U.S. patent application number 11/384091 was filed with the patent office on 2006-09-21 for manufacturing method of inkjet head, and adhesive agent composition.
This patent application is currently assigned to KONICA MINOLTA HOLDINGS, INC.. Invention is credited to Sadatoshi Nishibuchi, Hiroyuki Nomori, Hajime Tanisho, Tomomi Yoshizawa.
Application Number | 20060207720 11/384091 |
Document ID | / |
Family ID | 37009083 |
Filed Date | 2006-09-21 |
United States Patent
Application |
20060207720 |
Kind Code |
A1 |
Yoshizawa; Tomomi ; et
al. |
September 21, 2006 |
Manufacturing method of inkjet head, and adhesive agent
composition
Abstract
Disclosed are an adhesive agent composition which has high
chemical resistance and solvent resistance and is curable at around
room temperature, an inkjet head which has good durability and
jetting performance even in the case of using solvent ink, and a
manufacturing method of the inkjet head. For these characteristics,
the adhesive agent composition contains, as an activator, an
imidazole derivative in which an alkyl group or a substituted alkyl
group is substituted at the 1-postion or at the 1- and 2-positions,
and as a base, a compound having three or more epoxy groups.
Inventors: |
Yoshizawa; Tomomi; (Tokyo,
JP) ; Nomori; Hiroyuki; (Tokyo, JP) ;
Nishibuchi; Sadatoshi; (Tokyo, JP) ; Tanisho;
Hajime; (Osaka, JP) |
Correspondence
Address: |
FRISHAUF, HOLTZ, GOODMAN & CHICK, PC
220 Fifth Avenue
16TH Floor
NEW YORK
NY
10001-7708
US
|
Assignee: |
KONICA MINOLTA HOLDINGS,
INC.
Tokyo
JP
HANNA CHEMICAL INDUSTRY CO., LTD.
Higashiosaka-shi
JP
|
Family ID: |
37009083 |
Appl. No.: |
11/384091 |
Filed: |
March 17, 2006 |
Current U.S.
Class: |
156/325 ;
156/330 |
Current CPC
Class: |
B41J 2/1609 20130101;
B41J 2/1623 20130101; C08G 59/3218 20130101; C08G 59/686 20130101;
B41J 2/1612 20130101; C09J 163/00 20130101; C08G 59/3227 20130101;
C08G 59/4042 20130101 |
Class at
Publication: |
156/325 ;
156/330 |
International
Class: |
C09J 163/00 20060101
C09J163/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 18, 2005 |
JP |
2005-079552 |
Mar 18, 2005 |
JP |
2005-079570 |
Dec 1, 2005 |
JP |
2005-347811 |
Dec 19, 2005 |
JP |
2005-364691 |
Feb 14, 2006 |
JP |
2006-036571 |
Claims
1. A method of manufacturing an inkjet head, comprising: adhering
members constituting the inkjet head together by using an adhesive
agent composition, wherein the adhesive agent composition contains,
as an activator, an imidazole derivative in which an alkyl group or
a substituted alkyl group is substituted at a 1-position or at 1-
and 2-positions, contains a compound having three or more epoxy
groups as a base, and is cured at 60.degree. C. or less, thereby
adhering the members together.
2. The method of claim 1, wherein a difference in linear thermal
expansion coefficient between the members is 12 ppm/K or more.
3. The method of claim 1, wherein the adhesive agent composition
contacts ink after being cured.
4. The method of claim 1, wherein the adhesive agent composition
further contains bisphenol A type epoxy resin or bisphenol F type
epoxy resin as a compound having two epoxy groups.
5. The method of claim 1, wherein, in the adhesive agent
composition, an epoxy equivalent of the compound having three or
more epoxy groups is 120 or less.
6. The method of claim 1, wherein, in the adhesive agent
composition, the compound having three or more epoxy groups is a
compound represented by a following general formula (1): ##STR5##
where R.sub.1 to R.sub.3 are hydrogen, an alkyl group, or a
substituted alkyl group, and R.sub.4 is hydrogen, an alkyl group,
an alkoxy group, alkyl amino group, substituted alkyl amino group
or a substituted alkoxy group.
7. The method of claim 1, wherein, in the adhesive agent
composition, the compound having three or more epoxy groups is a
compound represented by a following general formula (2): ##STR6##
where R.sub.1 and R.sub.2 are hydrogen, an alkyl group, or a
substituted alkyl group.
8. The method of claim 4, wherein the compound having two epoxy
groups is bisphenol F type epoxy resin, in the base, the compound
having two epoxy groups is contained by 20 to 90% by mass, and the
compound having three epoxy groups is contained by 10 to 80% by
mass, and 6 parts by mass or more of the activator is mixed with
respect to 100 parts by mass of the base.
9. The method of claim 1, wherein the base further contains a
compound having two epoxy groups, the compound having two epoxy
groups is contained by 20 to 90% by mass in the base, and the
compound having three or more epoxy groups is contained by 10 to
80% by mass in the base, 6 parts by mass or more of the activator
is mixed with respect to 100 parts by mass of the base, and at
least one of microparticles of resin, a silane coupling agent, and
zirconate is added to the adhesive agent composition.
10. An adhesive agent composition, comprising: as an activator, an
imidazole derivative in which an alkyl group or a substituted alkyl
group is substituted at a 1-postion or at 1- and 2-positions; and
as a base, a compound having three or more epoxy groups.
11. The adhesive agent composition of claim 10, further comprising:
bisphenol A type epoxy resin or bisphenol F type epoxy resin as a
compound having two epoxy groups.
12. The adhesive agent composition of claim 10, wherein an epoxy
equivalent of the compound having three or more epoxy groups is 120
or less.
13. The adhesive agent composition of claim 10, wherein the
compound having three or more epoxy groups is a compound
represented by a following general formula (1): ##STR7## where
R.sub.1 to R.sub.3 are hydrogen, an alkyl group, or a substituted
alkyl group, and R.sub.4 is hydrogen, an alkyl group, an alkoxy
group, alkyl amino group, substituted alkyl amino group or a
substituted alkoxy group.
14. The adhesive agent composition of claim 10, wherein the
compound having three or more epoxy groups is a compound
represented by a following general formula (2): ##STR8## where
R.sub.1 and R.sub.2 are hydrogen, an alkyl group, or a substituted
alkyl group.
15. The adhesive agent composition of claim 11, wherein the
compound having two epoxy groups is bisphenol F type epoxy resin,
in the base, the compound having two epoxy groups is contained by
20 to 90 percents by mass, and the compound having three epoxy
groups is contained by 10 to 80 percents by mass, and 6 parts by
mass or more of the activator is mixed with respect to 100 parts by
mass of the base.
16. The adhesive agent composition of claim 10, wherein the base
further contains a compound having two epoxy groups, the compound
having two epoxy groups is contained by 20 to 90 percents by mass
in the base, and the compound having three or more epoxy groups is
contained by 10 to 80 percents by mass in the base, 6 parts by mass
or more of the activator is mixed with respect to 100 parts by mass
of the base, and at least one of microparticles of resin, a silane
coupling agent, and zirconate is added to the adhesive agent
composition.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an adhesive agent
composition, an inkjet head fabricated by using the adhesive agent
composition, and a manufacturing method of the same.
[0003] 2. Description of Related Art
[0004] At present, a screen printing method is used for
manufacturing a color filter of a liquid crystal display, coating
an orientation film of the liquid crystal display, manufacturing
various electronic precision parts such as an organic EL display,
and so on. Moreover, a billboard is printed on a vinyl chloride
sheet by the screen printing method. As described above, in
general, the printing for commercial use is performed by the screen
printing method.
[0005] Here, the screen printing method is a method which forms a
desired printing pattern on a meshed screen, and prints, on a
medium, ink passing through the pattern. The screen must be
designed and manufactured before the printing, which has led to an
increase of manufacturing steps and manufacturing cost. Moreover,
there has been a problem that, every time when the pattern is
changed, the screen must be remade so as to correspond to the
changed pattern. Furthermore, since the screen is made of a
stainless steel mesh and the like, there has also been a problem
that a micro pattern cannot be manufactured.
[0006] Accordingly, in recent years, an inkjet recording method has
come to be used in place of the conventional screen printing method
since the inkjet recording method has been able to print
ultra-micro ink droplets on an arbitrary place owing to a progress
of an inkjet recording apparatus. The printing by the inkjet
recording apparatus has advantages in that the pattern is not
necessary unlike the printing by the conventional screen printing
method, that it is possible to perform more micro printing than the
screen printing method, that the apparatus is inexpensive, and so
on.
[0007] An inkjet head for use in the inkjet recording apparatus
includes one of a thermal mode of foaming the ink by providing a
heater for ink passages, followed by jetting, and one of a
piezoelectric mode of pressurizing the ink by piezoelectric
elements provided in the ink passages. The ink for use in the
thermal mode is limited to aqueous ink since organic solvent ink
and oil-base ink do not foam. As opposed to this, the piezoelectric
mode can jet any of the aqueous, solvent-base and the oil-base
inks, and accordingly, is preferable.
[0008] The piezoelectric mode includes a mode of deforming a
pressurization chamber by expansion and contraction of the
piezoelectric elements, which are caused when an electric field is
applied to the piezoelectric elements in a polarization direction,
and a mode of deforming the pressurization chamber by shear
deformation caused when the electric field is applied to the
piezoelectric elements in a direction perpendicular to the
polarization direction. The mode using the shear deformation
includes a mode in which two wall surfaces of the pressurization
chamber are composed of the piezoelectric elements, and a mode in
which only one surface thereof is composed of the piezoelectric
element.
[0009] In the inkjet head as described above, the ink passages are
formed so as to contact with the piezoelectric elements, an inner
capacity of each ink passage is varied following deformations of
the piezoelectric elements, and the ink droplets are jetted. To the
ink passages, various members such as a nozzle plate in which a cap
member and nozzle holes are provided are adhered.
[0010] In general, the ink for use in the inkjet recording
apparatus includes the aqueous ink and the solvent ink. The aqueous
ink is ink made of water, a pigment, a water-soluble organic
solvent, and an activator. The water-soluble organic solvent is
glycol ether, which prevents evaporation of moisture from ink
jetting ports during a pause of the jetting. Meanwhile, the solvent
ink is one using a strong solvent for dissolution of resin. By
using such a solvent, the solvent ink permeates through a recording
medium after recording an image, and durability thereof is
enhanced. Accordingly, the solvent ink is used for the printing for
commercial use, which takes the durability as important.
[0011] In the inkjet recording method as an alternative to the
screen printing method, various solvent inks including the oil-base
ink, UV curing ink, and the like are used, and there is a
possibility that the solvent for use in these inks swells or
dissolves an adhesive agent of the inkjet head. As such a solvent,
for example, there are used n-methylpyrrolidone, dimethylformamide,
2-pyrrolidinone, ethyl acetate, diethylene glycol monoethyl ether
acetate, cyclohexanone, butoxyethyl acetate, and the like.
[0012] However, an adhesive agent composition usable with high
reliability even in the extremely strong organic solvent for the
dissolution of the resins has been unknown yet.
[0013] At the time of adhering the respective members to one
another in a manufacturing process of the inkjet head, it is
preferable that temperature at which the inkjet head is heated be
low, and ideally, it is desirable that the temperature be room
temperature. The adhesion at the low temperature makes it possible
to prevent depolarization of the piezoelectric elements and to
reduce a stress caused by a difference in linear thermal expansion
coefficient among the members adhered to one another. When members
largely different in linear thermal expansion coefficient from one
another are adhered together by heat curing, there occur
exfoliation, breakage, and the like in adhered portions owing to
the stress when the members are returned to a room temperature
atmosphere.
[0014] As examples of the adhesive agent having solvent resistance
to the solvent ink, the following are mentioned. An adhesive agent
described in JP 2001-301160A or JP 2001-301178A is an amine curing
epoxy adhesive agent in which a mass increase is 5% or less in the
case of being immersed in oil-base ink containing saturated
hydrocarbon with the carbon number of 15 to 18 or monovalent
alcohol with the carbon number of 15 to 18. In JP 2002-302591A, an
adhesive agent formed of epoxy resin cured at 60.degree. C. by
using an amine curing resin is disclosed.
[0015] As examples of a curing method of the adhesive agent, which
enhances the solvent resistance, the following are mentioned. In JP
2003-266708A, there is disclosed a method which, when the epoxy
resin is cured by a dicyandiamide activator, slows down a
temperature increase rate in a temperature range from the room
temperature to 100.degree. C., and enhances a crosslink density,
thereby improving the solvent resistant. In JP 2000-68294A, there
is disclosed a method which cures polyfunctional epoxy resin
together with denatured imidazole at 150.degree. C. for one minute,
and assembles an electronic device.
[0016] However, in the adhesive agent composition described in JP
2001-301160A or JP 2001-301178A, resistance thereof to the solvent
ink has been insufficient. Also in the adhesive agent composition
described in JP 2002-302591A, though alkali resistance thereof is
excellent, there has been a problem that resistance thereof to
solvent ink containing a resin solvent is low. In the curing method
of an adhesive agent, which is described in JP 2003-266708A, since
a high curing temperature is required, there has been a problem
that, when the members different from each other in thermal
expansion coefficient are adhered together, there occurs warpage,
breakage, and reduction of jetting performance owing to the stress
caused by the above-described adhesion. In the curing method of an
adhesive agent, which is described in JP 2000-68294A, since the
curing temperature is too high, resulting in an occurrence of the
depolarization of the piezoelectric elements, there has been a
problem that the method concerned cannot be applied to the inkjet
head using the piezoelectric elements.
[0017] In general, as the adhesive agent having the large solvent
resistance, the epoxy adhesive agent is mentioned as described
above. It is known that the property of the epoxy adhesive agent is
varied depending on the activator to be used together therewith. As
an activator which performs the curing at a relatively low
temperature from the room temperature to approximately 60.degree.
C., there are known aliphatic polyamine, and alicyclic polyamine
and polyamide. However, when the epoxy resin is cured by such an
amine activator at the room temperature, there are disadvantages in
that polar groups are created therebetween and that the cured epoxy
resin is weak for the water and the solvent because a crosslink
distance therebetween is long. The epoxy adhesive agent cured at
the room temperature is usable in a temperature range from the room
temperature to an intermediate temperature by heating as long as
the aqueous ink is used. However since the solvent resistance of
the epoxy adhesive agent is insufficient, the epoxy adhesive agent
is prone to cause an ink leakage during use.
[0018] A description will be made of the curing of the epoxy
adhesive agent by the amine activator. Since primary amine present
in the amine activator has high activity, the primary amine opens a
ring of an epoxy group and adds to the epoxy resin, thereby
generating a secondary amine and a hydroxyl group. Such generation
is repeated, and chains grown into a linear shape. When the
secondary amine reacts with the epoxy group, a tertiary amine and a
hydroxyl group are generated. Such generation is repeated, and a
three-dimensional structure is thus formed. However, the amine
activator is captured in such a crosslink structure, and the
crosslink structure contains the hydroxyl group, and accordingly,
the crosslink structure is prone to swell by absorbing the solvent.
