Food container having enhanced biodegradability, heat-stability and absorbability

Abstract

A paper laminate provided for a food container includes a substrate paper or paper sheet, and at least a fibrous or fabric absorbent layer consisting of a biodegradable polymer selected from the group consisting of polylactic acid (PLA), polyhdroxyalkanoate (PHA), and polyhydroxy butyrate-co-valerate (PHBV), and a reinforcing polymer which includes a thermobondable polymer of polyethylene; with the absorbent layer formed, coated, bonded or adhered on the substrate paper to form a moisture and oil absorbable layer inside the food container to absorb moisture and oil in the food container for enhancing the food taste and quality, and also to provide a heat-durable and biodegradable food container.

Description

BACKGROUND OF THE INVENTION

A conventional food box may be made by coating a polyethylene (PE) film or other films on a paper sheet to form a water-proof box. When such a film-coated paper box is provided for storing heated food such as fried rice, the moisture existing in the food will be vaporized and then condensed to cause the food sticky, thereby deteriorating the food quality or taste.

If such a film-coated paper box is provided for storing fried chicken or other oily foods, the excess oil as drained from the food will not be absorbed by the paper box and may be accumulated on the food to be fed into the eater's body to be hazardous to her or his body weight control or even harmful to their cardiovascular system.

The PE-coated paper box served for food container may be water repellent and heat durable. However, the conventional polyethylene is not biodegradable and may cause environmental problem when discarded.

For environmental protection reason, the polylactic acid (PLA)-coated paper box may be served as food or drink container to be biodegradable after being used.

Even polylactic acid (PLA) is biodegradable, it however has disadvantages of low resistance to condition of high heat and humidity, thereby still being not satisfactory to be a food or drink container.

The present invention has found the drawbacks of conventional food container and invented the present food container, which is biodegradable, thermally stable and moisture or oil absorbable.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a food container foldably formed by a paper laminate including a substrate paper or paper sheet, and at least a fibrous or fabric absorbent layer consisting of a thermobondable polymer including polyethylene (PE) and a biodegradable polymer selected from the group consisting of polylactic acid (PLA), polyhdroxyalkanoate (PHA), and polyhydroxy butyrate-co-valerate (PHBV) formed, coated, bonded or adhered on the substrate paper to form a moisture and oil absorbable layer inside the food container to absorb moisture and oil in the food container for enhancing the food taste and quality, and also to provide a heat-durable and biodegradable food container.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional drawing showing a food container for storing fried rice in accordance with the present invention.

FIG. 2 is a partial cross-sectional drawing as viewed from line 2-2 of FIG. 1.

FIG. 3 is a partial cross-sectional drawing as viewed from 3-3 direction of FIG. 1.

FIG. 4 is a sectional drawing of the paper laminate for forming a drink container in accordance with the present invention.

DETAILED DESCRIPTION

As shown in FIGS. 1-3, the present invention of food container, especially for storing foods F such as fried rice or fried chicken therein, comprises a food container foldably made of a paper laminate 10.

The paper laminate 10 of the present invention comprises: a paper substrate (or base paper sheet) 1, and a fibrous absorbent layer 2 formed on an inside surface of the paper substrate 1 adjacent or contiguous to the food F as stored in the food container, and a protective layer 3 formed on an outer surface of the paper substrate 1, with the protective layer 3 exposed to the environment or the surroundings of the food container.

The paper substrate 1 may be selected from a paper, a paper sheet, a paper board, etc.

The fibrous absorbent layer 2 comprises a fiber layer, non-woven or woven fabric made of multi-component fiber, which includes: a biodegradable polymer, and a reinforcing polymer including a thermobondable polymer.

The thermobondable polymer and the biodegradable polymer are co-extruded to produce the multi-component fiber, which is then processed as a fabric, including non-woven fabric or woven fabric. A conventional co-extrusion or lamination or any other processes may be provided for forming the fabric of the present invention, not limited in this invention.

The biodegradable polymer may be selected from polylactic acid (PLA), polyhydroxyalkanoate (PHA), polyhydroxy butyrate-co-valerate (PHBV), Copoly-L-Lactide (CPLA), and other suitable biodegradable polymers.

The thermobondable polymer includes polyethylene (PE), polypropylene (PP) or any other thermobondable polymers. The thermobondable polymer may also include heat adhesive or heat bondable adhesive for thermally bonding the biodegradable polymer as above-mentioned in order to form the multi-component or bi-component fiber, which is then further processed as non-woven or woven fabric to be the fibrous absorbent layer 2 as formed on the paper substrate 1 of the present invention.

The thermobondable polymer, e.g., polyethylene (PE) may be well thermally bonded with the biodegradable polymer, e.g., polylactic acid (PLA) to produce the fibrous absorbent layer 2, which is then formed on the paper substrate 1 to obtain the paper laminate 10 of a food container of the present invention.

The fibrous absorbent layer 2 may be thermally bonded on the paper substrate 1, preferably by the aid of a heat-bondable biodegradable adhesive including an adhesive of PLA blended with PE. Such a heat-bondable biodegradable adhesive may be coated or pre-formed on the paper substrate 1 by any conventional processes, not limited in the present invention. Or, the adhesive may be formed as an adhesive layer or binder coated or formed on the paper substrate 1, before being further coated with the fibrous absorbent layer 2 thereon.

The thermobondable polymer, such as polyethylene, may also be modified to be biodegradable, even the production cost thereof may be increased.

The reinforcing polymer including a thermobondable polymer is provided for reinforcing the heat stability and moisture resistance of the biodegradable polymer.

The outer protective film layer 3 may be made by blending polyethylene with biodegradable polylactic acid to have the properties for biodegradation and heat stability as well as moisture resistance (water-proof property) so that the food container of the present invention may be totally biodegraded after being used.

