WO2014142590A1 - Poly lactic acid modifier, method for preparing poly lactic acid modifier, method for modifying poly lactic acid using same, biodegradable foam composition using modified poly lactic acid, and foam for shoes using biodegradable foam composition - Google Patents

Abstract

The present invention relates to a method for modifying a poly lactic acid and a biodegradable foam composition using the same. The method for modifying a poly lactic acid is characterized in that the poly lactic acid polymerizes to be modified into a molecule having a double bond, and the biodegradable foam composition is characterized by being produced through mixing and polymerization of the modified poly lactic acid and a mixing substance.

Description

Modifiers of polylactic acid, methods of preparing polylactic acid modifiers, methods of modifying polylactic acid using the same, biodegradable foam compositions using modified polylactic acid, and shoe foams using biodegradable foam compositions

The present invention relates to a modifier of polylactic acid, and more particularly, to a polylactic acid modifier to modify polylactic acid and to use it as a biodegradable foam, a method for preparing a polylactic acid modifier, a polylactic acid modifier using the same, and a modified A biodegradable foam composition using polylactic acid and a shoe foam using the biodegradable foam composition.

Polylactic acid (PLA, poly (lactic acid), polylactic acid) is a biodegradable thermoplastic polyester with great potential to replace traditional petrochemical polymers. Possible polymer material.

Polylactic acid has the property of rapidly degrading and reproducing carbon dioxide under certain composting conditions, thus providing a more disposal option for these resins than most other organic polymers. In addition, polylactic acid exhibits superior thermal processing properties in comparison to biopolymers such as polyethylene glycol and polycaprolactone in addition to the eco-friendliness, biocompatibility, and resource savings of biopolymers. Therefore, the use has been expanded to general consumption materials such as surgical sutures and prosthetics utilizing biocompatibility and bioabsorbability of polylactic acid, as well as packaging materials utilizing biodegradability, processability and transparency. These packaging sectors include various rigid or semi-rigid articles such as 'clamshell' containers, prepared foods and other food serving trays and bottles or other containers.

However, the above-described prior art has the following problems.

Polylactic acid material has problems such as cracking point, slow decomposition rate, and hydrophobic point. In particular, polylactic acid has high tensile strength, elastic modulus, and low elongation, and thus has poor impact resistance, thereby making it an obstacle to application to various packaging materials and elastic materials. In addition, the slow biodegradation characteristics have a problem in the application to various general consumer goods as well as medical materials. Therefore, various attempts have been made to improve the impact resistance as well as the decomposition rate.

In order to solve the above problems, an object of the present invention is to improve the flexibility and biodegradability and can be used under various conditions, polylactic acid modifier, polylactic acid modifier manufacturing method, polylactic acid modified method using the same, modified polylactic acid The present invention provides a biodegradable foam composition and a shoe foam using the biodegradable foam composition.

The modifier of polylactic acid according to the present invention is characterized in that it is composed of a compound of the following formula (1) in modifying polylactic acid using a modifier to polylactic acid (Poly Lactic Acid).

[ Formula 1]

(R ₁ and R ₂ are composed of one of the following Chemical Formulas 2 to 7)

[Formula 2]

(In Formula 2, R ₃ is hydrogen or methyl group, R ₄ is hydrogen or alkyl group of C ₁ to C ₈ , n is 1 to 20)

[Formula 3]

(In Formula 3, R ₅ is hydrogen or an alkyl group of C ₁ to C ₈ , n is 1 to 20)

[Formula 4]

(In Formula 4, R ₆ is hydrogen or an alkyl group of C ₁ to C ₈ , l + m + n is 3 to 20)

[Formula 5]

(In Formula 5, R ₇ and R ₈ are hydrogen or an alkyl group having ₁ to C ₈ , and l + m + n is 3 to 20.)

[Formula 6]

(In Formula 6, R ₉ and R ₁₀ are hydrogen or a methyl group, R ₁₁ is hydrogen or an alkyl group of C ₁ to C ₈ , m + n is 2 to 20)

[Formula 7]

(In formula 7, R ₁₂ and R ₁₃ are hydrogen or a methyl group, R ₁₄ is hydrogen or an alkyl group having ₁ to ₈ , 1 + m is 2 to 20, n is 1 to 5)

In the method for producing a polylactic acid modifier according to the present invention, in modifying polylactic acid by using a modifier to polylactic acid, any one of polyethylene glycol monool, polyethylene glycol diol, polyethylene glycol triol and male anhydride The acid is formed by the esterification reaction.

The method for modifying polylactic acid according to the present invention is a method for modifying polylactic acid, wherein the polylactic acid is modified using the above-described modifier.

In addition, the polylactic acid reforming method according to the present invention is characterized by further adding an initiator during the polymerization to react.

In addition, the initiator, 2,2 azobis (2,4-dimethylvaleronitrile), 2,2- azobisisobutyronitrile, 2,2- azodi (2-methylbutylonitrile), 1, 1-azobis (cyanacyclohexane), dimethyl-2,2-azobis (2-methylpropionate), 1-((cyano-1-methylethyl) azo) formamide, 2,5- Bis (tertbutylperoxy) -2,5-dimethyl-3-hexene, ditertbutyl peroxide, 2,5-bis (tertbutylperoxy) -2,5-dimethyl-hexene, dibenzoylperoxide, bis (Tertbutylperoxyisopropyl) benzene, butyl 4,4-bis (tertbutylperoxy) valerate, 1,1-bis (tertbutylperoxy) 3,3,5-trimethylchlorohexane, tertbutylperoxy It is characterized by being used as one or more of benzoate, lauryl peroxide, dicumyl peroxide.

The biodegradable foam composition according to the present invention is characterized by comprising the above-described modified polylactic acid and a mixed base and constituted by their foam polymerization.

The mixed base material is characterized by consisting of at least one of ethylene vinyl acetate copolymer, styrene isoprene styrene copolymer or ethylene methacrylate copolymer.

The polymerization is characterized in that it further comprises a cross-linking initiator and a blowing agent.

The crosslinking initiator is 2,5-bis (tertbutylperoxy) -2,5-dimethyl-3-hexene, ditertbutyl peroxide, 2,5-bis (tertbutylperoxy) -2,5-dimethyl -Hexene, dibenzoyl peroxide, bis (tertbutylperoxyisopropyl) benzene, butyl 4,4-bis (tertbutylperoxy) valerate, 1,1-bis (tertbutylperoxy) 3,3,5 Trimethylchlorohexane, tertbutylperoxybenzoate, lauryl peroxide and dicumyl peroxide.

The blowing agent is characterized by comprising at least one of an azodicarbonamide-based blowing agent or a dinitrosopentamethylenetetraamine-based blowing agent.

The shoe foam according to the present invention is characterized by comprising the biodegradable foam composition described above.

Another embodiment of the method for modifying polylactic acid according to the present invention is characterized by polymerizing polylactic acid (Poly Lactic Acid) into a molecule having a double bond and modifying it.

The molecule having the double bond is an acrylate (CH ₂ = CH-CO-), methacrylate (Methacrylate, CH ₂ = C (CH ₃ ) -CO-), vinyl (Vinyl, CH ₂ = CH- Or -CH = CH-), maleate (Maleate, -CO-CH = CH-CO-), styrene (styrene, CH ₂ = CH (C ₆ H ₅ )), allyl (Allyl, CH ₂ = CH-O It is characterized in that the molecule containing at least one of-).

The polymerization reaction is characterized in that the reaction is carried out dry.

The polylactic acid reforming method according to the present invention is characterized by further adding an initiator during the polymerization and reacting it.

The initiator is 2,2 azobis (2,4-dimethylvaleronitrile), 2,2-azobisisotropyronitrile, 2,2-azodi (2-methylbutylonitrile), 1,1- Azobis (cyanacyclohexane), dimethyl-2,2- azobis (2-methylpropionate), 1-((cyano-1-methylethyl) azo) formamide, 2,5-bis ( Tertbutylperoxy) -2,5-dimethyl-3-hexene, ditertbutyl peroxide, 2,5-bis (tertbutylperoxy) -2,5-dimethyl-hexene, dibenzoylperoxide, bis (tert Butyl peroxy isopropyl) benzene, butyl 4, 4-bis (tertbutyl peroxy) valerate, 1, 1-bis (tertbutyl peroxy) 3, 3, 5- trimethylchlorohexane, tert butyl peroxy benzoate , Lauryl peroxide, dicumyl peroxide, characterized in that used as one or more.

