JP2005281424A - Block copolymer, method for producing the same and resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a poly(α-hydroxycarboxylic acid)/polyolefin-based block copolymer excellent in impact resistance and excellent also in compatibility of a poly(α-hydroxycarboxylic acid)-based resin with a polyolefin-based resin and to provide a resin composition having good appearance and excellent in thermal and mechanical physical properties. <P>SOLUTION: The poly(α-hydroxycarboxylic acid)/polyolefin-based block copolymer is composed of a poly(α-hydroxycarboxylic acid) component and a polyolefin component and comprises both components in a mass ratio of (10/90) to (90/10). The resin composition is obtained by formulating 0.1-20 pts.mass of the block copolymer with 100 pts.mass total amount of (A) 10-90 pts.mass poly(α-hydroxycarboxylic acid)-based resin with (B) 90-10 pts.mass polyolefin-based resin. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a block copolymer comprising a poly (α-hydroxycarboxylic acid) component and a polyolefin component, a method for producing the same, and a resin composition containing this as a compatibilizing agent.

  In recent years, with the growing awareness of the environment, there is a growing movement to prevent petroleum resource depletion and global warming by replacing petroleum-derived general-purpose resins with plant-derived resins represented by polylactic acid. However, polylactic acid alone, which is a representative example of poly (α-hydroxycarboxylic acid), is insufficient in impact resistance, heat resistance, durability, and the like, and various attempts have been made to combine it with other resins. For example, Patent Document 1 proposes a method of improving impact strength while maintaining transparency by mixing an aliphatic polyester mainly composed of polylactic acid and syndiotactic polypropylene. However, the invention described in Patent Document 1 has room for improvement in physical properties such as heat resistance, durability, and moldability as a result of a decrease in crystallinity with emphasis on the transparency of the resin composition.

  On the other hand, the present applicant first comprises a biodegradable polyester represented by polylactic acid and a polyolefin resin, a resin composition excellent in heat resistance, impact resistance, durability, and moldability, its production method, and A technique related to a resin composition was proposed (Japanese Patent Application No. 2003-350869). However, since the resin composition obtained here has a clear sea-island structure peculiar to incompatible systems, surface unevenness is likely to occur, and it is not always satisfactory in the surface appearance of the molded product, and there is room for improvement in compatibility. was there.

  In general, it is known that the addition of a block copolymer of both components is effective for improving the compatibility of incompatible resins. Patent Document 2 discloses a block copolymer composed of polylactic acid and polyhydrocarbon and a method for producing the same, but this composition is intended to impart hydrophobicity to polylactic acid, When the polyhydrocarbon copolymerization ratio is 5% as shown in the examples, the effect as a compatibilizer of the poly (α-hydroxycarboxylic acid) resin and the polyolefin resin is poor.

  On the other hand, as a method of imparting impact resistance to polylactic acid, a method of copolymerizing flexible components such as polyether and aliphatic polyester has been conventionally known. However, impact resistance can be improved by copolymerizing a polyolefin component. There was no knowledge that could be improved.

JP-A-10-251498 JP 2000-44659 A

  The present invention is intended to solve the above-described problems, and is excellent in compatibility between a poly (α-hydroxycarboxylic acid) -based resin and a polyolefin-based resin, and itself excellent in impact resistance. (Α-Hydroxycarboxylic acid) / polyolefin block copolymer, and a resin composition comprising a poly (α-hydroxycarboxylic acid) resin and a polyolefin resin containing the same.

  As a result of intensive studies to solve the above problems, the present inventors have conducted ring-opening polymerization of an α-hydroxycarboxylic acid cyclic dimer in the presence of a polyolefin having a hydroxyl group, or α-hydroxycarboxylic acid or It has been found that a poly (α-hydroxycarboxylic acid) / polyolefin block copolymer can be provided by polycondensation of the oligomer, and this has excellent impact resistance, and a poly (α-hydroxycarboxylic acid) resin. And found an excellent effect as a compatibilizer for polyolefin resins, and reached the present invention.

