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BACKGROUND OF THE INVENTION
1. Field Of The Invention
The present invention relates to a light shielding screen structure. More
particularly the present invention is concerned with a light shielding
screen structure having not only a high mechanical strength but also
excellent optical properties, which is useful for adjusting the angles of
the light rays emitted from various indicators such as indicators for
instruments mounted on an instrument panel of an automobile and from
image-indicating devices such as the CRT (cathode-ray tube) of a
television receiver and for shielding extraneous light rays incident on
the indicators or image-indicating devices, thereby preventing the
deterioration of an image projected.
2. Discussion Of Related Art
Various light shielding screens have heretofore been proposed. For example,
Japanese Patent Application Publication No. 55-7562/1980 and U.S. Pat. No.
2,053,173 disclose a light shielding screen which is produced by a process
which comprises putting transparent plastic layers and light shielding
plastic layers one upon another to form a block consisting of laminated
layers and slicing the resulting block perpendicularly relative to the
laminated layers.
However, in the above-mentioned conventional light shielding screen, it is
difficult to precisely control the width and the thickness of the
transparent layer and the light shielding layer, since in slicing the
block to form a light shielding screen the transparent layer and the light
shielding layer undergo deformation. Further, the process necessarily
involves the step of smoothing the surface exposed by slicing. Therefore,
such a light shielding screen cannot be stably produced.
On the other hand, a light shielding screen having a fine structure
produced from a photocurable resin composition has been proposed in
Japanese Patent Application Laid-Open Specification No. 55-139250/1980.
However, in the light shielding screen disclosed in the above-mentioned
patent application laid-open specification, the fine partition walls are
exposed. Therefore, the light shielding screen has disadvantages in that
when it is actually used for various applications, there is the
disadvantage that the exposed fine structure suffers physical damage upon
contact with other objects, and that foreign matter such as dust etc. may
accumulate in the spaces between the partition walls, thereby decreasing
the light transmission.
In order to obviate the above-mentioned disadvantages, Japanese Patent
Application Laid-Open Specification Nos. 57-89701, 57-165802, 58-215880
and 60-125880 and U.S. Pat. No. 4,688,156 have proposed to fill the spaces
between the partition walls with a transparent resin or attach a
transparent sheet to the ends of the partition walls by means of an
adhesive or a double-coated adhesive tape so as to cover up the fine
partition wall structure. However, in the case where the spaces are filled
with a transparent resin, it is difficult to fill up the spaces between
the partition walls with the transparent resin without causing bubbles to
form therein. On the other hand, in the case of attaching a transparent
sheet by means of an adhesive or a double-coated adhesive tape, if the
amount of the adhesive used is not enough, the bonding strength between
the transparent sheet and the ends of the partition walls is too low,
whereas if the amount of the adhesive is in excess, the adhesive is likely
to enter the spaces between the partition walls to such a degree that
transmitted light rays are scattered, resulting in a decrease in light
transmission. Thus, heretofore there has not been realized a light
shielding screen structure satisfying both the requirements of
satisfactory bond strength and excellent optical properties.
Japanese Utility Patent Application Laid-Open Specification No. 62-9201
discloses a light shielding screen structure comprising a first light
transmissible substrate having a light shielding layer thereon, and a
second light transmissible substrate connected to the first light
transmissible substrate through the light shielding layer. The light
shielding layer comprises at least one light shielding screen portion and
a light non-transmissible retaining portion which includes the entire
outermost peripheral area of the light shielding layer. The second light
transmissible substrate is attached to the light shielding layer at only
its light non-transmissible retaining portion by means of a double-coated
adhesive tape. However, in preparing this light shielding screen
structure, since it is necessary to provide an adhesive tape having a
shape corresponding to the shape of the light shielding screen portion,
the types of light shielding screen structures which may be used are
limited. Further, this type of light shielding screen structure is also
disadvantageous in that since there is no bonding between the light
shielding screen portion of the light shielding layer and the second light
transmissible substrate, when it is intended to produce a light shielding
screen structure in which the light shielding screen portion has a large
area relative to the light non-transmissible retaining portion, the
bonding strength between the light shielding layer and the second light
transmissible substrate becomes too weak, and there cannot be obtained a
light shielding screen structure having a sufficient mechanical strength
as a whole.
