CN1580110A - Biodegradable resin composition - Google Patents

Abstract

The invention provides a biodegradable resin composition having good processability, which can be used in biodegradable films, multifunctional films and bags for household garbage. A biodegradable resin composition characterized by comprising a starch ester wherein the hydrogen atom of a reactive hydroxyl group of the same starch molecule is replaced by an acyl group having 2 to 4 carbon atoms (hereinafter referred to as "short-chain acyl group") and an acyl group having 6 to 18 carbon atoms (hereinafter referred to as "long-chain acyl group") and the melt flow rate MFR (measured in accordance with JIS K7210) is 0.1 to 25g/10min as a part or all of the composition.

Description

biodegradable resin composition

【Technical field】

The present invention relates to a biodegradable resin composition formed by mixing starch esters produced by substituting reactive hydroxyl groups on the same starch molecule with acyl groups and those derivative groups (hereinafter referred to as "acyl groups").

The biodegradable resin composition can be used as a raw material for general-purpose resin processed products, foams, and water-based dispersants, and is particularly useful for biodegradable films, multifunctional films, and household products that have excellent low-temperature flexibility. Appropriate biodegradable resin compositions such as bags for garbage.

Here, the term "biodegradable resin composition" refers to a composition that retains the same level of function as conventional plastics during use and is decomposed by microorganisms or the like after use, for example, in natural environments such as soil or in composite materials. Low-molecular compounds are finally decomposed into high-molecular materials such as water and carbon dioxide. There are ISO14851, ISO14852, ISO14855, etc. as a measuring method of biodegradability.

In addition, the term "resin processed product" here refers to a material including a molded product and a modified processed product obtained by molding or modifying all or part of the plastic composition. For forming processing, it includes injection molding, extrusion molding, stamping method, T-die method, calender processing, compression molding (pressure forming), transfer molding, casting method (casting), lamination method, vacuum forming, Injection molding (blow molding), foam molding, coating, salivation, thermal bonding, drawing processing, etc. (The 5th edition of the Chemical Handbook of Applied Chemistry I edited by the Japan Chemical Society (March 15, 2017) Maruzen, refer to p773 Table 10.22). Therefore, molded products include not only three-dimensional molded products but also films, sheets, and coated papers. In addition, the modified product also includes the case where a starch-substituted derivative is added as a modifying agent to paper and nonwoven fabric made of natural materials, and also includes paper, processed paper, and nonwoven fabric.

【Background technique】

As a basic starch modification method related to the present invention, there is esterification (acylation), and starch esters produced by those reactions have been known heretofore as aqueous reaction esterified starches (starch esters) with a low degree of substitution. ("Handbook of Starch Science" Asakura Shoten Co., Ltd. p550)

Also regarding starch esters (esterified starch) with a high degree of substitution, there is known a method in which an acid anhydride is reacted in pyridine with dimethylaminopyridine or an alkali metal as a catalyst ("starch chemistry & technology" ウイスラ one work, Published by Academic Press, p332-336), there is a method of using an alkali metal hydroxide aqueous solution as a catalyst in an acid anhydride and reacting at a high temperature above 100°C (JP 5-508185 and DieStarke March 1972 No. p73, etc.), There is a method of reacting in a non-aqueous organic solvent (JP-A-8-188601), and a short-chain/long-chain mixed starch ester (JP-A-2000-159801).

In recent years, amid increasing awareness of environmental issues, starch esters produced by the method described above have been used in various biodegradable plastic materials, but whether this starch ester is mixed with various synthetic resins or Forming a molded article or a film alone does not provide molding processability (for example, injection moldability, extrusion moldability, stretchability, etc.) like ordinary thermoplastics (thermoplastic resins).

Especially in the case of an impression film, it is difficult to obtain a good stretch (drawing stretch) like polyethylene, and the properties suitable for film processing are not good.

Furthermore, such a tendency becomes more remarkable as the ratio of starch ester in the plastic composition (plastic material) used as a molding material increases.

On the other hand, in order to improve these impact strength and elongation properties, in the case of mixing and using a biodegradable resin (biodegradable polymer) other than starch ester, if the natural decomposition higher than that of starch ester is not improved If the ratio of the resin is low, the effect of improvement cannot be obtained, and it becomes difficult to produce so-called biodegradable plastics based on starch esters.

【Content of invention】

In view of the above circumstances, an object of the present invention is to provide a biodegradable resin composition having good processability, which can be used as a thermoplastic material, and in which starch ester is mixed.

Another object of the present invention is to provide biodegradable resin processed products, biodegradable films, Multifunctional film, bags for household garbage, foam.