Of course, other water-proof or heat durable polymers, or biodegradable polymers may also be selected for making the outer protective layer 3 of the present invention.

The multi-component fiber may also be directly formed (to serve as the absorbent layer 2) on the paper substrate 1 without being primarily processed to be a non-woven or woven fabric. For instance, the multi-component fiber (including PE and PLA fibers) may be directly thermally bonded or bonded by adhesive to the paper substrate 1.

The thermobondable polymer (e.g., PE) and the biodegradable polymer (e.g., PLA) may be blended in a ratio of 50:50, but not limited in this invention.

The fibrous absorbent layer 2 formed on the paper substrate 1 may be further perforated to increase its capillary absorptive property.

When the food container is constructed by the paper laminate 10 as shown in FIG. 1 in accordance with the present invention, a hot food F such as fried rice just taken-away from a restaurant may vaporize its steam vapor V upwardly to be absorbed into the fibrous absorbent layer 2 bonded to the paper substrate 1 of the top cover C of the food container as illustrated in FIG. 2 to minimize the moisture content in the food container to prevent a dew condensation after the steam vapor being condensed and drained to the fried rice to thereby prevent the rice from being sticky and to maintain its “fresh” taste or quality of the food.

Meanwhile, the oil drops O as drained downwardly from the fried rice may be capillarily penetrated and absorbed by the fibrous absorbent layer 2 on the paper substrate 1 of the bottom container B as shown in FIG. 3, to minimize the oil accumulated in the voids or on the surface of the rice. Therefore, the eater may reduce oil “dosage” into her or his body (stomach and bowels) to be beneficial for her or his health including cardiovascular system and body weight control.

If the fried rice as above-mentioned is substituted with fried chicken or other oily foods, the fibrous absorbent layer 2 of the present invention may also help absorb the excess oil as contained in (or on) the oily foods, to be helpful for the eater's health.

The present invention may not only improve the poor heat stability or durability of the biodegradable polylactic acid (PLA) by incorporating therein with polyethylene (PE), but also improving the poor biodegradability of the non-biodegradable PE by incorporating PLA therein. Both PE and PLA are made as oil and moisture absorbable fibers or fabric, thereby enhancing their absorbability of oil and moisture to keep a well food taste or quality, and also to serve an oil-minimized food beneficial for eater's health.

The biodegrable polymer, e.g., the PLA, may be further incorporated therein with nano silver or any other anti-bacterial ingredient to enhance the food preserving and anti-bacterial property of the present invention.

If the oil or moisture absorption requirement is not so critical or necessary for making the food container in accordance with the present invention, the fibrous absorbent layer 2 as aforementioned may be simplified or modified to be a thermobondable biodegradable film layer 3 as shown in FIG. 4 to be formed or coated on both inner and outside layers of the “core layer” of paper substrate 1 to serve as a drink container.

Or, such a thermobondable biodegradable layer 3 may be served as a protective layer 3 to be formed or adhered on an outer surface of the paper substrate 1 as shown in FIGS. 1-3.

The word “Food” of the title of the invention, “Food Container”, may be comprehensively explained to be a food, a drink or the like. The paper laminate 10 may be formed as food containers with diversified shapes, or designs to be a box, a case, a bowl, a bag, a tray, a cup, etc.

The present invention may be further modified without departing from the spirit and scope of the present invention.

Claims

1. A food container made of a paper laminate comprising:

a paper substrate made of paper, paper sheet or paper board; and

at least a fibrous absorbent layer formed on at least one surface of said paper substrate for absorbing moisture or oil as vaporized or released from a food as contacted with the surface of the food container and as stored in the food container;

said fibrous absorbent layer comprising a multi-component fiber including at least a biodegradable polymer and a reinforcing polymer.

2. A food container according to claim 1, wherein said fibrous absorbent layer includes a non-woven fabric or woven fabric made from said multi-component fiber.

3. A food container according to claim 1, wherein said biodegradable polymer is selected from the group consisting of: polylactic acid (PLA), polyhydroxyalkanoate (PHA), polyhydroxybutyrate-co-valerate (PHBV) and Copoly-L-Lactide (CPLA).

4. A food container according to claim 1, wherein said reinforcing polymer includes a thermobondable polymer, which includes polyethylene (PE), and polypropylene (PP).

5. A food container according to claim 1, wherein said fibrous absorbent layer is coated on said paper substrate by an adhesive or a binder.

6. A food container according to claim 5, wherein said adhesive is a thermally bondable adhesive or a heat adhesive.

7. A food container according to claim 6, wherein said adhesive includes polylactic acid and polyethylene.

8. A food container according to claim 1, wherein said paper laminate further includes a protective film layer coated or formed on at least one side or one surface of said paper substrate.

9. A food container according to claim 8, wherein said protective film layer includes a heat stable and biodegradable polymer.

10. A food container according to claim 9, wherein said polymer includes polyethylene blended with polylactic acid.

11. A food container according to claim 1, wherein said fibrous absorbent layer is further incorporated therein with a nano silver ingredient or an anti-bacterial ingredient.

12. A food container according to claim 1, wherein said fibrous absorbent layer is further perforated to make it capillarily penetrable by oil and moisture.

13. A food container made of a paper laminate comprising:

a paper substrate; and

a protective film layer formed on at least one side or one surface of said paper substrate;

said protective film layer including a thermobondable polymer and a biodegradable polymer co-extruded or laminated to form said film layer.

14. A food container according to claim 13, wherein said thermobondable polymer is polyethylene.

15. A food container according to claim 13, wherein said biodegradable polymer is selected from the group consisting of: polylactic acid (PLA), polyhydroxy alkanoate (PHA), polyhydroxy butyrate-co-valerate (PHBV), and Copoly-L-Lactide (CPLA).