Fibrous product and method and apparatus for producing same

The disclosure embraces a fibrous product comprising amorphous glass fibers and crystallizable mineral fibers wherein the mineral fibers may be formed of fusible rock, slag, basalt rock or fibers formed of blends or mixtures of these materials or crystallizable ceramic fibers and to a method and apparatus for forming or processing blends, composites or laminations of such fibers to produce several composite fibrous end products having various uses such as fire rated acoustical tile and ceiling board, high temperature block and pipe insulations, roofing insulation, form board, fire rated cores for walls and doors, fire rated hardboard and building, pouring and blowing wool insulation.

The invention relates to products fashioned of two or more kinds of fibers 
formed of different materials having different characteristics, and to a 
method of and apparatus for forming, combining, blending or laminating 
fibers of the different materials. The invention more especially relates 
to forming, combining, blending or laminating crystallizable mineral 
fibers and amorphous glass fibers, and to a method of processing such 
fibers and end products fashioned of the two kinds of fibers. 
Crystallizable fibers are made by well known cupola processes or by 
electric melting furnaces from fusible rock or slag or combinations of 
fusible rock and slag and are usually referred to as mineral fibers. 
Ceramic fibers, such as aluminum silicate fibers, are also crystallizable, 
and such ceramic fibers, rock wool fibers and slag wool fibers are 
referred to herein as crystallizable mineral fibers. Crystallizable 
mineral fibers, such as rock wool and slag wool fibers, have been 
heretofore used as thermal insulation in the form of batts, mats or in 
nodules of a character which may be blown into spaces in building 
constructions. 
Mineral wool fibers are usually comparatively short, and products such as 
hardboards or panels fashioned of compressed mineral fibers have 
comparatively low strength characteristics by reason of the short length 
fibers. Crystallizable mineral fibers have a further disadvantage in that 
they contain a high "shot" content, that is, particles of unfiberized 
mineral material. However, mineral wool fibers and particularly mineral 
fibers having a high iron content have good thermal properties as they are 
comparatively short and hence a mass of such fibers provides a tortuous 
path for heat transfer through the pack. 
Crystallizable mineral fibers have a high resistance to fire or flame and 
further have the characteristic of crystallizing at temperatures above 
1000.degree. F., this characteristic being particularly desirable where 
the fibers are used for fire resistant insulation. For example, a ceiling 
tile or panel fashioned of mineral fibers, when subjected to high 
temperature such as that encountered by fire, is highly resistant to 
collapse as the mineral fibers crystallize or devitrify into a 
substantially rigid mass. 
Glass fibers formed from amorphous glass have several advantages not found 
in products fashioned of crystallizable mineral fibers. Glass fibers are 
usually longer and hence impart high strength characteristics to products 
fashioned of such fibers. Masses of glass fibers have no appreciable 
"shot" content as the glass fiber-forming processes attenuate 
substantially all of the material of the glass streams into fibers. 
Glass fibers, when pressed or formed into panels, tiles, hardboard or the 
like, provide smooth, attractive surfaces and hence surfaces of walls, 
ceilings and the like faced with glass fiber panels or tiles do not 
require finishing other than light sanding, painting or facing with a 
film. While amorphous glass fibers are resistant to temperatures below 
their fusing point, under high temperatures the glass fibers fuse or melt 
and wall panels or ceilings fashioned of glass fibers may collapse when 
subjected to high temperature flames. 
The invention embraces a method of processing resin-bearing crystallizable 
mineral fibers and resin-bearing amorphous glass fibers with the resin in 
a particularly cured "B" stage which results in fibrous products having 
performance characteristics superior to those products produced from 
either crystallizable mineral fibers or amorphous glass fibers used alone. 
The invention embraces composite fibrous products of various types 
resulting from combining, blending, laminating or processing 
crystallizable mineral fibers and amorphous glass fibers in a manner to 
produce such products. 
An object of the invention resides in producing fibrous products of 
crystallizable mineral fibers and amorphous glass fibers which have 
improved thermal properties and high fire or heat resistance. 