In order to use the raw material produced every year, that is, starch without the risk of depletion, it is necessary to develop a biodegradable plastic that has good processability and can be used as a thermoplastic material. A novel biodegradable resin composition comprising starch esters of the following structure.

The feature is that (A) the hydrogen atom of the reactive hydroxyl group of the same starch molecule is replaced by an acyl group with 2 to 4 carbon atoms (hereinafter referred to as "short-chain acyl group") and an acyl group with 6 to 18 carbon atoms (hereinafter referred to as "short-chain acyl group") "Long-chain acyl group") substitution, the substitution degree of the above-mentioned long-chain acyl group is 0.06-2.0, the substitution degree of the above-mentioned short-chain acyl group is 0.9-2.7, and the total substitution degree of the acyl group is 1.5-2.95,

(B) The melt flow rate (measured by JIS K7210) is 0.1 to 25 g/10 min of starch ester as part or all of the composition.

In addition, using the biodegradable resin composition of the present invention, it is possible to form a product exhibiting a water absorption rate (after soaking in tap water at 23° C. for 24 hours) of 0.5% or less and an Izod impact strength of 1.8 kgf·cm/cm or more. injection molded products, or films with a film thickness of 100 μm or less showing traction stretch (JIS K6301) of 200% or more, biodegradable multifunctional films with biodegradability and strength, bags for biodegradable household waste, biodegradable sex foam.

【Function and effect of the invention】

The biodegradable resin composition of the present invention is a biodegradable plastic material having good molding properties, especially good impact strength and elongation at low temperature, as supported by the following Examples and Comparative Examples.

Furthermore, the naturally degradable resin composition of the present invention has surprisingly excellent processability, and can easily prepare resin processed products, biodegradable films, multifunctional films, bags for household garbage, and foam films • Flakes.

【Detailed description of the method】

The method of the present invention will be described in detail below. Mixed units here are all mass units unless previously specified. In addition, in the description below, Cn in parentheses attached to each compound means that the number of carbon atoms corresponding to the acyl group is n.

The degree of substitution DS (Degree of Substitution) here means that in starch derivatives, the average of the substituted hydroxyl groups of each glucose residue in the reactive hydroxyl group (3: 2, 3, 6 (or 4) positions) value, the reactive sealing ratio (substitution ratio) at DS=3 becomes 100%.

In order to solve the above-mentioned problems, the present inventors have worked hard to find that it is important to impart thermoplasticity to starch itself in the practical temperature range in order to solve the above-mentioned problems. For this reason, long-chain alkyl groups, Cycloalkyl, alkylene, aryl and other groups containing long-chain hydrocarbons and short-chain alkyl, cycloalkyl, alkylene, aryl and other groups containing short-chain hydrocarbons are crucial, while , MFR (measured by JIS K7210) in the range of 0.1 to 25g/10min the above-mentioned starch ester satisfies the above conditions and has excellent processability biodegradable plastic material, and it is thought to be formed by mixing starch esters with the following new structure Biodegradable resin composition. This starch ester is conceptually represented by the following structural formula.

(wherein, R ¹ : a short-chain acyl group with 2 to 4 carbon atoms, R ² : a long-chain acyl group with 6 to 18 carbon atoms)

The manufacturing method of this starch ester is not specifically limited, However, It can manufacture easily using the manufacturing method of the following structure starch ester.

"Method for producing starch ester using vinyl ester as an esterification agent" (see JP-A-8-188601 (JP-A-2579843)), "Short-chain and long-chain mixed starch ester" (JP-A-2000-159801 Bulletin).

As the raw material starch of the starch ester of the present invention, ground unmodified starches such as corn starch, higher amylose starch, wheat starch, and rice starch, underground starch such as potato starch, and tapioca starch can be used alone or in combination of two or more. Unmodified starches and those starch esters that have undergone low esterification, etherification, oxidation, acid treatment, dextrinization, etc.

As an acylating (esterifying) agent used to introduce a long-chain acyl group with 6 to 18 carbon atoms into a reactive hydroxyl group by a substitution reaction, an ester that can be bonded to a carbonyl group from a long-chain hydrocarbon group with 5 to 17 carbon atoms Alkyl ketene dimers, cyclic esters (caprolene), acid anhydrides, oxyhalides, or vinyl compounds at the conversion (acylation) reaction site (6 to 18 carbon atoms) are selected. One or more than two.

Among the above-mentioned long-chain hydrocarbon groups, there are alkyl groups, cycloalkyl groups, alkylene groups, aryl groups, etc. and their derivative groups. As the derivative groups, aralkyl groups (aralykl), alkaryl groups (alkaryl groups) can be mentioned. ), alkoxyalkyl groups, etc. In addition, groups containing active hydrogen atoms such as hydroxyalkyl groups and aminoalkyl groups are also included within the range that does not affect the effects of the present invention. Among these compounds, an esterification agent having 8 to 14 carbon atoms and containing an esterification reaction site is preferable from the viewpoint of reaction efficiency and operability.

