U.S. patent application number 12/085686 was filed with the patent office on 2009-08-27 for part for producing castings and process of making the same.
This patent application is currently assigned to Kao Corporation. Invention is credited to Yoshimasa Takagi, Akira Yoshida.
Application Number | 20090211717 12/085686 |
Document ID | / |
Family ID | 38092221 |
Filed Date | 2009-08-27 |
United States Patent
Application |
20090211717 |
Kind Code |
A1 |
Takagi; Yoshimasa ; et
al. |
August 27, 2009 |
Part for Producing Castings and Process of Making the Same
Abstract
A process of producing a part for casting including the step of
preparing a raw material slurry containing inorganic fibers,
organic fibers, a thermosetting resin, a papermaking binder, and a
sulfonate-based and/or a cellulose-based dispersant. The raw
material slurry preferably further contains an inorganic powder
and/or a water repellant.
Inventors: |
Takagi; Yoshimasa; (Tochigi,
JP) ; Yoshida; Akira; (Aichi, JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
Kao Corporation
Tokyo
JP
|
Family ID: |
38092221 |
Appl. No.: |
12/085686 |
Filed: |
November 29, 2006 |
PCT Filed: |
November 29, 2006 |
PCT NO: |
PCT/JP2006/323797 |
371 Date: |
October 29, 2008 |
Current U.S.
Class: |
162/145 ;
162/141; 162/148 |
Current CPC
Class: |
B22C 1/08 20130101 |
Class at
Publication: |
162/145 ;
162/141; 162/148 |
International
Class: |
D21H 13/40 20060101
D21H013/40; D21H 13/36 20060101 D21H013/36; D21H 13/50 20060101
D21H013/50 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 30, 2005 |
JP |
2005-346813 |
Nov 30, 2005 |
JP |
2005-346814 |
Claims
1. A process of producing a part for casting comprising the step of
preparing a raw material slurry comprising inorganic fibers,
organic fibers, a thermosetting resin, a papermaking binder, and a
sulfonate-based and/or a cellulose-based dispersant.
2. The process of producing a part for casting according to claim
1, wherein the raw material slurry further comprises an inorganic
powder and/or a water repellant.
3. The process of producing a part for casting according to claim
2, wherein the mass content of the inorganic powder is 0% to 70%,
the mass content of the inorganic fibers is 1% to 60%, the mass
content of the organic fibers is 1% to 40%, the mass content of the
thermosetting resin is 1% to 40%, the mass content of the
papermaking binder is 1% to 10%, and the mass content of the water
repellant is 0% to 5%, the total of the inorganic powder, the
inorganic fibers, the organic fibers, the thermosetting resin, the
papermaking binder, and the water repellant being 100%.
4. The process of producing a part for casting according to claim
1, wherein the sulfonate-based dispersant is a sodium
.beta.-naphthalenesulfonate-formalin condensate having a degree of
polycondensation of 3 to 6.
5. The process of producing a part for casting according to claim
1, wherein the cellulose-based dispersant is a propylene oxide
adduct derivative of cellulose.
6. The process of producing a part for casting according to claim
2, wherein the raw material slurry contains at least one of
obsidian, mullite, and graphite as the inorganic powder, at least
one of carbon fiber, rock wool, and ceramic fiber as the inorganic
fibers, and at least one of a phenol resin, an epoxy resin, and a
furan resin as the thermosetting resin.
7. A part for casting comprising inorganic fibers, organic fibers,
a thermosetting resin, a papermaking binder, and a sulfonate-based
and/or a cellulose-based dispersant.
8. The part for casting according to claim 7, which generates not
more than 250 l/m.sup.2 of combustion gas at 1000.degree. C.
9. The part for casting according to claim 7, which further
comprises an inorganic powder and/or a water repellant.
10. The part for casting according to claim 9, wherein the mass
content of the inorganic powder is 0% to 70%, the mass content of
the inorganic fibers is 1% to 60%, the mass content of the organic
fibers is 1% to 40%, the mass content of the thermosetting resin is
1% to 40%, the mass content of the papermaking binder is 1% to 10%,
and the mass content of the water repellant is 0% to 5%, the total
of the inorganic powder, the inorganic fibers, the organic fibers,
the thermosetting resin, the papermaking binder, and the water
repellant being 100%.
11. The part for casting according to claim 7, wherein the
sulfonate-based dispersant is a sodium
.beta.-naphthalenesulfonate-formalin condensate having a degree of
polycondensation of 3 to 6.
12. The part for casting according to claim 7, wherein the
cellulose-based dispersant is a propylene oxide adduct derivative
of cellulose.
13. The part for casting according to claim 9, wherein the raw
material slurry contains at least one of obsidian, mullite, and
graphite as the inorganic powder, at least one of carbon fiber,
rock wool, and ceramic fiber as the inorganic fibers, and at least
one of a phenol resin, an epoxy resin, and a furan resin as the
thermosetting resin.
Description
TECHNICAL FIELD
[0001] The present invention relates to a part for producing
castings (hereinafter "part for casting" or simply "part") that can
be use as a runner, etc. in the production of castings and a
process of making the part.
