JPH10101919A - Biodegradable resin and method for controlling biodegradation rate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely control the biodegradation rate of a biodegradable resin by compounding it with a specified amt. of a nucleating agent. SOLUTION: At least one resin selected from among polycaprolactone, polylactic acid, a polyhydroxybutyrate, polyglutamic acid, etc., is used as a biodegradable resin. 100 pts.wt. biodegradable resin is compounded with 0.01-5 pts.wt., pref. 0.1-0.5 pt.wt., nucleating agent selected from among silica, alumina, sodium succinate, sodium glutarate, dibenzylidenesorbitol, polystyrene, etc. The resultant compsn. is melt kneaded on a kneading extruder to give a biodegradable resin with a high biodegradation rate. The biodegradation rate of the resin can be controlled by adjusting the compounding ratio of the nucleating agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a biodegradable resin and a method for controlling a biodegradation rate, and more particularly, to a biodegradable resin in which a biodegradable resin is blended with a nucleating agent to increase the biodegradation rate. The present invention relates to a resin and a biodegradation rate control method.

[0002]

2. Description of the Related Art Since plastic waste does not decompose after disposal, environmental pollution by plastic waste is a problem. Therefore, in recent years, interest in biodegradable resins that are degraded by enzymes and microorganisms has been increasing, and various molded articles such as disposable containers and agricultural films using biodegradable resins have been proposed. In addition, many studies for improving the moldability and various physical properties of biodegradable resins have been reported (for example, JP-A-8-73574 and JP-A-8-3432).

On the other hand, in order to increase the degradability of the biodegradable resin after disposal, it is necessary to increase the decomposition rate of the biodegradable resin. Therefore, JP-A-6-143407 discloses that
A method has been disclosed in which a physical stress is applied to polycaprolactone as a biodegradable resin to refine the crystal structure and increase the biodegradation rate.

[0004] Further, a biodegradable resin composition in which the decomposition rate of the biodegradable resin is increased by adding a highly degradable substance such as starch or a compound having a relatively low molecular weight to the biodegradable resin is also considered. (JP-A-8-92419,
Japanese Patent Publication No. 6-78475).

However, as described in Japanese Patent Application Laid-Open No. 6-143407, in the method of applying a physical stress to a compact to refine the crystal, the biodegradation rate is increased, but the physical stress is reduced during the production. A complicated process for adding must be performed, and there is a problem that productivity of a resin molded product is reduced. Further, since the crystal is refined by applying a physical stress, the shape of an applied product is restricted. In other words, a flat molded product such as a sheet or a film can apply physical stress uniformly, but a molded product having a three-dimensional shape cannot apply physical stress uniformly, which makes application difficult. Met.

On the other hand, in a method of increasing the biodegradation rate by blending a substance having excellent degradability such as starch or a compound having a relatively low molecular weight, the biodegradation rate must be increased unless a considerable amount of starch or low molecular weight compound is blended. Was difficult to increase.

For example, in Japanese Patent Application Laid-Open No. Hei 8-92419, 20 to 70% by weight of a fat and oil modified starch is blended with 80 to 30% by weight of a biodegradable resin such as an aliphatic polyester or polylactic acid. In JP-A-6-78475,
The biodegradable aliphatic polyester contains 10 to 50% by volume of an inorganic or organic filler.

However, when the amount of starch or low molecular weight compound is increased, the moldability of the biodegradable resin and various physical properties of the obtained molded article may be greatly impaired.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the necessity of performing a complicated process for applying a physical stress, to apply the present invention to products having various shapes, and to improve the moldability and the like. It is an object of the present invention to provide a biodegradable resin capable of increasing the biodegradation rate without causing deterioration in various physical properties, and a method for controlling the biodegradation rate.

[0010]

Means for Solving the Problems The inventors of the present application have conducted intensive studies to achieve the above object, and as a result, have found that if a nucleating agent is added to a biodegradable resin, the rate of biodegradation can be increased. Invented the invention.

That is, the first aspect of the present invention is a biodegradable resin containing a nucleating agent. The invention according to claim 2 is a biodegradable resin characterized by containing a nucleating agent in an amount of 0.01 to 5 parts by weight per 100 parts by weight of the biodegradable resin.

The third aspect of the present invention is a method for controlling a biodegradation rate by blending a nucleating agent with a biodegradable resin and adjusting the amount of the nucleating agent. Hereinafter, details of the present invention will be described.

In the present invention, the biodegradable resin includes
There is no particular limitation, and aliphatic polyesters such as polycaprolactone, polylactic acid, polyhydroxybutyrate, polyhydroxyvalerate, polybutylene succinate adipate; polyamides such as polyglutamic acid and polycaprolactam; and resins of these resins A conventionally known general biodegradable resin such as a copolymer can be used. These biodegradable resins may be used alone or in combination of two or more.