With regard to the degree of substitution (DS) of esters on starch, in the case of long-chain acyl groups, the length of that acyl group has an effect on the miscibility with the biodegradable resin which is one of the objects of the present invention, but even at the largest number of carbon atoms In the case of long-chain acyl groups, if the DS is below 0.05 (reactive hydroxyl sealing ratio 2%), it will be difficult for starch to maintain its specified properties. Also, as an acyl group having the largest number of carbon atoms, the reaction efficiency is extremely low when the number of carbon atoms is 19 or more, so it is not practical.

Generally speaking, the DS of long-chain acyl groups: 0.06~2.0 (sealing ratio: 2~67%), the DS of short-chain acyl groups: 0.9~2.7 (sealing ratio: 30~90%), and the total acyl DS: 1.5~ 2.95 (sealing rate: 50-98%).

From the case where the degree of substitution of long-chain acyl groups is the smallest and the degree of substitution of short-chain acyl groups is the largest, to the case where the degree of substitution of long-chain acyl groups is the largest and the degree of substitution of short-chain acyl groups is the smallest, in terms of miscibility with biodegradable resins and mechanical and physical properties, there is no difference. to extreme changes. Moreover, to obtain the same level of thermal plasticization without the need for plasticizers, the degree of substitution can be reduced corresponding to an increase in the number of carbon atoms of the long-chain acyl group.

Therefore, the above numerical range has no particular critical meaning, and the present invention can be practiced even in the vicinity of the above range.

Preferably, the DS of long-chain acyl groups: 0.1 to 1.6 (sealing ratio: 3 to 53%), the DS of short-chain acyl groups: 1.2 to 2.1 (sealing ratio: 40 to 70%), and the total acyl DS: 2.0 to 2.9 (sealing ratio). Rate: 67-97%).

In addition, the number of carbon atoms of the short-chain acyl group is set at 4 or less. According to the test results, there is no difference in the reaction efficiency of the present invention when the number of carbon atoms is between 2 and 4.

The glass transition temperature (JIS K7121: Tg) of the starch ester of the present invention is 30°C to 140°C, preferably 45°C to 130°C. As the transformation point (transition temperature) increases, the mutual dissolution with the biodegradable resin gradually becomes difficult because mutual dissolution is difficult if the temperature exceeds 140° C. without a plasticizer. Starch esters with a Tg of 30°C are difficult to manufacture.

In the above, it is required that films made of the biodegradable resin composition of the present invention, household garbage bags, foams, etc. require stretchability and flexibility at low temperatures (for example, below zero degrees) In some cases, Tg needs to be about 100°C or lower, more preferably about 30 to 75°C.

When the MFR (measured by JIS K7210) of the starch ester of the present invention is 0.1 to 25 g/10 min, it is most ideal for the processability of the biodegradable resin composition. The melt flow rate (MFR: Melt FlowRate) is measured by JIS K7210 (ISO 1133). For example, under the specified temperature and pressure conditions, use an extrusion-type plastic gauge such as a melt indexer to extrude the sample entering the metal cylinder from the die, and then measure the weight of the extruded sample within the specified time, and use 10 The weight (g) of the sample extruded within one minute is expressed. Here, when the melt flow rate of the starch ester is lower than 0.1 g/10 min, the biodegradable resin composition has poor fluidity, poor molding stability, and poor processability. In particular, with regard to the processability of the film, since a pull resonance phenomenon or the like is likely to occur, the extrusion amount is also unstable and the continuous molding stability is also poor. Raising the processing temperature in order to obtain good fluidity is not suitable for starch esters because it will cause detachment and coloring of the esters. In addition, when the MFR is higher than 25 g/10 min, it is not preferable because the low molecular weight or biodegradability of starch is impaired at the time of starch derivatization. Even when the DS of the above-mentioned starch esters is the same, when the crosslinking reaction occurs during the derivatization or the molecular weight of the starch is lowered, the MFR will be different. A more suitable MFR for starch esters is 0.3-20 g/10 min.

Whether or not a crosslinking reaction occurs during the derivatization of the above-mentioned starch ester is determined, for example, as follows.

First, each number-average molecular weight (Mn) of starch ester and raw material starch is measured by a column of gel permeation chromatography (GPC), and obtained by the following formula.

Number average molecular weight Mn=∑hi/(∑hi/Mi)

(Wherein, Hi: the concentration of i molecules in the solution, Mi: the molecular weight of i molecules in the solution)

Then, the number average molecular weight of the starch base was obtained from the obtained number average molecular weight by the following formula.