Another object of the invention resides in forming amorphous glass fibers 
and concomitantly mixing, blending or bringing together crystallizable 
mineral fibers and amorphous glass fibers to form a composite mass or mat 
of the fibers having improved fire resistance characteristics and improved 
insulating characteristics. 
Another object of the invention resides in a method of forming amorphous 
glass fibers, delivering bonding resin onto the glass fibers, collecting 
the glass fibers in a mass, feeding mineral fibers bearing a bonding resin 
into contiguous relation with the glass fibers, and processing the 
composite mass of fibers into a body of desired density, and curing the 
resin in the body. 
Another object of the invention resides in a method of concomitantly mixing 
or blending amorphous glass fibers and crystallizable mineral fibers, 
collecting the mixture or blend of fibers on a conveyor, the two types of 
fibers being substantially homogeneously distributed throughout the 
collected mass of fibers. 
Another object of the invention resides in forming a body of attenuated 
amorphous glass fibers, delivering an uncured bonding resin onto the glass 
fibers, collecting the glass fibers in a layer on a conveyor, delivering 
crystallizable mineral fibers bearing an uncured resin into contiguous 
relation with the glass fibers whereby a composite fibrous mass is formed, 
compressing the collected crystallizable mineral fibers and amorphous 
glass fibers to a body of increased density, and curing the resin in the 
fibers to establish rigidity in the compressed body of fibers. 
Another object of the invention resides in establishing a layer of 
crystallizable mineral fibers bearing a partially cured bonding resin, 
establishing a layer of amorphous fibers bearing a partially cured bonded 
resin in contiguous relation with the layer of crystallizable mineral 
fibers, compressing the fibrous body comprising the layers of fibers to an 
increased density, and curing the resin on the fibers to form a 
substantial rigid composite fibrous product. 
Another object of the invention resides in processing amorphous glass 
fibers and crystallizable mineral fibers to establish a blend or mixture 
of the fibers having characteristics enhancing the use of the blended 
fibers for installation by an air blowing process.

In order to clarify the terms identifying fibers embraced within the 
invention, there are two types of fibers referred to herein, viz. 
crystallizable mineral fibers and amorphous glass fibers. Crystallizable 
mineral fibers as used herein refer to fibers made from fusible rock, 
including basalt rock, slag or fibers made from mixtures of fusible rock 
and slag or ceramic materials such as aluminum silicate, the normal 
process of forming crystallizable mineral fibers including the use of a 
conventional cupola containing the fusible mineral materials fired with 
coke or the mineral material melted in an electric furnace. 
The term amorphous glass fibers as used herein refers to amorphous glass 
compositions which do not readily crystallize and that may be attenuated 
into comparatively fine or coarse fibers, the glass compositions being of 
conventional character which are attenuable to fibers of comparatively 
long lengths depending upon the fiberizing process employed. The amorphous 
glass compositions may be of the character disclosed in U.S. Pat. to 
Welsch Nos. 2,877,124 and 2,882,173. 
Referring to the drawings in detail and initially to FIG. 1, there is 
illustrated an arrangement or apparatus for forming attenuated fibers of 
heat-softened amorphous glass and for mixing or commingling crystallizable 
mineral fibers with the attenuated amorphous glass fibers and processing 
the mass of commingled fibers. FIG. 1 illustrates a melting and refining 
furnace 10 in which amorphous glass batch is conditioned by the 
application of heat in a conventional manner to a heat-softened or 
flowable state, the flowable glass being refined in the furnace 
construction. 
Connected with the furnace 10 is a forehearth 12 having a channel 14 in 
which glass flows from the furnace. Arranged along the bottom of the 
forehearth in spaced relation are stream feeders or bushings 16, each 
feeder flowing or delivering a stream 18 of amorphous glass from the 
forehearth channel 14. A fiber-forming unit or instrumentality 20 is 
disposed beneath each stream feeder and each unit adapted to receive a 
glass stream 18. The fiber-forming arrangement illustrated in FIGS. 1 and 
2 is of the general character of that disclosed in Kleist U.S. Pat. No. 
