KR100951537B1 - High viscosity modified plant-derived biodegradable resin for high magnification foam and its manufacturing method - Google Patents

Abstract

The present invention relates to a modified plant-derived biodegradable resin having a high melt viscosity suitable for high magnification foaming, and a method for preparing the same, and a monomer having a functional group such as a double bond and an epoxy in a commercialized polylactic acid resin, which is a plant-derived biodegradable resin. After the addition, the electron beam was irradiated to 0.1kGy-300kGy to provide a high melt viscosity resin with a melt viscosity of up to 200 times and a storage modulus of about 10000 times. In particular, the present invention, unlike the method of increasing the melt viscosity and storage modulus under the premise of crosslinking (gel), which is a conventional method, the crosslinking is to be minimum (less than 5% gelling, preferably less than 3%) It is a method of increasing the molecular weight while maintaining the branching and linearity of the polymer chain. Unlike the resin modified by the conventional crosslinking method, the invention is very easy to process into a continuous foam sheet. Completely decomposed into water and carbon dioxide by the production, the produced carbon dioxide is a modified plant-derived biodegradable resin suitable for the carbon dioxide circulation cycle without the accumulation of carbon dioxide produced as a reusable raw material by plant photosynthesis.

Polylactic acid (PLA), GMA, melt compound viscosity, storage modulus, carbon dioxide, electron beam

Description

High viscosity modified biobased and biodegradable polymer for the application of low density extrusion foaming and method of preparation Technical

The present invention relates to a modified plant-derived biodegradable resin having a high melt viscosity suitable for high magnification foaming, and to a method for producing the same, more particularly, which is decomposed into carbon dioxide by microorganisms after disposal and the carbon dioxide is used again by photosynthesis. The present invention relates to a high viscosity modified plant-derived biodegradable resin derived from a high magnification foam capable of producing a foam having various magnifications including a high magnification foam while reducing carbon dioxide in the atmosphere using circulation and reducing the global environmental load.

Conventionally, non-degradable polyolefin resin foams and polyurethane resin foams, which have been used as raw materials for blow molding and foams, have been widely used industrially because they have excellent moldability, are easy to manufacture, lightweight, and have excellent thermal insulation and buffering properties. .

However, such resin foams put a great burden on the global environment due to their non-degradation upon disposal. In addition, since these resins are produced as petrochemical raw materials, their use is limited by the CO2 reduction Tokyo Convention.

Thus, in recent years, research and development on the foam corresponding to the non-degradable and carbon dioxide emission regulations are active.

For example, biodegradable resins decomposed by microorganisms in a natural environment such as aliphatic polyester homopolymers or crosslinked foams using peroxides or aliphatic polyester-aromatic polyester copolymers are researched and developed to form molded articles and films. And commercialized as fibers and developed for extruded foams of some biodegradable resins, but these biodegradable resins are subject to carbon dioxide emission restrictions because they produce their raw materials from petrochemical raw materials.

Therefore, it is necessary to develop a resin that is easy to expand in high magnification without being subject to biodegradability and carbon dioxide emission regulation. Recently, mass production of lactone resin polymerized with polymers by producing monomers from plants such as corn has been performed. The resin could not be molded into a blow molded article or foam due to the low melt viscosity of the polyester.

As a method for manufacturing a resin for foaming to compensate for this disadvantage, Japanese Patent Laid-Open No. 11-279311 proposes a foam using a lactone resin, but the degree of disintegration at the time of crosslinking only by irradiation treatment in a normal state Since it progresses simultaneously, it is difficult to obtain the melt viscosity for fully maintaining a bubble at the time of foaming, and it is difficult to obtain foam with a favorable surface form. That is, irradiation in the vicinity of room temperature requires a large radiation dose of 200 kGy, and in order to solve this problem, it is described that it is preferable to melt the lactone resin above the melting point and then perform crystallization without reaching crystallization. Easily a foam having a high degree of crosslinking (gel fraction) could not be obtained. In addition, since the degree of gelation is high, it is difficult to apply modified resin to continuous foaming, and when the degree of crosslinking is high, stabilization of the foaming cell is extremely difficult.

