U.S. patent application number 10/006567 was filed with the patent office on 2002-07-04 for curable resin composition.
This patent application is currently assigned to KANEKA CORPORATION. Invention is credited to Iwakiri, Hiroshi, Kotani, Jun, Kusakabe, Masato.
Application Number | 20020084030 10/006567 |
Document ID | / |
Family ID | 26481970 |
Filed Date | 2002-07-04 |
United States Patent
Application |
20020084030 |
Kind Code |
A1 |
Kotani, Jun ; et
al. |
July 4, 2002 |
Curable resin composition
Abstract
This invention has its object to provide a curable resin
compositions useful as contact adhesives with a prolonged tack
retention period, without affecting the final bond strength. This
invention is related to a A curable resin composition which
comprises (I) a reactive silicon group-containing polyether
oligomer, (II) a copolymer comprising a molecular chain
substantially composed of one or more acrylate ester monomer units
and/or methacrylate ester monomer units and (III) an
accelerator.
Inventors: |
Kotani, Jun; (Hyogo, JP)
; Kusakabe, Masato; (Hyogo, JP) ; Iwakiri,
Hiroshi; (Hyogo, JP) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 Pennsylvania Avenue, NW
Washington
DC
20037-3213
US
|
Assignee: |
KANEKA CORPORATION
|
Family ID: |
26481970 |
Appl. No.: |
10/006567 |
Filed: |
December 10, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10006567 |
Dec 10, 2001 |
|
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|
09584075 |
Jun 1, 2000 |
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Current U.S.
Class: |
156/329 ;
525/100 |
Current CPC
Class: |
C08L 43/04 20130101;
C08L 2666/14 20130101; Y10S 528/901 20130101; C08L 71/02 20130101;
C09J 143/04 20130101; C09J 143/04 20130101; C08L 43/04 20130101;
C08L 2666/14 20130101; C08L 2666/14 20130101; C08L 33/06 20130101;
C08L 2666/14 20130101; C08L 33/06 20130101 |
Class at
Publication: |
156/329 ;
525/100 |
International
Class: |
C08F 008/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 1, 1999 |
JP |
HEI. 11-153320 |
Feb 8, 2000 |
JP |
2000-030370 |
Claims
1. A curable resin composition which comprises (I) a reactive
silicon group-containing polyether oligomer, (II) a copolymer
comprising a molecular chain substantially composed of one or more
acrylate ester monomer units and/or methacrylate ester monomer
units and (III) an accelerator, said reactive silicon
group-containing polyether oligomer having, within the molecule
thereof, a partial structure represented by the general formula
(1):--O--R.sup.1--CH(R.sup.2)--CH.sub.2--(Si(R.sup.3.-
sub.2-b)(X.sub.b)O).sub.mSi(R.sup.4.sub.3-a)X.sub.a (1)wherein
R.sup.1 represents a divalent organic group of 1 to 20 carbon atoms
containing at least one constituent element selected from the group
consisting of hydrogen, oxygen and nitrogen, R.sup.2 represents an
alkyl group of 1 to 10 carbon atoms, R.sup.3 and R.sup.4 may be the
same or different and each represents an alkyl group of 1 to 20
carbon atoms, an aryl group of 6 to 20 carbon atoms or an aralkyl
group of 7 to 20 carbon atoms or a triorganosiloxy group of the
formula (R').sub.3SiO--, in which R' is a monovalent hydrocarbon
group of 1 to 20 carbon atoms and the three R' groups may be the
same or different, and where there are two or more R.sup.3 or
R.sup.4 groups, they may be the same or different; X represents a
hydroxyl group or a hydrolyzable group and, where there are two or
more X groups, they may be the same or different; a represents 0,
1, 2 or 3, b represents 0, 1 or 2, m represents an integer of 0 to
19, and the b's in the m --(Si(R.sup.3.sub.2-b)(X.sub.b)--O)--
groups may be the same or different, provided that the condition
a+.SIGMA.b.gtoreq.1 is satisfied.
2. The curable resin composition according to claim 1, wherein
R.sup.1 in component (I) is CH.sub.2.
3. The curable resin composition according to claim 1 or 2, wherein
R.sup.2 in component (I) is CH.sub.3.
4. The curable resin composition according to any of claims 1 to 3,
wherein component (I) is a reactive silicon group-containing
polyether oligomer having a partial structure represented by the
formula:--O--CH.sub.2-CH(CH.sub.3)--CH.sub.2--Si(CH.sub.3)(OCH.sub.3).sub-
.2
5. The curable resin composition according to claim 1, wherein
component (I) is a reactive silicon group-containing polyether
oligomer obtainable by reacting a polyether oligomer having an
unsaturated bond introduced therein of the general formula
(2):--O--R.sup.1--C(CH.sub.3)=CH.sub.2 (2)wherein R.sup.1 is as
defined above, with a reactive silicon group-containing compound
represented by the general formula
(3):H--(Si(R.sup.3.sub.2-b)(X.sub.b)O).sub.mSi(R.sup.4.sub.3-a)X.sub.a
(3)wherein R.sup.3, R.sup.4, a, b, m and X are as defined above, in
an oxygen-containing atmosphere in the presence of a catalyst and a
sulfur compound.
6. The curable resin composition according to claim 5, wherein
component (I) is a reactive silicon group-containing polyether
oligomer having a partial structure represented by the
formula:--O--CH.sub.2--CH(CH.sub.3)--
-CH.sub.2--Si(CH.sub.3)(OCH.sub.3).sub.2as obtainable by reacting a
polyether oligomer having an unsaturated bond introduced therein of
the formula:--O--CH.sub.2--C(CH.sub.3)=CH.sub.2 with a reactive
silicon group-containing compound of the
formula:H--Si(CH.sub.3)(OCH.sub.3).sub.2- in an oxygen-containing
atmosphere in the presence of a catalyst and a sulfur compound.
7. The curable resin composition according to any of claims 1 to 6,
wherein component (II) is a copolymer comprising a molecular chain
substantially composed of (a) acrylic and/or methacrylic ester
monomer units having a hydrocarbon group of 1 to 8 carbon atoms,
and (b) acrylic and/or methacrylic ester monomer units having a
hydrocarbon group of 10 or more carbon atoms.
8. The curable resin composition according to any of claims 1 to 7,
wherein component (II) is a copolymer having a silicon group
crosslinkable under siloxane bond formation.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a curable resin composition
useful as a contact adhesive. The term "contact adhesives" as used
herein means an adhesive capable of adhesion under pressure after
standing for a certain period of time following application thereof
to an adherend.
PRIOR ART
[0002] The so-called solvent type adhesives comprising a natural
rubber or a diene compound polymer such as synthetic rubber,
together with additives, such as a tackifier resin, a plasticizer
and an antioxidant, as homogeneously dissolved in an organic
solvent (the solid concentration being 20 to 35%) have so far been
widely used as contact adhesives. Since, however, a large amount of
an organic solvent is used in such solvent type adhesives, not only
the cost of the solvent arises but also the organic solvent must be
evaporated and removed, which raises problems from the viewpoint of
working environment, protection against disasters and pollution.
For solving such problems and providing adhesives comparable in
performance to the conventional solvent type adhesives,
solvent-free contact adhesives have been proposed in which a
modified silicone polymer is used, as disclosed in Japanese Kokai
Publication Hei-03-263478 and Japanese Kokai Publication
Hei-07-258535.
[0003] However, the contact adhesive in which the modified silicone
polymer disclosed in Japanese Kokai Publication Hei-03-263478 is
used has problems in that it takes a fairly long time for a
sufficient extent of tack to enable lamination to develop and that
it is poor in workability because of its high viscosity. Japanese
Kokai Publication Hei-07-258535 discloses a curable composition
comprising a reactive silicon group-containing oxyalkylene polymer,
an acrylic copolymer and a curing catalyst. However, it does not
disclose the introduction of a hydrocarbon group into such a
reactive silicon group-containing oxyalkylene polymer at a position
close to the reactive silicon group. In Japanese Kokai Publication
Hei-07-258535, it is proposed that a contact adhesive capable of
developing tack in a short time, allowing laminating over a long
period and showing good workability be prepared by the method
disclosed therein. However, the period during which tack is
retained is not longer than an hour, hence cannot be said to be
sufficient for workers to effect lamination. The measures so far
taken for prolonging the tack retention period comprise adjusting
the cure rate by changing the catalyst species, increasing or
decreasing the catalyst amount, and/or changing the terminal
reactive silicon group content, among others. However, the prior
art measures have a problem in that when the tack retention period
is prolonged by adjusting the cure rate, the final bond strength
decreases accordingly. Thus, it is an object of the present
invention to provide a curable resin composition with a prolonged
tack retention period without affecting the final bond
strength.
SUMMARY OF THE INVENTION
[0004] The present inventors made intensive investigations in an
attempt to solve the problems mentioned above and, as a result,
found that when an alkyl group is introduced into a reactive
silicon group-containing polyether oligomer at a position close to
the reactive silicon group, the reactivity of the reactive silicon
group is indirectly reduced and the tack retention period is
prolonged without affecting the final bond strength. Based on this
finding, the present invention has now been completed.
