JP3622561B2 - Lactic acid composition and molded article thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The composition of the present invention can be used for various applications such as packaging materials, industrial materials, industrial articles, containers, etc., but is particularly suitable as a material for films, tapes and sheets that require transparency and flexibility. In addition, since it has a flexible component in the branched chain, it has stability over time, has a wide rubber-like elastic region and excellent shock absorption, and is very suitable for use as a vibration damping material, vibration damping material, or shock absorbing material. Although it is not particularly limited as a vibration damping material / vibration-proof material, it can be vibrated and accompanied by vibrations in bearings of rotating shafts, automobiles, machinery, ships, building materials, acoustic materials, etc. Therefore, it can be used as a countermeasure against noise generated. Or, it can be used as a sound absorbing and insulating material and a vibration reducing material by using it as an interior material in automobiles and buildings.
[0002]
Further, by using a damper or a vibration isolator containing the composition according to the present invention, it can be applied to uses for reducing earthquake resistance of a building, micro-vibration of an internal combustion drive device, and the like. Although it is not particularly limited as a shock absorbing application, it can be used for bridge girder parts of road bridges, road or quay side walls, building floors / walls, shock absorbing parts of vehicles, etc. The composition of the present invention or a molded product thereof is used for a part that receives repeated impacts, such as application to encapsulation, etc., application to canes / sports equipment, application to tools / equipment such as hammers, etc. It is possible to reduce the impact. Furthermore, since it has biodegradability, the problem of waste like the conventional plastic is also reduced.
[0003]
[Prior art]
In recent years, biodegradable polymers that can be decomposed in the natural environment and molded articles thereof have been demanded from the viewpoint of protecting the natural environment, and research on natural degradable resins such as aliphatic polyester has been actively conducted. In particular, the lactic acid polymer has a glass transition point of 60 ° C. and a melting point of 170 to 180 ° C., and has high thermal stability and excellent transparency.・ The spread is awaited.
[0004]
It is known that the lactic acid-based polymer has a very large loss angle tangent of 2.0 to 3.0 at the glass transition point, and has unique properties as compared with general-purpose resins. However, the homopolymer has a glass transition point around 60 ° C., and its properties were not fully utilized near room temperature. In order to extract the characteristics, a method of preparing a copolymer or blending other components can be considered. However, in the case of copolymerization, if the copolymerization is carried out at a composition ratio necessary to sufficiently lower the glass transition point, the copolymer has a random block structure and the block length of the lactic acid component is shortened. As a result, the characteristics of the lactic acid polymer deteriorate and it becomes difficult to obtain a sufficient loss angle tangent value. When blending other components, a method of adding a plasticizer for the purpose of lowering the glass transition point is conceivable, but simply blending causes bleeding out of the plasticizer and there is a problem in stability over time. It was.
[0005]
In JP-A-8-199052, JP-A-8-199053, JP-A-8-283557, etc., a composition containing a (poly) ester plasticizer using an ether bond-containing glycol such as polyethylene glycol is disclosed. However, lactic acid polymers have high crystallinity and low stability over time. In addition, there is a problem in melting characteristics when forming a film or the like.
US Pat. No. 5,180,765 discloses a composition in which a low molecular weight product of lactic acid or lactide, which is a lactic acid polymer raw material, is added as a plasticizer as a plastic component. However, a lactic acid polymer containing a low molecular weight product of lactic acid or lactide is thermally stable. However, there is a problem in stability over time because the properties are lowered and the decomposition is accelerated.
[0006]
[Problems to be solved by the invention]
As described above, it has heretofore been difficult to produce a composition having stability over time and maintaining a high loss angle tangent in a temperature range of room temperature or higher.
