JPH0952901A - Composition for biodegradable molding and production of biodegradable molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition containing a gelatinized material of starch which is subjected to oxidation treatment, capable of improving fluidity when heat melting, enabling injection molding and useful for disposable dishes, etc. SOLUTION: This composition comprises (A) only a gelatinized material of starch which is subjected to oxidation treatment or contains the component A and (B) a biodegradable resin. Furthermore, the component A is obtained by heating and mixing (i) starch with (ii) water and (iii) an oxidizing agent (preferably persulfuric acid salt selected from potassium persulfate, ammonium persulfate and sodium persulfate or hydrogen peroxide) or component (ii), (iv)a plasticizer and the component (ii) or the component (iv) and the component (iii), preferably so that 0.01-50 pts.wt. component (iii) or 10-50 pts.wt. component (ii) or 0.1-40pts wt. component (ii) and 1-100 pts.wt. component (iv) or 1-100 pts.wt. component (iv) based on 100 pts.wt. component (i) are used, respectively.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a composition for a biodegradable product containing a starch gelatinization product and a method for producing the biodegradable product. More specifically, by adding an oxidizing agent to starch, the viscosity of the starch is reduced during gelatinization, the composition for biodegradable molded articles having improved fluidity during molding, and the fluidity during molding are improved. The present invention relates to a method for producing a biodegradable molded article having excellent forming processability.

[0002]

It has been proposed to utilize a 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 starch gelatinized material as a main component. Further, for example, Japanese Patent Application Laid-Open No. 2-14228 (referred to as Prior Art 2) discloses a biodegradable composition which is a complex of a starch gelatinization product and a biodegradable resin.

Biodegradable resin compositions using various modified starches as starch are also known. For example, JP-A-3
-56543 (referred to as Prior Art 3) discloses a biodegradable composition containing a starch graft copolymer. JP-A-3-70752 (referred to as Prior Art 4) discloses a biodegradable composition containing an anionically modified starch. Japanese Patent Application Laid-Open No. 3-74445 (referred to as Prior Art 5) discloses a biodegradable composition containing a cationic modified starch. Japanese Patent Application Laid-Open No. 3-74446 (referred to as Prior Art 6) discloses a biodegradable composition containing as a starch component a starch chemically modified to contain at least one of a hydroxyalkyl group, an alkyl ether group and an ester group. The thing is disclosed.

[0004]

In the biodegradable composition, important physical properties 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 in processing into a molded product is good. In putting the biodegradable composition into practical use, it is preferable that it has fluidity comparable to that of synthetic resins conventionally processed into molded articles, such as polystyrene. However,
Until now, much attention has been paid to fluidity in the development of starch-based biodegradable compositions.

In the starch gelatinization products disclosed in the prior arts 1 and 2, and further in the processed starches described in the prior arts 3 to 6, the fluidity during heating and melting was insufficient. Therefore, it was possible to obtain a molded article having a simple shape, for example, a sheet, by extrusion molding to some extent, but when attempting to mold an article having a complicated shape by injection molding, a desired fluidity was not obtained due to poor fluidity. It was difficult to obtain a shaped molded product.

Therefore, a first object of the present invention is a biodegradable composition using a starch gelatinization product, which has improved fluidity when heated and melted and is easy to mold, and is therefore a composition for biodegradable molded articles. To provide things. A second object of the present invention is to provide a method for producing a biodegradable molded product containing a starch gelatinized product, which has improved fluidity during heating and melting and can be easily molded.

[0007]

The present invention relates to a composition for biodegradable molded articles, which comprises an oxidized starch gelatinized product. The biodegradable composition for molded articles of the present invention includes an embodiment comprising an oxidized starch gelatinization product and an embodiment including an oxidation-treated starch gelatinization product and a biodegradable resin.

