Note: Descriptions are shown in the official language in which they were submitted.
~ 1641~
SIZING COMPOSITION TO YIELD SIZED GLASS
FIBERS WITH IMPROVED UV STABILITY
Background of the Invention
The present invention is directed to a sizing composition useful
in producing si~ed glass fibers having improved stability to ultraviolet
radiation.
More particularly, the present invention is directed to a sizing
composition and sized glass fibers produced therewith that when used in
reinforced polymers yield reinforced polymers with improved color stability
when subjected to light.
Light is electromagnetic radiation in the wave length range
including infrared, visible, ultraviolet, and X-rays. Only about five
percent of the ultraviolet radiation emitted from the sun reaches the
earth's surface and this five percent is usually radiation having wave
lengths longer than 290 nanometers. The light produced from man-made
sources such as fluorescent lights and the like can emit ultraviolet
radiation ~UV) that generally has wave lengths below 290 nanometers.
~tost organic substances including polymers or plastics are changed on
long-term exposure to light including sun light and man-made light that
contains ultraviolet radiation. Prolonged exposure of polymers to UV-
containing light leads to photo oxidation and degradation of the polymer.
This degradation is usually manifested in the discoloration of the polymer.
It is well known in the art to use additives for polymers that
give some degree of UV stability to the polymer to retard the process of
photo oxidation and degradation of the polymer upon exposure to light.
There must be at least ten different classes of materials used as UV
1 3 2
stabilizers for polymers. The principle classes of UV stabilizers are the
benzophenones, benzotriazoles, the salicylates, metallic complexes, sub-
stituted acrylonitriles and certain colorants. Which class or particular
stabilizer within a class that should be used with a particular type of
polymer depends on the specific requirements relating to polymer compati-
bility, permanence, and the level of absorption needed for the particular
polymer, because some polymers are more sensitive to UV radiation than
others. For example, polyurethanes, which are produced by reacting polyols
containing an active hydrogen with isocyanate, require stabilization
against photo oxidation. It is known in the art in the case of polyurethanes
that the hindered amine light stabilizers, like bis(2,2,6,6-tetramethyl-
piperidinyl-4)sebacate and oxalic-anilide derivatives, in combination with
benzotriazoles provide excellent UV stability. In addition to the use of
UV stabilizers, it is also known to add functional groups to the backbone
in order to retard the photo oxidation of the polymer caused by UV radiation.
Glass fibers used as reinforcement for polymers are formed by
being drawn at a high rate of speed from molten cones of glass from tips of
small orifices in a platinum device called a bushing. In order to protect
the glass fibers from interfilament abrasion during formation and further
processing and to make them compatible with the polymers they are to
reinforce, the sizing composition is applied to the glass fibers during
their formation. The sizing compositions conventionally contain lubricants,
film formers, coupling agents, wetting agents, emulsifiers, and the like.
Many of these components are polymeric materials that can degrade by photo
oxidation when subjected to radiation. The degradation of the polymers in
the sizing composition on glass fibers used to reinforce polymers may
lead to the discoloration of the reinforced polymeric material. Such
~ 16~13~
discoloration leads to an unaesthetic appearance of a reinforced polymeric
material and lack of color uniformity over a period of time for the rein-
forced polymeric material.
Objects of the Invention
It is an object of the invention to provide a sizing composition
that has improved light stability.
It is another object of the present invention to provide a sizinv
composition for glass fibers that yields sized glass fibers having improved
UV stability and a reduced tendency to discolor.
It is a further object of the present invention to provide a
polymeric material reinforced with sized glass fibers wherein the sizing
composition on the glass fibers has improved light stability, so as to
deter imparting of discoloration to the fiber and the reinforced poly-
meric material upon long exposure to ultraviolet light.
It is still a further object of the present invention to provide
a sizing composition, sized glass fibers that lead to the production of
polymeric materials reinforced with sized glass fibers that have improved
light stability without the use in the sizing composition of conventional
light stabilizing agents.
It is still another object of the present invention to provide a
sizing composition and sized glass fibers having improved UV stability
and reduced tendency to discolor without deleteriously affecting other
properties of the sizing composition and sized glass fibers.
Summary of the Invention
Accordingly, the foregoing objects are accomplished by the
discovery of sizing compositions comprising thermoplastic, predominantly
~ 1641~2
aliphatic, curable polyurethane latices, appropriate silane coupling
agents, and appropriate lubricant system.