In addition, the biodegradable foam composition according to the present invention is characterized by comprising the above-mentioned modified polylactic acid and a mixed base and constituted by their foam polymerization.

The mixed base material is characterized by consisting of at least one of ethylene vinyl acetate copolymer, styrene isoprene styrene copolymer or ethylene methacrylate copolymer.

The polymerization is characterized in that it further comprises a cross-linking initiator and a blowing agent.

The crosslinking agent is 2,5-bis (tertbutylperoxy) -2,5-dimethyl-3-hexene, ditertbutyl peroxide, 2,5-bis (tertbutylperoxy) -2,5-dimethyl- Hexene, dibenzoyl peroxide, bis (tertbutylperoxyisopropyl) benzene, butyl 4,4-bis (tertbutylperoxy) valerate, 1,1-bis (tertbutylperoxy) 3,3,5- Trimethylchlorohexane, tertbutylperoxybenzoate, lauryl peroxide, dicumyl peroxide, characterized in that it is composed of one or more.

The blowing agent is characterized by comprising at least one of an azodicarbonamide-based blowing agent or a dinitrosopentamethylenetetraamine-based blowing agent.

In addition, the foam for shoes according to the present invention is characterized by including the biodegradable foam composition described above.

In the present invention, a polylactic acid modifier, a polylactic acid modifier production method, a polylactic acid modification method using the same, a biodegradable foam composition using the modified polylactic acid, and a shoe foam using the biodegradable foam composition have the following effects.

When polylactic acid is used, tensile strength and elastic modulus are lower, elongation is higher, soft physical properties are shown, and durability and flexibility are excellent, and biodegradation properties are excellent, so it can be used as foam material for biodegradable shoe midsole.

1 is a view showing the modification of the polylactic acid according to the present invention

Figure 2 shows the mechanism by which a preferred embodiment of the modifier of polylactic acid according to the present invention is synthesized.

Figure 3 is a view showing the modification of the polylactic acid according to the present invention

4 is a view showing a nuclear magnetic resonance spectrometer measurement results of a composition in which polyethylene glycol acrylate is blended with polylactic acid according to the present invention ((a) pure polylactic acid of Comparative Example 2, (b) modified polylactic acid of Example 20 )

Figure 4 is a view showing the infrared spectroscopy (FT-IR) measurement results of the composition blended polyethylene glycol acrylate to the polylactic acid according to the present invention ((a) pure polylactic acid of Comparative Example 2, (b) of Comparative Example 3 Simple blend, (c) modified polylactic acid of Example 20)

6 is a view showing a solvent extraction result of a composition in which polyethylene glycol acrylate is blended with polylactic acid according to the present invention ((a) pure polylactic acid of Comparative Example 2, (b) modified polylactic acid of Example 19, (c ) Simple blend of Comparative Example 4, (d) modified polylactic acid of Example 20, (e) simple blend of Comparative Example 3)

7 is a view showing the differential scanning calorimetry (DSC Thermogram) measurement results of a composition in which polyethylene glycol acrylate is blended with polylactic acid according to the present invention ((a) pure polylactic acid of Comparative Example 2, (b) Example 19 Modified polylactic acid, (c) modified polylactic acid of Example 20, (d) modified polylactic acid of Example 21, (e) modified polylactic acid of Example 22)

8 is a view showing the results of measurement of biodegradability of a composition blended polyethylene glycol acrylate to polylactic acid according to the present invention ((a) pure polylactic acid of Comparative Example 2, (b) modified polylactic acid of Example 19, ( c) modified polylactic acid of Example 20, (d) modified polylactic acid of Example 21, (e) modified polylactic acid of Example 22)

9 is a view showing a molecule of another embodiment for modifying the polylactic acid according to the present invention

Hereinafter, preferred embodiments of the polylactic acid modifier, polylactic acid modifier manufacturing method, polylactic acid reforming method using the same, biodegradable foam composition using the modified polylactic acid and shoe foam using the biodegradable foam composition is attached. It will be described in detail with reference to the drawings.

The constitution of the polylactic acid reforming method according to the present invention is characterized in that the polylactic acid (Poly Lactic Acid) is modified using polyethylene glycol maleate (Poly Ethylene Glycol Maleate).

First, polylactic acid is a polyester synthesized by polycondensation of lactic acid or ring-opening polymerization of lactide, and the intermediate of polyamide and polyethylene terephthalate (PET). It has physical properties and is mainly composed of natural vegetable sugar components obtained from potatoes and corn, which have high biodegradability but generally have high hardness, low elasticity, and poor durability.

The polymer can be synthesized in the form of poly-L-lactic acid, poly-D-lactic acid and poly-DL-lactic acid, depending on the steric structure of the monomer used in the synthesis. Among them, poly-L-lactic acid (PLLA) synthesized using pure L-lactic acid or L-lactide is called crystalline polylactic acid because of its crystallinity, and mixed with D-lactic acid or D-lactide The prepared poly-DL-lactic acid is prepared as amorphous polylactic acid (PDLA).

When the polylactic acid is heated in a state in which polyethylene glycol maleate and a thermal initiator are included, as shown in FIG. 1, the initiator thermally decomposes to form a radical, and the radical forms hydrogen of the carbon to which the methyl group of the polylactic acid is bonded. It is taken away to form radicals on the polylactic acid chain.

A radical polymerization reaction by polyethylene glycol maleate occurs in the radical on the polylactic acid to produce a modified polylactic acid in which branched chains formed by monomers are formed on the polylactic acid chain.

At this time, when changing the amount of the double bond molecule added, it is possible to control the physical properties of the modified polylactic acid and to control the reaction temperature and reaction rate according to the type and amount of the initiator.

The polylactic acid is due to the branches of the polyethylene glycol maleate, as shown in Figure 1, the tensile strength is lowered, the elastic modulus is lowered, the elongation is increased.

The polyethylene glycol maleate may be any material as long as it has a maleate group and can cause grafting coplolymerization to the polylactic acid.

Specifically, for example, any material may be applied as long as the material has the following formula (1).

[ Formula 1]

(R ₁ and R ₂ are composed of one of the following Chemical Formulas 2 to 7)

[Formula 2]

(In Formula 2, R ₃ is hydrogen or methyl group, R ₄ is hydrogen or alkyl group of C ₁ to C ₈ , n is 1 to 20)

[Formula 3]

(In Formula 3, R ₅ is hydrogen or an alkyl group of C ₁ to C ₈ , n is 1 to 20)

[Formula 4]

(In Formula 4, R ₆ is hydrogen or an alkyl group of C ₁ to C ₈ , l + m + n is 3 to 20)

[Formula 5]

(In Formula 5, R ₇ and R ₈ are hydrogen or an alkyl group having ₁ to C ₈ , and l + m + n is 3 to 20.)

[Formula 6]

(In Formula 6, R ₉ and R ₁₀ are hydrogen or a methyl group, R ₁₁ is hydrogen or an alkyl group of C ₁ to C ₈ , m + n is 2 to 20)

[Formula 7]

(In formula 7, R ₁₂ and R ₁₃ are hydrogen or a methyl group, R ₁₄ is hydrogen or an alkyl group having ₁ to ₈ , 1 + m is 2 to 20, n is 1 to 5)

In addition, an initiator may be further added and reacted during the polymerization. The initiator is an azo compound containing an azo group (-N = N-), an organic peroxide containing a peroxide group (-OO-), hydroperoxide (-COOH), persulfate-based (S ₂ O ₈ ^-2) ), Which may be an organometallic compound, specifically 2,2 azobis (2,4-dimethylvaleronitrile), 2,2-azobisisotropyronitrile, 2,2-azodi (2-methylbutyronitrile ), 1,1-azobis (cyanacyclohexane), dimethyl-2,2-azobis (2-methylpropionate), 1-((cyano-1-methylethyl) azo) formamide, 2,5-bis (tertbutylperoxy) -2,5-dimethyl-3-hexene, ditertbutyl peroxide, 2,5-bis (tertbutylperoxy) -2,5-dimethyl-hexene, dibenzoyl Peroxide, bis (tertbutylperoxyisopropyl) benzene, butyl 4,4-bis (tertbutylperoxy) valerate, 1,1-bis (tertbutylperoxy) 3,3,5-trimethylchlorohexane, Tert-butyl peroxy benzoate, lauryl peroxide, dicumyl peroxide, DE peroxide, potassium persulfate, are ethyl, propyl, the butyl may be characterized in that the use of one or more of the.

