellular polyurethane
elastomer as claimed in any one of claims 1 to 15.
17. A method of producing a microcellular polyurethane elastomer,
obtained by reacting a polyol with a polyisocyanate compound to
have (1) an overall density (D) of 100 kg/m.sup.3 or more but 900
kg/m.sup.3 or less, and (2) overall density (D) and compression set
(CS2, unit: %) satisfying a relationship shown by the following
equation (1) CS2.ltoreq.0.00008*D.sup.2-0.091*D+42 (1) and to have
overall density (D) and average cell diameter (X, unit: .mu.m)
observed on the skin surface satisfying a relationship shown by the
following equation (2): X.ltoreq.120e.sup.-0.0015.sup..sup.D (2)
wherein, said polyol contains 50 wt. % or more of at least one
polyoxyalkylene polyol having a hydroxyl value of 2 to 200
mg-KOH/g, an overall degree of unsaturation of 0.001 to 0.07 meq./g
and a head-to-tail linkage selectivity of 95 mol % or more for that
of the polyoxyalkylene polyol produced by addition polymerization
of propylene oxide.
18. The method of producing a finely foamed polyurethane elastmer
as claimed in claim 17, wherein said polyoxyalkylene polyol is
produced in the presence of a compound having a P.dbd.N bond as a
catalyst.
19. The method of producing a finely foamed polyurethane elastmer
as claimed in claim 17, which is obtained by reacting a polyol with
a polyisocyanate compound, wherein said polyol contains 0.5 to 50
wt. % of polymer-dispersed polyol containing 1 to 50 wt. % of the
polymer micro particles produced by polymerization of at least one
monomer containing an ethylenically unsaturated group.
20. The method of producing a finely foamed polyurethane elastmer
as claimed in any one of claims 17 to 19, which is obtained by
reacting a polyol with a polyisocyanate compound, wherein said
polyisocyanate compound is an isocyanate-terminated prepolymer
obtained by reacting an aromatic polyester polyol with a
polyisocyanate.
21. The method of producing a finely foamed polyurethane elastmer
as claimed in claim 20, wherein said polyisocyanate compound
contains 20 wt. % or more of the isocyanate-terminated prepolymer
obtained by reacting an aromatic polyester polyol with a
polyisocyanate.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a microcellular
polyurethane elastomer and a method of producing the same, more
particularly to a microcellular polyurethane elastomer for a shoe
sole and a method of producing the same.
[0003] 2. Description of the Prior Art
[0004] A microcellular polyurethane elastomer has fine cells
uniformly dispersed in a formed body, and is characterized by its
forming density lower than that of a solid type polyurethane
elastomer but higher than that of a flexible polyurethane foam. The
microcellular polyurethane elastomer has been used for, e.g., shoe
soles, gaskets, sealants and vibration insulators, and is still a
very important material.
[0005] The representative microcellular polyurethane elastomer is
produced by reacting a resin premix with an isocyanate component,
wherein the resin premix is a mixture of a polyol component and one
or more aids/additives, e.g., chain extender, catalyst, foam
stabilizer and foaming agent.
[0006] It is known that polyester polyol and polyoxyalkylene polyol
are used as the polyol component.
[0007] However, the microcellular polyurethane elastomer using a
polyester polyol is insufficient in resistance to hydrolysis,
although excellent in various physical properties, e.g., tensile
strength, elongation and tear strength. Therefore, various attempts
have been done to retard the hydrolysis, e.g., use of various types
of additives and modification of chemical structures of polyester
polyol. One of the methods proposed so far for improving resistance
to the hydrolysis is to contain 0.001 to 0.007 mol of a compound
having 3 active hydrogen atoms per 1000 g of the polyurethane resin
produced, to cause a small quantity of branched structure. Such a
compound, however, is still required to be further improved in
resistance to hydrolysis.
[0008] On the other hand, use of polyoxypropylene polyol as the
polyoxyalkylene polyol is known to improve resistance of the
polyurethane to hydrolysis. However, a polyoxypropylene polyol has
generally insufficient reactivity, and causes problems, e.g.,
extended demolding time and deterioration of green and final
strength. These problems may be solved by increasing quantity of
the catalyst, which, however, is accompanied by other problems,
e.g., deterioration of processability and moldability resulting
from shortened cream time or gel time.
[0009] Development of a polyoxyalkylene polyol exhibiting higher
physical characteristics has been demanded even for the areas to
which the conventional polyoxyalkylene polyol is sufficiently
applicable with its resistance to hydrolysis, because of the
problems associated with production of the polyol. One of the
methods generally used for producing a polyoxyalkylene polyol is
addition polymerization in which an active hydrogen compound is
reacted with an alkylene oxide in the presence of potassium
hydroxide (KOH) as the catalyst. However, it is known that, when
propylene oxide as the common alkylene oxide is used for addition
polymerization in the presence of a KOH catalyst, a mono-ol having
an unsaturated group at the molecular chain piece terminal is
produced increasingly as the by-product, as the polyoxypropylene
polyol increases in molecular weight.
[0010] In general, mono-ol content corresponds to overall degree of
unsaturation of polyoxypropylene polyol. The mono-ol has a lower
molecular weight than the polyoxypropylene polyol produced by the
main reaction, and greatly widens molecular weight distribution of
the polyoxypropylene polyol and hence decreases average number of
functional groups. It is also known that the mono-ol retards
formation of the polymer networks for the urethane-forming reaction
with polyisocyanate compound, resulting in deterioration of
mechanical strength of polyurethane as the reaction product.
[0011] Attempts have been made to improve productivity of the
polyoxyalkylene polyol synthesis, while inhibiting formation of
mono-ol as the by-product. For example, a double metal cyanide
complex (DMC) is proposed as the catalyst for addition
polymerization of propylene oxide, as disclosed by publications of
U.S. Pat. No. 3,829,505 and U.S. Pat. No. 4,472,560, which describe
that DMC is an excellent catalyst for polymerization of propylene
oxide.
[0012] A publication of U.S. Pat. No. 5,728,745 discloses a
polyoxyalkylene polyol synthesized in the presence of an improved
DMC as the catalyst, which gives a microporous elastomer showing a
very high green strength and demolded in a short time, without
causing deterioration of the final elastomer properties. Japanese
Patent Publication No. 3-47202 describes, in its exmaples, that the
polyoxyalkylene polyol synthesized in the presence of a DMC
catalyst gives a polyurethane-based resin for shoe soles highly
resistant to moist heat.
[0013] However, addition polymerization of ethylene oxide as the
alkylene oxide in the presence of a DMC catalyst needs several
steps, e.g., deactivation of the DMC catalyst by the reaction with
an oxidant (e.g., an oxygen-containing gas, peroxide or sulfate),
separation of the residual catalyst from the polyoxyalkylene
polyol, and addition polymerization in the presence of a hydroxide
of alkali metal (e.g., KOH), alkoxide of alkali metal or the like
as the catalyst, as disclosed by U.S. Pat. No. 5,235,114. The
inventors of the present invention have synthesized a
polyoxyalkylene polyol in the presence of a DMC catalyst, and
produced the microcellular polyurethane elastomer from the polyol,
to find that the microcellular polyurethane elastomer fails to
satisfy the desired characteristics they have pursued with respect
to demolding time, durability-related characteristics (e.g.,
compression set), and cell shape in a specific range.
[0014] One of the catalysts other than the above-described ones for
synthesizing polyoxyalkylene polyol is a phosphazene compound,
disclosed by a publication of EPO 763,555, Macromol. Rapid Commun.
Vol. 17, pp. 143 to 148, 1996, and Macromol. Symp. Vol. 107, pp.
331 to 340, 1996). When used as the catalyst for synthesizing
polyoxyalkylene polyol, the phosphazene compound brings about
advantages of controlled production of the mono-ol as the
by-product and greatly improved productivity.
BRIEF SUMMARY OF THE INVENTION
Object of the Invention
[0015] It is an object of the present invention to provide a
microcellular polyurethane elastomer which can solve the problems
involved in the conventional techniques. It is another object of
the present invention to provide a method of producing the same.
More concretely, the present invention provides a microcellular
polyurethane elastomer showing reduced demolding time, greatly
reduced compression set and excellent mechanical properties, and,
at the same time, excellent in appearances and coating
characteristics, and also provides a method of producing the
same.
SUMMARY OF THE INVENTION
[0016] The inventors of the present invention have found, after
having extensively studied to develop a microcellular polyurethane
elastomer of excellent characteristics and a method of efficiently
producing the same, that the microcellular polyurethane elastomer
can have excellent mechanical strength when it has an overall
density (D) in a specific range and its compression set (CS2) and
cell diameter on the skin surface satisfy specific correlations
with its overall density (D), that the microcellular polyurethane
elastomer can have excellent characteristics and its demolding time
can be reduced to improve production efficiency by use of
polyoxyalkylene polyol having a specific hydroxyl value (OHV), an
overall degree of unsaturation and head-to-tail (H-T) linkage
selectivity, and that the microcellular polyurethane elastomer can
have reduced demolding time and excellent mechanical properties by
use of a specific quantity of polyoxyalkylene polyol having a
W.sub.20/W.sub.80 ratio as an index representing molecular weight
distribution in a specific range, reaching the present
invention.
[0017] The present invention, which solves the above problems,
provides the following items (1) to (21).
[0018] (1) A microcellular polyurethane elastomer, having
[0019] (a) an overall density (D) of 100 kg/m.sup.3 or more but 900
kg/m.sup.3 or less,
[0020] (b) overall density (D) and compression set (CS2, unit: %)
satisfying a relationship shown by the following equation (1)
CS2.ltoreq.0.00008*D.sup.2-0.091*D+42 (1)
[0021] and having
[0022] overall density (D) and average cell diameter (X, unit:
.mu.m) observed on the skin surface satisfying a relationship shown
by the following equation (2):
X.ltoreq.120e.sup.-0.0015.sup..sup.D (2).
[0023] (2) The microcellular polyurethane elastomer of (1), wherein
its overall density is 200 kg/m.sup.3 or more but 700 kg/m.sup.3or
less.
[0024] (3) The microcellular polyurethane elastomer of (1),
containing the cells having an average diameter of 1 .mu.m or more
but 200 .mu.m or less.