Broadly speaking, in one aspect, the sizing composition of the
present invention comprises one or more thermoplastic, predominantly
aliphatic, polyurethane latices, one or more ureidofunctional silanes, one
or more aminofunctional silanes.
The sizing composition can be used to treat glass fibers that
are processed into any form of glass fibers such as chopped strand; roving;
woven product; continuous strand, chopped strand, or needled mat; and
strands and the like. Depending on what form the treated glass fibers are
to be used, a compatible lubricant can be used in the sizing composition
along with the polyurethane dispersion and the ureidofunctional and amino-
functional silanes. The amount of the polyurethane dispersion and the
ureidofunctional and aminofunctional silanes present in the sizing composition
are generally those amounts conventionally used for film formers and
coupling agents in sizing compositions for glass fibers.
Also, in accordance with this invention the glass fibers are
provided that have at least a portion of their surface in contact with the
residue produced by removing water from the aqueous sizing composition
having a curable thermoplastic, predominantly aliphatic including cyclic
aliphatic polymer, ureidofunctional silane9 aminofunctional silane, and
usually one or more compatible lubricants.
In addition to the polyurethane polymer, ureidofunctional and
aminofunctional silanes and usually lubricant, the sizing composition may
have present additional agents conventionally used in sizing compositions
for glass fibers.
The use of the sizing composition and the sized glass fiber
strand of the present invention can be used to produce reinforced polymeric
~ I641.~
material such as nylon, polybutylene terephthalate, polyethylene tere-
phthalate and polystyrenics. These reinforced polymers have improved
stability from the improved UV stability of the sized glass fibers while
the sized glass fibers have good handleabilities, physical properties,
thermal stability, and processing properties.
Detailed Description of the Invention
The sizing composition, sized glass fiber strands and glass fiber
reinforced polymeric material of the present invention is believed to have
excellent UV stability while maintaining good glass fiber properties of
handleability, thermal aging, ambient aging and processability in accord-
ance with the following theory although the present invention is not
limited by this theory.
The energy content of UV radiation is in the range of about 290
up to 400 nanometers which corresponds to about 95 to about 71.5 kilo-
calories per einstein. This energy level can rupture most of the chemical
bonds in polymer structures, and lower amounts of energy can rupture some
of the chemical bonds in polymers. It is known that not all polymers are
equally affected by UV radiation and some are more resistant than others,
for example, polymethylmethacrylates and fluorocarbons are more resistant
than polyethylene. Some polymers in their pure forms expected to be
resistant to UV radiation are actually degraded because of contaminants
that act as sights for UV energy absorption. It is known that polyurethane
resins based on aliphatic components are resistant to yellowing by UV
light. When polyurethane resins based on aliphatic components are to be
used in a sizing composition with other sizing components, particular
coupling agents must be used in order not to act as contaminants and
present sights for UV energy absorption.
~ 16~132
The thermoplastic, curable, polyurethane resins that are based on
predominantly aliphatic components useful in the present invention are
aqueous emulsions or solutions of polyurethane polymers formed by ehe
reaction of an organic; linear, branched, or ryclic aliphatic isocyanate
with an organic; linear, branched or cyclic aliphatic polyhydroxylated
compound or hydroxyl terminated ether or polyester polymer. By the term
"predominantly aliphatic" it is meant that minor amounts of aromatic
materials may be present so long as the minor amount is not sufficient to
permit degradation of the polyurethane by light so as to cause an unac-
ceptable or unaesthetic amount of discoloration. The aqueous emulsion or
solution of polyurethane has present in it anionic or nonionic surfactants.
Particularly suitable aqueous emulsions of polyurethane polymers useful in
the present invention includes "Rucothane Latex 2010L, 2030L, 2040L, 2050L,
and 2060L", available from Ruco Division of Hooker Chemical Corporation,
New York. The materials are thermoplastic polyurethane latices having a
varying particle size of a high molecular weight isocyanate based thermo-
plastic elastomer in a water dispersion with an anionic or nonionic surfactant.
The Rucothane latices are based on aliphatic isocyanates and have a
polymer solids content of the stable emulsions ranging from 55 to 65
percent by weight where the urethane polymer has an ester backbone.
