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Description  |
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BACKGROUND OF THE INVENTION
This invention relates to a primer composition, more specifically to a
primer composition which permits providing extremely good adhesion
properties between the primer composition and each of a glass plate and an
adhesive by previously applying the primer composition to the glass plate,
when joining the glass plates is carried out with the adhesive.
Heretofore, as the primers used in causing the glasses to adhere to each
other, there are known, for example, organic silicon compounds, i.e.
silane coupling agents and their mixtures, which have carbon functional
groups such as vinyl groups, amino groups, glycidoxy groups, methacyloxy
groups and mercapto groups and in which silicon functional groups such as
alkoxy groups, alkoxy-alkoxy groups and acetoxy groups are directly bonded
to silicon atoms (e.g., Japanese Provisional Patent Publication No.
65232/1973). Although being excellent in the adhesion properties to the
glass, these silane coupling agents are insufficient in an affinity for
adhesive layers, depending upon kinds of adhesives. Therefore, they have
the problems that a peel-off phenomenon occurs at the interfacial layer
between the adhesive layer and the primer layer.
Further, another kind of primer is extensively known in which an epoxy
resin and an amino group-containing alkoxysilane are employed together.
However, such a primer has the drawback that it can not provide a
sufficient adhesive strength, depending upon certain kinds of adhesives.
Furthermore, Japanese Provisional Patent Publication No. 120626/1983
discloses an active energy ray curing composition a film of which is
formed on the surface of a substrate by the irradiation of active energy
rays such as ultraviolet rays, a main component of the composition being
an urethane polyacrylate obtained by the reaction of a hydroxyl
group-containing epoxy compound which contains an aromatic hydrocarbon
group and an ether bond or contains an aromatic, an alicyclic or an
aliphatic hydrocarbon group and an ester bond in its molecular and which
has a hydroxyl group as a side chain and an epoxy ring at a chain end; a
polyisocyanate; and a hydroxyl group-containing (meth)acrylate. Such a
composition just mentioned has the advantage that a treatment can be
carried out in the absence of any solvent, but the adhesion of this
composition to the substrate is not satisfactory, since it is dependent
upon an amount of unreacted epoxy groups. Particularly, such a composition
has the fault that its heat-resistant adhesion to the glass plate is poor.
SUMMARY OF THE INVENTION
Accordingly, an object of this invention is to provide a primer composition
by which the above-mentioned problems are overcome and an excellent
adhesion is established between the primer composition and each of the
glass plate and the adhesive, when it is used in manufacturing glass-glass
laminates or glass-polycarbonate laminates.
The inventors of this invention have intensively conducted researches into
primer composition which are pretreatment agents for glasses used in
preparing the glass-glass laminates or the glass-polycarbonate laminates
by the use of a variety of adhesives, with the aim of improving the
affinity of primer layers for adhesive layers. As a result, it has been
found that on using a composition in which an epoxyurethane (meth)acrylate
is blended with an amino group-containing alkoxysilane or its partially
hydrolyzed condensate, (meth)acrylic double bonds present in the primer
composition are reacted with double bonds present in the used adhesive,
when the adhesive is cured by a low-temperature heating, ultraviolet rays
or the like, so that a good adhesion can be obtained, and thus this
invention has now been achieved.
That is to say, the primer composition of this invention is characterized
by comprising
[A] a reaction product of:
(1) a hydroxyl group-containing organic compound composed of;
(a) an epoxy group-containing alcohol represented by the general formula
[I]:
##STR2##
wherein, R.sup.1 is a hydrocarbon group having 1 to 15 carbon atoms, or
an organic group in which the same or different hydrocarbon groups are
bonded to each other by an ether bond or an ester bond; and each of m and
n is a value of 1 or more; and
(b) a hydroxyl group-containing (meth)acrylate represented by the formula
[II]:
(CH.sub.2 =CR.sup.2 COO).sub.a R.sup.3 [II]
wherein R.sup.2 is a hydrogen atom or a methyl group; R.sup.3 is a
substituted or unsubstituted hydrocarbon group, or a group in which the
same or different hydrocarbon groups are bonded to each other by ether
bond or the ester bond, the R.sup.3 being a-valent and having at least one
hydroxyl group; and a is an integer of 1 to 3;
an amount of active hydrogen atoms included in the aforesaid (a) being 25
to 75% with respect to the total amount of active hydrogen atoms included
in the aforesaid (1); and
(2) a polyisocyanate including 70 to 100% of the theoretical amount of
isocyanato groups which will react with the total amount of the active
hydrogen atoms included in the aforesaid (1);
[B] an amino group-containing alkoxysilane or its partially hydrolyzed
condensate having 0.5 to 1.5 amino active hydrogen atoms per epoxy group
included in the aforesaid (1)(a); and
[C] a diluent.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the following, this invention will be further described in detail.
