JP2012082333A - Biodegradable resin composition for foaming, and foamed molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biodegradable resin composition for foaming, with which the foaming ratio is easily enhanced in various foam molding methods and which provides a product having a surface with high-quality feeling, and to provide a foamed molding body.SOLUTION: The biodegradable resin composition for foaming includes 99-50 wt.% of a biodegradable resin (a) and 1-50 wt.% of a specified polyethylene-based resin (b).

Description

  The present invention relates to a biodegradable resin composition capable of obtaining a foamed molded article excellent in dispersibility of bubbles and the beauty of the surface of a molded article, and excellent in mechanical performance such as impact resistance and strength, and foaming using the composition. It relates to molded products.

  In recent years, biodegradable resins such as polylactic acid and polyhydroxybutyrate polymers have attracted attention as materials that do not increase biodegradability and do not increase carbon dioxide in the atmosphere from the viewpoint of carbon neutrality. Therefore, these biodegradable resins have begun to be used in tableware, packaging films, leisure goods, extruded products, home appliances such as personal computers and mobile phones, OA equipment such as printers and copiers, and automobile parts.

  Among these, foams that are lightweight and have excellent heat insulating properties are often used in tableware, automobile members, home appliance parts, and house interior members.

  Therefore, in order to produce these foams, in-mold foam molding using polylactic acid-based resin foam particles (see, for example, Patent Document 1), and a method for obtaining a polylactic acid resin injection-molded body using a supercritical fluid (for example, Patent Document 2), and a resin composition (for example, see Patent Document 3) composed of specific polylactic acid and an isocyanate compound has been proposed.

JP 2010-208091 A JP 2009-255432 A JP 2002-155197 A

  However, the method described in Patent Document 1 has low impact resistance, and the method described in Patent Document 2 requires an expensive molding machine and has a problem that the expansion ratio does not increase. Further, the resin composition described in Patent Document 3 also has a problem that the expansion ratio does not increase.

As a result of intensive studies to solve the above problems, the present inventors have conducted a foam molding using a biodegradable resin composition comprising a biodegradable resin and a specific polyolefin-based resin. In this case, the present inventors have found that a foamed molded article excellent in dispersibility of bubbles and the beauty of the surface of the molded article and excellent in mechanical performance such as impact resistance and strength has been found.
That is, this invention relates to the biodegradable resin composition for foaming characterized by consisting of biodegradable resin (a) 99-50 weight% and specific polyethylene-type resin (b) 1-50 weight%. is there.

  The present invention will be described in detail below.

  The biodegradable resin (a) used in the present invention is not particularly limited as long as it is known. For example, aliphatic polyester, aliphatic-aromatic copolymer polyester, polyvinyl alcohol, polylactic acid resin, and polyhydroxybutyrate resin A coalescence, a polyester carbonate type polymer, etc. are mentioned, These 1 type (s) or 2 or more types can be used.

  Examples of the aliphatic polyester include polybutylene succinate, polycaprolactone, polybutylene succinate adipate, polyethylene succinate, and polyglycolic acid.

  Examples of the aliphatic-aromatic copolymer polyester include a copolymer of terephthalic acid, butanediol, and adipic acid, poly (ethylene terephthalate / succinate), poly (caprolactone / butylene succinate), and the like.

  Examples of the polylactic acid-based resin include L-lactic acid, D-lactic acid, polymers of derivatives thereof, and copolymers having these as main components. Examples of such copolymers include L-lactic acid, D-lactic acid, and derivatives thereof, such as glycolic acid, polyhydroxybutyric acid, polycaprolactone, polybutylene succinate, polyethylene succinate, polybutylene adipate terephthalate, and polybutylene succinate terephthalate. And a copolymer obtained from one or more of polyhydroxyalkanoate and the like. Of these, poly (L-lactic acid), poly (D-lactic acid) and copolymers thereof are particularly preferable from the viewpoints of heat resistance and moldability.

  Examples of the polyhydroxybutyrate polymer include poly-3-hydroxybutyrate homopolymers, hydroxyalkanoate copolymers other than 3-hydroxybutyrate / 3-hydroxybutyrate, and the like. Examples of hydroxyalkanoates other than 3-hydroxybutyrate include, for example, 3-hydroxypropionate, 3-hydroxyvalerate, 3-hydroxyhexanoate, 3-hydroxyheptanoate, 3-hydroxyoctanoate , 3-hydroxynonanoate, 3-hydroxydecanoate, 3-hydroxyundecanoate, 4-hydroxybutyrate, and hydroxylaurylate. Among them, since a biodegradable resin composition having excellent heat resistance can be obtained, poly-3-hydroxybutyrate homopolymer, 3-hydroxybutyrate / 3-hydroxyvalerate copolymer, 3-hydroxybutyrate / 4- It is preferably a hydroxybutyrate copolymer. The amount of the copolymer component of the hydroxyalkanoate other than 3-hydroxybutyrate in the poly-3-hydroxybutyrate polymer is preferably 0 to 20 mol%, more preferably 0 to 10 mol%. preferable.

  Examples of the polyester carbonate polymer include trimethylene carbonate.

  Among these biodegradable resins, polybutylene succinate, polylactic acid resin, and polyhydroxybutyrate polymer are preferable from the viewpoint of physical properties and availability.