SUMMARY OF THE INVENTION
The present inventors have made extensive and intensive studies with a view
toward eliminating the above-mentioned drawbacks of the conventional light
shielding screen structures. As a result, they have found that when in a
light shielding screen structure comprising first and second light
transmissible substrates and a light shielding screen composed of
partition walls and interposed between the first and second substrates,
the upper and lower end surfaces of the partition walls are bonded
respectively to the first and second substrates by means of a photo
curable adhesive, the light shielding screen structure is advantageous in
that it not only has a high mechanical strength but also has excellent
optical properties. Based on these findings, the present invention has
been completed.
According to the present invention, there is provided a light shielding
screen structure comprising:
a first light transmissible substrate;
a second light transmissible substrate; and
a light shielding screen interposed between
said first light transmissible substrate and
said second light transmissible substrate,
said light shielding screen comprising a photocured resin composition layer
and a plurality of apertures passing through said resin composition layer,
said apertures in said resin composition layer forming a perforated
structure of a striped or sectioned pattern, in which said resin
composition layer constitutes partition walls defining said apertures,
said apertures having their respective upper and lower openings
respectively defined by the upper and lower ends of said partition walls,
the upper and lower end surfaces of said partition walls being connected
respectively to said first light transmissible substrate and said second
light transmissible substrate through a photocured adhesive layer, with
part of the photocured adhesive layer which protrudes outwardly from the
areas of the upper and lower end surfaces of said partition walls forming
a fillet in each aperture at a corner portion which is defined by the
inner wall of each aperture and the inner surface of each light
transmissible substrate,
the connection between each partition wall and each light transmissible
substrate having a peeling strength of 50 g/cm or more, and
said fillet having a width of not greater than 5 .mu.m.
Accordingly, it is an object of the present invention to provide a light
shielding screen structure which not only has excellent optical properties
but also excellent mechanical strength.
It is another object of the present invention to provide a light shielding
screen structure of the above kind, which is simple in structure.
It is a further object of the present invention to provide a method for
producing a light shielding screen structure of the character described
above, which can be easily conducted through photocuring a photocurable
adhesive.
The foregoing and other objects, features and advantages of the present
invention will be apparent to those skilled in the art from the following
description and appended claims in connection with the accompanying
drawings.
BRIEF DESCRIPTION OF DRAWINGS
In the drawings:
FIG. 1 shows a schematic side view of one form of a light shielding screen
structure according to the present invention;
FIG. 2 shows a schematic perspective view of one form of a light shielding
screen to be used in the present invention;
FIG. 3 is a partly cut-away enlarged view of FIG. 1;
FIG. 4 is a partly cut-away enlarged view of FIG. 3, showing the structure
of a fillet formed at the corner portion defined by the inner wall of each
aperture of the light shielding screen and the inner surface of each light
transmissible substrate;
FIGS. 5(a) to 5(g) are schematic views explaining one mode of a process for
producing a light shielding screen structure according to the present
invention, in which process a light shielding screen is provided in a
composite form in which the light shielding screen is attached to a light
transmissible substrate by means of a photocured adhesive; an
FIGS. 6(a) and 6(b) are schematic views explaining another mode of a
process for preparing a light shielding screen structure according to the
present invention, in which process a light shielding screen is provided
in a single form.
In FIGS. 1 through 6(b), like parts or portions are designated by like
numerals or characters.
