Attorney Docket No. 5747-000010/WO/POA

PROCESS FOR PREPARING BIODEGRADABLE MOLDED COMPOSITIONS

FIELD [0001] The present disclosure relates to biodegradable molded compositions and processes for making biodegradable molded compositions.

BACKGROUND

[0002] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0003] Traditionally, molded compositions have been prepared using polyvinyl chloride (PVC) plastisols. Generally, the process comprises heating a suspension of PVC resin and plasticizer to a temperature of 300° to 400 ⁰ F to prepare a PVC hot melt which is then injected into metal molding cavities. After injection, the hot melt cools to become a solid at room temperature.

[0004] Although PVC resins have been preferred because they are ideally suited for forming low hardness molding compounds, PVC does not degrade if released into the environment. Thus, there have been attempts at developing more environmentally-friendly compositions for preparing molded products. For example, U.S. Patent No. 6,174,525 describes compositions comprising polyvinyl alcohols and natural gums to prepare biodegradable

"gels" for use in making fishing lures. Likewise, U.S. Patent No. 6,753,004 describes compositions comprising gelatin and collagen for forming biodegradable fishing lures. Although each of the references describes a process for making biodegradable compositions, the processes are more

Attorney Docket No. 5747-000010/WO/POA

costly and time-consuming as compared to traditional PVC molding because the each process requires that the composition be cooled below ambient temperature for extended periods to cure.

[0005] Thus, a need exists for a process of preparing biodegradable molded products which can be cured and demolded at a temperature and time consistent with traditional PVC processing.

SUMMARY

[0006] The present disclosure is directed to biodegradable molded products, compositions for making biodegradable molded products, and processes for making such products and compositions.

[0007] In one embodiment, the disclosure provides a process for preparing a biodegradable molded composition. The process comprises contacting polyvinyl alcohol, an organic plasticizer, and water to form a liquid dispersion. The dispersion is heated to prepare a hot melt which is then filled into a mold to form the molded composition. In a particular embodiment, the dispersion comprises less than about 50% by weight water.

[0008] In another embodiment, the disclosure provides a liquid dispersion for preparing moldable composition. The dispersion comprises from about 10% to about 30% by weight polyvinyl alcohol; from about 20% to about 80% by weight of an organic plasticizer, and from about 10% to about

40% by weight water.

[0009] In still another embodiment, the disclosure provides for a formulation for preparing a biodegradable molded composition. The formulation comprises from about 15% to about 25% by weight polyvinyl

Attorney Docket No. 5747-000010/WO/POA

alcohol; from about 50% to about 60% glycerin; and from about 20% to about 30% water.

[0010] Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

DETAILED DESCRIPTION

[0011] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.

[0012] In accordance with the present disclosure, it has been found that biodegradable molded compositions can be prepared under conditions consistent with traditional PVC processing by using dispersions comprising polyvinyl alcohol, an organic plasticizer and water. In particular, the dispersions of the present disclosure have been found to have the advantage of requiring less than about 50% by weight water, thereby requiring less curing time to provide for an acceptable molded composition.

[0013] In a first embodiment, the disclosure provides for a liquid dispersion for use in preparing a molded composition. Generally, the dispersion comprises from about 10% to about 30% by weight polyvinyl alcohol, from about 20% to about 80% by weight organic plasticizer, and from about 10% to about 40% by weight water. In an exemplary embodiment, the dispersion comprises from about 15% to about 25% by weight polyvinyl alcohol, from about 50% to about 60% by weight organic plasticizer, and from

Attorney Docket No. 5747-000010/WO/POA

about 20% to about 30% by weight water. In another exemplary embodiment, the dispersion comprises about 20% by weight polyvinyl alcohol.

[0014] Suitable polyvinyl alcohols for use in the dispersions can include fully hydrolyzed polyvinyl alcohol, partially hydrolyzed polyvinyl alcohol, and mixtures thereof. An example of a suitable polyvinyl alcohol for use in the present disclosure is Elvanol 71 -30 commercially available from

DuPont Co., Wilmington, DE.

[0015] Suitable organic plasticizers for use in the dispersions can generally include any known plasticizer selected from the group consisting of glycols, polyglycols, esters, polyethers, and mixtures thereof. Exemplary organic plasticizers may include glycerin, trimethylol propane, triethylene glycol, triethyl citrate, ethylene glycol, pentaerythritol, and mixtures thereof. In an exemplary embodiment, the organic plasticizer is glycerin.

[0016] The dispersions may further comprise a preservative such as a biocide to impart storage stability to the dispersion and/or a de-foamer to facilitate the removal of air from the dispersion. An example of a suitable preservative is Dowicil 75 commercially available from The Dow Chemical Co., Midland, Ml. A specific example of a suitable defoamer is BYK 067 commercially available from BYK-Chemie USA, Wallingford, MA. [0017] The present disclosure also provides methods for preparing a biodegradable molded composition. The methods generally comprise heating any of the dispersions described above to prepare a hot melt, filling the hot melt into a mold and allowing the composition to cure before demolding.

Attorney Docket No. 5747-000010/WO/POA

[0018] Generally, the dispersion is heated to a temperature of from about 19O ⁰ F to about 22O ⁰ F to form the hot melt. In some embodiments it may be desirable to remove at least a portion of the air from the dispersion prior to heating. Air may be removed from the dispersion, for example, by any suitable means including the addition of a defoamer or by subjecting the dispersion to vacuum.

[0019] After injecting the hot melt into molds, the molded composition is allowed to cure for 2 to 10 minutes at ambient temperature.

Thus, the process of the present disclosure allows for the preparation of a molded composition wherein the molded composition can be de-molded within less than about 20 minutes after filling the hot melt into the mold and without forcibly cooling the composition. Accordingly, the present disclosure may be advantageous in that biodegradable molded compositions can be prepared without additional time or expense required to cure the compositions.

[0020] The present disclosure will be further understood with reference to the following example:

EXAMPLE 1

[0021] The following example describes a comparison of four formulations for use in preparing a biodegradable molded composition. The formulations are shown in Table 1.

Table 1

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[0022] The experiment comprised preparing a liquid dispersion by mixing the polyvinyl alcohol (Elvanol 71 -30 commercially available from DuPont Co., Wilmington, DE), glycerin and water (for formulations 1 and 2 only) or plasticizer (for formulation 4) at room temperature. Biocide (Dowicil 75 commercially available from The Dow Chemical Co., Midland, Ml) and defoamer (BYK 067 commercially available from BYK-Chemie USA, Wallingford, MA) were added and the dispersions were de-aerated for one minute in an atmosphere of 30 inches Hg. After de-aerating, the dispersions were heated to a temperature of about 200 ⁰ F in a microwave for 1 .5 to 2.5 minutes to form a hot melt. The hot melt was inserted into molds and allowed to cool to ambient temperature. Results showed that the molded compositions prepared from formulations 1 and 2 provided good physical and elastomeric characteristics in comparison to the compositions from formulations 3 and 4. Accordingly, 20% to 30% water appears to be required to provide a good plasticizer mixture for the Elvanol 71 -30 polyvinyl alcohol.

[0023] While the present disclosure is made with reference to exemplary embodiments, it will be understood by those skilled in the art that a number of modifications, additions and deletions are within the scope of the disclosure as defined by the claims below.