U.S. patent application number 13/817041 was filed with the patent office on 2013-06-13 for polyvinyl acetal resin, slurry composition prepared therefrom, ceramic green sheet, and multilayer ceramic capacitor.
This patent application is currently assigned to KURARAY CO., LTD. The applicant listed for this patent is Yuhi Shimazumi. Invention is credited to Yuhi Shimazumi.
Application Number | 20130148263 13/817041 |
Document ID | / |
Family ID | 45605171 |
Filed Date | 2013-06-13 |
United States Patent
Application |
20130148263 |
Kind Code |
A1 |
Shimazumi; Yuhi |
June 13, 2013 |
POLYVINYL ACETAL RESIN, SLURRY COMPOSITION PREPARED THEREFROM,
CERAMIC GREEN SHEET, AND MULTILAYER CERAMIC CAPACITOR
Abstract
According to the present invention, provided is a polyvinyl
acetal resin capable of obtaining a ceramic green sheet that has
sufficient mechanical strength, in which the dimensional change in
the storage of ceramic green sheet is small, and the delamination
hardly occurs in the delipidation. The present invention relates to
a polyvinyl acetal resin that has a degree of polymerization of 200
or more to 6000 or less, a content percentage of vinylester unit of
0.01 to 30 mol %, a degree of acetalization of 55 to 83 mol %, and
a structural unit represented by Chemical formula (1): ##STR00001##
in a molecule.
Inventors: |
Shimazumi; Yuhi; (Tokyo,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Shimazumi; Yuhi |
Tokyo |
|
JP |
|
|
Assignee: |
KURARAY CO., LTD
Okayama
JP
|
Family ID: |
45605171 |
Appl. No.: |
13/817041 |
Filed: |
August 12, 2011 |
PCT Filed: |
August 12, 2011 |
PCT NO: |
PCT/JP11/68459 |
371 Date: |
February 14, 2013 |
Current U.S.
Class: |
361/321.1 ;
252/500; 524/557; 525/61 |
Current CPC
Class: |
C08K 3/22 20130101; C04B
2235/3236 20130101; H01G 4/12 20130101; C04B 35/6342 20130101; C08F
116/06 20130101; C09D 129/04 20130101; C08K 2003/2241 20130101;
H01G 4/30 20130101; C08F 216/38 20130101; C08K 5/01 20130101; C04B
35/4682 20130101 |
Class at
Publication: |
361/321.1 ;
525/61; 524/557; 252/500 |
International
Class: |
C08F 116/06 20060101
C08F116/06; H01G 4/12 20060101 H01G004/12 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 19, 2010 |
JP |
2010-183815 |
Claims
1. A polyvinyl acetal resin, comprising a structural unit of
formula (1): ##STR00006## in a molecule, wherein the polyvinyl
acetal resin has a degree of polymerization of from 200 to 6000, a
content percentage of vinylester unit of from 0.01 to 30 mol %, and
a degree of acetalization of from 55 to 83 mol %.
2. The polyvinyl acetal resin according to claim 1, wherein the
degree of polymerization is from 1500 to 4500.
3. The polyvinyl acetal resin according to claim 1, wherein the
polyvinyl acetal resin is obtained by a process comprising
acetalizing a polyvinyl alcohol resin with aldehyde comprising
3-methylbutanal.
4. The polyvinyl acetal resin according to claim 1, further
comprising a structural unit of formula (2): ##STR00007## formula
(3): ##STR00008## or both in the molecule.
5. The polyvinyl acetal resin according to claim 1, wherein the
polyvinyl acetal resin comprises the structural unit of formula (1)
in a content of at least 30 mol % relative to a total molar amount
of acetalized structural units.
6. A slurry composition, comprising: the polyvinyl acetal resin
according to claim 1; a ceramic powder; and an organic solvent.
7. A ceramic green sheet, obtained by a process comprising
producing the ceramic green sheet from the slurry composition
according to claim 6.
8. A conductive paste, comprising: the polyvinyl acetal resin
according to claim 1; and a conductive powder.
9. A laminated ceramic capacitor, obtained by a process comprising
producing the laminated ceramic capacitor from the ceramic green
sheet according to claim 7.
10. A laminated ceramic capacitor, obtained by a process comprising
producing the laminated ceramic capacitor from the conductive paste
according to claim 8.
11. The polyvinyl acetal resin according to claim 2, wherein the
degree of polymerization is from 2000 to 3500.
12. The polyvinyl acetal resin according to claim 1, wherein the
content percentage of vinylester unit is from 0.5 to 20 mol %.
13. The polyvinyl acetal resin according to claim 1, wherein the
degree of acetalization is from 65 to 80 mol %.
14. The polyvinyl acetal resin according to claim 1, obtained by a
process comprising acetalizing a polyvinyl alcohol resin with
aldehyde comprising acetaldehyde.
15. The polyvinyl acetal resin according to claim 1, obtained by a
process comprising acetalizing a polyvinyl alcohol resin with
aldehyde comprising butyraldehyde.
16. The polyvinyl acetal resin according to claim 3, wherein the
polyvinyl acetal resin comprises the structural unit acetylized by
3-methylbutanal of formula (1) in a content of at least 50 mol %
relative to the total molar amount of acetalized structural units.
Description
TECHNICAL FIELD
[0001] The present invention relates to a polyvinyl acetal resin
that is suitably used as a binder of a ceramic green sheet, and a
slurry composition using the polyvinyl acetal resin, a ceramic
green sheet, a conductive paste, and a laminated ceramic
capacitor.
BACKGROUND ART
[0002] In the case of producing a laminated ceramic capacitor,
generally the following production method is employed. Firstly, a
binder resin such as a polyvinyl butyral resin, and a plasticizer
are added into an organic solvent in which ceramic powders have
been dispersed, the resultant is mixed homogeneously by a ball mill
or the like to prepare a slurry composition. The prepared slurry
composition is casted on a strippable support of polyethylene
terephthalate film and the like, and the solvent and the like are
removed by heating and the like, and then the resultant is stripped
off from the support to obtain a ceramic green sheet.
[0003] Next, plural ceramic green sheets on the surfaces of which a
conductive paste that becomes an internal electrode has coated by a
screen printing or the like, are piled up alternately, and a
laminated body thereof is obtained by heating, clamping, and the
like, and then the laminated body is cut into a predetermined
shape. Subsequently, a treatment in which the binder components and
the like contained in the laminated body are pyrolytically
decomposed and removed, so-called a delipidation treatment, is
performed, and then by performing a step of sintering an external
electrode on the end face of the ceramic burned product obtained
through firing, a laminated ceramic capacitor is obtained.
Therefore, in the case of the above ceramic green sheet, favorable
working properties in the preparation of slurry composition and
further improvement of the strength capable of withstanding these
steps of processes are required.
[0004] Recent years, with the diversification and miniaturization
of an electronic equipment, in the case of a laminated ceramic
capacitor, the capacity enlargement and the miniaturization are
required. In response to the above situation, as a ceramic powder
used for a ceramic green sheet, a ceramic powder with a minute
particle diameter of 0.5 .mu.m or less is used, and an attempt to
coat on the strippable support has been conducted so that the above
slurry composition can be in a film state around 5 .mu.m or
less.
[0005] However, when a ceramic powder with a minute particle
diameter is used, the packing density and the surface area are
increased, and thus the amount of the binder resin to be used is
increased. According to this situation, the viscosity of slurry
composition is increased, therefore, the coating becomes difficult
and the poor dispersion of the ceramic powder itself has been
generated. In addition, in the steps of the preparation of a
ceramic green sheet, stress such as tension, and bending is loaded,
therefore, in order to withstand such a stress, a resin with a high
degree of polymerization is used as a binder resin.
[0006] In Patent Literature 1 (Japanese Patent Application
Laid-Open (JP-A) No. 2006-089354), there is a disclosure that a
ceramic green sheet obtained from a slurry composition that
contains a polyvinyl acetal resin in which the degree of
polymerization exceeds 2400 and is 4500 or less, the content
percentage of vinylester unit is 1 to 20 mol %, the degree of
acetalization is 55 to 80 mol %; ceramic powders; and an organic
solvent, is excellent in mechanical strength.
[0007] However, recently a much thinner ceramic green sheet is
required, and when the thickness is 2 .mu.m or less in the case
that a super thin layer of ceramic green sheet is prepared from a
slurry composition containing the above ceramic powders, a problem
that a seat attack phenomenon easily occurs is caused.
[0008] Herein, the seat attack phenomenon is a phenomenon of
generating a defect such as break in a ceramic green sheet by
dissolving the binder resin that is contained in the ceramic green
sheet due to an organic solvent in a conductive paste when the
conductive paste to be an internal electrode layer is printed on
the obtained ceramic green sheet. When the seat attack phenomenon
occurs, the electrical performance and reliability of the laminated
ceramic capacitor are decreased, and the yield is extremely
decreased.
