U.S. patent application number 12/624780 was filed with the patent office on 2010-03-25 for polychloroprene latex composition and its production method.
This patent application is currently assigned to Denki Kagaku Kogyo Kabushiki Kaisha. Invention is credited to Motohiro Ose, Kosuke Watanabe.
Application Number | 20100076149 12/624780 |
Document ID | / |
Family ID | 33458355 |
Filed Date | 2010-03-25 |
United States Patent
Application |
20100076149 |
Kind Code |
A1 |
Watanabe; Kosuke ; et
al. |
March 25, 2010 |
POLYCHLOROPRENE LATEX COMPOSITION AND ITS PRODUCTION METHOD
Abstract
A nonionic polychloroprene latex composition employing a
polyvinyl alcohol as an emulsifier/dispersant has favorable
chemical and mechanical stability but has a high viscosity, and
therefore it has such drawbacks that its coating method is limited,
and it is hardly made to have a high solid content. A
polychloroprene latex composition which has a low viscosity and
which can be made to have a high solid content, can be obtained by
emulsion polymerization of chloroprene alone or chloroprene and a
monomer copolymerizable with chloroprene in the presence of a
polyvinyl alcohol and a nonionic emulsifier.
Inventors: |
Watanabe; Kosuke; (Niigata,
JP) ; Ose; Motohiro; (Niigata, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, L.L.P.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
Denki Kagaku Kogyo Kabushiki
Kaisha
Chuo-ku
JP
|
Family ID: |
33458355 |
Appl. No.: |
12/624780 |
Filed: |
November 24, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10556720 |
Nov 14, 2005 |
|
|
|
PCT/JP04/06714 |
May 12, 2004 |
|
|
|
12624780 |
|
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Current U.S.
Class: |
524/552 ;
526/209 |
Current CPC
Class: |
C08F 2/30 20130101; C08F
36/18 20130101; C08L 71/02 20130101; C09D 111/02 20130101; C08F
36/18 20130101; C08L 29/04 20130101; C09J 111/02 20130101; C09J
111/02 20130101; C08L 2666/04 20130101; C09J 111/02 20130101; C08L
11/02 20130101; C08L 2666/14 20130101; C08L 2666/14 20130101; C08F
2/30 20130101; C08L 2666/04 20130101 |
Class at
Publication: |
524/552 ;
526/209 |
International
Class: |
C08L 27/04 20060101
C08L027/04; C08F 2/30 20060101 C08F002/30 |
Foreign Application Data
Date |
Code |
Application Number |
May 14, 2003 |
JP |
2003-136182 |
May 22, 2003 |
JP |
2003-144332 |
Apr 16, 2004 |
JP |
2004-121135 |
Claims
1. A polychloroprene latex composition obtained by emulsion
polymerization of chloroprene alone or chloroprene and a monomer
copolymerizable with chloroprene, in the presence of a polyvinyl
alcohol and a nonionic emulsifier represented by the formula:
##STR00003## wherein each of R and R' is an alkyl group or an aryl
group, and each of m and n is an integer).
2. The polychloroprene latex composition according to claim 1,
wherein the nonionic emulsifier has a HLB value of from 14 to
19.
3. The polychloroprene latex composition according to claim 1,
wherein the monomer copolymerizable with chloroprene is an
ethylenically unsaturated carboxylic acid.
4. The polychloroprene latex composition according to claim 1,
wherein the polyvinyl alcohol has a saponification degree of from
60 to 98 mol %.
5. The polychloroprene latex composition according to claim 1,
wherein the total amount of the polyvinyl alcohol and the nonionic
emulsifier is from 1 to 10 parts by mass, per 100 parts by mass of
chloroprene alone, or the total amount of chloroprene and the
monomer copolymerizable with chloroprene, and the ratio (mass
ratio) of the polyvinyl alcohol/the nonionic emulsifier is within a
range of from 0.5/99.5 to 99.5/0.5.
6. The polychloroprene latex composition according to claim 1,
which has a solid content concentration of from 45 to 75 mass
%.
7. The polychloroprene latex composition according to claim 6,
which has a pH of from 6 to 9, and a viscosity of from 5 to 5,000
mPas.
8. An adhesive employing the polychloroprene latex composition as
defined in claim 1.
9. The adhesive according to claim 8, wherein the gel content
(toluene-insoluble matter) of a (co)polymer contained in the
polychloroprene latex composition is from 3 to 30 mass %.
