KR101780794B1 - Expandable-molded polylactide article having heat resistance and biodegradable container using the same - Google Patents
Expandable-molded polylactide article having heat resistance and biodegradable container using the same Download PDFInfo
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- KR101780794B1 KR101780794B1 KR1020150170602A KR20150170602A KR101780794B1 KR 101780794 B1 KR101780794 B1 KR 101780794B1 KR 1020150170602 A KR1020150170602 A KR 1020150170602A KR 20150170602 A KR20150170602 A KR 20150170602A KR 101780794 B1 KR101780794 B1 KR 101780794B1
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- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
- C08L67/04—Polyesters derived from hydroxycarboxylic acids, e.g. lactones
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
- C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
- C08G63/06—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from hydroxycarboxylic acids
- C08G63/08—Lactones or lactides
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- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
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- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
- C08J9/22—After-treatment of expandable particles; Forming foamed products
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- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L101/00—Compositions of unspecified macromolecular compounds
- C08L101/16—Compositions of unspecified macromolecular compounds the macromolecular compounds being biodegradable
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- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G2150/00—Compositions for coatings
- C08G2150/60—Compositions for foaming; Foamed or intumescent coatings
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2201/00—Foams characterised by the foaming process
- C08J2201/02—Foams characterised by the foaming process characterised by mechanical pre- or post-treatments
- C08J2201/03—Extrusion of the foamable blend
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Abstract
The present invention relates to a heat-resistant polylactide-based foam, a process for producing the same, and a biodegradable heat-resistant molded article made therefrom.
The heat-resistant polylactide-based foam of the present invention comprises an extruded foam sheet comprising a polylactide blend composition having controlled thermal properties; Or a multilayer foamed sheet in which a coating resin layer containing a biodegradable polymer resin is laminated on at least one surface of the extruded foamed sheet is heated and preheated under specific conditions to be molded and finished, It is possible to commercialize a biodegradable heat-resistant molded article which maintains its shape stability until elapsed.
Description
The present invention relates to a heat-resistant polylactide foam, a process for producing the same, and a biodegradable heat-resistant molded article comprising the same, and more particularly, to an extruded foam sheet comprising a polylactide blend composition having controlled thermal properties; Or a multilayer foamed sheet in which a coating resin layer containing a biodegradable polymer resin is laminated on at least one surface of the extruded foamed sheet, a heat-resistant polylactide foam having excellent heat resistance and strength formed by heating and preheating under specific conditions, And a biodegradable heat-resistant molded article made therefrom.
Conventionally, foams composed of general-purpose resins such as polyethylene-based resin, polypropylene-based resin and polystyrene-based resin have been widely used for various fields for a long time because of their excellent lightweight property, heat insulating property and buffering property.
However, since the foam composed of the general-purpose resin is mostly decomposed when it is left in a natural environment after use, in recent years, a polylactide resin derived from plants has been attracting attention in place of the general-purpose resin having a petroleum resource as a raw material .
The polylactide resin is a thermoplastic resin that is made from a plant such as corn as a starting material and is an environmental bottom-bottom type decomposed into carbon dioxide and water even if left in a natural environment after use. Therefore, the polylactide resin is expected to be used as a general-purpose resin for foaming originating from environment-friendly plants showing decomposability in a natural environment, and a foam made from polylactide resin as a raw material has been studied as one of them Development of a foamed resin molded article is progressing.
As an example thereof, Japanese Laid-Open Patent Publication No. 2002-322309 discloses a polylactide-based resin foam which is uniformly and finely foamed by extruding and foaming a polylactide resin, and foamed at a high magnification.
However, since the above-mentioned foam contains amorphous polylactide as a main component, there is a problem in that it is excellent in moldability but has a problem in heat resistance and deforms at room temperature.
Therefore, when the crystalline polylactide is contained in the polylactide resin for the purpose of improving the heat resistance, improvement in heat resistance can be expected. On the other hand, there is a problem in foaming property and heat generation property, A foam having a function can not be obtained. Further, in order to improve the heat resistance and productivity, conventionally, a method of crosslinking by adding a (meth) acrylic acid ester compound or a polyvalent isocyanate compound to a biodegradable polyester (Japanese Patent Application Laid-Open No. 2003-128901) or a method in which a biodegradable polyester and a layer silicate (Japanese Patent Application Laid-Open No. 2003-147182) has been proposed.