Next, the method for synthesizing the modifier of Formula 1, which is polyethylene glycol maleate, will be described in detail.

The mechanism for synthesizing polyethylene glycol maleate, the modifier of the present invention is as shown in FIG. Any one of polyethylene glycol monool, polyethylene glycol diol, and polyethylene glycol triol may be mixed with maleic anhydride and then heated to esterify to produce a modifier of Chemical Formula 1, which is the modifier of the present invention.

More specifically, in the present invention, experiments using polyethylene glycol maleate as a modifier are described. First, the experimental details of the synthesis of various polyethylene glycol maleates will be described in detail as in Examples 1 to 6. .

Example 1

A 500 ml sand dune flask is equipped with a stirrer, thermometer, inert gas, suction tube and condenser for condensation reaction. 98 g of maleic anhydride and 124 g of ethylene glycol are added to the flask, followed by stirring while passing nitrogen gas at a flow rate of 100 ml / min. After slowly raising the temperature to 160 ° C. over about 1 hour, the amount of water produced for the condensation reaction at 160 ° C. was obtained about 36 ml, and the temperature was maintained until the reaction was completed. Ethylene glycol maleate (MEGMA) with a light amber viscosity was obtained after completion | finish of reaction.

Example 2

A 500 ml sand dune flask is equipped with a stirrer, thermometer, inert gas, suction tube and condenser for condensation reaction. 49 g of maleic anhydride and 150 g of triethylene glycol were added to the flask, and the mixture was stirred while passing nitrogen gas at a flow rate of 100 ml / min, and gradually heated. After slowly raising the temperature to 160 ° C. over about 1 hour, the amount of water produced for the condensation reaction at 160 ° C. was obtained about 36 ml, and the temperature was maintained until the reaction was completed. Triethylene glycol maleate (TEGMA) was obtained after completion of the reaction.

Example 3

A 500 ml sand dune flask is equipped with a stirrer, thermometer, inert gas, suction tube and condenser for condensation reaction. 24.5 g of maleic anhydride and 200 g of polyethylene glycol (molecular weight 400) were added to the flask, and the mixture was stirred while passing nitrogen gas at a flow rate of 100 ml / min, and gradually heated. After slowly raising the temperature to 160 ° C. over about 1 hour, the amount of water produced for the condensation reaction at 160 ° C. was obtained about 36 ml, and the temperature was maintained until the reaction was completed. After the reaction was completed, polyethylene glycol maleate (PEG400MA) was obtained.

Example 4

A 500 ml sand dune flask is equipped with a stirrer, thermometer, inert gas, suction tube and condenser for condensation reaction. 12.25 g of maleic anhydride and 250 g of polyethylene glycol (molecular weight 1000) are added to the flask, and the mixture is stirred while passing nitrogen gas at a flow rate of 100 ml / min and gradually heating. After slowly raising the temperature to 160 ° C. over about 1 hour, the amount of water produced for the condensation reaction at 160 ° C. was obtained about 36 ml, and the temperature was maintained until the reaction was completed. After the reaction was completed, polyethylene glycol maleate (PEG1000MA) was obtained.

Example 5

A 500 ml sand dune flask is equipped with a stirrer, thermometer, inert gas, suction tube and condenser for condensation reaction. 49 g of maleic anhydride and 192 g of tripropylene glycol were added to the flask, followed by stirring while passing nitrogen gas at a flow rate of 100 ml / min. After slowly raising the temperature to 160 ° C. over about 1 hour, the amount of water produced for the condensation reaction at 160 ° C. was obtained about 36 ml, and the temperature was maintained until the reaction was completed. Tripropylene glycol maleate (TPGMA) was obtained after completion | finish of reaction.

Example 6

A 500 ml sand dune flask is equipped with a stirrer, thermometer, inert gas, suction tube and condenser for condensation reaction. 24.5 g of maleic anhydride and 200 g of polyethylene glycol monomethyl ether (molecular weight 400) are added to the flask, and the mixture is heated while stirring while flowing nitrogen gas at a flow rate of 100 ml / min. After slowly raising the temperature to 160 ° C. over about 1 hour, the amount of water produced for the condensation reaction at 160 ° C. was obtained about 36 ml, and the temperature was maintained until the reaction was completed. Polyethylene glycol monomethyl ether maleate (MPEG400MA) was obtained after completion | finish of reaction.

Next, the polyethylene glycol malate prepared by the method of Examples 1 to 6 described above was blended with polylactic acid to prepare modified polylactic acid as in Examples 7 to 12, which was followed. It demonstrates in detail.

Example 7

80 parts by weight of polylactic acid (PLA) is melted by heating at 180 ° C. in a kneader, which is a compound kneader, and then kneaded for 5 minutes after adding 20 parts by weight of ethylene glycol maleate (EGMA) of Example 1. Thereafter, 0.8 parts by weight of dicumyl peroxide (DCP), which is an initiator, was further added, followed by reactive blending at 180 ° C. for 10 minutes to prepare modified polylactic acid (PL-EGMA).

Example 8

80 parts by weight of polylactic acid (PLA) is melted by heating at 180 ° C. in a kneader, which is a compound kneader, and then kneaded for 5 minutes after adding 20 parts by weight of triethylene glycol maleate (TEGMA) of Example 2. Thereafter, 0.8 parts by weight of dicumyl peroxide (DCP), which is an initiator, was further added, followed by reactive blending at 180 ° C. for 10 minutes to prepare modified polylactic acid (PL-TEGMA).

Example 9

80 parts by weight of polylactic acid (PLA) was melted by heating at 180 ° C. in a kneader, which is a compound kneader, and then kneaded for 5 minutes after 20 parts by weight of polyethylene glycol maleate (PEG400MA) of Example 3. Thereafter, 0.8 parts by weight of dicumyl peroxide (DCP), which is an initiator, was further added, followed by reactive blending at 180 ° C. for 10 minutes to prepare modified polylactic acid (PL-PEG400MA).

Example 10

80 parts by weight of polylactic acid (PLA) is heated and melted at 180 ° C. in a kneader, which is a compound kneader, and then 20 parts by weight of polyethylene glycol maleate (PEG1000MA) of Example 4 is added and kneaded for 5 minutes. Thereafter, 0.8 parts by weight of dicumyl peroxide (DCP), which is an initiator, was further added, followed by reactive blending at 180 ° C. for 10 minutes to prepare modified polylactic acid (PL-PEG1000MA).

Example 11

80 parts by weight of polylactic acid (PLA) is heated and melted at 180 ° C. in a kneader, which is a compound kneader, and then 20 parts by weight of tripropylene glycol maleate (TPGMA) of Example 5 is added and kneaded for 5 minutes. Thereafter, 0.8 parts by weight of dicumylperoxide (DCP), which is an initiator, was further added, followed by reactive blending at 180 ° C. for 10 minutes to prepare modified polylactic acid (PL-TPGMA).

Example 12

80 parts by weight of polylactic acid (PLA) is melted by heating at 180 ° C. in a kneader, which is a compound kneader, and then kneaded for 5 minutes after adding 20 parts by weight of polyethylene glycol monomethyl ether maleate (MPEG400MA) of Example 6. Thereafter, 0.8 parts by weight of dicumylperoxide (DCP), which is an initiator, was further added, followed by reactive blending at 180 ° C. for 10 minutes to prepare modified polylactic acid (PL-MPEG400MA).

Then, a method for producing a biodegradable foam composition using the modified polylactic acid according to the present invention will be described.

As shown in Table 3, the biodegradable foam compositions may comprise polylactic acid (PLA), modified polylactic acid (PLEA), mixed substrates, crosslinking initiators and blowing agents.

The modified polylactic acid may be modified crystalline polylactic acid (PLLEA) or modified amorphous polylactic acid (PDLEA).