That is, the gist of the present invention is as follows.
First, a poly (α-hydroxycarboxylic acid) / polyolefin block copolymer comprising a poly (α-hydroxycarboxylic acid) component and a polyolefin component, wherein the constituent mass ratio of both components is 10/90 to 90/10 Coalesced,
The second is a poly (α-hydroxycarboxylic acid) / polyolefin block copolymer in which the constituent mass ratio of the poly (α-hydroxycarboxylic acid) component and the polyolefin component is particularly in the range of 15/85 to 65/35. ,
Third, a poly (α-hydroxycarboxylic acid) / polyolefin block copolymer having an Izod impact strength of 30 J / m or more,
Fourth, ring-opening polymerization of an α-hydroxycarboxylic acid cyclic dimer or polycondensation of α-hydroxycarboxylic acid or an oligomer thereof in the presence of a polyolefin having an average number of hydroxyl groups in one molecule of 0.5 or more. A process for producing a poly (α-hydroxycarboxylic acid) / polyolefin block copolymer,
Fifth, (A) 10 to 90 parts by mass of a poly (α-hydroxycarboxylic acid) resin and (B) 90 to 10 parts by mass of a polyolefin resin, and (C) the block copolymer 0. A resin composition comprising 1 to 20 parts by mass,
Sixth, in the resin composition, poly (α-hydroxycarboxylic acid) (A) forms an island phase, and the maximum diameter of the dispersed phase is 20 μm or less,
Seventh, a molded body obtained by molding the resin composition.

  According to the present invention, a poly (α-hydroxycarboxylic acid) / polyolefin block copolymer having excellent impact resistance is provided, and further, when used, a poly (α-hydroxycarboxylic acid) resin and a polyolefin resin are used. The compatibility of both components of the resin composition comprising the above is improved, the surface appearance of various molded products is remarkably improved, and the impact resistance is remarkably improved. Furthermore, it is possible to achieve both of these performances without impairing heat resistance and durability.

  Hereinafter, the present invention will be described in detail.

  First, a poly (α-hydroxycarboxylic acid) / polyolefin block copolymer (hereinafter simply referred to as “block copolymer”) will be described.

  Examples of the poly (α-hydroxycarboxylic acid) component in the block copolymer of the present invention include polylactic acid, poly (glycolic acid), and mixtures or copolymers thereof, with polylactic acid being most preferred. The polylactic acid may be poly (L-lactic acid), a mixture of poly (D-lactic acid) or a copolymer. Although L body / D body ratio is not specifically limited, For example, it can use in the range of 0.5 / 99.5-99.5 / 0.5.

  As long as the characteristics of the poly (α-hydroxycarboxylic acid) component are not significantly impaired, other aliphatic polyester components may be copolymerized, and poly (ε-caprolactone), poly (δ -Valerolactone), poly (3-hydroxybutyric acid), poly (3-hydroxyvaleric acid), poly (3-hydroxycaproic acid), polyethylene succinate, polybutylene succinate, polyethylene adipate, polybutylene adipate, polybutylene succin Nate terephthalate, polybutylene adipate terephthalate, and the like.

  The types of polyolefin components in the block copolymer include poly (α-olefins) such as polyethylene, polypropylene, poly (4-methylpentene-1), polybutylene and polyisobutylene, polydienes such as polybutadiene and polyisoprene, and polystyrenes. And hydrogenated products thereof, and cycloolefin resins such as poly (cyclopentadiene). Among them, polybutadiene, polyisoprene, and hydrogenated products thereof are preferable. As long as the properties of the polyolefin component are not significantly impaired, other components may be copolymerized. Examples of other copolymerization components include vinyl acetate, acrylonitrile, acrylic acid and its salts or esters, methacrylic acid and its Examples thereof include salts or esters and maleic anhydride.

  As a method for producing the block copolymer of the present invention, a polyolefin resin having the above-described polyolefin component as a main skeleton and having a hydroxyl group in the molecule is used as a raw material, and an α-hydroxycarboxylic acid cyclic dimer is present in this presence. Examples thereof include ring-opening polymerization or polycondensation of α-hydroxycarboxylic acid or its oligomer.

