U.S. patent application number 12/153309 was filed with the patent office on 2008-09-18 for photocurable and thermosetting resin composition and printed circuit boards made by using the same.
This patent application is currently assigned to Taiyo Ink Manufacturing Co., Ltd.. Invention is credited to Yoshitaka Hirai, Hideaki Kojima, Shouji Minegishi, Hidekazu Miyabe, Naoki Yoneda.
Application Number | 20080227883 12/153309 |
Document ID | / |
Family ID | 34990895 |
Filed Date | 2008-09-18 |
United States Patent
Application |
20080227883 |
Kind Code |
A1 |
Kojima; Hideaki ; et
al. |
September 18, 2008 |
Photocurable and thermosetting resin composition and printed
circuit boards made by using the same
Abstract
A photocurable and thermosetting composition comprises (A) a
carboxyl group-containing resin having at least one carboxyl group
in its molecule, (B) a photopolymerization initiator having an
oxime linkage represented by the following general formula (I), (C)
a reactive diluent, and (D) an epoxy compound having two or more
epoxy groups in its molecule. The above-mentioned
photopolymerization initiator (B) is incorporated into a
formulation which is different from at least a formulation into
which the above-mentioned carboxyl group-containing resin (A) and
the above-mentioned reactive diluent (C) are incorporated to
formulate a system comprising at least two parts. ##STR00001##
Inventors: |
Kojima; Hideaki;
(Kawagoe-shi, JP) ; Miyabe; Hidekazu; (Hiki-gun,
JP) ; Minegishi; Shouji; (Irma-shi, JP) ;
Yoneda; Naoki; (Kawagoe-shi, JP) ; Hirai;
Yoshitaka; (Higashimatsuyama-shi, JP) |
Correspondence
Address: |
RADER FISHMAN & GRAUER PLLC
LION BUILDING, 1233 20TH STREET N.W., SUITE 501
WASHINGTON
DC
20036
US
|
Assignee: |
Taiyo Ink Manufacturing Co.,
Ltd.
Tokyo
JP
|
Family ID: |
34990895 |
Appl. No.: |
12/153309 |
Filed: |
May 16, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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PCT/JP03/15187 |
Nov 27, 2003 |
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12153309 |
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11137641 |
May 26, 2005 |
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PCT/JP03/15187 |
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Current U.S.
Class: |
522/18 ;
522/26 |
Current CPC
Class: |
C08G 8/08 20130101; G03F
7/027 20130101; G03F 7/038 20130101; G03F 7/031 20130101 |
Class at
Publication: |
522/18 ;
522/26 |
International
Class: |
C08J 3/28 20060101
C08J003/28 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 28, 2002 |
JP |
2002-246254 |
Nov 28, 2002 |
JP |
2002-346254 |
Claims
1. A method of storing a multi-part photocurable and thermosetting
resin composition in the form of a multi-part system comprising in
combination at least two compositions, which comprises: preparing a
composition containing (A) a carboxyl group-containing resin having
at least one carboxyl group in its molecule and (C) a reactive
diluent, and a composition containing (D) an epoxy compound having
two or more epoxy groups in its molecule, and further comprising
(B) a photopolymerization initiator having an oxime linkage
represented by the following general formula (I), said
photopolymerization initiator (B) being incorporated into a
composition which is different from the composition into which said
carboxyl group-containing resin (A) and said reactive diluent (C)
are incorporated, and storing said compositions in individual
states. ##STR00006##
2. The method of storing a multi-part photocurable and
thermosetting resin composition according to claim 1, wherein said
carboxyl group-containing resin (A) is a carboxyl group-containing
photosensitive resin having two or more photosensitive unsaturated
double bonds in its molecule.
3. The method of storing a multi-part photocurable and
thermosetting resin composition according to claim 1, wherein said
photopolymerization initiator (B) having the oxime linkage
represented by said general formula (I) is a compound represented
by the following general formula (II): ##STR00007## wherein one or
two of R is a group represented by the following formula (III) and
the remainder is a hydrogen atom, a halogen atom, a methyl group,
or a phenyl group, and X represents an oxygen atom, a sulfur atom,
or a carbonyl group, ##STR00008## wherein R.sup.1 represents a
hydrogen atom, a methyl group, a phenyl group, a biphenyl group, or
a phenyl group or biphenyl group severally substituted by an alkyl
group of 1-6 carbon atoms.
4. The method of storing a multi-part photocurable and
thermosetting resin composition according to claim 1, further
comprising another photopolymerization initiator (B-I) other than
said photopolymerization initiator (B) and/or a sensitizer (B-II),
wherein said other photopolymerization initiator (B-I) and/or said
sensitizer (B-II) being incorporated into a composition which is
different from the composition into which said carboxyl
group-containing resin (A) and said reactive diluent (C) are
incorporated.
5. The method of storing a multi-part photocurable and
thermosetting resin composition according to claim 1, wherein said
reactive diluent (C) is a liquid photosensitive compound having at
least one unsaturated double bond in its molecule and present in an
amount of 2 to 50 parts by weight, based on 100 parts by weight of
said carboxyl group-containing resin (A).
6. The method of storing a multi-part photocurable and
thermosetting resin composition according to claim 1, further
comprising an inorganic filler and/or an organic filler (E),
wherein said inorganic filler and/or said organic filler (E) being
incorporated into either one of said compositions.
7. The method of storing a multi-part photocurable and
thermosetting resin composition according to claim 1, wherein said
photopolymerization initiator (B) is a compound represented by the
following general formula (IV): ##STR00009## wherein R.sup.2
represents a methyl group or an ethyl group.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of application Ser. No.
11/137,641 filed on May 26, 2005, which is a continuation of
Application PCT/JP03/15187, filed Nov. 27, 2003, which was
published under PCT Article 21(2).
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to a photocurable and thermosetting
resin composition and a printed circuit board made by using the
same, and more particularly relates to a photocurable and
thermosetting resin composition which excels in tack-free dryness,
adhesiveness, and resolving properties, scarcely produces mist
during the thermal curing thereof, enjoys high sensitivity, and
excels in storage stability, and to a printed circuit board having
a solder resist layer and/or a resin insulating layer excelling in
resistance to PCT (pressure cooker test), electrical insulating
properties, etc., which are produced by using the composition
mentioned above and which reduce the generation of gas during the
mounting of the parts thereon.
[0004] 2. Description of the Prior Art
[0005] A solder resist composition is used for the purpose of
preventing the bridging of solder and protecting circuits during
the soldering of a given part to a printed circuit board.
[0006] The cured product thereof is, therefore, required to possess
such properties as adhesiveness, resistance to chemicals, and
electrical properties. In recent years, the demand for the
production of printed circuit boards of further decreased weight
and increased density of conductor circuits has been finding
growing recognition in the printed circuit board manufacture
industry. To cope with this demand, a photolithographic developing
type solder resist composition, particularly the composition which
can be developed with an aqueous alkaline solution has been
developed and employed (see JP 1-141904, A, for example).
[0007] However, in the case of the solder resist composition which
has been heretofore used, since the photo-curing of the depths of a
coating film at the time of exposure is inadequate in the image
formation, the coating film may exfoliate during the development
thereof, which forms a big factor of preventing formation of the
image with high resolving properties.
[0008] Therefore, the fully satisfied material is not found out
till now, though the demand for development of the solder resist
composition excelling in the curing properties in deep portions at
the time of exposure increases.
[0009] The formation of a solder resist layer using such a
photolithographic developing type composition requires a step of
applying a resist composition to the entire surface of a substrate
by a screen printing method, a curtain coating method, a spray
coating method, a roll coating method, etc., a preliminary drying
step for volatilizing an organic solvent in order to allow the
contact exposure, an exposure step for cooling the coating film and
subjecting it to the contact exposure, a developing step to remove
unexposed portions by development, and a thermal curing step for
obtaining the sufficient coating properties. Among these steps,
particularly the exposure step is the very cumbersome process which
comprises exchanging a negative film according to the kind of the
printed circuit board, carrying out the position alignment thereof,
then drawing a vacuum and subjecting it to exposure to light.
Therefore, the shortening of the exposure process becomes a
significant factor for improving the productivity and lowering the
cost. The high sensitivity of the solder resist composition greatly
contributes to the shortening of an exposure process. Under such
circumstances, as for the solder resist composition used for a
general-purpose electric device, the demand for high sensitivity is
increasing. In order to realize such demand for increasing the
sensitivity, it is generally considered to add a large amount of a
polyfunctional (meth)acrylate compound to the composition. However,
if the polyfunctional (meth)acrylate compound of a low molecular
weight is added to the composition in a large amount, though the
sensitivity will be improved, there is a problem that tack-free
dryness (tack-free properties) required for the contact exposure
decreases remarkably, and the properties of the cured coating film
also decrease.
[0010] Furthermore, in the formation of a solder resist layer using
such a photolithographic developing type solder resist composition,
a volatile component (mist) generated from a resist composition
adheres to a hot air circulation type drying oven or to an exposure
device in a preliminary drying process accompanied with heating, an
exposure process, a thermal curing process, and a soldering
process, which becomes the cause of the abnormalities in mounting
the parts in the following soldering process and a subsequent gold
plating process. Therefore, the demand for the development of a
solder resist composition which contains a small amount of
ingredients (mist) which volatilizes from the resist composition in
the preliminary drying process, the exposure process, the thermal
curing process, and the soldering process has been finding growing
recognition, but the material which may fully satisfy such a demand
is not found out till now.
