KR20150063367A

KR20150063367A - Method for producing block copolymer

Info

Publication number: KR20150063367A
Application number: KR1020157005412A
Authority: KR
Inventors: 마사유키 히로타; 고우헤이 야마무라; 준 사카모토
Original assignee: 도레이 카부시키가이샤
Priority date: 2012-09-24
Filing date: 2013-07-31
Publication date: 2015-06-09
Also published as: JPWO2014045717A1; CN104619745A; JP6119608B2; WO2014045717A1

Abstract

The present invention provides a process for producing a polylactic acid based block copolymer having a low residual lactide. Characterized in that a polylactic acid resin, a resin having at least one hydroxyl group in the molecule (hereinafter, a resin having at least one hydroxyl group in the molecule is referred to as a resin (A)) and an ester exchange catalyst are melted at normal pressure. And a method for producing a block copolymer of a lactic acid resin and a resin (A).

Description

METHOD FOR PRODUCING BLOCK COPOLYMER < RTI ID = 0.0 >

The present invention relates to a polylactic acid resin, a resin having at least one hydroxyl group in the molecule, and an ester exchange resin as a preparation process for a block copolymer comprising a polylactic acid resin and a resin having at least one hydroxyl group in a molecule Characterized in that the catalyst is melted at atmospheric pressure.

Recently, environmental consciousness has increased, and there is concern about the problem of soil pollution caused by the disposal of plastic products and global warming, which is caused by the increase of carbon dioxide due to the incineration of the same product. As countermeasures against electrons, a biodegradable resin which is completely decomposed into carbon dioxide molecules and water molecules under an environment in soil is synthesized as a raw material for biologically derived materials such as plants as a countermeasure against the latter, and a new carbon dioxide load Research and development on biomass resins which are not used in the field of biomass are being actively carried out.

The polylactic acid resin has been attracting attention as being suitable for both of them and being relatively advantageous in terms of cost. When the polylactic acid resin alone is used, flexibility is insufficient. Therefore, in applications such as agricultural multi-films, shopping bags, packaging wrap films and stretch films, the use of polylactic acid copolymers and flexibility by addition of plasticizers are examined .

The polylactic acid-based block copolymer can be used as a flexible resin by being mixed with the polylactic acid resin alone or in combination with the polylactic acid resin. In particular, when mixed with a polylactic acid resin, the block copolymer can function as a plasticizer. For example, the plasticizer comprising the polylactic acid-polyether block copolymer described in Patent Document 1 is effective in preventing blotting of the polylactic acid segment and contributing to the plasticization of the polylactic acid in the polyether segment. Therefore, And is superior in bleed-out resistance as compared with a plasticizer for use as a curable resin.

In the method for producing these polylactic acid block copolymers, ring-opening polymerization of a cyclic lactone chain of lactic acid is generally carried out using a hydroxyl group of a resin having at least one hydroxyl group in the molecule as a starting point as disclosed in Patent Document 1. As another method, there is a method in which a polylactic acid resin and a resin having at least one hydroxyl group in a molecule are melted as described in Patent Document 2, and then an ester exchange catalyst is added to effect transesterification reaction under reduced pressure. A process for producing a lactic acid based block copolymer is known.

Japanese Patent No. 4363325 Japanese Patent Application Laid-Open No. 2004-231773

In the lactide ring-opening polymerization method described in Patent Document 1, contamination of the reactor due to accumulation of lactide sublimed during polymerization, lactide of the resin due to the remaining unreacted lactide in the obtained polylactic acid-based block copolymer There is a problem that the odor is generated or the hydrolysis resistance is deteriorated. Further, in the method described in Patent Document 2, since the reaction is carried out under a reduced pressure, lactide generation by transesterification reaction of the polylactic acid resin in the molecule is promoted, and the same problems as described above arise.

The present invention has been made to solve such conventional problems, and thereby to obtain a method for producing a specific block copolymer having a low residual lactide.

In order to solve the above problems, the present invention proposes the following manufacturing method. That is, as follows.

(One)

(Hereinafter, referred to as resin (A)) and an ester exchange catalyst (hereinafter, referred to as resin (A)) having at least one hydroxyl group in the molecule (Hereinafter referred to as a block copolymer of a polylactic acid resin and a resin (A) as a block copolymer), which is characterized in that a polylactic acid resin and a resin (A) ).

(2)

The method for producing a block copolymer according to (1), wherein the atmospheric pressure-melting step is carried out in a twin screw extruder (hereinafter, the twin screw extruder is referred to as a twin screw extruder 1).

(3)

The method for producing a block copolymer according to (1) or (2), wherein the resin (A) is a polyalkylene glycol resin.

(4)

The method for producing a block copolymer according to any one of (1) to (3), wherein the transesterification catalyst is a metal organic acid salt and / or a metal halide salt.

(5)

A process for producing a polylactic acid resin, which comprises introducing a block copolymer produced by the method described in (2) directly into another biaxial extruder from within the biaxial extruder 1 and mixing with the polylactic acid resin, &Lt; / RTI >

(6)

(2), the polylactic acid resin was fed into the same side feeder of the same twin-screw extruder as that in which the block copolymer was produced, to obtain the same 2 A method for producing a mixture of a polylactic acid resin and a block copolymer, wherein the block copolymer and the polylactic acid resin are mixed in an axial extruder.

By using the atmospheric pressure-melting process, which is a feature of the present invention, a block copolymer having a small residual lactide can be obtained. The block copolymer obtained by the present invention can be used not only as a flexible resin but also as a plasticizer having an internal bleed-out for polylactic acid resins, by being mixed with a polylactic acid resin alone, Can be used.

The present invention relates to a resin composition comprising a polylactic acid resin, a resin having at least one hydroxyl group in a molecule (hereinafter, a resin having at least one hydroxyl group in a molecule is referred to as a resin (A) (Hereinafter referred to as a block copolymer of a polylactic acid resin and a resin (A)) in the presence of a block copolymer (hereinafter referred to as " polylactic acid resin "Quot;).