The mixed base may be an ethylene vinyl acetate copolymer (EVA, Ethylene-Vinyl Acetate copolymer), styrene isoprene styrene copolymer (SIS, Styrene-Isoprene Styrene copolymer) or ethylene methacrylate copolymer (EMA, Ethylene-Methacrylate copolymer) It may be used, which is a resin that is widely used as a foam because of excellent compressive strain, impact absorption, mechanical strength and the like.

The crosslinking initiator may be an organic peroxide crosslinking initiator. For example, 2,5-bis (tertbutyl peroxy) -2,5-dimethyl-3-hexene, ditertbutyl peroxide, 2,5-bis (tertbutyl peroxy) -2,5-dimethyl- Hexene, dibenzoyl peroxide, bis (tertbutylperoxyisopropyl) benzene, butyl 4,4-bis (tertbutylperoxy) valerate, 1,1-bis (tertbutylperoxy) 3,3,5- Trimethylchlorohexane, tertbutyl peroxybenzoate, lauryl peroxide, dicumyl peroxide can be used.

The blowing agent may be used alone or in combination with an azodicarbonamide blowing agent or a dinitrosopentamethylenetetraamine blowing agent. For example, Kumyang Chemical's JTR series may be used.

Hereinafter, the characteristics of Comparative Example 1 and Examples 13 to 18 will be described in detail by varying compositions.

Table 1

division	Example 13	Example 14	Example 15	Example 16	Example 17	Example 18	Comparative Example 1
PLA 1)							30
PL-EGMA 2)	30
PL-TEGMA 3)		30
PL-PEG400MA 4)			30
PL-PEG1000MA 5)				30
PL-TPGMA 6)					30
PL-MPEG400MA 7)						30
EVA 8)	70	70	70	70	70	70	70
DCP 9)	0.7	0.7	0.7	0.7	0.7	0.7	0.7
JTR 10)	3.3	3.3	3.3	3.3	3.3	3.3	3.3

1) poly (L-lactic acid), 2) modified crystalline polylactic acid prepared from Example 7, 3) modified crystalline polylactic acid prepared from Example 8, 4) modified crystalline polyl made from Example 9 Lactic acid, 5) modified crystalline polylactic acid prepared from Example 10, 6) modified crystalline polylactic acid prepared from Example 11, 7) modified crystalline polylactic acid prepared from Example 12, 8) ethylene-vinyl acetate (Hanhwa Petrochemical, EVA1328), 10) DCP, dicumylperoxide, 9) DOP, dioctylphthalate, 10) JTR, Geumyang

Comparative Example 1

In Comparative Example 1, 30 parts by weight of polylactic acid (PLA) and 70 parts by weight of ethylene vinyl acetate (EVA) were kneaded at 180 degrees for 5 minutes using a compound kneader, kneader, to prepare a compound. Then, in a roll mill, 0.7 parts by weight of crosslinking initiator and 3.3 parts by weight of blowing agent are added to 100 parts by weight of the compound, and then uniformly mixed to prepare a 4 mm sheet-like compound. Thereafter, the sheet-like compound was introduced into a mold and then molded for about 20 minutes under a press condition of 170 degrees and 150 kg / cm ² to prepare a foam.

Example 13

Example 13 kneaded at 180 degrees for 5 minutes using a compound kneader kneader compound 30 parts by weight of polylactic acid (PL-EGMA) modified by Example 7 and 70 parts by weight of ethylene vinyl acetate (EVA) compound Was prepared. Then, in a roll mill, 0.7 parts by weight of crosslinking initiator and 3.3 parts by weight of blowing agent are added to 100 parts by weight of the compound, and then uniformly mixed to prepare a 4 mm sheet-like compound. Thereafter, the sheet-like compound was introduced into a mold and then molded for about 20 minutes under a press condition of 170 degrees and 150 kg / cm ² to prepare a foam.

Example 14

Example 14 kneaded at 180 degrees for 5 minutes using a compound kneader kneader compound 30 parts by weight of polylactic acid (PL-TEGMA) modified by Example 8, 70 parts by weight of ethylene vinyl acetate (EVA) compound Was prepared. Then, in a roll mill, 0.7 parts by weight of crosslinking initiator and 3.3 parts by weight of blowing agent are added to 100 parts by weight of the compound, and then uniformly mixed to prepare a 4 mm sheet-like compound. Thereafter, the sheet-like compound was introduced into a mold and then molded for about 20 minutes under a press condition of 170 degrees and 150 kg / cm ² to prepare a foam.

Example 15

Example 15 kneaded at 180 degrees for 5 minutes using a compound kneader compound kneader 30 parts by weight of polylactic acid (PL-PEG400MA), 70 parts by weight of ethylene vinyl acetate (EVA) modified by Example 9 Was prepared. Then, in a roll mill, 0.7 parts by weight of crosslinking initiator and 3.3 parts by weight of blowing agent are added to 100 parts by weight of the compound, and then uniformly mixed to prepare a 4 mm sheet-like compound. Thereafter, the sheet-like compound was introduced into a mold and then molded for about 20 minutes under a press condition of 170 degrees and 150 kg / cm ² to prepare a foam.

Example 16

Example 16 kneaded at 180 degrees for 5 minutes using a compound kneader kneader compound 30 parts by weight of polylactic acid (PL-PEG1000MA) modified by Example 10, 70 parts by weight of ethylene vinyl acetate (EVA) compound Was prepared. Then, in a roll mill, 0.7 parts by weight of crosslinking initiator and 3.3 parts by weight of blowing agent are added to 100 parts by weight of the compound, and then uniformly mixed to prepare a 4 mm sheet-like compound. Thereafter, the sheet-like compound was introduced into a mold and then molded for about 20 minutes under a press condition of 170 degrees and 150 kg / cm ² to prepare a foam.

Example 17

Example 17 was kneaded at 180 degrees for 5 minutes using a compound kneader compound kneader 30 parts by weight of polylactic acid (PL-TPGMA) modified by Example 11, 70 parts by weight of ethylene vinyl acetate (EVA) compound Was prepared. Then, in a roll mill, 0.7 parts by weight of crosslinking initiator and 3.3 parts by weight of blowing agent are added to 100 parts by weight of the compound, and then uniformly mixed to prepare a 4 mm sheet-like compound. Thereafter, the sheet-like compound was introduced into a mold and then molded for about 20 minutes under a press condition of 170 degrees and 150 kg / cm ² to prepare a foam.

Example 18

Example 18 kneaded at 180 degrees for 5 minutes using a compound kneader compound kneader 30 parts by weight of polylactic acid (PL-MPEG400MA), 70 parts by weight of ethylene vinyl acetate (EVA) modified by Example 11 compound Was prepared. Then, in a roll mill, 0.7 parts by weight of crosslinking initiator and 3.3 parts by weight of blowing agent are added to 100 parts by weight of the compound, and then uniformly mixed to prepare a 4 mm sheet-like compound. Thereafter, the sheet-like compound was introduced into a mold and then molded for about 20 minutes under a press condition of 170 degrees and 150 kg / cm ² to prepare a foam.

Hereinafter, with reference to Table 2, Comparative Examples 1 and 13 to 18 will be described in detail by varying the composition.

TABLE 2

Evaluation item	unit	Example 13	Example 14	Example 15	Example 16	Example 17	Example 18	Comparative Example 1
importance	(g / cm -3 )	0.21	0.22	0.22	0.23	0.22	0.22	0.21
The tensile strength	(kg / cm 2 )	25	26	27	30	25	26	18
Elongation	%	415	420	427	390	410	420	380
Tear strength	(kg / cm)	14.7	15.3	15.6	15.7	14.9	15.2	9.3
Hardness	Type D	52	53	56	61	51	54	64

As shown in Table 2, it can be seen that compared with Comparative Example 1, Examples 13 to 18 have a higher tensile strength, a higher elongation, and a larger elastic force. That is, the modified polylactic acid (PL-EGMA, PL-TEGMA, PL-PEG400MA, PL-PEG1000MA, PL-TPGMA, PL-MPEG400MA) shows soft physical properties, so it can be used as a foam material because of its excellent durability and flexibility. It can be seen that it is modified.

In addition, a plasticizer may be further added during the preparation of the biodegradable foam composition. The plasticizer is a hydroxycarboxylic acid ester-based plasticizer, which may be used alone in tributyl o-acetylcitrate, triethyl oacetylcitrate, and tributyl citrate. Or in combination.