Although the amine activator and the hydroxyl group which remain in
the three-dimensional structure should be reacted with the epoxy
group remaining therein, the crosslink structure has already been
formed at this point of time, and a glass transition point thereof
is high, and accordingly, these groups cannot be brought into
contact with one another to make the reaction unless heating is
performed up to a glass transition temperature or more. Therefore,
heating up to 150 to 200.degree. C. or more is required, thereby
deteriorating the polarization of the piezoelectric elements.
[0019] In the case of using the imidazoles as the activator, an
adhesive agent having large resistance can be obtained. However,
heating up to approximately 150.degree. C. is required for the
curing in the conventional technology. Since the imidazoles contain
the secondary amine and the tertiary amine, the activity thereof is
somewhat inferior to the activator containing the primary amine,
the imidazoles make the reaction slowly at the room temperature,
and the heating up to approximately 150.degree. C. is required.
However, a curing reaction mechanism of the activator of the
imidazoles is different from that of the primary amine, the
imidazoles act as a catalyst which starts the curing reaction, and
when the curing reaction is started, the epoxy resin is crosslinked
with the other by ether bonding. Accordingly, the polar groups are
not contained in the cured body, and the distance between the
crosslink points is short. Therefore, the imidazoles are excellent
in solvent resistance. Moreover, since the primary amine has high
activity, the primary amine causes a rash and an itch upon touching
the human skin; however, the imidazoles do not cause the rash and
the itch.
[0020] Typically, the structure of the cured object cured by the
primary amine contains the hydroxyl group and amino bonding, and
meanwhile, when the curing is performed by the imidazoles, only
ether bonding is contained. Carbon-carbon bonding constituting a
benzene ring and a methyl group has the highest chemical
resistance, and the ether bonding follows the above. The ether
bonding has characteristics that it is difficult to be swelled and
dissolved by the organic solvent.
[0021] As described above, in the case of using the imidazoles as
the activator, an adhesive agent layer excellent in solvent
resistance is formed. However, the heating up to approximately
150.degree. C. is required for the curing in the conventional
technology, and it has been difficult to use the imidazoles for
manufacturing the piezoelectric type inkjet head because of the
reason of the difference in thermal expansion, which is described
above.
[0022] Moreover, in the inkjet head used in recent years, a density
of the nozzle holes on the nozzle plate is highly densified to 180
to 600 dpi (which represents the number of dots per inch, that is,
per 2.54 cm). Accordingly, the inkjet head is formed so that an
interval between the respective ink passages can be as extremely
narrow as 40 to 70 .mu.m. Moreover, the inkjet head is formed so
that the number of ink passages can be as extremely large as 100 to
1000 in the case of a serial head and as 1000 to 8000 in the case
of a line head. Specifically, there are several thousands of micro
adhesion spots with a width of approximately 40 to 70 .mu.m in one
inkjet head, and adhesion positions thereof are prone to be
misaligned owing to a difference in thermal expansion between the
nozzle plate and a channel base. Accordingly, the adhesion of the
nozzle plate is the most difficult technology in the manufacture of
the inkjet head.
[0023] In this connection, when the adhesive agent is heated and
cured in the case of manufacturing the inkjet head, the lower the
temperature for the heating is, the more preferable it is. Ideally,
it is desirable that the adhesive agent be cured at the room
temperature. The reason of this is in order to prevent the
depolarization of the piezoelectric elements and in order to
prevent the warpage, the breakage, and the reduction of the jetting
performance owing to the difference in linear thermal expansion
coefficient.
[0024] The depolarization of the piezoelectric elements is a
phenomenon that piezoelectric property thereof is lost when the
piezoelectric elements are heated up to a high temperature. Since
the piezoelectric elements have such characteristics, there has
been a problem that the piezoelectric elements cannot be heated up
to 100 to 150.degree. C. or more.
SUMMARY OF THE INVENTION
[0025] The present invention has been made in consideration of the
above-described circumstances. It is one of objects of the present
invention to provide an inkjet head which has high chemical
resistance and solvent resistance, and is good in durability and
jetting performance even in the case of using an adhesive agent
composition curable at the room temperature to a moderate
temperature and solvent ink, and to provide a manufacturing method
of the inkjet head.
[0026] In order to achieve the above-described object, according to
a first aspect of the invention, a method of manufacturing an
inkjet head comprises: adhering members constituting the inkjet
head together by using an adhesive agent composition, wherein the
adhesive agent composition contains, as an activator, an imidazole
derivative in which an alkyl group or a substituted alkyl group is
substituted at the 1-postion or at the 1- and 2-positions, contains
a compound having three or more epoxy groups as a base, and is
cured at 60.degree. C. or less, thereby adhering the members
together.
[0027] As described above, the adhesive agent composition using the
activator which contains the imidazole derivative in which the
alkyl group or the substituted alkyl group is substituted at the
1-position or at the 1- and 2-positions is cured at 60.degree. C.
or less, and the members are thus adhered together, thereby
manufacturing the inkjet head. Thus, even if the adhesive agent
which has high chemical resistance and solvent resistance and is
curable at low temperature and the solvent ink are used, an inkjet
head which has good durability and jetting performance can be
provided.
[0028] Preferably, a difference in linear thermal expansion
coefficient between the members is 12 ppm/K or more.
[0029] Preferably, the adhesive agent composition contacts ink
after being cured.
[0030] Preferably, the adhesive agent composition further contains
bisphenol A type epoxy resin or bisphenol F type epoxy resin as a
compound having two epoxy groups.
[0031] Preferably, in the adhesive agent composition, an epoxy
equivalent of the compound having three or more epoxy groups is 120
or less.
[0032] Preferably, in the adhesive agent composition, the compound
having three or more epoxy groups is a compound represented by a
following general formula (1): ##STR1##
[0033] where R.sub.1 to R.sub.3 are hydrogen, an alkyl group, or a
substituted alkyl group, and R.sub.4 is hydrogen, an alkyl group,
an alkoxy group, alkyl amino group, substituted alkyl amino group
or a substituted alkoxy group.
[0034] Preferably, in the adhesive agent composition, the compound
having three or more epoxy groups is a compound represented by a
following general formula (2): ##STR2##
[0035] where R.sub.1 and R.sub.2 are hydrogen, an alkyl group, or a
substituted alkyl group.
[0036] Preferably, the compound having two epoxy groups is
bisphenol F type epoxy resin, in the base, the compound having two
epoxy groups is contained by 20 to 90% by mass, and the compound
having three epoxy groups is contained by 10 to 80% by mass, and 6
parts by mass or more of the activator is mixed with respect to 100
parts by mass of the base.
[0037] Preferably, the base further contains a compound having two
epoxy groups, the compound having two epoxy groups is contained by
20 to 90% by mass in the base, and the compound having three or
more epoxy groups is contained by 10 to 80% by mass in the base, 6
parts by mass or more of the activator is mixed with respect to 100
parts by mass of the base, and at least one of microparticles of
resin, a silane coupling agent, and zirconate is added to the
adhesive agent composition.
[0038] According to a second aspect of the invention, an adhesive
agent composition, comprises: as an activator, an imidazole
derivative in which an alkyl group or a substituted alkyl group is
substituted at the 1-postion or at the 1- and 2-positions; and as a
base, a compound having three or more epoxy groups.
[0039] As described above, the adhesive agent composition using the
activator which contains the imidazole derivative in which the
alkyl group or the substituted alkyl group is substituted at the
1-position or at the 1- and 2-positions is prepared. Thus, even if
the adhesive agent which has high chemical resistance and solvent
resistance and is curable at low temperature and the solvent ink
are used, an inkjet head which has good durability and jetting
performance can be provided.
[0040] Preferably, the adhesive agent composition further
comprises: bisphenol A type epoxy resin or bisphenol F type epoxy
resin as a compound having two epoxy groups.
[0041] Preferably, an epoxy equivalent of the compound having three
or more epoxy groups is 120 or less.
[0042] Preferably, the compound having three or more epoxy groups
is a compound represented by a following general formula (1):
##STR3##
[0043] where R.sub.1 to R.sub.3 are hydrogen, an alkyl group, or a
substituted alkyl group, and R.sub.4 is hydrogen, an alkyl group,
an alkoxy group, alkyl amino group, substituted alkyl amino group
or a substituted alkoxy group.
[0044] Preferably, the compound having three or more epoxy groups
is a compound represented by a following general formula (2):
##STR4##
[0045] where R.sub.1 and R.sub.2 are hydrogen, an alkyl group, or a
substituted alkyl group.
[0046] Preferably, the compound having two epoxy groups is
bisphenol F type epoxy resin, in the base, the compound having two
epoxy groups is contained by 20 to 90 percents by mass, and the
compound having three epoxy groups is contained by 10 to 80
percents by mass, and 6 parts by mass or more of the activator is
mixed with respect to 100 parts by mass of the base.
[0047] Preferably, the base further contains a compound having two
epoxy groups, the compound having two epoxy groups is contained by
20 to 90 percents by mass in the base, and the compound having
three or more epoxy groups is contained by 10 to 80 percents by
mass in the base, 6 parts by mass or more of the activator is mixed
with respect to 100 parts by mass of the base, and at least one of
microparticles of resin, a silane coupling agent, and zirconate is
added to the adhesive agent composition.
BRIEF DESCRIPTION OF THE DRAWINGS
[0048] The present invention will become more fully understood from
the detailed description given hereinbelow and the appended
drawings which given by way of illustration only, and thus are not
intended as a definition of the limits of the present invention,
and wherein;
[0049] FIG. 1 is a longitudinal cross-sectional view of an inkjet
head in a first embodiment of the present invention;
[0050] FIG. 2 is an exploded perspective view of an ink chamber in
the first embodiment of the present invention;
[0051] FIG. 3 is a cross-sectional view along a line I-I of FIG. 1
and FIG. 2;
[0052] FIGS. 4A and 4B are explanatory views of a manufacturing
method of an inkjet head in the first embodiment of the present
invention, in which FIG. 4A is a cross-sectional view showing a
state where two piezoelectric ceramic bases and a cap member are
adhered together, and FIG. 4B is a cross-sectional view along a
line II-II of FIG. 4A;
[0053] FIG. 5 is an explanatory view of the manufacturing method of
an inkjet head;
[0054] FIG. 6 is an explanatory view of the manufacturing method of
an inkjet head;
[0055] FIGS. 7A to 7C are explanatory views of deformation of ink
passages;
[0056] FIGS. 8A to 8C are explanatory views of deformation of ink
passages;
[0057] FIG. 9 is a longitudinal cross-sectional view of an inkjet
head according to a second embodiment; and
[0058] FIG. 10 is a longitudinal cross-sectional view of an inkjet
head according to a third embodiment.
DETAILED DESCRIPTION OF THE INVENTION
First Embodiment
[0059] First, a description will be made of an embodiment of an
adhesive agent composition according to the present invention.
[0060] The adhesive agent composition according to the present
invention is an adhesive agent composition containing, as an
activator, an imidazole derivative in which an alkyl group or a
substituted alkyl group is substituted at the 1-postion or at the
1- and 2-positions, and as a base, a compound having three or more
epoxy groups.
[0061] As the alkyl group, an alkyl group with a carbon number of 1
to 20 is mentioned. Specifically, there are mentioned branched and
straight-chain alkyl groups such as a methyl group, an ethyl group,
an isopropyl group, a t-butyl group, a hexyl group, a dodecyl
group, and a pentadecyl group, and cyclo alkyl groups such as a
cyclopentyl group and a cyclohexyl group. These may be substituted
alkyl groups having substituent groups. As the substituent groups,
there are mentioned an alkyl group, an alkenyl group, an aryl
group, a heterocycle group, a halogen atom, an alkoxy group, an
aryloxy group, an alkoxy carbonyl group, an aryloxy carbonyl group,
a sulfonamide group, a sulfamoyl group, a ureide group, an acyl
group, an acyloxy group, a carbamoyl group, an alkyl sulfonyl
group, an aryl sulfonyl group, a cyano group, a nitro group, a
sulfo group, a hydroxyl group, and the like.
[0062] Moreover, in the imidazole derivative in which the alkyl
group or the substituted alkyl group is substituted at the
1-position, the substituent group may be provided at a position
other than the 1-position. In the imidazole derivative in which the
alkyl groups or the substituted alkyl groups are substituted for
the 1- and 2-positions, the substituent group may be provided at a
position other than the 1- and 2-positions. As the substituent
group, the ones mentioned as the substituent group of the
substituted alkyl group are applicable.
[0063] As the imidazole derivative in which the alkyl group or the
substituted alkyl group is substituted at the 1-position or at the
1- and 2-positions, specifically, there are mentioned
1-methylimidazole, 1-benzyl-2-methylimidazole,
1-benzyl-2-phenylimidazole, 1,2-dimethylimidazole,
1-isobutyl-2-mehylimidazole, 1-methyl-2-ethylimidazole,
1-ethylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole,
1-cyanoethyl-2-methylimidazole,
1-(2-hydroxy-3-phenoxypropyl)-2-ethyl-4-methylimidazole,
1-(2-hydroxy-3-phenoxypropyl)-2-methylimidazole, and the like.
[0064] As the activator, in addition to the imidazole derivative in
which the alkyl group or the substituted alkyl group is substituted
at the 1-position or at the 1- and 2-positions, hexahydro phthalic
anhydride, diethylene triamine, triethylene tetraamine, and
polyamide may be used. Moreover, an aliphatic amine series, an
aromatic amine series, and the like may be used in combination.
[0065] Here, with regard to the imidazole derivative in which the
alkyl group or the substituted alkyl group is substituted at the
1-position or the 1- and 2-positions, as an additional amount
thereof with respect to 100 parts by mass of the compound having
the epoxy groups, 6 parts by mass or more is preferable, and 6 to
15 parts by mass is more preferable.
[0066] As the compound having three or more epoxy groups,
specifically, there are mentioned triglycidyl-p-aminophenol (92.3),
tetraglycidyl diaminodiphenyl methane (105.5), triglycidyl
isocyanurate (99), triglycidyl urazole (89.7), triglycidyl
aminocresol (97), tetraglycidyl-1,3-diaminomethylcyclohexane
(91.5), and glycerol triglycidyl ether (86.7). Note that numeric
values in the parentheses represent epoxy equivalents of the
respective compounds. Here, the epoxy equivalents are values
obtained by dividing molecular weights of the epoxy resins by the
number of epoxy groups. The smaller each of the values is, the
shorter the distance between the crosslink points becomes.
[0067] Moreover, as the compound having three or more epoxy groups,
novolac epoxy resin may be used. As the novolac epoxy resin, phenol
novolac type epoxy resin and cresol novolac type epoxy resin are
applicable. As specific examples of the phenol novolac type epoxy
resin, there are mentioned EPPN 201 (prepared by Nippon Kayaku Co.,
Ltd.), EPPN202 (prepared by Nippon Kayaku Co., Ltd.), EPIKOTE 152
(prepared by Japan Epoxy Resins Co., Ltd.), EPIKOTE 154 (prepared
by Japan Epoxy Resins Co., Ltd.), DEN-438 (prepared by The Dow
Chemical Company), and the like. As specific examples of the cresol
novolac type epoxy resin, there are mentioned EOCN 102 (prepared by
Nippon Kayaku Co., Ltd.), EOCN 103S (prepared by Nippon Kayaku Co.,
Ltd.), EOCN 104S (prepared by Nippon Kayaku Co., Ltd.), EOCN 1020
(prepared by Nippon Kayaku Co., Ltd.), EOCN 1025 (prepared by
Nippon Kayaku Co., Ltd.), EOCN 1027 (prepared by Nippon Kayaku Co.,
Ltd.), EPIKOTE 180S (prepared by Japan Epoxy Resins Co., Ltd.), and
the like.