Hereinafter, a method for producing a block copolymer of the present invention will be described.

(Polylactic acid resin)

In the present invention, a polylactic acid resin is used as a raw material for producing a block copolymer. The polylactic acid resin is a polymer mainly composed of an L-lactic acid unit and / or a D-lactic acid unit. Here, the main constituent component means that the proportion of the lactic acid unit in the entire monomer unit in the polymer is the largest, preferably 70 to 100 mol% in the lactic acid unit in 100 mol% of the whole monomer unit.

The poly-L-lactic acid in the present invention means that the content ratio of the L-lactic acid unit in 100 mol% of all the lactic acid units in the polymer is more than 50 mol% and not more than 100 mol%. On the other hand, the poly D-lactic acid in the present invention means that the content ratio of the D-lactic acid unit in 100 mol% of all the lactic acid units in the polymer is more than 50 mol% and not more than 100 mol%.

However, the polylactic acid resin in the present invention does not include the block copolymerized resin (A). When copolymerized with the resin (A) and the polylactic acid resin, it is referred to as a block copolymer.

In the poly-L-lactic acid, the crystallinity of the resin itself changes depending on the content ratio of the D-lactic acid unit. That is, when the content of the D-lactic acid unit in the poly L-lactic acid is increased, the crystallinity of the poly L-lactic acid is lowered and becomes closer to amorphous. Conversely, if the content ratio of the D- - The crystallinity of lactic acid increases. Similarly, the crystallinity of the resin itself varies with the content of the L-lactic acid unit in the poly-D-lactic acid. That is, when the content of the L-lactic acid unit in the poly-D-lactic acid is increased, the crystallinity of the poly-D-lactic acid becomes lower and becomes closer to amorphous. Conversely, if the content of the L- - The crystallinity of lactic acid increases.

The content ratio of the L-lactic acid unit in the poly-L-lactic acid used in the present invention or the content ratio of the D-lactic acid unit in the poly-D-lactic acid used in the present invention can be arbitrarily adjusted. When the block copolymer obtained in the present invention is a molded body requiring mechanical strength, it is preferable that 90 to 100 mol% of the L-lactic acid unit and 90 to 100 mol% of the D-lactic acid unit are contained in 100 mol% More preferably 95 to 100 mol% of the lactic acid unit, or 95 to 100 mol% of the D-lactic acid unit. When the block copolymer obtained in the present invention is used as a plasticizer of a crystalline polylactic acid resin, it is preferable to form a polylactic acid segment of a polylactic acid resin and a block copolymer to suppress the bleed-out of the block copolymer , The content ratio of L-lactic acid and D-lactic acid is preferably the same as the above. Conversely, when the polylactic acid resin containing the block copolymer obtained in the present invention or the block copolymer obtained in the present invention as a plasticizer is used as a heat seal layer or the like of the film, it is preferable that the resin is low crystalline or amorphous , And the L-lactic acid unit and the D-lactic acid unit in 100 mol% of the total lactic acid unit are preferably 10 to 90 mol%.

The crystalline polylactic acid resin according to the present invention is a resin obtained by allowing the polylactic acid resin to stand for 1 hour under heating at 100 ° C and then measuring the temperature by a differential scanning calorimeter (DSC) at a heating rate of 20 ° C / , And a polylactic acid resin in which crystal heat of fusion derived from the polylactic acid component is observed.

On the other hand, the amorphous polylactic acid resin as used in the present invention means a polylactic acid resin which does not show a melting point when the same measurement is carried out.

The polylactic acid resin used in the present invention may also randomly copolymerize monomer units other than lactic acid. Examples of other monomers include ethylene glycol, propylene glycol, butanediol, heptanediol, hexanediol, octanediol, nonanediol, decanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, glycerin, pentaerythritol, bisphenol A, Glycol compounds such as glycols, polypropylene glycols and polytetramethylene glycols, and glycol compounds such as oxalic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, malonic acid, glutaric acid, cyclohexanedicarboxylic acid, terephthalic acid, (Meth) acrylates such as phthalic acid, naphthalene dicarboxylic acid, bis (p-carboxyphenyl) methane, anthracene dicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, 5-sodium sulfoisophthalic acid, Isophthalic acid and the like, hydroxycarboxylic acids such as glycolic acid, hydroxypropionic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxycaproic acid and hydroxybenzoic acid, capro Tons, there may be mentioned the lactones, such as valerolactone, propiolactone, undecalactone, 1,5-octanoic sepan-2-one. The copolymerization amount of the monomer units other than the above is preferably 0 to 30 mol%, more preferably 0 to 10 mol%, relative to 100 mol% of the entire monomer units in the polymer of the polylactic acid resin. Among the above-mentioned monomer units, it is preferable to select a component having biodegradability depending on the application.

The mass average molecular weight of the polylactic acid resin used in the present invention is preferably 5,000 to 1,000,000, more preferably 10,000 to 500,000, and even more preferably 100,000 to 300,000, from the viewpoints of the molecular weight of the block copolymer after the reaction and the handling property upon melting. Is most preferable. The mass average molecular weight in the present invention means the molecular weight calculated by polymethylmethacrylate conversion method by measurement by gel permeation chromatography (GPC) with a good solvent such as hexafluoroisopropanol .

The polylactic acid resin used in the present invention can be obtained by a method of directly dehydrating condensation of lactic acid and other raw materials or by a ring-opening polymerization of lactide and other cyclic ester intermediates. For example, when it is prepared by direct dehydration condensation, lactic acids or hydroxycarboxylic acids and hydroxycarboxylic acids are preferably subjected to azeotropic dehydration condensation in the presence of an organic solvent, particularly a phenyl ether solvent, particularly preferably by azeotropic distillation The solvent is removed from the solvent, and the solvent which has been brought to a substantially anhydrous state is returned to the reaction system, whereby a high molecular weight polymer can be obtained.