Japanese Patent Application Laid-Open No. 8-73628 discloses blister sheets and molded articles having excellent transparency, impact resistance, and heat resistance by stretching a polylactide-based sheet in two axes and performing a predetermined orientation There is a bar. It is known to those skilled in the art that in order to carry out a predetermined orientation in the present invention, the polylactide needs to be crystallized, it does not show crystallinity unless the D or L form has a composition occupying most of the D form or L form. / L ratio of 2 to 5/96 to 98 is mainly used as the polylactide. However, in the case of producing the thermoformed body using the polylactide disclosed in the above-mentioned invention, in order to exhibit sufficient impact resistance and heat resistance, it is necessary to increase the thickness of the molded article. However, When thermoforming is carried out by using a sheet, the impact resistance and heat resistance are maintained, but the pressing pressure in the thermoforming becomes larger, which causes problems in the molding processability.
The present inventors have made efforts to improve the physical properties of polylactide and to improve the utilization thereof. As a result, it has been found that the amorphous polylactide is mixed with crystalline polylactide, and the content of amorphous polylactide is compared with that of crystalline polylactide To thereby optimize the polylactide-containing base resin to control the thermal properties of the polylactide blend composition composed of additives for improving physical properties and to heat the extruded foam sheet made of the polylactide blend composition having the controlled thermal properties The present invention has been accomplished by providing a biodegradable foam having improved heat resistance and strength by molding and confirming the shape stability until 10 minutes have elapsed in boiling water.
It is an object of the present invention to provide a heat-resistant polylactide-based foam in which an extruded foam sheet made of a polylactide blend composition having controlled thermal properties is thermoformed.
Another object of the present invention is to provide a process for producing a heat-resistant polylactide-based foam.
It is still another object of the present invention to provide a biodegradable heat-resistant molded article using the heat-resistant polylactide-based foam.
In order to accomplish the above object, the present invention provides a foamed molded foam extruded foam sheet comprising a polylactide blend composition,
Wherein the extruded foam sheet has a heat of fusion (Hm) before molding of 12 to 40 J / g,
In the heating apparatus, the sheet surface temperature was adjusted to 12 Deg.] C for 60 seconds to form a heat-resistant polylactide-based foam having a degree of crystallization (enthalpy change value [Delta] Hm- [Delta] Hc) of 47 to 75 J / g.
The heat-resistant polylactide foam according to the present invention is characterized in that the degree of crystallization (enthalpy change value (DELTA Hm-DELTA Hm) of the foam after molding relative to the degree of crystallization (enthalpy change value (DELTA Hm- DELTA Hc) Hc)) meets the requirement of 3 to 50 J / g higher.
The heat resistant polylactide foam according to the present invention satisfying the above properties is molded from an extruded foam sheet made of a polylactide blend composition, wherein the polylactide blend composition comprises, based on 100 parts by weight of the polylactide-containing base resin, 0.1 to 2.0 parts by weight of a compound and 0.1 to 1.0 part by weight of a peroxide compound, 0.1 to 5 parts by weight of a crystal nucleating agent containing talc, and an adipic acid ester, a lactic acid ester, a glycerin ester and a citric acid ester And 0.1 to 3 parts by weight of any one of the plasticizers.
The present invention also relates to a multilayer foamed article comprising (A) a multilayer foamed article in which a coating resin layer containing (B) a biodegradable polymer resin is laminated on at least one surface of an extruded foamed sheet layer composed of the polylactide blend composition in an extrusion coating type or a lamination type Wherein the multilayer foamed sheet is heated and preheated for 12 to 60 seconds so as to have a sheet surface temperature of 70 to 130 DEG C in a heating device and molded so that a heat resistant polylactic acid having a strength of 10% Tide type foam.
At this time, when the (B) coating resin layer is laminated to a thickness of 10 to 300 탆, heat resistance and strength property are satisfied.
The present invention also relates to a process for producing a polylactide-containing base resin, which comprises adding 0.1 to 2.0 parts by weight of an epoxy compound and 0.1 to 1.0 part by weight of a peroxide compound, 0.1 to 5 parts by weight of a crystal nucleating agent comprising talc, And 0.1 to 3 parts by weight of any one plasticizer selected from the group consisting of adipic acid esters, lactic acid esters, glycerin esters and citric acid esters are extruded and foamed, a process for producing an extruded foam sheet, Is heated and heated in a heating device and inserted into a mold to form a heat-resistant polylactide-based foam.
The method of the present invention is characterized in that the temperature is preheated in the heating apparatus for 12 to 60 seconds so that the surface temperature of the sheet becomes 70 to 130 占 폚.
