Primer composition

In order to provide a general-purpose aqueous primer composition requiring no organic solvent and capable of improving adhesive strength and durability while ensuring an adequate application life required for the work of primer coating process, a primer composition according to the present invention contains (a) a modified polyisocyanate obtained by reaction of polyisocyanate; an emulsifying agent having an active hydrogen group reactable to an isocyanate group; and a silane coupling agent having an active hydrogen group reactable to an isocyanate group and (b) a core shell emulsion having a core layer of a rubbery polymer and a shell layer of a glassy polymer and having an active hydrogen group reactable to an isocyanate group in the core layer and/or the shell layer.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a primer composition and, more 
particularly, to a primer composition for use in a priming process applied 
when an adhesive such as a sealant and adherends such as concrete, woods, 
metals, plastics and others are adhesive bonded together. 
2. Description of the Prior Art 
When an adhesive such as a sealant used mainly for building constructions 
is filled into joints of adherends including concrete, woods, metals and 
plastics, the priming process is often applied to the adherend, for the 
purpose of increasing adhesive strength and adhesive durability. 
A primer composition usable for the purpose of this kind is disclosed in, 
for example, Japanese Laid-Open Patent Publication No. Hei 3(1991)-6274, 
which discloses a primer composition comprising a reactant of a trimer of 
isophorone diisocyanate with an active-hydrogen-group-containing resin; a 
silane coupling agent; and a curing-catalyst-containing organic solvent 
solution. Also, Japanese Laid-Open Patent Publication No. Hei 
6(1994)-329925 discloses a primer composition comprising polyisocyanate 
modified by mercapto silane having an alkoxy group; polyisocyanate having 
one or more isocyanurate rings and two or more isocyanate groups; at least 
one of alkoxy silane and .gamma.-chloropropyl trimethoxy silane; and 
chlorinated polymer dissolved in an inert organic solvent. 
However, any of these known primer compositions contain an organic solvent. 
An aqueous primer composition containing no organic solvent for purposes 
of this kind has not been known so far. 
On the other hand, from the viewpoints of global environment, safety, 
hygiene and the like, reduction of the amount of use of the organic 
solvent has recently come to be urgently necessary, for the reason of 
which development of an aqueous primer composition has been being strongly 
desired for a primer composition for use in the priming process for the 
adhesive such as a sealant. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to provide an aqueous 
primer composition requiring no organic solvent and capable of improving 
adhesive strength and durability while ensuring an adequate application 
life required for the work of primer coating process. 
The present invention is directed to a primer composition comprising (a) a 
modified polyisocyanate obtained by reaction of polyisocyanate; an 
emulsifying agent having an active hydrogen group reactable to an 
isocyanate group; and a silane coupling agent having an active hydrogen 
group reactable to an isocyanate group and (b) a core shell emulsion 
having a core layer of a rubbery polymer and a shell layer of a glassy 
polymer and having an active hydrogen group reactable to an isocyanate 
group in the core layer and/or the shell layer. 
Preferably, the core shell emulsion (b) has the active hydrogen group in 
the core layer. Also, it is preferable that a glass transition temperature 
(Tg) of the rubbery polymer of the core layer of the core shell emulsion 
(b) is not more than 20.degree. C. and a glass transition temperature (Tg) 
of the glassy polymer of the shell layer of the core shell emulsion (b) is 
not less than 80.degree. C. 
Additionally, it is desirable that the polyisocyanate in the modified 
polyisocyanate (a) is an isocyanurate group containing polyisocyanate 
containing an isocyanurate group using 1,6-diisocyanato hexane as a base. 
Desirably, the emulsifying agent is polyoxyethylene alkyl ether and/or 
polyoxyethylene alkylaryl ether. Further, it is preferable that the silane 
coupling agent is a mercapto silane base silane coupling agent. 
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
In the primer composition according to the present invention, a modified 
polyisocyanate (a) is a reaction product produced by reaction of an active 
hydrogen group reactable to an isocyanate group of an emulsifying agent 
and an active hydrogen group reactable to an isocyanate group of a silane 
coupling agent with an isocyanate group of a polyisocyanate in a 
prescribed proportion. 
Polyisocyanates of the present invention mainly include diisocyanate of 
aliphatic and/or alicyclic and polyisocyanate containing derivative with 
the diisocyanate of aliphatic and/or alicyclic as the base. Preferably, 
the polyisocyanates employed include isocyanurate group containing 
polyisocyanate containing an isocyanurate group using 
1,6-diisocyanato-hexane (hereinafter it is referred to as HDI) and/or 
1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane (hereinafter 
it is referred to as IPDI) as the base; uretdion group containing 
polyisocyanate containing an uretdion group using HDI and/or IPDI as the 
base; allophanate group containing polyisocyanate containing an 
allophanate group using HDI and/or IPDI as the base; biuret group 
containing polyisocyanate containing a biuret group using HDI and/or IPDI 
as the base; and oxadiazinetrion group containing polyisocyanate 
containing an oxadiazinetrion group using HDI and/or IPDI as the base. 
These derivative-containing polyisocyanate may include two or more kinds 
of derivatives, and two or more kinds of such derivatives-containing 
polyisocyanates may be employed together, and further preferable among 
them may be the isocyanurate group containing polyisocyanate containing 
the isocyanurate group using HDI as the base. Also, it is preferable that 
the isocyanate content is in the range of about 10% by weight to about 40% 
by weight. 
The emulsifying agents having the active hydrogen group reactable to the 
isocyanate group of the polyisocyanate include, for example, nonionic 
emulsifiers having a hydroxyl group or a mercapto group as the active 
hydrogen group reactable to the isocyanate group. Preferable among them is 
a polyoxyethylene base emulsifying agent having the hydroxyl group. 
