JP2008031402A - Hydrogenated castor oil-based reaction product, modifier for polylactic acid, polylactic acid composition and polylactic acid molded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydrogenated castor oil-based reaction product produced by reacting hydrogenated castor oil with a lactide or the like, to provide a modifier containing the reaction product, to provide a composition comprising the modifier and polylactic acid, and to provide a formed article, such as a film, using the composition. <P>SOLUTION: This hydrogenated castor oil-based reaction product is characterized by reacting hydrogenated castor oil with a lactide or an α-hydroxy acid linear oligomer. The molar ratio of the hydrogenated castor oil with the lactide is 1:4 to 32. The molar ratio of the hydrogenated castor oil to the linear oligomer is preferably 1 : (8/a to 64/a), wherein a is a value obtained by dividing the weight-average mol.wt. of the linear oligomer with the formula weight of the α-hydroxy acid unit. The modifier for the polylactic acid comprises the hydrogenated castor oil-based reaction product. The polylactic acid composition comprises the polylactic acid and the modifier. It is preferable that the modifier is contained in an amount of 10 to 45 mass%. The polylactic acid molded article uses the polylactic acid composition. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a castor oil-based reaction product, a polylactic acid modifier containing the reaction product, a polylactic acid composition containing the modifier, and a polylactic acid molded article using the composition. About. More specifically, the present invention relates to a castor oil-based reaction product obtained by reacting a castor oil with a chain oligomer of lactide or α-hydroxy acid, containing the reaction product, The present invention relates to a modifier used for plasticization, a polylactic acid composition containing the modifier and polylactic acid, and a polylactic acid molded article such as a film having sufficient biodegradability using the composition.

  In recent years, plastics derived from petroleum resources have been used for a wide range of applications, but these materials can be incinerated to increase the amount of carbon dioxide in the atmosphere, causing global warming, Then, since it is not decomposed or corroded in the environment, there is a concern that it will remain in the soil and cause a shortage of landfill.

  Also, it is known that plastics containing chlorine such as polyvinyl chloride and polyvinylidene chloride in general-purpose resins and plastics containing halogen elements generate harmful substances such as dioxins during incineration. Yes. Therefore, various types of recycling have been studied, but there are many problems in terms of cost and the like, and the situation is that it has not been rapidly spread.

  In view of the above situation, it has become necessary to prevent the global environment from being burdened by actively using materials obtained from biomass that does not depend on fossil resources. In other words, it is made from biomass that can be repeatedly produced and regenerated in cycles of several years to several decades, such as plant materials and animal materials, and is finally corroded and decomposed in the natural environment after use. It is the development of materials that go.

  Such a material is recently called an environmental circulation type material, and does not increase the total amount of carbon dioxide in the global environment, but has a low environmental load that can maintain a balance of carbon balance. Known examples include polylactic acid produced from plant resources such as chitin, chitosan, and corn obtained from cellulose, lignin obtained from woody biomass, crustacean crabs, and the like. Among these, polylactic acid is a thermoplastic plastic, and its calorific value during incineration is less than that of general-purpose resin such as polyethylene, and it is less likely to damage the incinerator. Expected.

  Polylactic acid is a substance produced by microbial fermentation of starch and other substances contained in plant biomass to produce lactic acid by biosynthesis and polymerizing it, and was previously classified as a biodegradable plastic. Recently, however, biodegradation due to the action of microorganisms, etc., with a molecular weight of tens of thousands or more has been slow, and it has become known that decomposition due to hydrolysis action is prioritized, and is now treated as an environmentally-circulating material. It was.

  Polylactic acid has a glass transition point of about 60 ° C. and a melting point of about 170 ° C., is similar to polystyrene in thermal properties, and is a hard resin having excellent transparency in a glass state at room temperature. Because of its disadvantages such as slow biodegradation, lack of impact resistance and poor flexibility, reliable biodegradability in environments similar to the living environment such as agricultural multi-films, general packaging, and food packaging However, the range of application to the fields that require is limited, and on the other hand, research and development is progressing in fields that require rigidity such as casings of electrical products and interior parts of automobiles.

  On the other hand, polylactic acid has properties such as high melting point and high transparency, but in response to the general demand for plastics, research to improve the physical properties of polylactic acid and expand its application range. Development has been done. For example, there is a method (for example, polylactic acid and polyvinyl acetate, polylactic acid and nylon, etc.) of blending an existing petroleum-based plastic with polylactic acid. Also, methods of blending polylactic acid and petroleum-derived biodegradable plastics (for example, polylactic acid and polycaprolactone, polylactic acid and polyvinyl alcohol), low molecular weight plasticizers such as polylactic acid and phthalic acid diester (For example, refer to Patent Document 1), a method for introducing other components into the polylactic acid skeleton by copolymerization (for example, refer to Patent Document 2), a method for stretching and aligning polylactic acid, and the like. .

