KR20110130029A - Biodegradable materials having excellent transparency and flexibility, its manufacturing process and formed products - Google Patents

Abstract

PURPOSE: A biodegradable resin provided to increase mechanical strength like elongation and shock resistance, maintaining transparency which is the inherent characteristic of a polylactic acid resin. CONSTITUTION: A biodegradable resin comprises: a polylactic acid resin including more than 50mol% L-lactic acid, D-lactic acid, or L,D-lactic acid; an acrylic monomer; and a peroxide initiator. The weight ratio of the polylactic acid resin and the acrylic monomer is 95/5 - 50/50 wt%. The parts by weight of the acrylic monomer is 0.01-10 parts by weight comparison to the sum of the polylactic acid resin and the acrylic monomer of 100 parts by weight.

Description

      Biodegradable materials having excellent transparency and flexibility, its manufacturing process and formed products

The present invention relates to a biodegradable resin composition having excellent transparency and flexibility, and a method of manufacturing the same. More specifically, polylactic acid resin and acrylic monomer are melt kneaded in a twin screw extruder to maintain transparency, which is inherent in polylactic acid. In the meantime, the present invention relates to a biodegradable resin composition, a manufacturing method, and a processed molded article of which mechanical properties such as elongation and impact strength are improved and a melt flow index is adjustable to improve molding processability.

        Plastic, a petrochemical product, has excellent physical properties, processability, durability, and economy, and is used as a material for various purposes such as industrial, agricultural, and commercial purposes. In particular, it is widely used as a packaging material indispensable to life. However, these plastic products have a disadvantage of good durability at the stage of disposal as a role, because the degradation of the natural world affects the ecosystem, the problem of environmental pollution is getting serious day by day. In addition, carbon dioxide and energy generated during the depletion of petroleum resources and the production of plastics are a major cause of global warming.

        Therefore, attention is now focused on the development of so-called degradable plastics, which makes it possible to decompose the used plastic by itself. Currently, various kinds of degradable plastics have been developed from various technologies and raw materials. Among them, polylactic acid is produced in large quantities and inexpensively by developing fermentation method of L-lactic acid, which is produced by decomposing corn or sugar cane. Its fast decomposition rate, resistance to mold, and good odor resistance to food have expanded its range of applications. However, in the case of polylactic acid, all of them are limited in the field of hard molded products due to their brittle, hard and low melt viscosity characteristics, and foaming occurs during extrusion foaming, so that sufficient foaming ratio is not obtained, and when inflation molding or blow molding is performed. Since there is a problem that bubbles are not stabilized and knitting tends to occur in the molded body, there are various drawbacks such as being limited in setting molding conditions and having a low crystallization rate, such as poor production efficiency in injection molding. Therefore, in order to put it into practical use, it is necessary to improve the melt tension and the torsional hardenability during the measurement of the elongation viscosity and the improvement of the crystallization rate.

         Therefore, in order to use polylactic acid for a purpose, it is required to improve physical properties by using materials other than polylactic acid. In general, techniques for soft-nitrifying resins include plasticizer addition, copolymerization, blending of soft polymers, and the like. Although the plasticizer and the copolymer method can impart sufficient flexibility, there is a problem in that the plasticizer oozes out, or the heat resistance is insufficient at high temperatures, so that the plasticizer or the copolymer method can be put to practical use due to the change in flexibility due to temperature change. In addition, the method of blending the soft polymer lowers the transparency of PLA inherent, and the price of the biodegradable soft polymer used in the blend is expensive, and there are various problems for practical use due to the deterioration of physical properties due to the addition of a large amount.

          On the other hand, many studies have been conducted in that the method of crosslinking by melt kneading such as a peroxide, a reactive compound, etc. is simple and the molecular weight can be freely modified. However, acid anhydrides and polyhydric carboxylic acids used in Japanese Patent Laid-Open No. 11-60928 are not practical, such as unevenness in the reaction and need to be reduced in pressure. In addition, the polyhydric isocyanate used in Japanese Patent No. 2571329 and Japanese Patent Laid-Open No. 2000-17037 has a well-established technique for reaching the practical use level, such as a low molecular weight decrease during remelting and a problem in stability during operation. not.