It is also known that a polymer having a high molecular weight can be obtained by ring-opening polymerization of a cyclic ester intermediate such as lactide under reduced pressure using a catalyst such as tin octanoate. At this time, a method of adjusting the removal conditions of water and a low-molecular compound upon heating and refluxing in an organic solvent, a method of deactivating the catalyst by deactivating the catalyst after completion of the polymerization reaction, a method of heat- A polymer having a small amount of the polymerization initiator can be obtained.

(A resin having at least one hydroxyl group in the molecule (resin (A)))

In the present invention, the resin (A) is used as a raw material for producing a block copolymer. In the present invention, since the transesterification reaction proceeds from the hydroxyl group of the resin (A) to the ester bond between the lactic acid unit and the lactic acid unit in the polylactic acid resin, the resin (A) has at least one hydroxyl group in the molecule It is important that it is resin. However, the resin (A) is a resin having at least one hydroxyl group in the molecule other than the polylactic acid resin. The resin (A) is preferably selected from resins having biodegradability depending on the application.

Examples of the resin (A) include a polyester resin, a polyether resin, a polyacetal resin and the like other than the polylactic acid resin as the resin containing a hydroxyl group at the molecular end. Examples of the resin containing a hydroxyl group in the side chain include polyvinyl alcohol resin, ethylene-vinyl alcohol copolymer resin, polysaccharide, esterified polysaccharide, etherified polysaccharide, deoxyhalogenated polysaccharide, polysaccharide oxide, hydroxyl group modified polyolefin Based resins and the like. For imparting flexibility to the polylactic acid resin, the glass transition temperature of the resin (A) is preferably -70 to 50 占 폚, and more preferably -70 to 40 占 폚.

Among them, polylactic acid resin is highly effective in enhancing flexibility and has high compatibility with polylactic acid resin. As resin (A), polyester resin and / or polyether resin other than polylactic acid resin More preferably a polyether-based resin, and more preferably a polyalkylene glycol resin.

Particularly preferred as the polyalkylene glycol resin as the resin (A) are polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyethylene glycol-polypropylene glycol copolymer, and most preferably polyethylene glycol. Since polyethylene glycol is flexible and has high affinity with polylactic acid resin, the block copolymer of polylactic acid resin and polyethylene glycol is excellent in flexibility and plasticizing efficiency of polylactic acid resin.

The mass average molecular weight of the resin (A) used in the present invention is preferably 1,000 to 1,000,000, more preferably 5,000 to 500,000, and even more preferably 5,000 to 1,000,000, in view of the molecular weight of the block copolymer after the reaction, flexibility, More preferably 100,000 to 100,000, and most preferably 5,000 to 30,000.

(Ester exchange catalyst)

In the present invention, it is important to melt the polylactic acid resin, the resin (A) and the ester exchange catalyst at normal pressure. That is, in the present invention, the block copolymer is produced by an ester exchange method, but it is important to use an ester exchange catalyst at that time.

The ester exchange catalyst in the present invention is not particularly limited, and examples thereof include metals, metal salts, sulfuric acid, and nitrogen-containing basic compounds.

Examples of the metal include manganese, magnesium, titanium, zinc, iron, aluminum, cerium, calcium, barium, cobalt, lithium, sodium, potassium, cesium, lead, strontium, tin, antimony, germanium, yttrium, lanthanum, indium, zirconium .

Examples of the metal salt include an organic acid salt of a metal, a nitrate of a metal, a phosphate of a metal, a borate of a metal, a halide of a metal, and a hydroxide of a metal. Examples of the metal used for the metal salt include the same metals as those described above. Examples of the organic acid include carboxylic acid, sulfuric acid, carbonic acid, phenol and the like.

Examples of sulfuric acid include sulfuric acid, sulfonic acid compounds, sulfinic acid compounds and sulfamic acid compounds.

Examples of the nitrogen-containing basic compound include quaternary amine salts, tertiary amines, secondary amines, primary amines, pyridines, imidazoles, and ammonia.

Among them, the transesterification catalyst of the present invention is preferably a metal salt from the viewpoints of dispersibility in resin, degree of decomposition of resin and decrease in molecular weight, and effect as catalyst, and it is preferable that the transesterification catalyst is a metal salt, It is more preferable to be a cargo salt. In particular, as the organic acid salt of metal and / or the halide salt of metal, from the viewpoints of a small amount of causticity of the polymerization kiln and the extruder, a high ester exchange catalytic activity per mass, and a difficulty of bleeding out from the resin, A salt of an organic acid having an alkyl group having 0 to 10 carbon atoms and a metal (an organic acid salt of a metal), and / or a halide salt of a metal. In the present invention, the alkyl group having no carbon number means that the alkyl group has no alkyl group in the molecule.

Considering the possibility that the block copolymer obtained in the present invention can be used for agriculture and forestry applications and applications requiring biodegradability such as dust bags and compost bags, the transesterification catalyst used in the present invention is a biodegradable, It is preferable that the safety of the apparatus is high. Further, if the ability as an ester exchange catalyst is selected together, the ester exchange catalyst is preferably an organic acid salt of a metal and / or a halide salt of a metal, and particularly preferable as an ester exchange catalyst is an alkyl group having 0 to 10 carbon atoms (Metal organic acid salt), or a halide salt of a metal shown below.

Concrete examples of the organic acid and metal salt having an alkyl group having 0 to 10 carbon atoms, which are particularly preferable as the organic acid salt of the metal, include, for example, a carboxylic acid having 1 to 10 carbon atoms and no magnesium, titanium, tin, zinc , Iron, aluminum, calcium, and potassium. A particularly preferred halide salt embodiment of the metal is, for example, a halide of a metal selected from magnesium, titanium, tin, zinc, iron, aluminum, calcium, potassium.

In the present invention, it is also possible to use two or more different transesterification catalysts in combination.

(Process for producing a block copolymer of a polylactic acid resin and a resin (A)

The method for producing a block copolymer according to the present invention is characterized in that a raw material polylactic acid resin, a resin (A) and an ester exchange catalyst are fed to a reactor and melted at normal pressure (subjected to an atmospheric pressure / melting process).

