Note: Descriptions are shown in the official language in which they were submitted.
L32
BUILDING INSUL~TIS~)N PRODILJCrS
Field of the Invention
This invention relates to an insulation product which can serve
basically as a thermal and/or acoustic insulation with concomitant properties
S such as resistance to fire, mould, fungus and bacterial growth control etc.,
when installed in or adjacent ~o walls, floors and ceilings of buildings, con-
tainers and other space enclosures.
Background of ~e Invention
The main components of building insulations usually belong to
one of two groups i.e. mineral materials and organic ones. Glass fiber is a
common rnineral insulating material, usually produced in the form of batts or
sheets or used as a loose fill. In the last case, although not as detrimental tohuman health as asbestos fiber (also a mineral material), glass fiber tends to
emit dust and rninute particles during application.
The second group, organic insulations, in addition to foams
includes various cellulosic fibrous and non-fibrous materials e.g. wood pulp,
cotton, straw, bagasse, wood flour, hemp, rayon and the like. Proposals exist
for cellulosic fiber insulation (CFI) manufactured from recycled newsprint. In
Canada, the requirements for the CFI insulation are specified in the CGSB
standard 51-GP-60M.
In order to increase the fire resistance of loose-fill cellulosic
fiber insulation, various chemicals are added thereto during the preparation s)rapplication stages. Additives to stabilize the insulation i.e. to prevent or reduce
its settling are also employed.
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Loose-fill mineral fiber insulation (MFI), particularly manufac-
tured with molten glass, basalt or slag wool fibers, of~ers an excellent fire
resistance and much smaller settlement than cellulosic insulation.
S In recent years, there has been a tendency to reduce the density
of loose-fill in.sulations, both mineral and cellulosic ones. For example, recent
advances in the fiberization (fluffing) techniques such as one introduced by
Advanced Fibre Technology Inc. reduced the density of blown CFI to as little
as 21 kilograms per cubic meter (1.3 pounds per cubic foot). On the MFI side,
changes in the fibre manufacturing and the installation machinery caused the
density of loose-fill insulations to drop to as little as 9 kg/cu.m. (0.56 lb/cu.ft).
These changes have led to the redustion of field performance of
the building insulation materials. It has been evidenced recently, for example,
that a certain type of mineral fiber loose-fill material can exhibit a thermal
performance, after installation, 30 percent lower than anticipated on the basis
of laboratory testing.
It is well recognized in the art that the choice of an insulation,
particularly thermal one, is a comprornise between its weight, fire resistance,
performance and price.
An alternative to either the MFI or CFI loose fill is a wet spray
systern. Adding water and adhesive will reduce dust and may to some extent
reduce the settlement of the CFI insulation. Adding water may, however,
introduce other problems for the systems applied in the cold climates.
A positive development in the loose-fill and spray CFI and MFI
products was the introduction in recent years of the Blown In Blanket System
(BIBS) such as described in Canadian Patent 1,260,667 issued Sept. 26, 1989 to
,
.
~5~
Sperbcr. In this system, fibrous insulation is installed behind a plastic netting
~mesh) permitting unrestricted air outflow from the cavity while containing the
blown-in material in a confined space.
US Patent 3,902,~13 to Helser et al describes hydrous calcium
silicate insulation products - relatively heavy, solid molded blocks - which
comprise 60-95 % hydrous calcium silicate, 0-20 % fillers, 1-20 % organic
fibers (bleached wood pulp) and 0.1-10 % glass fibers.
US Patents 4,543,158 and 4,513,045 to Bs)ndoc et al describe a
sheet type felt comprising 5-20 % glass fibers, 40-80 % cellulose fibers, binderand asphalt. The felt may be used as roofing underlayment.
Various other types of insulation products are described in US
patents Nos. 3,379,608 (Roberts), 4,024,014 and 4,072,558 (Akerson), and
3,321,171 (Gorka et al). A perlite-based acoustic board comprising volcanic
glass (45-75%~, mineral Iibers and nongelatinous cellulosic fibers is disclosed in
US Patent 3,952,830 to Oshida et al.
While these references describe insulation products comprising,
in combination, certain mineral fibers and cellulosic fibers, these products arenot intended as light-weight insulation suitable to be blown in into house wall
or attic enclosures.