      Japanese Patent Application Laid-open No. Hei 10-324766 suggests that biodegradable polyester resins synthesized from dibasic acids and glycols can be effectively foamed by crosslinking with a compound having an unsaturated bond with an organic peroxide. It is. This method is an example of a method of impregnating the resin fine particles with a crosslinking agent at a temperature lower than the melting point of the resin. Although the use of divinylbenzene as a crosslinking assistant is described in detail, the use of acrylic compounds has not been studied. Moreover, only application to the low heat resistance biodegradable polyester resin synthesize | combined from dibasic acid and glycol is examined. Moreover, in addition of such a crosslinking agent and a crosslinking adjuvant, the method which can operate stably for a long time is not proposed.

In addition, in Japanese Patent Application Laid-Open No. 2004-67894, in order to increase the mechanical strength heat resistance and flexibility of the polylactic acid, the mixed composition of the polylactic acid and the aliphatic polyester has two or more meta (acryl) groups in the molecule, or one or more. There is a composition in which a (meth) acrylic acid ester compound having a (meth) acrylic group and at least one glycidyl group is added and melt-kneaded, but the (meth) acrylic acid ester compound used herein has a bifunctional group and is a polylactic acid and an aliphatic By only acting as a crosslinking agent for improving compatibility with the polyester, the transparent and flexible composition obtained in the present invention cannot be obtained.

Therefore, the present invention is to solve the problems of the conventional polylactic acid resin as described above, in particular, the mechanical properties such as transparency, flexibility and improved melt flow index control is made using a biodegradable resin and the processability is improved using this resin It is an object to provide a product and a method for producing the resin.

The object of the present invention comprises a polylactic acid resin (a) containing at least 50 mol% of L-lactic acid, D-lactic acid or L, D-lactic acid, an initiator (c) consisting of an acrylic monomer (b) and a peroxide (a) (C) is 0.01-10 weight part with respect to a total of 100 weight part of (a) and (b) whose weight ratio (a / b) is 95/5-50/50, and (b) It is achieved by the biodegradable resin composition characterized by.

The said acryl monomer (b) is achieved by the biodegradable resin composition characterized by mixing an acryl or methacryl monomer individually or in mixture of 2 or more types.

The biodegradable resin composition is achieved by a biodegradable resin composition comprising a single or two or more selected from a plasticizer, a nucleating agent, a heat stabilizer, an antioxidant, a weathering agent, a flame retardant, a lubricant, an antistatic agent, and a filler.

It is achieved by a biodegradable resin composition comprising any one of the biodegradable resin moldings obtained by extrusion molding, injection molding, foam molding, and blow molding the biodegradable resin composition.

The present invention by mixing the acrylic monomer and the initiator to the polylactic acid resin having fragile properties, melt-kneading to produce a biodegradable resin composition, while maintaining the transparency, which is an inherent characteristic of polylactic acid resin, elongation and impact resistance By increasing the mechanical strength such as, and increasing the melt viscosity, there is an effect of improving the workability.

In addition, it is possible to control the melt flow index by controlling the type of monomer and the degree of crosslinking.Increasing the melt viscosity improves the processability to improve the processability, injection molding, extrusion molding, packaging film, and co-extrusion or laminate processing for various film uses. Can be used.

