Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-06-23
2002-06-11
Szekely, Peter (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C523S205000
Reexamination Certificate
active
06403677
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the aqueous application of additives to polymeric particles. Particularly, the invention relates to a composition and a method for applying additives to polymeric particles. More particularly, the composition and method for applying additives to polymeric particles includes using a water-dissipatable polyester derived from a dicarboxylic acid component and a diol component and a difunctional monomer containing a SO
3
M moiety attached to an aromatic nucleus. The composition and method of the invention are particularly suited for applying hydrophilic and/or hydrophobic materials to polymeric particles.
Numerous methods for introducing additives to polymeric particles are known to those skilled in the art. For example, additives such as antioxidants, processing aids, slip agents, antiblocking agents, antistatic agents, lubricants, UV stabilizers, coupling agents and colorants can be dry blended in either pellet or powder form or melt blended using an extruder or other suitable melt blending apparatus.
Some polymers are presently being manufactured with technology that does not lend itself to such techniques as melt compounding and pelletizing. Many polymers such as high density polyethylene, linear low density polyethylene, and polypropylene emerge from the polymerization reactor in a dry granular form, i.e., in a form similar to that of a fluidized bed system. Presently, additives for these polymers must be introduced by melting, compounding, and then pelletizing. This extra step increases the cost of such polymer manufacturing operations and can adversely affect the properties of such polymers.
Another method of introducing additives to polymeric particles is to contact such particles with an additive at the extruder hopper during end use processing, but before melt compounding or extrusion. Additives such as colorants, slip agents, processing aids, blowing agents, and others are introduced to virgin polymeric particles at this stage usually in concentrate form. In many instances, difficulty is encountered in metering the exact amounts of additive concentrate necessary to do a specific job. This is especially true for additives such as processing aids and external lubricants which are used at very low levels and usually cannot be added in a concentrate form.
Another method for coating polymeric particles, particularly polypropylene granules, with additives includes dispersing the additives in a solvent followed by removal of the solvent. While some stabilization is imparted to the coated polypropylene granules, the treated pellets have severe static electricity problems when subsequently processed.
It would be desirable to have available a simple process for applying additives to polymeric particles in order to enhance the stability of the particles without adversely affecting the physical properties and processability of the treated particles.
SUMMARY OF THE INVENTION
In accordance with the present invention, a wide range of additives, such as antioxidants or thermal stabilizers, colorants or the like can be applied to the surface of polymeric particles. Advantageously, the additives may be emulsified or dispersed in an aqueous system and used to coat the polymeric particles before normal drying or degassing operations. The additives may be applied using a variety of techniques such as, for example employing a spray, wipe, or dip system. Such aqueous systems may be formulated to treat polymeric particles which can then be formed into materials made from such particles. The resulting materials may be used in applications such as film or packaging for food, medicine and the like. Also, such aqueous systems may contain lubricants, mold release agents, antistatic agents and the like.
Briefly, the present invention includes an aqueous composition includes an additive, an effective amount of a water-dissipatable polyester, and from about 15 to about 95 weight % water.
Another aspect of the present invention is a method for applying various additives to a polymeric particle. The method includes the steps of contacting at least a portion of the polymer with the composition of the present invention having at least one additive included therein and drying the polymeric particles whereby at least a portion of the additive is retained on the polymeric particle.
Polymers which emerge from the polymerization reactor in particle form would substantially benefit from the application of such aqueous emulsions containing antioxidants and other additives by means of such an aqueous treatment. This means of introducing additives would eliminate melt compounding, lower production energy requirements, and minimize heat history on the polymer particles.
DETAILED DESCRIPTION OF THE INVENTION
In accordance with the present invention, an aqueous composition is provided for applying a variety of additives to polymeric particles. The aqueous composition includes at least one additive, an effective amount of a water-dissipatable polyester derived from a dicarboxylic acid component and a diol component and a difunctional monomer containing a —SO
3
M group attached to an aromatic nucleus to at least partially disperse the additive, and from about 5 weight % to about 95 weight % water, wherein the percentages are based on the total weight of the components in the aqueous composition.
Additives employed in the practice of the present invention include such materials as antioxidants, including, for example, hindered phenols, thioesters, organophosphites, and hindered amines, which may readily be dispersed or emulsified in the aqueous emulsion system. Additional additives contemplated by the present invention include coupling agents, antistatic agents, nucleating agents, metal deactivators, lubricants, slip agents, antiblocking agents, UV inhibitors, flame retardants, release agents, pigments, colorants, acetaldehyde reducing compound, reheat aids, and the like. More particularly, the additives employed in the practice of the present invention may be selected from antioxidants, e.g., tetrakis[methylene 3-(3′,5′-di-tert-butyl-4′-hydroxyphenyl)propionate]methane, octadecyl 3-(3′,5′-di-tert-butyl-4′-hydroxyphenyl)propionate, 1,3,5-trimethyl-2,4,6-tris-(3,5-di-tert-butyl)-4-(hydroxybenzyl)benzene, bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite, tris(mono nonylphenyl)phosphite, 4,4′-butylidene-bis(5-methyl-2-t-butyl)phenol, tris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate, tris-nonylphenyl phosphite; distearyl pentaerythritol diphosphite; tetrakis-(2,4-di-t-butylphenyl)-4,4′-biphenylylene-diphosphonite; tris-(2,3-di-t-butylphenyl)phosphite; butylated hydroxy toluene; dicetyl thiodipropionate; dimyristyl thiodipropionate; poly (1,4-cyclohexylene-dimethylene-3,3′-thiodipropionate (partially terminated with stearyl alcohol); and the like; coupling agents, e.g., silanes; titanates; chromium complexes; low molecular weight polyolefins (with carboxylic moieties); high molecular weight polyolefins and acrylates (with carboxylic moieties); chlorinated paraffins; and the like; antistatic agents, e.g., glycerol monostearates; ethyoxylated amines; polyethylene glycol; quartemary ammonium compounds (salts); and the like; nucleating agents, e.g., sodium benzoate; diphenyl phosphinic acid (including magnesium, sodium, calcium, aluminum salts); phenyl phosphinic acid (including salts); phenyl phosphorous acid (including salts); and the like; metal deactivators, e.g., oxalyl bis-(benzylidene hydrazide); 2,2′-oxamido bis-(ethyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate; and the like; lubricants/slip agents/antiblocking agents, e.g., diatomaceous silica (earth); precipitated silica, silica gel, talc; clay; metallic stearates; alkyl bis-stearamids; glycerol monostearates; polyethylene glycol; erucamid; oleamid, and the like; UV inhibitors, e.g., 2-hydroxy-4-octoxybenzophenone; 2-hydroxy-4-isooctoxybenzophenone; 4-hydroxy-4-n-dodecyloxybenzophenone; 2-(3-di-t-butyl-2-hydroxy-5-methylphenyl-5-chlo
Boshears Betty J.
Eastman Chemical Company
Graves Bernard J.
Szekely Peter
LandOfFree
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