Sheet type roofing

Sheet type felt material and sheet type roofing material such as shingles and rolls made therefrom. The felt comprises 10-60 wt % glass fibers of varying lengths, 15-80 wt % cellulosic fiber and 5-25% binder. The roofing material is felt of the invention saturated with asphaltic saturant and coated with filled asphaltic coating material and conventional roofing granules.

BACKGROUND OF THE INVENTION 
The invention relates to sheet type felt suitable for use in manufacture of 
roofing material and to sheet type roofing material such as shingles made 
therefrom. 
Sheet type roofing materials such as shingles and rolled roofing are 
normally made from cellulosic felt impregnated and coated with asphalt or 
from fiberglass mat coated and impregnated with asphalt. Materials based 
on each of these substrates have certain disadvantages. Conventional sheet 
roofing materials using cellulosic felt substrates do not provide a 
desirable degree of fire protection. Roofing materials based on the use of 
fiberglass mat as substrate can provide the desired degree of fire 
protection, but tend to have inferior handling characteristics in either 
hot or cold weather. 
SUMMARY OF THE INVENTION 
The present invention includes sheet type felt and sheet type roofing 
material incorporating felt of the invention. Sheet type felt of the 
invention comprises on a dry basis: 
(a) between about 10 and about 50 wt % glass fibers having diameters 
between about 3 and about 20 microns, said glass fibers comprising between 
about 50 and about 95 wt % fibers between about 3 and about 7 millimeters 
in length and between about 5 and about 50 wt % fibers between about 10 
and about 15 millimeters in length; 
(b) between about 15 and about 80 wt % cellulosic fibers, said cellulosic 
fibers comprising between about 25 and about 75 wt % short fibers and 
between about 25 and about 75 wt % long fibers, and 
(c) between about 5 and about 25 wt % binder with at least about 0.5 wt % 
of the binder based on dry felt being hot strength binder. 
In preferred embodiments the binder includes styrenebutadiene rubber latex 
and starch or acrylamide resin. 
Sheet type roofing material of the invention comprises felt of the 
invention which is impregnated with between about 80 and about 150 wt %, 
preferably between about 105 and about 130 wt %, based on dry felt of 
asphaltic saturant having a softening point between about 25.degree. and 
110.degree. C., preferably between about 70.degree. and about 100.degree. 
C. In preferred embodiments the saturated felt is coated on both faces 
with filled asphaltic coating material. Unfilled asphalt used for such 
products has a softening point between about 90.degree. C. and about 
115.degree. C. The asphalt is filled with between about 55 and about 75 wt 
% based on said coating of mineral stabilizer. For some uses such as in 
making shingles it is preferred that sheet type roofing material of the 
invention be further coated on one face with conventional roofing 
granules. 
DETAILED DESCRIPTION OF THE INVENTION 
Sheet type felt material of the invention is useful primarily in the 
manufacture of sheet type roofing products such as products suitable for 
use in built-up roofing and especially in the manufacture of roofing 
shingles. Roofing products of the invention possess improved fire 
resistant and handling characteristics when compared with conventional 
roofing products based on either felt or glass mat substrates. These 
improved fire resistant and handling characteristics are achieved by a 
unique combination of a fibrous felt substrate, asphaltic saturant, 
asphaltic coating and mineral aggregate granules. The skeletal structure 
of the fibrous substrate combines with the characteristics of the various 
other components to produce a desired combination of properties including 
fire resistant characteristics and mechanical properties such as tear 
strength, tensile strength, dimensional stability and resistance to 
bending. 
The sheet type fibrous felt of the invention acts as a substrate which 
forms the skeletal matrix upon which the balanced sheet type roofing 
materials of the invention are made. The substrate is impregnated with a 
controlled amount of asphaltic saturant possessing certain softening point 
characteristics. The resulting saturated substrate may then be used in 
certain roofing applications such as in producing certain types of 
built-up roofing or as underlayment. More commonly, however, the saturated 
substrate is further coated with asphaltic coating possessing certain 
softening point characteristics and into which certain quantities of 
mineral filler have been thoroughly mixed. This coating is usually applied 
to both top and bottom faces of the saturated substrate. Such coated 
product is useful for instance as rolled roofing material in the 
production of built-up roofing (BUR). For some applications such as 
shingle manufacture or manufacture of rolled roofing for certain BUR 
applications conventional roofing granules are then applied and pressed 
onto one coated surface which then forms the exposed surface of the 
roofing product. In preferred embodiments back surfacing is applied to the 
other surface of the coated substrate to make it non-sticky. 