1 is a photograph after measuring the tensile strength of Comparative Example 1 and Example 6 of the present invention
2 is a graph showing transmittances of visible light regions of Comparative Examples 1 and 2 of the present invention;

The present invention has been conducted in order to solve these problems, as a result of 100 parts by weight of a polylactic acid resin (a) containing L-lactic acid, D-lactic acid or L, D-lactic acid (b) 95 / 5-50 In mixing / 50 parts by weight, the acrylic monomer is characterized in that one or more (meth) acryl groups are used alone or in combination, specifically methyl (meth) acrylate, ethyl (meth) acrylate, 2-ethylhexyl (Meth) acrylate, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 4-tert-butylcyclohexyl (meth) acrylate, hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, hexyl (meth) acrylate, butyl (meth) acrylate, dodecyl (meth) acrylate, isobutyl (meth) acrylate, isodecyl (meth) acrylate, iso Octyl (meth) acrylate, glycy 0.01-10 parts by weight of a peroxide initiator is added to 100 parts by weight of (meth) acrylate and 2-carboxyethyl (meth) acrylate alone or as a mixture and a mixture of polylactic acid resin (a) and acrylic monomer (b). The polymerization is carried out by melt kneading in an extruder. As an initiator, di-t-butyl peroxide, dicumyl peroxide, di-t-amyl peroxide, 2,5-dimethyl-2,5-di (t -Butyl foroxy) hexine-3, t-butyl peroxy benzoate, etc. are used alone or in combination, and by controlling the melt flow index of the polylactic resin, easy processing, improved transparency and flexibility biodegradation The resin was prepared.

     Polylactic acid resins contain at least 50 mol%, preferably 50% to 80% mol%, of L-lactic acid, D-lactic acid and mixtures thereof, in addition to these α- and / or β-hydroxy acids, ie glycolic acid. , 3-hydroxybutyl acid, 3-hydroxy valeric acid, 3-hydroxy caproic acid and the like, and there is no limitation on the mixing ratio.

     The (meth) acryl monomer is not particularly limited, and when the carbon number of the (meth) acryl monomer is 5 or more, or contains a hydroxy group, 4 or more are preferable, and glycidyl (meth) acryl having a reactive functional group The compound containing two or more (meth) acryl groups in a rate or a single molecule can also be used.

      The peroxide used in the present invention is added in a state in which it is dissolved or dispersed in an acrylic monomer, and is not limited in kind, but preferably has a boiling point of 70 ° C. or more and a half-life of 20 minutes or less at a melting temperature.

As the melt kneading used in the present invention, conventionally known twin screw extruders, single screw extruders, roll kneaders, brabenders, and the like can be used. Particularly, melt kneading in a twin screw extruder provides a uniform reaction and obtains a good biodegradable resin composition. Can be.

In the biodegradable resin composition of the present invention, pigments, heat stabilizers, antioxidants, weathering agents, flame retardants, plasticizers, lubricants, antistatic agents, fillers and the like can be added within a range that does not significantly impair their properties. As the heat stabilizer or the antioxidant, for example, it is possible to use hindered phenols, phosphorus compounds, hindered amine ions compounds, copper compounds, halides of alkali metals or mixtures of these. Examples of the inorganic filler include talc, calcium carbonate, zinc carbonate, wollastonite, silica, alumina, magnesium oxide, calcium silicate, sodium aluminate, potassium aluminate, sodium aluminosilicate, magnesium silicate, hollow glass beads, carbon black, zinc oxide, Antimony trioxide, zeolite, metal whiskers, ceramic whiskers, potassium tartanate, urea nitrides, graphite, glass fibers, carbon fibers and the like. As the organic filler, starch, cellulose fine particles. Natural polymers such as wood flour, soybean meal, rice, bran, and modified products thereof.

      When manufacturing a foam with the biodegradable resin composition of this invention, all the methods generally used are applicable. For example, an extruder can be used to blend a decomposable blowing agent that decomposes in advance at the melting temperature of the resin into the resin, extrude from a slitter-like nozzle to form a sheet, or a pipe or the like using a release nozzle. As an example of a decomposition type foaming agent, inorganic foaming agents, such as an azo compound, a nitroso compound, a hydramine compound, or sodium hydrogencarbonate, are also possible. As the blowing agent in this case, inorganic compounds such as nitrogen, carbon dioxide and water, various hydrocarbons such as methane, ethane and butane, freon compounds and organic solvents represented by various alcohols such as ethanol and methanol may be used. Moreover, the method of manufacturing the organic fine particle which prepares microparticles | fine-particles of a resin composition previously, impregnates the above-mentioned foaming agents, such as an organic solvent and water, and foams by a change of temperature or pressure can also be applied.

