JP2003327814A - Compatible resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compatible resin composition having improved softness represented by elongation at break and mechanical properties represented by tensile strength from a blended resin composed of mutually incompatible poly(ε- caprolactone) (PCL) and poly(lactic acid) (PLA). <P>SOLUTION: The compatible resin composition contains a poly(lactic acid) (PLA), a poly(ε-caprolactone) (PCL) and a solubilizing agent consisting of a poly(ε-caprolactone)-poly(ethylene glycol) block copolymer. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a resin composition having compatibility. More specifically, they do not mix 2
The present invention relates to a compatible resin composition comprising a specific resin of a type and a compatibilizing agent for a copolymer containing a specific block component. Each constituent resin of the resin composition is biodegradable and the resin composition has improved mechanical properties.

[0002]

2. Description of the Related Art Recently, the demand for research and development of biodegradable polymers has increased, and various new polymers having biodegradability have become available. Most of the currently available biodegradable polymers are limited to aliphatic polyesters, polyethers, poly (vinyl alcohol), and natural polysaccharides. The most important of these biodegradable polymers are aliphatic polyesters such as polylactic acid (PLA),
Poly (3-hydroxybutyrate) (PHB), poly (ε-caprolactone) (hereinafter sometimes abbreviated as “PCL”), polyglycolide, poly (butyl succinate), and the like Polymers have received much attention because they are biodegradable in the human body as well as in the global environment.

To date, much research and reporting has been done on the properties and applications of these polyesters. However, many properties of these polyesters have not reached the properties required for possible applications. The properties of these polymers can be improved in several ways, including polymer blends and copolymers. Compared to copolymer synthesis, polymer blends are a relatively simple and fast method, which makes them a popular choice for biocompatible and biodegradable polymer blends from the perspective of biomedical and environmental applications. Was focused.

Polylactic acid (PLA) has been extensively studied and, due to its high biocompatibility, good biodegradability and physical properties, has been widely used for this type of application.
However, one major drawback of PLA is the change from ductile fracture under elongation to brittle fracture with physical aging. In contrast, PCL has a high degree of flexibility, but its strength is relatively low and its melting point is 60 ° C., too low for various practical applications. Therefore, PCL and PL
It is entirely plausible that the blends of A are expected to result in increased flexibility or increased strength when compared to their respective constituents.

In recent years, blends of PLA with a more flexible and biodegradable polymer such as PCL have been developed and studied. There have been some interesting and notable results, even though blends of these two polymers could not exhibit the desired properties due to their immiscibility regardless of composition. Yang, J.-M .; Chen, H.-L .; You,
J.-W .; Hwang, J.-C., Polym. J. 1997, 29, 657)
By using differential scanning calorimetry (DSC) and optical microscopy, poly (L-lactic acid) (PLLA) / PC
Despite the phase separation of the L system in the molten state, the PL
The crystallinity of LA can be increased by blending PCL and it was reported that the partial miscibility between these two polymers promotes the crystallization of PLLA. Using dynamic mechanical thermal analysis (DMTA) and scanning electron microscopy (SEM) measurements, Dell'Erba et al. (Del
l'Erba, R .; Groeninckx, G .; Maglio, G .; Malinconic
O.M .; Migliozzi, A. Polym., 2000, 42, 7831) also report that PLLA and PCL are immiscible but not highly incompatible. As mentioned above, P
CL has relatively low mechanical strength, has a melting point of around 60 ° C. and is too low as a processing temperature, but has high flexibility. Attempts have been made to obtain a resin composition having more improved flexibility and mechanical strength as compared with the respective components by polymer blending these PLA and PCL, but since both resins are immiscible, Mere blends of both resins have not achieved the desired performance.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to improve the compatibility of a mixed resin of PCL and PLA, which are immiscible with each other, in flexibility represented by elongation at break and mechanical properties represented by tensile strength. It is to provide a resin composition.

[0007]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present inventors have earnestly studied based on the recognition that it is important to consider miscibility between polymers in preparing a polymer blend. did. And in view of the above, it is believed that these binary blends can have some domains of fairly good dispersibility, and their domain distribution is related to their composition.
In fact, especially for reactively compatibilized blends, some synergistic composition (PLA / PCL = 80/2
Wang, L .;
Ma, W .; Gross, RA; McCathy, SP Polym. Degra
d. Stab., 1998, 59, 161). PLA /
In order to effectively improve the physical properties of PCL blends, a detailed study of blend composition dependence of phase behavior is required. As a method for improving the miscibility of blends, we investigated a method of increasing interphase adhesion, that is, compatibilization. (Shuai, X .; He, Y .; Na, Y.-H .; Ino
ue, YJ Appl. Polym. Sci., 2001, 80, 2600) One of the effective methods of compatibilization is to pre-prepare a block copolymer consisting of blocks, each of which is miscible with one of the blend constituents, Is to add. These so-called compatibilizers, which often tend to collect at the interface like emulsifiers, convert some immiscible blends to be compatible. The inventors have found that PCL-poly (ethylene glycol) block copolymers (PCL-b) for miscibility, phase behavior and thermal properties.
-PEG) and PLA blend or PCL-monomethoxy-poly (ethylene glycol) block copolymer (PC
Lb-MPEG) and PLA blend,
The effect of PCL-b-PEG as a compatibilizer on the mechanical properties of PCL / PLA blends was investigated. Further, the effects of the blend composition ratio and the thermal history on the phase behavior were examined for the PLA / PCL blend. As a result, they have found that the above problems can be solved by using a specific block copolymer having a segment miscible with each of two immiscible resin components (PCL) and (PLA). The invention was completed.

