JPH06104759B2 - Novel composite material film and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention has a novel composite material film having excellent strength and capable of being decomposed by microorganisms in soil, and particularly useful as a film for packaging and agriculture and horticulture, and its The present invention relates to a manufacturing method.

[Conventional technology]

Conventionally, many molded products have been known using natural products such as cellulose, starch, protein and chitosan as raw materials. But,
These have problems that they are weaker in strength than general plastics, and that they dissolve in water or have extremely weak strength in a wet state.

In order to improve these problems, for example, in the case of a molded article using starch, a crosslinking agent such as formaldehyde is reacted, or in the case of a molded article using a protein, a crosslinking agent such as isocyanate or dimethylolurea is reacted, Further, in the case of a molded product using chitosan, complicated operations such as fixing with alkali are performed.

On the other hand, plastic pollution has become a big problem in recent years, and there has been a great desire to develop plastics that can be incorporated into the natural decay cycle.

[Problems to be solved by the invention]

INDUSTRIAL APPLICABILITY The present invention solves, by a simple method, the problem of not being able to maintain its shape and strength in water or in a wet state, which is found in a molded product made of a natural product, and quickly decomposes in soil after use. A pollution-free molding material film is provided.

[Means for solving problems]

As a result of intensive studies on films of various combinations of natural products, the inventors of the present invention have found that when fine cellulose fibers and proteins are dried individually, they cannot maintain their shape and strength in water or in a wet state. Mix them though
The present invention has been accomplished by discovering that a composite is formed only by casting, drying and forming a film, and that it has excellent dry strength and exhibits sufficient strength even in water. Moreover, they were also found to be degraded by microorganisms in the soil.

Examples of the cellulose fiber used in the present invention include cellulose obtained from plants such as wood, straw, cotton, hemp, bamboo and bagasse, hemicellol, lignocellulose, pectocellulose and bacterial cellulose produced by fungi. These cellulose fibers can be made fine by various known methods, but finely beaten cellulose fibers are particularly preferably used.

Regarding the size of the fine cellulose fiber, the length is 3000μ or less, the diameter is 50μ or less, especially the length is 1000μ or less, the diameter is 30
It is preferably μ or less. It is also possible that some of the fibers larger than those mentioned above are mixed in these.

Examples of the protein used in the present invention include those obtained by separating or concentrating from various animal and plant bodies and microorganisms such as casein, albubin, gluten, soybean protein, gelatin and glue. These can be used alone or in combination of two or more.

In the present invention, a plasticizer is used for the purpose of imparting flexibility to the molding material film. The plasticizer used is not particularly limited as long as it is a water-soluble or hydrophilic plasticizer, but glycerin, sorbitol, trimethylolpropane, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol. And the like are preferably used.

The method for producing the composite material film of the present invention will be described. First, the protein is dissolved in water adjusted to a pH suitable for dissolving the protein. The aqueous solution of the obtained protein is mixed with an aqueous dispersion of finely-divided cellulose fibers, and if a plasticizer is used, the plasticizer is mixed therewith. The order of mixing is not limited to this. When the water is evaporated from this mixture and dried, the novel composite material film of the present invention in which the fine cellulose and the protein are composited is obtained.

Although the details of the mechanism of compounding are not clear,
It is presumed that the hydroxyl group or carboxyl group in cellulose and the amino group or carboxyl group in protein are chemically bonded to each other during drying to form a complex.

The drying temperature is room temperature to 200 ° C, particularly preferably 50 to 160
C is used.

When adjusting the above mixture, it is possible to add additives such as a colorant, a filler and a reinforcing agent, if necessary.

[Action]

When the fine cellulose fibers and the protein used in the present invention are each formed into a molded film independently, they are dissolved in water or in a wet state, and even if the shape is maintained, only very weak strength can be obtained, but they are mixed. It is cast, dried and formed into a film to form a composite, which retains its shape even in water and exhibits sufficient wet strength. Also, since it uses natural raw materials, it is easily decomposed by microorganisms in the soil.

〔Example〕

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. In these examples, all parts are parts by weight. The tensile strength was measured according to ASTM D882-81. The wet tensile strength was measured immediately after taking out the sample after immersing the sample in water at 23 ° C. for 24 hours. The microbial degradability test was carried out by burying the sample in a plastic container containing soil, leaving it at 23 ° C. and 95 to 100% RH for 2 months, excavating the sample, and observing the state of its degradation.

Example 1 Fine cellulose fibers obtained by beating softwood bleached pulp 10
0 parts of an aqueous dispersion (concentration 4 wt%) is mixed with an aqueous solution of 10 parts of gelatin (concentration 5 wt%, pH 6). This was cast on a glass plate and blow-dried at 70 ° C. for 15 hours to obtain a semitransparent film having a thickness of 60 to 70 μm.

引針strength at the obtained film dried 1102kg / cm ^2, a tensile strength of 104 kg / cm ² of wet, the biodegradability test was degraded to an extent that does not stop the original form.

Examples 2 to 6 Fine cellulose fibers obtained by beating softwood bleached pulp 10
0 parts of an aqueous dispersion (concentration 4 wt%) was mixed with a predetermined amount of an aqueous solution of gelatin (concentration 5 wt%, pH 6) and 50 parts of glycerin,
A film was produced in the same manner as in Example 1.