3,759,680. 
FIG. 2 illustrates a top plan view of one of the units 20. While three 
fiber-forming units 20 are illustrated in FIG. 1, it is to be understood 
that a greater or lesser number of units may be employed depending upon 
the rate of production of attenuated amorphous glass fibers desired. Each 
fiber-forming unit 20 is adapted for forming the glass of a stream 18 into 
discrete bodies, primary filaments or small streams by centrifuging the 
heat-softened glass from a hollow spinner or rotor, the linear bodies, 
primary filaments or small streams being attenuated to fibers by an 
annularly-shaped, high velocity gaseous blast. 
The fiber-forming units 20 include support members 22 which are mounted by 
conventional structural frame means (not shown). The fiber attenuating 
region of each fiber-forming unit is surrounded or embraced by a 
thin-walled cylindrically-shaped guard 24 supported by brackets 25. 
Journally supported in bearings mounted by a frame member 27 is a shaft 
28, a hollow spinner or rotor 30 being secured to the lower end of each 
shaft 28. The upper end of each of the shafts 28 is equipped with a sheave 
or pulley 32. 
As shown in FIG. 2, each unit is provided with an electrically energizable 
motor 34, the shaft of each motor provided with a sheave or pulley 36. A 
drive is established for each spinner 30 by a belt 38 connecting the 
sheaves 32 and 36. Each frame member is fashioned with an opening 40 
through which a stream 18 of glass flows into a spinner or rotor 30. 
The peripheral wall of the spinner or rotor 30 is fashioned with a large 
number of small orifices or passages (not shown) there being ten thousand 
or more orifices through which the heat-softened glass in the interior of 
the spinner is projected outwardly by centrifugal forces as small streams, 
linear bodies or primary filaments. 
Each of the members 22 is provided with an annular combustion chamber 48 
which is lined with refractory (not shown), each chamber having an annular 
discharge outlet or throat adjacent and above the peripheral wall of each 
spinner 30. A fuel and air mixture is admitted into the chamber 48 and 
combustion occurs therein. The products of combustion in the chamber are 
extruded through an annular throat or opening as a high temperature gas 
stream providing a heated environment at the peripheral wall of the rotor 
for the centrifuged glass streams or primary filaments. 
Surrounding the spinner is an annular blower construction 52 which has an 
annular outlet or delivery orifice adjacent to and spaced from the 
peripheral wall of the spinner 30. Steam, compressed air or other gas 
under pressure is admitted to the blower 52 and the blast from the blower 
engages the bodies, primary filaments or streams of amorphous glass 
centrifuged from the openings in the wall of the spinner 30 and attenuates 
the amorphous glass into fibers 54. 
It is desirable in fashioning certain end products from the fibers 54 to 
deliver a bonding resin onto the fibers as they move downwardly from the 
attenuating units 20. Supported by each of the guard members 24 and 
arranged in spaced circumferential relation are applicator nozzles 58 for 
delivering bonding resin, binder or adhesive onto the fibers 54. 
In the embodiment illustrated in FIG. 1, the amorphous glass fibers are 
delivered into a rectangularly-shaped chamber or forming hood 60 defined 
by a walled enclosure 62. The enclosure 62 is open at the bottom and 
arranged at the base of the chamber 60 is the upper flight 66 of a movable 
fiber collector, receiver or foraminous conveyor 67. The collector or 
conveyor 67 is supported and guided by pairs of rolls 69, one of the rolls 
being driven by conventional motive means (not shown) to advance the upper 
flight 66 in a right-hand direction. 
Positioned beneath the upper flight 66 in registration with the forming 
chamber 60 is a suction chamber 71 defined by a thin-walled receptacle 72, 
the suction chamber 71 being connected by a pipe 74 with a suction blower 
of conventional construction (not shown) for establishing subatmospheric 
or reduced pressure in the chamber 71. The reduced pressure or suction 
existent in the chamber 71 assists in the collection of the amorphous 
glass fibers upon the collector or conveyor flight 66 and the spent gases 
of the attenuating blasts from the blowers 52 are conveyed away through 
the pipe 74. The chamber 60 constitutes a fiber-receiving station. 