Deesterified starch Mn (starch base Mn on starch ester) = starch ester Mn-∑Ei×Di×raw starch Mn/162 (glucose residue molecular weight)

(Wherein, Ei: molecular weight of ester group, Di: DS of ester group)

Comparing the deesterified starch Mn obtained in this way with the raw starch Mn, if the former is larger than the latter, then crosslinking has occurred; if the former is smaller than the latter, then it has occurred during derivatization (esterification). Low molecular weight of starch.

For the starch ester of the present invention, the deesterified starch Mn is preferably within the range of 0.5 to 1.5 times, more preferably 0.8 to 1.2 times the raw material starch Mn. This is because the crosslinking reaction increases the MFR, and the low molecular weight reduces the physical properties such as the strength of the resin processed product.

In order to suppress such a cross-linking reaction and prevent such low molecular weight, generally speaking, the esterification of starch can be controlled in a neutral-weak alkaline environment. In the case of vinyl ester esterification, it is more desirable to discharge the generated aldehyde from the system by fractional distillation or the like.

The following describes the biodegradable resin blended with the starch ester of the present invention.

The so-called "compatibility" here refers to the state in which two or more substances are uniformly dispersed with each other, and this state does not only refer to making them The state obtained by mixing also includes the state of being "immiscible" with each other and evenly dispersed.

As the above-mentioned biodegradable resin, what is hereinafter referred to as natural (mainly cellulose) or synthetic (polymer) can be suitably used.

Cellulose: cellulose acetate, hydroxyethyl cellulose, propyl cellulose, hydroxybutyl cellulose, etc. Polymers:

① Polycaplactone (PCL: Polycaplactone), polylactic acid (PLA: Polylactic acid), polyadipate, polyhydroxybutyrate (polyhydroxyalkanol esters), polyhydroxybutyrate valerate (PHB /V), 1,4-butanediol succinate polymer, polyhydroxyalkanol ester (PHA), polybutylene succinate (PBS), butylene succinate-adipate copolymer (PBSA), polybutylene succinate (PES), polybutylene succinate terephthalate copolymer (PET), polybutylene adipate terephthalate copolymer (PBT), polybutylene succinate-carbonate copolymer (PEC), aromatic-introduced aliphatic polyester, poly-3-hydroxybutyrate (P(3HB)), and 3-hydroxybutyrate (3HB) and 3-hydroxyvalerate (3HV) random copolymerization polyester (P(3HB-∞-3HV) and other biodegradable polyester or polyamide;

②Polyalkylene oxides such as polyethylene oxide and polypropylene oxide;

③ Polyvinyl alcohol, modified polyvinyl alcohol, polyacrylamide resin, polycarbonate resin, polyurethane resin, polyvinyl acetate, polyvinyl carbazole, polyacrylate, ethylene vinyl acetate Ethylene polymers such as copolymers;

In addition, the MFR of these blended biodegradable resins is 2 to 70 g/10 min, more preferably 2 to 30 g/10 min. This is due to consideration of properties suitable for processing (molding properties) of the biodegradable resin composition.

When preparing a plastic material (starch ester composition) based on the biodegradable resin composition of the present invention, the following various fillers can be used as fillers (fillers) used together with other auxiliary materials. Furthermore, the shape of the filler can be selected from any suitable shape such as powder, granule, plate, column, fiber, needle, etc. according to the required characteristics.

Inorganic fillers: talc, titanium oxide, clay, chalk, limestone, calcium carbonate, mica, glass, silica and various silica salts, diatomaceous earth, wall star stone, various magnesium salts, various A manganese salt etc.

Organic fillers: starch and starch derivatives, cellulose and its derivatives, wood flour, pulp, ビカンフアイバ-, cotton powder, grain skin, lint, wood fiber, bagasse, etc.;

Synthetic fillers: glass fibers, urea polymers, ceramics, etc.

The resin processed product of the present invention includes a molded product and a modified product obtained by molding or modifying all or part of the above-mentioned degradable resin composition, and the molding process includes injection molding, extrusion molding, stamping method, T-die method, wheel press processing, compression molding (pressure forming), transfer molding, casting method (casting), lamination method, vacuum forming, injection molding (blow molding), foam molding, coating, Known methods such as salivation, thermal bonding, stretching and the like (Maruzen, "The Fifth Edition of the Chemical Handbook of Applied Chemistry I" edited by the Chemical Society of Japan (March 15, 2017), refer to Table 10.22 of p773).

Therefore, the molded products include not only three-dimensional molded products but also films, sheets, coated papers, and the like. In addition, modified processed products also include the case where starch-substituted derivatives are added as modifiers to paper and nonwoven fabrics composed of natural materials, and also include paper, processed paper, and nonwoven fabrics.

