U.S. patent application number 11/176602 was filed with the patent office on 2007-01-11 for method for producing a wet-laid fiber mat.
Invention is credited to Gregory S. Helwig, Jerry H.C. Lee.
Application Number | 20070006775 11/176602 |
Document ID | / |
Family ID | 37617136 |
Filed Date | 2007-01-11 |
United States Patent
Application |
20070006775 |
Kind Code |
A1 |
Helwig; Gregory S. ; et
al. |
January 11, 2007 |
Method for producing a wet-laid fiber mat
Abstract
A method is provided for forming a wet-laid nonwoven glass fiber
mat comprised of a plurality of bundles of fibers. The method
includes the steps of adding chopped fibers to an aqueous slurry
containing a sufficient amount of a suitable hydrophobic agent to
cause the fibers to form a plurality of bundles. The fibers are
then formed into a mat which may be used in a number of
reinforcement applications. A method is also provided for modifying
the components in the water slurry to produce mats comprising
either bundles of fibers or dispersed fibers.
Inventors: |
Helwig; Gregory S.;
(Granville, OH) ; Lee; Jerry H.C.; (Columbus,
OH) |
Correspondence
Address: |
OWENS CORNING
2790 COLUMBUS ROAD
GRANVILLE
OH
43023
US
|
Family ID: |
37617136 |
Appl. No.: |
11/176602 |
Filed: |
July 7, 2005 |
Current U.S.
Class: |
106/287.1 ;
106/287.25; 106/287.3; 162/156; 162/158; 162/179; 252/8.83 |
Current CPC
Class: |
D21H 13/40 20130101;
C03C 25/26 20130101 |
Class at
Publication: |
106/287.1 ;
162/156; 162/179; 162/158; 106/287.3; 106/287.25; 252/008.83 |
International
Class: |
D06M 15/333 20060101
D06M015/333 |
Claims
1. A method for forming a wet-laid glass fiber mat comprising:
preparing glass fibers, the glass fibers being coated with a size
composition having a bundling agent; mixing the glass fibers into
an aqueous slurry composition to form a fiber slurry in which the
fibers tend to form bundles of at least about 50 fibers; applying
the fiber slurry to a porous conveyor; dewatering the fiber slurry
to form a fiber web composed primarily of fiber bundles; applying a
binder composition to the fiber web to form a treated fiber web;
and curing the treated fiber web to form a fiber mat.
2. The method for forming a wet-laid glass fiber mat according to
claim 1, wherein: the slurry composition includes a cationic
surfactant and a viscosity modifier.
3. The method for forming a wet-laid glass fiber mat according to
claim 1, wherein: the bundling agent is prepared from a condensate
of a polyunsaturated fatty acid and an amine.
4. The method for forming a wet-laid glass fiber mat according to
claim 1, wherein: the bundling agent is an acetate prepared from a
condensate of a polyunsaturated fatty acid and an amine.
5. The method for forming a wet-laid glass fiber mat according to
claim 4, wherein: the amine is present in a ratio of between about
1:1 and about 3:1 relative to the polyunsaturated fatty acid.
6. The method for forming a wet-laid glass fiber mat according to
claim 5, wherein: the bundling agent is an acetate salt of a
condensate of linoleic acid and tetraethylenepentamine.
7. The method for forming a wet-laid glass fiber mat according to
claim 6, wherein: the linoleic acid and the tetraethylenepentamine
are present in the condensate at a ratio of about 2:1.
8. An aqueous size composition for treating mineral fibers
comprising: a silane cross-linking agent; and a bundling agent
comprising condensate of a polyunsaturated fatty acid and an
amine.
9. The aqueous size composition according to claim 8, wherein: the
composition includes a cationic surfactant and a viscosity
modifier.
10. The aqueous size composition according to claim 8, wherein: the
bundling agent is an acetate prepared from a condensate of a
polyunsaturated fatty acid and an amine.
11. The aqueous size composition according to claim 8, wherein: the
amine is present in a ratio of between about 1:1 and about 3:1
relative to the polyunsaturated fatty acid.
12. The aqueous size composition according to claim 11, wherein:
the bundling agent is an acetate salt of a condensate of linoleic
acid and tetraethylenepentamine.
13. The aqueous size composition according to claim 12, wherein:
the linoleic acid and the tetraethylenepentamine are present in the
condensate at a ratio of about 2:1.