[0009] In Patent Literature 2 (JP-A No. 2008-133371), there is a
disclosure of a polyvinyl acetal resin that is obtained by
acetalizing a polyvinyl alcohol resin with a degree of
saponification of 80 mol % or more, and a number-average degree of
polymerization of 1000 to 4000, and characterized in that the
degree of acetalization is 60 to 75 mol %, and the ratio of the
moiety acetalized by acetaldehyde and the moiety acetalized by
butyraldehyde (mol number of the hydroxyl group disappeared by the
acetalization of butyraldehyde/mol number of the hydroxyl group
disappeared by the acetalization of acetaldehyde) is 0.1 to 2.
[0010] However, the miniaturization of the laminated ceramic
capacitor has limitation, and in order to increase the capacity of
chip or to miniaturize the size while keeping the capacity, in
addition to making the ceramic green sheet thinner, a multi-layered
is also required. With such a multi-layered sheet and the
miniaturization, the hygroscopicity in the storage of a ceramic
green sheet has become a problem. That is, there may be cases that
when a binder resin absorbs moisture in the storage of a ceramic
green sheet, the dimensional change occurs; and since thin films
are laminated into a multi-layered form, when the amount of
moisture per layer is large, water evaporates at a stretch and
interlayer peeling called delamination occurs in the delipidation.
Therefore, the humidity control in the storage of a ceramic green
sheet, and the adjustment of delipidation conditions are extremely
important.
[0011] For example, since the glass transition temperature of the
polyvinyl acetal denatured by acetaldehyde becomes high, the
mechanical strength can be improved, however, since the
hydrophobicity of acetaldehyde is low, the hygroscopicity is also
high in an acetal product mixed with butylaldehyde, and the above
problem was not satisfied. Further, even in an acetal product
denatured by only butylaldehyde, sufficient low hygroscopicity was
not satisfied.
[0012] As described above, in Patent Literatures 1 and Patent
Literatures 2, there is no disclosure of the polyvinyl acetal resin
having both the properties that the dimensional change in the
storage of a ceramic green sheet is small, and the delamination
hardly occurs in the delipidation.
CITATION LIST
Patent Literature
[0013] Patent Literature 1: Japanese Patent Application Laid-Open
(JP-A) No. 2006-089354 [0014] Patent Literature 2: JP-A No.
2008-133371
SUMMARY OF INVENTION
Technical Problem
[0015] In view of the situation described above, an object of the
present invention is to provide a polyvinyl acetal resin capable of
obtaining a ceramic green sheet, in which when the polyvinyl acetal
resin is used as a binder resin of the ceramic green sheet, the
mechanical strength is sufficient, the dimensional change in the
storage is small, and further the delamination hardly occurs in the
delipidation. In addition, an object of the present invention is
also to provide a slurry composition using the polyvinyl acetal
resin, a ceramic green sheet, conductive paste, and a laminated
ceramic capacitor.
Solution to Problem
[0016] The present inventors, as a result of the keen study, found
that the polyvinyl acetal resin that has a degree of polymerization
of 200 or more to 6000 or less, a content percentage of vinylester
unit of 0.01 to 30 mol %, a degree of acetalization of 55 to 83 mol
%, and a structural unit represented by Chemical formula (1) in a
molecule shows high glass transition temperature and low water
absorption. In addition, particularly when the polyvinyl acetal
resin is used as a binder resin of a slurry composition that is
used for a ceramic green sheet, the present inventors also found
that the mechanical strength is sufficient, the dimensional change
in the storage is small, and further the delamination hardly occurs
in the delipidation even in a thinner ceramic green sheet, and thus
have completed the present invention.
##STR00002##
[0017] That is, the present invention relates to a polyvinyl acetal
resin that has a degree of polymerization of 200 or more to 6000 or
less, a content percentage of vinylester unit of 0.01 to 30 mol %,
a degree of acetalization of 55 to 83 mol %, and a structural unit
represented by Chemical formula (1) in a molecule.
##STR00003##
[0018] The degree of polymerization of polyvinyl acetal resin
preferably exceeds 1500 and is 4500 or less.
[0019] The polyvinyl acetal resin is obtained preferably by
acetalizing a polyvinyl alcohol resin by using aldehyde that
contains 3-methylbutanal.
[0020] The polyvinyl acetal resin further preferably has a
structural unit represented by Chemical formula (2) and/or Chemical
formula (3) in the molecule.
##STR00004##
[0021] In the above-mentioned polyvinyl acetal resin, preferably
the structural unit represented by Chemical formula (1) is
contained in 30 mol % or more relative to the total molar amount of
all the acetalized structural units.
[0022] The present invention relates to a slurry composition
containing the above-mentioned polyvinyl acetal resin, ceramic
powders, and an organic solvent.
[0023] The present invention relates to a ceramic green sheet
obtained by using the above-mentioned slurry composition.
[0024] The present invention relates to a conductive paste
containing the above-mentioned polyvinyl acetal resin and
conductive powders.
[0025] The present invention relates to a laminated ceramic
capacitor obtained by using the above-mentioned ceramic green
sheet.
[0026] The present invention relates to a laminated ceramic
capacitor obtained by using the above-mentioned conductive
paste.
Advantageous Effects of Invention
[0027] According to the present invention, when the polyvinyl
acetal resin is used as a binder resin of a ceramic green sheet, a
polyvinyl acetal resin capable of obtaining a ceramic green sheet,
in which the mechanical strength is sufficient, the dimensional
change in the storage is small, and further the delamination hardly
occurs in the delipidation, is provided. Further, the polyvinyl
acetal resin of the present invention can be used as a binder resin
of the conductive paste to be an internal electrode.
DESCRIPTION OF EMBODIMENTS
[0028] Hereinafter, the present invention is explained in
detail.
[0029] The degree of polymerization of the polyvinyl acetal resin
of the present invention is 200 or more to 6000 or less. In the
case that the degree of polymerization of the polyvinyl acetal
resin is less than 200, when a thin film ceramic green sheet is
prepared, the mechanical strength is insufficient, and on the other
hand, in the case that the degree of polymerization exceeds 6000,
the polyvinyl acetal resin is not sufficiently dissolved in an
organic solvent, or the solution viscosity is too high, and thus
the coating property and the dispersibility may be decreased. The
degree of polymerization of the polyvinyl acetal resin is
preferably 800 or more, more preferably 1000 or more, further
preferably more than 1500, particularly preferably 1700 or more,
and the most preferably more than 2000. Further, the degree of
polymerization of the polyvinyl acetal resin is preferably 4500 or
less, and more preferably 3500 or less.
[0030] The polyvinyl acetal resin can be produced, for example, by
acetalizing a polyvinyl alcohol resin with a degree of
polymerization of 200 or more to 6000 or less by using aldehyde
that contains at least 3-methylbutanal. The degree of
polymerization of the polyvinyl alcohol resin is preferably 800 or
more, more preferably 1000 or more, further preferably more than
1500, particularly preferably 1700 or more. Further, the degree of
polymerization of the polyvinyl alcohol resin is preferably 4500 or
less, and more preferably 3500 or less.
[0031] Further, the degree of polymerization is determined from
both of the viscosity average degree of polymerization of the
polyvinyl alcohol that is used for the production of a polyvinyl
acetal resin and the viscosity average degree of polymerization of
polyvinyl acetal resin. That is, since the degree of polymerization
is not changed by acetalization, the degree of polymerization of
polyvinyl alcohol resin and the degree of polymerization of the
polyvinyl acetal resin obtained by acetalizing the polyvinyl
alcohol resin are the same. Herein, the viscosity average degree of
polymerization of polyvinyl alcohol resin refers to an average
degree of polymerization determined based on JIS K6726:1994.
Further, when two or more kinds of polyvinyl alcohol resins are
used in a mixture as a polyvinyl alcohol resin, the degree of
polymerization thereof refers to an apparent average degree of
polymerization of the total polyvinyl alcohol resins after the
mixture. On the other hand, the degree of polymerization of
polyvinyl acetal resin refers to a viscosity average degree of
polymerization measured based on a method described in JIS
K6728:1977. Herein also, when the polyvinyl acetal resin is a
mixture of two or more kinds of polyvinyl acetal resins, the degree
of polymerization thereof refers to an apparent viscosity average
degree of polymerization of the total polyvinyl acetal resins after
the mixture.