The film of the present invention is obtained by forming a film using the above-mentioned biodegradable resin composition by a known processing method. That is, it can be obtained by a film-forming method such as a T-molding method by extrusion, an impression method, a calendering method, or a stretching method. By processing such a film into a bag, the bag for household garbage of the present invention can be obtained. Also, a multifunctional membrane can be prepared by adjusting the biodegradability of the membrane. Furthermore, a biodegradable foam can be obtained by using the above biodegradable resin composition and using a known method (extrusion foam molding).

【Example】

Next, in order to demonstrate the effects of the present invention, examples, comparative examples, and application examples performed will be described.

A. The starch esters used in Examples and Comparative Examples were prepared by each method below.

<Example 1>

Suspend 25Kg of high-grade amylose cornstarch (70% amylose; the same below) in 180Kg of dimethyl sulfoxide (DMSO), heat up to 90°C while stirring, and keep such a temperature within 20 minutes to make it gelatinized. Add 20Kg of sodium bicarbonate as a catalyst to this solution, keep the reaction temperature at 90°C and add 16kg of vinyl laurate (C12), and react at this temperature for 1 hour while removing acetaldehyde from the system by fractional distillation. Next, 35 kg of vinyl acetate (C ₂ ) was further added, and acetaldehyde was removed from the system by fractional distillation in the same manner, and the reaction was carried out at 80° C. for 1 hour. Afterwards, pour the reaction solution into tap water, perform high-speed stirring and pulverization, and then filter and dehydrate to prepare starch ester.

<Example 2>

According to embodiment 1, except using 15Kg stearic acid chloride (C18) to replace vinyl laurate, obtain starch ester through other identical steps modulation.

<Example 3>

According to embodiment 1, except using acid-treated conventional corn starch to replace high-grade amylose corn starch, and using 13Kg vinyl stearate to replace vinyl laurate (C18), starch esters were prepared through the same steps.

<Example 4>

Put 100kg of commercially available cornstarch and 800kg of DMSO that have been dried in advance so that the water content is below 1% into a tank with a stirrer, heat to 90°C and keep the temperature for 20 minutes to make it gelatinized. Add 5 kgt tert-butyl bromide and 532 kg hexadecyl diketene (C17) dropwise to this solution, after that, decompress the inside of the system and reflux DMSO, remove acetaldehyde from the system by fractional distillation, at 90°C The reaction was carried out for 5 hours. Thereafter, the pressure in the system was returned to atmospheric pressure, 126 kg of acetic anhydride and 103.8 kg of sodium bicarbonate were added, and the reaction was carried out at reflux temperature for 1 hour. After the unreacted matter and by-products flowed out, they were recovered while vigorously stirring in water, and the product was washed with water to prepare starch esters.

<Example 5>

According to embodiment 1, except using 18.5kg 2,2-dimethyl tridecanoic acid vinyl ester (C15) to replace vinyl laurate, the mixed ester of embodiment 5 was prepared through the same steps. Prepare starch esters.

<Example 6>

According to embodiment 1, except using 27kg n-caproic acid vinyl ester (C6) to replace vinyl laurate, obtain the starch ester of embodiment 6 through other identical steps modulation.

<Example 7>

According to embodiment 1, except using 30kg stearic acid chloride (C18) to replace vinyl laurate, obtain starch ester through other identical steps modulation.

<Embodiment 8>

According to Example 1, except that 25kg stearic acid chloride (C18) is used to replace vinyl laurate, and 45kg vinyl propionate (C3) is used to replace vinyl acetate (C2), starch esters are prepared through other identical steps .

<Comparative example 1>

Suspend 20kg of high-grade amylose cornstarch in 200kg of solvent (DMSO), heat up to 90°C while stirring, and keep at this temperature for 20 minutes to make it gelatinized. To this solution, 20 kg of sodium bicarbonate was added as a catalyst, 40 kg of vinyl acetate (C2) was added, and the reaction was carried out at 80° C. for 1 hour while refluxing the whole. Afterwards, pour the reaction solution into tap water and perform high-speed stirring and pulverization, and then filter and dehydrate to prepare starch ester (starch acetate).

<Comparative example 2>

Suspend 25kg of high-grade amylose cornstarch in 180kg of DMSO, raise the temperature to 80°C, and make it gelatinized by keeping it for 20 minutes. Add 35kg of sodium bicarbonate used as the acid generated by the neutralization side reaction to this solution, after that, the reaction temperature is cooled to 20°C, in order to suppress starch hydrolysis, keep the reaction at 20-25°C while adding 45kg of acetic anhydride, add After completion, the reaction was carried out at this temperature for 1 hour. Thereafter, starch ester was prepared in the same manner as in Embodiment 1.