[0005] Thus, in a first aspect thereof, the present invention
relates to a curable resin composition
[0006] which comprises (I) a reactive silicon group-containing
polyether oligomer, (II) a copolymer comprising a molecular chain
substantially composed of one or more acrylate ester monomer units
and/or methacrylate ester monomer units, and (III) an
accelerator,
[0007] said reactive silicon group-containing polyether oligomer
having, within the molecule thereof, a partial structure
represented by the general formula (1):
--O--R.sup.1--CH(R.sup.2)--CH.sub.2--(Si(R.sup.3.sub.2-b)(X.sub.b)O).sub.m-
Si(R.sup.4.sub.3-a)X.sub.a (1)
[0008] wherein R.sup.1 represents a divalent organic group of 1 to
20 carbon atoms containing at least one constituent element
selected from the group consisting of hydrogen, oxygen and
nitrogen, R.sup.2 represents an alkyl group of 1 to 10 carbon
atoms, R.sup.3 and R.sup.4 may be the same or different and each
represents an alkyl group of 1 to 20 carbon atoms, an aryl group of
6 to 20 carbon atoms or an aralkyl group of 7 to 20 carbon atoms or
a triorganosiloxy group of the formula (R').sub.3SiO--, in which R'
is a monovalent hydrocarbon group of 1 to 20 carbon atoms and the
three R' groups may be the same or different and, where there are
two or more R.sup.3 or R.sup.4 groups, they may be the same or
different; X represents a hydroxyl group or a hydrolyzable group
and, where there are two or more X groups, they may be the same or
different; a represents 0, 1, 2 or 3, b represents 0, 1 or 2, m
represents an integer of 0 to 19, and the b's in the m
--(Si(R.sup.3.sub.2-b)(X.sub.b)--O)--groups maybe the same or
different, provided that the condition a+.SIGMA.b.gtoreq.1 is
satisfied.
[0009] In a preferred embodiment, this invention is related to the
above curable resin composition wherein R.sup.1 in component (I) is
CH.sub.2 .
[0010] In a further preferred embodiment, this invention is related
to the above curable resin composition wherein R.sup.2 in component
(I) is CH.sub.3.
[0011] In a further preferred embodiment, this invention is related
to the above curable resin composition wherein component (I) is a
reactive silicon group-containing polyether oligomer having a
partial structure represented by the formula:
--O--CH.sub.2--CH(CH.sub.3)--CH.sub.2--Si(CH.sub.3)(OCH.sub.3).sub.2.
[0012] In another preferred embodiment, this invention is related
to the above curable resin composition
[0013] wherein component (I) is a reactive silicon group-containing
polyether oligomer obtainable by reacting a polyether oligomer
having an unsaturated bond introduced therein of the general
formula (2):
--O--R.sup.1--C(CH.sub.3).dbd.CH.sub.2 (2)
[0014] wherein R.sup.1 is as defined above, with a reactive silicon
group-containing compound represented by the general formula
(3):
H--(Si (R.sup.3.sub.2-b)(X.sub.b)O).sub.mSi(R.sup.4.sub.3-a)X.sub.a
(3)
[0015] wherein R.sup.3, R.sup.4, a, b, m and X are as defined
above, in an oxygen-containing atmosphere in the presence of a
catalyst and a sulfur compound.
[0016] In a further preferred embodiment, this invention is related
to the above curable resin composition
[0017] wherein component (I) is a reactive silicon group-containing
polyether oligomer having a partial structure represented by the
formula:
--O--CH.sub.2--CH(CH.sub.3)--CH.sub.2--Si(CH.sub.3)(OCH.sub.3).sub.2
[0018] as obtainable by reacting a polyether oligomer having an
unsaturated bond introduced therein of the formula:
--O--CH.sub.2--C(CH.sub.3).dbd.CH.sub.2
[0019] with a reactive silicon group-containing compound of the
formula:
H--Si(CH.sub.3)(OCH.sub.3).sub.2
[0020] in an oxygen-containing atmosphere in the presence of a
catalyst and a sulfur compound.
[0021] In another preferred embodiment, this invention is related
to the above curable resin composition
[0022] wherein component (II) is a copolymer comprising a molecular
chain substantially composed of (a) acrylic and/or methacrylic
ester monomer units having a hydrocarbon group of 1 to 8 carbon
atoms and (b) acrylic and/or methacrylic ester monomer units having
a hydrocarbon group of 10 or more carbon atoms.
[0023] In a further preferred embodiment, this invention is related
to the above curable resin composition wherein component (II) is a
copolymer having a silicon group crosslinkable under siloxane bond
formation.
DETAILED DESCRIPTION OF THE INVENTION
[0024] In the following, the present invention is described in
detail. The reactive silicon group-containing polyether oligomer to
be used as component (I) according to the present invention may be
any polyether-based oligomer comprising a polyether as its main
chain and, on a side chain or at a terminal, at least one structure
represented by the general formula (1):
--O--R.sup.1--CH(R.sup.2)--CH.sub.2--(Si(R.sup.3.sub.2-b)(X.sub.b)O).sub.m-
Si(R.sup.4.sub.3-a)X.sub.a (1)
[0025] wherein R.sup.1 represents a divalent organic group of 1 to
20 carbon atoms containing at least one constituent element
selected from the group consisting of hydrogen, oxygen and
nitrogen, R.sup.2 represents an alkyl group of 1 to 10 carbon
atoms, R.sup.3 or R.sup.4 may be the same or different and each
represents an alkyl group of 1 to 20 carbon atoms, an aryl group of
6 to 20 carbon atoms or an aralkyl group of 7 to 20 carbon atoms or
a triorganosiloxy group of the formula (R').sub.3SiO--, in which R'
is a monovalent hydrocarbon group of 1 to 20 carbon atoms and the
three R' groups may be the same or different, and where there are
two or more R.sup.3 or R.sup.4 groups, they may be the same or
different; X represents a hydroxyl group or a hydrolyzable group
and, where there are two or more X groups, they may be the same or
different; a represents 0, 1, 2 or 3, b represents 0, 1 or 2, and
the b's in the m--(Si(R.sup.3.sub.2-b)(X.sub.b)--O)--groups may be
the same or different, provided that the condition
a+.SIGMA.b.gtoreq.1 is satisfied.
[0026] R.sup.1, which is a divalent organic group of 1 to 20 carbon
atoms containing at least one constituent element selected from the
group consisting of hydrogen, oxygen and nitrogen, includes, among
others, --CH.sub.2--, --C.sub.2H.sub.4--, --C.sub.3H.sub.6--,
--C.sub.4H.sub.8--, --C.sub.5H.sub.10--, --C.sub.6H.sub.4--,
--C.sub.6H.sub.12--, --C.sub.7H.sub.14--, --C.sub.8H.sub.16--,
--C.sub.9H.sub.18--, --C.sub.10H.sub.20--, --CH(CH.sub.3)--,
--CH.sub.2--CH(CH.sub.3)--, --CH.sub.2--CH(CH.sub.3)--CH.sub.2--,
--C.sub.2H.sub.4--CH(CH.sub.3)--, --CH.sub.2--C.sub.6H.sub.4--,
--CH.sub.2--C.sub.6H.sub.4--CH.sub.2--,
--C.sub.2H.sub.4--C.sub.6H.sub.4--, --C(O)--, --C(O)--CH.sub.2--,
--C (O)--C.sub.6H.sub.4--, --C (O)--NH--, --C(O)--NH--CH.sub.2--,
--C(O)--NH--C.sub.6H.sub.4--, --C(O)--O--, --C(O)--O--CH.sub.2--,
--C(O)--O--C.sub.6H.sub.4-- and like groups. Among these,
--CH.sub.2--, --C.sub.2H.sub.4--, --CH.sub.2--CH(CH.sub.3)--,
--C(O)-- and --C(O)--NH-- are preferred because of ease of
synthesis and --CH.sub.2-- is most preferred because of ready raw
material availability.
[0027] As specific examples of R.sup.2, there may be mentioned,
among others, alkyl groups such as methyl, ethyl and propyl, and
cycloalkyl groups such as cyclohexyl. Among them, methyl is
particularly preferred.
[0028] As specific examples of R.sup.3 and R.sup.4, there may be
mentioned alkyl groups such as methyl and ethyl, cycloalkyl groups
such as cyclohexyl, aryl groups such as phenyl, aralkyl groups such
as benzyl, and triorganosiloxy groups of the formula
(R').sub.3SiO-- in which R' is methyl or phenyl, for instance.
Methyl is most preferred as R.sup.3, R.sup.4 or R'.
[0029] Among the groups represented by X, the hydrolyzable group is
not particularly restricted but may be any of the so far known
hydrolyzable groups. Specifically, there may be mentioned, among
others, a hydrogen or halogen atom, and an alkoxy, acyloxy,
ketoximate, amino, amido, acid amido, amino-oxy, mercapto or
alkenyloxy group. Among these, alkoxy groups such as methoxy,
ethoxy, propoxy and isopropoxy are preferred because of their mild
hydrolyzability and ease of handling thereof.
[0030] One to three hydroxyl and/or hydrolyzable groups may be
bound to one silicon atom and the sum (a+.SIGMA.b) is preferably
equal to 1 to 5. When a reactive silicon group has two or more
hydroxyl and/or hydrolyzable groups, the two or more groups may be
the same or different.
[0031] The number of silicon atoms in each reactive silicon group
may be 1 or 2 or more and, in the case of a reactive silicon group
including silicon atoms bound together via siloxane bonding, for
instance, the number of silicon atoms may be up to about 20.