The mold may be coated or plated with a material selected from the group consisting of molybdenum, titanium, chromium, nickel, silicon, ceramic, diamond and fluorine resin.
At this time, the mold is composed of a cavity mold and a plug mold having a preheating system, the temperature of the cavity mold is 25 to 130 캜, and the temperature of the mold is 60 to 130 캜 .
Further, the present invention provides a biodegradable heat-resistant molded article comprising a heat-resistant polylactide-based foam having improved crystallinity from the above-mentioned production method, wherein the shape stability is maintained until 10 minutes elapse in hot water at 80 to 100 ° C.
The present invention relates to a method for optimizing a polylactide-containing base resin by mixing an amorphous polylactide with a crystalline polylactide, wherein the amount of the amorphous polylactide is less than that of the crystalline polylactide, An extruded foam sheet composed of a polylactide blend composition composed of an additive is heated and preheated under specific conditions to form a finished heat-resistant polylactide foam.
Further, the present invention can provide a foam having improved heat resistance and strength by thermoforming a multilayer foam sheet in which a coating resin layer containing a biodegradable polymer resin is laminated on at least one surface of the extruded foam sheet.
Furthermore, the present invention can commercialize a biodegradable heat-resistant molded article in which the shape stability is maintained until 10 minutes have elapsed in boiling water by using the above heat-resistant polylactide-based foam.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph comparing the thermal properties (b) of the extruded foam sheet prepared from the polylactide blend composition with respect to the thermal property (a) of the polylactide (PLA) chip of the present invention.
Hereinafter, the present invention will be described in detail.
Brief Description of Drawings Fig. 1 is a graph comparing the thermal properties (b) of an extruded foam sheet prepared from a polylactide blend composition with respect to the thermal property (a) of the polylactide (PLA) chip of the present invention. The peak is sharp and large and shows high crystallinity of the polylactide chip. The extruded foam sheet (b) comprising the polylactide blend composition of the present invention exhibits an exothermic peak due to crystallization during the temperature raising process in the differential scanning calorimetry (DSC), and an endothermic peak in which the crystal is thermally melted when the temperature is continuously increased , It is confirmed that the extruded foamed sheet of the present invention can be molded after heating and preheating under specific conditions to produce a heat resistant polylactide heat resistant molded article having excellent heat resistance and strength. (b), the degree of crystallization of the sample is determined based on the enthalpy change value (Hm-Hc).
Accordingly, the present invention provides, as a first preferred embodiment, a foam obtained by molding an extruded foam sheet comprising a polylactide blend composition, wherein the extruded foam sheet has a heat of fusion (Hm) before molding of 12 to 40 J / g, The extruded foamed sheet is heated and preheated for 12 to 60 seconds, more preferably 18 to 36 seconds, so as to have a sheet surface temperature of 70 to 130 占 폚 in the heating apparatus, and the degree of crystallization (enthalpy change value? Hm- Hc)) satisfies the thermal properties of 47 to 75 J / g.
If the degree of crystallization (enthalpy change value? Hm-? Hc) is less than 47 J / g, the heat resistance is poor. On the other hand, if the degree of crystallization exceeds 75 J / g, the degree of crystallization is excessively high, Is difficult to handle.
The heat-resistant polylactide foam according to the present invention is characterized in that the degree of crystallization (enthalpy change value (DELTA Hm-DELTA Hm) of the foam after molding relative to the degree of crystallization (enthalpy change value (DELTA Hm- DELTA Hc) Hc)) meets the requirement of 3 to 50 J / g higher.
The foam having the above-described thermal properties is put into a dryer preliminarily heated to a predetermined temperature and held for 10 minutes. After cooling at room temperature, a foam having a shape and size change of 0.1% or less and a boiling water And the mixture was kept at the temperature for 10 minutes. After the water was discarded and cooled to room temperature, the result of the heat resistance evaluation without the change of the diameter and the height of the foam was satisfied.
The thermal properties of the extruded foamed sheet and the foam produced therefrom are analyzed based on JIS-K-7121, and the crystallinity due to the polylactide resin in the sheet is measured by differential scanning calorimetry (DSC). The heating device is not particularly limited to known heating means such as a far-infrared ray heater and an electric heater, but in the embodiment of the present invention, a far-infrared ray heater is used.
At this time, in order to calculate the degree of crystallization of the polylactide-based resin, the heat of fusion (Hm) and the amount of heat of crystallization (Hc) are measured and calculated by the following formula (1). At this time, the melting enthalpy Hm o of 100% crystals of polylactic acid is 93 J / g [EW Fischer, HJ Sterzel, G. Wegner, Kolloid Z .: Z. Polym., 251, 980 (1973)].