[0007]
[Means for Solving the Invention]
In order to solve such problems, the present inventors have intensively studied, and as a result, a lactic acid polymer is a main chain, and a component that shifts the transition temperature represented by a plasticizer to a low temperature is a side chain or a crosslinked chain. The present inventors have found a composition that exhibits a stable value in a temperature range of normal temperature or higher without reducing the loss angle tangent value of a lactic acid-based polymer by chemical bonding. It has also been found that this composition has stability over time.
[0008]
That is, the present invention provides a lactic acid-based composition that has a high loss angle tangent and is stable over time, and is particularly suitable for use as a vibration damping material, a vibration damping material, and a shock absorbing material, and a molded product thereof. It is. More specifically, the present invention has a transition temperature of 30 ° C. or less in dynamic viscoelasticity measurement (JIS K7198A method), and a dynamic storage elastic modulus of 1 × 10 ⁴ to 150 ° C. from the transition temperature. The lactic acid composition is 1 × 10 ⁸ Pa and the loss angle tangent is 0.1 to 3.0.
In addition, the transition temperature of the dynamic storage elastic modulus in JIS K7198A method is the temperature at which the composition or molded product is physically soft and deformed, and the molding obtained from the same polymer composition or the same polymer composition. Even if it is a product, it becomes a different value for each composition or molded product depending on the degree of crystallization and the crystallization state. In this respect, it differs from the glass transition temperature which is a value inherent to the polymer.
[0009]
The transition temperature is 30 ° C. or lower, preferably 10 ° C. or lower. If it exceeds 30 ° C., it becomes a temperature range below the transition point at room temperature. Because there is a problem with sex.
The dynamic storage elastic modulus is 1 × 10 ⁴ to 1 × 10 ⁸ Pa, preferably 1 × 10 ⁵ to 1 × 10 ⁸ Pa, and the loss angle tangent is 0.1 to 3.0, preferably 0.8. 2 to 1.5. This is because if these ranges are exceeded, sufficient characteristics cannot be obtained for a flexible vibration damping material or shock absorbing application. Furthermore, these values need to be stable against temperature changes. This is because when the value changes greatly, the characteristics change due to changes in the operating temperature.
[0010]
The present invention relates to a lactic acid composition obtained by melt-mixing a lactic acid polymer and a plastic component at 100 to 180 ° C. to cause a polymerization reaction. Furthermore, it is related with the molded article of the composition obtained by this invention.
Hereinafter, the lactic acid polymer and plastic component used in the present invention will be described in order.
The lactic acid polymer in the present invention includes a lactic acid homopolymer, a lactic acid copolymer, and a blend polymer. Lactic acid homopolymers include L-lactide composed of two L-lactic acids, D-lactide composed of D-lactic acid, and meso-lactide composed of L-lactic acid and D-lactic acid. It may be a polymer as a main raw material, and can be obtained by carrying out a polymerization reaction in the presence of a catalyst. A copolymer containing only L-lactide or D-lactide can be crystallized to obtain a copolymer having a high melting point. In the copolymer of the present invention, various characteristics can be further improved by combining these three kinds of lactides. The lactic acid copolymer is obtained by copolymerizing a lactic acid monomer or other component copolymerizable with lactide. Examples of such other components include dicarboxylic acids having two or more ester bond-forming functional groups, polyhydric alcohols, hydroxycarboxylic acids, lactones, etc., and various polyesters and various polyethers composed of these various components. And various polycarbonates.
[0011]
Examples of the dicarboxylic acid include succinic acid, adipic acid, azelaic acid, sebacic acid, terephthalic acid, and isophthalic acid. Examples of polyhydric alcohols include aromatic polyhydric alcohols such as those obtained by addition reaction of bisphenol with ethylene oxide, ethylene glycol, propylene glycol, butanediol, hexanediol, octanediol, glycerin, sorbitan, trimethylolpropane, neo Examples include aliphatic polyhydric alcohols such as pentyl glycol, ether glycols such as diethylene glycol, triethylene glycol, polyethylene glycol, and polypropylene glycol. Examples of the hydroxycarboxylic acid include glycolic acid, hydroxybutylcarboxylic acid, and others described in JP-A-6-184417. Examples of the lactone include glycolide, ε-caprolactone glycolide, ε-caprolactone, β-propiolactone, δ-butyrolactone, β- or γ-butyrolactone, pivalolactone, δ-valerolactone, and the like.