The arrangement illustrated in FIG. 1 is inclusive of means for delivering 
crystallizable mineral fibers into the chamber 60 whereby the 
crystallizable mineral fibers are combined, mixed or commingled with the 
amorphous glass fibers moving through the chamber. As shown schematically 
in FIG. 1, there are three mineral fiber delivery means or units 78, the 
units being adapted to direct the crystallizable mineral fibers into 
combining or commingling relation with the amorphous glass fibers. 
Each of the units 78 is inclusive of a housing 80 which is provided with 
fiber delivery or discharge means or nozzle 82. Disposed within the 
housing 80 is a picker device 83 which comprises rotatably mounted pickers 
or picker wheels 84 having peripheral teeth arranged to engage and fluff 
up the nodules of crystallizable mineral fibers fed to the wheels. The 
picker device is conventional and is driven by a motor (not shown). 
The function of the picker wheels 84 is to break up the nodules of 
crystallizable mineral fibers to effect a degree of separation of the 
fibers to attain better distribution of the crystallizable mineral fibers 
with the amorphous glass fibers. The crystallizable mineral fibers are 
indicated at 86. Each housing 80 is equipped with a guide means 88 to 
receive a body 90 of crystallizable mineral fibers from a supply (not 
shown). 
One method of forming crystallizable mineral fibers is schematically 
illustrated in FIG. 3 and hereinafter described. The crystallizable 
mineral fibers may be delivered from a fiber-forming means directly to the 
picker devices 83. Any of the well known conventional methods of forming 
crystallizable mineral fibers may be used. 
Air tubes 92 are formed on the housings 80 and are adapted to be connected 
with a source of compressed air or other gas under pressure for delivering 
or projecting the crystallizable mineral fibers from the nozzles 82 to 
promote better distribution or commingling of the crystallizable mineral 
fibers with the amorphous glass fibers moving through the chamber 60. 
The amorphous glass fibers 54 are usually several inches in length while 
the crystallizable mineral fibers are of short lengths usually less than 
one inch with a substantial percentage less than one-fourth inch which 
enhances a more homogeneous mixing of the short length mineral fibers with 
the longer amorphous glass fibers. In the arrangement illustrated in FIG. 
1, the blended, mixed or commingled amorphous glass fibers 54 and the 
crystallized mineral fibers 86 are collected as a mass 87 on the collector 
or conveyor flight 66. 
Organic thermosetting bonding resins are delivered onto both the amorphous 
glass fibers and the crystallizable mineral fibers. Bonding resins that 
may be used include phenol formaldehyde resin or copolymer of phenol 
formaldehyde resin and urea, melamine or dicyandiamide resins. Typical 
resin compositions that may be used are disclosed in U.S. Pat. to Stalego 
No. 3,223,668 and in U.S. Pat. to Smucker et al 3,380,877. The resin is 
usually applied in an "A" stage ie. in a water soluble/dispersible 
solution depending upon the end use of the product. In the arrangement 
shown in FIG. 1, the bonding resin is delivered onto the amorphous glass 
fibers by applicators 58. A bonding resin of the same or compatible 
character is delivered onto the crystallizable mineral fibers in advance 
of their delivery to the picker devices or units 78. 
The commingled resin-bearing fibers are thereafter processed in a manner 
depending upon the end use for the product. The ratio of the two types of 
fibers in the fiber blend or mass may vary between about ten percent 
crystallizable mineral fibers to ninety percent amorphous glass fibers or 
ten percent glass fibers to ninety percent mineral fibers, a preferred 
blend range being fifty percent crystallizable mineral fibers and fifty 
percent amorphous glass fibers to a ratio of seventy-five percent 
crystallizable mineral fibers and twenty-five percent amorphous glass 
fibers. 