14. A method of synthesizing a bundling agent comprising: charging
a vessel with an unsaturated fatty acid; heating the unsaturated
fatty acid to form a melt, the unsaturated fatty acid exhibiting an
initial degree of unsaturation; adding an amine with the melt to
form a reaction mixture; heating the reaction mixture to distill
lighter components and produce a distillate, wherein the reaction
mixture; cooling the reaction mixture; treating the reaction
mixture to form a treated reaction mixture; and solidifying the
treated reaction mixture to obtain the bundling agent, wherein the
bundling agent maintains at least about 90% of the original
unsaturation.
15. The method of synthesizing a bundling agent according to claim
14, wherein: agitating the melt while the melt is being maintained
under a nitrogen blanket; and removing the nitrogen blanket and
applying a low nitrogen sparge until production of the distillate
is substantially complete and the reaction mixture temperature
approaches 480.degree. F. (249.degree. C.); and and cooling the
reaction mixture temperature.
16. The method of synthesizing a bundling agent according to claim
14, wherein: the unsaturated fatty acid includes a major portion of
linoleic acid; and the amine is a multifunctional amine.
17. The method of synthesizing a bundling agent according to claim
14, wherein: the amine is chosen from alkylenepolyamines, amines
represented by the formula H.sub.2N((CH.sub.2).sub.yNH).sub.x--H in
which x is one or more and y is an integer having a value of 4 to
10. Typical amines of this class are the alkylenediamines such as
1,6-diamino-3-methyl-n-hexane; 1,3-propylenediamine
1,4-diamino-n-butane; 1,6-diamine-n-hexane, 1,10-diamino-n-decane
and polyalkylenepolyamines such as diethylenetriamine,
triethylenetetramine, tetraethylenepentamine,
polypropylenepolyamines and polybutylenepolyamines.
18. The method of synthesizing a bundling agent according to claim
14, wherein: the amine is chosen from tetraethylenepentamine,
polypropylenepolyamines and polybutylenepolyamines.
19. The method of synthesizing a bundling agent according to claim
14, wherein: the amine is tetraethylenepentamine.
20. A wet-laid glass fiber mat comprising: mineral fibers
comprising a silane cross-linking agent and a bundling agent
comprising condensate of a polyunsaturated fatty acid and an
amine.
21. The wet-laid glass fiber mat of claim 20, wherein said mineral
fibers further comprise a cationic surfactant and a viscosity
modifier.
22. The wet-laid glass fiber mat of claim 20, wherein said bundling
agent is an acetate prepared from a condensate of a polyunsaturated
fatty acid and an amine.
23. The wet-laid glass fiber mat of claim 20, wherein said amine is
present in a ratio of between about 1:1 and about 3:1 relative to
the polyunsaturated fatty acid.
24. The wet-laid glass fiber mat of claim 23, wherein said bundling
agent is an acetate salt of a condensate of linoleic acid and
tetraethylenepentamine.
Description
TECHNICAL FIELD AND INDUSTRIAL APPLICABILITY
[0001] The present invention relates to a process for producing a
non-woven fiber mat, and more particularly, to a wet-laid process
for forming a glass fiber mat comprised of small bundles of glass
fibers.
BACKGROUND OF THE INVENTION
[0002] Two main techniques utilized for producing glass fiber mats
are wet-laid processing and dry-laid processing. Typically, in a
wet-laid process, an aqueous slurry containing dispersed fibers and
a variety of other components such as surfactants, viscosity
modifiers, defoaming agents, or other chemical agents is prepared
and sufficiently agitated to disperse the fibers throughout the
slurry composition. The aqueous slurry is then deposited onto a
moving screen, chain or fabric that retains the majority of the
fibers while allowing a substantial portion of the water to be
removed and thereby form a fiber web supported by the upper
surfaces of the screen.
[0003] A binder composition may then be applied to the fiber web
and the resulting mat is then typically dried at a temperature
sufficient to remove the remaining water and to cure the binder.
The resulting non-woven mat consists of an assembly of dispersed,
individual glass filaments. Wet-laid processes are preferred in
applications where a very uniform distribution of fibers in the
non-woven mat is desired.
[0004] Conversely, a typical dry-laid process tends to produce mats
in which the fibers are grouped into bundles (i.e., multiple fibers
generally adjacent one another and arranged in a substantially
parallel relationship). In a conventional dry-laid process, the
fibers are chopped and blown onto a conveyor to form a dry web to
which a binder is then applied to form the mat. Dry-laid processes
tend to be favored in instances in which a more open structure is
desired in the resulting mat that will allow, for example, more
rapid penetration of viscous liquids or resins, and in instances in
which it may be desierable to reduce the volume of the glass
fibers.