The Rucothane latexes have a ~rookfield RVF 4 viscosity in centipoise at 2
RPM ranging from 7000 for the "2060L" up to 25,000 for the "2020L" latices.
The preferred Rucothane latex used in the sizing composition of the present
invention is the resin designated "2010L" because of the i~proved process-
ability obtained with glass fibers treated with a sizing composition
containing this particular Rucothane resin. Also the polyurethane product
designated "Hylene W" available from Dupont may be used. The amount of the
4~ k
-- 6 --
116~
thermoplastic polyurethane latex present in the sizing composition is
generally a major amount of the solids in the sizing composition and is
preferably in the range from about 40 to about 95 weight percent of the
sizing composition based on the non-aqueous solids of the sizing composition
and from about 2 to about 50 weight percent based on the aqueous sizing
composition.
Any suitable ureidofunctional silsnes can be used in the ~izing
composition of the present invention. By ureidofunctional is meant the
presence of the group
R' ~ H
R - ~ - - N - C -
wherein R' and R are as defined below. Non-exclusive examples include
compounds with the following formula
R-N-~-N-CH2-CH2-CH2-Si(OR " ~3
wherein R and R' can be a hydrogen atom or methyl group and wherein R " is
a methyl or ethyl group. The ureidofunctional silanes are generally
neutral and water soluble materials that hsve reduced reactivity at lower
temperatures with many matrix resins. One particularly useful ureidofunc-
tional silane for the sizing composition of the present invention is
*
designated "~-1160" and is available as 50 percent concentration in methanol
solution from Union Carbide Corporation, New York. The "A-1160" has a
formula molecul&r weight of 264.1, a flash point of 43 as determined by ASTM
method D-56 using a tag closed cup, and has a specific gravity at 25/25~C
of 0.988, and a refractive index at 25-C of 1.386. The amount of ureido-
functional silane used in the sizing composition of the present invention
i5 generally in the range of about Q.05 to about 2.0 weight percent based
on the aqueous sizing composition and about 1 to about 4 weight percent of
the non-aqueous solids in the sizing composition.
Any suitable aminofunctional silane can be used in the sizing
composition of the present invention. These aminofunctional silanes range
* Trade Mark
~ 1641~'~
in composition from the single primary amino group of gamma-aminopropyltri-
ethoxysilane to the primary-secondary diaminofunctional silane of N-beta(amino-
ethyl) gamma-aminopropyltrimethoxysilane and polyaminofunctional silanes.
One particularly useful aminofunctional silane for the sizing composition
of the present invention is gamma-aminopropyltrimethoxysilane available
A commercially under the designation "A-1100" from Union Carbide Corporation.
The amount of aminofunctional silane used in the sizing composition of the
present invention is in the range from about 0.05 to about 2.0 weight
percent of the total aqueous sizing composition and from about 1 to about 5
weight percent of the sizing composition based on the non-aqueous solids in
the composition.
Lubricants which are suitable for use in the sizing composition
of the present invention can be any cationic, anionic, or nonionic lubri-
cant or mixture thereof. Preferably, lubricants are used in the sizing
composition and the particular lubricant used will vary with the particular
form in which ~he sized glass fibers will be used, e.g., chopped strands,
roving, woven strand, mat and the like. Particu~arly suitable lubricants
are those designated "Emery 6717" and "Emery 67-U" both of which are amide
substituted polyethylene amines commercially available from Emery Industries.
In addition polytetrafluoroethylene fluorocarbon resin dispersions, for
example, "TeElon" resin dispersion can be employed as lubricants in the
dispersion of this invention. Also, the lubricant can be a combination of
lubricants such as Emery Lubes 6717 and Emsorb 6901 available from Emery
Industries. When the sizing composition is used to treat glass fibers that
will eventually be chopped to produce the preferred sized glass fibers
strand form, i.e., chopped strand, it is preferred to use a combination of
lubricants. This preferred combination of lubricants include one or more
r,~J~
1 1641~2
polyoxyalkylene and/or polyalkylene polyol lubricants such as "Pluracol~
V-10 or V-7 polyols" both available from BASF Wyandotte Corporation
from Michigan. The product, "Pluracol~ V-10 polyol", is a viscous, high
molecular weight, liquid polyoxyalkylene polyol with a specific gravity at
60F./60F. by BWC test of 1.089 with a flash point by ASTM D92-52 of
510F. The product, "Pluracol~ V-7 polyol", is a water-soluble, high
molecular weight, viscous, liquid polyalkylene polyol with a specific
gravity at 25C./25C. of 1.090 and flash point of 510F. Also, this
lubricant combination includes a lubricant modified aminosilane, for
0~ C~oY ~
10 ~ example, "Y-9072 lubricant modified/~ silane" available from ~nion
Carbide Corporation having a flash point of 145F as determined by ASTM
method D-93 using a Pensky closed cup with a specific gravity of 0.998 at
25/25C and a refractive index at 25C of 1.438. The use of this preferred
combination of lubricants facilitates further processing and fabrication of
glass fibers into chopped strand.