As illustrated in FIG. 1, a sizing roll 94 or other fiber compressing means 
is disposed at the exit end of the chamber 60 and is adapted to be rotated 
by a suitable means (not shown). The mass 87 of fibers is compressed into 
a mat 95 to an extent depending upon the density of the composite fibrous 
body desired. The range of density of the mat may be varied depending upon 
the end use for the product. 
In the embodiment illustrated, the mat 95 of compressed fibers impregnated 
with binder is advanced by endless belts 96 and 97 through a curing 
chamber 98 of an oven 99 in which the binder or resin is set or cured by 
the application of heat in a well-known conventional manner. The cured mat 
is particularly useful as insulation as the longer amorphous glass fibers 
contribute strength and resiliency to the mat, and the shorter 
crystallizable mineral wool fibers improve thermal properties as they 
promote a more tortuous path for heat movement through the mat. 
These factors significantly improve the fire resistance of the mat 
particularly since the crystallizable mineral fibers crystallize or 
devitrify very rapidly when subjected to high temperatures of over 
1000.degree. F. Where the crystallizable mineral fibers have a high iron 
content, the thermal and fire resistance properties of the products made 
from blends of crystallizable mineral fibers and amorphous glass fibers 
are further improved. 
The fibrous mat 95, upon curing of the binder, may be used as insulation in 
fire rated acoustical systems, high temperature resistance block, roofing 
insulation, form board, fire rated cores for walls and doors, fire rated 
hardboard and other similar uses. While the method illustrated for forming 
amorphous glass fibers 54 involves blast attenuation of centrifuged glass 
streams or primary filaments, it is to be understood that other methods 
may be utilized for forming amorphous glass fibers, as for example the 
method and arrangement disclosed in Stalego and Leaman U.S. Pat. No. 
3,002,224. 
The invention includes the processing of amorphous glass fibers and 
crystallizable mineral fibers to produce a blend or mixture of such fibers 
of suitable character whereby the fibers may be blown into spaces in 
building constructions as thermal insulation. In processing the composite 
fibers to provide a product that may be air blown, the mass of mixed or 
commingled fibers 87 which comprises a mixture or blend of amorphous glass 
fibers and crystallizable mineral fibers is delivered in an uncompressed 
state through the curing chamber 98 to set or cure the binder in the 
fibers. The mixture of fibers for use as thermal insulation may be of a 
density of about two pounds per cubic foot. 
The mass of fibers is then delivered to a conventional instrumentality 
known as a beater or granulator (not shown) which fractures or breaks up 
the longer fibers to shorter length fibers to enhance air blowing of the 
mixture. 
Applicant's invention embraces a method of forming, processing or utilizing 
bodies or laminations of amorphous glass fibers and bodies or laminations 
of crystallizable mineral fibers in producing several types of composite 
fiber end products. 
FIG. 3 is illustrative of method and apparatus for concomitantly forming 
amorphous glass fibers and crystallizable mineral fibers and collecting 
the respective fibers in contiguous layers. In FIG. 3 the instrumentality 
or unit 20' for forming amorphous glass fibers corresponds with one of the 
units 20 shown in FIG. 1. The unit 20' receives a stream 18' of glass from 
a forehearth 12', the heat-softened amorphous glass flowing into the 
forehearth from a melting and refining furnace 10'. A single amorphous 
glass fiber attenuating unit 20' is illustrated in FIG. 3, but it is to be 
understood that more than one unit may be used in the manner illustrated 
in FIG. 1. 
The attenuated amorphous glass fibers 54' move downwardly from the 
attenuating instrumentality 20' into an enclosure or forming hood 104 
which defines a chamber 106. Mounted by the enclosure 104 are applicators 
107 for delivering thermosetting resin or binder onto the fibers 54'. It 
is to be understood that the applicators may be mounted by the attenuating 
instrumentality in the manner illustrated in FIG. 1. 
The fibers are collected upon an upper flight 108 of a foraminous conveyor 
or collector 109 as a layer 112, the upper flight 108 of the conveyor 
moving in a right-hand direction. Disposed below the upper flight 108 of 
the conveyor 109 is a suction chamber 110, the chamber being connected by 
a pipe 111 with a suction blower (not shown) for establishing 
subatmospheric or reduced pressure in the chamber 110, this arrangement 
assisting in the collection of the fibers upon the conveyor flight 108. 