[0012]
The lactic acid polymer is synthesized by a conventionally known method. That is, a direct dehydration condensation from a lactic acid monomer or a lactic acid cyclic dimer as described in JP-A-7-33861, JP-A-59-96123, Polymer Proceedings Proceedings Vol. 44, pages 3198-3199 It can be synthesized by ring-opening polymerization of lactide.
When performing direct dehydration condensation, any lactic acid of L-lactic acid, D-lactic acid, DL-lactic acid, or a mixture thereof may be used. Also, in the case of performing ring-opening polymerization, any lactide of L-lactide, D-lactide, DL-lactide, or a mixture thereof may be used.
Further, when the lactic acid component is 50% or less by weight in the lactic acid polymer main chain, the properties unique to polylactic acid such as transparency, heat resistance and biodegradability are lost. Furthermore, when the weight average molecular weight is 10,000 or less, high elasticity cannot be obtained and decomposition is also promoted, which is not preferable.
[0013]
Lactide synthesis, purification and polymerization procedures are described, for example, in US Pat. No. 4,057,537, published European Patent Application No. 261572, Polymer Bulletin, 14, 491-495 (1985) and Makromol Chem. , 187, 1611-1628 (1986) and the like.
The catalyst used in this polymerization reaction is not particularly limited, but a known lactic acid polymerization catalyst can be used. For example, tin compounds such as tin lactate, tin tartrate, dicaprylate, dilaurate, dipalmitate, tin distearate, dioleate, α-naphthoate, β-naphthoate, and octylate Tin powder, tin oxide; zinc powder, zinc halide, zinc oxide, organic zinc compounds, titanium compounds such as tetrapropyl titanate, zirconium compounds such as zirconium isopropoxide, antimony compounds such as antimony trioxide, Examples thereof include bismuth compounds such as bismuth (III) oxide, and aluminum compounds such as aluminum oxide and aluminum isopropoxide. Among these, a catalyst made of tin or a tin compound is particularly preferable from the viewpoint of activity. The amount of these catalysts used is, for example, about 0.001 to 5% by weight based on lactide when ring-opening polymerization is performed. The polymerization reaction can be usually carried out at a temperature of 100 to 220 ° C. in the presence of the catalyst, although it varies depending on the catalyst type. It is also preferable to carry out two-stage polymerization as described in JP-A-7-247345.
[0014]
As the plastic component used in the present invention, a plasticizer generally used for plasticizing polylactic acid or polylactic acid-modified products can be used. As examples of these plasticizers, many plasticizers widely developed for vinyl chloride polymers can be used. Preferably, phthalate ester, adipic acid ester, glycolic acid derivative, ether ester derivative, glycerin derivative, alkyl Single or a mixture selected from phosphoric acid ester, dialkylate, diester, tricarboxylic acid ester, polyester, polyglycol diester, alkyl alkylter diester, aliphatic diester, alkylate monoester, citrate ester, aromatic hydrocarbon Can be used. More specifically, a single or a mixture of plastic components selected from dimethyl phthalate, diethyl phthalate, ethyl phthalyl ethyl glycolate, triethylene glycol diacetate, ether ester, tributyl acetylcitrate, and triacetin is preferred. .
[0015]
Regarding the solubility parameter (SP) value, it is generally known that those having a close SP value have high compatibility. Since the SP value of the lactic acid-based polymer is around 9.7, a plasticizer having an SP value of 9.0 to 11.0 is preferable. More preferably, it is 9.5 to 10.5. In particular, the higher the SP value than the lactic acid-based polymer, the higher the compatibility than the lower one. If it is smaller than 9.0 or larger than 11.0, the compatibility is poor, and the transparency is lowered.