The epoxy group-containing alcohol (1)(a) serves to give the epoxy groups
to the reaction product [A] and to thereby provide the composition with
excellent adhesion properties to both the glass plate and the adhesive
layer. In the general formula [I], R.sup.1 represents a hydrocarbon group
having 1 to 15 carbon atoms or an organic group in which the hydrocarbon
groups are bonded to each other by an ether bond or an ester bond. Such
hydrocarbon groups may be aromatic or aliphatic, and their examples
include a hydroxyethyl group, a 2,3-dihydroxypropyl group, a
2,2-dimethylolbutyl group, a trimethylolethyl group, a
2-ethyl-2-methylolpropylene group, a 2,2-dimethylolpropylene group, a
diglycerol group, a sorbitol group, and groups represented by the
following formulae:
##STR3##
Further, in the formula, each of m and n is an integer of 1 or more.
Examples of such epoxy group-containing alcohols include, in addition to
glycidol, ethylene glycol monoglycidyl ether, glycerin monoglycidyl ether,
glycerin diglycidyl ether, trimethylolpropane monoglycidyl ether,
trimethylolpropane diglycidyl ether, pentaerythritol monoglycidyl ether,
pentaerythritol diglycidyl ether, pentaerythritol triglycidyl ether,
diglycerol monoglycidyl ether, diglycerol diglycidyl ether, diglycerol
triglycidyl ether, sorbitol triglycidyl ether, sorbitol tetraglycidyl
ether, bisphenol A-diglycidyl ether-modified monoacrylate and compounds
represented by the following formula:
##STR4##
of the recited alcohols, those in which (a) is a glycidol or R.sup.1 is an
aliphatic hydrocarbon group are preferred, if it is desired that a cured
primer film is elastic.
The hydroxyl group-containing (meth)acrylate (1)(b) is the component which
react with the polyisocyanate of (2) in order to provide the primer
composition with a property of curing by heating at a relatively low
temperature or a light irradiation. R.sup.3 in the general formula [II]
represents an a-valent group having at least one hydroxyl group. This
a-valent group is a substituted or unsubstituted hydrocarbon group having
at least one hydroxyl group, or a group, having at least one hydroxyl
group, in which the same or different hydrocarbon groups are bonded to
each other by an ether bond or an ester bond. Examples of the R.sup.3
include hydroxy group-containing hydrocarbon groups such as a hydroxyethyl
group, a hydroxypropyl group, a glycerol group and a tetramethylolmethyne
group; hydroxy group-containing hydrocarbon groups containing ether bond
such as a hydroxybutoxypropoxy group and a hydroxyphenyloxypropoxy group;
and hydroxy group-containing hydrocarbon groups containing ester bond such
as a hydroxy-(meth)acryloyloxy group. These hydrocarbon groups may be
substituted by halogen atoms or the like. If it is desired to provide the
primer with physical properties, especially, elasticity after curing, the
valence a is required to be within the range of 1 to 3. Examples of the
hydroxyl group-containing (meth)acrylates include 2-hydroxyethyl acrylate,
2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate,
2-hydroxy-3-chloropropyl acrylate, 2-hydroxy-3-butoxypropyl acrylate,
2-hydroxy-3-(meth)acryloyloxypropyl acrylate, 2-hydroxy-3-phenyloxy
acrylate, 1,4-butylene glycol monoacrylate, glycerin monoacrylate,
glycerin diacrylate, trimethylolpropane diacrylate, tetramethylolmethane
triacrylate, triethylene glycol monoacrylate, polypropylene glycol
monoacrylate and polycaprolactone glycol monoacrylate, and methacrylates
corresponding to these acrylates.