Disposed adjacent the fiber attenuating unit 20' is a facility or apparatus 
114 for forming crystallizable mineral fibers. In the embodiment 
illustrated in FIG. 3, the mineral fiber-forming facility 114 is inclusive 
of a conventional cupola 115 which is adapted to successively receive 
charges of crystallizable fiber-forming mineral material and coke. The 
coke is burned within the cupola and reduces the mineral material to a 
flowable or molten state, the molten material collecting in the lower part 
of the cupola. 
Connected with the cupola near the bottom is a spout 116 providing a port 
for the discharge of a stream 118 of the molten mineral material. The 
stream 118 of mineral material is delivered to a conventional attenuating 
instrumentality for fiberizing the mineral material. In the schematic 
illustration of FIG. 3, the stream 118 is engaged with a rotating wheel 
120 driven by a motor 122. The engagement of the stream of mineral 
material with the rotating wheel 120 shatters or breaks up the stream to 
form fibers of the mineral material. 
In the process of fiberizing fusible rock or slag, it is well known that a 
substantial portion of the mineral material is unfiberized and is in the 
form of fine particles or "shot". While a rotating fiberizing wheel 120 is 
illustrated in FIG. 3, it is to be understood that other conventional 
methods may be used for fiberizing the molten mineral material such as a 
plurality of rotating wheels. Another conventional method utilizes a high 
velocity blast of steam to shatter or break up the stream of molten 
material in fiberizing the mineral material. 
The arrangement shown in FIG. 3 is inclusive of a forming chamber 123 
defined by a walled forming hood 124, the walled hood having an entrance 
opening 125 through which the crystallizable mineral fibers 128 and some 
of the unfiberized material or "shot" are delivered into the chamber 123. 
An applicator 129 is mounted by the forming hood 124 for delivering 
thermosetting resin or binder onto the fibers 128, the binder or resin 
being of the same character as the binder delivered from the applicators 
107 onto the amorphous glass fibers in the chamber 106. 
The fibers 128 and the unfiberized material are delivered onto the upper 
flight 130 of a foraminous conveyor 131 which is mounted on rolls 132, one 
of which is a driven roll for moving the upper flight 130 of the conveyor 
in a left-hand direction. Disposed beneath the upper flight 130 of the 
conveyor 131 is a suction chamber 133, the chamber being connected by a 
pipe 134 with a suction blower (not shown) for establishing subatmospheric 
or reduced pressure in the chamber 133. 
The suction or reduced pressure in the chamber 133 assists in collecting 
the crystallizable mineral fibers 128 on the conveyor flight 130 to form a 
layer or mass 135 of crystallizable mineral fibers on the conveyor flight 
130. The suction or reduced pressure in the chamber 133 also assists in 
removing unfiberized particles or "shot" from the mineral fibers on the 
flight 130 of the conveyor and thereby effectively reduces the amount of 
unfiberized material in the layer 135 of crystallizable mineral fibers, 
the unfiberized material being conveyed away through the pipe 134 as 
waste. 
As illustrated in FIG. 3, the layer or mass 135 of crystallizable mineral 
fibers is delivered by the conveyor 131 into contiguous relation with the 
layer 112 of amorphous glass fibers on the collector or conveyor flight 
108. The composite fibrous body 138 may be further processed to form 
various end products. For example, the fibrous body or assemblage 138 may 
be compressed to a high density and the resin in the fibers fully cured to 
form a substantially rigid hard board. 
If it is desired to concomitantly form a fibrous body or assemblage of 
multilayers of fibers, additional fiber-forming units 20 and mineral fiber 
attenuating facilities 114 may be positioned alternately along the 
conveyor flight 108 whereby the collected amorphous glass fibers and 
crystallizable mineral fibers are arranged in contiguous alternate layers 
or laminations. 