Referring now to FIGS. 1 to 3, numeral 2a designates a first light
transmissible substrate, numeral 7a an adhesive layer, numeral 1 a light
shielding screen, numeral 7b an adhesive layer and numeral 2b a second
light transmissible substrate. Light shielding screen 1 comprises a
photocured resin composition layer and a plurality of apertures passing
through the photocured resin composition layer in a direction
perpendicular to the layer surface of the resin composition layer. The
photocured resin composition layer cooperates with the apertures to form a
perforated structure of a predetermined pattern, in which the photocured
resin composition layer constitutes partition walls defining the
apertures. As shown in FIG. 2, in one embodiment of the present invention,
a plurality of partition walls 1A are arranged in a regular square network
pattern. The apertures have their respective upper and lower openings
respectively defined by the upper and lower ends of partition walls 1A. As
shown in FIG. 1, the upper and lower end surfaces of partition walls 1A
are connected respectively to first light transmissible substrate 2a and
second light transmissible substrate 2b through photocured adhesive layer
7a, 7b.
In FIG. 4, there is shown an enlarged view illustrating how a fillet is
formed. As is seen from FIG. 4, part of photocured adhesive layer 7a, 7b
protrudes outwardly from the areas of the upper and lower end surfaces of
the partition walls 1A to form fillet 8 in each aperture at its corner
portion defined by the inner wall of each aperture and the inner surface
of each light transmissible substrate 2a, 2b. The width of fillet 8 is
herein defined by the length of W as depicted in FIG. 4.
In the light shielding screen structure of the present invention, due to
the connection of light transmissible substrate 2a, 2b to the end surface
of partition wall 1A through photocured adhesive layer 7a, 7b, protrusion
of the adhesive layer into each aperture defined by the partition walls is
suppressed and, accordingly, the size of fillet 8 can be minimized, while
maintaining the bonding strength between light transmissible substrate 2a,
2b and partition wall 1A at a practical level. As a result, in the present
light shielding screen structure, the viewable angle and haze can be
controlled. Further, the light shielding screen structure of the present
invention does not suffer from peeling, not only when it is subjected to
blanking or cutting but also when it is fixed on an indicator, an
image-indicating device and the like. In addition, because a photocurable
adhesive is used, the time for completion of bonding in the process for
the production of a light shielding screen structure is shortened.
As described above, light shielding screen 1 to be used in the present
invention comprises a plurality of partition walls 1A made of a photocured
resin composition and apertures defined thereby. Such a light shielding
screen is prepared by a process comprising superimposing a negative mask
having a predetermined pattern on a photocurable resin composition layer,
irradiating the resin composition with active rays through the mask so as
to photocure the photocurable resin so that it corresponds with the
pattern, and removing the uncured resin with a developer. The height of
the partition wall is equal to the thickness of light shielding screen 1,
which thickness depends on the thickness of the photocurable resin
composition layer
The light shielding screen to be used in the present invention has a
striped pattern or a sectioned pattern. Examples of sectioned patterns
include various patterns such as a circle network pattern, an ellipse
network pattern, a triangle network pattern, a regular square network
pattern, a rectangle network pattern, a rhombic network pattern, a
parallelogram network pattern and honeycomb pattern, etc. The partition
wall structure may constitute the entire part of the light shielding
screen or may be locally present in the light shielding screen. In the
case of the latter, the partition wall structure portion may represent a
design such as a circle, a polygon, a silhouette, etc., and the remaining
portion of the light shielding screen layer may constitute a light
non-transmissible portion having the same thickness as that of the
partition wall structure portion.
The width of an aperture defined by the partition walls may vary depending
on the shape of the aperture. However, in general, if the width of the
aperture is too small, the formation of partition walls becomes difficult
while if the width is too large, the angle of transmitted light becomes
too large, which is undesirable from a practical viewpoint. Thus, the
width of the aperture is preferably in the range of from 20 to 500 .mu.m.
