Note: Descriptions are shown in the official language in which they were submitted.
` 1~48699
~ his invention relates to a method of manufacturing
a polyisocyanate foam having isotropic cells which has physical
properties homogeneous in all the directions irrespective of
foaming direction and good diMensional stability a~ an appropriate
apparatus for carrying it into effect. Moreover this invention
relates to a foam product having a homogeneous physical propertieq.
` There have heretofore been Icno~n1 and been put into
practice various many arts on a method for shaping a polyurethane
foam and an apparatus thereof, accordin`g to which the thus shaped
~0 foam has usually elliptic cells having a long diameter in the
foaming direction, as known well. It is also well known that
different physical properties of a polyurethane foam varying
dependent upon foaming direction are ascribable to the cell
structure.
~ ecause of this, various investigations have been
conducted concerning alteration of such cellular structure, namely
a method and apparatus for shaping a polyurethane foam to be
isotropic cell structure, and for example, USP 3,249,486 and -
Japanese Patent Publication 28,781/1973 are proposed as such.
However, according to those methods above in which a moulding
container for a foam is provided with a lid on it or a flat plate
for pressing the top face of a foam is placed, whereby the foam
is extended also in a side wall direction of the container by
compulsory pressing of the top portion of the foam and thus,
isotropic cells are formed, a foaming pressure imposed upon the
entire moulding container is naturally great, so that problems
to be overcome in respect of construction of a moulding container
in respect of construction of a moulding container and of mold
releasing persisted.
In view of the above, the present invention prov~des
a novel method of manufacturing polyisocyanate foam ha~ing an
isotropic cell structure, in
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which the foam i5 obtained with a simple and light weight
molding container and in a shortened mold~releasing time.
This method comprises the steps of placing a charge
of a liquid polyisocyanate foamable composition into a mould
cavity, allowing the composition to rise freely in one direction
Z in the mould cavity by expansion during foaming and, while the
composition is still fluid and rising, positively extending
the size of the mould cavity in two mutually perpendicular
directions X and Y perpendicular to said direction Z of free
rising of the composition, to an equal extent in the two direc-
tions X and Y and in rQsponse to the rising height and/or to the
foaming rate of the composition in said free rising direction,
so as to permit the composition to expand in said three direc-
tions X, Y and Z to form an isotropic cell structure.
The present invention is also concerned with the
polyisocyanate foam obtained by the method according to the
invention, which foam is characterized by having substantially
isotropic cells and physical properties; an apparent density
of 0.025 - 0.015 g/cm , and a dimensional change index in every
direction referred to ASTM D-2126 of within 5% at 70C, 95RH after
48 hrs. and that of within 1.5% at -20 C after 48 hrs.
Accordingly, the first aspect of this invention resides
in the production of a foam having homogeneous physical properties.
The second aspect of this invention resides in the foam per se.
A third aspect of this invention resides in the
construction of an apparatus for carrying out the method
according to the invention.
Polyisocyanate foam as used in this specification
means polyurethane foam, polyisocyanurate foam, polycarobodiimide
foam etc. including isocyanate group as starting material of foam
product. However, the present invention will only b~ explained
with reference to the polyurethane foam, as below.
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The manufacturing process will be explained below
wherein polyurethane foam having isotropic cells is obtained by
positively spreading out the mould in X and Y directions.
In general, a polyurethane foam irrespec:tive of rigid
or semirigid is produced as follows: after a foaming composition
is mixed and stirred, it commences to foam in a creamy state in a
few seconds to a few minutes; the composition is gradually
increased in viscosity to be a so-called tack-free state in which
even if a hand is touched on the foam surface the foam .s no more
sticky in a few minutes to several tens of minutes; and thereafter,
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the fca~ing process is completed in a further few seconds to a
few minutes. Here, the cell form of a foam is determi~ed during
a period of time when the foam becomes from a creamy state to a
taclc-free state, but it is almost not influenced during a period
of time when the foa~ becomes from a tack-free state to a completea
product since the foam volume is increased only in a few per cent~.