[0068] Furthermore, as the compound having three or more epoxy
groups, one described in JP 2002-210985A is mentioned. Here, as the
compound having three or more epoxy groups, one with an epoxy
equivalent of 120 or less is preferable, and one with an epoxy
equivalent of 100 or less is more preferable.
[0069] As the compound having three or more epoxy groups, a
preferable one is the compound represented by the above-described
general formula (1). R.sub.1 to R.sub.3 in the general formula (1)
denote a hydrogen atom, an alkyl group, or a substituted alkyl
group. R.sub.4 denotes a hydrogen atom, an alkyl group, an alkoxy
group, or a substituted alkoxy group. Moreover, the sum of the
epoxy groups owned by R.sub.1 to R.sub.4 is two or more. Although
no particular limitations are imposed on the alkyl groups of
R.sub.1 to R.sub.4, as examples thereof, there are mentioned a
methyl group, an ethyl group, a propyl group, an isopropyl group, a
t-butyl group, a pentyl group, an isopentyl group, and the like, of
which carbon number is about 1 to 20. No particular limitations are
imposed on the substituted alkyl group of R.sub.1, and a glycidyl
group, a benzyl group, and the like are mentioned as examples
thereof. No particular limitations are imposed on the substituted
alkyl groups of R.sub.2 and R.sub.3, and a benzyl group, a
p-diglycidyl amino benzyl group, and the like are mentioned as
examples thereof. No particular limitations are imposed on the
alkoxy group of R.sub.4, and a methoxy group, an ethoxy group, and
the like are mentioned as examples thereof. No particular
limitations are imposed on the substituted alkoxy group of R.sub.4,
and a glycidyl group and the like are mentioned as examples
thereof.
[0070] Moreover, as the compound having three or more epoxy groups,
a more preferable one is the compound represented by the
above-described general formula (2). No particular limitations are
imposed on the alkyl groups denoted by R.sub.1 and R.sub.2 in the
general formula (2), and as examples thereof, there are mentioned
branched and straight-chain alkyl groups such as a methyl group, an
ethyl group, an isopropyl group, a t-butyl group, a hexyl group, a
dodecyl group, and a pentadecyl group, and cyclo alkyl groups such
as a cyclopentyl group and a cyclohexyl group. These may be
substituted alkyl groups having substituent groups. As the
substituent groups, there are mentioned an alkyl group, an alkenyl
group, an aryl group, a heterocycle group, a halogen atom, an
alkoxy group, an aryloxy group, an alkoxy carbonyl group, an
aryloxy carbonyl group, a sulfonamide group, a sulfamoyl group, a
ureide group, an acyl group, an acyloxy group, a carbamoyl group,
an alkyl sulfonyl group, an aryl sulfonyl group, a cyano group, a
nitro group, a sulfo group, a hydroxyl group, and the like.
[0071] A compound having two epoxy groups may be mixed to each of
the above-described compounds each having three or more epoxy
groups. It is preferable that an epoxy equivalent of the compound
having two epoxy groups be 150 or less. As the compound having two
epoxy groups, for example, there are mentioned bisphenol A type
epoxy resin (184 to 194) (EPIKOTE 828: prepared by Japan Epoxy
Resins Co., Ltd.), bisphenol F type epoxy resin (160 to 170)
(EPIKOTE 806, EPIKOTE 807: prepared by Japan Epoxy Resins Co.,
Ltd.), RE303S-L (prepared by Nippon Kayaku Co., Ltd.), and further,
one described in JP 2002-210985A). Among them, it is preferable to
add the bisphenol F type epoxy resin from a viewpoint of enhancing
the solvent resistance. Moreover, with regard to an additional
amount of the compounds, the additional amount of the compound
having three or more epoxy groups to 100 parts by mass of the
compound having two epoxy groups is preferably 10 to 100 parts by
mass, more preferably, 20 to 50 parts by mass.
[0072] As the base according to the present invention, any one of
the compounds each having three or more epoxy groups and the
compound having two epoxy groups are used in combination. Besides
this, several kinds of the compounds each having three or more
epoxy groups and the compound having two epoxy groups may be used
in combination.
[0073] As a method of enhancing the crosslink density of the
adhesive agent composition for enhancing the resistance thereof
after the curing, methods of increasing the number of epoxy groups
of the base are mentioned. As one of the methods, there is a method
of using novolac epoxy resin having three or more epoxy groups as
the base. However, the novolac epoxy resin has problems that
fluidity of the novolac epoxy resin at the room temperature is low,
that it is thus difficult to obtain sufficient adhesive force by
the curing at the room temperature, and that sufficient solvent
resistance cannot be obtained by the curing at a low temperature.
However, the one with an epoxy equivalent of 120 or less, and
further, of 100 or less is used as the compound having three or
more epoxy groups, thus making it possible to improve the
performance described above.
[0074] From the adhesive agent composition after the curing, an
imidazole ring-containing compound and the compound having three or
more epoxy resins are detected by a pyrolysis GC mass spectrum in a
form from which the epoxy groups are desorbed. Moreover, the
imidazole ring-containing compound is detected by a solid state
NMR.
[0075] To the adhesive agent according to the present invention,
microparticles of resin, a silane coupling agent, and zirconate may
be added as an additive.
[0076] Particles of a copolymer of methyl methacrylate and butyl
acrylate, and the like are applicable as the microparticles of
resin.
[0077] As the silane coupling agent, there are applicable amino
silane coupling agents such as .gamma.-aminopropyl triethoxy
silane, N-.beta.-aminoethyl-.gamma.-aminopropyl triethoxy silane,
N-.beta.-aminoethyl-.gamma.-aminopropyl trimethoxy silane,
N-.beta.-aminoethyl-.gamma.-aminopropyl methyl dimethoxy silance,
N-phenyl-.gamma.-aminopropyl trimethoxy silane, and
.gamma.-ureidepropyl triethoxy silane, and epoxy silane coupling
agents such as .beta.-glycidoxy propyl trimethoxy silane,
.beta.-(3,4-epoxy cyclohexyl)ethyl trimethoxy silane, and
.gamma.-glycidoxy propyl methyl diethoxy silane.
[0078] Moreover, as the zirconate, there are applicable
neopentyl(diallyl)oxytrineodecanoyl zirconate,
neopentyl(diallyl)oxytri(dodecyl)benzene-sulfonyl zirconate,
neopentyl(diallyl)oxy.cndot.tri(p-amino)benzoate.cndot.zirconate
(LZ-37), tetrapropyl zirconate, tetrabutyl zirconate,
tetra(ethanolamine)zirconate, tetraisopropyl zirconate,
isopropyltri(n-aminoethyl-aminoethyl)zirconate,
diisopropyldi(4-aminobenzoyl)zirconate,
tris-2-propoxy(2-ethylamino)ethyl zirconate,
tris[(2,2-bis2-propenyloxymethyl)butoxy]ethylene diaminoethoxy
zirconate, and the like.
[0079] Moreover, an inorganic filler may be added to the adhesive
agent composition of the present invention. As the inorganic
filler, there are mentioned carbonates such as calcium carbonate
and magnesium carbonate, sulfates such as barium sulfate and
magnesium sulfate, silicates such as aluminum silicate and
zirconium silicate, oxides such as iron oxide, titanium oxide,
aluminum oxide and zinc oxide, kaolin, talc, asbestos powder,
quartz powder, mica, glass fiber, and the like. However, the
inorganic filler is not limited to these. Among them, it is
preferable to use titanium oxide and silica singly or in
combination of two or more thereof from various viewpoints.
[0080] In the case of using the inorganic filler, in order to
couple inorganic microparticles and an organic material contained
in the adhesive agent composition to each other, it is preferable
to use the silane coupling agent and a titanium coupling agent as
the coupling agent.
[0081] As specific examples of the silane coupling agent, the
above-described ones are applicable.
[0082] As specific examples of the titanium coupling agent, for
example, isopropyltri(N-aminoethyl-aminoethyl)titanate, dicumyl
phenyloxy acetate titanate, diisostearoyl ethylene titanate, and
the like can be mentioned. However, the titanium coupling agent is
not limited thereto.
[0083] Additional amounts of these coupling agents are largely
varied depending on the type of the adhesive agent composition of
the present invention. However, it is preferable to set each
additional amount at 5 parts by mass or less when the sum of the
adhesive agent composition and the inorganic filler added thereto
is 100 parts by mass. When the additional amount exceeds 5 parts by
mass, cohesion force of the organic material is decreased, and as a
result, the adhesive force and reliability of the adhesive agent
composition are decreased.
[0084] Moreover, it is preferable to add 0.2 to 10% of
microparticles with a mean particle diameter of 0.1 .mu.m or less
to the adhesive agent composition of the present invention, thereby
increasing viscosity thereof, followed by the adhesion. As the
microparticles with a mean particle diameter of 0.1 .mu.m or less,
specifically, AEROSIL R202 prepared by Nippon Aerosil Co., Ltd. is
mentioned.
[0085] By using the adhesive agent composition in this embodiment,
the curing from the normal temperature to 60.degree. C. is made
possible. In terms of the difference in linear thermal expansion
coefficient between the adhered members, the adhesive agent
composition is applicable within a range from 12 ppm/K to 100
ppm/K. Heretofore, an adverse effect owing to a stress, which will
be described later, has occurred in the case where there is a
difference in linear thermal expansion coefficient, which exceeds
12 ppm/K. However, according to the present invention, the adverse
effect as described above does not occur, and it is possible to
select and use the optimum materials from viewpoints of the
performance and the processability.
[0086] Here, as the adhered members, ceramics, metal, resin, and
the like are mentioned.
[0087] As the ceramics, for example, lead zirconate titanate
(hereinafter, "PZT"), aluminum nitride, boron nitride, alumina,
silica, and the like are mentioned. PZT is preferably used as the
piezoelectric elements, and as specific examples thereof,
PZT(PbZrO.sub.3--PbTiO.sub.3) and third component-added PZT are
mentioned. As the third component to be added, BaTiO.sub.3, ZnO,
LiNbO.sub.3, and LiTaO.sub.3 are mentioned as well as
Pb(Mn.sub.1/3Sb.sub.2/3)O.sub.3, Pb(CO.sub.1/3Nb.sub.2/3)O.sub.3,
and the like.
[0088] As the metal, for example, aluminum, stainless steel,
titanium, and the like are mentioned.
[0089] As the resin, for example, acrylic resin, polyetherimide,
Nylon, polyethylene telephthalate, polyphenylene sulfide, polyether
ether ketone, polyphenylene ether, polybutylene telephthalate,
liquid crystal polymer, polycarbonate, and the like are
mentioned.
[0090] Here, when there is a difference in linear thermal expansion
coefficient, which exceeds 12 ppm/K, the linear thermal expansion
coefficients of the adhered members largely differ from each other.
Accordingly, contraction factors of the members when the members
are cooled after being heated and cured differ from each other,
causing a problem that exfoliation and breakage such as fracture
occur owing to deflection caused in the adhered position.
[0091] Even if the members different in linear thermal expansion
coefficient from each other are adhered together, such problem does
not occur if the members are adhered together at approximately the
room temperature. However, there was also a problem that the
adhesive agent composition was not resistant to ink having strong
corrosive property. Here,
a description will be made more in detail of the problem at the
time when the members different in linear thermal expansion
coefficient are heated and adhered together.
[0092] The stress P owing to thermal contraction caused between the
adhesive agent and the adhered member when the members are cooled
down to the room temperature after being heated and cured is
generally obtained by the following formula.
P.apprxeq.E.DELTA..alpha.(t.sub.2-t.sub.1)
[0093] (where E: elastic modulus of adhesive agent; .DELTA..alpha.:
difference in linear thermal expansion coefficient; t.sub.2: curing
temperature; t.sub.1: room temperature)
[0094] In general, while the linear thermal expansion coefficient
of PZT is 2.times.10.sup.-6=2 ppm/K, the linear thermal expansion
coefficient of the resin member as the adhered member to which PZT
is adhered is approximately 8.times.10.sup.-5 to 2.times.10.sup.-4
(80 to 200 ppm/K). Accordingly, for example, when PZT with a linear
thermal expansion coefficient of 2 ppm/K and a resin member with a
linear thermal expansion coefficient of 140 ppm/K are cured
together at 100.degree. C., PZT extends 15 .mu.m, the resin member
extends 1050 .mu.m, and a dimensional shift of 1 mm occurs
therebetween. In the case of an inkjet head with 1800 dpi, the
interval between the ink passages is 70 .mu.m, and accordingly, the
dimensional shift of 1 mm largely affects the inkjet head.
[0095] Here, when the microparticle filler is added to the epoxy
adhesive agent, the linear thermal expansion coefficient of the
epoxy adhesive agent can be decreased in substantial proportion to
the additional amount of the filler. For example, when the filler
is added by 50 percents by mass to the epoxy adhesive agent, the
linear thermal expansion coefficient of the epoxy adhesive agent
can be made to coincide with the linear thermal expansion
coefficient of PZT. However, in the inkjet head, since PZT and the
resin member are adhered together by using the epoxy adhesive
agent, even if the linear thermal expansion coefficients of PZT and
the epoxy adhesive agent are made to coincide with each other,
breakage occurs in the adhered portion if a difference in linear
thermal expansion coefficient between the resin member and the
epoxy adhesive agent is large.
[0096] In this case, it is also possible to decrease the linear
thermal expansion coefficient of the resin member by adding the
filler thereto. Therefore, as compared with the conventional case,
the linear thermal expansion coefficients of the resin member and
the epoxy adhesive agent are decreased, and the influence from the
thermal contraction is reduced. It is preferable to decrease the
curing temperature to the lowest possible value as well as to adopt
the technologies described above. For example, when the curing
temperature is decreased from 100.degree. C. to 60.degree. C., the
influence from the thermal contraction can be decreased to
half.
[0097] The filler is preferable since the filler not only decreases
the linear thermal expansion coefficient of the resin member but
also has a function to enhance the solvent resistance of the resin
member. As the filler, silica and alumina are mentioned. It is
preferable that the additional amount of the filler be 30 to 50
percents by mass with respect to the resin.
[0098] Moreover, the inventors of the present invention found that,
in the case of using the imidazole-series activator according to
the present invention, the activator concerned is sufficiently
resistant to such a strong resin solvent as being contained in
screen printing ink. Thus, it is made possible to improve the
enormous inkjet technologies developed heretofore, and to achieve
application of the inkjet technology to the screen printing, which
has been heretofore impossible or problematic.
[0099] Next, a description will be made of a structure of an inkjet
head according to the present invention, to which the
above-described adhesive agent composition is applied, with
reference to the drawings. FIG. 1 is a longitudinal cross-sectional
view of an inkjet head 1a. The inkjet head 1a is a piezoelectric
type inkjet head according to this embodiment, and is formed so as
to extend in a direction substantially perpendicular to FIG. 1.
Here, as shown in FIG. 1, a direction substantially parallel to a
recording medium and substantially perpendicular to the inkjet head
1a is defined as a fore and aft direction, a width direction of the
inkjet head 1a is defined as a right and left direction, and a
direction substantially perpendicular to the recording medium is
defined as a vertical direction.
