CA1110533A - Fiberglass strand reinforced mat - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A fiberglass mat high in tear resistance which consists of a base or sheet made of chopped glass fibers bonded together by a bonding agent and having embedded in said base random oriented fiberglass yarns or silvers which are in separated layers and are bonded in the base material, and in which the mat may also have a separate layer of longitudinal fiberglass yarns or slivers also bonded in the base material.

Description

:_L d o~ Invent.ion and E~rior ~rt Back~rountl of` the Invent:Lon 1.`hl.s :~nverltioll :relates t;o flberglass mats whlch ar~
ur:ua:Lly provicled :i.n sheet ~or~ and m~ be market;ed in a roll~
ur f`orrne~ irlt~.) desi.red shapesO The fîberlgass ma-ts on t;he market to-lay consi.st of a base of chopped glass ~lbe:rs of`
one~quarter to an inch and an inch and a quarter long and of cllameters which may range between nine and sixteen microns~
I'he chopped glass ~ibers are bonded together by a suitable bonding agen-t such as urea resins, phenolic resins~ bone glue, poly~inyl alcohols3 etc., pre~erably those of the type referred to which are water resistant. The glass ~ibers and the bonding ma-terial a.re usually provided in mat :~orm and are sent through an oven to cure the bonding agent.
There are ~wo methods of making ~lberglass mat, one is the dry method and the other is the wet method A In the dry method yarns have been placed in the center area of the mat or sheet to pro~ide -tear resistanceO Such an arrangement, howe~er 3 has the disadvantage o~ causing layering~ that is, a ~eparation o~ the mat into a plurality of sheets. This is caused because the central laye.r o~ yarns weakens the rnat in ~.
mechanical s~rength and destroys its homogenity~ thus causing or allowing easy separation of the mat into -two parts~
One o~ the basic weaknesses o~ a mat produced by the wet process ls its inherent lack o~ tear resistance ~rhich is very critical in United States products and applications o~
use Because of this inherent weakness the use of wet process fiberglass mats has been substan-tially restricted~

This inventlon provides a ~et process fiberglass mat whlch is higrl in tear resls-tance, thus maklng it sultable .tor many use.., irl many di.f`fererlt industries.
On~ sub3i;a.ntlal use o:~ -the ~I.berglass ma-t Or th:is :Lnvent:Lon wll:l.ch ls h.Lgh ln tear resL~tance~ in an~ cllrectlon~
is :ln the manu.~actllre of asphalt roofing~ :Ln which the ~iber~
g.~ass mat is sllbsti.tuted for the asphalt impregna-ted f`elted shaet now in common use. Such roofing made -~rom a fiberglass mat has many advantages such as being ~ireproo~, superior in quality and per~ormance, requiring the use o~ less asphalt than the s-tandard roofing, and~ o~ course, a sub~tantial savlngs in cost~
Another use for the mat of this invention is i~
connectlon with carpeting and flooring and also in plywood reinforcing where the mat in sheet form may be placed between layers o~ the plywood.
Other uses ~or this invention are for non-corrosive products3 battery separator mats, electrlcal laminates~ wood surfacing~ and in many other industriesJ
Brief Summary of the Invention It is the prime object of th~s invention to provide ~iberglass mats which have hi~h tear resistance in all directions~
It is also an object of this invention ~o provide a ma-t having high tear resistance in all dlrections and in which the mat has adequate mechanica~ strength throughout its en-tlre body of mixture of chopped glass and bonding agent so that the ma-t not only has adequate tear resistance but also has ~dequate mechanical strength at ~he central portion ~o that layering i5 el.iminated.
It is another ob~ect o.f this :invention to p.rovide a mat wh:l.ch has embodied thereln ~lass fiber yarns or ~llvers embedcled in the base of the mat ln ~eparate layer~
with ample ba~e ~aterial be-tween the layers to provide me~chanical s-trength at the central part of the mat, the ~arns bein~ arra.nged in a random oriented pattern, the yar}l~ or slivers being s-trong and hlghly resistant to tearing or severing and which provlde tear resistance in all directions throughout the entire mat.
It is also an object oP this lnvention to provide these tear xesistance yarns in patterns which may be of a partlcular desired size and shape~ such, for example~ as a uniform circular pattern in whi~h the circular portions ~oin each other and are of~set, and wnere overlapping occurs the portions of the yarn are bonded together.
It is a further ob~ect of this invention to provide a mat of the type referred to in the preceding objects in : -~hich there is a separate layer of longitudinal strands oi fiberglass e~bedded in the base3 which give extra strength and prevent ~Iripcording~
Other ob~ects and advantages o-~ this invent~on will be brought out during the course o~ the followlng detailed description of preferred forms of my invention~