Examples of these emulsifying agents are polyoxyethylene alkyl ethers 
including polyoxyethylene monomethyl ether, polyoxyethylene monolauryl 
ether and polyoxyethylene monooleyl ether; polyoxyethylene alkylaryl 
ethers including polyoxyethylene monooctylphenyl ether and polyoxyethylene 
monononylphenyl ether; and polyoxyethylene sorbitan fatty acid esters 
including polyoxyethylene sorbitan monolaurate and polyoxyethylene 
sorbitan monostearate. 
These emulsifying agents may be employed alone or in combination with two 
or more kinds, and preferable among them are polyoxyethylene alkyl ether 
and/or polyoxyethylene alkyl aryl ether. 
Preferably, the polyisocyanate is allowed to react with the emulsifying 
agent with the equivalent ratio of 0.010-0.034 of the active hydrogen 
group of the emulsifying agent per 1.00 of an isocyanate group in the 
polyisocyanate. With the equivalent ratio less than 0.010 of the active 
hydrogen group of the emulsifying agent per 1.00 of the isocyanate group, 
insufficient emulsification may be caused in some instances. On the other 
hand, with the equivalent ratio more than 0.034 of the active-hydrogen 
group of the emulsifying agent per 1.00 of the isocyanate group, 
hydrophilic nature may increase excessively to cause deterioration of the 
properties including water resistance. 
The silane coupling agents having the active hydrogen group reactable to 
the isocyanate group of the polyisocyanate include, for example, silane 
coupling agents having a mercapto group, an amino group as the active 
hydrogen group reactable to the isocyanate group. Examples of the silane 
coupling agents are mercaptosilane base silane coupling agents, such as 
.beta.-mercapto ethyltriethoxy silane and .gamma.-mercapto 
propyltrimethoxy silane; and aminosilane base silane coupling agents, such 
as .gamma.-aminopropyltrimethoxy silane and .gamma.-aminopropyltriethoxy 
silane. Preferable among them are the mercaptosilane base silane coupling 
agents, and further preferable is the .gamma.-mercapto propyltrimethoxy 
silane. 
Preferably, the polyisocyanate is allowed to react with the silane coupling 
agent with the equivalent ratio of 0.010-0.300 of the active hydrogen 
group of the silane coupling agent per 1.00 of the isocyanate group in the 
polyisocyanate. With the equivalent ratio of less than 0.010 of the active 
hydrogen group of the silane coupling agent per 1.00 of the isocyanate 
group, insufficient adhesion of an adherend by means of the silane 
coupling agent may occur to lower water resistance. On the other hand, 
with the equivalent ratio of more than 0.300 of the active hydrogen group 
of the silane coupling agent per 1.00 of the isocyanate group, 
concentration of a free isocyanate group may decrease excessively to cause 
deterioration of the properties including durability in adhesion 
properties. 
The modified polyisocyanate (a) can be obtained by mixing the components of 
polyisocyanate, emulsifying agent and silane coupling agent in the 
above-mentioned reacting proportions and stirring the mixture for about 1 
hour to about 8 hours at about 50.degree. C. to about 90.degree. C. to be 
allowed to react. It is preferable that the content of the free isocyanate 
group in the modified polyisocyanate (a) thus obtained is in the range of 
11.5 to 21.5% by weight. With the content of less than 11.5%, the 
concentration of free isocyanate group may decrease excessively to cause 
deterioration of the properties including durability in adhesion 
properties. On the other hand, with the content of more than 21.5%, a pot 
life after the mixture with the core shell emulsion (b) may be shortened. 
To obtain the modified polyisocyanate (a) of a desired free isocyanate 
group content, a sampling of the reactant from a reaction system can be 
made with time in the course of the abovesaid reaction, to determine the 
isocyanate group content by an amine equivalent weight method so that the 
reaction can be concluded when the isocyanate group content reaches a 
predetermined content. Preferably, the components are mixed in advance in 
such proportions that when reaction of the emulsifying agent and the 
silane coupling agent with the polyisocyanate is quantitatively concluded, 
the content of the free isocyanate group in the modified polyisocyanate 
(a) obtained can be in the range of 11.5 to 21.5%, and threafter the mixed 
components are allowed to react until their reaction is completely 
concluded. 
Further, it is preferable that the modified polyisocyanate (a) obtained has 
a viscosity of 100 to 10,000 mPa.multidot.s (at 23.degree. C.). 
A core shell emulsion (b) of the present invention is an emulsion of a core 
shell polymer having a core layer of a rubbery polymer and a shell layer 
of a glassy polymer, and the core layer and/or the shell layer have an 
active hydrogen group reactable to an isocyanate group. 
The core shell emulsion, which may include those obtained by various kinds 
of synthesizing methods, can be usually obtained by a consecutive 
multistage emulsion polymerization method by which a polymer in an earlier 
stage is sequentially covered with a polymer in the next stage, among seed 
emulsion polymerization methods. It is preferable that when particles are 
generated in the polymerization, monomers, surface-active agents and water 
are added into the reaction system and then polymerization initiators are 
added thereto, for allowing emulsion polymerization reaction to start. 
The polymerization in the core layer is a reaction for forming the rubbery 
polymer. The monomers capable of forming the rubbery polymer include, for 
example, conjugated diene or alkyl acrylate having 2-8 carbons in the 
alkyl group or the mixture thereof. The conjugated dienes include, for 
example, butadiene, isoprene and chloroprene. The alkyl acrylates having 
2-8 carbons in the alkyl group include, for example, ethyl acrylate, 
propyl acrylate, butyl acrylate, cyclohexyl acrylate, 2-ethylhexyl 
acrylate and isononyl acrylate. Preferable among them may be butyl 
acrylate. 