Accordingly, there is still a need for a bonded fibrous lightweight
insulation that could be used for floors, walls and ceilings of buildings, con-
tainers and other space enclosures and applied mainly by blowing. To mee~ the
latter requirement, the insulation should exhibit a relatively easy flow throughthe blowing equipment
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Summa~:y of the Invention
It has been found now that the flowability of a fibrous mixture
depends on the quali~ of the surface of the fibers, or at least some of the
fibers constituting the mixture. l'his finding has been combined with the
S observation that certain wood pulps (e.g. Kraft pulp) consist of fibers having a
rather rough appearance (splinters,nodules,etc.~, while certain other p-ulps,
notably the thermal-mechanical pulp (TMP) and the chernical-thermal-mechan-
ical pulp (CIMP) contain substantially smooth fibers.
According to one aspect of the invçntion, there is provided a
method of manu~acturing an insulation product, the method comprising:
1) providing a mixture comprising at least about 40
wt.~o fibrous cellulosic pulp having predominantly
smooth fibers, a filler, a bonding agent and optio-
nally a fire retarding agent,
2) reducing the density of the mixture to about 15-
45 kg/cu.m, and
3) bringing the moisture content of the mixture to a
level sufficient to achieve at least a partial bonding
of the mixture.
It is important that at least about 10~o by weight of the total
filler is a fibrous material, either inorganic, synthetic or an organic one, thehalance being a non-fibrous particulate material.
Preferably, the fibrous wood pulp is either CTMP or TMP. These
pulps have only been produced for a few years and ha~e not been considered
for insulation purposes. A microscopic examination of these pulps reveals that
the surface of the fibers is very smooth compared to such cellulosic materials
30 as Kraft pulp or recycled newsprint.
Tests have shown that a lightweight building ;nsulation made
with Cl MP cr TMP in the ranges as specified herein, exhibits a markedly
better flowability in blown-;n applications than the glass fiber or other prior
art fibrous materials.
s
Flowability, owed mainly to the smoothness of the fibers, is an
indication of the facility of pneumatic transport of the material through
conduits. A material with a relatively good flowability lends itself to a relative-
ly easy transport and attaining the required performance level at lower density
10 of the final product. It is reasonable to expect any s)ther fibrous cellulosic
smooth-fiber cellulosic material beside CIMP or TMP to perform in a similar
manner as these two pulps.
Examples of the fibrous fillers are, ~or inorganic fibers: glass,
15 basalt, slag, slagstone fibers; for synthetic fibers: acrylic (PMMA)~ carbon,polypropylene fibers; for organic fibers: recycled newsprint and other materials.
Exemplary non-fibrous fillers include: amorphous silica, kaolin,
fly-ash, recycled shredded rubber (e.g. tires) and carbon black powder with
20 d;ameter of about 3-30 microns.
Preferably, the pulp is treated with a fire retarding agent, known
in the art, while moist. Subsequently, it may be fiberized (fluffed) and mixed
with the filler and a bonding agent. The filler, at least the fibrous part thereof,
25 may also be fiberized before being mixed with the cellulosic pulp component.
As used throughout the specification, fire retarding properties
denote: at least partial resistance to fire smouldering, reduction of flame
spread when forcefully ignited, fire extinguishing when fire source is removed.
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Tests conducted to validate the invention have indicated that an
effective insulating material can be obtained in the following range of the
component content: 40-97 G/G cellulosic pulp (CrMP or 1 MP~, 1-50 % filler, 1-
5~o bonding agent and 1-10 C/o fire retarding agent. The above percentages are
S by weight based on ~he dry weight of the mix~ure.
It hax been found that the performance of the insulation of the
invention depends on the degree of fiberization of the cellulosic material.
Compared to a hammer mill technology, it is advantageous to ~iberize the pulp
component (and preferably, also the fibrous filler) using rotational fiberization
as described hereinbelow.
~ccording to another aspect of the invention, there is provided
- an insulation product comprising, on a dry weight basis, at least 40 wt.~o
cellulosic pulp having predominantly smooth fibers, a filler, a bonding agent
and optionally a fire retarding agent. Preferably, the material comprises about
40-97 wt.~o pulp, 150 wt.% filler, 1-5 wt.% bonding agent and 1-1û wt.% fire
retardant.
The material is preferably admixed with an inert liquid cornpat-
ible with the bonding agent, practically water, shortly before application. The
amount of the resulting moisture in the material is adapted so as to achieve at
least a partial bonding of the material by reaction of the bonding agent with
the water. The actual final water content will depend on a choice and content
of the components of the product of the invention.