10. A coating agent employing the polychloroprene latex composition
as defined in claim 1.
11. A method for producing the polychloroprene latex composition as
defined in claim 1, which comprises emulsion polymerization of
chloroprene alone, or chloroprene and a monomer copolymerizable
with chloroprene, in the presence of a polyvinyl alcohol and the
nonionic emulsifier.
12. An adhesive employing the polychloroprene latex composition as
defined in claim 1, wherein the chloroprene is polymerized
alone.
13. An adhesive employing the polychloroprene latex composition as
defined in claim 1, wherein the chloroprene is polymerized with the
monomer copolymerizable with chloroprene.
Description
CONTINUATION DATA
[0001] This application is a Continuation of U.S. application Ser.
No. 10/556,720, filed Nov. 14, 2005, which is a National Stage of
PCT/JP04/06714, filed May 12, 2004.
TECHNICAL FIELD
[0002] The present invention relates to a nonionic polychloroprene
latex composition having a low viscosity. Such a polychloroprene
latex composition has a low viscosity, even though it is a nonionic
type, and thereby has such advantages that it is useful also for
spray coating, a high solid content is likely to be achieved, etc.,
and is suitable as a material for an aqueous adhesive.
BACKGROUND ART
[0003] As a polychloroprene latex composition, an anionic latex
employing resin acid as an emulsifier has been well known. However,
an anionic latex employing resin acid has a drawback in chemical
and mechanical stability when used as a material for an aqueous
adhesive. As a means of improving this point, an anionic latex
employing a special sulfonate as an emulsifier has been known, but
as the latex is acidic, there are such problems that a pH decrease
is significant, and a metal may be eroded (e.g. "Adhesion
Technology" vol. 21, No. 4 (2002) Serial Number 65 (p. 17,
2.2.2.2)).
[0004] In order to solve such problems, a nonionic polychloroprene
latex composition employing a polyvinyl alcohol as an emulsifier/a
dispersant has been proposed. However, since such a latex itself
has a high viscosity, there are such problems that the coating
method is limited, and it is difficult to achieve a high solid
content by concentration (JP-A-2000-303043 (Claims 1 and 2,
Examples 1 to 6), JP-A-2002-53703 (Claims 1 and 2, Examples 1 to
6)).
DISCLOSURE OF THE INVENTION
[0005] Under these circumstances, the present invention is to
provide a nonionic polychloroprene latex composition excellent in
chemical and mechanical stability, having a pH stable in the
vicinity of a neutral pH and having a low viscosity, and its
production method.
[0006] Further, it is to provide a nonionic polychloroprene latex
composition having, as a secondary effect by making the composition
have a low viscosity, a high solid content i.e. a high solid
content concentration.
[0007] The present inventors have conducted extensive studies to
achieve the above objects and as a result, found that a nonionic
polychloroprene latex composition excellent in chemical and
mechanical stability, with a small decrease of pH, and having a low
viscosity, can be obtained by emulsion polymerization of
chloroprene alone or chloroprene and a monomer copolymerizable with
chloroprene in the presence of a polyvinyl alcohol and a nonionic
emulsifier. The present invention has been accomplished on the
basis of this discovery.
[0008] Namely, the present invention provides the following:
(1) A polychloroprene latex composition obtained by emulsion
polymerization of chloroprene alone or chloroprene and a monomer
copolymerizable with chloroprene, in the presence of a polyvinyl
alcohol and a nonionic emulsifier. (2) The polychloroprene latex
composition according to the above (1), wherein the nonionic
emulsifier is a polyoxyethylene alkyl ether. (3) The
polychloroprene latex composition according to the above (1),
wherein the nonionic emulsifier is a polyoxyethylene-acetylene
glycol ether represented by the formula (1):
##STR00001##
(wherein each of R and R' is an alkyl group or an aryl group, and
each of m and n is an integer). (4) The polychloroprene latex
composition according to any one of the above (1) to (3), wherein
the nonionic emulsifier has a HLB value of from 14 to 19. (5) The
polychloroprene latex composition according to any one of the above
(1) to (4), wherein the monomer copolymerizable with chloroprene,
is an ethylenically unsaturated carboxylic acid. (6) The
polychloroprene latex composition according to any one of the above
(1) to (5), wherein the polyvinyl alcohol is one having a
saponification degree of from 60 to 98 mol %. (7) The
polychloroprene latex composition according to any one of the above
(1) to (6), wherein the total amount of the polyvinyl alcohol and
the nonionic emulsifier is from 1 to 10 parts by mass, per 100
parts by mass of chloroprene alone, or the total amount of
chloroprene and the monomer copolymerizable with chloroprene, and
the ratio (mass ratio) of the polyvinyl alcohol/the nonionic
emulsifier is within a range of from 0.5/99.5 to 99.5/0.5. (8) The
polychloroprene latex composition according to any one of the above
(1) to (7), which has a solid content concentration of from 45 to
75 mass %. (9) The polychloroprene latex composition according to
the above (8), which has a pH of from 6 to 9, and a viscosity of
from 5 to 5,000 mPas. (10) An adhesive employing the
polychloroprene latex composition as defined in any one of the
above (1) to (9). (11) The adhesive according to the above (10),
wherein the gel content (toluene-insoluble matter) of a (co)polymer
contained in the polychloroprene latex composition is from 3 to 30
mass %. (12) A coating agent employing the polychloroprene latex
composition as defined in any one of the above (1) to (9). (13) A
method for producing a polychloroprene latex composition, which
comprises emulsion polymerization of chloroprene alone, or
chloroprene and a monomer copolymerizable with chloroprene, in the
presence of a polyvinyl alcohol and a nonionic emulsifier.