That is, according to the present invention, poly (lactic acid),
Poly (ε-caprolactone) and poly (ε-caprolactone) -poly (ethylene glycol) as a compatibilizer
Provided is a compatible resin composition containing a block copolymer. In the said invention, the compatible resin composition whose poly (lactic acid) (PLA) is poly (L-lactic acid) (PLLA) is provided. In addition, poly (lactic acid) (PLA) and poly (ε
-Caprolactone) (PCL) in a mixing ratio of ((PLA) / (PCL)) = 1/99 to 99/1 (the total of both is 100% by weight), which is the compatible resin composition according to any one of the above inventions. Things are offered. In addition, poly (lactic acid) (P
100 parts by weight of a mixed resin of LA) and poly (ε-caprolactone) (PCL) is added to poly (ε-caprolactone).
-Poly (ethylene glycol) block copolymers 1-1
There is provided a compatible resin composition of any one of the above inventions, which comprises 100 parts by weight. Further, the (ε-caprolactone) monomer unit and the (ethylene glycol) monomer unit constituting the block copolymer are by weight (ε-caprolactone) unit / (ethylene glycol) unit = 99/1 to 40/60
There is provided the compatible resin composition according to any one of the above inventions (the total of both is 100% by weight).

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. Pure PCL is immiscible with PLA. The process of improving the adhesion between the individual blend component phases in such immiscible blends is called compatibilization. In the present invention, P
CL, PLA and poly (ε-caprolactone) -poly (ethylene glycol) block copolymer (hereinafter referred to as “P
CL-b-PEG ”), both of the elongation at break and the tensile strength of the resin composition are higher than those obtained by simply blending the PCL and PLA polymers. If it is improved, it is regarded as the compatible resin composition of the present invention.

The poly (lactic acid) (PLA) used in the polymer blend in the present invention includes, for example, PLLA, poly (D) lactic acid, poly (DL-lactic acid) (PDLLA), or a mixture thereof. . The selection of PLA is not particularly limited, but it is PLLA from the viewpoint that it is easily available and the effect of the present invention can be more exerted. The molecular weight (number average molecular weight Mn, the same applies hereinafter) is 1
It is preferably 50,000 or more, more preferably 40,000 or more. It should be noted that the same effect as that of the present invention can be expected even if polyglycolic acid (PGA) is used instead of or together with PLA in the present invention. Poly (ε-caprolactone) (PCL), which is the other polymer used in the polymer blend, is important in terms of imparting mechanical strength and flexibility to the polymer blend, but there are particular restrictions on selection. There is no. Number average molecular weight is 1
It is preferably 50,000 or more, more preferably 50,000 or more. In addition, PCL includes those mainly composed of ε-caprolactone and copolymerized with other lactones as long as the effects of the present invention are not impaired. The blend ratio of PLA and PCL (PLA / PCL) is determined by the function required for the intended polymer blend and is not particularly limited, but is 1/99 to 99/1 by weight (the total of both is 100% by weight. ), And more preferably 20/80 to 80/20.

The poly (ε-caprolactone) -poly (ethylene glycol) block copolymer (PCL-b-PEG) used in the present invention comprises poly (ε-caprolactone) (PCL) and poly (ethylene glycol) (PE).
G) or monomethoxy-poly (ethylene glycol)
(Hereinafter, sometimes abbreviated as "MPEG"), which is a block copolymer, preferably the former and used as a compatibilizer. The PCL unit constituting one block of the block copolymer is not particularly limited, but P
The average molecular weight of CL block is 1,000 or more, moreover 1
It is preferably 10,000 or more. The average molecular weight of the PCL block unit of the block copolymer can be controlled by the reaction conditions of the block copolymer when synthesizing the block polymer (for example, the charging ratio of ε-caprolactone monomer, the reaction temperature, etc.). The PCL block includes not only ε-caprolactone alone, but also copolymers containing ε-caprolactone as a main component and copolymerized with other lactones as long as the effects of the present invention are not impaired. Further, P constituting the other block of the block copolymer
There is no particular limitation for EG or MPEG, but PE
The average molecular weight of the G block is 500 to 300,000,
Furthermore, 1,000-100,000 are preferable. Alternatively, the average molecular weight of the MPEG block is 500 to 300,0.
00, and more preferably 500 to 100,000. PE
The molecular weight of G or MPEG block unit is too small,
Alternatively, if it is too large, the compatibilizing effect becomes difficult to be exhibited. P
The number average molecular weight of CL-b-PEG is preferably 1,500 or more, and more preferably 10,000 or more. If the number average molecular weight is less than 1,000, compatibilizing effects such as mechanical strength and flexibility are less likely to appear, so it may be appropriately determined in consideration of the molecular weights of PLA and PCL used in the blend. In the poly (ε-caprolactone) -poly (ethylene glycol) block copolymer used in the present invention, instead of the poly (ethylene glycol) block, a poly (propylene glycol) block or poly (ethylene glycol / propylene glycol) is used. A block copolymer using random blocks can be used as well.