It is to be understood that layers of resin-bearing amorphous glass fibers 
and layers of resin-bearing crystallizable mineral fibers may be formed 
separately and brought into contiguous relation to form laminated products 
of the two types of fibers. FIG. 4 is illustrative of assembling a layer 
142 of preformed amorphous glass fibers with a layer 144 of preformed 
crystallizable mineral fibers. 
The layer 142 of amorphous glass fibers may be formed into a roll 146 as 
the layer of fibers is delivered from a fiber attenuating unit such as a 
unit 20. The layer 144 of crystallizable mineral fibers may be formed into 
a roll 148, the layer of crystallizable mineral fibers being taken 
directly from a fiber-forming facility of the character shown in FIG. 3. 
The resin-bearing layers or laminations 142 and 144 may be brought into 
contiguous engaging relation as shown in FIG. 4, the assemblage being 
conveyed through suitable sizing or compressing rolls and the assemblage 
delivered through a curing oven to set or cure the binder in the fibrous 
layers. The assemblage of the layers of fibers may be compressed to a 
density desired depending upon the particular end product. The layers of 
fibers are adhesively joined by the resin or binder. 
Where the end product is acoustical tile, wall paneling, pipe insulation or 
the like, the assemblage of layers may be compressed to a density in a 
range of from one pound to about sixteen pounds or more per cubic foot. 
FIG. 5 is illustrative of a laminated fibrous body or assemblage 150 
comprising alternate layers of amorphous glass fibers and crystallizable 
mineral fibers. In FIG. 5, the outer layers 151, 152, and the central 
layer 153 are of resin-bearing amorphous glass fibers and the intermediate 
alternate layers 154, 155 are of resin-bearing crystallizable mineral 
fibers. The assemblage 150 comprising the fibrous layers may be compressed 
by sizing rolls or other means and the compressed laminated body or 
assemblage subjected to heat in an oven to set or cure the binder in the 
fibers of the layers. 
The assemblage 150 compressed to a comparatively high density is usable as 
fire-rated hardboard, roof insulation or the like. Hardboard or roof 
insulation of this character has high strength characteristics and, if 
subjected to high heat or flames, the amorphous glass fibers may be 
melted, but the crystallizable mineral fibers will crystallize at 
temperatures above 1000.degree. F. thus providing a body or board which 
resists collapse by reason of the crystallization or devitrification of 
the mineral fibers. The outer layers 151 and 152 of amorphous glass fibers 
provide a smooth surface finish for the product. The density for hardboard 
is generally in a range of from twenty-five pounds to sixty pounds per 
cubic foot. 
FIG. 6 illustrates a modified assemblage or body 158 of layers of fibers. 
The outer layers 159 and 160 are resin-bearing amorphous glass fibers and 
the inner layers 161 are resin-bearing crystallizable mineral fibers. 
FIG. 7 illustrates the end product formed from the assemblage 158, shown in 
FIG. 6, by compressing the assemblage to a high density and the resin 
cured in the assemblage to form a substantially rigid product 163 such as 
a hardboard or panel comprising compressed outer layers 159' and 160' of 
amorphous glass fibers. 
The outer layers 159' and 160' being of amorphous glass fibers provide a 
smooth surface finish for the panel or hardboard 163. The product 163 has 
high fire rating by reason of the central core being of crystallizable 
mineral fibers which renders the panel resistant to collapse should the 
product be subjected to high heat or flames. 
FIG. 8 illustrates an assemblage or fibrous body 165 which includes outer 
layers 166 and 167 of resin-bearing amorphous glass fibers and a central 
core comprising layers 168 of resin-bearing crystallizable mineral fibers. 
FIG. 9 illustrates the end product formed from the assemblage 165, shown in 
FIG. 8, by compressing the assemblage to a high density and the resin 
cured in the assemblage to form a substantially rigid hardboard, panel or 
like product 171 comprising compressed outer layers 166' and 167' of the 
amorphous glass fibers and the core layers 168' of compressed 
crystallizable mineral fibers. The panel or hardboard 171 has high 
strength characteristics and with a comparatively thick core of 
crystallizable mineral fibers is highly resistant to collapse at high 
temperatures. The products 163 and 171 of FIGS. 7 and 9 may be used as 
acoustical tile and ceiling board or the like. 