  The MFR (measured under a load of 190 ° C. and 2.16 kg) of the biodegradable resin (a) used in the present invention is preferably 0.1 to 300 g / 10 minutes, and preferably 1 to 20 g / 10 minutes. Is more preferable.

  The melting point of the biodegradable resin (a) is not particularly limited, and is preferably 90 ° C to 250 ° C from the viewpoint of moldability.

  The polyethylene-based resin (b) used in the present invention may be any as long as it belongs to the category called polyethylene-based resin, such as an ethylene homopolymer, a high-pressure low-density polyethylene, and a repeating unit derived from ethylene. Examples thereof include ethylene-α-olefin copolymers composed of repeating units derived from α-olefins having 3 to 8 carbon atoms, and among them, a biodegradable resin composition for foaming that is particularly excellent in heat resistance. It is preferably an ethylene homopolymer composed of a repeating unit derived from ethylene, or an ethylene-α-olefin copolymer composed of a repeating unit derived from ethylene and a repeating unit derived from an α-olefin having 3 to 8 carbon atoms. . Here, the repeating unit derived from an α-olefin having 3 to 8 carbon atoms is derived from an α-olefin having 3 to 8 carbon atoms, which is a monomer, and is contained in the ethylene-α-olefin copolymer. Examples of the α-olefin having 3 to 8 carbon atoms include propylene, 1-butene, 1-hexene, 1-octene, 4-methyl-1-pentene, and 3-methyl-1-butene. . You may use together at least 2 types of these C3-C8 alpha olefins.

And since this polyethylene-type resin (b) becomes a biodegradable resin composition for foaming from which the foaming molding which has especially heat resistance and a high foaming ratio is obtained, it is density according to (A) JISK6760. The density (d) measured by the gradient tube method is 920 kg / m ³ or more and 960 kg / m ³ or less, and (B) the melt tension (MS ₁₆₀ ) measured at 160 ° C. is in the range of 50 to 150 mN. Furthermore, since it becomes a foaming biodegradable resin composition which is excellent in foaming moldability when obtaining a foamed molded article, and obtains a foamed molded article excellent in mechanical strength and color tone, (C) at 190 ° C. The melt flow rate (hereinafter referred to as MFR) measured at a load of 16 kg is 1 g / 10 min to 20 g / 10 min, and (D) the number of terminal vinyls is 0.2 or less per 1,000 carbon atoms. (E) The relationship between the melt tension measured at 160 ° C. (hereinafter referred to as MS ₁₆₀ ) and MFR satisfies the following formula (1), and preferably satisfies the following formula (4):
MS ₁₆₀ > 90-130 × log (MFR) (1)
MS ₁₆₀ > 110-130 × log (MFR) (4)
(F) The relationship between the melt tension measured at 190 ° C. (hereinafter referred to as MS ₁₉₀ ) and MS ₁₆₀ satisfies the following formula (2), and preferably satisfies the following formula (5).
MS ₁₆₀ / MS ₁₉₀ <1.8 (2)
MS ₁₆₀ / MS ₁₉₀ <1.7 (5)
(G) The flow activation energy (kJ / mol) (hereinafter referred to as _{E a.)} Polyethylene and relationship with the density, it satisfies the following formula (3), preferably satisfying the following formula (6) A resin is preferred.

_{125-0.105d <E a <88-0.0550d (3} )
_{127-0.107d <E a <88-0.060d (6} )
The polyethylene-based resin (b) is a melt tension improver that is particularly excellent in the effect of improving the melt tension when blended with a biodegradable resin. Therefore, (H) weight average molecular weight / number average molecular weight (hereinafter, M _w / _Mn .) is preferably 3 or more and 10 or less, more preferably 4 or more and 8 or less.

In addition, as a measuring method of the number of terminal vinyls in this invention, after heat-pressing a polyethylene-type resin, the film prepared by ice-cooling is 4000cm < ^-1 > -400cm < ^- > with a Fourier transform infrared spectrophotometer (FT-IR). It measured in the range of ¹ and computed by the following formula.
Number of terminal vinyls per 1000 carbon atoms (pieces / 1000 C) = a × A / L / d
(In the formula, a is an absorptivity coefficient, A is an absorbance of 909 cm ⁻¹ attributed to terminal vinyl, L is a film thickness, and d is a density. Note that a is 1000 carbons from ¹ H-NMR measurement. was determined from a calibration curve prepared using samples confirmed terminal number vinyl per atom. ^{1 H-NMR} measurement, NMR measurement apparatus (manufactured by JEOL Ltd., trade name GSX400) using deuterated benzene and o -In a mixed solvent of dichlorobenzene at 130 ° C. The number of terminal vinyls per 1000 carbon atoms was calculated from the integral ratio of the peak attributed to methylene and the peak attributed to terminal vinyl. (Based on methylsilane as a reference (0 ppm), a peak with a chemical shift of 1.3 ppm was assigned as methylene and a peak at 4.8 to 5.0 ppm was attributed to terminal vinyl.)
Moreover, MS ₁₆₀ in the present invention uses a die having a length of 8 mm and a diameter of 2.095 mm, an inflow angle of 90 °, a shear rate of 10.8 s ⁻¹ , a draw ratio of 47, and a measurement temperature of 160 ° C. When the maximum stretch ratio was less than 47, the value measured at the highest stretch ratio that did not break was designated as MS ₁₆₀ . Further, MS ₁₉₀ in the present invention was measured under the same conditions as MS ₁₆₀ except for the measurement temperature of 190 ° C.

