U.S. patent application number 10/366407 was filed with the patent office on 2003-08-28 for electroconductive paper and carrier for electronic member using said paper.
This patent application is currently assigned to LINTEC CORPORATION. Invention is credited to Morio, Sadakazu, Yagura, Mitsuaki.
Application Number | 20030159787 10/366407 |
Document ID | / |
Family ID | 27750868 |
Filed Date | 2003-08-28 |
United States Patent
Application |
20030159787 |
Kind Code |
A1 |
Yagura, Mitsuaki ; et
al. |
August 28, 2003 |
Electroconductive paper and carrier for electronic member using
said paper
Abstract
There are disclosed electroconductive paper which comprises on
at least one side thereof, an
electroconductive-substance-containing layer having a surface
resistivity of at most 10.sup.7 .OMEGA. and a surface pH in the
range of 5.5 to 8.0, and which has preferably a half-life period of
static electricity being at most 0.2 second and a concentration of
sulfate ions of at most 1 ppm, the ions being extracted by
subjecting 1 g of electroconductive paper to an extraction
treatment in 70 milliliter (mL) of deionized water at 100.degree.
C. for 1 hour; and a carrier for an electronic member which carrier
uses the electroconductive paper. The above electroconductive paper
is capable of suppressing the corrosion of the electronic member
due to the generation of sulfate ions and the like, and thereby is
well suited for use as a carrier for the electronic member.
Inventors: |
Yagura, Mitsuaki; (Saitama,
JP) ; Morio, Sadakazu; (Saitama, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
LINTEC CORPORATION
Tokyo
JP
|
Family ID: |
27750868 |
Appl. No.: |
10/366407 |
Filed: |
February 14, 2003 |
Current U.S.
Class: |
162/138 ;
162/146; 162/181.1 |
Current CPC
Class: |
D21H 27/16 20130101;
C09K 3/16 20130101; H01B 1/24 20130101; H01B 1/22 20130101; H01B
1/20 20130101 |
Class at
Publication: |
162/138 ;
162/146; 162/181.1 |
International
Class: |
D21H 017/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 27, 2002 |
JP |
2002-051902 |
Claims
What is claimed is:
1. Electroconductive paper which comprises on at least one side
thereof, an electroconductive-substance-containing layer having a
surface resistivity of at most 10.sup.7 .OMEGA. and a surface pH in
the range of 5.5 to 8.0.
2. The electroconductive paper according to claim 1, which has a
half-life period of static electricity being at most 0.2
second.
3. The electroconductive paper according to claim 1, wherein the
concentration of sulfate ions thereof is at most 1 ppm, which are
extracted by subjecting 1 g of electroconductive paper to an
extraction treatment in 70 milliliter (mL) of deionized water at
100.degree. C. for 1 hour.
4. The electroconductive paper according to claim 2, wherein the
concentration of sulfate ions thereof is at most 1 ppm, which are
extracted by subjecting 1 g of electroconductive paper to an
extraction treatment in 70 mL of deionized water at 100.degree. C.
for 1 hour.
5. A carrier for an electronic member which carrier makes use of
the electroconductive paper as set forth in claim 1.
6. A carrier for an electronic member which carrier makes use of
the electroconductive paper as set forth in claim 2.
7. A carrier for an electronic member which carrier makes use of
the electroconductive paper as set forth in claim 3.
Description
BACKGROUND OF THE INVENTION
[0001] 1 . Field of the Invention
[0002] The present invention relates to electroconductive paper,
and in particular to electroconductive paper which has an
electroconductive-substance-containing layer possessing a surface
resistivity of a specific value or less and an almost neutral
surface pH on at least one side thereof, and which is well suited
for use as a carrier for an electronic member.
[0003] 2 . Description of the Related Arts
[0004] A fine electronic member has heretofore been supported on a
carrier in the case of being transported or stored for the purpose
of preventing individual electronic member from damaging each
other, or of enhancing the workability in a subsequent step. For
instance, in the case of a light-emitting diode having a metallic
portion, transfer of the aforesaid diode is carried out by
fastening a terminal of the metal portion to a narrow carrier in
the form of tape by means of a hot melt adhesive or the like.