[0011] On the other hand, as a method for the production of a
multi-layer printed circuit board, a lamination pressing method has
been heretofore known to the art. The lamination pressing method,
however, necessitates use of production facilities which are very
voluminous and highly expensive and incurs difficulty in forming
fine patterns because the plating is carried out on the outer layer
during the plating step of through-holes and the thickness of
copper deposit increases.
[0012] For the purpose of overcoming such problems, in recent years
strenuous efforts are being continued for the development of a
multi-layer printed circuit board having conductor layers and resin
insulating layers alternately build up (build-up technique).
[0013] One method of such a build-up technique is, for example, a
method of manufacturing a multi-layer printed circuit board which
forms a resin insulating layer by using a photolithographic
developing type composition. This method comprises firstly applying
a liquid photosensitive resin composition to the entire surface of
a circuit board having conductor circuits formed in advance thereon
so that the conductor circuits are buried in the resultant coating
film by an arbitrary method such as a screen printing method, a
curtain coating method, and a spray coating method, drying the
coating film, then superposing a negative film having a prescribed
exposure pattern on the dried coating film, irradiating the dried
coating film with ultraviolet light for exposure, then removing the
negative film from the coating film, subjecting the coating film to
a development treatment to form a cured resin insulating layer of
the prescribed pattern, subsequently treating the resin insulating
layer with a coarsening agent thereby imparting coarsened surface
thereto, and thereafter forming a conductor layer as by electroless
plating or electroplating.
[0014] In such a method of manufacturing the multi-layer printed
circuit board having conductor layers and resin insulating layers
alternately build up, the photosensitive resin composition to be
used is required to exhibit sufficient photo-curing of the depths
of a coating film at the time of exposure, and the interlaminar
resin insulating layer formed therefrom is required to be excellent
in such properties as adhesiveness to a conductor layer, electrical
insulating properties, heat resistance, and resistance to
chemicals.
[0015] Further, in the heating step performed after formation of a
conductor layer as by electroless plating or electroplating, the
volatile component generated from the interlaminar resin insulating
layer becomes the cause of inferior adhesiveness of the conductor
layer thereto. However, the material which may fully solving such
problems is not found out till now.
[0016] As for the manufacture of a printed circuit board which is
used in the devices of small-amount production such as analytical
instrument and a printed circuit board to be manufactured as a
trial, the demand is directed to a solder resist composition which
can cope with a direct imaging technique which directly forms an
image on a printed circuit board according to the CAD (computer
aided design) data from a computer. As a light source to be used in
such a direct imaging technique, a laser source is preponderantly
used. The ultraviolet light of 300-450 nm in wavelength is used as
a single wavelength or in combination of several wavelengths, the
beam diameter is in the range of 5-15 .mu.m, and the output is
about several watts. Since the image is formed by scanning with a
width of 5-15 .mu.m while repeating ON-OFF of such a laser beam,
the period for forming a resist pattern on one printed circuit
board greatly depends on the sensitivity of the solder resist
composition. Accordingly, the solder resist composition to be used
in the laser direct imaging technique is required to possess the
sensitivity higher than that of the developing type solder resist
composition to be subjected to the general contact exposure.
SUMMARY OF THE INVENTION
[0017] The present invention has been made under the aforementioned
background and its main object is to provide a photocurable and
thermosetting resin composition which can be developed with an
aqueous alkaline solution, exhibits sufficiently high curing
properties in deep portions of a coating film at the time of
exposure, enjoys high degree of resolution, gives a cured product
which excels in such properties as heat resistance, resistance to
chemicals, electrical properties, resistance to moisture
absorption, and PCT resistance, and contains a small amount of a
component (mist) which volatilizes from a solder resist composition
in a preliminary drying process accompanied with heating, an
exposure process, a thermal curing process, and a soldering
process.
[0018] Another object of the present invention is to provide a
photocurable and thermosetting resin composition which exhibits
high sensitivity, enjoys high workability, is capable of coping
with a solder resist to be used in the laser direct imaging
technique, and excels in storage stability.
[0019] A further object of the present invention is to provide a
printed circuit board having a solder resist layer and/or a resin
insulating layer formed thereon, which layers allow reduction of
gas which generates during the mounting of the parts thereon and
excel in PCT resistance, electrical insulating properties, etc.
[0020] To accomplish the objects mentioned above, the present
invention provides a photocurable and thermosetting resin
composition characterized by comprising (A) a carboxyl
group-containing resin having at least one carboxyl group in its
molecule, (B) a photopolymerization initiator having an oxime
linkage represented by the following general formula (I), (C) a
reactive diluent, and (D) an epoxy compound having two or more
epoxy groups in its molecule, wherein the photopolymerization
initiator (B) mentioned above is incorporated into a formulation
which is different from at least a formulation into which the
above-mentioned carboxyl group-containing resin (A) and the
above-mentioned reactive diluent (C) are incorporated to formulate
a system comprising at least two parts.
##STR00002##
[0021] In accordance with the present invention, there is further
provided a printed circuit board having a solder resist layer
and/or a resin insulating layer formed thereon by the use of the
photocurable and thermosetting resin composition mentioned
above.
[0022] Since the photocurable and thermosetting resin composition
according to the present invention uses the photopolymerization
initiator having an oxime linkage as a photopolymerization
initiator, it exhibits high sensitivity and high curing properties
in deep portions of a coating film and is capable of stably forming
a cured film which excels in such properties as heat resistance and
PCT resistance.
[0023] Further, since the composition exhibits high sensitivity, it
enjoys high workability, allows preparation at a low cost, and is
capable of coping with the laser direct imaging technique. By
incorporating the photopolymerization initiator having the oxime
linkage which exhibits high sensitivity into a formulation
separated from a formulation into which a carboxyl group-containing
photosensitive resin and a reactive diluent having at least one
unsaturated double bond in its molecule are incorporated, it will
be easy to prepare a composition using the oxime-based
photopolymerization initiator which generates radicals by the
irradiation of visible light. Further, by incorporating the
photopolymerization initiator having the oxime linkage into a
formulation separated from a formulation into which the carboxyl
group-containing resin is incorporated, the oxime-based
photopolymerization initiator is prevented from being deteriorated,
thereby providing the stable photocurable and thermosetting resin
composition. Moreover, there is obtained another effect of reducing
the contamination of the working environment because any mist
originated from a photopolymerization initiator will not generate
in an exposure process, a thermal curing process accompanied with
heating, and a soldering process.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] The present inventors, after continuing a diligent study for
solving the problems mentioned above, have made the findings that
the composition containing at least one photopolymerization
initiator having the oxime linkage represented by the
aforementioned general formula (I) as a photopolymerization
initiator (B) in combination with (A) a carboxyl group-containing
resin having at least one carboxyl group in its molecule, (C) a
reactive diluent, and (D) an epoxy compound having two or more
epoxy groups in its molecule highly sensitively reacts with the
active energy ray irradiated during the exposure process, that the
photopolymerization rate of the photosensitive components (a
carboxyl group-containing resin having two or more photosensitive
unsaturated double bonds in its molecule and a reactive diluent)
increases and, as a result, the resolving properties are improved,
that a coating film which excels in tack-free dryness may be
obtained, and that the generation of components (mist) which
volatilizes during the thermal curing process is little.
[0025] Specifically, since the photopolymerization initiator (B)
having the oxime linkage represented by the aforementioned general
formula (I) to be used in the present invention exhibits high
sensitivity, thereby giving the sufficient resolving properties
with the addition of a small amount thereof, does not give the
cause of generation of mist because it does not vapor out by
heating, and contributes to the preparation of a coating film which
excels in tack-free dryness because it sparingly dissolves in a
solvent.
[0026] It has been now confirmed, however, that a composition
containing the photopolymerization initiator (B) having the oxime
linkage represented by the aforementioned general formula (I)
incorporated therein together with the aforementioned carboxyl
group-containing resin (A) having at least one carboxyl group in
its molecule exhibits poor storage stability because the
photopolymerization initiator has a pair of unpaired electrons in
its nitrogen atom. Further, since the photopolymerization initiator
(B) having the oxime linkage represented by the aforementioned
general formula (I) exhibits high sensitivity, the contact thereof
with the reactive diluent (C) is not preferable in view of the
storage stability.
[0027] After due consideration of the above findings, the present
inventors have found that the photocurable and thermosetting resin
composition which enjoys high storage stability may be obtained by
incorporating the photopolymerization initiator (B) having the
oxime linkage mentioned above into a formulation which is different
from at least a formulation into which the above-mentioned carboxyl
group-containing resin (A) and the above-mentioned reactive diluent
(C) are incorporated to formulate a system comprising at least two
parts. As a result, the present invention has been perfected.
[0028] Incidentally, in this specification the photopolymerization
initiator having the oxime linkage represented by the
aforementioned general formula (I) may be occasionally referred to
as the oxime-based photopolymerization initiator.
[0029] Now, the components of the alkali-developing type
photocurable and thermosetting resin composition of the present
invention will be described in detail below.