[0025] (4) The microcellular polyurethane elastomer of one of (1)
to (3), wherein its overall density and compression set satisfy a
relationship shown by the following equation (3):
CS2.ltoreq.0.00008*D.sup.2-0.091*D+40 (3)
[0026] (5) The microcellular polyurethane elastomer of one of (1)
to (3), wherein its average cell diameter (X, unit: .mu.m) observed
on a skin surface satisfies the relationship shown by a following
equation (4):
X.ltoreq.110e.sup.0.0015.sup..sup.D (4)
[0027] (6) A microcellular polyurethane elastomer a polyol with a
polyisocyanate compound to having an overall density (D) of 100
kg/m.sup.3 or more but 900 kg/m.sup.3 or less obtained by reacting,
wherein above described polyol contains 50 wt. % or more of at
least one polyoxyalkylene polyol having a hydroxyl value of 2 to
200 mg-KOH/g, an overall degree of unsaturation of 0.001 to 0.07
meq./g and a head-to-tail linkage selectivity of 95 mol % or more
for that of the polyoxyalkylene polyol produced by addition
polymerization of propylene oxide.
[0028] (7) The microcellular polyurethane elastomer of (6), wherein
above described polyoxyalkylene polyol is produced in the presence
of a compound having a P.dbd.N bond as a catalyst.
[0029] (8) The microcellular polyurethane elastomer of (1),
obtained by reacting a polyol with a polyisocyanate compound,
wherein above described polyol contains 50 wt. % or more of at
least one polyoxyalkylene polyol having a hydroxyl value of 2 to
200 mg-KOH/g, an overall degree of unsaturation of 0.001 to 0.07
meq./g and a head-to-tail linkage selectivity of 95 mol % or more
for that of the polyoxyalkylene polyol produced by addition
polymerization of propylene oxide.
[0030] (9) The microcellular polyurethane elastomer of (8), wherein
above described polyoxyalkylene polyol is produced in the presence
of a compound having a P.dbd.N bond as a catalyst.
[0031] (10) The microcellular polyurethane elastomer of (8),
wherein above described polyol contains 0.5 to 50 wt. % of
polymer-dispersed polyol containing 1 to 50 wt. % of the polymer
micro particles produced by polymerization of at least one monomer
containing an ethylenically unsaturated group.
[0032] (11) The microcellular polyurethane elastomer of (10),
wherein above described polymer-dispersed polyol is produced by
polymerization of at least one monomer containing an ethylenically
unsaturated group in at least one polyoxyalkylene polyol having a
hydroxyl value of 2 to 200 mg-KOH/g, an overall degree of
unsaturation of 0.001 to 0.07 meq./g and a head-to-tail linkage
selectivity of 95 mol % or more for that of the polyoxyalkylene
polyol produced by addition polymerization of propylene oxide.
[0033] (12) The microcellular polyurethane elastomer of (10),
wherein above described polymer-dispersed polyol contains 10 to 45
wt. % of above described polymer micro particles.
[0034] (13) The microcellular polyurethane elastomer of one of (10)
to (12), wherein above described monomer containing an
ethylenically unsaturated group is one or more types of monomers
selected from the group consisting of acrylonitrile, styrene,
acrylamide and methyl methacrylate.
[0035] (14) The microcellular polyurethane elastomer of one of (10)
to (13), wherein above described monomer containing an
ethylenically unsaturated group contains 30 wt. % or more of
styrene.
[0036] (15) The microcellular polyurethane elastomer of one of (1)
to (14), which is obtained by reacting an isocyanate-terminated
prepolymer with a polyol, above described prepolymer being obtained
by reacting an aromatic polyester polyol with a polyisocyanate.
[0037] (16) A shoe sole which is made of the microcellular
polyurethane elastomer of one of (1) to (15).
[0038] (17) A method of producing a microcellular polyurethane
elastomer, obtained by reacting a polyol with a polyisocyanate
compound to have
[0039] (a) an overall density (D) of 100 kg/m.sup.3 or more but 900
kg/m.sup.3 or less, and
[0040] (b) overall density (D) and compression set (CS2, unit: %)
satisfying the relationship shown by the following equation (1):
and
CS2.ltoreq.0.00008*D.sup.2-0.091*D+42 (1)
[0041] and to have overall density (D) and average cell diameter
(X, unit: .mu.m) observed on the skin surface satisfying the
relationship shown by the following equation (2):
X.ltoreq.120e.sup.-0.0015.sup..sup.D (2)
[0042] wherein, above described polyol contains 50 wt. % or more of
at least one polyoxyalkylene polyol having a hydroxyl value of 2 to
200 mg-KOH/g, an overall degree of unsaturation of 0.001 to 0.07
meq./g and a head-to-tail linkage selectivity of 95 mol % or more
for that of the polyoxyalkylene polyol produced by addition
polymerization of propylene oxide.
[0043] (18) The method of producing a finely foamed polyurethane
elastmer of (17), wherein above described polyoxyalkylene polyol is
produced in the presence of a compound having a P.dbd.N bond as a
catalyst.
[0044] (19) The method of producing a finely foamed polyurethane
elastmer of (17), which is obtained by reacting a polyol with a
polyisocyanate compound, wherein above described polyol contains
0.5 to 50 wt. % of polymer-dispersed polyol containing 1 to 50 wt.
% of the polymer micro particles produced by polymerization of at
least one monomer containing an ethylenically unsaturated
group.
[0045] (20) The method of producing a finely foamed polyurethane
elastmer of one of (17) to (19), which is obtained by reacting a
polyol with a polyisocyanate compound, wherein above described
polyisocyanate compound is an isocyanate-terminated prepolymer
obtained by reacting an aromatic polyester polyol with a
polyisocyanate.
[0046] (21) The method of producing a finely foamed polyurethane
elastmer of (20), wherein above described polyisocyanate compound
contains 20 wt. % or more of the isocyanate-terminated prepolymer
obtained by reacting an aromatic polyester polyol with a
polyisocyanate.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0047] The present invention will be described in detail below by
the preferred embodiments.
[0048] <<Microcellular polyurethane elastomer>>
[0049] The microcellular polyurethane elastomer has an overall
density of 100 to 900 kg/m.sup.3, preferably 200 to 800 kg/m.sup.3,
more preferably 200 to 700 kg/m.sup.3, wherein overall density
means density of the whole elastomer including its surface layer
section. Keeping overall density at 100 kg/m.sup.3 or more gives
the elastomer of improved mechanical strength and allows the formed
elastomer to exhibit excellent mechanical properties. The
microcellular polyurethane elastomer of the present invention has
following mechanical properties; hardness (Asker C): 5 to 95,
tensile strength (TB): 0.5 to 20 MPa, maximum elongation (EB): 100
to 700%, tear strength (TR): 0.5 to 50 kN/m, and compression set
(CS2): 3 to 35%, which vary depending on its overall density.
[0050] Compression set (CS2) is an important property for the
microcellular polyurethane elastomer, especially for shoe soles,
because it determines the product quality. The elastomer of lower
CS2 value suffers less dimensional changes when used repeatedly,
and enables to keep desired elastic feeling for extended periods.
It is determined in accordance with JIS K-6262, where the circular
specimen 29 mm in diameter, cut from a sheet, was tested under the
conditions of test temperature: 50.+-.1.degree. C., test time: 6
hours, and compression ratio: 50%. The compression set thus
determined is referred to as the "CS2" value in this
specification.
[0051] The CS2 value of the microcellular polyurethane elastomer of
the present invention satisfies the relationship shown by the
following equation (1):
CS2.ltoreq.0.00008*D.sup.2-0.091*D+42 (1)
[0052] preferably the following equation (3):
CS2.ltoreq.0.00008*D.sup.2-0.091*D+40 (3)
[0053] more preferably the following equation (5): and
CS2.ltoreq.0.00008*D.sup.2-0.091*D+38 (5)
[0054] especially preferably the following equation (6):
CS2.ltoreq.35*e.sup.-0.0025*D (6).
[0055] The microcellular polyurethane elastomer should have
sufficient mechanical strength, when it has a CS2 value in the
above range.
[0056] Surface characteristics are also important for the foamed
polyurethane elastomer for shoe soles. It is needless to say that
surface characteristics greatly affect quality of the uncoated
product, let alone coated surface of the product post-treated by
coating. It is preferable that the microcellular polyurethane
elastomer has a glossy surface without defects, e.g., flow marks
and pinholes, before being coated, and keeps the glossy surface
without defects, e.g., uneven coloration, after being coated.
[0057] The inventors of the present invention have found that the
surface characteristics are determined by size of the cells on the
skin surface, where the skin surface of the present invention means
the surface of the microcellular polyurethane elastomer sheet in
contact with the mold, e.g., of aluminum 12.5 by 150.0 by 250.0 mm
in inner dimensions, in which it is formed. The surface (150.0 by
250.0 mm) in contact with the mold bottom was observed for its cell
diameters by a microcamera at a total of five position, the four
corners and center, for the portion excluding the 20 mm wide
sections from the edges in the length and breadth directions. The
average diameter of these cells at each of the 5 points is
determined by image processor/analyzer, and the average cell
diameter X on the skin surface is determined by averaging the
average diameters at these points.
[0058] The cell diameter (X, unit: .mu.m) observed on the skin
surface of the microcellular polyurethane elastomer of the present
invention preferably satisfies the relationship shown by the
following equation (2):
X.ltoreq.120e.sup.0.0015.sup..sup.D (2)
[0059] more preferably the following equation (4): and
X.ltoreq.110e.sup.0.0015.sup..sup.D (4)
[0060] still more preferably the following equation (7):
X.ltoreq.100e.sup.0.0015.sup..sup.D (7)
[0061] Controlling the average cell diameter on the skin surface in
the above range substantially increases thickness of the skin
layer. The inventors of the present invention have also found that
increasing thickness of the skin layer improves mechanical
properties, e.g., tensile strength, of the elastomer.
[0062] The average cell diameter inside of the microcellular
polyurethane elastomer of (e.g. the average cell diameter as
measured without skin layer) the present invention is preferably 1
.mu.m or more but 200 .mu.m or less, more preferably 1 .mu.m or
more but 150 .mu.m or less, still more preferably 1 .mu.m or more
but 100 .mu.m or less, and most preferably 5 .mu.m or more but 100
.mu.m or less. The average cell diameter inside of the
microcellular polyurethane elastomer of the present invention is
determined by observing diameters of the cells at the four planes
of the specimen in the sectional direction (perpendicular to the
skin surface) by a microcamera, and finding the average cell
diameter by an image processor/analyzer, where the specimen is
prepared by, e.g., cutting the sheet of microcellular polyurethane
elastomer, formed in an aluminum mold of 12.5 by 150.0 by 250.0 mm
in inner dimensions, into a shape of 3 cm in the length direction
and 1 cm in the breadth direction from the central portion, and
removing the 4 mm thick upper and lower sections.
[0063] Keeping the average cell diameter at 200 .mu.m or less,
especially 100 .mu.m or less, can inhibit growth of the cell
diameter, and give the microcellular polyurethane elastomer of good
feeling of touch and improved mechanical properties.