[0005] However, conventional dry-laid processes tend to produce
mats are of a less uniform weight when compared with mats produced
by a wet-laid process, i.e., different areas of the mats have
different weights and/or fiber densities. This variation in mat
weight can be exacerbated during the production of lightweight
mats, e.g., mats having a basis weight of 300 g/m.sup.2 or less. At
lower basis weights below about 300 g/m.sup.2, the relatively poor
small-scale weight uniformity of the air-laid process mat becomes
increasingly apparent in terms of uneven distribution of the
fibers. As a result, machine productivity is also sacrificed
because the conveyor speed cannot be increased in proportion to the
reduction in bias weight of the mat without further degrading the
uniformity.
[0006] In addition, processes utilizing dry-chopped input fibers
tend to be more expensive than those utilizing wet-chopped input
fibers because the fibers in a dry-laid process are dried and
packaged in separate steps before being chopped offline, while size
can be applied directly to the manufactured fibers shortly before
they are chopped to form the chopped fibers that will be added to
the aqueous slurry.
[0007] For certain reinforcement applications useful during the
formation of molded parts using polymer resins, it would be
desirable to form fiber mats in which the mat comprises bundles of
fibers (similar to the bundling achieved during a dry-laid process)
and yet has a generally uniform weight (similar to that achieved
during a wet-laid process).
[0008] Various wet-laid processes have been proposed for producing
fiber mats that exhibited increased levels of bundling of the
fibers. One such process is described in U.S. Pat. No. 4,242,404 to
Bondoc in which bundles or "strings" of fibers are formed along
with individual fibers. Another such process is described in U.S.
Pat. No. 4,112,174 to Hanne in which a mat comprising individual
glass fibers and glass fibers bundles is formed with the bundles
being held together with a water insoluble binder.
[0009] However, because such mats still include a number of
dispersed fibers in addition to the fiber bundles, they have proven
generally unsuitable for applications in which higher porosities
are desired or necessary. Further, it has been noted that the
process disclosed by Bondoc tends to produce bundles of relatively
long fibers. This result is particularly undesirable in
reinforcement applications because the longer fibers tend to be
visible in the final molded product and detract from the product's
appearance.
[0010] Another solution was disclosed in U.S. Pat. No. 6,054,022 to
Helwig et al. in which a chopped strand mat was manufactured using
a wet-laid process with wet use chopped strands (WUCS) as the fiber
input. Although a conventional WUCS fiber was used, but a
hydrophobic agent, such as an ethylene oxide/propylene oxide block
copolymer was added to the aqueous slurry composition, i.e., the
"white" water system to cause the dispersed WUCS fibers to
self-assemble into small bundles. These small bundles were then
maintained throughout the forming process and were present in the
final product. Although this method improved the uniformity and
porosity of the resulting fiber mat, it was difficult to control on
a commercial scale and the addition of the hydrophobic agent was
associated with certain negative effects on subsequent
products.
[0011] Accordingly, a need remains for an economically competitive
process capable of producing lightweight glass fiber mats which are
both relatively uniform in weight and are comprised of primarily of
bundles of relatively short fibers and which exhibits an open,
porous structure suitable for and compatible with use in the
production of reinforced molded parts with highly viscous resin
compositions.
SUMMARY OF THE INVENTION
[0012] The present invention provides an economically competitive
process capable of producing lightweight glass fiber mats which are
both relatively uniform in weight and are comprised of primarily of
bundles of relatively short fibers and which exhibits an open,
porous structure suitable for and compatible with use in the
production of reinforced molded parts with highly viscous resin
compositions. The present process provides a wet-laid glass fiber
mat utilizing a conventional aqueous slurry composition, thereby
avoiding the difficulties associated with the inclusion of the
hydrophobic agent, while still promoting the organization of the
fibers into discrete bundles of closely associated multiple fibers
arranged in a substantially parallel relationship. The resulting
mat may comprise small or large bundles of fibers, is of a
substantially uniform weight, and has a generally porous
structure.
[0013] In particular, the process according to the present
invention uses WUCS that have been treated with a modified size
composition that promotes the formation of the fiber bundles within
the slurry without the difficulties associated with adding a
hydrophobic agent directly to the slurry composition. Then, as in
the conventional processes, the slurry will be applied to a
supporting and porous conveyor through which the majority of the
water will be removed to form a fiber web. The fiber web will then
typically be transferred to another downstream conveyor for
application of a binder composition, after which it will be dried
and the binder cured to form the finished fiber mat product.