For this reason, it is essential in this invention to
alter the cell form of a foam during a period of time when a foaminO
composition has fluidity before it becomes tack-free, for the
pu~l)ose of which the cells of a foam are modified so that a pressure
~ay not be almost exerted upon around a foaming foam while the
four sides X and Y directions of a moulding container are made free.
~hus, since the upper part o the moulding container is opened and
the foam has fluid~ty as mentioned above, the foaming pressure of
the foam during this time is very low and is of only a self-weight
of the foaming composition, with the result that it is possible to
obtain easily a polyurethane foam comprised of isotropic cells
while making the four sides of the mould nearly free with a simple
~ig. :-
The foam having isotropic cells thus obtained according
to this invention has an appearance nearly similar to the prior
art foams, but superior physical properties to them and can be
manui`actured in a very short time, which fact leads to enhancement
of productivity. It is noteworthy that the foam obtained in this
invention has a good dimensional stability and accordingly, it
is possible to lower greatly specific gravity of the foam in
response to object for use. Consequently, great reduction of
cost can be expected owing to the reduction in specific gravity,
coupied with shortening in time of mould releasing.
In this invention, the idea of making the cells of a
foam nearly completely isotropic form is based on the ground that
foaming process, namely foam rising is carried out in the lateral
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direction as well as in the longitudinal direction, with the rat o
of both the foaming directions being appropriately regulated, and
an effective means for it is thus proposed.
The invention will be further described in greater
detail by way of example with reference to the accompanying
drawings in which: -
Fig. 1 shows the sectional view of the free rising
direction in conventional foam;
Fig. 2 shows the sectional view of the free rising
direction of the foam in the present invention;
Fig. 3 is a perspective view showing schema of an outer
mould of a foaming container in one example of this invention;
Fig. 4 and Fig. 5 are a perspective view showing portions
of an inner mould, the essential part of this invention in which
Fig. 4 is an inner mould and Fig. 5 is a bottom plate;
Fig. 6 is a perspective view of an inner mould after -
foaming is completed and ~ig. 7 is a perspective view showing a
situtation of an inner mould before a foaming composition is
poured therein;
Fig. 8 is a plan view showing a situation that an inner
mould is unopened or contracted and put in an outer mould;
Fig. ~ is a fragmentar~ sectional view showing a situa-
tion when an inner mould and an outer mould are fitted just before
a foaming composition is poured; and
Fig. 10, Fig. 11 and Fig. 12 are views showing process
steps of manufacturing a foam according to this invention in that
order.
Fig. 13 and ~ig. 14 are perspective view of the mould
used in the present invention and which show the other examples.
~ig. 15 is an outlined plan of the mou].d used in the
present invention and which shows the other example. ~
In the preferred embodiments of this invention a~ herein~ -
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a~ter described, a double mould in which outside the essenti.al
moulcl of this invention an outer ~lould i5 used will be sho~m.
Howe~er, in this invention, the outer mould need not be necessarily
used bu-t is inessential. It goes without saying that use o an
outer mould is included in a scope of thls invention.
As shown in Fig. 1, the profile of the conventional ce'l
is an ellipse with ~ajo- axis in Z direction due to the insufficient
expansion in X and Y directions compared to that in ~ direction.
~i~. 2 shows the profile of isotropic cell of the foam manufactured
in accordance with the present invention wherein the expansion in
X and Y directions are the same level as in Z direction.
Now, referring to Fig. 3, one example of an outer mould
(A) is shown, whereas in Fig. 4 one example of a mould (B) essential
in this invention (hereinafter designated to as an inner mould)
is illustrated in which Fig. 4 and Fig. 5 are a side wall (3) and
a bottom plate (4), respectively.
` ~he outer mould (A) is so formed that side plates (1)
can be opened outwards, for exa~ple in the arrow direction of
the figure, and inside the outer mould is provided a roller
conveyor (2) for making possible to readily put and remove the
inner mould (~) hereinafter disclosed.
On the other hand, the inner mould (~) is co~posed of
a main body having side walls (3) capable of being folded and
retrenched as shown in Fig. 4 and a bottom plate (4) having a
spacer (5) projected thereon which conforms to the bottom opening
when the main body was folded and contracted, that is to say it
became a state of Fig. 7 lest a foaming composition should not
leak therethrough. In one example of construction that the main
body is folded and contracted, pieces of the side wall are
~0 mutually fixed with hinges (7) as shown in Fig. 6.