The amount of lubricant employed in the sizing composition of the
present invention is within the range of about 0.2 to about 2 weight
percent of the aqueous sizing composition. If more than one type of
lubricant is employed then the total lubricant in the sizing composition
can range from about 0.2 to about 5 weight percent of the aqueous sizing
composition.
In addition to the linear or branched but preferred cyclic
aliphatic polyurethane, and ureidofunctional silane and aminofunctional
silane, and preferably lubricant components of the sizing composition,
additional agents may be added to the sizing composition. Non-exclusive
examples of additional agents that may be used are coupling agents, film
formers, film former modifiers, lubricants, adhering agents such as Ruco
~ 164;1~2
Catalyst, available from Hooker Corporation, cross-linking agents such as
A "Cymel 370" available from American Cyanamid Corporation and other similar
additives. It is preferred to have present in the sizing composition
additional agents that perform the function of processing aids. The
preferred processing aids include dibutylphthalate (DBP) that acts as a
plasticizer for the polyurethane cured film. Another preferred processing
aid present in the sizing com~osition of the present invention is a polyester
film former such as "RD-1135B" available from PPG Industries, Inc. that
reduces binder throw off and acts as an antioxidant. In general the amount
of additional agents present in the sizing'composition of the present
invention are those amounts conventionally used to perform the function for
which the agent is added to the sizing composition. The amounts of DBP
added to the sizing composition are in the range of about 0.05 to about 5
weight percent based on the non-aqueous solids of the sizing composition.
The amount of RD-1135B added to the sizing composition is in the range of
about 2 to about 15 weight percent based on the non-aqueous sizing composition.
The sizing composition of the instant invention is prepared by
mixing the polyurethane dispersion with water in a mixing tank with aggitation.
To the polyurethane dispersion-water mixture there is added the dibutyl-
phthalate ~DBP) and it is dispersed well into the polyurethane with moderate
agitation. In a separate vessel the ureidofunctional silane, the amino-
' functional silane, and a lubricant modified silane, "A-~40" silane,
"A-~6~" silane and "Y-9072" silane respectively are premixed with water
and hydrolized for a short period of time. After the silanes are premixed
they are combined with the mixture of DBP, polyurethane and water. The
lubricant is diluted with water, preferably hot water and cooled and then
added to the combination of coupling agents and polyurethane mixture.
Je /n~2~
-- 10 --
~ 1 6 ~
After this addition the processing aids can be added to the mixture. The
mixture is then diluted to final volume with water. The mixture is checked
for its pH characteristic, its solids content and viscosity. Typically,
the overall solids content of the sizing composition can vary from about 4
to about 20 percent by weight. It should be noted that the solids content
can be adjusted in accordance with the desired solids content for the
specific forming condition employed. Generally, the solids content will
range from about 5 to about 10 percent by weight and preferably from 6.5 to
8.5 percent by weight. By solids content it is meant the residual solids
remaining after drying the sizing composition at about 105C to constant
weight. In a~l events, the solids content of the sizing composition should
be adjusted so that the viscosity at 20~C of said sizing solution does not
exceed 100 centipoise. This viscosity restriction is necessary in order
that the filaments do not break during the application of the sizing
solution.
In applying the sizing composition of the instant invention to
glass fibers, the glass fiber strand is formed by a multitude of fine fiber
glass filaments which are drawn at a high rate of speed through molten
cones of glass located at the tips of small orifices in a bushing such as
is shown in U.S. 2,133,238. During formation, the filaments are coated
while they are moving at speeds on the order of 5,000 to 20,000 fpm with
the forming size of the instant invention. The sizing composition may be
sprayed on the fibers as they are being drawn or in the preferred embodiment
the fibers may be drawn across the surface of a roller applicator on which
the sizing composition is placed. The fibers after sizing are grouped
into strands which are then wound, typically, onto forming packages utilizing
a winder and an associated paper or plastic or other type of forming tube
located on the surface of the winder in the conventional manner.