[0030] First, as the above-mentioned carboxyl group-containing
resin (A) having at least one carboxyl group in its molecule, any
of the carboxyl group-containing resins, specifically any of the
carboxyl group-containing photosensitive resins having an
ethylenically unsaturated double bond in itself and any of the
carboxyl group-containing resins having no ethylenically
unsaturated double bond may be used and not limited to particular
resins. However, the resins (either of oligomer and polymer may be
adopted) as listed below can be particularly advantageously
used:
[0031] (1) a carboxyl group-containing resin obtained by the
copolymerization of (a) an unsaturated carboxylic acid with (b) a
compound having an unsaturated double bond,
[0032] (2) a carboxyl group-containing photosensitive resin
obtained by adding an ethylenically unsaturated group (b') as a
pendant to a copolymer of (a) an unsaturated carboxylic acid and
(b) a compound having an unsaturated double bond,
[0033] (3) a carboxyl group-containing photosensitive resin
obtained by causing (d) an unsaturated monocarboxylic acid to react
with a copolymer of (c) a compound having a epoxy group and an
unsaturated double bond and (b) a compound having an unsaturated
double bond and then causing (e) a saturated or unsaturated
polybasic acid anhydride to react with the secondary hydroxyl group
caused by the above reaction,
[0034] (4) a carboxyl group-containing photosensitive resin
obtained by causing (g) a compound having a hydroxyl group and an
unsaturated double bond to react with a copolymer of (f) an acid
anhydride having an unsaturated double bond and (b) a compound
having an unsaturated double bond,
[0035] (5) a carboxyl group-containing photosensitive resin
obtained by causing (h) a polyfunctional epoxy compound to react
with (d) an unsaturated monocarboxylic acid and then causing (e) a
saturated or unsaturated polybasic acid anhydride to react with the
hydroxyl group caused by the above reaction,
[0036] (6) a hydroxyl group-containing and carboxyl
group-containing photosensitive resin obtained by causing (e) a
saturated or unsaturated polybasic acid anhydride to react with (i)
a hydroxyl group-containing polymer and then further causing (c) a
compound having an epoxy group and an unsaturated double bond to
react with the resultant carboxylic acid,
[0037] (7) a carboxyl group-containing photosensitive resin
obtained by causing (e) a saturated or unsaturated polybasic acid
anhydride to react with a reaction product of (h) a polyfunctional
epoxy compound with (d) an unsaturated monocarboxylic acid and (j)
a compound containing in its molecule at least one alcoholic
hydroxyl group and one reactive group other than the alcoholic
hydroxyl group, which can react with an epoxy group, and
[0038] (8) a carboxyl group-containing photosensitive resin
obtained by causing (d) an unsaturated monocarboxylic acid to react
with (1) a polyfunctional oxetane compound having at least two
oxetane rings in its molecule and then causing (e) a saturated or
unsaturated polybasic acid anhydride to react with the primary
hydroxyl group of the resultant modified oxetane resin.
[0039] Among other resins enumerated above, the carboxyl
group-containing photosensitive resins having two or more
photosensitive unsaturated double bond in its molecule,
particularly the carboxyl group-containing photosensitive resin (5)
mentioned above, prove to be desirable.
[0040] Since the carboxyl group-containing resins (A) mentioned
above have numerous free carboxyl groups added to the side chain of
a backbone polymer, the composition containing these resins is
developable with a dilute aqueous alkaline solution.
[0041] The acid value of the carboxyl group-containing resin (A)
mentioned above is preferred to be in the range of 45 to 200 mg
KOH/g, preferably in the range of 45 to 160 mg KOH/g.
[0042] If the acid value of the carboxyl group-containing resin is
less than 45 mg KOH/g, the development of the composition with an
aqueous alkaline solution will be performed only with difficulty.
Conversely, if the acid value exceeds 200 mg KOH/g, the dissolving
out of the exposed area in a developing solution will proceed, the
line width will become narrow unduly, occasionally a coating film
is dissolved out in a developing solution and separated from a
substrate regardless of the exposed area or unexposed area and, as
a result, the formation of a proper resist pattern may be attained
only with difficulty.
[0043] The carboxyl group-containing resin (1) mentioned above is
obtained by the copolymerization of (a) an unsaturated carboxylic
acid and (b) a compound having an unsaturated double bond and is
soluble in an aqueous alkaline solution because it contains the
carboxyl groups.
[0044] As concrete examples of the unsaturated carboxylic acid (a)
mentioned above, acrylic acid, methacrylic acid, itaconic acid,
crotonic acid, maleic acid, fumaric acid, vinylacetic acid, or
anhydrides of these acids; and the reaction product of such an acid
hydride as maleic anhydride, itaconic anhydride, or pyromellitic
anhydride with such a hydroxyl group-containing unsaturated
compound as 2-hydroxyethyl (meth)acrylate or
2-hydroxypropyl(meth)acrylate, and other similar
hydroxyalkyl(meth)acrylates may be cited. These unsaturated
carboxylic acids may be used either singly or in the form of a
combination of two or more members. Among other unsaturated
carboxylic acids mentioned above, acrylic acid and/or methacrylic
acid prove to be desirable. Incidentally, the term "(meth)acrylate"
as used in the present specification refers collectively to
acrylate and methacrylate. This holds good for other similar
expression.
[0045] As concrete examples of the aforementioned compound (b)
having an unsaturated double bond, styrene, chlorostyrene, and
.alpha.-methylstyrene; (meth)acrylates possessing methyl, ethyl,
n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, amyl,
2-ethylhexyl, octyl, capryl, nonyl, dodecyl, hexadecyl, octadecyl,
cyclohexyl, isobornyl, methoxyethyl, butoxyethyl, 2-hydroxyethyl,
2-hydroxypropyl, 3-chloro-2-hydroxypropyl, etc. as substituent(s);
mono(meth)acrylates of polyethylene glycol and mono(meth)acrylates
of polypropylene glycol; vinyl acetate, vinyl butyrate, and vinyl
benzoate; and acrylamide, methacrylamide, N-hydroxymethyl
acrylamide, N-hydroxymethyl methacrylamide, N-methoxymethyl
acrylamide, N-ethoxymethyl acrylamide, N-butoxymethyl acrylamide,
acrylonitrile, vinyl ethers, isobutylene, etc. may be cited. These
compounds may be used either singly or in the form of a combination
of two or more members. Among other compounds mentioned above,
styrene, .alpha.-methylstyrene, lower alkyl(meth)acrylates, and
isobutylene are advantageously used.
[0046] The carboxyl group-containing photosensitive resin (2)
mentioned above is a resin obtained by adding an ethylenically
unsaturated group (b') as a pendant to part of the carboxyl groups
of the copolymer of the above-mentioned unsaturated carboxylic acid
(a) and the unsaturated double bond-containing compound (b)
mentioned above, thereby inducing introduction of the
photosensitive ethylenically unsaturated group into the side chain
of the copolymer. Since the copolymer keeps part of the carboxyl
groups contained therein in the unreacted form, the carboxyl
group-containing photosensitive resin to be obtained is soluble in
an aqueous alkaline solution. The film which is formed of the
photosensitive resin composition containing such a resin,
therefore, permits stable development with an aqueous alkaline
solution after the selective exposure to light.
[0047] As the aforementioned ethylenically unsaturated group (b')
to be added as a pendant, vinyl group, allyl group, acryloyl group,
and methacryloyl group may be cited. As a method of adding such an
ethylenically unsaturated group to the copolymer mentioned above,
the method of adding an ethylenically unsaturated compound having
an epoxy group or (meth)acrylic chloride to the carboxylic group of
the copolymer may be adopted.
[0048] As the ethylenically unsaturated compound having an epoxy
group or (meth)acrylic chloride used herein, glycidyl
(meth)acrylate, allyl glycidyl ether, .beta.-methylglycidyl
(meth)acrylate, chrotonic acid glycidyl ether,
3,4-epoxycyclohexylmethyl(meth)acrylate, (meth)acrylic chloride,
chrotonic chloride, etc. may be cited. Among other compounds
mentioned above, glycidyl(meth)acrylate proves to be desirable.
[0049] The carboxyl group-containing photosensitive resin (3)
mentioned above is a resin obtained by causing the carboxyl group
of (d) an unsaturated monocarboxylic acid to react with the epoxy
group of a copolymer of (c) a compound containing an epoxy group
and an unsaturated double bond in its molecule and (b) the
unsaturated double bond-containing compound mentioned above, at
such a ratio as to improve the photo-curing properties until a
sufficient photo-curing depth is obtained, thereby inducing
introduction of the unsaturated double bond of the above-mentioned
unsaturated monocarboxylic acid into the side chain of the
copolymer, and further causing the esterification reaction of the
resultant secondary hydroxyl group caused by the above addition
reaction with (e) a saturated or unsaturated polybasic acid
anhydride, thereby inducing introduction of the carboxylic group
into the side chain of the resin.
[0050] As concrete examples of the aforementioned compound (c)
containing an epoxy group and an unsaturated double bond in its
molecule, glycidyl(meth)acrylate, .beta.-methylglycidyl
(meth)acrylate, 3,4-epoxycyclohexylmethyl(meth)acrylate, etc. may
be cited. These compounds may be used either singly or in the form
of a combination of two or more members.