The foam thus foamed can be applied to food packaging trays, buffers, stationery, sundries, and the like.

        As extrusion molding, it is possible to apply the T-die method. The extrusion temperature is required to be equal to or higher than the melting point (Tm) or the flow initiation temperature of the biodegradable polyester resin composition, and is preferably in the range of 160 to 230 ° C, more preferably 170 to 210 ° C. If the molding temperature is too low, the molding may become unstable or difficult to work due to overloading. On the contrary, if the molding temperature is too high, the biodegradable polyester resin may be decomposed and the strength of the obtained extrudate may be degraded. It is undesirable because it occurs.

Specific examples of the biodegradable sheets or pipes produced by the extrusion method include thermoforming sheets, batch foam sheets, credit cards and the like, book holders, clear piles, straws, agricultural / horticultural hard pipes, and the like. Can be. In addition, the biodegradable sheet is formed by complex shapes such as vacuum forming, press forming, and vacuum pressing forming, and thus it is possible to manufacture food containers, agricultural / horticultural containers, blister packaging containers, Ptpi pack containers, and the like. Do.

      In addition, it is possible to manufacture a transparent sheet by a calendering molding method, and the manufactured sheet can be used as an overlay film for credit cards, a film for stationery, or a decorative sheet.

     The shape of the food container, the agricultural / horticultural container, the blister pack container, and the Ptpi pack container is not particularly limited, but is suitable for molding of 2 mm or more in depth for accommodating food, articles and medicines. Although the thickness of a container is not specifically limited, In order to maintain a constant intensity | strength, it is preferable that it is 50 micrometers or more, and it is more preferable that it is 150-500 micrometers. As a specific example of a food container, the tray of a fish food, an instant food container, a fast food container, a bento container, etc. are mentioned. In addition, as a specific example of the blister pack container, a packaging container of various product groups such as office supplies, toys, batteries, etc. may be used in addition to food.

       As a blow molding method, the direct blow method which directly shape | molds using a raw material chip, the injection blow molding method which blow-molds after shaping | molding a preform (preform) first by injection molding, or a stretch blow molding, etc. can also be employ | adopted. In addition, both the hot parison method of continuously blow molding after preform molding and the cold parison method of cooling out the preform once and then heating it again to perform blow molding can be used.

        As the injection molding method for producing an injection molded product from the biodegradable polyester composition of the present invention, a general injection molding method can be used, or gas injection molding, injection press molding and the like can also be employed. Preferably it is best to shape | mold in the range of 170-230 degreeC, and further more preferably 180-210 degreeC. If the molding temperature is too low, unmolding may occur, or work may not be possible due to overload. On the contrary, if the molding temperature is too high, the biodegradable polyester resin may be decomposed, resulting in a decrease in strength or coloring of the obtained molded article. Is not desirable because On the other hand, mold temperature needs to be below (Tm-20 degreeC).

        The shape of the injection molded article obtained by the injection molding method is not particularly limited, and specifically, foods such as plates, bowls, bowls, chopsticks, spoons, forks, knives, containers for fluids, caps for caps, rulers, writing instruments, Office supplies such as clear cases, CD cases, triangular corners for kitchens, trash cans, toiletries, toothbrushes, combs, hangers, daily necessities, agricultural / horticultural materials such as flower pots, seedling pots, various models such as plastic models, air conditioning panels, refrigerators Resin parts for electronic products such as trays and various boxes, automotive resin parts such as bumpers, automobile dashboards, and door trims. In addition, although the form of the container for fluids is not limited, it is preferable to shape | mold to 20 mm or more for accommodating a fluid. Although there is no restriction | limiting in particular in thickness of yogi, It is preferable that it is 0.1 mm or more from a side of strength maintenance, and it is preferable that it is 0.1-5 mm. As a specific example of a container for fluids, the primary storage container of seasonings, such as food cups, beverage bottles, soy sauce, sauce, mayonnaise, ketchup, and cooking oil, such as dairy products, soft drinks, and liquor, containers, such as shampoo and rinse, and cosmetic containers And agricultural containers.