~ _ =~
Fig~ 1 is a plan view partl~ sec-tloned in different planes o~ this invention employing the random oriented glass , tex~i.le yarns or s:L~vers~
Fig. 2 is a view s:Lmilar to Fi~r. 1 but showing ~heu~e of the long:t.~.udina:l strarlds of ~iberglass in combination with random orl~nted glass textile yarns;
Flg. 3 :Is a cross-sectional view -taken on the llne 3-3 of Flg. l;
Flg. 4 is a cross-se&tional view taken on the line of Flg. 2; ~nd Fig7 5 is a plan sectional view of the tear resis-tant yarns when arranged in a de~inite spiral or con~olutedpat-tern Detailed Description As shown in Fig. 1 and 3, thexe ls a mat or sheet or base 10 which is ~ormed of chopped glass ~ibers indicated b~ the n~eral 11, and is bonded together by a suitable bonding agent, The chopped glass ~ibers may be of a standard size and length as well as o~ a glass composition normally used in the chopped glass fibers in present day production.
The fibers may be o~ a suitable diameter such, ~or example, as within the range of the nine to sixteen microns and the fibers lengths may adhere to present standards o~ one-quarter to one and a quarter inches long~ Ho~rever, these lengths are not critical~ and~ therefore, need not be adhered to.
The bonding agents which may be employed in forming the mat or base are those commonl~ used in the industry today~
and would include urea resins~ phenolic resins, bone glue~
polyvinyl alcohol~ polyvinyl acetates and various coupling ~ 5 --5i33 and stabl.liz.i.ng agents~ It is preferable to use ~ bonding agent whi.ch :l.s wat,er res:;stant~
The numer.ll 12^-1.3 :LndLcates .random or:iented g,lass t;~xt:i.le ya:rn3 c)r slivers wh1.ch a.re po~:ltio~le~ wit,hln the llmits of the base in t~/Jo separate and sepa.rated layers with a volume O:r mat materlal of chopped gla~s~ ancl bondirlg agent positioned between the layers as indicated a-t 16, With the layers thus separated and with the volume of mat ma'erial between the layers there is n3 weakening of the central por-tion of the mat. The body o~ the mat will have adequate mechanlcal strength throughout and because of the skrengthen- :
ing of the central plane of the mat there will be no separa-t,lon of the mat body in~o a plurali~y of parts, These yarns and sllvers, or~ as generally called "strands of iberglass"
are not arra.nged according to a particular pattern~ but are arranged at random in successive circula-f or oval portions of diCferent sizes and radii. They cross, intersect, lnterlace and intertwine, Wherever the strands 12 or 13 of each separate layer cross themselves they are bonded toge-ther at those poillts which are indicated at 14 in Figs. 1 and 2 The strands 12 and 13 3xtend -throughou-t substantially the entîre area of the mat so that ~o portion of the mat is devoid of these tear resis~a~t elements or strands 12 and 13, Figs~ 2.and 4 illustra-te the use of parallel or longitudinal yarns, slivers or strands of fiberglass iden-tified by the numeral 15 in combin~t.ion with the random yarn layers 12 and 13. I-t will be not,ed that these longitudinal strands 15 are in a separate or third layer~ The ~4~

longltudinal strands 15 are subs-tantially straight. The layer o~ s-trand~ 15 is separated from the layer 13 by a volume of mat materlal 17 ln order to g:lve adeq~late mechanlcal s-trength to the mat body ln thls area~
I~ ^t;hrou~h a tearlng action a strand 12 ~ras torn loose a~d would -terlcl to be pullecl from the mat, which although hLghly unlikely~ it will be stopped because o~ the presence o~
the random orlented yarn 12 and 13 at ~he first bonding point 14 and thus prevent pulling loose of the entire strand and thus prevent ripcording.
In this form of thls lnventio~ showr in th~s appli-cation, the mat i5 thirty~six inches wide, the three parallel strands along each edge o~ the mat are three-fourths of an inch apaxt, and the other parallel strands are t~o inches apart plus or minus one-half inchO The random oriented strands are spaced on center lines three-fourths of an inch apart. By putting the garn in three separated layers the tear strength o~ the mat is enhanced because of the pluralit~ of bearing sur~aces. To tear the product across there are yarns at three di~fere~t levels rather ~han one level and this is found to resist the tear ~ar superior to that where a single layer of ;~
yarn is provided.
In the final product o~ this invention the percen-tages by wei~ht of material are ~ithin the order of 70~ chopped ~iberglass, 10~ strands 12 and 15, and 20~ bonding agent.
This invention is not limited to these percentages and obviously the~ may be changed as desired~ For example, it may be desirable in a certain form of the in~enti~n to have more th~n 10,~ of t;he strands 12, 13 or 15. Likewise, lt maybe desire(l to hElVe' -the ma-t; or base 10 -thicker, ln ~rhich event;
t;tle percerll;a~re ~,f ~lberglas3 and the percentage of bonding a~rent wo~lld be more than 707' and 20~ xespectivel~.
~ Fi~,~ 5 is a plan sectlonal vlew of my invention in which khe strands vf fiberglass 22 and 23 form a definite pat-tern o~ splral portions or convolutions offset from each oth~r bu-t connected together. In -this form of the invention~
like the prior formsg the yarns 22 and 23 are in two separate layers. In thls form, like all of the others, the la~ers of strands 22 and 23 are distributed over the en-tire area so tha-t each portion of the mat or base is tear resistant in all directions.