The hydroxyl group-containing organic compound (1) is composed of (a) and
(b). A formulating proportion of (a) and (b) is such that an amount of the
active hydrogen atoms of (a) is within the range of 25 to 75% with respect
to the total amount of the active hydrogen atoms which are included in (1)
and will react with the isocyanate of (2). When the formulating amount of
(a) is less than 25%, any sufficient adhesive strength will not be
obtained. On the other hand, when it is more than 75%, any satisfactory
curing state will not be obtained in the case that the curing is carried
out by heating at a relatively low temperature or the irradiation of
ultraviolet rays.
The polyisocyanate (2) can react with the hydroxyl groups of the
above-mentioned (1)(a) and (b) in order to form an urethane acrylate
oligomer [A] which is one of the main components of the primer
composition. By way of such polyisocyanates, polyisocyanates used in usual
urethanating reactions can be employed, but when an especially excellent
light stability is required, it is preferred to employ a so-called
non-yellowing type polyisocyanate. Examples of these polyisocyanates
include tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene
diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate,
hexamethylene diisocyanate, trimethylhexamethylene diisocyanate,
isophorone diisocyanate, methylene-bis(4-cyclohexyl isocyanate),
##STR5##
They may be employed alone or in any combination of two or more thereof.
A formulating proportion of (2) is such that the amount of the isocyanate
groups included in the polyisocyanate is within the range of 70 to 100%,
preferably 80 to 100% of a theoretical amount of the isocyanate groups
which react with the total amount of the active hydrogen atoms included in
(1)(a) and (b). When the amount of the isocyanate groups is less than 70%
of the above-mentioned theoretical amount, the unreacted hydroxyl
group-containing organic compound which has no reactivity with the
adhesive will be great in amount, so that the adhesive strength of the
primer composition to the glass plate or the adhesive will be
deteriorated. On the other hand, when it is more than 100% of the
theoretical amount, the excessive isocyanate groups will remain and will
bring about a reaction with the amino groups of (b) which should react
with epoxy groups, with the result that the adhesive strength will be
lowered and a stability of the primer composition will be reduced during a
storage period.
The above-mentioned component [A] can be prepared, for example, by adding
dropwise (1)(a) and (b) separately or previously mixed (1)(a) and (b) to
(2), or treating them in a temporary preparation manner, with stirring,
but the way of adding dropwise (1)(a) and (b) separately is preferred,
since the primer obtained in such a way will be excellent in the adhesive
strength. The reaction for the manufacture of the component [A] can
progress even at ambient temperature, but it is preferred to heat the
materials up to 40.degree. to 80.degree. C. at the reaction. In this case,
a reaction catalyst such as dibutyltin difatty acid salt and a
polymerization inhibitor such as 2,4-di-tertbutyl-4-hydroxytoluene may be
added thereto, if desired. Further, at the above-mentioned reaction, the
diluent (C) not having active hydrogen atoms may be added thereto. After
the completion of the dropwise addition, the stirring is further continued
to bring the reaction to an end. The reaction time depends upon a kind of
polyisocyanate but is preferably in the range of 1 to 30 hours. Moreover,
in the case that the reaction catalyst is used, its amount depends upon a
kind of polyisocyanate but is preferably in the range of 0 to 10% by
weight, more preferably in the range of 0.001 to 2% by weight based on the
total amount of component [A].
The amino group-containing alkoxysilane or its partially hydrolyzed
condensate of [B] reacts with the epoxy groups of [A] in order to
introduce a silicon-functionality into the primer composition and to
thereby improve the adhesion to the glass plate. Examples of such amino
group-containing alkoxysilanes or their partially hydrolyzed condensates
include .gamma.-aminopropyltrimethoxysilane,
.gamma.-aminopropyltriethoxysilane,
N-(.beta.-aminoethyl)-.gamma.-aminopropyltrimethoxysilane,
N-(.beta.-aminoethyl)-.gamma.-aminopropylmethyldimethoxysilane,
.gamma.-anilinopropyltrimethoxysilane and their partially hydrolyzed
condensates, but they are not limited. Of these compounds, the amino
group-containing alkoxysilanes, particularly
N-(.beta.-aminoethyl)-.gamma.-aminopropyltrimethoxysilane is preferred,
since a good adhesion to the glass plate and the adhesive is obtained
thereby.
