JP2008115288A - Polylactic acid copolymer resin and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a polylactic acid copolymer resin having improved heat-resistance and applicable in a wide application range by a simple production method. <P>SOLUTION: The method for producing a polylactic acid copolymer resin containing (A) a bisphenol compound component and (B) a polylactic acid component comprises the copolymerization of (A) 1-50 mass% bisphenol compound having a number-average molecular weight of ≤10,000 and (B') 99-50 mass% raw material compound for the polylactic acid. More particularly, the raw material compound B' for the polylactic acid is a lactide. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a polylactic acid copolymer resin containing a bisphenol compound.

As the Kyoto Protocol related to global warming came into effect and carbon dioxide emission trading became a hot topic, attention to global warming increased and strict attention was paid to carbon dioxide emissions. Under such circumstances, in the field of biodegradable plastics, the concept of “carbon neutral” has come to be used and has become widespread.
The concept of “carbon neutral” is as follows. In biodegradable plastics synthesized by organisms or synthesized from substances produced by organisms, carbon dioxide and water generated by biodegradation are originally carbon dioxide in the atmosphere and water that was in the soil. Therefore, if the whole life cycle is taken, the amount of carbon dioxide present on the surface will not be increased, and therefore global warming will not be promoted.

  Among biodegradable plastics, polylactic acid resin is made from renewable plant resources (such as corn and sweet potato), and is expected to be most popular in terms of mechanical properties and price. In terms of environment, it does not cause waste problems due to biodegradation, contributes greatly to the prevention of global warming due to its carbon neutral properties, and is not derived from petroleum resources, so it is a substitute for synthetic resins using petroleum-derived components. As a result, it can also contribute to saving oil resources.

  On the other hand, looking at the characteristics of the polylactic acid resin, polyethylene terephthalate (PET), which is widely used as the same polyester-based synthetic resin as the polylactic acid resin, has a glass transition temperature (Tg) of about 78 ° C. The Tg of the polylactic acid resin is generally less than 60 ° C. depending on the molecular weight and copolymer composition, and is inferior in heat resistance. For this reason, a product using polylactic acid resin has a problem of being fused or deformed when the indoor temperature rises during transportation by truck or ship.

  As a method for improving the heat resistance of the polylactic acid resin, a method for improving the crystallization speed, a method using a stereo complex, a method for improving Tg, and the like can be considered. In order to improve the crystallization speed, it is common to add a nucleating agent such as talc that promotes crystallization. However, there are problems such as resin becoming opaque and physical properties being lowered. When using a stereo complex, poly-D-lactic acid is required, but there are problems such that the production amount of D-lactic acid is small, expensive and difficult to obtain, and heat resistance cannot be improved depending on molding conditions. .

  As techniques for improving Tg, Patent Document 1 discloses a method of copolymerizing an aromatic hydroxycarboxylic acid aryl ester and lactide, Patent Documents 2 and 3 describe a method of copolymerizing a ring structure-containing compound and lactide, Patent Document 4 Is a method in which polylactic acid is depolymerized with an aromatic dicarboxylic acid and then polycondensed with bisphenol, etc., Patent Document 5 is a method of copolymerizing aromatic polycarbonate and lactide, and Patent Document 6 is a method of copolymerizing aromatic polycarbonate and polylactic acid. A method of polymerizing is disclosed.

However, in the method of Patent Document 1, the Tg is not sufficiently improved, and in Patent Document 2, the ring structure-containing epoxy compound is not sufficiently improved in Tg, and other ring structure-containing monomer compounds are expensive. Furthermore, in the methods of Patent Documents 3 and 6, the reaction is performed in an organic solvent, the operation is complicated, and it is not suitable for mass production. In the method of Patent Literature 4, lactide by-product and coloring are remarkable during the polycondensation reaction after depolymerizing the polylactic acid resin, and it is not practical. In the method of Patent Document 5, since the aromatic polycarbonate resin used has a weight average molecular weight of 10,000 or more, the resulting copolymer was opaque.
JP 2002-338666 A JP 2003-238667 A JP 2006-037055 A JP 2006-143810 A JP 7-82369 A JP-A-9-216942

  The present invention solves the above-described problems, and an object of the present invention is to provide a method for producing a polylactic acid copolymer resin with improved heat resistance, which can be applied in a wide range by a simple method.