5~3 - ~:

SUPPLEMENTAR~ DISCLOSURE

A further modification of the present invention emphas:izes the construction of a mat of the type refered to before, in which there may be a separate layer of longi- `
tudinal strands of ~iberglass embedded in the base, which layer gives ex-tra strength to the mat to withstand tear:ing in a direction transverse to the major mat dimension. Such longitudinal strands may, in some applications at least, be substantially straight. This would be satisfactory, for example, when "ripcording" or "fishlining" (condition where straight line crack developes along the length of the mat) will not create any significant problem in the product to be produced from the mat. Alternatively, however, the longitudinal strands can be laid into the mat in such a manner that they resemble a sine wave extending from one end of the mat to the other.
Such a sinusoidal configuration produces two advantages. ~ny "hanging-up" of the strand on the spool will result in the application of a tension force to the strand which will disorient the chopped fibers only through a very short length of the mat, such as a few inches.
Further, such a disruption would be immedia~ely evident to the naked eye because the relatively consistent sinusoidal pattern of the strand would suddenly be disrupted by a straight portion a few inches long, Of course, depending upon the severity of the "hang-up" it is quite possible that the chopped fibers might not even be disoriented at all. Further, the elimination of the straight reinforcing strand has proven to be a significant factor in the production of higher strength roofing shingles, for example.

. . .

Those familiar with roofing shingles will realize that the exposed portion o:E the shingle is susceptible to repeated bend:ing by the wind, at lea.st until the bonding adhesive used to apply the shingle to a roof, becomes completely cured.
stra:Lght reinforcing strand in such a product may :Eorm a bend line or ripcord in the shingle which will result in a very rapid severing of the shingle along that natural bend line. Consequently, it can be seen that the sinusoidal con~lguration of the longitudinally oriented reinforcing strand can produce significant benefits over the substantially straight strand.

BRIEF DESCRIPTION OF ADDITIONAL DRA~INGS TO SUPPORT THE
FURTHER MODIFICATION OF THE INVENTION IS AS FOLLOWS:

Fig. 6 comprises a view of an alternate embodi-ment of the present invention, similar to Fig. 2, in which the longitudinal strands are laid in a generally sinusoidal orientation; and Fig. 7 comprises a plan view of a mat formed in accordance with the alternate embodiment of this invention, illustrating only the longitudinal strands.

DETAILED DESCRIPTION

For the purposes of this application, the term 'Ivertical'', as applied to the mat and its components, shall be considered to refer to mat thickness. On the other hand~
"horizontal" shall refer to the length/width of the mat.
Obviously, these terms do not define the orientation of the mat or any resulting product. Thus, Figure 1 is a multi-planar horizontal sectional view and Figure 3 is a vertical sectional view.

~`

~3 In the embodiment of the inven~ion illustrated in Figs. 6 and 7, those structural elements which are substan-tially identical to those in the above-described embodiments have been provided with similar re:Eerence numerals so that no further description thereof is necessary. As shown in Fig. 6, the s~ralght longitudinal strands 15 depicted in Fi~s. 2 and 4 have been replaced by longitudinal strands 31, such as are depicted in Figs. 6 and 7. Broadly speaking, the strands 31 are somewhat longer than is necessary to form a straight longitudinal strand, such as that at 15.
This is accomplished to set up the wavy pattern depicted which, for the sake of convenience, shall hereinafter be referred to as "sinusoidal". Those skilled in the art will realize, of course, that the longitudinal strands 31 could be employed without the random strands 12 and 13, with only one of the layers o~ random strands 12 and 13, or in a po-sition intermediate the random strands 12 and 13. In any event, the strands 31 are preferably within a single hori-zontal plane intermediate the upper and lower surfaces of the base 10, It has been found that the semi-straight or sinu-soidal longitudinal strands are advantageous for several reasons~ ~eferring to Fig. 2, it can be seen that any of the strands 15 cover only a very narrow area and any bending of the mat along the line parallel to the strands 15 will tend to use one of those strands as a bending line.
Consequently, any bending forces in that direc~ion are applied over a very narrow area, resulting in a relatively early failure of the product. For ex~mple, the substantially parallel strands 15 act as a ripcord at the junction of the ` :~

