Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1995-02-15
2001-03-27
Cain, Edward J. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S132000, C524S133000, C524S135000, C524S148000, C524S261000, C524S262000, C524S267000, C524S414000, C524S417000, C524S418000, C524S419000
Reexamination Certificate
active
06207737
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is directed to chemically treated glass fibers, strands or yarn where the fibers impart improved strength in reinforcing thermoplastics and in particular polyolefins.
Glass fibers are produced by flowing molten glass via gravity through a multitude of small openings in a precious metal device, called a bushing. Typical formulations of glass fibers are disclosed in
The Manufacturing Technology of Continuous Glass Fibres
, Library of Congress Catalog Card Number 72-97429, by K. L. Loewenstein, Elsevier Scientific Publishing, 1973, at page 29. Glass fibers are, for example, those known as “E glass”, “S glass”, “D glass” and are typically between 3 and 30 microns in diameter.
After the fibers have cooled very shortly after their issuance from the bushing and usually in close proximity to the bushing, these fibers are treated with a chemical treating formulation usually referred to in the art as a sizing composition or size. The size serves to make the fibers more compatible with the material they will ultimately be used to reinforce and to make the fibers more easy to process. The aqueous size can be applied by sprayers, rollers, belts, metering devices or any similar application device. The sized glass fibers are gathered into bundles or strands comprising a plurality of individual fibers, generally from 200 to more than 3000. The sized glass fibers generally can have between about 0.01 and 5 percent of sizing composition based on the weight of the glass fiber.
After their formation and treatment, the strands can be wound into a spool or “forming package” and/or may be chopped. The forming packages or chopped strands are usually dried in either an oven or at room temperature to remove some of the moisture from the fibers.
The strands of treated fibers can be used to reinforce various materials such as thermoplastic polymers. Thermoplastics can be of different types, including chemically coupled and non-chemically coupled polyalkylenes such as polypropylenes and particular types of strands of sized fibers have generally been directed to reinforcement of either of these thermoplastics.
U.S. Pat. No. 5,130,197 to Temple teaches a sizing having 1) an amino-silane coupling agent, 2) a carboxylic modified polyolefin resin, 3) an epoxy, urethane, or polyester resin or copolymer thereof, and 4) a binder stabilizer. These sized fibers are preferably used to reinforce non-chemically coupled polypropylene homopolymer. Also U.S. Pat. No. 4,341,677 to Tamosauskas teaches a size having a film forming polymer, coupling agent and an oil-in-water emulsion of an antioxidant like hindered phenols and diarylamines.
The fiber reinforced plastic industry continues to search for improvements in mechanical properties both initially and upon heat aging.
It would be beneficial, therefore, to provide chemically treated or sized fibers, strands and bundles thereof resulting in improved initial mechanical strength and/or improved mechanical strength retention and/or color on heat aging when used to reinforce for example, chemically coupled polypropylene, non-chemically coupled polypropylene and mixtures of these.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided an aqueous sizing composition for glass fibers. The sizing composition comprises:
a) a coupling agent;
b) a chemically modified polyolefin film forming material;
c) a stabilizer selected from the group consisting of:
i) phosphinates selected from the group consisting of alkali metal phosphinates, alkaline earth metal phosphinates, ammonium phosphinate, organic phosphinates and mixtures thereof;
ii) phosphonites selected from the group consisting of alkali metal phosphonites, alkaline earth metal phosphonites, ammonium phosphonite, organic phosphonites and mixtures thereof;
iii) phosphites selected from the group consisting of alkali metal phosphites, alkaline earth metal phosphites, ammonium phosphite, organic phosphites and mixtures thereof;
iv) hypophosphites selected from the group consisting of alkali metal hypophosphites, alkaline earth metal hypophosphites, ammonium hypophosphite and mixtures thereof;
v) sulfites selected from the group consisting of alkali metal sulfites, alkaline earth metal sulfites, ammonium sulfite and mixtures thereof;
vi) bisulfites selected from the group consisting of alkali metal bisulfites, alkaline earth metal bisulfites, ammonium bisulfite and mixtures thereof; and
vii) mixture of one or more of the stabilizers of i through vi with an antioxidant selected from the group consisting of hindered phenols, diarylamines, thioethers and mixtures thereof.
Also provided are a plurality of glass fibers having said sizing composition applied thereon as well as polyolefin composites reinforced with said sized glass fibers.
DETAILED DESCRIPTION OF THE INVENTION
The aqueous sizing composition of the present invention contains, in addition to water as a carrier, a coupling agent, a chemically modified polyolefin film forming material and, stabilizer effective against oxidizing phenomena. That is, the material is effective to deter oxidation of the matrix polymer to which sized glass fibers are added as reinforcement as well as the coupling agent. Particular types of stabilizers that can act as antioxidants provide particular benefits to thermoplastic polymers such as polyolefins, polyamides, and polyesters (polybutylene terephalate, PBT, and polyethylene terephthalate, PET) that are reinforced with glass fibers. These water emulsifiable, dispersible, or soluble stabilizers include inorganic and organic, phosphinates (or termed phosphonites depending upon the valance), phosphites, hypophosphites, sulfites and bisulfites. These can be used alone or in mixtures with each other or in mixtures with any other emulsifiable, dispersible, or soluble antioxidant that is known to those skilled in the art for use with coatings and films on discrete surfaces such as fibers. For instance, the antioxidants of U.S. Pat. Nos. 4,483,948; and 4,341,677 can be used and these patents are hereby incorporated by reference. Examples of these other types of antioxidants include hindered phenols, diarylamines, thiothers, and the like. More particularly, the stabilizer for use in the present invention can be selected from:
i) phosphinates selected from the group consisting of alkali metal phosphinates, alkaline earth metal phosphinates, ammonium phosphinate, organic phosphinates and mixtures thereof;
ii) phosphonites selected from the group consisting of alkali metal phosphonites, alkaline earth metal phosphonites, ammonium phosphonite, organic phosphonites and mixtures thereof;
iii) phosphites selected from the group consisting of alkali metal phosphites, alkaline earth metal phosphites, ammonium phosphite, organic phosphites and mixtures thereof;
iv) hypophosphites selected from the group consisting of alkali metal hypophosphites, alkaline earth metal hypophosphites, ammonium hypophosphite and mixtures thereof;
v) sulfites selected from the group consisting of alkali metal sulfites, alkaline earth metal sulfites, ammonium sulfite and mixtures thereof;
vi) bisulfites selected from the group consisting of alkali metal bisulfites, alkaline earth metal bisulfites, ammonium bisulfite and mixtures thereof; and
vii) mixture of one or more of the stabilizers of i through vi with an antioxidant selected from the group consisting of hindered phenols, diarylamines, thioethers and mixtures thereof.
Sodium, potassium and lanthanum are exemplary of alkali metals and alkaline earth metal, respectively for the above stabilizes.
In one embodiment, an alkali metal phosphinate stabilizer is used which is an alkali metal phenyl phosphinate, an example of which is sodium benzene phosphinate. This material is used in amounts as generally disclosed hereinafter, although greater amounts can be used if additional benefits are required. An example of a commercially available sodium benzene phosphinate is that available from Stauffer Chemical Company having the formula C
6
H
6
O
2
PNa with a for
Meesters Laura A.
Schell Philip L.
Subramanian Rajgopal
Cain Edward J.
Pingitore Linda
PPG Industries Ohio Inc.
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