BACKGROUND ART
[0002] Applicant has proposed in JP 2004-174605A a technique
relating to a part for casting that can be used as a runner, etc.
in the production of castings. The technique provides a tube formed
of base paper containing organic fiber, inorganic fiber, and a
binder, in which the tube is light, easy to handle, and easy to
dispose of after use for casting as compared with historically used
refractory materials.
DISCLOSURE OF THE INVENTION
[0003] It is desirable that such a part for casting containing
organic fiber, inorganic fiber, and a binder has a minimized
content of the organic fiber in order to reduce the generation of
combustion gas (hereinafter sometimes referred simply to as "gas")
accompanying thermal decomposition of the organic fiber during
casting. If the organic fiber content is reduced, however, the
components will have poor dispersibility, tending to result in poor
formation to yield a high proportion of defective castings. In the
case of making base paper by papermaking, in particular, reduction
in organic fiber content is liable to produce wavy paper.
[0004] The present invention relates to a satisfactory part for
casting and a process of producing the part, in which a specific
dispersant is used to allow for reducing an organic fiber content.
The invention also relates to a satisfactory part for casting
having a reduced organic fiber content and a process of producing
the part.
[0005] The present inventors have found that a satisfactory part
for casting can be obtained by using a specific dispersant even
when an organic fiber content is reduced and completed the
invention.
[0006] Based on the above finding, the present invention provides a
process of producing a part for casting including the step of
preparing a raw material slurry containing inorganic fibers,
organic fibers, a thermosetting resin, a papermaking binder, and a
sulfonate-based and/or a cellulose-based dispersant.
[0007] The present invention also provides a part for casting
containing inorganic fibers, organic fibers, a thermosetting resin,
a papermaking binder, and a sulfonate-based and/or a
cellulose-based dispersant.
[0008] BRIEF DESCRIPTION OF THE DRAWING
[0009] FIG. 1 is a schematic perspective of an embodiment of the
present invention.
[0010] FIG. 2 is a cross-section schematically illustrating a
casting mold that is used to evaluate blowback in Examples.
DETAILED DESCRIPTION OF THE INVENTION
[0011] The present invention will be described based on its
preferred embodiments with reference to the accompanying
drawings.
[0012] The part for casting according to the invention is first
described based on its preferred embodiment. The part 10 of the
embodiment shown in FIG. 1 contains inorganic powder, inorganic
fibers, organic fibers, a thermosetting resin, a papermaking
binder, and a water repellant and, in addition, 0.001% to 10% by
mass, preferably 0.01% to 10% by mass, of a sulfonate-based and/or
a cellulose-based dispersant based on 100% by mass of the total of
the inorganic powder, inorganic fibers, organic fibers,
thermosetting resin, papermaking binder, and water repellant. Use
of such amount of a dispersant enables production of a good part
while minimizing the content of the organic fibers.
[0013] Examples of the sulfonate-based dispersant include a sodium
.beta.-naphthalenesulfonate-formalin condensate, sodium
ligninsulfonate, a sodium melaminesulfonate-formalin condensate, an
aromatic aminosulfonic acid sodium salt polymer, sodium
polystyrenesulfonate, a styrenesulfonic acid-sodium maleinsulfonate
copolymer, sodium polycyclopentadienesulfonate, and an aliphatic
dienesulfonic acid sodium salt polymer. Preferred of them is a
sodium .beta.-naphthalenesulfonate-formalin condensate having a
degree of polycondensation of 3 to 6 for consideration of the
formation of wet base paper (a wet mat of fiber).
[0014] The cellulose-based dispersant preferably has high water
solubility and preferably dissolves completely in a 1% by mass
aqueous solution. Such a cellulose-based dispersant is exemplified
by cellulose propylene oxide adduct derivatives, e.g.,
hydroxypropyl cellulose and hydroxypropylmethyl cellulose.
Hydroxypropyl cellulose is preferred for consideration of the
formation of wet base paper (a wet fiber mat).
[0015] The dispersants can be used either individually or as a
combination of two or more thereof.
[0016] The ratio of the inorganic powder/inorganic fibers/organic
fibers/thermosetting resin (solid content)/papermaking binder
(solid content)/water repellant in the part for casting of the
invention is 0-70%/1-60%/1-40%/1-40%/1-10%/0-5% by mass, preferably
40-70%/1-10%/1-25%/1-25%/1-10%/0-5% by mass, more preferably
50-70%/1-8%/1-20%/10-25%/3-7%/0-1% by mass, taking the total of
these components as 100% by mass. The content of the inorganic
powder being within the range recited, the part has good shape
retention during pouring, and a fiber molded article has good
surface conditions and good release from a mold. With the content
of the inorganic fibers being within the range recited, good
papermaking properties and good shape retention during pouring are
obtained. With the organic fiber content being in the range
recited, good papermaking properties are obtained, and combustion
gas generation during pouring can be held down so as to prevent a
blowback (a back-flow of molten metal). The thermosetting resin
content falling in that range, the casting mold has good molding
properties, and a fiber molded article has good shape retention
after pouring and good surface smoothness. The papermaking binder
content being in that range, the binder makes the powder component
in the slurry cling to the fibers while causing the fibers to
moderately intermingle with one another to form flocks optimum for
sheet formation and thereby securing good yield. With the water
repellant content being in the range recited, the base paper formed
by papermaking can be converted into a part for casting with a
minimum amount of an adhesive because the adhesive applied is
prevented from penetrating into the base paper. Furthermore, after
the part for casting is buried in molding sand, the water content
of the molding sand is prevented from penetrating into the
part.