[0032] The lower limit of the content percentage of vinylester unit
of polyvinyl acetal resin is 0.01 mol %, and the upper limit is 30
mol %. When the content percentage of vinylester unit of polyvinyl
acetal resin is less than 0.01 mol %, the hydrogen bonds in a
molecule and between molecules of the hydroxyl group in polyvinyl
acetal resin are increased, the viscosity of a slurry composition
is too high, the solubility to the organic solvent used for a
conductive paste is also too high, and thus a seat attack
phenomenon occurs. On the other hand, when the content percentage
of vinylester unit of polyvinyl acetal resin exceeds 30 mol %, the
glass transition temperature of polyvinyl acetal resin is
decreased, the flexibility is too strong, and thus the handling
ability, the mechanical strength, and the dimensional stability in
the storage are decreased in a ceramic green sheet. The preferable
lower limit of the content percentage of vinylester unit is 0.5 mol
%, the preferable upper limit is 23 mol %, and the more preferable
upper limit is 20 mol %.
[0033] The polyvinyl acetal resin having a content percentage of
vinylester unit of 0.01 to 30 mol % can be obtained by acetalizing,
for example, a polyvinyl alcohol resin having a content percentage
of vinylester unit of 0.01 to 30 mol %, typically, a polyvinyl
alcohol resin having a degree of saponification of 70 to 99.99 mol
%. The preferable lower limit of the degree of saponification of
the polyvinyl alcohol resin is 77 mol %, the more preferable lower
limit is 80 mol %, and the preferable upper limit is 99.5 mol %.
Herein, the content percentage of vinylester unit of the present
specification means a component ratio of the molar amount of the
vinylester units to the total molar amount of the vinylester units,
the vinyl alcohol units, and the acetalized vinyl alcohol
units.
[0034] The lower limit of the degree of acetalization of the
polyvinyl acetal resin is 55 mol %, and the upper limit is 83 mol
%. When the degree of acetalization of the polyvinyl acetal resin
is less than 55 mol %, the hydrophilicity of the polyvinyl acetal
resin is increased and the polyvinyl acetal resin is hardly
dissolved in an organic solvent, and further, the dimensional
change occurs due to the water absorption in the storage of a
ceramic green sheet, and the delamination occurs in the
delipidation. On the other hand, when the degree of acetalization
of the polyvinyl acetal resin is more than 83 mol %, the remaining
hydroxyl groups are decreased, and not only the toughness of the
polyvinyl acetal resin is impaired but also the productivity is
decreased. Therefore, the preferable lower limit of the degree of
acetalization is 60 mol %, the more preferable lower limit is 65
mol %, and the preferable upper limit is 80 mol %. Herein, the
degree of acetalization in the present specification is not
calculated based on the acetalized structural units but is
calculated based on the molar amount of acetalized vinyl alcohol
units. That is, the degree of acetalization means a component ratio
of the molar amount of the acetalized vinyl alcohol units to the
total molar amount of the vinylester units, the vinyl alcohol
units, and the acetalized vinyl alcohol units.
[0035] As a method of adjusting the degree of acetalization of the
polyvinyl acetal resin of the present invention to 55 to 83 mol %,
for example, a method in which the addition amount of aldehyde to
the polyvinyl alcohol resin, the reaction time after the addition
of aldehyde and an acid catalyst, and the like are appropriately
adjusted is mentioned. For example, aldehyde is preferably added in
an amount of 30 to 150 parts by mass relative to 100 parts by mass
of polyvinyl alcohol resin.
[0036] The content percentage of vinylester unit, the content
percentage of vinyl alcohol unit, and the degree of acetalization
of the polyvinyl acetal resin can be calculated by dissolving the
polyvinyl acetal resin in DMSO-d.sub.6 (dimethyl sulfoxide) and
measuring the .sup.1H-NMR or the .sup.13C-NMR spectrum.
[0037] As a polyvinyl acetal resin of the present invention, a
resin obtained by reacting (acetalizing) the polyvinyl acetal resin
with the aldehyde described later can be used. Such a polyvinyl
acetal resin can be obtained according to a conventionally known
technique, that is, by polymerizing vinylester-based monomer and
saponifying the obtained polymer. As a method for polymerizing
vinylester-based monomer, a conventionally known method such as a
solution polymerization method, a bulk polymerization method, a
suspension polymerization method, and an emulsion polymerization
method can be employed. As a polymerization initiator, depending on
the polymerization method, an azo-based initiator, a peroxide-based
initiator, a redox-based initiator, and the like can be
appropriately selected. As for the saponification reaction,
alcoholysis, hydrolysis, and the like in which a conventionally
known alkali catalyst or acid catalyst is used are applied, among
them a saponification reaction in which a sodium hydroxide (NaOH)
catalyst is employed using methanol as a solvent is easy and the
most preferable.
[0038] Examples of the vinylester-based monomer, for example,
include vinyl formate, vinyl acetate, vinyl propionate, vinyl
butyrate, vinyl isobutyrate, vinyl pivalate, vinyl versatate, vinyl
caproate, vinyl caprylate, vinyl laurate, vinyl palmitate, vinyl
stearate, vinyl oleate, and vinyl benzoate, and particularly vinyl
acetate is preferred.
[0039] Further, when the above-mentioned vinylester-based monomer
is polymerized, other monomers can be copolymerized within the
range not impairing the gist of the present invention. Therefore,
the polyvinyl alcohol resin of the present invention has a concept
including also the polymer that is constituted of vinyl alcohol
unit and other monomer units. Examples of the other monomer units
include, for example, .alpha.-olefin such as ethylene, propylene,
n-butene, and isobutylene; acrylic acid and a salt thereof;
acrylates such as methyl acrylate, ethyl acrylate, n-propyl
acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate,
t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, and
octadecyl acrylate; methacrylic acid and a salt thereof;
methacrylates such as methyl methacrylate, ethyl methacrylate,
n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate,
i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl
methacrylate, dodecyl methacrylate, and octadecyl methacrylate;
acrylamides such as acrylamide, N-methyl acrylamide, N-ethyl
acrylamide, N,N-dimethyl acrylamide, diacetone acrylamide,
acrylamide propanesulfonic acid and a salt thereof, acrylamide
propyl dimethylamine or an acid salt thereof or a quaternary salt
thereof, and N-methylol acrylamide and a derivative thereof;
methacrylamides such as methacrylamide, N-methyl methacrylamide,
N-ethyl methacrylamide, methacrylamide propanesulfonic acid and a
salt thereof, methacrylamido propyl dimethylamine or an acid salt
thereof or a quaternary salt thereof, and N-methylol methacrylamide
and a derivative thereof; vinyl ethers such as methyl vinyl ether,
ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether,
n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether,
dodecyl vinyl ether, and stearyl vinyl ether; nitriles such as
acrylonitrile, and methacrylonitrile; vinyl halide such as vinyl
chloride, and vinyl fluoride; vinylidene halide such as vinylidene
chloride, and vinylidene fluoride; an allylic compound such as
allyl acetate, and allyl chloride; maleic acid and a salt thereof,
ester or an acid anhydride thereof; a vinylcyril compound such as
vinyl trimethoxy silane; and isopropenyl acetate. These monomers
are usually used at a ratio of 20 mol % or less, and more
preferably less than 10 mol % relative to vinylester-based
monomers.
[0040] As the acid catalyst used for acetalization, it is not
particularly limited, both organic acid and inorganic acid can be
used, for example, acetic acid, p-toluenesulfonic acid, nitric
acid, sulfuric acid, hydrochloric acid, and the like can be
mentioned. Among them, hydrochloric acid, sulfuric acid, and nitric
acid are preferably used, and especially, hydrochloric acid, and
sulfuric acid are preferably used.
[0041] A polyvinyl acetal resin of the present invention can be
obtained according to the following method. Firstly, an aqueous
solution of polyvinyl alcohol resin with a concentration of 3 to 15
mass % is adjusted to the temperature range of 80 to 100.degree.
C., and the temperature is gradually cooled over 10 to 60 minutes.
When the temperature is lowered to -10 to 40.degree. C., aldehyde
and acid catalyst are added, and while the temperature is kept at a
certain level, acetalization reaction is performed for 10 to 300
minutes. After that, the reaction mixture is heated to 15 to
80.degree. C. over 30 to 200 minutes, and a ripening process in
which the temperature is maintained for 0 to 360 minutes is
preferably included. Next, the reaction mixture is cooled suitably
to room temperature, washed with water, and then a neutralizer such
as alkali is added, and the resultant is washed and dried, and thus
an intended polyvinyl acetal resin is obtained.
[0042] In the polyvinyl acetal resin of the present invention, it
is important to have a structural unit represented by the Chemical
formula (1). As a method for obtaining such a polyvinyl acetal
resin, for example, a method in which a polyvinyl alcohol resin is
acetalized by using aldehyde that contains 3-methylbutanal can be
mentioned. As described above, when 3-methylbutanal is used for
acetalization, since the number of carbon atoms in a molecule is in
the range of 2 to 6, the productivity of the polyvinyl acetal resin
is excellent, further the structure becomes a structure in which an
isopropyl group is further bound to the carbon atoms that is bound
to two oxygen atoms in an acetal structure unit of the polyvinyl
acetal resin, therefore, a coating film having good property
balance and excellent resistance to moist heat is obtained.