E _a in the present invention can be obtained by performing dynamic viscoelasticity measurement in a temperature range of 160 ° C. to 230 ° C. and substituting the obtained shift factor into the Arrhenius equation.

M _w / M _n in the present invention is calculated by measuring a weight average molecular weight (M _w ) and a number average molecular weight (M _n ), which are standard polyethylene equivalent values, by gel permeation chromatography (GPC). Is possible.

  The polyethylene resin (b) constituting the biodegradable resin composition for foaming of the present invention is known as a method for producing a polyethylene resin, for example, a high pressure polymerization method, a Ziegler-Natta catalyst, a chromium catalyst, a metallocene catalyst. It may be obtained by a method such as a low pressure polymerization method using a polymerization catalyst such as polyethylene, and particularly preferably polyethylene that satisfies the above (A) to (B), and further (C) to (G), (H) As a method for producing a resin, for example, the production conditions of the present embodiment described later can be arbitrarily made by fine adjustment of the condition factors.

  Specifically, for example, polymerization described in JP-A-2004-346304, JP-A-2005-248013, JP-A-2006-321991, JP-A-2007-169341, JP-A-2008-50278 In the presence of a catalyst, a method of polymerizing ethylene or a method of copolymerizing ethylene and an α-olefin having 3 to 8 carbon atoms can be used.

  More specifically, for example, as a metallocene compound, a bridged bis (substituted or unsubstituted cyclopentadienyl) zirconium complex in which two substituted or unsubstituted cyclopentadienyl groups are bridged by a crosslinking group (hereinafter referred to as component ( a) and a bridged (cyclopentadienyl) (fluorenyl) zirconium complex and / or a bridged (indenyl) (fluorenyl) zirconium complex (hereinafter referred to as component (b)). In the presence of, a method of polymerizing ethylene or a method of copolymerizing ethylene and an α-olefin having 3 to 8 carbon atoms can be used.

  Specific examples of component (a) include dimethylsilylene bis (cyclopentadienyl) zirconium dichloride, dimethylsilylene (cyclopentadienyl) (indenyl) zirconium, dichloride 1,1,3,3-tetramethyldisiloxane-1 , 3-diyl-bis (cyclopentadienyl) zirconium dichloride, 1,1-dimethyl-1-silaethane-1,2-diyl-bis (cyclopentadienyl) zirconium dichloride, propane-1,3-diyl-bis (Cyclopentadienyl) zirconium dichloride, butane-1,4-diyl-bis (cyclopentadienyl) zirconium dichloride, cis-2-butene-1,4-diyl-bis (cyclopentadienyl) zirconium dichloride, 1 , 1,2,2-Tetramethyl Disilane-1,2-diyl - dimethyl body bis (cyclopentadienyl) zirconium dichloride dichloride and the transition metal compound such as chloride, diethyl body, dihydro derivative, diphenyl body, can be exemplified dibenzyl body. Further, compounds in which the hydrogen of the cyclopentadienyl derivative of the above transition metal compound is substituted with a hydrocarbon group, and compounds in which the zirconium atom of the central metal is substituted with a titanium atom or a hafnium atom can also be exemplified.

  Specific examples of component (b) include diphenylmethylene (1-cyclopentadienyl) (9-fluorenyl) zirconium dichloride, diphenylmethylene (2-trimethylsilyl-1-cyclopentadienyl) (9-fluorenyl) zirconium dichloride, Diphenylmethylene (1-cyclopentadienyl) (2,7-dimethyl-9-fluorenyl) zirconium dichloride, diphenylmethylene (1-cyclopentadienyl) (2,7-di-t-butyl-9-fluorenyl) zirconium Dichloride, isopropylidene (1-cyclopentadienyl) (9-fluorenyl) zirconium dichloride, isopropylidene (1-cyclopentadienyl) (2,7-di-t-butyl-9-fluorenyl) zirconium dichloride, diphenylsila Diyl (1-cyclopentadienyl) (9-fluorenyl) zirconium dichloride, dimethylsilanediyl (1-cyclopentadienyl) (9-fluorenyl) zirconium dichloride, diphenylmethylene (1-indenyl) (9-fluorenyl) zirconium dichloride Diphenylmethylene (2-phenyl-1-indenyl) (9-fluorenyl) zirconium dichloride, diphenylmethylene (2-phenyl-1-indenyl) (2,7-di-t-butyl-9-fluorenyl) zirconium dichloride, etc. Examples thereof include dimethyl, diethyl, dihydro, diphenyl, and dibenzyl isomers of dichloride and the above transition metal compounds. Further, compounds in which the hydrogen of the cyclopentadienyl derivative of the above transition metal compound is substituted with a hydrocarbon group, and compounds in which the zirconium atom of the central metal is substituted with a titanium atom or a hafnium atom can also be exemplified.

  Moreover, the quantity of the component (b) with respect to a component (a) does not have a restriction | limiting in particular, It is preferable that it is 0.0001-100 times mole, Most preferably, it is 0.001-10 times mole.