The various components of products of the invention, especially of coated 
roofing products, interact in a unique manner to attain the desired fire 
resistant and mechanical properties. The fibrous substrate acts as an 
asphaltic material sink to restrain coating slide during the "spread of 
flame" fire resistance test. The substrate also acts as a sheet insulation 
barrier in the "burning brand" fire test by retaining, even after burning, 
sheet integrity as formed by the skeletal matrix of the glass fiber 
content. The asphaltic saturant impregnates the fibrous substrate and 
fills up its skeletal voids only to a point where the substrate will still 
act as a sink to restrain asphaltic coating slide during fire testing. 
However, the level of asphaltic saturant in the substrate should be such 
that the fiber substrate is essentially completely wetted. Under this 
condition the saturant retards the burning rate of the substrate thus 
enhancing the ability of the substrate and the saturant to form an 
insulating charred material in the burning brand test. 
The asphaltic coating applied to saturated felt substrate of the invention 
should have desired softening point characteristics and mineral filler 
content. In fire resistance tests the flow characteristics of the filled 
coating are critical. The mineral filler content of the asphaltic coating 
should be high enough to develop a high viscosity resistance to flow at 
elevated temperature, but low enough to make production of roofing 
products such as shingles practical. The slow flowing coating will char, 
forming an insulating crusty material that acts as a fire barrier. In 
addition high filler content reduces the amount of combustible material in 
the asphalt coating thereby increasing the overall fire resistant 
characteristics of the product. 
As mentioned above, sheet type felt of the invention comprises as essential 
ingredients cellulosic fiber, glass fiber and binder. 
Cellulosic fibers suitable for use in products of the invention include any 
of the cellulosic fibers commonly used in making materials such as roofing 
felt and may include for instance fibers derived from wood, paper, rags, 
etc. For economic reasons waste paper such as waste newspaper, waste kraft 
corrugated paper, etc. is frequently used. Blends of long and short 
cellulosic fibers are used in order to obtain felt of desired porosity. In 
this respect suitable blends contain between about 25 and about 75 wt % 
short fibers with between about 25 and about 75 wt % long fibers. 
Cellulosic fibers are used in felt of the invention in amounts between 
about 15 and about 80 wt % on a dry basis with amounts between about 50 
and about 60% on the same basis being preferred. Fibers of the type 
normally used in making newsprint are for instance a suitable source of 
short fibers and fibers of the type normally used in making kraft paper 
are for instance a suitable source of long fibers. Suitable short fibers 
normally have lengths between about 0.5 and about 1.5 millimeters. 
Suitable long fibers normally have lengths between about 1.5 and about 3.5 
millimeters. 
Glass fibers are present in felt of the invention in amounts of between 
about 10 and about 60 wt % on a dry basis and more preferably in amounts 
between about 15 and about 35 wt % on the same basis. Chopped glass fiber 
is especially preferred. Glass fibers used have diameters between about 3 
and about 20 microns with fibers having diameters in the general range of 
about 13-16 microns being especially preferred. Fibers of substantially 
smaller diameters are sometimes unsatisfactory because of the deleterious 
effect on felt formation on conventional paper machines and may present 
health problems. In order to form felt of the desired matrix glass fiber 
used should comprise between about 50 and about 95 wt % of fibers having 
lengths between about 3 and about 7 millimeters and about 5-50 wt % of 
fibers having lengths between about 10 and about 15 millimeters. A 
convenient mixture of this type includes about 50-95 wt % glass fibers of 
nominal 1/4 inch (6.4 mm) length mixed with about 5-40 wt % glass fibers 
of nominal 1/2 inch (12.7 mm) length. In general fiber lengths longer than 
about 7 millimeters create difficulty in felt formation. However, use of a 
small amount of longer fibers has a pronounced beneficial effect in 
attaining the desired matrix and fire resistance. It is believed that this 
is due to the superior bridging mechanism of relatively longer fibers 
between felt components so that even after burning, sheet integrity 
without break is maintained. 