[0051] As concrete examples of the unsaturated monocarboxylic acid
(d) mentioned above, acrylic acid, methacrylic acid, crotonic acid,
cinnamic acid, .alpha.-cyanocinnamic acid, .beta.-styryl acrylic
acid, .beta.-furfuryl acrylic acid, etc. may be cited. These
unsaturated monocarboxylic acids may be used either singly or in
the form of a combination of two or more members.
[0052] As concrete examples of the saturated or unsaturated
polybasic acid anhydride (e), succinic anhydride, maleic anhydride,
phthalic anhydride, tetrahydrophthalicanhydride, hexahydrophthalic
anhydride, methylhexahydrophthalic anhydride, itaconic anhydride,
methylendomethylenetetrahydrophthalic anhydride, trimellitic
anhydride, pyromellitic anhydride, etc. may be cited. These
polybasic acid anhydrides may be used either singly or in the form
of a combination of two or more members.
[0053] The carboxyl group-containing photosensitive resin (4)
mentioned above is a resin obtained by causing the acid anhydride
group of a copolymer of an unsaturated double bond-containing acid
anhydride (f) and the unsaturated double bond-containing compound
(b) mentioned above to react with the hydroxyl group of a compound
(g) having a hydroxyl group and an unsaturated double bond to
produce a half ester, thereby inducing introduction of the
unsaturated double bond of the compound (g) mentioned above into
the side chain of the resin.
[0054] As concrete examples of the unsaturated double
bond-containing acid anhydride (f) mentioned above, maleic
anhydride, itaconic anhydride, a partial reaction product of
pyromellitic anhydride with a hydroxyl group-containing unsaturated
compound such as a hydroxyalkyl(meth)acrylate like
2-hydroxyethyl(meth)acrylate and 2-hydroxypropyl (meth)acrylate,
etc. may be cited. These acid anhydrides may be used either singly
or in the form of a combination of two or more members. Among other
acid anhydrides cited above, maleic anhydride is particularly
desirable from the viewpoint of stable synthesis of the
polymer.
[0055] As concrete examples of the compound (g) having a hydroxyl
group and an unsaturated double bond, hydroxyalkyl (meth)acrylates
such as 2-hydroxyethyl(meth)acrylate and
2-hydroxypropyl(meth)acrylate; a hydroxyethyl (meth)acrylate
modified with lactone, etc. may be cited. These compounds may be
used either singly or in the form of a combination of two or more
members.
[0056] The carboxyl group-containing photosensitive resins (2)-(4)
mentioned above excel in photo-curing properties and contribute to
the tack-free dryness of the composition.
[0057] The carboxyl group-containing photosensitive resin (5)
mentioned above is a resin obtained by causing the carboxyl group
of (d) the aforementioned unsaturated monocarboxylic acid to react
with the epoxy group of (h) a polyfunctional epoxy compound to
produce an epoxy acrylate and further causing the esterification
reaction of the resultant secondary hydroxyl group caused by the
above addition reaction with (e) the saturated or unsaturated
polybasic acid anhydride mentioned above, thereby inducing
introduction of the carboxylic group into the side chain of the
resin.
[0058] As concrete examples of the polyfunctional epoxy compound
(h) mentioned above, any epoxy resins may be used. As the typical
examples thereof, bisphenol A type, hydrogenated bisphenol A type,
bisphenol F type, bisphenol S type, phenol novolak type, cresol
novolak type, bisphenol A novolak type, biphenol type, bixylenol
type, N-glycidyl type, and other well known and widely used epoxy
compounds may be cited. As commercially available, preferred
substances, EHPE-3150 produced by Daicel Chemical Industries, Ltd.,
etc. may be cited. Further, the polyfunctional bisphenol type epoxy
resin obtained by reacting the hydroxyl group of a solid bisphenol
type epoxy resin with epihalohydrin such as epichlorohydrin so as
to be polyfunctional may be cited. Among other epoxy compounds,
particularly the use of phenol novolak type epoxy resin, cresol
novolak type epoxy resin, and polyfunctional bisphenol type epoxy
resin which have many epoxy groups and are in a solid state proves
to be desirable.
[0059] These polyfunctional epoxy compounds (h) may be used either
singly or in the form of a combination of two or more members.
[0060] The reaction of the polyfunctional epoxy compound (h) and
the unsaturated monocarboxylic acid (d) mentioned above is
preferred to be effected in such a proportion that the ratio of
equivalent weight of the epoxy group/equivalent weight of the
carboxyl group falls in the range of 0.8 to 1.2, preferably 0.9 to
1.05. If the ratio of equivalent weight of the epoxy
group/equivalent weight of the carboxyl group is less than 0.8, the
problem of smell will arise due to the remaining unsaturated
monocarboxylic acid. Conversely, if the equivalent ratio mentioned
above exceeds 1.2, a large amount of epoxy group will remain, which
will cause the undesired gelation during the subsequent reaction
with the saturated or unsaturated polybasic acid anhydride (e). The
reaction ratio of the saturated or unsaturated polybasic acid
anhydride (e) to the resultant secondary hydroxyl group is adjusted
such that the acid value of the resin obtained in the final stage
falls in the preferred range of 45 to 160 mg KOH/g. In general, the
equivalent weight of the acid anhydride group per one equivalent
weight of the hydroxyl group caused by the reaction of the
polyfunctional epoxy compound (h) and the unsaturated
monocarboxylic acid (d) is in the range of 0.3 to 0.9, preferably
in the range of 0.5 to 0.7.
[0061] The hydroxyl group-containing and carboxyl group-containing
resin (6) mentioned above is a resin obtained by causing (e) the
saturated or unsaturated polybasic acid anhydride to react with (i)
a hydroxyl group-containing polymer and then causing a compound
having an epoxy group and an unsaturated double bond to react with
the part of the resultant carboxyl groups caused by the above
reaction, thereby inducing introduction of the photosensitive group
into the resin. As the hydroxyl group-containing polymer (i),
polyvinyl acetals, cellulose, etc. may be used. By adjusting the
reacting weight of the saturated or unsaturated polybasic acid
anhydride (e), it is possible to use water as a diluent of the
composition and also to use water as a developing solution besides
a dilute aqueous alkaline solution.
[0062] The reaction for the synthesis of the carboxyl
group-containing resin (7) mentioned above is attained by the first
method which comprises causing the aforementioned unsaturated
monocarboxylic acid (d) [or a compound (j) containing in its
molecule at least one alcoholic hydroxyl group and one reactive
group other than the alcoholic hydroxyl group, which can react with
an epoxy group] to react with the aforementioned polyfunctional
epoxy compound (h), then causing the compound (j) containing in its
molecule at least one alcoholic hydroxyl group and one reactive
group other than the alcoholic hydroxyl group, which can react with
an epoxy group [or the unsaturated monocarboxylic acid (d)] to
react with the resultant reaction product, and further causing the
saturated or unsaturated polybasic acid anhydride (e) to react with
the reaction product or by the second method which comprises
causing simultaneous reaction of the polyfunctional epoxy compound
(g), the unsaturated monocarboxylic acid (h), and the compound (j)
containing in its molecule at least one alcoholic hydroxyl group
and one reactive group other than the alcoholic hydroxyl group,
which can react with an epoxy group, and further causing the
saturated or unsaturated polybasic acid anhydride (e) to react with
the reaction product. Though these two methods are both available,
the second method proves to be desirable.
[0063] As concrete examples of the aforementioned compound (j)
containing in its molecule at least one alcoholic hydroxyl group
and one reactive group (such as, for example, a carboxyl group, a
phenolic hydroxyl group, or secondary amino group) other than the
alcoholic hydroxyl group, which can react with an epoxy group, for
example, hydroxymonocarboxylic acids such as glycolic acid,
dimethylol propionic acid, dimethylol acetic acid, dimethylol
butyric acid, dimethylol valeric acid, and dimethylol caproic acid;
alcoholic hydroxyl group-containing phenols such as
(bis)hydroxymethyl phenol, (bis)hydroxymethyl cresol,
p-hydroxyphenyl-2-methanol, p-hydroxyphenyl-3-propanol, and
p-hydroxyphenetyl alcohol; dialkanol amines such as diethanol amine
and diisopropanol amine, etc. may be cited.
[0064] The carboxyl group-containing photosensitive resin (8)
mentioned above uses (1) a polyfunctional oxetane compound instead
of the polyfunctional epoxy resin (h) which is a starting raw
material of the carboxyl group-containing photosensitive resin (5)
mentioned above.
[0065] That is, it is the carboxyl group-containing photosensitive
resin obtained by causing the unsaturated monocarboxylic acid (d)
to react with the polyfunctional oxetane compound (I) and then
causing the saturated or unsaturated polybasic acid anhydride (d)
to preponderantly react with the primary hydroxyl group of the
resultant modified oxetane resin. This resin excels in thermal
stability because the bonded site between the primary hydroxyl
group and the acid anhydride may be thermally broken only with
difficulty.
[0066] By the use of this carboxyl group-containing photosensitive
resin, it is possible to prepare an alkali-developing type
photocurable and thermosetting resin composition which excels in
heat resistance and thermal stability.
[0067] Next, as the photopolymerization initiator (B) having the
oxime linkage represented by the aforementioned general formula
(I), any of the well-known and widely used oxime-based
photopolymerization initiator such as an o-acyl oxime ester
compound, an oxime sulfonate compound, and a ketoxime ether
compound may be used. Preferably, the oxime-based
photopolymerization initiator represented by the following general
formula (II) and having either skeleton of a xanthone skeleton, a
thioxanthone skeleton, or an anthraquinone skeleton may be
cited.