JP-A-4-335060 Japanese Patent Laid-Open No. 2005-113001

  The above method is performed in order to improve the flexibility and impact resistance of polylactic acid, but in the blend of polylactic acid and petroleum-based non-biodegradable resin, the resin does not partially decompose and remains in the environment. In the blend with petroleum-based biodegradable resin, the blended material is dependent on petroleum, so there are problems such as large environmental load such as increase of carbon dioxide and not becoming transparent resin after all. There is. In the method described in Patent Document 1, since the plasticizer has a low molecular weight, it tends to bleed out, and the flexibility may decrease with time. Furthermore, in the method described in Patent Document 2, it is difficult to control the molecular weight due to the difference in reactivity of each component, and it may be difficult to balance practical flexibility and strength. Thus, it is necessary to improve the flexibility and biodegradability while maintaining the characteristics and transparency of polylactic acid as an environmentally conscious material.

  The present invention has been made in view of the above situation, and castor produced by ester bonding of 2 to 24 lactic acid molecules to the hydroxyl group in the molecule of castor hydrogenated oil derived from environmentally circulating plant biomass. Hardened oil-based reaction product, a modifier used to modify polylactic acid, in particular plasticization, containing this reaction product, a polylactic acid composition containing this modifier and polylactic acid, and this composition An object of the present invention is to provide a polylactic acid molded article such as a film having a practical tensile elongation and improved biodegradability, without loss of transparency inherent in polylactic acid. To do.

By reacting castor oil and lactide, etc., and adding lactide or the like to the hydroxyl group of castor oil, 4 to 32 lactides (a considerable amount of chain oligomers) per molecule of castor oil It has been found that a reaction product useful as a modifier for plasticizing polylactic acid can be obtained by adding (having an α-hydroxy acid unit). This reaction product improves the flexibility of polylactic acid, which is poor in flexibility and is not easily developed for use in films, etc., for example, when formed into a film, it can sufficiently improve its elongation. It was also found that biodegradability can be improved.
The present invention has been made based on such knowledge.

The present invention is as follows.
1. A castor oil-based reaction product obtained by reacting a castor oil with a chain oligomer of lactide or α-hydroxy acid.
2. 1. The molar ratio of the castor oil hardened to the lactide is 1: 4 to 32. The castor oil-based reaction product described in 1.
3. When the value obtained by dividing the weight average molecular weight of the chain oligomer by the formula amount of the α-hydroxy acid unit is 1: (8 / a to 64) / A) above. The castor oil-based reaction product described in 1.
4). 1. The weight average molecular weight is 1500-5500. To 3. The castor hydrogenated oil-type reaction product of any one of these.
5. Above 1. To 4. A modifier for polylactic acid containing the castor oil-based reaction product according to any one of the above.
6). Polylactic acid and 5. A polylactic acid composition comprising the polylactic acid modifier described in 1.
7). When the total of the polylactic acid and the castor oil-based reaction product contained in the polylactic acid modifier is 100% by mass, the castor oil-based reaction product is 10 to 45% by mass. The above 6. The polylactic acid composition according to 1.
8). Above 6. Or 7. A polylactic acid molded article comprising the polylactic acid composition described in 1.
9. The above 8. which is in the form of a film or sheet. The polylactic acid molded article according to 1.

The castor oil-based reaction product of the present invention is useful as a modifier for plasticizing polylactic acid, and can plasticize poorly flexible polylactic acid, and requires flexibility. , It is possible to produce a molded body that can be disposed of by biodegradation, particularly a molded body such as a film.
In addition, when the molar ratio of castor oil to lactide is 1: 4 to 32, and the molar ratio of castor oil to chain oligomer is the weight average molecular weight of the chain oligomer is α-hydroxy acid unit. When the value obtained by dividing by the formula amount of a is 1: (8 / a to 64 / a), it is excellent in action as a modifier and bleeds out when blended with polylactic acid. It can be a difficult reaction product.
Furthermore, when a weight average molecular weight is 1500-5500, it can be set as the reaction product which has the effect | action as a more superior modifier.
According to the modifier for polylactic acid of the present invention, it can be sufficiently plasticized when blended with polylactic acid and can improve biodegradability.
According to the polylactic acid composition of the present invention, a molded product that requires flexibility can be produced, and the molded product can be biodegraded.
When the total of polylactic acid and castor oil-based reaction product contained in the polylactic acid modifier is 100% by mass, the castor oil-based reaction product is 10 to 45% by mass. In this case, polylactic acid having poor flexibility can be sufficiently plasticized, and the physical properties and the like of a molded body using this polylactic acid composition can be improved.
The polylactic acid molded article of the present invention has practical strength due to the plasticizing action of the modifier and can be biodegraded.
Moreover, when a molded object is a form of a film or a sheet | seat, it can be set as the film or sheet | seat which has sufficient elongation, biodegradability, etc.

The present invention will be described in detail below.
[1] Castor hydrogenated oil-based reaction product The castor hydrogenated oil-based reaction product of the present invention is obtained by reacting a castor hydrogenated oil with a chain oligomer of lactide or α-hydroxy acid.
The above “castor hydrogenated oil” is produced by hydrogenating castor oil. This castor oil has about 2.7 hydroxyl groups per molecule, and a reaction product is generated by adding a ring-opened lactide or the like to this hydroxyl group.