The present invention further provides that starch is added to water and an oxidizing agent,
Alternatively, the present invention relates to a method for producing a biodegradable molded article, which comprises heating and mixing with water, a plasticizer and an oxidizing agent, or a plasticizer and an oxidizing agent, and molding the obtained mixture into a desired shape.
Further, the present invention was 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 article, which comprises molding the mixture into a desired shape.

Biodegradable Molded Article Composition The biodegradable molded article composition of the present invention contains an oxidized starch gelatinization product. The gelatinized starch subjected to the oxidation treatment can be obtained by performing the oxidation treatment and the gelatinization of the starch in parallel. The starch used as a raw material for the above-mentioned oxidation treatment and gelatinization is not particularly limited, and any starch can be used. Examples thereof include unprocessed starch such as potato starch, corn starch, sweet potato starch, tapioca starch, sago palm starch, rice starch, wheat starch, and modified starch such as various esterified starches and etherified starches.

The oxidation treatment and gelatinization of starch can be carried out, for example, by heating and mixing the starch with water and an oxidizing agent, or water, a plasticizer and an oxidizing agent. By allowing an oxidizing agent to coexist, the oxidizing treatment can be performed simultaneously with gelatinization of starch, and the fluidity of the resulting 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 salt selected from the group consisting of potassium persulfate, ammonium persulfate, and sodium persulfate, or hydrogen peroxide can be used. The amount of oxidizing agent used is starch (dry matter basis) 1
It is suitable to set it in the range of 0.01 to 0.50 parts by weight per 00 parts by weight. Preferably 0.02-0.10
The range is 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 the oxidant,
A starch gelatinized product is obtained by heating and mixing in the presence of water, a plasticizer, or water and a plasticizer. The gelatinization of starch can be carried out in the presence of water alone or a plasticizer alone. Also,
Starch can be gelatinized even in the presence of water and plasticizer,
In this case, the amount of water used can be reduced, which is effective in preventing foaming during molding. Furthermore, there is an advantage that the starch gelatinized product and the biodegradable resin can be easily mixed and molded by adding a plasticizer to 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 biodegradable high boiling point plasticizers. 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. It is more preferable to use 10 to 20 parts by weight of water per 100 parts by weight of starch (on a dry matter basis) from the viewpoint of sufficiently gelatinizing the starch and preventing foaming when the starch is added to the biodegradable composition and molded. Appropriate.

When water and a plasticizer are used for gelatinization, 0.1 to 40 per 100 parts by weight of starch (dry matter basis) is used.
The use of parts by weight of water and 1 to 100 parts by weight of a plasticizer is suitable from the viewpoint that the starch can be sufficiently gelatinized and the gelatinized product can have sufficient plasticity. Further, it is preferably 0.1 to 100 parts by weight of starch (dry matter basis).
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 mold it, and form a gelatinized product. It is suitable from the viewpoint that appropriate plasticity can be imparted.

When only the plasticizer is used for gelatinization, 1 to 100 parts by weight of the plasticizer is used per 100 parts by weight of the starch (on a dry matter basis) so that the starch is sufficiently gelatinized.
It is also suitable from the viewpoint that it can impart sufficient plasticity to the gelatinized product. Further, preferably, starch (dry matter basis) 1
It is suitable to use 5 to 40 parts by weight of the plasticizer per 00 parts by weight from the viewpoint of sufficiently gelatinizing the starch and imparting appropriate plasticity to the gelatinized product.

The gelatinization of starch generally refers to a state in which starch particles irreversibly swell or dissolve when heated in the presence of water or the like, lose crystallinity and birefringence, and increase in viscosity. The starch gelatinization product in the present invention refers to a substance which exhibits substantially no crystallinity or birefringence. The loss of crystallinity and birefringence can be determined by observing the starch granules with a polarization microscope and eliminating the crossed polarization cross at the forming center, which was observed in the ungelatinized starch.