In the present invention, a block copolymer is produced by performing an ester exchange reaction between a polylactic acid resin and a resin (A). The ester interchange reaction referred to herein means a reaction in which a hydroxyl group, a carboxylic acid group, or another ester bond is allowed to act on an ester bond to cause the exchange of a hydroxyl group or a carboxylic acid group in the ester bond and an ester different from the original ester bond Linkage. In particular, in the present invention, the main purpose is to introduce an ester bond between the polylactic acid resin and the resin (A) by reacting the ester bond of the polylactic acid resin with the hydroxyl group of the resin (A).

The melting temperature in the atmospheric pressure melting process differs depending on the kind of the reactor, the melting point of the polylactic acid resin, the melting point of the resin (A), the viscosity of the polylactic acid resin, and the viscosity of the resin (A) Considering the melting point and the thermal decomposition temperature of the resin, the temperature in the atmospheric pressure-melting process is preferably 150 to 250 占 폚, more preferably 180 to 240 占 폚. The polylactic acid resin and the resin (A) to be used are preferably sufficiently dried in advance in order to prevent the hydrolysis and discoloration at the time of melting to reduce the water content. The water content of the polylactic acid resin and the resin (A) is preferably 1,200 ppm (mass basis) or less, more preferably 500 ppm (mass basis) or less, and even more preferably 200 ppm (mass basis) or less.

The input mass ratio of the polylactic acid resin and the resin (A) is not particularly limited, but the preferred range is 95: 5 to 5:95 by mass ratio. Particularly, when the block copolymer of the product is used as the main component of the molded article as the flexible resin, the mass ratio of the polylactic acid resin and the resin (A) is preferably 95: 5 to 50:50, More preferably 60:40. When the block copolymer is used as the plasticizer of the polylactic acid resin, the mass ratio of the polylactic acid resin to the resin (A) is preferably 80:20 to 5:95, more preferably 75:25 to 10:90 , More preferably 70:30 to 30:70.

The amount of the ester exchange catalyst added is preferably 0.001 to 5 parts by mass per 100 parts by mass of the total amount of the polylactic acid resin and the resin (A), although it varies depending on the kind of the reactor, the reaction temperature, the reaction time, , More preferably 0.005 to 1 part by mass. If the addition amount of the ester exchange catalyst is in the range of 0.001 to 5 parts by mass based on the total 100 parts by mass of the polylactic acid resin and the resin (A), the coloring of the obtained block copolymer, the decrease in molecular weight and the generation of lactide are kept to a minimum .

In the present invention, it is important to carry out an atmospheric pressure-melting process at normal pressure in order to suppress the generation of lactide in the transesterification reaction. The atmospheric pressure in the present invention means that the atmospheric pressure in the atmospheric pressure and melting process is in the range of 5 x 10 ⁴ to 1.5 x 10 ⁵ Pa, preferably 7 x 10 ⁴ to 1.3 x 10 ⁵ Pa, More preferably from 10 ⁴ to 1.1 10 ⁵ Pa. In order to suppress the hydrolysis and oxidative decomposition of the resin in this atmospheric pressure and melting step, it is preferable to set the reactor to an inert gas atmosphere.

The reactor used for the atmospheric pressure and melting process is not particularly limited, and for example, a test tube having a stirring device, a vertical or horizontal tank reactor or a kneader may be mentioned as a batch reactor. Examples of the continuous reactor include a single screw extruder, a twin screw extruder, and other multi-screw extruders. In a multi-screw extruder having two or more axes, the screw rotation direction thereof may be the same direction or may be different directions.

Among them, in view of shortening of the reaction time and operability, the reactor for the atmospheric pressure and melting process is preferably a continuous reactor, more preferably a twin screw extruder. That is, the atmospheric pressure-melting process is preferably carried out in a continuous-type reactor, particularly in a biaxial extruder. In the twin-screw extruder, not only the polylactic acid resin and the resin (A) are rapidly melted but also the distribution mixing and dispersion mixing of the resins progress efficiently, so that the ester linkage of the polylactic acid resin and the The probability of collision of hydroxyl groups is increased, and as a result, their transesterification reaction proceeds in a short time.

As described above, it is preferable that the atmospheric pressure-melting process be performed in a twin-screw extruder. However, as a screw configuration of such a twin screw extruder, a reverse kneading disk is used in order to secure the resin retention time and kneading force necessary for the reaction The screw diameter is preferably 10 to 400 mm, and the L / D ratio is preferably 20 to 200. Further,

If the reactor is a twin screw extruder, the air pressure is measured as a vent hole.

The time required for the atmospheric pressure and melting process is preferably 30 minutes to 5 hours when a batch-type reactor having a low kneading property is used. On the other hand, in the case of a continuous reactor represented by a twin-screw extruder, the time of the atmospheric pressure-melting process corresponds to the residence time of the resin in the reactor, and it is preferably 5 to 30 minutes, more preferably 5 to 15 minutes Do.

The block copolymer obtained by the production method of the present invention can further improve its storage stability by deactivating the remaining ester exchange catalyst. Examples of the deflocculating agent used for such a purpose include amino acids, phenols, hydroxycarboxylic acids, diketones, amines, oximes, phenanthrolines, pyridine compounds, dithio compounds, diazo compounds, thiols, porphyrins And phosphorus compounds such as nitrogen-containing phenols, carboxylic acids, phosphoric acid, phosphoric acid esters, metal phosphate salts, phosphorous acid, phosphorous acid esters, and phosphorous acid metal salts as coordinating atoms. These deflocculating agents may be used alone or in combination. From the viewpoint of the hydrolysis resistance of the polylactic acid resin, compounds in these deflocculating agents are more preferable, and crystals of phosphoric acid or phosphorous acid having a purity of 98% by mass or more are more preferable.

As a method of adding a deflocculant, in the case of a batch-type reactor, there is a method of stopping the reactor once after completion of the transesterification reaction, adding the deflocculating agent, and then running the reactor again. In the case of a continuous reactor typified by a biaxial extruder, there is a method of adding a deflocculant from a side feeder of an extruder.

