Stock material or miscellaneous articles – Composite – Of addition polymer from unsaturated monomers
Reexamination Certificate
2000-04-07
2001-12-11
Michl, Paul R. (Department: 1714)
Stock material or miscellaneous articles
Composite
Of addition polymer from unsaturated monomers
Reexamination Certificate
active
06329068
ABSTRACT:
FIELD OF INVENTION
This invention relates to novel rosin-fatty acid vinylic polymer compositions which exhibit properties that make them useful for formulating moisture vapor barrier coatings for paper and other cellulosic base materials. In particular, this invention relates to rosin-fatty acid vinylic polymer moisture barrier coatings produced from the addition polymerization reaction of a mixture of rosin and fatty acid and a mixture of (meth)acrylic and vinylic monomers.
BACKGROUND OF THE INVENTION
Many packaged materials, such as detergents and potato chips, must maintain a substantially constant moisture content in order to prevent the development of undesirable characteristics (such as agglomeration of the detergent particles or a lack of brittleness of potato chips). When the material in which these types of products were packaged did not function as an effective moisture barrier, the shelf life of the product was shortened due to the moisture gain or loss by the product.
Currently, the moisture vapor barrier coatings most commonly employed by the packaging industry are polyvinylidene chloride (PVDC) and polyethylene. However, problems exist with both of these coatings. For example, the use of PVDC in certain coating applications requires the utilization of environmentally unfriendly solvents. Moreover, where solvents are not be used and an aqueous dispersion of PVDC is employed, the corrosive nature of the dispersion often damages the coating equipment. As for polyethylene, this material must be applied on the desired substrate via a relatively expensive extrusion process.
Often these coating are employed in two-step systems where a primer is used to seal the pores of the packing material and a top coat is utilized to provide additional moisture resistance (see generally U.S. Pat. No. 3,770,486 which is hereby incorporated by reference). However, the addition coating step required in these two-part systems adds to the expense of the process.
To address these problems, the packing industry is actively seeking an effective water-based moisture barrier coating that can be applied in one step.
The traditional process for producing a polymer resin is well-known (see generally U.S. Pat. Nos. 4,839,413 and 5,216,064, which is hereby incorporated by reference). Commonly a solution polymerization reaction is employed wherein a styrenic monomer and acrylic acid is mixed with a hydrocarbon solvent, a polymerization initiator, and a chain transfer agent. Upon completion of the reaction, the solution is stripped of the solvent to yield the polymer composition.
However, major problems exist with the traditional methods of producing such polymers. For example, these methods require the use of environmentally adverse hydrocarbon solvents. Moreover, as these solvents are not usable or desirable in water-based formulations, the solvents must be stripped from the resulting polymers (thereby causing a yield loss). This stripping step also adds expense to the process due to both the loss of yield and the energy consumed in performing the stripping. Also, these methods must utilize chain transfer agents to regulate the molecular weight of the resulting polymer.
Therefore, an object of this invention is to solve these major problems by disclosing a method of producing rosin-fatty acid vinylic polymer compositions which exhibit properties that make them useful for formulating moisture vapor barrier coatings for paper and other cellulosic base materials.
Another object of this invention is to disclose rosin-fatty acid vinylic polymer moisture vapor barrier coating compositions.
SUMMARY OF THE INVENTION
The objects of this invention are met via a method that employs rosin and fatty acid to act as solvents in the polymerization reaction of the acrylic monomers, thereby producing rosin-fatty acid vinylic polymer compositions which are useful as moisture vapor barrier coatings for paper and other cellulosic base materials. As this method does not require the use of hydrocarbon solvents, the need for solvent stripping is eliminated. Also, the polymerization reaction can be conducted at higher temperatures (i.e., up to boiling point of fatty acid) than traditional solution polymer methods, thereby allowing the practitioner to utilize smaller amounts of free radical initiators. Furthermore, the practitioner is able to regulate molecular weight without the use of chain transfer agents, thereby both reducing costs and avoiding the production of unpleasant odors associated with such agents. Moreover, the fatty acid and rosin can function as a reactive diluent to impart flexibility to the vinylic polymer.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The rosin-fatty acid vinylic polymer moisture vapor barrier coating compositions are prepared by the process of:
(A) reacting in an addition polymerization reaction:
(1) about 20.0% to about 60.0% by total weight of the reactants of a fatty acid rosin mixture comprising:
(a) about 10.0% to about 90.0% by total weight of the fatty acid rosin mixture of fatty acid, and
(b) about 10.0% to about 90.0% by total weight of the fatty acid rosin mixture of rosin; and
(2) about 40.0% to about 80.0% by total weight of the reactants of a monomer mixture comprising:
(a) about 15.0% to about 45.0% by total weight of the monomer mixture of a member selected from the group consisting of acrylic acid, methacrylic acid, and combinations thereof,
(b) about 55.0% to about 85.0% by total weight of the monomer mixture of a member selected from the group consisting of vinylic monomers and combinations thereof,
(c) about 0.5% to about 5.0% by total weight of the monomer mixture of a polymerization initiator,
(d) up to about 4.0% by total weight of the monomer mixture of a chain transfer agent, and
(e) up to about 30.0% by total weight of the monomer mixture of a hydrocarbon solvent; at a temperature in the range of about 135° C. to about 1750° C. to produce rosin-fatty acid vinylic polymer reaction products having a weight average molecular weight in the range of about 4,000 to about 12,000; and
(B) dispersing the rosin-fatty acid yinylic polymer in water to produce the moisture vapor barrier coating composition.
Preferred rosin-fatty acid vinylic polymer moisture vapor barrier coating compositions are prepared by the process of:
(A) reacting in an addition polymerization reaction:
(1) about 20.0% to about 60.0% by total weight of the reactants of a fatty acid rosin mixture comprising:
(a) about 20.0% to about 50.0% by total weight of the fatty acid rosin mixture of fatty acid, and
(b) about 50.0% to about 80.0% by total weight of the fatty acid rosin mixture of rosin; and
(2) about 40.0% to about 80.0% by total weight of the reactants of a monomer mixture comprising:
(a) about 20.0% to about 25.0% by total weight of the monomer mixture of a member selected from the group consisting of acrylic acid, methacrylic acid, and combinations thereof,
(b) about 60.0% to about 70.0% by total weight of the monomer mixture of a member selected from the group consisting of vinylic monomers and combinations thereof,
(c) about 1.0% to about 3.0% by total weight of the monomer mixture of a polymerization initiator,
(d) about 0.5% to about 2.0% by total weight of the monomer mixture of a chain transfer agent, and
(e) about 1.0% to about 4.0% by total weight of the monomer mixture of a hydrocarbon solvent;
at a temperature in the range of about 135° C. to about 175° C. to produce rosin-fatty acid vinylic polymer reaction products having a weight average molecular weight in the range of about 4,000 to about 12,000; and
(B) dispersing the rosin-fatty acid yinylic polymer in water to produce the moisture vapor barrier coating composition.
The addition polymerization reaction used to produce the rosin-fatty acid vinylic polymer reaction products is a melt polymerization reaction in which no water is employed. Reaction temperatures suitable for use in the present method are within the range of about 135° C. to about 175° C.; with the preferred temperatures being in the range of about 140° C. to about 170° C.
Adams Stanley C.
Shah Rajnikant
McDaniel Terry B.
Michl Paul R.
Reece IV Daniel B.
Westvaco Corporation
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