(The term "width of an aperture" as used herein is intended to mean: the
inner distance between the adjacent stripes in the case of a striped
pattern; the inner diameter in the case of a circular aperture; the length
of the inner minor axis in the case of an oval aperture; in the case of a
polygonal aperture having sides in odd numbers, the minimum inner distance
between the vertexes and the sides opposite to the vertexes; and in the
case of a polygonal aperture having sides in even numbers, the minimum
inner distance between the opposite sides.) Likewise, if the height of the
partition wall is too large, the formation of partition walls becomes
difficult while if it is too small, the angle of transmitted light becomes
too large. Therefore, the height of the partition wall is preferably in
the range of from 50 to 1,000 .mu.m. With respect to the thickness of the
partition wall, if it is too small, the formation of the partition walls
becomes difficult while if it is too large, the light transmission is
lowered. The thickness is preferably in the range of from 5 to 500 .mu.m,
more preferably in the range of from 10 to 200 .mu.m. In addition, if the
ratio of the thickness of the partition wall to the width of the aperture
is too large, the angle of the transmitted light becomes too large, while
if it is too small, the formation of the partition walls becomes
difficult. The ratio of the thickness of the partition wall to the width
of the aperture is preferably in the range of from 1/1 to 1/10. On the
other hand, if the ratio of the width of the aperture to the height of the
partition wall is too large, the angle of transmitted light becomes too
large, while if it is too small, the formation of the partition walls
becomes difficult. The ratio of the width of the aperture to the height of
the partition wall is preferably in the range of from 1/0.5 to 1/5.
The size of the light shielding screen structure of the present invention
may vary depending on the applications, but in general, it is not smaller
than a 5 mm.times.5 mm size. If desired, a light shielding screen
structure having a great size may first be obtained, and light shielding
screen structures of smaller sizes may be cut out therefrom.
In the method for producing a light shielding screen structure of the
present invention, the preparation of a light shielding screen is
involved. As described later, a light shielding screen may be provided in
a composite form for the subsequent steps, in which composite form the
light shielding screen is attached to a light transmissible substrate, or
it may be prepared in a single form for the subsequent steps.
For preparing a light shielding screen in a composite form as mentioned
above, there is used a method comprising: applying a photocurable resin
composition in a predetermined thickness to the surface of a light
transmissible substrate or laminating a sheet of a photocurable resin
composition on the surface of a light transmissible substrate to obtain an
assembly, the light transmissible substrate having previously been coated
with a photocurable adhesive which is capable of bonding the light
transmissible substrate to the photo curable resin composition when
photocured; placing a negative having a predetermined pattern on the
assembly; exposing the resultant assembly to active rays from a source
such as an arc lamp, a mercury vapor lamp, a xenon lamp, an ultraviolet
ray fluorescent lamp or the sun to cure the photocurable resin composition
in accordance with the pattern of the negative and simultaneously cure the
photocurable adhesive; removing the negative; and removing the non-exposed
portion of the photocured resin by means of a developer to effect
development, so that the desired reliefs are obtained. The above-mentioned
photocurable adhesive may preferably comprise, for example, a polymer
disclosed in Japanese Patent Application Laid-Open Specification No.
58-174945/1983, which has been three-dimensionally polymerized by an ionic
addition reaction and has terminal ethylenically unsaturated bonds in the
molecule.
In the photocuring process of the resin composition, it is preferred that
the surface portions of both the ends of the resultant relief (i.e., the
end surfaces of the partition walls) still contain a photocurable resin
composition remaining less cured. In this connection, the following should
be noted. As described later when referring to FIGS. 5(a) to 5(g), in
preparing a light shielding screen, areas on the surface of the
photocurable resin composition layer which correspond to the end surfaces
of the partition walls are in contact with a release film when pattern
forming exposure is conducted. Since such a release film generally has
oxygen permeability, the areas corresponding to the end surfaces of the
partition walls are caused to be contacted with oxygen. In the presence of
oxygen, the radicals produced by the exposure are likely to undergo
termination of the reaction and thus the photocuring reaction no longer
proceeds at the end surfaces of the partition wall, whereas the inner
portions of the partition walls are completely photocured. From a
viewpoint of oxygen permeability, it is preferred that the release film to
be interposed between the negative film and the photocurable resin
composition layer (see FIGS. 5(a) to 5(g)) is made of polypropylene,
cellulose ester, polycarbonate, polymethyl methacrylate, polyethylene,
polystyrene, polyethylene terephthalate or the like and that the thickness
of the release film is 3 .mu.m to 50 .mu.m.