[0014] The resulting non-woven glass fiber mat comprises bundles of
chopped fibers. The disclosed process may be used with a range of
chopped fiber products, but it is expected that wet-chopped fibers
having a length of from about 3 mm to about 50 mm, or, more
typically, from about 25 mm to about 50 mm will be suitable for
most applications. The fiber bundles formed in the resulting mat
may include between about 50 and about 500 fibers, depending on
both the size composition, the slurry composition and the slurry
processing prior to deposition on the conveyor. For purposes of the
present invention, bundles comprising between about 50 and 100
individual fibers will be referred to as small bundles while
bundles comprising between about 300 and about 500 individual
fibers will be referred to as large bundles, with intermediate
bundles having between about 100 and about 300 individual
fibers.
[0015] The non-woven glass fiber mat preferably has a basis weight
of from about 40 to about 500 g/m.sup.2, and more preferably, from
about 60 to about 300 g/m.sup.2. The thickness of the fiber mat is
typically thinner than wet-laid mats comprised of a corresponding
weight of dispersed fibers, but will tend to vary somewhat
depending on the average bundle size and bundle size distribution.
For example, smaller bundles tend to produce thicker mats while
larger bundles tend to produce thinner mats.
[0016] The method of the present invention provides an advantage
over prior processes in that the size composition used to treat the
chopped fibers prior to their distribution in the aqueous slurry
which tends to cause or promote bundle formation within the slurry
may be easily modified to form mats comprising primarily dispersed
fibers (i.e., having substantially no fiber bundles). This can be
done without having to drain the aqueous slurry from the machine or
mixing tank in which the fibers are processed, which results in a
substantial savings in time and cost.
[0017] For example, a method according to another exemplary
embodiment of the invention, incorporates a step of modifying the
components of the aqueous size composition used to prepare the
chopped fibers. A wet-laid fiber mat is then prepared as described
above by preparing and dispensing a slurry incorporating the
chopped fibers treated with the modified size composition to form a
fiber web, applying a binder composition to the web and curing a
binder to form a fiber mat product in which the majority of the
fibers are present as associated bundles rather than individual
fibers.
[0018] When the formation of mats with bundled fibers is no longer
desired, the method may include the step of increasing the amount
of a surfactant or introducing a different surfactant package to
the existing slurry sufficient to counteract, at least partially,
the bundling of the fibers induced by the size composition. A mat
comprising primarily dispersed fibers may then be produced by
removing water from the fibers to form a web and applying a
binder.
[0019] When the formation of mats with bundled fibers is no longer
desired, the method may include the step of modifying the size
composition that is being applied to the fibers before chopping to
reduce or suppress the tendency of the fibers to form bundles in
the slurry. A mat comprising primarily dispersed fibers may then be
produced by removing water from the fibers to form a web and
applying a binder.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0020] The process of the present invention provides many
advantages over prior art mats which are formed by a dry-laid
process. The wet-laid process of the present invention provides a
highly porous, thin, non-woven glass fiber mat which has greater
uniformity of fiber distribution than mats produced in dry-laid
processes. Further, the mat of the present invention can be
produced at lower cost because it uses low-cost wet chopped fibers
which are formed into bundles by altering the components of the
slurry used in a normal wet-laid process. In addition, the slurry
components may be modified so as to produce mats comprising either
bundles of fibers or dispersed fibers without having to replace the
entire slurry.
[0021] The wet-laid mat of the present invention may be processed
with the use of papermaking-type machines such as Fourdrinier, wire
cylinder, Stevens Former, Roto Former, Inver Former and Venti
Former machines. The general procedure for preparing the glass
fiber mat of the present invention is to form an aqueous slurry
which may further contain a surfactant, a viscosity modifier and a
complexing agent. The amount of water in the slurry may vary
depending on the size of the equipment used. Typical volumes of
water may range from 40,000 to 80,000 liters. Wet chopped fibers
treated with a size composition according to the invention are
added to the slurry, typically at a concentration between about 0.2
wt % and about 1 wt % of the slurry, agitated to form a thick
stock. During this agitation, the fibers begin to form bundles.
[0022] The aqueous slurry will typically include at least one
surfactant, usually a cationic surfactant, that may be maintained
within the slurry at a concentration of between about 30 to about
200 ppm. The surfactant functions to lubricate the fibers and aid
in dispersion of the fibers as they are initially placed in the
slurry. The aqueous slurry will also typically include at least one
viscosity modifier, such as hydroxyethyl cellulose, that may be
maintained within the slurry at a concentration of about 2000 ppm.