EFFECTS OF THE INVENTION
[0009] The polychloroprene latex composition obtainable by the
present invention has a low viscosity as compared with a
conventional nonionic polychloroprene latex composition obtained by
emulsion polymerization employing a polyvinyl alcohol alone.
Accordingly, a method of coating it is not limited, and it can be
made to have a high solid content. Accordingly, it is very suitable
as a material for an aqueous adhesive.
BEST MODE FOR CARRYING OUT THE INVENTION
[0010] Now, the present invention will be explained in detail
below. The chloroprene of the present invention is
2-chloro-1,3-butadiene obtainable via acetylene or butadiene.
[0011] The monomer copolymerizable with chloroprene of the present
invention may, for example, be 2,3-dichloro-1,3-butadiene,
1-chloro-1,3-butadiene, butadiene, isoprene, styrene,
acrylonitrile, acrylic acid or its ester, or methacrylic acid or
its ester, and two or more of them may be used as the case
requires.
[0012] Particularly, copolymerization of an unsaturated carboxylic
acid represented by acrylic acid, methacrylic acid, maleic acid or
fumaric acid is preferred in view of improvement of adhesive force
and emulsion stability during emulsion polymerization.
Particularly, copolymerization of an ethylenically unsaturated
carboxylic acid such as methacrylic acid is preferred in view of
copolymerizability with chloroprene.
[0013] The amount of the monomer copolymerizable with chloroprene
is not particularly limited. It is preferably at most 50 parts by
mass, particularly preferably from 0.5 to 20 parts by mass, per 100
parts by mass of chloroprene, with a view to maintaining
characteristics of the polychloroprene.
[0014] Particularly when an unsaturated carboxylic acid is
copolymerized, its amount is preferably at most 10 parts by mass,
more preferably from 0.2 to 5 parts by mass, furthermore preferably
from 0.5 to 3.5 parts by mass, particularly preferably from 0.7 to
2.0 parts by mass, per 100 parts by mass of chloroprene. If the
amount of the unsaturated carboxylic acid is too small, its
contribution to adhesive force may be insufficient, and if it is
too large, the emulsified state may be unstable.
[0015] The polyvinyl alcohol in the present invention is not
particularly limited. Preferred is one having a saponification
degree of from 60 to 98 mol %, more preferred is one having a
saponification degree of from 75 to 95 mol %, and more preferred is
one having a saponification degree of from 75 to 90 mol %.
[0016] The degree of polymerization of the polyvinyl alcohol is
preferably from 200 to 3,000, more preferably from 200 to 700.
[0017] When the polyvinyl alcohol has a degree of polymerization
within this range, polymerization operation can be stably carried
out, and a chemically and mechanically stable polychloroprene latex
composition can be obtained at a high concentration.
[0018] Further, as the case requires, a polyvinyl alcohol having
another monomer copolymerized may also be used. As an example of
the copolymer, a copolymer with acrylamide may be mentioned.
[0019] The nonionic emulsifier in the present invention is not
particularly limited, and it may, for example, be a polyoxyethylene
alkyl ether, a polyoxyethylene alkyl aryl ether, a polyoxyethylene
styryl phenyl ether, a polyoxyethylene alkyl phenyl ether, a
polyoxyalkylene alkyl ether, a polyoxyethylene-acetylene glycol
ether or a sorbitan fatty acid ester.