In addition, Korean Patent Laid-Open Publication No. 10-2004-0066148 proposes a method of crosslinking a resin using an electron beam after producing a biodegradable resin containing a polyfunctional monomer having at least two unsaturated bonds in a molecule into a sheet. . However, this method is impossible to recycle after use with a sheet having a gelation degree of at least 5% that compares the crosslinking rate under the influence of multifunctional groups, and cannot use a conventional continuous foaming machine. In addition, if the thickness of the irradiated object exceeds 1mm, the radiation does not reach the inside, so that the bubbles inside are uneven at the time of foaming. Due to the decrease in molecular weight by the viscosity is significantly reduced bubbles very unstable, there was a problem that it is difficult to produce a reliable uniform foam sheet.

In another technique, a method of preparing a resin having high viscosity by cross-linking and reforming with a peroxide initiator has been proposed, but since the gelation degree is not easy to process after modification, it is actually foamed with a resin having a lower viscosity. If the foaming temperature is to be significantly lowered in order to obtain high viscosity, there is a problem that continuous expansion of high magnification is almost impossible at low processing temperature (D. Carlson, P. Dubois, and R. Narayan, Polym . Eng ., & Sci . , 38 (2), 311-321 (1998).)

In addition, the method of using a chain extender as a method of increasing the molecular weight while maintaining the linearity of the molecular chain was introduced, but the reaction time is long, or the toxicity of the chain extender is limited to the application as a final product. (SS Ray and M. Okamoto, Macromol. Rapid. Commun., 24, 815, (2003))

In addition, recently, a method of increasing the viscosity by preparing a nanocomposite has been announced, but in this case, a large amount of nano-inorganic material, which is a foreign material, is so destroyed that the foaming cell is destroyed early, which is not suitable for high foaming. (Y. Di, S. Iannace, ED Maio, and L. Nicolais, J. Polym. Sci .: Part B, 43 , 689 (2005))

On the other hand, those that are known to be biodegradable and not subject to carbon dioxide emission control are those produced by ring-opening polymerization of glycolide or lactide.

Among these, polylactic acid (PLA), which can be mass-produced, has been widely applied to films, sheets, injection molded articles, fibers, and the like. As a study on modifying polylactic acid, a method of using a chain extender has been introduced. Long reaction times and the toxicity of chain extenders have severely limited their application to the final product (SS Ray and M. Okamoto, Macromol . Rapid . Commun ., 24 , 815, (2003)).

In order to solve the problems as described above, the present invention is to minimize crosslinking (less than 5% gelation, preferably less than 3%) and to modify the polymer chain by branching the functional chain by adding functional monomers while maintaining linearity. Unlike the resin modified by the conventional crosslinking method, it is very easy to process into extrusion or injection continuous foam sheet, and it is possible to provide resin with excellent productivity as well as biodegradability of plant origin. The purpose is to provide a high-viscosity modified high viscosity modified plant-derived biodegradable resin suitable for the carbon dioxide circulation cycle without the accumulation of carbon dioxide, which is completely decomposed into water and carbon dioxide and produced as a reusable raw material by plant photosynthesis. There is this.

In the present invention, a monomer having a functional group such as double bond and epoxy is added to a commercialized polylactic acid resin, which is a plant-derived biodegradable resin, and then irradiated with an electron beam up to 1kGy-300kGy, the melt viscosity is up to 200 times, and the storage modulus is about 10000. It is characterized by a high viscosity modified plant-derived biodegradable resin for high magnification foaming and a method for producing the same.

The present invention provides a resin having a high melt viscosity and storage modulus having a gelation degree of less than 5% by adding a monomer having a double bond and an epoxy functional group to a resin of a commercialized polylactic acid which is a plant-derived biodegradable resin, and a method for producing the same. As a result, since the chains of molecules are linear or branched rather than crosslinked, extrusion or injection foaming at any magnification in which thermoplasticity is required is possible. That is, the resin according to the present invention has a gelation degree of less than 5%, maintaining the thermoplastic properties as it is, there is an effect that can be used to obtain a continuous foam sheet of various magnification by using the olefin resin extrusion foaming machine currently used as it is.

Hereinafter, an embodiment of the present invention will be described.