[0016]
The weight average molecular weight of the plastic component is preferably 100 to 5000, more preferably 200 to 3000. If the weight average molecular weight is less than 100, a sufficient plastic effect cannot be obtained, and if it is greater than 5000, a sufficient plastic effect cannot be obtained, and the molecular properties of the plasticizer become remarkable, resulting in a decrease in heat resistance and transparency. Therefore, it is not preferable.
Although the compounding quantity of a plastic component is not specifically limited, It is 1-500 weight part with respect to 100 weight part of lactic acid polymers, Preferably it is 5-100 weight part. This is because if the plasticizer is less than 5 parts by weight, the softening temperature of the lactic acid-based polymer cannot be lowered sufficiently, and if it is more than 100 parts by weight, the efficiency of the copolymerization reaction is lowered. Specifically, for example, as an effective formulation example for plasticizing a lactic acid-based polymer, 10 to 100 parts by weight of dimethyl phthalate and / or 10 to 100 parts by weight of diethyl phthalate are added to 100 parts by weight of the lactic acid-based polymer. Can be used. Alternatively, RS1000 manufactured by Asahi Denka Kogyo Co., Ltd. may be similarly used as triacetin and / or triethylene glycol diacetate or ether ester. By using these plastic components, the softening temperature can be lowered while maintaining the transparency and hue of the lactic acid composition. As a result, the hue of the copolymer can be kept good, and a sufficient plastic effect can be imparted to the molded product.
[0017]
In addition, the weight average molecular weight of a lactic acid-type polymer is 10,000 or more, Preferably it is 50,000-300,000.
[0018]
Next, a manufacturing method is demonstrated in order.
The lactic acid polymer and the plastic component are previously melt mixed. As a method for plasticizing the lactic acid polymer with a plastic component, a known method can be used. For example, 10 to 50 parts by weight of dimethyl phthalate and 10 to 50 parts by weight of diethyl phthalate are added to 100 parts by weight of the lactic acid polymer. It is obtained by stirring and melting and mixing in a nitrogen atmosphere by extrusion at 0 ° C. When melt-mixing the lactic acid polymer and the plastic component in advance, it is preferable to carry out in a dry nitrogen stream, for example, at 180 ° C. in order to prevent moisture from entering. The melting and mixing temperature is preferably equal to or higher than the melting temperature of the lactic acid polymer. If the melting temperature is too high, the plastic component is volatilized and the physical properties of the composition become insufficient. It is preferable to carry out within a range.
Next, a branched / crosslinked structure is prepared from the obtained mixture. As a method for initiating the branching / crosslinking reaction, a known method such as a method of adding a radical initiator such as peroxide or a method of irradiating an electron beam having a wavelength of 400 nm or less and an intensity of 120 mW / cm ² or more can be used. For example, 0.1 to 10 parts by weight of peroxide is added to 100 parts by weight of the mixture to carry out the reaction.
[0019]
Further, when the lactic acid polymer and the plastic component are melt-mixed, it is possible to carry out a branching / crosslinking reaction at the same time. For example, when a biaxial horizontal reactor is used for the polymerization reaction, the lactic acid polymer and the plastic component may be added simultaneously with the radical initiator or the like, and the above-mentioned electron beam is used when the lactic acid polymer and the plastic component are melt-mixed. Irradiation may cause a mixed reaction. Furthermore, it is also possible to carry out the reaction by irradiating an electron beam again after melt-mixing a lactic acid-based polymer and a plastic component and adding a reaction initiator such as acrylic acid.
