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Патент USA US3095321

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United States Patent 0
LAf'llVl | wen
Patented June 25, 1963
duce a water-insoluble foamed product. This ratio is
Sidney T. Holmes, 1410 Warrington Road, Deer?eld, Ill.
No Drawing. Filed Dec. 24, 1959, Ser. Nmw
2 Claims. (Cl. 106-75)
This invention deals with the production of inexpen
the portion of total Nazo to paraformaldehyde used,
which should be less than 3 to l, and preferably less than
2 to 1. It is apparent that, when metals other than so
5 dium are used in the silicate, the ratio ?gures must be
adjusted accordingly. At the same time, the total amount
sive, essentially inorganic, foamed products formed by
expanding a mixture__i_nt9_ nah liar/d lpgrouskmass suitable
of paraformaldehyde present, by weight, in the reaction
mixture, should be less than 5% and preferably 3% or
less, such as between about 0.1% and 2%. This para
for a variety of important uses. More speci?cally, it 10 formaldehyde, in addition to promoting water-insolubility,
irelates'to'foanredmassesproduced by interaction at am
also acts to trigger the expansion of the reaction mixture
bient temperatures of water-soluble inorgaic il' 4
in certain cases, as well as to accelerate the foaming rate.
' general]
The fourth in
‘m, which, though not necessary
presence 0
ow - -- inorgam
ers, and
ound suit—
abte 'i’6rT1se“'as"f6ai?Ed1iiiIpT5€eTi'?§u'iation and in other 15 insoluble pro ucts, wk; preferably an inorganic and ~
valuable outlets.
.generally an inert refrac
"material such as alumina,
In the case of thermal insulation, for example, indus
magnesia, Wm, ?reclay, graphite
trial usage thereof for many years has been limited be
or__coml5ination_thereof. ltis usually employed in pow- 9
cause of the di?iculty of shaping the commercially avail
dered form, preferably as a ?our of 200 mesh or ?ner, in
able solid materials to ?t the speci?c needs involved. 20 amounts of about 0.1% by weight up to 20%, 30%, 40%
Until recently, such insulation was available only in the
or 50% or more of the composition.
form of powder, sheet (?exible and rigid), and block.
The reaction of the present invention may be con
trolled to produce a water-soluble or water-insoluble solid
material to the desired form for the particular applica
foamed product, as desired. The in-situ foaming causes
tion. This led to the unfortunate results that high labor 25 an increase in volume of the mixture, following which
costs would be involved and that the efficiency of the in
a hardening of the foam occurs. Roughly, an increase
sulation would not be at its optimum due to the inherent
in volume of 3 to 1 results in forming a solidi?ed foam
di?iculty in ?tting closely the product to be insulated.
of density of about 40 lb./cu. ft., while an increase of 6
In the past few years, light-weight foamed-in-place in
to 1 results with a product density of about 18 lb./cu. ft.
sulation became available and it was received enthusiasti 30
The reaction mixture to rodu
ater-soluble hard
Accordingly, it was necessary to fabricate (shape) the
cally by industry because of its many advantages. Un
ed foam product contains a peroxy compound, and
fortunately, these rather expensive foamed products have
been composed of organic materials which necessarily
limit their usage to low operating temperatures. Also,
both hquid water-soluble and powdered water-soluble .
the foaming reac
atter. ingredient,’
, they require control of the reaction composition to rather 35 '
ing takes from 10 to 24 hours with no
narrow limits, and usually heat has been necessary to gen
appreciable evolution of heat, m the ingredient
erate the gas from the “blowing” agent in the production
in amounts of from 1% to 5%, foaming takes place in
of such foamed masses. These temperature limitations
from 5 to 60 minutes, with some evolution of heat. The
and installation di?iculties under industrial conditions
t ratlo
"-71 is
- '
-. '
have emphasized the need for a simple, light-weight,
foamed-in-place product which would be resistant to heat
greater than 3 to 1 Density of the oamed product may
and would not require external heating for the foaming "' E controlled to be from 10 to 30 lb./cu. ft., depending
upon the proportions of the ingredients and the amount
According to the present invention, there is produced
an essentially inorganic foamed-in-place (or in-situ
foamed) product suitable for use at elevated tempera
tures, which is competitive price-wise even with the
archaic powder, sheet, or block type of material.