[0064] <<Production of microcellular polyurethane
elastomer>>
[0065] The microcellular polyurethane elastomer of the present
invention, having the above-described characteristics, is produced
by reacting a polyol including a polyoxyalkylene polyol having a
specific structure as the main component, with a polyisocyanate
compound in the presence of a foaming agent, catalyst and foam
stabilizer. Each component is described first in detail.
[0066] <<Polyol>>
[0067] The polyol for the present invention contains 50 wt. % or
more of at least one polyoxyalkylene polyol having a hydroxyl value
(OHV) of 2 to 200 mg-KOH/g, an overall degree of unsaturation of
0.001 to 0.07 meq./g, and head-to-tail (H-T) linkage selectivity of
95 mol % or more for that of the polyoxyalkylene polyol produced by
addition polymerization of propylene oxide.
[0068] <Polyoxyalkylene polyol>
[0069] The polyoxyalkylene polyol for the present invention has an
OHV value of 2 to 200 mg-KOH/g, preferably 9 to 120 mg-KOH/g, more
preferably 10 to 100 mg-KOH/g, still more preferably 20 to 80
mg-KOH/g, and most preferably 20 to 60 mg-KOH/g, viewed from
mechanical properties and demolding characteristics of the
microcellular polyurethane elastomer.
[0070] The polyoxyalkylene polyol for the present invention also
has an overall degree of unsaturation of 0.07 meq./g or less,
preferably 0.05 meq./g or less, more preferably 0.04 meq./g or
less, and most preferably 0.03 meq./g or less, in order to improve
mechanical strength of the microcellular polyurethane elastomer and
allow it to exhibit its inherent properties in the early stage.
[0071] Keeping an overall degree of unsaturation at 0.07 meq./g or
less greatly improves mechanical strength of the microcellular
polyurethane elastomer. The lower limit of an overall degree of
unsaturation is not limited for the present invention, but around
0.001 meq./g.
[0072] The polyoxyalkylene polyol for the present invention also
has a head-to-tail (H-T) linkage selectivity of 95 mol % or more,
preferably 96 mol % or more, more preferably 97 mol % or more,
where the selectivity results from the cleavage mode of oxirane
ring in addition polymerization of propylene oxide. Keeping
head-to-tail (H-T) linkage selectivity at 95 mol % or more can keep
polyoxyalkylene polyol viscosity in an adequate range, develop the
compatibility with an aid/additive, e.g., foam stabilizer, and also
inhibit growth of the average cell diameter and deterioration of
processability of the microcellular polyurethane elastomer.
[0073] The polyoxyalkylene polyol for the present invention also
has a W.sub.20/W.sub.80 ratio of 1.5 or more but below 3.0, where
W.sub.20 and W.sub.80 are widths of the peaks at 20 and 80% of the
highest peak in the gel permeation chromatography (GPC) elution
curve.
[0074] The causes for broadening the molecular weight distribution
of polyoxyalkylene polyol include formation of mono-ol by the
side-reaction of propylene oxide, and formation of a
high-molecular-weight component as the by-product. The mono-ol
(corresponding to an overall degree of unsaturation, defined in
this specification) has a lower molecular weight than the
polyoxyalkylene polyol produced by the main reaction, and slower
than the component formed by the main reaction in peak holding time
in the GPC elution curve. Decreasing concentration of mono-ol makes
an overall degree of unsaturation of the polyol decrease, as a
result, mechanical strength of the microcellular polyurethane
elastomer is greatly improved.
[0075] Therefore, a polyoxyalkylene polyol containing a higher
proportion of the high-molecular-weight component has a higher
viscosity than the one containing a lower proportion of the
high-molecular-weight component, increasing viscosity of the resin
premix containing a catalyst, foam stabilizer, foaming agent or the
like and also viscosity of the isocyanate-terminated prepolymer
obtained by the reaction with a polyisocyanate, and hence causing
problems, e.g., deteriorated processability and flowability of the
microcellular polyurethane elastomer, to deteriorate its
formability and grow its cell diameter.
[0076] The polyoxyalkylene polyol for the present invention is
preferably produced from propylene oxide as the main monomer and
ethylene oxide. Introduction of ethylene oxide into the terminal of
the polyoxyalkylene polyol structure with the propylene oxide as
the main chain allows the polyol to exhibit a sufficient reaction
rate, and also can sufficiently increase molecular weight of the
microcellular polyurethane elastomer. Content of ethylene oxide in
the polyoxyalkylene polyol for the present invention is preferably
30 wt. % or less, more preferably 5 to 30 wt. %, and most
preferably 10 to 25 wt. %. Rate for producing a primary hydroxyl
group at the terminal of the polyoxyalkylene polyol is preferably
around 50 mol % or more, more preferably 70 mol % or more, still
more preferably 75 mol % or more, and most preferably 80 mol % or
more.
[0077] It is also preferable that the polyoxyalkylene polyol for
the present invention is produced in the presence of a compound
having the P.dbd.N bond as a catalyst. More preferably, the
compound is one or more types of compound selected from the group
consisting of phosphazenium compound, phosphazene compound and
phosphine oxide compound, of which a phosphazenium compound is most
preferable. The polyoxyalkylene polyol produced in the presence of
a phosphazenium compound preferably has a hydroxyl value of 2 to
200 mg-KOH/g, an overall degree of unsaturation of 0.001 to 0.07
meq./g and a head-to-tail linkage selectivity of 95 mol % or more
for that of the polyoxyalkylene polyol produced by addition
polymerization of propylene oxide. Although the polyoxyalkylene
polyol is preferably produced in the presence of a phosphazenium
compound, a hydroxide of alkali metal, e.g., cesium hydroxide
(CsOH), may be used in combination with the phosphazenium compound,
so long as the effects of the present invention are not damaged.
The catalyst for producing the polyoxyalkylene polyol will be
described in detail later.
[0078] A polyol having a structure other than the above
polyoxyalkylene polyol may be used for production of the
microcellular polyurethane elastomer of the present invention. The
polyoxyalkylene polyol for the present invention accounts for 50
wt. % or more of the polyols, preferably 70 wt. % or more and more
preferably 80 wt. % or more. The polyol, other than the
polyoxyalkylene polyol, which can be used for the present
invention, will be described in detail later.
[0079] The polyoxyalkylene polyol preferably has a number-average
molecular weight of 1,000 to 12,000 for the microcellular
polyurethane elastomer for shoe soles. More preferably, it has a
number-average molecular weight of 2,000 to 8,000, and ethylene
oxide added to its terminals.
[0080] <Production of polyoxyalkylene polyol>
[0081] The polyoxyalkylene polyol for the present invention is also
referred to as polyoxyalkylene polyether polyol, which is an
oligomer or polymer produced by ring opening polymerization of an
alkylene oxide in the presence of a catalyst and active hydrogen
compound as the initiator. One or more types of initiators and
alkylene oxides may be used for the present invention.
[0082] <Catalyst for producing polyoxyalkylene polyol>
[0083] The catalyst for producing polyoxyalkylene polyol for the
present invention is particularly preferably a compound having the
P.dbd.N bond in its molecular structure. The example of such a
compound is one or more types of compound selected from the group
consisting of phosphazenium compound, phosphazene compound and
phosphine oxide compound.
[0084] The preferable phosphazenium compounds are a salt of
hosphazenium cation and inorganic anion, represented by the
chemical formula (1), disclosed by Japanese Patent Application
Laid-Open No. 11-106500, 1
[0085] and phosphazenium compound, represented by the chemical
formula (2): 2
[0086] where, (a), (b), (c) and (d) in the chemical formulas (1)
and (2) are each an integer of 0 to 3, which are not simultaneously
zero; R in the chemical formulas (1) and (2) is a hydrocarbon group
of 1 to 10 carbon atoms, which may be the same or different,
wherein two Rs on the same nitrogen atom may form a ring structure;
(r) in the chemical formula (1) is an integer of 1 to 3, and
representing number of phosphazenium cation; T.sup.r in the
chemical formula (1) represents an inorganic anion having a valence
number of (r); and Q.sup.- in the Equation (2) represents hydroxy
anion, alkoxy anion, aryloxy anion or carboxy anion, more
concretely,
[0087] tetrakis[tris(dimethylamino)phosphoranilideneamino]
phosphonium hydroxide, tetrakis[tris(dimethylamino)
phosphoranilideneamino]phosphoniu- m methoxide, tetrakis
[tris(dimethylamino)phosphoranilideneamino]phosphoni- um ethoxide,
tetrakis[tri(pyrrolidin-1-yl) phosphoranilideneamino]phosphon- ium
tert-butoxide, or the like.
[0088] The phosphazene compounds useful for the present invention
are disclosed by EP-763555, e.g.,
[0089] 1-tert-butyl-2,2,2-tris(dimethylamino)phosphazene,
[0090] 1-(1,1,3,3-tetramethylbutyl)-2,2,2-tris(dimethylamino)pho
sphazene,
[0091]
1-ethyl-2,2,4,4,4-pentakis(dimethylamino)-2.lambda..sup.5,4.lambda.-
.sup.5-catenad i(phosphazene),
[0092] 1-tert-butyl-4,4,4-tris(dimethylamino)-2,2-bis[tris(dimet
hylamino)
[0093]
phosphoranilideneamino]-2.lambda..sup.5,4.lambda..sup.5-catenadi(ph-
osphazene),
[0094] 1-(1,1,3,3-tetramethylbutyl)-4,4,4-tris(dimethylamino)-2,
2-bis[tris(dimethylamino)phosphoranilideneamino]-2.lambda..sup.5,4.lambda-
..sup.5-catenadi(phosphazene),
[0095] 1-tert-butyl-2,2,2-tri(1-pyrrolidinyl) phosphazene, and
[0096]
7-ethyl-5,11-dimethyl-1,5,7,11-tetraaza-6.lambda..sup.5-phosphaspir-
o[5,5]undeca-1(6)-ene.
[0097] The phosphine oxide compounds useful for the present
invention are disclosed by Japanese Patent Application No.
11-296610, e.g.,
[0098] tris[tris(dimethylamino)phosphoranilideneamino]phosphine
oxide, and
[0099] tris[tris(dimethylamino)phosphoranilideneamino]phosphine
oxide.
[0100] Of the above compounds having the P.dbd.N bond, preferable
ones are phosphazenium compounds and phosfine compounds, and more
preferable ones are phosphazenium compounds.
[0101] <Initiator>
[0102] The active hydrogen compounds useful as the initiator for
producing polyoxyalkylene polyol include those having an activated
hydrogen atom on the oxygen or nitrogen atom.
[0103] Of the active hydrogen compounds described below, more
preferable ones include ethylene glycol, propylene glycol,
dipropylene glycol, glycerin, trimethylolpropane, pentaerythritol,
sorbitol, and sucrose.