  And as a metallocene catalyst using component (a) and component (b), for example, a catalyst comprising component (a), component (b) and an organoaluminum compound (hereinafter referred to as component (c)); a catalyst comprising a), component (b) and aluminoxane (hereinafter referred to as component (d)); a catalyst further comprising component (c); component (a), component (b) and protonic acid salt (Hereinafter referred to as component (e)), Lewis acid salt (hereinafter referred to as component (f)) or metal salt (hereinafter referred to as component (g)). Catalyst; catalyst further comprising component (c); catalyst comprising component (a), component (b), component (d) and inorganic oxide (hereinafter referred to as component (h)); component (a ), Component (b), component (h), component (e), component (f), component (g) A catalyst comprising at least one salt; a catalyst further comprising a component (c); a component (a), a component (b), a clay mineral (hereinafter referred to as component (i)), and a component (c). Catalysts: Catalysts comprising a component (a), a component (b), and a clay mineral treated with an organic compound (hereinafter referred to as component (j)) can be exemplified. Preferably, the component (a) and the component ( A catalyst comprising b) and component (j) can be used.

  Here, examples of the clay mineral that can be used as the component (i) and the component (j) include fine particles mainly composed of microcrystalline silicate. As a structural feature, a layered structure is formed, and various layers of negative charges are included in the layer. In this respect, it is greatly different from a metal oxide having a three-dimensional structure such as silica or alumina. These clay minerals are generally of a large layer charge, with pyrophyllite, kaolinite, dickite and talc groups (negative charge per chemical formula is approximately 0), smectite groups (negative charge per chemical formula is from about 0.25). 0.6), vermiculite group (negative charge per chemical formula is approximately 0.6 to 0.9), mica group (negative charge per chemical formula is approximately 1), brittle mica group (negative charge per chemical formula is approximately 2) It is classified. Each group shown here includes various clay minerals, and examples of the clay mineral belonging to the smectite group include montmorillonite, beidellite, saponite, hectorite and the like. Further, a plurality of the above clay minerals can be mixed and used.

  The organic compound treatment in component (j) refers to introducing an organic ion between clay mineral layers to form an ionic complex. Examples of the organic compound used in the organic compound treatment include N, N-dimethyl-n-octadecylamine hydrochloride, N, N-dimethyl-n-eicosylamine hydrochloride, N, N-dimethyl-n-docosylamine hydrochloride, N, N-dimethyloleylamine hydrochloride, N, N-dimethylbehenylamine hydrochloride, N-methyl-bis (n-octadecyl) amine hydrochloride, N-methyl-bis (n-eicosyl) amine hydrochloride, N-methyl -Dioleylamine hydrochloride, N-methyl-dibehenylamine hydrochloride, N, N-dimethylaniline hydrochloride can be exemplified.

  The catalyst comprising component (a), component (b) and component (j) can be obtained by bringing component (a), component (b) and component (j) into contact in an organic solvent, A method of adding component (b) to the contact product of (a) and component (j); a method of adding component (a) to the contact product of component (b) and component (j); and component (a) A method of adding the component (j) to the contact product of the component (b); a method of adding the contact product of the components (a) and (b) to the component (j) can be exemplified.

  As the contact solvent, aliphatic hydrocarbons such as butane, pentane, hexane, heptane, octane, nonane, decane, cyclopentane or cyclohexane, aromatic hydrocarbons such as benzene, toluene or xylene, ethyl ether or n-butyl ether And ethers such as halogenated hydrocarbons such as methylene chloride or chloroform, 1,4-dioxane, acetonitrile, or tetrahydrofuran.

  About a contact temperature, it is preferable to select between 0-200 degreeC and to process.

  The amount of each component used is 0.0001 to 100 mmol, preferably 0.001 to 10 mmol of component (a) per 1 g of component (j).

  The contact product of component (a), component (b) and component (j) prepared in this way may be used without washing, or may be used after washing. Further, when the component (a) or the component (b) is a dihalogen, it is preferable to further add the component (c). Further, component (c) can be added for the purpose of removing impurities in component (j), polymerization solvent and olefin.

  When producing the polyethylene-based resin constituting the foamable biodegradable resin composition of the present invention, it is preferable to carry out at a polymerization temperature of −100 to 120 ° C., particularly considering productivity, preferably 20 to 120 ° C., Furthermore, it is preferable to carry out in the range of 60-120 degreeC. The polymerization time is preferably in the range of 10 seconds to 20 hours, and the polymerization pressure is preferably in the range of normal pressure to 300 MPa. The polymerizable monomer is ethylene alone or ethylene and an α-olefin having 3 to 8 carbon atoms. When ethylene is an α-olefin having 3 to 8 carbon atoms, ethylene and α-olefin having 3 to 8 carbon atoms are used. As the olefin supply ratio, ethylene / C3-C8 α-olefin (molar ratio) of 1 to 200, preferably 3 to 100, and more preferably 5 to 50 can be used. It is also possible to adjust the molecular weight using hydrogen during polymerization. The polymerization can be carried out by any of batch, semi-continuous and continuous methods, and can be carried out in two or more stages by changing the polymerization conditions. In addition, the ethylene copolymer can be obtained by separating and recovering from the polymerization solvent by a conventionally known method after the completion of the polymerization and drying.