[0017] Examples of the inorganic powder include obsidian, mullite,
and graphite including flaky graphite and earthy graphite. One or
more than one kind of the inorganic powders can be selected for
use. In the case where a casting has a carbon content of 4.2% by
mass or less, carburizing (penetration of carbon into a casting to
make the casting brittle) occurs. In that case, inorganic powder
having a silica content should be used to prevent carburizing from
a casting carbide. It is preferred to use obsidian, mullite, etc.
as an inorganic powder. When the carbon content of the casting is
4.2% by mass or more, the part does not need to contain inorganic
powder.
[0018] The inorganic fiber serves mainly to constitute the skeleton
of the part. For example, it does not burn even with the heat of
molten metal and continues serving to retain the shape of the part
during casting. Examples of the inorganic fiber include artificial
mineral fibers, such as carbon fiber and rock wool, ceramic fibers,
and natural mineral fibers. They can be used either alone or in
combination of two or more thereof. Carbon fiber that maintains
high strength even in high temperatures, such as pitch-based carbon
fiber or polyacrylonitrile (PAN)-based carbon fiber, is preferred
for effectively reducing thermal shrinkage accompanying
carbonization of the thermosetting resin. PAN-based carbon fiber is
especially preferred.
[0019] The inorganic fiber preferably has an average length of 0.1
to 10 mm, more preferably 0.5 to 8 mm, in view of the quality of a
fiber molded product obtained by papermaking technique. Continuous
fibers of 10 mm or longer may be used as cut in a slurry in a
refiner, etc. to have an average fiber length controlled to 0.1 to
10 mm.
[0020] Examples of the organic fibers include pulp fibers,
fibrillated synthetic fibers, and regenerated fibers (e.g., rayon
fiber). These fibers are used either individually or as a mixture
of two or more thereof. Preferred of them is pulp fiber from the
viewpoint of sheet forming properties, strength after drying, and
cost.
[0021] Examples of the pulp fibers include not only wood pulp but
non-wood pulp, such as cotton pulp, linter pulp, bamboo, and straw.
These kinds of pulp, whether virgin or recycled, can be used either
alone or in combination thereof. From the standpoint of
availability, environmental conservation, and reduction of
production cost, used paper pulp is preferred.
[0022] It is preferred for the organic fibers to have an average
length of 0.1 to 20 mm, more preferably 0.5 to 10 mm, from the
viewpoint of surface smoothness and impact strength of the
resulting base sheet.
[0023] The thermosetting resin is a component necessary to retain
the low- and high-temperature strength of the part 10 and to
provide a paper tube with good surface properties which contribute
to improve the surface smoothness of a casting. The thermosetting
resins include phenol resins, epoxy resins, and furan resins.
Phenol resins are preferred in view of reduced generation of
combustible gas, resistance to burning, and a high carbon residue
content after thermal decomposition (carbonization) as high as 25%
or more to form a carbonized film to provide a casting with an
improved casting surface. As used herein the terms "carbon residue
content" refers to a value obtained by heating a thermosetting
resin sample in a nitrogen atmosphere from room temperature up to
1200.degree. C. at a rate of temperature rise of 50.degree. C./min,
measuring the mass of the residue, and dividing the mass of the
residue with the mass before heating. The mass after heating is
lighter than that before heating because combustion gas is released
from the resin during heating. Usable phenol resins include novolak
phenol resins requiring a curing agent and resol type phenol resins
requiring no curing agent. In order to minimize elution of free
phenol into white water, it is preferred to use a low-release
phenol resin, such as high-molecular-weight resol phenol resins
synthesized using a basic catalyst or an acidic catalyst. In using
a novolak phenol resin, a curing agent is needed. Since the curing
agent easily dissolves in water, it is preferably applied to the
surface of a dewatered fiber mat. Preferred examples of the curing
agent include hexamethylenetetramine. The thermosetting resins can
be used either individually or as a combination of two or more
thereof.
[0024] Examples of the combustion gas include carbon monoxide,
carbon dioxide, and hydrocarbons such as methane and ethylene.
[0025] Examples of the papermaking binder include natural polymers
such as starch, gelatin, guar gum, and carboxymethyl cellulose
(CMC); water soluble synthetic polymers such as KAIMEN
(polyamideamine-epichlorohydrin resin), polyvinyl alcohol (PVA),
polyacrylamide (PAM), and polyethylene oxide (PEO);
styrene-butadiene latices, acrylonitrile-butadiene latices, acrylic
latices, and vinyl acetate latices; and inorganic binders such as
colloidal silica and alumina-based binders. Preferred of them are
KAIMEN, CMC, and acrylic latices for their powder-fixing
properties. The papermaking binder is preferably used in an amount
of 0.01% to 5%, more preferably 0.02% to 1%, on a solid basis based
on the mass of the organic fibers. These papermaking binders can be
used either individually or as a combination of two or more
thereof.