Equation 1
Crystallinity (%) = [(Hm-Hc) / Hm o ] x 100
Accordingly, the present invention optimizes the crystallinity of the polylactide-containing base resin constituting the polylactide blend composition to control the thermal properties of the extruded foam sheet depending on the specific additive and its content.
Specifically, the polylactide blend composition includes a chain extender consisting of 0.1 to 2.0 parts by weight of an epoxy compound and 0.1 to 1.0 part by weight of a peroxide compound, talc, 0.1 to 5 parts by weight of a crystal nucleating agent and 0.1 to 3 parts by weight of any one plasticizer selected from the group consisting of adipic acid esters, lactic acid esters, glycerin esters and citric acid esters.
1) Polylactide-containing base resin
The crystalline polylactide is a polylactide having a high ratio of L-lactide in PDLA and D-lactide in PDLA, that is, a high optical purity, and has high crystallinity and excellent heat resistance and mechanical properties . On the other hand, the amorphous polylactide is a copolymer having a relatively high ratio of L-lactide in PDLA or D-lactide in PLLA, and has low crystallinity and thermal stability and low mechanical properties.
A commercially available polylactide is a copolymer of PLLA / PDLA. When the L content (or D content) is 80% or more in the copolymer, it is a crystalline polylactide because it has a predetermined melting point and crystallinity.
In the present invention, a resin having an L content (or D content) of 90% or more and having a predetermined high melting point and a high crystallinity is referred to as a crystalline polylactide. Out of this range, an amorphous polylactide having no or very low crystallinity .
The polylactide-containing base resin of the present invention is prepared by mixing crystalline polylactide and amorphous polylactide resin in a specific mixing ratio, wherein 55 to 98% by weight of crystalline polylactide, 2 to 45% by weight of amorphous polylactide By weight of the crystalline polylactide-based polymer exhibits the impact resistance and heat resistance of the crystalline polylactide-based polymer, and is imparted with flexibility by the amorphous polylactide-based polymer, so that the foamability of the polylactide- Stability is improved. Particularly, since the content of the amorphous polylactide is less than that of the crystalline polylactide, the bending resistance is improved and the shape change of the molded article due to heat can be minimized.
The crystalline polylactide used in the polylactide-based polymer composition of the present invention may be any of PDLA or PLLA. If the amount of the amorphous polylactide is less than 2% by weight, the effect of the amorphous polylactide-based polymer can not be expected. If the amorphous polylactide is contained in an amount exceeding 45% by weight, As the polymer composition is converted to amorphous nature, it results in a final shape change. More preferably, by blending 2 to 40% by weight, and most preferably 2.5 to 20% by weight, of the amorphous polylactide in the crystalline polylactide, the foaming property of the polylactide resin and the molding stability in the mold, Heat stability of the molded article is imparted.
In addition to the polylactide-containing base resin, modified starch, thermoplastic starch, cellulose and the like may be contained as a polymer that can be modified by blending with polylactide. Poly (3-hydroxybutyrate), Poly (3HB- co- 3HV): Poly (3-hydroxybutyrate- co- 3-hydroxyvalerate), PHBV Poly 3-HB- co -4HB): Poly (3-hydroxybutyrate- co -4-hydroxybutyrate), Poly (3HB- co -3HH): Poly (3-hydroxyoctanoate- co -hydroxyhexanoate), Poly (3HO- co -3HH) : Poly (3-hydroxyoctanoate- co -hydroxyhexanoate), Poly (4-HB): Poly (4-hydroxybutyrate).
2) chain extender
The chain extender contained in the polylactide blend composition of the present invention reacts with the base resin and additive of the composition to increase the viscosity of the melt in the extrusion foaming process. Accordingly, the use of the chain extender improves the melt strength of the extruded foamed sheet, increases the number of cells, and increases the size of the cell.
As a preferred example of the chain extender used in the present invention, there is preferably used a chain extender comprising bisphenol A diglycidyl ether, terephthalic acid diglycidyl ether, trimethylolpropane diglycidyl ether and 1,6-hexanediol diglycidyl ether Epoxy group compounds are preferable, and it is preferable to use epoxy compounds in view of the fact that they are applied to heat-resistant molded articles. When an epoxy chain extender is used, the high melt index of the crystalline polylactide should be lowered to 4 g / 10 min or less and the viscosity of the molten resin should be increased to exhibit excellent sheet formability.