[0100] In the inkjet head 1a, a cover 10 which covers the entirety
of the inkjet head 1a is provided. In the inside of the cover 10,
an ink chamber 3 which jets ink droplets D by varying an inner
capacity thereof is provided while protruding one end thereof from
the cover 10. A lower surface of the ink chamber 3 is an adhesion
surface, to which a flat nozzle plate 50 opposite to the recording
medium is adhered. The nozzle plate 50 is adhered to the ink
chamber 3 through an adhesion portion b, and the adhesion portion b
is a region formed by the curing of the adhesive agent composition
according to the present invention. In the nozzle plate 50, nozzle
holes 51 which jet the ink droplets D are provided so as to be
opposite to the ink chamber 3.
[0101] FIG. 2 is an exploded perspective view of the ink chamber 3,
the nozzle plate 50, and a cap member 2 to be described later. FIG.
3 is a cross-sectional view along a line I-I of FIG. 1 and FIG.
2.
[0102] In the ink chamber 3, a piezoelectric ceramic base 11
serving as a base is provided. In the piezoelectric ceramic base
11, a piezoelectric element 11A serving as the base of the ink
chamber 3 is provided. Onto a front surface of the piezoelectric
element 11A, a piezoelectric element 11B polarized in a direction
reverse to a polarization direction of the piezoelectric element
11A is pasted. The piezoelectric element 11A and the piezoelectric
element 11B are adhered to each other through an adhesion portion
80, and the adhesion portion 80 is a region formed by the curing of
the adhesive agent composition according to the present
invention.
[0103] On a front surface of the piezoelectric ceramic base 11,
plural ink passages 5 which extend in the vertical direction are
formed at a predetermined interval in a width direction (right and
left direction) of the inkjet head. As shown in FIG. 2, the ink
passages 5 are formed so that a depth dimension thereof can be
larger than that of the adhesion portion 80 of the piezoelectric
ceramic base 11. Upper ends of the ink passages 5 are formed so as
to form a substantially circular arc shape when viewed from the
side. Onto front surfaces of the ink passages 5, electrode layers
3a to which a voltage based on image information is transmitted are
pasted.
[0104] As shown in FIG. 1, an FPC 40 to which the image information
is inputted is electrically connected to each upper end of the
electrode layers 3a. In an adhered region of the electrode layer 3a
and the FPC 40, an adhesion portion c formed of the adhesive agent
composition according to the present invention is formed. The FPC
40 is adhered in a reinforced manner to the piezoelectric ceramic
base 11 through an adhesion portion i. Onto a front surface of the
FPC 40, a drive IC 45 which generates the voltage based on the
image information inputted to the FPC 40 is adhered. On an adhered
region of the drive IC 45, an adhesion portion d formed of the
adhesive agent composition according to the present invention is
formed.
[0105] In each inside of the electrode layers 3a, an ink passage 5
in which ink flows in a direction of an arrow shown in FIG. 1 is
provided. As shown in FIGS. 1 to 3, each ink passage 5 is formed to
be adapted to a shape of the ink passage 5, and a front surface of
the ink chamber 3 is made substantially uniform. On a surface of
each ink passage 5, a protection layer 4 as an outer layer for
preventing damage of the electrode layer 3a owing to deformation is
provided.
[0106] Onto the front surface of the ink chamber 3, the flat cap
member 2 formed so that a length dimension thereof in the vertical
direction can be made shorter than a length dimension of the ink
passages 5 is adhered. The cap member 2 is formed of a flat plate
made of, for example, glass, ceramics, metal, or plastics.
Moreover, as shown in FIG. 3, an adhesion portion a formed of the
adhesive agent composition according to the present invention is
interposed between the ink chamber 3 and the cap member 2.
[0107] As shown in FIG. 1, onto a front surface of the cap member
2, a manifold 20 to be described later is adhered so as to coat
openings of the ink passages 5. These are adhered together by using
the adhesive agent composition according to the present invention.
Between the cap member 2 and the manifold 20, an adhesion portion f
is formed, and between the piezoelectric ceramic base 11 and the
manifold 20, an adhesion portion e is formed.
[0108] In the manifold 20, an ink tube 30 is provided through an
adhesion portion h. An ink reservoir portion (not shown) is coupled
to the ink tube 30, and the ink is supplied through the ink tube 30
to the manifold 20. In the inside of the manifold 20, a filter 35
which removes foreign objects in the supplied ink is provided
through an adhesion portion g. In a similar way to the other
adhesion portions, the adhesion portion g is also one formed by the
curing of the adhesive agent composition according to the present
invention.
[0109] In the inkjet head 1a of this embodiment, the adhesion
portion a, the adhesion portion b, and the adhesion portions e to h
are regions brought into direct contact with the ink.
[0110] Next, a description will be made of the ink for use in this
embodiment.
[0111] When the ink for use in the inkjet head of the present
invention contains a solvent in which a solubility parameter (SP)
value ((cal/cm).sup.1/2) is 9.5 to 15.0 and a dipole moment is 2.0
to 4.5 by 3% or more with respect to the entire solvents, the ink
has a particularly significant effect of the present invention. As
specific examples of such a solvent, there are mentioned
N,N-dimethylformamide (SP=12.1, dipole moment=3.86),
N-methyl-2-pyrrolidinone (SP=11.3, dipole moment=4.09), ethyl
lactate (SP=10.0, dipole moment=2.14), cyclohexanone (SP=9.9,
dipole moment=3.01), 2-pyrrolidinone (SP=14.7, dipole moment=3.83),
and the like. The SP values are ones obtained by calculating by
means of the Bicerano method (refer to Jozef Bicerano, "Prediction
of Polymer Properties (Plastics Engineering, 65)). The dipole
moments are ones obtained by calculation based on AM1 of MOPAC.
[0112] Here, the SP value means a value of a solubility parameter
for use in determining solubility of a resin member to an organic
solvent. SP of the solvent refers to a square root of a cohesion
energy density of the solvent concerned. SP of resin refers to SP
of a solvent which dissolves the resin concerned best. SP is a
concept proposed for a substance which does not have polarity.
Accordingly, substances which do not have polarities will be
dissolved into each other if SPs thereof coincide with each other
or if a difference therebetween is 1.35 or less. However, if the
substances have polarities, the above-described difference is
increased, and a variety of resins are dissolved in a variety of
solvents. Since many materials for use in the inkjet head and the
ink have polarities, it is preferable to consider the SPs and the
dipole moments representing the polarities of the solvents
simultaneously in order to determine the solubilities of the
materials.
[0113] Since SP of N-methylpyrrolidone to be used as a solvent for
vinyl chloride is equal to 11.3, the N-methylpyrrolidone dissolves
resin with SP equal to approximately 10 to 13 well. Moreover, since
the polarity of N-methylpyrrolidone is high because the dipole
moment thereof is 4.09, N-methylpyrrolidone even dissolves resin of
which SP value is out of the above-described range if the resin has
polarity. As described above, dissolving power of
N-methylpyrrolidone is extremely strong, and swells and dissolves
most of resins excluding fluororesin and thermosetting resin cured
completely.
[0114] SP of the organic resins for use in the inkjet head, which
include epoxy resin, is approximately 9 to 11, and almost all
thereof are dissolved into N-methylpyrrolidone. N-methylpyrrolidone
is an extremely strong solvent, and dissolves many resins. A
coating apparatus of a liquid crystal orientation film is made of
stainless steel, and the ink in which polyimide is dissolved in
N-methylpyrrolidone is used while being reserved in a stainless
steel container. If the inkjet head is made of stainless steel, and
stainless steel members are joined together by an eutectic alloy,
then solvent resistance of the joined members becomes perfect.
However, it is difficult to manufacture the inkjet head with a
micro structure by stainless steel poor in processability.
Moreover, even if it is possible to manufacture the inkjet head, a
price of the manufactured inkjet head becomes high. In order to
manufacture a high-performance inkjet head with a micro structure
at a low price, it is preferable to manufacture the inkjet head by
adhering the piezoelectric element and the resin member together.
The resin member can be formed by injection molding, and
accordingly, a manifold with a complicated structure can be
manufactured easily. However, there has not been a good adhesive
agent with solvent resistance, it has been impossible to
manufacture such a high-performance inkjet head. Alternatively,
though it is possible to manufacture a small inkjet head, a
lifetime thereof has been short, and reliability thereof has not
been sufficient.
[0115] Here, in the inkjet head 1a of FIG. 1, it is necessary that
the adhesion portion a and the adhesion portion b be as thin as
possible and not run over to portions which do not require the
adhesion. The adhesion portion a and the adhesion portion b are
portions for which adhesion precision is required most. For the
adhesion portion c, it is preferable to use an adhesive agent of
which thermal contraction in the case of the curing is small. Since
the adhesion portion d is located on the periphery of a contact
with the drive IC, it is preferable to use, for the adhesion
portion d, a strong adhesive agent for a stress. For the adhesion
portion g, it is preferable to set the amount of adhesive agent at
a small amount for the purpose of preventing clogging of the
filter.
[0116] Moreover, for the adhesion portions a to h in FIG. 1 and the
adhesion portion 80 in FIG. 3, it is preferable that an adhesion
step be performed under conditions of a low temperature of
100.degree. C. or less and a short time, under which piezoelectric
property of the piezoelectric ceramic base 11 is not lost, and that
the adhesive agent not run over to the portions other than the
adhered portions in a process of the curing.
[0117] In this embodiment, the adhesive agent composition according
to the present invention is used for the adhesion portions a to h
and the adhesion portion 80, and the problems as described above
are thus solved. Moreover, it is possible to adhere together such
members of which linear thermal expansion coefficients have the
difference exceeding 12 ppm/K. Furthermore, the solvent ink can be
used, and one containing, as the solvent, a solvent in which the SP
value is 9.5 to 15.0 and the dipole moment is 2.0 to 4 by 3% or
more with respect to the entire solvents can be used.
[0118] Next, a description will be made of a manufacturing method
of the inkjet head 1a using the adhesive agent composition
according to the present invention.
[0119] First, a description will be made of a manufacturing method
of the ink chamber 3. The ink chamber 3 of this embodiment is
formed in such a manner that the piezoelectric ceramic base 11 and
the cap member 2 are adhered to each other, the adhered member is
then cut in the fore and aft direction of the ink chamber 3, and
two ink chambers 3 are formed.
[0120] First, the piezoelectric element 11B is adhered to the front
surface of the piezoelectric element 11A by using the adhesive
agent composition according to the present invention, and the
piezoelectric ceramic base 11 is thus formed. In this case, the
piezoelectric element 11A and the piezoelectric element 11B are
adhered to each other so that the polarization directions thereof
can be reverse to each other, and between both of them, the
adhesion portion 80 made of the adhesive agent composition
according to the present invention is formed.
[0121] Subsequently, the ink passages 5 are formed by dicing on the
front surface of the piezoelectric ceramic base 11. In this case,
as shown in FIG. 4A, a shape of each ink passage 5 when viewed from
the side is formed so that both ends thereof can form circular arc
shapes, and that a center thereof can be substantially parallel to
the front surface of the piezoelectric ceramic base 11.
[0122] Then, the electrode layer 3a is formed on the inside of each
ink passage 5 in FIG. 3 by a film forming method such as an
evaporation method. Thereafter, in a similar way, the protection
layer 4 is formed on the inside of the electrode layer 3a. The FPC
40 is electrically connected to the upper end of the electrode
layer 3a, and the adhesion portion c is formed therebetween by
using the adhesive agent composition according to the present
invention. The FPC 40 is adhered to the piezoelectric ceramic base
11 in a reinforced manner, and the adhesion portion i made of the
adhesive agent composition according to the present invention is
formed.
[0123] Subsequently, in FIG. 2, the cap member 2 is adhered to the
front surface of the piezoelectric ceramic base 11 by using the
adhesive agent composition according to the present invention, and
the adhesion portion a is formed. The cap member 2 is formed so
that the length dimension thereof in the vertical direction can be
shorter than the length dimension of the ink passage 5.
Accordingly, as shown in FIG. 4A, a part of the front surface of
the ink passage 5 is left opened. The cap member 2 is formed so
that the length dimension thereof in the vertical direction can be
substantially equivalent to the length dimension of the ink chamber
3. Accordingly, as shown in FIG. 4A, a lower portion of the front
surface of the ink passage 5 is entirely coated. The cap member 2
is adhered to the piezoelectric ceramic base 11 in such a way, and
the inside of the protection layer 4 of the piezoelectric ceramic
base 11 thus becomes the ink passage 5. Here, FIG. 4B is a
cross-sectional view along a line II-II in FIG. 4A. Note that, for
the purpose of simplifying the illustrations, the electrode layer
3a and the protection layer 4 are omitted in FIGS. 4A and 4B.
[0124] Then, in such a state where the piezoelectric ceramic base
11 and the cap member 2 are adhered to each other, the adhered
member is cut into two so that cut pieces can be symmetrical along
the right and left direction of the ink chamber 3. FIG. 5 shows a
state of one of the cut pieces.
[0125] After the cutting, as shown in FIG. 6, the manifold 20 is
adhered to the cut piece so as to cover the opening of the front
surface of the ink passage 5. In this case, one end of the manifold
20 is adhered to the front surface of the piezoelectric ceramic
base 11, and the adhesion portion e is formed. The other end of the
manifold 20 is adhered to the front surface of the cap member 2,
and the adhesion portion f is formed. Since the manifold 20 is
coupled to the ink reservoir portion through the ink tube 30, the
ink from the manifold 20 flows into the ink chamber 3 through the
opening of the ink passage 5.
[0126] The nozzle plate 50 is adhered to the lower surface of the
cut ink chamber 3 by using the adhesive agent composition according
to the present invention. In this case, the nozzle plate 50 is
adhered to the lower surface concerned so that the nozzle holes 51
can be opposite to positions opposite to the ink passages 5, and
the adhesion portion b is formed.
[0127] The ink chamber 3 manufactured as described above is
attached to the cover 10, and the inkjet head 1a is thus
formed.
[0128] Next, a description will be made of a function of the inkjet
head 1a by using FIG. 7 and FIG. 8. Note that the respective
adhesion portions and the protection layer 4 are omitted in FIG. 7
and FIG. 8.
[0129] FIGS. 7A to 7c are an example of the deformation of the ink
chamber 3. In this embodiment, the ink chamber 3 fluctuates in the
right and left direction in FIGS. 7A to 7C based on an image signal
inputted to the inkjet head 1a, thereby varying the inner capacity
of each ink passage 5, and jetting the ink droplet D.
[0130] First, when the image signal is inputted to the inkjet head
1a, the image signal concerned is transmitted to the FPC 40. Since
the drive IC 45 is adhered to the FPC 40, the drive IC 45 generates
a voltage of a predetermined value based on the image signal
transmitted thereto. The generated voltage is applied to the
electrode layer 3a of the ink chamber 3 through the adhesion
portion i.
[0131] The electrode layer 3a is pasted to the piezoelectric
ceramic base 11. Accordingly, when the voltage is applied to the
electrode layer 3a, the voltage is also applied to the
piezoelectric ceramic base 11. Here, the piezoelectric ceramic base
11 is composed of the piezoelectric element 11A and the
piezoelectric element 11A which are polarized in the directions
reverse to each other. Accordingly, the polarized regions of the
piezoelectric ceramic base 11 undergo the shear deformation so as
to be bent as shown in FIGS. 7A to 7C when the voltage is applied
thereto.