  Polymerization can be carried out in a slurry state, a solution state, or a gas phase state. In particular, when the polymerization is performed in a slurry state, an ethylene-based copolymer having a powder particle shape is efficiently and stably produced. Can do. Further, the solvent used for the polymerization may be any organic solvent that is generally used, and specific examples include benzene, toluene, xylene, propane, isobutane, pentane, hexane, heptane, cyclohexane, gasoline, and the like, propylene, Olefin itself such as 1-butene, 1-hexene and 1-octene can also be used as a solvent.

  The foamable biodegradable resin composition of the present invention comprises biodegradable resin (a) 99 to 50% by weight and polyethylene resin (b) 1 to 50% by weight. Here, when the biodegradable resin (a) exceeds 99% by weight (that is, the polyethylene resin (b) is less than 1% by weight), the resulting biodegradable resin composition is subjected to foam molding. However, since the foaming gas cannot be sufficiently retained, a foamed molded product having a uniform cell structure cannot be obtained. On the other hand, when the biodegradable resin (a) is less than 50% by weight (that is, the polyethylene-based resin (b) exceeds 50% by weight), even if the obtained biodegradable resin composition is subjected to foam molding, bubbles are generated. Only a molded body that does not grow sufficiently and has a low expansion ratio can be obtained, and heat resistance is poor.

  The biodegradable resin composition of the present invention includes various thermosetting resins and thermoplastic resins such as cyanate ester resins, polyimides, silicone resins, polyolefins, polyesters, polyamides, and polyphenylene oxides without departing from the object of the present invention. , Polycarbonate, polysulfone, polyetherimide, polyethersulfone, polyetherketone, polyetheretherketone, polyamideimide, polyamide elastomer, polyolefin elastomer, polyester elastomer, polyalkylene oxide, etc. can do.

  In addition, the biodegradable resin composition of the present invention includes an antioxidant, a thermal decomposition inhibitor, an ultraviolet absorber, a crystallization accelerator such as talc, a crystallization accelerator, a colorant, a flame retardant, if necessary. It contains one or more of reinforcing agents such as glass fibers and their surface treatment agents, fillers, mold release agents, plasticizers, antistatic agents, hydrolysis inhibitors, adhesion assistants, and pressure-sensitive adhesives. Also good.

  The production method of the biodegradable resin composition of the present invention is not particularly limited, and for example, various additives are added to the biodegradable resin and the polyolefin resin as necessary, and then melt-kneaded with other optional components. Can be manufactured. Melt kneading can be carried out using a kneader such as a single screw extruder, a twin screw extruder, a kneader, a Banbury mixer, etc., and the type of apparatus used and melt kneading conditions are not particularly limited, It is good to knead | mix for 1 to 30 minutes at the temperature of the range of about 120-250 degreeC in general.

  There is no restriction | limiting in particular as a foaming agent at the time of foaming the biodegradable resin composition for foaming of this invention, As a thermally decomposable foamable compound, the thermal decomposable foaming agent which decomposes | disassembles and generate | occur | produces nitrogen gas ( Azodicarbonamide, azobisisobutyronitrile, dinitrosopentamethylenetetramine, p-toluenesulfonyl hydrazide, p, p'-oxy-bis (benzenesulfonylhydrazide), etc.) Known pyrolytic foamable compounds such as inorganic foaming agents (sodium hydrogen carbonate, ammonium carbonate, ammonium hydrogen carbonate, etc.); gases such as carbon dioxide, butane, propane, etc.

  Moreover, the biodegradable resin composition for foaming of the present invention can be a foamable biodegradable resin composition containing the foaming agent.

  There is no particular limitation on the method for producing a foamed molded product using the biodegradable resin composition of the present invention, and various types of molding that are generally used depending on the type, application, shape, etc. of the desired foamed molded product. Methods and molding equipment can be used. For example, foam molded products can be produced by any molding method such as injection molding, extrusion molding, press molding, blow molding, calendar molding, casting molding, etc., and molding can also be performed by combining these molding techniques. Can do. Furthermore, it can be molded by composite molding with other polymers.

  By these molding methods, machine parts, daily necessities, miscellaneous goods, industrial parts, containers, parts for office equipment, stationery, toys, pipes, sheets, and other foam molded products of any other shape and application can be manufactured. The present invention includes these foam-molded articles produced using the biodegradable resin composition of the present invention.

  By using the biodegradable resin composition for foaming of the present invention, the foaming ratio can be easily increased in various foam molding methods, and the foam surface biodegradable resin composition and foam molding have a high-class feeling. The body can be provided.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereby.

-Measurement of molecular weight and molecular weight distribution-
The weight average molecular weight (M _w ), number average molecular weight (M _n ), and ratio of the weight average molecular weight to the number average molecular weight (M _w / M _n ) of the polyethylene resin are measured by gel permeation chromatography (GPC). did. Tosoh Co., Ltd. HLC-8121GPC / HT is used as the GPC apparatus, Tosoh Co., Ltd. TSKgel GMHhr-H (20) HT is used as the column, the column temperature is set to 140 ° C., and 1 is used as the eluent. Measurement was performed using 2,4-trichlorobenzene. A measurement sample was prepared at a concentration of 1.0 mg / ml, and 0.3 ml was injected and measured. In addition, _Mw and _Mn were calculated | required as a value of linear polyethylene conversion.