[0020] Among such nonionic emulsifiers, a polyoxyethylene alkyl
ether is suitably used. The polyoxyethylene alkyl ether may, for
example, be preferably a polyoxyethylene lauryl ether, a
polyoxyethylene cetyl ether, a polyoxyethylene stearyl ether, a
polyoxyethylene higher alcohol ether, a polyoxyethylene myristyl
ether or a mixture thereof, but is not limited thereto.
[0021] Further, a polyoxyethylene-acetylene glycol ether
represented by the formula (1) is also suitably employed. The
polyoxyethylene-acetylene glycol ether may, for example, be one
obtained by adding ethylene oxide to
2,4,7,9-tetramethyl-5-decyn-4,7-diol. In the formula (1), values m
and n can be changed by changing the proportion of ethylene oxide
added. Practically, the values m and n are controlled as values
with a certain distribution, and thus the addition amount (m+n) of
ethylene oxide is usually represented as an average.
[0022] If the production cost is not considered, it is possible to
accurately control the values m and n, and such a product may also
be used for the present invention:
##STR00002##
wherein each of R and R' is an alkyl group preferably having from 1
to 10 carbon atoms or an aryl group, and each of m and n is an
integer of preferably from 1 to 50.
[0023] The HLB value of the nonionic emulsifier of the present
invention is preferably at least 14, more preferably from 15 to
19.5, furthermore preferably from 16 to 19. If the HUB value is
small, the chloroprene latex composition tends to be poor in
stability, and deposits may form during the polymerization. The HLB
value is a numerical value representing the balance between
hydrophilic groups and lipophilic groups in an emulsifier (e.g.
"New Edition Surfactant Handbook 2000", Tokiyuki Yoshida et al,
Kougakutosho Ltd., p. 234).
[0024] The total amount of the polyvinyl alcohol and the nonionic
emulsifier in the present invention is not particularly limited. It
is preferably from 1 to 10 parts by mass, more preferably from 2 to
6 parts by mass, furthermore preferably from 3 to 5 parts by mass,
per 100 parts by mass of chloroprene alone or the total amount of
chloroprene and the monomer copolymerizable with chloroprene. If
the total amount of the polyvinyl alcohol and the nonionic
emulsifier is less than 1 part by mass, the emulsification power
tends to be insufficient, and agglomerates are likely to form
frequently during the polymerization reaction. Further, if it
exceeds 10 parts by mass, production may be difficult due to
abnormal heat generation or thickening during the polymerization
reaction, or the adhesive properties may significantly be
impaired.
[0025] The ratio of the polyvinyl alcohol to the nonionic
emulsifier is not particularly limited. The mass ratio of the
polyvinyl alcohol/the nonionic emulsifier is preferably from
0.5/99.5 to 99.5/0.5, more preferably from 50/50 to 1/99,
furthermore preferably from 30/70 to 5/95. If the above ratio is
too high, water resistance may decrease, or thickening may occur
during the polymerization reaction, thus making the production
difficult. Further, if the above ratio is too small, emulsification
power may be insufficient, and agglomerates are likely to form
frequently during the polymerization reaction.
[0026] In the present invention, a chain transfer agent may be
added at the time of the emulsion polymerization to adjust the
content of a gel which is a polymer insoluble in toluene or the
molecular weight of the polychloroprene. The chain transfer agent
is not particularly limited, and one usually used for emulsion
polymerization of chloroprene may be used. It may, for example, be
a long chain alkyl mercaptan such as n-dodecyl mercaptan or
tert-dodecyl mercaptan, a dialkyl xanthogen disulfide such as
diisopropyl xanthogen disulfide or diethyl xanthogen disulfide, or
iodoform.
[0027] In the present invention, the temperature at which
chloroprene alone or chloroprene and the monomer copolymerizable
with chloroprene are polymerized in production of a polychloroprene
latex composition is not particularly limited. It is preferably
from 0 to 55.degree. C., more preferably from 10 to 50.degree. C.,
so that the polymerization reaction will smoothly proceed. If the
polymerization temperature is lower than 0.degree. C., water may
freeze, and if it is higher than 55.degree. C., chloroprene tends
to volatilize in a large amount, and a countermeasure against it
will be required.