Glass fiber content of the felt of the invention is important in 
controlling its porosity and skeletal structure. Low glass fiber content 
in the felt can result is low porosity and, therefore, low rate of asphalt 
saturation and a low order of skeletal structure. In this configuration 
low asphaltic saturant content and low rate of asphaltic saturation can 
occur which reduces chances of passing the burning brand fire test. The 
low order of skeletal structure impairs the functioning of the felt as an 
asphaltic material sink for the asphaltic mineral filled coating in the 
"spread of flame" fire test and does not provide sufficient bridging 
action between felt components to maintain felt integrity in the "burning 
brand" fire test. On the high end of glass fiber content the felt 
substrate tends to be too porous with a high order of skeletal structure. 
Such a felt will uncontrollably absorb excessive amounts of asphaltic 
saturant at a very high rate during roofing shingle processing and this 
has a deleterious effect in the spread of flame test due to severe 
asphaltic filled coating slides. Proper proportions and sizes of 
cellulosic and glass fibers as described herein will provide the desired 
balance of structural properties in the felt of the invention and rendor 
such felt suitable as substrate for roofing material of the invention so 
that such roofing materials can meet the desired standards for mechanical 
strength and fire resistance. 
Binder is used in felt of the invention in amounts between about 5 and 
about 25 wt % based on dry felt with amounts of between about 7 and about 
15 wt % on the same basis being preferred. At least about 0.5 wt % and 
preferably at least about 7 wt % based on dry felt of the binder used 
should be hot strength binder. Suitable hot strength binders include for 
instance acrylamides starch, urea resins, phenol resins, sodium silicates, 
epoxy resins, etc. Other suitable binders include for instance SBR, 
acrylic, neoprene, acrylonitrile or other natural or synthetic latices. A 
preferred binder comprises a mixture of between about 5 and about 15 wt % 
styrene-butadiene rubber (SBR) latex based on dry felt and between about 
0.5 and about 5 wt % based on dry felt of acrylamide resin. Another 
preferred binder comprises between about 5 and about 15 wt % SBR latex 
based on dry felt and between about 1 and about 10 wt % starch based on 
dry felt. A preferred SBR latex is that made by continuous monomer 
addition without the use of surfactant as taught for instance by U.S. Pat. 
No. 4,378,272 the disclosure of which is incorporated herein by reference. 
In addition to the required ingredients of felt of the invention described 
above various optional ingredients may be used including for instance 
flocculants, defoaming agents, precipitants, etc. Suitable flocculants 
include for instance high molecular weight acrylamide polymer such as Betz 
1260 and may be used in amounts of e.g. between about 1/2 pound and about 
8 pounds per ton of dry felt. Suitable precipitants include for instance 
multivalent metal salts or synthetic polymers. 
Felt of the invention may be manufactured in a conventional manner on 
conventional equipment such as single cylinder or Fourdinier machines. 
Felt thickness may vary widely depending upon the desired end use 
application with thicknesses between about 0.4 and 4.0 millimeters being 
suitable for many applications including roll roofing and shingles. In 
order to provide the desired matrix for preferred end uses a dry felt 
apparent density between about 15 and about 35 lb/ft.sup.3 (0.24-0.56 
g/cc) is preferred. 
As mentioned above, felt of the invention may be saturated with asphaltic 
saturant to obtain sheet type roofing material of the invention. Depending 
upon the desired end use, the saturated felt may further be coated with 
filled asphaltic coating material and the coated felt may be further 
coated on one side with conventional roofing granules. In order to obtain 
the desired combination of good mechanical properties and adequate fire 
resistance, the special matrix present in felt of the invention must be 
filled with the proper amount of the proper type of asphaltic saturant and 
for coated product the proper type of asphaltic coating must then be used. 
Asphaltic saturant and coating materials suitable for use in producing 
roofing materials of the invention may be derived from petroleum, coal or 
other sources with saturants and coating materials derived from petroleum 
distillation being preferred. Generally the asphaltic saturant and coating 
materials have similar chemical components. They do, however, differ in 
physical characteristics. Asphaltic saturant for use in producing product 
of the invention should have a softening point as measured by ASTM D-36-76 
of between about 25.degree. and about 110.degree. C., more preferably 
between about 70.degree. and about 100.degree. C. Suitable asphaltic 
coating materials have softening points as measured on the same basis 
between about 90.degree. and about 115.degree. C. Asphaltic coating 
material should contain between about 50 and about 75 wt %, preferably 
between about 60 and about 70 wt %, mineral stabilizer as determined by UL 
55B mineral stabilizer test (Oct. 30, 1974). The mineral stabilizer should 
be of the type commonly used in filled asphaltic coatings and may be 
derived from limestone, stone dust, sand and other sources of suitable 
fine mineral aggregate. 