Before application, the density of the material is preferably
reduced, in order to provide a lightweight insulation, to about 15-45 kg/cu.m.
It will be appreciated, however, that the invention also encompasses the
product before the density reduction.
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Brief Description of the Drawin~
Xn the drawing, the single figure represents a graph illustratirlg
the thermal performance, in terms of thermal resistivi~ per inch, of the
insulation of the invention as compared to prior art insulating materials.
s
Detailed Description of the lnven~2~
In tests conducted to validate the invention, the pulp (CI-MP or
TMP) was ohtained from a paper m;ll as a wet swbstance, usually containing
about 40-50 % of solid material by weight. A fire retarding agent, or agents,
10 was added either to the wet pulp during the pulp manufacturing process, or tothe relatively dry mixture of the pulp with the filler during the insulation final
preparation stage, as described below. Beside a fire retardant, it is known to
'add to a building insulation other chemicals for one or more of the ollowing
functions: to control mould, fungi and bacterial growth; to balance pH in order
15 to reduce the risk of corrosion; to reduce fiber swelling and shrinking. A list of
acceptable fire retarding agents and the additional chemicals includes, among
others, borax, boric acid, aluminum sulphate, alumina, calcium sulphate,
dicalcium hydrogen phosphate, bismuth(II) chloride, urea, sodium carbonate,
sodium silicate, tin(II) chloride. These agents may be added singly or in
20 combination depending on the desired properties of the final insulation.
The choice of a filler, both fibrous and non-fibrous one, is
dictated by a requirement that the infrared opacity factor (extinction coeffi-
cient for long-wave thermal radiation) of the filler contribute to an increased
25 thermal performance of the insulation by reducing the radiative heat transferthrough the insulation, and that its specific surface is large enough for bonding
into the multiphase fibrous system of the insulation product of the invention.
Water is a necessary additive to the pulp/filler/bonding agent
30 mLxture to achieve a bonding, or partial bonding, of the final product when
3L3
blown in, or sprayed, in the xite. The pulp, a.s mentioned above, usually carries
certain amount of water, but it is usually necessary to increase the water
content to a sufficient limit for bonding to ~ake place. However, the amount of
free water in the flnal product must be limited so that the insulation's thermal5 (or acoustic) performance is not impaired. Therefore, it is recommended to
adjust the amount of water in the product before installation so that the water
forms an integral part of the insulation due to physical and chemical reactions
with the bonding agent and other components of the insulation. Physical
bonding may be achieved by limited admixture to the insulation of calcinated
10 gypsum or cement powder. Chemical binding of water may be effected by the
use of e.g. isocyanurates.
Bonding agents suitable for the purposes of the invention are, for
instance, polyvinyl acetate, polyurea and styrene/butadiene rubber latex binder.
The pulp is fiberized either before being mixed with the filler or
afterwards. Preferably, both the pulp and the fibrous filler are fiberized
(fluffed) and admixed with chemicals before being mLxed together in a cyclone
for a substantially uniform distribution of the components throughout the
20 mixture. The mixture can then be stored in bags and carried to the site where final fiberization and water addition takes place.
The following examples, as part of the testing program, serve to
illustrate the invention in more detail.
Example 1
CIMP pulp with freeness of approximately 500, was made from
spruce and partially dewatered to moisture content of about 8%. It was then
admixed with about 9 % by weight ~on a dry basis) of each borax and boric
30 acid and then fiberized using a modified commercial rotational fiberizing
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equipment. The glass fiber material used ha(l fibers in the length range of 3-6
mm. After fiberi~ation, 90 part by weight of the treated pulp was mixed in a
cyclone with 10 parts by weight of glass fiber which was also prefiberized usinga commercial blowing machine. The mixture, without the addition of a bonding
5 agent, was then packed in bags and transported to a set-up which comprised a
blowing machine equipped with a positive displacement blower and an air lock
but no shredder nor agitator. An additional rotational fiberizer was disposed inline of the flow of the material (a cylinder wi~h spirally disposed sharp protru-
sions which force rotational movement and impact fiberization of the
10 material). The fiberized mixture was then packed to predetermined densities
using test frames (600x600x150 mm). The densities were:18, 21, 24, 28, 44
kg/cu.m. Thermal resistance of the respective insulations in relation to their
densities is shown in the drawing (points marked 1). It can be seen that despitethis broad density span, thermal resistance of this product varies little.