~ Measurement of density ~
The density (d) of the polyethylene resin was measured by a density gradient tube method in accordance with JIS K6760 (1995).

~ Calculation of flow activation energy ~
The activation energy (E _a ) of the flow of the polyethylene resin (b) is 150 ° C., 170 ° C., 190 using a disk-disk rheometer (manufactured by Anton Paar Co., Ltd., trade name: MCR-300). The shear storage elastic modulus G ′ and shear loss elastic modulus G ″ in the range of angular velocities of 0.1 to 100 rad / s are obtained at each temperature of ° C., the shift factor of the horizontal axis at the reference temperature of 150 ° C. is obtained, and the Arrhenius type formula Calculated by

~ Measurement of melt tension ~
The melt tension of polyethylene resin is set on a capillary viscometer (Toyo Seiki Seisakusho, trade name: Capillograph) with a barrel diameter of 9.55 mm and a die with a length of 8 mm, a diameter of 2.095 mm, and an inflow angle of 90 °. It was measured. In MS ₁₆₀ , the temperature was set to 160 ° C., the piston lowering speed was set to 10 mm / min, the stretch ratio was set to 47, and the load (mN) required for take-up was MS ₁₆₀ . When the maximum draw ratio was less than 47, the load (mN) required for taking up at the highest draw ratio that did not break was MS ₁₆₀ . The load (mN) measured by the same method with the temperature set at 190 ° C. was designated as MS ₁₉₀ .

The polyethylene resin (b) used for measurement of melt tension (MS ₁₆₀ , MS ₁₉₀ ) and flow activation energy (E _a ) was previously used as a heat-resistant stabilizer by Irganox 1010 ^™ (Ciba Specialty Chemicals Co., Ltd.). ) 1,500 ppm, Irgaphos 168 ^™ (Ciba Specialty Chemicals Co., Ltd.) with 1,500 ppm added, nitrogen was added using an internal mixer (Toyo Seiki Seisakusho Co., Ltd., trade name: Labo Plast Mill) What knead | mixed for 30 minutes at 190 degreeC and rotation speed 30rpm under airflow was used.

-Production of foam molded products-
The biodegradable resin composition pellets obtained in the examples or comparative examples were used as molding materials, and a chemical foaming agent (ADCA: azodicarbonamide) was blended at a ratio of 1.0 part by weight. Using a company-made 120-ton injection molding machine, foam molding is performed under conditions of a cylinder temperature of 190 ° C. and a mold temperature of 40 ° C. to evaluate the dispersibility of bubbles and the beauty of the molded product surface. (Dimensions: length × width × thickness = 147 mm × 97 mm × 6.2 mm) were prepared.

~ Foaming ratio ~
A 50 mm square sample is cut out from the foam produced by injection molding, the weight W2 (g) is measured, and the apparent density is calculated by the following formula in accordance with JIS K6767.

Apparent density (g / cm ³ ) = W2 / (5 × 5 × 0.62)
The expansion ratio was determined from the apparent density by the following formula.

Foaming ratio = 1 / apparent density-foam shape and bubble shape-
The appearance of the extruded foam formed using the biodegradable resin composition for foaming and the state of bubbles in the cross section were visually evaluated.

Smooth surface, foam-shaped closed cells ... ○
Uneven foam shape, open cells ... ×
-Evaluation of dispersibility of bubbles-
The center part of the test piece produced above was cut out, the cross section was observed with an optical microscope, and the dispersibility of bubbles was evaluated as follows.

○: Bubbles of 0.05 to 0.3 mm are dispersed Δ: Bubbles of 0.3 to 1 mm are dispersed ×: Bubbles of 1 mm or more are dispersed ~ Evaluation of the beauty of the molded product surface ~
The surface of the test piece produced above was observed visually, and its beauty was evaluated as follows.

    ○: No swirl mark is generated.

    Δ: A swirl mark occurs on a part of the surface.

    X: Swirl marks are generated on the entire surface, and irregularities are also observed.