     In addition, the biodegradable resin of the present invention can be used as an impact modifier of a conventional biodegradable resin, the amount of addition may vary depending on the required physical properties and uses.

Although the following examples are intended to illustrate the present invention in more detail, these examples are for illustrative purposes only and should not be construed as limiting the present invention.

Example 1

0.3 part by weight of dicumyl peroxide based on 95 parts by weight of polylactic acid resin containing 50% by weight of L-lactic acid, D-lactic acid or L, D-lactic acid and 5 parts by weight of 2-hydroxyethyl acrylate (L / D 36 extruded at an extrusion bed temperature of 200 ° C. and a die outlet temperature of 190 ° C.) to cut into pellets to obtain a biodegradable resin composition.

Example 2

       Based on 95 parts by weight of polylactic acid resin containing 50% by weight of L-lactic acid, D-lactic acid or L, D-lactic acid and 5 parts by weight of butyl acrylate, 0.3 part by weight of dicumyl peroxide is a twin screw extruder (L / D 36 extrusion bed At a temperature of 200 ° C. and a die exit temperature of 190 ° C.), and cutting into pellets to obtain a biodegradable resin composition.

Example 3

Dicumilfer based on a mixture of 90 parts by weight of a polylactic acid resin containing at least 50 mol% of L-, D- or L, D-lactic acid, 5 parts by weight of 2-hydroxyethyl acrylate and 5 parts by weight of ethylhexyl acrylate. 0.5 parts by weight of oxide was extruded with a twin screw extruder (L / D 36 extrusion bed temperature 200 ° C., die exit temperature 190 ° C.) to cut into pellets to obtain a biodegradable resin composition.

Example 4

       1 weight of dicumyl peroxide based on a mixture of 80 parts by weight of polylactic acid resin containing 50% by weight of L-lactic acid, D-lactic acid or L, D-lactic acid, 5 parts by weight of butyl acrylate and 15 parts by weight of ethylhexyl acrylate. The part was extruded by the twin screw extruder (L / D36 extrusion bed temperature 200 degreeC, die exit temperature 190 degreeC), and it processed into the pellet form and obtained the biodegradable resin composition.

Example 5

        Based on a mixture of 80 parts by weight of a polylactic acid resin containing at least 50 mol% of L-lactic acid, D-lactic acid or L, D-lactic acid, 8 parts by weight of 2-hydroxyethyl acrylate and 2 parts by weight of glycidyl methacrylate 0.3 parts by weight of dicumyl peroxide was extruded using a twin screw extruder (L / D 36 extrusion bed temperature 200 ° C., die exit temperature 190 ° C.) to obtain a biodegradable resin composition.

Example 6

Dicumylfer based on a mixture of 80 parts by weight of a polylactic acid resin containing at least 50 mol% of L-, D- or L, D-lactic acid, 5 parts by weight of 2-hydroxyethyl acrylate and 15 parts by weight of butyl acrylate. 0.5 weight part of oxide was extruded with the twin screw extruder (L / D36 extrusion bed temperature 200 degreeC, die exit temperature 190 degreeC), and it processed into the pellet form and obtained the biodegradable resin composition.

Example 7

80 parts by weight of polylactic acid resin containing at least 50 mol% of L-lactic acid, D-lactic acid or L, D-lactic acid, 2 parts by weight of 2-hydroxyethyl acrylate, 7 parts by weight of ethylhexyl acrylate, glycidyl acryl Based on the mixture of 1 part by weight and 10 parts by weight of polyethylene glycol 300, 0.5 part by weight of dicumyl peroxide was extruded with a twin screw extruder (L / D 36 extrusion bed temperature 200 ° C., die exit temperature 190 ° C.) and processed into pellets to be biodegradable. The resin composition was obtained.