The addition amount of the deflocculating agent is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass with respect to 1 part by mass of the transesterification catalyst added in the production process.

When it is intended to make the present block copolymer as the main component of the block copolymer with respect to the mass average molecular weight of the block copolymer obtained in the present invention, the mass average molecular weight thereof is preferably 10,000 to 1,000,000, more preferably 50,000 To 500,000. When the present block copolymer is used as an additive such as a plasticizer, the mass average molecular weight thereof is preferably 1,000 to 500,000, more preferably 5,000 to 100,000, and even more preferably 5,000 to 1,000,000 in order to exhibit softening and bleeding- To 50,000.

(A mixture of a block copolymer and a polylactic acid resin)

The block copolymer obtained in the present invention can be used in combination with a polylactic acid resin. The block copolymer in this case can also function as a plasticizer of a polylactic acid resin. When the block copolymer obtained in the present invention is used as a plasticizer of a polylactic acid resin, in order to disperse the block copolymer in the polylactic acid resin, the polylactic acid resin and the block copolymer may be melt-kneaded, , The polylactic acid resin and the block copolymer may be dissolved in the solvent and the resin may be volatilized or the resin may be precipitated in a poor solvent.

When the block copolymer is used as a plasticizer of a polylactic acid resin, the content ratio of the polylactic acid resin and the block copolymer is preferably from 3% by mass to 100% by mass in total of the block copolymer and the polylactic acid resin, By mass, more preferably from 5 to 60% by mass, still more preferably from 5 to 50% by mass. When the content of the block copolymer is within the above range, flexibility and impact resistance of the polylactic acid resin are improved, and bleed-out of the block copolymer can be suppressed.

When the block copolymer is used as a plasticizer for a polylactic acid resin, in addition to the polylactic acid resin and the block copolymer, other thermoplastic resins, general particles and additives may be mixed into the resin composition.

The atmospheric pressure melting process for producing the block copolymer is preferably carried out in a twin screw extruder (hereinafter, the twin screw extruder is referred to as a twin screw extruder 1) as described above. When a mixture of a polylactic acid resin and a block copolymer is prepared, for example, by using a block copolymer as a plasticizer of a polylactic acid resin, the block copolymer produced in the biaxial extruder 1 is fed to a twin screw extruder 1 (Hereinafter, the other twin-screw extruder is hereinafter referred to as a twin-screw extruder 2), and is mixed with the polylactic acid resin in the twin-screw extruder 2. The polylactic acid resin And a method of preparing a mixture of a block copolymer is preferable. That is, when a mixture of a polylactic acid resin and a block copolymer is produced, the block copolymer produced in the twin-screw extruder 1 is directly fed into the twin-screw extruder 2 in the molten state by a method such as side feed And is mixed with the polylactic acid resin in the biaxial extruder 2. Herein, when the block copolymer is introduced into the twin-screw extruder 2 from within the twin-screw extruder 1, it means that the block polymer is introduced into the twin-screw extruder 2 from within the twin-screw extruder 1 while maintaining the above-mentioned block polymer at a temperature not lower than the glass transition temperature . For example, when the block copolymer is taken out from the twin screw extruder 1 and the block copolymer is introduced into the biaxial extruder 2 at a temperature not higher than the glass transition temperature, it is not interpreted as being directly referred to herein. When the block copolymer has a plurality of glass transition temperatures, it is directly referred to as being introduced into the twin screw extruder 2 from within the twin screw extruder 1 while keeping the block copolymer at the highest glass transition temperature or higher.

When a mixture of a block copolymer and a polylactic acid resin is produced, the mass average molecular weight of the block copolymer is small and the glass transition temperature is low. In such a case, such a block copolymer may be difficult to be formed into chips. In such a case, it is necessary to cool the obtained block copolymer once to solidify it, followed by pulverization treatment. On the other hand, when the block copolymer obtained by using the twin-screw extruder 1 is directly introduced into the twin-screw extruder 2 and is mixed with the polylactic acid resin in the twin-screw extruder 2, the above- Is omitted, which is preferable.

The screw configuration, screw diameter, L / D and residence time of the twin screw extruder 1 and the twin screw extruder 2 are preferably the same as those of the screw configuration, screw diameter, L / D and residence time of the twin screw extruder described above. The twin screw extruder 1 and the twin screw extruder 2 may be of the same type.

In addition, the biaxial extruder 1 in which the block copolymer is to be produced needs to be atmospheric pressure for the above-mentioned reason. The range of the atmospheric pressure is the same as that described above. On the other hand, in the present method, since the biaxial extruder 2 does not contribute to the formation of the block copolymer, the atmospheric pressure in the biaxial extruder 2 does not necessarily have to be normal pressure, but can also be reduced.

As a method for producing a mixture of a polylactic acid resin and a block copolymer, a method of producing a mixture of a block copolymer produced by a twin screw extruder and a polylactic acid based block copolymer from a side feeder of the same twin- There is also a method for producing a mixture of a polylactic acid resin and a block copolymer, wherein the block copolymer and the polylactic acid resin are mixed in the same twin-screw extruder as the one in which the block copolymer is produced. do. In the present method, the time and effort required for cooling and pulverizing the block copolymer can be omitted in the same manner as described above, and only one twin-screw extruder is required, which is preferable in that the apparatus configuration can be simplified.

As a preferable screw configuration of the twin screw extruder used in the present method, a kneading disk is inserted forward from the side feeder into which the polylactic acid resin is fed. The screw diameter, L / D and residence time are preferably the same as the screw diameter, L / D and residence time of the twin screw extruder described above. The extrusion temperature is preferably 200 to 280 DEG C at a temperature near the kneading disk, and preferably 0.05 to 5 parts by mass. This is because the production of the block copolymer in the present method is mainly performed only from the point of the main feeder of the biaxial extruder to the point of the side feeder containing the polylactic acid resin, that is, a part of the biaxial extruder, It is necessary to carry out the process efficiently. When the polylactic acid resin is fed from the side feeder, it is preferable to add the deflocculant at the same time.