~ he reference nu~ber (8) shown in Fig. 6 is ~etal
fittings capable of disjointing the side walls (3) of the inner
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m~ d (~) in order to re~ove them from a foam produced after finls:n
of the foaming process.
~ hen the inner mould (B) thus constructed is put in
the outer mould (~), the former is folded and contracted in such
a state as shown in ~ig. 7. ~his situation that the inner mould
is put in the outer mould is sho~m in ~ig. 8, in which in the
center part is formed a space a for injecting and holding a foaming
composition therein and in the periphery thereof is formed a space
b having a distance marked in the arrow of the figure and necessary
to make the foam cells isotropic. In this connection, it is
preferred and suitable that the central space a has an area of
about 1/3 to 1/4 of the area of the space shoYn in ~ig. 6 from
the viewpoint of formation of isotropic cells and of opening and
contracting operation of the inner mould (B).
~ ig. 9 shows a construction of apparatus for carrying
out foaming operation by the use of both the outer mould (A) and
the inner mould (B) hereinabove described. Here, a cushoning
material (9) having a thickness of ca. 5 to 10 mm is preliminarily
sticked on the bottom plate (4), on which the spacer (5) is mounted
and a mould-releasing paper (10) is further covered on the side
walls (3) and the bottom plate (4) for the convenience of repeated
use of the inner mould (B).
A suitable material which may be employed as the side
wall (3) or the bottom plate (4) includes for ex~mple, a pl~Yood
of a thickness of ca. 15 mm and a metal plate of the s~me strength.
~he tickness of the spacer (5) will suffice to be in the neighbor- -
hood of 5 mm.
Besides, as shown in ~ig. 9, a holding plate (12') is
pro~ided in contact with the outside of the side walls (3) of the
inner mould (B) and Joined to a mould extending means (12) ~hich
is operated to inform the timing for spreading out and shifting
the inner mould (B) in the opening direction.
.
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~ he mould extending means (12) is fixed picrcing through
a side piece of the outer mould (A) in the iigure, but the outer
mould (A) may be only a side frame capable of supporting the means.
~he means may be used in oil pressure system or screw system.
Operation of the mould extending means (12) is connected to a
height detecting means (11) of contact-detecting type like limit
switch, for detecting the height of the foam surface which is
disposed in a specified position above the pouring space a, and
by the operation of it the side walls (3) are opened and unfolded
out~ards, namely in X and Y directions.
It i9 preferred that the detecting means (11) is so
constructed that it is interlocked with the mould extending means
(12) and operates automatically to spread the inner mould (B) out
and that it can be pivoted or moved up and down so as to be removed
immediately after the foam hardened.
The method of this invention is carried into effect
by the use of the outer mould (A) and the inne~ mould (~) thus
constructed. ~he invention will be hereinafter disclosed more
concretely concerning manufacturing process of a polyurethane
foam having isotropic cells.
First of all, as shown in ~ig. 10, a foaming composition
for polyurethane in an amount sufficient to fill a space of the
final volume as shown in ~ig. 12 is mixed, agitated and poured
into the space a. Soon after a few seconds to a few minutes,
the composition thus mixed commences to foam in a creamy state.
A foam comes to expand up to the height of the detecting means
(i1) such as a limit switch which is located above the space a.
~his step so far is not particularly different from the conventional
procèss of manufacturing a foam and the cells being thus formed
are eiliptical, with the liquid composition having still fluidity.
~en the foam expanded up to the height of the detecting means
(11), as shown in Fig. 11, the mould extending means (12) slide
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outwards, in response to which the side ~alls (3) of the irmer
mould (~) go to open arld unfold in the X and Y directions
gradually while ascertaining the height of the foam by the
detecting means (11) and retaining it homogeneous, whereby the
previous foaming in Z direction is changed to the foaming in X
and Y directions as mar~ed in the arrow and at the same time,
the cells of the foam begin to be formed isotropic.
~ }le foaming in X and Y directions continues to proceed
till the side walls (3) become the state of ~ig. 6 (cf. ~ig. 12).