The “lactide” is a cyclic dimer of α-hydroxy acid. As this lactide, a cyclic dimer of α-hydroxy acid having 2 to 3 carbon atoms can be used. That is, lactide is a cyclic dimer of glycolic acid and / or a cyclic dimer of lactic acid. The type of lactide is not particularly limited, and only one type may be used, or two types may be used in combination.
The lactide is preferably a cyclic dimer of lactic acid which is an α-hydroxy acid having 3 carbon atoms. Examples of the cyclic dimer of lactic acid include L-lactide, which is a cyclic dimer of L-lactic acid, D-lactide, which is a cyclic dimer of D-lactic acid, and a cyclic dimer of D-lactic acid and L-lactic acid. And meso-lactide and DL-lactide which is a racemic mixture of D-lactide and L-lactide. Any of these lactides may be used. Moreover, only 1 type may be used and 2 or more types may be used together. As a lactide, it is preferable to use L-lactide and / or D-lactide, and it is more preferable to use L-lactide.

  The blending ratio of castor oil and lactide is not particularly limited, but castor oil and lactide are blended at a molar ratio of 1: 4 to 32, particularly 1: 5 to 25, more preferably 1: 6 to 18, and reacted. It is preferable. When castor oil and lactide are reacted at this molar ratio, an average of 1.5 to 11.9, particularly 1.8 to 9.3, and more particularly 2.2 to 1, per hydroxyl group of castor oil. ˜6.7 lactides can be added to provide a reaction product excellent in the action of plasticizing polylactic acid.

The “chain oligomer” is a polymer of α-hydroxy acid. As this chain oligomer, a chain oligomer of an α-hydroxy acid having 2 to 3 carbon atoms can be used. The degree of polymerization of the oligomer is not particularly limited, but it is preferable to use an oligomer having a degree of polymerization of 6 to 14, particularly 8 to 12. Examples of the chain oligomer include a chain oligomer of lactic acid and a chain oligomer of glycolic acid.
As this chain oligomer, a chain oligomer of lactic acid which is an α-hydroxy acid having 3 carbon atoms is preferable. Lactic acid includes L-lactic acid, D-lactic acid, and DL-lactic acid, and any of these lactic acids may be used. Moreover, only 1 type may be used and 2 or more types may be used together. As lactic acid, it is preferable to use L-lactic acid and / or D-lactic acid, and it is more preferable to use L-lactic acid.

The blending ratio between the castor oil and the chain oligomer is not particularly limited, and can be set according to the weight average molecular weight of the chain oligomer. This blending ratio is to generate a reaction product in which the same number of α-hydroxy acid units are added as in the case where the above castor oil is reacted with lactide on an average per hydroxyl group of the castor oil. It is preferable that the blending ratio is such that That is, when a value obtained by dividing the weight average molecular weight of the chain oligomer by the formula amount of the α-hydroxy acid unit is a, castor oil and the chain oligomer are 1: (8 / a to 64 / a), In particular, it is preferable to mix and react at a molar ratio of 1: (10 / a to 50 / a) and further 1: (12 / a to 36 / a). If it does in this way, it can be set as the reaction product excellent in the effect | action which plasticizes polylactic acid.
The above formula weight is the formula weight of the portion excluding the hydrogen of the hydroxyl group of the α-hydroxy acid and the hydroxyl group of the carboxyl group.

The weight average molecular weight measured by the method in the examples described later of the reaction product is not particularly limited. This weight average molecular weight should just be 1500-5500, and it is preferable that it is 1700-4500, especially 1800-3500. That is, an average of 1.5 to 11.9, particularly 1.8 to 9.3, and further 2.2 to 6 per one hydroxyl group of the castor oil is added to one castor oil molecule. .7 lactide, or reaction product in which 3.0 to 23.8, particularly 3.6 to 18.6, and further 4.4 to 13.4 lactic acid units or glycolic acid units are added. It is preferable. If it is such a reaction product, it can be set as the reaction product excellent by the effect | action etc. which plasticize polylactic acid. When this molecular weight is large, the transparency of the polylactic acid composition described in [6] below is good, and the reaction product does not bleed out from the composition. On the other hand, when the molecular weight is small, the flexibility of the polylactic acid composition is further improved. In addition, the biodegradability of the composition can be similarly improved regardless of the molecular weight. Therefore, it is preferable to set the molecular weight while taking into consideration the characteristics particularly required for the polylactic acid composition.
In addition, if the weight average molecular weight of the reaction product is excessive, for example, if the weight average molecular weight exceeds about 7000, the tensile strength does not decrease greatly, but the elongation decreases or is notable regardless of the blending amount. There is no improvement, which is not preferable.

[2] Method for producing castor oil-based reaction product The method for producing the castor oil-based reaction product of the present invention is not particularly limited, and can be produced, for example, by the following method.
The castor oil and the lactide or chain oligomer can be produced by using each of them in the molar ratio described in [1] above and reacting at 70 to 180 ° C. in the presence of a catalyst. The reaction temperature is preferably 80 to 150 ° C, particularly 90 to 120 ° C. In addition, this reaction can be a two-stage reaction in which the reaction is performed in a relatively low temperature range within the above temperature range and then the reaction is performed in a relatively high temperature range. Further, in order to suppress decomposition and coloring of lactide and the like, the reaction is preferably performed in an inert atmosphere such as a nitrogen gas atmosphere or an inert gas atmosphere such as argon. Further, it is preferable to dry castor oil and lactide before the reaction to remove moisture. The reaction time is not particularly limited, but can be 10 minutes to 20 hours, particularly 1 to 20 hours, and further 12 to 18 hours.

