JP3078478B2 - Composition for biodegradable molded article and method for producing biodegradable molded article - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a composition for a biodegradable product containing a gelatinized starch and a method for producing the biodegradable product. More specifically, a composition for a biodegradable molded article in which the viscosity is reduced at the time of starch gelatinization by adding an oxidizing agent to the starch to improve the fluidity at the time of molding, and the fluidity at the time of molding are improved. The present invention relates to a method for producing a biodegradable molded product having good processability.

[0002]

2. Description of the Related Art It has been proposed to utilize gelatinized starch as a biodegradable component. For example, JP-A 1-2170
No. 02 (referred to as Prior Art 1) discloses a biodegradable composition containing a gelatinized starch as a main component. For example, Japanese Patent Application Laid-Open No. 2-142228 (hereinafter referred to as Prior Art 2) discloses a biodegradable composition which is a complex of a gelatinized starch and a biodegradable resin.

[0003] Biodegradable resin compositions using various modified starches as starches are also known. For example, Japanese Unexamined Patent Publication
-56543 (referred to as prior art 3) discloses a biodegradable composition comprising a starch graft copolymer. JP-A-3-70752 (hereinafter referred to as Prior Art 4) discloses a biodegradable composition containing an anionic modified starch. JP-A-3-74445 (hereinafter referred to as Prior Art 5) discloses a biodegradable composition containing a cationically modified starch. JP-A-3-74446 (referred to as prior art 6) discloses a biodegradable composition containing starch chemically modified to contain at least one of a hydroxyalkyl group, an alkyl ether group and an ester group as a starch component. Is disclosed.

[0004]

The important physical properties of a biodegradable composition are biodegradability, strength, elongation and the like. However, in addition to these physical properties, it is also practically important that the fluidity at the time of heating and melting when processing into a molded article is good. In practical use of the biodegradable composition, it is preferable that the composition has the same fluidity as a synthetic resin conventionally processed into a molded article, for example, polystyrene or the like. However,
Heretofore, in developing starch-based biodegradable compositions, much attention has been paid to fluidity.

[0005] The gelatinized starch disclosed in Prior Art 1 and 2, and the processed starch described in Prior Art 3 to 6, have insufficient fluidity during heating and melting. For this reason, it was possible to obtain a molded product having a simple shape, for example, a sheet, by extrusion molding to some extent. However, when molding an article having a complicated shape by injection molding, it was difficult to obtain a desired product due to poor fluidity. It was difficult to obtain a shaped article.

Accordingly, a first object of the present invention is a biodegradable composition using a gelatinized starch, which has improved fluidity during heating and melting, and is easy to mold. To provide things. Further, a second object of the present invention is to provide a method for producing a biodegradable molded article containing a gelatinized starch, which has improved fluidity during heating and melting and can be easily molded.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a composition for a biodegradable molded article characterized by containing a gelatinized starch which has been oxidized. The composition for a biodegradable molded article of the present invention includes an embodiment comprising an oxidized starch gelatinized product and an embodiment comprising an oxidized starch gelatinized product and a biodegradable resin.

[0008] The present invention further provides a starch and water and an oxidizing agent,
Alternatively, the present invention relates to a method for producing a biodegradable molded product, which comprises heating and mixing with water, a plasticizer and an oxidizing agent, or a plasticizer and an oxidizing agent, and molding the resulting mixture into a desired shape.
Further, the present invention is obtained by heating and mixing starch with water, an oxidizing agent and a biodegradable resin, or water, a plasticizer, an oxidizing agent and a biodegradable resin, or a plasticizer, an oxidizing agent and a biodegradable resin. The present invention relates to a method for producing a biodegradable molded product, which comprises molding a mixture into a desired shape.

Composition for Biodegradable Molded Article The composition for biodegradable molded article of the present invention contains gelatinized starch which has been oxidized. The oxidized starch gelatinized product can be obtained by performing starch oxidizing treatment and gelatinization in parallel. Any starch can be used as a raw material for the oxidation treatment and gelatinization without any particular limitation. For example, raw starches such as potato starch, corn starch, potato starch, tapioca starch, sago palm starch, rice starch, wheat starch, and processed starches such as various esterified starches, etherified starches and the like can be mentioned.

The oxidation treatment and gelatinization of starch can be carried out, for example, by heating and mixing starch with water and an oxidizing agent or with water, a plasticizer and an oxidizing agent. By coexisting the oxidizing agent, the oxidizing treatment can be performed simultaneously with the starch gelatinization, and the fluidity of the obtained composition at the time of heating and melting can be improved. As the oxidizing agent, for example, a peroxide can be used. As the peroxide, for example, a persulfate or hydrogen peroxide selected from the group consisting of potassium persulfate, ammonium persulfate, and sodium persulfate can be used. The amount of oxidizing agent used is starch (dry matter basis) 1
It is appropriate that the amount is in the range of 0.01 to 0.50 parts by weight per 00 parts by weight. Preferably, 0.02 to 0.10
It is in the range of parts by weight. The type and amount of the oxidizing agent can be appropriately changed in consideration of the fluidity of the obtained composition.