The chain extender used in the present invention is also a peroxide compound. At this time, the peroxide compound makes the cell of the foam sheet denser while the reaction by-product becomes gas phase in the pressure starting depressurization, and at the same time, the cell content increases and the closed cell also increases.
Examples of the peroxide compound include benzoyl peroxide, 1,1-bis-tert-butylperoxy-3,3,5-triethylcyclohexane, 3,3,5-trimethylcyclohexane, Di-t-butyl peroxide, t-Butyl peroxy acetate, t-Butyl peroxy benzoate, t-butyl hydroperoxide, t-butyl peroxy-2-ethyl hexanoate, t-Butyl peroxy-2-ethylhexanoate, peroxy isopropyl carbonate, t-butyl peroxy pivalate, t-butyl peroxy maleic acid, t-butyl peroxy neodecanoate, cumyl peroxyneodecanoate, di-2-ethylhexylperoxy di (2-ethylhexylperoxy di carbonate, di-isopropyl peroxy dicarbonate, di-3-methoxybutyl peroxydicarbonate, di 3,3,5-trimethylhexanoyl peroxide (Di -3,3,5-trimethyl hexanoyl peroxide, cumene hydroperoxide, p-Menthane hydoperoxide, dicumyl peroxide, lauroyl peroxide, ,?,? '-bis (t-butylperoxy) diisopropyl benzene, and methylethylketone peroxide.
The chain extender of the present invention is remarkably effective in improving the heat resistance when 0.1 to 2.0 parts by weight of the epoxy compound and 0.1 to 1.0 part by weight of the peroxide compound are used per 100 parts by weight of the base resin containing polylactide.
3) Crystalline nucleating agent
The crystal nucleating agent contained in the polylactide blend composition of the present invention may be mixed with other raw materials and introduced into the pressure starting furnace, or master batch with PLA polymer or master batch with PLA / aliphatic polyester polymer blend, Or it may be put into a pressure starting depression by extrusion compounding with the entire raw material. In addition, it may be mixed with other additives or put into a master batch, and it can be applied to general processes and machines for polymer processing.
The kind of the crystal nucleating agent used in the present invention is various kinds such as an organic substance and an inorganic substance. Examples of the inorganic substance include talc, calcium carbonate, silica, clay, calcium silicate, mica, kaolin, titanium dioxide; Examples of organic substances include fatty acid metal salts such as zinc stearate and calcium stearate. The crystal nucleating agent can be used in a mixture of one or more kinds. More preferably, talc may be used, and an organic crystal nucleating agent may be mixed with the talc.
The crystal nucleating agent of the present invention is used in an amount of 0.1 to 5 parts by weight, more preferably 0.1 to 2 parts by weight, of a crystal nucleating agent containing talc, based on 100 parts by weight of the base resin containing polylactide. If the content is less than 0.1 parts by weight, the polylactide-containing base resin particles can not be sufficiently foamed. If the amount is more than 5 parts by weight, the resulting expanded particles may be insufficiently inflated and welded at the time of molding.
In addition, a foaming agent is pressed into the extruder together with the polylactide-containing base resin and the foam nucleating agent, and a hydrocarbon such as pentane and butane or a mixture thereof is widely used as the foaming agent. In addition, carbon dioxide, nitrogen, acetone, methyl Formate and the like can be used.
4) Plasticizer
As the plasticizer contained in the polylactide blend composition of the present invention, any plasticizer selected from the group consisting of adipic acid esters, lactic acid esters, glycerin esters and citric acid esters is used. In the embodiment of the present invention, acetyl tributyl citrate (ATBC) is used as a citric acid plasticizer, but the present invention is not limited thereto.
The plasticizer used in the present invention contains 0.1 to 3 parts by weight based on 100 parts by weight of the polylactide-containing base resin. If the content of the plasticizer is less than 0.1 parts by weight, the flexibility of the extruded foamed sheet is insufficient. If the plasticizer content exceeds 3 parts by weight, the foamed sheet is too flexible.
In the polylactide blend composition of the present invention, a filler, an antioxidant, a UV stabilizer, a heat stabilizer, a flame retardant, an antiblocking agent, a slip agent, a lubricant, an antistatic agent, an antimicrobial agent, Can be added throughout the processing.