##STR00003##
wherein one or two of R is a group represented by the following
formula (III) and the remainder is a hydrogen atom, a halogen atom,
a methyl group, or a phenyl group, and X represents an oxygen atom,
a sulfur atom, or a carbonyl group.
##STR00004##
wherein R.sup.1 represents a hydrogen atom, a methyl group, a
phenyl group, a biphenyl group, or a phenyl group or biphenyl group
severally substituted by an alkyl group of 1-6 carbon atoms.
[0068] As the particularly preferred initiator among these
compounds, the oxime-based photopolymerization initiator
represented by the following general formula (IV) and having the
thioxanthone skeleton may be cited.
##STR00005##
wherein R.sup.2 represents a methyl group or an ethyl group.
[0069] Since the oxime-based photopolymerization initiator (B)
mentioned above has a pair of unpaired electrons in its nitrogen
atom and exhibits high sensitivity, it is preferable that it should
be incorporated into a formulation which is different from a
formulation into which the above-mentioned carboxyl
group-containing resin (A) and the above-mentioned reactive diluent
(C) are incorporated to formulate a system comprising at least two
parts in view of the stability of properties and the storage
stability.
[0070] Specifically, when the above-mentioned oxime-based
photopolymerization initiator (B) is mixed with an acid
group-containing compound such as the aforementioned carboxyl
group-containing resin (A) and the resultant mixture is left
standing, the photosensitivity of the composition will
significantly decrease or the composition will fail to be
photosensitized and cause gelation due to the generation of
radicals, which will result in the deterioration of various
properties. In order to prevent such deterioration and attain
stability of properties, it is important that the oxime-based
photopolymerization initiator (B) should be incorporated into a
formulation which is different from a formulation into which the
above-mentioned carboxyl group-containing resin (A) is
incorporated. Similarly, it is preferable in view of the storage
stability that the oxime-based photopolymerization initiator should
be incorporated into a formulation which is different from a
formulation into which the above-mentioned carboxyl
group-containing resin (A) and the above-mentioned reactive diluent
(C) both having a reactive functional group are incorporated before
their use and these formulations should be mixed at the time of
use. Accordingly, when the photocurable and thermosetting resin
composition is formulated to a two-part system consisting of
formulations "A" and "B", for example, if the above-mentioned
carboxyl group-containing resin (A) is incorporated into the
formulation "A", it is then preferable that the oxime-based
photopolymerization initiator (B) should be incorporated into the
formulation "B" and the above-mentioned reactive diluent (C) should
be incorporated into the formulation "A".
[0071] These oxime-based photopolymerization initiators (B) may be
used either singly or in the form of a combination of two or more
members. The amount of the aforementioned oxime-based
photopolymerization initiator (B) to be used generally falls in the
range of 0.01 to 20 parts by weight, preferably 0.1 to 10 parts by
weight, based on 100 parts by weight of the aforementioned carboxyl
group-containing resin (A).
[0072] Further, when the alkali-developing type photocurable and
thermosetting resin composition containing the oxime-based
photopolymerization initiator (B) as mentioned above is used on a
copper foil, there is a possibility of producing copper ions, which
are a strong Lewis acid, on the interface between the composition
and the copper foil due to the presence of a carbooxyl group and a
water content. Since such a Lewis acid may decompose the
oxime-based photopolymerization initiator (B) mentioned above and
may cause an undercut of a coating film after the exposure and
development, it is preferred that other photopolymerization
initiator (B-I) and/or sensitizer (B-II) be used in combination
with the oxime-based photopolymerization initiator.
[0073] The other photopolymerization initiator (B-I) which may be
used in combination with the aforementioned oxime-based
photopolymerization initiator (B) in the composition of the present
invention is a radical photopolymerization initiator of the
benzophenone type, acetophenone type, benzoin ether type, ketal
type, acyl phosphine oxide, peroxide type, titanothene type, etc.
As concrete examples of the other photopolymerization initiator
(B-I), for example, benzoin and alkyl ethers thereof such as
benzoin, benzoin methyl ether, benzoin ethyl ether, and benzoin
isopropyl ether; acetophenones such as acetophenone,
2,2-dimethoxy-2-phenyl acetophenone, 2,2-diethoxy-2-phenyl
acetophenone, and 1,1-dichloroacetophenone; aminoacetophenones such
as 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one and
2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1;
anthraquinones such as 2-methylanthraquinone, 2-ethylanthraquinone,
2-t-butyl-anthraquinone, and 1-chloroanthraquinone; thioxanthones
such as 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone,
2-chloro-thioxanthone, 2-isopropylthioxanthone, and
4-isopropylthioxanthone; ketals such as acetophenone dimethyl ketal
and benzyl dimethyl ketal; benzophenones such as benzophenone; or
xanthones; acyl phosphine oxides such as
(2,6-dimethoxybenzoyl)-2,4,4-pentyl phosphine oxide,
bis(2,4,6-trimethylbenzoyl)-phenyl phosphine oxide,
2,4,6-trimethylbenzoyl-diphenyl phosphine oxide, and
ethyl-2,4,6-trimethylbenzoyl-phenyl phosphinate; various peroxides,
etc. may be cited. These well-known and widely used
photopolymerization initiators may be used either singly or in the
form of a combination of two or more members. The amount of the
photopolymerization initiator (B-I) to be incorporated into the
composition is preferred to be in the range of 0.1 to 10 parts by
weight, based on 100 parts by weight of the aforementioned carboxyl
group-containing resin (A).
[0074] As the sensitizer (B-II) to be used in combination with the
photopolymerization initiator (Band B-I) mentioned above, tertiary
amines like ethyl N,N-(dimethylamino) benzoate, isoamyl
N,N-(dimethylamino)benzoate, pentyl-4-dimethylaminobenzoate,
triethylamine, triethanolamine, etc. may be cited. These
sensitizers may be used either singly or in the form of a
combination of two or more members.
[0075] Further, such a titanothene type photopolymerization
initiator as the product of Ciba Specialty Chemicals K.K., Irgacure
784, which initiates radical polymerization in a visible region, a
leuco-dye, etc. may be optionally used as a curing aid in
combination with the above photopolymerization initiator.
[0076] The reactive diluent (C) to be used in the photocurable and
thermosetting resin composition of the present invention is used
for the purpose of adjusting the viscosity of the composition
thereby improving the workability thereof and increasing the
crosslink density thereby obtaining a coating film possessed of
adhesiveness etc. As such a reactive diluent (C), any compounds
having at least one unsaturated double bond in its molecule, for
example, alkyl(meth)acrylates such as 2-ethylhexyl(meth)acrylate
and cyclohexyl(meth)acrylate; hydroxyalkyl(meth)acrylates such as
2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl(meth)acrylate;
mono- or di-(meth)acrylates of alkylene oxide derivatives such as
ethylene glycol, propylene glycol, diethylene glycol, and
dipropylene glycol; polyfunctional (meth)acrylates of polyhydric
alcohols such as hexane diol, trimethylol propane, pentaerythritol,
ditrimethylol propane, dipentaerythritol, and tris-hydroxyethyl
isocyanurate, and ethylene oxide adducts or propylene oxide adducts
of these polyhydric alcohols; (meth)acrylates of ethylene oxide
adducts or propylene oxide adducts of phenols such as phenoxyethyl
(meth)acrylate and polyethoxy di(meth)acrylate of bisphenol A;
(meth)acrylates of glycidyl ethers such as glycerin diglycidyl
ether, trimethylol propane triglycidyl ether, and triglycidyl
isocyanurate; melamine(meth)acrylate, etc. may be cited. Among
these compounds, a liquid reactive diluent proves to be desirable
from the viewpoint of reactivity and diluting ability.
[0077] Further, a compound having an unsaturated double bond and
also a carboxyl group in its molecule may be used as the reactive
diluent (C). As such compounds, the reaction products of a
saturated or unsaturated dibasic acid anhydride with a
(meth)acrylate having one hydroxyl group in its molecule, for
example, half esters obtained by causing a saturated or unsaturated
dibasic acid anhydride, such as succinic anhydride, maleic
anhydride, phthalic anhydride, tetrahydrophthalic anhydride,
hexahydrophthalic anhydride, methylhexahydrophthalic anhydride,
methyltetrahydrophthalic anhydride, itaconic anhydride, and
methylendomethylene tetrahydrophthalic anhydride, to react in an
equimolar ratio with a (meth)acrylate having one hydroxyl group in
its molecule, such as hydroxyethyl(meth)acrylate,
hydroxypropyl(meth)acrylate, hydroxybutyl(meth)acrylate,
polyethylene glycol mono(meth)acrylate, glycerin di(meth)acrylate,
trimethylol propane di(meth)acrylate, pentaerythritol tri(meth)
acryalte, dipentaerythritol penta(meth)acrylate, and (meth)acrylate
of phenyl glycidyl ether, may be used.