[0132] In this embodiment, two wall surfaces of each ink passage 5,
which are opposite to side surfaces of each ink passage 5,
fluctuate. As shown in FIGS. 7A to 7C, the polarized regions
adjacent to each other are deformed so as to be bent to the reverse
sides in the right and left direction, and the inner capacity of
the ink passage 5 is varied. When the inner capacity of the ink
passage 5 is varied, the ink droplet D is jetted from the ink
passage 5 in which the inner capacity is reduced following the
variation.
[0133] As described above, by using the adhesive agent composition
according to the present invention, the members of which linear
thermal expansion coefficients have the difference exceeding 12
ppm/K can be adhered to each other under a temperature condition of
60.degree. C. or less. Accordingly, the inkjet head 1a can be
manufactured easily without depolarizing the piezoelectric element,
and the inkjet head 1a of which solvent resistance is high is
manufactured. Moreover, by using the adhesive agent composition
according to the present invention, stresses are absorbed, which
are applied among the adhesion portions a to h and 80, and the
piezoelectric ceramic base 11 as a channel substrate, the adhered
members (the cap member 2, the nozzle plate 50, the manifold 20,
and the like) to be adhered to the piezoelectric ceramic base 11,
or the second adhered members (the manifold 20, the ink tube 30,
the filter 35, and the like) to be adhered to the adhered members
concerned.
[0134] In particular, when the manifold 20 is molded of
thermoplastic resin, though it is easy to mold the manifold 20, the
manifold 20 has a large linear thermal expansion coefficient, and a
difference thereof in linear thermal expansion coefficient from the
piezoelectric ceramic base 11 and the cap member 2 is prone to
exceed 12 ppm/K. Moreover, since a cross-sectional area of the
manifold 20 is large, stresses applied thereto from the
piezoelectric ceramic base 11 and the cap member 2 are large
(meanwhile, stresses applied from the manifold 20 to the
piezoelectric ceramic base 11 and the cap member 2 are also large).
Therefore, in this case, in the piezoelectric ceramic base 11, the
cover plate 2, and the manifold 20, a crack, deflection,
exfoliation, and the like are prone to occur. However, since these
members are adhered together by the above-described adhesive agent
in this embodiment, the crack, deflection, exfoliation, and the
like of the members concerned can be prevented effectively.
[0135] For example, when the piezoelectric ceramic base 11 and the
manifold 20, which are adhered to each other through the adhesion
portion e, are taken as an example, a difference therebetween in
linear thermal expansion coefficient exceeds 12 ppm/K.
[0136] Moreover, in the case of using the nozzle plate 50 made of
polyimide, a difference in linear thermal expansion coefficient
between the nozzle plate 50 and the piezoelectric ceramic base 11
also exceeds 12 ppm/K. Heretofore, when the nozzle plate as
described above and the channel substrate (the piezoelectric
ceramic base in this embodiment) are adhered to each other, there
has been problems that the adhesion is performed in a state where
the position of the nozzle plate is misaligned, and that the
jetting performance is decreased because the adhesive agent
composition flows into the nozzle holes. However, the
above-described problems can be solved by adhering these members to
each other by using the adhesive agent composition according to the
present invention.
[0137] Specifically, when the nozzle plate of which difference in
linear thermal expansion coefficient from the ink chamber 3 exceeds
12 ppm/K is adhered to an end surface of the ink chamber 3,
microparticles with a mean particle diameter of 0.1 .mu.m or less
are added by 0.2 to 10% to the adhesive agent composition according
to the present invention, and the viscosity of the adhesive agent
composition is thus increased, followed by the adhesion. In such a
way, the adhesive agent composition can be prevented from flowing
to the spots other than the adhered portions when the adhesive
agent composition is cured.
[0138] Note that, in this embodiment, the piezoelectric ceramic
base 11 includes the piezoelectric element 11A and the
piezoelectric element 11B. As shown in FIGS. 8A to 8C, the
piezoelectric ceramic base 11 may be formed of one piezoelectric
element 11C. In this case, though a deformation amount of the
piezoelectric element 11c is limited, the deformation of the ink
passages 5 when the voltage is applied to the electrode layers 3a
is increased if the electrode layers 3a are provided on frontal
halves of the ink passages 5 of the piezoelectric ceramic base 11
as shown in FIGS. 8A to 8C. Such a configuration is also
preferable.
[0139] Though the ink is supplied to all the ink passages 5 of the
piezoelectric ceramic base 11 of this embodiment, the ink passages
5 to which the ink is supplied and the ink passages 5 to which the
ink is not supplied may be provided alternately in the ink passages
5. In this case, as compared with the case of jetting the ink by
using all the ink passages 5, the influence from the deformations
of the piezoelectric element 11A and the piezoelectric elements 11B
can be absorbed by the ink passages 5 to which the ink is not
supplied, the ink passages 5 are being adjacent to the
piezoelectric elements 11A and 11B. Accordingly, the inner capacity
of each ink passage 5 can be varied accurately.
Second Embodiment
[0140] FIG. 9 is a longitudinal cross-sectional view of an inkjet
head 1b of a type in which the inner capacity of each ink passage
is varied by extension/contraction deformation of the piezoelectric
element provided on the outer surface of the ink passage.
[0141] In the inkjet head 1b of FIG. 9, the nozzle plate 50 in
which the nozzle holes 51 are formed is provided so as to be
opposite to a recording medium. Onto the upper surface of the
nozzle plate 50, a passage plate 12a is adhered through an adhesion
portion j. In the passage plate 12a, a first ink passage 5a
extended in the vertical direction and formed to have an inner
diameter larger than that of each nozzle hole 51 by a predetermined
dimension is formed so as to be opposite to the nozzle hole 51. At
a position of the passage plate 12a, which is not opposite to the
nozzle hole 51, a second ink passage 5b extended in the vertical
direction is formed.
[0142] Onto the upper surface of the passage plate 12a, a supply
plate 16 is adhered through an adhesion portion k. In the supply
port 16, a first hole portion 16b substantially similar in
cross-sectional shape to the first ink passage 5a is formed so as
to be opposite to the first ink passage 5a. At a position of the
supply plate 16, which is opposite to the second ink passage 5b, an
ink introduction port 16a having a tapered shape in cross section
is formed so as to be opposite to a pressurization chamber A to be
described later. As a position of the supply plate 16, which is not
opposite to a connection plate 12b to be described later, a second
hole portion 16c is formed. The ink reservoir (not shown) is
coupled to the second hole portion 16c. The ink is supplied to the
second ink passage 5b through the second hole portion 16c.
[0143] Onto the upper surface of the supply plate 16, the
connection plate 12b formed so that a length dimension thereof in
the width direction can be shorter than that of the supply plate 16
is adhered. The connection plate 12b and the supply plate are
adhered to each other through an adhesion portion l. Here, the
adhesion portions j to l are ones formed by the curing of the
adhesive agent composition according to the present invention.
[0144] At positions of the connection plate, which are opposite to
the first hole portion 16b and the ink introduction port 16a, hole
portions 12e and 12e are formed, respectively.
[0145] Onto the upper surface of the connection plate 12b, a spacer
plate 12c including an inner space which covers the hole portions
12e is adhered. Moreover, onto the upper surface of the spacer
plate 12c, a flat closing plate 12d is adhered. Here, the
vertically upper and lower portions of the inner space of the
spacer plate 12c are surrounded by the closing plate 12d and the
connection plate 12b, and the pressurization chamber A is thus
formed. The closing plate 12d is formed of a material freely
deformable in the vertical direction, thereby varying the inner
capacity of the pressurization chamber A in response to the
deformation of the closing plate 12d.
[0146] As described above, the respective plates are stacked on one
another, and the ink reservoir portion, the second ink passage 5b,
the pressurization chamber A, the first ink passage 5a, and the
nozzle hole 51 are thus connected to one another in this order.
Thus, the ink flows in a direction of arrows described in FIG. 9,
and the ink droplets D are jetted.
[0147] On the upper surface of the closing plate 12d, an
piezoelectric element 13 is provided which deforms based on an
image signal. For the piezoelectric element 13, a publicly known
one is used, which includes an electrode 13a, a piezoelectric
element layer 13b, and an electrode 13a in this order.
[0148] Note that, for the respective plates 50, 16 and 12a, in
general, it is preferable to use plastics and ceramics of metal and
silicon such as nickel and stainless steel for the purpose of
forming the nozzle hole 51 and the ink introduction port 16a with
high dimensional precision. Moreover, as shown in FIG. 9, it is
desirable that the ink introduction port 16a be formed into a
tapered shape reduced in diameter toward the ink flowing
direction.
[0149] It is preferable that the closing plate 12d, the spacer
place 12c, and the connection plate 12b be made of ceramics. For a
material of the ceramics, it is preferable to use alumina,
zirconia, and the like in terms of processability. A plate
thickness of the closing plate 12d is preferably 50 .mu.m or less,
more preferably, approximately 3 to 12 .mu.m. A plate thickness of
the connection plate 12b is preferably 10 .mu.m or more, more
preferably, 50 .mu.m or more. A plate thickness of the spacer plate
12c is preferably 50 .mu.m or more, more preferably, 100 .mu.m or
more.
[0150] Although the pressurization chamber A can be formed as an
integrally fired body, it is preferable to adhere the respective
plates together by the adhesive agent in terms of processing
precision.
[0151] The piezoelectric element 11B is one formed by forming the
respective constituents by means of a film forming method. In this
case, it is preferable to use, as the closing plate 12d, a ceramic
substrate containing zirconium oxide as a main component.
Preferably, PZT is used as a material of the piezoelectric layer
13b constituting a piezoelectric operation portion.
Third Embodiment
[0152] FIG. 10 is a cross-sectional view of an inkjet head of the
same type as but different in structure from that of the second
embodiment in which the inner capacity of the pressurization
chamber A is varied by the extension/contraction deformation of the
piezoelectric element provided outside of the pressurization
chamber A.
[0153] In an inkjet head 1c, the nozzle plate 50 in which the
nozzle holes 51 are formed is provided so as to be opposite to a
recording medium. Onto the upper surface of the nozzle plate 50, a
spacer member 22 is adhered through an adhesion portion m. In the
spacer member 22, the ink passage 5 made of an elastic material is
provided so that one end thereof can be connected to the nozzle
holes 51. In the other end of the ink passage, an ink supply
portion 27 coupled to the ink reservoir portion (not shown) is
provided.
[0154] Onto the upper surface of the spacer member 22, a vibration
plate 24 made of an elastic material is adhered, and an adhesion
portion n is formed therebetween. Here, the adhesion portions m and
n are ones formed of the adhesive agent composition according to
the present invention.
[0155] On the upper surface of the vibration plate 24, a base 21b
including convex portions extended in the right and left direction
on both side surfaces is provided. On both of the side surfaces of
the base 21b and on the upper surface of the vibration plate 24,
piezoelectric elements 23 are provided so as to extend and contract
in the vertical direction when a voltage is applied to electrode
portions thereof. Each piezoelectric electric element 23 deforms
the ink passage 5 through the vibration plate 24. When the
piezoelectric element 23 extends downward of the inkjet head 1c,
the piezoelectric element 23 applies a pressure to the ink passage
5 so as to reduce the inner capacity thereof.
[0156] On the upper end surface of the vibration plate 23, a fixing
member 21a which covers and fixes the upper surfaces of the
piezoelectric elements 23 and the base 21b is provided.
[0157] By forming the inkjet head 1c as described above, the
voltage is applied to the piezoelectric elements 23 based on image
information, the ink passages 5 are deformed, and the ink droplets
D are jetted from the nozzle holes 51.
[0158] Note that, though inner diameters of the ink passages 5 are
made uniform in FIG. 10, the inner diameters of the ink passages 5
may be made smaller as approaching the nozzle holes 51 in order to
transmit the pressure from the piezoelectric elements 23 to the ink
efficiently and then to jet the ink droplets D.
EXAMPLES
[0159] A description will be made below more in detail of the
present invention by using examples; however, the present invention
is not limited to these at all.
Example 1
[0160] In Example 1, adhesive agent compositions (hereinafter,
"adhesive agents") made of various components were prepared, and
solvent resistances thereof were investigated.
[0161] After bases and activators, which are described in Table 1,
were mixed together, the obtained mixtures were dropped on a Teflon
(registered trademark) sheet so that one droplet thereof could be
0.1 to 0.2 g, and were cured at 60.degree. C. for 3 hours. In such
a way, pellets of the adhesive agents were prepared. TABLE-US-00001
TABLE 1 BASE MASS INCREASING RATIO 1:2:3 ACTIVATOR N-METHYL
DIMETHYL 1 2 3 (MASS) ACTIVATOR phr PILORIDONE FORMAMIDE
COMPARATIVE 1 E1 -- -- 100:0:0 H1 8 NOT NOT HARDENED HARDENED
COMPARATIVE 2 E1 E3 -- 60:40:0 H4 100 CRACKED 22.3 COMPARATIVE 3 E2
E3 -- 70:30:0 H2 8 15.4 12.6 COMPARATIVE 4 E1 E4 -- 80:20:0 H3 10
17.6 13.1 COMPARATIVE 5 E2 E4 70:30:0 Z4 10 14.5 16.0 INVENTIVE 1
E2 E4 -- 60:40:0 Z1 10 7.5 4.6 INVENTIVE 2 E2 E4 -- 70:30:0 Z1 10
3.2 2.5 INVENTIVE 3 E2 E4 -- 70:30:0 Z2 10 3.9 3.5 INVENTIVE 4 E2
E4 -- 70:30:0 Z3 10 4.8 4.1 INVENTIVE 5 E2 E3 -- 70:30:0 Z1 10 10.7
9.6 INVENTIVE 6 E2 E5 -- 80:20:0 Z1 10 5.4 7.7 INVENTIVE 7 E1 E6 --
80:20:0 Z2 10 6.5 6.8 INVENTIVE 8 E1 E4 -- 80:20:0 Z3 10 8.6 7.2
INVENTIVE 9 E2 E4 E3 40:30:30 Z1 10 3.1 2.3 INVENTIVE 10 E4 -- --
100:0:0 Z1 10 1.2 1.8 Note: "CRACKED" represents that it was
impossible to measure because the adhesive agent was broken when
immersed.
[0162] Here, compounds in Table 1 are as follows.
(Base)
[0163] E1: bisphenol A type epoxy resin (epoxy equivalent: 184 to
194) (EPIKOTE 828: prepared by Japan Epoxy Resins Co., Ltd., which
is a compound having two epoxy groups)
[0164] E2: bisphenol F type epoxy resin (epoxy equivalent: 160 to
170) (EPIKOTE 806: prepared by Japan Epoxy Resins Co., Ltd., which
is a compound having two epoxy groups)
[0165] E3: phenol novolac type epoxy resin (epoxy equivalent: 172
to 178) (EPIKOTE 152: prepared by Japan Epoxy Resins Co., Ltd.,
which is a compound having three epoxy groups)
[0166] E4: triglycidyl-p-aminophenol (a compound having three epoxy
groups)
[0167] E5: tetraglycidyl diaminodiphenyl methane (a compound having
four epoxy groups)
[0168] E6: tetraglycidyl-1,3-diaminomethylcyclohexane (a compound
having four epoxy groups)
(Imidazole-Series Activator According to the Present Invention)
[0169] Z1: 1-benzyl-2-methylimidazole
[0170] Z2: 1-methylimidazole
[0171] Z3: 1-benzyl-2-phenylimidazole
(Imidazole-Series Activator Out of the Present Invention)
[0172] Z4: 2-phenylimidazole
(Activator Other than Imidazole-Series Activator)
[0173] H1: hexahydro phthalic anhydride
[0174] H2: diethylene triamine
[0175] H3: triethylene tetramine
[0176] H4: polyamide
[0177] Moreover, phr in Table 1 is values obtained by the following
expression: activator mass/base mass.times.100.