The constitution of the polylactic acid reforming method according to another embodiment of the present invention is to modify the polylactic acid by polymerizing it with a molecule having a double bond.

First, polylactic acid is a polyester synthesized by polycondensation of lactic acid or ring-opening polymerization of lactide, and the intermediate of polyamide and polyethylene terephthalate (PET). It has physical properties and is mainly composed of natural vegetable sugar components obtained from potatoes and corn, which have high biodegradability but generally have high hardness, low elasticity, and poor durability.

The polymer can be synthesized in the form of poly-L-lactic acid, poly-D-lactic acid and poly-DL-lactic acid, depending on the steric structure of the monomer used in the synthesis. Among them, poly-L-lactic acid (PLLA) synthesized using pure L-lactic acid or L-lactide is called crystalline polylactic acid because of its crystallinity, and mixed with D-lactic acid or D-lactide The prepared poly-DL-lactic acid is prepared as amorphous polylactic acid (PDLA).

When the polylactic acid is heated in a state in which a monomer including a double bond and a thermal initiator are included, as shown in FIG. 1, the initiator is pyrolyzed to form a radical, and the radical is formed of a carbon to which a methyl group of the polylactic acid is bonded. The hydrogen is taken away to form radicals on the polylactic acid chain.

A radical polymerization reaction by a monomer having a double bond in the radical on the polylactic acid may occur to produce a modified polylactic acid in which branched chains formed by monomers are formed on the polylactic acid chain.

At this time, when changing the amount of the double bond molecule added, it is possible to control the physical properties of the modified polylactic acid and to control the reaction temperature and reaction rate according to the type and amount of the initiator. The polymerization reaction is carried out dry because no other solvent is used during the reaction.

Due to the branches of the double bond molecule, the polylactic acids have a lower tensile strength, a lower elastic modulus, and a higher elongation as shown in FIG. 6.

Herein, the molecules having the double bond may be applied to any material that can cause grafting coplolymerization to the polylactic acid. For example, acrylate (CH ₂ = CH-CO— ), Methacrylate (CH ₂ = C (CH ₃ ) -CO-), vinyl (Vinyl, CH ₂ = CH- or -CH = CH-), maleate (Maleate, -CO-CH = CH-) CO-), styrene (styrene, CH ₂ = CH (C ₆ H ₅ )), allyl (Allyl, CH ₂ = CH-O-) and the like may include molecules.

In addition, an initiator may be further added and reacted during the polymerization. The initiator is an azo compound containing an azo group (-N = N-), an organic peroxide containing a peroxide group (-OO-), hydroperoxide (-COOH), persulfate-based (S ₂ O ₈ ^-2) ), Which may be an organometallic compound, specifically 2,2 azobis (2,4-dimethylvaleronitrile), 2,2-azobisisotropyronitrile, 2,2-azodi (2-methylbutyronitrile ), 1,1-azobis (cyanacyclohexane), dimethyl-2,2-azobis (2-methylpropionate), 1-((cyano-1-methylethyl) azo) formamide, 2,5-bis (tertbutylperoxy) -2,5-dimethyl-3-hexene, ditertbutyl peroxide, 2,5-bis (tertbutylperoxy) -2,5-dimethyl-hexene, dibenzoyl Peroxide, bis (tertbutylperoxyisopropyl) benzene, butyl 4,4-bis (tertbutylperoxy) valerate, 1,1-bis (tertbutylperoxy) 3,3,5-trimethylchlorohexane, Tert-butyl peroxy benzoate, lauryl peroxide, dicumyl peroxide, DE peroxide, potassium persulfate, are ethyl, propyl, the butyl may be characterized in that the use of one or more of the.

More specifically, in the present invention, the content of the experiment with the composition as shown in Table 3 using polyethylene glycol acrylate (PEGA) containing acrylate will be described in detail.

TABLE 3

division	Comparative Example 2	Comparative Example 3	Comparative Example 4	Example 19	Example 20	Example 21	Example 22	Example 23
PLLA 1)	100	80	90	90	80	70	60
PDLA 2)								80
PEGA 3)		20	10	10	20	30	40	20
DCP 4)				0.8	0.8	0.8	0.8	0.8

1) poly (L-lactic acid), 2) poly (D, L-lactic acid), 3) polyethyleneglycol acrylate, 4) dicumyl peroxide

Comparative Example 2

In order to confirm the change in the physical properties of the polylactic acid, Comparative Example 2 was prepared by 0.1 to 2mm sheet by hot pressing at 180 ℃ 100 parts by weight of pure crystalline polylactic acid (PLLA, Natureworks, 4032D) using a hot press.

Comparative Example 3

In Comparative Example 3, 80 parts by weight of crystalline polylactic acid (PLLA) was melted and heated at 180 ° C. in a kneader compound kneader, and then 20 parts by weight of polyethylene glycol acrylate (PEGA) was added and kneaded for 5 minutes to prepare a simple blending compound. Prepared. The compound thus prepared was thermally compressed at 180 ° C. using a hot press to prepare a sheet of 0.1 to 2 mm.

Comparative Example 4

In Comparative Example 4, 90 parts by weight of crystalline polylactic acid (PLLA) was melted by heating to 180 in a compound kneader kneader, and then 10 parts by weight of polyethylene glycol acrylate (PEGA) was added and kneaded for 5 minutes to prepare a simple blending compound. It was. The compound thus prepared was thermally compressed at 180 using a hot press to prepare a sheet of 0.1 to 2 mm.

Example 19

In Example 19, 90 parts by weight of crystalline polylactic acid (PLLA) was heated and melted at 180 ° C. in a kneader, which is a compound kneader, and 10 parts by weight of polyethylene glycol acrylate (PEGA) was added and kneaded for 5 minutes. Thereafter, 0.8 parts by weight of dicumylperoxide (DCP), which is an initiator, was further added, followed by reactive blending at 180 ° C. for 10 minutes to prepare modified polylactic acid. The compound thus prepared was thermally compressed at 180 ° C. using a hot press to prepare a sheet of 0.1 to 2 mm.

Example 20

In Example 20, 80 parts by weight of crystalline polylactic acid (PLLA) was melted by heating at 180 ° C. in a kneader, which is a compound kneader, and then kneaded for 5 minutes after adding 20 parts by weight of polyethylene glycol acrylate (PEGA). Thereafter, 0.8 parts by weight of dicumylperoxide (DCP), which is an initiator, was further added, followed by reactive blending at 180 ° C. for 10 minutes to prepare modified polylactic acid. The compound thus prepared was thermally compressed at 180 ° C. using a hot press to prepare a sheet of 0.1 to 2 mm.

Example 21

In Example 21, 70 parts by weight of crystalline polylactic acid (PLLA) was melted by heating at 180 ° C. in a kneader, which is a compound kneader, and then kneaded for 5 minutes after 30 parts by weight of polyethylene glycol acrylate (PEGA) was added. Thereafter, 0.8 parts by weight of dicumylperoxide (DCP), which is an initiator, was further added, followed by reactive blending at 180 ° C. for 10 minutes to prepare modified polylactic acid. The compound thus prepared was thermally compressed at 180 ° C. using a hot press to prepare a sheet of 0.1 to 2 mm.

Example 22

In Example 22, 60 parts by weight of crystalline polylactic acid (PLLA) was melted by heating at 180 ° C. in a kneader, which is a compound kneader, and then 40 parts by weight of polyethylene glycol acrylate (PEGA) was kneaded for 5 minutes. Thereafter, 0.8 parts by weight of dicumylperoxide (DCP), which is an initiator, was further added, followed by reactive blending at 180 ° C. for 10 minutes to prepare modified polylactic acid. The compound thus prepared was thermally compressed at 180 ° C. using a hot press to prepare a sheet of 0.1 to 2 mm.

Example 23

In Example 23, 80 parts by weight of amorphous polylactic acid (PDLA) was melted by heating to 180 in a compound kneader kneader, and then 40 parts by weight of polyethylene glycol acrylate (PEGA) was kneaded for 5 minutes. Thereafter, 0.8 parts by weight of dicumylperoxide (DCP), which is an initiator, was further added, followed by reactive blending for 180 minutes to prepare modified polylactic acid. The compound thus prepared was thermally compressed at 180 using a hot press to prepare a sheet of 0.1 to 2 mm.