FIG. 10 illustrates an assemblage or body 174 of layers of resin-bearing 
amorphous glass fibers and a layer of resin-bearing crystallizable mineral 
fibers. The central layer 175 is fashioned of crystallizable mineral 
fibers and layers 176 of resin-bearing amorphous glass fibers are arranged 
at each side of the central core 175 of crystallizable mineral fibers. 
FIG. 11 illustrates the end product formed from the assemblage shown in 
FIG. 10 by compressing the assemblage to a high density and the resin 
cured in the assemblage to form a substantially rigid hardboard, panel 180 
or the like comprising compressed outer layers 176' of the amorphous glass 
fibers and a central core 175' of compressed crystallizable mineral 
fibers. The panel or hardboard 180 has high strength characteristics by 
reason of the several layers or laminations of amorphous glass fibers. 
FIG. 12 illustrates an end view of an assemblage or body 184 of one or more 
layers of resin-bearing amorphous glass fibers and layers of resin-bearing 
crystallizable mineral fibers, the layers being dimensioned in width to 
fashion the assemblage 184 into a tubular fibrous body 192 illustrated in 
FIG. 13 for use as pipe insulation. The outer layer or lamination 186 of 
the assemblage 184 is of the greatest width and is of resin-bearing 
amorphous glass fibers. The layers or laminations 187, 188 and 189 are 
fashioned of resin-bearing crystallizable mineral fibers, the layers 187 
through 189 being preferably progressively reduced in width to facilitate 
molding the assemblage into tubular configuration. 
The assemblage 184 of layers of fibers is processed in a conventional 
molding apparatus and the fibers of the layers compressed to an increased 
density when the molds are closed. The molds in closed position are 
subjected to heat to set or cure the thermosetting bonding resin in the 
fibers, the molding of the fibers resulting in a tubular configuration or 
tube 192 of the character shown in FIG. 13. An example of one method and 
apparatus for molding fibrous pipe insulation is disclosed in U.S. patent 
to Tkacs 3,088,573. 
The tubular fibrous body 192, shown in FIG. 13, may be split as at 194 and 
the split extended in the lower wall about two-thirds of the wall 
thickness, as shown in FIG. 13, providing a hinge region to facilitate 
assembly or installation of the tubular insulating body 192 on pipe. The 
fibers are compressed by the mold to a density so that the finished 
tubular insulation is substantially rigid. The outer layer 186 of the 
longer amorphous glass fibers imparts high strength characteristics to the 
molded body 192 and the inner layers 187 through 189 of crystallizable 
mineral fibers provide high thermal insulating properties and are 
resistant to collapse under high temperatures as the mineral fibers 
crystallize or devitrify to form a solid body. 
The commingled or blended mixture of amorphous glass fibers and 
crystallizable mineral fibers may be formed into fibrous products through 
the use of a so-called "wet" process. In carrying out the "wet" process 
the amorphous glass fibers and the crystallizable mineral fibers together 
with additives such as clay and starch are mixed together with water to 
form a slurry. The slurry is delivered onto wire conveyor belts such as 
those used in the well-known Fourdrinier paper making machine. 
Dewatering of the slurry on the wire belts is accomplished by gravity and 
by suction or reduced pressure beneath the belts. The "wet lap" or web is 
passed through roller presses for further dewatering and is conveyed 
through a drying facility. The web is then cut into the sizes desired for 
the particular end product. The end products have high strength 
characteristics by reason of the presence of the amorphous glass fibers 
and high fire resistant characteristics provided by the short length 
crystallizable mineral fibers. The products made by the "wet" process are 
generally in a range of density of about twenty-pounds to thirty pounds 
per cubic foot. 
It is apparent that, within the scope of the invention, modifications and 
different arrangements may be made other than as herein disclosed, and the 
present disclosure is illustrative merely, the invention comprehending all 
variations thereof.