[0043] Further, as the aldehyde used for acetalization of a
polyvinyl alcohol resin, the following aldehyde may be used in
combination within the range not impairing the gist of the present
invention. That is, as the aldehyde containing an alkyl group, an
aryl group, or the like as a substituent, for example, there are an
aliphatic aldehyde such as acetaldehyde, propionaldehyde,
butyraldehyde, isobutyraldehyde, 2-ethyl butyraldehyde,
valeraldehyde, pivalic aldehyde, hexyl aldehyde, 2-ethylhexyl
aldehyde, octyl aldehyde, nonyl aldehyde, decyl aldehyde, and
dodecyl aldehyde, and an alkyl acetal thereof; an alicyclic
aldehyde such as cyclopentane aldehyde, methyl cyclopentane
aldehyde, dimethyl cyclopentane aldehyde, cyclohexane aldehyde,
methyl cyclohexane aldehyde, dimethyl cyclohexane aldehyde, and
cyclohexane acetaldehyde, and an alkyl acetal thereof; a cyclic
unsaturated aldehyde such as cyclopentene aldehyde, and cyclohexene
aldehyde, and an alkyl acetal thereof; an aromatic or unsaturated
bond-containing aldehyde such as benzaldehyde, methyl benzaldehyde,
dimethyl benzaldehyde, methoxy benzaldehyde, phenylacetaldehyde,
phenylpropyl aldehyde, cumin aldehyde, naphthyl aldehyde,
anthraldehyde, cinnamaldehyde, crotonaldehyde, acrolein, and
7-octene-1-al, and an alkyl acetal thereof; a heterocyclic aldehyde
such as furfural, and methylfurfural, and an alkyl acetal thereof;
and the like.
[0044] Further, as the aldehyde that can be used in combination for
acetalization of a polyvinyl alcohol resin in the present invention
and contains a hydroxyl group, a carboxyl group, a sulfonate group,
or a phosphate group as a functional group, there are hydroxyl
group-containing aldehyde such as hydroxyacetaldehyde,
hydroxypropionaldehyde, hydroxybutyraldehyde,
hydroxypentylaldehyde, salicylaldehyde, and dihydroxybenzaldehyde
and an alkyl acetal thereof; acid-containing aldehyde such as
glyoxylic acid and a metal salt thereof or an ammonium salt
thereof, 2-formylacetic acid and a metal salt thereof or an
ammonium salt thereof, 3-formylpropionic acid and a metal salt
thereof or an ammonium salt thereof, 5-formylpentanoic acid and a
metal salt thereof or an ammonium salt thereof,
4-formylphenoxyacetic acid and a metal salt thereof or an ammonium
salt thereof, 2-carboxybenzaldehyde and a metal salt thereof or an
ammonium salt thereof, 4-carboxybenzaldehyde and a metal salt
thereof or an ammonium salt thereof, 2,4-dicarboxybenzaldehyde and
a metal salt thereof or an ammonium salt thereof,
benzaldehyde-2-sulfonic acid and a metal salt thereof or an
ammonium salt thereof, benzaldehyde-2,4-disulfonic acid and a metal
salt thereof or an ammonium salt thereof, 4-formylphenoxysulfonic
acid and a metal salt thereof or an ammonium salt thereof,
3-formyl-1-propanesulfonic acid and a metal salt thereof or an
ammonium salt thereof, 7-formyl-1-heptanesulfonic acid and a metal
salt thereof or an ammonium salt thereof, 4-formylphenoxyphosphonic
acid and a metal salt thereof or an ammonium salt thereof; and an
alkyl acetal thereof; and the like.
[0045] Further, as the aldehyde that can be used in combination for
acetalization of a polyvinyl alcohol resin and contains an amino
group, a cyano group, a nitro group or a quaternary ammonium salt
as a functional group, there are aminoacetaldehyde,
dimethylaminoacetaldehyde, diethylaminoacetaldehyde,
aminopropionaldehyde, dimethylaminopropionaldehyde,
aminobutyraldehyde, aminopentylaldehyde, aminobenzaldehyde,
dimethylaminobenzaldehyde, ethylmethylaminobenzaldehyde,
diethylaminobenzaldehyde, pyrrolidylacetaldehyde,
piperidylacetaldehyde, pyridylacetaldehyde, cyanoacetaldehyde,
.alpha.-cyanopropionaldehyde, nitrobenzaldehyde,
trimethyl-p-formylphenylammonium iodine,
triethyl-p-formylphenylammonium iodine,
trimethyl-2-formylethylammonium iodine, and an alkyl acetal
thereof; and the like.
[0046] As the aldehyde that can be used in combination for
acetalization of a polyvinyl alcohol resin and contains halogen as
a functional group, there are chloroacetaldehyde,
bromoacetaldehyde, fluoroacetaldehyde, chloropropionaldehyde,
bromopropionaldehyde, fluoropropionaldehyde, chlorobutyraldehyde,
bromobutylaldehyde, fluorobutyraldehyde, chloropentylaldehyde,
bromopentylaldehyde, fluoropentylaldehyde, chlorobenzaldehyde,
dichlorobenzaldehyde, trichlorobenzaldehyde, bromobenzaldehyde,
dibromobenzaldehyde, tribromobenzaldehyde, fluorobenzaldehyde,
difluorobenzaldehyde, trifluorobenzaldehyde,
trichloromethylbenzaldehyde, tribromomethylbenzaldehyde,
trifluoromethylbenzaldehyde, and an alkyl acetal thereof, and the
like. For, example, formaldehyde (including paraformaldehyde),
acetaldehyde (including paraacetaldehyde), propionaldehyde,
butyraldehyde, amylaldehyde, hexylaldehyde, heptylaldehyde,
2-ethylhexylaldehyde, cyclohexylaldehyde, furfural, glyoxal,
glutaraldehyde, benzaldehyde, 2-methylbenzaldehyde,
3-methylbenzaldehyde, 4-methylbenzaldehyde, p-hydroxybenzaldehyde,
m-hydroxybenzaldehyde, phenylacetaldehyde,
.beta.-phenylpropionaldehyde, and the like may be used in
combination.
[0047] Among them, when acetalization of the polyvinyl alcohol
resin is performed by using the aldehyde other than 3-methylbutanal
in combination, acetaldehyde is preferable in that the mechanical
strength of the obtained polyvinyl acetal resin is excellent, and
butyraldehyde is preferable in that the low hygroscopicity is
excellent. Further, 3 kinds of aldehyde, that is, 3-methylbutanal,
acetaldehyde, and butyraldehyde can be used in combination. By the
acetalization using acetaldehyde, a structural unit represented by
the Chemical formula (2) is introduced into a polyvinyl alcohol
resin, and by the acetalization using butyraldehyde, a structural
unit represented by the Chemical formula (3) is introduced into a
polyvinyl alcohol resin.
[0048] As in the case of using butyraldehyde and/or acetaldehyde
and 3-methylbutanal in combination, when the obtained polyvinyl
acetal resin has a structural unit other than the structural unit
represented by the Chemical formula (1) as an acetalized structural
unit, a ratio of the structural unit represented by the Chemical
formula (1) that corresponds to the structural unit acetalized by
3-methylbutanal is preferably 30 mol % or more relative to the
total molar amount of all the acetalized structural units.
Specifically, for example, as the structural unit of an acetalized
polyvinyl acetal resin, when containing only a structural unit
represented by Chemical formula (4):
##STR00005##
[0049] (in Chemical formula (4), R is a hydrogen atom or a
hydrocarbon group having any number of carbon atoms (for example, a
methyl group or a propyl group), hydrogen in the hydrocarbon group
may be substituted with any atom or any functional group), a
structural unit represented by Chemical formula (1) in the
polyvinyl acetal resin is preferably 30 mol % or more relative to
the total molar amount of the structural units represented by the
Chemical formula (4) (all the acetalized structural units).
[0050] When the ratio of the structural units represented by the
Chemical formula (1) that corresponds to the structural units
acetalized by 3-methylbutanal is lower than 30 mol % relative to
the total molar amount of all the acetalized structural units in
the polyvinyl acetal resin, the hygroscopicity of the polyvinyl
acetal resin is high, and the dimensional change in the storage of
a ceramic green sheet and the delamination in the delipidation
readily occur. The ratio of the structural units represented by the
Chemical formula (1) that corresponds to the structural units
acetalized by 3-methylbutanal is preferably 40 mol % or more, and
more preferably 50 mol % or more. The ratio is determined by the
following calculation formula.