The high-viscosity modified high viscosity modified plant-derived biodegradable resin according to the present invention is based on polylactic acid, and is a double bond, one epoxy group or a maleic anhydride group capable of rapid radical polymerization as a functional monomer. Or glycidyl methacrylate (GMA) which has an isocyanate group was added.

In addition, the resin production method of the present invention by irradiating the electron beam to the high-viscosity modified plant-derived biodegradable resin composition for high magnification foaming to prepare a branched chain or a polymer linear chain of polylactic acid to maintain plasticity while maintaining plasticity To prepare a modified polylactic acid having a.

In the functional monomer composition described above, when the monomer has three or more functional groups, crosslinking proceeds, and thus processing is difficult after modification as in the conventional method, and thus the functional monomer having two functional groups is used in the present invention.

Other examples of such monomers include 1,2-EPOXY-9-DECENE, 1,2-EPOXY-5-HEXENE, 4-VINYL-1-CYCLOHEXENE-1,2-EPOXIDE, LIMONENE-1,2-EPOXIDE, ALLYL There is GLYCIDYL ETHER.

On the other hand, in the above configuration, the monomer is added 0.1-10 parts by weight based on 100 parts by weight of polylactic acid.

reagent

Poly Lactic Acid (Nature Work ^® PLA Polymer) was purchased from Cargill Dow LLC and dried at 50 ° C. for 24 hours, and glycidyl methacrylate (GMA) was purchased from Aldrich and used without purification. In Comparative Example, 2,5-bis ((tert-butyl peroxy) -2,5-dimethyl hexane (Luperox) as a reaction initiator was purchased from Aldrich and used without purification.

end. Preparation of Experimental Sample by Irradiation of Monomer and Electron Beam

Modified polylactic acid of Comparative Examples and Examples was prepared with the composition ratio and the electron beam irradiation amount as in Table 1 and Table 2, Table 1 shows a comparative example and Table 2 shows an example, and the weight parts in Tables 1 and 2 are polylactic acid (PLA) The amount of GMA and initiator (g) per 100 g.

First, polylactic acid and GMA were mixed in a plastic bag using the compositions of Tables 1 and 2, and mixed in advance, and then melt mixed using a twin screw extruder (SM PLATEK Co. Ltd., TEK 30, Korea). The twin screw extruder is a co-rotating type with a screw diameter of 30 mm and a length / diameter (L / D) ratio of 36. The screw rotation speed was 150 times per minute, the barrel temperature was maintained at 130-190 ° C, the die temperature at 185 ° C, and the extrusion speed was adjusted to 12 kg / hr. The prepared sample was cut into chips and dried at 50 ° C. for 24 hours.

The electron beam irradiation was conducted to the sample at the irradiation amount shown in Tables 1 and 2 at room temperature / atmospheric pressure in a nitrogen atmosphere using an electron beam accelerator (ELV-0.5, BINP, Russia). Samples irradiated with electron beams were kept in an oven at 50 ° C. for at least 12 hours to remove residual radicals and to be dried.

I. analysis

The gel fraction, which is a qualitative measure of the degree of crosslinking and branching of molecules, was measured as follows.

First, the gel is separated from the modified polycaprolactone by operating in a chloroform solvent for 24 hours using a soxhlet apparatus. The separated gel was dried and weighed. Gelation refers to the weight percentage of gel relative to the initial sample.

The thermal properties were measured by glass differential temperature (T _g ) and melting temperature (T _m ) using a differential calorimetry (DSC; Perkin-Elmer Pyris 6). In order to make the thermal history the same, the sample was first heated to 200 ° C at a heating rate of 20 ° C / min, stopped for 5 minutes, and then quenched to 0 ° C. Thereafter, the temperature was raised to 200 ° C. at a temperature increase rate of 10 ° C./min, and thermal properties were examined.

The crystallization temperature was the peak value of the exothermic curve that appears when the second temperature is cooled again to 10 ℃ / min.

The change in composite viscosity, storage modulus (G ') and loss modulus (G ") of samples with frequency was measured using Advanced rheometric expansion system (ARES; Rheometric Scientific Co. Ltd.). A disc with a diameter of 25 mm and a thickness of 2 mm was prepared by compression molding method, and the melting point elasticity was investigated while the measurement temperature was fixed at 190 ° C. and the strain was fixed at 5%, a linear section, and the frequency was changed from 0.1 to 100 rad / s.