  The catalyst used for the reaction is not particularly limited, and for example, a catalyst generally used in an esterification catalyst, a ring-opening polymerization catalyst, or the like can be used. As this catalyst, (1) tin octoate, tin lactate, tin tartrate, dicaprylate, tin dilaurate, tin dipalmitate, tin distearate, dioleate, tin α-naphthoate, tin β-naphthoate Tin compounds such as tin dioctylate, (2) zinc compounds such as zinc halide and zinc oxide, (3) titanium compounds such as tetraisopropoxy titanate, (4) zirconium compounds such as zirconium isopropoxide, (5) Antimony compounds such as antimony trioxide, (6) bismuth compounds such as bismuth oxide, and (7) aluminum compounds such as aluminum oxide and aluminum isopropoxide. Of these, highly active tin compounds are preferred. The amount of the catalyst used is 0.1 to 5 parts by mass, particularly 0.5 to 4 parts by mass, and further 1 to 3 parts by mass, when the total of castor oil and lactide or chain oligomer is 100 parts by mass. It is preferable that

  In order to make the castor oil and lactide or chain oligomer react efficiently, it is preferable to mix the castor oil and lactide in advance more uniformly. The mixing method is not particularly limited. For example, castor oil and lactide are charged into a reaction vessel, and a necessary amount of solvent is further charged, heated to increase the temperature, and mixed by stirring. it can. The temperature at the time of stirring can be set to the same level as the temperature at the time of the above reaction. Moreover, the solvent should just be a solvent which can fully dissolve castor oil and lactide etc. at the temperature at the time of stirring, for example, toluene, xylene, etc. can be used. Furthermore, it is preferable to mix in an inert atmosphere as in the reaction. The mixing time is not particularly limited, but can be 30 minutes to 3 hours, particularly 40 minutes to 2 hours. After this mixing, the reaction solution can be produced by using the mixed solution as it is as the reaction solution and reacting under the above reaction conditions.

  The method for recovering the reaction product from the reaction solution after completion of the reaction is not particularly limited. For example, the reaction product is poured into a poor solvent having a volume ratio of 2 to 10 times, particularly 3 to 8 times, at room temperature (20 to 25 ° C., hereinafter, the temperature range of “room temperature” is the same). Then, the reaction product can be recovered by removing the supernatant. Moreover, it is preferable that the reaction product is washed with a poor solvent and then dried under reduced pressure to sufficiently remove the reaction solvent and the poor solvent. The poor solvent should just be a solvent which can fully precipitate a reaction product from a reaction liquid, For example, hexane, a cyclohexane, etc. can be used. If unreacted lactide or the like remains after completion of the reaction, it can be removed by repeating reprecipitation.

[3] Polylactic acid modifier The polylactic acid modifier of the present invention (hereinafter sometimes referred to as a modifier) contains the castor oil-based reaction product of the present invention.
This modifier for polylactic acid is excellent in the modification of polylactic acid, in particular, the effect of plasticizing and the effect of improving biodegradability. That is, this modifier can be used as a plasticizer for polylactic acid. This modifier can also be used as a biodegradability improver for polylactic acid. The content of the castor oil-based reaction product in the polylactic acid modifier is preferably 80% by mass or more, particularly 90% by mass or more, when the modifier is 100% by mass. More preferably, the total amount of the polylactic acid modifier is a castor oil-based reaction product.

  The modifier for polylactic acid may contain a filler such as calcium carbonate or an extender such as talc as long as the effect of plasticizing polylactic acid is not impaired. . The content of these other components is preferably 20% by mass or less, particularly preferably 10% by mass or less, when the polylactic acid modifier is 100% by mass.

[4] Polylactic acid composition The polylactic acid composition of the present invention contains polylactic acid and the modifier for polylactic acid of the present invention.
Examples of the “polylactic acid” include a homopolymer of lactic acid or a copolymer of lactic acid and glycolic acid. A homopolymer of lactic acid can be produced by dehydrating polycondensation of L-lactic acid and / or D-lactic acid. As this lactic acid, L-lactic acid is preferably used. The homopolymer is produced by ring-opening polymerization of one or more cyclic dimers of L-lactide, D-lactide, meso-lactide and DL-lactide, which are cyclic dimers of lactic acid. You can also. As this lactide, it is preferable to use L-lactide.

  On the other hand, the copolymer can be produced by dehydrating polycondensation of L-lactic acid and / or D-lactic acid and glycolic acid. The copolymer can also be produced by ring-opening polymerization of at least one of the above cyclic dimers of lactic acid and glycolide. L-lactide is preferably used as the cyclic dimer of lactic acid. The ratio of lactic acid units to glycolic acid units in the copolymer is not particularly limited, but the lactic acid units are preferably 85 mol% or more.

  The average molecular weight of each of the homopolymer and the copolymer is not particularly limited. For example, the weight average molecular weight measured by gel permeation chromatography is 50,000 or more, particularly 50,000, for both the homopolymer and the copolymer. ˜500,000, more preferably 70,000 to 300,000.