In forming roofing materials of the invention the felt of the invention is 
impregnated with asphaltic saturant to a saturation level of between about 
80 and about 150%, preferably between about 100 and about 130% (% 
saturation is expressed in weight % by dividing weight of saturant by 
weight of dry felt). When asphaltic coating material is used it is applied 
to both faces of the saturated felt. Top coating on what is to be the 
upper surface of end roofing product usually applies between about 20 and 
about 45 pounds, more preferably between about 25 and about 35 pounds, of 
coating per 100 square feet of surface area of the saturated felt while 
back coating usually applies between about 3 and about 10 pounds per 
hundred square feet. When desired such as for making shingles or certain 
types of rolled roofing material, conventional roofing granules are then 
applied and pressed into the top coated surface for decorative and 
protective purposes. Granules commonly used in roofing manufacture are 
referred to as No. 11 granules and No. 9 granules. No. 11 granules are 
normally used in amounts between about 25 and about 45 pounds per 100 
square feet; and No. 9 granules are normally used in amounts between about 
60 and about 80 pounds per 100 square feet. A fine mineral aggregate such 
as sand is preferably applied to the back coated surface in a conventional 
manner to prevent blocking and sticking. 
As mentioned, felt of the invention may be prepared using conventional 
paper making equipment. In preparing the felt, a blend of cellulosic 
fibers is dispersed in a water slurry in suitable equipment such as a 
hydrapulper. When the fibers are fully dispersed, chopped glass fibers are 
added and thoroughly dispersed in the slurry of cellulosic fibers. Binder 
as called for by the invention is then added and the slurry is mixed 
thoroughly. Binder particles are then precipitated in the slurry using 
aluminum sulphate. Stock consistency is adjusted as desired and the 
completed stock is decanted to the forming end of a conventional paper 
making machine at which point flocculant is usually added and mixed 
thoroughly with the slurry prior to forming the felt product. Subsequent 
processing usually includes pressing for water removal, followed by drying 
and winding into rolls. A defoaming agent may also be used.

The following examples are intended to illustrate the invention without 
limiting the scope thereof. 
EXAMPLE 1 
In order to demonstrate the favorable fire resistance of products made with 
felt of the invention, products were made and tested as described 
immediately below. 
Felt used in this example was made on conventional paper making equipment 
and was identical for all runs except for the varying amounts of glass, 
cellulose and binder and the varying types of binder used as set forth in 
Table I below. The shingles and rolled roofing product referred to in this 
example were made using conventional roofing plant equipment. 
The "burning brand" and "spread of flame" tests reported herein were 
conducted in accordance with ASTM E-108 using simulated roof decks 
prepared as specified in ASTM E-108 except that the "spread of flame" 
differed from that described in ASTM E-108 in that a simulated roof deck 
measuring 40".times.48" was used rather than the 40".times.13' deck 
specified by ASTM E-108. Natural gas was supplied to a slotted burner 
measuring 1/4" by 18" at the base of the deck at approximately 6 inches of 
water pressure while a 12 mile per hour wind was blowing across the deck. 
All decks tested were mounted at approximately a 30.degree. angle to the 
horizontal. 
Conventional organic based shingles will normally fail a Class A "burning 
brand" test at about 14 minutes and in the "spread of flame" test will 
normally show a spread of greater than 48" after 4 or 5 minutes. 
Conventional glass mat based shingles commonly pass the Class A "burning 
brand" test at 45 to 120 minutes and commonly give maximum flame spreads 
in the "spread of flame" test between 25 and 35 inches at 8 to 9 minutes 
of testing. Roll roofing made using either organic felt or glass mat will 
not pass Class A or B "burning brand" tests but is expected to pass Class 
C "burning brand" tests. Roofing products using felt of the invention 
provide results which are generally comparable with those obtained using 
conventional glass mat based materials but without the mechanical 
disadvantages associated with the glass mat based materials. 
Filled coating used in this example was filled with 52-63 wt % mineral 
filler and was based upon unfilled coating having a softening point of 
222-225.degree. F. Asphalt saturant used had a softening point of 
162.degree. F. except for the saturant used in Run 1 which had a softening 
point of 147.degree. F. and that used in runs 5 and 6 which had a 
softening point of 138.degree. F. 
Table I shows ingredients used and results obtained in "burning brand" and 
"spread of flame" tests for a number of different compositions of felt as 
well as shingle and rolled roofing product made from such felt in 
accordance with the invention. The results of "burning brand" and "spread 
of flame" tests on the felt and rolled roofing products are also set forth 
in Table I. 