[0104] (1) Active hydrogen compounds having an activated hydrogen
atom on oxygen atom
[0105] The active hydrogen compounds useful for the present
invention and having an activated hydrogen atom on the oxygen atom
include water, polyvalent carboxylic acids having a carboxyl group,
carbamic acid, polyhydric alcohols having a hydroxyl group, sucrose
and its derivatives, and aromatic compounds having a hydroxyl
group.
[0106] The polyvalent carboxylic acids having a carboxyl group
include malonic acid, succinic acid, maleic acid, fumaric acid,
adipic acid, itaconic acid, butanetetracarboxylic acid, phthalic
acid, isophthalic acid, terephthalic acid, trimellitic acid, and
pyromellitic acid.
[0107] The carbamic acids include N,N-diethyl carbamate,
N-carboxypyrrolidone, N-carboxyaniline and
N,N'-dicarboxy-2,4-toluenediam- ine.
[0108] The polyhydric alcohols having a hydroxyl group include
ethylene glycol, propylene glycol, diethylene glycol, dipropylene
glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol,
1,6-hexanediol, 1,4-cyclohexanediol, trimethylolpropane, glycerin,
diglycerin, pentaerythritol and dipentaerythritol.
[0109] The saccharides and their derivatives include glucose,
sorbitol, dextrose, fructose and sucrose.
[0110] The aromatic compounds having a hydroxyl group include
2-naphthol, 2, 6-dihydroxynaphthalene, bisphenol A, bisphenol F,
hydroquinone, resorcin, and bis(hydroxyethyl)terephthalate.
[0111] (2) Active hydrogen compounds having an activated hydrogen
atom on nitrogen atom
[0112] The active hydrogen compounds useful for the present
invention and having an activated hydrogen atom on the nitrogen
atom include aliphatic and aromatic amines.
[0113] The aliphatic and aromatic amines include n-propylamine,
isopropylamine, n-butylamine, isobutylamine, sec-butylamine,
tert-butylamine, cyclohexylamine, benzylamine,
.beta.-phenylethylamine, aniline, o-toluidine, m-toluidine, and
p-toluidine.
[0114] The polyvalent amines include ethylenediamine,
di(2-aminoethyl)amine, hexamethylenediamine,
4,4'-diaminodiphenylmethane, tri(2-aminoethyl)amine,
N,N'-dimethylethylenediamine, N,N'-diethylethylendiamine, and
di(2-methylaminoethyl)amine.
[0115] <Alkylene oxide>
[0116] The alkylene oxide useful for producing polyoxyalkylene
polyol for the present invention preferably has propylene oxide as
the main component, and is more preferably a mixture of 50 wt. % or
more of propylene oxide and one or more other alkylene oxide
compounds. Use of this quantity of propylene oxide allows to
control oxypropylene group content in the polyoxyalkylene polyol at
50 wt. % or more. The polyoxyalkylene polyol has a sufficiently low
viscosity, when its oxypropylene group content is controlled at 50
wt. % or more to give a resin premix of good flowability. The
alkylene oxide compounds which can be used in combination with
propylene oxide include epoxy compounds, e.g., ethylene oxide,
1,2-butylene oxide, 2,3-butylene oxide, styrene oxide, cyclohexene
oxide, epichlorohydrin, epibromohydrin, methyl glycidyl ether, aryl
glycidyl ether, and phenyl glycidyl ether.
[0117] Of these, ethylene oxide is more preferable to be used in
combination with propylene oxide.
[0118] <Other polyols>
[0119] A polyol having a structure other than the above
polyoxyalkylene polyol may be used for production of the
microcellular polyurethane elastomer of the present invention, so
long as it does not damage the effects of the present invention.
Such polyols useful for the present invention include di- to
hexa-valent polyhydric alcohols, polyester polyols (including
polyester polyols, aromatic polyester polyols and polycaprolactone
polyols for common purposes), polycarbonate polyols, and
polymer-dispersed polyols.
[0120] (Polyhydric alcohol)
[0121] The polyhydric alcohols include di-valent alcohol, e.g.,
1,3-propanediol, 1,4-butanediol, ethylene glycol, diethylene
glycol, triethylene glycol, propylene glycol, dipropylene glycol,
tripropylene glycol, butanediol, pentanediol, hexanediol,
cyclohexanediol and neopentyl glycol; tri-valent alcohols, e.g.,
glycerin, trimethylolethane and trimethylolpropane; tetra-valent
alcohols, e.g., pentaerythritol and diglycerin; and hexa-valent
alcohols, e.g., sorbitol.
[0122] (Polyester polyol for common purposes)
[0123] The polyester polyol for common purposes includes polyester
polyol produced by polycondensation of a dicarboxylic acid and
polyhydric alcohol. The dicarboxylic acids for producing the
polyester polyols include adipic acid, succinic acid, azelac acid,
suberic acid and ricinolic acid. The polyhydric alcohols include
ethylene glycol, propylene glycol, butanediol, hexanediol,
neopentylglycol, diethylene glycol, triethylene glycol,
pentanediol, cyclohexanediol, polyoxyalkylene polyol,
polytetramethylene ether glycol, glycerin, trimethylolpropane,
trimethylolethane and pentaerythritol.
[0124] (Polycaprolactone polyol)
[0125] The polycaprolactone polyol is a polyol from
.epsilon.-caprolactone and polyhydric alcohol. These polyols have,
in general, a number-average molecular weight of 500 to 4,000 and
hydroxyl value of around 30 to 240 mg-KOH/g. The polyhydric
alcohols for the above polyester polyols may be used for producing
the polycaprolactone polyols.
[0126] (Polycarbonate polyol)
[0127] The polycarbonate polyols are liner chain aliphatic or
alicyclic polyols produced by condensation of a polyhydric alcohol
(e.g., 1,4-butanediol and 1,6-hexanediol) and dimethyl or diethyl
carbonate, and shown by the following general formula (3): 3
[0128] where, R.sup.1 and R.sup.2 are each an aliphatic alkylene or
alicyclic alkylene group, and may be the same or different.
[0129] They have, in general, a hydroxyl value of around 60 to 200
mg-KOH/g.
[0130] (Aromatic polyester polyol)
[0131] The aromatic polyester polyols are produced by the
interesterification between synthetic resin, e.g., polyethylene
terephthalate, and polyhydric alcohol, or polycondensation of an
aromatic carboxylic acid (e.g., o-, m- or p-phthalic acid) and
polyhydric alcohol. The preferable polyhydric alcohols for the
above purpose include polyoxyalkylene polyols and
polytetramethylene ether glycols, in addition to the
above-described polyhydric alcohols. They may be used either alone
or in combination. The aromatic ester polyol preferably has a
hydroxyl value of 10 to 150 mg-KOH/g, more preferably 15 to 100
mg-KOH/g and acid value of 0.7 mg-KOH/g or less, more preferably
0.5 mg-KOH/g or less. Use of the aromatic polyester polyol as the
polyol of isocyanate-terminated prepolymer helps improve mechanical
properties of the microcellular polyurethane elastomer.
[0132] (Polymer-dispersed polyol)
[0133] The polymer-dispersed polyol means the one dispersed with
the vinyl polymer particles (hereinafter sometimes referred to as
simply the polymer micro particles) partly containing the graft
polymer, produced by dispersion polymerization of at least one
monomer containing ethylenically unsaturated group (e.g.,
acrilonitrile and styrene) in a polyol in the presence of a radical
initiator (e.g., azobisisobutylonitrile). Use of the
polymer-dispersed polyol brings about the effect of sufficiently
increasing hardness of the microcellular polyurethane
elastomer.
[0134] The polyols useful for the present invention include
polyester polyols and polyoxyalkylene polyols having 2 to 6
functional groups on the average, the above-described
polyoxyalkylene polyols having specific properties for the present
invention being more preferable. The polymer produced by the
dispersion polymerization preferably has an average particle size
of 0.1 to 10 .mu.m.
[0135] The polymer-dispersed polyol preferably has a hydroxyl value
of 5 to 99 mg-KOH/g, more preferably 10 to 59 mg-KOH/g, for the
microcellular polyurethane elastomer to exhibit sufficiently high
mechanical strength.
[0136] The polymer-dispersed polyol for the present invention
preferably contains the polymer micro particles at 1 to 50 wt. %,
based on the polyoxyalkylene polyol, more preferably 10 to 45 wt.
%. The monomer containing an ethylenically unsaturated group is
preferably one or more types selected from the group consisting of
acrylonitrile, styrene, acrylamide and methyl methacrylate. Use of
the monomer containing an ethylenically unsaturated group, selected
from the above group, for the polymer-dispersed polyol helps
improve mechanical properties of the microcellular polyurethane
elastomer. It is particularly preferable to use the
polymer-dispersed polyol containing styrene at 30 wt. % or more,
still more preferably 40 wt. % or more, and most preferably 50 wt.
% or more. When the polymer micro particles based on an
acrylonitrile/styrene copolymer are used for the polymer-dispersed
polyol, whiteness of the microcellular polyurethane elastomer is
affected by styrene content. Controlling styrene content helps
produce the microcellular polyurethane elastomer of white
appearances suitable for white-colored shoe soles.
[0137] <<Polyisocyanate compound>>
[0138] Any polyisocyanate compound which is used for production of
polyurethane may be used for production of the microcellular
polyurethane elastomer of the present invention.
[0139] The polyisocyanate compounds useful for the present
invention include diisocyanates, e.g., tolylene diisocyanate
(including various types of mixtures of the isomers),
diphenylmethane diisocyanate (including various types of mixtures
of the isomers), 3,3'-dimethyl-4,4'-biphenylene diisocyanate,
norbornane diisocyanate, 1,4-phenylene diisocyanate,
tetramethylxylylene diisocyanate, naphthalene diisocyanate,
dicyclohexylmethane-4,4'-diisocyanate, isophorone diisocyanate,
hexamethylene diisocyanate, hydrogenated xylene diisocyanate,
1,4-cyclohexyl diisocyanate, 1-methyl-2,4-diisocyanate cyclohexane
and 2,4,4-trimethyl-1,6-diisocyanate-hexane; and triisocyanates,
e.g., 4,4',4"-triphenylmethane triisocyanate and
tris(4-phenylisocyanate)thiophosphate.
[0140] The other isocyanates useful for the present invention
include the above-described polyisocyanates modified with urethane,
isocyanurate, carbodiimide or burette; and multifunctional
isocyanates, e.g., crude tolylene diisocyanate, polymethylene
isocyanate and polyphenyl isocyanate.
[0141] Of these, the polyisocyanate or carbodiimide-modified
polyisocyanate is preferable for production of the suitable
urethane-modified isocyanate-terminated prepolymer by the reaction
with polyol.
[0142] The isocyanate-terminated prepolymer molecule contains the
isocyanate group at 0.3 to 30 wt. % (as isocyanate group content in
the isocyanate-terminated prepolymer), preferably 1 to 30 wt. %,
more preferably 4 to 25 wt. %, most preferably 5 to 25 wt. %.