[0032] A reactive silicon group represented by the following
general formula (5):
--Si(R.sup.4.sub.3-a)X.sub.a (5)
[0033] wherein R.sup.4, X and a are as defined above, is preferred
because of its ready availability.
[0034] It is more preferred that R.sup.4 be methyl, X be methoxy
and a be 2 or 3.
[0035] Ten molecular chain terminals of the polyether oligomer
preferably have, on an average, at least one, more preferably 0. 5
to 5 from the viewpoint of curability, still more preferably 0.8 to
2 reactive silicon groups. It is particularly preferred that the
number of reactive silicon groups per terminal be 0.9 to 1, since,
then, cured products showing good rubber elasticity behavior can be
obtained.
[0036] The average number of reactive silicon groups per polymer
molecule maybe one or more. For securing sufficient curability,
however, said average number is preferably 1.5 to 4.
[0037] The reactive silicon group-containing polyether oligomer,
namely component (I), may comprise one single species or a
combination of two or more different species.
[0038] Specifically, it is preferred that component (I) be a
reactive silicon group-containing polyether oligomer having a
partial structure represented by the formula:
--O--CH.sub.2--CH(CH.sub.3)--CH.sub.2--Si(CH.sub.3)(OCH.sub.3).sub.2.
[0039] Although the molecular weight of the reactive silicon
group-containing polyether oligomer, namely component (I), is not
restricted, a number average molecular weight of 1,000 to 100,000
is preferred. When the number average molecular weight is less than
1,000, the reactive silicon group-containing polyether oligomer
will give brittle cured products. When said molecular weight
exceeds 100,000, the functional group concentration becomes too
low, which results in a decreased rate of curing, and at the same
time, the viscosity of the polymer becomes excessively high, which
renders handling of the polymer difficult. For attaining desirable
mechanical properties, a number average molecular weight of 10,000
to 50,000 is especially preferred.
[0040] The "number average molecular weight of the polyether
oligomer" is herein defined as the number average molecular weight
determined by directly determining the terminal group
concentrations through hydroxyl value determination according to
JIS K 1557 and titrimetric analysis based on the principle of
iodine value determination as described in JIS K 0070 and making a
calculation with the structure of the polyether oligomer taken into
consideration. It is also possible, by constructing a working curve
for the relation between the polystyrene-equivalent molecular
weight determined by GPC, which is a generalized method for
relative number average molecular weight determination, and the
above terminal group-based molecular weight, to determine the
number average molecular weight in question by converting the
molecular weight obtained by GPC to the corresponding terminal
group-based molecular weight.
[0041] The main chain structure of the component (I) polyether
oligomer has, as a repeating unit, a structure represented by
--R--O-- (in which R is a divalent organic group of 1 to 20 carbon
atoms containing at least one constituent atom selected from the
group consisting of hydrogen, oxygen and nitrogen atoms). Said
oligomer may be a homopolymer in which all repeating units are the
same or a copolymer including two or more repeating unit species.
The main chain may have a branched structure.
[0042] As specific examples of R, there maybe mentioned
--CH.sub.2CH.sub.2--, --CH(CH.sub.3)CH.sub.2--,
--CH(C.sub.2H.sub.5)CH.su- b.2--, --C(CH.sub.3).sub.2CH.sub.2--,
--CH.sub.2CH.sub.2CH.sub.2CH.sub.2-- and the like, among which
--CH(CH.sub.3)CH.sub.2-- is particularly preferred.
[0043] For obtaining component (I) to be used according to the
present invention, a polyether obtained by subjecting a substituted
or unsubstituted epoxy compound containing 2 to 12 carbon atoms,
for example an alkylene oxide, specifically ethylene oxide,
propylene oxide, .alpha.-butylene oxide, .beta.-butylene oxide,
hexene oxide, cyclohexene oxide, styrene oxide,
.alpha.-methylstyrene oxide, or an alkyl, allyl or aryl glycidyl
ether, specifically methyl glycidyl ether, ethyl glycidyl ether,
isopropyl glycidyl ether, butyl glycidyl ether, allyl glycidyl
ether or phenyl glycidyl ether, to ring opening polymerization in
the presence of a dihydric or polyhydric alcohol or a
hydroxyl-containing oligomer, such as ethylene glycol, propylene
glycol, butanediol, hexamethylene glycol, methallyl alcohol,
hydrogenated bisphenol A, neopentyl glycol, polybutadiene diol,
diethylene glycol, triethylene glycol, polyethylene glycol,
polypropylene glycol, polypropylene triol, polypropylene tetraol,
dipropylene glycol, glycerol, trimethylolmethane,
trimethylolpropane or pentaerythritol, as an initiator and in the
presence of a catalyst can be used. Usable as the catalyst for this
polymerization are alkali catalysts such as KOH and NaOH, acidic
catalysts such as trifluoroborane etherate, aluminoporphyrin-metal
complex catalysts, cobalt zinc cyanide-glyme complex catalysts,
like double metal cyanide complex catalysts and other catalysts
already known for such polymerization. While the use of a double
metal cyanide complex catalyst is preferred because of causing
little side reactions, any other catalysts may also be
employed.
[0044] Further, the main chain skeleton of the polyether oligomer
can also be obtained by chain extension of a hydroxyl-terminated
polyether oligomer with a bifunctional or multifunctional alkyl
halide, such as CH.sub.2Cl.sub.2 or CH.sub.2Br.sub.2, in the
presence of a basic compound such as KOH, NaOH, KOCH.sub.3 or
NaOCH.sub.3.
[0045] For producing component (I) from such a hydroxyl-containing
polyether oligomer, any of known methods may be employed, for
example the method comprising introducing an unsaturated bond into
a hydroxyl-containing polyether oligomer and then reacting the
product with a reactive silicon group-containing compound.
[0046] The method of introducing an unsaturated bond into a
hydroxyl-containing polyether oligomer may comprise ether bond,
ester bond, urethane bond, carbonate bond or like bond formation.
In the case of unsaturated group introduction through ether bond
formation, for instance, the hydroxyl group of the polyether
oligomer is converted to the metaloxy form --OM (M being Na or K),
followed by reacting with an organohalogen compound represented by
the general formula (6):
H.sub.2C=C(R.sup.2)--R.sup.1--Y (6)
[0047] wherein R.sup.1 is a divalent organic group of 1 to 20
carbon atoms containing at least one constituent atom selected from
the group consisting of hydrogen, oxygen and nitrogen atoms,
R.sup.2is an alkyl group of 1 to 10 carbon atoms and Y is a halogen
atom) to give an unsaturated group-containing polyether. As
specific examples of the unsaturated group-containing compound of
general formula (6), there may be mentioned
H.sub.2C=C(CH.sub.3)--CH.sub.2--Cl, H.sub.2C=C(CH.sub.3)--CH-
.sub.2--Br and the like, among which
H.sub.2C=C(CH.sub.3)--CH.sub.2--Cl is particularly preferred from
the viewpoint of reactivity, raw material availability and ease of
synthesis.
[0048] It is also possible to effect unsaturated group introduction
using an isocyanate compound, carboxylic acid or epoxy compound
having a H.sub.2C=C(CH.sub.3)--CH.sub.2-- or like group.
[0049] The reaction of the unsaturated bond-containing polyether
oligomer with the reactive silicon group-containing compound can be
carried out, for example, in the manner of hydrosilylation in the
presence of a catalyst.
[0050] The reactive silicon group-containing compound to be used in
this hydrosilylation reaction may have, within its molecule, one or
more silicon groups with said hydroxyl and/or hydrolyzable group
being bound thereto, and one or more Si--H groups within its
molecule. Typical examples are represented by the general formula
(3):
H--(Si(R.sup.3.sub.2-b)(X.sub.b)O).sub.mSi(R.sup.4.sub.3-a)X.sub.a
(3)
[0051] wherein R.sup.3, R.sup.4, a, b, m and X are as defined above
referring to general formula (1) given above.
[0052] Specifically, there may be mentioned halogenated silanes
such as trichlorosilane, methyldichlorosilane,
dimethylchlorosilane, phenyldichlorosilane,
trimethylsiloxymethylchlorosilane and
1,1,3,3-tetramethyl-1-bromodisiloxane; alkoxysilanes such as
trimethoxysilane, triethoxysilane, methyldiethoxysilane,
methyldimethoxysilane, phenyldimethoxysilane,
trimethylsiloxymethylmethox- ysilane and
trimethylsiloxydiethoxysilane; acyloxysilanes such as
methyldiacetoxysilane, phenyldiacetoxysilane, triacetoxysilane,
trimethylsiloxymethylacetoxysilane and
trimethylsiloxydiacetoxysilane; ketoximatesilanes such as
bis(dimethylketoximate)methylsilane,
bis(cyclohexylketoximate)methylsilane,
bis(diethylketoximate)trimethylsil- oxysilane,
bis(methylethylketoximate)methylsilane and tris(acetoximate)silane;
alkenyloxysilanes such as methylisopropenyloxysilane; and so forth.
Among these, alkoxysilanes are especially preferred and, among
alkoxy groups, methoxy is particularly preferred.
[0053] Reactive silicon group-containing compounds represented by
the general formula (7):
H--Si (R.sup.4.sub.3-a)X.sub.a (7)
[0054] wherein R.sup.4, X and a are as defined above, are preferred
because of their ready availability.