For polymerization of the core layer, monomers copolymerizable with the 
alkylacrylate, e.g. aromatic vinyls or aromatic vinylidenes including 
styrene, vinyltoluene and .alpha.-methylstyrene; vinyl cyanides or 
vinylidene cyanides including acrylonitrile and methacrylonitrile; and 
alkyl methacrylates including methyl methacrylate and butyl methacrylate 
may also be copolymerized. Further, cross-linkable monomers including 
alkane polyol polyacrylates or alkane polyol polymethacrylates, such as 
ethylene glycol diacrylate, ethylene glycol dimethacrylate, butylene 
glycol diacrylate, hexanediol diacrylate, hexanediol dimethacrylate, 
oligoethylene glycol diacrylate, oligoethylene glycol dimethacrylate, 
trimethylolpropane triacrylate and trimethylolpropane trimethacrylate, and 
unsaturated carboxic acid allyl esters, such as allyl acrylate, allyl 
methacrylate, diallyl maleate, diallyl fumarate and diallyl itaconate, may 
be copolymerized. 
Further, when the active hydrogen group reactable to the isocyanate group 
is introduced into the core layer, monomers having the active hydrogen 
group reactable to the isocyanate group are copolymerized together with 
the monomers capable of forming the rubbery polymer. The active hydrogen 
groups reactable to the isocyanate groups include, for example, a carboxyl 
group, a hydroxyl group and an amino group, and preferable among them is 
the hydroxyl group. The monomers having the active hydrogen group 
reactable to the isocyanate group include acrylic acid, methacrylic acid, 
2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, polyethylene glycol 
acrylate, polyethylene glycol methacrylate, polypropylene glycol acrylate, 
polypropylene glycol methacrylate, N-methylol acrylamide, N-methylol 
methacrylamide, N-methylamino ethyl acrylate, N-methylamino ethyl 
methacrylate, N-tert-butylamino ethyl acrylate, N-tert-butylamino ethyl 
methacrylate, 2-hydroxypropyl acrylate and 2-hydroxypropyl methacrylate. 
Preferable among them are 2-hydroxyethyl methacrylate and 2-hydroxypropyl 
methacrylate. 
These monomers are polymerized to form the rubbery polymer. Preferably, the 
glass transition temperature (Tg) of the rubbery polymer is not more than 
20.degree. C. With the glass transition temperature Tg exceeding 
20.degree. C., sufficient adhesive strength may not be obtained in some 
instances. 
When two or more kinds of monomers are employed together, the Tg of the 
copolymerizate can be roughly determined from the following equation (1). 
EQU 1/Tgc=W.sub.1 /Tg.sub.1 +W.sub.2 /Tg.sub.2 +W.sub.3 /Tg.sub.3 +(1) 
Here, 
W.sub.1 represents a weight fraction of monomer 1 in the copolymer; 
W.sub.2 represents a weight fraction of monomer 2 in the copolymer; 
W.sub.3 represents a weight fraction of monomer 3 in the copolymer; 
Tgc is Tg expressed by absolute temperature (.degree.K) of the copolymer; 
Tg.sub.1 is Tg expressed by absolute temperature (.degree.K) of homopolymer 
of the monomer 1; 
Tg.sub.2 is Tg expressed by absolute temperature (.degree.K) of homopolymer 
of the monomer 2; and 
Tg.sub.3 is Tg expressed by absolute temperature (.degree.K) of homopolymer 
of the monomer 3. 
Known values of prior art documents, e.g. polyacrylic acid ethyl ester 249 
(.degree.K), polyacrylic acid butyl ester 233 (.degree.K), polyacrylic 
acid 2-ethylhexyl ester 213 (.degree.K), polystyrene 378 (.degree.K), 
polyvinyltoluene 409 (.degree.K), poly .alpha.-methylstyrene 441 
(.degree.K), polymethyl methacrylate 403 (.degree.K), polyacrylic acid 379 
(.degree.K), polymethacrylic acid 501 (.degree.K), poly 2-hydroxyethyl 
methacrylate 328 (.degree.K), are available for the homopolymer Tg. 
However, since there are no available known values for Tg of the 
homopolymer of the allyl methacrylate and also the crosslinked structure 
or the Tg depends on reaction conditions, calculations are made assuming 
the Tg to be 373 (.degree.K), for convenience's sake. 
The polymerization of the shell layer is a reaction for forming glassy 
polymer. The monomers capable of forming the glassy polymer include, for 
example, (i) vinyl polymerizable monomers including alkyl acrylates or 
alkyl methacrylates, such as methyl acrylate, methyl methacrylate, ethyl 
acrylate, ethyl methacrylate, butyl acrylate and butyl methacrylate; 
aromatic vinyls or aromatic vinylidenes, such as styrene, vinyltoluene and 
.alpha.-methylstyrene; and vinyl cyanides or vinylidene cyanides, such as 
acrylonitrile and methacrylonitrile, (ii) alkanpolyol polyacrylates or 
alkane polyol polymethacrylates including ethylene glycol diacrylate, 
ethylene glycol dimethacrylate, butylene glycol diacrylate, hexanediol 
diacrylate, hexanediol dimethacrylate, oligoethylene glycol diacrylate, 
oligoethylene glycol dimethacrylate, trimethylolpropane triacrylate and 
trimethylolpropane trimethacrylate and (iii) unsaturated carboxic acid 
allyl esters including allyl acrylate, allyl methacrylate, diallyl 
maleate, diallyl fumarate and diallyl itaconate. Preferable among them are 
methyl methacrylate and styrene. 