The ?rst ingredient in the c mposition of the present
of paraformaldehyde used.
- -
In the preparation of a water-soluble hardened foamed
45 product, a liquid comprising about 5 to 20 parts by weight
of a wategsg?ileiiq?dfpero
weight of anliqui‘d'wa‘t'eif-sqipyle?cate,
and is mixed
with about 10 to mam-ty'?eigm of powdered water
, which is a peroxy
soluble silicate. It is generally desirable to add about 1
50 to 5 parts by weight of paraformaldehyde to accelerate
the foaming rate. The liquid portion is mixed with the
powder, then the slurry is stirred until smooth and
creamy, and it is poured into the cavity to be ?lled. No
e second ingredient is a WWW
silicate serving (in ?nished form) as the skeletal struc
ture and
further processing is required.
(when I - M
T'n mass.
are submitted:
This ingredient is
employed inmmlggnor liquid form, as will be explained
further, and it is’the proportion of this component in
relation to the third ingredient, which determines whether 60
the resulting foam will be water-soluble or water-insolu
ble. Particularly effective, are the-alkali metal siliates;
x such as those 0
The third ingredient, w c may be omitte in certain
special cases (i.e., in water-soluble products where foam
ing time duration is unimportant), as will be explained
It appears to act in_a
catalytic mann'é'r, oth to promote insolubility and to ac
celerate the foaming reaction. In the case where sodium
silicate is used together with paraformaldehyde, there is
a critical weight ratio of concentration necessary to pro
To illustrate the e?fect of various ingredients on the
properties of the foamed product, the following examples
s the adhesive comound to bind the filler
Example Number
Sodium Silt
e (Powdered)
' 7:
- - - Powdered),pereent
- . __
e (30% Aqueous),
__________________ __
Sodium Silicate (Liquid) (“N" Brand
1.0Naz0:3.22 Si0z),percentb weight
Density of foamed product, lb. cu. ft...
Water Solubility _____________________ __
70 Radio oi NazO/Paraiorm?ldehyde .... ..
1 N o foaming.
Bran — .
az0:3.22 Bios), percent
by weight .......................... -65
1 Very soluble.
The product of Example 1 has a uniform multicellular
structure, and is readily soluble in water, resistant to
ples 7 and 8 illustrate the need for both paraformalde
hyde and peroxy compounds to cause full foaming.
The second type of water-insoluble foamed product
?ame impingement and capable of withstanding continual
exposure of at least 10 minutes to temperatures of up to
made in accordance with this invention involves use of
a reaction mixture comprising a powder mixture of
1200° F. The product of Example 2 (to which mixture
paraformaldehyde was added to accelerate the rate of
paraformaldehyde (essential to this type of foam) and
foaming) possesses the same properties except that the
an inert organic ?ller. This powder is admixed with an
structure of the material is coarse, and the product shrinks
aqueous liquid comprising a peroxy compound, also a
on solidifying. Example 3 illustrates the fact that the
liquid water-soluble inorganic silicate, and water. The
peroxy compound is essential to foam production. With 10 prepared powder mixture is combined with the aqueous
out it, the mixture does not expand upon reaction.
mixture of peroxy compound and water and the resulting
Such water-soluble solidi?ed foam products made in
paste is ?nally mixed with the liquid water-soluble sili
accordance with the present invention have a number
cate. The foamed product resulting from the reaction
of important uses, such as in making temporary molds
is water-insoluble (the ratio of Nazo to paraformalde
for plastic boat bulls, and for other similar purposes 15 hyde being less than 3 to 1), and its density can vary
wherein an empty cavity is desired upon completion of
from 20 to 50 lb./cu. ft. Foaming time may be made to
the plastic or other type of article to be made (wherein
take place in about 5 to 60 minutes after the initial mix
the solid foam is leached out with water). The low cost
ing (with slight evolution of heat) by control of the
of such foams makes them expendable.
amount of paraformaldehyde used.