Further, in the biodegradable resin of the present invention,
In addition to the biodegradable resin, another general resin, that is, an appropriate resin having no biodegradability may be mixed as long as the object of the present invention is not impaired.

In the present invention, the crystal nucleating agent includes:
A commonly used crystal nucleating agent can be used,
Although not particularly limited, for example, metal fine particles,
Examples thereof include inorganic materials such as alumina, silica, talc, calcium oxide, and carbon black; inorganic salts of organic acids such as sodium succinate, sodium glutarate, and aluminum benzoate; sorbitol derivatives; and organic substances such as polystyrene.

The proportion of the crystal nucleating agent is not particularly limited, but is preferably 0.01 to 5 parts by weight, more preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the biodegradable resin.
It is in the range of 1 to 0.5 parts by weight. When the compounding ratio of the crystal nucleating agent is less than 0.01 part by weight, the biodegradation rate is not sufficiently increased, and the effect of compounding the crystal nucleating agent may not be obtained. Even if the compounding amount exceeds 5 parts by weight, This is because the decomposition rate may not be further increased.

The method of compounding the nucleating agent is not particularly limited, and any appropriate method can be adopted as long as the nucleating agent can be sufficiently dispersed in the biodegradable resin.
For example, the biodegradable resin and the crystal nucleating agent may be kneaded using a roll mill or a kneader, or both may be kneaded in a kneading extruder. Alternatively, the nucleating agent may be mixed with the biodegradable resin by dissolving the biodegradable resin in a solvent, mixing the nucleating agent, and removing the solvent by volatilization and drying.

In the method for controlling the biodegradation rate according to the present invention, when the nucleating agent is mixed with the biodegradable resin, the biodegradation rate is controlled by adjusting the amount of the nucleating agent. That is, as is clear from the examples described later, the biodegradation rate of the biodegradable resin according to the present invention changes depending on the amount of the crystal nucleating agent. Therefore, the biodegradation rate of the biodegradable resin can be easily and reliably controlled only by adjusting the blending ratio of the crystal nucleating agent.

In the biodegradable resin of the present invention, the reason why the rate of biodegradation can be increased by blending a nucleating agent is to disperse the nucleating agent in the biodegradable resin to form the biodegradable resin. It is considered that the crystallization proceeds from the nucleating agent as a starting point, so that the crystals in the biodegradable resin molded product can be refined, thereby increasing the biodegradation rate.

[0020]

The present invention will be clarified by the following non-limiting examples.

Example 1 Polycaprolactone (trade name, manufactured by Daicel Chemical Industries, Ltd.)
100 parts by weight of Praxel H7) were melted in a plastmill at 180 ° C., and dibenzylidene sorbitol (Ec Chemical Co., product number: EC-1-55) was used as a crystal nucleating agent.
0.1 part by weight was added, and the mixture was kneaded at a speed of 60 rotations per minute for 5 minutes, and then formed into a sheet having a thickness of 1 mm using a hot press forming machine. The obtained sheet was punched into a circular shape having a diameter of 30 mm to obtain a sample of Example 1.

[0022] except for changing the mixing ratio of Example 2 dibenzylidene sorbitol 0.2 parts by weight, in the same manner as in Example 1 to obtain a sample of Example 2.

[0023] except for changing the mixing ratio of Example 3 dibenzylidene sorbitol 0.5 parts by weight, in the same manner as in Example 1 to obtain a sample of Example 3.

[0024] except for changing the mixing ratio of Example 4 dibenzylidene sorbitol to 1 part by weight, in the same manner as in Example 1 to obtain a sample of Example 4.

[0025] Except for not blending the comparative example 1 dibenzylidene sorbitol, in the same manner as in Example 1 to obtain a sample of Comparative Example 1.

Evaluation of Examples and Comparative Examples In order to evaluate the biodegradability of the samples obtained in the above Examples and Comparative Examples, the following Experiments 1 and 2 were performed.

Experiment 1: A lipase (R) capable of decomposing 0.0833 μg of 1,2-o-dilauryl-rac-glycero-3-glutaric acid resorufin ester (manufactured by Boehringer Mannheim, lipase measurement kit) in 1 ml per minute .Arrhizuslipaze, SIGMA) solution and 50 μl of a 0.2 M phosphate buffer solution (pH =
7.0) 17 ml and a 0.1% by weight surfactant solution (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name: Plysurf A210)
G) 1 ml, 17 ml of distilled water, and a sample
1 Erlenmeyer flask and reacted at 30 ° C. for 16 hours.
The weight difference before and after the reaction, that is, the weight loss value was measured, and the biodegradation rate was calculated from the weight loss value. That is, biodegradation rate = (weight loss value μg before and after reaction) / (7.065 cm
^The biodegradation rate was calculated at ( ² × 16 hours). The results are shown in FIG.