~ 5 ~ ~

main body of a finished shingle and its exposed edge portion.
When the shingle is exposed to wind, the wind will bend it back-and-orth about the straight strand until the exposed edge ls even~ually sealed down to the roof by its self-sealLng adhesive. Th:is problem often occurs ln products using ab-s~lutely parallel yarns and such shingle failure often occurs durlng Fall and Winter in northern climates since the adhesive does not have sufficient time to bond in the lower ambient temperatures and high winds.
On the other hand, if bending should occur along a line generally parallel to the longitudinal strands 31, any bend line which might be formed is several hundred times wider than that ~hich would be possible with the embodiment of Fig. 2. This eliminates the possibility of a ripcord effect, slnce there is so much more material to resist the bending and the ripcording.
This alternate embodiment also has additional advantages when "fishlining" occurs as the result of a hang-up in the strand material as it leaves the spool. When ~O an absoluteIy straight or parallel strand "hangs up", i. e., stops running momentarily for any number of reasons, it will disorient the chopped fibers located above and below it for some substantial length within the mat. This disorientation is not readily apparent and can later cause the mat product to crack or break apart along that line for a number of feet.
This failure often does not show up until the mat is within the finished product and is located, for example, on a roof.
Obviously, such a failure can be extremely costly since, at least, a large portion of the roofing material will have to be replaced.

~12--On the other hand~ when the semi-straight or sinusoidal strands hang-up or stop running momentarily, any major defect in the mat which might be caused by fishling, such as is shown at 33 in Fig. 7, can be easily detected by the naked eye. As a result, the defective por-tion o:E the mat can be cu-t away to eliminate the possibili-ty of hidden deEects gettinc3 into a :E:inished product..
Partly as the result of the use of sinusoidal reinforcing strands, and partly as the result of the distinct separation of the different reinforcing strand configurations into separate planes located between the top and bottom of the mat, products formed in accordance with the present invention have been found to be much stronger than those formed in accordance with the Hogendobler, et al, British Patent 746,021, dated March 7, 1956. In fact, recent testing of products produced according to these two processes over an extended period of time has disclosed that products formed in accordance with the present invention are far stronger than those formed in accordance with the Hogendobler patent.
By way of example, the following table sets forth the results of certain testing conducted upon the two types of mat products. A brief review of that table will indicate to those skilled in the art that mats formed in accordance with -the alternate embodiment of the present invention are signifi-cantly stronger than those formed in accordance with the Hogendobler, et al. patent.

Hogendobler, et al. Alternate Embodiment M Mat Product Mat Product Weight 1.85 lbs. per 1.85 lbs. per 100 ~t 2 100 ~t.2 Elmendorf Tear -Resistance 266 grams 466 grams Tensile Strength:
Machine Direction 58 lbs. per 3" 75~ lbs. per 3"
wid-th section width section Cross Machine 45 lbs. per 3" 72.4 lbs. per 3"
Direction width section width section _ 1i4_ .

Claims (2)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A fiberglass mat comprising:
a base formed of fiberglass fibers bonded together by a bonding agent; and a plurality of layers of fiberglass strands embedded in said base and bonded to said base, said strands being ar-ranged in a definite pattern of oval portions offset from each other and joining each other, and being bonded together wherever the strands of a separate layer cross themselves, there being a volume of mat material formed of glass fibers bonded together by a bonding agent positioned between the layers of strands, thus providing mechanical strength at the intermediate portion of said mat between said layers of strands.

2. A fiberglass mat comprising:
a base formed of glass fibers bonded together by a bonding agent;
a plurality of separate layers of random oriented fiberglass strands embodied in said base and oriented fiberglass strands embodied in said base and bonded thereto, said random oriented strands being bonded to themselves at spaced locations, there being a volume of mat material formed of glass fibers bonded together by a bonding agent positioned between the layers of strands, thus providing mechanical strength at the intermediate portion of said mat between said layers of strands, and the random oriented fiberglass strands being formed as oval portions offset from each other yet joined together and which are of different sizes which intertwine and intersect at differ-ent portions, and in which wherever there is a crossing or inter-secting of portions of one of said strands, the strands are bonded together at these separate points.