As mentioned above, starch is added to an oxidizing agent,
By heating and mixing in the presence of water, a plasticizer, or water and a plasticizer, a starch gelatinized product is obtained. Gelatinization of starch can be performed in the presence of water alone or a plasticizer alone. Also,
Starch can be gelatinized even in the presence of water and a plasticizer,
In this case, the amount of water used can be reduced, which is effective in preventing foaming during molding. Furthermore, there is also an advantage that mixing and molding of the starch gelatinized product and the biodegradable resin can be facilitated by including a plasticizer in the gelatinized product.

The plasticizer used for gelatinization is not particularly limited as long as it can gelatinize starch and can impart plasticity to the gelatinized product, and examples thereof include a high-boiling plasticizer having biodegradability. Examples of such plasticizers include ethylene glycol, propylene glycol, glycerin, sorbitol, polyethylene glycol, polypropylene glycol and the like.

When water is used for gelatinization, it is appropriate to use 10 to 50 parts by weight of water per 100 parts by weight of starch (dry matter basis) from the viewpoint of sufficiently gelatinizing the starch. More preferably, 10 to 20 parts by weight of water is used per 100 parts by weight of starch (based on dry matter), from the viewpoint of sufficiently gelatinizing the starch and preventing foaming when added to the biodegradable composition and molded. Appropriate.

When water and a plasticizer are used for gelatinization, 0.1 to 40 parts by weight of starch (based on dry matter) is used.
It is appropriate to use 1 part by weight of water and 1 to 100 parts by weight of a plasticizer from the viewpoint that starch can be sufficiently gelatinized and sufficient plasticity can be imparted to the gelatinized product. More preferably, 0.1 to 100 parts by weight of starch (based on dry matter) is used.
The use of 20 parts by weight of water and 5 to 40 parts by weight of a plasticizer can sufficiently gelatinize the starch, prevent foaming when added to the biodegradable composition and molding, and provide a gelatinized material. It is appropriate from the viewpoint that appropriate plasticity can be imparted.

When only a plasticizer is used for gelatinization, it is preferable to use 1 to 100 parts by weight of a plasticizer per 100 parts by weight of starch (based on dry matter) to sufficiently gelatinize the starch,
It is also suitable from the viewpoint that sufficient plasticity can be imparted to the gelatinized product. Further preferably, starch (on a dry matter basis)
The use of 5 to 40 parts by weight of a plasticizer per 100 parts by weight is appropriate from the viewpoint that the starch can be sufficiently gelatinized and that the gelatinized product can be imparted with appropriate plasticity.

[0016] The gelatinization of starch generally means a state in which, when heated in the presence of water or the like, starch granules irreversibly swell or dissolve, lose crystallinity and birefringence, and increase in viscosity. The starch gelatinized product in the present invention refers to one that does not substantially exhibit crystallinity and birefringence. The loss of crystallinity and birefringence can be determined by observing the starch granules with a polarizing microscope and observing the presence of a polarizing cross crossing at the center of formation of ungelatinized starch.

The heating and mixing for oxidizing and gelatinizing the starch can be appropriately determined depending on the type of starch, the type of plasticizer when a plasticizer is used, and the amounts of water and plasticizer added. For example, it is appropriate to carry out at 60 to 220 ° C. for 10 to 60 minutes. The heating and mixing can be performed using, for example, a pressure kneader or an extruder. By heating and mixing, the composition for a biodegradable molded article of the present invention, which is made of an oxidized starch gelatinized product, can be obtained. The obtained composition is pelletized, for example, and the pellet can be used in the production of a biodegradable molded article.

The composition for a biodegradable molded article of the present invention containing an oxidized starch gelatinized product and a biodegradable resin is, for example, a pellet-like oxidized starch gelatinized product and a biodegradable resin. It can be obtained by mixing. The biodegradable resin used in the present invention is not particularly limited.
It is sufficient that the resin itself has biodegradability, and thermoplastic resin is appropriate in consideration of moldability. Resins belonging to any of a chemically synthesized resin, a microbial resin, a natural product-based resin and the like may be used. For example, aliphatic polyesters (for example, polycaprolactone, polylactic acid, polyhydroxybutyrate / valerate copolymer, etc.), polyvinyl alcohol, acetylcellulose and the like can be mentioned.

The composition for a biodegradable molded article of the present invention may optionally contain additives in addition to the above-mentioned components. Examples of the additives include vegetable protein, pulp, ultraviolet stabilizer, fungicide, herbicide, fertilizer, antioxidant, surfactant, pigment and the like.