[0026] The part 10 can contain a water repellant to prevent
penetration of the adhesive described supra into base paper and to
prevent loss of strength due to moisture absorption. Silicone
surface active agents, fluorine-containing surface active agents,
fat and oil type surface active agents, hydrophobic surface active
agents, and hydrophobic polymers can be used as a water repellant.
The water repellant is preferably applied to both the inner and
outer sides of the part 10 and dried to prevent deterioration of
strength due to moisture absorption. The water repellant is
advisably used in the form of an aqueous solution or emulsion that
is convenient to handle upon use. The water repellants may be used
either individually or as a combination of two or more thereof.
Silicone, fluorine-containing or fat and oil type emulsions are
preferably used. When the water repellant is added to a slurry,
particularly preferred is an alkyl ketene dimer (AKD), which
exhibits excellent water repellency in a neutral region at a small
amount and is superior in acid resistance and alkali resistance to
rosin, etc. The water repellant may be added in an adequate amount
to a raw material slurry or applied to the part. Coating techniques
include spraying, brush coating, dipping, and pouring. Spraying,
dipping or pouring is preferred for productivity. Coating by
"pouring" as used here is achieved by hosing a pumped liquid over
the part to be coated. In cases where the part for casting is used
in a dry working environment or when the thermosetting resin serves
for water repellency depending on its kind or amount used, the
water repellant may be dispensed with.
[0027] The part 10 may contain other components such as a
flocculant and a colorant in appropriate amounts in addition to the
above described components.
[0028] The part 10 preferably has a surface roughness Ra of 20
.mu.m or less, more preferably 10 .mu.m or less. The surface
roughness Ra is measured, e.g., with Surtronic 10 from Rank Taylor
Hobson.
[0029] The part 10 is preferably formed of base paper containing
the aforementioned components. The base paper preferably has a
tensile strength of 40 N/15 mm or more, more preferably 80 N/15 mm
or more. The tensile strength is measured in a tensile test of a 15
mm wide specimen cut out of 0.7 mm thick base paper on a Tensilon
lo universal tester RTA500 from A & D Co., Ltd. When the
thickness of a sample is not 0.7 mm, the tensile strength as
measured is converted to strength per unit cross-sectional area for
comparison. Base paper having a tensile strength within the above
range does not tear or break when spirally wound to make paper
tubing as a part for casting as in the present embodiment.
[0030] To secure strength, the part 10 preferably has a compressive
strength of 20 N or higher, more preferably 40 N or higher, before
use in casting. The term "compressive strength" as used herein is a
compressive strength of the wall of tubing measured as follows. A
60 mm wide specimen cut out of a part for casting is set on a
compressive strength testing instrument (e.g., a Tensilon universal
tester RTA 500 from A & D) with its cut area horizontal and
compressed at a rate of 10 mm/min.
[0031] While the thickness of the part 10 is subject to variation
according to where it is applied, it is preferably 0.5 to 6 mm,
more preferably 1 to 3 mm, for securing strength required of a part
for casting and air permeability and reducing the production
cost.
[0032] It is preferred for the part 10 before use in casting to
have a water content of not more than 20% by mass, more preferably
10% by mass or less, to minimize water vapor generation on contact
with molten metal. Water vapor generation causes blowback (back
flow) of molten metal from the pour spout.
[0033] A preferred embodiment of the process of producing a part
for casting according to the present invention will then be
described with reference to the production of the part 10.
[0034] The part 10 is composed of two tubular paper plies 11 and 12
each formed of spirally wound base paper. The production of the
part 10 starts with preparation of base paper for making the
tubular paper plies 11 and 12.
[0035] Respective raw material slurries for the base paper for
making the tubular paper plies 11 and 12 are prepared from the
above-described inorganic powder, inorganic fibers, organic fibers,
thermosetting resin, papermaking binder, and dispersant. Each of
the slurries is converted to a sheet form (wet fiber mat),
dewatered, and dried in accordance with a wet papermaking technique
to obtain base paper.
[0036] Examples of the dispersing medium of the slurry include
water, white water, and solvents such as ethanol and methanol.
Water is preferred in view of stability in wet fiber mat formation
and dewatering, stability of quality of the resulting base paper,
cost, and ease of handling.
[0037] If desired, the slurry can contain additives including a
flocculant and an antiseptic.
[0038] The slurry thus prepared is then converted into base paper
for making paper tubing by a papermaking process.
[0039] Papermaking can be carried out by any technique selected
from, for example, continuous papermaking methods using a cylinder
paper machine, a Fourdrinier paper machine, a short-wire paper
machine or a twin-wire paper machine, and batchwise papermaking
methods including manual papermaking.