(B) a coating resin layer containing a biodegradable polymer resin is formed on at least one surface of an extruded foamed sheet layer made of a polylactide blend composition by an extrusion coating type or a lamination type Wherein the multilayer foamed sheet is heated and preheated for 12 to 60 seconds so as to have a sheet surface temperature of 70 to 130 DEG C in a heating apparatus, Thereby providing a reinforced heat-resistant polylactide-based foam.
At this time, the extruded foam sheet composed of the polylactide blend composition constituting the extruded foam sheet layer (A) is the same as that described in the first embodiment.
(B) A coating resin layer containing a biodegradable polymer resin can be used without limitation as long as it is a polymer that is generally certified as a biodegradable polymer. Specific examples thereof include polylactide (PLA), polybutylene adipate (PBA) Co-succinate (PBAS), poly (butylene adipate-co-succinate-co-succinate-co-succinate), polybutylene adipate- Terephthalate (PBAST), or a mixture of two or more of them.
Further, the polylactide blend composition constituting (A) the extruded foam sheet layer may be further laminated as the (B) coating resin layer in the extrusion processing step.
The coating resin layer (B) is laminated to a thickness of 10 to 300 mu m so as to satisfy the heat resistance and physical properties of the foam.
At this time, if the thickness of the coating resin layer (B) is less than 10 mu m, the strength property can not be satisfied and the printability is insufficient. And if it is more than 300 탆, there is a problem that heat transfer is difficult during molding by preheating by heating.
The multilayer foamed sheet is heated and preheated for 12 to 60 seconds so that the sheet surface temperature becomes 70 to 130 占 폚 in the heating apparatus and then molded to provide a foamed body. In addition to ensuring heat resistance, the foamed sheet has a strength of 35 kgf or more When a coating resin layer is present, it is possible to provide an improved foam having a weight of 40 kgf or more.
The present invention also provides a process for producing the heat-resistant polylactide-based foam. More specifically, it is preferable that 1) 0.1 to 2.0 parts by weight of an epoxy compound and 0.1 to 1.0 part by weight of a peroxide compound are added to 100 parts by weight of the polylactide-containing base resin, 0.1 to 1.0 part by weight of a nucleating agent comprising talc, And 0.1 to 3 parts by weight of a plasticizer selected from the group consisting of adipic acid esters, lactic acid esters, glycerin esters and citric acid esters are extruded and foamed to produce an extruded foam sheet,
2) a step of heating the above extruded foamed sheet in a heating device to preheat the same,
3) The post-molding crystallization process is performed.
In the process for producing the heat-resistant polylactide-based foam of the present invention, the polylactide blend composition of the process 1) is the same as that described above, and is manufactured into an extruded foamed sheet according to a conventional method.
The manufacturing method of the present invention is characterized in that in the step (2), the extruded foamed sheet is heated and preheated in a heating device, inserted into a mold, and molded.
The temperature of the heating apparatus is preheated by heating for 12 to 60 seconds so that the surface temperature of the sheet becomes 70 to 130 ° C in the heating apparatus. When the heating temperature is lower than 70 ° C, the crystallization may not be performed properly. There is a problem that molding is not performed properly beyond the desired crystallization level. Further, the heating time is determined depending on the temperature condition, but the temperature is gradually warmed up in such a manner as to satisfy the change in enthalpy before and after the molding of the extruded foam sheet.
Also, in the step (2), the molten metal passes through the mold after the temperature is preheated. At this time, the molten metal passing through the mold is molten, molten, Coated or plated with a material consisting of two or more combinations. By coating or plating with the material, the preheated melt does not adhere, thereby improving the flowability of the polymer melt.
The mold is composed of a cavity mold and a plug mold having a preheating system, the temperature of the cavity mold is 25 to 130 캜, and the temperature of the mold is maintained at 60 to 130 캜.
Further, the present invention provides a biodegradable heat-resistant molded article comprising a heat-resistant polylactide-based foam having improved crystallinity prepared from the above-mentioned production method.
Examples of the heat-resistant molded article include trays, cups, cup noodles, lunch boxes, and other food packaging materials. At this time, due to the heat-resistant polylactide-based foam, the shape stability is maintained until the lapse of 10 minutes under hot water at 80 to 100 ° C, which is useful for commercialization.
Hereinafter, the present invention will be described in more detail with reference to Examples.
The present invention is intended to more specifically illustrate the present invention, and the scope of the present invention is not limited to these embodiments.