Ratio(%)=molar amount of structural units represented by Chemical
formula(1)/total molar amount of all the acetalized structural
units.times.100
[0051] Aldehyde used for the polyvinyl acetal resin is preferably
monoaldehyde (one aldehyde group in a molecule). When the
acetalization is performed by a compound containing two or more
aldehyde groups, since the stress-relaxation powers of a
cross-linking site and an uncross-linking site are different from
each other, warp may be generated after being stripped off from
polyethylene terephthalate after drying. Therefore, the aldehyde to
be used is preferably monoaldehyde alone, and even when the
compound containing two or more aldehyde groups is used, the
addition amount of the compound containing two or more aldehyde
groups is preferably less than 0.005 mol %, and more preferably
0.003 mol % or less relative to the vinyl alcohol unit of a
polyvinyl alcohol resin.
[0052] The polyvinyl acetal resin of the present invention may be a
polyvinyl acetal resin containing .alpha.-olefin units. The
preferable lower limit of the content of .alpha.-olefin units in
such a polyvinyl acetal resin is 1 mol %, and the preferable upper
limit is 20 mol %. When the content is less than 1 mol %, the
effect of containing .alpha.-olefin units is insufficient, and when
the content exceeds 20 mol %, the hydrophobicity becomes too
strong, and the dispersibility of ceramic powder is decreased and
the solubility of the polyvinyl alcohol resin to be a raw material
is also decreased, therefore, the production of polyvinyl acetal
resin may become difficult. In the specification, the content
percentage of .alpha.-olefin unit in a polyvinyl acetal resin means
a component ratio of the molar amount of .alpha.-olefin units
relative to the total molar amount of all the structural units
constituting the polyvinyl acetal resin. Herein, the acetalized
structural units are used as the molar amount of acetalized vinyl
alcohol units (usually, has doubled the molar amount of the
acetalized structural units) to calculate the above total molar
amount.
[0053] The glass transition temperature of the polyvinyl acetal
resin of the present invention is preferably 72 to 100.degree. C.,
and more preferably 75 to 95.degree. C. When the glass transition
temperature of the polyvinyl acetal resin is lower than 72.degree.
C., the mechanical strength becomes insufficient, on the other
hand, when the glass transition temperature exceeds 100.degree. C.,
the heating and crimping property is deteriorated, and the
delamination tends to readily occur.
[0054] The slurry composition of the present invention contains the
polyvinyl acetal resin, ceramic powders, and an organic solvent.
Further, in the slurry composition, the polyvinyl acetal resin is
usually used as a binder resin. Since the solution viscosity of the
polyvinyl acetal resin of the present invention does not become too
high even when the polyvinyl acetal resin is dissolved in a mixed
solvent containing ethanol and toluene that are generally used in a
production process of a ceramic green sheet at a ratio of 1:1, the
slurry composition containing the polyvinyl acetal resin of the
present invention has the coating property sufficiently. In
addition, according to the above slurry composition, a ceramic
green sheet having excellent mechanical strength, and favorable
filling property can be obtained efficiently.
[0055] Further, the slurry composition of the present invention may
contain an acryl-based resin, a cellulose-based resin, and the like
as a binder resin in addition to the polyvinyl acetal resin. When a
resin other than the above polyvinyl acetal resin, that is, an
acryl-based resin, a cellulose-based resin, and the like is
contained as a binder resin, the preferable lower limit of the
content percentage of the polyvinyl acetal resin to the total
binder resin is 30 mass %. When the content percentage of the
polyvinyl acetal resin is less than 30 mass %, the mechanical
strength and the heating and crimping property of the obtained
ceramic green sheet may become insufficient.
[0056] As the above ceramic powder, it is not particularly limited,
for example, a powder of alumina, zirconia, aluminum silicate,
titanium oxide, zinc oxide, barium titanate, magnesia, sialon,
spinemulrite, silicon carbide, silicon nitride, aluminum nitride,
and the like is mentioned. These ceramic powders may be used alone,
or may be used in combination of two or more kinds. The preferable
upper limit of the content percentage of ceramic powder is 80 mass
%, and the preferable lower limit is 30 mass %, relative to the
total amount of the slurry composition of the present invention.
When the content percentage of ceramic powder is less than 30 mass
%, the viscosity of the obtained slurry composition becomes too
low, and the handling ability becomes worse during the molding of a
ceramic green sheet, on the other hand, when the content percentage
is more than 80 mass %, the viscosity of the slurry composition is
too high, and the kneading property tends to decrease.
[0057] As the above organic solvent, it is not particularly
limited, for example, ketones such as acetone, methyl ethyl ketone,
dipropyl ketone, and diisobutyl ketone; alcohols such as methanol,
ethanol, isopropanol, and butanol; aromatic hydrocarbons such as
toluene, and xylene; esters such as methyl propionate, ethyl
propionate, butyl propionate, methyl butyrate, ethyl butyrate,
butyl butyrate, methyl pentanoate, ethyl pentanoate, butyl
pentanoate, methyl hexanoate, ethyl hexanoate, butyl hexanoate,
2-ethylhexyl acetate, and 2-ethylhexyl butyrate; glycols such as
methyl cellosolve, ethyl cellosolve, butyl cellosolve,
.alpha.-terpineol, butyl cellosolve acetate, and butyl carbitol
acetate; terpenes such as terpineol; and the like are mentioned.
These organic solvents may be used alone, or may be used in
combination of two or more kinds. Above all, a mixed solvent of
toluene and xylene is preferably used. The content percentage of
the organic solvent is preferably 20 mass % or more to less than 70
mass % relative to the total amount of the slurry composition of
the present invention. In the above range, appropriate kneading
property can be given to the slurry composition of the present
invention. When the content percentage of the organic solvent is 70
mass % or more, the viscosity is too low, and the handling ability
becomes worse during the molding of a ceramic green sheet, on the
other hand, when the content percentage is less than 20 mass %, the
viscosity of the slurry composition becomes too high, and the
kneading property tends to decrease.
[0058] The slurry composition of the present invention may contain
a conventionally known additive such as a plasticizer, a lubricant,
a dispersant, an antistatic agent, and an antioxidant within the
range not impairing the effects of the present invention.
[0059] The kind of the plasticizer is not particularly limited,
however, for example, a phthalate plasticizer such as dioctyl
phthalate, benzyl butyl phthalate, dibutyl phthalate, dihexyl
phthalate, di(2-ethylhexyl) phthalate (DOP), and di(2-ethylbutyl)
phthalate; an adipate plasticizer such as dihexyl adipate, and
di(2-ethylhexyl) adipate (DOA); a glycol-based plasticizer such as
ethylene glycol, diethylene glycol, and triethylene glycol; a
glycol ester-based plasticizer such as triethylene glycol
dibutyrate, triethylene glycol di(2-ethyl butyrate), and
triethylene glycol di(2-ethylhexanoate); and the like are
mentioned. These can be used in combination of two or more kinds.
The content percentage of the plasticizer is not particularly
limited, however, preferably 0.1 to 10 mass %, and more preferably
1 to 8 mass % relative to the total amount of the slurry
composition. Among them, since the volatility is low, and the
flexibility is easily maintained in the case of a ceramic green
sheet, and thus DOP, DOA, and triethylene glycol (2-ethylhexanoate)
are suitable.
[0060] As a method for producing a slurry composition using the
polyvinyl acetal resin of the present invention, it is not
particularly limited, for example, a method in which a binder resin
containing the above polyvinyl acetal resin, ceramic powders, an
organic solvent, and various additives that add as needed, are
mixed using various mixers such as a ball mill, a blender mill, a
three-roller milling machine, or the like is employed.
[0061] Since the slurry composition of the present invention has
the above described constitution, a thin film ceramic green sheet
having sufficient mechanical strength can be produced. The present
invention includes a ceramic green sheet that is obtained using
such a slurry composition.
[0062] As a production method of a ceramic green sheet of the
present invention, it is not particularly limited, a ceramic green
sheet can be produced by a conventionally known production method,
for example, a method in which the slurry composition of the
present invention is casted on a strippable support of polyethylene
terephthalate film and the like, and the solvent and the like are
removed by heating and the like, and then the resultant is stripped
off from the support, and the like are mentioned.
[0063] The conductive paste of the present invention contains the
above polyvinyl acetal resin, and conductive powders, and
preferably contains the above polyvinyl acetal resin, conductive
powders and an organic solvent.
[0064] The conductive paste of the present invention may contain a
resin other than the above polyvinyl acetal resin, such as an
acryl-based resin, and a cellulose-based resin as a binder resin,
in addition to the polyvinyl acetal resin. When an acryl-based
resin, a cellulose-based resin, and the like are contained as a
binder resin, the preferable lower limit of the content percentage
of the above polyvinyl acetal resin to the total binder resin is 30
mass %. When the content percentage of the polyvinyl acetal resin
is less than 30 mass %, the adhesive property between layers tends
to decrease.