Further, when the active hydrogen group reactable to the isocyanate group 
is introduced into the shell layer, monomers having the active hydrogen 
group reactable to the isocyanate group are copolymerized together with 
the above-mentioned monomers capable of forming the glassy polymer. The 
active hydrogen groups reactable to the isocyanate groups include, for 
example, a carboxyl group, a hydroxyl group and an amino group, and 
preferable among them is the hydroxyl group. The monomers having the 
active hydrogen group reactable to the isocyanate group include acrylic 
acid, methacrylic acid, 2-hydroxyethyl acrylate, 2-hydroxyethyl 
methacrylate, polyethylene glycol acrylate, polyethylene glycol 
methacrylate, polypropylene glycol acrylate, polypropylene glycol 
methacrylate, N-methylol acrylamide, N-methylol methacrylamide, 
N-methylamino ethyl acrylate, N-methylamino ethyl methacrylate, 
N-tert-butylamino ethyl acrylate, N-tert-butylamino ethyl methacrylate, 
2-hydroxypropyl acrylate and 2-hydroxypropyl methacrylate. Preferable 
among them are 2-hydroxyethyl methacrylate and 2-hydroxypropyl 
methacrylate. 
These monomers are polymerized to form the glassy polymer. The reaction of 
the shell layer is performed by adding the monomers capable of forming the 
glassy polymer in the presence of the rubbery polymer particle emulsifying 
solution obtained by the above-mentioned reaction of the core. Preferably, 
the Tg of the glassy polymer is not less than 80.degree. C. With the Tg 
lower than 80.degree. C., reduction of water resistance may possibly 
occur. The Tg of the shell layer can be determined from the above equation 
(1). 
The core shell emulsion (b) thus obtained has the active hydrogen group 
reactable to the isocyanate group in the core layer and/or the shell 
layer. It is preferable that the core shell emulsion has the active 
hydrogen group reactable to the isocyanate group in the core layer. With 
the core shell emulsion having no active hydrogen group reactable to the 
isocyanate group in the core layer, sufficient adhesive strength may not 
be obtained in some instances. 
Preferably, the active hydrogen group reactable to the isocyanate group 
contained in the obtained core shell emulsion is contained in such a range 
that when the hydroxyl group is employed as the active hydrogen group 
reactable to the isocyanate group, for example, the hydroxyl value of a 
solid content of the core shell emulsion is in the range of between 
approximately 20 and approximately 110 (mgKOH/g). Desirably, a weight 
ratio of the rubbery polymer in the core layer to the glassy polymer in 
the shell layer is in the range between 20/80 and 90/10. Further, there is 
no specific limitation on a particle diameter of the obtained core shell 
emulsion, which is usually 50-1,000 nm, preferably, 100-700 nm. 
In the production of the core shell emulsion (b), almost all 
widely-employed surface active agents including anionic surface active 
agents including sodium dodecyl benzenesulfonate, sodium lauryl sulfate 
and sodium dioctylsulfosuccinate, and nonionic surface active agents 
including polyoxyethylene nonylphenyl ether and polyoxyethylene 
monostearate, may be employed. In addition, organic and inorganic or 
oil-soluble and water-soluble polymerization initiators including, for 
example, azobisisobutyronitrile, benzoil peroxide, t-butyl hydroperoxide, 
cumene hydroperoxide, hydrogen peroxide, sodium persulfate and ammonium 
persulfate may be employed. 
To modify molecular weights of the polymers, molecular weight modifiers 
including, for example, n-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl 
mercaptan, thioglycolic acid and 2-ethylhexyl thioglycolate, may also be 
employed in the polymerization. 
The modified polyisocyanate (a) and the core shell emulsion (b) thus 
obtained are mixed with the equivalent ratio (isocyanate group/active 
hydrogen group) of the isocianate group of the modified polyisocyanate (a) 
of 0.2-5, preferably 0.5-2.5, further preferably 1.0-2.0, per active 
hydrogen group of the core shell emulsion (b), to obtain the primer 
composition of the present invention. 
With the primer composition of the present invention, 0.1-400 parts by 
weight of water per 100 parts by weight of the mixture of the modified 
polyisocyanate (a) and the core shell emulsion (b) may be mixed according 
to its objects and uses. Further, known additives including silane 
coupling agents having no active hydrogen group reactable to the 
isocyanate; colorants; age resistors; plasticizing agents; and tackifiers 
may be mixed as required. 
The primer composition of the present invention thus obtained has an 
application life of the order of 8 hours so that it can be adequately 
employed in primer operations throughout the day, despite of its being a 
two-component system primer comprising the modified polyisocyanate (a) and 
the core shell emulsion (b). In addition, the primer composition of the 
present invention may be applied to an adherend surface by a common means 
e.g. spraying, brushing and the like, when applied to joints of building 
constructions and the like. 
The primer composition of the present invention, which is an aqueous primer 
requiring no organic solvent, is superior to conventional organic solvent 
base primers in terms of global environment, safety, hygiene and the like, 
while also can improve adhesive strength of an adhesive and an adherend 
and adhesive durability as well as or better than the conventional organic 
solvent-based primers. 
Besides, despite of its being a two-component system primer comprising the 
modified polyisocyanate (a) and the core shell emulsion (b), the primer 
composition of the present invention has such a long application life that 
it can be adequately employed in primer operations over a long time.

EXAMPLES 
Next, the present invention will be more clearly understood with reference 
to the following examples. It is to be noted that the number of parts and 
percent (%) used herein represent parts by weight and percent (%) by 
weight, respectively, unless otherwise specified. 