There are two types of water-insoluble foams which 20
In the preparation of such water-insoluble foam, a
may be prepared in accordance with the present inven
powder comprising about 1 to 5 parts by weight of para
tion. The ?rst type involves use of a powder mixture
formaldehyde and about 20 to 50 parts by weight of an
of a peroxy compound, paraformaldehyde (which is es
inert inorganic ?ller is mixed with a liquid comprising
sential to this type of foam) and an inert inorganic ?ller,
about 5 to 15 parts by weight of liquid peroxy compound
which powder then is admixed with a liquid water
and 5 to 15 parts by weight of water, and the resulting
soluble inorganic silicate. The product produced by
paste is further mixed with about 15 to 70 parts by weight
interaction of these ingredients is a water-insoluble foam
of a liquid water-soluble silicate. The ?nal reaction slurry
(the ratio of NazO to paraformaldehyde in this case
then is poured into the cavity to be ?lled and no further
being less than 3 to 1). Densities of the solid products
processing is required.
vary from about 20 to 50 lbs./cu. ft. Su?’icient para 30
To illustrate the effects of the various ingredients on
formaldehyde is employed so that foaming occurs rapidly
the properties of the foamed product, the following ex
in about 5 to 60 minutes after the initial mixing, with
amples are submitted:
slight evoldtfé‘n'iaf'heat.
In the preparation of such water-insoluble solid foams,
a powder is mixed comprising about 5 to 30 parts by
Example Number
weight of a solid peroxy compound, about 1 to 5 parts of
paraformaldehyde, and about 20 to 50 parts by weight
of an inert inorganic ?ller. Then, this powder is mixed
Silica Flour (200+ mesh), percent by
_________________________________ __
with about 15 to 75 parts by weight of a liquid, water
(Powdered), percent by
soluble inorganic silicate. This reaction mixture is stirred 40 Parafoil'lmaldehyde
eig t ................................. ..
until it is smooth and creamy, and it is then poured into
. lg
the cavity to be ?lled.
Water, percent by weight
No further processing is required.
To illustrate the e?ects of various ingredients on the
properties of the foamed product, the following examples 45
are submitted:
Sodium Silicate (Liquid), (9% N810),
“N"Brand 1.0 NaiO:3.22 sioa), Percent
by weight
Density of Foamed Product, lb./cu it
Water Solubility _______________ _.
Ratio of N rim/paraformaldehyde ......... __
1 Little foam.
Example Number
Silica Flour (200+ mesh), per
cent by weight ............ __
dered), percent by weight-"
dered), percent by weight-..
‘ (Liquid)
(“N" Brand 1.0 NazO:3.22
SiOr)I percent by we1gbt._..
Density of Foamed Product,
1 N o foam.
The product obtained from Example 9 has a uniform
50 multicellular structure. It is insoluble in water, is resist
ant to ?ame impingement and is capable of withstanding
continual exposure of at least 16 hour to temperatures
of up to 1400° F. Examples 10 and 11 illustrate the
interdependence of paraformaldehyde and peroxy com
55 pound to promote full foaming. Example 12 shows the
need for solid ?ller to be utilized in order to form a rigid
fully foamed product.
All of the aforesaid three types of foamed products
(one soluble and the two insoluble) are readily repair
None Soluble Slight
60 able or “weldable” by addition of foam slurry (e.g., the
Ratio of NmO/Paratormalde
1. 5
4. 6
2. 4
hyde ...................... -.
mixture before setting) to any defect and/or cavity which
requires subsequent ?lling. Such “repairs” form a con
1 Little foam.
1 No foam.
tiguous, adherent structure that maintains the essential
characteristics of the initial foam.