[0078] These reactive diluents (C) may be used either singly or in
the form of a combination of two or more members. The preferred
amount thereof to be used is in the range of 2 to 50 parts by
weight, based on 100 parts by weight of the carboxyl
group-containing resin (A) mentioned above. If the amount of the
reactive diluent (C) is less than the lower limit of the above
range, the shortage will tend to induce insufficient curing and
reduced sensitivity of a coating film. Conversely, if the amount is
unduly large so as to exceed the above range, the composition will
be at a disadvantage in reducing the tack-free dryness of a coating
film and render the cured coating film brittle.
[0079] Though the photocurable and thermosetting resin composition
of the present invention does not always require to use an organic
solvent because it uses the reactive diluent (C) mentioned above,
it may incorporate an organic solvent for the purpose of adjusting
the viscosity of itself or for dissolving the aforementioned
carboxyl group-containing resin therein to prepare a varnish. As
the organic solvent, a solvent which makes the composition to be
easily dried and exhibit slow toxicity is selected. For example,
alcohols such as methanol, ethanol, propyl alcohol, isopropyl
alcohol, butanol, and isobutanol; acetates such as ethyl acetate,
butyl acetate, amyl acetate, cyclohexyl acetate, methyl
acetoacetate, dimethyl adipate, dimethyl glutamate, and dimethyl
succinate; ketones such as cyclohexanone, methyl cyclohexanone,
2-butanone, methyl isobutyl ketone, and acetone; alkylene oxide
derivatives such as ethylene glycol monomethyl ether acetate,
ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl
ether acetate, ethylene glycol monomethyl ether, ethylene glycol
monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol
dimethyl ether, ethylene glycol diethyl ether, ethylene glycol
dibutyl ether, diethylene glycol monomethyl ether acetate,
diethylene glycol monoethyl ether acetate, diethylene glycol
monobutyl ether acetate, diethylene glycol monomethyl ether,
diethylene glycol monoethyl ether, diethylene glycol monobutyl
ether, diethylene glycol dimethyl ether, diethylene glycol diethyl
ether, diethylene glycol dibutyl ether, propylene glycol monomethyl
ether acetate, propylene glycol monomethyl ether, propylene glycol
monobutyl ether, dipropylene glycol monomethyl ether acetate, and
dipropylene glycol monomethyl ether; toluene, mineral spirit, etc.
may be suitably used. These organic solvents may be used either
singly or in the form of a mixture of two or more members.
[0080] As the aforementioned epoxy compound (D) having two or more
epoxy groups in its molecule, any polyfunctional epoxy compounds
which have been heretofore known in the art may be used. For
example, any epoxy compounds having two or more epoxy groups in its
molecule such as bisphenol A type epoxy resins represented by
EPIKOTE 828, EPIKOTE 834, EPIKOTE 1001, and EPIKOTE 1004 produced
by Japan Epoxy Resin K.K., EPICLON 840, EPICLON 850, EPICLON 1050,
and EPICLON 2055 produced by Dainippon Ink and Chemicals Inc., Epo
Tohto YD-011, YD-013, YD-127, and YD-128 produced by Tohto Kasei
Co., Ltd., and Sumi-epoxy ESA-011, ESA-014, ELA-11S, and ELA-128
produced by Sumitomo Chemical Co., Ltd. (all trade names);
brominated epoxy resins represented by EPIKOTE YL903 produced by
Japan Epoxy Resin K.K., EPICLON 152 and EPICLON 165 produced by
Dainippon Ink and Chemicals Inc., Epo Tohto YDB-400 and YDB-500
produced by Tohto Kasei Co., Ltd., and Sumi-epoxy ESB-400 and
ESB-700 produced by Sumitomo Chemical Co., Ltd. (all trade names);
novolak type epoxy resins represented by EPIKOTE 152 and EPIKOTE
154 produced by Japan Epoxy Resin K.K., EPICLON N-730, EPICLON
N-770, and EPICLON N-865 produced by Dainippon Ink and Chemicals
Inc., Epo Tohto YDCN-701 and YDCN-704 produced by Tohto Kasei Co.,
Ltd., EPPN-201, EOCN-1025, EOCN-1020, EOCN-104S, and RE-306
produced by Nippon Kayaku Co., Ltd., and Sumi-epoxy ESCN-195.times.
and ESCN-220 produced by Sumitomo Chemical Co., Ltd. (all trade
names); bisphenol F type epoxy resins represented by EPICLON 830
produced by Dainippon Ink and Chemicals Inc., EPIKOTE 807 produced
by japan Epoxy Resin K.K., and Epo Tohto YDF-170, YDF-175, and
YDF-2004 produced by Tohto Kasei Co., Ltd. (all trade names);
hydrogenated bisphenol A type epoxy resins represented by Epo Tohto
ST-2004, ST-2007, and ST-3000 produced by Tohto Kasei Co., Ltd.
(all trade names); glycidylamine type epoxy resins represented by
EPIKOTE 604 produced by Japan Epoxy Resin K.K., Epo Tohto YH-434
produced by Tohto Kasei Co., Ltd., and Sumi-epoxy ELM-120 produced
by Sumitomo Chemical Co., Ltd. (all trade names); alicyclic epoxy
resins represented by Celloxide 2021 (trade name) produced by
Daicel Chemical Industries, Ltd.; trihydroxyphenyl methane type
epoxy resins represented by YL-933 produced by Japan Epoxy Resin
K.K. and EPPN-501 and EPPN-502 produced by Nippon Kayaku Co., Ltd.
(all trade names); bixylenol type or biphenol type epoxy resins or
mixtures thereof represented by YL-6056, YX-4000, and YL-6121
produced by Japan Epoxy Resin K.K. (all trade names); bisphenol S
type epoxy resins represented by EBPS-200 produced by Nippon Kayaku
Co., Ltd., EPX-30 produced by Asahi Denka Kogyo K.K., and EXA-1514
produced by Dainippon Ink and Chemicals Inc. (all trade names);
bisphenol A novolak type epoxy resins represented by EPIKOTE 157S
(trade name) produced by Japan Epoxy Resin K.K.; tetraphenylol
ethane type epoxy resins represented by EPIKOTE YL-931 (trade name)
produced by Japan Epoxy Resin K.K.; heterocyclic epoxy resins
represented by TEPIC (trade name) produced by Nissan Chemical
Industries Ltd.; diglycidyl phthalate resin represented by BLEMMER
DGT (trade name) produced by Nippon Oil and Fats Co., Ltd.;
tetraglycidyl xylenoyl ethane resins represented by ZX-1063 (trade
name) produced by Tohto Kasei Co., Ltd.; naphthalene
group-containing epoxy resins represented by ESN-190 and ESN-360
produced by Shinnittetsu Chemical Co., Ltd. and HP-4032, EXA-4750,
and EXA-4700 produced by Dainippon Ink and Chemicals Inc. (all
trade names); dicyclopentadiene skeleton-containing epoxy resins
represented by HP-7200 and HP-7200H produced by Dainippon Ink and
Chemicals Inc. (all trade names); glycidyl methacrylate copolymer
type epoxy resins represented by CP-50S and CP-50M produced by
Nippon Oil and Fats Co., Ltd. (all trade names); copolymeric epoxy
resin of cyclohexylmaleimide and glycidyl methacrylate, etc. may be
cited. These epoxy compounds may be used either singly or in the
form of a combination of two or more members. The amount of the
aforementioned polyfunctional epoxy compound (D) to be incorporated
in the composition as a thermosetting component is desired to be in
such a ratio that the epoxy group is in the range of 0.6 to 2.0
equivalent weights, preferably 0.8 to 1.6 equivalent weights per
one equivalent weight of the carboxyl group of the aforementioned
carboxyl group-containing resin (A). The ratio of the epoxy group
less than 0.6 equivalent weight is not preferred because the
carboxyl groups will remain and the resistance to alkalis and
electrical insulating properties of a coating film will be
degraded. Conversely, the ratio of the epoxy group exceeding 2.0
equivalent weights is not preferred because the excess epoxy resin
functions as a plasticizing agent and, as a result, the strength of
a coating film will be degraded.
[0081] Further, as an accelerator for the reaction of the
polyfunctional epoxy compound (D) mentioned above with the
aforementioned carboxyl group-containing resin (A), a well-known
epoxy curing promotor such as amines, dicyandiamide, urea
derivatives, melamine, S-triazine compounds, guanamine compounds,
and imidazole compounds such as 2-ethyl-4-methylimidazole may be
used in combination therewith. By effecting the thermal curing of
the above components in the presence of the above-mentioned
accelerator, it is possible to improve various properties of a
cured coating film such as heat resistance, resistance to
chemicals, adhesiveness, and pencil hardness.
[0082] The photocurable and thermosetting resin composition of the
present invention may further incorporate therein an inorganic
filler and/or an organic filler (E) for the purpose of improving
the properties thereof. As the inorganic filler, any well-known and
widely used inorganic fillers such as barium sulfate, barium
titanate, finely powdered silicon oxide, amorphous silica,
crystalline silica, fused silica, talc, clay, magnesium carbonate,
calcium carbonate, aluminum oxide, aluminum hydroxide, and mica
power may be used. The amount of the inorganic filler to be used is
desired to be in the ratio of 0 to 60% by weight, more preferably 5
to 40% by weight of the composition of the present invention.