[0005] The characteristics required of such carrier include (1) to
be electroconductive for the purpose of preventing dust or the like
from adhering thereto or preventing the electronic member from
being electrically damaged due to static electricity; (2) the
surface pH of the carrier to be almost neutral in order that the
metallic portion of the electronic member may not be corroded; (3).
ions of a corrosive impurity, particularly sulfate ions are not to
be generated in order that the metallic portion of the electronic
member may not be corroded; and the like.
[0006] There have hitherto been employed as an electroconductive
carrier, a carrier made of plastics containing powdery
electroconductive substance such as carbon black, fibrous
electroconductive substance such as carbon fibers and paper coated
or incorporated inside with the above-exemplified electroconductive
substance. However, a carrier made of plastics involves the
problems of a fear of causing environmental pollution in the
incineration after its service, liability to moisture condensation.
On the other hand, a carrier made of paper, although being less
liable to moisture condensation and generation of static
electricity as compared with the carrier made of plastics, involves
the problems of a fear of corroding the electronic member by a
large amount of sulfate ions generated from the use of aluminum
sulfate as a fixing agent or the use of an additive for paper
making containing chemicals as a source of producing sulfate ions
and the like.
SUMMARY OF THE INVENTION
[0007] In the light of the above-mentioned circumstances, a general
object of the present invention is to provide electroconductive
paper which is imparted with electroconductivity on at least one
side thereof, and capable of suppressing the corrosion of the
electronic member due to the generation of sulfate ions or the like
and at the same time, to provide a carrier for the electronic
member by using the above-mentioned electroconductive paper.
[0008] Other objects of the present invention will become obvious
from the text of this specification hereinafter disclosed.
[0009] As a result of intensive extensive research and
investigation accumulated by the present inventors in order to
achieve the objects as mentioned before, it has been found that the
objects can be achieved by electroconductive paper which has an
electroconductive-substance-containi- ng layer possessing a surface
resistivity of a specific value or less and an almost neutral
surface pH on at least one side thereof. The present invention has
been accomplished by the above-mentioned findings and
information.
[0010] Specifically, the present invention provides the
followings.
[0011] 1. Electroconductive paper which comprises on at least one
side thereof, an electroconductive substance-containing layer
having a surface resistivity of at most 10.sup.7 .OMEGA. and a
surface pH in the range of 5.5 to 8.0.
[0012] 2. The electroconductive paper as set forth in the preceding
item 1, which has a half-life period of static electricity being at
most 0.2 second.
[0013] 3. The electroconductive paper as set forth in the preceding
item 1 or 2, wherein the concentration of sulfate ions thereof is
at most 1 ppm, which are extracted by subjecting 1 g of
electroconductive paper to an extraction treatment in 70 milliliter
(mL) of deionized water at 100.degree. C. for 1 hour.
[0014] 4. A carrier for the electronic member which carrier makes
use of the electroconductive paper as set forth in the preceding
item 1, 2 or 3.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0015] The electroconductive paper according to the present
invention needs to comprise on at least one side thereof, an
electroconductive-substance-containing layer. The constitution
thereof is not specifically limited, but is exemplified by
monolayer or multi-layer electroconductive paper composed only of a
layer or layers each containing an electroconductive substance;
double-layered electroconductive paper composed of a layer
containing an electroconductive substance and a layer not
containing the same; triple-layered electroconductive paper
composed of a layer not containing an electroconductive substance
and on both the sides thereof, two layers each containing the same;
and the like.
[0016] The layer containing an electroconductive substance and the
layer not containing the same each constituting the
electroconductive paper according to the present invention is made
of paper manufactured by a conventional sheet making process.
[0017] As fibers for raw material of paper to be used in the
present invention, there are cited natural pulp and synthetic pulp,
various fibers and the like to be used in combination with the
natural pulp as desired. The above-mentioned natural pulp is not
specifically limited, but may be optionally selected for use from
wood pulp, non-wood pulp such as basi fiber ganpi fiber.