In the present method, the block copolymer is mainly produced from the point of the main feeder of the twin-screw extruder to the point of the side feeder of the polylactic acid resin, so that the reaction is carried out at the normal pressure It is necessary to do. The range of the atmospheric pressure is the same as described above. On the other hand, after the point of the side feeder, it hardly contributes to generation of the block copolymer. Therefore, the atmospheric pressure does not necessarily have to be atmospheric pressure in the section, but can also be reduced.

The polylactic acid resin used in the mixture of the polylactic acid resin and the block copolymer may be the same resin as the polylactic acid resin described above as a raw material for the block copolymer.

The composition containing the block copolymer obtained in the present invention may contain known antioxidants, nucleating agents, ultraviolet stabilizers, anticolor agents, anticorrosive agents, deodorants, flame retardants, antiwear agents, antistatic agents, ion exchangers, Antifoaming agents, coloring pigments, dyes, lubricants, foaming agents, and other resins may be used as needed. The amount of these additives to be added is not particularly limited so long as the effect achieved by the present invention is not impaired, but it is preferable that the amount of the additive is 0.01 to 30% by mass based on 100% by mass of the composition containing the block copolymer, More preferably 0.01 to 20% by mass, and still more preferably 0.01 to 10% by mass.

The block copolymer obtained in the present invention preferably has a residual lactide content of 1.00 mass% or less, more preferably 0.70 mass% or less, still more preferably 0.50 mass% or less, from the viewpoints of odor and hydrolysis resistance.

The block copolymer obtained in the present invention is preferably one in which only one peak originating from the polymer is present in the GPC elution curve (single-sticking) because it is preferable that the polylactic acid resin and the resin (A) . When the polylactic acid resin and the resin (A) remain, the GPC elution curve has two peaks derived from the polymer (bimetallic) or more.

It is preferable that the block copolymer obtained in the present invention does not contain the resin (A) as a raw material. Therefore, for TmA0 and TmA defined below, TmA0-TmA is preferably 7.0 DEG C or more, and more preferably 9.0 DEG C or more.

TmA0: Melting peak temperature derived from Resin (A), which is read from the chart of the DSC heating process of the resin (A).

Tma: the melting peak temperature derived from the resin (A) segment, which is read from the chart of the DSC temperature rise procedure of the block copolymer.

When a mixture of the block copolymer and the polylactic acid resin obtained in the present invention is formed into a sheet, the resulting sheet preferably has a tensile modulus of 100 to 1,000 MPa in order to exhibit sufficient flexibility. The tensile modulus of elasticity is more preferably 100 to 950 MPa, and further preferably 100 to 900 MPa.

Further, in the sheet containing the block copolymer and the polylactic acid resin, the block copolymer does not escape from the polylactic acid resin, that is, its inner bleeding-out property is required. As an index of the bleed-out resistance, it is preferable that the hot water extraction rate of the sheet is in the following range. That is, it is preferable that the mass reduction rate when the sheet is treated in distilled water at a pressure of 1 atm for 1 hour is 5.0% or less, more preferably 3.0% or less.

Example

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto at all.

[Measurement and evaluation method]

Measurement and evaluation described in the examples were carried out under the conditions as described below.

(1) Modulus of elasticity (MPa)

Strain measurement was carried out using TENSILON UCT-100 manufactured by Orientech, and the stress difference between two points on the straight line was divided by the strain difference between the same two points by using the first straight portion of the stress-strain curve, The tensile modulus was calculated. Specifically, a rectangular sample having a length of 150 mm and a width of 10 mm was cut out from the breath sheet, and measurement was carried out according to the method defined in JIS K 7127 (1999) at an initial tensile chuck distance of 50 mm and a tensile rate of 200 mm / min . Further, the measurement was performed five times, and the average value thereof was calculated.

(2) Amount of lactide

The resulting sample was dissolved in methylene chloride, and the concentration was adjusted to 1 g / 20 ml. Then, 60 ml of acetone was added, and 320 ml of cyclohexane was added dropwise while stirring with ultrasonic waves to precipitate a polymer component. The precipitate was removed by centrifugation and a PTFE filter having a pore diameter of 0.45 mu m to prepare a sample solution. Column: DB-17MS (manufactured by J & W), column temperature: 80 to 250 占 폚, 10 占 폚 / min, carrier gas: He (trade name, manufactured by Shimadzu Corporation) using gas chromatograph GC- . In addition, a calibration curve was prepared using a sample solution of a single lactide mixture with a concentration changed in advance, and the amount of lactide (% by mass) of the sample was determined using this calibration curve.

(3) Hot water extraction rate

And the hot water extraction rate was measured as an index of the bleed-out resistance. The mass of the pressed sheet before the treatment was measured for a press sheet which was previously conditioned at a temperature of 23 캜 and a humidity of 65% RH for one day or more. Subsequently, the sheet was immersed in boiling distilled water under 1 atm for 1 hour, and after the humidity was maintained under the same conditions as before the treatment, the mass after the treatment was measured. Then, the hot water extraction rate was calculated by the following formula.

(Mass%) = (mass before treatment - mass after treatment) x 100 / mass before treatment

(4) GPC

The mass average molecular weight was measured by gel permeation chromatography (GPC) and calculated by polymethyl methacrylate conversion method. The calculation of the mass average molecular weight is carried out only when there is only one polymer-derived peak in the elution curve of the obtained sample (single-sticking), and the peaks derived from the polylactic acid resin and the resin (A) But not in the case of having (peak) polymeric peaks. The measurement of GPC was carried out using a Model 2695 manufactured by Waters, a Waters type differential refractometer Model 2414 was used as a detector, a Wattus MODEL 510 was used as a pump, and a Shodex HFIP-806M Were connected in series. The measurement was carried out at a flow rate of 0.5 mL / min and a column temperature of 40 캜, and 0.2 mL of a solution having a sample concentration of 0.1% by mass was injected into the solvent using hexafluoroisopropanol containing 5 mM sodium trifluoroacetate.