The ratio of the (ε-caprolactone) monomer unit and the (ethylene glycol) monomer unit constituting the block copolymer is not particularly limited, but it is (PCL / PE) by weight.
G) = 99/1 to 40/60 (total of 100% by weight of both), and further preferably 98/2 to 50/50.

The block copolymer is disclosed in JP-A-2002-
69279 or Shuai, X .; He, Y .; Na, Y.-H .;
According to the method described in Inoue, Y., J. Appl. Polym. Sci., 2001, 80, 2600., it can be synthesized as shown in the following scheme 1. That is, PEG or MPEG is previously filled with nitrogen.
Into a reaction vessel equipped with a stirrer containing ε, ε-caprolactone was injected together with a polymerization initiator, and the reaction temperature was set at 110 to
It can be obtained by reacting at 0 ° C. for 15 to 25 hours, and after the reaction, the product is dissolved in chloroform and then methanol is added to precipitate and purify. The resulting block copolymer is represented by formulas (1) and (2).
For example, a calculated amount of caprolactam and octyl stannate in pre-weighed and dried poly (ethylene glycol) of 20,000 molecular weight (PEG 20000) or monomethoxy-poly (ethylene glycol) of 750 molecular weight (MPEG750). By adding each, a block copolymer of poly (ethylene glycol) (PEG) and PCL can be synthesized.

[0014]

[Chemical 1] (N and m are integers of 1 or more)

The block copolymer (P
CL-b-PEG) is 1 to 100 parts by weight, and further, 100 parts by weight of (PLA) / (PCL) mixed resin.
It is preferable to add 5 to 20 parts by weight. If the amount added is less than 1 part by weight, the effect of the block copolymer as a compatibilizer will not be exhibited. Further, if it exceeds 100 parts by weight, the significance of being a compatibilizing agent is lost, which is not preferable.

(PLA), (PCL) and (PCL-b
For (-PEG), a mixed resin of (PLA) / (PCL) may be prepared in advance, and a predetermined amount of (PCL-b-PEG) may be added thereto, or each resin may be mixed simultaneously. .
The mixing can be performed by a known method. The mixing device is not particularly limited, but for example, a method of mixing using an extruder (melt kneading method) is industrially recommended in that it can be continuously processed in a short time. The temperature during mixing is preferably in the range of 180 to 210 ° C. The compatible resin composition can also be prepared by a method of simultaneously dissolving the three in a common solvent and then removing the solvent. Further, the compatible resin composition of the present invention, a modifier, a filler, a lubricant, an ultraviolet absorber, an antioxidant, a stabilizer, a pigment, within a range that does not impair the effects of the present invention,
In addition to various additives such as colorants, various fillers, antistatic agents, release agents, plasticizers, fragrances, antibacterial agents, etc., transesterification catalysts, various monomers, coupling agents, terminal treatment agents, other resins, wood Powder, starch, etc. can be added.

Since the compatible resin composition of the present invention has appropriate elongation at break, tensile strength and biodegradability, it can be molded by injection molding, extrusion molding, vacuum molding, blow molding, etc. It can be widely used in the fishery field, food field, clothing field, medical field, and packaging material field.

[0018]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited thereto. still,
The analysis and evaluation were performed as follows. ¹ H NMR measurement was performed with a JSX (Japan) GSX-270 spectrometer.
It was performed in a CDCl3 solution at 70 MHz and 25 ° C. The molecular weight is Tosoh HL equipped with Tosoh SC-8010 controller and refractive detector.
It was measured by C-8020 GPC system (Tosoh, Japan). Chloroform was used as the eluent and polystyrene samples with narrow molecular weight distribution were used as standards. The differential scanning calorimeter (DSC) analysis was performed by Seiko DSC200U system (Seiko Instruments (Japan)). First, the sample was heated from -100 ° C to 195 ° C at a heating rate of 20 ° C / min. After quenching, the sample was then heated again from -100 ° C to 195 ° C at a rate of 10 ° C / min. The center point of the heat capacity change of the DSC scan diagram obtained by the second heat run was defined as the glass transition temperature (Tg). The peak top value of the crystallization exotherm of the second heat run is cooled to the crystallization temperature (Tc
c), and the peak top of the melting endotherm of the fast heat run was taken as the melting point (Tm). Melting enthalpy (ΔH)
Was calculated from the integrated value of the endothermic peak of the fast run DSC curve. The mechanical properties are measured by EZ tester (Co., Ltd.)
Shimadzu (Japan) was used at a crosshead speed of 3 mm / min at room temperature. The reported values are average values of at least 3 test pieces each. Atomic force microscopy (A
FM) was observed by SPI3800 / SPA400 (Seiko Instruments Inc.). A pyramid-silicon device (Piazo device made of silicon) mounted on a 200 μm long microcantilever with a spring constant of 14 Nm ⁻¹ was used for the dynamic force (tapping) mode experiment. Height and deflection images were observed simultaneously.