All. result

(One) Comparative Example  result

The gelation degree and thermal characteristic change of the modified polylactic acid of the comparative example is shown in Table 1 according to the content of the initiator, and their rheological properties according to the frequency is shown in Figs.

The gelation degree between pure PLA and Comparative Examples 1-7 is between 0.2-1.5%, indicating that pure polylactic acid hardly crosslinks by electron beam irradiation. However, in Comparative Example 8-10 modified with only the initiator, when the content of the initiator is low, the possibility of crosslinking is low, but the gelation degree is increased to 3.1% at 0.5 parts by weight of the initiator. Say progress. And in Comparative Example 11-16 in which only GMA is added without electron beam irradiation, it can be seen that the crosslinking reaction does not occur with gelation degree of 0.5-1.1%.

The glass transition temperature and the melting temperature of the crystals did not show a significant change until Comparative Examples 1-14, but in Comparative Examples 15 and 16, the two transition temperatures decreased and the crystallinity increased, from which GMA was miscible with polylactic acid. It can be seen that it acted as a plasticizer.

Referring to FIG. 1, when only pure polylactic acid is irradiated with electron beams up to Comparative Examples 1-6, the composite viscosity is significantly reduced and the storage modulus is continuously decreased as shown in FIG. 2. 3, the crosslinking reaction or the branching reaction hardly occurred, and the chain of the polylactic acid was continuously cut by electron beam irradiation, so that the molecular weight decreased. This is very different from the properties seen in the existing polyolefin modification results (polypropylene or polyethylene). Therefore, it can be seen that the modification of the polylactic acid by the electron beam requires other additives in addition to the electron beam.

4-6, which shows the characteristics of Comparative Example 8-10, which is a method using the conventionally used initiator, it can be seen that the compound viscosity has a synergistic effect to some extent. In other words, when the content of the initiator is 0.1 and 0.3 parts by weight, the compound viscosity and storage modulus are 2.5 and 1.8 times higher than those of the unmodified pure polylactic acid, respectively, but when 0.5 parts by weight of the initiator is added, the composite viscosity is slightly decreased. The storage modulus is inverted with the value of pure polylactic acid near the frequency of 10 rad / s.

These composite viscosities and storage modulus are directly related to the melt strength, which shows melt processability, so it is expected that the polylactic acid melt strength can be improved by simple chemical modification, but it is greatly used for high magnification continuous foaming or application to blow molding products. It's not enough.

The storage modulus of FIG. 5 shows a similar result. Referring to FIG. 6, branching and crosslinking of the chain occur with addition of an initiator, but at the same time, a chain cleavage reaction occurs.

When only GMA is added without electron beam irradiation, as shown in FIGS. 7 and 8, the composite viscosity and storage modulus decrease according to the amount of GMA, indicating that GMA plays a role as a plasticizer.

In addition, the storage modulus vs. loss modulus log-log curve of FIG. 9 shows that the addition of functional monomers without electron beam irradiation causes little cross-linking.

(2) Example  With 1-46 functional monomers Of polylactic acid  Electron beam reforming result

The gelation and thermal properties results of Examples 1-40 are shown in Table 2 and the melt point elastic results of all the examples in FIGS. 10-30.

First, thermal properties of polylactic acid modified at various dosages to polylactic acid added with 0.1 parts by weight of GMA of Example 1-6 are shown in Table 2, and the melt-complex viscosity, storage modulus and storage modulus versus loss modulus log-log curve The results are shown in FIGS. 10-12.

The glass transition and melting temperatures of the modified polylactic acids have almost the same values as those of pure polylactic acid (Comparative Example 1-6), but the crystallinity is slightly higher than that of pure polylactic acid modified without GMA addition. You can see that. These results do not have a significant effect on the glass transition temperature when the amount of GMA is small, but it seems to have an effect on the crystallization rate as a plasticizer.