[0055] As specific examples of R.sup.3 and R.sup.4 in the above
general formulas (3) and (7), there may be mentioned, among others,
alkyl groups such as methyl and ethyl, cycloalkyl groups such as
cyclohexyl, aryl groups such as phenyl, aralkyl groups such as
benzyl, and triorganosiloxy groups of the formulas (R').sub.3SiO--
in which R' is methyl or phenyl, for instance. Methyl is
particularly preferred as R.sup.3, R.sup.4 and/or R'.
[0056] In a preferred embodiment of the above hydrosilylation
reaction, a polyether oligomer, introduced an unsaturated bond
therein and represented by the general formula (2):
--O-R.sup.1--C(CH.sub.3)=CH.sub.2 (2)
[0057] wherein R.sup.1 is as defined above, is reacted with a
reactive silicon group-containing compound represented by the
general formula (3):
H--(Si(R.sup.3.sub.2-b)(X.sub.b)O).sub.mSi(R.sup.4.sub.3-a)X.sub.a
(3)
[0058] wherein R.sup.3, R.sup.4, a, b, m and X are as defined above
referring to general formula (1) given above, in an
oxygen-containing atmosphere in the presence of a catalyst and a
sulfur compound to give a reactive silicon group-containing
polyether oligomer, which is a preferred one. More preferred is a
polyether oligomer having a structure represented by the
formula:
--O--CH.sub.2--CH(CH.sub.3)--CH.sub.2--Si(CH.sub.3)(OCH.sub.3).sub.2
[0059] as obtained by reacting a polyether oligomer, introduced an
unsaturated bond therein and represented by the formula:
--O--CH.sub.2--C(CH.sub.3)=CH.sub.2
[0060] with a reactive silicon group-containing compound of the
formula:
H--Si(CH.sub.3)(OCH.sub.3).sub.2
[0061] in an oxygen-containing atmosphere in the presence of a
catalyst and a sulfur compound.
[0062] Effective as the catalyst for the hydrosilylation reaction
between the polyether oligomer with an unsaturated bond introduced
therein and the reactive silicon group-containing compound are
metal complex catalysts in which the metal is selected from among
group VIII transition metal elements such as platinum, rhodium,
cobalt, palladium and nickel. Usable are, for instance,
H.sub.2PtCl.sub.6.6H.sub.2O, platinum-vinylsiloxane complexes,
platinum-olefin complexes, Pt metal, RhCl(PPh.sub.3).sub.3,
RhCl.sub.3, Rh/Al.sub.2O.sub.3, RuCl.sub.3, IrCl.sub.3, FeCl.sub.3,
PdCl.sub.2.2H.sub.2O, NiCl.sub.2 and like compounds. From the
viewpoint of reactivity in hydrosilylation, either
platinum-vinylsiloxane complexes or platinum-olefin complexes are
especially preferred. The term "platinum-vinylsiloxane complexes"
as used herein collectively refers to those compounds containing a
platinum atom and a siloxane, polysiloxane or cyclic siloxane
having a vinyl group within its molecule as a ligand to the
platinum atom. As specific examples of the ligand, there may be
mentioned 1,1,3,3-tetramethyl-1,3-di- vinyldisiloxane
(platinum-divinylsiloxane complex) and
1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane. As
specific examples of the olefin ligand in the platinum-olefin
complexes, there may be mentioned 1,5-hexadiene, 1,7-octadiene,
1,9-decadiene, 1,11-dodecadiene and 1,5-cyclooctadiene. Among such
ligands, 1,9-decadiene is particularly preferred.
[0063] Such platinum-vinylsiloxane complexes and platinum-olefin
complexes are disclosed in Japanese Kokoku Publication
Hei-08-9006.
[0064] In addition to those mentioned above, AlCl.sub.3, TiCl.sub.4
and the like may also be used as hydrosilylation catalysts.
[0065] Although the amount of the catalyst is not restricted, it is
generally preferred that the platinum catalyst be used in an amount
of 10.sup.-1 to 10.sup.-8 mole, more preferably 10.sup.-3 to
10.sup.-6 mole, per mole of the alkenyl group. When the amount of
the catalyst is below the range mentioned above, the
hydrosilylation reaction may fail to proceed to a sufficient
extent. When the catalyst amount is excessive, problems may arise,
namely the consumption of the catalyst may result in an increase in
production cost and the residual catalyst amount in the product may
increase.
[0066] The hydrosilylation reaction in the practice of the present
invention is carried out generally at a temperature within the
range of 10 to 150.degree. C., preferably 20 to 120.degree. C.,
more preferably 40 to 100.degree. C. The hydrosilylation reaction
can be carried out in the absence or presence of a solvent
according to the necessity of reaction temperature adjustment
and/or reaction system viscosity adjustment, among others.
Generally, hydrocarbons, halogenated hydrocarbons, ethers and
esters can be used as the solvent in the hydrosilylation reaction.
Preferred among them are heptane, hexane, benzene, toluene, xylene,
tetrahydrofuran and methylene chloride. In certain instances, a
plasticizer or the like which does not affect the hydrosilylation
reaction, for example a paraffin or .alpha.-methylstyrene oligomer,
can also be used.
[0067] For promoting the hydrosilylation reaction, catalyst
reactivation using oxygen (Japanese Kokai Publication
Hei-08-283339) and addition of a sulfur compound are preferred. The
addition of a sulfur compound contributes to reduce the production
time without causing such problems as an increase in production
cost as otherwise resulting from the use of an increased amount of
the expensive platinum catalyst or necessity of removing the
residual catalyst and thus contributes to increase the
productivity. The sulfur compound includes, but is not limited to,
elemental sulfur, thiols, sulfides, sulfoxides, sulfones and
thioketones. Among them, sulfur is especially preferred. In adding
a sulfur compound to the liquid reaction system, the sulfur
compound is dissolved and mixed in advance with a portion of the
reaction mixture or solvent, for instance. Then, the solution can
be homogeneously dispersed in the whole reaction mixture. Thus, for
example, the sulfur compound can be added following dissolution
thereof in an organic solvent such as toluene, hexane or
xylene.
[0068] The addition amount of the sulfur compound can be selected,
for example, within the range of 0.1 to 10 moles per mole of the
metal catalyst or of 0.002 to 0.1 mole per mole of the alkenyl
group, or of 1 to 500 ppm on the whole reaction mixture weight
basis. When the addition amount is too low, the effects of the
present invention may not be fully produced in certain instances.
When it is excessively high, the sulfur compound may reduce the
catalyst activity or inhibit the reaction as the case may be. It is
thus desirable to adequately select the addition amount.
[0069] In the hydrosilylation reaction in the production process
according to the invention, the gaseous phase in the reactor may
comprise an inert gas (e.g. nitrogen or helium) alone or oxygen or
another gas. From the viewpoint of safety in handling inflammable
gases, the hydrosilylation reaction may be carried out in the
presence of an inert gas, such as nitrogen or helium, in the
gaseous phase in the reactor. When the reaction is carried out in
the presence of an inert gas in the gaseous phase in the reactor,
however, the rate of reaction may decrease depending on the
conditions of the hydrosilylation reaction system.
[0070] In the hydrosilylation reaction in the production process
according to the invention, the hydrosilylation reaction can be
safely promoted in the presence of oxygen by selecting the oxygen
concentration in the gaseous phase in the reactor at an amount such
that the formation of an explosive mixture composition can be
avoided. The oxygen concentration in the gaseous phase in the
reactor may be 0.5 to 10%, for instance.
[0071] For preventing the polyether oligomer, reaction solvent
and/or plasticizer in the system, among others, from being oxidized
by oxygen, the hydrosilylation reaction may be carried out in the
presence of an antioxidant. Usable as the antioxidant are phenolic
antioxidants having a radical chain inhibitor function, for
example, 2,6-di-tert-butyl-p-cresol- , 2,6-di-tert-butylphenol,
2,4-dimethyl-6-tert-butylphenol,
2,2'-methylenebis(4-methyl-6-tert-butylphenol),
4,4'-butylidenebis(3-meth- yl-6-tert-butylphenol),
4,4'-thiobis(3-methyl-6-tert-butylphenol),
tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionato]methan-
e, 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane and the
like. Amine type antioxidants such as phenyl-.beta.-naphthylamine,
.alpha.-naphthylamine, N,N'-di-sec-butyl-p-phenylenediamine,
phenothiazine and N,N'-diphenyl-p-phenylenediamine may also be used
as like radical chain inhibitors. The antioxidant is not limited to
those mentioned above, however.
[0072] Further, in the practice of the present invention, the
hydrolyzable group X in the silyl group obtained may be converted
to another hydrolyzable group Y. Particularly when the group X is a
halogen atom, a hydrogen halide having a strong irritating odor is
generated in the step of curing by moisture, so that said group is
preferably converted to another hydrolyzable group. The
hydrolyzable functional group, which is the target of conversion,
includes alkoxy, acyloxy, ketoximate, amido, acid amido, aminoxy,
mercapto and like groups. Various methods are available for
converting a halogen functional group to such hydrolyzable
functional groups. For conversion to an alkoxy group, for instance,
there may specifically be mentioned the method comprising reacting
the halogen functional group with (1) an alcohol or phenol, such as
methanol, ethanol, 2-methoxyethanol, sec-butanol, tert-butanol and
phenol, (2) the sodium, potassium or lithium alkoxide or phenoxide
or the like of an alcohol or phenol, (3) an orthoformate ester such
as methyl orthoformate and ethyl orthoformate or (4) an epoxy
compound such as ethylene oxide, propylene oxide and allyl glycidyl
ether, among others. Particularly when a reaction system comprising
a combination of (1) and (3), namely an alcohol or phenol and an
orthoformate ester, or a reaction system comprising a combination
of (1) and (4), namely an alcohol or phenol and an epoxy compound,
is used, the reaction can be carried out with ease and favorable
results can be obtained. For conversion to an acyloxy group, there
may specifically be mentioned the method comprising reacting the
halogen functional group with (1) a carboxylic acid such as acetic
acid and propionic acid, (2) an acid anhydride such as acetic
anhydride, or (3) the sodium, potassium or lithium salt of a
carboxylic acid, among others. For conversion to an aminoxy group,
there may specifically be mentioned the method comprising reacting
the halogen functional group with (1) a hydroxylamine such as
N,N-dimethylhydroxylamine, N,N-diethylhydroxylamine,
N,N-methylphenylhydroxylamine and N-hydroxypyrrolidine or (2) the
sodium, potassium or lithium salt of a hydroxylamine, among others.