The raw materials used were as follows. Poly (L-
Lactic acid) (PLLA) (Mw = 1.38 × 10 ⁵ , Mw /
Mn = 1.65), and poly (DL-lactic acid) (PDLL
A) (Mw = 1.06 × 105, Mw / Mn = 2.4)
5; Isotack dyad fraction [i] = 0.5
0) was obtained from Shimadzu Corporation (Japan). These samples were purified by precipitation from chloroform solution into ethanol and precipitation before use. Poly (ε-caprolactone) (PCL) is manufactured by Daicel Chemical Industries Ltd., Cell Green PH4 (Mw = 1.15 × 10 ⁵ , Mw / M).
n = 1.47) was used as is. Molecular weight 20000
(PEG 20000, Mn = 20000) poly (ethylene glycol) (obtained from Aldrich) and molecular weight 750
Methoxy-poly (ethylene glycol) (MPEG750, Mn = 750) (obtained from Aldrich) was made into a tetrahydrofuran (THF) solution before use, which was precipitated in hexane and dried under reduced pressure at 60 ° C. for 8 hours for purification. did. ε-caprolactone (obtained from Acros) is CaH2
Purified by vacuum distillation in the presence. Tin (II) caprylate
(Stannous (II) octoate) (Wako Pure Chemical Industries, Ltd.) was used as received.

(Poly (ε-caprolactone) -poly (ethylene glycol) block copolymer (PCL-b-P
Production of EG)) In a dry nitrogen stream, 15 g of ε-caprolactone (PEG
20000) or 195 g (in the case of MPEG750) and tin (II) caprylate 0.002 g (PEG
20000) or 0.032g (MPEG750
Was weighed in advance and poured into a flask containing dried poly (ethylene glycol) (5 g of PEG 20000 or 3 g of MPEG 750). The flask was purged with dry nitrogen and sealed. Then the reaction mixture is added to 11
It was heated to 5 ° C. and kept at this temperature in an oil bath for 24 hours. The polymerization product was purified by dissolving it in chloroform and precipitating it in methanol twice. The purified polymer was dried in vacuum at 40 ° C until a constant weight was obtained.
EG2000 series (PCL-b-PEG) 12.43
and 161.75 g of MPEG750 system (PCL-b-MPEG) were obtained. The purified copolymer is ¹ H NM
It was identified by R and the molecular weight was estimated by GPC measurement. As a result, Mw = 1.15 × 10 ⁵ and Mw / M
PEG 20000-based block copolymer with n = 1.86 and Mw = 6.38 × 10 ⁴ and Mw /
An MPEG750-based block copolymer with Mn = 1.45 was obtained. ^{The 1} H NMR spectrum showed good agreement with the structure derived from the block copolymer, and the GPC curves of all the purified copolymers showed a monomorphic distribution. Therefore, it was confirmed from ¹ HNMR and GPC measurements that this reaction was a copolymerization reaction, and that trace amounts of PEG and PCL did not remain in the purified product of the block copolymer.

Blend Preparation The following blend films were prepared for thermal analysis. Blend of PLLA and PCL-b-PEG Blend of PDLLA and PCL-b-PEG Blend of PLLA and PCL with and without PCL-b-PEG Blend of PDLLA and PCL with and without PCL-b-PEG Blend film is Teflon (registered) It was prepared by casting a 2 wt% chloroform solution in a Trademark) Petri dish and evaporating the solvent overnight at room temperature. After drying under vacuum for 2 weeks at room temperature to remove residual solvent,
Cast film is Lab Press (Mini Test Press-1
0, manufactured by Toyo Seiki Co., Ltd., under pressure of 5 MPa, 195 ° C., compression molded between Teflon sheets for 3 minutes, and then rapidly cooled to room temperature between two iron plates.

Preparation of PLA / PCL Blend Thin Films For atomic force microscopy (AFM), first the following PLA (PLLA and PDLLA) / PCL binary blend films were prepared from a chloroform solution by solvent casting. . The weight ratio of PLLA / PCL is 100 /
0, 90/10, 80/20, 70/30 and 50 /
50 and those of PDLLA / PCL are 100 /
0, 80/20, 70/30, 50/50 and 30 /
It was 70. 1 of polymer solution (1.0% (w / v))
Glass cover slip (substrate size 18)
X 18 mm) and sandwiched with another cover slip to spread the solution. The coverslips were then slid together and a thin layer of binary blend was formed on the substrate surface. The thickness of the thin film was about 100 nanometers. After the first AFM observation at room temperature, the thin film on the substrate was heated on the lab press hot plate at 195 ° C. for 1 minute, then removed and cooled to room temperature for 5, 15, 2
After 5 minutes, AFM observation was performed again.

PC based on PLLA and PEG 20000
The results of DSC measurement of the Lb-PEG blend are shown in Table 1.

[0024]

[Table 1] a Tcc and Tg are cooling-crystallization temperature and glass transition temperature, respectively. Only the Tcc value of the PLLA part is shown. Tm, ΔH, and Xc are melting point, melting enthalpy, and crystallinity, respectively. The melt enthalpy of the copolymer (normalized by the weight fraction of the components in the blend) is also shown in parentheses. b Cop1 is a PEG 20000 based PCL-b
-Shows a PEG block copolymer. cn. d. Indicates no detection.

As a typical example, FIGS. 1 and 2 show PLLA, PCL-b-PE recorded by a first heat scan and a second heat scan, respectively.
3 shows a DSC trace of G and blends of various component compositions thereof.