[0028] As a polymerization initiator, a persulfate such as
potassium persulfate, an organic peroxide such as
tert-butylhydroperoxide may, for example, be suitably used, but the
initiator is not limited thereto.
[0029] In a case where the polymerization temperature is set to
20.degree. C. or below, it is preferred to use sodium sulfite,
ferrous sulfate, sodium anthraquinone-.beta.-sulfonate, Rongalite,
ascorbic acid, formamidinesulfinic acid or the like in combination
in the form of a so-called redox initiator, whereby polymerization
will smoothly proceed.
[0030] The final degree of polymerization of the polychloroprene
latex composition of the present invention is not particularly
limited and can optionally be adjusted. For that purpose, a
polymerization terminator (polymerization inhibitor) may be used to
terminate the polymerization. The polymerization terminator is not
particularly limited, and a common polymerization terminator may be
used, such as 2,6-tert-butyl-4-methylphenol, phenothiazine or
hydroxylamine.
[0031] On that occasion, an unreacted monomer is removed by monomer
removal operation, and its method is not particularly limited.
[0032] Further, the solid content concentration (sometimes referred
to simply as solid content) of the polychloroprene latex
composition of the present invention is not particularly limited,
and the solid content concentration can be controlled to a
necessary concentration by concentration or dilution by addition of
water or the like. The solid content concentration in the present
invention may be determined also by a method in accordance with JIS
K6387-2.
[0033] Considering use of the composition as an adhesive, the solid
content concentration is preferably at least 45 mass %, more
preferably at least 50 mass %, furthermore preferably at least 55
mass %, in view of drying rate. However, if the solid content is 75
mass % or higher, stability may be impaired practically.
Particularly, the polychloroprene latex composition of the present
invention has a low viscosity as compared with a conventional
nonionic latex and therefore it has such an advantage that it is
easily made to have a high solid content. Accordingly, it is
preferred to increase the solid content by concentration.
[0034] The concentration method may, for example, be vacuum
concentration, but it is not particularly limited. In general, it
is economical to carry out the operation of the monomer removal to
the concentration continuously by heating under reduced
pressure.
[0035] The structure of the polychloroprene latex composition of
the present invention is not particularly limited, and it is
possible to adjust the solid content concentration, the molecular
weight of toluene-soluble matter, the toluene-insoluble matter (gel
content), etc. by appropriately selecting or controlling the
polymerization temperature, the polymerization initiator, the chain
transfer agent, the polymer terminator, the final degree of
polymerization, the monomer removal, the concentration conditions,
etc.
[0036] When the initial adhesive power is emphasized, it is
preferred to adjust the gel content (toluene-insoluble matter) of
the (co)polymer in the polychloroprene latex composition to from 3
to 30 mass %, and when the heat resistant adhesive force is
emphasized, it is preferred to adjust the gel content to from 30 to
70 mass %.
[0037] In a case where an unsaturated carboxylic acid is used as
the monomer copolymerized with chloroprene for the polychloroprene
latex composition of the present invention, the latex immediately
after the polymerization is acidic, but it can be adjusted by e.g.
a pH adjustor. pH is adjusted to preferably from 6 to 9,
particularly preferably from 6.5 to 8.0, in view of stability of
the latex.
[0038] The pH adjustor may, for example, be an inorganic salt such
as sodium carbonate, potassium carbonate, trisodium phosphate,
disodium hydrogen phosphate, tripotassium phosphate, dipotassium
hydrogen phosphate, tripotassium citrate, dipotassium hydrogen
citrate, trisodium citrate, disodium hydrogen citrate, sodium
acetate, potassium acetate or sodium tetraborate, or a basic
substance such as sodium hydroxide, potassium hydroxide or
diethanolamine.
[0039] The method of adding the pH adjustor is not particularly
limited, and the pH adjustor may be added directly or as diluted
with water to an optional proportion.
[0040] In a case where the polychloroprene latex composition of the
present invention is used as an aqueous adhesive, it is preferred
to add an adhesion-imparting resin so that characteristics such as
initial adhesive force, water resistant adhesive force and
adhesion-holding time are more practically balanced.
[0041] In a case where an adhesion-imparting resin is blended in
the aqueous adhesive, the type is not particularly limited. It may,
for example, be a rosin resin, a rosinate resin, a polymerized
rosin resin, an .alpha.-pinene resin, a .beta.-pinene resin, a
terpene phenol resin, a C5 petroleum resin, a C9 petroleum resin, a
C5/C9 petroleum resin, a dicyclopentadiene petroleum resin, an
alkylphenol resin, a xylene resin, a coumarone resin or a
coumarone-indene resin. In order to obtain sufficient initial
adhesive force, preferred is a resin having a softening temperature
of from 50 to 160.degree. C. Among such resins, an emulsion of a
terpene phenol resin or a rosinate resin is particularly preferred
in view of initial strength and water resistance.