[0143] The polyol for production of the isocyanate-terminated
prepolymer is not limited. Some examples include polyoxyalkylene
polyol, polyester polyol, polybutadiene polyol and polycarbonate
polyol. They may be used either alone or in combination.
[0144] Particularly preferable one is an aromatic polyester polyol
or the polyoxyalkylene polyol for the present invention, which is
reacted with a polyisocyanate to produce the urethane-modified
isocyanate-terminated prepolymer.
[0145] Especially, use of an aromatic polyester polyol as the
polyol for the isocyanate-terminated prepolymer increases content
of the isocyanate-terminated prepolymer from the aromatic polyester
polyol and polyisocyanate to 20 wt. % or more, preferably 30 wt. %
or more, more preferably 40 wt. % or more, increasing its
reactivity and hence giving the microcellular polyurethane
elastomer of excellent mechanical strength.
[0146] <<Foaming agent>>
[0147] The foaming agents useful for production of the
microcellular polyurethane elastomer of the present invention
include water, cyclopentane, trichloromethane,
trichloromonofluoromethane, 1,1,2-trichlorotrifluoromethane,
1,1-dichloro-2,2,2-trifluoroethane, and
1,1-dichloro-1-monofluoroethane. They may be used either alone or
in combination. Of these, the more preferable one is water used
alone.
[0148] <<Catalyst>
[0149] Various known catalysts may be used for the present
invention. They include amines, e.g., triethylamine,
tripropylamine, tributylamine, morpholine, N-methylmorpholine,
N-ethylmorpholine, dimethylcyclohexylamine,
1,4-diazabicyclo-(2,2,2)-octane (hereinafter referred to as TEDA),
TEDA salt, N,N,N',N'-tetramethylhexamethylenediamin- e,
N,N,N',N'-tetramethylpropylenediamine,
N,N,N',N',N"-pentamethyldiethyle- netriamine,
trimethylaminoethylpiperazine, N,N-dimethylcyclohexylamine,
N,N-dimethylbenzylamine, N-methylmorpholine, N-ethylmorpholine,
bis(dimethylaminoalkyl)piperazine,
N,N,N',N'-tetramethylethylenediamine, N,N-diethylbenzylamine,
bis(N,N-diethylaminoethyl)adipate,
N,N,N',N'-tetramethyl-1,3-butanediamine,
N,N-dimethyl-.beta.-phenylethyla- mine, 1,2-dimethylimidazole, and
2-methylimidazole; organotin compounds, e.g., tin octylate, tin
oleate, tin laurate, dibutyltin diacetate and dibutyltin dilaurate;
and organolead compounds, e.g., lead octylate and lead naphthenate.
They may be used either alone or in combination, preferably at 0.1
to 10 wt. parts per 100 wt. parts of the polyol, more preferably
0.1 to 5 wt. parts.
[0150] <<Chain extender>>
[0151] The suitable chain extender is a polyol having a low
molecular weight of 400 or less. These compounds include propylene
glycol, dipropylene glycol, ethylene glycol, diethylene glycol,
1,4-butanediol, 1,3-butanediol, neopentyl glycol, 1,6-hexanediol,
glycerin, bishydroxyethoxy benzene, bishydroxyethyl terephthalate
and diethoxy resorcin. Two or more types of the chain extenders may
be used. The preferable extenders are ethylene glycol and
1,4-butanediol. It is preferable to use the chain extender at 3 to
60 wt. parts per 100 wt. parts of the polyol, more preferably 3 to
50 wt. parts.
[0152] <<Foam stabilizer>>
[0153] The foam stabilizer for the present invention is not
limited, so long as it is generally used for production of
polyurethane foams, and known organosilicon-based surfactants may
be used. The amount used is preferably at 0.1 to 20 wt. parts per
100 wt. parts of the polyol, more preferably at 0.2 to 5 wt. parts.
The examples of the stabilizers include SRX-274C, SF-2969, SE-2961
and SF-2962 (Trade Name, produced by Toray/Dow Corning Silicone);
L-5309, L-5302, L-3601, L-5307 and L-3600 (Trade Name, produced by
NIPPON UNICAR COMPANY LTD.).
[0154] <<Other additives>>
[0155] The other additives useful for the present invention include
a yellowing inhibitor, ultraviolet ray absorber, antioxidant, flame
retardant and colorant.
[0156] <<Method of producing the microcellular polyurethane
elastomer>>
[0157] The microcellular polyurethane elastomer of the present
invention is produced by mixing, under agitation, a resin premix
with a polyisocyanate compound, wherein the resin premix is a
mixture of the polyol for the present invention (including
polyoxyalkylene polyol), and additives, e.g., chain extender, water
as the foaming agent, catalyst and foaming agent, which is prepared
beforehand. It is preferable to keep an NOC index normally at 0.8
to 1.3, more preferably 0.9 to 1.2, wherein NOC index is a ratio of
moles of the active hydrogen in the total active hydrogen compounds
(polyol, chain extender and water as the foaming agent) to moles of
the isocyanate group in the polyisocyanate compound.
[0158] The mixing with agitation is effected normally by a low- or
high-pressure circulation type foaming machine at 20 to 60.degree.
C., although varying depending on size of the molded product of the
microcellular polyurethane elastomer. When a low-pressure foaming
machine is used in an open mold, for example, the mixture of the
resin premix and polyisocyanate compound is injected into the mold,
the open mold is quickly closed by a clamp, and the mixture is
cured at 70.degree. C. for 5 to 20 min by, e.g., hot wind in a
drier.
[0159] When cured, the microcellular polyurethane elastomer is
withdrawn from the mold, to analyze its properties. The after cure,
when required, is effected normally under the conditions of, e.g.,
70.degree. C. for 24 or 2 hours.
[0160] The microcellular polyurethane elastomer is normally
incorporated with 0.1 to 5 wt. parts of water as the foaming agent,
0.1 to 20 wt. parts of a foam stabilizer, 0.1 to 10 wt. parts of a
catalyst for forming urethane and 3 to 60 wt. parts of a chain
extender, all per 100 wt. parts of the polyol, in order to satisfy
the above required characteristics.
[0161] <<Applications of the microcellular polyurethane
elastomer>>
[0162] The microcellular polyurethane elastomer of the present
invention is excellent in mechanical properties, e.g., tensile
strength, 100% modulus, maximum elongation, tear strength and
compression set, and also excellent in productivity coming from its
reduced demolding time. The shoe sole of the microcellular
polyurethane elastomer of these characteristics provides good
feeling when the shoe on the sole is worn and is excellent in
durability. Controlling cell diameter on the skin surface in a
specific range keeps good surface and coating characteristics.
Therefore, the microcellular polyurethane elastomer of the present
invention can suitably find various applications, including shoe
soles, gaskets for electric appliances, gaskets for industrial
parts, seat mats and foot mats, vibration and sound insulators, and
shock absorbers.
EFFECT OF THE INVENTION
[0163] The present invention provides a microcellular polyurethane
elastomer, excellent in mechanical properties, e.g., tensile
strength, 100% modulus, maximum elongation, tear strength and
compression set, and suitable for, e.g., shoe soles of excellent
surface and coating characteristics. The microcellular polyurethane
elastomer of the present invention, with its excellent mechanical
properties, can be lower in density than the conventional elastomer
of the equivalent mechanical properties, and can reduce weight of
the products for various purposes.
[0164] In particular, a microcellular polyurethane elastomer
retaining excellent mechanical properties can be obtained even with
a reduced demolding time.
[0165] The shoe sole or the like of such a polyurethane elastomer
provides good feeling when the shoe on the sole is worn and is
excellent in durability and surface characteristics.
EXAMPLES
[0166] The present invention will be described by Examples, which
by no means limit the present invention, wherein parts and
percentages mean wt. parts and wt. %, respectively.
[0167] <<Analytical methods>>
[0168] The characteristics determined in Examples and Comparative
Examples were measured by the following methods:
[0169] <Analysis of polyoxyalkylene polyol>
[0170] (1) Hydroxyl value (OHV, unit: mg-KOH/g) and an overall
degree of unsaturation (C.dbd.C, unit: meq./g)
[0171] These properties were determined in accordance with JIS
K-1557, in which the number of hydroxyl groups in a polyoxyalkylene
polyol corresponds to that of an active hydrogen compound used as
an initiator.
[0172] (2) Head-to-tail (H-T) linkage selectivity (unit: mol %)
[0173] The .sup.13C-NMR spectral pattern of the polyoxyalkylene
polyol was determined by a .sup.13C-nuclear magnetic resonance
(NMR) analyzer (JEOL LTD., 400 MHz) with deuterated chloroform as
the solvent. This selectivity was determined by the ratio of the
signal of methyl group (16.9 to 17.4 ppm) in the head-to-tail
linkage in the oxypropylene segment to the signal of methyl group
(17.7 to 18.5 ppm) in the head-to-head bond in the oxypropylene
segment. The methyl group to which each signal is relevant was
determined, based on the values in the report by F. C. Schiling and
A. E. Tonelli, Macromolecules, 19, 1337-1343 (1986).
[0174] (3) W.sub.20/W.sub.80 ratio (as an index representing
molecular weight distribution of polyoxyalkylene polyol, unit:
dimensionless)
[0175] W.sub.20 and W.sub.80 are widths of the peaks at 20 and 80%
of the highest peak in the gel permeation chromatography (GPC)
elution curve of the polyoxyalkylene polyol. The GPC analysis
conditions are given below:
[0176] Analyzer: Shimadzu's LC-6A system
[0177] Detector: Shimadzu's differential refractometer RID-6A
[0178] Separation column: Showa Denko's ShodexGPC, KF series (4
columns KF-801, 802, 802.5 and 803 connected in series)
[0179] Elutant: Tetrahydrofuran for liquid chromatogram
[0180] Liquid flow rate: 0.8 ml/min
[0181] Column temperature: 40.degree. C.
[0182] (4) Terminal oxyethylene group content in polyoxyalkylene
polyol (unit: wt. %)
[0183] The oxyethylene group content was determined by .sup.1H-NMR
analysis for the polyoxyalkylene polyol dissolved in deuterated
chloroform.
[0184] (5) Rate for producing the primary OH group at the terminals
(unit: mol %)
[0185] The rate for producing the primary OH group at the terminals
was determined by .sup.13C-NMR analysis for the polyoxyalkylene
polyol dissolved in deuterated chloroform.
[0186] <Methods for analyzing properties of the microcellular
polyurethane elastomer>
[0187] The sheet of the microcellular polyurethane elastomer,
formed in an aluminum mold 12.5 by 150.0 by 250.0 mm in inner
dimensions, was cut by a punching die of given dimensions, to
prepare the specimen for analyzing the properties.