A formulating amount of [B] is such that the number of amino active
hydrogen atoms included in [B] is 0.5 to 1.5, preferably, 0.8 to 1.2 per
epoxy group included in (1)(a). When the number of the amino active
hydrogen atoms is less than 0.5, a good adhesion to the glass plate and
the adhesive can not be obtained; when the number is more than 1.5, its
excess will be in vain, because the adhesion to the glass plate and the
adhesive will not be improved in proportion to the number of the added
amino active hydrogen atoms.
The primer composition of this invention is substantially composed of
components [A] and [B], but for the purpose of lowering a viscosity of the
composition to facilitate its application work, the diluent of [C] is
further added thereto. Such a diluent may be a reactive material having
functional groups which will bring about a reaction with the
above-mentioned component [A] or [B], or a material having no functional
groups. Examples of the diluents of having no functional groups include
organic solvents, i.e., aromatic hydrocarbons such as toluene and xylene;
alcohols such as methanol, ethanol, isopropanol and butanol; alcohol
ethers such as ethylene glycol monomethyl ether and ethylene glycol
monoethyl ether as well as their acetic esters; ethers such as diethyl
ether and tetrahydrofuran; esters such as ethyl acetate, propyl acetate
and butyl acetate; ketones such as acetone, methyl ethyl ketone, methyl
isobutyl ketone, cyclohexanone and isophorone; chlorinated hydrocarbons
such as trichloroethylene, tetrachloroethylene and 1,1,1-trichloroethane;
and polar solvents such as dimethylformamide and dimethylsulfoxide. They
may be used alone or in the form of a mixture thereof. Further, examples
of the reactive diluents include acrylates such as the hydroxyl
group-containing (meth)acrylates usable as (1)(b), 2-ethylhexyl acrylate,
propylene glycol diacrylate, butylene glycol diacrylate, 1,4-butanediol
diacrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate,
butoxyethylene glycol acrylate, tetrahydrofurfuryl acrylate, cyclohexyl
acrylate, benzyl acrylate, ethylcarbitol acrylate, butoxyethyl acrylate,
butoxydiethylene glycol monoacrylate and glycidyl acrylate; methacrylates
corresponding to the above-mentioned acrylates; (meth)acrylic compounds
having no hydroxyl groups such as (meth)acrylate oligomers; and vinyl
compounds such as N-vinyl-2-pyrrolidone.
In the case that the diluent having the functional groups capable of
reacting with the isocyanate groups is used in this invention, the diluent
is to be added after the synthesis of the component [A]. When the used
diluent has no functional groups which can react with the isocyanate
groups, it may be added at or after the synthesis of the component [A].
The component [C] is blended with the primer composition in such an amount
that it leads to such a viscosity as to make the application work
possible.
In order to facilitate the application work, the primer composition of this
invention has a viscosity of, preferably, 10,000 cP or less, more
preferably, 1,000 cP or less at 25.degree. C. When the viscosity is in
excess of 10,000 cP, it will be difficult to apply it on a substrate in a
thin state.
For the sake of the improvement in weathering resistance, the primer
composition of this invention may further include a known ultraviolet-ray
absorber, antioxidant, age resister and/or the like.