[0040] In order for the base paper to keep the shape retention and
mechanical strength after papermaking, the wet fiber mat is
dewatered to reduce its water content preferably to 30% or smaller,
more preferably to 10% or smaller. Dewatering of the fiber layer
can be conducted by, for example, suction, blowing pressurized air
or pressing with a pressure roll or a pressure plate.
[0041] The dewatered fiber mat is forwarded to a drying step. Any
means for drying that has conventionally been used to dry paper can
be used in the drying step.
[0042] The base paper after dewatering and drying preferably has a
tensile strength of 40 N/15 mm or more, more preferably 80 N/15 mm,
to be wound into tubing. The tensile strength is measured in a
tensile test of a 15 mm wide specimen cut out of 0.7 mm thick base
paper on the above mentioned Tensilon universal tester. When the
thickness of samples to be measured is not 0.7 mm, the tensile
strength as measured is converted to strength per unit
cross-sectional area for comparison.
[0043] The base paper after dewatering and drying preferably has a
buckling strength of 3 N or higher, more preferably 4 N or higher,
in view of the strength of the resulting part for casting. The
buckling strength is measured by a 3-point bending test as follows.
A specimen of base sheet measuring 60 mm in width and 100 mm in
length is set on a tester with a 40 mm span length, and compressed
from above by an indenter having a width of 60 mm and a diameter of
6 mm at the tip. From the same viewpoint, the base paper after
dewatering and drying preferably has a buckling displacement of 3
mm or more, more preferably 5 mm or more. The term "buckling
displacement" means the amount of displacement of base paper at the
maximum stress point in the above described 3-point bending
test.
[0044] It is preferred that the base paper after dewatering and
drying generates not more than 250 cc/g, more preferably not more
than 200 cc/g, of combustion gas per unit mass of the part at
1000.degree. C. The amount of combustion gas generated is measured
using equipment for measuring the amount of generated combustion
gas (No. 682 Gas Pressure Tester from Harry W. Dietert Co.). The
amount of combustion gas generated is preferably as small as
possible. The practically reachable lower limit is 0.1 to 1
cc/g.
[0045] The base paper after dewatering and drying preferably has a
surface roughness Ra of 20 .mu.m or less, more preferably 10 .mu.m
or less. The surface roughness Ra is measured, e.g., with Surtronic
10 from Rank Taylor Hobson.
[0046] In the case where the water repellant is used, the base
paper after dewatering and drying preferably has water repellency
of 15% or less, more preferably 10% or less. The water repellency
of base paper is measured, e.g., in accordance with the method
specified in JIS P8140, paper and board--determination of water
absorptiveness--Cobb method. The contact time between a test piece
and water was set at 60 seconds.
[0047] The base sheet after dewatering and drying preferably has a
density of 0.62 to 0.9 g/m.sup.3, more preferably 0.64 to 0.75
g/m.sup.3. With this density, break of base paper during winding
into tubing due to insufficient strength and difficulty in winding
due to excessive bending stiffness of base paper are avoided.
[0048] The resulting webs of base paper was each slit into a strip
of predetermined width, and the strips are successively lap-wound
helically with an overlap between adjacent turns either in the same
direction or different directions to be shaped into a tubular form.
When wound in the same direction, the outer strip is preferably
wound in a manner to cover the exposed edge of the preceding turns
of the inner strip. In lap winding, an adhesive is applied as
appropriate to form tubing. The width of the strips, the width of
overlap, the inner diameter of paper tubing, and the like are
decided according to the mass of a casting (i.e., the amount of
molten metal passing the paper tube) and required sand-pressure
strength of the paper tube (i.e., the strength withstanding the
pressure in making a sand mold).
[0049] After completion of lap-winding all the plies, the tubing is
dried by heating at a prescribed temperature and cut to length to
complete the production of a part for casting.
[0050] The part for casting of the present embodiment is excellent
in that the amount of combustion gas it generates during casting is
reduced because of its reduced organic fiber content, and yet it
retains good formation.
[0051] The part 10 for casting of the present embodiment generates
not more than 250 l/m.sup.2, preferably not more than 150
l/m.sup.2, of combustion gas at 1000.degree. C., wherein "m.sup.2"
is the unit of the surface area of the part 10 at an average
diameter. The term "average diameter" as used herein denotes a
diameter calculated by (inner diameter+outer diameter)/2. The
amount of combustion gas generated is preferably as small as
possible. The practically reachable lower limit is 1 to 10
l/m.sup.2. The amount of combustion gas generated at 1000.degree.
C. is measured using equipment for measuring the amount of
generated combustion gas (No. 682 Gas Pressure Tester from Harry W.
Dietert Co.).
[0052] As understood from the above description, the amount of
combustion gas generated from base paper is given in cubic
centimeter per gram, while that from a part for casting is in liter
per square meter. This is because a part having a smaller inner
diameter is more liable to cause blowback (back-flow of molten
metal) than a part having a larger inner diameter with the base
paper making them being equal, i.e., with the amount of gas
generation given in cc/g being equal. That is, the amount given in
cc/g is not enough to evaluate proneness to blowback. The reason a
part with a smaller inner diameter is more prone to cause a
blowback is that the volume of molten metal present in a tubular
part is relatively smaller and therefore relatively lighter to be
blown up than in a larger-diameter tubular part.
