JPH04189740A - Food tray and case - Google Patents

Abstract

PURPOSE:To realize a tray which is light weight, strong, stable in the shape, waterproof and having biodegradability by a method wherein unwoven cloth is made from fiber connecting agent mainly composed of chitosan, and the unwoven cloth is heated and molded for contraction. CONSTITUTION:A web composed of natural, regenerated, semi-synthetic fiber or a mixture of these fibers having cellulose structure is directly treated with a fiber connecting agent which is mainly composed of salt of chitosan, or the fibers are preliminarily crossed physically. Next, unwoven cloth is obtained by using 0.5 to 1.0% aqueous chitosan salt solution obtained by solving chitosan in 0.5 to 1.0% aqueous solution of an organic acid or aqueous chitosan salt solution mixed with fine cellulose as a fiber connecting agent, adjusting the ratio of fiber 100 pts.wt. chitosan 1 to 5 pts.wt. in solid, and water repellent 1 to 10 pts.wt. attached on the fiber and then drying. Weight of the unwoven cloth must by 200g/m<2> or more, and the unwoven cloth is molded for contraction to have a fiber density of 0.2g/cm<2> or more. As the water repellent, aliphatic compound or derivative of thereof which is easy to biodegradate by bacteria in the earth is preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to food trays and cases used for transporting meat, fish, vegetables, eggs, etc. and displaying them in showcases.

[Conventional technology and its problems]

In recent years, in the food departments of supermarkets, department stores, retail stores, etc., when transporting fresh foods such as meat, fish, vegetables, eggs, etc., or displaying them in showcases, containers using styrofoam resin have been used to store subdivided foods. Food trays and cases are used. The amount of food trays used is enormous, and most of them are used by ordinary households.

It is discarded at food processing companies and becomes garbage.

These food trays and cases are made of foamed resin, so they have a large volume despite their light weight, which is a big problem because they will not decompose if thrown into a landfill.

In the metropolitan areas of Tokyo and Osaka, it is predicted that there will be no place to dispose of municipal waste in the next few years, and even if incinerated, the generation of harmful substances has become a problem and a cause of environmental pollution.

There is a huge social need to make food trays and cases into products that can be decomposed by microorganisms in the soil in a short period of time.

[Means to solve the problem]

In view of the above drawbacks, the present invention aims to provide a food tray or case that is light, strong, stable in shape, water resistant, safe, inexpensive, and biodegradable. It is something.

That is, the present invention forms a web of fibers made of a cellulose structure such as cotton or rayon, and uses an interfiber binder mainly composed of chitosan to form a nonwoven fabric that is decomposed by microorganisms in soil. The above problem was solved by heating and compression molding the product.

The fibers used in the present invention can achieve the purpose as long as they are natural fibers such as cotton and hemp having a cellulose structure, recycled fibers such as viscose rayon and copper ammonia rayon, or semi-synthetic fibers such as acetate. It is possible to
Moreover, you may use these mixed fibers.

The above-mentioned fibers can be used to form a nonwoven fabric using a known web forming machine to form a parallel web, a cross web, or a random web, and these webs can be directly treated with an interfiber binder mainly composed of chitosan salt. Or,
Alternatively, these webs may be subjected to needle punching or water needle punching to physically entangle the fibers in advance.

The entangled web is then prepared with 0.5-1% chitosan in a 0.5-1.0% aqueous solution of an organic acid such as acetic acid or citric acid.
For 100 parts by weight (solid content) of fibers, use an aqueous chitosan salt solution dissolved to a 0% concentration or a chitosan salt aqueous solution prepared by mixing fine cellulose with the aqueous chitosan salt solution as an interfiber binder by dipping or spraying. Chitosan 1~
After adjusting the adhesion amount to 5 parts by weight (solid content) and 1 to 1 n parts by weight (solid content) of the water repellent, it is dried to form a nonwoven fabric. If the amount of water repellent is less than 1 part by weight, it is not preferable because it absorbs water and easily loses its shape (and if it exceeds 10 parts by weight, the biodegradation period will be longer than necessary).

In addition, the basis weight of the nonwoven fabric must be 200 g/d or more, and 2
If it is less than 00 g/J, sufficient strength required for shape retention cannot be obtained.

As a molding method for the water repellent-treated biodegradable nonwoven fabric thus formed, thermal compression molding using a press is effective, and the fiber density is made to be 0.2 g/a1 or more by compression molding. If it is less than 0.2 g/cd, the effect of the water repellent will not be sufficiently exhibited, the cellulose fibers will easily lose their shape due to their water absorption, and the strength will be insufficient.

Furthermore, it is known that an aqueous salt solution of chitosan solidifies when dried, but since this solidified product is a chitosan salt, it will swell in water and even dissolve if it is not fixed with an alkali. However, if it is heated and dried together with cellulose, it will react with the cellulose and will not dissolve even in water.

Furthermore, the water resistance strength can be improved by mixing fine cellulose fibers with a diameter of 11 m or less, which are obtained by beating pulp or the like, into the aqueous chitosan salt solution.

In addition, food trays must be treated with water repellent treatment to prevent them from absorbing protein juices such as fish juice and meat juice, and the water repellent is made from carbon atoms, which are said to be easily biodegradable by microorganisms in the soil. Water repellents of aliphatic compounds and derivatives of aliphatic compounds having a structure connected in a straight chain are preferred.

Specifically, N-ophtadecyl ethylene urea.