~hus, when the foam beca~e a state that foa~ing no more occurs
~udging by appearances with the naked eye, it is released from the
mould as a~ finished product.
~ ~hus, according to this invention, the foam product
can be obtained that is composed of nearly isotropic cells and
has homogeneous physical properties in all the directions because
the subsequent foaming in X and Y directions takes place by auto- -
matic actuation of the mould extending means interlocked to the
height detecting means. ~urthermore, mould-releasing time of the
foam can be exceedingly shortened since the foaming pressure is
difficult to be exerted upon the foam itself at the side face. In
this con~ection, the conventional foam was cracked when released -
from mould owing to an inner stress occured in the side foam if it
had not been kept to stand in a moulding container for 20 to 60
minutes at room temperature after finishing of the foaming process.
In contrast, according to this invention, even if mould-releasing
is conducted in one or two minutes after foaming was finished,
the foam thus obtained is not cracked Accordingly, it is
advantageous in this invention that number of the foaming container
to be required may be less than 1/10 in comparison with container
number of the conventional methods.
hs a mould in the apparatus in this invention other
moulds than those described so far and sho~n in ~ig. 4 and ~ig. 8
1¢3 4~99
~ay be available, for example, the mould having bellow side wall
(refer to Fig. 13 and Fig. 14) or one with four foldable corners
(refer to Fig. 15). In such cases, mould extending means are
preferably secured to the four corners and the process comprises
pouring the foaming composition into the mould when it i9
shrinked indicated by line (21) and (23) and then spreading out
the mould to the desired position (shown by line (22) and (24))in
X and Y directions in response to the operation of height detecting
means (11) (not sho~m on the Fig.) in Z direction; thereby poly-
urethane foam having isotropic cells can be obtained.
~ he present invention will be further illustrated by
the following non-limitative examples.
Example 1
Five kinds of compositions ("A" solution) were prepared
as in the following table:
Ingredient 1 2 3 4 5
Polyether (sucrose
delivertive: OH 60 60 60 60 60
value of 450)
Polyether (sucrose
delivertive: OH 40 40 40 40 4o
value of 550)
. .. .
Surface Active Agent
(silicone) 2 2 2 2 2
, . . . . .. _ _
Amine Catalyst 0.4 0-.4 0.5 0.7 1.0
. . _.
Foaming Agent
(Freon 11)~ 41 41 4~ 54 60
. _
~otal 143.4 143.4 150.5156.7 163
lhen, to the respective "A"solution above is added 130
parts of prepolymer (sucrose polyether isocyanate), and the
respective mixture is stirred. Five kinds of polyurethane foams
were thus produced having different specific gravities.
trademark
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` ` 1~48699
~ he comparative test results of physical properties on
them are shown in Table 1 given below. In the table, No. 1 is a
polyurethane foam manufactured by the conventional art whereas
No. 2 to No. 5 are polyurethane foams manufactured according to
this invention. Size of the sample foam is 500 x 1000 x 2000 mm
Table 1
~o. Specific Direction !Compressiv~ _ Dimensional Change %
Gravityof Measure- Streng~h100~C 70C I -20C
of the ment (Kg/cm )48 hr. 95~ RH 48 hr
Foam Core . 48 hr.
(g/cm3)
1 0,0291 L 0.88 +2.44 +4.63 _0,30
// 2.13 -1.20 -1.09 -0.45
. ,, ,
2 0.0284 l 1.38 +0.~4 +2.49 -0.29
// 1,42 +0.50 +1.23 -0.30
3 0.0270 l 1.29 +0.7~ +2.70 -0.23
/t 1.35 -tO.83 +2.00 -0.23
~ '.