From the melting point elastic properties, it was found that the composite viscosity and storage modulus of the modified polylactic acid decreased with increasing electron beam irradiation. Other gelling degrees, storage modulus of FIG. 11 and storage modulus versus loss modulus log-log curves of FIG. 12 also showed similar trends with modified polylactic acid without GMA. That is, it can be seen that addition of a small amount of GMA does not significantly affect the object of the present invention except for the effect on the crystallization rate as a plasticizer.

Accordingly, the experimental results of polylactic acid (Example 7-12) modified by electron beam irradiation after increasing the amount of GMA to 0.3 parts by weight are shown in Table 2 and FIGS. 13 to 15.

The glass transition temperature and melting temperature of the modified polylactic acid did not change much, and the degree of gelation was 0.2-1.6%, which was similar to that of 0.1 parts by weight of GMA, and the same tendency to decrease or increase with irradiation dose. That is, there was no change with the increase of GMA amount.

However, when the melting point elastic properties shown in Figs. 13 to 15 are examined, a slight change begins. In particular, the storage modulus vs. loss modulus log-log curve of FIG. 14 and the storage modulus vs. loss modulus log-log curve of FIG. That is, the storage modulus of the modified polylactic acid with 0.1 parts by weight of GMA tended to decrease sequentially with increasing dose, but the 0.3 parts by weight of modified polylactic acid with GMA showed a slight change in the low frequency range. In particular, the storage modulus value of the polylactic acid modified at a dose of 10 kGy was higher than that of the pure polylactic acid. This suggests that the change in molecular chain reaction may be due to an increase in the amount of GMA. That is, it means that there existed a change of the chain structure and the molecular weight distribution by reaction.

  Example 13-18 is a polylactic acid modified by increasing the amount of GMA to 0.5 parts by weight, their thermal properties and gelation degree are shown in Table 2, the melting point elastic properties are shown in Figure 16-18.

The gelation degree, glass transition temperature and melting temperature of the modified polylactic acid were not significantly different from the modified polylactic acid with low GMA content under the same irradiation conditions. However, from the melting point elasticity characteristics of FIGS. 16 to 18, it can be seen that there is an electron beam irradiation amount in which the melt compound viscosity and the storage modulus which are objects of the present invention are increased.

In the composite viscosity curve of FIG. 16, the composite viscosity of the modified polylactic acid with 0 kGy (comparative example) and 1 kGy dose (Example 13) was lower than that of pure polylactic acid. This is because GMA acts as a plasticizer and the dose of 1 kGy is low enough to cause a sufficient radical reaction.

In addition, the complex viscosity of polylactic acid modified with 5, 10, 20 (Example 14, 15, 16) kGy dosage changed from Newton's flow behavior to strong shear stress dependent flow, and was pure polylactic in the low frequency region. The complex viscosity of acid had a value larger than that of acid.

Polymers containing polylactic acid had a much higher melt viscosity than those of linear polymers or crosslinked polymers. The polylactic acid modified at a dose of 5, 10, or 20 kGy exhibited a shear-dependent flow behavior. The composite viscosity of was higher than that of pure polylactic acid at low frequency.

The composite viscosity of the modified polylactic acid (Example 14) at a dose of 5 kGy was about 3 times higher than the pure polylactic acid 2430 Pa-s at 7440 Pa-s at a frequency of 0.1 rad / s.

The storage modulus of FIG. 17 shows a larger change than the composite viscosity in the low frequency region.

The storage modulus of polylactic acid modified with a dose of 5 kGy is increased by about 10 times. This means that the polylactic acid chain structure was changed when the GMA was added to irradiate the electron beam in the appropriate dosage range. The amount of crosslinking observed in previous studies is very small in view of the degree of gelation of modified polylactic acid. Therefore, it can be seen that the branching reaction predominates rather than the crosslinking reaction when the electron beam is irradiated with GMA.

The modified polylactic acid at high doses (50, 100 kGy) showed similar properties to Newtonian fluids with less complex viscosity and shear dependence.

Referring to FIG. 18, the slope of the modified polylactic acid with irradiation doses of 5, 10, and 20 kGy was less than that of the modified polylactic acid having a low GMA content in the range of 1.25 to 1.27. These results also indicate that the polylactic acid chain structure has changed.