In order for the photocurable resin composition to surely remain less cured
at portions corresponding to the end surfaces of the partition walls, a
post-exposure operation is preferably omitted or conducted with active
rays as weak as 500 mJ/cm.sup.2 or less, which post-exposure operation is
usually conducted in preparing a conventional light shielding screen after
the pattern forming exposure and subsequent development in order to
increase the strength of the partition walls. Alternatively, there may be
employed a photocurable resin composition having photocuring properties
lowered by incorporating a dye or a pigment. There may also preferably be
employed a photocurable resin composition which contains a prepolymer
having unsaturated bonds in the main chain. In these ways, less
photocuring of the photocurable resin composition at portions
corresponding to the upper and lower end surfaces of the partition walls
can be attained.
For preparing a light shielding screen having partition walls with improved
light shielding properties, a light shielding screen is dyed or it is
prepared using a photocurable resin composition having incorporated
therein a dye or a pigment. In the latter case, it is necessary that a dye
or a pigment be incorporated in such an amount that the photosensitivity
of the photocurable resin composition is not remarkably decreased. The
amount of a dye or a pigment to be added is from 0.05 to 2.0 wt%,
preferably from 0.1 to 1.0 wt%. Examples of dyes to be used in the present
invention include cationic dyes, disperse dyes, reactive dyes, acid dyes,
direct dyes and metallized dyes. Particularly, a disperse dye or a
metallized dye is preferable from the viewpoint of weathering-resistant
properties. The type of dye to be used may be chosen from the viewpoints
of the compatibility of the dye with the photocurable resin composition
and the absorption characteristics of the dye. With respect to the pigment
to be used in the present invention, either an inorganic pigment or an
organic pigment can be employed, and it is preferable to employ a pigment
having good dispersibility.
In FIG. 5(a) to 5(g), there is schematically illustrated one mode of a
process for producing the light shielding screen structure of the present
invention, in which a light shielding screen is first prepared in
composite form as in Example 1 which is described later.
As shown in FIG. 5(a), on transparent glass plate 3 are superimposed
image-bearing negative 4, release film 5a which is made of a polypropylene
film, and photocurable resin composition layer 6 in this order to obtain a
photocurable resin assembly. As shown in FIG. 5(b), a separately-prepared
laminate of light transmissible substrate 2a made of polyethylene
terephthalate, photocurable adhesive layer 7a and release film 5b made of
a polypropylene film is provided. Release film 5b is peeled off from the
laminate. The laminate with release film 5b peeled off therefrom is placed
on the photocurable resin assembly so that adhesive layer 7a and
photocurable resin composition layer 6 are contacted with each other [see
FIG. 5(c)]. Then, the resultant assembly is exposed from the side of
transparent glass plate 3 to active rays to effect photocuring of not only
photocurable resin composition layer 6 but also photocurable adhesive
layer 7a. In this instance, as described before, it is preferred that the
photocuring is conducted in such a manner that the photocurable resin
composition remains less cured at portions corresponding to the end
surfaces of the ultimate partition walls. Then, release film 5a is peeled
off and the non-exposed (non-photocured) areas of resin layer 6A are
removed for the development of partition walls, followed by dying the
partition walls, thereby obtaining light shielding screen 1 in a composite
form in which partition walls are connected at their respective ends to
light transmissible substrate 2a through photocured adhesive layer 7a [see
FIG. 5(d) and 5(e)]. Thereafter, release film 5c is peeled off from a
laminate of photocurable adhesive 7b and light transmissible substrate 2b.