  In the polyolefin resin used as the raw material for producing the block copolymer, the position of the hydroxyl group is not particularly limited, and may be in the polyolefin main chain or at the terminal, but the terminal is preferable. Examples of the method for introducing a hydroxyl group include a method of copolymerizing a small amount of a monomer having a hydroxyl group such as 2-hydroxyethyl vinyl ether or 2-hydroxyethyl methacrylate, a monomer having a functional group that can be converted into a hydroxyl group by post-treatment such as vinyl acetate or glycidyl methacrylate. A method of converting a hydroxyl group into a hydroxyl group after copolymerization of a small amount, a method of converting an epoxy group into a hydroxyl group after epoxidizing a polyolefin having an unsaturated bond, a hydrocarbon capable of anion polymerization such as dienes and styrenes Examples include a method in which a monomer is polymerized with a metal alkoxide initiator and then neutralized to convert the terminal to a hydroxyl group. The average number of hydroxyl groups in one molecule of the polyolefin resin is preferably 0.5 or more, more preferably 1 to 10, more preferably 1.2 to 5, and particularly preferably 1.5 to 3. If the average number of hydroxyl groups in one molecule is less than 0.5, a block copolymer cannot be obtained, or even if it is obtained, the efficiency decreases, which is not preferable. On the other hand, when the average number of hydroxyl groups exceeds 10, the block copolymer becomes a branched polymer and the compatibility improving effect intended by the present invention tends to be reduced. The average number of hydroxyl groups per molecule of polyolefin can be calculated by measuring the hydroxyl value according to JIS-K1557 and dividing this by the number average molecular weight in terms of polystyrene measured by GPC.

  The number average molecular weight of the polyolefin used as the raw material for the block copolymer is preferably 500 to 50,000, more preferably 1,000 to 10,000, and still more preferably 2,000 to 5,000. When the molecular weight is less than 500, the effect as a compatibilizing agent is hardly exhibited, and when the molecular weight exceeds 50,000, the efficiency of block copolymerization is lowered, which is not preferable.

  Commercially available polyolefins suitable for production of the block copolymer of the present invention include, for example, Mitsubishi Chemical Polytail H, Polytail HA, Nippon Soda G-3000, GI-3000, Idemitsu Petrochemical R-45HT, Arakawa Chemical Examples include Alcon KR-1841 manufactured by Alcon.

  Examples of the α-hydroxycarboxylic acid cyclic dimer used as a raw material for the poly (α-hydroxycarboxylic acid) component in the block copolymer include L-lactide, D-lactide, DL-lactide, and glycolide. It may be a mixture of

  As the catalyst used in the ring-opening polymerization of the α-hydroxycarboxylic acid cyclic dimer, a general cyclic ester ring-opening polymerization catalyst or a transesterification catalyst is used. Specifically, tin-based catalysts such as tin octylate, tin dimethylmaleate, tin lactate, tin dilaurate, tin distearate, tin chloride, and tin powder, aluminum trisacetylacetonate, aluminum triisopropoxide, aluminum A metal catalyst such as an aluminum catalyst such as a len-type complex, tetraisopropyl titanate, tetrabutyl titanate, antimony oxide, germanium oxide, and zinc acetate is used, and a tin catalyst and an aluminum catalyst are particularly preferably used. The amount of the catalyst added is preferably 0.01 to 0.5 parts by mass, more preferably 0.02 to 0.1 parts by mass with respect to 100 parts by mass of lactide.

  The temperature of the ring-opening polymerization is preferably 150 to 230 ° C, more preferably 160 to 210 ° C, and further preferably 170 to 200 ° C. The polymerization time is preferably 0.5 to 20 hours, and more preferably 1 to 10 hours. The pressure during the polymerization is not particularly limited, but in general, the polymerization is carried out at normal pressure or under pressure in an inert gas atmosphere such as nitrogen gas, and after the polymerization reaches equilibrium, the pressure is reduced to unreacted α-hydroxy. The block copolymer of the present invention can be obtained by distilling off the carboxylic acid cyclic dimer.

  As the catalyst used in the polycondensation of α-hydroxycarboxylic acid or its oligomer, the above-mentioned tin-based and aluminum-based metal catalysts can be used, and a protonic acid catalyst such as toluenesulfonic acid or phosphoric acid can be used in combination. Good. The addition amount of the catalyst is preferably 0.02 to 1 part by mass, more preferably 0.05 to 0.5 part by mass with respect to 100 parts by mass of α-hydroxycarboxylic acid or oligomer thereof. In addition, a high molecular weight body can be obtained in a shorter time by using a solvent in the polycondensation. Preferred solvents include diphenyl ether, dimethyl benzyl ether, benzyl phenyl ether, toluene, xylene and the like. The polymerization temperature is preferably 140 to 220 ° C, more preferably 150 to 200 ° C. The polymerization time is preferably 1 to 100 hours, more preferably 2 to 50 hours. The pressure during the polymerization is preferably a reduced pressure condition.

  As a method for producing a block copolymer, a poly (α-hydroxycarboxylic acid) resin is further depolymerized to form an α-hydroxycarboxylic acid oligomer in the presence of a hydroxyl group-containing polyolefin under normal pressure or pressurized conditions, A method in which this is again polycondensed under reduced pressure can be employed.