(5) DSC

Using a differential scanning calorimeter RDC220 manufactured by Seiko Instruments Inc., 5 mg of the resulting sample was placed in an aluminum base plate, and the temperature was raised from 25 占 폚 to 220 占 폚 at a heating rate of 20 占 폚 / min for 5 minutes at 220 占 폚 After the melt was maintained, it was quenched to 25 占 폚. Then, the melting peak temperature TmA (占 폚) derived from the resin (A) segment was read from the chart of the temperature rise process thereof. The melting peak temperature TmA0 (占 폚) of the resin (A) was determined in the same manner as above using the unreacted resin (A) as a sample, and TmA0-TmA was calculated.

[Polylactic Acid Resin]

(4032D)

Poly-L-lactic acid, NatureWorks "4032D", mass average molecular weight of 200,000, D-form content of 1.4 mol%, melting point of 166 ° C. And dried at 100 DEG C for 5 hours under reduced pressure in a vacuum oven in advance.

(4060D)

L-lactic acid, "4060D", a weight average molecular weight of 200,000, a D-isomer content of 12.0 mol%, no melting point. And dried at 50 DEG C for 7 hours under reduced pressure in a vacuum oven in advance.

The weight average molecular weight was measured by using Waters 2695 manufactured by Nippon Wotas Co., Ltd., using polymethyl methacrylate as a standard and a hexafluoroisopropanol solvent at a column temperature of 40 ° C.

[Resin (A)]

(PEG6000S)

Polyethylene glycol, "PEG6000S" manufactured by Sanyo Chemical Industries, Ltd., mass average molecular weight of 8,000, and TmA0 of 64.0 ° C. And dried at 30 DEG C for 7 hours under reduced pressure in a vacuum oven in advance.

(Ecoflex)

Polybutylene adipate terephthalate, "Ecoflex F Blend C1200" manufactured by BASF, mass average molecular weight of 60,000, and TmA0 of 120.2 ° C. And dried in a vacuum oven under reduced pressure at 80 DEG C for 7 hours.

[Ester exchange catalyst]

(Mg acetate)

As the metal salt (organic acid salt of metal), magnesium acetate dihydrate (manufactured by Wako Pure Chemical Industries, Ltd.) was used.

(Mg chloride)

Magnesium chloride hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) was used as a metal salt (halide salt of metal).

(Sn octanoate)

As a metal salt (organic acid salt of metal), tin 2-ethylhexanoate (II) (manufactured by Wako Pure Chemical Industries, Ltd.) was used.

(p-TSA)

As sulfuric acid, p-toluenesulfonic acid (manufactured by Wako Pure Chemical Industries, Ltd.) was used.

(Example 1)

40 parts by weight of the 4032D, was added to 60 parts by weight of the PEG6000S, chlorinated Mg in a test tube equipped with a stirrer were weighed 0.5 part by mass, while stirring in a nitrogen atmosphere at atmospheric pressure 1.0 × 10 ⁵ Pa melting at 200 ℃ 4 hours, cooled Solidified to obtain Sample A. The amount of lactide, mass average molecular weight and DSC of the obtained sample A were measured.

Further, the sample 30 parts by weight of A, 20 parts by weight of the 4032D, was added to 4060D in a test tube equipped with a stirrer were weighed 50 parts by weight, water pressure 1.0 × 10 ⁵ Pa in the 1 hours melted at 240 ℃ with stirring in a nitrogen atmosphere , Cooled and solidified to obtain Sample B. The obtained sample B was pulverized and dried in a vacuum oven under reduced pressure at 50 DEG C for 7 hours and pressurized at 220 DEG C to obtain an isotropic pressed sheet having a thickness of 200 mu m. The elastic modulus and hot water extraction rate of the obtained press sheet were measured.

In Example 2 and Comparative Example 1, a sample was obtained in the same manner as in Example 1, except that the composition and the melting temperature of the raw material put into the test tube were changed as shown in Tables 1 and 2.

In Comparative Examples 2 to 3, the composition and the melting temperature of the raw material to be introduced into the test tube were changed as shown in Table 2, and the pressure in the test tube was set to 1.0 × 10 ³ Pa using a vacuum pump when the sample A was obtained , A sample was obtained in the same manner as in Example 1.

(Example 3)

(L / D = 35, screw diameter = 30 mm) were kneaded and kneaded by weighing 40 parts by mass of PEG6000S, 40 parts by mass of PEG6000S, 60 parts by mass of PEG6000S and 0.5 parts by mass of Mg chloride, , And a feed amount of 10 kg / h. The sample A was cooled and solidified by discharging it from the spinneret. The temperature of TEX30 alpha was set at 80 占 폚 from the bottom of the hopper to the front of the first kneading portion (measured from the tip of the screw to the point of L / D = 25), and 200 占 폚 after the first kneading portion. Further, the vent hole existing at the point of L / D = 20 was measured from the tip of the screw, and the vent hole was opened. The pressure at the point was 1.0 10 ⁵ Pa. The amount of lactide, mass average molecular weight and DSC of the obtained sample A were measured.

In Examples 4 to 10 and Comparative Examples 4 to 7, a sample was obtained in the same manner as in Example 3, except that the composition and the extrusion temperature of the raw material charged into TEX30? Were changed as shown in Tables 1 and 2.

In Comparative Example 8, the composition and the extrusion temperature of the raw material to be fed into TEX30α were changed as shown in Table 2, and the vent holes existing at the L / D = 20 were measured from the tip of the screw of TEX30α to the vacuum pump , And a sample was obtained in the same manner as in Example 3 except that the air pressure at the point was 3.0 × 10 ³ Pa.

The physical properties of the obtained sample are shown in Table 1 and Table 2.