The primer composition of this invention has hydroxyl groups, alkoxysilyl
groups and acryloyl groups as functional groups, and either the epoxy
groups included in (1)(a) or the amino groups included in [B] further
remain in the primer composition in compliance with a molar ratio of their
groups. Thus, to begin with, the primer composition of this invention
carries out curing at a first step in the range of ambient temperature to
150.degree. C. after its application on the glass plate, and the
above-mentioned functional groups except the acryloyl groups
simultaneously act on silanol groups on the surface of the glass plate in
order to form a primer layer thereon which is excellent in an adhesive
strength and is strong. The adhesive including a polymerization initiator
and having double bonds is then filled or applied thereonto in order to
allow the acryloyl groups in the primer to react with the double bonds of
the adhesive, so that the curing of the primer at a second step is carried
out together with the curing of the adhesive. At this time, in order to
carry out the curing of the primer at a relatively low temperature for a
short period of time, and for the purpose of obtaining an excellent
adhesive strength, it is preferred to previously add the polymerization
initiator to the primer composition. As the polymerization initiator, a
thermal polymerization initiator and a photopolymerization initiator may
be used. Particularly, in the case that the material to be applied and the
adhesive must not be heated, or in the case that the curing should be
accomplished in a short time, it is preferred that the photopolymerization
initiator is employed and the curing is achieved by the irradiation of
ultraviolet rays. Examples of the photopolymerization initiators include
benzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone,
acetophenone, benzoin, benzoin ethyl ether, benzoin n-propyl ether,
benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether,
benzyl, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropane-1-one,
2-hydroxy-2-methyl-1-phenylpropane-1-one, benzyl sulfide, thioxanthone and
2-chlorothioxanthone.
The primer composition of this invention is first applied to the glass
plate by means of, e.g., brushing or immersion and is then allowed to
stand at ambient temperature or heated at a relatively low temperature in
order to accomplish curing and to thereby form a primer layer thereon.
Next, any of acrylic adhesives, epoxy adhesives, urethane adhesives and
other various organic adhesives having double bonds is applied thereto or
filled and is then cured by heating, ultraviolet rays irradiation or
electron beams irradiation to prepare a laminated product excellent in the
adhesion to the glass and the adhesive.
The reason why the excellent adhesive strength can be obtained by using the
primer composition of this invention is that hydroxyl groups produced by
the reaction of the epoxy groups of the epoxy urethane (meth)acrylate in
the composition of this invention with the amino groups of the amino
group-containing alkoxysilane or its partially hydrolyzed condensate and
alkoxysilyl groups of the said silane act on silanol groups on the surface
of the glass plate in order to provide a strong adhesive strength between
the primer layer and the glass plate, and groups having unsaturated double
bonds react with groups having unsaturated double bonds of the adhesive in
order to further provide an excellent adhesive strength between the primer
layer and the adhesive layer.
The primer composition of this invention which is constituted as mentioned
above is utilized as a primer when laminates are manufactured by applying
the organic adhesive to the glass plates, and at this time, an excellent
adhesion is given to both the glass plates and the adhesive. Further, the
cured film thus obtained is more elastic than a cured film of a
conventional epoxy resin primer, therefore it can sufficiently withstand
shocks from the outside.
The present invention is illustrated by referring to the following
Examples, in which parts represent all parts by weight.
EXAMPLE 1
In a reaction vessel, 388 parts of hydrogenated xylylenediisocyanate and
0.83 part of 2,6-di-tert-butyl-4-hydroxytoluene were placed, and they were
heated up to 85.degree. C. with stirring. To the resulting solution, there
was added dropwise over 2 hours a mixture in which 0.42 part of dibutyltin
dilaurate and 444 parts of 2-hydroxy-3-phenyloxypropyl acrylate were
homogeneously dissolved. Next, a temperature of the mixture was raised up
to 70.degree. C., and 4 hours' heating and stirring were carried out in
order to prepare an urethane acrylate intermediate having
2.40.times.10.sup.-3 mole/g of unreacted isocyanato groups. While the
temperature was maintained at 70.degree. C., 738 parts of
trimethylolpropane diglycidyl ether were further added thereto, and
heating and stirring were then continued for 18 hours to obtain a reaction
product in which a reaction ratio of the isocyanato groups was 98% or
more.
After diluted 300 parts of thus obtained reaction product with 700 parts of
isopropyl alcohol, to the mixture were added 9 parts of
1-(4-isopropylphenyl)-2-hydroxy-2-methylpropane-1-one and 101 parts of
N-(.beta.-aminoethyl)-.gamma.-aminopropyltrimethoxysilane. Then, they were
uniformly mixed to prepare a primer composition A.
EXAMPLE 2
In a reaction vessel were placed, in the following order, a polyisocyanate,
a polymerization inhibitor, a hydroxyl group-containing (meth)acrylate, a
reaction catalyst, an epoxy group-containing alcohol, a diluent, a
reaction initiator and an amino group-containing alkoxysilane shown in
Tables 1 and 2 below, and the process of Example 1 was repeated under
conditions described in Tables 1 and 2 in order to prepare primer
compositions B to E.