[0178] After measuring mass of the prepared pellet of the mass, the
pellet was immersed in the solvent (N-methylpyrrolidone or
dimethylformamide) described in Table 1, and was left at 60.degree.
C. for seven days. Then, the pellet was taken out of the solvent,
and was washed by isopropyl alcohol in a wash bottle. Thereafter,
the isopropyl alcohol on the surface of the pellet was removed, and
the mass of the pellet was measured. Note that a mass increase rate
of the pellet was obtained by the following expression. mass
increase rate=100.times.(mass after immersion-mass before
immersion)/mass before immersion
[0179] From Table 1, it is understood that, in the adhesive agents
(of the present invention 1 to 10) obtained by combining the bases
and the activators according to the present invention, the mass
increase rates are smaller than those of Comparative examples 1 to
5, and that the adhesive agents according to the present invention
are excellent in solvent resistance.
Example 2
[0180] PZT (thickness: 700 .mu.m; Curie temperature: 210.degree.
C.; linear thermal expansion coefficient: 4 ppm/K) and PZT
(thickness: 150 .mu.m; Curie temperature: 210.degree. C.; linear
thermal expansion coefficient: 4 ppm/K) were adhered to each other
so that the polarization directions thereof could be reverse to
each other by using an adhesive agent A according to the present
invention, which will be described as below. In such a way, a
piezoelectric ceramic base was formed. Subsequently, concave
portions with a depth of 300 .mu.m and a width of 70 .mu.m were
formed from the thinner PZT side as shown in FIGS. 4A and 4B. Then,
aluminum was deposited on side surfaces of the concave portions,
and electrode layers were formed. As shown in FIG. 4A, a cap member
(AlN with a thickness of 700 .mu.m, linear thermal expansion
coefficient: 4 ppm/K) was joined to a joined member of the PZTs of
the piezoelectric ceramic base by using the adhesive agent A, and
by a CVD method, poly-p-xylylene was coated thereon as an
insulating layer. Thereafter, a body thus obtained was cut along
the direction perpendicular to the length direction of the concave
portions, and a head chamber was thus formed (refer to FIG. 5).
Onto the head chamber, a nozzle plate (one in which nozzle holes
with a diameter of 30 .mu.m are formed in polyimide with a
thickness of 100 .mu.m) was joined by using the adhesive agent A
(refer to FIG. 6). Thereafter, as shown in FIG. 6, an electrode was
drawn out, and the manifold (made of PBT, linear thermal expansion
coefficient: 100 ppm/K) was adhered by using the adhesive agent A,
followed by curing, and an inkjet head was constituted.
TABLE-US-00002 <Composition of adhesive agent A> EPIKOTE 807
(bisphenol F; epoxy equivalent: 165; 70 parts by mass prepared by
Japan Epoxy Resins Co., Ltd.) triglycidyl-p-aminophenol (epoxy
equivalent: 95) 30 parts by mass 1-benzyl-2-methylimidazole 10
parts by mass vapor spherical silica (mean particle diameter: 15
nm) 3 parts by mass
<Heating Conditions for Adhesive Agent a at Joining>
[0181] Heating temperature: 45.degree. C.
[0182] Heating time: 13 hours
<Jetting Test>
[0183] A jetting test was performed for the constituted inkjet head
by using dummy ink for jetting evaluation, which does not contain
colorant. Composition of the dummy ink is as follows.
TABLE-US-00003 butoxyethyl acetate 50 parts by mass
dimethylformamide 50 parts by mass (SP = 12.1, dipole moment =
3.86)
[0184] A difference between the maximum jetting speed and the
minimum jetting speed in the nozzles was 7%, and uniformity of the
jetting speed was satisfactory. Moreover, after the ink was filled
in the inkjet head and was left for 4 weeks at 60.degree. C., there
was no ink leakage.
[0185] Next, as a comparative example, the adhesive agent A was
replaced by the following adhesive agent B, and the adhesive agent
B was cured under heating conditions similar to the above. Then,
ink leakage occurred. Then, the curing was performed while changing
the temperature to 70.degree. C., and as a result, a difference
between the maximum jetting speed and the minimum jetting speed in
the jetting test was 18%, which was problematic in uniformity.
<Composition of Adhesive Agent B>
[0186] In place of 1-benzyl-2-methylimidazole,
2-ethyl-4-methylimidazole (Z5) was used. Other than the above, the
adhesive agent B was prepared similarly to the adhesive agent
A.
[0187] Results of Example 2 are shown in Table 2. TABLE-US-00004
TABLE 2 ADHESIVE AGENT EVALUATION COMPOSITION JETTING ADHESIVE
(PARTS BY MASS) CURING INK LEAKAGEAGE SPEED AGENT BASE ACTIVATOR
CONDITION TEST DISTRIBUTION INVENTIVE A E7 (70) E4 (30) Z1 (10)
45.degree. C. 13 H NO INK LEAKAGEAGE UNIFORM AFTER 4 WEEKS
COMPARATIVE B E7 (70) E4 (30) Z5 (10) 45.degree. C. 13 H INK
LEAKAGEAGE -- OCCURRED COMPARATIVE 70.degree. C. 13 H --
NONUNIFORM
[0188] Here, compounds in Table 2 are as follows.
[0189] E4: triglycidyl-p-aminophenol (a compound having three or
more epoxy groups)
[0190] E7: EPIKOTE 807 (bisphenol F type epoxy resin (a compound
having two epoxy groups)
[0191] Z1: 1-benzyl-2-methylimidazole (imidazole-series activator
according to the present invention)
[0192] Z5: 1-benzyl-2-methylimidazole (imidazole-series activator
out of the present invention)
[0193] From Table 2, it is understood that, when the
imidazole-series activator according to the present invention is
used, the ink leakage is less prone to occur, and excellent solvent
resistance is brought. Moreover, it is understood that, when the
imidazole-series activator according to the present invention is
used, the jetting speed is uniform, and excellent jetting
performance is brought. Moreover, members of which linear thermal
expansion coefficients have the difference exceeding 12 ppm/K can
be adhered together, and the inkjet head can be manufactured by
using a manifold with a linear thermal expansion coefficient of 100
ppm/K.
Example 3
[0194] PZT (thickness: 700 .mu.m; Curie temperature: 210.degree.
C.; linear thermal expansion coefficient: 4 ppm/K) and PZT
(thickness: 150 .mu.m; Curie temperature: 210.degree. C.; linear
thermal expansion coefficient: 4 ppm/K) were adhered to each other
so that the polarization directions thereof could be reverse to
each other by using an adhesive agent C according to the present
invention, which will be described as below. In such a way, a
piezoelectric ceramic base was formed. Subsequently, concave
portions with a depth of 300 .mu.m and a width of 70 .mu.m were
formed from the side of the PZT with a thickness of 150 .mu.m as
shown in FIG. 3, and electrode layers were formed. To a joined
member of the PZTs of the piezoelectric ceramic base, as shown in
FIG. 4A, a cap member (AlN with a thickness of 700 .mu.m, linear
thermal expansion coefficient: 4 ppm/K) was joined by using the
adhesive agent C, and an obtained joined body was subjected to
parylene treatment. Thereafter, the body was cut along the
direction perpendicular to the length direction of the concave
portions, and a head chamber was thus formed (refer to FIG. 5).
Onto the head chamber, a nozzle plate (one in which nozzle holes
with a diameter of 30 .mu.m are formed in polyimide with a
thickness of 100 .mu.m) was joined by using the adhesive agent C
(refer to FIG. 6). Thereafter, as shown in FIG. 6, an electrode was
drawn out, and the manifold (made of polyamide, linear thermal
expansion coefficient: 500 ppm/K) was adhered by using the adhesive
agent C, followed by curing, and an inkjet head was constituted.
TABLE-US-00005 <Composition of adhesive agent C (present
invention)> EPIKOTE 807 (bisphenol F; epoxy equivalent: 165; 40
parts by mass prepared by Japan Epoxy Resins Co., Ltd.)
triglycidyl-p-aminophenol 30 parts by mass EPIKOTE 152 (phenol
novolac type epoxy resin: 30 parts by mass prepared by Japan Epoxy
Resins Co., Ltd.) 1-benzyl-2-methylimidazole 10 parts by mass
AEROSIL 200 silica particles (prepared by Nippon 2 parts by mass
Aerosil Co., Ltd.; silica particles; primary particle diameter: 14
nm)
<Heating Conditions for Adhesive Agent C at Joining>
[0195] Heating temperature: 45.degree. C.
[0196] Heating time: 13 hours
<Jetting Test>
[0197] A jetting test was performed for the constituted inkjet head
by using dummy ink for jetting evaluation, which does not contain
colorant. Composition of the dummy ink is as follows.
TABLE-US-00006 butoxyethyl acetate 50 parts by mass
dimethylformamide (SP = 12.1, 50 parts by mass dipole moment =
3.86)
[0198] A difference between the maximum jetting speed and the
minimum jetting speed in the nozzles was 7%, and uniformity of the
jetting speed was satisfactory. Moreover, after the ink was filled
in the inkjet head and was left for one week at 60.degree. C., for
two weeks at 60.degree. C., and for one month at 60.degree. C., the
jetting was performed. As a result, there was no ink leakage in any
of the cases.
[0199] Next, inkjet heads were constituted while replacing the
adhesive agent C by the following adhesive agents D to H, and the
jetting test was performed.
<Composition of Adhesive Agent D (Comparative Example)>
[0200] EPIKOTE 807 (bisphenol F; epoxy equivalent: 165; prepared by
Japan Epoxy Resins Co., Ltd.) 100 parts by mass
[0201] 2-ethyl-4-methylimidazole 10 parts by mass
[0202] The adhesive agent D was cured under similar heating
conditions to those of the adhesive agent C, and was left for one
week at 60.degree. C., and then the jetting test was formed. As a
result, ink leakage occurred. Then, the curing was performed while
changing the temperature to 70.degree. C., and as a result, a
difference between the maximum jetting speed and the minimum
jetting speed in the jetting test was 18%, which was problematic in
uniformity. TABLE-US-00007 <Composition of adhesive agent E
(present invention)> EPIKOTE 807 (bisphenol F; epoxy equivalent:
165; 70 parts by mass prepared by Japan Epoxy Resins Co., Ltd.)
triglycidyl-p-aminophenol 30 parts by mass
1-isobutyl-2-mehylimidazole 10 parts by mass AEROSIL 200 silica
particles (prepared by Nippon 2 parts by mass Aerosil Co., Ltd.;
silica particles; primary particle diameter: 14 nm)
<Heating Conditions for Adhesive Agent E at Joining>
[0203] Heating temperature: 45.degree. C.
[0204] Heating time: 13 hours
[0205] A jetting test was performed similarly to the case of the
adhesive agent C. A difference between the maximum jetting speed
and the minimum jetting speed in the nozzles was 6%, and uniformity
of the jetting speed was substantially satisfactory. Moreover,
after the ink was filled in the inkjet head and was left for one
month at 60.degree. C., the jetting was performed. As a result,
there was no ink leakage. TABLE-US-00008 <Composition of
adhesive agent F (present invention)> EPIKOTE 807 (bisphenol F;
epoxy equivalent: 165; 50 parts by mass prepared by Japan Epoxy
Resins Co., Ltd.) tetraglycidyl diaminodiphenyl methane (epoxy 50
parts by mass equivalent: 105.5) 1-benzylimidazole 10 parts by mass
AEROSIL 200 silica particles (prepared by Nippon 2 parts by mass
Aerosil Co., Ltd.; silica particles; primary particle diameter: 14
nm)
<Heating Conditions for Adhesive Agent F at Joining>
[0206] Heating temperature: 45.degree. C.
[0207] Heating time: 13 hours
[0208] A jetting test was performed similarly to the case of the
adhesive agent C. A difference between the maximum jetting speed
and the minimum jetting speed in the nozzles was 8%, and uniformity
of the jetting speed was substantially satisfactory. Moreover,
after the ink was filled in the inkjet head and was left for three
weeks at 60.degree. C., the jetting was performed. As a result,
leakage occurred. TABLE-US-00009 <Composition of adhesive agent
G (comparative example)> EPIKOTE 807 (bisphenol F; epoxy
equivalent: 165; 70 parts by mass prepared by Japan Epoxy Resins
Co., Ltd.) triglycidyl-p-aminophenol 30 parts by mass
2-methylimidazole 10 parts by mass AEROSIL 200 silica particles
(prepared by Nippon 2 parts by mass Aerosil Co., Ltd.; silica
particles; primary particle diameter: 14 nm)
<Heating Conditions for Adhesive Agent G at Joining>
[0209] Heating temperature: 45.degree. C.
[0210] Heating time: 13 hours
[0211] A jetting test was performed similarly to the case of the
adhesive agent C. A difference between the maximum jetting speed
and the minimum jetting speed in the nozzles was 8%, and uniformity
of the jetting speed was substantially satisfactory. However, after
the ink was filled in the inkjet head and was left for one week at
60.degree. C., the jetting was performed. As a result, leakage
occurred. Next, the curing was performed while changing the
temperature to 70.degree. C., and as a result, such a distribution
of the jetting speed became 19%, which was problematic in
uniformity. TABLE-US-00010 <Composition of adhesive agent H
(comparative example)> EPIKOTE 828 (bisphenol A type epoxy
resin; epoxy 70 parts by mass equivalent: 190; prepared by Japan
Epoxy Resins Co., Ltd.) triglycidyl-p-aminophenol 30 parts by mass
2-methylimidazole 10 parts by mass triethylene AEROSIL 200 silica
particles (prepared by Nippon 2 parts by mass Aerosil Co., Ltd.;
silica particles; primary particle diameter: 14 nm) triethylene
tetramine 9 parts by mass AEROSIL 200 silica particles (prepared by
Nippon 2 parts by mass Aerosil Co., Ltd.; silica particles; primary
particle diameter: 14 nm)
<Heating Conditions for Adhesive Agent H at Joining>
[0212] Heating temperature: 45.degree. C.
[0213] Heating time: 13 hours
[0214] When the adhered portion was touched after the heating,
stickiness remained, and the adhesive agent was not completely
cured. Next, heating was performed at 70.degree. C. for 13 hours.
As a result, a difference between the maximum jetting speed and the
minimum jetting speed in the nozzles was 15%, which was problematic
in uniformity. Moreover, after the ink was filled in the inkjet
head and was left for two weeks at 60.degree. C., the jetting was
performed. As a result, leakage occurred.