The present inventors have focused on a compound having a bisphenol unit and found that a polylactic acid copolymer resin having an improved Tg can be produced by copolymerizing the compound with a raw material compound of polylactic acid. did.
That is, the gist of the present invention is as follows.
(1) A method for producing a polylactic acid copolymer resin comprising a bisphenol compound (A) component and a polylactic acid (B) component, wherein the number average molecular weight is 10,000 or less bisphenol compounds (A) 1 to 1 A method for producing a polylactic acid-based copolymer resin, comprising copolymerizing 50% by mass and 99-50% by mass of a raw material compound (B ′) of polylactic acid.
(2) The group in which the bisphenol compound (A) is composed of bisphenol A, bisphenol S ethylene glycol adduct, bisphenol A ethylene glycol adduct, and an aromatic polycarbonate oligomer or aromatic polyester oligomer having a bisphenol unit and two hydroxyl groups. (1) The method for producing a polylactic acid copolymer resin according to (1), wherein the compound is a compound selected from the group consisting of:
(3) The method for producing a polylactic acid-based copolymer resin according to (1) or (2), wherein the raw material compound (B ′) of polylactic acid is lactide.
(4) After the copolymerization reaction between the bisphenol compound (A) and the polylactic acid raw material compound (B ′), a chain extender having two or more functional groups capable of reacting with a hydroxyl group is reacted. The method for producing a polylactic acid copolymer resin according to any one of (1) to (3).
(5) A polylactic acid copolymer resin obtained by the production method according to any one of (1) to (4) above.

According to the production method of the present invention, a polylactic acid copolymer resin can be easily obtained.
The polylactic acid copolymer resin obtained by the production method of the present invention has a Tg higher than that of conventional polylactic acid, and can be applied to a wide range of fields requiring heat resistance. Moreover, it is excellent in transparency and can be applied to uses that require transparency. Furthermore, because it uses polylactic acid, it is carbon neutral, so it greatly contributes to the prevention of global warming and also contributes to the saving of petroleum resources.

Hereinafter, the present invention will be described in detail.
The polylactic acid copolymer resin produced by the method of the present invention contains a bisphenol compound (A) component and a polylactic acid (B) component.
The polylactic acid (B) component can be introduced into the polylactic acid copolymer resin by polymerizing the raw material compound (B ′) of polylactic acid. Examples of the raw material compound (B ′) for polylactic acid include D-lactic acid, L-lactic acid, lactic acid oligomer, L- or D-lactide, and lactide is preferable from the viewpoint of easy polymerization reaction.
In addition, when using a lactic acid oligomer as a raw material compound, it is preferable that the both terminal groups are a hydroxyl group and / or a carboxyl group from the point of high molecular weight. A lactic acid oligomer in which both terminal groups are hydroxyl groups can be obtained by polymerizing lactide using a diol molecule as an initiator or depolymerizing polylactic acid with a diol. Moreover, the lactic acid oligomer whose both terminal groups are carboxyl groups can be obtained by depolymerizing polylactic acid with dicarboxylic acid. Furthermore, a lactic acid oligomer having a hydroxyl group and a carboxyl group at its end can be obtained by polycondensation of lactic acid or hydrolysis of polylactic acid.
There is no restriction | limiting in particular regarding D / L ratio in a polylactic acid component (B) component.

In the present invention, the bisphenol compound (A) component constituting the polylactic acid copolymer resin contains a bisphenol unit,
(1) Monomer containing one bisphenol unit (A-1)
(2) Alkylene glycol adduct of the above monomer (A-2)
(3) Oligomer (A-3) containing a plurality of bisphenol units and having two hydroxyl groups
Is mentioned.