[0020]
When charging only the reaction initiator from the middle, the lactic acid polymer and the plastic component can be melt-kneaded in advance, so the temperature at the initiator charging point can be lowered and the reaction can proceed slowly. It is possible to react without reducing the activity of the initiator. The reaction temperature is 120 to 180 ° C. When the reaction temperature is lower than 120 ° C., the reaction does not proceed sufficiently, and the reaction at a temperature higher than 180 ° C. is not preferable because it promotes the deterioration of the reaction initiator or the decomposition reaction of the lactic acid polymer by the reaction intermediate. . Also, the plastic component may be reduced in volatilization, and the desired physical properties cannot be obtained. When a biaxial horizontal reactor is used, depending on the relationship with the reaction temperature, for example, when the reaction is performed at 120 to 180 ° C., the reaction proceeds sufficiently with a residence time of 5 to 20 minutes, and lactic acid A branched / crosslinked copolymer of polymer and plastic component can be obtained.
[0021]
The obtained copolymer contains a plastic component in the molecular structure, and is a thermoplastic resin having flexible properties. With this copolymer, the molding temperature can be set lower than in the case of polylactic acid alone, there is little molecular deterioration during molding, it is difficult to color, and a transparent molded product can be obtained. Further, since the molding temperature can be set low, the cooling time after molding can be shortened, and good moldability is exhibited.
The flexibility of this copolymer can be controlled by appropriately changing the composition of the plastic component used and the amount used. Furthermore, after the end of the reaction or after the completion of the reaction, the unreacted lactide monomer and reaction by-products remaining about 1 to 3% can be removed by exposing to a reduced pressure in a molten state.
[0022]
As a specific decompression method, the latter half of the biaxial horizontal reactor can be maintained at 120 to 160 ° C. and 1 to 50 Torr, and retained and devolatilized for 3 to 15 minutes. Thus, the copolymer which removed the lactide monomer and the by-product can obtain an excellent one having greatly improved stability over time.
In a simple blend of a lactic acid polymer and a plastic component, the plastic component bleeds out of the system as the lactic acid polymer crystallizes, and the effect of lowering the transition point is reduced. In addition, if unreacted substances and by-products are not sufficiently removed and remain, there is a risk of contributing as a hydrolysis accelerator.
[0023]
The copolymer of the present invention can be prepared in a known reaction vessel in addition to the above-described biaxial horizontal reactor, for example, a vertical reaction vessel or a horizontal reaction vessel provided with a uniaxial or multiaxial agitator A reaction apparatus such as a horizontal reaction vessel provided with scraping blades of one or more axes, a kneader of one or more axes, or an extruder of one or more axes may be used alone. Alternatively, a plurality of groups may be connected in series or in parallel.
[0024]
In addition, the composition of the present invention can be subjected to various modifications by adding secondary additives. Examples of secondary additives include UV absorbers, pigments, colorants, various fillers, electrostatic agents, mold release agents, fragrances, antibacterial agents, nucleating agents, stabilizers such as antioxidants and regulators, etc. , Other similar ones. Furthermore, it is also possible to add a plasticizer as a secondary plasticizer and add it as appropriate.
[0025]
In the present invention and the following examples, the weight average molecular weight of the polymer is a polystyrene conversion value by GPC analysis, and the glass transition point, crystallization point, and melting point of the polymer are values measured by a scanning differential calorimeter (DSC). . Moreover, the dynamic viscoelasticity measurement was measured with Shimadzu Corporation dynamic viscoelasticity measuring apparatus DVA-300 according to JIS K7198A method.
[0026]
【Example】
Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited thereto.
In this example, experiments were conducted using the following lactic acid-based polymer, plasticizer, and peroxide.
<Lactic acid polymer A (P1)>
To 90 parts by weight of L-lactide, 10 parts by weight of D-lactide is added, melted and mixed in an inert gas atmosphere, and 0.24 parts by weight of tin octylate as a ring-opening polymerization catalyst is stirred with a biaxial kneader. After polymerization at 15 ° C. for 15 minutes, low-crystalline polylactic acid chip C1 was obtained by extruding with a nozzle having a diameter of 2 mm, cooling with water and cutting.