[0053] In addition to the above, being light-weight and easy to cut
to length with a convenient device, the part for casting according
to the present invention enjoys the same advantage of ease of
handling as of this type of conventional parts.
[0054] The present invention is not limited to the foregoing
embodiments, and various changes and modifications can be made
therein without departing from the spirit and scope thereof.
[0055] For example, while in the foregoing embodiments the part for
casting is composed of two tubular paper plies, it may be composed
of three or more tubular paper plies. The ply structure is selected
as appropriate to required sand-pressure strength, required
high-temperature strength, the thickness of base paper, and so
forth. The term "high-temperature strength" as used herein refers
to mechanical strength of a part on contact with molten metal.
[0056] While in the foregoing embodiments the part for casting is
formed of base paper previously prepared by a papermaking
technique, it is possible to make the part by a conventionally
known pulp molding technique using the same raw material slurry as
described.
EXAMPLES
[0057] The present invention will now be illustrated in greater
detail with reference to Examples, but it should be understood that
the invention is not limited thereto. Unless otherwise noted, all
the percents are by mass.
Example 1
[0058] A sample sheet for evaluation was prepared using the
following raw materials of base paper for tubular paper plies. The
resulting sheet of base paper was evaluated for formation (waviness
and disperse state of inorganic powder, etc.), surface roughness,
and generation of combustion gas in accordance with the methods
described below. The results obtained are shown in Table 1.
TABLE-US-00001 Composition of base paper for tubular paper plies
(sample for evaluation) (1) Inorganic powder: obsidian powder 65.5%
by mass (average particle size: 30 .mu.m) (2) Inorganic fiber:
carbon fiber (length: 3 mm; 4% by mass Torayca chopped fiber,
available from Toray Industries, Inc.) (3) Organic fiber: used
paper 12% by mass (4) Thermosetting resin: resol phenol resin 18%
by mass (Bellpearl S-890 from Air Water Bellpearl Inc.) (5)
Papermaking binder: KAIMEN 0.25% by mass (6) Papermaking binder:
CMC 0.25% by mass (7) Water repellant not added Total of (1) to
(7): 100% by mass (8) Dispersant: sodium
.beta.-naphthalenesulfonate- 0.5% by mass formalin condensate
(Demol N from Kao Corp.)
[0059] The dispersant (8) was added in an amount of 0.5% by mass
based on the total (100% by mass) of the components (1) to (7).
[0060] In a 2-liter juicer-mixer were put 100 g, in total, of the
components (1) to (7) and 0.5 g of the dispersant (8) in accordance
with the composition above, together with 1.9 liters of water and
agitated for 3 minutes to prepare a stock slurry. The stock slurry
was poured into a papermaking tester (size of paper made: 250 mm
(W).times.250 mm (L); wire: 40 mesh; capacity: 15 liters) together
with 13-liter of diluted water, stirred, and allowed to stand for 1
minute. White water was drained through the wire to form a wet
fiber mat, which was pressed under 0.1 MPa and dried in a dryer at
105.degree. C. for 30 minutes to obtain a sample sheet of base
paper.
(a) Evaluation of Waviness
[0061] The waviness on the top side (opposite to the wire side) of
the sample paper was evaluated by scoring from 1 to 5 based on the
number of projections of 1 mm or 15 more in height counted on that
side.
[0062] Scoring system:
[0063] 0: 50 or more projections
[0064] 1: 40 to 49 projections
[0065] 2: 30 to 39 projections
[0066] 3: 20 to 29 projections
[0067] 4: 10 to 19 projections
[0068] 5: 9 or less projections
(b) Disperse State of Inorganic Fibers
[0069] The disperse state of inorganic fibers was evaluated by
scoring from 1 to 5 based on the number of flocks of inorganic
fibers appearing on the back side (wire side) of sample paper.
[0070] 0: 50 or more flocks of carbon fibers
[0071] 1: 40 to 49 flocks of carbon fibers
[0072] 2: 30 to 39 flocks of carbon fibers
[0073] 3: 20 to 29 flocks of carbon fibers
[0074] 4: 10 to 19 flocks of carbon fibers
[0075] 5: 9 or less flocks of carbon fibers
(c) Disperse State of Inorganic Powder and Thermosetting Resin
[0076] The area ratio of flocks of the inorganic powder and the
thermosetting resin was measured on the back side (wire side) of
the sample paper and scored for evaluation. When these components
are poorly dispersed, they gather on the wire side of paper.
[0077] 0: the area ratio of the inorganic powder and thermosetting
resin flocks is 80% to 100%.
[0078] 1: the area ratio of the inorganic powder and thermosetting
resin flocks is 60% to 79%.
[0079] 2: the area ratio of the inorganic powder and thermosetting
resin flocks is 40% to 59%.
[0080] 3: the area ratio of the inorganic powder and thermosetting
resin flocks is 20% to 39%.