Comparative Examples 2 to 4 and Examples 19 to 23 as described above were subjected to structural analysis, solvent extraction, thermomechanical analysis, tensile property analysis, and biodegradation property analysis, respectively.

1. Structural Analysis

Structural analysis was performed to determine whether polylactic acid (PLA) was modified with polyethylene glycol acrylate (PEGA) using nuclear magnetic resonance spectroscopy (NMR) and Fourier transform infrared spectroscopy (FTIR) for structural analysis of modified polylactic acid (PLA). The presence or absence of the result was obtained as shown in FIGS. 4 and 5.

As shown in FIG. 4, in the case of polylactic acid (B) modified by a reactive blend of polylactic acid, a peak due to a methylene structure of polyethylene glycol acrylate (PEGA) is newly generated at 3.6 ppm. It can be seen that the modified by acrylate after the polylactic acid (PLA) reactive blend.

In addition, as shown in Figure 5, (a) polylactic acid (PLA), (b) polylactic acid (PLA) / polyethylene glycol acrylate (PEGA) in the case of a simple blend of polyethylene acrylate from the newly appeared peak at 2900 cm ^-1 It can be seen that the C = C double bond peak found near 1640 cm ⁻¹ of the simple blend (b) disappears from the reactive blend (c), and thus the double bond of the acrylate monomer is polymerized by the lycal reaction. Can be confirmed.

2. Solvent Extraction

Solvent extraction is carried out using polylactic acid (SLA) using soxhlet method using polylactic acid (PLA), modified polylactic acid (PLEA) and polylactic acid (PLA) / polyethylene glycol acrylate (PEGA) simple blend. The amount of acrylate unbound in PLA) was confirmed.

As shown in FIG. 6, in the case of polylactic acid (Example 19, Example 20) modified by a reactive blend of polylactic acid (PLA) and polyethylene glycol acrylate (PEGA) (Comparative Example 4, comparison) Compared with Example 3), the modification was effectively performed because the amount of the solvent dissolved and extracted by the solvent was very small.

3. Thermal Characteristic Analysis

Thermal characteristics analysis, differential scanning calorimetry (DSC, differential scanning calorimetry) was used to analyze the thermal properties of the modified polylactic acid (PLEA) from 0 ℃ to 200 ℃, the glass transition temperature was measured.

As shown in FIG. 7, the glass transition temperature is falling as more polyethylene glycol acrylate (PEGA) is added, and in the case of modified polylactic acid (PLEA) as compared to pure polylactic acid (PLA), the glass transition phenomenon is clear. It is not clearly distinguished and appears in a wide range. This result shows that the acrylate grafted to polylactic acid (PLA) weakens the rigidity of the polylactic acid (PLA) chain so that the modified polylactic acid has soft physical properties at room temperature.

4. Tensile Characteristic Analysis

Tensile properties were analyzed by using a universal testing machine (UTM) to measure the tensile strength, modulus and elongation of the modified polylactic acid.

Table 4

Evaluation item	unit	Comparative Example 2	Example 19	Example 20	Example 21	Example 22	Example 23
The tensile strength	MPa	51	49	37	28	14	35
Modulus of elasticity	MPa	1290	1070	880	690	440	760
Elongation	%	4.6	6.1	9.5	10.8	17.8	11.3

As shown in Table 4, compared to pure polylactic acid, the modified polylactic acid shows a small tensile strength and elastic modulus, and it can be seen that the elongation is increased, and this tendency increases as the amount of added polyethylene glycol acrylate is increased. It can be seen that the increase. From this result, it can be seen that the modified polylactic acid shows soft and flexible physical properties compared to pure polylactic acid.

5. Biodegradation Characterization

Biodegradation characterization was performed by measuring modified polylactic acid (PLEA) having a thickness of 0.1 mm and a size of 2 * 2 cm in a NaHCO ₃ / NaOH buffer solution having a pH of 10.7 to measure the degradation rate in the aqueous base solution.

As shown in FIG. 7, it can be seen that the biodegradability of the modified polylactic acid (PLEA) is superior to pure polylactic acid (PLA) as a result of measurement of biodegradability in an aqueous solution of pH 10.7. The more PEGA), the better the biodegradation.

Then, a method for producing a biodegradable foam composition using the modified polylactic acid according to the present invention will be described.

As shown in Table 5, the biodegradable foam compositions may comprise polylactic acid (PLA), modified polylactic acid (PLEA), mixed substrates, crosslinking initiators and blowing agents.

The modified polylactic acid may be modified crystalline polylactic acid (PLLEA) or modified amorphous polylactic acid (PDLEA).

The mixed base may be an ethylene vinyl acetate copolymer (EVA, Ethylene-Vinyl Acetate copolymer), styrene isoprene styrene copolymer (SIS, Styrene-Isoprene Styrene copolymer) or ethylene methacrylate copolymer (EMA, Ethylene-Methacrylate copolymer) It may be used, which is a resin that is widely used as a foam because of excellent compressive strain, impact absorption, mechanical strength and the like.

The crosslinking initiator may be an organic peroxide crosslinking initiator. For example, 2,5-bis (tertbutyl peroxy) -2,5-dimethyl-3-hexene, ditertbutyl peroxide, 2,5-bis (tertbutyl peroxy) -2,5-dimethyl- Hexene, dibenzoyl peroxide, bis (tertbutylperoxyisopropyl) benzene, butyl 4,4-bis (tertbutylperoxy) valerate, 1,1-bis (tertbutylperoxy) 3,3,5- Trimethylchlorohexane, tertbutyl peroxybenzoate, lauryl peroxide, dicumyl peroxide can be used.

The blowing agent may be used alone or in combination with an azodicarbonamide blowing agent or a dinitrosopentamethylenetetraamine blowing agent. For example, Kumyang Chemical's JTR series may be used.

Hereinafter, with reference to Table 5, Comparative Examples 4 and 6 to 11 will be described in detail by comparing the characteristics of the compositions.

Table 5

division	Comparative Example 5	Example 24	Example 25	Example 26	Example 27	Example 28	Example 29
PLLA 1)	30
PLLEA20 2)		10	20	30	50	70
PDLEA20 3)							30
EVA 4)	70	90	80	70	50	30	70
Crosslinking initiator 5)	0.7	0.7	0.7	0.7	0.7	0.7	0.7
Blowing agent 6)	4.5	4.5	4.5	4.5	4.5	4.5	4.5

1) poly (L-lactic acid), 2) modified crystalline polylactic acid prepared from Example 2, 3) modified amorphous polylactic acid prepared from Example 5, 4) ethylene-vinyl acetate (Hanhwa Petrochemical, EVA1328) 5) DCP, dicumylperoxide, 6) DOP, dioctylphthalate, 7) JTR, Geumyang

Comparative Example 5

In Comparative Example 5, 30 parts by weight of crystalline polylactic acid (PLLA) and 70 parts by weight of ethylene vinyl acetate (EVA) were kneaded at 180 degrees for 5 minutes using a compound kneader, kneader, to prepare a compound. Then, in a roll mill, 0.7 parts by weight of crosslinking initiator and 4.5 parts by weight of blowing agent are added to 100 parts by weight of the compound, and then uniformly mixed to prepare a 4 mm sheet-like compound. Thereafter, the sheet-like compound was introduced into a mold and then molded for about 20 minutes under a press condition of 170 degrees and 150 kg / cm ² to prepare a foam.

Example 24

In Example 24, 10 parts by weight of modified crystalline polylactic acid (PLLEA20) and 90 parts by weight of ethylene vinyl acetate (EVA) were kneaded at 180 degrees for 5 minutes using a compound kneader, kneader, to prepare a compound. Then, in a roll mill, 0.7 parts by weight of crosslinking initiator and 4.5 parts by weight of blowing agent are added to 100 parts by weight of the compound, and then uniformly mixed to prepare a 4 mm sheet-like compound. Thereafter, the sheet-like compound was introduced into a mold and then molded for about 20 minutes under a press condition of 170 degrees and 150 kg / cm ² to prepare a foam.