[0042] The method of adding the adhesion-imparting resin is not
particularly limited, but it is preferably added in the form of an
aqueous emulsion so that the resin is uniformly dispersed in a
primer.
[0043] Further, as a method of preparing the aqueous emulsion of
the adhesion-imparting resin, a method wherein a solution of the
adhesion-imparting resin in an organic solvent such as toluene is
emulsified/dispersed in water employing an emulsifier, and then the
organic solvent is removed by heating while the pressure is
reduced, a method wherein the resin is ground into fine particles
and then emulsified/dispersed, and the like may be mentioned, and
preferred is a method capable of preparing an emulsion comprising
finer particles.
[0044] The amount (as calculated as solid content) of the
adhesion-imparting resin is preferably from 10 to 100 parts by
mass, more preferably from 20 to 70 parts by mass, per 100 parts by
mass of the solid content of the polychloroprene latex composition.
If it is less than 10 parts by mass, adhesive characteristics such
as initial adhesive force may not sufficiently be improved, and if
it exceeds 100 parts by mass, it is highly possible that the
adhesive characteristics such as heat resistant strength are
insufficient.
[0045] To the polychloroprene latex composition of the present
invention, in addition to the above components, a thickener, a
metal oxide, a filler, a film-forming aid, an ultraviolet absorber,
an antioxidant, a plasticizer, a vulcanizer, a vulcanization
accelerator, an antifoaming agent or the like may optionally be
added depending upon the performance required.
[0046] Further, it may also be used as a two-pack adhesive in
combination with a curing agent comprising a polyisocyanate
compound or the like.
[0047] The metal oxide to be added for imparting stability to or
for improving adhesive properties of the latex composition of the
present invention, may, for example, be zinc oxide, titanium oxide
or ferric oxide, but it is not limited thereto. Use of zinc oxide
or titanium oxide is preferred in view of adhesive properties, and
use of zinc oxide is particularly preferred. Particularly in a case
of a latex having an unsaturated carboxylic acid copolymerized, use
of zinc oxide is recommended, which improves heat resistant
strength.
[0048] The amount of the metal oxide is preferably from 0.2 to 6
parts by mass, more preferably from 0.5 to 5 parts by mass, per 100
parts by mass of the solid content of the polychloroprene latex
composition. If it is less than 0.2 part by mass, the effect of
improving the adhesive characteristics may be insufficient in some
cases, and if it exceeds 6 parts by mass, stickness may be
impaired.
[0049] The application of the adhesive comprising the latex
composition of the present invention is not particularly limited,
and the adhesive is suitably used for adhesion of various materials
such as cement, mortar, slate, cloth, wood, a synthetic rubber
material, a polyurethane material, a polyvinyl chloride material
and a polyolefin material.
[0050] Now, the effects of the present invention will be explained
in detail with reference to Examples and Comparative Examples.
However, the present invention is by no means restricted to such
specific Examples. In the following description, "part(s)" and "%"
are based on mass unless otherwise specified.
Example 1
[0051] Using a reactor having an internal volume of 3 liter, 0.6
part of a polyvinyl alcohol (PVA 203: manufactured by KURARAY CO.,
LTD.) and 3.0 parts of a polyoxyethylene alkyl ether (EMULGEN
1118S-70, manufactured by Kao Corporation, HLB value: 16.4) as a
nonionic emulsifier were dissolved in 95 parts of water in nitrogen
atmosphere at 60.degree. C. This polyvinyl alcohol/nonionic
emulsifier aqueous solution was cooled to about room temperature,
and 97 parts of a chloroprene monomer, 3 parts of methacrylic acid
and 0.3 part of octyl mercaptan were added. While the aqueous
solution was kept at 45.degree. C., polymerization was carried out
employing sodium sulfite and potassium persulfate as initiators.
The system was left to stand further for 1 hour after termination
of generation of the polymerization heat, and that point was
regarded as the end point of the polymerization. A 20%
diethanolamine aqueous solution was added to the obtained
polychloroprene latex composition to adjust pH to 7, and the latex
composition was concentrated by heating under reduced pressure to
prepare samples having solid contents of 50% and 60%.