[0215] Results of Example 3 are shown in Table 3. TABLE-US-00011
TABLE 3 ADHESIVE AGENT EVALUATION COMPOSITION JETTING ADHESIVE
(PARTS BY MASS) CURING SPEED AGENT BASE ACTIVATOR CONDITION INK
LEAKAGEAGE TEST DISTRIBUTION INVENTIVE C E7 (40) E4 (30) E3 (30) Z1
(10) 45.degree. C. 13 H NO INK LEAKAGEAGE UNIFORM AFTER 4 WEEKS
COMPARATIVE D E7 (100) -- -- Z6 (10) 45.degree. C. 13 H INK
LEAKAGEAGE -- OCCURRED COMPARATIVE 70.degree. C. 13 H NO INK
LEAKAGEAGE NONUNIFORM INVENTIVE E E7 (70) E4 (30) -- Z7 (10)
45.degree. C. 13 H NO INK LEAKAGEAGE UNIFORM AFTER 4 WEEKS
INVENTIVE F E7 (50) E5 (50) -- Z8 (10) 45.degree. C. 13 H NO INK
LEAKAGEAGE UNIFORM AFTER 2 WEEKS COMPARATIVE G E7 (70) E4 (30) --
Z9 (10) 45.degree. C. 13 H INK LEAKAGEAGE UNIFORM OCCURRED AFTER 1
WEEK COMPARATIVE 70.degree. C. 13 H NO INK LEAKAGEAGE NONUNIFORM
COMPARATIVE H E1 (70) E4 (30) -- Z10 (9) 45.degree. C. 13 H NOT
MEASURABLE DUE TO -- BRAKEAGE COMPARATIVE 70.degree. C. 13 H INK
LEAKAGEAGE NONUNIFORM OCCURRED AFTER 2 WEEKS
[0216] Here, compounds in Table 3 are as follows
[0217] E1: EPIKOTE 828 (bisphenol A type epoxy resin (a compound
having two epoxy groups))
[0218] E3: EPIKOTE 152 (phenol novolac type epoxy resin (a compound
having three or more epoxy groups))
[0219] E4: triglycidyl-p-aminophenol (a compound having three or
more epoxy groups)
[0220] E5: tetraglycidyl diaminodiphenyl methane (a compound having
three or more epoxy groups)
[0221] E7: EPIKOTE 807 (bisphenol F type epoxy resin (a compound
having two epoxy groups))
[0222] Z1: 1-benzyl-2-methylimidazole (an imidazole-series
activator according to the present invention)
[0223] Z6: 2-ethyl-4-methylimidazole (an imidazole-series activator
out of the present invention)
[0224] Z7: 1-isobutyl-2-methylimidazole (an imidazole-series
activator according to the present invention)
[0225] Z8: 1-benzylimidazole (an imidazole-series activator
according to the present invention)
[0226] Z9: 2-methylimidazole (an imidazole-series activator out of
the present invention)
[0227] Z10: triethylene tetramine (an imidazole-series activator
out of the present invention)
[0228] From Table 3, it is understood that, in the case of using
the imidazole-series activator according to the present invention,
the curing at 60.degree. C. or less is possible, and in addition,
the ink leakage is less prone to occur, and the excellent solvent
resistance is brought. Moreover, in the case of using the compound
having three or more epoxy groups, which is expressed by the
above-described general formula (2), the ink leakage is further
less prone to occur, and the solvent resistance is further
enhanced. Moreover, the members of which linear thermal expansion
coefficients have the difference exceeding 12 ppm/K can be adhered
together, and the inkjet head can be easily manufactured by using
the manifold with a linear thermal expansion coefficient of 50
ppm/K.
Example 4
[0229] A similar test to that of Example 3 was performed except
that ink made only of N-methylpyrrolidinone (SP=11.3, dipole
moment=4.09) was prepared and used. However, with regard to the
heating conditions, the heating temperature was set at 55.degree.
C., and the heating time was set at three hours.
Adhesive Agent C: Present Invention
[0230] A difference between the maximum jetting speed and the
minimum jetting speed in the nozzles was 8%, and uniformity of the
jetting speed was substantially satisfactory. The ink was filled in
the inkjet head and was left for one month at 60.degree. C., and
the jetting was performed. As a result, there was no ink
leakage.
Adhesive Agent D: Comparative Example
[0231] The ink was filled in the inkjet head and was left for one
week at 60.degree. C., and the jetting was performed. As a result,
ink leakage occurred.
Adhesive Agent E: Present Invention
[0232] A difference between the maximum jetting speed and the
minimum jetting speed in the nozzles was 9%, and uniformity of the
jetting speed was substantially satisfactory. After the ink was
filled in the inkjet head and was left for one month at 60.degree.
C., the jetting was performed. As a result, there was no ink
leakage.
Adhesive Agent F: Present Invention
[0233] After the ink was filled in the inkjet head and was left for
two weeks at 60.degree. C., the jetting was performed. As a result,
no ink leakage occurred. However, when the jetting was performed
after the ink filled in the inkjet head was left for three weeks at
60.degree. C., ink leakage occurred. The uniformity of jetting
speed is considerably good.
Adhesive Agent G: Comparative Example
[0234] After the ink was filled in the inkjet head and was left for
one week at 60.degree. C., the jetting was performed. As a result,
ink leakage occurred.
Adhesive Agent H: Comparative Example
[0235] When the adhered portion was touched after the heating,
stickiness remained, and the adhesive agent was not completely
cured. However, the ink was filled as it was in the inkjet head and
was left for one week at 60.degree. C., and the jetting was then
performed. As a result ink leakage occurred.
[0236] Results of Example 4 are shown in Table 4. TABLE-US-00012
TABLE 4 ADHESIVE AGENT EVALUATION COMPOSITION JETTING ADHESIVE
(PARTS BY MASS) CURING SPEED AGENT BASE ACTIVATOR CONDITION INK
LEAKAGE TEST DISTRIBUTION INVENTIVE C E7 (40) E4 (30) E3 (30) Z1
(10) 55.degree. C. 3 H NO INK LEAKAGE AFTER 4 UNIFORM WEEKS
COMPARATIVE D E7 (100) -- -- Z6 (10) 55.degree. C. 3 H INK LEAKAGE
OCCURRED -- AFTER 1 WEEKS INVENTIVE E E7 (70) E4 (30) -- Z7 (10)
55.degree. C. 3 H NO INK LEAKAGE AFTER 4 UNIFORM WEEKS INVENTIVE F
E7 (50) E5 (50) -- Z8 (10) 55.degree. C. 3 H NO INK LEAKAGE AFTER 2
UNIFORM WEEKS COMPARATIVE G E7 (70) E4 (30) -- Z9 (10) 55.degree.
C. 3 H INK LEAKAGE OCCURRED -- AFTER 1 WEEKS COMPARATIVE H E1 (70)
E4 (30) -- Z10 (9) 55.degree. C. 3 H NO CURING --
[0237] Here, compounds in Table 4 are as follows.
[0238] E1: EPIKOTE 828 (bisphenol A type epoxy resin (a compound
having two epoxy groups))
[0239] E3: EPIKOTE 152 (phenol novolac type epoxy resin (a compound
having three or more epoxy groups))
[0240] E4: triglycidyl-p-aminophenol (a compound having three or
more epoxy groups)
[0241] E5: tetraglycidyl diaminodiphenyl methane (a compound having
three or more epoxy groups)
[0242] E7: EPIKOTE 807 (bisphenol F type epoxy resin (a compound
having two epoxy groups))
[0243] Z1: 1-benzyl-2-methylimidazole (an imidazole-series
activator according to the present invention)
[0244] Z6: 2-ethyl-4-methylimidazole (an imidazole-series activator
out of the present invention)
[0245] Z7: 1-isobutyl-2-methylimidazole (an imidazole-series
activator according to the present invention)
[0246] Z8: 1-benzylimidazole (an imidazole-series activator
according to the present invention)
[0247] Z9: 2-methylimidazole (an imidazole-series activator out of
the present invention)
[0248] Z10: triethylene tetramine (an imidazole-series activator
out of the present invention)
[0249] From Table 4, it is understood that, in the case of using
the imidazole-series activator according to the present invention,
the curing at 60.degree. C. or less is possible, and in addition,
ink leakage is less prone to occur even if N-methylpyrrolidone
having strong resin dissolving power is jetted as a substitution
for the ink, and excellent solvent resistance is brought. Moreover,
it is understood that, in the case of using the compound having
three or more epoxy groups, which is expressed by the
above-described general formula (2), the ink leakage is further
less prone to occur, and the solvent resistance is further
enhanced.
Example 5
[0250] PZT (thickness: 700 .mu.m; Curie temperature: 210.degree.
C.; linear thermal expansion coefficient: 4 ppm/K) and PZT
(thickness: 150 .mu.m; Curie temperature: 210.degree. C.; linear
thermal expansion coefficient: 4 ppm/K) were adhered to each other
so that the polarization directions thereof could be reverse to
each other by using an adhesive agent I according to the present
invention, which will be described as below. In such a way, a
piezoelectric ceramic base was formed. Subsequently, concave
portions with a depth of 300 .mu.m and a width of 70 .mu.m were
formed from the thinner PZT side as shown in FIG. 3. Then, aluminum
was deposited on side surfaces of the concave portions, and
electrode layers were formed. As shown in FIG. 4A, a cap member
(AlN with a thickness of 700 .mu.m, linear thermal expansion
coefficient: 4 ppm/K) was joined to a joined member of the PZTs of
the piezoelectric ceramic base by using the adhesive agent I, and
by a CVD method, poly-p-xylylene was coated thereon as an
insulating layer. Thereafter, a body thus obtained was cut along
the direction perpendicular to the length direction of the concave
portions, and a head chamber was thus formed (refer to FIG. 5).
Onto the head chamber, a nozzle plate (one in which nozzle holes
with a diameter of 30 .mu.m are formed in polyimide with a
thickness of 100 .mu.m) was joined by using the adhesive agent I
(refer to FIG. 6). Thereafter, as shown in FIG. 6, an electrode was
drawn out, and a manifold (made of AlN/BN, linear thermal expansion
coefficient: 5 ppm/K) was adhered by using the adhesive agent I,
followed by curing. Subsequently, a cover made of aluminum die cast
(linear thermal expansion coefficient: 20 ppm/K) was attached so as
to surround the piezoelectric ceramic base and the cap member.
Then, the adhesive agent I was injected between the cover and the
piezoelectric ceramic base and between the cover and the cap
member, and the respective members were joined together.
TABLE-US-00013 <Composition of adhesive agent I> EPIKOTE 807
(bisphenol F; epoxy equivalent: 165; 70 parts by mass prepared by
Japan Epoxy Resins Co., Ltd.) triglycidyl-p-aminophenol 30 parts by
mass 1,2-dimethylimidazole 10 parts by mass AEROSIL 200 silica
particles (prepared by Nippon 2 parts by mass Aerosil Co., Ltd.;
silica particles; primary particle diameter: 14 nm)
<Heating Conditions for Adhesive Agent I at Joining>
[0251] Heating temperature: 45.degree. C.
[0252] Heating time: 13 hours
<Jetting Test>
[0253] A jetting test was performed for the constituted inkjet head
by using dummy ink for jetting evaluation, which does not contain
colorant. Composition of the dummy ink is as follows.
TABLE-US-00014 butoxyethyl acetate 50 parts by mass
dimethylformamide (SP = 12.1, 50 parts by mass dipole moment =
3.86)
[0254] A difference between the maximum jetting speed and the
minimum jetting speed in the nozzles was 5%, and uniformity of the
jetting speed was satisfactory. Moreover, after the ink was filled
in the inkjet head and was left for four weeks at 60.degree. C.,
the jetting was performed. As a result, there was no ink
leakage.
[0255] Next, as a comparative example, the adhesive agent I was
replaced by the following adhesive agent J, and the adhesive agent
J was cured under heating conditions similar to the above. When the
ink was jetted after the ink was filled in the inkjet head and was
left for one week at 60.degree. C., ink leakage occurred. Then, the
curing was performed while changing the curing temperature to
70.degree. C. As a result, though no ink leakage occurred ever
after the ink was jetted after being left for three weeks at
60.degree. C., a difference between the maximum jetting speed and
the minimum jetting speed was 15%, which was problematic in
uniformity. TABLE-US-00015 <Composition of adhesive agent J>
EPIKOTE 807 (bisphenol F; epoxy equivalent: 165; 70 parts by mass
prepared by Japan Epoxy Resins Co., Ltd.) triglycidyl-p-aminophenol
30 parts by mass 2-phenylimidazole 10 parts by mass AEROSIL 200
silica particles (prepared by Nippon 2 parts by mass Aerosil Co.,
Ltd.; silica particles; primary particle diameter: 14 nm)
[0256] Results of Example 5 are shown in Table 5. TABLE-US-00016
TABLE 5 ADHESIVE AGENT EVALUATION COMPOSITION JETTING ADHESIVE
(PARTS BY MASS) CURING SPEED AGENT BASE ACTIVATOR CONDITION INK
LEAKAGE TEST DISTRIBUTION INVENTIVE I E7 (70) E4 (30) Z11 (10)
45.degree. C. 13 H NO INK LEAKAGE AFTER 4 UNIFORM WEEKS COMPARATIVE
J E7 (70) E4 (30) Z12 (10) 45.degree. C. 13 H INK LEAKAGE OCCURRED
-- AFTER 1 WEEK COMPARATIVE 70.degree. C. 13 H NO INK LEAKAGE AFTER
3 NONUNIFORM WEEKS
[0257] Here, compounds in Table 5 are as follows.
[0258] E4: triglycidyl-p-aminophenol (a compound having three or
more epoxy groups)
[0259] E7: EPIKOTE 807 (bisphenol F type epoxy resin (a compound
having two epoxy groups)
[0260] Z11: 1,2-dimethyl-p-aminophenol (imidazole-series activator
according to the present invention)
[0261] Z12: 2-phenylimidazole (imidazole-series activator out of
the present invention)
[0262] From Table 5, the following is understood. When the adhesive
agent to which the imidazole-series activator out of the present
invention is added is used, even in the case where the members of
which linear thermal expansion coefficients have a small difference
are adhered to each other, ink leakage occurred, and the jetting
speed became nonuniform. As opposed to this, when the adhesive
agent to which the imidazole-series activator of the present
invention is added is used, the ink leakage is less prone to occur,
and the distribution of the jetting speed also became uniform, thus
making it possible to enhance the solvent resistance and the
jetting performance.
Example 6
(1.1) Preparation of Samples 1 to 13
[0263] The bases and the activators were mixed together (the
microparticles of resin, the silane coupling agents, and zirconate
were also mixed arbitrarily). Mixtures thus obtained were prepared
into particulates with a mass of 0.1 to 0.2 g per droplet, and the
particulates wee dropped on a Teflon (registered trademark) sheet.
Thereafter, the respective dropped particulates were cured by being
left for 20 hours at 45.degree. C., pellets of adhesive agents K to
W were thus prepared, and these pellets were named "Samples 1 to
13". Compositions (existences and types of the bases, the
activators, the microparticles of resin, the silane coupling
agents, and zirconate) of the respective adhesive agents K to W are
as shown in the following Table 6.
(1.2) Measurement of Mass Increase Rates of Samples 1 to 13
[0264] After preparing Samples 1 to 13, masses of the respective
Samples 1 to 13 were measured, and the respective Samples 1 t 13
were immersed in a solvent (N-methylpyrrolidone), and were left for
seven days at 60.degree. C. After seven days, the respective
Samples 1 to 13 were taken out of the solvent and were washed by
isopropyl alcohol in a wash bottle. After the washing, the
isopropyl alcohol attached to the surfaces of the respective
Samples 1 to 13 was removed, and the masses of the respective
Samples 1 to 13 were measured again.