4 0.0250 1 1.10 +0.96 +3.55 -0.10
// 1.15 +0.96 +2.30 _0.12
_
0.0214 L 0.80 ~1.61 +4.67 -1.50
_ // 0.85 ~1.32 +3.40 -1.10 I ~:
Remark : Direction l : horizontal direction in Fig. 10 - 12
Directionll : up-and down direction in Fig. 10 - 12
Example 2
First, a composition solution was prepared in the
following formula:
Polyether (aromatic series : OH value of 380) 30 parts
Polyether (sucrose series : OH value of 450) 70 "
Surface Active Agent (silicone) 1 "
Amine Catalyst 1 "
Water 3
Foamin~ A~ent (Freon 11) 175
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1~48699
Thereafter, to the compo~ition solution above was mixed
and stirred 162 parts of prepolymer (sucrose-polyether isocyanate)
to produce polyurethane foams both accordin~ to conventional
method and the method of the invention. Comparison between both
the polyurethane foams in physical properties was made and the
results are sho~m in the following table:
Table 2
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Physical Properties Conventional Art This inve~ion
~pecific Gravity of
the Foam Core 0,0170 0.0163
(g/cm3)
Compressive 1
Strength 0.23 0.63
(kg/cm3) . Il O . 80 0.63
Dimensional -20C 1 -40.2 ~0.6
48 hr. Il -~.0 -0.6
70c 1 -2.0 +1.3
Change (~o) 95~oRH ~5.2 -0.7
. .
100C 1 ~3.5 ~0.8
4~ hr. ~' -2.1 -0.7
_ ~ ~ .
Water ab~orption 6.48 5.0
(vol. ~o)
. _
Content of closed cens 76.3 _ .
rhermal Conductivity 0~0216 0.0190
(Kcal/mhrC)
Remark : The directions 1 and ll are the same as in Example,l.
A9 will be seen from the tables below, the polyurethane
foams obtained in accordance with this invention have superior
physical properties almost equal both in the Z direction and in
the X and Y directions to those of the conventionally manufactured
foams~ that is to say it can be understood that the polyurethane
16)48~99
foa~ having i~otrnp c cell3 were obtained in thi~ inven-uion
~ he exa~lples ~o far show the methods of manufacturin~
polyurethalle foam having isotropic cells by ~preading out the
mould in X and Y directions in response to the detecting means
tvhich operates only when the foam rises to the specified
height.in Z direction.
As mentloned above, the present invention compr ses
spreading out the mould positively in X and Y directions in
responsQ to the free rising height in Z dircction without recourse
to the foaming pressure as in prior arts. In view of the
philosophy of the present in~ention theObieCt can also be
attained by positively operate the mould extending means in
response to the foaming speed of foaming compo~ition. Thus it
is a matter of course that the present invention comprises the
modified examples as follows~
For an-~example, the mould extending means can be started to operate ~`~
in response to the operation of the rising height detecting means
which starts simultaneously with or slightly a~ter-the begi-nning
of expansion,
In this case, the detecting means, unlike the case
before mentioned, rises as the foam expands in Z direction up to
the predetermined heigth with mould extending mean3 operating in
response to it. After it reaches the predetermined height in Z
direction, it stops rising. It i8 possible to make mould
extending means (12) continue to operate during the period of
time when said height detecting means (11) is in contact with
the foam sur~ace.
It may also be pO9 ~ible to make it a condition that the side ~a?l
(3) of the mould is ~lightly bended inwards rather than completely
opened at the finishing point of expansion as shoYrn in Fig 6,
Furthermore, the mould extending mean~ can be independent-
ly operated after the expansion begin~ under the condition pre-
determined on the basis of preliminary -trial~ in response to
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the rising height in Z direction and all of which can even be
operated by programme restraint system, if desired. Although
this method i9 inferior in accuracy to that mentioned before
wherein the mould extending means operates by detecting directly
the rising height in Z dlrection. It's possible to obtain the
desired cell structure by proper control of the ambient
temperature, humidity and quality of foaming compo~ tion.
~ he foam manufactured in accord~nce with the present
invention i~ of low density and has improved physical property,
especially high dimensional stability. Consequently the resultant
~oam is suitable for insulating material and yet the insulating
exedution can be done economicaily. In sddition 'o that, the
foam can take any form as in~ulating material such as plate, cube
and circular arc-profiled form etc. and some other ~urface
material can be laminated onto at leasts one surface of the foam
such as paper, plastic sheet, ply~ood, asbestos, metal laminate
etc.. Consequently, finished product will find so u3eful and wide
ranged applications in the field of insulation industry.
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