[0083] As the organic filler, any particles of a macromolecular
compound such as an epoxy-based, rubber-based, acryl-based,
urethane-based, polyimide-based, or polyamide-based macromolecular
compound may be used. The particle size thereof is preferred to be
not more than 10 .mu.m. The organic filler may be incorporated in
the composition of the present invention in the ratio of 0 to 30%
by weight of the composition.
[0084] The photocurable and thermosetting resin composition of the
present invention may further incorporate therein, when necessary,
a well-known and widely used additive such as a well-known and
widely used coloring pigment like phthalocyanine blue,
phthalocyanine green, Iodine Green, disazo yellow, crystal violet,
titanium dioxide, carbon black, and naphthalene black; a well-known
and widely used polymerization inhibitor like hydroquinone,
hydroquinone monomethyl ether, t-butyl catechol, pyrogallol, and
phenothiazine; a well-known and widely used thickening agent like
asbestos, organic bentonite, benton, and montomorillonite; an
anti-foaming agent and/or leveling agent of a silicone type, a
fluorine type, and a macromolecular type; an adhesiveness-imparting
agent of a imidazole type, a thiazole type, a triazole type, and a
silane coupling agent, or the like.
[0085] By using the photocurable and thermosetting resin
composition containing the aforementioned components in the way as
mentioned below, it is possible to provide a printed circuit board
having a solder resist layer and/or a resin insulating layer formed
thereon.
[0086] The photocurable and thermosetting resin composition of the
present invention is adjusted, when necessary, to a level of
viscosity suitable for a particular coating method, for example,
applied to a substrate by a dip coating method, a flow coating
method, a roll coating method, abarcoater method, a screen printing
method, a curtain coating method, or the like, and then dried at a
temperature in the approximate range of 60 to 100.degree. C. to
expel by evaporation the organic solvent contained in the
composition (preliminary drying) to produce a tack-free coating
film. Further, a resin insulating layer may be formed by applying
the composition mentioned above to a plastic film, drying the
composition, winding the film, and then laminating the coating film
on a substrate. Thereafter, the coating film is selectively exposed
to an actinic ray through a photomask having a prescribed pattern
by a contact method (or non-contact method) and the unexposed area
of the coating film is developed with a dilute aqueous alkaline
solution (such as, for example, an aqueous solution of about 0.3 to
3% sodium carbonate) to form a resist pattern. Further, the
photo-cured coating film may be thermally cured by heating to a
temperature in the approximate range of 140 to 180.degree. C., for
example. Since the reaction of the carboxyl group of the
aforementioned carboxyl group-containing resin (A) with the epoxy
group of the aforementioned epoxy compound (D) having two or more
epoxy groups in its molecule takes place in this thermal treatment,
it is possible to form a cured coating film which excels in various
properties such as resistance to heat, resistance to solvents,
resistance to acids, resistance to moisture absorption, PCT
resistance, adhesiveness, and electrical properties.
[0087] The light sources which are properly used for the purpose of
photo-curing the composition include a low-pressure mercury lamp, a
medium-pressure mercury lamp, a high-pressure mercury lamp, an
ultra-high-pressure mercury lamp, a xenon lamp, and a metal halide
lamp. Further, the laser source may also be utilized as the actinic
ray for exposure of the film in the direct imaging technique to
directly form the image.
[0088] As a dilute aqueous alkaline solution to be used in the
process of development mentioned above, aqueous alkaline solutions
of potassium hydroxide, sodium hydroxide, sodium carbonate,
potassium carbonate, sodium silicate, ammonia, amines, etc. may be
used. Among other aqueous alkaline solutions, sodium carbonate
proves to be particularly preferable.
[0089] Now, the present invention will be described more
specifically below with reference to a synthesis example, working
examples, and comparative examples. As a matter of course, the
following Examples are in any sense restrictive of the present
invention. Wherever the terms "parts" and "%" are used hereinbelow,
they shall refer to "parts by weight" and "% by weight" unless
otherwise specified.
Synthesis Example 1
Synthesis of Carboxyl Group-Containing Photosensitive Resin
[0090] Into a three-necked flask equipped with a thermometer, a
stirrer, a dropping funnel, and a reflux condenser, 217 g (1.0
equivalent weight) of cresol novolak type epoxy resin of which
epoxy equivalent is 217 and which contains seven phenol skeleton
residues in average per one molecule and also epoxy groups and
204.8 g of carbitol acetate were charged and they were molten by
heating. To this mixture, 0.2 g of hydroquinone as a polymerization
inhibitor and 1.0 g of triphenyl phosphine as a catalyst were
added. To the resultant mixture, 72.0 g (1.0 equivalent weight) of
acrylic acid was gradually added and they were left reacting for 16
hours at 85-105.degree. C. To the resultant reaction product, 91.2
g (0.67 equivalent weight) of tetrahydrophthalic anhydride was
further added to effect the addition reaction. The varnish obtained
as described above was a viscous liquid containing 35 parts of
carbitol acetate and confirmed to be a carboxyl group-containing
photosensitive resin having an acid value of 65 mg KOH/g as a
mixture.
Example 1
A Composition Containing the Component (B) Added to a Formulation
Separated from that Containing the Components (A) and (C)
[0091] A composition was prepared by compounding 100 parts of the
carboxyl group-containing photosensitive resin as the component (A)
obtained in Synthesis Example 1 with 10 parts of dipentaerythritol
hexaacrylate as the component (C), 1 part of an anti-foaming agent
(AC-300 produced by Kyoeisha Chemical Co., Ltd.), 80 parts of
barium sulfate, and 0.5 part of phthalocyanine green and then
mixing and dispersing the resultant mixture with a three-roll mill.
This composition is hereinafter referred to as liquid "A". Another
composition was prepared by compounding 5 parts of the
photopolymerization initiator as the component (B) having the oxime
linkage and represented by the aforementioned formula (IV) wherein
R.sup.2 is methyl group with 1 part of diethyl thioxanthone
(Kayacure DETX-S produced by Nippon Kayaku Co., Ltd.) as the
component (B-I), 2.5 parts of ethyl 4-dimethylaminobenzoate
(Kayacure EPA produced by Nippon Kayaku Co., Ltd.) as the component
(B-II), and 20 parts of cresol novolak type epoxy resin (EOCN 1020
produced by Nippon Kayaku Co., Ltd.) and 10 parts of bisphenol A
type epoxy resin (EPIKOTE 828 produced by Japan Epoxy Resin K.K.)
both as the component (D) and then mixing and dispersing the
resultant mixture with a three-roll mill.
[0092] This composition is hereinafter referred to as liquid "B".
In this way, the liquid "A" and the liquid "B" of a photocurable
and thermosetting resin composition were prepared.
Example 2
A Composition Containing the Component B Added to a Formulation
Separated from that Containing the Components A and C
[0093] The liquid "A" and the liquid "B" of a photocurable and
thermosetting resin composition were prepared under the conditions
of the same formulations and the same procedures as used in Example
1 except that diethyl thioxanthone as the component (B-I) and ethyl
4-dimethylaminobenzoate as the component (B-II) were not used.
Comparative Example 1
A Composition Including a Formulation to Which the Component B was
Added Together with the Component A
[0094] A composition was prepared by compounding 100 parts of the
carboxyl group-containing photosensitive resin as the component (A)
obtained in Synthesis Example 1 with 5 parts of the
photopolymerization initiator as the component (B) having the oxime
linkage and represented by the aforementioned formula (IV) wherein
R.sup.2 is methyl group, 1 part of diethyl thioxanthone (Kayacure
DETX-S produced by Nippon Kayaku Co., Ltd.) as the component (B-I),
2.5 parts of ethyl 4-dimethylaminobenzoate (Kayacure EPA produced
by Nippon Kayaku Co., Ltd.) as the component (B-II), 1 part of an
anti-foaming agent (AC-300 produced by Kyoeisha Chemical Co.,
Ltd.), 80 parts of barium sulfate, and 0.5 part of phthalocyanine
green and then mixing and dispersing the resultant mixture with a
three-roll mill. This composition is hereinafter referred to as
liquid "A". Another composition was prepared by compounding 10
parts of dipentaerythritol hexaacrylate as the component (C) with
20 parts of cresol novolak type epoxy resin (EOCN 1020 produced by
Nippon Kayaku Co., Ltd.) and 10 parts of bisphenol A type epoxy
resin (EPIKOTE 828 produced by Japan Epoxy Resin K.K.) both as the
component (D) and then mixing and dispersing the resultant mixture
with a three-roll mill. This composition is hereinafter referred to
as liquid "B". In this way, the liquid "A" and the liquid "B" of a
photocurable and thermosetting resin composition were prepared.
Comparative Example 2
A Composition to Which the Component B was Added Together with the
Component A and the Component C
[0095] A photocurable and thermosetting resin composition of
one-pack type was prepared by compounding 100 parts of the carboxyl
group-containing photosensitive resin as the component (A) obtained
in Synthesis Example 1 with 5 parts of the photopolymerization
initiator as the component (B) having the oxime linkage and
represented by the aforementioned formula (IV) wherein R.sup.2 is
methyl group, 1 part of diethyl thioxanthone (Kayacure DETX-S
produced by Nippon Kayaku Co., Ltd.) as the component (B-I), 2.5
parts of ethyl 4-dimethylaminobenzoate (Kayacure EPA produced by
Nippon Kayaku Co., Ltd.) as the component (B-II), 1 part of an
anti-foaming agent (AC-300 produced by Kyoeisha Chemical Co.,
Ltd.), 80 parts of barium sulfate, 0.5 part of phthalocyanine
green, 10 parts of dipentaerythritol hexaacrylate as the component
(C), 20 parts of cresol novolak type epoxy resin (EOCN 1020
produced by Nippon Kayaku Co., Ltd.) and 10 parts of bisphenol A
type epoxy resin (EPIKOTE 828 produced by Japan Epoxy Resin K.K.)
both as the component (D) and then mixing and dispersing the
resultant mixture with a three-roll mill.