The chip C1 was treated in nitrogen at 120 ° C. and a pressure of 1.5 kg / cm ² for 12 hours to remove unreacted monomer (lactide) to obtain a chip P1. The weight average molecular weight of chip P1 was 168,000, and the residual monomer (lactide) was 0.5% or less. As a result of measuring DSC, it was observed that the glass transition temperature was 55.3 ° C., the crystallization temperature was 144.9 ° C., and the melting point was 175.7 ° C.
[0027]
<Lactic acid polymer B (P2)>
To 75 parts by weight of L-lactide, 25 parts by weight of D-lactide is added, melted and mixed in an inert gas atmosphere, and 0.24 parts by weight of tin octylate as a ring-opening polymerization catalyst is stirred with a biaxial kneader. After polymerization at 15 ° C. for 15 minutes, an amorphous polylactic acid chip C2 was obtained by extruding with a nozzle having a diameter of 2 mm, cooling with water and cutting.
Chip C2 was treated in nitrogen at 120 ° C. under a pressure of 1.5 kg / cm ² for 12 hours to remove unreacted monomer (lactide) to obtain chip P2. The weight average molecular weight of the chip P2 was 117,000, and the residual monomer (lactide) was 1.5% or less. As a result of measuring DSC, the glass transition temperature was 51.7 ° C., and the crystallization temperature and the melting point were not observed.
[0028]
<Plastic component: Triacetin (manufactured by Daihachi Chemical Industry Co., Ltd.) (S1)>
Acid value: 0.05 or less, Hue (APHA): 20 or less, Molecular weight: 218, Specific gravity (20/20 ° C.): 1.160 ± 0.003, Solubility parameter (HOY): 9.9
[0029]
<Peroxide: Kayahexa AD40C (manufactured by Kayaku Akzo Co., Ltd.) (O1)>
Content: 40%, active oxygen content: 4.4%, molecular weight: 290.44, 10 hour half-life temperature: 118 ° C., activation energy: 36.0 kcal / kmol (CAS No. 78-63-7)
[0030]
(Example 1)
100 parts by weight of P1 and 40 parts by weight of S1 are sufficiently melt-mixed with a twin screw extruder at 190 ° C., and 2.5 parts by weight of O1 with respect to P1 is added to the melted mixture, and then mixed for an average of 5 minutes. The lactic acid polymer chip (PC1) was obtained by reacting, extruding with a nozzle having a diameter of 2 mm, cooling with water and cutting. After the chip PC1 was vacuum-dried at 60 ° C. to make it completely dry, a business card large plate (1 mmt) was prepared by injection molding, and dynamic viscoelasticity measurement was performed.
The result of the dynamic viscoelasticity measurement is shown in FIG. From this figure, the dynamic storage elastic modulus is 1.5 × 10 ^{6 to} 1.2 × 10 ⁷ and the loss angle tangent is 0.15 to 10 ° C. in the temperature range from the transition temperature to 150 ° C. It turns out that it is 0.25.
[0031]
(Example 2)
100 parts by weight of P2 and 40 parts by weight of S1 are sufficiently melt-mixed with a twin screw extruder at 190 ° C., and 2.5 parts by weight of O1 with respect to P2 is added to the melted mixture and then mixed for an average of 5 minutes The lactic acid polymer chip (PC2) was obtained by reacting, extruding with a nozzle having a diameter of 2 mm, cooling with water and cutting. After the chip PC2 was vacuum-dried at 60 ° C. to make it completely dry, a business card large plate (1 mmt) was prepared by injection molding, and dynamic viscoelasticity measurement was performed.
The result of the dynamic viscoelasticity measurement is shown in FIG. From this figure, the dynamic storage elastic modulus is 9.0 × 10 ^{4 to} 1.5 × 10 ⁶ and the loss angle tangent is 0.3 to 0.3 in the temperature range from 20 ° C. to the transition temperature to 150 ° C. It turns out that it is 1.0.