For conversion to an amido group, there may specifically be
mentioned the method comprising reacting the halogen functional
group with (1) a primary or secondary amine such as
N,N-dimethylamine, N,N-diethylamine, N-methylphenylamine and
pyrrolidine or (2) the sodium, potassium or lithium salt of a
primary or secondary amine, among others. For conversion to an acid
amide, there may specifically be mentioned the method comprising
reacting the halogen functional group with (1) an acid amide having
at least one hydrogen atom on the nitrogen atom, such as acetamide,
formamide or propionamide, or (2) the sodium, potassium or lithium
salt of such acid amide, for instance. By using a reaction system
in which a ketoxime such as acetoxime or methyl ethyl ketoxime or a
mercaptan such as N-octylmercaptan and t-butylmercaptan is combined
with an orthoformate ester or an epoxy compound, partial conversion
to the corresponding ketoximate or mercapto group can be effected,
with the remaining groups being converted to the corresponding
orthoformate ester- or epoxy compound-derived alkoxyl groups.
Conversion to another hydrolyzable functional group is applicable
not only to the case of halogen functional groups as mentioned
above but also to various other hydrolyzable functional groups.
[0073] Referring to the copolymer having a molecular chain
substantially composed of one or more acrylic and/or methacrylic
ester monomer unit species, namely component (II) to be used
according to the present invention (hereinafter such copolymer is
referred to as copolymer (II)), the acrylic ester monomer unit
species includes a wide variety of those known in the art as
derived, for example, from methyl acrylate, ethyl acrylate,
n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl
acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, decyl acrylate,
undecyl acrylate, lauryl acrylate, tridecyl acrylate, myristyl
acrylate, cetyl acrylate, stearyl acrylate, bephenyl acrylate and
biphenyl acrylate. The methacrylic ester monomer unit species
includes a wide variety of those known in the art as derived, for
example, from methyl methacrylate, ethyl methacrylate, n-propyl
methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl
methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate,
decyl methacrylate, undecyl methacrylate, lauryl methacrylate,
tridecyl methacrylate, myristyl methacrylate, cetyl methacrylate,
stearyl methacrylate, behenyl methacrylate and biphenyl
methacrylate.
[0074] The molecular chain of copolymer (II) is substantially
composed of one or more acrylic and/or methacrylic ester monomer
unit species. The phrase "substantially composed of such monomer
unit species" means that the acrylic and/or methacrylic ester
monomer unit species occurring in copolymer (II) account for more
than 50%, preferably not less than 70%, of all the monomer units
occurring therein.
[0075] Among various combinations of these monomers, a copolymer
(hereinafter, copolymer (II)-a) having a molecular chain
substantially composed of (a) acrylic and/or methacrylic ester
monomer units having a hydrocarbon group of 1 to 8 carbon atoms and
(b) acrylic and/or methacrylic ester monomer units having a
hydrocarbon group of 10 or more carbon atoms is preferred from the
viewpoint of compatibility and stability. The monomer unit species
(a), namely an acrylic and/or methacrylic ester monomer unit
species having a hydrocarbon group of 1 to 8 carbon atoms, in said
copolymer is represented by the general formula (8):
CH.sub.2=C(R.sup.5)COOR.sup.6 (8)
[0076] wherein R.sup.5 represents a hydrogen atom or a methyl group
and R.sup.6 represents a hydrocarbon group of 1 to 8 carbon
atoms.
[0077] As R.sup.6 in the above general formula (8), there may be
mentioned alkyl groups containing 1 to 8 carbon atoms, such as
methyl, ethyl, propyl, n-butyl, t-butyl and2-ethylhexyl, among
which those containing 1 to 4 are preferred and those containing 1
or 2 carbon atoms are more preferred. The monomer represented by
general formula (8) may comprise one single species or two or more
species.
[0078] The acrylic and/or methacrylic ester unit species having a
hydrocarbon group of 10 or more carbon atoms, which forms monomer
units (b), is represented by the general formula (9):
CH.sub.2=C(R.sup.5)COOR.sup.7 (9)
[0079] wherein R.sup.5 is as defined above and R.sup.7 represents a
hydrocarbon group of 10 or more carbon atoms.
[0080] As R.sup.7 in the above general formula (9), there may be
mentioned, among others, long chain alkyl groups containing 10 or
more carbon atoms, generally 10 to 30, preferably 10 to 20 carbon
atoms, such as lauryl, tridecyl, cetyl, stearyl and groups
containing 22 carbon atoms, as well as biphenyl groups. The monomer
represented by general formula (9) may comprise a single species or
a combination of monomers having, for example, hydrocarbon groups
of 12 and 13 carbon atoms, respectively.
[0081] The molecular chain of copolymer (II)-a is substantially
composed of monomer unit species (a) and (b). The phrase
"substantially composed of monomer unit species (a) and (b)" means
that the monomer unit species (a) and (b) occurring in copolymer
(II)-a account for more than 50%, preferably not less than 70%, of
all the monomer units occurring therein. When the content of the
monomer units (a) and (b) is less than 50%, the compatibility of
polyether oligomer (I) with copolymer (II)-a will be poor and there
is a tendency toward turbidity and, at the same time, the adhesion
characteristics tend to lower.
[0082] The ratio between monomer units (a) and monomer units (b) is
preferably 95:5 to 40:60 by weight, more preferably 90:10 to 60:40
by weight. When the above ratio is higher than 95:5, the
compatibility will become decreased. A ratio lower than 40:60 will
be disadvantageous from the cost viewpoint.
[0083] Copolymer (II) may additionally contain another monomer unit
species copolymerizable with the acrylic and/or methacrylic ester
monomer unit species. As the other monomer unit species, there
maybe mentioned, for example, monomer units derived from acrylic
acids such as acrylic acid and methacrylic acid; amido
group-containing monomers such as acrylamide, methacrylamide,
N-methylolacrylamide and N-methylolmethacrylamide, epoxy
group-containing monomers such as glycidyl acrylate and glycidyl
methacrylate, and amino group-containing monomers such as
diethylaminoethyl acrylate, diethylaminoethyl methacrylate and
aminoethyl vinyl ether; and, further, acrylonitrile, styrene,
.alpha.-methylstyrene, alkyl vinyl ethers, vinyl chloride, vinyl
acetate, vinyl propionate, ethylene and so forth.
[0084] From the viewpoint of contact adhesiveness, copolymer (II)
preferably has a relatively high softening point, preferably a
softening point not lower than 0.degree. C., more preferably not
lower than 20.degree. C. When copolymer (II) has a low softening
point, it is also possible to use a tackifier resin for improving
the contact adhesiveness.
[0085] While the molecular weight of the copolymer (II) component
is not restricted, a number average molecular weight of 500 to
100,000 as expressed in terms of polystyrene equivalent in GPC is
preferred. A number average molecular weight of 1,000 to 10,000 is
more preferred from the viewpoint of ease of handling, for
instance.
[0086] Copolymer (II) can be prepared by a conventional method of
vinyl polymerization. The method of obtaining it includes, but is
not particularly limited to, solution and bulk polymerization
methods utilizing a radical reaction. After adding the monomers
mentioned above, a radical initiator, a chain transfer agent and a
solvent, for instance, the reaction is carried out generally at 50
to 150.degree. C.
[0087] As examples of the radical initiator mentioned above, there
may be mentioned azobisisobutyronitrile, benzoyl peroxide and the
like and, as examples of the chain transfer agent, there may be
mentioned mercaptans, such as n-dodecylmercaptan,
tert-dodecylmercaptan and laurylmercaptan, and halogen-containing
compounds. Preferred for use as the solvent are, for example,
ethers, hydrocarbons, esters and like nonreactive solvents.
[0088] From the viewpoint of contact adhesiveness and final bond
strength, it is preferred that copolymer (II) have a
silicon-containing group crosslinkable under siloxane bond
formation (hereinafter, such silicon-containing group is referred
to as "reactive silicon group").