As the monomer (A-1) containing one bisphenol unit, 1,1-bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 1,1-bis (4- Methyl-2-hydroxyphenyl) methane, 1,1-bis (3,5-dimethyl-4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 2,2-bis (4-hydroxy) Phenyl) -4-methylpentane, 2,2-bis (4-hydroxyphenyl) propane (bisphenol A), 2,2-bis (3-methyl-4-hydroxyphenyl) propane, 2,2-bis (3 5-dimethyl-4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1,1-bis (4-hydro) Ciphenyl) -2-ethylhexane, 2,2-bis (3-phenyl-4-hydroxyphenyl) propane, 1,1-bis (3-methyl-4-hydroxyphenyl) methane, 4,4′-biphenol, 2 , 2-bis (4-hydroxyphenyl) butane, 1,1-bis (4-hydroxyphenyl) -2-methylpropane, 1,1-bis (4-hydroxyphenyl) -1-phenylmethane, 2,2- Bis (4-hydroxyphenyl) octane, 1,1-bis (3-methyl-4-hydroxyphenyl) cyclohexane, 2,2-bis (3-allyl-4-hydroxyphenyl) propane, 2,2-bis (3 -Isopropyl-4-hydroxyphenyl) propane, 2,2-bis (3-tert-butyl-4-hydroxyphenyl) propane, 2,2-bis 3-sec-butyl-4-hydroxyphenyl) propane, bisphenolfluorene, 1,1-bis (2-methyl-4-hydroxy-5-tert-butylphenyl) -2-methylpropane, 4,4 ′-[1 , 4-phenylene-bis (2-propylidene) -bis (3-methyl-4-hydroxyphenyl)], 1,1-bis (3-phenyl-4-hydroxyphenyl) cyclohexane, 4,4′-dihydroxyphenyl ether Bis (2-hydroxyphenyl) methane, 2,4′-methylenebisphenol, bis (3-methyl-4-hydroxyphenyl) methane, bis (4-hydroxyphenyl) propane, 1,1-bis (2-hydroxy-) 5-methylphenyl) ethane, 1,1-bis (4-hydroxyphenyl) -3-methylbutane, bis 2-hydroxy-3,5-dimethylphenyl) methane, 1,1-bis (4-hydroxyphenyl) cyclopentane, 1,1-bis (3-methyl-4-hydroxyphenyl) cyclopentane, 3,3-bis (4-hydroxyphenyl) pentane, 3,3-bis (3-methyl-4-hydroxyphenyl) pentane, 3,3-bis (3,5-dimethyl-4-hydroxyphenyl) pentane, 2,2-bis ( 2-hydroxy-3,5-dimethylphenyl) propane, 2,2-bis (4-hydroxyphenyl) nonane, 1,1-bis (3-methyl-4-hydroxyphenyl) -1-phenylethane, 1,1 -Bis (3,5-dimethyl-4-hydroxyphenyl) cyclohexane, 2,2-bis (4-hydroxyphenyl) decane, 1,1-bis (4-hydroxy) Droxyphenyl) decane, bis (2-hydroxy-3-tert-butyl-5-methylphenyl) methane, bis (4-hydroxyphenyl) diphenylmethane, terpene diphenol, 1,1-bis (3-tert-butyl- 4-hydroxyphenyl) cyclohexane, 1,1-bis (2-methyl-4-hydroxy-5-tert-butylphenyl) -2-methylpropane, 2,2-bis (3-cyclohexyl-4-hydroxyphenyl) propane 1,1-bis (3,5-ditert-butyl-4-hydroxyphenyl) methane, 1,1-bis (3,5-disec-butyl-4-hydroxyphenyl) methane, 1,1-bis (3-Cyclohexyl-4-hydroxyphenyl) cyclohexane, 1,1-bis (2-hydroxy-3,5-di ert-butylphenyl) ethane, bis (3-nonyl-4-hydroxyphenyl) methane, 2,2-bis (3,5-ditert-butyl-4-hydroxyphenyl) propane, bis (2-hydroxy-3, 5-ditert-butyl-6-methylphenyl) methane, 1,1-bis (3-phenyl-4-hydroxyphenyl) -1-phenylethane, bis (3-fluoro-4-hydroxyphenyl) methane, bis ( 2-hydroxy-5-fluorophenyl) methane, 2,2-bis (4-hydroxyphenyl) -1,1,1,3,3,3-hexafluoropropane, 2,2-bis (3-fluoro-4) -Hydroxyphenyl) propane, bis (3-fluoro-4-hydroxyphenyl) -phenylmethane, bis (3-fluoro-4-hydroxyphenyl) )-(P-fluorophenyl) methane, bis (4-hydroxyphenyl)-(p-fluorophenyl) methane, 2,2-bis (3-chloro-4-hydroxy-5-methylphenyl) propane, 2, 2-bis (3,5-dichloro-4-hydroxyphenyl) propane, 2,2-bis (3-chloro-4-hydroxyphenyl) propane, 1,1-bis (3,5-dibromo-4-hydroxyphenyl) ) Methane, 2,2-bis (3,5-dibromo-4-hydroxyphenyl) propane, 2,2-bis (3-nitro-4-hydroxyphenyl) propane, 3,3′-dimethyl-4,4 ′ -Biphenol, 