Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Reexamination Certificate
1999-07-29
2001-08-07
Kelly, Cynthia H. (Department: 1774)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
C428S378000, C428S375000, C428S392000, C106S287120, C106S287130, C106S287160, C524S492000
Reexamination Certificate
active
06270897
ABSTRACT:
TECHNICAL FIELD AND INDUSTRIAL APPLICABILITY OF THE INVENTION
The present invention relates to glass fibers used in the manufacture of glass fiber reinforced composite structures. More particularly, the present invention relates to an aqueous sizing composition for application to the glass fibers to reduce interfilament abrasion during formation, and to improve compatibility of the fibers with the matrix material of the composite structure.
BACKGROUND OF THE INVENTION
In the manufacture of glass fiber reinforced polymeric composites, many of the properties of the composites are directly attributable to the properties of the glass fiber reinforcement. Accordingly, anything that deleteriously affects the desired physical properties of the glass fibers, such as abrasion of the fibers during their processing, is desirably avoided. Moreover, the degree to which the composite benefits from the inclusion of the glass fibers is largely dependent on the chemical coupling that occurs at the fiber polymer interface. For these reasons, glass fibers intended to be used as reinforcing elements in articles fabricated from polymeric or resinous materials are usually provided with a light-weight size coating to protect the fibers from damage by abrasion during processing and fabrication, and/or to enhance the reinforcing interaction between the fibers and the matrix material. Such size coatings typically comprise a film-forming polymeric or resinous component, a lubricant to reduce interfilament abrasion, and a glass-resin coupling agent, such as a partially hydrolizable organosilane or hydrozylate thereof.
Such size coatings are usually deposited on the glass fibers during their production, which is ordinarily by attenuation of a plurality of streams of molten glass issuing from a reservoir through a corresponding plurality of orifices in a bushing, and solidification of the attenuated filaments by cooling. The coating is typically applied to the fibers as a liquid solution or dispersion in a volatile medium, from which the ultimate size coating is deposited on the fibers by evaporation of the medium and any other volatile components. Evaporation of the liquid medium may occur either before or after the fibers have been collected into a package, as by winding onto a suitable collet, or chopped into discrete lengths.
While a number of organosilanes, or hydrozylates thereof, either alone or in various mixtures, have been employed as coupling agents in such sizing compositions, the advantages provided by the particular mixture of organosilanes in the sizing composition of the present invention have not heretofore been appreciated in the art.
SUMMARY OF THE INVENTION
The present invention provides an aqueous sizing composition for glass fibers utilized in the reinforcement of polymeric composites. In particular, the present invention provides an aqueous sizing composition formed by combining at least one diester-organosilane coupling agent and at least one triester-organosilane coupling agent with water, which, after hydrolysis, provides a sizing composition comprising at least one diol-organosilane hydrozylate and at least one triol-organosilane hydrozylate. It has been discovered that the combination of these coupling agents in the sizing composition provides enhanced physical properties to composite articles reinforced with glass fibers coated therewith.
DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS OF THE INVENTION
The sizing composition of the present invention provides sized glass fibers for use as reinforcement in polymeric articles which, in turn, provide the resulting composite with enhanced physical properties. The sizing composition, and the sized glass fiber strands of the present invention, can be used for any reinforcement application, but are preferably used to reinforce epoxy composites. The glass fiber coated with the sizing composition of the present invention can be of any conventional form, for example, chopped or continuous strand, roving, woven glass fiber strand and the like, but continuous strand is generally preferred.
The glass fibers can be prepared and coated with the sizing composition by any conventional method suitable for producing such fibers. For example, suitable fibers can be formed by attenuating molten glass into filaments through orifices in a bushing and the fibers coated with the sizing composition by spraying or roll coating as is well known in the fiber-making art.