Example 2
In this example, all the steps were identical as in Example 1
except a different treatment after the blowing machine set-up. In this example,
20 the mixture was then sprayed with an equivalent amount (1:1 by weight~ of a
mixture of water (90%) and a commercial latex adhesive (1û%). The insulation
material was fiberized to a density of about 17 kg/cu.m. Thermal resistivity of
the insulation was tested after the material was oven-dried, and it was found tobe slightly better (see point 2 in the graph) than that of the material of
25 Example 1.
Example 3
CIMP was mixed with a filler (90:10 wt.%) consisting of rock
modified slag wool having relatively short fibers (1-2 mm). The moisture
30 content of CIMP was the same as in Examples 1 and 2. The insulation was
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prepared using the same equipment as in ~xample 2 (fiberization with a
conventional blowing machine and spraying). The final density of the material
was about 32 kg/cu.m. The thermal performance of the material (point 3) was
similar to that of material of Example 1 at comparable density.
s
Example 4a
Example 4a is identical as example 1 except that CTMP was
mixed with only 1 wt.% s)f glass fiber. The density of the material was about 15kg/cu.m. The thermal resistivity is shown in the graph (point 4a).
Example 4b
In this example, the amount of the filler, rock rnodiffed slag wool
having fibers in the length range of 3 - 6 mrn, was S0 wt.~o (50 wt.% pulp~.
The pulp selected (CTMP) had a relatively low freeness of approximately 350.
~he preparation of the insulation and the apparatus used were as in the
example 4a. The density and thermal performance of the material are indi-
cated in the graph (point 4b).
ExampLe S
Conventional fibrous insulations were tested for their thermal
resistivity at comparable densities. The thermal properties are displayed in thegraph as follows: point S - GFI 1 (glass fiber insulation), point 6 - GFI 2, point
7 - a low density cellulosic fiber insulation (CFI~ manufactured of recycled
newsprint, at a density of 25 kg/cu.m., and point 8 - a standard cellulosic fiber
insulation with a density of about 43 kg/cu.m.
Conclusions
The comparison of product of Example 2 with that of Example 1
indicates that the fiberization of the product is not impaired by the spraying
with adhesive/water.
An insulation of the invention (example 4a~ exhibits a be~ter thermal perform-
ance than each of the used components. It showld be noted that the mineral
fiber used in the example 4b is one of the best commercially available in North
Arnerica slag/rock melt with long fibers. This mineral fiber, not suitable by
S itself for pneumatically applied loose fills (due to fiber breakage) may be
successfully applied for the production of the insulation of the invention.
It is evident, when analyzing the results of examples 4a and 4b,
that the mixing in the fiberized condition of partly wet cellulosic fibers with
10 inorganic fibers results in a f;ber ma~rix with improved thermal properties. It
appears also that the degree of fiber refining (fiberizing) may h~ve a larger
effect on the thermal performance of the product than variation in perform-
ance of one of the fibrous materials used for the multifiber system, or even
varying the fraction of the second fiber (filler) in the mixture belween 1 and
15 50% of the total fiber.
It can be seen from the graph that the insulation of the invention
(points 1,2,4a,4b) has better thermal resistance than glass fiber ;nsulation
(points 5 and 6). It has somewhat lower thermal resistance than CFI (points 7
20 and 8), but the density of the insulation of the invention is clearly lower than
that of the cellulosic fiber insulation.
Referring to the graph, the field marked by a triangle is of
particular interest because of relatively low density and good thermal perform-
~5 ance of the insulation.
The above results indicate that fiberization (refining) of thefibrous mixture can be controlled to maintain high thermal resistance for the
density range 15-Z kg/cu.m. while at the same time 20 to 30 % of the high-
30 performance fibrous mix can be replaced with lower quality fillers or fibers e.g.
~5g~L3;~
derived from recycled substances. This may be of advanta~e when designing~ire-protective and sound absorbing products based on the present invention.
Regarding the sequence of the manufacturing processJ it should
S be emphasized that the process may take place partially at a plant, where the
mixture is partly fiberized, admixed with some chemicals and bagged, and
partly at the installation site where the final fiber;zation and admixture of
water (and a bonding agent) may be effected. Al$ernatively, all the steps may
take place at the site.
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