[0065] As the conductive powder used for the conductive paste of
the present invention, it is not particularly limited as long as it
has electrical conductivity, for example, copper, nickel,
palladium, platinum, gold, silver, and the like are mentioned. The
preferable upper limit of the content percentage of the conductive
powder is 70 mass %, and the preferable lower limit is 30 mass %,
relative to the total amount of the conductive paste. When the
content percentage of the conductive powder is less than 30 mass %,
there are few conductive components and many organic components,
and thus the change of the shrinkage percentage after firing is
large, and further the carbon components may easily remain. On the
other hand, when the content percentage of the conductive powder
exceeds 70 mass %, the viscosity of the conductive paste is too
high, and thus the coating property and the printability tend to
decrease.
[0066] As the organic solvent used for the conductive paste of the
present invention, it is not particularly limited, and the same
organic solvent as that exemplified in the above as an organic
solvent used for the slurry composition of the present invention,
can be used. These organic solvents may be used alone, or may be
used in combination of two or more kinds. The preferable upper
limit of the content percentage of the organic solvent is 70 mass
%, and the preferable lower limit is 20 mass %, relative to the
total amount of the conductive paste of the present invention. When
the content percentage of organic solvent is less than 20 mass %,
the viscosity is too high, and thus the kneading property tends to
decrease, on the other hand, when the content percentage is more
than 70 mass %, the viscosity of the slurry composition is too low,
and the handling ability tends to deteriorate when the conductive
paste is coated.
[0067] The conductive paste of the present invention may contain a
conventionally known additive such as a plasticizer, a lubricant, a
dispersant, and an antistatic agent within the range not impairing
the effects of the present invention.
[0068] As a method for producing the conductive paste of the
present invention, it is not particularly limited, for example, a
method in which the above polyvinyl acetal resin is mixed with
conductive powders, an organic solvent, a plasticizer, a
dispersant, and the like is mentioned, more specifically, a method
in which a binder resin containing the above polyvinyl acetal
resin, conductive powders, an organic solvent, and various
additives that add as needed are mixed using various mixers such as
a ball mill, a blender mill, a three-roller milling machine, or the
like is mentioned.
[0069] By laminating a ceramic green sheet on which a conductive
paste has been coated, a laminated ceramic capacitor can be
produced. Herein, at least one of the ceramic green sheet and the
conductive paste may be the ceramic green sheet of the present
invention, or the conductive paste of the present invention, the
ceramic green sheet of the present invention on which a conductive
paste that is not the conductive paste of the present invention has
coated may be laminated, a ceramic green sheet that is not the
ceramic green sheet of the present invention on which the
conductive paste of the present invention has coated may be
laminated, and the ceramic green sheet of the present invention on
which the conductive paste of the present invention has coated may
be laminated. As described above, a laminated ceramic capacitor
that is obtained using at least one of the ceramic green sheet of
the present invention and the conductive paste of the present
invention is also included in the present invention.
[0070] As a production method of the laminated ceramic capacitor of
the present invention, it is not particularly limited, a
conventionally known production method can be employed. For
example, a method in which plural ceramic green sheets (the ceramic
green sheets of the present invention, and the like) on the
surfaces of which a conductive paste that is to be an internal
electrode has coated by a screen printing or the like, are piled up
alternately and a laminated body is obtained by heating, crimping,
and the like, the binder component and the like contained in the
laminated body are pyrolytically decomposed and removed
(delipidation treatment), and then an external electrode is
sintered on the end face of the ceramic burned product obtained
through firing, is mentioned.
[0071] The application using the polyvinyl acetal resin of the
present invention is not particularly limited, however, in addition
to a ceramic green sheet or a binder of internal electrode, for
example, a material for paint, and a heat developing sensitive
material are mentioned.
EXAMPLES
[0072] Hereinafter, the present invention is explained in more
detail by referring to Examples, however, the present invention is
not limited at all by these Examples. Further, in the following
Examples, "%" and "parts" mean "mass %" and "parts by mass" unless
otherwise specifically noted.
[0073] Measurements of the physical properties of a polyvinyl
acetal resin were performed according to the following methods.
(Content Percentage of Vinylester Unit, Content Percentage of Vinyl
Alcohol Unit, and Content Percentage of Acetalized Vinyl Alcohol
Unit of Polyvinyl Acetal Resin)
[0074] A polyvinyl acetal resin was dissolved in DMSO-d.sub.6
(dimethyl sulfoxide), and the .sup.1H-NMR spectrum was measured and
calculated.
(Glass Transition Point of Polyvinyl Acetal Resin)
[0075] As DSC (differential scanning calorimetry), using EXTAR6000
(RD220) manufactured by Seiko Instruments Inc., a polyvinyl acetal
resin was heated at a heating rate of 10.degree. C./minute from
30.degree. C. to 150.degree. C. in nitrogen, and then cooled to
30.degree. C., and again heated at a heating rate of 10.degree.
C./minute to 150.degree. C. The value measured after the re-heating
was taken as the glass transition point.
(Water Absorption Rate of Polyvinyl Acetal Resin)
[0076] A test sample with thickness 0.2 mm.times.10 cm.times.10 cm
was dried at 50.degree. C. under reduced pressure for 6 days, and
then the mass of the dried sample was measured when the dried
sample was immersed in pure water at 20.degree. C. for 24 hours,
and the water absorption rate was determined according to the
following equation.
Water absorption rate(mass %)=(mass after immersion-mass of dried
sample before immersion)/(mass of dried sample before
immersion).times.100
Example 1
Preparation of Polyvinyl Acetal Resin
[0077] Into a glass container with an inner volume of 2 L provided
with a reflux condenser, a thermometer, and an anchor-type
impeller, 1295 g of ion exchanged water, and 105 g of polyvinyl
alcohol (PVA-1: polymerization degree 1700, saponification degree
99.0 mol %) were charged, the whole was heated to 95.degree. C. to
thoroughly dissolve the polyvinyl alcohol, and thus a polyvinyl
alcohol aqueous solution (concentration 7.5 mass %) was prepared.
The prepared polyvinyl alcohol aqueous solution was cooled to
13.degree. C. over around 30 minutes while stirring at a rotation
rate of 120 rpm, and then the resultant aqueous solution was added
with 70.5 g of 3-methylbutanal, and further added with 100 mL of
hydrochloric acid with a concentration of 20 mass % as an acid
catalyst that is an acetalization catalyst, and the acetalization
of polyvinyl alcohol was started. After performing the
acetalization for 15 minutes, the whole of the resultant mixture
was heated to 47.degree. C. over 120 minutes, and was kept at
47.degree. C. for 180 minutes, and then cooled to the room
temperature. The resin precipitated by cooling was filtered, and
washed with ion exchanged water (ion exchanged water with 100-fold
amount of that of the resin) 10 times, and then added with 0.3 mass
% sodium hydroxide aqueous solution to neutralization, kept at
50.degree. C. for 5 hours, and then further washed with the ion
exchanged water with 100-fold amount 10 times repeatedly, and
dehydrated, and then dried at 40.degree. C. under reduced pressure
for 18 hours, and thus a polyvinyl acetal resin (PVIV-1) was
obtained. The obtained polyvinyl acetal resin (PVIV-1) had the
content percentage of the vinyl alcohol unit acetalized with
3-methylbutanal of 69.0 mol % (the degree of acetalization was 69.0
mol %), the content percentage of the vinylester unit of 1.0 mol %,
and the content percentage of the vinyl alcohol unit of 30.0 mol
%.
Preparation of Slurry Composition
[0078] 10 parts by mass of the obtained polyvinyl acetal resin was
added to a mixed solvent of 20 parts by mass of toluene and 20
parts by mass of xylene, the resultant mixture was dissolved while
stirring, further added with 8 parts by mass of DOP as a
plasticizer and dissolved while stirring. The obtained resin
solution was added with 100 parts by mass of barium titanate (BT-03
manufactured by Sakai Chemical Industry Co., Ltd. (average particle
diameter 0.3 .mu.m)) as a ceramic powder, and mixed for 48 hours by
a ball mill to obtain a slurry composition.
Example 2
[0079] By using polyvinyl alcohol (PVA-2: polymerization degree
800, saponification degree 99.0 mol %) instead of PVA-1, a
polyvinyl acetal resin (PVIV-2) was obtained in the same manner as
in Example 1 except that 73.5 g of 3-methylbutanal was used. The
content percentage of the vinyl alcohol unit acetalized with
3-methylbutanal was 71.2 mol % (the degree of acetalization was
71.2 mol %), the content percentage of the vinylester unit was 1.0
mol %, and the content percentage of the vinyl alcohol unit was
27.8 mol %. Next, a slurry composition was obtained by using PVIV-2
in the same manner as in Example 1.