The tensile strength of the obtained film is shown in Table 1.

Further, in the microbial decomposition test, all the films were decomposed to the extent that the original shape was not retained.

Comparative Example 1 Fine cellulose fibers obtained by beating softwood bleached pulp 10
A film was obtained by mixing 0 parts of an aqueous dispersion (concentration 4 wt%) and 50 parts of glycerin and forming a film in the same manner as in Example 1.

The tensile strength of the obtained film is shown in Table 1.

Comparative Example 2 100 parts gelatin aqueous solution (concentration 5 wt%, pH 6) and glycerin
50 parts were mixed, and a film was obtained in the same manner as in Example 1.

The tensile strength of the obtained film is shown in Table 1.

Example 7 Fine cellulose fiber obtained by beating softwood bleached pulp 10
0 parts of an aqueous dispersion (concentration 4 wt%) was mixed with an aqueous solution of 10 parts of dairy casein (concentration 3 wt%, pH 8) and 50 parts of glycerin,
A film was produced in the same manner as in Example 1.

The resulting film,引脹strength 1003kg / cm ² at the time of drying, a引脹strength 104 kg / cm ² of wet, the biodegradability test was degraded to an extent that does not stop the original form.

Comparative Example 3 An aqueous solution of 100 parts of dairy casein (concentration 3 wt%, pH 8) and 50 parts of glycerin were mixed and formed into a film in the same manner as in Example 1 to obtain a film.

The obtained film had a tensile strength when dried of 167 kg / cm ² , but a tensile strength when wet was too weak to be measured.

Example 8 Fine cellulose fiber obtained by beating softwood bleached pulp 10
0 parts of an aqueous dispersion (concentration 4 wt%) is mixed with an aqueous solution of 20 parts dairy casein (concentration 3 wt%, pH 8) and 50 parts glycerin. This is cast on a glass plate and heated at 70 ° C for 5 hours, then
The film was blown and dried at 160 ° C. for 1 hour to obtain a semitransparent film having a thickness of 60 to 70 μm.

The resulting film tension during dry strength 861kg / cm ^2, a tensile strength of 215 kg / cm ² of wet, the biodegradability test was degraded to an extent that does not stop the original form.

Example 9 Fine cellulose fiber obtained by beating softwood bleached pulp 10
0 parts of an aqueous dispersion (concentration 4 wt%) is mixed with 10 parts of an aqueous solution of soy protein (concentration 3 wt%, pH 8) and 100 parts of ethylene glycol. This was cast on a glass plate and blow-dried at 70 ° C. for 5 hours and then at 130 ° C. for 1 hour to obtain a semitransparent film having a thickness of 60 to 70 μm.

The film obtained had a tensile strength of 952 kg / cm ² when dried and a tensile strength of 219 kg / cm ² when wet, and was decomposed to such an extent that the original shape was not retained in the microbial degradability test.

〔The invention's effect〕

The composite material film obtained by the present invention has excellent dry strength and sufficient wet strength, and also has the characteristic that it does not produce harmful substances even after being decomposed because it is made from a natural product. It exhibits excellent effects as a pollution-free molding material film in the fields of packaging film, agricultural film and the like.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Issei Yoshihara 2-3-3 Hananomiyacho, Takamatsu City, Kagawa Prefecture, Shikoku Institute of Industrial Technology (72) Inventor Takamasa Kubo, Hana, Takamatsu City, Kagawa Prefecture 2-3-3 Miyanomachi, Shikoku Institute of Industrial Technology, Institute of Industrial Technology (72) Inventor Kunio Kanaoka, 1515 Nakatsu-cho, Marugame, Kagawa Prefecture, Research Institute, Okura Industrial Co., Ltd. (72) Kazuo Kondo, Marugame, Kagawa Prefecture 1515 Nakatsu-cho, Nakatsu, Okura Industrial Co., Ltd. Research Institute (72) Inventor Satoshi Maruyama 1515 Nakatsu-cho, Marugame-shi, Kagawa Okura Industrial Co., Ltd. Research Institute (72) Kenji Tateishi 1515, Nakatsu-cho, Marugame, Kagawa Inside the Institute of Industrial Co., Ltd. (72) Inventor Akihiko Ueda 1515 Nakatsu-cho, Marugame City, Kagawa Okura Industrial Co., Ltd. Inside Examiner, Hiroshi Josho (56) References JP-A-48-34962 (JP, A) JP-A-54-133549 (JP, A)

Claims (4)

[Claims] 1. A novel composite material film obtained by mixing an aqueous dispersion of fine cellulose fibers and an aqueous protein solution and casting the mixture. 2. A novel method for producing a composite material film, which comprises mixing an aqueous dispersion of fine cellulose fibers with an aqueous protein solution, casting and drying. 3. A novel composite material film obtained by mixing an aqueous dispersion of fine cellulose fibers, an aqueous protein solution, and a plasticizer and casting the mixture. 4. A method for producing a novel composite material film, which comprises mixing an aqueous dispersion of fine cellulose fibers, an aqueous protein solution, and a plasticizer, casting and drying.