  When L-lactic acid and D-lactic acid are used as lactic acid, their use ratio is not particularly limited, but when the total of L-lactic acid and D-lactic acid is 100 mol%, L-lactic acid is 80 mol%. As mentioned above, it is especially preferable that it is 95 mol% or more. If L-lactic acid is 80 mol% or more, it can be set as a polymer with high transparency and a high melting point. Further, when L-lactide and D-lactide are used as the lactide, the use ratio thereof is not particularly limited, but when the total of L-lactide and D-lactide is 100 mol%, L-lactide is 80%. It is preferably at least mol%, particularly at least 95 mol%. When L-lactide is 80 mol% or more, a polymer having high transparency and a high melting point can be obtained.

  The blending method of the modifier for polylactic acid of the present invention into polylactic acid is not particularly limited, and it can be blended by a conventional method of blending various additives such as a modifier with the resin. For example, it can mix | blend by the method of using an extruder, a kneader, a heating roll, and these apparatuses in combination. Among these apparatuses, an extruder is preferable, and as this extruder, a single screw extruder, a twin screw extruder, or the like can be used, and a twin screw extruder is preferable. In addition, an extruder provided with a vent port is preferable in order to remove the remaining volatile matter and the like under reduced pressure after kneading. The blending temperature is not particularly limited, but is usually 120 to 250 ° C, preferably 150 to 200 ° C.

  The content of the modifier for polylactic acid in the polylactic acid composition is not particularly limited, and is preferably set according to physical properties required for the polylactic acid composition, its use, and the like. Since the modifier for polylactic acid of the present invention has an excellent action as a plasticizer, it is preferable to set the content particularly depending on the flexibility required for a molded article using the polylactic acid composition. Content of the modifier for polylactic acid is the content of castor oil-based reaction product when the total of polylactic acid and castor oil-based reaction product contained in the modifier is 100% by mass. The content is preferably 10 to 45% by mass. This content is preferably 10% by mass or more, particularly preferably 20% by mass or more in order to greatly improve the flexibility, and the weight average molecular weight of the reaction product is 1500 to 3500 (preferably 2000 to 3000). In some cases, it is preferably 13 to 27% by mass. When the weight average molecular weight of the reaction product exceeds 3500, and when it is ˜5500 (preferably 4000 to 5000), it is preferably 23 to 37% by mass. Further, the modifier can be contained in excess of the above upper limit value, but as the content increases, the modifier bleeds out, and the polylactic acid composition and the molded body using the same over time. It is not preferable because it may be altered.

  In addition to polylactic acid and the polylactic acid modifier of the present invention, other components can be blended in the polylactic acid composition of the present invention. Examples of the other components include conventionally used plasticizers such as phthalate esters and other additives. Examples of this additive include anti-blocking agents, heat stabilizers, light stabilizers, antioxidants, ultraviolet absorbers, matting agents, pigments, colorants, inorganic fillers, organic fillers, antistatic agents, release agents. Examples include molds, fragrances, lubricants, flame retardants, foaming agents and antibacterial agents.

[5] Polylactic acid molded article The polylactic acid molded article of the present invention uses the polylactic acid composition of the present invention.
The method for producing a molded body using the polylactic acid composition is not particularly limited, and can be produced by an ordinary resin molding method. Examples of the molding method include extrusion molding, injection molding, vacuum molding, and compression molding. The molding conditions are not particularly limited, and can be normal molding conditions for polylactic acid. For example, in the case of extrusion molding, a polylactic acid composition in the form of pellets is heated in a cylinder, melted and kneaded, and then continuously extruded from a molding die adjusted to a temperature exceeding the melting point of polylactic acid. Can be molded. In the case of injection molding, a polylactic acid composition in the form of pellets is heated in a cylinder, melted and kneaded, and then injected into a mold adjusted to a temperature exceeding the melting point of polylactic acid and cooled. Then, it can be molded by solidifying.

The type of the molded body is not particularly limited, and various molded bodies such as a film, a sheet, a container, and a tubular body can be used. Moreover, the usage of the molded body is not particularly limited, and it can be a molded body used as a packaging material for food packaging, daily miscellaneous goods, industrial materials, agricultural materials, and horticultural materials. Furthermore, since the polylactic acid having high rigidity and poor flexibility is sufficiently plasticized by the modifier for polylactic acid of the present invention, such as films and sheets that could not be formed into a molded body until now. It can be set as a molded body. Thus, since it can be set as molded bodies, such as a film and a sheet | seat which have biodegradability in particular, it is useful as agricultural and horticultural materials, such as a packaging material with low environmental impact, and an agricultural multi film.
It should be noted that the film and the sheet are different in thickness, and are molded bodies used in specific applications depending on the thickness.

Hereinafter, the present invention will be described specifically by way of examples.
[1] Production of castor oil-based reaction product Example 1
939 parts by mass of castor hydrogenated oil and 1061 parts by mass of L-lactide, which is a cyclic dimer of L-lactic acid, are put into a reaction vessel (molar ratio of castor hydrogenated oil and L-lactide is 1: 7.4). In addition, toluene was added as a solvent. Thereafter, the atmosphere was replaced with a nitrogen gas atmosphere, and the mixture was heated with stirring at 100 to 110 ° C. for 1 hour. Next, 2 parts by mass of tin octoate was added as a catalyst and reacted at 100 to 110 ° C. for 16 hours. Thereafter, the reaction solution was put into about 5 times amount of hexane and cooled. Next, the supernatant was removed, and the remainder was washed with hexane, and then dried under reduced pressure at 120 ° C. for 2 hours to obtain a reaction product. The obtained reaction product was a colorless liquid having a high viscosity.