[0081] 4: the area ratio of the inorganic powder and thermosetting
resin flocks is 10% to 19%.
[0082] 5: the area ratio of the inorganic powder and thermosetting
resin flocks is 9% or less.
[0083] Flocks of the inorganic powder are recognizable with the
naked eye as flocks of whitish powder. Flocks of the thermosetting
resin are recognizable with the naked eye as flocks of yellow
powder.
(d) Evaluation of Formation
[0084] The formation was evaluated by the sum of the scores
obtained in the evaluations (a) to (c). A higher score means better
formation, and a lower score means poor formation.
(e) Evaluation of Surface Roughness
[0085] The surface roughness Ra was measured with Surtronic 10 from
Rank Taylor Hobson in accordance with the operation manual.
(f) Evaluation of Combustion Gas Generation
[0086] The amount of combustion gas generated was measured using an
instrument for measuring the amount of generated combustion gas
(No. 682 Gas Pressure Tester from Harry W. Dietert Co.) as follows.
The furnace inner temperature was set at 1000.degree. C. One-tenth
gram (nominal mass) of the sample was weighed out with precision of
milligram and placed on the mount of the instrument, and the amount
of combustion gas generated was measured in accordance with the
instruction manual. The amount of combustion gas generated was
calculated as programmed based on the integration of the rate of
combustion gas generation. Calculation was made based on the amount
of combustion gas after an elapse of 30 seconds. The rate of
combustion gas generation and the amount of combustion gas
generated were analyzed on Chromato Pack C-R4A from Shimadz
Corp.
Example 2
[0087] A sample sheet of base paper was prepared in the same manner
as in Example 1, except for replacing the dispersant of Example 1
with the one described below. The resulting paper was evaluated in
the same manner as in Example 1. The results obtained are shown in
Table 1.
Dispersant: hydroxypropyl cellulose (Klucel H from Hercules). This
dispersant, being sparingly soluble, was preliminarily diluted with
water to a 1% concentration and then added to a 0.5% by mass on a
solid basis.
Comparative Example 1
[0088] A sample sheet of base paper was prepared in the same manner
as in Example 1, except for using no dispersant, and a part for
casting was formed of the resulting base paper in the same manner
as in Example 1. The resulting paper was evaluated in the same
manner as in Example 1. The results obtained are shown in Table
1.
Comparative Example 2
[0089] A sample sheet of base paper was prepared in the same manner
as in Example 1, except for using the following raw materials of
base paper for tubular paper plies. In Comparative Example 2, the
amount of the organic fiber was doubled, and any dispersant was not
added.
TABLE-US-00002 Composition of base paper for tubular paper plies
(sample for evaluation) (1) Inorganic powder: obsidian powder 48%
by mass (average particle size: 30 .mu.m) (2) Inorganic fiber:
carbon fiber (length: 3 mm; 9.5% by mass Torayca chopped fiber,
available from Toray Industries, Inc.) (3) Organic fiber: used
paper 24% by mass (4) Thermosetting resin: resol phenol resin 18%
by mass (Bellpearl S-890 from Air Water Bellpearl Inc.) (5)
Papermaking binder: KAIMEN 0.25% by mass (6) Papermaking binder:
CMC 0.25% by mass (7) Water repellant not added (8) Dispersant not
added Total of (1) to (8): 100% by mass
TABLE-US-00003 TABLE 1 Formation Dispersed State Surface Combustion
Inorganic Inorganic Thermosetting Overall Roughness Gas from
Waviness Powder Fiber Resin Judgement Ra (.mu.m) Paper (cc/g)
Example 1 4 4 4 5 17 4.2 190 Example 2 5 5 4 5 19 9.5 198 Comp.
Example 1 1 2 2 2 7 23.8 202 Comp. Example 2 5 4 5 5 19 8.0 268
[0090] As is apparent from Table 1, the base paper obtained in each
Example was proved better in formation and surface roughness and to
generate a reduced amount of combustion gas as compared with that
of Comparative Example 1. In Comparative Example 2, base paper with
good formation and surface roughness was obtained owing to the use
of double the amount of organic fibers used in Example 1 but, in
turn, produced an increased amount of combustion gas.
Example 3
[0091] A two-ply tubular part for casting (paper tube) as
illustrated in FIG. 1 was formed of base paper having the following
composition. The resulting part was evaluated for combustion gas
generation and blowback in accordance with the method described
below. The results obtained are shown in Table 2.
TABLE-US-00004 Composition of base paper for paper tube (1)
Inorganic powder: obsidian 57.3% by mass (Nice Catch Flower # 330
from Kinsei Matec Co., Ltd.) (2) Inorganic fiber: carbon fiber
(Pyrofil TR03CM 7.2% by mass from Mitsubishi Chemical Industries,
Co., Ltd.) (3) Organic fiber: recycled paper 11.5% by mass (4)
Thermosetting resin: resol phenol resin 17.5% by mass (Bellpearl
S-890 from Air Water Bellpearl Inc.) (5) Papermaking binder: KAIMEN
3.0% by mass (6) Papermaking binder: CMC 3.0% by mass (7) Water
repellant: alkyl ketene dimer 0.5% by mass Total of (1) to (7):
100% by mass (8) Dispersant: sodium .beta.-naphthalenesulfonate-
0.5% by mass formalin condensate (Demol N from Kao Corp.) The
dispersant (8) was added in an amount of 0.5% by mass based on the
total (100% by mass) of the components (1) to (7).