-- 11 --
I ~ 6~1~2
The forming packages containing the glass fiber strand sized with
the sizing composition of the instant invention may then be formed into
roving by unwinding a plurality of strands from several forming packages
positioned on a creel and combine the strands into parallel form and
winding the strands on tubular support in the conventional manner, or into
chopped strands by feeding the sized glass fiber strands through a chopper
in a conventional manner, or into a mat or woven glass fiber product. The
preferred glass fiber form for which the sizing composition of the instant
invention is used is the chopped glass fiber strand, which is preferably
formed by chopping sized glass fiber strands that are obtained from a
plurality of forming packages located on a creel rather than chopping a
plurality of sized glass fibers during the glass fiber forming process.
The glass fiber strands in any form, but preferably in the form
of chopped strand sized with the sizing composition of the present invention
can be used to reinforce any polymeric material and obtain a product that
has better UV stability while still maintaining satisfactory physical
properties. It is preferred to use the sized glass fibers of the present
invention as reinforcement for polymeric material such as polyamide (nylon),
polyethylene terephthalate (PET), polybutylene terphthalate tPBT), poly-
styrenics (PS), thermose~ting polyester, and chemically coupled poly- -
propylene like the product of Hercules Chemical Corporation designated
"PC0-72" which is a blend of homopolymer of polypropylene and a polypropylene
polymer grafted with maleic anhydride. It is most preferred to use the
sized glass fibers in the form of chopped strand as reinforcement for
polyamide materials.
The following examples will further elucidate the concept of the
present invention.
Sizing compositions were prepared from the formulations of Table 1.
1 1 6 ~
r ~ ~d~ ~ ~ ~ ~ ^ c~ ^ D ^ C ~ ~ ~ ,0 u~
5~ 0 ~ ~ O c: 0 3 c c~ ~ 3 ~ ~t O ~ O C 1--
V V ~-- V 1~ J V I Y . I ~ p) N
3 r~ ~ c ,_ O ,_ ~ ~ (D c y-
n~ n ~- P r~ ~ o ~ a~ o ~ - ~q
W r ~ P) P~ t.n O ~ ~ O C O ~r~
c ~ r ~ co p ~ P- g
r~ 0~3 tD3 p~ ~ p 3 p~ p O
3 ~--c ~(D 3 c o u, n ~ (D P ~ C ~ r~ (D
~O ~ O (~ ~ O ~ :~
O ~ ~ ~ V ~n o rr ~; p u~
0 0 O~ P~ 3
r5 r'- C `I X O ~ D~O ~ ~
O -- I';
o ~o r o
~ I_
I_ O P
~_ _ 3 ~-.
~n ~ I ~ ~ ~ ~_ C O
n OCO ~
> n
O' P~
C~
O cn
~ 3 rr~ ~
I I ~ w c~ o ~ c ~ ~
O ~D
u~
~ ~ r~
O ~ ~
~c 3 ~ O
I I ~ ~ w r~ c ,.. ~;
O cr~ W Ul ~ W _ ~7
~ n ~
O'
o
0
r~
~D a ,
~ I I I I W tJ~ ~ C N
O I i I I ~ ~ Ul ~~ ~- .
O` O'
~ oo 0
O ~s~ w ~ 3
o 1~ ~n I I I O CJ` ~ O C~ C
O O O I I I O O O O ~OD~
~ n
O
l ~
~ ~ - ~ ~
-- ^ ~ ~ ^ ~ ~ ~rr
l - o o ~ l - ~ o ~
O O I ~ ~ `D 0~ ~_~
-
~ 13 --
1 16Al~
p ~ ~ V~, o X ,~ ,
O N ~_ O N
I P ~ ~ . ~D .
r~ tD C~ ~D' 3
P ~ O ~p
~ ~' U~, P
~ ~q
o
p 3
o C~ ~ ~ ,_
`D 0~ V~ P'
a
~ ~D W r~
O
O a~ ~D W I--
n
00 ~'
O _l ~D ~ ~
O ~ O'
0
~, 0 a
~ . .