The melt enthalpy of PCL-b-PEG in the blend is the glass transition enthalpy (ΔH) of PLLA in the blend film regardless of the blend content.
It was calculated under the assumption that g = 4.9 J / g) was constant. The crystallinity (Xc) of PLLA in the blend was calculated by assuming a completely crystalline PLLA enthalpy of dissolution of 93 J / g. A significant change in Tg was observed in the PLLA rich phase in the blend. PL
The Tg of the LA rich phase drops from 61 ° C (PLLA 100%) to 38 ° C (50/50 mix). Moreover,
The other series of Tg's for PCL-b-PEG copolymers were constant and approached that of pure PCL (60 ° C) at relatively high copolymer contents. On the other hand, it has been reported that the PLLA / PCL blend system is immiscible and the PLLA is miscible with PEG, as reported by Yang et al. Considering the Tg measurement by DSC and the above report, the amorphous region of PLLA is PCL-b-PE.
It is concluded that it is miscible with that of the PEG domain of G and that discrete PCL domains containing crystalline and amorphous phases are present in the blend. Therefore, PCL-
It is clear that the penetration of PEG chains other than the PCL chain of b-PEG into the PLLA amorphous region caused a decrease in Tg of the PLLA phase. At this time, it is not clear whether a small portion of the short PCL chain near the junction of the PCL block and the PEG block has entered the PLLA amorphous region. However, it appears that homo-PCL is immiscible with PLLA (J. Appl. Polym. Sci., 2001, 80, 2
600), the PCL-segment phase of PCL-b-PEG is certainly still immiscible with PLLA.
The temperature of the melting peak of the PLLA component varies from 173 ° C (170 ° C) to 162 with increasing its content in the blend.
C (which is a decrease of about 10 C). This result showed that the crystallization of PLLA was greatly affected by the addition of PCL-b-PEG. This type of result indicates that the PCL-b-PEG copolymer can act as a diluent for PLLA and that the two components are compatible in the melt phase. This also means that the cooling-crystallization temperature (Tcc) of pure PLLA is 121 ° C.
It is also shown that the cooling-crystallization temperature of PLLA in these blends is lower than that of PLLA. Crystallization of PLLA was performed using PCL-b-PEG.
It seems easier to blend with. A slight increase in the corrected ΔH value and crystallinity (Xc) of PLLA in the blend may be related to the improved perfection of PLLA crystals. In fact, PLLA is PCL-b-PEG
When blended into the polymer, the reorganization of the polymer chains within the crystalline PLLA phase is higher than that of the pure homopolymer by Tm-
This is facilitated by the difference in Tcc. According to the report of Dell'Ebra et al., The presence of PCL enhances the crystallization rate of PLLA in PLLA / PCL blends, and this is probably caused by the increased nucleation rate. The boundary regions of the phase separated domains can provide nucleation sites that favor crystallization and, therefore, due to the immiscibility of the constituents, the crystallization rate of PLLA is
Promoted by a lower nucleation barrier. Another reason may be that the miscibility between PEG and PLLA results in the plasticizing action of PEG and the presence of PEG domains increased the crystallinity of PLLA. These results indicate that when the PEG chains of the copolymer are incorporated into the amorphous regions of the PLLA, isolated PCL domains free from the PLLA chains are still within the blend of PCL-b-PEG copolymer and PLLA. It certainly exists. For the thermal behavior of PCL-b-PEG, see PCL-
Although the Tm of b-PEG remains unchanged around 68 ° C,
With increasing PLLA content, the melt enthalpy attributed to the copolymer in the blend is significantly reduced. Similar to the discussion above, we believe that the crystallization of the PEG segment of PCL-b-PEG was significantly suppressed by the addition of PLLA, while the crystallization of the PCL segment of the copolymer was not affected at all. Is rational.

Table 2 shows the thermal properties of the blends of PLLA and MPEG750 based PCL-b-MPEG copolymer.

[0028]

[Table 2] a Tcc and Tg are cooling-crystallization temperature and glass transition temperature, respectively. Only the Tcc value of the PLLA part is shown. Tm, ΔH, and Xc are melting point, melting enthalpy, and crystallinity, respectively. The melt enthalpy of the copolymer (normalized from the weight fraction of the components in the blend) is also shown in brackets. b Cop2 is an MPEG750-based PCL-b-
1 shows an MPEG block copolymer. cn. d. Indicates no detection.