Measurement of Latex Viscosity
[0052] The latexes obtained in Example 1 were adjusted at
25.degree. C., and their viscosity was measured by a Brookfiled
viscometer at 30 rpm. The results are shown in Table 1.
Measurement of Agglomerates
[0053] The total amount of the polychloroprene latex composition
having a solid content of 60% obtained in Example 1 was filtrated
through a stainless steel wire mesh with an opening of 177 .mu.m.
The residue product was sufficiently washed with distilled water
and dried at 110.degree. C., and its mass was measured. The mass of
the residue product was divided by the mass of the total amount of
the polychloroprene latex composition as shown in the formula (2)
to determine the agglomerate content. The result is shown in Table
1.
Agglomerate content (%)={Mass (g) of the residue product}/{Mass (g)
of the entire polychloroprene latex composition}.times.100 (2)
Mechanical Stability Test
[0054] The latex having a solid content of 60% obtained in Example
1 is adjusted at 20.degree. C. and filtrated through a stainless
steel wire mesh with an opening of 177 .mu.m to collect resulting
agglomerates. The agglomerates are washed with distilled water,
dried at 110.degree. C. and weighed. The mass is divided by the
mass of the total solid content in the polychloroprene latex
composition as shown in the formula (3) to determine mechanical
stability. The result is shown in Table 1.
Mechanical stability (%)={Mass (g) of the agglomerates}/{Mass (g)
of the total solid content in the polychloroprene latex
composition}.times.100 (3)
Preparation of Adhesive Composition
[0055] 100 Parts of the polychloroprene latex composition obtained
in Example 1, 30 parts of an adhesion-imparting resin emulsion
(Tamanol E-100, manufactured by ARAKAWA CHEMICAL INDUSTRIES, LTD.)
and 1 part of a zinc oxide dispersion (AZ-SW, manufactured by OSAKI
INDUSTRIES CO., LTD.), each as calculated as solid content, were
mixed and stirred by a three one motor to prepare an adhesive
composition.
Spray Test
[0056] An adhesive composition prepared by employing the sample
having a solid content of 50% was tested for spray coating. The
evaluation of the spray coating was carried out based on the amount
of the adhesive coated, uniformity in coating of the adhesive, etc.
The result is shown in Table 1. In Table, "favorable" means that
the adhesive could be coated uniformly in a sufficient coating
amount, and "poor" means that the coating amount was insufficient
or uniform coating could not be carried out.
Bonding of Canvas
[0057] The above obtained sample was tested for adhesion by brush
coating.
[0058] The adhesive composition prepared by employing the sample
having a solid content of 60% was coated by a brush on each of two
pieces of canvas (25.times.150 mm) in an amount of 300 g (solid
content)/m.sup.2, dried in an atmosphere of 80.degree. C. for 9
minutes and then left to stand at room temperature for 1 minute,
and the coated faces were bonded to each other and clamped by a
hand roller.
Initial Peel Strength
[0059] The bonded canvas was left to stand for 10 minutes, and then
180.degree. peel strength was measured at a tensile rate of 200
mm/min by using a tensile tester.
Normal State Peel Strength
[0060] The bonded canvas was left to stand for 7 days, and then
180.degree. peel strength was measured at a tensile rate of 200
mm/min by using a tensile tester.
Water Resistant Strength
[0061] The bonded canvas was left to stand for 7 days and immersed
in water for 2 days. Immediately after moisture on the surface of
the canvas taken out was wiped off, 180.degree. peel strength was
measured at a tensile rate of 200 mm/min by using a tensile tester.
The following other Examples and Comparative Examples were carried
out in the same manner as in the present Example unless otherwise
specified.
Examples 2 and 3
[0062] In the same manner as in Example 1 except that the ratio of
the polyvinyl alcohol/the nonionic emulsifier was changed to
1.2/2.4 (Example 2) or 1.8/1.8 (Example 3), latex samples were
prepared, which were tested and evaluated.
Example 4
[0063] In the same manner as in Example 1 except that the nonionic
emulsifier was changed to a polyoxyethylene alkyl ether (EMULGEN
1135S-70, manufactured by Kao Corporation, HLB value: 17.9), latex
samples were prepared, which were tested and evaluated.
Example 5
[0064] In the same manner as in Example 1 except that the nonionic
emulsifier was changed to a polyoxyethylene alkyl ether (EMULGEN
1108, manufactured by Kao Corporation, HLB value: 13.5), latex
samples were prepared, which were tested and evaluated.