[0018] In addition, examples of usable kinds of pulp include
mechanical pulp such as ground wood pulp which is obtained by
mechanically treating a raw material; chemical pulp which is
obtained by treating a raw material with a chemical agent such as
sulfite pulp, soda pulp, sulfate pulp (kraft pulp), nitrate pulp
and chlorine pulp; semi-chemical pulp which is obtained by chemical
treatment and mechanical treatment in combination; bleached pulp
which is obtained by subjecting any of the foregoing pulp to
bleaching refining treatment; unbleached pulp which is not
subjected bleaching refining treatment; semi-bleached pulp which is
intermediate between bleached pulp and unbleached; and the like
pulp. Of these are preferable needle-leaved tree bleached kraft
pulp (N-BKP), broad-leaved tree bleached kraft pulp (L-BKP) and a
mixture thereof. Reclaimed waste pulp is also usable.
[0019] Examples of synthetic pulp to be used when desired include
synthetic pulp obtained from such material as polyethylene and
polypropylene. Examples of various fiber include organic fiber such
as acrylic fiber, rayon fiber, phenolic resin fiber, polyamide base
fiber, polyester base fiber and polyolefin base fiber and inorganic
fiber such as glass fiber and alumina fiber.
[0020] As the electroconductive substance to be used in the present
invention, mention is made of powdery carbonaceous
electroconductive substance such as carbon black and graphite
electroconductive powdery metal oxide such as tin oxide, titanium
oxide and zinc oxide; metal fiber such as copper, nickel and zinc;
electroconductive fiber coated by metal vapor deposition; carbon
fiber; organic electroconductive high molecular compounds such as
polythiazine, halogenated polyacetylene, poly-p-phenylene, and the
like. The above-cited electroconductive substances are preferably
in the form of fiber rather than powder in order to prevent dust
generation.
[0021] Any of these electroconductive substance may be used alone
or in combination with at least one other. The amount thereof to be
blended is selected usually in the range of 1 to 100 parts by
weight based on 100 parts by weight of the above-mentioned fiber
for raw material of paper. The amount thereof, when being less than
1 part by weight based on the same, gives rise to insufficient
electroconductivity, whereas the amount, when being more than 100
parts by weight based on the same, results in failure to exhibit
the working effect on enhancing electroconductivity considering the
amount and rather leads to the cause for deteriorating the physical
properties as electroconductive paper. For this reason, the amount
to be blended is in the range of preferably 1 to 50 parts by
weight, particularly preferably 5 to 20 parts by weight based on
the same.
[0022] In the electroconductive paper according to the present
invention, the electroconductive-substance-containing layer has a
surface resistivity of at most 10.sup.7 .OMEGA. . The surface
resistivity, when being in more than 10.sup.7 .OMEGA. , gives rise
to insufficient electroconductivity, thereby brings about unsuccess
in sufficiently exerting the function of preventing dust or the
like from adhering the paper surface or preventing the electronic
member from being electrically damaged due to static electricity,
whereby the objects of the present invention are not achieved. The
surface resistivity thereof is preferably at most 10.sup.5 .OMEGA..
The lower limit thereof is not restricted in particular, but is
usually 10.sup.1 .OMEGA., approximately. The measuring method for
the surface resistivity will be described hereinafter.
[0023] The surface pH of the electroconductive-substance-containing
layer is in the range of 5.5 to 8.0. The surface pH thereof, when
being less than 5.5, causes corrosion of the metallic portion of
the electronic member, whereby the objects of the present invention
are not achieved. On the other hand, the surface pH thereof, when
being more than 8.0, sometimes brings about corrosion of terminals
of the electronic member depending upon the raw material thereof,
or exerts adverse influence up on the performance of the electronic
member. The measuring method for the surface pH will be described
hereinafter.
[0024] The half-life period of static electricity of the
electroconductive paper according to the present invention is
preferably at most 0.2 second. The half-life period thereof, when
being more than 0.2 second, will cause insufficiency in preventing
charge-up due to static electricity, thereby gives rise to a fear
of unsuccess in sufficiently exerting the function of preventing
dust or the like from adhering the surface or preventing the
electronic member from being electrically damaged due to static
electricity. The lower limit thereof is not restricted in
particular, but is usually 0.01 second, approximately. The
measuring method for the half-life period of static electricity
will be described hereinafter.
[0025] In addition, the concentration of sulfate ions of the
electroconductive paper according to the present invention is
preferably at most 1 ppm, which are extracted by subjecting 1 g of
electroconductive paper to an extraction treatment in 70 milliliter
(mL) of deionized water at 100.degree. C. for 1 hour. When the
concentration of sulfate ions thereof is more than 1 ppm, the oxide
film on the surface of metallic terminals is liable to be attacked,
thereby unfavorably increasing the corrosion rate. The measuring
method for the concentration of sulfate ions will be described
hereinafter.
