JP2002097301A - Yeast-based biodegradable resin and biodegradable resin composition containing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biodegradable resin, and to provide a biodegradable resin composition having high safety and exhibiting very good biodegradability. SOLUTION: This biodegradable resin comprises yeast which is heated and pressurized to be resinified. The biodegradable resin composition contains the biodegradable resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a resin and a resin composition useful as a biodegradable material.

[0002]

2. Description of the Related Art In recent years, interest in "biodegradable plastics" has been extremely high due to various environmental problems. The term "biodegradable plastic" as used in the present invention means that during use, it can be used in the same manner as ordinary plastic, and after use, it becomes a low molecular compound due to the involvement of microorganisms or moisture in nature after it is used. It means "plastic that decomposes into carbon," and various biodegradable plastics have been developed. Among them, those which use safe natural products include a complex of starch and polyvinyl alcohol, a complex of starch and polycaprolactone, and a chemically modified starch is also known. Little is known about plastic.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a biodegradable resin which can be processed into a molded product or the like in the same manner as a plastic. And a resin composition.

[0004]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a resin obtained by converting yeast powder into a resin by heating and pressing and a resin composition containing the same are similar to plastics. The present inventors have found that they can be formed and formed the present invention.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The yeast used in the present invention is not particularly limited, and baker's yeast, alcoholic yeast, yeast for sake, and brewer's yeast produced in large quantities can be used. Examples of such yeasts include Saccharomyces cerevisiae (IFO 1954, IFO 0309, IAM 4274), Candida utilis (IFO 0619, ATCC 15239),
Truropsis nodaensis (IFO 1942), Truropsis sterata (IFO 1953), Hansenula anomala (IF
O 1150). In addition, yeasts that have been subjected to a treatment such as extraction, such as yeast from which nucleic acids have been extracted (enucleated yeast), are also useful.
The yeast is usually used in the form of powder, but may be used even if it contains water.

[0006] Since yeast is rich in useful substances,
It is an extremely safe natural product used for pharmaceuticals, feed, fertilizers, etc.

However, unlike ordinary plastics, it is not melted only by heating, and even if heated, its properties do not change and thermal decomposition eventually occurs.

[0008] The present inventors have found that individual yeasts are melted and integrated only by heating and further pressurizing, and have accomplished the present invention. Although the details of the mechanism are unknown, it is considered that the yeast cell wall composed of glucan and mannan melts and bonds with each other. Therefore, the term “resinification by heating and pressurization” in the present invention means that powdered yeast is melted and integrated to form a resin.

In the present invention, the temperature and pressure are not particularly limited as long as they are conditions under which the yeast powder is integrated. Usually, the temperature is preferably 80 ° C. or more, and the pressure is preferably 20 kg / cm ² or more. The processing time is not particularly limited, but when the temperature and pressure are low, it is necessary to perform the processing for a long time.

[0010] The biodegradable resin composition of the present invention includes natural high-molecular polysaccharides such as cellulose, lignin, starch, chitin and chitosan, which are industrially produced in large amounts, without departing from the gist of the present invention. Derivatives thereof can also be used in combination. In addition, biodegradable plastics, wood flour, bamboo flour and the like may be used in combination, and if necessary, commonly used plasticizers, foaming agents, dyes and pigments may be added. The amount of these additives may be appropriately determined according to the purpose, but 100 parts by weight of the biodegradable resin composition of the present invention may contain 5 parts of yeast.
It is preferably 0 parts by weight or more.

[0011] The addition of lignin is also useful. Yeast has a very fast biodegradation rate. If the biodegradation rate is too fast depending on the application, it is possible to make the biodegradation rate slower than before mixing by further adding lignin having low hydrophilicity. The amount of lignin is preferably in a range not exceeding 40 parts by weight based on 100 parts by weight of yeast used. When the amount exceeds 40 parts by weight, the effect of inhibiting biodegradation becomes large. Lignin to be used is used for the purpose of suppressing biodegradation, and lignin having low hydrophilicity is advantageous. Lignin having high hydrophilicity is eluted in rainwater or the like, and promotes biodegradation of a molded product. Specifically, the organic sulfur content in lignin is preferably 3% by weight or less. The organic sulfur content indicates the degree of hydrophilicity of lignin and serves as an index of solubility in water.

[0012] The resin composition of the present invention is usually processed into a molded article by transforming yeast into a resin by hot-pressure treatment, but resinification and molding may be performed simultaneously. However, when resinification is insufficient, the molded body is brittle, and it is necessary to adjust the temperature, pressure, and processing time to sufficiently convert the resin.