Example 3
[0080] By using polyvinyl alcohol (PVA-3: polymerization degree
2400, saponification degree 99.0 mol %) instead of PVA-1, a
polyvinyl acetal resin (PVIV-3) was obtained in the same manner as
in Example 1 except that 70.5 g of 3-methylbutanal was used. The
content percentage of the vinyl alcohol unit acetalized with
3-methylbutanal was 68.4 mol % (the degree of acetalization was
68.4 mol %), the content percentage of the vinylester unit was 1.0
mol %, and the content percentage of the vinyl alcohol unit was
30.6 mol %. Next, a slurry composition was obtained by using PVIV-3
in the same manner as in Example 1.
Example 4
[0081] By using polyvinyl alcohol (PVA-4: polymerization degree
4300, saponification degree 99.0 mol %) instead of PVA-1, a
polyvinyl acetal resin (PVIV-4) was obtained in the same manner as
in Example 1 except that 75.6 g of 3-methylbutanal was used. The
content percentage of the vinyl alcohol unit acetalized with
3-methylbutanal was 73.8 mol % (the degree of acetalization was
73.8 mol %), the content percentage of the vinylester unit was 1.0
mol %, and the content percentage of the vinyl alcohol unit was
25.2 mol %. Next, a slurry composition was obtained by using PVIV-4
in the same manner as in Example 1.
Example 5
[0082] By using polyvinyl alcohol (PVA-5: polymerization degree
1700, saponification degree 88.0 mol %) instead of PVA-1, a
polyvinyl acetal resin (PVIV-5) was obtained in the same manner as
in Example 1 except that 64.6 g of 3-methylbutanal was used. The
content percentage of the vinyl alcohol unit acetalized with
3-methylbutanal was 71.2 mol % (the degree of acetalization was
71.2 mol %), the content percentage of the vinylester unit was 12.0
mol %, and the content percentage of the vinyl alcohol unit was
16.8 mol %. Next, a slurry composition was obtained by using PVIV-5
in the same manner as in Example 1.
Example 6
[0083] By using polyvinyl alcohol (PVA-6: polymerization degree
3500, saponification degree 88.0 mol %) instead of PVA-1, a
polyvinyl acetal resin (PVIV-6) was obtained in the same manner as
in Example 1 except that 62.5 g of 3-methylbutanal was used. The
content percentage of the vinyl alcohol unit acetalized with
3-methylbutanal was 69.7 mol % (the degree of acetalization was
69.7 mol %), the content percentage of the vinylester unit was 12.0
mol %, and the content percentage of the vinyl alcohol unit was
18.3 mol %. Next, a slurry composition was obtained by using PVIV-6
in the same manner as in Example 1.
Example 7
[0084] A polyvinyl acetal resin (PVIV-7) was obtained in the same
manner as in Example 1 except that 81.6 g of 3-methylbutanal was
used. The content percentage of the vinyl alcohol unit acetalized
with 3-methylbutanal was 79.0 mol % (the degree of acetalization
was 79.0 mol %), the content percentage of the vinylester unit was
1.0 mol %, and the content percentage of the vinyl alcohol unit was
20.0 mol %. Next, a slurry composition was obtained by using PVIV-7
in the same manner as in Example 1.
Example 8
[0085] A polyvinyl acetal resin (PVIV-8) was obtained in the same
manner as in Example 1 except that 66.6 g of 3-methylbutanal was
used. The content percentage of the vinyl alcohol unit acetalized
with 3-methylbutanal was 65.0 mol % (the degree of acetalization
was 65.0 mol %), the content percentage of the vinylester unit was
1.0 mol %, and the content percentage of the vinyl alcohol unit was
34.0 mol %. Next, a slurry composition was obtained by using PVIV-8
in the same manner as in Example 1.
Example 9
[0086] By using polyvinyl alcohol (PVA-7: polymerization degree
500, saponification degree 99.0 mol %) instead of PVA-1, a
polyvinyl acetal resin (PVIV-9) was obtained in the same manner as
in Example 1 except that 70.5 g of 3-methylbutanal was used. The
content percentage of the vinyl alcohol unit acetalized with
3-methylbutanal was 69.0 mol % (the degree of acetalization was
69.0 mol %), the content percentage of the vinylester unit was 1.0
mol %, and the content percentage of the vinyl alcohol unit was
30.0 mol %. Next, a slurry composition was obtained by using PVIV-9
in the same manner as in Example 1.
Example 10
[0087] By using polyvinyl alcohol (PVA-8: polymerization degree
5000, saponification degree 99.0 mol %) instead of PVA-1, a
polyvinyl acetal resin (PVIV-10) was obtained in the same manner as
in Example 1 except that 71.5 g of 3-methylbutanal was used. The
content percentage of the vinyl alcohol unit acetalized with
3-methylbutanal was 70.0 mol % (the degree of acetalization was
70.0 mol %), the content percentage of the vinylester unit was 1.0
mol %, and the content percentage of the vinyl alcohol unit was
29.0 mol %. Next, a slurry composition was obtained by using
PVIV-10 in the same manner as in Example 1.
Example 11
[0088] A polyvinyl acetal resin (PVIV-11) was obtained in the same
manner as in Example 1 except that 44.6 g of 3-methylbutanal and
30.5 g of butylaldehyde were used as aldehyde. The content
percentage of the vinyl alcohol unit acetalized with
3-methylbutanal was 42.9 mol %, the content percentage of the vinyl
alcohol unit acetalized with butylaldehyde was 36.1 mol % (the
degree of acetalization was 79.0 mol %), the content percentage of
the vinylester unit was 1.0 mol %, and the content percentage of
the vinyl alcohol unit was 20.0 mol %. Next, a slurry composition
was obtained by using PVIV-11 in the same manner as in Example
1.
Example 12
[0089] A polyvinyl acetal resin (PVIV-12) was obtained in the same
manner as in Example 1 except that 42.6 g of 3-methylbutanal and
20.2 g of acetaldehyde were used as aldehyde. The content
percentage of the vinyl alcohol unit acetalized with
3-methylbutanal was 41.0 mol %, the content percentage of the vinyl
alcohol unit acetalized with acetaldehyde was 38.0 mol % (the
degree of acetalization was 79.0 mol %), the content percentage of
the vinylester unit was 1.0 mol %, and the content percentage of
the vinyl alcohol unit was 20.0 mol %. Next, a slurry composition
was obtained by using PVIV-12 in the same manner as in Example
1.
Comparative Example 1
[0090] A polyvinyl acetal resin (PVB-A) was obtained in the same
manner as in Example 1 except that 65.0 g of butylaldehyde was used
as aldehyde. The content percentage of the vinyl alcohol unit
acetalized with butylaldehydeal was 68.8 mol % (the degree of
acetalization was 68.8 mol %), the content percentage of the
vinylester unit was 1.0 mol %, and the content percentage of the
vinyl alcohol unit was 30.2 mol %. Next, a slurry composition was
obtained by using PVB-A in the same manner as in Example 1.
Comparative Example 2
[0091] By using polyvinyl alcohol (PVA-9: polymerization degree
3500, saponification degree 99.0 mol %) instead of PVA-1, a
polyvinyl acetal resin (PVB-B) was obtained in the same manner as
in Example 1 except that 25.1 g of acetaldehyde and 31.0 g of
butylaldehyde were used as aldehyde. The content percentage of the
vinyl alcohol unit acetalized with butylaldehyde was 36.0 mol %,
the content percentage of the vinyl alcohol unit acetalized with
acetaldehyde was 44.4 mol % (the degree of acetalization was 80.4
mol %), the content percentage of the vinylester unit was 1.0 mol
%, and the content percentage of the vinyl alcohol unit was 18.6
mol %. Next, a slurry composition was obtained by using PVB-B in
the same manner as in Example 1.
Comparative Example 3
[0092] By using polyvinyl alcohol (PVA-10: polymerization degree
6500, saponification degree 88.0 mol %) instead of PVA-1, a
polyvinyl acetal resin (PVIV-13) was obtained in the same manner as
in Example 1 except that 69.0 g of 3-methylbutanal was used as
aldehyde. The content percentage of the vinyl alcohol unit
acetalized with 3-methylbutanal was 73.9 mol % (the degree of
acetalization was 73.9 mol %), the content percentage of the
vinylester unit was 12.0 mol %, and the content percentage of the
vinyl alcohol unit was 14.1 mol %. Next, it was tried to prepare a
slurry composition by using PVIV-13 in the same manner as in
Example 1, however, the dispersion was poor, and thus a slurry
composition was not obtained.