Stearic acid chloride, alkyl ketene dimer, quaternary ammonium salt of fatty acid, stearic acid amide, 2
-Ethylhexylzirconate and the like are used.

[Function] By having the structure shown in FIGS. 1 and 2, the food tray according to the present invention has sufficient practical strength as a food storage container, has excellent water repellency, and is light and easy to handle. It does not break when bent like a plastic container, and after its use, it decomposes in the soil as industrial waste in a short period of time, freeing it from environmental pollution.

An embodiment of the present invention will be described below.

〔Example〕

As shown in FIG.
A cross web (3) with a basis weight of 350 g/nf, for example, is used, which is formed using a web forming machine using dX38m as a cellulose fiber.

This web is passed through a needle punch machine at 100P/c.
By performing the needle punching treatment of i, the fibers are intertwined with each other to form a temporarily fixed needle punched web. (4) shows the state of fiber entanglement after needle punching.

The temporarily fixed needle punch web thus formed is prepared by preparing an aqueous solution of chitosan salt with a concentration of 1% using chitosan lactic acid = I:] (weight ratio), and containing fine cellulose and a water repellent having the composition shown below. After being immersed in the mixed solution, it was dried in a hot air dryer at 100° C.

(Blend) (Parts by weight) 1% chitosan salt aqueous solution 100 parts (Kyowa Yushi Fuconac C) Fine cellulose fiber 43 parts (Daicel M
FC-100) Water repellent (oftadenol ethylene urea) 1.
25 Department Hodogaya Chemical Oftex EM40%
This nonwoven fabric has a solid content of 7.0 g of chitosan and a solid content of 3.5 g of water repellent attached to the fibers, and has a basis weight of 361.
g#, thickness was 1.2 plates. This nonwoven fabric was thermally compressed using a thermal compression molding machine.

The above nonwoven fabric was sandwiched between a concave mold and a convex mold, and about 5 tons of pressure was applied, and the mold was heated to 100°C and compression time was set for 30 seconds. Weight 7.
A saucer-shaped food tray with a weight of 5g and a nonwoven fabric density of 0.27g/cJ was obtained. FIG. 2 is a perspective view of the food tray (6) molded in this manner, and a dense container with excellent shape retention is formed.

When this biodegradable food tray was buried in soil, it completely decomposed and disappeared in about 2.2 months.

Incidentally, the shape and dimension of the tray is not limited to the above embodiment, and a desired shape and dimension of nine dimensions can be obtained by changing the molding die.

FIG. 3 shows another embodiment of the present invention, in which a water repellent and an aqueous chitosan salt solution containing fine cellulose fibers were applied as an interfiber binder to a temporarily fixed needle punched web formed in the same manner as in the above embodiment. Glue and chitosan 15g/I
Il, thickness of about 2.0 g with water repellent attached to 8 g/ffl fibers.
Using a degradable non-woven fabric with a weight of 523 g/d, a desired number of small containers (7) are adjacent to each other in an uneven state, and a pair of upper and lower uneven containers are molded using a heat compression molding machine. Heat molding was carried out using a mold at 10 tons of pressure and 100°C for 30 seconds to form a ready-to-use case "Y" in which several small containers were connected. It should be noted that the present invention is not limited to the above embodiments, and food cases of various shapes can be formed by molding by changing the mold.

〔Effect of the invention〕

As described above, the present invention uses chitosan as an interfiber binder, so the cellulose fibers are promoted to decompose by microorganisms in the soil, and are completely decomposed in a short period of time, which also inhibits the activity of microorganisms in the soil. do not have. In addition, this tray has sufficient strength even when food is placed on it, and has excellent water repellency because it prevents the absorption of water such as meat juice and fish juice.

These biodegradable trays are extremely useful in the distribution of fresh foods such as meat, fish, and vegetables, and also allow the garbage generated by general consumers and food processing companies to decompose in a short period of time in landfills. This invention has various effects such as being used as fertilizer, helping to reduce municipal waste, and freeing the environment from pollution.

[Brief explanation of drawings]

Fig. 1 is a schematic cross-sectional view of the biodegradable nonwoven fabric used in the present invention, Fig. 2 is a perspective view of a food tray showing an embodiment of the present invention, and Fig. 3 is a ready-to-use drawing showing an embodiment of the same. It is a perspective view of a case. ■L... Biodegradable nonwoven fabric (2)...
・・・・・・ Rayon fiber (3)・・・・・・・・・
Cross web (4)...Fiber entangled state (5)...Chitosan salt (6)...
... Food tray (7)...Small container" and egg case Figure 1 procedural amendment (released) February 19, 1991

Claims (3)

[Claims] (1) A fiber web composed of cellulose-based natural fibers, cellulose-based regenerated or semi-synthetic fibers, or mixed fibers thereof is bonded with an interfiber binder mainly composed of chitosan salt, and It is made of biodegradable nonwoven fabric with a basis weight of 20 Og/m^2 or more and has an apparent density of 0.2 g/cm^ to which 1 to 10 parts by weight of solid water repellent is attached.
A food tray characterized in that it is formed into the shape of a saucer which is compression molded into two or more parts. (2) The food tray according to claim 1, wherein the water repellent is an aliphatic compound or an aliphatic compound derivative. (3) A food case comprising a pair of upper and lower containers in which a plurality of small containers obtained by compression molding the biodegradable nonwoven fabric according to claim 1 are successively arranged in an uneven manner.