The viscosity modifier is utilized to increase the viscosity of the
aqueous slurry to a level that facilitates agitation and improve
control of water drainage as water is removed through the conveyor
from the fiber web. The aqueous slurry may also include a
complexing agent, such as a polycarboxylate salt at a concentration
of between about 20 to about 100 ppm, that will function to tie up
the surfactant, thus aiding in fiber bundle formation.
[0023] In the present method, however, no separate hydrophobic
agent is added to the aqueous slurry composition. Many of the size
compositions utilized in the production of WUCS contain a cationic
surfactant that acts as the primary dispersant and causes the
bundles of chopped fibers to filamentize as they are introduced
into the white water. One such cationic surfactant is K-12, an
acetate salt of a 2:1 condensate of stearic acid and
tetraethylenepentamine. An exemplary size composition A includes
the ingredients listed below in TABLE 1. TABLE-US-00001 TABLE 1
Size Composition A % by % Active % by wt. Weight Weight Material
Solids (as received) Solids (g) Nalco 7530 25.5% 0.048% 0.0122%
3.60 K-12 premix 8.8% 1.014% 0.0892% 76.05 Y-9669 silane 100.0%
0.023% 0.0225% 1.69 A-1100 silane 58.0% 0.079% 0.0459% 5.94 PVAl
premix 24.6% 1.952% 0.4801% 146.42 Acetic Acid 0.076% 5.70 Water
96.808% 7260.60 100.000% 0.6500% 7500.00
[0024] With regard to the size components listed in TABLE 1 above,
and TABLES 2 and 3 below, the Nalco 7530 is a high molecular weight
acrylamide copolymer prepared in water and hydrocarbon that is
often used as a flocculant that is being used primarily as a
viscosity (or rheology) modifier to increase size viscosity and
thereby enhance the degree of size coating on the glass during the
fiberizing operation. The PVA1 premix is polyvinyl alcohol
dissolved in water and prepared to have a 25% solids content that
is included primarily as a film former for bundling the fibers and
enhancing the strand chopping operation. The specific polyvinyl
alcohol used in formulating the PVA1 premix was CELVOL 205, a low
molecular weight, partially hydrolyzed (87.0-89.0% hydrolysis),
polyvinyl alcohol.
[0025] When a conventional size composition such as size
composition A is used to prepare WUCS, as the WUCS are added to a
conventional agitated white water system, the bundles of fibers
undergo substantially complete filamentization, i.e., are dispersed
throughout the slurry as individual fibers. The size compositions
according to the present invention, however, replace at least a
portion of the cationic surfactant of the conventional size
composition with a bundling agent, such as a 2:1 condensate of
EMERSOL 315 linoleic acid and tetraethylenepentamine. This bundling
agent can be prepared in much the same manner as the cationic
surfactant, such as K-12, that it is replacing. An emulsion of the
acetate salt of this condensate was prepared and then utilized in
the preparation of an exemplary size formulation B having the
overall composition reflected below in TABLE 2: TABLE-US-00002
TABLE 2 Size Composition B % by % Active % by wt. Weight Weight
Material Solids (as received) Solids (g) Nalco 7530 25.5% 0.048%
0.0122% 3.60 Linoleic/TEPA/HOAc 7.5% 1.790% 0.0892% 134.28 RC-1
silane 98.0% 0.035% 0.0225% 2.59 A-1100 silane 58.0% 0.079% 0.0459%
5.94 PVAl premix 24.6% 1.952% 0.4801% 146.42 Acetic Acid 0.076%
5.70 Water 96.020% 7201.47 100.00% 0.7063% 7500.00
[0026] Another exemplary size composition according to the present
invention, replaces at least a portion of the cationic surfactant
of the conventional size composition with a bundling agent, such as
a 2:1 condensate of EMERSOL 213 oleic acid and
tetraethylenepentamine. An emulsion of the acetate salt of this
condensate was prepared and then utilized in the preparation of an
exemplary size formulation C having the overall composition
reflected below in TABLE 3: TABLE-US-00003 TABLE 3 Size Composition
C % by % Active % by wt. Weight Weight Material Solids (as
received) Solids (g) Nalco 7530 25.5% 0.048% 0.0122% 3.60
Oleic/TEPA/HOAc 7.5% 1.790% 0.0892% 134.28 RC-1 silane 98.0% 0.035%
0.0225% 2.59 A-1100 silane 58.0% 0.079% 0.0459% 5.94 PVAl premix
24.6% 1.952% 0.4801% 146.42 Acetic Acid 0.076% 5.70 Water 96.020%
7201.47 100.00% 0.7063% 7500.00
Synthesis of Conventional Surfactant (LUBESIZE K-12)
[0027] LUBESIZE K-12 is a cationic surfactant that is an adduct of
tetraethylenepentamine (TEPA) and stearic acid that is used in
preparing the comparative size composition reflected above in TABLE
1. It has no degree of unsaturation. The ingredients used to
synthesize LUBESIZE K-12 are set forth below in TABLE 4.