<Comparative example 3>

Add 40kg of high-grade amylose cornstarch in a 1L four-neck flask with a capacity of reflux condenser, dropping funnel and thermometer, and add 150L of acetic anhydride while stirring. Next, heat until some reflux begins. The boiling temperature is about 125°C. After 1-2 hours, the viscosity increased, and after 3-4 hours a viscous slightly brownish transparent mixture was formed. After the necessary reaction time is about 5 hours, fractionally distill 5-10L of acetic acid at 118°C, and continue to add 20L of ethanol dropwise. Stirring was continued for 30 minutes under slightly controlled heating, and the solvent mixture composed of ethyl acetate and acetic acid formed by the reaction of ethanol and acetic anhydride was fractionally distilled at 102-105°C. Next, the heating was stopped and the mixture was cooled for 0.5-1 h. Next, 20 L of ethanol was added dropwise again. The mixture was then slowly precipitated with approximately 200 L of methanol. The resultant was washed with ethanol several times, separated by suction filtration, and dried in air to obtain starch ester.

Table 1 shows the long-chain and short-chain acyl substitution (DS), melt flow rate (MFR), glass transition temperature (Tg) and deesterified starch group Mn/ Ratio of raw starch Mn.

【Table 1】 Biodegradable resin compounding amount* LCDS short chain DS Total DS MFR(g/10min) Glass transition temperature of StE (Tg)℃ Deesterified Mn/raw starch Mn Embodiment 1StE+PCL-A 50 copies C120.48 C21.96 2.44 StE 3.5PCL 2.7 114 0.95 Embodiment 2StE+PBS 25 copies C180.31 C21.92 2.23 StE 1.5PBS 25.0 123 1.35 Embodiment 3StE+CA-A 150 copies C180.28 C21.94 2.22 StE 0.5CA 4.5 127 0.90 Embodiment 4StE+PCL-B 75 copies C170.23 C21.89 2.12 StE 0.3PCL 6.1 114 0.85 Embodiment 5StE+PCL-A 50 copies C150.45 C21.88 2.33 StE 3.8PCL 2.7 100 1.05 Embodiment 6StE+PHBV 50 copies C61.45 C21.33 2.78 StE 7.8PHBV 8.0 97 0.65 Embodiment 7StE+PBS 25 copies C180.63 C22.04 2.67 StE 6.5PBS 25.0 52 1.00 Embodiment 8StE+PBS 25 copies C180.51 C32.18 2.69 StE 3.5PbS 25.0 49 0.95 Comparative example 1StE+CA-B 50 copies - C22.44 2.44 StE0.05CA0.3 165 1.80 Comparative example 2StE+CA-B 50 copies - C22.35 2.35 StE 0.05CA 0.3 170 0.55 Comparative example 3StE+CA-B 50 copies - C22.40 2.40 StE 0.08CA 0.3 167 0.35

These characteristic values were measured by the methods described below. In addition, the ratio of deesterified starch base Mn/raw material starch Mn is measured and calculated by the above-mentioned method.

(1) Long-chain and short-chain acyl substitution degree (DS)... For the saponification method (Genung & Mallet, 1941), follow the method of Smith (1967) ("Starch-associated sugar quality test method" Co., Ltd. Society Publishing Center, 1986 Issued on October 10, 2010, refer to p291), regarding the saponified product (alkaline hydrolyzate), the ratio of long-chain fatty acid and short-chain fatty acid is determined by liquid chromatography at the same time from the liquid phase to determine the ratio of long-chain and short-chain acyl Degree of substitution.

(2) Glass transition temperature (Tg)... Measured according to JIS K7121 using "differential scanning calorimeter DSC-50" (manufactured by Shimadzu Corporation).

(3) Melt flow rate (MFR)...Measured by JIS K7210 (ISO 1133). Under the specified temperature and pressure conditions, use the melt indexer: extrusion plastic meter TOYOSEIKI S-101 to extrude the sample loaded into the metal cylinder from the mold, and measure the weight of the extruded sample within the specified time , and expressed by the weight (g) of the sample extruded within 10 minutes.

B. Preparation of pellets for manufacturing molded products (processed products)

Biodegradable resins were mixed with the various starch esters prepared above, and melted and blended by a disintegrator at 190° C. to form biodegradable resin compositions in Examples and Comparative Examples as pellets. Table 1 shows the mixing ratio and the biodegradable resin used.

In addition, the biodegradable resin used respectively shows each thing below.