  The reaction product had a weight average molecular weight of 2,300 as measured by gel permeation chromatography (GPC). Further, no shoulder was observed in the molecular weight distribution curve of GPC, and it was found that reaction products having almost the same molecular structure were formed.

Comparative Example 1
A reaction product was obtained in the same manner as in Example 1 except that castor oil was used instead of castor oil. The obtained reaction product was a colorless liquid having a high viscosity. The weight average molecular weight measured by GPC of this reaction product was 2300. The shoulder was not recognized in the molecular weight distribution curve of GPC, and it was found that reaction products having almost the same molecular structure were formed.

The measurement conditions of the above GPC are as follows.
Device: Showa Denko (model "Shodex 104")
Solvent; Tetrahydrofuran Solvent flow rate; 0.6 ml / min Calibration curve standard; Polyethylene glycol

[2] Heat loss of reaction product, acid value and hue Experimental Examples 1-6
The reaction product of Example 1 (indicated as “HCO / L-Ltd (a)” in Table 1 and hereinafter referred to as “HCO / L-Ltd (a)”) and the reaction product of Comparative Example 1 (In Table 1, “CO / L-Ltd” is described. In addition, hereinafter, it is referred to as “CO / L-Ltd”.) Each heating loss, oxidation, and hue were measured. In Experimental Example 1, acid value and hue were measured without heating HCO / L-Ltd (a), and in Experimental Example 2, HCO / L-Ltd (a) was heated at 150 ° C. for 3 hours, and then The weight loss on heating, the acid value and the hue were measured, and Experimental Example 3 measured HCO / L-Ltd (a) at 180 ° C. for 3 hours, and then measured the heat loss, acid value and hue. is there. Experimental Example 4 was obtained by measuring the acid value and hue without heating CO / L-Ltd. Experimental Example 5 heated CO / L-Ltd at 150 ° C. for 3 hours. The acid value and hue were measured. In Experimental Example 6, CO / L-Ltd was heated at 180 ° C. for 3 hours, and then the loss on heating, acid value and hue were measured.

The measuring method is as follows.
(1) Loss on heating: Measured according to JIS K0067.
(2) Acid value: measured according to JIS K0070.
(3) Hue: Measured according to JIS K0071-2. Specifically, it was measured using a Gardner colorimeter and displayed with a Gardner-Heligue standard number.
When the color of the sample is between the two colored glasses, it is displayed in five levels, for example, 5, 5+, 5-6, 6 and 6.
The results are listed in Table 1.

  According to the results in Table 1, the heating loss and the acid value are HCO / L-Ltd (a) and CO / L-Ltd when heating is not performed and when heating is performed at 150 ° C. or 180 ° C. It can be said that there is no difference. However, when heated, especially when heated at 180 ° C., CO / L-Ltd (Experimental Example 6) is inferior to HCO / L-Ltd (a) (Experimental Example 4). It turns out that the coloring component resulting from the unsaturated bond which produced | generated has produced | generated.

[3] Physical properties of polylactic acid composition (Part 1)
Experimental Examples 7-10
To the flask, HCO / L-Ltd (a) (also expressed as “HCO / L-Ltd (a)” in Table 2) was added so as to have the mass ratio shown in Table 2, and then polylactic acid was added. (Mitsui Chemicals, trade name “LACEA H-400”) was added (the total of HCO / L-Ltd (a) and polylactic acid is 100% by mass). Next, chloroform was added and the mixture was allowed to stand at room temperature for 12 hours, and then stirred at room temperature with a stirrer bar for 3 hours. Next, the solvent was recovered by an evaporator to obtain a solid mixture. Thereafter, this mixture was dried at 50 to 60 ° C. under reduced pressure for 5 to 6 hours to produce a polylactic acid composition. Next, using this polylactic acid composition, test pieces for measuring the respective physical properties were produced by extrusion at 180 ° C., and the physical properties were evaluated.

The measuring method is as follows.
(1) Elongation and tensile strength: Measured according to JIS K 7113.
Equipment: manufactured by Shimadzu Corporation (Shimadzu Autograph, model “AGS-10KNG”)
Test piece: Dumbbell shape (length 45 mm, width 5 mm, thickness 2.7 mm)
Distance between grips: 15mm
Tensile speed: 5 mm / min Measurement environment: Temperature 23 ° C., relative humidity 50%
(2) Bending strength: measured in accordance with JIS K 7113.
Equipment: manufactured by Shimadzu Corporation (trade name “Autograph”, model “AGS-50KNG”)
Test piece: prismatic shape (length 50 mm, width 6 mm, thickness 4 mm)
Crosshead moving speed: 5 mm / min Measurement environment: Temperature 23 ° C., relative humidity 50%
(3) Impact strength: Measured according to the Charpy impact test method of JIS K 7111.
Equipment: Tokyo Test Machine Co., Ltd. (Instrumented Charpy Tester, Model “CI-8E”)
Test piece: prismatic shape (length 50 mm, width 6 mm, thickness 4 mm)
Measurement environment; temperature 23 ° C, relative humidity 50%
The results are listed in Table 2.