The product from Example 4 has a uniform multicellu 65
Another facet of this invention is the substitution of
lb.lcu. ft ................... ._
Water Solubility ____________ .
lar structure.
It is insoluble in water, is resistant to
some or all of the inert organic ?llers mentioned in the
?ame impingement, and is capable of withstanding con~
examples, by use of an oxidizable powdered solid, such
as graphite, carbon, wood ?our, etc., which may be
tinual exposure of at least 10 minutes to temperatures of
up to 1200° F. The product from Example 5 has similar
properties, but it is soluble in water, as is evidenced by
the ratio of Nap/paraformaldehyde. The product from
Example 6 has similar, but somewhat less refractory
burned to produce an exothermic reaction.
Such an
exothermic reagent has utility in the ?eld of “hot topping”
of metal ingots; i.e., use as a monolithic foam in place
of fabricated refractory forms used to provide heat to
properties, higher density and only slight solubility in
cast metal bodies for feeding shrinkage cavities.
water. The Nap/paraformaldehyde ratio of 2.4/1 is a
It will be noted that, among the other advantages of
borderline value with respect to water solubility. Exam 75 the present solidi?ed foam material over prior art mate
high operating temperatures, light-weight, excellent cavity
?lling properties, shock resistance, and excellent insula
tion properties.
I claim:
1. A process for producing a water-insoluble light rigid
porous rapidly-foamed product having a multicellular
rials, there are included low cost, ease of preparation,
lack of corrosive properties, no need for external heat,
structure consisting essentially of mixing together in an
aqueous medium at ambient temperature about 1 to 20
Furthermore, it is possible to foam
parts by weight of a gas-producing peroxy compound,
about 30 to 135 parts of water-soluble inorganic silicate.
and about 1 to 5 parts of paraformaldehyde, while main
taining a silicate/aldehyde weight ratio between about
additional material on to already-foamed solid so that
the two become welded into a monolithic mass of high
tenacity. This is of importance in repair work where
cavities and broken parts require mending with additional
10 1.26 to about. 2.4 (expressed as NazO/paraformaldehyde) .
2. A process according to claim 1 in which up to 50
The foams of the present invention have advantages
parts of an insoluble ?ller is added to the reaction mixture.
in ?lling cavities to be insulated against heat, cold, or
sound, and in providing intimate contact for more effi
References Cited in the ?le of this patent
cient insulation as compared to the ?tted types. Also,
the foam may be generated in ?ab slab forms or as molds
Thoretz _____________ __ Nov. 17, 1931
for the production of acoustical panels for ceilings and
similar uses.
The reactions involved in the preparation of the foam
are not clearly understood, but it is believed that the ex
pansion element is oxygen, the source of which is the
peroxy compound. The paraformaldehyde is believed
to be decomposed or volatilized in the reaction, so that
the ?nal product consists mainly of hardened silicate and
?ller (if used), which are the essential ingredients of the
16, 1934
22, 1935
Llewellyn et a1 _________ __ May 26,
Fujii et a1 _____________ -_ June 19,
Aberegg _____________ ..- June 13,
' ?nished hardened foam product.
Other materials which may be added to the powder
or liquid ingredients, or to both, prior to foaming, in
‘Great Britain __________ __ Oct. 5, 1933
Mellor: “A Comprehensive Treatise on Inorganic and
clude other exothermic reagents, soluble dyes, pigments,
re?ective ingredients, such as aluminum and magnesium
' ?akes or powder, and the like.
Hobart _______________ _- Jan.
Boller _______________ .... Oct.
Fowler ______________ __ May
Humphries ___________ _... Mar.
Theoretical Chemistry," publ. 1925, Longmans Green &
Co., London, vol. VI, page 334.
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