In the case of modified polylactic acid irradiated at various doses by adding GMA 1 parts by weight of Examples 19-24, the glass transition temperatures of the modified polylactic acids were similar to pure polylactic acid, but as shown in Table 2, The degree of crystallinity decreased from the 10 kGy dose to the minimum value due to the branching reaction and the crystallinity of the modified polylactic acid irradiated by more than 10 kGy dose increased with the decrease of the molecular weight. In this case, the effect of the crosslinking reaction could not be excluded, but the gelation values were very small, indicating that the ratio of crosslinked molecules was very low. Therefore, it can be seen that this change is not due to the crosslinking of the chain but due to branching or chain shear reaction.

These viscoelastic characteristics are shown in FIGS. 19-21.

As shown in FIG. 19, the composite viscosity of the polylactic acid irradiated with 0 and 1 kGy doses (Comparative Example 14, Example 19) is lower than that of pure polylactic acid. This is because GMA acts as a plasticizer, but the flow behavior begins to change from Newtonian flow to non-Newtonian flow.

Composite viscosity was also greatly influenced by the dosage.

The composite viscosity showed an increase in the maximum value of polylactic acid (Example 21) irradiated at 10 kGy. However, 50 kGy (Example 23) and 100 kGy (Example 24) irradiated modified polylactic acid showed lower composite viscosity and storage modulus than unirradiated polylactic acid containing pure polylactic acid and GMA due to decomposition reaction. But still shows shear curves that are shear dependent. These results indicate a competitive reaction of the eggplant at high doses, ie, the presence of functional monomers, leading to branching reactions and chain cleavage reactions depending on the dose.

The change in storage modulus of FIG. 20 was also similar to the composite viscosity.

Referring to FIG. 21, the curve slope ranges from 1.32 to 1.69, and the slope decreases due to the increase in the dose and the branching and the molecular weight distribution.

Composite viscosity, which is the object of the present invention, was increased by 4.5 times than that of pure polylactic acid in Example 21, and the storage modulus was increased by about 20 times.

Examples 25-30 are for irradiated polylactic acid comprising 3 parts by weight of GMA. Their thermal and rheological properties are shown in Table 2 and Figures 25-27.

Interestingly, the GMA is increased and the degree of gelation is still low depending on the dosage. This shows a peculiar result that almost no crosslinking reaction occurs under the dose of 100 kGy. This indicates that after modification, which is one of the objects of the present invention, high viscosity and storage modulus can be maintained without losing thermoplastic properties.

The melting temperature of the modified polylactic acid gradually decreased due to the branching effect of the chain, and the crystallinity was observed at the minimum when the 20 kGy (Example 28) was investigated. Compared with the polylactic acid containing 1 part by weight of GMA, it can be seen that the minimum value of the heat of fusion increases with the dose. Branching and chain cleavage reactions are exhibited by the effect of irradiation due to the inclusion of GMA. And the flow behavior shows stronger shear dependence than polylactic acid containing 1 part by weight of GMA. The composite viscosity and storage modulus of 20 kGy dose of polylactic acid (Example 28) at a frequency of 0.1 rad / s increased 10 times or more than the composite viscosity and storage modulus of pure polylactic acid, respectively. This is comparable to the previously described reactive modified polyesters and organoclays and nanocomposites polylactic acid for the foaming process. However, continuous low-density foams lack the melt compound viscosity. It can be seen from the degree of gelation and FIG. 24 that a crosslinking reaction does not occur and a branching reaction or a chain extension reaction occurs to prepare a plastically modified polylactic acid capable of post-processing.

The largest change in the present invention was seen in the modified polylactic acid of Examples 31-40, and this change showed a much higher value of composite viscosity and storage modulus than the modified polylactic acid developed to date and at the same time crosslinking It is almost free of thermoplastic properties.

Table 2 shows the gelability and thermal properties, and Fig. 25-27 shows their rheological properties.