[0188] (6) Average diameter of the cells observed on the skin
surface (unit: .mu.m)
[0189] The skin surface means the sheet (of the microcellular
polyurethane elastomer) in contact with an aluminum mold in which
it is formed, 12.5 by 150.0 by 250.0 mm in inner dimensions. The
surface (150.0 by 250.0 mm) in contact with the mold bottom was
observed for its cell diameters by a microcamera (Shimadzu's MICRO
CCD SCOPE/CCD-F2) at the four corners and center, for the portion
excluding the 20 mm wide sections from the edges in the length and
breadth directions. The average diameter of these cells at each of
the 5 points is determined by image processor/analyzer, and the
average cell diameter on the skin surface is determined by
averaging the average diameters at these points.
[0190] (7) Average cell diameter inside of the microcellular
polyurethane elastomer (unit: .mu.m)
[0191] The average cell diameter was determined for the inside of
the microcellular polyurethane elastomer sheet, formed in an
aluminum mold of 12.5 by 150.0 by 250.0 mm in inner dimensions by
observing diameters of the cells at the four planes of the specimen
in the sectional direction (perpendicular to the skin surface) by a
microcamera (Shimadzu's MICRO CCD SCOPE/CCD-F2), and finding the
average cell diameter by an image processor/analyzer, where the
specimen was prepared by cutting the sheet into a shape of 3 cm in
the length direction and 1 cm in the breadth direction from the
central portion, and removing the 4 mm thick upper and lower
sections.
[0192] (8) Overall density (unit: kg/m.sup.3)
[0193] The overall density was determined by dividing weight of the
sheet demolded from the mold by its volume.
[0194] (9) Hardness (unit: dimensionless)
[0195] The hardness was determined by an Asker C hardness meter in
accordance with JIS K-6301.
[0196] (10) Tensile strength (T.sub.B, unit: MPa), 100% modulus
(M.sub.100, unit: MPa) and maximum elongation (EB, unit: %)
[0197] The specimen for determining the above properties was
prepared by a dumbbell No. 1 die, and analyzed in accordance with
JIS K-6251.
[0198] (11) Tear strength (T.sub.R, unit: kN/m)
[0199] The specimen was prepared by an angle die with no notch, and
analyzed in accordance with JIS K-6252.
[0200] (12) Compression set (unit: %)
[0201] The circular specimen, 29 mm in diameter, was prepared from
the sheet, and analyzed in accordance with JIS K-6262 at
55.+-.1.degree. C. for 24 hours, with the specimen set at a
compression ratio of 25%. The compression set thus determined is
referred to as "CS."
[0202] The 29 mm diameter circular specimen prepared from the sheet
was also analyzed in accordance with JIS K-6262 at 50.+-.1.degree.
C. for 6 hours, with the specimen set at a compression ratio of
50%. The compression set thus determined is referred to as
"CS2."
[0203] (13) Viscosity of the resin premix (unit: mPa.multidot.s at
25.degree. C.)
[0204] Viscosity at 25.degree. C. of the resin premix compositions
shown in Tables 5 and 6 was determined by the B type viscometer
(Tohki Sangyo's) in accordance with JIS K-1557.
[0205] (14) Demolding time of the microcellular polyurethane
elastomer (unit: sec)
[0206] Demolding time is defined as time required for the elastomer
to be demoldable from a mold after the mixed liquid of resin premix
and polyisocyanate compound is injected into the mold. To be
demoldable means the state of the microcellular polyurethane
elastomer sheet to be completely cured and demolded from the mold
without causing any problem, e.g., partial exfoliation on the sheet
surface or sheet missing.
[0207] (15) Surface characteristics of the microcellular
polyurethane elastomer
[0208] The microcellular polyurethane elastomer, demolded out of
the mold, was visually observed to determine its surface
characteristics, based on the comprehensive judgement with respect
to gloss, and presence or absence of flow marks or pinholes, and
marked with A: good, B: average, and C: not good.
[0209] (16) Coating characteristics of the microcellular
polyurethane elastomer
[0210] The microcellular polyurethane elastomer, demolded out of
the mold, was stored at room temperature for 24 hours, and sprayed
with a black coating material (Asahi Pen's lacquer spray). It was
then dried at room temperature for 24 hours, visually observed for
gloss and presence or absence of uneven coloration on the coated
surface, and marked with A: good, B: slightly inferior in gloss or
uneven coloration slightly observed, and C: lack of gloss or uneven
coloration observed.
[0211] <<Stock materials>>
[0212] The stock materials used in Examples and Comparative
Examples are described.
[0213] <Polyoxyalkylene polyol>
Synthesis Example 1
[0214] First, synthesis of the polyoxyalkylene polyols used in
Examples will be described.
[0215] Polyoxyalkylene polyol A
[0216] A mixture of 1 mol of glycerin and 0.01 mol of
tetrakis[tris(dimethylamino)phosphoranilideneamino] phosphonium
hydroxide {[(Me.sub.2N).sub.3P.dbd.N].sub.4P.sup.+OH.sup.-} (or
P5OH) was desiccated under a vacuum at 100.degree. C. for 6 hours,
addition-polymerized with propylene oxide at 80.degree. C. and
0.372 MPaG (3.8 kg/cm.sup.2G, where G stands for gauge pressure) as
the highest pressure, and then addition-polymerized with ethylene
oxide at 100.degree. C., to prepare a polyoxyalkylene polyol having
a hydroxyl value of 28 mg-KOH/g.
[0217] The polyoxyalkylene polyol thus prepared had a terminal
oxyethylene group content of 15 wt. %, an overall degree of
unsaturation of 0.014 meq./g, and a head-to-tail linkage
selectivity of 96.8 mol %.
[0218] Polyoxyalkylene polyols B, C and D were prepared in the same
manner as for Polyoxyalkylene polyol A except that hydroxyl value
and hydroxyl group number were changed, as shown in Table 1, where
propylene oxide was used as the main monomer, and ethylene oxide
was used in a quantity to keep a terminal oxyethylene group content
at 15 wt. % in the polyoxyalkylene polyol. Polyoxyalkylene polyols
E and F were prepared in the same manner except that the terminal
oxyethylene group content was kept at 20 wt. %. Dipropylene glycol
was used as the active hydrogen compound for production of the
polyoxyalkylene polyol having a hydroxyl group number of 2, and
glycerin for production of the polyoxyalkylene polyol having a
hydroxyl group number of 3. The analysis results of Polyoxyalkylene
polyols A, B, C, D, E and F are given in Table 1.
1 TABLE 1 Polyoxyalkylene polyol A B C D E F Hydroxyl group number
3 3 2 2 3 2 Hydroxyl value (mg-KOH/g) 28 22 28 22 28 28 Terminal
oxyethylene group 15 15 15 15 20 20 content (wt. %) Rate for
producing the 80.8 80.3 81.2 80.9 90.9 91.5 primary OH group at the
terminals (mol %) Overall degree of unsaturation 0.014 0.018 0.013
0.017 0.011 0.010 (meq./g) Head-to-tail linkage 96.8 97 97.2 97 98
98.3 selectivity (mol %) W.sub.20/W.sub.80 2.67 2.63 2.61 2.59 2.51
2.48
Synthesis Example 2
[0219] Second, synthesis of the polyoxyalkylene polyols used in
Comparative Examples will be described.
[0220] Polyoxyalkylene polyol G
[0221] A mixture of 1 mol of glycerin and 0.37 mol of potassium
hydroxide (hereinafter referred to as KOH) was desiccated under
vacuum at 100.degree. C. for 6 hours, addition-polymerized with
propylene oxide at a reaction temperature of 115.degree. C. and
0.490 MPaG (5.0 kg/cm.sup.2G) as the highest pressure, and then
addition-polymerized with ethylene oxide at a reaction temperature
of 115.degree. C., to prepare a polyoxyalkylene polyol having a
hydroxyl value of 28 mg-KOH/g. The polyoxyalkylene polyol thus
prepared had a terminal oxyethylene group content of 15 wt. %, an
overall degree of unsaturation of 0.085 meq./g, and a head-to-tail
linkage selectivity of 96.3 mol %, as determined in the same manner
as in Synthesis example 1.
[0222] Polyoxyalkylene polyol H was also prepared for Comparative
Example in the same manner as for Polyoxyalkylene polyol G except
that hydroxyl value and hydroxyl group number were set at 28
mg-KOH/g and 2, respectively. Propylene oxide was used as the main
monomer, and ethylene oxide was used in a quantity to keep a
terminal oxyethylene group content at 15 wt. % in the
polyoxyalkylene polyol. Dipropylene glycol was used as the active
hydrogen compound for production of the polyoxyalkylene polyol
having a hydroxyl group number of 2. The analysis results of
Polyoxyalkylene polyols G and H are given in Table 2.
2 TABLE 2 Polyoxyalkylene polyol G H Hydroxyl group number 3 2
Hydroxyl value (mg-KOH/g) 28 28 Terminal oxyethylene group content
(wt. %) 15 15 Rate for producing the primary OH group at the 78.3
77.9 terminals (mol %) Overall degree of unsaturation (meq./g)
0.085 0.088 Head-to-tail linkage selectivity (mol %) 96.3 96.6
W.sub.20/W.sub.80 2.61 2.65
Synthesis Example 3
[0223] Synthesis of the other polyoxyalkylene polyols used in
Comparative Examples will be described.
[0224] Polyoxyalkylene polyol I
[0225] A mixture of 100 wt. parts of MN1000 (Trade Name,
polyoxypropylene polyol having an OHV of 168 mg-KOH/g (produced by
Mitsui Chemicals, Inc.) and 0.05 wt. parts of the so-called double
metal cyanide complex (DMC) catalyst, composed of zinc-cobalt
cyanide, zinc chloride, water and dimethoxyethanol, was
addition-polymerized with propylene oxide at 90.degree. C. and
0.392 MPaG (4.0 kg/cm.sup.2G) as the highest pressure, to prepare a
polyoxypropylene polyol having a hydroxyl value of 33 mg-KOH/g. The
effluent was treated with ammonia water to extract the DMC, and
washed with water to purify polyoxypropylene polyol. Then, 0.26 wt.
parts of potassium hydroxide (KOH) was added to 100 wt. parts of
the polyoxypropylene polyol, and the mixture was desiccated under a
vacuum at 100.degree. C. for 6 hours.
[0226] The polyoxypropylene polyol was then addition-polymerized
with ethylene oxide at 100.degree. C., to prepare a polyoxyalkylene
polyol having an OHV of 28 mg-KOH/g. It had a terminal oxyethylene
group content of 15 wt. %, an overall degree of unsaturation of
0.010 meq./g, and a head-to-tail linkage selectivity of 85.4 mol %,
as determined in the same manner as in Synthesis example 1.