[0092] In a 2-liter juicer-mixer were put 100 g, in total, of the
components (1) to (7) and 0.5 g of the dispersant (8) in accordance
with the composition above together with 1.9 liters of water and
agitated for 3 minutes to prepare a stock slurry. The stock slurry
was poured into a papermaking tester (size of paper made: 250 mm
(W).times.250 mm (L); wire: 40 mesh; capacity: 15 liters) together
with 13-liter of diluted water, stirred, and allowed to stand for 1
minute. White water was drained through the wire to form a wet
fiber mat, which was pressed under 0.1 MPa and dried in a dryer at
105.degree. C. for 30 minutes to obtain a sample sheet of base
paper.
Form of Part for Casting:
[0093] The base paper for tubing (thickness; 0.7 mm) was slit into
strips having widths of 80 mm and 82 mm. The 80 mm wide strip was
spirally lap-wound onto a mandrel having an outer diameter of 50 mm
as a first ply. The 82 mm wide strip was spirally lap-wound on the
first ply while applying an adhesive to the 82 mm wide strip in a
manner as to cover the exposed edge of the 80 mm strip to make a
paper tube as a part for casting shown in FIG. 1.
Adhesive: phenol resin emulsion (PR-51464 from Sumitomo Bakelite
Co., Ltd.) Total thickness: 1.4 mm Inner diameter: 50 mm
(a) Evaluation of Combustion Gas Generation
[0094] The amount of combustion gas generated was measured using an
instrument for measuring the amount of generated combustion gas
(No. 682 Gas Pressure Tester from Harry W. Dietert Co.) as follows.
The furnace inner temperature was set at 1000.degree. C. One-tenth
(0.1) gram (nominal mass) of the sample was weighed out with
precision of milligram and placed on the mount of the instrument,
and the amount of combustion gas generated was measured in
accordance with the instruction manual. The amount of combustion
gas generated was calculated as programmed based on the integration
of the rate of combustion gas generation. Calculation was made
based on the amount of combustion gas after an elapse of 30
seconds. The rate of combustion gas generation and the amount of
combustion gas generated were analyzed on Chromato Pack C-R4A from
Shimadz Corp.
(b) Evaluation of Blowback
[0095] A casting mold 1 illustrated in FIG. 2 was made by burying
paper tubes 2 to 4 measuring 50 cm, 30 cm, and 5 cm in length,
respectively, all having an inner diameter of 50 mm, connected with
pottery elbows, in the hatched portion of cured sand (molding sand)
containing a furan resin. Two hundred fifty kilograms of molten
metal at 1400.degree. C. was poured in the mold through the pour
spout 5, and a blowback from the pour spout was observed with the
naked eye and rated as follows.
[0096] good: a slight flame generated
[0097] bad: an about one-meter column of flame generated
Comparative Example 3
[0098] A two-ply tubular part for casting (paper tube) was made in
the same manner as in Example 3, except that base paper was
prepared using the following composition (the amount of the organic
fibers was doubled, and any dispersant was not used). The resulting
part for casting was evaluated in the same manner as in Example 3.
The results are shown in Table 2.
TABLE-US-00005 Composition of base paper for paper tube (1)
Inorganic powder: mullite 47.6% by mass (Mullite MM#200 from MC
Kosan K.K.) (2) Inorganic fiber: carbon fiber 4.2% by mass (Pyrofil
TR03CM from Mitsubishi Chemical Industries, Co., Ltd.) (3) Organic
fiber: recycled paper 25.0% by mass (4) Thermosetting resin: resol
phenol resin 16.7% by mass (Bellpearl S-890 from Air Water
Bellpearl Inc.) (5) Papermaking binder: KAIMEN 3.0% by mass (6)
Papermaking binder: CMC 3.0% by mass (7) Water repellant: alkyl
ketene dimer 0.5% by mass Total of (1) to (7): 100% by mass
TABLE-US-00006 TABLE 2 Combustion Gas Combustion Gas from Part for
from Paper (cc/g) Casting (l/m.sup.2) Blowback Example 3 230 225.0
good Comparative 260 315.8 bad Example 3
[0099] As can be seen from Table 2, the parts for casting obtained
in Example show a reduction of combustion gas generation and
prevent a blowback.
INDUSTRIAL APPLICABILITY
[0100] The present invention provides a part for casting which has
a reduced content of organic fibers while retaining excellent
formation so as to reduce generation of combustion gas during
casting. The invention also provides a process for advantageously
making a part for casting having the above effects.
[0101] The present invention is applicable to various casting mold
parts constituting a casting mold, such as a pouring cup, a runner,
a gate, a gas vent, a feeder, and a mold cavity, and production of
such parts.
* * * * *