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Disposable containers coated with a latex coating

a technology of latex coating and dispersible containers, which is applied in the field of disposable containers, can solve the problems of stains appearing on the outer surface of the container, liquids, hot liquids, etc., and the container, especially those made from eps particles, have a tendency to leak, and achieve the effect of reducing or eliminating leakag

Inactive Publication Date: 2005-07-14
NOVA CHEM INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0022] The invention has met the above need. A thermoplastic container is molded from expandable thermoplastic particles and a latex coating is applied to a portion of at least one of the inner and outer surfaces of the container; preferably to the inner surface; and more preferably to both the inner and outer surfaces. The container is relatively impenetrable thereby substantially reducing or eliminating leakage, and therefore, stains from forming on the surfaces of the container.
[0028] Some embodiments of the invention involve a molded thermoplastic container that exhibits improved resistance to leakage and / or stain and improved insulation properties.
[0031] And still other embodiments involve an article of manufacture comprising a molded thermoplastic container that is coated with a latex coating and that contains a liquid or food substance, and which container has improved storage longevity, improved stain resistance, and / or improved leakage resistance.

Problems solved by technology

In spite of careful bead size control, one problem that continues to plague the container industry is that after a period of time the containers, especially those made from EPS particles, have a tendency to leak.
That is, liquids, especially hot liquids, e.g. coffee, water, oil and / or fat, permeate around the fused polystyrene beads and leak onto the outer surface of the container.
Generally, this results in an unsafe condition for the person holding the container and / or results in stains appearing on the outer surface of the container.
None of these prior art containers pertain to thermoplastic containers that are coated with a latex coating and are used to retain and / or store liquid and food substances, such as coffee, soups, stews, pre-cooked foods and the like.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0063] This example illustrates the preparation of latex coated containers. Expandable polystyrene cup beads (DYLITE® beads from NOVA Chemicals, Inc., which comprise polystyrene and pentane) were blended with zinc stearate and pre-expanded in an 11-gallon (about 1.5 cubic foot) Rodman Steam pre-expander (Artisan Industries Inc.) at atmospheric pressure. The pre-expansion was operated batch wise. 3.5 pounds of cup beads having a diameter distribution of about 0.008 inches to about 0.02 inches were used to make pre-puff with a density of about 3.5 pounds per cubic foot. The newly prepared pre-puff was air dried for 5 minutes to remove the moisture and aged for about 4 hours before molding.

[0064] Sixteen-ounce cups were molded from the aged pre-puff beads. The steam header pressure was 80 pounds per square inch and the total cycle time was in the range of 6 to 15 seconds. The molded foam cups were allowed to age overnight.

[0065] Latex (Roymal 45526 product manufactured and marketed b...

example 2

[0071] The EPS cups were 6 ounce cups. The oil retention test (ATF) for these EPS cups having a pre-puff density of 3.5 pounds per cubic foot was performed in a manner similar to that for Example 1.

[0072] The type of latex coating was the same as that used in Example 1. The coating was first diluted with water to produce coatings with varying solids content. The molded foam cups were coated via a dip coating process with the diluted latex so that both the inner and the outer surfaces of the cups were coated. The coated cups were dried at room temperature overnight before being tested. The results are shown in Table 2.

[0073] The cups with the latex coating have an increased ATF compared to those cups without the latex coating (control).

TABLE 2CoatingThickness6.0μ9.0μ12.0μSolid—8.0812.1316.17content (%)ATF (hr)0.8316.44848RemarkControl

example 3

[0074] The procedure of Example 1 was repeated except the testing method was replaced by the following method.

[0075] Four coated cups were tested by the following method: 1) Oil fried pre-shaped cup noodles, such as those available in the market, were placed in each cup. 2) Three grams of red pepper powder were spread evenly onto the noodle surfaces. 3) Each cup was tightly sealed with an adhesive label and plastic stretch film, and placed in the oven at a temperature of 149° F. (65° C.). 4) Each sample was checked for stains first every hour during a 7 hour period and then once every 8 hours until failure for a total of 72 hours or 3 days.

[0076] The average time to failure (ATF) was calculated similar to that set forth in Example 1. The maximum ATF value of 72 hours represents that none of the cups for the cup group sampling exhibited any stain or leakage. The minimum ATF value of 1 hour represents that all of the cups in the cup group sampling failed within the first 1 hour.

[00...

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Abstract

A molded thermoplastic container e.g. cup, bowl made from expandable thermoplastic particles e.g. expandable polystyrene, has a latex coating, e.g. latex of methyl methacrylate and styrene copolymer, latex of methyl acrylate and styrene copolymer, latex of acrylic acid and styrene copolymer, and latex of butadiene and styrene copolymer, applied to at least its inner surface via dipping, brushing or spraying processes for improved leakage and / or stain resistance and / or storage longevity. The coating may be applied to the outer surface of the container for leak resistance and printing purposes. A related method for forming the container, an article of manufacture, and an improved method for storing liquid and food substances are also disclosed.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to disposable containers. More particularly, the present invention relates to molded foam containers that are made from thermoplastic particles, e.g. expandable polystyrene particles (EPS), and that are coated with a latex coating. The containers are used to retain liquids, e.g. coffee or foods containing oil and / or fatty components, e.g. precooked fat-containing foods, e.g. instant noodles, soups, fried chicken, sauces, and the like. The invention also relates to a method for forming a container, an article of manufacture, and an improved method for storing liquid and food substances. [0003] 2. Background Art [0004] The manufacture of molded foam containers, e.g. cups, bowls, etc. from expanded thermoplastic particles is well known. The most commonly used thermoplastic particles are expandable polystyrene (EPS) particles. [0005] Typically, polystyrene beads are impregnated with hydroca...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B65D1/00B65D1/28C08J7/04
CPCB29K2025/00B29K2105/0064B29K2105/048Y10T428/1352C08J7/047C08J2325/06C08J2433/00B65D1/28C08J7/0427B29C49/42828B65D25/34B65D23/08B65D85/00
Inventor RUSSELL, JEFFORY E.COWAN, DAVID ALLENPIISPANEN, DENNIS H.TANG, JIANSHENGWILLIAMS, MICHAEL TRAVIS
Owner NOVA CHEM INC