[0227] Polyoxyalkylene polyols J, K, L, M and N were also prepared
for Comparative Example in the same manner as for Polyoxyalkylene
polyol G except that hydroxyl value and hydroxyl group number were
set at the levels shown in Table 3.
[0228] Propylene oxide was used as the main monomer, and ethylene
oxide was used in a quantity to keep a terminal oxyethylene group
content at 15 wt. % in the polyoxyalkylene polyol terminal, except
for Polyoxyalkylene polyols M and L, for which ethylene oxide was
used in a quantity to keep the terminal oxyethylene group content
at 20 wt. %. Polyoxypropylene polyol (Diol-700 (Trade Name),
produced by Mitsui Chemicals, Inc.), produced by addition
polymerization of dipropylene glycol and propylene oxide, was used
as the active hydrogen compound for production of the
polyoxyalkylene polyol having a hydroxyl group number of 2, and
polyoxypropylene polyol (MN1000 (Trade Name), produced by Mitsui
Chemicals, Inc.), produced by addition polymerization of glycerin
and propylene oxide, for production of the polyoxyalkylene polyol
having a hydroxyl group number of 3. The analysis results of
Polyoxyalkylene polyols I, J, K, L, M and N thus prepared are given
in Table 3.
3 TABLE 3 Polyoxyalkylene polyol I J K L M N Hydroxyl group number
3 3 2 2 3 2 Hydroxyl value (mg-KOH/g) 28 22 28 22 28 28 Terminal
oxyethylene group 15 15 15 15 20 20 content (wt. %) Rate for
producing the 78.3 78.0 78.5 79.1 88.6 88.5 primary OH group at the
terminals (mol %) Overall degree of 0.010 0.015 0.011 0.013 0.007
0.008 unsaturation (meq./g) Head-to-tail linkage 85.4 86.4 87.2
87.0 85.0 86.0 selectivity (mol %) W.sub.20/W.sub.80 4.18 4.06 4.60
5.15 4.50 4.81
[0229] <Polymer-dispersed polyol>
[0230] The polymer-dispersed polyols for the present invention will
be described by the examples, which by no means limit the present
invention.
[0231] The stock materials, abbreviations and analytical methods
for the examples will be described below:
[0232] Polyoxyalkylene polyols A, I; (The polyoxyalkylene polyol
used for synthesis of the polymer-dispersed polyol is hereinafter
referred to as Base PPG)
[0233] Ethylenically unsaturated monomer-1; acrylonitrile
(hereinafter referred to as AN)
[0234] Ethylenically unsaturated monomer-2; styrene (hereinafter
referred to as St)
[0235] Chain transfer agent; triethylamine (hereinafter referred to
as TEA)
[0236] Radical initiator; azobisisobutyronitrile (hereinafter
referred to as AIBN)
[0237] (17) Hydoxy value (abbreviated by OHV, unit: mg-KOH/g) and
viscosity (abbreviated by .eta., unit: mPa.multidot.s at 25.degree.
C.) of the polymer-dispersed polyol
[0238] These properties were determined in accordance with JIS
K-1557.
[0239] (18) Polymer concentration (unit: wt. %)
[0240] The polymer-dispersed polyol was well dispersed in methanol,
and the mixture was centrifugally separated, to measure weight of
the methanol insolubles. For the polymer-dispersed polyol from
acrylonitrile (AN) as the sole ethyleniclly unsaturated monomer,
the polymer concentration was determined by the nitrogen balance by
the elementary analysis.
[0241] Base PPG, put fully in a 1-liter autoclave equipped with a
thermometer, agitator and liquid-sending device, was heated to
120.degree. C., with agitation. Then, a mixture composed of 58.5
wt. parts of Base PPG, 12.45 wt. parts of AN, 29.05 wt. parts of
St, 0.55 wt. parts of V-59, 2.76 wt. parts of IPA and 0.28 wt.
parts of TEA prepared beforehand was continuously charged into the
autoclave, and the polymer-dispersed polyol was continuously
discharged from the discharge port. The reaction conditions were
0.444 MPaG (3.5 kgf/cm.sup.2G) as pressure and 50 min as residence
time. The effluent, collected after the steady-state conditions
were attained, was thermally treated under a vacuum at 120.degree.
C. and 2.66 kPa (20 mmHg, abs.) for 3 hours, to prepare
Polymer-dispersed polyols O and P after the unreacted ethylenically
unsaturated monomer, and residual additives, e.g., decomposed
polymerization initiator and chain transfer agent were removed. The
results are given in Table 4.
4 TABLE 4 Polymer-dispersed polyol O P Base PPG A I Hydroxyl group
number 3 3 Hydroxyl value (mg-KOH/g) 20.1 20.2 Polymer
concentration (wt. %) 30.5 30.2 St/AN wt. ratio 70/30 70/30
[0242] <Polyisocyanate compound>
[0243] Isocyanate-terminated prepolymer Q
[0244] Isocyanate-terminated prepolymer Q was prepared by the
following procedure: 676 wt. parts of 4,4-diphenylmethane
diisocyanate (Cosmonate PH (Trade Name), produced by Mitsui
Chemicals, Inc.) was reacted with 324 wt. parts of polyoxypropylene
diol (Diol-1000 (Trade Name), produced by Mitsui Chemicals, Inc.),
having an OHV of 112 mg-KOH/g) in a nitrogen atmosphere in a
separable flask at 80.degree. C. for 2 hours. It had an isocyanate
group content of 20 wt. %.
[0245] Isocyanate-terminated prepolymer R
[0246] A mixture of 100 parts of terephthalic acid and 125 parts of
tripropylene glycol was charged in a four-necked flask, equipped
with an agitation rod, dehydration tube, nitrogen gas introduction
tube and thermometer. Next, a nitrogen gas was introduced into the
flask, water produced was distilled off while carefully controlling
bumping, and the content was heated to 200.degree. C. The effluent
was incorporated with 0.045 parts of tetraisopropyl titanate as the
titanium-based catalyst, after its acid value was decreased to 20
or less, and system pressure was slowly reduced to a vacuum of 1.33
kPa, at which water was further distilled off. The reaction was
continued until acid value of the effluent was decreased to 1
mg-KOH/g or less, to prepare Aromatic polyester polyol S. The
reaction system was returned back to the normal pressure, and the
effluent was cooled to 80.degree. C. and incorporated with 3.4 wt.
parts of distilled water. The mixture was continuously heated for 2
hours, with agitation, to deactivate the titanium-based catalyst,
and water was distilled off under a vacuum. Aromatic polyester
polyol S thus prepared had an acid value of 0.3 mg-KOH/g and
hydroxyl value of 113.1 mg-KOH/g.
[0247] Isocyanate-terminated prepolymer R was prepared in the same
manner as for Isocyanate-terminated prepolymer Q, except that
Aromatic polyester polyol S was used as the polyol working as the
isocyanate modifier.
[0248] <Catalyst>
[0249] MINICO; Trade Name, produced by Katuzai Chemical, amine
catalyst (triethylenediamine)
[0250] <Chain extender>
[0251] Ethylene glycol; produced by Wako Pure Chemical
Industries'
[0252] <Foam stabilizer>
[0253] SF-2962; Trade Name, produced by Toray/Dow Corning Silicone,
silicone foam stabilizer, <Foaming agent>
[0254] Ion-exchanged water (hereinafter merely referred to as
water)
Examples and Comparative Examples
[0255] Examples and Comparative Examples will be described
below.
[0256] Each composition of polyoxyalkylene polyol, the chain
extender and water as the foaming agent, foam stabilizer and
catalyst (this composition is hereinafter referred to as resin
premix) is described in Table 5 or 6, where unit for all of the
items is wt. parts, except for molar ratio.
[0257] Table 5 describes the compositions of the present invention,
prepared by Examples 1 to 5, each comprising Polyoxyalkylene polyol
A, B, C, D, E or F, and the one prepared by Example 4 additionally
containing Polymer-dispersed polyol O. Table6describes the
compositions prepared by Comparative Examples, wherein the resin
premix prepared by Comparative Example 1 comprised Polyoxyalkylene
polyols G and H, each polymerized in the presence of a KOH
catalyst, and those prepared by Comparative Examples 2 to 6
comprised Polyoxyalkylene polyol I, J, K, L, M or N, each
polymerized in the presence of a DMC catalyst, the one prepared by
Comparative Example 5 additionally containing Polymer-dispersed
polyol P.
Example 1
[0258] A mixture of 372 wt. parts of Polyoxyalkylene polyol A, 563
wt. parts of Polyoxyalkylene polyol C, 45 wt. parts of the chain
extender, 5 wt. parts of water, 5 wt. parts of the catalyst and 10
wt. parts of the foam stabilizer was agitated for mixing at 500 rpm
in a stainless steel container for 5 min, to prepare the resin
premix. A polyisocyanate compound was added to the resin premix in
a quantity to keep an isocyanate index NCO/OH at 1.0, i.e., ratio
of moles of the active hydrogen in the resin premix to moles of the
isocyanate group in the polyisocyanate compound, wherein the resin
premix and polyisocyanate compound were kept at 40.degree. C.
beforehand. The mixture was agitated for further mixing at 1,500
rpm in a homomixer for 3 sec, and immediately injected into an
aluminum mold, 12.5 by 150.0 by 250.0 mm in inner dimensions, kept
at 40.degree. C. beforehand. The mold was closed, and put in an
oven, also kept at 40.degree. C. beforehand. The microcellular
polyurethane elastomer thus prepared was analyzed for its demolding
time, and various properties after it was demolded out of the
mold.
[0259] Table 7 gives viscosity of the resin premix, and Table 8
demolding time and Table 9 properties of the microcellular
polyurethane elastomer.
Example 2
[0260] The microcellular polyurethane elastomer was prepared in the
same manner as in Example 1, except that Polyoxyalkylene polyols A
and C were replaced by Polyoxyalkylene polyols B and D. Table 5
gives its composition (where unit for all of the items is wt.
parts, except that for NCO/OH), and Table 8 its demolding time and
Table 9 properties.
Example 3
[0261] The microcellular polyurethane elastomer was prepared in the
same manner as in Example 1, except that Polyoxyalkylene polyols A
and C were replaced by Polyoxyalkylene polyols E and F. Table 5
gives its composition, and Table 8 its demolding time and Table 9
properties.
Example 4
[0262] The microcellular polyurethane elastomer was prepared in the
same manner as in Example 1, except that Polyoxyalkylene polyols A
and C were replaced by Polyoxyalkylene polyol C and
Polymer-dispersed polyol O. Table 5 gives its composition, and
Table 8 its demolding time and Table 9 properties.