(Example 11)

(L / D = 35, screw diameter = 30 mm) was used as the twin screw extruder 1 and TEX44 alpha (L / D = 38, screw diameter = 44 mm) manufactured by Nippon Shekou Co., The apparatus was configured so that the resin discharged from the axial extruder 1 was fed sideways in the middle of the twin screw extruder 2 (measured from the end of the screw and at the point of L / D = 18).

4032D, 60 parts by mass of PEG6000S and 0.5 parts by mass of Mg chloride were weighed and blended, and the mixture was charged into a twin-screw extruder 1 and melted and kneaded at a screw rotation speed of 200 rpm and a feed rate of 10 kg / h. The temperature of the twin screw extruder 1 was set at 80 ° C from the bottom of the hopper to the front of the first kneading portion (measured from the tip of the screw to the point of L / D = 25), and 200 ° C after the first kneading portion. Further, the vent hole existing at the point of L / D = 20 was measured from the tip of the screw of the twin screw extruder 1, and the vent hole was opened. The pressure at the point was 1.0 10 ⁵ Pa.

In addition, 67 parts by mass of 4032D and 167 parts by mass of 4060D were weighed and blended, and the mixture was melted and kneaded at a screw rotation speed of 200 rpm and a feed rate of 23.3 kg / h. The temperature of the twin screw extruder 2 was set at 150 ° C from the bottom of the hopper to the front of the first kneading portion (measured from the tip of the screw to the point of L / D = 28), and 220 ° C after the first kneading portion. Further, the vent hole existing at the point of L / D = 20 was measured from the tip of the screw of the twin screw extruder 2, and the vent hole was opened. The pressure at the point was 1.0 10 ⁵ Pa. The resin discharged from the nip of the twin screw extruder 2 was cooled and solidified to obtain a sample C. The obtained sample C was crushed and dried in a vacuum oven under reduced pressure at 50 DEG C for 7 hours and pressurized at 220 DEG C to obtain an isotropic pressed sheet having a thickness of 200 mu m. The elastic modulus and hot water extraction rate of the obtained press sheet were measured.

In Example 12 and Comparative Example 9, samples were obtained in the same manner as in Example 11, except that the composition of the raw materials charged in the twin screw extruders 1 and 2 was changed as shown in Table 3.

Table 3 shows the physical properties of the obtained sample.

(Example 13)

A side feeder was provided in the middle of the twin screw extruder (measured from the tip of the screw and at the point of L / D = 18) using a Nippon Shekou Co., Ltd. TEX30 alpha (L / D = 35, screw diameter = 30 mm) .

4032D, 60 parts by mass of PEG6000S, and 0.5 parts by mass of Mg chloride were weighed and blended and charged into a main hopper of a twin-screw extruder and melted and kneaded at a screw rotation speed of 200 rpm and a feed rate of 10 kg / h. The temperature of the twin screw extruder 1 was set at 80 占 폚 from the bottom of the hopper to the first kneading portion (measured from the tip of the screw to the point of L / D = 25), and 240 占 폚 from the first kneading portion to the side feeder . Further, the vent hole existing at the point of L / D = 20 was measured from the tip of the screw of the twin screw extruder 1, and the vent hole was opened. The pressure at the point was 1.0 10 ⁵ Pa.

In addition, 67 parts by mass of 4032D and 167 parts by mass of 4060D were weighed, blended, put into a side feeder, melted and kneaded. The temperature after the side feeder was set at 200 캜. The resin discharged from the spinneret of the twin screw extruder was cooled and solidified to obtain a sample D. The obtained sample D was pulverized and dried in a vacuum oven under reduced pressure at 50 DEG C for 7 hours and pressurized at 220 DEG C to obtain an isotropic pressed sheet having a thickness of 200 mu m. The elastic modulus and hot water extraction rate of the obtained press sheet were measured.

In Examples 14 to 15 and Comparative Examples 10 to 11, a sample was obtained in the same manner as in Example 13 except that the composition of the raw material charged in the twin-screw extruder was changed as shown in Table 4.

Table 4 shows the physical properties of the obtained sample.

(Example 16)

(L / D = 28, screw diameter = 40 mm) made by Plastics Engineering Research Laboratories were weighed and weighed and mixed with 40 parts by mass of PEG6000S, 60 parts by mass of PEG6000S and 0.5 parts by mass of Mg chloride, And a feed amount of 10 kg / h, and the mixture was discharged from the spinneret and cooled and solidified to obtain a sample A. The temperature of the GT-40 was set at 80 ° C below the hopper and 200 ° C afterwards. Further, the vent hole on the way was opened. The pressure at the point was 1.0 10 ⁵ Pa. The amount of lactide, mass average molecular weight and DSC of the obtained sample A were measured.

In Comparative Example 12, a sample was obtained in the same manner as in Example 16, except that the composition of the raw material to be fed into GT-40 was changed as shown in Table 5. [

In Comparative Example 13, a sample was obtained in the same manner as in Example 16, except that the vent hole of the GT-40 was connected to a vacuum pump, and the air pressure at the point was 3.0 × 10 ³ Pa.

The physical properties of the obtained sample are shown in Table 5.

&Lt; Industrial applicability >

Claims

2. The method for producing a block copolymer according to claim 1, wherein the pressureless-melting step is carried out in a twin screw extruder (hereinafter, the twin screw extruder is referred to as a twin screw extruder).

The method for producing a block copolymer according to claim 1 or 2, wherein the resin (A) is a polyalkylene glycol resin.

The method for producing a block copolymer according to any one of claims 1 to 3, wherein the ester exchange catalyst is an organic acid salt of a metal and / or a halide salt of a metal.

A block copolymer produced by the method according to claim 2 is introduced directly into the other twin screw extruder from within the twin screw extruder 1 and mixed with the polylactic acid resin. &Lt; / RTI >

A block copolymer produced by the method according to claim 2 was loaded with the same polylactic acid resin as the block copolymer from the side feeder of the same twin screw extruder as that of the block copolymer to obtain the same 2 A method for producing a mixture of a polylactic acid resin and a block copolymer, wherein the block copolymer and the polylactic acid resin are mixed in an axial extruder.