Comparative Example 3
A Composition Using an Initiator Other Than the Oxime-Based
Photopolymerization Initiator
[0096] The liquid "A" and the liquid "B" of a photocurable and
thermosetting resin composition were prepared under the conditions
of the same formulations and the same procedures as used in
Comparative Example 1 except that 5 parts of
2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one
(Irgacure 907 produced by Ciba Specialty Chemicals K.K.) was used
instead of 5 parts of the photopolymerization initiator as the
component (B) having the oxime linkage and represented by the
aforementioned formula (IV) wherein R.sup.2 is methyl group.
[0097] The photocurable and thermosetting resin compositions
obtained in Examples 1, 2 and Comparative Examples 1-3 were kept in
a thermostatic chamber at 20.degree. C. or 50.degree. C. for three
days. Thereafter, with respect to the photocurable and
thermosetting resin compositions obtained in Examples 1, 2 and
Comparative Examples 1, 3, the liquid "A" and the liquid "B" of
respective compositions were thoroughly mixed.
[0098] After storage under the conditions mentioned above, each of
the photocurable and thermosetting resin compositions of Examples
1, 2 and Comparative Examples 1-3 was applied by the screen
printing method to the entire surface of a copper-clad laminate of
a glass-epoxy substrate laminated with a copper foil (35 .mu.m
thickness) and to the entire surface of a printed circuit board
prepared from this copper-clad laminate and having a prescribed
pattern formed in advance by etching. Thereafter, the coating film
was dried in a hot air circulating drying oven, irradiated with
ultraviolet light at a dose of 300 mJ/cm.sup.2 through a prescribed
negative film tightly superposed on the coating film, then
developed for 60 seconds with an aqueous 1.0 wt. % sodium carbonate
solution, and thermally cured in a hot air circulating drying oven
at 150.degree. C. for 60 minutes to obtain a cured coating film.
With respect to the properties of each of the resultant cured
coating films, the results of respective Examples are shown in
Table 1 and those of respective Comparative Examples are shown in
Table 2. The properties of each cured coating film were evaluated
by the following methods.
[0099] (1) Developability:
[0100] Each coating film which had undergone the preliminary drying
was developed without subjecting to the exposure to evaluate the
presence or absence of undeveloped residue.
[0101] .largecircle.: Developable
[0102] X: Undevelopable
[0103] (2) Sensitivity:
[0104] A step tablet, Kodak No. 2 was placed on each coating film
which had undergone the preliminary drying. The coating film was
then exposed to light at a dose of 300 mJ/cm.sup.2 by using an
exposure device equipped with an ultra-high-pressure mercury lamp
and then developed. Thereafter, the sensitivity was evaluated based
on the number of steps obtained from the step tablet.
[0105] Numerical value: Number of steps obtained
[0106] X: A cured coating film was not obtained after
development.
[0107] (3) Resolution:
[0108] Each coating film which had undergone the preliminary drying
was exposed to light through a prescribed negative pattern of the
line of 50-130 .mu.m at a dose of 300 mJ/cm.sup.2 by using an
exposure device equipped with an ultra-high-pressure mercury lamp
and then developed. Thereafter, the formed line of the smallest
width was read out to evaluate the resolution characteristics.
[0109] (4) Adhesiveness:
[0110] In accordance with the testing method specified in JIS
(Japanese Industrial Standard) D-0202, the cured coating film of
each test piece was incised like cross-cut in the shape of squares
in a go board to form 100 cut portions and then subjected to a peel
test with a cellophane adhesive tape to visually examine the
separated portions of the film.
[Unpeeled portions]/100
[0111] (5) Resistance to Soldering Heat:
[0112] In accordance with the testing method specified in JIS
C-6481, a cycle of the test in which each test piece having the
cured coating film was immersed for 10 seconds in a solder bath set
in advance at 260.degree. C. and then subjected to a peel test with
a cellophane adhesive was repeated three times. After completion of
the test of three cycles, the state of the coating film was
evaluated.
[0113] .largecircle.: Absence of any discernible change was found
in the coating film even after three-cycle test.
[0114] X: Peeling of the coating film was found after three-cycle
test.
[0115] (6) Resistance to Electroless Plating:
[0116] Each test piece was plated successively in an electroless
nickel plating bath and an electroless gold plating bath, both
available in the market, under the conditions of 0.5 .mu.m of
nickel and 0.03 .mu.m of gold and then subjected to a peel test
with a cellophane adhesive tape to determine whether or not the
cured coating film was peeled and whether or not the cured coating
film had been infiltrated with the plating medium.
[0117] .largecircle.: Absolutely no peeling of the cured coating
film observed.
[0118] .DELTA.: Slight peeling of the cured coating film
observed.
[0119] X: Peeling of the cured coating film observed.
[0120] (7) LDI (Laser Direct Imaging) Sensitivity:
[0121] A step tablet, Kodak No. 2 was tightly superposed on each
coating film which had undergone the preliminary drying. The
coating film was then exposed to light by using an exposure device
equipped with a laser source capable of irradiating a
multi-wavelength of 350 nm and 366 nm at such a dose that the
accumulation dose of 350 nm reaches 60 mJ/cm.sup.2 and then
developed. Thereafter, the sensitivity was evaluated based on the
number of steps obtained from the step tablet.
[0122] Numerical value: Number of steps obtained
[0123] X: A cured coating film was not obtained after
development.
TABLE-US-00001 TABLE 1 Example 1 Example 2 Conditions for left
standing 20.degree. C., 50.degree. C., 20.degree. C., 50.degree.
C., 3 days 3 days 3 days 3 days Drying period (80.degree. C.) 30 60
30 60 30 60 30 60 min. min. min. min. min. min. min. min.
Developability .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. Sensitivity 10 10 10 10 9 9 9 8 (step) Resolution 50
50 50 50 50 50 50 50 Adhesiveness 100/100 100/100 100/100 100/100
100/100 100/100 100/100 100/100 Resistance to .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. soldering heat Resistance
to .largecircle. .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. .largecircle. electroless
plating LDI sensitivity 6 6 6 6 6 6 6 5
TABLE-US-00002 TABLE 2 Comparative Example 1 Comparative Example 2
Comparative Example 3 Conditions for left standing 20.degree. C.,
50.degree. C., 20.degree. C., 50.degree. C., 20.degree. C.,
50.degree. C., 3 days 3 days 3 days 3 days 3 days 3 days Drying
period (80.degree. C.) 30 60 30 60 30 60 30 60 30 60 30 60 min.
min. min. min. min. min. min. min. min. min. min. min.
Developability .largecircle. .largecircle. .largecircle.
.largecircle. .largecircle. .largecircle. X X .largecircle.
.largecircle. .largecircle. .largecircle. Sensitivity 8 5 1 X 8 X
-- -- 5 5 5 5 (step) Resolution 50 50 50 -- 80 -- -- -- 100 100 100
100 Adhesiveness 100/100 100/100 60/100 -- 100/100 -- -- -- 100/100
100/100 100/100 100/100 Resistance to .largecircle. .largecircle. X
-- .largecircle. -- -- -- .largecircle. .largecircle. .largecircle.
.largecircle. soldering heat Resistance to .largecircle. .DELTA. X
-- .largecircle. -- -- -- .largecircle. .largecircle. .largecircle.
.largecircle. electroless plating LDI sensitivity 4 2 X X 4 X -- --
1 1 1 1
[0124] As being clear from the results shown in Tables 1 and 2,
Comparative 1 including the formulation to which the component (B)
was added together with the component (A) exhibited poor storage
stability as compared with Examples 1 and 2. Further, Comparative 2
including the formulation to which the component (B) was added
together with the component (A) and the component (C) exhibited
more poor storage stability than that of Comparative Example 1.
Incidentally, though Comparative Example 3 using the components
(B-I) and (B-II) instead of the component (B) as a
photopolymerization initiator had no problem in storage stability
but was inferior in sensitivity and resolution.
[0125] While certain specific working examples have been disclosed
herein, the invention may be embodied in other specific forms
without departing from the spirit or essential characteristics
thereof. The described examples are therefore to be considered in
all respects as illustrative and not restrictive, the scope of the
invention being indicated by the appended claims rather than by the
foregoing description and all changes which come within the meaning
and range of equivalency of the claims are, therefore, intended to
be embraced therein.
[0126] The photocurable and thermosetting resin composition
according to the present invention is useful in the formation of
solder resist layers and/or resin insulating layers of printed
circuit boards or multi-layer printed circuit boards. Further, it
may be used in the laser direct imaging technique.
[0127] The International Application PCT/JP03/15187, filed Nov. 27,
2003, describes the invention described hereinabove and claimed in
the claims appended hereinbelow, the disclosure of which is
incorporated here by reference.
* * * * *