(Synthesis of Modified Polyisocyanate A) 
In a four neck flask equipped with a stirrer, a thermometer and a reflux 
condenser tube thereto, 100 parts of an isocyanurate group containing 
polyisocyanate containing an isocyanurate group using HDI as its base 
(TAKENATE D-170 HN (Trade name) available from Takeda Chemical Industries, 
Ltd.) was weighed, to which 12 parts of polyoxyethylene nonylphenyl ether 
(EMULGEN 920 (Trade name) available from Kao Corporation) and 3 parts of 
.gamma.-mercapto propyltrimethoxy silane (Y-11167 (Trade name) available 
from Nippon Unicar Company Limited) were added with stirring at 70.degree. 
C. Then, the mixture was heated at 80.degree. C. and stirred for 3 hours. 
After cooling to room temperature, substantially colorless, transparent, 
modified polyisocyanate A was obtained. The isocyanate group content of 
the modified polyisocyanate A was 18.6% and the viscosity thereof was 900 
mPa.multidot.s (at 23.degree. C.). 
(Synthesis of Modified Polyisocyanate B) 
Except that 9 parts of polyoxyethylene nonylphenyl ether and 3 parts of 
polyoxyethylene monomethyl ether (UNIOX M-550 (Trade name) available from 
NOF Corporation) were substituted for 12 parts of polyoxyethylene 
nonylphenyl ether in the synthesis of the modified polyisocyanate A, the 
same operations were performed to obtained the modified polyisocyanate B. 
The isocyanate group content of the modified polyisocyanate B was 18.5% 
and the viscosity thereof was 860 mPa.multidot.s (at 23.degree. C). 
(Synthesis of Modified Polyisocyanate C) 
Except that .gamma.-mercapto propyltrimethoxy silane was changed from 3 
parts to 27 parts in the synthesis of the modified polyisocyanate A, the 
same operations were performed to obtained the modified polyisocyanate C. 
The isocyanate group content of the modified polyisocyanate C was 11.6% 
and the viscosity thereof was 2,000 mPa.multidot.s (at 23.degree. C). 
(Synthesis of Modified Polyisocyanate D) 
Except that no .gamma.-mercapto propyltrimethoxy silane was used in the 
synthesis of the modified polyisocyanate A, the same operations were 
performed to obtained the modified polyisocyanate D. The isocyanate group 
content of the modified polyisocyanate D was 19.7% and the viscosity 
thereof was 540 mPa.multidot.s (at 23.degree. C.). 
(Synthesis of Modified Polyisocyanate E) 
Except that no .gamma.-mercapto propyltrimethoxy silane was used in the 
synthesis of the modified polyisocyanate B, the same operations were 
performed to obtained the modified polyisocyanate E. The isocyanate group 
content of the modified polyisocyanate E was 19.6% and the viscosity 
thereof was 490 mPa.multidot.s (at 23.degree. C.). 
(Synthesis of Modified Polyisocyanate F) 
Except that .gamma.-glycidoxy propyltrimethoxy silane (KBM403 (Trade name) 
available from Shin-Etsu Chemical Co., Ltd) having no active hydrogen 
group reactable to the isocyanate group was substituted for 
.gamma.-mercapto propyltrimethoxy silane in the synthesis of the modified 
polyisocyanate A, the same operations were performed to obtained the 
modified polyisocyanate F. The isocyanate group content of the modified 
polyisocyanate F was 19.2% and the viscosity thereof was 450 
mPa.multidot.s (at 23.degree. C.). 
(Production of Core Shell Emulsion a) 
In the following examples and comparative examples, abbreviations are used 
for the following terms: 
Ethyl acrylate . . . EA 
n-butyl acrylate . . . BA 
Methyl methacrylate . . . MMA 
Styrene . . . St 
2-hydroxyethyl methacrylate . . . HEMA 
Allyl methacrylate . . . ALMA 
t-dodecyl mercaptan . . . t-DMP 
Sodium dioctylsulfosuccinate (NEOCOL P (Trade name) available from Dai-Ichi 
Kogyo Seiyaku Co., Ltd) . . . NP 
Deionized water . . . DIW 
Sodium persulfate . . . SPS 
75.00 parts of DIW, 10.00 parts of an 1% aqueous NP solution and 5.00 parts 
of an 1% aqueous sodium bicarbonate solution were charged into a 
polymerization container with a reflux condenser and were stirred in a 
stream of nitrogen while the temperature was elevated to 70.degree. C. 
After 5 parts of BA were added and dispersed, 5.00 parts of a 2% aqueous 
SPS solution was added to initiate the seed polymerization. After stirring 
at 70.degree. C. for 30 minutes, 8.00 parts of the 2% aqueous SPS solution 
was added and then monomer emulsion for the core layer comprising the 
following composition was fed for 180 minutes. 
______________________________________ 
Monomer Emulsion For Core Layer 
______________________________________ 
BA 56.25 parts 
HEMA 18.68 parts 
t-DMP 0.08 parts 
1% aqueous NP solution 48.00 parts 
1% aqueous sodium bicarbonate solution 
8.00 parts 
DIW 8.00 parts 
______________________________________ 
After having been stirred at 80.degree. C. for 90 minutes, the mixture was 
cooled to 70.degree. C. Then, 2.00 parts of 2% aqueous SPS solution was 
added and then monomer emulsion for the shell layer comprising the 
following composition was fed for 60 minutes. 