[0089] Various methods are available for introducing a reactive
silicon group into copolymer (II). For example, there may be
mentioned (A) the method comprising copolymerizing a polymerizable
unsaturated bond- and reactive silicon group-containing compound
with monomers (a) and (b), (B) the method comprising copolymerizing
a polymerizable unsaturated bond--and reactive functional group
(hereinafter referred to as group Y)--containing compound (e.g.
acrylic acid) with monomers (a) and (b) and then reacting the
resulting copolymer with a compound having a reactive silicon group
and a functional group (hereinafter referred to as group Y)
reactive with group Y (e.g. an isocyanato- and
--Si(OCH.sub.3).sub.3--con- taining compound), (C) the method
comprising copolymerizing monomers (a) and (b) in the presence of a
reactive silicon group-containing mercaptan as a chain transfer
agent, (D) the method comprising copolymerizing monomers (a) and
(b) using a reactive silicon group-containing azobisnitrile
compound or disulfide compound as an initiator, and (E) the method
comprising polymerizing monomers (a) and (b) in the manner of
living radical polymerization and introducing a reactive silicon
group into the polymer at molecular terminals thereof, without any
particular restriction thereto. It is also possible to employ any
arbitrary combination of methods (A) to (E). For example, methods
(A) and (C) may be combined: thus, it is possible to employ the
method comprising copolymerizing a polymerizable unsaturated bond-
and reactive silicon group-containing compound with monomers (a)
and (b) in the presence of a reactive silicon group-containing
mercaptan as a chain transfer agent.
[0090] The polymerizable unsaturated bond- and reactive silicon
group-containing compound referred to above under (A) is
represented by the general formula (10):
CH.sub.2=C(R.sup.5)COOR.sup.8-[Si(R.sup.2.sub.2-b)(X.sub.b)O].sub.mSi(R.su-
p.4.sub.3-a)X.sub.a (10)
[0091] wherein R.sup.5is as defined above, R.sup.8 represents a
divalent alkylene group of 1 to 6 carbon atoms with R.sup.3,
R.sup.4, X, a, b and m are as defined above, or the general formula
(11):
CH.sub.2=C(R.sup.5)-[Si(R.sup.3.sub.2-b)(X.sub.b)O].sub.mSi(R.sup.4.sub.3--
a)X.sub.1 (11)
[0092] wherein R.sup.3, R.sup.4, R.sup.5, X, a, b and m are as
defined above.
[0093] As the group R.sup.8 in the above general formula (10),
there may be mentioned ones having 1 to 6 carbon atoms, preferably
ones having 1 to 4 carbon atoms, such as methylene, ethylene and
propylene.
[0094] As specific examples of the hydrolyzable group X in formula
(10) or (11), there may be mentioned, among others, halogen atoms,
a hydrogen atom, alkoxy groups, acyloxy groups, ketoximate groups,
amino groups, amido groups, aminoxy groups, mercapto groups,
alkenyloxy groups and the like. Among them, alkoxy groups, such as
methoxy and ethoxy, are preferred because of their mild
hydrolyzability. The monomer represented by general formula (10) or
(11) may comprise either one single species or two or more
species.
[0095] As the polymerizable unsaturated bond- and reactive silicon
group-containing compound represented by general formula (10) or
(11), there may be mentioned, for example,
.gamma.-methacryloxyalkylpolyalkoxys- ilane such as
.gamma.-methacryloxypropyltrimethoxysilane,
.gamma.-methacryloxypropylmethyldimethoxysilane and
.gamma.-methacryloxypropyltriethoxysilane,
.gamma.-acryloxyalkylpolyalkox- ysilane such as
.gamma.-acryloxy-propyltrimethoxysilane,
.gamma.-acryloxypropylmethyldi-methoxysilane and
.gamma.-acryloxypropyltr- iethoxysilane, and
vinylalkylpolyalkoxysilanes such as vinyltrimethoxysilane,
vinylmethyldimethoxysilane and vinyltriethoxysilane.
[0096] As examples of group Y and group Y' mentioned above under
(B), there maybe mentioned various combinations of groups. For
example, group Y may be an amino, hydroxyl or carboxylic acid
group, while group Y' may be an isocyanato group. In another
example, group Y may be an allyl group and group Y' may be a
silicon hydride group (H--Si), as described in Japanese Kokai
Publication Sho-54-36395, Japanese Kokai Publication Hei-01-272654,
and Japanese Kokai Publication Hei-02-214759. In this case, group Y
can bind to group Y' in the manner of hydrosilylation in the
presence of a group VIII transition metal.
[0097] As the reactive silicon group-containing mercaptan to be
used as a chain transfer agent as mentioned above under (C), there
may be mentioned .gamma.-mercaptopropyltrimethoxysilane,
.gamma.-mercaptopropylmethyldimet- hoxysilane and
.gamma.-mercaptopropyltriethoxysilane, among others. It is also
possible, as described in Japanese Kokai Publication Sho-59-78222,
to copolymerize monomers (a) and (b) in the presence of a
bifunctional radical-polymerizable compound and an
alkoxysilyl-containing mercaptan as a chain transfer agent.
[0098] As the reactive silicon group-containing azobisnitrile or
disulfide compound mentioned above under (D), there may be
mentioned those alkoxysilyl-containing azobisnitrile compounds or
alkoxysilyl-containing disulfide compounds which are described in
Japanese Kokai Publication Sho-60-23405 and Japanese Kokai
Publication Sho-62-70405, for instance.
[0099] As for the method mentioned above under (E), reference may
be made to Japanese Kokai Publication Hei-09-272714, for
instance.
[0100] Furthermore, there may be mentioned the method comprising
using a reactive silicon group-containing mercaptan and a reactive
silicon group-containing radical polymerization initiator
combinedly, as described in Japanese Kokai Publication
Sho-59-168014 and Japanese Kokai Publication Sho-60-228516, for
instance.
[0101] The number of reactive silicon groups contained in copolymer
(II) is not particularly restricted. From the view point of effects
on bond strength and cost, however, it is preferred that each
molecule of copolymer (II) have, on an average, not less than 0.1
but not more than2.0, more preferably not less than 0.5 and not
more than 1.5, reactive silicon groups.
[0102] As regards the mixing ratio between polyether oligomer (I)
and copolymer (II) in the composition of the present invention, it
is preferred, from the viewpoint of characteristic improving
effects, that the composition contain 10 to 200 parts by weight,
more preferably 20 to 160 parts by weight, of copolymer (II) per
100 parts by weight of polyether oligomer (I). Generally, an
adequate mixing ratio is to be selected according to the intended
use and performance characteristics.
[0103] The accelerator, which is component (III) to be used
according to the invention, is not particularly restricted but may
be any of silanol condensation catalysts in general use and capable
of promoting the reaction of the reactive silicon group. As
specific examples of such accelerators, there may be mentioned,
among others, organotin compounds, organic titanate compounds,
organoaluminum compounds, organozirconium compounds, amine
compounds, acidic phosphate esters, reaction products from acidic
phosphate esters and amine compounds, saturated or unsaturated
polybasic carboxylic acids or anhydrides thereof, salts or like
reaction products from carboxylic acid compounds and amine
compounds, and lead octylate. As the above tin compounds, there may
be mentioned dibutyltin dilaurate, dibutyltin maleate, dibutyltin
diacetate, dioctyltin maleate, dibutyltin phthalate, stannous
octoate, stannous naphthenate, stannous stearate, stannous
versatate, reaction products from dibutyltin oxide and phthalate
esters, chelate compounds such as dibutyltin diacetylacetonate and
the like, and dibutyltin oxide. As the organic titanate compounds,
there may be mentioned titanate esters such as tetrabutyl titanate,
tetrapropyl titanate, tetraisopropyl titanate and triethanolamine
titanate, and chelate compounds such as titanium
tetraacetylacetonate, among others. As the organoaluminum
compounds, there may be mentioned aluminum trisacetylacetonate,
aluminum tris(ethyl acetoacetate), diisopropoxyaluminum ethyl
acetoacetate and the like. As the zirconium compounds, there may be
mentioned zirconium tetraisopropoxide, zirconium tetrabutoxide and
zirconium tetraacetylacetonate, among others. As the amine
compounds, there may be mentioned butylamine, octylamine,
laurylamine, dibutylamine, monoethanolamine, diethanolamine,
triethanolamine, diethylenetriamine, triethylenetetramine,
oleylamine, cyclohexylamine, benzylamine, diethylaminopropylamine,
xylylenediamine, triethylenediamine, guanidine, diphenylguanidine,
2,4,6-tris(dimethylaminomethyl)phenol, morpholine,
N-methylmorpholine, 2-ethyl-4-methylimidazole, and
1,8-diazabicyclo[5.4.0]undecene-7 (DBU), among others. Salts of
these amines with carboxylic acids or the like may also be used. As
other examples, there may be mentioned low-molecular-weight
polyamide resins obtained from an excess of a polyamine and a
polybasic acid and reaction products from an excess of a polyamine
and an epoxy compound. In addition, there may be mentioned
organolead compounds such as lead octylate, organoiron compounds
such as iron naphthenate, organovanadium compounds, bismuth salts
such as bismuth-tris(2-ethylhexanoate) and bismuth tris
(neodecanoate), and reaction products from an excess of an organic
carboxylic acid and an organic amine. These accelerators may be
used singly or two or more of them may be used in combination.
Among these silanol condensation catalysts, organometallic
compounds or combination systems comprising an organometallic
compound and an amine compound are preferred from the viewpoint of
curability.
[0104] Such an accelerator is used generally in an amount selected
according to the intended use and performance characteristics.
Preferably, it is used in an amount of 0.1 to 20, more preferably
from the cost viewpoint 0.5 to 10 parts, per 100 parts by weight of
the total of polyether oligomer component (I) and copolymer
component (II).