COMPARATIVE EXAMPLE 1
A comparative composition D' was prepared by using the same reaction
product that was employed for the preparation of the primer composition D,
but not using the amino group-containing alkoxysilane.
Table 1 shows blending proportions and reaction requirements for
synthesizing reaction products, and Table 2 shows blending proportions for
the preparation of primer compositions.
TABLE 1
______________________________________
Primer composition
B C D E
______________________________________
Polyisocyanate (parts)
Isophorone diisocyanato
520 520
Trimethylol propane (1 mole)
420
hexamethylene diisocyanato
(3 moles) adduct *1
Trimethylhexamethylene 420
diisocyanato
Polymerization inhibitor (parts)
2,6-Di-tert-butyl-4-
0.83 0.74 0.83 0.88
hydroxytoluene
Hyroxyl group-containing
acrylate or methacrylate
(parts)
2-Hydroxypropyl acrylate
305 305
Polypropylene glycol 339
monomethacrylate *2
Glycerin dimethacrylate 456
Reaction catalyst (parts)
Dibutyltin dilaurate
0.40 0.37 0.40 0.44
First step dropwise
60 70 60 60
addition temp. (.degree.C.)
First step dropwise
2 1 2 2
addition time (hr.)
First step reaction
60 70 60 60
temp. (.degree.C.)
First step reaction
1.5 5 2 3
time (hr.)
Unreacted isocyanato groups
2.62 0.62 2.61 2.26
of urethane acrylate
intermediate (10.sup.-3 mole/g)
Epoxy group-containing
alcohol (parts)
Glycidol 174
Pentaerythritol diglycidyl
78
ether
Glycerin-1,3-diglycidyl 479
ether
Sorbitol tetraglycidyl 406
ether
Second step dropwise
60 60
addition temp. (.degree.C.)
Second step dropwise
1 *3 1 *3
addition time (hr.)
Second step reaction
65 75 65 70
temp. (.degree.C.)
Second step reaction
.sup. 1.sup..5
5 2 3
time (hr.)
Reaction ratio of
>98 >98 >98 >98
isocyanato group (%)
______________________________________
Note:
*1 An ethyl acetate solution including 70% of solids.
*2 The average molecular weight was 360.
*3 The total amount was added at once.
TABLE 2
______________________________________
Primer composition
B C D D' E
______________________________________
Reaction product (parts)
400 500 400 400 400
Diluent (parts)
Ethyl acetate 600 600
Butyl acetate 600
Toluene 800
Xylene 500
Reaction initiator (parts)
2-Hydroxy-2-methyl-1-
8 10 10 10 6
phenylpropane-1-one
Amino group-containing
alkoxysilane (parts)
.gamma.-Aminopropyltriethoxysilane
100
N--(3-Aminoethyl)-.gamma.-amino-
70 26 51
propyltrimethoxysilane
______________________________________
EXAMPLE 3
The primer compositions A to E and the comparative composition D' prepared
in Examples 1 and 2 were applied to each one surface of the glass plates
having a square shape one side of which was 30 cm in length and having a
thickness of 3 mm by the use of a brush, and heating was then carried out
for a period of 30 minutes at 120.degree. C. in order to prepare primer
films thereon. Each glass plate and a polycarbonate plate having the same
plane size as the glass plate and having a thickness of 0.5 mm were fixed
in parallel by using a spacer so that the primer-applied surface of the
glass plate might confront the polycarbonate plate and so that both the
plates might be spaced as much as 0.5 mm, and three sides of the fixed
plates were sealed with a tape, leaving the one remaining side open. The
fixed plates were oriented turning up the open sides thereof, and an
urethane acrylate adhesive U1 modified with a polycarbonate and an amino
group-containing alkoxysilane and an epoxyacrylate adhesive U2 were each
fully injected through the open sides into the spaces between the fixed
plates, least air bubbles should be introduced thereinto. The resulting
laminates were subjected to ultraviolet rays irradiation for 5 seconds by
the use of an ultraviolet rays irradiation device equipped with a 30 W/cm
output high-pressure mercury vapor lamp, with the lamp spaced as much as
15 cm from the glass plates thereof, in order to cure the adhesives, so
that there were prepared glass plate-adhesive-polycarbonate plate
laminates in which each primer layer was formed between the glass plate
and the adhesive.