TABLE-US-00004 TABLE 4 Ingredient Weight (g) % of Total Stearic
Acid 125.00 63.98 Tetraethylepetamine 46.75 23.93 (TEPA) Acetic
Acid 23.62 12.09 Total 195.37 100.00
[0028] The stearic acid, also referred to as octadecanoic acid, was
placed in a processing vessel and melted at about 200.degree. F.
(93.3.degree. C.) under a light nitrogen blanket. Once all of the
stearic acid was melted, ##STR1## the melt was agitated while
maintaining the nitrogen blanket with the temperature of the melt
being maintained at about 200.degree. F. while the
tetraethylenepentamine (TEPA) was ##STR2## slowly added to the
stearic acid melt to form the reaction mixture. Because the
reaction is exothermic, the temperature of the reaction mixture
will typically exceed 200.degree. F. even without supplemental
heating applied during the addition of the TEPA. However, after an
exotherm peak is reached and the temperature of the reaction
mixture begins to decrease, supplemental heating may be resumed to
maintain the reaction mixture at or above 200.degree. F.
[0029] Once all of the TEPA was added, the temperature of the
reaction mixture was increased quickly, but at a rate that did not
produce excessive foaming. When the reaction mixture temperature
reached about 380.degree. F. (193.30.degree. C.), it was determined
that approximately 50% of the distillate had been removed. The
nitrogen blanket was then removed, a low nitrogen sparge was
applied and the heating continued until the distillate flow stopped
as the reaction mixture temperature approached 480.degree. F.
(249.degree. C.).
[0030] Once the evolution of distillate was substantially complete,
the reaction mixture was cooled to a temperature of approximately
160-170.degree. F. (71.1-76.7.degree. C.). The total distillate
removed from the combined stearic acid and TEPA reaction mixture
was determined to be approximately 12% by weight of the initial
reaction mixture. The acetic acid was then slowly added (over a
period of approximately 15 minutes) to the reaction mixture, which
resulted in a slight exotherm of approximately 10.degree. F. (about
4.5.degree. C.) was noted as the acetic acid was added. After all
of the acetic acid was added, the mixture was agitated for
approximately 10 minutes and then poured onto release paper where
it was permitted to cool and solidify.
[0031] The synthesized product, at 1% by weight in water, and was
slightly acidic, having a pH in the range of about 4.5-5.0, and,
prior to acid neutralization, exhibited a residual acid value of
about 0.4% and an essentially non-detectable iodine value. The
iodine value, also referred to as the iodine number, is a relative
measure of the degree of unsaturation of an oil, fat, or wax. Fully
saturated oils, fats, and waxes take up no iodine, resulting in an
iodine value of zero, but partially saturated and unsaturated oils,
fats, and waxes will take up varying quantities of iodine. The
solidified product was determined to be the compound also
identified as Lubesize K-12.
Synthesis of an Exemplary Bundling Agent A
[0032] The synthesis procedure as set forth above with respect to
the LUBESIZE K-12 was repeated, but with the substitution of an
equivalent molar basis of linoleic acid, a polyunsaturated fatty
acid also referred to as 9,12-octadecadienoic acid, for the stearic
acid. The linoleic acid used was EMERSOL 315 linoleic acid
commercially available from Cognis Corp. ##STR3##
[0033] Prior to acid neutralization, the synthesized product
exhibited a residual acid value of 0.29% and an iodine value of
24.8. Given that the iodine value of the EMERSOL 315 linoleic acid
used in this synthesis was 27.4, it was determined that over 90% of
the original unsaturation in the fatty acid was maintained in the
synthesized product. The synthesized product also includes a
conjugated diene structure. As reflected above, this bundling agent
was then utilized in preparing size composition B.
Synthesis of Bundling Agent B
[0034] The synthesis procedure as set forth above with respect to
the LUBESIZE K-12 was repeated, but with the substitution of an
equivalent molar basis of oleic acid for the stearic acid. The
oleic acid, a monounsaturated fatty acid also referred to as
9-octadecenoic acid, used was Emersol 213 oleic acid from Cognis
Corp. ##STR4##
[0035] Prior to acid neutralization, the synthesized product
exhibited a residual acid value of about 0. 18% and an iodine value
of 21.8. Given that the iodine value of Emerson 213 oleic acid was
24.3, it was determined that again approximately 90% of the
unsaturation in the fatty acid was maintained in the synthesized
product. As reflected above, this bundling agent was then utilized
in preparing size composition C.