[0105] To the contact adhesive in which the curable resin
composition of the present invention is used, there maybe added,
where necessary, a tackifier resin, filler, plasticizer, pigment,
adhesion aid, silicon compound, ultraviolet absorber, antioxidant,
light stabilizer, solvent and/or a like additive.
[0106] Any known filler can be used as the filler. Examples are
heavy calcium carbonate, colloidal calcium carbonate, light calcium
carbonate, magnesium carbonate, kaolin, talc, clay, bentonite,
organic bentonite, silica, titanium oxide, aluminum silicate,
magnesium oxide, zinc oxide, carbon black, glass balloons, and the
like. These fillers may be used singly or two or more of them may
he used combinedly.
[0107] Any known plasticizer may be used as the plasticizer
mentioned above. Examples are phthalate esters such as dioctyl
phthalate and butyl benzyl phthalate, aliphatic carboxylic acid
esters, nonaromatic dibasic acid esters, glycol esters and
phosphate esters, as well as relatively high-molecular plasticizers
such as polyesters from a dibasic acid and a dihydric alcohol,
polypropylene glycol and derivatives thereof, polystyrenes,
paraffins, chlorinated paraffins, epoxidized soybean oil, and the
like. These plasticizers may be used either singly or in
admixture.
[0108] For improving the adhesiveness, curability and/or storage
stability, various aminosilanes or silicon compounds such as
epoxysilanes may be added. As examples thereof, there may be
mentioned, without any particular limitative meaning,
vinyltrimethoxysilane, vinyltriethoxysilane,
methyltrimethoxysilane, phenyltrimethoxysilane,
diphenyldimethoxysilane, phenylmethyldimethoxysilane,
dimethyldimethoxysilane, phenyltriethoxysilane,
diphenyldiethoxysilane, phenylmethyldiethoxysilane,
dimethyldiethoxysilane, .gamma.-methacryloxypropyltrimethoxysilane,
.gamma.-methacryl-oxypropylme- thyldimethoxysilane,
.gamma.-methacryloxy-propyltriethoxysilane,
.gamma.-aminopropyltrimethoxysilane,
.gamma.-aminopropyltriethoxysilane,
.gamma.-aminopropylmethyl-dimethoxysilane,
N-(.beta.-aminoethyl)-.gamma.-- aminopropyl-trimethoxysilane,
N-(.beta.-aminoethyl)-.gamma.-aminopropyl-tr- iethoxysilane,
N-(.beta.-aminoethyl)-.gamma.-aminopropyl-methyldimethoxysi- lane,
1,3-diaminoisopropyltrimethoxysilane,
.gamma.-glycidoxypropyltrimeth- oxysilane,
.gamma.-glycidoxypropyltriethoxysilane, .gamma.-glycidoxy-propy-
lmethyldimethoxysilane,
.beta.-(3,4-epoxycyclo-hexyl)ethyltrimethoxysilane and the like.
These silicon compounds may be used singly or two or more of them
may be used combinedly.
[0109] The solvent includes, but is not particularly limited to,
nonreactive ones such as hydrocarbons, acetate esters, alcohols,
ethers and ketones.
[0110] The method of preparing the contact adhesive in which the
curable resin composition of the present invention, comprising
component (I), component (II) and component (III), is used is not
particularly restricted. Thus, for example, such an ordinary method
may be employed that comprises mixing components (I), (II) and
(III) together and kneading the mixture at ordinary temperature or
with heating using a mixer, roll, kneader or the like, or
dissolving the above components respectively in small amounts of an
appropriate solvent and mixing the solutions together.
[0111] By adequately combining these components, it is possible to
prepare the adhesive in the one component or two component form, or
in the three or more component form as the case may be. The method
of applying the adhesive is not restricted. The adhesive can be
applied in the conventional manner using a spatula, roll or sprayer
or the like. It is also possible to apply the adhesive directly
from a container (e.g. tube, cartridge) in which the adhesive is
stored.
[0112] As regards the method of adhesion, after application, the
adhesive is allowed to stand in the air for a certain period of
time, during which curing of the adhesive by moisture in the air
proceeds, and tack is developed in the adhesive layer. On that
occasion, heating and/or humidification may be made to promote tack
development. Adhesion of adherends is conducted during the tack is
retained in the adhesive layers.
[0113] The present invention can provide curable resin compositions
useful as contact adhesives with a prolonged tack retention period,
without affecting the final bond strength.
Best Mode for Carrying Out the Invention
[0114] The following specific examples illustrate the present
invention in further detail. They are, however, by no means
limitative of the scope of the invention.
Synthesis Example 1
[0115] Polyoxypropylene glycol with an average molecular weight of
10,000 as determined by terminal group analysis was prepared by
polymerizing propylene oxide using polypropylene glycol as an
initiator and zinc hexacyanocobaltate-glyme complex as a catalyst.
Then, NaOMe in the form of a methanol solution was added in an
amount of 1.2 equivalents per hydroxyl group of the above
hydroxyl-terminated polyether oligomer, the methanol was distilled
off, and 3-chloro-2-methyl-1-propene was further added to thereby
convert the terminal hydroxyl group to a methallyl group. Then, 10
g of hexane was added to 500 g of the oligomer obtained and
azeotropic dehydration was effected at 90.degree. C., the hexane
was distilled off under reduced pressure, and the vessel was purged
with 8% O.sub.2/N.sub.2. To the vessel contents were added 25 .mu.l
of sulfur (1% (by weight) toluene solution) and 56 .mu.l of
platinum-divinyldisiloxane complex (3% (by weight as platinum)
xylene solution), and 24.2 g DMS (dimethoxymethylsilane) was
gradually added dropwise with stirring. After allowing the reaction
to proceed at 90.degree. C. for 5 hours, the unreacted DMS was
distilled off under reduced pressure to give a reactive silicon
group-containing polyoxypropylene polymer. By .sup.1H-NMR analysis
of the polymer obtained, it was confirmed that the terminal
reactive silicon group introduction percentage was 98% (polymer A).
Polymer A thus obtained had a number average molecular weight of
about 10,000.
Synthesis Example 2
[0116] Polyoxypropylene glycol with an average molecular weight of
20,000 as determined by terminal group analysis was prepared by
polymerizing propylene oxide using polypropylene glycol as an
initiator and zinc hexacyanocobaltate-glyme complex as a catalyst.
Then, NaOMe in the form of a methanol solution was added in an
amount of 1.2 equivalents per hydroxyl group of the above
hydroxyl-terminated polyether oligomer, the methanol was distilled
off, and 3-chloro-2-methyl-1-propene was further added to thereby
convert the terminal hydroxyl group to a methallyl group. Then, 10
g of hexane was added to 500 g of the oligomer obtained and
azeotropic dehydration was effected at 90.degree. C., the hexane
was distilled off under reduced pressure, and the vessel was purged
with 8% O.sub.2/N.sub.2. To the vessel contents were added 24 .mu.l
of sulfur (1% (by weight) toluene solution) and 54 .mu.l of
platinum-divinyldisiloxane complex (3% (by weight as platinum)
xylene solution), and 11.5 g of DMS (dimethoxymethylsilane) was
gradually added dropwise with stirring. After allowing the reaction
to proceed at 90.degree. C. for 10 hours, the unreacted DMS was
distilled off under reduced pressure to give a reactive silicon
group-containing polyoxypropylene polymer. By .sup.1H-NMR analysis
of the polymer obtained, it was confirmed that the terminal
reactive silicon group introduction percentage was 98% (polymer B).
Polymer B thus obtained had a number average molecular weight of
about 20,000.
Comparative Synthesis Example 1
[0117] Polyoxypropylene glycol with an average molecular weight of
10,000 as determined by terminal group analysis was prepared by
polymerizing propylene oxide using polypropylene glycol as an
initiator and zinc hexacyanocobaltate-glyme complex as a catalyst.
Then, NaOMe in the form of a methanol solution was added in an
amount of 1.2 equivalents per hydroxyl group of the above
hydroxyl-terminated polyether oligomer, the methanol was distilled
off, and 3-chloro-1-propene was further added to thereby convert
the terminal hydroxyl group to an allyl group. Then, 10 g of hexane
was added to 500 g of the oligomer obtained and azeotropic
dehydration was effected at 90.degree. C., the hexane was distilled
off under reduced pressure, and the vessel was purged with
nitrogen. To the vessel contents was added 30 .mu.l of
platinum-divinyldisiloxane complex (3% (by weight as platinum)
xylene solution), and 9.0 g of DMS (dimethoxymethylsilane) was
gradually added dropwise with stirring. After allowing the reaction
to proceed by heating the mixed solution at 90.degree. C. for 2
hours, the unreacted DMS was distilled off under reduced pressure
to give a reactive silicon group-containing polyoxypropylene
polymer. By.sup.1H-NMR analysis of the polymer obtained, it was
confirmed that the terminal reactive silicon group introduction
percentage was 82% (polymer C). Polymer C thus obtained had a
number average molecular weight of about 10,000.
Comparative Synthesis Example 2
[0118] Polyoxypropylene glycol with an average molecular weight of
10, 000 as determined by terminal group analysis was prepared by
polymerizing propylene oxide using polypropylene glycol as an
initiator and zinc hexacyanocobaltate-glyme complex as a catalyst.