1. Manufacture of extruded foam sheet
< Manufacturing example 1 to 2>
10% by weight of amorphous polylactide (manufactured by Zhejiang Hisun Biomaterials, trade name: Revode 101) was mixed with 90% by weight of a crystalline polylactide resin (trade name: 4032D, manufactured by Natureworks) to prepare a polylactide- . 1.0 part by weight of an epoxy chain extender as a chain extender and 0.1 part by weight of a peroxide chain extender as 100 parts by weight of the polylactide-based polymer composition, 1.8 parts by weight of talc having a size of 0.1 to 5 mu m as a nucleating agent, And 1.0 part by weight of a plasticizer (Acetyl tributyl citrate) were well mixed using a general mixer such as a tumbling mixer, and then extruded in a tandem type extruder connected to a first extruder having an inner diameter of 90 mm and a second extruder having an inner diameter of 120 mm, . At this time, the polylactic acid resin particles were fed to the first extruder, heated and melt kneaded, and then 2.5 parts by weight of butane as a blowing agent was injected into the first extruder and the retention time was maintained at 10 minutes. At this time, the heating and melting temperature was maintained at 170 to 230 占 폚 based on the resin temperature. Then, the temperature of the melt-mixing reaction product was slightly reduced in the second extruder connected to the first extruder so that the resin temperature was 120 to 150 ° C. Thereafter, the resultant was extruded from a ring-shaped die having a circular cross-section with a diameter of 110 mm and a slit interval of 0.5 mm, and was foamed cylindrically, and the cylindrical foamed material was cooled and discharged in the extrusion and extrusion directions to obtain a foamed sheet.
< Comparative Example 1 to 2>
The extruded foam sheet was produced in the same manner as in Preparation Example 1, except that the content of the chain extender, talc, and plasticizer as described in the following Table 1 and the content thereof were changed.
< Comparative Example 3>
In Step 1, 10 wt% of amorphous polylactic acid (trade name: Revode 101, manufactured by Zhejiang Hisun Biomaterials Co., Ltd.) was mixed with 90 wt% of a crystalline polylactic acid resin (trade name: 4032D, manufactured by Natureworks) to prepare a polylactic acid polymer composition . The procedure of Production Example 1 was repeated except that the chain extender and the content of talc and the content of the chain extender shown in Table 1 were changed with respect to 100 parts by weight of the polylactic acid polymer composition.
< Experimental Example 1> Heat resistance evaluation One
The extruded foamed sheets produced in Production Examples 1 to 2 and Comparative Examples 1 to 3 were selected as samples and heat resistance was measured.
Specifically, the sample was placed in a dryer preliminarily heated to a predetermined temperature, and the sample was held for 10 minutes. The sample was taken out and cooled to room temperature, and the shape and size of the sample were measured. If the numerical change is within 0.1%, it is judged to be heat-resistant.
The results are shown in Table 2 below. In the experiment in which a sample (original length = 100 mm) was put in a drying furnace, the sample was marked with o when the change in the sample length was within 0.5%
From the results of the above Table 2, the extruded foam sheet produced according to the composition of Table 1 was evaluated for heat resistance temperature according to JIS-K-7121 by the heat resistance evaluation 1 method. As a result, The foam sheet exhibited a heat-resistant temperature of 60 to 65 캜.
On the other hand, in the case of Comparative Example 3 in which the chain extender was added in a large amount, when a part of the polymer was crosslinked and the sheet rolled up in the machine direction was reheated in the dryer, the excessively crosslinked sheet was shrunk, The occurrence of shrinkage and warping was confirmed.
2. Manufacture of foamed molded extruded foam sheet
< Example 1 to 2>
Specifically, the extruded foam sheet for molding was partially crystallized in a preheater and then transferred to a mold heated to a predetermined temperature to form a container.
The molding conditions of the extruded foam sheet were preliminarily heated in a far infrared ray heater from 70 ° C to 90 ° C for a total preheating time of 18 to 60 seconds, and inserted into a mold to prepare a bowl. At this time, the temperature of the cavity mold is 60 占 폚 and the temperature of the mold is 100 占 폚. The bowl container formed from the above was 144 mm in diameter and 75 mm in height.
< Comparative Example 4-5>
The extruded foamed sheets obtained in Preparation Examples 1 and 2 were passed through an infrared preheater at 70 캜 for a total preheating time of 12 seconds, and then inserted into a mold to be molded.
< Comparative Example 6>
The extruded foamed sheet obtained in Comparative Example 3 was passed through an infrared preheater at 70 캜 for a total preheating time of 12 seconds and inserted into a mold to be molded.