3,3 ', 5,5'-tetramethyl-4,4'-biphenol, 3,3', 5,5'-tetra-tert-butyl-4,4'-biphenol, bis (4-hydro Cyphenyl) ketone, 3,3′-difluoro-4,4′-biphenol, 3,3 ′, 5,5′-tetrafluoro-4,4′-biphenol, bis (4-hydroxyphenyl) dimethylsilane, bis ( 3-methyl-4-hydroxyphenyl) ether, bis (3,5-dimethyl-4-hydroxyphenyl) ether, bis (2,3,5-trimethyl-4-hydroxyphenyl) -phenylmethane, 2,2-bis (4-hydroxyphenyl) dodecane, 2,2-bis (3-methyl-4-hydroxyphenyl) dodecane, 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) dodecane, 1,1-bis ( 3-tert-butyl-4-hydroxyphenyl) -1-phenylethane, 1,1-bis (3,5-ditert-butyl-4-hydroxypheny ) -1-phenylethane, 1,1-bis (2-methyl-4-hydroxy-5-cyclohexylphenyl) -2-methylpropane, 1,1-bis (2-hydroxy-3,5-ditert-) Butylphenyl) ethane, isatin bisphenol, isatin biscresol, 2,2 ′, 3,3 ′, 5,5′-hexamethyl-4,4′-biphenol, bis (2-hydroxyphenyl) methane, 2,4 '-Methylenebisphenol, 1,2-bis (4-hydroxyphenyl) ethane, 2- (4-hydroxyphenyl) -2- (2-hydroxyphenyl) propane, bis (2-hydroxy-3-allylphenyl) methane, 1,1-bis (2-hydroxy-3,5-dimethylphenyl) -2-methylpropane, 1,1-bis (2-hydroxy-5-tert-butyl) Ruphenyl) ethane, bis (2-hydroxy-5-phenylphenyl) methane, 1,1-bis (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, bis (2-methyl-4-hydroxy-) 5-cyclohexylphenyl) methane, 2,2-bis (4-hydroxyphenyl) pentadecane, 2,2-bis (3-methyl-4-hydroxyphenyl) pentadecane, 2,2-bis (3,5-dimethyl-4) -Hydroxyphenyl) pentadecane, 1,2-bis (3,5-ditert-butyl-4-hydroxyphenyl) ethane, bis (2-hydroxy-3,5-ditert-butylphenyl) methane, 2,2- Bis (3-styryl-4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) -1- (p-nitro Phenyl) ethane, bis (3,5-difluoro-4-hydroxyphenyl) methane, bis (3,5-difluoro-4-hydroxyphenyl) phenylmethane, bis (3,5-difluoro-4-hydroxyphenyl) diphenylmethane, Bis (3-fluoro-4-hydroxyphenyl) diphenylmethane, 2,2-bis (3-chloro-4-hydroxyphenyl) propane, 3,3 ′, 5,5′-tetra-tert-butyl-2,2′- Biphenol, 2,2'-diallyl-4,4'-biphenol, 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethyl-cyclohexane, 1,1-bis (4-hydroxyphenyl)- 3,3,5,5-tetramethyl-cyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3,4-trimethyl Cyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3-dimethyl-5-ethyl-cyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethyl-cyclopentane, 1 , 1-bis (3,5-dimethyl-4-hydroxyphenyl) -3,3,5-trimethyl-cyclohexane, 1,1-bis (3,5-diphenyl-4-hydroxyphenyl) -3,3,5 -Trimethyl-cyclohexane, 1,1-bis (3-methyl-4-hydroxyphenyl) -3,3,5-trimethyl-cyclohexane, 1,1-bis (3-phenyl-4-hydroxyphenyl) -3,3 , 5-trimethyl-cyclohexane, 1,1-bis (3,5-dichloro-4-hydroxyphenyl) -3,3,5-trimethyl-cyclohexane, 9 , 9-bis (4-hydroxyphenyl) fluorene, 9,9-bis (3-methyl-4-hydroxyphenyl) fluorene, 1,1-bis (3,5-dibromo-4-hydroxyphenyl) -3,3 , 5-trimethyl-cyclohexane, bis (4-hydroxyphenyl) sulfone (bisphenol S), bis (2-hydroxyphenyl) sulfone, bis (3,5-dimethyl-4-hydroxyphenyl) sulfone, bis (3,5- Diethyl-4-hydroxyphenyl) sulfone, bis (3-methyl-4-hydroxyphenyl) sulfone, bis (3-ethyl-4-hydroxyphenyl) sulfone, bis (4-hydroxyphenyl) sulfide, bis (3,5- Dimethyl-4-hydroxyphenyl) sulfide, bis (3,5-diethyl-4-hydroxy) Phenyl) sulfide, bis (3-methyl-4-hydroxyphenyl) sulfide, bis (3-ethyl-4-hydroxyphenyl) sulfide, e.g., 2,4-dihydroxydiphenyl sulfone.
Of these, bisphenol A is preferred for reasons of availability.