The glass transition temperature decreased with the addition of GMA recovered as polylactic acid as the dose increased, but the melting temperature was slightly lower than that of pure polylactic acid after irradiation. Here, the degree of crystallization by electron beam irradiation decreased drastically. As shown in Table 2, the degree of gelation of the modified polylactic acids (Examples 31-37) at a lower intensity than 200 kGy was very low, but suddenly increased at 300 kGy or more (Examples 38-40). . The results showed that branching reactions were superior to crosslinking at 200 kGy or less, but crosslinking could occur at very high intensity electron beams above 300 kGy. As shown in Table 2, the polylactic acid samples of 400 and 500 kGy showed very high gelation degree and were unable to prepare the specimens due to the rubbery properties at the temperature of 200 ° C. when the viscoelastic specimens were prepared. Therefore, the modified polylactic acid irradiated more than 400 kGy, even though the composite viscosity and storage modulus is high, the thermoplastic properties are lost due to crosslinking, so post-processing becomes difficult, and thus, continuous melt foaming or injection foaming cannot be performed.

25 to 27, it can be seen that the rheological properties of 5 parts by weight of GMA addition-modified polylactic acid were much more affected than when 3 parts by weight of GMA were included.

As shown in FIG. 25, due to the plasticity effect of GMA, the composite viscosity of polylactic acid (Comparative Example 16) containing only 5 parts by weight of GMA without being irradiated with an electron beam was much lower than that of pure polylactic acid. The proportion increased greatly. All modified polylactic acid showed non-Newtonian flow characteristics, although modified with a small intensity of 1 kGy. In addition, the storage and elastic modulus were also greatly affected by the dose. The cause of this enormous increase in composite viscosity and modulus can be solved due to chain entanglement and the formation of physically crosslinked structures.

The composite viscosity and storage modulus of polylactic acid received 200kGy dose were about 200 to 10,000 times higher than pure polylactic acid at the frequency of 0.1rad / sec, respectively. This tremendous increase is due to the fact that the high molecular weight branched and linear chains produced by the addition of GMA and electron beam irradiation have a physical structure.

The range of the curve slope of FIG. 27 ranged from 0.07 (polylactic acid irradiated with 300 kGy; Example 38) to 1.65 (unirradiated polylactic acid) and decreased with increasing dose. The slope was 200 at 200 kGy and 0.07 at 300 kGy. At 300 kGy, the high crosslinking resulted in a slope similar to that of common elastomers with chemical crosslinking. This proves that the modified polylactic acid irradiated at a dosage of 300 kGy or more is difficult to melt.

28 to 30 are viscoelastic curves of Examples 41-46, which are not described in Table 2, after 10 parts by weight of GMA was added, and the amount of electron beam irradiation, 0 kGy. 1 kGy (Example 41), 5 kGy (Example 42), 10 kGy (Example 43), 20 kGy (Example 44), 50 kGy (Example 45), 100 kGy (Example 46) The result is polylactic acid. Although these modified polylactic acid also increased the composite viscosity and storage modulus, the effect was significantly reduced compared to the modified polylactic acid containing 5 parts by weight of GMA. In addition, the excessive amount of GMA caused a problem in that it was difficult to put into the mixing process by the twin screw extruder and the quality was uneven.

Therefore, in the embodiment of the present invention, the addition amount of GMA is preferably added 0.1-10 parts by weight, but most preferably 3-5 parts by weight.

la. Reaction Path

Formula 1 is a reaction pathway showing the chain cleavage of pure polylactic acid by electron beam radiation, the compound viscosity according to the dosage shown in the results of Comparative Example 1-7, the chain cleavage path which causes the decrease of storage modulus, and also the branching which is a possible path , Crosslinking is also shown. From the results of the degree of gelation, crosslinking hardly occurred.

Formula (2) is a reaction path between GMA and polylactic acid, and the epoxy functional group of GMA reacts with a hydroxyl group at the end of polylactic acid to cause an esterification reaction with carbonyl group.

Formula 3 shows a route for branching and coupling (chain extension) when the ether and ester reaction materials represented by Formula 2 are exposed to an electron beam. Except for the special case of Examples 38-40, the degree of gelation was very low, and even at 200 kGy dose of GMA 5 parts by weight of polylactic acid, it was judged that the crosslinking reaction hardly occurred because the gelation degree was very low. Interestingly, as shown in Eq. 3, the coupling reaction pathway can be inferred, resulting in the formation of high molecular weight linear molecules. These branched and high molecular weight linear chain molecules induced a significant increase in melt compound viscosity and storage modulus.