< Comparative Example 7>
The extruded foamed sheet obtained in Comparative Example 3 was preliminarily heated in an infrared preheater from 70 ° C to 90 ° C for a total preheating time of 36 to 54 seconds and inserted into a mold for molding.
< Experimental Example 2> Heat resistance evaluation 2
Boiling water was poured into the bowl container manufactured in the above Examples and Comparative Examples and held for 10 minutes, then the water was discarded, and the container was cooled to room temperature to measure its diameter and height. It was judged that there was heat resistance if there was no numerical change. The results are shown in Table 3 below.
3. Production of foamed molded multilayer foam sheet
< Example 5>
(A) A method of extruding a coated resin layer (B) shown in the following Table 3 onto the layer of the extruded foamed sheet prior to winding the extruded foam sheet layer of Example 1 or a method of lamination of the sheet composed of the above coated resin layer (B) To prepare a multilayer foamed sheet.
Thereafter, the multi-layered foamed sheet was heated and preheated in a far-infrared ray heater to partially crystallize it, and then transferred to a mold heated at a predetermined temperature. At this time, the molding conditions of the multilayer extruded foam sheet were preheated in a far-infrared ray heater at 70 to 90 DEG C for a total preheating time of 18 to 36 seconds, and then inserted into a mold to form a bowl. At this time, the cavity mold was preheated to 60 deg. C, and the mold mold was preheated and maintained at 100 deg.
Evaluation of heat resistance was carried out in the same manner as in Experimental Example 2 and is shown in Table 4 below.
As described above, the present invention provides an extruded foam sheet comprising a polylactide blend composition having controlled thermal properties; Or a multilayer foamed sheet in which a coating resin layer containing a biodegradable polymer resin is laminated on at least one surface of the extruded foamed sheet was heated and preheated under specific conditions and molded to complete a heat resistant polylactide foam.
The heat-resistant polylactide-based foam of the present invention is improved in heat resistance and strength, and therefore, the biodegradable heat-resistant molded article using the same is useful for commercialization because its shape stability is maintained until 10 minutes elapses in boiling water.
While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art.
Claims (11)
The heat of fusion (Hm) of the extruded foam sheet before molding is 12 to 40 J / g,
(Enthalpy change value (Hm -? Hc)) of the foamed product after the molding is 47 to 75 J / g when the degree of crystallization (enthalpy change value A heat-resistant polylactide-based foam having a heat characteristic controlled to be 30 to 50 J / g higher than the crystallization degree (enthalpy change value (Hm -? Hc)) of the extruded foamed sheet.
0.1 to 2.0 parts by weight of an epoxy compound and 0.1 to 1.0 part by weight of a peroxide compound,
0.1 to 5 parts by weight of a crystal nucleating agent containing talc and
0.1 to 3 parts by weight of any one plasticizer selected from the group consisting of adipic acid esters, lactic acid esters, glycerin esters and citric acid esters.
Wherein the multi-layered foamed sheet is preheated by heating for 12 to 60 seconds so that the surface temperature of the sheet becomes 70 to 130 占 폚 in the heating apparatus, cured after molding, and the strength is reinforced by 10% or more.
Heating and extruding the extruded foamed sheet at a temperature of 70 to 130 占 폚 in a heating device for 12 to 60 seconds,
Wherein the heat-resistant polylactide-based foam is subjected to the post-molding crystallization process.
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| KR20190093886A (en) | 2018-02-02 | 2019-08-12 | 케이비에프(주) | Foaming composition, manufacturing method of foaming extruded sheet using the same and expandable-molded article manufactured therefrom |
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| CN114854079B (en) * | 2022-06-20 | 2023-05-23 | 台州玉米环保科技有限公司 | Preparation method of temperature-resistant PLA plastic-absorbing tableware |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2002003709A (en) * | 2000-06-20 | 2002-01-09 | Unitika Ltd | Biodegradable heat-resistant resin composition, sheet, molded product and foamed product |
| US20120244362A1 (en) * | 2011-03-22 | 2012-09-27 | Pramanik Pranabes K | Multi-layer sheet structure |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2002003709A (en) * | 2000-06-20 | 2002-01-09 | Unitika Ltd | Biodegradable heat-resistant resin composition, sheet, molded product and foamed product |
| US20120244362A1 (en) * | 2011-03-22 | 2012-09-27 | Pramanik Pranabes K | Multi-layer sheet structure |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| KR20190093886A (en) | 2018-02-02 | 2019-08-12 | 케이비에프(주) | Foaming composition, manufacturing method of foaming extruded sheet using the same and expandable-molded article manufactured therefrom |
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