Experiment 2: A 50 ml sample of seawater collected on the surface of the sea surface at Sakai Port filtered through a plankton net (mesh 50 μm) was added to an inorganic salt-added aqueous solution A shown in Table 1 below.
The sample was immersed in all of the samples to 25 ° C. for 12 days at 25 ° C., the weight loss value of the sample before and after immersion was measured, and the biodegradation rate was calculated based on the weight loss value. That is, the biodegradation rate was calculated by the biodegradation rate (μg / cm ² · ratio) = (μg weight loss value of sample before and after immersion) / (7.065 cm ² × 12 days). The results are shown in FIG.

[0029]

[Table 1]

In FIGS. 1 and 2, the horizontal axis represents the number of nucleating agents, and the horizontal axis corresponds to the nucleating agent mixing ratio in Examples 1 to 4 and Comparative Example 1. That is, the case where the compounding ratio of the crystal nucleating agent is 0 corresponds to Comparative Example 1. For example, the compounding ratio of the crystal nucleating agent 0.5 part corresponds to Example 3.

As is clear from FIGS. 1 and 2, in each of Experiments 1 and 2, Comparative Examples 1 to 4 in which dibenzylidene sorbitol was blended as a nucleating agent were used.
It can be seen that the biodegradation rate is increased as compared with. In particular, it can be seen that by blending the nucleating agent in a ratio of 0.1 part by weight to 0.5 part by weight, the biodegradation rate can be effectively increased with the amount of the nucleating agent. Also, it can be seen that when 1 part by weight of the crystal nucleating agent is blended, the biodegradation rate is not so different from that when 0.5 part by weight is blended.

Therefore, preferably, when the nucleating agent is blended in a ratio of 0.1 to 0.5 part by weight with respect to 100 parts by weight of the biodegradable resin, the amount of the nucleating agent used is not greatly increased. It can be seen that the biodegradation rate can be increased.

It can also be seen that the biodegradation rate can be reliably controlled by changing the amount of the crystal nucleating agent as described above. That is, in order to increase the biodegradation rate, the biodegradation is performed by adjusting the compounding ratio of the nucleating agent within a range of 0.5 part by weight or less based on 100 parts by weight of the biodegradable resin. It can be seen that the speed can be reliably controlled.

[0034]

As described above, according to the first aspect of the present invention, the rate of biodegradation can be effectively increased, possibly because the crystal nucleating agent is blended to achieve finer crystals.
In the conventional method of increasing the biodegradation rate by refining crystals,
In the production, a complicated step of applying a physical stress had to be performed, whereas in the invention according to claim 1, the biodegradation rate could be effectively increased by adding the nucleating agent. Such a complicated process need not be performed. That is, it is possible to provide a biodegradable resin product having excellent biodegradability without performing a complicated process requiring a device for applying stress.

In addition, the conventional method of increasing the biodegradation rate by adding a substance having excellent biodegradability, such as starch or a low molecular weight compound, utilizes the degradability of these substances themselves. In order to increase the decomposition rate, a considerable amount of starch and low molecular weight compounds had to be incorporated. On the other hand, in the invention of claim 1, the nucleating agent does not increase the biodegradation rate due to its own biodegradability,
The biodegradation rate of the biodegradable resin can be increased only by adding a very small amount of the nucleating agent. Therefore, in the biodegradable resin according to the first aspect of the present invention, since the amount of the crystal nucleating agent used can be extremely small, the moldability and various physical properties are not impaired.

According to the second aspect of the present invention, since the nucleating agent is blended at a ratio of 0.01 to 5 parts by weight per 100 parts by weight of the biodegradable resin, the biodegradable resin has an effect on the biodegradation rate. It is possible to provide a biodegradable resin product having excellent moldability and physical properties, because it can be increased only by adding a very small amount of a crystal nucleating agent of 5 parts by weight or less.

According to the third aspect of the present invention, since the biodegradation rate is controlled by adjusting the blending ratio of the nucleating agent, the biodegradable resin in a molten state is required for the production of a biodegradable resin product. It is possible to easily and reliably control the biodegradation rate only by changing the amount of the crystal nucleating agent mixed with the resin. That is, it is possible to reliably provide a biodegradable resin product having a desired biodegradation rate without performing special equipment or complicated steps.

[Brief description of the drawings]

FIG. 1 is a diagram showing the results of Experiment 1 performed in Examples and showing the relationship between the number of crystal nucleating agents and the biodegradation rate.

FIG. 2 shows the results of Experiment 2 performed in Examples, and shows the relationship between the number of nucleating agents and the biodegradation rate.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 77/12 C08L 77/12 101/00 101/00

Claims (3)

[Claims] 1. A biodegradable resin comprising a nucleating agent. 2. The biodegradable resin according to claim 1, comprising a nucleating agent in an amount of 0.01 to 5 parts by weight per 100 parts by weight of the biodegradable resin. 3. A method for controlling a biodegradation rate, comprising blending a nucleating agent with a biodegradable resin and adjusting the amount of the nucleating agent to control the rate of biodegradation.