1 is a composite viscosity versus frequency curve of Comparative Examples 1-6

2 shows the storage modulus versus frequency curves of Comparative Examples 1-6.

3 is a log-log curve of storage modulus vs. loss modulus of Comparative Examples 1-6.

4 is a composite viscosity versus frequency curve of Comparative Example 8-10

5 is the storage modulus vs. frequency curve of Comparative Example 8-10

6 is a log-log curve of storage modulus vs. loss modulus of Comparative Example 8-10.

7 is a composite viscosity versus frequency curve of Comparative Example 14-16

8 shows the storage modulus versus frequency curve of Comparative Example 14-16.

9 is a log-log curve of storage modulus vs. loss modulus of Comparative Example 14-16.

10 is a composite viscosity versus frequency curve of Examples 1-6

11 shows the storage modulus versus frequency curves of Examples 1-6.

12 is a log-log curve of storage modulus vs. loss modulus of Examples 1-6.

13 is a composite viscosity vs. frequency curve of Examples 7-12

14 shows the storage modulus versus frequency curves of Examples 7-12.

15 is a log-log curve of storage modulus versus loss modulus of Examples 7-12.

16 is a composite viscosity versus frequency curve of Examples 13-18

17 shows the storage modulus versus frequency curves of Examples 13-18.

18 is a log-log curve of storage modulus versus loss modulus of Examples 13-18.

19 is a composite viscosity versus frequency curve of Examples 19-24

20 is the storage modulus versus frequency curve of Examples 19-24.

21 is a log-log curve of storage modulus versus loss modulus of Examples 19-24.

22 is a composite viscosity versus frequency curve of Examples 25-30

23 is a storage modulus versus frequency curve of Examples 25-30.

24 is a log-log curve of storage modulus versus loss modulus of Examples 25-30.

FIG. 25 is a composite viscosity versus frequency curve of Examples 31-38

26 is a storage modulus versus frequency curve of Examples 31-38.

27 is a log-log curve of storage modulus versus loss modulus of Examples 31-38.

FIG. 28 is a composite viscosity versus frequency curve of Examples 41-46

29 is a storage modulus versus frequency curve of Examples 41-46.

30 is a log-log curve of storage modulus versus loss modulus of Examples 41-46.

Claims (5)

The host is polylactic acid, A functional monomer is composed of 0.1-10 parts by weight based on 100 parts by weight of the polylactic acid a monomer having one double radical reaction, one epoxy group capable of rapid condensation polymerization, or a maleic anhydride group or an isocyanate group as a functional monomer. , 0.1 kGy-300 kGy high viscosity modified high viscosity modified plant-derived biodegradable resin, characterized in that modified by electron beam irradiation. The method of claim 1, wherein the monomer is glycidyl methacrylate (GMA), 1,2-EPOXY-9-DECENE, 1,2-EPOXY-5-HEXENE, 4-VINYL-1-CYCLOHEXENE A high viscosity modified plant-derived biodegradable resin for high magnification foam, characterized in that it is used alternatively from -1,2-EPOXIDE, LIMONENE-1,2-EPOXIDE, ALLYL GLYCIDYL ETHER. The host is polylactic acid, A functional monomer comprising 0.1-10 parts by weight based on 100 parts by weight of the polylactic acid a monomer having a double bond, one epoxy group capable of rapid radical polymerization, or a maleic anhydride group or an isocyanate group capable of rapid radical polymerization. A method of producing a high viscosity modified plant-derived biodegradable resin for high magnification foaming, wherein the resin composition is irradiated with an electron beam of 0.1 kGy-300 kGy. The method of claim 3, wherein the monomer is glycidyl methacrylate (GMA), 1,2-EPOXY-9-DECENE, 1,2-EPOXY-5-HEXENE, 4-VINYL-1-CYCLOHEXENE -1,2-EPOXIDE, LIMONENE-1,2-EPOXIDE, ALLYL GLYCIDYL ETHER alternatively used for producing a high viscosity modified plant-derived biodegradable resin for high magnification foam. delete

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