  The Izod impact strength according to ASTM-256 of the block copolymer of the present invention needs to be 30 J / m, preferably 40 J / m or more, more preferably 50 J / m. If the Izod impact strength is less than 30 J / m, it cannot be said to be a practical impact resistance improving effect.

  Although the molecular weight of the block copolymer of this invention is not specifically limited, 1,000-500,000 are preferable as a weight average molecular weight, and 2,000-200,000 are more preferable. When the weight average molecular weight is less than 1,000, the impact resistance improving effect is poor, and the effect as a compatibilizing agent described later is also poor. When the weight average molecular weight exceeds 500,000, it is discharged from the polymerization apparatus. It becomes difficult, the molding processability is inferior, and the effect as a compatibilizing agent is hardly obtained.

  A chain extender may be used to adjust the molecular weight of the block copolymer. As the chain extender, a compound containing two or more isocyanate groups or glycidyl groups, which are functional groups capable of reacting with a hydroxyl group, is preferably used. Specific examples include hexamethylene diisocyanate and tolylene diisocyanate. And diglycidyl compounds such as polyethylene glycol diglycidyl ether and neopentyl glycol diglycidyl ether. When the number of functional groups capable of reacting with a hydroxyl group is 3 or more, the block copolymer may be gelled depending on the method of use. Therefore, it is preferable to use two functional groups.

  Next, the resin composition of the present invention using the block copolymer as a compatibilizing agent will be described. When the block copolymer (C) described above is blended in a resin composition comprising a poly (α-hydroxycarboxylic acid) resin (A) and a polyolefin resin (B), the components (A) and (B) This produces remarkable effects such as improving the compatibility and improving the surface appearance of the molded body.

  Examples of the poly (α-hydroxycarboxylic acid) resin (A) include poly (L-lactic acid), poly (D-lactic acid), poly (glycolic acid), and a mixture or copolymer thereof. Other components may be copolymerized as long as the characteristics of the component (-hydroxycarboxylic acid) are not significantly impaired. Other copolymer components include poly (ε-caprolactone), poly (δ-valerolactone), poly (3-hydroxybutyric acid), poly (3-hydroxyvaleric acid), poly (3-hydroxycaproic acid), polyethylene Examples thereof include succinate, polybutylene succinate, polyethylene adipate, polybutylene adipate, polybutylene succinate terephthalate, polybutylene adipate terephthalate and the like. When polylactic acid is used as the poly (α-hydroxycarboxylic acid) resin, the L-form / D-form ratio is 90/10 to 99.5 / 0.5 in order to ensure the crystallinity necessary for maintaining heat resistance. It is preferable that it is the range of these.

  The poly (α-hydroxycarboxylic acid) resin (A) may have a crosslinked or branched structure introduced therein. As a method of introducing a crosslinked or branched structure, a method of adding an organic peroxide, a method of using an organic peroxide in combination with a radical polymerizable compound, a method of irradiating radiation, and polylactic acid in the presence of a polyfunctional initiator are used. The manufacturing method etc. are mentioned. Examples of the peroxide include dibutyl peroxide and bis (butylperoxy) diisopropylbenzene. Examples of the radical polymerizable compound include glycidyl methacrylate, ethylene glycol dimethacrylate, and polyethylene glycol dimethacrylate. Examples of the polyfunctional initiator include ethylene-vinyl alcohol copolymer, partially saponified polyvinyl alcohol, and cellulose diacetate.

  The weight average molecular weight of the poly (α-hydroxycarboxylic acid) -based resin (A) is preferably 50,000 to 1,000,000, more preferably 100,000 to 500,000, and 150,000 to 300,000. Further preferred. Moreover, as a melt flow index (MFI) measured by 190 degreeC and load 21.2N, the range of 0.1-50 is preferable, 0.2-40 are more preferable, and 0.5-30 are more preferable.

  On the other hand, as the polyolefin resin (B), poly (α-olefin) such as polyethylene, polypropylene, polybutylene, polyisobutylene and poly (4-methylpentene-1), polydiene such as polybutadiene and polyisoprene, and hydrogen thereof. Examples thereof include additives, hydrogenated products of polystyrenes, cycloolefin resins, and the like. Among these, polypropylene and polyethylene are preferable, and polypropylene is most preferable. The polyolefin resin may be partially crosslinked with an organic peroxide, partially chlorinated, or a copolymer with vinyl acetate, acrylic acid, methacrylic acid, maleic anhydride, etc. It doesn't matter.