Composition Ranges for Size Compositions A, B and C
[0036] Ranges for the various components in the size compositions
A, B and C are listed in TABLE 5. TABLE-US-00005 TABLE 5 Material
Range 1 (*), % Range 2 (*), % Nalco 7530 about 0.005 to about 0.100
about 0.01 to aobut 0.04 Cationic about 0.020 to about 0.500 about
0.05 to about 0.20 surfactant (+) Y-9669 silane about 0.005 to
about 0.100 about 0.01 to about 0.06 A-1100 silane about 0.010 to
about 0.300 about 0.02 to about 0.15 PVAI about 0.400 to about
0.900 about 0.60 to about 0.80 (*) Based on total solids content of
the size (+) Including K-12, linoleic/TEPA/HOAc, and
oleic/TEPA/HOAc shown in size compositions A, B, and C
respectively
Evaluation of Comparative and Exemplary Examples
[0037] Conventional size composition A, the exemplary size
composition B, and a second comparative size composition C as
detailed above, were separately applied to 16 .mu.m glass fiber in
the forming room, after which the sized fibers were chopped,
inline, to an average length of about 25 mm, to prepare chopped
fiber. When this chopped fiber was run on a wet-laid process pilot
line using substantially identical slurry composition and formation
conditions, the chopped fiber treated with exemplary size
composition B yielded a fiber mat composed almost entirely of small
bundles of fibers. Compared to the corresponding fiber mat prepared
with the conventional size composition A and comparative size
composition C, fiber mats prepared with exemplary size composition
B having similar basis weights exhibit both reduced thickness and
increased porosity when manufactured under substantially identical
process conditions.
[0038] Representative fiber mats were prepared using size
compositions A-C as detailed above. The resulting fiber mats were
then tested to determine Basis Weight (lbs/ft.sup.2),
Loss-On-Ignition (LOI) as a percent of the weight of the initial
fiber mat, air permeability (ft.sup.3/min/ft.sup.2); and thickness
(inches). The results of this evaluation for mats having similar
basis weight are reflected below in TABLE 6. TABLE-US-00006 TABLE 6
Basis Fiber Weight LOI Air Permeability.sup.1 Caliper.sup.2 Mat
(lbs/f.sup.2) (%) (ft.sup.3/min/ft.sup.2) (in) 1 1.79 17.7 887.2
0.024 2 1.80 6.9 1079.5 0.016 3 1.79 17.9 866.1 0.024 .sup.1The
ASTM D737 procedure was adopted for measuring the air permeability.
.sup.2The ASTM D1777 procedure was adopted for measuring the
caliper.
[0039] As reflected above, the data shows that the fiber mat
manufactured with exemplary size composition 2, which was formed
from the chopped fibers treated with siz composition B, exhibited
both lower LOI (% binder weight in mat) and caliper (mat thickness)
numbers. Comparing the control mats 1 and 3 with the exemplary mat
2, reveals that conventional wisdom regarding the formation of
fiber mat products allows room for improvement, particularly with
regard to porosity (as reflected in the air permeability values)
and thickness. Similarly, comparing control mats 1 and 3, the
similarity in their properties, with the air permeability for the
mat C sample (oleic acid synthesis) was about the same as the
control mat (LUBESIZE K-12), while the exemplary mat, mat 2,
indicates an improvement in both the porosity and thickness.
[0040] The data also illustrates that a bundling agent in a size
formulation that includes a diene structure, size B, to produce
bundled fibers yields a mat having increased porosity and reduced
thickness.
[0041] As will be appreciated by those skilled in the art, the
intended use for the resulting fiber mat will tend to guide the
selection of an appropriate binder composition, fiber mat
properties and/or manufacturing techniques. For example, if the
fiber mat is intended for use in a roofing mat, a urea-formaldehyde
resin binder may be utilized to improve compatibility of the mat
with the asphalt composition. As will be appreciated by those of
ordinary skill in the art, any suitable binder and/or binder
application process may be utilized to convert the fiber web to a
desired fiber mat product.
[0042] In addition to binder compositions applied to the fiber mat
as a solution, slurry or emulsion, the aqueous slurry, and
consequently the fiber mat, may incorporate one or more varieties
of thermoplastic binder fibers. Depending on the binder fiber(s)
selected, the addition of the binder fibers may tend to increase
the strength of the wet fiber web, facilitating the transfer of the
web between the forming section and the saturator section of the
production line or during other subsequent handling and/or transfer
operations.