  According to the results in Table 2, it can be seen that when HCO / L-Ltd (a) is blended with polylactic acid, the impact strength is improved as the blending amount is increased. In particular, in Experimental Example 9 in which 20% by mass of HCO / L-Ltd (a) was blended, it can be seen that the absorbed energy value up to the maximum energy value was large, and the flexibility of the composition was greatly improved. Furthermore, in Experimental Example 10 in which 30% by mass of HCO / L-Ltd (a) is blended, it can be seen that the absorbed energy value after the maximum energy value is large, and the flexibility of the composition is greatly improved. Elongation is also improved by the blending of HCO / L-Ltd (a). In particular, in Example 9 where 20% by mass of HCO / L-Ltd (a) is blended, the elongation is remarkably improved. There is expected. On the other hand, the tensile strength and bending strength tend to decrease with an increase in the amount of HCO / L-Ltd (a), but this is not a significant decrease.

[4] Physical properties of polylactic acid composition (part 2)
Polylactic acid compositions were produced using HCO / L-Ltd having different average molecular weights, and their elongation and tensile strength were evaluated.
(1) Production of HCO / L-Ltd with different average molecular weights Example 2
A reaction product was obtained in the same manner as in Example 1 except that 939 parts by weight of castor hydrogenated oil and 2061 parts by weight of L-lactide were used (in Table 3, expressed as “HCO / L-Ltd (b)”). Hereinafter, it is also referred to as “HCO / L-Ltd (b)”). The resulting reaction product was a colorless wax. The average molecular weight of the reaction product thus obtained is about 3000.
Example 3
A reaction product was obtained in the same manner as in Example 1 except that 939 parts by weight of castor hydrogenated oil and 3061 parts by weight of L-lactide were used (in Table 3, expressed as “HCO / L-Ltd (c)”). Hereinafter, it is also referred to as “HCO / L-Ltd (c)”). The resulting reaction product was a colorless wax. The average molecular weight of the reaction product thus obtained is about 4000.
Example 4
A reaction product was obtained in the same manner as in Example 1 except that 939 parts by weight of castor hydrogenated oil and 4061 parts by weight of L-lactide were used (in Table 3, expressed as “HCO / L-Ltd (d)”). Hereinafter, it is also referred to as “HCO / L-Ltd (d)”). The obtained reaction product was a white solid. The average molecular weight of the reaction product thus obtained is about 5000.

(2) Production of polylactic acid composition and evaluation of physical properties Experimental Examples 11 to 28
A polylactic acid composition was produced in the same manner as in the above [3] except that the reaction products of Examples 2 to 4 were used at the mass ratios shown in Table 3. Thereafter, using this polylactic acid composition, elongation and tensile strength were measured by the methods described in [3] and (1) above.
Although a polylactic acid composition was produced using castor oil instead of HCO / L-Ltd, this polylactic acid composition was not easy to mold, and a test for measuring elongation and tensile strength. The piece could not be molded.
The results are listed in Table 3.

  According to the results in Table 3, the elongation was improved regardless of the type and amount of HCO / L-Ltd. In particular, when the blending amount is 15 to 25% by mass in HCO / L-Ltd (b), and when the blending amount is 30 to 35% by mass in HCO / L-Ltd (c), HCO / L-Ltd ( In d), when the blending amount was 25 to 30% by mass, a remarkable improvement in elongation was observed. Moreover, in any case of HCO / L-Ltd (b), (c), and (d), there was no significant difference in the tensile strength of the polylactic acid composition.

[5] Physical properties of polylactic acid composition (part 3)
Experimental Examples 29-32
The glass transition point and melting point of a polylactic acid composition produced in the same manner as in [3] above using HCO / L-Ltd (a) (also expressed as HCO / L-Ltd (a) in Table 4) are as follows: It measured by the method of.
(1) Glass transition point and melting point: Measured using a differential scanning calorimeter according to JIS K7121.
Apparatus; manufactured by Bruker, Inc. The results are shown in Table 4.

  According to the results in Table 4, the glass transition point tends to decrease regardless of the amount of HCO / L-Ltd (a), and polylactic acid and HCO / L-Ltd (a) are uniformly mixed. I understand that Further, since HCO / L-Ltd (a) has no melting point, the melting points of Experimental Examples 29 to 32 are all the melting points of polylactic acid itself, but in Experimental Examples 30 to 32, HCO / L- There is a tendency that the melting point shifts to the low temperature side due to the blending of LTD (a).

[6] Physical properties of polylactic acid composition (part 4)
Experimental Examples 33-40
The above [3] using HCO / L-Ltd (a) and HCO / L-Ltd (b) (also expressed as HCO / L-Ltd (a) or HCO / L-Ltd (b) in Table 5). The bleedability and transparency of the polylactic acid composition produced in the same manner as above and the polylactic acid composition produced in the same manner using castor oil instead of HCO / L-Ltd were measured by the following methods.
(1) Bleed property: When the temperature of a test piece having a length of 45 mm, a width of 6 mm, and a thickness of 4 mm produced by extrusion molding was lowered to room temperature, the appearance was visually observed to confirm the presence or absence of bleed.
(2) Transparency: Two straight lines having a width of 0.5 mm and a length of 10 mm are drawn on the paper so as to face each other with an interval of 3 mm, and a dumbbell-shaped test piece having a thickness of 6 mm is formed on the straight line. It was visually determined whether or not two straight lines could be discriminated.
The results are listed in Table 5.