Production Example 1
[Preparation of modified hectorite]
After adding 3 liters of ethanol and 100 ml of 37% concentrated hydrochloric acid to 3 liters of water, 585 g of N-methyldioleylamine (1.1 mol: product name: Armin M2O) was added to the resulting solution, A hydrochloride solution was prepared by heating to 60 ° C. 1 kg of hectorite was added to this solution. The suspension was stirred at 60 ° C. for 3 hours, and the supernatant was removed, followed by washing with 50 L of water at 60 ° C. Thereafter, 60 ° ^C., dried 10 -3 torr 24 hours, by grinding with a jet mill to obtain modified hectorite having an average particle diameter of 10.5 [mu] m.
[Preparation of production catalyst for polyethylene resin]
500 g of the modified hectorite was suspended in 3.3 liters of hexane, and 6.97 g (20.0 mmol) of dimethylsilanediylbis (cyclopentadienyl) zirconium dichloride and a hexane solution of triethylaluminum (1.18 M) 1.7. 1 liter (2 mol) was added and stirred at 60 ° C. for 3 hours. After allowing to stand and cooling to room temperature, the supernatant was taken out and washed twice with 4 liters of 1% triisobutylaluminum in hexane. The supernatant liquid after washing was extracted and made up to 5 liters with a 5% triisobutylaluminum hexane solution. Subsequently, 20% triisobutylaluminum was separately added to a suspension of diphenylmethylene (1-cyclopentadienyl) (2,7-di-tert-butyl-9-fluorenyl) zirconium dichloride (2.33 g, 3.48 mmol) in hexane (115 mL). A solution prepared by adding 79 ml of a hexane solution (0.71 M) was added and stirred at room temperature for 6 hours. The supernatant was removed by standing, washed twice with 4 liters of hexane, and hexane was added to finally obtain a catalyst slurry of 100 g / L.
[Manufacture of polyethylene resin]
In a polymerization vessel having an internal volume of 540 L, the hexane was 145 kg / hour, the ethylene was 33.0 kg / hour, the butene-1 was 1.0 kg / hour, the hydrogen was 19 NL / hour, and the polymer production amount was 30 kg / hour. The catalyst slurry prepared in [Preparation of Production Catalyst for Polyethylene Resin] was continuously supplied, and the polymerization reaction was continuously carried out while maintaining the total pressure at 3,000 kPa and the polymerization vessel internal temperature at 85 ° C. After continuously removing the slurry from the polymerization vessel and removing unreacted hydrogen, ethylene, and butene-1, a polyethylene resin powder was obtained through steps of separation and drying. Polyethylene resin pellets were obtained by melt-kneading and pelletizing the polyethylene resin powder using a 50 mm diameter single screw extruder set at 200 ° C. The density of the obtained polyethylene resin pellets was 950 kg / m ³ , and the MFR was 4.0 g / 10 min.

Production Example 2
Production Example 1 [Production of polyethylene resin] was performed in the same manner as in Production Example 1 except that the hydrogen supply amount was changed from 19 NL / hour to 12 NL / hour. The density of the obtained polyethylene resin was 950 kg / m ³ and the MFR was 2.0 g / 10 min.

Production Example 3
[Preparation of modified hectorite]
After adding 3 liters of ethanol and 100 ml of 37% concentrated hydrochloric acid to 3 liters of water, 330 g of N, N-dimethyl-octadecylamine (1.1 mol: manufactured by Lion Corporation, trade name: Armin DM18D) was added to the resulting solution. A hydrochloride solution was prepared by adding and heating to 60 ° C. To this solution, 1.0 kg of hectorite was added. The suspension was stirred at 60 ° C. for 3 hours, the supernatant was removed, and then washed with 5 L of water at 60 ° C. Thereafter, 60 ° ^C., dried 10 -3 torr 24 hours, by grinding with a jet mill to obtain modified hectorite having an average particle diameter of 10.5 [mu] m.
[Preparation of production catalyst for polyethylene resin]
500 g of the modified hectorite was suspended in 3.3 liters of hexane, and 6.97 g (20.0 mmol) of dimethylsilanediylbis (cyclopentadienyl) zirconium dichloride and a hexane solution of triethylaluminum (1.18 M) 1.7. 1 liter (2 mol) was added and stirred at 60 ° C. for 3 hours. After allowing to stand and cooling to room temperature, the supernatant was taken out and washed twice with 4 liters of 1% triisobutylaluminum in hexane. The supernatant liquid after washing was extracted and made up to 5 liters with a 5% triisobutylaluminum hexane solution. Subsequently, 20% triisobutylaluminum was separately added to a suspension of diphenylmethylene (1-cyclopentadienyl) (2,7-di-tert-butyl-9-fluorenyl) zirconium dichloride (2.33 g, 3.48 mmol) in hexane (115 mL). A solution prepared by adding 79 ml of a hexane solution (0.71 M) was added and stirred at room temperature for 6 hours. The supernatant was removed by standing, washed twice with 4 liters of hexane, and hexane was added to finally obtain a catalyst slurry of 100 g / L.
[Manufacture of polyethylene resin]
In the polymerization vessel having an internal volume of 540 L, the above-mentioned [145 kg / hour of hexane, 33.0 kg / hour of ethylene, 1.0 kg / hour of butene-1, 25 NL / hour of hydrogen and 30 kg / hour of polymer production] The catalyst slurry prepared in [Preparation of Production Catalyst for Polyethylene Resin] was continuously supplied, and the polymerization reaction was continuously carried out while maintaining the total pressure at 3,000 kPa and the polymerization vessel internal temperature at 85 ° C. After continuously removing the slurry from the polymerization vessel and removing unreacted hydrogen, ethylene, and butene-1, a polyethylene resin powder was obtained through steps of separation and drying. Polyethylene resin pellets were obtained by melt-kneading and pelletizing the polyethylene resin powder using a 50 mm diameter single screw extruder set at 200 ° C. The density of the obtained polyethylene resin pellets was 950 kg / m ³ , and the MFR was 6.0 g / 10 minutes.