[0026] The electroconductive paper in which the surface pH and
concentration of sulfate ions are each within the above-described
range can be produced by neutralized paper making. By the term
neutralized paper making as used herein is meant sizing treatment
without the use of aluminum sulfate or neutralization by chemical
treatment at the time of paper making.
[0027] The electroconductive paper having such properties according
to the present invention is well suited for use as a carrier for
the electronic member.
[0028] The electroconductive-substance-containing layer in the
electrocondIuctive paper according to the present invention can be
produced by preparing aqueous suspension containing the
above-mentioned fiber for raw material of paper and
electroconductive substance each at a prescribed proportion, and
subjecting the resultant suspension to paper making by a
conventional well known method.
[0029] The aforesaid aqueous suspension may be properly optionally
incorporated when desired with any of a variety of neutral
additives for paper making which have heretofore been used for
paper making such as fixing agent, wet paper strengthening agent,
dry paper strengthening agent, sizing agent and filler. It is
preferable in the present invention to prevent the use of the
additives for paper making which contain a compound that comes to
be a source of generating sulfate ions from the resultant
electroconductive paper.
[0030] As the aforesaid fixing agent, mention is made of
polyethylene-imine resin, a derivative thereof, polyacrylamide
resin, polyamine resin, acrylic resin, polyamide resin,
polyethylene oxide resin, polyamide/polyamine resin, a derivative
thereof, basic polyaluminum chloride, basic polyaluminum hydroxide
and alumina sol.
[0031] As the aforesaid wet, paper strengthening agent, mention is
made of epoxidized polyamide resin, polyamide resin, epoxy resin,
melamine resin, melamine/formalin resin and urea/formalin
resin.
[0032] As the aforesaid dry paper strengthening agent, mention is
made of acrylic resin, polyamine resin, polyacrylamide resin,
oxidized starch, carboxylated starch, cationized starch, vegetable
gum, polyvinyl alcohol resin and carboxymethyl cellulose .
[0033] As the aforesaid sizing agent, mention is made of at least
one species selected from sizing agents such as alkyl ketene dimer,
alkenyl maleic anhydride, polystyrene base resin and higher fatty
acid base resin.
[0034] As the aforesaid filler, mention is made of mineral base
fillers such as talc, kaolin, calcined kaolin, clay, diatomaceous
earth, ground calcium carbonate, magnesium, carbonate, aluminuim
hydroxide, titanium dioxide, silica, aluminosilicate and bentonite,
organic base fillers such as polystyrene grains and urea/formalin
resin grains.
[0035] The aforesaid aqueous suspension may be properly optionally
incorporated when desired with an additive aid for paper making
such as dyestuff, slime controlling agent, antifoaming agent and
thickening agent.
[0036] In the present invention, a sheet containing an
electroconductive substance is prepared by carrying out paper
making by the use of the aqueous suspension which comprises fiber
as raw material of paper, an electroconductive substance and any of
a variety of additives to be used when desired and which is
prepared in the above-mentioned manner, so that. monolayer
electroconductive paper is obtained. On the other hand in the case
where the electroconductive paper according to the present
invention contains a layer which is free from an electroconductive
substance, a sheet free from an electroconductive substance is
prepared by carrying out paper making by the use of the aqueous
suspension which comprises fibers as raw material of paper and any
of a variety of additives to be used when desired and which is
prepared in the same manner as above except that the aqueous
suspension is free from an electroconductive substance.
Subsequently, the above-prepared sheet containing an
electroconductive substance and the sheet free from an
electroconductive substance are together subjected to paper making,
so that electroconductive paper having double-layer or triple-layer
structure is obtained.
[0037] It is possible to coat or impregnate the surfaces of the
electroconductive paper according to the present invention obtained
in the foregoing manner with a surface strengthening agent such a
oxidized starch, polyvinyl alcohol, surface sizing agent, pigment
and any of various high molecular compounds during or after a paper
making step by a coating method using a size press, gate roll, air
knife or blade roll.