Polycaprolactone-A (PCL-A)…“P-HBO2” produced by Daicel Chemical Industry Co., Ltd., MFR: 2.7g/10min

Polycaprolactone-B (PCL-B)..."P-HBO5" produced by the same company, MFR: 6.1g/10min

Cellulose acetate (CA-A)..."P-CA05" produced by the same company, MFR: 4.5g/10min

Cellulose acetate (CA-B)..."P-CA00" produced by the same company, MFR: 0.3g/10min

Polybutylene succinate (PBS)..."BIONOLLE#1020" manufactured by Showa High Polymer Co., Ltd., MFR: 25g/10min

Polyhydroxybutyrate valerate (PHBV)…“BIOPOL D611G” manufactured by Japan Monsant Corporation, MFR: 8.0g/10min

C. In order to determine the film formability, each biodegradable resin composition pellet of each Example and Comparative Example was used as a molding material, and a film was produced with a two-screw extruder (L/D.=32) under the following conditions ( 120 mm wide and 40 μm thick).

Plasticizing temperature: 170°C, T molding temperature: 170°C, extrusion speed: 10m/min, output: 3kg/min.

At this time, no pull resonance occurred in any of the examples, the amount of extrusion was stable, the stability of continuous molding was also good, and the film processability was good. On the other hand, in any of the comparative examples, pull resonance was easily generated, and the amount of extrusion was also unstable, resulting in poor continuous molding stability.

D. In order to determine the injection moldability and test the water absorption rate and impact strength of the molded product, each of the biodegradable resin composition pellets of each embodiment and comparative example was used as a molding material to manufacture a disc-shaped test piece (diameter 50 mm × wall thickness) 3mm) (ASTM D256).

At this time, in any of the examples, the injection amount of the substance was stable, and the continuous molding stability was also good, and the processability was good. On the other hand, the injection amount was not stable, and the molding stability was also poor.

With respect to the test pieces obtained above, various experiments were carried out by the following methods.

(1) Water absorption... After immersing an injection-molded plastic disc (5mm in diameter x 3mm in thickness) in tap water at 23°C for 24 hours, the water absorption was measured to obtain the water absorption.

(2) Izod impact strength...measured in accordance with ASTM D256 at an ambient temperature of -23°C.

Those experimental results are shown in Table 2, comparing the examples of introducing both short-chain groups and long-chain groups with the comparative examples with only short-chain groups, it can be seen that the water absorption rate is far reduced (the difference is almost two order of magnitude), while the Izod impact strength becomes far larger.

【Table 2】 Water absorption (%) Izod impact strength (kgf cm/cm) Example 1 0.10 4.5 Example 2 0.11 5.3 Example 3 0.18 5.0 Example 4 0.10 4.7 Example 5 0.12 4.9 Example 6 0.10 5.5 Example 7 0.08 6.5 Example 8 0.07 7.1 Comparative example 1 10.5 1.0 Comparative example 2 8.00 0.6 Comparative example 3 11.0 0.7

E. In order to test the tensile properties of the impression film while judging the impression processability, each biodegradable resin composition pellet of each example and comparative example was used as a molding material, and an impression processing device (blow outlet diameter: 100mm, Cylinder diameter: 150mm), making impression film.

In addition, the following properties were observed or measured during die processing.

(1) Die condition... Visual observation was performed.

(2) Film thickness...The values at 5 places were measured with a micrometer, and then the average value was calculated.

(3) Film stretch (EB)...measured in accordance with JIS K6301.

The test results are shown in Table 3. In each of the examples, the formability was good, and the stretchability of the film was sufficient for practical use, but the film sheets in the comparative examples could not be produced.

In addition, in the case of forming a film sheet by the die-casting method, it is especially required that both resins have a high degree of compatibility when blending the resins. At first glance, it seems that the blending is very uniform, but the two resins that are not compatible are not sufficiently melted and stretched when forming a film, and they are broken. In addition, flow characteristics are important in film processability, and MFR also has a great influence. For this reason, polymers which have the property of being able to form thin film sheets without breaking and polymers which do not have this property are entered as completely different substances in the table below.

【table 3】 impression condition Film Thickness (μm) Film stretch (%) Example 1 good 40 580 Example 2 good 20 600 Example 3 good 40 480 Example 4 good 25 510 Example 5 good 25 380 Example 6 good 20 550 Example 7 good 20 650 Example 8 good 20 720 Comparative example 1 rupture Can't make - Comparative example 2 rupture Can't make - Comparative example 3 rupture Can't make -

F. In order to determine the extrusion characteristics and biodegradability of the multifunctional film mixed with an inorganic filler (talc), 0.7 kg of talc ("Hitron A" Takehara Chemical Co., Ltd. Manufactured, average particle size 3.3 μm), mixed and melt-blended by a disintegrator at 190° C. to form granules.

A stamp multifunctional film (thickness: 20 μm) was produced using this pellet and the same stamp processing apparatus as in E above under the following conditions.