Comparing the thermal properties of blends containing MPEG750-based copolymers with those of blends containing PEG20000-based copolymers reveals the following interesting points. The melting point Tm of PLLA is PLLA / PCL-b
Less loss than those of PEG blends, PCL-
The melting point Tm of the crystalline phase in the PCL segment of the b-MPEG copolymer does not change significantly with the blend composition. Glass transition point T of PCL segment phase in blend
g can be considered to be almost the same as that of pure PCL. The decrease in the glass transition point Tg attributed to the PLLA-rich amorphous phase with increasing copolymer content indicates that the PEG chains of the copolymer penetrate deeply into the amorphous region of PLLA. However, MPEG7
The PEG segment of the 50-based copolymer is very deficient in these blends. In other words, MPE
The PEG content of the blend containing the G750 based copolymer is significantly lower than that of the blend containing the PEG 20000 based copolymer, even at the same composition of the PLLA / PCL-b-PEG blend. Therefore, MPEG
The decrease in the glass transition temperature Tg of the PLLA phase when blended with the 750 based copolymer is much less than when blended with the PEG 20000 based copolymer.
In addition, PLLA and PCL-b-M in the blend system
The apparent enthalpies of fusion of PEG do not have a characteristic trend and are almost the same. Well separated PLLA and PCL phases were present in these blends, and PCL-b
It is believed that the melt enthalpy of MPEG is largely contributed by the PCL segment phase rather than by the PEG segment phase, which may be influenced by PLLA during blending. A cooling crystallization exotherm at 121 ° C. was observed in pure PLLA, and this exotherm was 10 wt.
When blended with% PCL-b-MPEG, it shifts to 98 ° C. and further increasing the amount of copolymer in the copolymer composition has little effect on the location of this exotherm. This crystallization behavior shows that PLLA / PCL-b- shows a gradual shift of the cooling crystallization peak with the blend composition.
It differs from that of the PEG blend system. PLLA / PCL-
In b-PEG blends, crystallization behavior is associated with increased chain mobility within the amorphous phase of PLLA by adding miscible PEG of relatively long chain length. Crystallization of PLLA from its glassy state provides a favorable nucleation site because the chain length of the PEG segment is much shorter in the PLLA / PCL-b-PEG blend than in the PLLA / PCL-b-PEG blend. It will be clear that the addition of the PCL segment, rather than the addition of

Table 3 shows the results of the examination of the miscibility of PDLLA and PCL-b-PEG.

[0031]

[Table 3] a Tcc and Tg are cooling-crystallization temperature and glass transition temperature, respectively. Only the Tcc value of the PDLLA part is shown. Tm and ΔH are melting point and melting enthalpy, respectively. The melt enthalpy of the copolymer (normalized from the weight fraction of the components in the blend) is also shown in brackets. b Cop1 is a PEG 20000 based PCL-b
-Shows a PEG block copolymer. cn. d. Indicates no detection.

As shown in Table 3, PDLLA has 54
It is a completely amorphous polymer having a glass transition temperature Tg at ° C. PEG 20000 based PCL-b-PEG
When blended with, the glass transition point Tg of the PDLLA phase
Became quite low. The changes in the glass transition point Tg and the melting point Tm related to the blend composition are
-Similar to those found in blends of b-PEG. Therefore, an isolated P consisting of an amorphous phase and a crystalline phase
It is concluded that the CL segment domain is present in these blends, while the PEG segment phase of the copolymer is mixed with PDLLA in the amorphous region. In general,
The tensile properties of immiscible and partially miscible blends depend on two interrelated factors: adhesion between the two phases and domain size of the dispersed components, both of which depend on interfacial tension. Mainly controlled. In general, compatibilized polymer blends have a finer phase domain size, greater interfacial contact area and higher interfacial adhesion than that of the corresponding non-compatibilized blend. Effective compatibilizers are rather along the interface.

PCL / PLA (PLLA and PDLLA) with and without addition of block copolymer
The stress, tension and elastic modulus of the blend film are shown in Tables 4-6.
It was shown to.

[0034]

[Table 4]

[0035]

[Table 5]

[0036]

[Table 6]

PLLA / PCL 80/2 shown in Table 4
In the case of 0 blend, the tension and elastic modulus at break are PCL
The content was increased stepwise at a content of 10% by weight of the -b-PEG copolymer. However, the maximum stress was slightly reduced.

As can be seen in FIG. 3, 10% PCL-
PLLA / PCL 8 containing b-PEG (weight content)
The 0/20 blend film has about 400 when compared to the blend film containing no block copolymer.
It showed an increase in elastic modulus of MPa and an increase in elongation of about 20%. However, PL containing 15% PCL-b-PEG
For the LA / PCL 80/20 film, all mechanical properties are reduced, indicating that there is an optimum copolymer concentration that maximizes the compatibilizing effect.

As shown in Table 6, the improvement of the tensile property is P
Also shown in the DLLA / PCL 80/20 blend. That is, in the PDLLA / PCL 80/20 blend containing the PCL-b-PEG copolymer, the tendency of the tensile properties was PL including the PCL-b-PEG copolymer.
Similar to that of the LA / PCL 80/20 blend. In contrast, MPEG750-based PCL-b-M
PLLA / PCL blends containing PEG copolymers show no significant increase in both tensile strength and modulus at break (Table 5). These results show that PLLA / PCL-b-PEG, PLL revealed by DSC measurements.
A / PCL-b-MPEG and PDLLA / PCL-
It is consistent with the phase structure of b-PEG blends. PCL-
Since the PEG segment phase of b-PEG is miscible with PLA, but the PCL segment phase of the copolymer is immiscible with PLA, the block copolymer added to the blend will be in the boundary region between PCL and PLA. It should be connected mainly. Therefore, the interfacial adhesion between PCL and PLA was enhanced. In the case of using an MPEG750-based block copolymer as a compatibilizer, P
The EG segment may be too short to connect between the PLLA and PCL interfaces. Therefore, PLLA
/ PCL blend film mechanical properties PCL-b-M
Addition of PEG did not significantly improve. Here, the results in Tables 4-6 show that PLLA / PCL 80/20 blends with and without block copolymer and P
PLLA / P with and without block copolymer compared to those of DLLA / PCL 80/20
CL50 / 50 blend and PDLLA / PCL 3
It is worth noting that most of the 0/70 blends show reduced tensile properties. Moreover, for these blends there is no change in the tensile properties despite the addition of the block copolymer as a compatibilizer, rather they show a decrease in the tensile properties. That is, an increase in the soft PCL component is expected to make the film more flexible by adding the block copolymer, but P
LLA / PCL 50/50 and PDLLA / PCL
The 30/70 blend film did not show any improvement in mechanical properties.