The heating and mixing for the oxidation treatment and gelatinization of starch can be appropriately determined depending on the type of starch, the type of plasticizer when a plasticizer is used, and the addition amount of water or plasticizer. For example, it is suitable to carry out at 60 to 220 ° C. for 10 to 60 minutes. The heat mixing can be performed using, for example, a pressure kneader or an extruder. By heat-mixing, the composition for biodegradable molded articles of the present invention, which comprises an oxidized starch gelatinized product, can be obtained. The obtained composition can be pelletized, for example, and the pellets can be used in the production of a biodegradable molded article.

The composition for biodegradable molded articles of the present invention containing an oxidized starch gelatinized product and a biodegradable resin is, for example, a pellet-shaped above-mentioned 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.
Any resin that has biodegradability itself may be used, and thermoplastic resin is suitable in consideration of moldability. Resins belonging to any of chemically synthesized resins, microbial resins, resins utilizing natural products, etc. may be used. For example, aliphatic polyester (for example, polycaprolactone, polylactic acid, polyhydroxybutyrate / vallate copolymer, etc.), polyvinyl alcohol, acetyl cellulose and the like can be mentioned.

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

Method for Producing Biodegradable Molded Article In the method for producing a biodegradable molded article of the present invention, when the biodegradable molded article is composed only of an oxidized starch gelatinized product, the above composition for biodegradable molded article is used. As in the case of the product, it can be carried out by heating and mixing the starch with water and an oxidizing agent, or water, a plasticizer and an oxidizing agent, or a plasticizer and an oxidizing agent, and then shaping the resulting mixture into a desired shape. it can. Molding into a molded product can be performed by using, for example, injection molding or extrusion molding. In addition, the production of a biodegradable molded article containing an oxidized starch gelatinization product and a biodegradable resin, starch is 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 by using, for example, injection molding, extrusion molding, or the like, as in the above.

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

[0022]

According to the present invention, there is provided a composition for a biodegradable molded article, which is a biodegradable composition using a starch gelatinization product, which has improved fluidity during heating and melting and is easy to mold. Can be provided. In particular, the composition for biodegradable molded articles of the present invention can also 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 starch gelatinized product, which has improved fluidity during heating and melting and can be easily molded. In the manufacturing method of the present invention, injection molding can also be used.

The improvement of fluidity according to the present invention can be carried out at a low cost because it can be carried out in parallel with gelatinization by using a small amount of an oxidizing agent (no additional step is required). When compounded with a biodegradable resin, which is more expensive than starch and starch gelatinized products, the fluidity is improved, so the blending ratio of starch gelatinized products (oxidized) can be increased. The cost of the biodegradable resin molded product can be reduced. The oxidised starch gelatinization product of the present invention has improved fluidity and, as a result, can be incorporated at a high rate in various composite compositions. As a result, the biodegradability of the composite composition can be accelerated (because the starch gelatinized product has a higher biodegradability than the biodegradable resin), and the application range of the biodegradable composite composition can be expanded to the level of general-purpose resins. It will be possible.

[0024]

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

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

Comparative Example 1 A pelletized 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 let (Styron 600 manufactured by Asahi Kasei Corporation) was used.

[0027]

[Table 1]

The heat 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 50 kgf, and the temperature was 50 ° C./min.
It measured in the range of ℃ -200 ℃. The result of melt viscosity at each temperature is shown in FIG. 1, and the result of flow rate (shear rate) is shown in FIG. That is, in Examples 1 to 3 to which a very small amount of the oxidizing agent was added, the melt viscosity was lowered and the fluidity was improved as compared with Comparative Example 1 to 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 (on a dry matter basis), 20 parts by weight of water, 15 parts by weight of polyethylene glycol and 0.04 part by weight of potassium persulfate were placed in a Henschel mixer (Mitsui Miike Kakoki Co., Ltd.) at 600 rpm. The mixture was stirred for 1 minute and mixed.
This was pelletized under the following extruder and conditions. Extruder name Labo Plastomill model manufactured by Toyo Seiki Co., Ltd. 2 screw extruder 2D25S screw L / D = 25 (2 screw) Temperature ZONE 1: ZONE 2: ZONE 3: ZONE 4 = 50 ° C: 60
℃: 120 ℃: 100 ℃ Die 3φ pelletizer Toyo Seiki Co., Ltd. cold cut pelletizer PETEC type