~0'
~:
a~
t 16413Z
The sizing formulations shown in Table I were prepared by placing
approximately 7.6 liters of water in a premix tank and stirring in the
stated amount of polyurethane resin dispersion with low speed stirring.
Following this mixing, the stated amount of the dibutylphthalate was
dispersed well into the polyurethane polymer dispersion with moderate speed
stirring. After this dispersion was prepared, the coupling agents, the
ureidofunctional silane, aminofunctional silane, and, if any, the lubricant
modified silane were premixed and hydrolized in approximately 75.7 liters
of water. The dispersed polyurethane polymer mixture was then added to the
hydrolized silane mixture. After this addition, the lubricant was dis-
solved in approximately 3.786 liters of hot water and cooled with approxi-
mately 11.4 liters of water which was then added to the mixture of coupling
agent and polyurethane polymer. After this addition, processing aids such
as the polyester film former, RD-1135B was diluted with an equal quantity
of water and added to the mixture of lubricant coupling agents and poly-
urethane polymer. After these additions, the mixture was diluted to
approximately the quantity of sizing composition indicated with water and
the pH and solids ch~racteristics were obtained.
The sizing formulation of Table I were applied to glass fiber
strands in the conventional manner as described above to produce glass
fiber strands of the K~37 dimension or G-67.5, although a sizing composition
of the present invention can be used to treat glass fibers to produce glass
fiber strand of any dimension. After the glass fibers were treated with
the sizing compositions of Table I and gathered into glass fiber strand in
the form of a forming package, the strands were prebaked for approximately
12 hours at approximately 240F. (116C.). The dried glass fiber strands
were then chopped in a conventional manner to a chopped length of 1/8".
~ 164137
Sized, chopped glass fiber strands prepared with sizing compo-
sitions like those stated in Table I were tested for their UV stability
and other physical properties when used to reinforce polyamides. The
results of this testing are shown in Table II.
1 1641~2
W ~ ~ 5
~ _ - O` O
O Ol~ _ 'O
~D I P~ 1-- D~1-- D~ t~
U~ C ~D ;~ ~D5~ ~D a3 ,.,
Pl g H H H ~1
o ~:) O D~ ~
O ~ ~ ~3
-hOqP~ 3 El 3 ~ ~
~D
t'~
n a ~
a
_ ~ o
o ~ o ~
~ o
5 0
W W ~ W
o . . .
~ U~
~D C ~ t r~ F~ & tn
rr ~ X X X rr
~~D n, ~D~, ~CT C
C ~ ~ ~ n ~ ~ C~
I'~ O P~ O
w n ~l 3
rrrr ~ ^r~ I_ O P~
~D C~ I I ~ r ~ r~
: _ _ _ O '~:1 0
O ~ ~ ~ ~
O ~ ~ ~D
~D ~ ~ r.~ ~ rt
_ ~ ~ W ~~ ~DH ~1 tD
~I O000r. ~ r
1~ H
O ~ ~
r~ 3
O ~ ~'
~ '':1 ~D r
O ~ t~
~ 0~ Xr ~ a P
U~ ~ ~ o
Oo r 0~ t~ D
N
0~ r
~3
W ~ _
O ~ I_ U~
g O O g l- ~
w w ~ ~ OZ 3
5 ~
u~
~ ~
~D ~
~I Co ~D 5
~ 16~132
The results of Table II indicate that the polyamide material
reinforced with chopped glass fiber strand having the sizing composition of
the present invention produce a reinforced polyamide material that has
excellent UV stahility while maintaining good physical properties.
The foregoing has described sizing compositions, sized glass
fiber strands and reinforced polymeric materials with sized glass fiber
strand of the present invention. The invention involves the presence of
sizing materials on glass fiber strands and in reinforced polymeric materials
that lead to the properties of improved UV stability while maintaining good
physical properties. This is accomplished by having a sizing composition,
sized glass fiber strands, and polymeric materials reinforced with sized
glass fiber strands wherein materials in the sizing include one or more
polyurethane polymers, preferably in the form of a dispersion, one or more
ureidofunction silanes, one or more aminofunctional silanes and one or
more appropriate lubricants depending on the form in which the glass fibers
are to be used, preferably polyalkylene, polyol type lubricant with a
lubricant modified aminosilane and processing aids such as polyester film
formers or film former modifiers and plasticizers.
- 18 -