[0032]
(Comparative Example 1)
100 parts by weight of P1 and 40 parts by weight of S1 are melt-mixed on average by a twin-screw extruder at 190 ° C. for 5 minutes, extruded through a nozzle with a diameter of 2 mm, cooled with water and cut to give a lactic acid polymer chip (RP1) Got. The chip RP1 was vacuum dried at 60 ° C. to make it completely dry, and then a business card large plate (1 mmt) was prepared by injection molding, and dynamic viscoelasticity measurement was performed.
The result of the dynamic viscoelasticity measurement is shown in FIG. From this figure, the dynamic storage elastic modulus is 8.0 × 10 ^{5 to} 8.0 × 10 ⁶ and the loss angle tangent is 0.1 to 0.1 in the temperature range from 20 ° C. to the transition temperature to 150 ° C. It turns out that it is 0.25.
[0033]
(Comparative Example 2)
100 parts by weight of P2 and 40 parts by weight of S1 are melt-mixed on average by a twin screw extruder at 190 ° C. for 5 minutes, extruded through a nozzle with a diameter of 2 mm, cooled with water and cut to give a lactic acid polymer chip (RP2) Got. The chip RP2 was vacuum dried at 60 ° C. to make it completely dry, and then a business card large plate (1 mmt) was prepared by injection molding, and dynamic viscoelasticity measurement was performed.
The result of the dynamic viscoelasticity measurement is shown in FIG. From this figure, the dynamic storage elastic modulus is 1.0 × 10 ^{4 to} 1.8 × 10 ⁶ and the loss angle tangent is 0.3 to 3.0 ° C. in the temperature range from 25 ° C. and from the transition temperature to 90 ° C. It turns out that it is 2.0. However, it can be seen that the temperature range is narrow, each value changes dramatically, and draws down in the temperature range of 90 ° C. or higher.
[0034]
【The invention's effect】
According to the present invention, a stable value is exhibited in a temperature range of normal temperature or higher without reducing the loss angle tangent value of the lactic acid-based polymer. In addition, this composition has stability over time.
[Brief description of the drawings]
1 is a graph showing the results of dynamic viscoelasticity measurement of Example 1. FIG.
2 is a graph showing the results of dynamic viscoelasticity measurement of Example 2. FIG.
FIG. 3 is a diagram showing the results of dynamic viscoelasticity measurement of Comparative Example 1. FIG. 4 is a diagram showing the results of dynamic viscoelasticity measurement of Comparative Example 2.

Claims (6)

It is composed of a lactic acid-based polymer having a branched or network structure composed of a main chain structure component containing a lactic acid component with a weight fraction of 50% or more and a plastic component. And a lactic acid composition having a dynamic storage elastic modulus of 1 × 10 ⁴ to 1 × 10 ⁸ Pa and a loss angle tangent of 0.1 to 3.0 in the temperature range from the transition temperature to 150 ° C. . The structural chain contains a plastic component having a weight average molecular weight of 10,000 or more and a solubility parameter (SP) value of 9.0 to 11.0 when the lactic acid polymer has a weight average molecular weight of 10,000 or more. The lactic acid composition according to 1. Plastic component is phthalate ester, adipic acid ester, glycolic acid derivative, ether ester derivative, glycerin derivative, alkyl phosphate ester, dialkylate, diester, tricarboxylic acid ester, polyester, polyglycol diester, alkylalkylate diester, aliphatic diester, alkyl diester The lactic acid composition according to claim 1 or 2, wherein the lactic acid composition is a single or plural mixture selected from a labeler monoester, a citrate ester and an aromatic hydrocarbon. The damping material which consists of a composition as described in any one of Claims 1-3. The vibration isolator which consists of a composition as described in any one of Claims 1-3. The impact-absorbing material which consists of a composition as described in any one of Claims 1-3.

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