There is no particular limitation on the resinization apparatus as long as it can be heated and pressurized. For example, a roll mill, an intensive mixer, a single-screw extruder, a twin-screw extruder and the like can be mentioned.

Examples of the forming method include an extrusion method (melt extrusion method), a calender method, and a biaxial stretching method. In addition, surface oxidation, lamination, coating, vacuum deposition, antistatic treatment,
Foaming treatment or the like is also possible.

[0015] The processed composition may be used as a tray for food or the like,
It can be used for conventionally known uses such as a seedling raising pot, a heat insulating material, a vegetation mat, a multi-film, a compost bag, a rose buffer, a drainer, a heat insulating material, a water retention sheet, a tape, and the like.

[0016]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. In the examples, parts and% indicate parts by weight and% by weight, respectively, unless otherwise specified.

Test Items and Test Methods-Strength Test of Molded Product The molded product was dropped freely from a height of 300 cm to a concrete plate having a thickness of 80 mm, and the state was visually observed. -Biodegradation test of the molded product The molded product was buried in the soil, collected after 2 weeks and 4 weeks, and the state was visually determined. ○: The molded product does not retain its shape ×: Little change is observed Test location: Iida-cho, Iwakuni-shi, Yamaguchi Pref.

Example 1 Enucleated yeast powder (trade name: Yeast B manufactured by Nippon Paper Industries Co., Ltd.)
6.0 parts are put into a cylindrical molding machine, and subjected to a heat-pressure treatment using a hot-press machine under the following conditions, and a diameter of 26 mm and a height of 8 mm
To obtain a uniform and black cylindrical molded product. The molded article was subjected to a free fall strength test three times, but no defects or cracks were found in the molded article. Table 1 shows the biodegradability test results of the molded products. Hot pressing conditions Temperature: 150 ° C Pressure: 150 kg / cm ² Holding time: 20 minutes

EXAMPLE 2 The procedure of Example 2 was repeated except that 4.5 parts of enucleated yeast powder and 1.5 parts of lignin powder having an organic sulfur content of 2.4% (trade name: Vanirex HW Nippon Paper Industries Co., Ltd.) were used. A molded product was obtained in the same manner as in Example 1. The molded article was subjected to a free fall strength test three times, but no defects or cracks were found in the molded article.
Table 1 shows the biodegradability test results of the molded products. The organic sulfur content of lignin was determined by the following method.

Organic sulfur content: Inductively coupled plasma emission spectrometer (Seiko Electronics Co., Ltd. SPS1700VR)
I) was used to determine the total sulfur content in lignin. Next, ion chromatography (761 Compact IC manufactured by METROHM)
Was used to determine the inorganic sulfur content in the lignin, and the organic sulfur content was determined from the difference between the total sulfur content and the inorganic sulfur content (% solids).

Example 3 The enucleated yeast was changed to brewer's yeast and the pressure was 30 kg / cm.
^{2. A} brown molded product was obtained in the same manner as in Example 1 except that the holding time was changed to 30 minutes. The molded article was subjected to a free fall strength test three times, but no defects or cracks were found in the molded article. Table 1 shows the biodegradability test results of molded products.
Shown in

Comparative Example 1 A treatment was carried out in the same manner as in Example 1 except that no pressure was applied.
No change was observed in the powdered yeast at a retention time of 20 minutes. The holding time was further extended to 240 minutes, but no change was observed, and the powder was the same as before the treatment.

Comparative Example 2 A treatment was carried out in the same manner as in Example 3 except that no pressure was applied.
No change was observed in the powdered yeast at a retention time of 30 minutes. The holding time was further extended to 240 minutes, but no change was observed, and the powder was the same as before the treatment.

[0024]

[Table 1] Table 1

[0025]

The effects of Comparative Examples 1 and 2 are not changed by heating the yeast. Examples 1 and 3 show that the molded product has practical strength and is biodegradable. Further, Example 2 shows that the incorporation of lignin is useful for adjusting the rate of biodegradation.
From the above, the effect of the present invention is clear.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masahiko okita 1280, Etsu-cho, Gotsu-shi, Shimane Nippon Paper Industries Co., Ltd. In-house Chemical Development Laboratory F-term (reference) 4B065 AA72X BD05 CA55 4J002 AH001 AJ002 GG01 GL00 4J031 BA23 BA26 BC03 BC04 BD11 BD17

Claims (3)

[Claims] 1. A biodegradable resin made of yeast resinified by heating and pressurizing. 2. A biodegradable resin composition comprising the biodegradable resin according to claim 1. 3. The biodegradable resin composition according to claim 2, further comprising lignin.