  According to the results of Table 5, regarding the bleeding property, there is no difference due to HCO / L-Ltd (a), (b) and no difference due to the respective blending amounts, both being good. On the other hand, when castor oil was blended with polylactic acid, bleeding was observed even when the blending amount was as small as 5% by mass. Moreover, also about transparency, there is no difference by HCO / L-Ltd (a) and (b), and the difference by each compounding quantity, and all are favorable. On the other hand, when castor hydrogenated oil was blended with polylactic acid, a decrease in transparency was observed even when the blending amount was as small as 5% by mass.

[7] Biodegradability of polylactic acid composition containing reaction product Experimental Examples 41 to 46
(1) Preparation of sample film HCO / L-Ltd (a) (also expressed as HCO / L-Ltd (a) in Table 6) and polylactic acid (trade name “LACEA H-400” manufactured by Mitsui Chemicals, Inc.) ) Were weighed so as to have the mass ratios shown in Table 6 (the total of HCO / L-Ltd (a) and polylactic acid was 100% by mass). Thereafter, polylactic acid was charged into the container, and chloroform was further charged to dissolve the polylactic acid. Next, HCO / L-Ltd (a) was added and dissolved by stirring for 3 hours. Thereafter, the solution was poured into a vat coated with polytetrafluoroethylene and cast into the vat. Subsequently, it was left still for 5 days in a fume hood, and chloroform was volatilized to form a film. A specimen having a diameter of 11.5 mm was cut out from this film (thickness is about 50 μm) using a cork borer.
(2) Preparation of reaction solution Weigh 5 ml of Tris-HCl buffer (pH = 8.6) into a screw vial tube, and add proteinase K (from Tritirachium album min. 30 units / mg protein, Lyophilized powder, Sigma-Aldrich Co., Ltd.) (Purchased from a company) 1 mg and sodium azide 1 mg were added to prepare a reaction solution.
(3) Evaluation of biodegradability Each specimen prepared in the above (1) was weighed with an ultraprecision microbalance (measurement lower limit 0.001 mg), immersed in the reaction solution prepared in the above (2), and 37 ° C. It was left still in the incubator set to. Thereafter, each time a predetermined time elapses, the specimen is taken out with tweezers, gently washed with the buffer solution described in (2) above, then the moisture is wiped off and weighed with the above-mentioned balance, and proteinase K was used as the enzyme. When biodegradability was evaluated.
The results are listed in Table 6 and shown in FIG. In Table 6, the upper part is the mass (unit: mg) of the specimen, and the lower parenthesis is the mass ratio (unit:%) after a predetermined time with respect to the initial mass.
Mass ratio (%) = (mass after predetermined time / initial mass) × 100

  According to the results of Table 6 and FIG. 1, in Experimental Example 41 in which HCO / L-Ltd (a) was not blended, the ratio to the initial mass was as high as 89.6% even after 5 hours had passed. It turns out that decomposition is not enough. On the other hand, in Experimental Examples 42 to 46, it can be seen that the decomposition is accelerated as compared with Experimental Example 41. More specifically, even in Experimental Example 42 in which the blending amount of HCO / L-Ltd (a) is as small as 5% by mass, decomposition is clearly promoted compared with Experimental Example 41, and the blending amount is 15% by mass. In Experimental Example 44, the mass is almost halved, and in Experimental Example 46, the blending amount is 30% by mass, the mass is reduced to a little less than 1/3. As described above, the decomposition is sufficiently accelerated in only 5 hours, and it is confirmed that the castor oil-based reaction product of the present invention has sufficient action and effect for promoting the biodegradation of polylactic acid.

  INDUSTRIAL APPLICABILITY The present invention can be used in the field of various molded articles such as general molded films, particularly agricultural films, sheets, tubular bodies and various containers that require biodegradability. Further, the molding method is not particularly limited, and the molding can be performed by various methods such as extrusion molding, injection molding, vacuum molding, and pressure molding.

It is a graph showing the correlation with the compounding quantity of the modifier for polylactic acids, and a biodegradable change with time.

Claims (9)

  A castor oil-based reaction product obtained by reacting a castor oil with a chain oligomer of lactide or α-hydroxy acid.   The castor oil-based reaction product according to claim 1, wherein a molar ratio of the castor oil to the lactide is 1: 4 to 32.   The molar ratio of the castor oil to the chain oligomer is 1: (8 / a) where a is a value obtained by dividing the weight average molecular weight of the chain oligomer by the formula weight of the α-hydroxy acid unit. The castor oil-based reaction product according to claim 1, which is ˜64 / a).   The castor oil-based reaction product according to any one of claims 1 to 3, having a weight average molecular weight of 1500 to 5500.   A polylactic acid modifier, comprising the castor oil-based reaction product according to any one of claims 1 to 4.   A polylactic acid composition comprising polylactic acid and the modifier for polylactic acid according to claim 5.   When the total of the polylactic acid and the castor oil-based reaction product contained in the polylactic acid modifier is 100% by mass, the castor oil-based reaction product is 10 to 45% by mass. The polylactic acid composition according to claim 6.   A polylactic acid molded article comprising the polylactic acid composition according to claim 6 or 7.   The polylactic acid molded article according to claim 8, which is in the form of a film or a sheet.

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