[0265] After the remeasurement of the masses, the mass increase
rates of the respective Samples 1 to 13 were calculated according
to the following expression. Results of the calculations are as
shown in the following Table 6. mass increase rate (%)=((mass after
immersion into solvent)-(mass before immersion into solvent))/(mass
before immersion into solvent) TABLE-US-00017 TABLE 6 ADHESIVE
AGENT COMPOSITION MASS RATE SAMPLE ADHESIVE (PARTS BY MASS) OF
INCREASE NO. AGENT BASE ACTIVATOR ADDITIVE (%) INVENTIVE 1 K E1
(60) E3 (10) E4 (30) Z1 (10) -- 7.4 INVENTIVE 2 L E2 (60) E3 (10)
E4 (30) Z1 (10) -- 3 INVENTIVE 3 M E2 (60) E3 (10) E4 (30) Z1 (10)
A (3) 3.7 INVENTIVE 4 N E2 (60) E3 (10) E4 (30) Z1 (10) B (3) 3.4
INVENTIVE 5 O E2 (60) E3 (10) E4 (30) Z1 (10) C (3) 3.4 INVENTIVE 6
P E1 (60) E3 (10) E4 (30) Z1 (10) A (3) 7.6 INVENTIVE 7 Q E1 (60)
E3 (10) E4 (30) Z1 (10) B (3) 7.3 INVENTIVE 8 R E1 (60) E3 (10) E4
(30) Z1 (10) C (3) 7.4 INVENTIVE 9 S -- -- E4 (100) Z1 (10) -- 1.5
INVENTIVE 10 T E2 (60) E3 (10) E4 (30) Z1 (7) -- 3.7 INVENTIVE 11 U
E2 (60) E3 (10) E4 (30) Z1 (5) -- 8.6 COMPARATIVE 12 V E2 (100) --
-- Z1 (10) -- 12.8 COMPARATIVE 13 W E1 (70) -- E4 (30) Z13 (10) --
13.1
[0266] Here, compounds in Table 6 are as follows.
[0267] E1: EPIKOTE 828 (bisphenol A type epoxy resin (a compound
having two epoxy groups))
[0268] E2: EPIKOTE 806 (bisphenol F type epoxy resin (a compound
having two epoxy groups))
[0269] E3: EPIKOTE 152 (phenol novolac type epoxy resin (a compound
having three or more epoxy groups))
[0270] E4: triglycidyl-p-aminophenol (a compound having three or
more epoxy groups)
[0271] Z1: 1-benzyl-2-methylimidazole (imidazole-series activator
according to the present invention)
[0272] Z13: 2,4-dimethylimidazole (imidazole-series activator out
of the present invention)
[0273] A: copolymer particles of methyl methacrylate and butyl
acrylate (microparticles of resin; mean particle diameter:
approximately 0.3 .mu.m)
[0274] B: .gamma.-glycidoxy propyl trimethoxy silane (silane
coupling agent)
[0275] C: isopropyltri(n-aminoethyl-aminoethyl)zirconate
(zirconate)
[0276] From Table 6, the following is understood. Mass change rates
of Samples 1 to 11 were lower than those of Samples 12 and 13, and
the adhesive agents K to U are less prone to be dissolved into the
solvent. In the case of using the imidazole-series activator
according to the present invention, the solvent resistance is
enhanced. Moreover, the bisphenol F type epoxy resin as a compound
having two epoxy groups is contained as the main material, thus
making it possible to further decrease the mass increase rates, and
to further enhance the solvent resistance.
Example 7
(2.1) Preparation of Samples 1 to 13
[0277] Two PZT substrates were prepared, which are: "a first PZT
substrate (thickness: 150 .mu.m; Curie temperature: 210.degree. C.;
linear thermal expansion coefficient: 4 ppm/K)"; and "a second PZT
substrate (thickness: 700 .mu.m; Curie temperature: 210.degree. C.;
linear thermal expansion coefficient: 4 ppm/K)". The fist and
second PZT substrates were adhered to each other so that the
polarization directions thereof could be reverse to each other by
an adhesive agent. When the first PZT substrate and the second PZT
substrate were adhered to each other, EPO-TEK 353 ND (prepared by
Rikei Corporation) was used as the adhesive agent, heat of 80 to
100.degree. C. was added to the adhesive agent concerned, and the
adhesive agent concerned was cured.
[0278] After the first and second PZT substrates were adhered to
each other, channels (grooves) with a depth of 300 .mu.m and a
width of 70 .mu.m were formed from the first PZT substrate to the
second PZT substrate, aluminum was deposited on inner walls of the
channels, and electrode layers made of aluminum were thus formed in
the inside of the channels.
[0279] After the electrode layers were formed, a cover plate (made
of aluminum nitride with a thickness of 700 .mu.m; linear thermal
expansion coefficient: 4 ppm/K) was adhered onto the first PZT
substrate by an adhesive agent (refer to FIGS. 4A and 4B). When the
cover plate and the first PZT substrate were adhered to each other,
EPO-TEK 353 ND (prepared by Rikei Corporation) was used as the
adhesive agent, heat of 80 to 100.degree. C. was added to the
adhesive agent concerned, and the adhesive agent concerned was
cured.
[0280] After the cover plate was adhered, the inner walls of the
electrode layers underwent the poly-p-xylylene treatment by the CVD
method, and protection layers were formed in the inside of the
channels. After the protection layers were formed, the first and
second PZT substrates and the cover plate were cut along the
direction perpendicular to the length direction of the channels,
and a head chip was manufactured (refer to FIG. 5).
[0281] After the head chip was manufactured, a nozzle plate (one in
which jetting holes with a diameter of 30 .mu.m are formed in
polyimide with a thickness of 100 .mu.m) was adhered thereto by an
adhesive agent. When the cover plate and the head chip (first PZT
substrate) were adhered to each other, EPO-TEK 353 ND (prepared by
Rikei Corporation) was used as the adhesive agent, heat of 80 to
100.degree. C. was added to the adhesive agent concerned, and the
adhesive agent concerned was cured.
[0282] After the nozzle plate was adhered, other members such as a
manifold (made of polyamide; linear thermal expansion coefficient:
50 ppm/K) were adhered to the head chip by an adhesive agent, and
the inkjet head was manufactured. In this Example 2, in the
adhesion of the manifold (adhesion of the manifold and the cover
plate and adhesion of the manifold and the first PZT substrate), 13
types of adhesive agents shown in the following Table 7 were
applied. Heat of 40.degree. C. was added to the respective adhesive
agents concerned, and the respective adhesive agents concerned were
cured. Then, totally 13 types of inkjet heads corresponding to the
types of adhesive agents were manufactured, and these inkjet heads
were named "Samples 1 to 13".
(2.2) Evaluation of Samples 1 to 13
(2.2.1) Jetting Test
[0283] As a substitution for the ink, a mixture of 90 parts by mass
of butoxyethyl acetate and 10 parts by mass of 2-pyrrolidinone was
applied, the mixture concerned kept on being jetted from the
respective Samples 1 to 13, and jetting performances (when ink
leakage occurred) of the respective Samples 1 to 13 were evaluated.
Results of the evaluations are shown in the following Table 7.
(2.2.2) Heat Cycle Test
[0284] As a heat cycle test at the first time, the above-described
ink substitution was filled in the respective Samples 1 to 13, and
the respective Samples 1 to 13 were put in a heat cycle environment
of three cycles each of which was 25.degree. C., (60.degree. C.,
one hour), (25.degree. C., 30 minutes), (0.degree. C., one hour),
(25.degree. C., 30 minutes) in this order. Thereafter, the ink
substitution was purged from the Samples 1 to 13, the channels of
the respective Samples 1 to 13 were decompressed, and it was
confirmed whether or not there was air leakage in the channels.
[0285] Thereafter, as a heat cycle test at the second time,
further, the ink substitution was filled in the respective Samples
1 to 13, and the respective Samples 1 to 13 were put in a heat
cycle environment of three cycles each of which was 25.degree. C.,
(60.degree. C., one hour), (25.degree. C., 30 minutes),
(-20.degree. C., one hour), (25.degree. C., 30 minutes) in this
order. Thereafter, the ink substitution was purged from the
respective Samples 1 to 13, the channels of the respective Samples
1 to 13 were decompressed, and it was confirmed whether or not
there was air leakage in the channels.
[0286] Results of the tests are as shown in the following Table 7.
Evaluation criteria of the heat cycle tests are as follows.
[0287] "No leakage" . . . There was no air leakage in both of the
heat cycle tests at the first and second times.
[0288] "Leakage occurred at second test" . . . Although there was
no air leakage in the heat cycle test at the first time, air
leakage occurred in the heat cycle test at the second time.
[0289] "Slight leakage occurred at first test" . . . . Some air
leakage occurred in the heat cycle test at the first time.
[0290] "Leakage occurred at first test" . . . . Air leakage
occurred in the heat cycle test at the first time.
(2.2.3) Observation of Existence of Crack
[0291] For each of the respective Samples 1 to 13, it was visually
observed whether or not there was a crack in the adhesive agent
between the cover plate and the manifold after the above-described
heat cycle tests. Results of the observations are shown in the
following Table 7. Evaluation criteria of the crack are as
follows.
[0292] "No crack" . . . There was no crack.
[0293] "A few cracks" . . . One or two cracks were observed.
[0294] "Cracks" . . . Three or more cracks were observed.
TABLE-US-00018 TABLE 7 ADHESIVE AGENT COMPOSITION SAM- ADHE- (PARTS
BY MASS) CURING EVALUATION PLE SIVE ACTI- ADDI- CONDI- INK LEAKAGE
HEAT CYCLE NO. AGENT BASE VATOR TIVE TION TEST TEST CRACK INVEN- 1
K E1 (60) E3 (10) E4 (30) Z1 (10) -- 40.degree. C. 20 H NO INK
LEAKAGE SLIGHT A FEW TIVE AFTER 2 WEEKS LEAKAGE CRACKS OCCURRED AT
FIRST TEST INVEN- 2 L E2 (60) E3 (10) E4 (30) Z1 (10) -- 40.degree.
C. 20 H NO INK LEAKAGE LEAKAGE NO TIVE AFTER 4 WEEKS OCCURRED AT
CRACK SECOND TEST INVEN- 3 M E2 (60) E3 (10) E4 (30) Z1 (10) A (3)
40.degree. C. 20 H NO INK LEAKAGE NO LEAKAGE NO TIVE AFTER 4 WEEKS
CRACK INVEN- 4 N E2 (60) E3 (10) E4 (30) Z1 (10) B (3) 40.degree.
C. 20 H NO INK LEAKAGE NO LEAKAGE NO TIVE AFTER 4 WEEKS CRACK
INVEN- 5 O E2 (60) E3 (10) E4 (30) Z1 (10) C (3) 40.degree. C. 20 H
NO INK LEAKAGE NO LEAKAGE NO TIVE AFTER 4 WEEKS CRACK INVEN- 6 P E1
(60) E3 (10) E4 (30) Z1 (10) A (3) 40.degree. C. 20 H NO INK
LEAKAGE NO LEAKAGE NO TIVE AFTER 4 WEEKS CRACK INVEN- 7 Q E1 (60)
E3 (10) E4 (30) Z1 (10) B (3) 40.degree. C. 20 H NO INK LEAKAGE NO
LEAKAGE NO TIVE AFTER 4 WEEKS CRACK INVEN- 8 R E1 (60) E3 (10) E4
(30) Z1 (10) C (3) 40.degree. C. 20 H NO INK LEAKAGE NO LEAKAGE NO
TIVE AFTER 4 WEEKS CRACK INVEN- 9 S -- -- E4 Z1 (10) -- 40.degree.
C. 20 H NO INK LEAKAGE SLIGHT A FEW TIVE (100) AFTER 3 WEEKS
LEAKAGE CRACKS OCCURRED AT FIRST TEST INVEN- 10 T E2 (60) E3 (10)
E4 (30) Z1 (7) -- 40.degree. C. 20 H NO INK LEAKAGE LEAKAGE NO TIVE
AFTER 4 WEEKS OCCURRED AT CRACK SECOND TEST INVEN- 11 U E2 (60) E3
(10) E4 (30) Z1 (5) -- 40.degree. C. 20 H NO INK LEAKAGE SLIGHT A
FEW TIVE AFTER 2 WEEKS LEAKAGE CRACKS OCCURRED AT FIRST TEST COM-
12 V E2 -- -- Z1 (10) -- 40.degree. C. 20 H INK LEAKAGE LEAKAGE
CRACKS PAR- (100) OCCURRED AFTER OCCURRED AT ATIVE 1 WEEK FIRST
TEST COM- 13 W E1 (70) -- E4 (30) Z13 (10) -- 40.degree. C. 20 H
INK LEAKAGE LEAKAGE CRACKS PAR- OCCURRED AFTER OCCURRED AT ATIVE 1
WEEK FIRST TEST
[0295] Here, compounds in Table 7 are as follows.
[0296] E1: EPIKOTE 828 (bisphenol A type epoxy resin (a compound
having two epoxy groups))
[0297] E2: EPIKOTE 806 (bisphenol F type epoxy resin (a compound
having two epoxy groups))
[0298] E3: EPIKOTE 152 (phenol novolac type epoxy resin (a compound
having three or more epoxy groups))
[0299] E4: triglycidyl-p-aminophenol (a compound having three or
more epoxy groups)
[0300] Z1: 1-benzyl-2-methylimidazole (imidazole-series activator
according to the present invention)
[0301] Z13: 2,4-dimethylimidazole (imidazole-series activator out
of the present invention)
[0302] A: copolymer particles of methylmethacrylate and butyl
acrylate (microparticles of resin; mean particle diameter:
approximately 0.3 .mu.m)
[0303] B: .gamma.-glycidoxy propyl trimethoxy silane (silane
coupling agent)
[0304] C: isopropyltri(n-aminoethyl-aminoethyl)zirconate
(zirconate)
[0305] From Table 7, it is understood that results of Samples 1 to
11 were better than results of Samples 12 and 13. In particular,
from the jetting test and the heat cycle test, it is understood
that there was no crack, deflection, exfoliation, or the like in
the adhesive agent at the joint of the manifold. From the above, it
is understood that the adhesive agents with such specific
compositions, such as the adhesive agents K to U, can be cured by
heat of 60.degree. C. and have flexibility. Moreover, it is
understood that the adhesive agents as described above effectively
function to prevent the crack, deflection, exfoliation, and the
like of the members. Moreover, by adding at least one of the
microparticles of resin, the silane coupling agent, and zirconate
to the adhesive agents, the adhesive agents can obtain good results
in the ink leakage test and the heat cycle test, can have higher
solvent resistance, can be cured at the low temperature, and can
have flexibility.
[0306] The entire disclosure of Japanese Patent Application Nos.
2005-79552 filed on March 18; 2005-347811 filed on Dec. 1, 2005;
2005-79570 filed on Mar. 18, 2005; 2005-364691 filed on Dec. 19,
2005; and 2006-036571 filed on Feb. 14, 2006 including description,
claims, drawings and summary respectively are incorporated herein
by reference.
* * * * *