[0038] In the electroconductive paper according to the present
invention, there are usable the above-cited additives for paper
making, additive aids for paper making and coating/impregnating
chemical agents, each being anionic, cationic, nonionic or
amphoteric. However as mentioned hereinabove, it is preferable not
to use the additives, additive aids and chemical agents containing
a compound that comes to be a source of generating sulfate ions in
order to suppress the concentration of sulfate ions to at most 1
ppm, which are extracted by subjecting 1 g of electroconductive
paper to an extraction treatment in 70 mL of deionized water at
100.degree. C. for 1 hour. As the additives, additive aids and
chemical agents containing a compound that comes to be a source of
generating sulfate ions, mention is made, for instance, of emulsion
solutions dispersed with an anionic emulsifier containing a sulfate
such as aluminum sulfate, basic aluminum sulfate, ferrous sulfate,
sulfonates and ester salts of ether sulfuric acid.
[0039] A proper basis weight of the electroconductive paper
according to the present invention is in the range of 64 to 600
g/m.sup.2 (total basis weight of all layers for a plurality of
layers), preferably 200 to 500 g/m.sup.2.
[0040] In summarizing the working effects and advantages of the
present invention, it is possible to provide electroconductive
paper which is imparted with electroconductivity on at least one
side thereof and capable of suppressing the corrosion of the
electronic member due to the generation of sulfate ions and the
like and at the same time, to provide a carrier for the electronic
member using the aforesaid electroconductive paper.
[0041] In the following, the present invention will be described in
more detail with reference to comparative examples and working
examples, which however shall never limit the present invention
thereto. The physical properties of the electroconductive paper
obtained in the examples were determined by the procedures as
described hereunder.
[0042] (1) Surface pH
[0043] Surface pH was determined in accordance with JAPAN TAPPI 1-1
A.
[0044] (2) Surface Resistivity .OMEGA.
[0045] Surface resistivity .OMEGA. was determined by a method in
which both the ends of electroconductive paper measuring 210 mm by
210 mm in size in the machine direction (direction of paper
parallel to the advance direction of a paper machine) were
sandwiched with clips each made of stainless steel with 145 mm wide
so that the distance therebetween was set on 200 mm, each of the
clips was brought into contact with an electrode of a tester
(available from TMK Co. Ltd. under the trade name
"Multitester-VF-10"), and the indicated value at that time was
regarded as the surface resistivity.
[0046] (3) Amount of Extracted Sulfate Ions
[0047] 1 g of electroconductive paper sample was immersed in 70 mL
of deionized water so as to carry out extraction at 100.degree. C.
for 1 hour, and a measurement was made of the sulfate ions (ppm) in
the resultant extract, wherein the deionized water was defined as
having a volume specific resistance of at least 15 k
.OMEGA..multidot.cm (25.degree. C.). At that time, in order to
prevent the hand from coming in direct contact with the
electroconductive paper, use was made of double-layered cotton
gloves covered with outer gloves made of polyethylene.
[0048] The measurement of extracted sulfate ions was carried out by
means of ion chromatography (available, from Japan Dionex Co. Ltd.
under the trade name "DX320") using as the standard sulfate ion
solution, the solution of 1,000 g of K.sub.2 SO.sub.4 dissolved in
1 liter of deionized water. The ion extraction vessel used therein
was a vessel which was equipped with a hermetically sealing lid and
made of polypropylene, wherein the impurity level in the vessel was
limited to at most one fifth of a possible impurity level at the
time of measuring the electroconductive paper sample.
[0049] (4) Half-life Period of Static Electricity
[0050] Half-life period of static electricity was determined by the
use of a static neostometer (available from Shishido Shokai Japan
Co. Ltd.) at a temperature of 23.degree. C. at a relative humidity
of 50% and at an applied voltage of 10 kV.
[0051] (5) Corrosion Test for Carrier
[0052] Corrosion test for carrier was carried out by a corrosion
accelerating test under the conditions including a temperature of
60.degree. C. and a relative humidity of 90% for 10 days by
sandwiching a terminal portion of a copper-made light emitting
diode the terminal of which was plated with silver with carriers in
which electroconductive paper was used, and then change in color,
if any, was visually observed.