Process for Producing a Biodegradable Molded Product The process for producing a biodegradable molded product of the present invention is characterized in that, when the biodegradable molded product comprises only oxidized starch gelatinized product, As in the case of the product, the starch is heated and mixed with water and an oxidizing agent, or with water, a plasticizer and an oxidizing agent, or a plasticizer and an oxidizing agent, and then the resulting mixture is formed into a desired shape. it can. The molding into a molded article can be performed using, for example, injection molding, extrusion molding, or the like. In addition, in the production of a biodegradable molded article containing an oxidized starch gelatinized product and a biodegradable resin, the starch is treated with water, an oxidizing agent and a biodegradable resin, or water, a plasticizer, an oxidizing agent and a biodegradable resin, Alternatively, it can be carried out by heating and mixing with a plasticizer, an oxidizing agent and a biodegradable resin, and molding the resulting mixture into a desired shape. Molding into a molded article can be performed using, for example, injection molding, extrusion molding, or the like, similarly to the above.

In each case, starch, oxidizing agent, plasticizer,
As the biodegradable resin, the same one as in the case of the composition for a biodegradable molded article can be used. In addition, the amounts of the oxidizing agent, the plasticizer, and the water used for the starch can be the same as in the case of the composition for a biodegradable molded article. The shape of the molded article is not particularly limited, and examples include molded articles for any use that can utilize biodegradability, such as containers for detergents, disposable tableware, and the like.

[0022]

According to the present invention, there is provided a biodegradable composition using a gelatinized product of starch, which has improved fluidity during heating and melting and is easy to mold. Can be provided. In particular, the composition for a biodegradable molded article of the present invention can be molded by injection molding. Further, according to the present invention, it is possible to provide a method for producing a biodegradable molded article containing a gelatinized starch product, which has improved fluidity during heating and melting and facilitates molding. In the production method of the present invention, molding can also be performed by injection molding.

The improvement of the fluidity according to the present invention can be carried out at low cost because a small amount of an oxidizing agent can be used in parallel with the gelatinization (an additional step is not required). When complexed with a biodegradable resin that is more expensive than starch or gelatinized starch, the flowability is improved, and the compounding ratio of gelatinized starch (oxidized) can be increased. In addition, the price of the biodegradable resin molded product can be reduced. The oxidized starch gelatinized product of the present invention has improved fluidity, and as a result, can be blended with various composite compositions at a high rate. As a result, the biodegradability of the composite composition can be promoted (because the biodegradability of the starch gelatinized product is higher than that of the biodegradable resin), and the application range of the biodegradable composite composition can be expanded to the level of general-purpose resins. It becomes possible.

[0024]

The present invention will be further described with reference to the following examples. Examples 1 to 3 To 100 parts by weight of corn starch (based on dry matter), 15 parts by weight of water, and 20 parts by weight of glycerin, 0.02 parts by weight, 0.06 parts by weight, or 0.10 parts by weight of ammonium persulfate was added. These mixtures were mixed for 1 minute each at a low speed, a medium speed, and a high speed using a rigid mixer (Kanto mixer manufactured by Kanto Blender Co., Ltd.). The mixture was extruded into a rod having a diameter of about 4 mm using a uniaxial extruder (plastograph) under the following conditions. Then use scissors about 0.5-1c in length
m in the form of pellets.

Screw L / D25 (uniaxial) Rotational speed 60 rpm Die 6φ Temperature ZONE1: ZONE2: ZONE3 = 50 ° C.:13
0 ° C: 50 ° C

Comparative Example 1 A pellet composition was obtained in the same manner as in Example 1 except that potassium persulfate was not added. Comparative Example 2 A commercially available polystyrene ret (Stylon 600 manufactured by Asahi Kasei Corporation) was used.

[0027]

[Table 1]

The thermal fluidity of the pellets prepared in Examples 1 to 3 and Comparative Examples 1 and 2 was examined by a temperature rising method using a flow tester (CFT500C manufactured by Shimadzu Corporation). As a measuring method, a die having a length of 2 cm and a diameter of 1 mm was used, the load was set to 50 kgf, and the temperature was increased at a rate of 5 ° C./min.
It measured in the range of ° C-200 ° C. FIG. 1 shows the results of the melt viscosity at each temperature, and FIG. 2 shows the results of the flow rate (shear rate). That is, in Examples 1 to 3 in which only a small amount of the oxidizing agent was added, the melt viscosity was reduced and the fluidity was improved as compared with Comparative Example 1 in which the oxidizing agent was not added. It was found to be equivalent to general purpose polystyrene.