Example  8

        73 parts by weight of a polylactic acid resin containing at least 50 mol% of L-, D- or L-D-lactic acid, 5 parts by weight of 2-hydroxyethyl acrylate, 5 parts by weight of butyl acrylate, ethylhexyl acrylate 15 0.5 parts by weight of dicumyl peroxide based on a mixture of 2 parts by weight of glycidyl acrylate is extruded with a twin screw extruder (L / D 36 extrusion bed temperature 200 ° C., die exit temperature 190 ° C.) and processed into pellets for biodegradability. The resin composition was obtained.

Comparative Example 1

100 parts by weight of polylactic acid resin was prepared in a pellet state using a twin screw extruder.

Comparative Example 2

85 parts by weight of polylactic acid resin and 15 parts by weight of polyethylene glycol 300 were extruded with a twin screw extruder (L / D 36 extrusion bed temperature 200 ° C., die exit temperature 190 ° C.) to be processed into pellets to obtain a biodegradable resin composition.

Comparative Example 3

70 weight part of polylactic acid resin and 30 weight part of polyethylene rosinate were extruded with the twin screw extruder (L / D36 extrusion bed temperature 200 degreeC, die exit temperature 190 degreeC), and it processed into the pellet form, and obtained the biodegradable resin composition.

In Examples 1 to 8, specimens of ASTM D638 (No. 4) were manufactured by injection molding for physical property tests of the biodegradable resin compositions according to the present invention and the resin compositions obtained in Comparative Examples 1 to 3. The temperature conditions were 100 degrees, 140 degrees, 180 degrees and nozzle temperature was formed at 195 degrees from the bottom of the hopper, respectively, and the elongation at break was measured in accordance with ASTMD885 using a universal testing machine. In addition, the transparency was measured using a naked eye or a light transmittance meter, and the results are shown in the following table.

ingredient
unit
Example Comparative example One
2 3 4 5 6 7 8 One 2 3 Polylactic acid
Parts by weight 95 95 90 80 90 80 80 73 100 85 70 2-hydroxy ethyl acrylate Parts by weight 5 - 5 - 8 5 2 5 Butyl acrylate
Parts by weight - 5 - 5 15 5 Ethylhexyl acrylate Parts by weight - - 5 15 7 15 Glycidyl methacrylate Parts by weight - - - 2 - One 2 Dicumyl peroxide
Parts by weight 0.3 0.3 0.5 One 0.3 0.5 0.5 0.5 Polyethylene Glycol 300 Parts by weight - - - 10 15 Polybutylene Lycinate Parts by weight 30 Melt flow index
g / 10min 6.2 4.3 5.4 10.2 3.6 6.1 4.5 1.8 5.3 10.4 12.5 Elongation rate
% 45 66 143 121 70 187 103 285 4 35 47 Transparency
- ○ ○ ○ ○ ○ ○ △ ○ ○ △ ×

○: Good transparency, △: Normal transparency, X: Poor transparency

Claims (4)

Consists of polylactic acid resin (a), acrylic monomer (b) and peroxide initiator (c) containing at least 50 mol% of L-lactic acid, D-lactic acid or L, D-lactic acid, and the weight ratio of (a) and (b) (c) is 0.01-10 weight part with respect to a total of 100 weight part of (a / b) (95%-50/50 (weight%)) and (a) and (b) in total, The biodegradable resin composition characterized by the above-mentioned. .
The biodegradable resin composition according to claim 1, wherein the acrylic monomer (b) is made of an acrylic or methacrylic monomer alone or in mixture of two or more thereof.
The biodegradable resin composition according to claim 1 or 2, wherein the biodegradable resin composition is made of a plasticizer, a nucleating agent, a heat stabilizer, an antioxidant, a weathering agent, a flame retardant, a lubricant, an antistatic agent, or a mixture selected from the group consisting of two or more. Biodegradable resin composition.
The biodegradable resin composition according to claim 1 or 2, wherein the biodegradable resin composition comprises any one of a biodegradable resin molded article obtained by extrusion molding, injection molding, foam molding, and blow molding.

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