In order to study the effect of the weight composition of the PLA / PCL binary blend on the compatibilization of the PLA / PCL / PCL-b-PEG blend, PLA / PCL
AFM observation was performed on the thin film of the binary blend of The morphology of these two-component blend films should have changed much more or less depending on the thermal history, without the flow effects as in a mixing extruder. Since the film was prepared from a chloroform solution that is miscible with both PLLA and PCL, they may be mixed at just above the general resolution of scanning electron microscopy. Despite the slight influence of the two-dimensional structure of the substrate and thin film, it seems that AFM observations would be preferable within our experimental range. Figure 4 shows PLs with various compositions (100/0 to 50/50) cast on glass substrates at room temperature.
Figure 3 shows typical AFM deflection images of LA / PCL thin films. 4A appears to be one homogeneous phase and 4B is the surface (spots are PC
L small crystals, which may be unfiltered or dust adsorbed from air during sample preparation).

Two different images were observed at the same blend ratio (PLLA / PCL = 80/20), as shown in FIGS. 4Ci (center left view) and 4Cii. In FIG. 4Ci, the PCL phase is dispersed in a spherical shape and P
As a spherical inclusion of the LLA matrix, it sank with a depth of about 5 nanometers and a width of about 100 nanometers. In Figure 4Cii, the shape of the surface is similar to those in Figures 4A and 4B. It may consist of a PLLA blend with low PCL content, in which the PCL domains are fused. Figure 4D
And 4E show the variation of the dispersed domain shape from spherical to elliptical and elongated. The sunken depths of the domains of Figures 4D and 4E were also increased by 20-40 nanometers and 80-110 nanometers, respectively, compared to that of the 4Ci figures. FIG. 4 shows that PLLA / PCL blends with a PCL content of less than 20% are well dispersed and compatible at AFM observation levels, but those with a PCL content of 20% and above suddenly agglomerate. The transformation of domain-sized and spherical to elliptical shape occurs around a PCL content of 20% in these binary blends, and the proportion at which the dispersed phase begins to become apparently coarse is
This indicates that the position is probably 20% of PCL. This conversion is also associated with interfacial area changes between blend components. So, as shown above,
The improvement in elongation properties of certain blends with optimal composition is
It is a result of the synergistic effect of increasing the (soft) component and decreasing the interfacial area of the PLA / PCL blend. Thus, proper compositional optimization of certain immiscible blends is necessary for effective compatibilization.

FIG. 5 shows various compositions (100/0 to 50).
/ 50 wt / wt), and after heat treatment at 195 ° C., an AFM deflection image of the PLLA / PCL thin film observed at room temperature is shown. These show a rougher and sharper interface between the PLLA-rich phase and the PCL-rich phase than in FIG. The film shown in FIG. 5B shows a rugged surface in various places despite the absence of domain fusion. Compared to the AFM images shown in Figures 4Ci and 4D (sunk inclusions), the PCL-rich phase is dispersed as spherical, surface-embedded inclusions in Figures 5Ci and 5D. Especially in FIG. 5D, the total area of the PCL rich phase is
It appears to be reduced compared to that of FIG. 4D. Furthermore, FIG. 5E shows the presence of PCL bulbar condyles.

Meredith and Amis are PDLLA / PC
For L2-component blends, there is a lower critical solution temperature (LCST) phase boundary with a critical temperature of 86 ° C. and a critical concentration of mass fraction of 36 wt% PCL, and its morphological control LCST of programmed temperature. It was reported that this was possible by jumping up and quenching the PCL below the Tm (J. Macromol. Chem. Phys., 200
0, 201, 733). So PDLLA / PCL and PL
Due to the chemical similarity between LA / PCL blends, PL
It is believed that the morphology and distribution of the LA / PCL blend was affected by temperature changes. As shown in FIG. 5, these phase behaviors are similar to those of PLLA / PCL by heat treatment.
Reasonably describes phase separation and crystallization of blends.

FIG. 6 shows various compositions (100/0, 80/20, 70/3) cast on glass substrates at room temperature.
0, 50/50 and 30/70)
2 shows an AFM deflection image of a / PCL thin film.

Overall, the tendency of image change with blend composition is similar to that observed in FIG. FIG. 6Bm is an enlarged view of FIG. 6B at the same ratio as FIG. The phase pattern of PDLLA / PCL 80/20 is PLLA / PCL 90/10 (Figs. 4B and 6B).
And 6Bm), and
It is worth noting that no spherically dispersed phase pattern was observed in the PDLLA / PCL blends. But,
PCL rich phase PDLLA / PCL 70/30
And 50/50 size and shape are PLLA / P
As for CL 70/30 and 50/50. In addition, PDLLA / PCL blends
It is less sharp than the PLLA / PCL blend, but exhibits a rough morphology with smooth interfaces. It is because PLLA and PDLLA have different stereoregularities, so any difference in the (non) compatibility dependence on the blend composition is due to PLLA / PCL and PDL.
It is shown to be present during the LA / PCL blend. It also means that the synergistic effect of the blend components on compatibilization can be maximized by choosing the appropriate blend ratio in the PLA / PCL blend system. Figure 6
As shown in E, the phase pattern of PDLLA / PCL 30/70 is similar to that of PDLLA / PCL 70/30 of FIG. 6C.
It looks like a bumpy upside-down phase.