EXAMPLE 1
[0053] A sheet was prepared from a paper material prepared by
adding to 100 parts by weight of wood pulp (N-BKP/L-BKP ratio by
weight being 20/80), 10 parts by weight expressed in terms of solid
content, of carbon pigment (available from Mikuni Pigment Co. Ltd.
under the trade name "Grand Black AM-1000") as the
electroconductive substance; 0.05 part by weight expressed in terms
of solid content, of polyethylene-imine resin (available from
Nippon Shokubai Kagaku Kogyo Co. Ltd. under the trade name "Epomin
P-1000") as the fixing agent; 0.5 part by weight expressed in terms
of solid content, of epoxidized polyamide resin (available from
Japan PMC Co. Ltd. under the trade name "WS-570") as the wet paper
strengthening agent; and 0.5 part by weight expressed in terms of
solid content, of polystyrene resin (available from Seiko Chemical
Industries Co. Ltd. under the trade name "Pearl Gum CS") as the
sizing agent. The resultant sheet was coated on both sides thereof
in an amount of 3 g/m.sup.2 expressed in terms of solid content
with oxidized starch (available from Oji Corn Starch Co. Ltd. under
the trade name "Oji Ace A") as the surface strengthening agent at
the time of paper making with a size press coater. As a result,
there was obtained electroconductive paper which had a basis weight
of 300 g/m.sup.2, and the physical properties of which are given in
Table 1.
EXAMPLE 2
[0054] A sheet was prepared from a paper material prepared by
adding to 100 parts by weight of wood pulp (N-BKP/L-BKP ratio by
weight being 20/80), 5 parts by weight of carbon fiber (available
from Toho Tenacs Co. Ltd. under the trade name "Besfite Ae" cut
into a size of 3 mm) as the electroconductive substance; 0.5 part
by weight expressed in terms of solid content, of epoxidized
polyamide resin (available from Japan PMC Co. Ltd. under the trade
name "WS-570") as the wet paper strengthening agent; and 0.5 part
by weight expressed in terms of solid content, of polystyrene resin
(available from Seiko Chemical Industries Co. Ltd. under the trade
name "Pearl Gum CS") as the sizing agent.
[0055] As a result, there was obtained electroconductive paper
which had a basis weight of 300 g/m.sup.2, and the physical
properties of which are given in Table 1.
EXAMPLE 3
[0056] By the use of a paper machine for double-layer paper making
which was equipped with Fourdrinier wire and a cylinder mould,
double-layer paper making was carried out to produce
electroconductive paper composed of two layers consisting of a
layer free from an electroconductive substance and a layer
containing an electroconductive substance.
[0057] A paper material for the Fourdrinier wire was prepared by
adding to 100 parts by weight of wood pulp (N-BKP/L-BKP ratio by
weight being 20/80), 0.5 part by weight expressed in terms of solid
content, of epoxidized polyamide resin (available from Japan PMC
Co. Ltd. under the trade name "WS-570") as the wet paper
strengthening agent; 0.5 part by weight expressed in terms of solid
content, of polystyrene resin (available from Seiko Chemical
Industries Co. Ltd. under the trade name "Pearl Gum CS") as the
sizing agent; and 0.5 part by weight expressed in terms of solid
content, of acrylic resin (available from Arakawa Chemical
Industries Co. Ltd. under the trade name "Polystoron 191") as the
dry paper strengthening agent.
[0058] On the other hand, a paper material for the cylinder mould
was prepared by using the materials same as in Example 1.
[0059] The resultant paper was coated on both sides thereof in an
amount of 3 g/m.sup.2 expressed in terms of solid content with
oxidized starch (available from Oji Corn Starch Co. Ltd. under the
trade name "Oji Ace A") as the surface strengthening agent at the
time of paper making with a size press coater. As a result, there
was obtained electroconductive paper which was composed of two
layers and had a basis weight of 400 g/m.sup.2 in which the
Fourdrinier wire side had a basis weight of 350 g/m.sup.2, and the
cylinder mould side had a basis weight of 50 g/m.sup.2. The
physical properties of the resultant electroconductive paper are
given in Table 1.