  The mass ratio of the poly (α-hydroxycarboxylic acid) resin (A) and the polyolefin resin (B) needs to be A / B = 10/90 to 90/10, preferably A / B = 15/85 to 65/35, more preferably A / B = 20/80 to 60/40. When B is less than 10% by mass, the effect of adding a polyolefin-based resin is not observed, and improvement in physical properties such as impact strength becomes insufficient. When A is less than 10% by mass, it is difficult to say that the resin composition is environmentally friendly.

  The blending ratio of the block copolymer (C) needs to be 0.1 to 20 parts by mass with respect to 100 parts by mass in total of the above component (A) and component (B), and 0.5 to 15 Mass parts are more preferable, 1-10 mass parts is still more preferable, and it is most preferable to set it as 2-7 mass parts. When (C) is less than 0.1 part by mass, the effect of improving the compatibility of components (A) and (B) is poor, and when it exceeds 20 parts by mass, heat resistance is insufficient due to the influence of the olefin component in the block copolymer. It becomes.

  In the resin composition of the present invention, it is preferable that the poly (α-hydroxycarboxylic acid) resin (A) is an island phase and the polyolefin resin (B) is a sea phase. In this case, the maximum diameter of the poly (α-hydroxycarboxylic acid) -based resin dispersed phase is preferably 20 μm or less, more preferably 15 μm or less, and further preferably 10 μm or less. When the maximum diameter of the dispersed phase exceeds 20 μm, the surface appearance of the molded article is impaired, and heat resistance and impact resistance tend to be lowered.

  To determine which component (A) or (B) in the resin composition is in the dispersed phase and to measure the maximum diameter of the dispersed phase, observe the surface or cross section of the molded body with a scanning or transmission electron microscope. Can be done. At this time, when the poly (α-hydroxycarboxylic acid) component is dissolved in a solvent such as chloroform or methylene chloride, the structure can be observed more clearly. For example, the imaging field of view is 300 μm × 400 μm at an imaging magnification of 300 times. The maximum dispersion diameter can be measured by performing the above.

  In the resin composition of the present invention, the pigment, heat stabilizer, antioxidant, weathering agent, end-capping agent, flame retardant, plasticizer, lubricant, mold release agent, charging, etc. Inhibitors, fillers and the like may be added. As heat stabilizers and antioxidants, for example, hindered phenols, phosphorus compounds such as phosphite, hindered amines, sulfur compounds, copper compounds, alkali metal halides or mixtures thereof can be used. Examples of the terminal blocking agent include isocyanate, carbodiimide, oxazoline, and epoxy compound. Inorganic fillers include mica, talc, calcium carbonate, zinc carbonate, wollastonite, silica, alumina, magnesium oxide, calcium silicate, sodium aluminate, calcium aluminate, sodium aluminosilicate, magnesium silicate, glass balloon, carbon Examples thereof include black, zinc oxide, antimony trioxide, zeolite, hydrotalcite, metal fiber, metal whisker, ceramic whisker, potassium titanate, boron nitride, graphite, glass fiber, and carbon fiber. Examples of the organic filler include natural products such as starch, cellulose fine particles, wood powder, okara, fir shell, bran, kenaf, and modified products thereof.

  In addition, a swellable layered silicate may be added for the purpose of further improving the heat resistance of the resin composition of the present invention or improving the crystallization speed, moldability and the like. The addition amount is not particularly limited, but is suitably 0.1 to 20 parts by mass per 100 parts by mass of the total of the poly (α-hydroxycarboxylic acid) resin and the polyolefin resin. The swellable layered silicate dispersed in the resin has an interlayer distance of 20 mm (2 nm) or more. Examples of the swellable layered silicate include smectite, vermiculite, and swellable fluorinated mica. Examples of smectites include montmorillonite, beidellite, hectorite, and saponite. Examples of the swellable fluorine mica include Na-type fluorine tetrasilicon mica, Na-type teniolite, Li-type teniolite, and the like. These swellable layered silicates can be pretreated with an organic cation as necessary in order to improve the dispersibility in the resin component. Examples of the organic cation include protonated products of primary to tertiary amines, quaternary ammonium, pyridinium, imidazolium, and organic phosphonium. Furthermore, in order to improve the dispersibility of the swellable layered silicate in the resin composition, it is preferable to add to the poly (α-hydroxycarboxylic acid) resin in advance.