Example 25

In Example 25, 20 parts by weight of modified crystalline polylactic acid (PLLEA20) and 80 parts by weight of ethylene vinyl acetate (EVA) were kneaded at 180 degrees for 5 minutes using a compound kneader, kneader, to prepare a compound. Then, in a roll mill, 0.7 parts by weight of crosslinking initiator and 4.5 parts by weight of blowing agent are added to 100 parts by weight of the compound, and then uniformly mixed to prepare a 4 mm sheet-like compound. Thereafter, the sheet-like compound was introduced into a mold and then molded for about 20 minutes under a press condition of 170 degrees and 150 kg / cm ² to prepare a foam.

Example 26

In Example 26, 30 parts by weight of modified crystalline polylactic acid (PLLEA20) and 70 parts by weight of ethylene vinyl acetate (EVA) were kneaded at 180 degrees for 5 minutes using a compound kneader, kneader, to prepare a compound. Then, in a roll mill, 0.7 parts by weight of crosslinking initiator and 4.5 parts by weight of blowing agent are added to 100 parts by weight of the compound, and then uniformly mixed to prepare a 4 mm sheet-like compound. Thereafter, the sheet-like compound was introduced into a mold and then molded for about 20 minutes under a press condition of 170 degrees and 150 kg / cm ² to prepare a foam.

Example 27

In Example 27, 50 parts by weight of modified crystalline polylactic acid (PLLEA20) and 50 parts by weight of ethylene vinyl acetate (EVA) were kneaded at 180 degrees for 5 minutes using a compound kneader, kneader, to prepare a compound. Then, in a roll mill, 0.7 parts by weight of crosslinking initiator and 4.5 parts by weight of blowing agent are added to 100 parts by weight of the compound, and then uniformly mixed to prepare a 4 mm sheet-like compound. Thereafter, the sheet-like compound was introduced into a mold and then molded for about 20 minutes under a press condition of 170 degrees and 150 kg / cm ² to prepare a foam.

Example 28

In Example 28, 70 parts by weight of modified crystalline polylactic acid (PLLEA20) and 30 parts by weight of ethylene vinyl acetate (EVA) were kneaded at 180 degrees for 5 minutes using a compound kneader, kneader, to prepare a compound. Then, in a roll mill, 0.7 parts by weight of crosslinking initiator and 4.5 parts by weight of blowing agent are added to 100 parts by weight of the compound, and then uniformly mixed to prepare a 4 mm sheet-like compound. Thereafter, the sheet-like compound was introduced into a mold and then molded for about 20 minutes under a press condition of 170 degrees and 150 kg / cm ² to prepare a foam.

Example 29

In Example 29, 30 parts by weight of modified amorphous polylactic acid (PDLEA20) and 70 parts by weight of ethylene vinyl acetate (EVA) were kneaded at 180 degrees for 5 minutes using a compound kneader, kneader, to prepare a compound. Then, in a roll mill, 0.7 parts by weight of crosslinking initiator and 4.5 parts by weight of blowing agent are added to 100 parts by weight of the compound, and then uniformly mixed to prepare a 4 mm sheet-like compound. Thereafter, the sheet-like compound was introduced into a mold and then molded for about 20 minutes under a press condition of 170 degrees and 150 kg / cm ² to prepare a foam.

Table 6

Evaluation item	unit	Comparative Example 5	Example 24	Example 25	Example 26	Example 27	Example 28	Example 29
importance	g / cm 3	0.21	0.20	0.20	0.21	0.21	0.22	0.20
The tensile strength	kg / cm 2	18	19	24	24	23	20	24
Elongation	%	380	470	450	440	420	380	460
Tear strength	kg / cm	9.3	8.7	11.7	14.2	12.6	9.4	13.8
Elasticity	%	36	38	38	38	37	37	38

As shown in Table 6, compared with Comparative Example 5, Examples 24 to 29 can be seen that the tensile strength is high, the elongation is increased, the elastic force is also large. That is, since the modified polylactic acid shows soft physical properties, it can be seen that it is modified to be used as a foam material because of its excellent durability and flexibility.

In another embodiment of the present invention, a method for preparing a biodegradable foam composition using polylactic acid (PLVA, PLEM, PLAU) modified with other double bond components will be described.

TABLE 7

division	Example 30	Example 31	Example 32
PLVA20 1)	30
PLEM20 2)		30
PLVU2 03)			30
EVA 4)	70	70	70
Crosslinking initiator 5)	0.7	0.7	0.7
Blowing agent 6)	4.5	4.5	4.5

1) crystalline polylactic acid modified with vinyl acetate, 2) crystalline polylactic acid modified with polyethylene glycol maleate, 3) polylactic acid modified with allylpolyurethane, 4) ethylene-vinyl acetate (Hanhwa Petrochemical, EVA1328), 5 ) DCP, dicumylperoxide, 6) DOP, dioctylphthalate, JTR, Geumyang

As shown in Table 7, it may comprise a modified polylactic acid (PLVA, PLEM, PLAU), mixed base, crosslinking initiator and blowing agent.

The composition of the polylactic acid reforming method according to the present invention is modified by polymerizing polylactic acid (Poly Lactic Acid) with vinyl acetate, polyvinyl glycol maleate or allyl polyurethane. It is.

The polylactic acid was prepared in the same manner as in Example 20 except that vinyl acetate, polyethylene glycol maleate or allyl polyurethane was used instead of the polyethylene glycol acrylate used in Example 2.

Example 30

In Example 30, 30 parts by weight of crystalline polylactic acid (PLVA20) modified with vinyl acetate and 70 parts by weight of ethylene vinyl acetate (EVA) were kneaded at 180 degrees using a kneader, which is a compound kneader, to prepare a compound. . Then, in a roll mill, 0.7 parts by weight of crosslinking initiator and 4.5 parts by weight of blowing agent are added to 100 parts by weight of the compound, and then uniformly mixed to prepare a 4 mm sheet-like compound. Thereafter, the sheet-like compound was introduced into a mold and then molded for about 20 minutes under a press condition of 170 degrees and 150 kg / cm ² to prepare a foam.

Example 31

In Example 31, 30 parts by weight of crystalline polylactic acid (PLEM20) modified with polyethylene glycol maleate and 70 parts by weight of ethylene vinyl acetate (EVA) were kneaded at 180 degrees using a kneader, which is a compound kneader, for 5 minutes. Prepared. Then, in a roll mill, 0.7 parts by weight of crosslinking initiator and 4.5 parts by weight of blowing agent are added to 100 parts by weight of the compound, and then uniformly mixed to prepare a 4 mm sheet-like compound. Thereafter, the sheet-like compound was introduced into a mold and then molded for about 20 minutes under a press condition of 170 degrees and 150 kg / cm ² to prepare a foam.

Example 32

In Example 32, 30 parts by weight of crystalline polylactic acid (PLAU20) modified with allyl polyurethane and 70 parts by weight of ethylene vinyl acetate (EVA) were kneaded at 180 degrees for 5 minutes using a compound kneader, kneader, to prepare a compound. It was. Then, in a roll mill, 0.7 parts by weight of crosslinking initiator and 4.5 parts by weight of blowing agent are added to 100 parts by weight of the compound, and then uniformly mixed to prepare a 4 mm sheet-like compound. Thereafter, the sheet-like compound was introduced into a mold and then molded for about 20 minutes under a press condition of 170 degrees and 150 kg / cm ² to prepare a foam.

Hereinafter, with reference to Table 8, the characteristics of Example 12, Example 13, and Example 14, which are different from each other, will be described in detail.

Table 8

Evaluation item	unit	Comparative Example 30	Example 31	Example 32
importance	g / cm 3	0.22	0.20	0.20
The tensile strength	kg / cm 2	26	22	23
Elongation	%	420	460	450
Tear strength	kg / cm	15.3	13.2	13.6
Elasticity	%	39	35	38

As shown in Table 8, compared with Comparative Example 5, Examples 30 to 32 can be seen that the tensile strength is high, the elongation is increased, the elastic force is also large. That is, since the modified polylactic acid (PLVA20, PLEM20, PLAU20) shows a soft physical properties, it can be seen that it is modified to be used as a foam material with excellent durability and flexibility.