The alkylene glycol adduct (A-2) of the monomer is a compound obtained by adding 1 to 2 mol of glycol having 2 to 6 carbon atoms such as ethylene glycol or propylene glycol to 1 mol of the monomer, Specific examples include bisphenol A ethylene glycol adducts and bisphenol S ethylene glycol adducts.
In the production method of the present invention, when an alkylene glycol adduct (A-2) is used as the bisphenol compound (A) and lactide is used as the polylactic acid raw material compound (B ′), ethylene glycol or the like is added to the phenolic hydroxyl group. The alcoholic hydroxyl group (A-2) produced by addition of is effective as an initiator for the ring-opening polymerization of lactide, and is preferable in order to increase the copolymerization reaction efficiency.

Examples of the oligomer (A-3) containing a plurality of bisphenol units and having two hydroxyl groups include aromatic polycarbonate oligomers and aromatic polyester oligomers containing the monomer (A-1).
These oligomers (A-3) are required to have two hydroxyl groups. In the oligomer having no two hydroxyl groups, the copolymerization with the polylactic acid raw material component does not proceed well. Usually, aromatic polycarbonates and polyarylates produced by interfacial polycondensation do not have two hydroxyl groups and cannot be used for copolymerization as they are because the ends are blocked. As a method for producing an aromatic polycarbonate oligomer or aromatic polyester oligomer having two hydroxyl groups, a method of depolymerizing an aromatic polycarbonate or aromatic polyester with a diol component, or a phenolic hydroxyl group as a terminal blocking agent during polycondensation And a method using a compound having one alcoholic hydroxyl group.
The diol component of the aromatic polyester oligomer includes the monomer (A-1) as described above, and the acid component includes dicarboxylic acids such as terephthalic acid and isophthalic acid.