Example 1
[Production of biodegradable resin composition]
Polylactic acid (Mitsui Chemicals Co., Ltd., (trade name) Lacia H-440) and the polyethylene resin obtained in Production Example 1 were dry blended at a ratio of 80:20 (% by weight), and this was screwed Using a twin screw extruder (trade name TEM-35B-102B, manufactured by Toshiba Machine Co., Ltd.) having a diameter of 37 mmφ, the mixture was melt-kneaded at a cylinder temperature of 180 ° C. to be pelletized.
[Manufacture of foam]
To 100 parts by weight of the obtained biodegradable resin composition, a chemical foaming agent comprising sodium bicarbonate and citric acid as a foaming agent was blended at a ratio of 1.0 part by weight. And the foaming magnification, the foam shape, the bubble shape, etc. were evaluated about the foaming molding produced by the injection molding method. The evaluation results of the obtained foam are shown in Table 1.

実施例２
実施例１において、ポリエチレン系樹脂の配合割合を表１に示すように変えたこと以外は、実施例１と同様に生分解性樹脂組成物、及び発泡体を作製し、評価を行った。評価結果を表１に示す。

Example 2
In Example 1, a biodegradable resin composition and a foam were produced and evaluated in the same manner as in Example 1 except that the blending ratio of the polyethylene resin was changed as shown in Table 1. The evaluation results are shown in Table 1.

Example 3
In Example 1, a biodegradable resin composition and a foam were produced and evaluated in the same manner as in Example 1 except that the polyethylene resin was changed to the resin obtained in Production Example 2. The evaluation results are shown in Table 1.

Example 4
In Example 1, a biodegradable resin composition and a foam were prepared and evaluated in the same manner as in Example 1 except that the polyethylene resin was changed to the resin obtained in Production Example 3. The evaluation results are shown in Table 1.

Example 5
In Example 1, biodegradation was performed in the same manner as in Example 1 except that polylactic acid was changed to a poly-3-hydroxybutyrate homopolymer (hereinafter referred to as PHB, manufactured by Tianan Biological Material, (trade name) ENMAT200). The resin composition and the foam were produced and evaluated. The evaluation results are shown in Table 1.

Example 6
The biodegradable resin composition in the same manner as in Example 1, except that polylactic acid was changed to polybutylene succinate (hereinafter referred to as PBS; manufactured by Showa Polymer Co., Ltd., (trade name) Bionore 1003) in Example 1. And foams were prepared and evaluated. The evaluation results are shown in Table 1.

Comparative Example 1
Except for changing the polyethylene resin in Example 1 to low density polyethylene (LDPE) produced by a commercially available high pressure method (trade name: Petrocene 203, manufactured by Tosoh, MFR = 8 g / 10 min, density = 919 kg / m ³ ). Was carried out in the same manner as in Example 1.

  The results are shown in Table 1.

Comparative Example 2
In Example 1, the polyethylene-based resin was converted into a linear low-density polyethylene (trade name: Umerit 4540F, manufactured by Ube Industries, MFR = 3.9 g / 10 min, density = 944 kg / m ³ ) produced with a commercially available metallocene catalyst. The procedure was the same as in Example 1 except for the change.

  The results are shown in Table 1.

Comparative Example 3
The same operation as in Example 1 was performed except that the amount of the polyethylene resin added was 0.9% by weight in Example 1.

  The results are shown in Table 1.

Comparative Example 4
The same operation as in Example 1 was performed except that the addition amount of the polyethylene resin in Example 1 was changed to 52% by weight.

  The results are shown in Table 1.

  The biodegradable resin composition of the present invention is excellent in dispersibility of bubbles and the beauty of the surface of a molded article, and is excellent in mechanical performance such as impact resistance and strength. It can be used very effectively for various molded products including daily necessities, miscellaneous goods, industrial parts, containers, parts for office equipment, stationery, toys, pipes, sheets, and a wide variety of other uses.

Claims (4)

The biodegradable resin (a) is 99 to 50% by weight and the polyethylene resin (b) is 1 to 50% by weight, and the polyethylene resin (b) satisfies the following (A) to (B). A biodegradable resin composition for foaming.
(A) The density (d) measured by the density gradient tube method in accordance with JIS K6760 is 920 kg / m ³ or more and 960 kg / m ³ or less.
(B) The melt tension (MS ₁₆₀ ) measured at 160 ° C. is in the range of 50 to 150 mN. The biodegradable resin composition for foaming (C) according to claim 1, wherein the polyethylene resin (b) further satisfies the following (C) to (G): The measured melt flow rate (MFR) is 1 g / 10 min or more and 20 g / 10 min or less.
(D) The number of terminal vinyls is 0.2 or less per 1,000 carbon atoms.
(E) The relationship between the melt tension (MS ₁₆₀ (mN)) measured at 160 ° C. and MFR satisfies the following formula (1).
MS ₁₆₀ > 90-130 × log (MFR) (1)
(F) The relationship between the melt tension (MS ₁₉₀ (mN)) measured at 190 ° C. and MS ₁₆₀ satisfies the following formula (2).
MS ₁₆₀ / MS ₁₉₀ <1.8 (2)
(G) The relationship between the flow activation energy (E _a (kJ / mol)) and the density satisfies the following formula (3).
_{125-0.105d <E a <88-0.055d (3} ) The foamable biodegradable resin composition (H) according to claim 1 or 2, wherein the polyethylene resin (b) further satisfies the following (H): Weight average molecular weight / number average molecular weight ( _Mw) / M _n ) is 3 or more and 10 or less. A foamed molded article comprising the biodegradable resin composition for foaming according to any one of claims 1 to 3.