In addition, a plasticizer may be further added during the preparation of the biodegradable foam composition. The plasticizer is a hydroxycarboxylic acid ester-based plasticizer, which may be used alone in tributyl o-acetylcitrate, triethyl oacetylcitrate, and tributyl citrate. Or in combination.

The rights of the present invention are not limited to the embodiments described above, but are defined by the claims, and those skilled in the art can make various modifications and adaptations within the scope of the claims. It is self-evident.

In the present invention, a polylactic acid modifier, a polylactic acid modifier manufacturing method, a polylactic acid reforming method using the same, a biodegradable foam composition using a modified polylactic acid and a shoe foam using a biodegradable foam composition than the use of polylactic acid in tensile strength and It has low elastic modulus, high elongation, soft properties, excellent durability and flexibility, and excellent biodegradability, so it can be used as a foam material for biodegradable shoe midsole.

Claims (22)

1. In modifying polylactic acid using a modifier to polylactic acid,

   Modifier of polylactic acid, characterized in that consisting of the compound of formula (1).

   [ Formula 1]

   

   (R ₁ and R ₂ are composed of one of the following Chemical Formulas 2 to 7)

   [Formula 2]

   

   (In Formula 2, R ₃ is hydrogen or methyl group, R ₄ is hydrogen or alkyl group of C ₁ to C ₈ , n is 1 to 20)

   [Formula 3]

   

   (In Formula 3, R ₅ is hydrogen or an alkyl group of C ₁ to C ₈ , n is 1 to 20)

   [Formula 4]

   

   (In Formula 4, R ₆ is hydrogen or an alkyl group of C ₁ to C ₈ , l + m + n is 3 to 20)

   [Formula 5]

   

   (In Formula 5, R ₇ and R ₈ are hydrogen or an alkyl group having ₁ to C ₈ , and l + m + n is 3 to 20.)

   [Formula 6]

   

   (In Formula 6, R ₉ and R ₁₀ are hydrogen or a methyl group, R ₁₁ is hydrogen or an alkyl group of C ₁ to C ₈ , m + n is 2 to 20)

   [Formula 7]

   

   (In formula 7, R ₁₂ and R ₁₃ are hydrogen or a methyl group, R ₁₄ is hydrogen or an alkyl group having ₁ to ₈ , 1 + m is 2 to 20, n is 1 to 5)
2. In modifying polylactic acid using a modifier to polylactic acid,

   A method for producing a polylactic acid modifier, wherein any one of polyethylene glycol monool, polyethylene glycol diol, and polyethylene glycol triol and maleic anhydride are formed by an esterification reaction.
3. A method for modifying polylactic acid, characterized in that the polylactic acid is modified using the modifier of claim 1.
4. The method of claim 3, wherein

   The method of reforming polylactic acid, characterized in that the reaction is further added to the initiator during the polymerization.
5. The method of claim 4, wherein

   The initiator,

   2,2 azobis (2,4-dimethylvaleronitrile), 2,2-azobisisobutyronitrile, 2,2-azodi (2-methylbutyronitrile), 1,1-azobis (sia) Nacyclohexane), dimethyl-2,2-azobis (2-methylpropionate), 1-((cyano-1-methylethyl) azo) formamide, 2,5-bis (tertbutylperoxy ) -2,5-dimethyl-3-hexene, ditertbutyl peroxide, 2,5-bis (tertbutylperoxy) -2,5-dimethyl-hexene, dibenzoyl peroxide, bis (tertbutylperoxyiso) Propyl) benzene, butyl 4,4-bis (tertbutylperoxy) valerate, 1,1-bis (tertbutylperoxy) 3,3,5-trimethylchlorohexane, tertbutylperoxybenzoate, lauryl per Process for reforming polylactic acid, characterized in that used as one or more of oxides, dicumyl peroxide.
6. A biodegradable foam composition comprising the modified polylactic acid of claim 3 and a mixed base, and constituted by their foam polymerization.
7. The method of claim 6,

   The mixed substrate,

   A biodegradable foam composition comprising at least one of an ethylene vinyl acetate copolymer, a styrene isoprene styrene copolymer or an ethylene methacrylate copolymer.
8. The method of claim 6,

   Biodegradable foam composition, characterized in that further comprises a cross-linking initiator and a blowing agent during the polymerization.
9. The method of claim 8,

   The crosslinking initiator,

   2,5-bis (tertbutylperoxy) -2,5-dimethyl-3-hexene, ditertbutyl peroxide, 2,5-bis (tertbutylperoxy) -2,5-dimethyl-hexene, dibenzoyl Peroxide, bis (tertbutylperoxyisopropyl) benzene, butyl 4,4-bis (tertbutylperoxy) valerate, 1,1-bis (tertbutylperoxy) 3,3,5-trimethylchlorohexane, A biodegradable foam composition comprising at least one of tertbutyl peroxybenzoate, lauryl peroxide and dicumyl peroxide.
10. The method of claim 8,

    The blowing agent,

    A biodegradable foam composition comprising at least one of an azodicarbonamide blowing agent or a dinitrosopentamethylenetetraamine blowing agent.
11. A foam for footwear comprising the biodegradable foam composition of claim 6.
12. A method of modifying polylactic acid, characterized in that the polylactic acid (Poly Lactic Acid) is polymerized and modified by a molecule having a double bond.
13. The method of claim 12,

    The molecule having the double bond is an acrylate (CH ₂ = CH-CO-), methacrylate (Methacrylate, CH ₂ = C (CH ₃ ) -CO-), vinyl (Vinyl, CH ₂ = CH- Or -CH = CH-), maleate (Maleate, -CO-CH = CH-CO-), styrene (styrene, CH ₂ = CH (C ₆ H ₅ )), allyl (Allyl, CH ₂ = CH-O -) A method for modifying polylactic acid, characterized in that the molecule contains at least one of.
14. The method of claim 12,

    The polymerization reaction,

    A method for reforming polylactic acid, characterized in that the reaction is carried out dry.
15. The method of claim 12,

    The method of reforming polylactic acid, characterized in that the reaction is further added to the initiator during the polymerization.
16. The method of claim 15,

    The initiator,

    2,2 azobis (2,4-dimethylvaleronitrile), 2,2-azobisisobutyronitrile, 2,2-azodi (2-methylbutyronitrile), 1,1-azobis (sia) Nacyclohexane), dimethyl-2,2-azobis (2-methylpropionate), 1-((cyano-1-methylethyl) azo) formamide, 2,5-bis (tertbutylperoxy ) -2,5-dimethyl-3-hexene, ditertbutyl peroxide, 2,5-bis (tertbutylperoxy) -2,5-dimethyl-hexene, dibenzoyl peroxide, bis (tertbutylperoxyiso) Propyl) benzene, butyl 4,4-bis (tertbutylperoxy) valerate, 1,1-bis (tertbutylperoxy) 3,3,5-trimethylchlorohexane, tertbutylperoxybenzoate, lauryl per Process for reforming polylactic acid, characterized in that used as one or more of oxides, dicumyl peroxide.
17. A biodegradable foam composition comprising the modified polylactic acid of claim 12 and a mixed base and constituted by their foam polymerization.
18. The method of claim 17,

    The mixed substrate,

    A biodegradable foam composition comprising at least one of an ethylene vinyl acetate copolymer, a styrene isoprene styrene copolymer or an ethylene methacrylate copolymer.
19. The method of claim 17,

    Biodegradable foam composition, characterized in that further comprises a cross-linking initiator and a blowing agent during the polymerization.
20. The method of claim 19,

    The crosslinking agent,

    2,5-bis (tertbutylperoxy) -2,5-dimethyl-3-hexene, ditertbutyl peroxide, 2,5-bis (tertbutylperoxy) -2,5-dimethyl-hexene, dibenzoyl Peroxide, bis (tertbutylperoxyisopropyl) benzene, butyl 4,4-bis (tertbutylperoxy) valerate, 1,1-bis (tertbutylperoxy) 3,3,5-trimethylchlorohexane, A biodegradable foam composition comprising at least one of tertbutyl peroxybenzoate, lauryl peroxide and dicumyl peroxide.
21. The method of claim 19,

    The blowing agent,

    A biodegradable foam composition comprising at least one of an azodicarbonamide blowing agent or a dinitrosopentamethylenetetraamine blowing agent.
22. A foam for footwear comprising the biodegradable foam composition of claim 17.

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