The starch pellets obtained under the above conditions were injection-molded under the following conditions using an injection molding machine and a flowerpot molding die manufactured by Nissei Plastic Engineering Co., Ltd. to obtain molded products. Heating cylinder set temperature Nozzle 150 ℃ Front 155 ℃ Middle
145 ℃ Rear 120 ℃ Mold surface temperature 20 ℃ 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 pellet obtained in Example 4 and polycaprolactone (Placcel H7) 5 manufactured by Daicel Chemical Industries, Ltd.
0 parts by weight was mixed, and an injection molding test was performed under the following conditions using an injection molding machine and a flowerpot molding die manufactured by Nissei Plastic Engineering Co., Ltd. to obtain a molded product. Heating cylinder set temperature Nozzle 150 ℃, front 155 ℃, middle part
145 ℃, rear 120 ℃ Mold surface temperature 20 ℃ 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 drawings]

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

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

Claims (14)

[Claims] 1. A composition for a biodegradable molded article, which comprises an oxidized starch gelatinized product. 2. The composition according to claim 1, which consists only of an oxidized starch gelatinization product or comprises an oxidized starch gelatinization product and a biodegradable resin. 3. The starch gelatinization product subjected to oxidation treatment is obtained by subjecting starch to oxidation treatment and gelatinization in parallel.
Or the composition according to 2. 4. The composition according to claim 5, wherein the starch is oxidized and gelatinized by heating and mixing the starch with water and an oxidizing agent, or water, a plasticizer and an oxidizing agent, or a plasticizer and an oxidizing agent. . 5. The composition according to claim 4, wherein the oxidizing agent is a peroxide. 6. The composition according to claim 5, wherein the peroxide is a persulfate selected from the group consisting of potassium persulfate, ammonium persulfate and sodium persulfate, or hydrogen peroxide. 7. An oxidizing agent is used in an amount of 0.01 to 0.50 parts by weight per 100 parts by weight of starch (dry matter basis).
7. The composition according to any one of the above items 6. 8. 1 per 100 parts by weight of starch (dry matter basis)
0 to 50 parts by weight of water, or 0.1 to 40 parts by weight of water and 1 to 100 parts by weight of plasticizer per 100 parts by weight of starch (dry matter), and 1 per 100 parts by weight of starch (dry matter).
The composition according to any one of claims 4 to 7, which uses -100 parts by weight of a plasticizer. 9. Starch is heated and mixed with water and an oxidizing agent, or water, a plasticizer and an oxidizing agent, or a plasticizer and an oxidizing agent,
A method for producing a biodegradable molded article, which comprises molding the obtained mixture into a desired shape. 10. A starch 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. A method for producing a biodegradable molded article, which comprises molding the above mixture into a desired shape. 11. The method according to claim 9, wherein the oxidizing agent is a peroxide. 12. The method according to claim 11, wherein the peroxide is a persulfate selected from the group consisting of potassium persulfate, ammonium persulfate and sodium persulfate, or hydrogen peroxide. 13. The use of 0.01 to 0.50 part by weight of an oxidizing agent per 100 parts by weight of starch (dry matter basis).
13. The manufacturing method according to any one of 12. 14. 10 to 50 parts by weight of water per 100 parts by weight of starch (dry matter), or 0.1 to 40 parts by weight of water and 1 to 100 parts by weight of plasticizer per 100 parts by weight of starch (dry matter). Or the plasticizer of 1 to 100 parts by weight per 100 parts by weight of starch (dry matter basis) is used.