  As a method for producing the resin composition of the present invention, using a general extruder such as a twin screw extruder, a poly (α-hydroxycarboxylic acid) resin (A), a polyolefin resin (B) and a block copolymer are used. There is a method of melt-kneading the polymer (C).

  The method of blending the above-mentioned heat stabilizer, antioxidant, plasticizer, filler, swellable layered silicate, etc. with the resin composition of the present invention is not particularly limited, and is added during the production of the block copolymer (C). Alternatively, they may be mixed during the melt kneading of the components (A) to (C).

  The resin composition of the present invention can be formed into a molded body using a general molding method. In particular, in the injection molding method, the mold temperature range required for obtaining a molded product having heat resistance is wider than before, and the injection molding cycle is shortened accordingly, and the productivity is remarkably improved. For example, conventionally, when producing a molded product having heat resistance with a single polylactic acid, it was necessary to set the mold temperature to 100 ° C. or higher. However, in the resin composition of the present invention, the mold temperature is 100 ° C. or higher. Needless to say, even when the temperature is lower than 100 ° C., the same degree of heat resistance can be obtained. In particular, injection molding can be preferably performed in the range of 50 ° C. to 90 ° C., and the range of 60 to 90 ° C. is still more preferable.

  As a molded body using the resin composition of the present invention, it is processed as a sheet, a foamed sheet, a tube, or a pipe by an extrusion molding method, cards such as credit cards, underlays, clear files, straws, agriculture / horticulture / Can be applied to industrial hard / soft pipes or pipe covers. Furthermore, these sheets are vacuum-formed, pressure-formed, and deep-drawn, such as vacuum-pressure-formed, and punched-out, etc., so that food containers, agricultural / horticultural / industrial containers, various miscellaneous goods, blister pack containers, In addition, press-through pack containers, folding cushioning materials, various building materials, various packings, partition plates and signs, bulletin boards, automobile interior materials, mannequins, shoe soles, cap collars, various core materials, and the like can be manufactured.

  The form of the injection-molded product produced by the injection molding method is not particularly limited. Specific examples include dishes, bowls, bowls, chopsticks, spoons, forks, knives, trays, etc., fluid containers (dairy products) Drinking cups and beverage bottles such as beverages and soft drinks and alcoholic beverages, soy sauce, sauces, mayonnaise, ketchup, containers for condiments such as edible oil, shampoo and rinse containers, cosmetic containers, agricultural chemical containers, etc. ), Container caps, rulers, writing instruments, clear cases, CD cases, chairs and other office supplies, containers and other storage containers, kitchen triangle corners, trash cans, washbasins, toothbrushes, combs, hangers and other daily necessities, fasteners and buttons Apparel related products such as flower pots, nursery pots and other agricultural and horticultural materials, plastic toys, air conditioner panels, refrigerator trays, personal computers, mobile phones, etc. Various electric appliances for the resin parts of the casing or the like, bumper, instrument panel, automotive plastic parts such as door trim, fishing supplies, such as a rod, lures, sporting goods, such as various kinds of racket-protector, various building materials, and the like.

  In the present invention, the ring-opening polymerization of the α-hydroxycarboxylic acid cyclic dimer is initiated from the hydroxyl group of the polyolefin, or polycondensation between the hydroxyl group of the polyolefin and the carboxyl group of the α-hydroxycarboxylic acid or its oligomer is used as a poly ( An α-hydroxycarboxylic acid) / polyolefin block copolymer is obtained. And the impact resistance is improved due to the presence of the flexible polyolefin block component, and it is assumed that the compatibility of the poly (α-hydroxycarboxylic acid) resin and the polyolefin resin is improved by having two block components. Is done.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited only to an Example.