In the present invention, the number average molecular weight of the bisphenol compound (A) is determined by the compatibility with the raw material compound (B ′) when copolymerized with the raw material compound (B ′) of polylactic acid, and the polylactic acid type copolymer obtained. From the viewpoint of improving the Tg and transparency of the resin, it is necessary to be 10,000 or less, preferably 7,000 or less, and more preferably 5,000 or less.
The bisphenol compound (A) may be linked by a chain extender described later to increase the molecular weight within the above range.

  In the production method of the present invention, it is necessary to copolymerize 1 to 50% by mass of the bisphenol compound (A) and 99 to 50% by mass of the polylactic acid raw material compound (B ′). By setting the copolymerization ratio of the bisphenol compound (A) to 50% by mass or less, a copolymer resin having a high molecular weight can be obtained, and when the chain extender is used after the copolymerization reaction, the amount added is small. The copolymerization ratio is preferably 40% by mass or less, and more preferably 30% by mass or less. On the other hand, by setting the copolymerization ratio of the bisphenol compound (A) to 1% by mass or more, the Tg of the obtained copolymer resin can be increased, and the heat resistance can be improved.

The copolymerization reaction of the bisphenol compound (A) and the polylactic acid raw material compound (B ′) is carried out by a conventional method.
Specifically, when lactide is used as the raw material compound (B ′) of polylactic acid, the polymerization temperature is 150 to 230 ° C., and a ring-opening polymerization catalyst (such as tin octylate) is used as the catalyst. The time is preferably about 10 to 120 minutes.
When lactic acid is used as the raw material compound (B ′) of polylactic acid, a polyester polymerization catalyst for low temperature polymerization (such as tin chloride) is used as the catalyst in the presence or absence of an organic solvent and a polymerization temperature of 50 to 250 ° C. The pressure is preferably reduced to about 20 hPa or less and the reaction is preferably performed for about 1 to 50 hours.
When a lactic acid oligomer is used as the polylactic acid raw material compound (B ′), a polylactic acid copolymer resin can be obtained by coupling with a bisphenol compound using a coupling agent. Examples of the coupling agent include compounds having two or more functional groups. Examples of the functional group include an isocyanate group, an epoxy group, an amino group, a hydroxyl group, a carboxyl group, an acid chloride, an acid anhydride, and a vinyl group, and the coupling reaction may be performed under reaction conditions suitable for each.