[0043] The binder fibers could include bicomponent binder fibers,
in which the fiber structure of the binder would generally be
preserved in the final product, and/or homofil binder fiber(s)
having a composition that allows essentially the entire fiber, when
exposed to the "curing" conditions, to melt and form "weld points"
at the points in the fiber web where two or more glass bundles are
in direct contact or are only slightly separated. The bicomponent
binder fibers will typically provide a softer hand and better
conformability while the homofil binder fibers will tend to
increase the relative porosity of the fiber mat, a property that
may be especially desirable when the resulting fiber mat is
intended for a process involving impregnation of the mat with one
or more high-viscosity resins.
[0044] Conventional fiber mat production techniques may be utilized
for forming a fiber mat from the slurry prepared in accord with the
present invention. After preparing the slurry, the fiber-containing
slurry will typically be passed to a head box from which the slurry
is deposited onto a moving wire screen or other suitable
conveyor.
[0045] Suction or vacuum is typically provided on the backside of
the conveyor to aid in the dewatering of the deposited slurry and
form a fiber web comprising bundles of fibers. The fiber web is
then coated with a binder composition, in the absence of or in
addition to the inclusion of binder fibers in the fiber web, using
any suitable means and then passed through a drying oven which
dries the fiber mat and cures the binder and/or activates the
binder fiber(s).
[0046] One suitable binder is an emulsion of a copolymer of
ethylene and vinyl acetate. However, as noted above, it will be
appreciated by those of ordinary skill in the art that the choice
of binder will depend on the intended end use for the fiber mat
product. Any binder which is suitable for use in a wet-formed mat
operation may be used in the present invention.
[0047] In embodiments in which the slurry contains a surfactant, a
preferred cationic surfactant is AEROSOL C-61, available from Cytec
Industries. In such embodiments, the surfactant may be used in
combination with a complexing agent, such as a polycarboxylate
salt, for example DISPEX N40V available from Allied Colloids, that
will tend to form a complex with at least a portion of the
surfactant to temper the action of the surfactant and promote the
formation of the fiber bundles.
[0048] In embodiments where the slurry contains a viscosity
modifier for the purpose of regulating the slurry viscosity,
suitable viscosity modifiers include hydroxyethyl cellulose,
anionic polyacrylamide, and polyethylene oxide. A preferred
viscosity modifier is NATROSOL 250 HHBR (hydroxyethyl cellulose)
available from Aqualon Co.
[0049] As noted above, the chopped glass fibers suitable for use in
the present invention are typically wet-chopped fibers having a
length of from about 3 mm to about 50 mm, and more preferably, from
about 25 mm to about 50 mm. Longer fibers tend to form longer and
irregular length strings that may interfere with the appearance of
a reinforced product, while shorter fibers will tend to form
bundles that have limited contact and will tend to produce a weaker
fiber mat. If molded into parts, the irregular shape of the bundles
formed from longer fibers may tend to "print-through" the surface
of the molded part, resulting in less uniform surface that may
include visible fibers.
[0050] The fibers should preferably have a diameter of about 16 to
about 25 .mu.m. The diameter of the fiber will tend to determine
the acceptable chop length range, e.g., with larger the fiber
diameters tending to support longer acceptable chop lengths.
[0051] A wide range of size compositions may be used on the fibers.
However, sufficient time must be allowed for the sizing to wash off
the fibers when they are placed in the slurry. This time may vary
depending on the temperature of the slurry and the degree of
agitation of the slurry after fiber addition, as well as the
composition of the size used on the fibers. For example, the
temperature of the slurry is typically in the range of from about
20.degree. C. to about 40.degree. C., and it usually takes from
about 5 to 15 minutes for the size to wash off and for the bundles
to form. When the temperature of the slurry is lower, the
dissolution of the size is usually slower. The surfactant
components incorporated in the slurry will also tend to affect the
removal of the size composition from the fibers.
[0052] The resulting fiber mat comprising bundles of fibers may be
used in a number of different applications. For example, the mat
may be used in the reinforcement of polyurethane foam headliners.
The wet-laid mats may also be used in reinforced plastics
applications such as in the production of boat hulls or food
service trays.
[0053] While certain representative embodiments and details have
been shown for purposes of illustrating the invention, it will be
apparent to those skilled in the art that various changes in the
methods and apparatus disclosed herein may be made without
departing from the scope of the invention, which is defined in the
appended claims.
* * * * *