The measuring methods used for the evaluation of the synthesis examples, examples and comparative examples are as follows.
(1) Weight average molecular weight of block copolymer:
Using a gel permeation chromatography (GPC) apparatus (manufactured by Shimadzu Corporation) equipped with a differential refractive index detector, tetrahydrofuran was measured at 40 ° C. as an eluent and evaluated in terms of standard polystyrene. The sample was dissolved in a small amount of chloroform, diluted with tetrahydrofuran, and the soluble content was measured.
(2) Melt flow index (MFI):
According to JIS-K7210, measurement was performed at a load of 190.degree. C. and 21.2 N (2.16 kg) from the conditions in Appendix A Table. The unit is g / 10 minutes.
(3) Impact strength:
According to ASTM-256, a notched Izod impact strength was measured for a 65 mm × 12 mm × 3 mm test piece.
(4) Thermal deformation temperature:
According to ASTM-648, the heat distortion temperature was measured with a load of 0.48 MPa for a test piece of 125 mm × 12 mm × 3 mm.
(5) Durability:
A 125 mm x 12 mm x 3 mm test piece is subjected to a high temperature humidification process at 60 ° C x 95% RH x 10 days in a thermo-hygrostat, and a bending test according to ASTM-790 is performed before and after the treatment. The bending strength retention before and after was used as an index of durability.
(6) Microstructure:
The resin pellet or injection-molded piece was cut or sliced into chloroform to dissolve the polylactic acid component, which was observed with a scanning electron microscope, and the dispersion diameter of the eluted polylactic acid phase was observed.
(7) Appearance:
○ when there are no defects such as sink marks, blistering, and peeling on the surface of the injection molded piece, △ when there are defective spots such as sink marks, blistering, and peeling on the surface of the molded piece, sink marks on the surface of the molded piece, There were defects such as blistering and peeling, and the case of apparently poor appearance was evaluated as x.

Resins used in Examples and Comparative Examples are as follows.
(1) Poly (α-hydroxycarboxylic acid) resin A: polylactic acid (Natural Works manufactured by Cargill Dow, weight average molecular weight 200,000, D-form 1%)
B: Polylactic acid (Natural Works manufactured by Cargill Dow, weight average molecular weight 120,000, D-form 1%)
C: polylactic acid modified product (100 parts by mass of B melted and kneaded together with 0.1 parts by mass of polyethylene glycol dimethacrylate and 0.2 parts by mass of di-t-butyl peroxide. MFI = 1.0)
D: Polylactic acid modified product (A96 parts by mass, Somasif MEE manufactured by Co-op Chemical, 4 parts by mass of synthetic fluorine mica treated with bishydroxyethyldodecylmethylammonium) melt-kneaded with a twin screw extruder, MFI = 4.5 .)
(2) Polyolefin resin X: Polypropylene (manufactured by Chisso, MFI = 2.3)
Y: Polypropylene (manufactured by Chisso, MFI = 4.2)

Example 1
60 parts by mass of L-lactide (manufactured by Musashino Chemical Co., 4 mol% D-form) and hydrogenated polybutadiene containing hydroxyl group (polytail H produced by Mitsubishi Chemical, number average molecular weight 2,700, average number of hydroxyl groups per molecule: 2.3 ) 40 parts by mass were charged into a polymerization can and the system was purged with nitrogen, and then the temperature was raised. When the internal temperature reached 190 ° C. and the contents were dissolved, 0.02 part by mass of tin octylate catalyst was added, and polymerization was carried out for 1 hour. To this, 2 parts by mass of hexamethylene diisocyanate was added dropwise over 0.5 hours, and the reaction was further continued for 0.5 hours to obtain a colorless and transparent resin.

Example 2
Example 1 except that the polyolefin component was a hydroxyl group-containing hydrogenated polybutadiene (Mitsubishi Chemical Polytail HA, number average molecular weight 2,000, average number of hydroxyl groups per molecule: 1.8) and 3 parts by mass of hexamethylene diisocyanate. Polymerization was carried out in the same manner as above to obtain a translucent resin.

Example 3
80 parts by mass of L-lactide and 20 hydroxyl group-containing alicyclic saturated hydrocarbons (Alcon KR-1841 by Arakawa Chemical, number average molecular weight 650, average number of hydroxyl groups per molecule: 1.8) instead of hydrogenated polybutadiene Polymerization was carried out in the same manner as in Example 1 except that 4 parts by mass of hexamethylene diisocyanate was added to obtain a colorless and transparent resin.

Example 4
Polymerization was performed in the same manner as in Example 1 except that 80 parts by mass of L-lactide, 20 parts by mass of hydroxyl-containing hydrogenated polybutadiene, and 1 part by mass of hexamethylene diisocyanate were obtained to obtain a colorless and transparent resin.

Example 5
60 parts by mass of polylactic acid (Cargildau Nature Works 4031DK) was melted at 220 ° C., 1.5 parts by mass of succinic acid was added thereto, and depolymerization was performed for 2 hours. Thereafter, the temperature was lowered to 180 ° C., 40 parts by mass of a hydroxyl group-containing hydrogenated polybutadiene (polytail H manufactured by Mitsubishi Chemical, number average molecular weight 3200) was added, and polycondensation was performed for 20 hours under reduced pressure to obtain a yellow transparent resin. .