On the laminate with release film 5c peeled off therefrom is placed the
above-prepared light shielding screen 1 with light transmissible substrate
2a connected thereto in such a manner that adhesive layer 7b is contacted
with the end surfaces of the partition walls of light shielding screen 1
[see FIG. 5(f) and 5(g)], and both of them are pressed to each other.
Finally, the resultant laminate assembly is exposed from the side of light
transmissible substrate 2b to active rays to bond the end surfaces of the
partition walls to light transmissible substrate 2b by means of photocured
adhesive 7b, thereby obtaining a light shielding screen structure of the
present invention.
In the above process, the photocuring of photocurable adhesive layer 7a for
connecting the upper ends of partition walls to upper light transmissible
substrate 2a is effected simultaneously with formation of partition walls
by the pattern-wise photo curing of the photocurable resin composition
layer 6. Therefore, there is no danger that photocured adhesive 7a
protrudes into the apertures between the partition walls of light
shielding screen 1.
In the above process, it should further be noted that the the photocurable
resin composition remains less cured at portions corresponding to the end
surfaces of the ultimate partition walls due to the polymerization
inhibiting effect of oxgen as described above. As photocurable adhesive 7a
and 7b, there is preferably employed such a polymer as is disclosed in
Japanese Patent Application Laid-open Specification No. 58-174945, which
polymer has been three-dimensionally polymerized by ionic addition
reaction and has terminal ethylenically unsaturated bonds in the molecule.
When exposed to active rays, the photocurable resin composition remaining
less cured in the end surfaces of the partition walls and the lower
adhesive layer 7b are caused to be chemically bonded together. Therefore,
although photocurable adhesive layer 7b is solid and very thin, strong
bonding with the end surfaces of the partition walls can be obtained. The
decreased thickness of the adhesive layer and the solid state of the
adhesive layer contributes to preventing the adhesive from protrusion into
the apertures so that the size of a fillet is reduced, while attaining
strong bonding between the end surfaces of the partition walls and lower
light transmissible substrate 2b through the photocured adhesive layer 7b.
In another mode in which a light shielding screen is produced in a single
form, substantially the same procedure is conducted as in the production
of a light shielding screen in a composite form, except that a
photocurable adhesive is not applied to the light transmissible substrate
and the transparent substrate is removed after the pattern forming
exposure, as described in Japanese Patent Application Laid-Open
Specification No. 60-195849/1985.
In this mode, after the photocurable resin composition layer has been
subjected to pattern forming exposure, the non-exposed areas of the
photocured resin composition layer are removed, thereby obtaining a light
shielding screen in a single form in which the photocurable resin
composition remains less cured on both the upper and lower end portions of
the partition walls. Since a photocured resin composition is not bonded to
the light transmissible substrate by means of a photocured adhesive, as
different from the previously-mentioned mode, removal of the non-exposed
areas can be easily performed as compared to the case of a photocured
resin composition layer having a light transmissible substrate bonded
thereto. Therefore, this mode of a process in which a light shielding
screen is produced in a single form, is suitable for the production of a
light shielding screen structure of the type in which partition walls
having large heights are desired.
Referring to FIG. 6(a), numeral 1 designates a light shielding screen
produced in a single form as mentioned above. Light shielding screen 1 is
interposed between light transmissible substrate 2a coated with
photocurable adhesive 7a and light transmissible substrate 2b coated with
photocurable adhesive 7b as depicted in FIG. 6(a). The resultant laminate
assembly is exposed from the sides of light transmissible substrates 2a
and 2b to active rays. By exposure to active rays, transmissible
substrates 2a and 2b are firmly bonded to light shielding screen 1 at the
end surfaces of the partition walls through photocured adhesive layers 7a
and 7b, respectively. Thus, a light shielding screen structure of the
present invention in which the formation of a fillet, constituted of the
adhesive, is restrained while attaining strong bonding between the light
transmissible substrates and the light shielding screen, is obtained.