Comparative Example 4
[0093] By using polyvinyl alcohol (PVA-11: polymerization degree
150, saponification degree 99.0 mol %) instead of PVA-1, a
polyvinyl acetal resin (PVIV-14) was obtained in the same manner as
in Example 1 except that 69.0 g of 3-methylbutanal was used as
aldehyde. The content percentage of the vinyl alcohol unit
acetalized with 3-methylbutanal was 66.8 mol % (the degree of
acetalization was 66.8 mol %), the content percentage of the
vinylester unit was 1.0 mol %, and the content percentage of the
vinyl alcohol unit was 32.2 mol %. Next, a slurry composition was
obtained by using PVIV-14 in the same manner as in Example 1.
Comparative Example 5
[0094] By using polyvinyl alcohol (PVA-12: polymerization degree
1700, saponification degree 69.0 mol %) instead of PVA-1, a
polyvinyl acetal resin (PVIV-15) was obtained in the same manner as
in Example 1 except that 39.0 g of 3-methylbutanal was used as
aldehyde. The content percentage of the vinyl alcohol unit
acetalized with 3-methylbutanal was 50.0 mol % (the degree of
acetalization was 50.0 mol %), the content percentage of the
vinylester unit was 31.0 mol %, and the content percentage of the
vinyl alcohol unit was 19.0 mol %. Next, a slurry composition was
obtained by using PVIV-15 in the same manner as in Example 1.
Comparative Example 6
[0095] A polyvinyl acetal resin (PVIV-16) was obtained in the same
manner as in Example 1 except that 54.0 g of 3-methylbutanal was
used as aldehyde. The content percentage of the vinyl alcohol unit
acetalized with 3-methylbutanal was 53.6 mol % (the degree of
acetalization was 53.6 mol %), the content percentage of the
vinylester unit was 1.0 mol %, and the content percentage of the
vinyl alcohol unit was 45.4 mol %. Next, a slurry composition was
obtained by using PVIV-16 in the same manner as in Example 1.
Comparative Example 7
[0096] A polyvinyl acetal resin (PVB-C) was obtained in the same
manner as in Example 1 except that 45.0 g of butylaldehyde was used
as aldehyde. The content percentage of the vinyl alcohol unit
acetalized with butylaldehydeal was 78.0 mol % (the degree of
acetalization was 78.0 mol %), the content percentage of the
vinylester unit was 1.0 mol %, and the content percentage of the
vinyl alcohol unit was 21.0 mol %. Next, a slurry composition was
obtained by using PVB-C in the same manner as in Example 1.
Preparation of Ceramic Green Sheet
[0097] On the polyester film to which detached treatment had been
performed, a slurry composition prepared in Examples 1 to 12 or
Comparative Examples 1 to 7 was coated using a coater bar so that
the thickness of the resultant after drying was 1 .mu.m, and the
resultant was air-dried at room temperature for 1 hour, and then
dried at 80.degree. C. for 3 hours by a hot air drier, and
continuously dried at 120.degree. C. for 2 hours, and thus a
ceramic green sheet was obtained.
Preparation of Conductive Paste
[0098] 100 parts by mass of nickel powder (2020SS manufactured by
Mitsui Mining 85 Smelting Co., Ltd.) as a conductive powder, 5
parts by mass of ethyl cellulose (STD-100 manufactured by The Dow
Chemical Company), and 60 parts by mass of Terpineol-C
(manufactured by Nippon Terpene Chemicals, Inc.) as a solvent were
mixed, and then kneaded with a three-roller milling machine to
obtain a conductive paste.
Preparation of Ceramic Burned Substance
[0099] On one surface of the above-obtained ceramic green sheet,
the above-obtained conductive paste was coated by a screen printing
so that the thickness of a conductive layer after drying was around
1.0 .mu.m, and the resultant was dried to form the conductive
layer. The ceramic green sheet with the conductive layer was cut
into 5 cm square pieces, 100 pieces were piled up, and heated and
crimped at a temperature of 70.degree. C. under a pressure of 150
kg/cm.sup.2 for 10 minutes, and thus a laminated body was obtained.
The obtained laminated body was heated to 400.degree. C. at a
heating rate of 3.degree. C./minute under a nitrogen atmosphere,
and kept for 5 hours, and then heated to 1350.degree. C. at a
heating rate of 5.degree. C./minute, and kept for 10 hours, and
thus a ceramic burned substance was obtained.
Evaluation
Evaluation of Mechanical Strength
[0100] The obtained ceramic green sheet was stripped off from the
polyester film, and the condition of the sheet was observed and
evaluated on three scales shown below. The results were shown in
Table 1.
A: Tear and break were not observed in a ceramic green sheet. B:
Tear and break were slightly observed. C: Tear and break were
observed.
Evaluation of Dimensional Stability in the Storage
[0101] A ceramic green sheet with 30 cm.times.30 cm was stood still
under constant temperature and constant humidity of 23.degree. C.
and 65% RH, the dimensional changes after the film production and
10 days after the film production were measured, and evaluated on
two scales shown below. The results were shown in Table 1.
A: The dimensional change of a ceramic green sheet was less than
0.1%, and warp was not observed. B: The dimensional change of a
ceramic green sheet was 0.1% or more, and/or warp was observed.
Evaluation of Delamination of Sintered Body
[0102] The obtained ceramic burned substance (that had been cooled
to room temperature) was divided into half, observed with an
electron microscope, and the presence or absence of delamination of
the ceramic layer and the conductive layer was observed, and
evaluated on three scales shown below. The results were shown in
Table 1.
A: Delamination was not observed. B: Delamination was slightly
observed. C: Delamination was observed.
TABLE-US-00001 TABLE 1 Capacitor Polyvinyl acetal resin Ceramic
green sheet (Ceramic Poly- Poly- Vinyl Glass Water Me- Dimen-
burned vinyl meri- alcohol Acetalized transition absorption chan-
sional substance) acetal zation Unit Vinylester vinyl alcohol
temperature rate ical stability Delamina- resin Aldehyde degree
[mol %] Unit [mol %] Unit [mol %] [.degree. C.] [%] strength in
storage tion Example 1 PVIV-1 3-Methylbutanal 1700 30.0 1.0 69.0 81
4.4 A A A Example 2 PVIV-2 3-Methylbutanal 800 27.8 1.0 71.2 80 4.2
B A A Example 3 PVIV-3 3-Methylbutanal 2400 30.6 1.0 68.4 82 4.3 A
A A Example 4 PVIV-4 3-Methylbutanal 4300 25.2 1.0 73.8 79 3.8 A A
A Example 5 PVIV-5 3-Methylbutanal 1700 16.8 12.0 71.2 74 3.3 B A A
Example 6 PVIV-6 3-Methylbutanal 3500 18.3 12.0 69.7 75 3.6 A A A
Example 7 PVIV-7 3-Methylbutanal 1700 20.0 1.0 79.0 77 3.1 A A A
Example 8 PVIV-8 3-Methylbutanal 1700 34.0 1.0 65.0 84 4.6 A A A
Example 9 PVIV-9 3-Methylbutanal 500 30.0 1.0 69.0 82 4.4 B A A
Example 10 PVIV- 3-Methylbutanal 5000 29.0 1.0 70.0 82 4.3 A A B 10
Example 11 PVIV- 3-Methylbutanal 1700 20.0 1.0 42.9 72 3.0 B A A 11
Butylaldehyde 36.1 Example 12 PVIV- 3-Methylbutanal 1700 20.0 1.0
41.0 94 4.9 A A A 12 Acetaldehyde 38.0 Comparative PVB-A
Butylaldehyde 1700 30.2 1.0 68.8 73 7.5 C B C Example 1 Comparative
PVB-B Butylaldehyde 3500 18.6 1.0 36.0 97 11.5 A B C Example 2
Acetaldehyde 44.4 Comparative PVIV- 3-Methylbutanal 6500 14.1 12.0
73.9 73 3.2 Slurry was not prepared because Example 3 13 of the
poor dispersion Comparative PVIV- 3-Methylbutanal 150 32.2 1.0 66.8
83 4.6 C Mold Release Example 4 14 from PET film was impossible
Comparative PVIV- 3-Methylbutanal 1700 19.0 31.0 50.0 70 5.3 C B C
Example 5 15 Comparative PVIV- 3-Methylbutanal 1700 45.4 1.0 53.6
88 8.4 B B C Example 6 16 Comparative PVB-C Butylaldehyde 1700 21.0
1.0 78 70 5.4 C B C Example 7
INDUSTRIAL APPLICABILITY
[0103] According to the present invention, a polyvinyl acetal resin
capable of obtaining a ceramic green sheet that has sufficient
mechanical strength, in which the dimensional change in the storage
is small, and the delamination hardly occurs in the delipidation,
can be provided.
* * * * *