Example 5
[0263] The microcellular polyurethane elastomer was prepared in the
same manner as in Example 3, except that Isocyanate-terminated
prepolymer R was used as the polyisocyanate compound. Table 5 gives
its composition, and Table 8 its demolding time and Table 9
properties.
5 TABLE 5 Example Example Example Example Example 1 2 3 4 5 Resin
Polyoxy-alkylene A 372 -- -- -- -- premix polyol B -- 376 -- -- --
C 563 -- -- 683 -- D -- 569 -- -- -- E -- -- 372 -- 372 F -- -- 563
-- 563 Polymer-dispersed O -- -- -- 171 -- polyol Chain extender 45
36 45 100 45 Water 5 4 5 6 5 Catalyst 5 5 5 20 5 Foam stabilizer 10
10 10 20 10 Isocyanate-terminated Q 519 431 519 902 -- prepolymer R
-- -- -- -- 519 NCO/OH 1.0 1.0 1.0 1.0 1.0
Comparative Example 1
[0264] The microcellular polyurethane elastomer was prepared in the
same manner as in Example 1, except that Polyoxyalkylene polyols A
and C were replaced by Polyoxyalkylene polyols G and H produced in
the presence of a KOH catalyst. Table 6 gives its composition
(where unit for all of the items is wt. parts, except that for
NCO/OH), Table 7 viscosity of the resin premix, and Table 8 its
demolding time and Table 10 properties.
Comparative Example 2
[0265] The microcellular polyurethane elastomer was prepared in the
same manner as in Example 1, except that Polyoxyalkylene polyols A
and C were replaced by Polyoxyalkylene polyols I and K produced in
the presence of a DMC catalyst. Table 6 gives its composition,
Table 7 viscosity of the resin premix, and Table 8 its demolding
time and Table 10 properties of the microcellular polyurethane
elastomer.
Comparative Example 3
[0266] The microcellular polyurethane elastomer was prepared in the
same manner as in Example 1, except that Polyoxyalkylene polyols A
and C were replaced by Polyoxyalkylene polyols J and L produced in
the presence of a DMC catalyst. Table 6 gives its composition, and
Tables 8 and 10 its demolding time and properties.
Comparative Example 4
[0267] The microcellular polyurethane elastomer was prepared in the
same manner as in Example 1, except that Polyoxyalkylene polyols A
and C were replaced by Polyoxyalkylene polyols M and N produced in
the presence of a DMC catalyst. Table 6 gives its composition, and
Table 8 its demolding time and Table 10 properties.
Comparative Example 5
[0268] The microcellular polyurethane elastomer was prepared in the
same manner as in Example 1, except that Polyoxyalkylene polyols A
and C were replaced by Polyoxyalkylene polyols K produced in the
presence of a DMC catalyst and Polymer-dispersed polyol P. Table 6
gives its composition, and Table 8 its demolding time and Table 10
properties.
6 TABLE 6 Comparative Comparative Comparative Comparative
Comparative Example Example Example Example Example 1 2 3 4 5 Resin
Polyoxy-alkylene G 372 -- -- -- -- premix polyol H 563 -- -- -- --
I -- 372 -- -- -- J -- -- 376 -- -- K -- 563 -- -- 683 L -- -- 569
-- -- M -- -- -- 372 -- N -- -- -- 563 -- Polymer-dispersed P -- --
-- -- 171 polyol Chain extender 45 45 36 45 100 Water 5 5 4 5 6
Catalyst 5 5 5 5 20 Foam stabilizer 10 10 10 10 20
Isocyanate-terminated Q 519 519 431 519 902 prepolymer R -- -- --
-- -- Molar ratio (NCO/OH) 1.0 1.0 1.0 1.0 1.0
[0269]
7 TABLE 7 Comparative Comparative Example 1 Example 1 Example 2
Resin premix viscosity 910 1050 1220 (mPa .multidot. s at
25.degree. C.)
[0270]
8 TABLE 8 Comparative Comparative Comparative Comparative
Cornparative Example 1 Example 2 Example 3 Example 4 Example 5
Example 1 Example 2 Example 3 Example 4 Example 5 Demolding 480 490
420 380 380 660 540 550 530 500 time (sec)
[0271]
9 TABLE 9 Example 1 Example 2 Example 3 Example 4 Example 5 Overall
510 510 510 510 510 density (kg/m.sup.3) Average cell 44 42 40 45
40 diameter on the skin sur- face (.mu.m) Diameter of 15-80 15-80
15-80 20-100 15-80 inside cell (.mu.m) Average 40 42 45 55 50
diameter of inside cell (.mu.m) Hardness 70 69 70 75 72 (Asker C)
T.sub.B (MPa) 4.2 4.5 4.5 5.5 5.6 M.sub.100 (MPa) 2.5 2.7 2.8 3.4
3.3 E.sub.B (%) 390 400 400 400 360 T.sub.R (kN/m) 26 29 31 40 38
CS (%) 5 3 6 7 5 CS2 (%) 9 8 9 8 9 Surface A A A A A character-
istics Coating A A A A A character- istics
[0272]
10 TABLE 10 Com- Com- Com- Com- Com- parative parative parative
parative parative Example 1 Example 2 Example 3 Example 4 Example 5
Overall 510 510 510 510 510 density (kg/m.sup.3) Average cell 65 70
75 72 80 diameter on the skin sur- face (.mu.m) Diameter of 25-110
20-90 20-90 25-100 30-150 inside cell (.mu.m) Average 85 90 88 110
120 diameter of inside cell (.mu.m) Hardness 72 70 70 71 74 (Asker
C) T.sub.B (MPa) 2.2 3.4 3.6 3.8 4.9 M.sub.100 (MPa) 1.8 2.2 2.3
2.6 2.7 E.sub.B (%) 280 340 350 350 340 T.sub.R (kN/m) 14 18 20 19
26 CS (%) 12 10 9 10 15 CS2 (%) 24 21 18 22 22 Surface C B C B B
character- istics Coating C B B B B character- istics
[0273] All of the microcellular polyurethane elastomers prepared by
Examples 1 to 5 and Comparative Examples 1 to 5 had an overall
density of 510 (kg/m.sup.3), and the numerals of the correlations
for the present invention between compression set (CS2) and overall
density (D) are given below:
0.00008*D.sup.2-0.091*D+42=16.4
0.00008*D.sup.2-0.091*D+40=14.4
0.00008*D.sup.2-0.091*D+38=12.4
[0274] The numerals of the correlations for the present invention
between cell diameter (X) and overall density (D) are given
below:
120e.sup.-0.0015.sup..sup.D=55.8
110e.sup.-0.0015.sup..sup.D=51.2
100e.sup.-0.0015.sup..sup.D=46.5
[0275] The mechanical properties of the microcellular polyurethane
elastomers having an overall density of 350 (kg/m.sup.3) are given
in Table 11, wherein those prepared by Examples 6 and 7 had the
same compositions as those prepared by Examples 1 and 2 (Table 5)
and those prepared by Comparative Examples 6 to 8 had the same
compositions as those prepared by Comparative Examples 1 to 3
(Table 6). Their quantities injected into the mold were adjusted to
have the different overall density.
11 TABLE 11 Com- Com- Com- parative parative parative Example 6
Example 7 Example 6 Example 7 Example 8 Overall 350 350 350 350 350
density (kg/m.sup.3) Average cell 50 55 80 90 85 diameter on the
skin sur- face (.mu.m) Diameter of 30-150 30-150 50-210 60-220
60-220 inside cell (.mu.m) Average 95 95 150 145 155 diameter of
inside cell (.mu.m) Hardness 16 18 16 17 16 (Asker C) TB (MPa) 1.2
1.3 0.9 0.8 0.8 EB (%) 320 330 300 310 310 TR (KN/m) 6.0 5.9 4.9
5.1 4.8 CS (%) 8 9 17 13 12 CS2 (%) 10 13 28 24 23
[0276] The numerals of the correlations for the present invention
between cell diameter (X) and overall density (D) are given below
for the microcellular polyurethane elastomers prepared by Examples
6 and 7 and Comparative Examples 6 to 8 having an overall density
of 350 (kg/m.sup.3):
0.00008*D.sup.2-0.091*D+42=20.0
0.00008*D.sup.2-0.091*D+40=18.0
0.00008*D.sup.2-0.091*D+38=16.0
[0277] The numerals of the correlations for the present invention
between cell diameter (X) and overall density (D) are given
below:
120e.sup.-0.0015.sup..sup.D=71.0
110e.sup.-0.0015.sup..sup.D=65.1
100e.sup.-0.0015.sup..sup.D=59.2
[0278] To explain these results: the microcellular polyurethane
elastomers of the present invention, prepared by Examples 1 to 5,
showed a shorter demolding time and hence greatly contributing to
improvement of productivity than those using the polyoxyalkylene
polyols polymerized in the presence of the conventional KOH
catalyst (Comparative Example 1) and in the presence of the DMC
catalyst (Comparative Examples 2 to 5), as shown in Table 8.
[0279] It is noted that the microcellular polyurethane elastomers
of the present invention, prepared by Examples 1 to 5, show
excellent mechanical properties, having a much higher tensile
strength, 100% modulus, maximum elongation and tear strength, and a
much lower compression set than those using the polyoxyalkylene
polyols polymerized in the presence of the conventional KOH
catalyst (Comparative Example 1) and in the presence of the DMC
catalyst (Comparative Examples 2 to 5), as shown in Tables 9 and
10. Improved mechanical properties, and surface and coating
characteristics are also noted with the microcellular polyurethane
elastomer prepared by Example 4 which used the polymer-dispersed
polyol and that prepared by Example 5 which used the aromatic
polyester polyol as the isocyanate-terminated prepolymer
modifier.
[0280] It is also noted that even the microcellular polyurethane
elastomer of low overall density exhibited improved mechanical
properties, because those prepared by Examples 6 and 7 have a much
higher tensile strength, 100% modulus, maximum elongation and tear
strength, and a much lower compression set than those prepared by
Comparative Examples 6 to 8, as shown in Table 11.
[0281] The microcellular polyurethane elastomer satisfies the
compression set (CS2) requirement for the present invention, when
its cell diameter (X) on the skin surface is in the specific range.
The cell diameter (X) is an important factor to have the
microcellular polyurethane elastomer, exhibiting not only good
surface characteristics as the important property but also
excellent mechanical properties.
[0282] Use of the polyoxyalkylene polyol having a hydroxyl value
(OHV), an overall degree of unsaturation and head-to-tail (H-T)
linkage selectivity each in a specific range can easily give the
microcellular polyurethane elastomer of excellent mechanical
properties, i.e., greatly increased tensile strength, 100% modulus,
maximum elongation and tear strength and greatly decreased
compression set, and, at the same time, excellent surface and
coating characteristics.
* * * * *