COMPARATIVE EXAMPLE 1
[0060] A sheet was prepared from a paper material prepared by
adding to 100 parts by weight of wood pulp (N-BKP/L-BKP ratio by
weight being 20/80), 10 parts by weight expressed in terms of solid
content, of carbon pigment (available from Mikuni Pigment Co. Ltd.
under the trade name "Grand Black AM-1000") as the
electroconductive substance; 0.5 part by weight expressed in terms
of solid content, of rosin size (available from Arakawa Chemical
Industries Co. Ltd. under the trade name "Sizepine E-50") as the
sizinig agent; 1 part by weight expressed in terms of solid
content, of aluminum sulfate (available from Sumitomo Aluminum Co.
Ltd. under the trade name "Aluminum sulfate"); and 0.5 part by
weight expressed in terms of solid content, of epoxidized polyamide
resin (available from Japan PMC Co. Ltd. under the trade name
"WS-570") as the wet paper strengthening agent. The resultant paper
material was coated on both sides thereof in an amount of 3
g/m.sup.2 expressed in terms of solid content with oxidized starch
(available from Oji Corn Starch Co. Ltd. under the trade name "Oji
Ace A") as the surface strengthening agent at the time of paper
making with a size press coater. As a result, there was obtained
electroconductive paper which had a basis weight of 300 g/m.sup.2,
and the physical properties of which are given in Table 1.
COMPARATIVE EXAMPLE 2
[0061] A sheet was prepared from a paper material prepared by
adding to 100 parts by weight of wood pulp (N-BKP/L-BKP ratio by
weight being 20/80), 10 parts by weight expressed in terms of solid
content, of carbon pigment (available from Mikuni Pigment Co. Ltd.
under the trade name "Grand Black AM-1000") as the
electroconductive substance; 0.05 part by weight expressed in terms
of solid content, of polyethylene-imine resin (available from
Nippon Shokubai Kagaku Kogyo Co. Ltd. under the trade name "Epomin
P-1000") as the fixing agent; 0.5 part by weight expressed in terms
of solid content, of epoxidized polyamide resin (available from
Japan PMC Co. Ltd. under the trade name "WS-570") as the wet paper
strengthening agent. The resultant paper material was impregnated
with an acrylic emulsion dispersed with an anionic emulsifier
containing a sulfonate (available from Rohm and Hass Co. Ltd. under
the trade name "PrimalTR-934HS") in an amount of 10 g/m.sup.2
expressed in terms of solid content as the dry paper strengthening
agent at the time of paper making with a size press coater.
[0062] As a result, there was obtained electroconductive paper
which had a basis weight, of 300 g/m.sup.2, and the physical
properties of which are given in Table 1.
COMPARATIVE EXAMPLE 3
[0063] A sheet was prepared from a paper material prepared by
adding to 100 parts by weight of wood pulp (N-BKP/L-BKP ratio by
weight being 20/80), 0.5 part by weight expressed in terms of solid
content, of epoxidized polyamide resin (available from Japan PMC
Co. Ltd. under the trade name "WS-570") as the wet paper
strengthening agent; and 0.5 part by weight expressed in terms of
solid content, of polystyrene resin (available from Seiko Chemical
Industries Co. Ltd. under the trade name "Pearl Gum CS") as the
sizing agent. The resultant paper material was coated on both sides
thereof in an amount of 3 g/m.sup.2 expressed in terms of solid
content with oxidized starch (available from Oji Corn Starch Co.
Ltd. under the trade name "Oji Ace A") as the surface strengthening
agent at the time of paper making with a size press coater. As a
result, there was obtained paper which was free from any
electroconductive substance and had a basis weight of 300
g/m.sup.2, and the physical properties of which are given in Table
1.
1 TABLE 1 Sulfate Half-time ions period Corrosion Surface extracted
of static test Surface resistivity amount electricity (color pH
(.OMEGA.) (ppm) (sec) change) Example 1 6.0 1.1 .times. 10.sup.3
0.753 0.12 none Example 2 6.2 7.5 .times. 10.sup.2 0.482 0.14 none
Example 3 6.0 1.1 .times. 10.sup.4 0.679 0.11 none Comparative 4.6
1.5 .times. 10.sup.3 6.262 0.12 yes Example 1 Comparative 4.6 1.7
.times. 10.sup.3 1.855 0.11 yes Example 2 Comparative 6.1 .sup. 1.0
.times. 10.sup.10 0.523 0.35 yes Example 3
* * * * *