Then, NaOMe in the form of a methanol solution was added in an
amount of 1.2 equivalents per hydroxyl group of the above
hydroxyl-terminated polyether oligomer, the methanol was distilled
off, and 3-chloro-1-propene was further added to thereby convert
the terminal hydroxyl group to an allyl group. Then, 10 g of hexane
was added to 500 g of the oligomer obtained and azeotropic
dehydration was effected at 90.degree. C., the hexane was distilled
off under reduced pressure, and the vessel was purged with
nitrogen. To the vessel contents was added 30 .mu.l of
platinum-divinyldisiloxane complex (3% (by weight as platinum)
xylene solution), and 6.5 g of DMS (dimethoxymethylsilane) was
gradually added dropwise with stirring. After allowing the reaction
to proceed by heating the mixed solution at 90.degree. C. for 2
hours, the unreacted DMS was distilled off to give a reactive
silicon group-containing polyoxypropylene polymer. By .sup.1H-NMR
analysis of the polymer obtained, it was confirmed that the
terminal reactive silicon group introduction percentage was 65%
(polymer D). Polymer D thus obtained had a number average molecular
weight of about 10,000.
Synthesis Example 3
[0119] To 43 g of toluene heated at 110.degree. C. was added
dropwise over 4 hours a solution of 2.0 g of azobisisobutyronitrile
as a polymerization initiator in a mixture of 28 g of butyl
acrylate, 46 g of methyl methacrylate, 20 g of stearyl
methacrylate, 4.4 g of
.gamma.-methacryloxypropylmethyldimethoxysilane and 23 g of
toluene. Then, polymerization was effected for 2 hours to give a
copolymer (polymer E) with a solid concentration of 60% and a
number average molecular weight (Mn) as determined by GPC
(polystyrene equivalent) of 8,500.
Synthesis Example 4
[0120] To 43 g of toluene heated at 110.degree. C. was added over 4
hours a mixture of 6.0 got butyl acrylate, 66 got methyl
methacrylate, 13 g of stearyl methacrylate, 5.4 g of
.gamma.-methacryloxypropylmethyldimethoxys- ilane, 7.0 g of
.gamma.-mercaptopropylmethyldimethoxysilane and 23 g of toluene
with 2.6 g of azobisisobutyronitrile dissolved therein as a
polymerization initiator and, then, the polymerization was allowed
to proceed for 2 hours to give a copolymer (polymer F) with a solid
concentration of 60% and a number average molecular weight (Mn) of
2,200 as determined by GPC (polystyrene equivalent).
Synthesis Example 5
[0121] To 43 g of toluene heated at 110.degree. C. was added
dropwise over 4 hours a mixture of 32 g of butyl acrylate, 62 g of
methyl methacrylate, 4.4 g of
.gamma.-methacryloxypropylmethyl-dimethoxysilane and 23 g of
toluene with 2.0 g of azobisisobutyronitrile dissolved therein as a
polymerization initiator, and the polymerization reaction was
carried out for 2 hours to give a copolymer having a number average
molecular weight (Mn) of 8,400 as determined by GPC (polystyrene
equivalent) with a solid concentration of 60% (polymer G).
Example 1
[0122] The reactive silicon group-containing polyether oligomer
(polymer A) obtained in Synthesis Example 1 and the copolymer
(polymer E) obtained in Synthesis Example 3 were blended with each
other in a solids ratio (by weight) of 60/40, and the volatile
matter was removed by heating at 110.degree. C. under reduced
pressure using an evaporator to give a clear and viscous liquid
with a solids concentration of not less than 99%. To 100 weight
parts of this liquid were added 50 weight parts of surface-treated
colloidal calcium carbonate (mean particle size: 0.08 .mu.m;
trademark: Hakuenka CCR; product of Shiraishi Kogyo), 3 weight
parts of vinyltrimethoxysilane (trademark: A-171; product of Nippon
Unicar) as a silicon compound, 2 weight parts of
N-(.beta.-aminoethyl)-.g- amma.-aminopropyltrimethoxysilane
(trademark: A-1122; product of Nippon Unicar) and 2 weight parts of
dibutyltin diacetylacetonate (trademark: U-220; product of Nitto
Kasei), followed by uniform blending to give a curable resin
composition of the present invention.
Example 2
[0123] A curable resin composition of the present invention was
prepared in the same manner as in Example 1 except that the
polyether oligomer obtained in Synthesis Example 1 (polymer A) was
used as the reactive silicon group-containing polyether oligomer
and the copolymer obtained in Synthesis Example 4 (polymer F) as
the copolymer.
Example 3
[0124] A curable resin composition of the present invention was
prepared in the same manner as in Example 1 except that the
polyether oligomer obtained in Synthesis Example 2 (polymer B) as
the reactive silicon group-containing polyether oligomer and the
copolymer obtained in Synthesis Example 3 (polymer E) as the
copolymer.
Example 4
[0125] A curable resin composition of the present invention was
prepared in the same manner as in Example 1 except that the
polyether oligomer obtained in Synthesis Example 1 (polymer A) was
used as the reactive silicon group-containing polyether oligomer
and the copolymer obtained in Synthesis Example 4 (polymer G) as
the copolymer. When polymer A and polymer G were blended together
and the volatile matter was removed by heating at 110.degree. C.
under reduced pressure, a turbid, viscous liquid was obtained.
Comparative Example 1
[0126] A curable resin composition of the present invention was
prepared in the same manner as in Example 1 except that the
polyether oligomer obtained in Comparative Synthesis Example 1
(polymer C) was used as the reactive silicon group-containing
polyether oligomer and the copolymer obtained in Synthesis Example
3 (polymer E) as the copolymer.
Comparative Example 2
[0127] A curable resin composition of the present invention was
prepared in the same manner as the Example 1 except that the
polyether oligomer obtained in Comparative Synthesis Example 1
(polymer C) was used as the reactive silicon group-containing
polyether oligomer and the copolymer obtained in Synthesis Example
4 (polymer F) as the copolymer.
Comparative Example 3
[0128] A curable composition of the present invention was prepared
in the same manner as in Example 1 except that the polyether
oligomer obtained in Comparative Synthesis Example 2 (polymer D)
was used as the reactive silicon group-containing polyether
oligomer and the copolymer obtained in Synthesis Example 3 (polymer
E) as the copolymer.
Comparative Example 4
[0129] A curable resin composition of the present invention was
prepared in the same manner as in Example 1 except that the
polyether oligomer obtained in Comparative Synthesis Example 1
(polymer C) was used as the reactive silicon group-containing
polyether oligomer and the copolymer obtained in Synthesis Example
4 (polymer G) as the copolymer. When polymer C was blended with
polymer G and the volatile matter was removed by heating at
110.degree. C. under reduced pressure, a turbid, viscous liquid was
obtained.
[0130] The physical properties of the cured products were measured
in the following manner.
[0131] (1) Tack development and retention periods and tackiness
[0132] The contact adhesives prepared in Examples 1, 2, 3 and 4 and
Comparative Examples 1, 2, 3 and 4 were each spread thinly over
aluminum substrates and the time until tack development, tackiness
and tack retention period (period from development to disappearance
of tack) were determined by finger touch under the conditions of
23.degree. C. and a humidity of 50%. The tackiness was evaluated
according to the following criteria:
[0133] Tackiness: .circleincircle. much stronger than,
.largecircle. almost comparable to, and .DELTA. weaker than the
tack of the curable resin composition of Comparative Example 1.
[0134] (2) Shear strength
[0135] For tensile shear strength measurements, JIS H 4000 aluminum
sheets A-1050P (100.times.25.times.2 mm test specimens) were used
according to JIS K 6850. Each of the above curable resin
compositions was thinly spread over the specimens using a spatula.
After 5 minutes, the test specimens were laminated together and
pressure was applied to the assemblies by hand to give specimens
for testing. These specimens were cured at 23.degree. C. for 2 days
and then further at 50.degree. C. for 3 days and then subjected 10
to tensile testing.
[0136] (3) Peel strength
[0137] For T-peel strength measurements, JIS H 4000 aluminum sheets
A-1050P (200.times.25.times.0.1 mm test specimens) were used
accordingly to JIS K 6854. Each of the above curable resin
compositions was thinly spread over the specimens using a spatula
and, 5 minutes later, the test specimens were laminated together
and pressure was applied using a hand roller to give test
specimens. Each test specimen was cured at 23.degree. C. for 2 days
and further at 50.degree. C. for 3 days and then subjected to
tensile testing.
[0138] The measurement results are shown in Table 1.
1 TABLE 1 Example Comparative Example 1 2 3 4 1 2 3 4 Polyether
oligomer A A B A C C D C Copolymer E F E G E F E G Tack Time until
min. 15 15 20 15 10 10 15 10 development Tackiness .largecircle.
.largecircle. .circleincircle. .largecircle. .largecircle.
.largecircle. .DELTA. .largecircle. Retention min. 120 120 180 120
50 50 120 45 period Sheer MPa 8.80 9.13 10.6 6.10 8.83 8.80 5.20
5.95 strength Peel N/25 62 76 115 55 63 62 43 52 strength mm
[0139] From the data shown in Table 1, it is evident that the time
until tack development is short in Comparative Examples 1, 2 and 4
representing the prior art and that, as seen in those examples,
adjustment to prolong the tack retention period results in reduced
tackiness and bond strength as shown in Comparative Example 3. On
the contrary, in Examples 1, 2 and 4, the tack retention period
could be prolonged while maintaining the same physical properties
as those attainable in the prior art. In Example 3, the physical
properties and tack retention time were further improved by using a
higher molecular weight polyether oligomer as component (I).
* * * * *