______________________________________ 
Monomer Emulsion For Shell Layer 
______________________________________ 
MMA 18.00 parts 
EA 1.60 parts 
ALMA 0.40 parts 
1% aqueous NP solution 12.00 parts 
1% aqueous sodium bicarbonate solution 
2.00 parts 
DIW 6.00 parts 
______________________________________ 
After having been stirred at 80.degree. C. for 90 minutes, the mixture was 
cooled to room temperature to obtain the core shell emulsion a with a 
solid content of 35.0% and a hydroxyl value of a solid content of 79.6 
(mgKOH/g). A calculated value of Tg of the resin in the core layer is 
approximately -22.degree. C. and that in the shell layer is approximately 
110.degree. C. 
(Production of Core Shell Emulsion b) 
Except that the composition of the monomer emulsion for the core layer was 
changed as follows in the production of the core shell emulsion a, the 
same operations were performed to obtain the core shell emulsion b with a 
solid content of 35.0% and a hydroxyl value of a solid content of 79.6 
(mgKOH/g). A calculated value of Tg of the resin in the core layer is 
approximately -6.degree. C. and that in the shell layer is approximately 
110.degree. C. 
______________________________________ 
BA 45.00 parts 
St 11.25 parts 
HEMA 18.68 parts 
t-DMP 0.08 parts 
1% aqueous NP solution 48.00 parts 
1% aqueous sodium bicarbonate solution 
8.00 parts 
DIW 8.00 parts 
______________________________________ 
(Production of Core Shell Emulsion c) 
(Production of Core Shell Emulsion c) 
No reaction of the shell layer was performed in the production of the core 
shell emulsion a to obtain the core shell emulsion c with a solid content 
of 33.3% and a hydroxyl value of a solid content of 99.4 (mgKOH/g). A 
calculated value of Tg of the resin is approximately -22.degree. C. 
(Production of Core Shell Emulsion d) 
Except that the composition of the monomer emulsion in the shell layer was 
changed as follows in the production of the core shell emulsion a, the 
same operations were performed to obtain the core shell emulsion d with a 
solid content of 35.0% and a hydroxyl value of a solid content of 79.6 
(mgKOH/g). A calculated value of Tg of the resin in the core layer is 
approximately -22.degree. C. and that in the shell layer is approximately 
70.degree. C. 
______________________________________ 
MMA 14.00 parts 
EA 5.60 parts 
ALMA 0.40 parts 
1% aqueous NP solution 12.00 parts 
1% aqueous sodium bicarbonate solution 
2.00 parts 
DIW 6.00 parts 
______________________________________ 
(Production of Core Shell Emulsion e) 
(Production of Core Shell Emulsion e) 
Except that the composition of the monomer emulsion for the core layer, the 
composition of the monomer emulsion for the shell layer and the addition of 
2% aqueous SPS solution were changed as follows in the production of the 
core shell emulsion a, the same operations were performed to obtain the 
core shell emulsion e having hydroxyl group in the shell layer only with a 
solid content of 35.0% and a hydroxyl value of a solid content of 79.6 
(mgKOH/g). A calculated value of Tg of the resin in the core layer is 
approximately -40.degree. C. and that in the shell layer is approximately 
98.degree. C. 
______________________________________ 
Monomer Emulsion For Core Layer 
BA 24.98 parts 
t-DMP 0.03 parts 
1% aqueous NP solution 18.00 parts 
1% aqueous sodium bicarbonate solution 
3.00 parts 
DIW 3.00 parts 
Monomer Emulsion For Shell Layer 
MMA 47.12 parts 
EA 2.80 parts 
HEMA 18.68 parts 
ALMA 1.40 parts 
1% aqueous NP solution 42.00 parts 
1% aqueous sodium bicarbonate solution 
7.00 parts 
DIW 11.00 parts 
2% aqueous SPS solution for core layer 
3.00 parts 
1% aqueous SPS solution for shell layer 
7.00 parts 
______________________________________ 
(Production of Core Shell Emulsion f) 
(Production of Core Shell Emulsion f) 
Except that the composition of the monomer emulsion for the core layer was 
changed as follows in the production of the core shell emulsion a, the 
same operations were performed to obtain the core shell emulsion f with a 
solid content of 35.0% and a hydroxyl value of a solid content of 79.6 
(mgKOH/g). A calculated value of Tg of the resin in the core layer is 
approximately 25.degree. C. and that in the shell layer is approximately 
110.degree. C. 
______________________________________ 
BA 27.75 parts 
St 28.50 parts 
HEMA 18.68 parts 
t-DMP 0.08 parts 
1% aqueous NP solution 48.00 parts 
1% aqueous sodium bicarbonate solution 
8.00 parts 
DIW 8.00 parts 
______________________________________ 
Example 1 
56 parts of DIW was added to 100 parts of the core shell emulsion a with 
stirring, and 17 parts of the modified polyisocyanate A was added to the 
obtained mixture with mixing, to obtain a primer composition of the 
present invention. The equivalent ratio of the isocyanate group relative 
to the hydroxyl group (isocyanate group/hydroxyl group) is 1.5. 
Example 2 
56 parts of DIW was added to 100 parts of the core shell emulsion a with 
stirring, and 17 parts of the modified polyisocyanate B was added to the 
obtained mixture with mixing, to obtain a primer composition of the 
present invention. The equivalent ratio of the isocyanate group relative 
to the hydroxyl group (isocyanate group/hydroxyl group) is 1.5. 
Example 3 
Except that the core shell emulsion b was substituted for the core shell 
emulsion a, the same operations as those in Example 1 were performed to 
obtain a primer composition of the present invention. The equivalent ratio 
of the isocyanate group relative to the hydroxyl group (isocyanate 
group/hydroxyl group) is 1.5. 
