Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1999-07-20
2003-09-30
Pyon, Harold (Department: 1772)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C428S407000, C428S520000, C428S522000, C428S514000, C428S515000, C427S212000, C427S222000, C427S385500, C523S200000, C524S501000, C524S569000
Reexamination Certificate
active
06627679
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to barrier polymer compositions in general and, more particularly, to vinylidene chloride or vinyl chloride polymer compositions having improved extrudability and to the process for preparing the same.
To improve the extrudability of vinylidene chloride or vinyl chloride polymer resins, additives, such as lubricants (for example, internal and external types), olefinic waxes and oils, have been blended with the vinylidene chloride or vinyl chloride polymer resins prior to fabrication into a final product. The additives are conventionally incorporated into the polymer resins by methods involving intense mechanical working at elevated temperature, on a roller mill or in high intensity mixers. These methods result in less than satisfactory uniform distribution of the additives on the resin particles and, sometimes, in the formation of the additives into agglomerates.
It would be desirable to provide a process for preparing vinylidene chloride polymer and vinyl chloride polymer compositions which ensured generally uniform distribution of additives on the polymer resin particles.
SUMMARY OF THE INVENTION
In a first aspect, the present invention is a vinylidene chloride polymer or vinyl chloride polymer composition comprising vinylidene chloride polymer particles or vinyl chloride polymer particles and a coagulated latex additive coated on the surface of the polymer particles.
In a second aspect, the present invention is a monolayer structure comprising the vinylidene chloride polymer or vinyl chloride polymer composition of the first aspect.
In a third aspect, the present invention is a multilayer structure comprising (1) one or more layers of an organic polymer or a blend of two or more different organic polymers, the organic polymer of one layer being the same as or different from the organic polymer of another layer and (2) one or more layers of the vinylidene chloride polymer or vinyl chloride polymer composition of the first aspect.
In a fourth aspect, the present invention is a process for preparing a vinylidene chloride polymer or vinyl chloride polymer composition which comprises:
(A) adding an additive in the form of a latex to an aqueous dispersion of vinylidene chloride polymer or vinyl chloride polymer particles; and
(B) coagulating the latex additive on the surface of the polymer particles to coat the polymer particles.
DETAILED DESCRIPTION OF THE INVENTION
As used herein, the term “barrier polymer” refers to polymers displaying the ability to restrict the passage of gases, such as oxygen, carbon dioxide or moisture vapors. As used herein, the term “vinylidene chloride polymer” encompasses homopolymers of vinylidene chloride and also copolymers, and terpolymers, thereof, wherein the major component is vinylidene chloride and the remainder is one or more monoethylenically unsaturated comonomer copolymerizable therewith. As used herein, the term “vinyl chloride polymer” encompasses homopolymers of vinyl chloride and also copolymers, and terpolymers thereof, wherein the major component is vinyl chloride and the remainder is one or more monoethylenically unsaturated comonomer copolymerizable therewith.
For vinylidene chloride polymers, an effective amount of polymerized vinylidene chloride monomer is generally in the range of from 60 to 100 percent by weight of polymer.
For vinyl chloride polymers, an effective amount of polymerized vinyl chloride monomer is generally in the range of from 60 to 100 percent by weight of polymer.
Monoethylenically unsaturated monomers which can be employed in the practice of the present invention for preparing the vinylidene chloride polymers and vinyl chloride polymers include vinyl chloride, vinylidene chloride, alkyl acrylates, alkyl methacrylates, acrylic acid, methacrylic acid, itaconic acid, and acrylonitrile, methacrylonitrile. Preferred monoethylenically unsaturated monomers include acrylonitrile, methacrylonitrile, alkyl acrylates, and alkyl methacrylates. More preferred monoethylenically unsaturated monomers include acrylonitrile, methacrylonitrile, and the alkyl acrylates and alkyl methacrylates having from 1 to 8 carbon atoms per alkyl group. Most preferably, the alkyl acrylates and alkyl methacrylates are methyl acrylates, ethyl acrylates, and methyl methacrylates. The most preferred monoethylenically unsaturated monomer is methyl acrylate.
Most preferred vinylidene chloride polymers include polymers formed from 91 to 94 weight percent vinylidene chloride and from 6 to 9 weight percent of methyl acrylate and polymers formed from 80 to 85 weight percent vinylidene chloride and from 15 to 20 weight percent vinyl chloride.
Most preferred vinyl chloride polymer include polymers formed from 91 to 94 weight percent vinyl chloride and from 6 to 9 weight percent of methyl acrylate and polymers formed from 80 to 85 weight percent vinyl chloride and from 15 to 20 weight percent vinylidene chloride.
Vinylidene chloride polymers are known and are commercially available. Processes for preparing them, such as by emulsion or suspension polymerization process, are also familiar to persons of ordinary skill in the art. See, for example, U.S. Pat. Nos. 2,558,728; 3,007,903 and 3,879,359, all of which are incorporated herein by reference. Except as specifically set forth herein, polymerization conditions (for example, temperature and agitation) are those conventionally employed in the polymerization of vinylidene chloride or vinyl chloride. Although the order of addition of the various ingredients is not critical, it is preferred to prepare the complete aqueous phase including initiator, and emulsifier or suspending agent, and then to add the monomer phase. Advantageously, in preparing the aqueous phase, about three-fourths of the water required for the polymerization is added to the reactor prior to the addition of the initiators, plasticizers and other suitable additives, such as, for example, chelating agents and antioxidants. This order of addition of the aqueous phase ingredients helps maintain a monomer-in-water suspension polymerization.
Typically, when the monomer is added to the aqueous phase (monomer-in-water phase), the mixture is heated with agitation, in the substantial absence of oxygen, to a temperature of between about 25° C. and 95° C. for a period sufficient to provide the desired conversion of monomer to polymer. The conversion of monomer to polymer is generally between 50 to 99 percent.
After polymerization is complete, an aqueous suspension or dispersion of the vinylidene chloride or vinyl chloride polymer or resin particles is formed. To form a monomer-free dispersion, residual monomer is preferably removed first by venting the reactor to atmospheric pressure while heating the reactor to 95° C. The dispersion is then transferred to a batch stripper where the remaining residual monomer is vacuum-stripped at 90° C. Thereafter, the dispersion is cooled down, unloaded and dewatered, and the resin is collected and further dried.
The latex additives which can be employed in the practice of the present invention include any polymer latex which can be coagulated, including acrylic polymer latexes, such as Metablen L-1000, an acrylic polymer obtained in latex form from Elf Atochem North America, Inc; vinylidene chloride polymer latexes, such as SARAN™ Resin F-278, a vinylidene chloride polymer latex commercially available from The Dow Chemical Company; impact modifier latexes such as grafted particulate rubbery polymers, including styrene/butadiene latex, methacrylate-butadiene-styrene (MBS), acrylonitrile-butadiene-styrene (ABS) acrylate-methacrylate (all acrylic) and acrylate-butadiene-methacrylate (modified acrylic). These latex additives impart onto the barrier polymers desirable properties such as, for example, improved impact resistance, improved barrier to oxygen, carbon dioxide or water vapor and improved extrudability.
Processes for preparing polymer latexes are known. See, for example, U.S. Pat. No. 3,108,984. Typically, latexes are prepared by dispersing the monomers in an
Dow Global Technologies Inc.
Hon Sow-Fun
Pyon Harold
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