Accordingly, in another aspect of the present invention, there is provided
a process for producing a light shielding screen structure comprising:
(a) providing a light shielding screen comprising a perforated structure
comprising a plurality of partition walls and apertures defined by said
partition walls, said partition walls being arranged to form the apertures
in a striped or sectioned pattern, said light shielding screen being in a
composite form in which said light shielding screen is connected at one
end surface of each partition wall to a first light transmissible
substrate through a photocured adhesive layer or being in a single form;
(b) in the case of the light shielding screen in a single form, pressing a
first light transmissible substrate having a photocurable adhesive layer
and a second light transmissible substrate having a photocurable adhesive
layer respectively against both sides of said light shielding screen to
obtain a laminate assembly, or
in the case of the light shielding screen in a composite form, pressing
said light shielding screen against a second light transmissible substrate
having a photocurable adhesive layer on its side of the photocurable
adhesive layer to obtain a laminate assembly; and
(c) exposing the laminate assembly to active rays to cure the photocurable
adhesive layer, thereby enabling the connection between each partition
wall and each light transmissible substrate to have a peeling strength of
50 g/cm or more and providing a fillet having a width of 5 .mu.m or less,
said fillet being defined as part of the photocured adhesive layer which
protrudes outwardly from the areas of the upper and lower end surfaces of
said partition walls in each aperture at a corner portion defined by the
inner wall of each aperture and the inner surface of each light
transmissible substrate.
A preferred example of a photocurable resin composition to be used in the
present invention is a composition comprising a prepolymer having
polymerizable ethylenically unsaturated groups, and, if desired, an
ethylenically unsaturated monomer, a photosensitizer and a thermal
polymerization inhibitor. Examples of prepolymers include unsaturated
polyesters, unsaturated polyurethanes, oligomers of an ester-acrylate
type, unsaturated polyamides, unsaturated polyimides, unsaturated
polyethers and unsaturated poly(meth)acrylates, various modified products
thereof such as alkyd resins and various rubber compounds having
carbon-carbon double bonds. Prepolymers having a number average molecular
weight of about 500 or more, usually about 500 to about 100,000 as
measured by osmometry, are generally employed.
Representative examples of unsaturated polyesters and modified unsaturated
polyesters include polyesters prepared by reacting unsaturated dibasic
acids such as maleic acid, fumaric acid and itaconic acid or anhydrides
thereof with polyvalent alcohols such as ethylene glycol, propylene
glycol, diethylene glycol, triethylene glycol, glycerin, trimethylol
propane, pentaerythritol, 1,4-polybutadiene having a terminal hydroxyl
group, hydrogenated or non-hydrogenated 1,2-polybutadiene,
butadienestyrene copolymer and butadiene-acrylonitrile copolymer;
polyesters obtained by substituting a portion of the acid components of
the abovementioned unsaturated polyesters with saturated polybasic acids
such as succinic acid, adipic acid, phthalic acid, isophthalic acid,
phthalic anhydride and trimellitic acid; and alkyd resins obtained by
modifying the above-mentioned polyesters with a drying oil fatty acid or
semidrying oil fatty acid.
Examples of unsaturated polyurethanes include unsaturated polyurethanes
having addition-polymerizable unsaturated groups introduced by utilizing
terminal isocyanate and/or hydroxyl groups of polyurethanes derived from
at least one polyol having two or more terminal hydroxyl groups and at
least one polyisocyanate, for example, unsaturated polyurethanes which are
prepared from (i) a polyurethane having terminal isocyanate and/or
hydroxyl groups and prepared from at least one polyol such as a polyhydric
alcohol as mentioned above, polyester polyol or polyether polyol and at
least one polyisocyanate such as tolylene diisocyanate,
diphenylmethane-4,4'-diisocyanate or hexamethylene diisocyanate and (ii)
at least one unsaturated mono- or dicarboxylic acid as mentioned above or
its ester or polyester having active hydrogen atoms derived from hydroxyl
(reactive with the terminal isocyanate) and/or carboxyl (reactive with
both of the terminal isocyanate and the terminal hydroxyl) and/o | | |