Example 4 
Except that the core shell emulsion b was substituted for the core shell 
emulsion a, the same operations as those in Example 2 were performed to 
obtain a primer composition of the present invention. The equivalent ratio 
of the isocyanate group relative to the hydroxyl group (isocyanate 
group/hydroxyl group) is 1.5. 
Example 5 
81 parts of DIW was added to 100 parts of the core shell emulsion a with 
stirring, and 28 parts of the modified polyisocyanate C was added to the 
obtained mixture with mixing, to obtain a primer composition of the 
present invention. The equivalent ratio of the isocyanate group relative 
to the hydroxyl group (isocyanate group/hydroxyl group) is 1.5. 
Example 6 
Except that the modified polyisocyanate A was changed from 17 parts to 12 
parts and the DIW was changed from 56 parts to 45 parts, the same 
operations as those in Example 1 were performed to obtain a primer 
composition of the present invention. The equivalent ratio of the 
isocyanate group relative to the hydroxyl group (isocyanate group/hydroxyl 
group) is 1.1. 
Example 7 
Except that the modified polyisocyanate A was changed from 17 parts to 22 
parts and the DIW was changed from 56 parts to 68 parts, the same 
operations as those in Example 3 were performed to obtain a primer 
composition of the present invention. The equivalent ratio of the 
isocyanate group relative to the hydroxyl group (isocyanate group/hydroxyl 
group) is 2.0. 
Example 8 
Except that the core shell emulsion d was substituted for the core shell 
emulsion a, the same operations as those in Example 1 were performed to 
obtain a primer composition of the present invention. The equivalent ratio 
of the isocyanate group relative to the hydroxyl group (isocyanate 
group/hydroxyl group) is 1.5. 
Example 9 
Except that the core shell emulsion e was substituted for the core shell 
emulsion a, the same operations as those in Example 1 were performed to 
obtain a primer composition of the present invention. The equivalent ratio 
of the isocyanate group relative to the hydroxyl group (isocyanate 
group/hydroxyl group) is 1.5. 
Example 10 
Except that the core shell emulsion f was substituted for the core shell 
emulsion a, the same operations as those in Example 1 were performed to 
obtain a primer composition of the present invention. The equivalent ratio 
of the isocyanate group relative to the hydroxyl group (isocyanate 
group/hydroxyl group) is 1.5. 
Comparative Example 1 
54 parts of DIW was added to 100 parts of the core shell emulsion a with 
stirring, and 16 parts of the modified polyisocyanate D was added to the 
obtained mixture with mixing, to obtain a primer composition. The 
equivalent ratio of the isocyanate group relative to the hydroxyl group 
(isocyanate group/hydroxyl group) is 1.5. 
Comparative Example 2 
Except that the modified polyisocyanate E was substituted for the modified 
polyisocyanate D, the same operations as those in Comparative Example 1 
were performed to obtain a primer composition. The equivalent ratio of the 
isocyanate group relative to the hydroxyl group (isocyanate group/hydroxyl 
group) is 1.5. 
Comparative Example 3 
Except that the modified polyisocyanate F was substituted for the modified 
polyisocyanate D, the same operations as those in Comparative Example 1 
were performed to obtain a primer composition. The equivalent ratio of the 
isocyanate group relative to the hydroxyl group (isocyanate group/hydroxyl 
group) is 1.5. 
Comparative Example 4 
58 parts of DIW was added to 100 parts of the core shell emulsion c with 
stirring, and 20 parts of the modified polyisocyanate A was added to the 
obtained mixture with mixing, to obtain a primer composition. The 
equivalent ratio of the isocyanate group relative to the hydroxyl group 
(isocyanate group/hydroxyl group) is 1.5. 
(Evaluation of the Primer Compositions) 
The primer compositions in Examples and Comparative Examples thus obtained 
were evaluated by measuring the sealant for building constructions applied 
to Examples and Comparative Examples on their adhesive strengths 
immediately after initial cure and after immersion in hot water. The tests 
were performed in the following way, using mortar boards, siding boards 
(MOENSIDING W (Trade name) available from Nichiha Co, Ltd) and ALC boards 
(POWER BOARD (Trade name) available from Asahi Chemical Construction 
Materials Co., Ltd.) as the adherend and using a modified silicone base 
one-component type sealant and a polyurethane base one-component type 
sealant as the sealant for building constructions. 
(1) Adhesive Bonding of Adherent with Modified Silicone Base One-Component 
Type Sealant 
The primer compositions obtained in the above-mentioned Examples and 
Comparative Examples were brushed double on surfaces of mortar boards and 
siding boards conformable with JIS (Japanese Industrial Standard) R5201. 
After air-drying for 1 hour, the boards were filled with the modified 
silicone base one-component type sealant in conformation with JIS A5758 
and were subjected to an initial cure. The adhesive members thus produced 
were used as test pieces for tensile adhesive strength. The initial cure 
was performed under the conditions of at 25.degree. C. and for 14 days. 
(2) Adhesive Bonding of Adherent with Polyurethane Base One-component Type 
Sealant 
The primer compositions obtained in Examples 1-4 were brushed double on 
surfaces of ALC boards conformable with JIS R5201. After air-drying for 1 
hour, the boards were filled with the polyurethane base one-component type 
sealant in conformation with JIS A5758 and were subjected to an initial 
cure. The bonding members thus produced were used as test pieces for 
tensile adhesive strength. The initial cure was performed under the 
conditions of at 25.degree. C. and for 28 days. 
Adhesive Strength and Adhesive Durability (Water resistance) Tests 
The test pieces were measured on their adhesive strength (kgf/cm.sup.2) and 
elongation (%) immediately after initial cure and after immersion in hot 
water of 50.degree. C. for 7 days, respectively. The test results are 
shown in TABLES 1 and 2, along with test results obtained when 
commercially available organic solvent base primer compositions 
(polyisocyanate base) were applied, for reference purposes. 