TABLE I 
__________________________________________________________________________ 
Run No. 
1 2 3 4 5 6 
__________________________________________________________________________ 
Ingredients (as wt. %) 
chopped glass (70% 1/4", 30% 1/2") 
35 27 25 -- -- 
chopped glass (100% 1/4" 30% 1/2") 
-- -- -- -- 15 15 
cellulose (50% news print, 50% kraft) 
53 61 61 63 76 73 
Binder 
a. 100% SBR 12 -- -- -- 7 7 
b. 83% SBR, 17% acrylamide 
-- 12 -- -- 9 -- 
c. 58% SBR, 42% starch 
-- -- -- 12 -- 12 
d. 74% SBR, 26% starch 
-- -- 9.5 
-- -- -- 
Felt Converted to: Shingles Rolls 
Product Composition (lbs/100 sq. ft.) 
Felt 4.8 
4.7 
4.3 
5.3 
5.3 4.7 
Asphalt Saturant 7.0 
4.8 
5.4 
4.3 
7.3 5.1 
Filled Coating Face 
27.0 
29.0 
31.2 
33.4 
14.7 
17.4 
Back 9.0 
8.7 
6.4 
9.2 
8.5 8.2 
Granules (No. 11) Face 
38.2 
36.8 
38.0 
40.7 
29.2 
31.0 
Sand - Back 5.6 
4.1 
4.2 
4.3 
3.2 2.7 
Wt % Filler in Coating 
60 61 63 62 54 52 
Test Results 
Fire Test. Burning Brand (Mins) 
60 55 75 45 -- -- 
Pass/Fail Pass 
Fail 
Pass 
Pass 
Pass 
Pass 
Spread of Flame maximum spread (in) 
36 26 27 25 32 33 
at (min) 7 5.5 
6 6 6 6.5 
__________________________________________________________________________ 
EXAMPLE 2 
In order to illustrate the desirability of using both long and short glass 
fibers in felt of the invention, felt handsheets were made and tested in 
the laboratory as described immediately below. Ingredients used and test 
results were as shown in Table II. 
In making felt for this experiment the cellulosic fibers were blended and 
thoroughly dispersed in water. The glass fibers were then added and 
thoroughly dispersed. The latex binder was then mixed with the resulting 
slurry and subsequently precipitated with alum solution. The acrylamide 
resin binder and a flocculant were then added and the consistency adjusted 
as desired. Handsheets were then formed using a Williams mold. The formed 
sheets were then dried and tested for tensile strength and Elmendorf Tear 
with the results shown in Table II. 
TABLE II 
______________________________________ 
Handsheet No. 
1 2 
______________________________________ 
Ingredients (wt % dry basis) 
Waste Newsprint 26.75 26.75 
Waste Kraft Corrugated Paper 
26.75 26.75 
Glass Fibers - 1/4" M Filament 
35.00 30.00 
Glass Fibers - 1/2" M Filament 
-- 5.00 
SBR Latex 10.00 10.00 
Acrylamide Resin 1.50 1.50 
Physical Characteristics 
Tensile Strength (lb/in) 
36 40 
Elmendorf Tear (grams) 
352 432 
______________________________________ 
EXAMPLE 3 
To illustrate the desirability of using both long and short cellulosic 
fibers in felt of the invention for controlling porosity of the felt while 
maintaining optimum tensile and tear strength, felt handsheets were made 
as described in Example 2 using the ingredients shown in Table III and 
were tested with the results shown in Table III. 
TABLE III 
______________________________________ 
Handsheet No. 
3 4 5 
______________________________________ 
Ingredients (wt % dry basis) 
Waste Newsprint 29.25 -- 58.50 
Waste Kraft Corrugated Paper 
29.25 58.50 -- 
Glass Fibers - 1/4" K Filament 
30.00 30.00 30.00 
SBR Latex 9.60 9.60 9.60 
Acrylamide Resin 1.90 1.90 1.90 
Physical Characteristics 
Tensile Strength (lb/in) 
36 50 25 
Elmendorf Tear (gram) 
424 680 328 
% Kerosene Absorption 
157 176 148 
______________________________________ 
While the invention has been described above with respect to preferred 
embodiments thereof, it will be understood by those skilled in the art 
that various changes and modifications may be made without departing from 
the spirit or scope of the invention.