The PDLLA / PCL thin film on the substrate is 19
After placing on a hot plate at 5 ° C. for 1 minute, AFM observation was performed at room temperature. The results are shown in Fig. 7.

FIGS. 7B and 7Bm show the spherically dispersed phase (different from that of the sample with the same PDLLA / PCL composition ratio shown in FIG. 6B). As noted above, it is uncertain whether this morphological change results from miscibility changes or crystallization of the PDLLA / PCL blend constituents, but the presence of spherically dispersed PCL-rich phases results from changes in phase structure. It seems to have been 7C,
7D and 7E represent spheroids of PCL in matrix phase, and the inset image of FIG. 7C shows fine crystal growth of PCL. It is interesting that artificial heat treatment leads to different sizes and distribution of PCL bulbar condyles. Meredith and Amis
As suggested by (above), P
Control of DLLA and PCL domain size may be achieved by coupling phase separation with a crystallization step. The increase in soft constituents leads to higher flexibility of the blend. In the case of immiscible polymer blends, increasing component proportions also generally lead to domain size, followed by re-agglomeration or coalescence in the dispersed particles. Therefore, optimization between mechanical properties and morphology must be adapted to the final properties of the product.

PLLA containing a copolymer of PCL and PEG
Analysis of the thermal properties of PDLLA and PDLLA shows that the PEG phase of the block copolymer is miscible with PLA
The phases generally showed to be immiscible with PLA.
When the PEG chains of the copolymer are incorporated into the amorphous regions of PLA, it is reasonable to separate the PCL domains without PLA chains in the blend, which is PCL-b-P.
It shows that there is a compatibilizing effect of EG.

[0049]

According to the present invention, immiscible PCL and PL
In A blend, PEG 20000 series and MPEG
Provided is a compatible resin composition in which mechanical strength and flexibility are improved by adding a 750-series block copolymer as a compatibilizing agent, as compared with a case where only a block copolymer is not added. be able to.

[Brief description of drawings]

FIG. 1 is a DSC thermogram measured by fast heat scan of a blend of PCL-b-PEG copolymer prepared from PLLA and PEG20000.

FIG. 2 is a DSC thermogram measured by a second heat scan of a blend of PCL-b-PEG copolymer prepared from PLLA and PEG20000.

FIG. 3 PLA / PCL for different compatibilizer contents
Figure 7 shows the elongation at break of the blend film.

FIG. 4: (A) 100/0, cast at room temperature
(B) 90/10, (Ci) 80/20, (Cii) 80
/ 20 (does not show distributed domain), (D) 70/3
AF of PLLA / PCL blend thin films of 0 and (E) various PLLA / PCL blend weight compositions of 50/50
The M deflection image is shown.

FIG. 5: (A) 100/0, heat treated at 195 ° C.
(B) 90/10, (Ci) 80/20, (Cii) 80
/ 20 (does not show distributed domain), (D) 70/3
AF of PLLA / PCL blend thin films of 0 and (E) various PLLA / PCL blend weight compositions of 50/50
The M deflection image is shown.

FIG. 6: (A) 100/0, cast at room temperature
(B) 80/20, (C) 70/30, (D) 50/5
AF of PDLLA / PCL blend thin films of various PDLLA / PCL blend weight compositions of 0, (E) 30/70
The M deflection image and the enlarged view of (Bm) 80/20 are shown.

FIG. 7: (A) 100/0, heat treated at 195 ° C.
(B) 80/20, (C) 70/30 (Insert image: PC
L crystal growth image), (D) 50/50, (E) 3
Figure 3 shows AFM deflection images of PDLLA / PCL blend thin films of various PDLLA / PCL blend weight compositions of 0/70, and an enlarged view of (Bm) 80/20.

Claims (5)

[Claims] 1. Poly (lactic acid) (PLA), poly (ε-caprolactone) (PCL) and poly (ε) as a compatibilizer.
-Caprolactone) -A compatible resin composition comprising a poly (ethylene glycol) block copolymer. 2. PLA is poly (L-lactic acid) (PLLA).
The compatible resin composition according to claim 1, which is 3. The phase according to claim 1, wherein the mixing ratio of PLA and PCL is ((PLA) / (PCL)) = 1/99 to 99/1 by weight (the total of both is 100% by weight). Soluble resin composition. 4. The poly (ε-caprolactone) -poly (ethylene glycol) block copolymer in an amount of 1 to 100 parts by weight based on 100 parts by weight of a mixed resin of PLA and PCL. Compatible resin composition. 5. The (ε-caprolactone) monomer unit and the (ethylene glycol) monomer unit constituting the block copolymer are by weight (ε-caprolactone) unit / (ethylene glycol) unit = 99/1 to The compatible resin composition according to claim 1, wherein the compatible resin composition is 40/60 (the total of both is 100% by weight).