COMPARATIVE EXAMPLE 2
For comparison, glass plates which had not undergone the primer treatment
were used to prepare similar laminates. For thus prepared laminates,
appearance and adhesion state were observed, and shear adhesive strength
and peel-off adhesive strength were measured. Furthermore, for laminates
prepared in the same manner, the following tests were carried out.
(1) Boiling test: Each laminate was caused to uprightly stand in warm water
of 65.degree. C. and was immersed therein for 3 minutes, it was immersed
immediately in boiling water at 100.degree. C. for 2 hours. Appearance and
the adhered state of this laminate were compared with those at room
temperature, and the shear adhesive strength and the peel-off adhesive
strength were measured.
(2) Heat resistance test: After the laminate was left to stand in a
thermostat at 100.degree. C. for 2 hours, comparison and measurements were
conducted similarly as in (1).
These results are shown in Table 3 below.
TABLE 3
__________________________________________________________________________
No primer D'
Adhe- (Compara- (Compar-
sive
Test item tive) A B C D ative)
E
__________________________________________________________________________
U1 Normal state:
Appearance
Color-
Color-
Color-
Color-
Color-
Color-
Color-
less less less less less less less
Adhered state
Good Good Good Good Good Good Good
Shear adhesive
72 208* 198* 168* 210* 81 182*
strength (kg/cm.sup.2)
Peel-off adhesive
3.0 9.0 8.8 6.2 9.3 5.3 7.7
strength (kg/cm)
Boiling test:
Appearance
Not Not Not Not Not ** Not
changed
changed
changed
changed
changed changed
Adhered state
Not Not Not Not Not ** Not
changed
changed
changed
changed
changed changed
Shear adhesive
36 82 69 48 94 44 66
strength (kg/cm.sup.2)
Peel-off adhesive
0.9 3.5 2.2 1.4 3.6 1.1 1.8
strength (kg/cm)
Heat resistance test:
Appearance
Not Not Not Not Not ** Not
changed
changed
changed
changed
changed changed
Adhered state
Not Not Not Not Not ** Not
changed
changed
change
changed
changed changed
Shear adhesion
75 220* 201* 169* 216* 80 188*
strength (kg/cm.sup.2)
Peel-off adhesive
3.2 10.3 9.1 6.6 9.5 5.4 7.2
strength (kg/cm)
U2 Normal state:
Appearance
Color-
Color-
Color-
Color-
Color-
Color-
Color-
less less less less less less less
Adhered state
Good Good Good Good Good Good Good
Shear adhesion
19 52 50 46 56 24 52
strength (kg/cm.sup.2)
Peel-off adhesive
0.8 2.2 2.7 2.9 3.7 1.2 3.3
strength (kg/cm)
__________________________________________________________________________
Note:
*The glass plate was broken.
**A partial peeloff occured between the glass plate and the primer layer.
U1: The main component was synthesized from polycarbonate diol, bisphenol
A, propylene oxide, 2hydroxypropyl acrylate, 2ethylhexyl acrylate and
isophoron diisocyanate.
U2: The main component was synthesized from bisphenol A, epichlorohydrin
and acrylic acid.
For the laminates in which the adhesive U2 was used, the boiling test and
the heat resistance test were carried out, and it has been found that with
regard to the laminates which had not undergone the primer treatment, the
adhesive layers were peeled from the glass plates and the polycarbonate
plates. On the contrary, with regard to the laminates which were treated
with the primer compositions of this invention, the adhesives were fully
kept adhering to the surfaces of the glass plates, though they were peeled
from the polycarbonate plates. With regard to the laminates treated with
the comparative primer composition D', the primer layers were partially
peeled from the glass plates, as in the case of the laminates in which the
adhesive U1 was employed.
The above-mentioned results indicate that the laminates in which the primer
compositions of this invention were used had an excellent adhesive
strength.
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