The aqueous sizing composition of the present invention comprises a combination of at least one diol organosilane and at least one triol-organosilane. Additionally, the sizing composition may contain other commonly included components such as film-forming polymeric materials and lubricants. The film-forming polymers must be compatible with the polymeric matrix to be reinforced, and, in combination with the other components of the sizing composition, impart good processing characteristics and matrix compatibility to the glass fiber strand. Suitable film-forming materials include epoxy, vinyl ester, polyester, vinylacetate, polyurethane and acrylic polymer resins. However, low molecular weight epoxy resins are generally preferred. Preferably such resins have an epoxy equivalent weight of from about 175 to about 275, more preferably, from about 230 to about 250.
Any conventional glass fiber lubricant compatible with the film-forming material and matrix resin can be used in the sizing compositions of the invention. For example, suitable lubricants include nonionic lubricants, such as polyethylene glycol esters (e.g., PEG 400 Monooleate), and cationic lubricants, such as polyethylene imine alkylamides (e.g., EMERY 6760u lubricant, commercially available from Henkel, Inc.).
In addition to any filmformer and lubricant, the sizing compositions of the invention contain the hydrozylates of at least two silane coupling agents, one of which is a triester-organosilane of the formula R
1
—Si(OR
2
)
3
, wherein R
1
is selected from a phenyl group or a saturated or unsaturated alkyl group having from 1 to 10 carbon atoms, optionally substituted with a halide, methacryloxy, cycloalkylepoxy, epoxy ester, mercapto, amino, ureido or carbamate moiety; and R
2
is selected from a methyl, ethyl, 2-methoxy-ethyl, isopropyl, n-propyl or n-butyl moiety; and one of which is a diester-organosilane of the formula R
3
—Si(CH
3
)(OR
4
)
2
, wherein R
3
can be independently selected from the same group of moieties as R
1
, and R
4
can be independently selected from the same group of moieties as R
2
. Preferably, R
1
and R
3
are independently selected from methyl, vinyl, chloropropyl, phenyl, methacrylyloxy-propyl, beta-(3,4epoxycyclohexyl)ethyl, glycidoxy propyl, mercaptopropyl, aminopropyl, N-beta-(aminoethyl) aminopropyl, mercaptoethyl, n-Octyl, (HOC
2
H
4
)
2
NH(CH
2
)
3
, H
2
NCONH(CH
2
)
3
, H
2
N(CH
2
)
2
NH(CH
2
)
2
NH(CH
2
)
3
and C
2
H
5
OCONHCH
2
CH
2
CH
2
; and R
2
and R
4
are independently selected from methyl and ethyl moieties. Suitable triester-organosilanes include the following compounds commercially available from OSi Specialties of Tarrytown, N.Y., and suitable diester-organosilanes include modified versions of the specified triester organosilanes, wherein one of the ester functionalities has been replaced with a methyl group.
TABLE A
Trade Designation
Nomenclature
Formula
A-143
gamma-Chloropropyl-trimethoxysilane
ClCH
2
CH
2
CH
2
Si(OCH
3
)
3
A-151
Vinyltriethoxysilane
CH
2
═CHSi(OCH
2
CH
3
)
3
A-153
Phenyltriethoxysilane
C
6
H
5
Si(OCH
2
CH
3
)
3
A-162
Methyltriethoxysilane
CH
3
Si(OCH
2
CH
3
)
3
A-163
Methyltrimethoxysilane
CH
3
Si(OCH
3
)
3
A-172
Vinyl tris(2-methoxy-ethoxy)silane
CH
2
═CHSi(OC
2
H
4
OCH
3
)
3
A-174
gamma-Methacryloxy- propyltrimethoxysilane
A-186
beta-(3,4-Epoxycyclohexyl) ethyltrimethoxysilane
A-187
gamma-Glycidoxypropy- trimethoxysilane
A-189
gamma-Mercaptopropyl-
HSCH
2
CH
2
CH
2
Si(OCH
3
)
3
trimethoxysilane
A-1100
gamma-Aminopropyl-triethoxysilane
H
2
NCH
2
CH
2
CH
2
Si(OCH
2
CH
3
)
3
A-1111
Hydroxy-functional silane
A-1120
N-beta-(Aminoethyl) gamm
Adzima Leonard J.
Flautt Martin Charles
Eckert Inger H.
Gray J.
Kelly Cynthia H.
Owens Corning Fiberglas Technology Inc.
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