Molding temperature: 200℃, film stretching speed: 17.0～20.0m/min, slit width: 1.0mm

At this time, in any of the examples, the injection amount of the substance was stable, the continuous molding stability was also good, and the processability was good. In addition, the biodegradability of this multifunctional film was measured by ISO 14855, and as a result, any of the multifunctional films showed a biodegradability of 70% or more.

G. According to the above description, except that the mixed amount of talc is 0.5kg, the particles prepared by the same method are used, and the obtained stamp multifunctional film (thickness: 40 μm) is passed through heat under the following conditions using the same stamp device. Sealing is processed into a bag shape to obtain a bag for biodegradable domestic garbage.

Molding temperature: 195°C, film stretching speed: 17.0～20.0m/min, slit width: 1.0mm

At this time, in any of the examples, the injection amount of the substance was stable, the continuous molding stability was also good, and the processability was good. In addition, when the biodegradability of such bags for biodegradable household garbage was measured according to ISO14855, any of the bags for biodegradable household garbage showed a biodegradability of 70% or more.

H. In order to confirm the foaming formability, the granules obtained by mixing 1.8 kg of hydroxy tapioca starch into 3 kg of the biodegradable resin composition granules in each example at 175° C. were used as molding materials using a disintegrator. An extruder (L/D.=30) was used to obtain a foam by extrusion foaming under the following conditions.

Plasticizing temperature: 170°C, molding temperature: 190°C, screw rotation speed: 40s ^-1 , output 3kg/h, moisture control: 12%

At this time, in any of the examples, the extruded amount was stable, the density of the foam was 20 to 45 kg/m ³ , the foaming stability was good, and the processability was good.

Claims (13)

1. the biodegradable resin composition is characterized in that, satisfy following condition (A) and starch ester (B) as form part or all:

(A) hydrogen atom of the reactive hydroxyl of same starch molecule is that 2～4 acyl group (hereinafter referred to as " short chain acyl ") and carbonatoms are that 6～18 acyl group (hereinafter referred to as " long acyl ") replaces by carbonatoms, the substitution value of above-mentioned long acyl is 0.06～2.0, the substitution value of above-mentioned short chain acyl is 0.9～2.7, and the substitution value of total acyl group is 1.5～2.95;

(B) melt flow speed (measuring by JIS K7210) is 0.1～25g/10min.

2. the biodegradable resin composition of record in the claim 1 is characterized in that the melt flow speed of above-mentioned starch ester (is measured by JIS K7210: MFR) be 0.3～20g/10min.

3. the biodegradable resin composition of record in the claim 1 or 2 is characterized in that the substitution value of above-mentioned long acyl is 0.1～1.6, and the substitution value of above-mentioned short chain acyl is 1.2～2.1, and the substitution value of total acyl group is 1.7～2.9.

4. the biodegradable resin composition of record in the claim 1,2 or 3 is characterized in that above-mentioned starch ester is about 30～75 ℃ by the second-order transition temperature (JIS K7121: hereinafter referred to as " second-order transition temperature (Tg) ") of differential scanning calorimetry.

5. the biodegradable resin composition of claim 1 record, it is characterized in that, with respect to above-mentioned starch ester 100 mass parts, the biodegradable resin that constitutes by from cellulose esters biodegradable resin, polyester biodegradable resin and polyvinyl alcohol biodegradable resin, selecting one or more of fusion 20 mass parts～500 mass parts.

6. the biodegradable resin composition of claim 5 record is characterized in that the MFR of above-mentioned biodegradable resin is 2～70g/10min.

7. the biodegradable resin composition of claim 1 record, it is characterized in that: the number-average molecular weight of taking off the ester starch base of above-mentioned starch ester (taking off ester starch base Mn) is 0.5～1.5 with respect to the ratio of the number-average molecular weight (raw starch Mn) of raw starch.

8. the biodegradable resin composition of claim 1 record is characterized in that, above-mentioned starch ester is by vinyl acetate is reacted the starch ester that the back modulation obtains like this as esterifying reagent, the aldehyde that produces when system is discharged esterification.

9. the biodegradable resin processed goods is characterized in that, the biodegradable resin composition of each record in the claim 1～8 as raw material.

10. the Biodegradable film is characterized in that, the biodegradable resin composition of each record in the claim 1～8 as raw material.

11. the Biodegradable multifunctional membrane is characterized in that, the biodegradable resin composition of each record in the claim 1～8 as raw material.

12. the Biodegradable domestic refuse is characterized in that with bag, the biodegradable resin composition of each record in the claim 1～8 is used as raw material.

13. the Biodegradable foam is characterized in that, the biodegradable resin composition of each record in the claim 1～8 is used as raw material.