Comparative Example 1
Polymerization was carried out in the same manner as in Example 1 except that 95 parts by mass of L-lactide, 5 parts by mass of hydroxyl-containing hydrogenated polybutadiene, and 0.25 part by mass of hexamethylene diisocyanate were obtained to obtain a colorless and transparent resin.

Comparative Example 2
A white resin was obtained by performing polymerization in the same manner as in Example 1 except that the polyolefin component was polypropylene resin X. Since GPC was not completely dissolved in a predetermined solvent, GPC measurement was not performed.

Reference Example Polymerization was carried out in the same manner as in Example 1 using 100 parts by mass of L-lactide and 0.02 parts by mass of ethylene glycol without using a hydroxyl group-containing hydrogenated polybutadiene.

  Table 1 shows the weight average molecular weight and Izod impact strength of each resin obtained in Examples 1 to 5, Comparative Examples 1 and 2 and Reference Example. In addition, the test piece was used under the conditions of a cylinder set temperature of 190 ° C., a mold temperature of 10 ° C., an injection pressure of 100 MPa, an injection time of 20 seconds, and a cooling time of 80 seconds using an injection molding machine (IS-80G manufactured by Toshiba Machine). Obtained by injection molding.

Examples 6-14, Comparative Examples 3-7
A polylactic acid / polyolefin copolymer obtained in Examples 1 to 5 and Comparative Examples 1 and 2 was dry blended with a predetermined amount of polylactic acid resin and polyolefin resin, and a twin-screw extruder (PCM-30 made by Ikegai) , 30 mmφ) was melt kneaded at 190 ° C. and 150 rpm to obtain a resin composition. Table 2 shows the evaluation results of the resin composition. In the test piece injection molding, the same conditions as in Examples 1 to 5 and Comparative Examples 1 and 2 were used except that the mold temperature was changed to 120 ° C.

  In each of Examples 1 to 5, a block copolymer having excellent impact resistance could be obtained. On the other hand, since the amount of polyolefin resin was small in Comparative Example 1, the impact strength was not improved. In Comparative Example 2, since the polyolefin component and the polylactic acid component did not form a block copolymer, the transparency was inferior, and the impact strength was low as compared with Examples 1-2.

Further, in Examples 6 to 14 of the resin composition using the block copolymer as the compatibilizing agent, all of the dispersions of the polylactic acid resin were compared with Comparative Examples 3, 6, and 7 in which the compatibilizing agent was not used. The diameter was reduced and the impact strength was improved. At this time, the heat distortion temperature and durability were similar or slightly increased. On the other hand, in Comparative Examples 4 and 5, since the resin component outside the range of the present invention was used, the effect of improving the physical properties due to the addition was poor.

Claims (7)

  A poly (α-hydroxycarboxylic acid) / polyolefin block comprising a poly (α-hydroxycarboxylic acid) component and a polyolefin component, wherein the constituent mass ratio of both components is 10/90 to 90/10 Polymer.   2. The poly (α-hydroxycarboxylic acid) / polyolefin block according to claim 1, wherein the constituent mass ratio of the poly (α-hydroxycarboxylic acid) component and the polyolefin component is 15/85 to 65/35. Polymer.   The poly (α-hydroxycarboxylic acid) / polyolefin block copolymer according to claim 1 or 2, wherein the Izod impact strength is 30 J / m or more.   It is characterized by ring-opening polymerization of an α-hydroxycarboxylic acid cyclic dimer or polycondensation of α-hydroxycarboxylic acid or an oligomer thereof in the presence of a polyolefin having an average number of hydroxyl groups in one molecule of 0.5 or more. A process for producing a poly (α-hydroxycarboxylic acid) / polyolefin block copolymer according to any one of claims 1 to 3.   A total of 100 parts by mass of (A) 10-90 parts by mass of a poly (α-hydroxycarboxylic acid) -based resin and (B) 90-10 parts by mass of a polyolefin-based resin, and (C) any one of claims 1 to 3. A resin composition comprising 0.1 to 20 parts by mass of a block copolymer.   The resin composition according to claim 5, wherein the poly (α-hydroxycarboxylic acid) (A) forms an island phase, and the maximum diameter of the dispersed phase is 20 μm or less. The molded object obtained by shape | molding the resin composition of Claim 5 or 6.