Examples 6 and 7
[0065] In the same manner as in Examples 1 except that the nonionic
emulsifier was changed to a polyoxyethylene distyrenated phenyl
ether (EMULGEN A-90, manufactured by Kao Corporation, HLB value:
14.5), and that the proportions were as shown in Table 1, latex
samples were prepared, which were tested and evaluated.
Examples 8 and 9
[0066] In the same manner as in Example 1 except that the nonionic
emulsifier was changed to an addition product of
2,4,7,9-tetramethyl-5-decyn-4,7-diol and ethylene oxide (SURFYNOL
485, manufactured by Nissin Chemical Industry Co., Ltd., HLB value:
17, ethylene oxide addition mass ratio: 85%), and that the
proportions were as shown in Table 1, latex samples were prepared,
which were tested and evaluated.
Comparative Example 1
[0067] The same experiment as in Example 1 was carried out except
that 3.6 parts of the polyvinyl alcohol alone was used instead of
0.6 part of the polyvinyl alcohol and 3.0 parts of the nonionic
emulsifier. The results are shown in Table 1. However, since no
sample having a solid content of 60% could be obtained, the brush
coating test, the initial peel strength test, the normal state peel
strength test and the water resistant strength test were carried
out employing a sample having a solid content of 50%.
Comparative Example 2
[0068] The same experiment as in Example 1 was carried out except
that 3.6 parts of the nonionic emulsifier (EMULGEN 1118S-70) alone
was used instead of 0.6 part of the polyvinyl alcohol and 3.0 parts
of the nonionic emulsifier. However, no polymerization reaction
took place even if the amount of the polymerization initiator was
increased, and no polychloroprene latex composition could be
obtained.
[0069] The results obtained in Examples and Comparative Examples
are summarized in Table 1. As evident from Table 1, the spray
coating was possible and the coating method was not limited in
Examples, whereas in Comparative examples, the composition had a
too high viscosity, and the spray coating was difficult.
[0070] Further, with respect to the adhesive characteristics also,
in Examples, strength equal to or higher than that of Comparative
Examples was obtained even though the composition had a low
viscosity, and the water resistance was rather excellent.
TABLE-US-00001 TABLE 1 Comparative Examples Examples 1 2 3 4 5 6 7
8 9 1 2 Emulsifier/ PVA203 0.6 1.2 1.8 0.6 0.6 0.6 1.8 1.8 3.0 3.6
dispersant EMULGEN 1118S-70 3.0 2.4 1.8 3.6 EMULGEN 1135S-70 3.0
EMULGEN 1108 3.0 EMULGEN A-90 3.0 1.8 SURFYNOL 485 1.8 0.6
Evaluation Solid content 50% 20 50 120 30 20 30 200 100 300 1000
Poly- Viscosity merization (30 rpm) (mPa s) impossible Solid
content 60% 200 550 1300 280 170 320 1700 1100 2700 Con- Viscosity
centration (30 rpm) (mPa s) impossible Agglomerates (%) <0.01
<0.01 <0.01 <0.01 0.08 0.22 0.02 <0.01 <0.01
Mechanical stability (%) <0.01 <0.01 <0.01 <0.01 0.85
1.20 0.03 <0.01 <0.01 Spray test F F F F F F F F F P Initial
peel 2.5 2.4 2.5 2.5 2.4 2.5 2.5 2.4 2.6 2.4 strength (N/mm) Normal
state peel 5.1 4.9 5.2 5.1 5.0 4.9 5.0 5.0 4.9 5.0 strength (N/mm)
Water resistant 1.65 1.15 0.32 1.55 1.40 1.45 0.29 0.30 0.28 0.06
strength (N/mm) F: Favorable, P: Poor
INDUSTRIAL APPLICABILITY
[0071] The polychloroprene latex composition obtained by the
present invention is very suitable as a material for an aqueous
adhesion.
[0072] The entire disclosures of Japanese Patent Application No.
2003-136182 (filed on May 14, 2003), Japanese Patent Application
No. 2003-144332 (filed on May 22, 2003), Japanese Patent
Application No. 2004-109691 (filed on Apr. 2, 2004) and Japanese
Patent Application No. 2004-121135 (filed on Apr. 16, 2004)
including specifications, claims, drawings and summaries are
incorporated herein by reference in their entireties.
* * * * *