Example 4 100 parts by weight of corn starch (based on dry matter), 20 parts by weight of water, 15 parts by weight of polyethylene glycol, and 0.04 parts by weight of potassium persulfate were placed in a Henschel mixer (manufactured by Mitsui Miike Kakoki Co., Ltd.) and the mixture was mixed at 600 rpm. Stir and mix for minutes.
This was pelletized using the following extruder and conditions. Extruder name Toyo Seiki Co., Ltd. Labo Plastomill Model Twin screw extruder 2D25S Screw L / D = 25 (two screws) Temperature ZONE 1: ZONE 2: ZONE 3: ZONE 4 = 50 ° C: 60
° C: 120 ° C: 100 ° C Die 3φ Pelletizer Cold cut pelletizer made by Toyo Seiki Co., Ltd. PETEC type

The starch pellets obtained under the above conditions were injection-molded under the following conditions using an injection molding machine manufactured by Nissei Resin Engineering Co., Ltd. and a flowerpot molding die to obtain a molded product. Heating cylinder set temperature Nozzle 150 ° C Front 155 ° C Middle
145 ° C Rear 120 ° C Mold surface temperature 20 ° C Injection time 3 seconds

Comparative Example 3 Pellets and molded articles were obtained in the same manner as in Example 4 except that potassium persulfate was not added.

[0032]

[Table 2]

Example 5 50 parts by weight of the pellets obtained in Example 4 and polycaprolactone (Placcel H7) 5 manufactured by Daicel Chemical Industries, Ltd.
And 0 parts by weight, and subjected to an injection molding test under the following conditions using an injection molding machine and a flowerpot molding die manufactured by Nissei Plastics Engineering Co., Ltd. to obtain a molded product. Heating cylinder set temperature Nozzle 150 ° C, front 155 ° C, middle
145 ° C, rear 120 ° C Mold surface temperature 20 ° C Injection time 3 seconds

Comparative Example 4 A molded product was obtained in the same manner as in Example 5 except that potassium persulfate was not added.

[0035]

[Table 3]

[Brief description of the drawings]

FIG. 1 shows the melt viscosity at each temperature of each composition of Examples 1 to 3 and Comparative Examples 1 and 2.

FIG. 2 shows a flow rate (shear rate) at each temperature of each composition of Examples 1 to 3 and Comparative Examples 1 and 2.

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08B 31/18 CA (STN)

Claims (12)

(57) [Claims] 1. A composition for a biodegradable molded article, comprising a gelatinized oxidized starch and a biodegradable resin. 2. The starch gelatinized product subjected to the oxidation treatment is obtained by performing the starch oxidation treatment and the gelatinization in parallel.
A composition as described. 3. The composition according to claim 2, wherein the starch is oxidized and gelatinized by heating and mixing the starch with water and an oxidizing agent, or with water, a plasticizing agent and an oxidizing agent, or a plasticizing agent and an oxidizing agent. . 4. The composition according to claim 3, wherein the oxidizing agent is a peroxide. 5. The composition according to claim 4, wherein the peroxide is a persulfate or hydrogen peroxide selected from the group consisting of potassium persulfate, ammonium persulfate, and sodium persulfate. 6. An amount of 0.1% by weight per 100 parts by weight of starch (based on dry matter).
6. The composition according to claim 2, wherein the oxidizing agent is used in an amount of from 0.01 to 0.50 parts by weight. 7. 10 parts per 100 parts by weight of starch (based on dry matter)
0.1 to 40 parts by weight of water and 1 to 100 parts by weight of plasticizer per 100 parts by weight of water or starch (based on dry matter) or 1 to 10 parts by weight per 100 parts by weight of starch (based on dry matter)
The composition according to any one of claims 2 to 6, wherein 0 parts by weight of a plasticizer is used. 8. The method of claim 1, wherein the starch is water, an oxidizing agent and a biodegradable resin.
Or biodegradable characterized by heating and mixing with water, a plasticizer, an oxidizing agent and a biodegradable resin, or a plasticizer, an oxidizing agent and a biodegradable resin, and forming the resulting mixture into a desired shape. Manufacturing method of molded article. 9. The method according to claim 8, wherein the oxidizing agent is a peroxide. 10. The method according to claim 9, wherein the peroxide is a persulfate or hydrogen peroxide selected from the group consisting of potassium persulfate, ammonium persulfate, and sodium persulfate. 11. The method according to claim 8, wherein the oxidizing agent is used in an amount of 0.01 to 0.50 parts by weight per 100 parts by weight of the starch (based on dry matter).
The production method according to any one of items 10 to 10. 12. 1 to 100 parts by weight of starch (based on dry matter)
0 to 50 parts by weight of water or 0.1 to 40 parts by weight of water per 100 parts by weight of starch (based on dry matter) and 1 to 100 parts by weight of a plasticizer or 1 to 100 parts by weight of starch (based on dry matter)
The method according to any one of claims 8 to 11, wherein 100 parts by weight of a plasticizer is used.