TABLE 1 
__________________________________________________________________________ 
Example Ex. 1 
Ex. 2 
Ex. 3 
Ex. 4 
Ex. 5 
Ex. 6 
Ex. 7 
Ex. 8 
__________________________________________________________________________ 
Modified Polyisocyanate A B A B C A A A 
Emulsion a a b b a a b d 
Equivalence Ratio (NCO group/OH group) 
1.5 
1.5 
1.5 
1.5 
1.5 
1.1 
2.0 
1.5 
Adhesive (1) 
Immediatety 
Strength (kgf/cm.sup.2) 
4.1 
4.0 
4.0 
3.8 
4.0 
3.9 
3.7 
3.4 
Adherent: 
After Cure 
Elongation (%) 
745 
727 
703 
683 
663 
665 
643 
387 
Mortar Board 
Sealant After Immersion 
Strength (kgf/cm.sup.2) 
2.5 
2.5 
2.4 
2.4 
2.5 
2.4 
2.3 
1.2 
Modified Silicone 
In Hot Water 
Elongation (%) 
605 
593 
580 
578 
574 
580 
558 
355 
Base Sealant 
Adhesive (1) 
Immediatety 
Strength (kgf/cm.sup.2) 
5.1 
5.2 
5.0 
4.9 
4.8 
4.9 
4.7 
3.7 
Adherent: 
After Cure 
Elongation (%) 
592 
612 
567 
545 
561 
533 
519 
344 
Siding Board 
Sealant After immersion 
Strength (kg/cm.sup.2) 
2.0 
2.1 
2.2 
2.0 
2.1 
2.0 
1.9 
1.6 
Modified Silicone 
In Hot Water 
Elongation (%) 
661 
680 
659 
624 
685 
631 
608 
420 
Base Sealant 
Adhesive (2) 
Immediatety 
Strength (kgf/cm.sup.2) 
4.9 
5.7 
4.5 
4.6 
-- -- -- -- 
Adherent: 
After Cure 
Elongation (%) 
569 
678 
607 
640 
-- -- -- -- 
ALC Board 
Sealant: 
After Immersion 
Strength (kgf/cm.sup.2) 
2.5 
2.7 
2.0 
2.1 
-- -- -- -- 
Urethane Base 
ln Hot Water 
Elongation (%) 
458 
521 
541 
546 
-- -- -- -- 
Sealant 
__________________________________________________________________________ 
TABLE 2 
__________________________________________________________________________ 
Example, Comparative Example and 
Ex. 
Com. 
Com. 
Com. 
Com. 
Reference 
Reference Example Ex. 9 
10 Ex. 1 
Ex. 2 
Ex. 3 
Ex. 4 
Example 
__________________________________________________________________________ 
Modified Polyisocyanate A A D E F A Organic 
solvent 
Emulsion e f a a a c base primer 
Equivalence Ratio (NCO group/OH group) 
1.5 
1.5 
1.5 
1.5 
1.5 
1.5 
compositions 
(polyisocyanate 
base) 
Adhesive (1) 
Immediately 
Strength (kgf/cm.sup.2) 
4.1 
3.3 
4.1 
4.0 
4.0 
2.9 
3.8 
Adherent: 
After Cure 
Elongation (%) 
551 
366 
588 
594 
570 
279 
537 
Mortar Board 
Sealant: 
After Immersion 
Strength (kgf/cm.sup.2) 
1.4 
1.1 
1.0 
0.9 
1.1 
0.4 
2.0 
Modified Silicone 
In Hot Water 
Elongation (%) 
390 
331 
206 
178 
218 
47 580 
Base Sealant 
Adhesive (1) 
Immediately 
Strength (kgf/cm.sup.2) 
4.0 
3.5 
4.0 
3.9 
4.i 
3.2 
4.5 
Adherent: 
After Cure 
Elongation (%) 
476 
329 
442 
401 
395 
311 
501 
Siding Board 
Sealant: 
After Immersion 
Strength (kgf/cm.sup.2) 
1.6 
1.4 
0.9 
0.8 
0.4 
0.7 
1.7 
Modified Silicone 
In Hot Water 
Elongation (%) 
424 
402 
165 
131 
28 122 
554 
Base Sealant 
Adhesive (2) 
Immediately 
Strength (kg/cm.sup.2) 
-- -- -- -- -- -- -- 
Adherent: 
After Cure 
Elongation (%) 
-- 
ALC Board 
Sealant: 
After Immersion 
Strength (kgf/cm.sup.2) 
-- -- -- -- -- -- -- 
Urethane Base 
In Hot Water 
Elongation (%) 
-- 
Sealant 
__________________________________________________________________________ 
It is understood from TABLES 1 and 2 that the primer compositions in 
Examples 1-10 have favorable adhesive properties immediately after the 
initial cure and after immersion in hot water, as compared with 
Comparative Examples 1-4. 
Further, it is understood that Examples 1-7 each using the core shell 
emulsion which has the active hydrogen group in the core layer and in 
which Tg of the rubbery polymer of the core layer is not more than 
20.degree. C. and Tg of the glassy polymer layer of the shell layer is not 
less than 80.degree. C. have favorable adhesive properties, as compared 
with Example 9 using the core shell polymer e having the active hydrogen 
group in the shell layer, Example 10 using the core shell polymer f in 
which the Tg of the rubbery polymer of the core layer is more than 
20.degree. C. and Example 8 using the core shell polymer d in which the Tg 
of the glassy polymer of the shell layer is less than 80.degree. C.