In the production method of the present invention, a chain extender can be used to increase the molecular weight of the polylactic acid copolymer resin. Examples of the chain extender include compounds having two or more functional groups capable of reacting with alcoholic or phenolic hydroxyl groups. Functional groups include isocyanate, carbodiimide, epoxy, acid anhydride, acid chloride, acid anhydride, and acid chloride for alcoholic hydroxyl groups, and epoxy, oxazoline, acid anhydride for phenolic hydroxyl groups. And acid chloride. In order to improve the Tg of the polylactic acid copolymer resin, a chain extender having an aromatic ring is preferably used.
Preferred chain extenders include tolylene diisocyanate, tolidine diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, naphthylene diisocyanate, isophorone diisocyanate, lysine diisocyanate, 1,4-cyclohexane diisocyanate, methylenebiscyclohexyl diisocyanate, bisisocyanatomethylcyclohexane and the like. Diisocyanate such as diisocyanate, resorcinol diglycidyl ether, bisphenol A diglycidyl ether, bisphenol S diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, diglycidyl terephthalic acid, diglycidyl isophthalic acid, ethylene glycol diglycidyl ether, naphthalene tetra carboxylic acid Water, dioxotetrahydrofuranylmethylcyclohexene dicarboxylic anhydride, pyromellitic anhydride, oxydiphthalic anhydride, biphenyl tetracarboxylic anhydride, benzophenone tetracarboxylic anhydride, diphenyl sulfone tetracarboxylic anhydride, tetrafluoroisopropyl Acid anhydrides such as dendiphthalic anhydride, terphenyltetracarboxylic anhydride, cyclobutanetetracarboxylic anhydride, carboxymethylcyclopentanetricarboxylic anhydride, fats such as oxalic acid, malonic acid, succinic acid, cyclohexanedicarboxylic acid And bisoxazolines such as 2,2 ′-(1,3-phenylene) bis-2-oxazoline.
Among them, diisocyanate is particularly preferable for alcoholic hydroxyl groups, and diglycidyl ether and bisoxazoline are particularly preferable for phenolic hydroxyl groups because of high reactivity and easy handling. Furthermore, alicyclic diisocyanates and bisphenol diglycidyl ethers are most suitable because they have a high effect of preventing the Tg from decreasing.
In the production method of the present invention, the chain extender can be used at any stage of production, but it must be after the copolymerization reaction between the bisphenol compound (A) and the polylactic acid raw material compound (B ′). It is preferable because of its high molecular weight.
When the chain extender is reacted, the reaction temperature is preferably not less than the melting point or flow start temperature of the polylactic acid copolymer resin and not more than 230 ° C., and the reaction time is preferably 3 minutes to 2 hours. Is used in such a range that the ratio of the functional group amount of the chain extender to the terminal functional group amount of the polylactic acid copolymer resin to be chain extended (chain extender / copolymer resin) is 0.98 to 1.1. It is preferable that

By the production method of the present invention, a polylactic acid copolymer resin having a weight average molecular weight of 20,000 or more can be produced. When the weight average molecular weight is 20,000 or less, Tg may not be sufficiently high, is preferably 40,000 or more, and more preferably 60,000 or more.
Further, the production method of the present invention can produce a polylactic acid copolymer resin excellent in transparency and having a total light transmittance of 80% or more at a thickness of 100 μm. If the total light transmittance is less than 80%, the use is limited because of poor transparency.

Hereinafter, the present invention will be described specifically by way of examples.
(1) Average molecular weight The average molecular weight was measured using gel permeation chromatography (GPC) equipped with a differential refractometer. Hexafluoroisopropanol containing 10 mM sodium trifluoroacetate was used as an eluent, and the molecular weight was converted using polymethyl methacrylate (manufactured by Polymer Laboratories) as a standard sample.

(2) Glass transition temperature (Tg)
A differential scanning calorimeter (DSC7 manufactured by Perkin Elmer) was used for the measurement of Tg. Tg is preferably 60 ° C. or higher, and more preferably 65 ° C. or higher because the application is expanded.

(3) Total light transmittance The total light transmittance was measured by using a haze meter manufactured by Nippon Denshoku Industries Co., Ltd. after hot-pressing the dispensed resin into a sheet having a thickness of 100 μm at 180 ° C. A total light transmittance of 80% or more was judged to be transparent.

Production Example 1 <Terminal hydroxyl group-containing aromatic polycarbonate oligomer>
In a reaction vessel equipped with a magnetic stir bar and a reflux condenser, 300 mL of 1,2,4-trichlorobenzene, 60 g of aromatic polycarbonate (Caliber 200-13 manufactured by Sumitomo Dow), 8.1 g of bisphenol A, 0.5 g of zinc acetate Was suspended, heated and dissolved at 180 ° C., and stirred for 3 hours. After allowing to cool, the contents were put into 3 L of methanol to precipitate the reaction product, filtered and separated and dried to obtain an aromatic polycarbonate oligomer having a number average molecular weight of 2,500 having a phenolic hydroxyl group at the terminal. .

Production Example 2 <Polylactic acid oligomer containing hydroxyl groups at both ends>
After putting 150 g of L-lactide and 3.5 g of 1,6-hexanediol (HD) in a glass polymerization tube and heating and dissolving in a nitrogen stream, 0.02 g of tin octylate was added, and the mixture was stirred at 180 ° C. with stirring at 180 ° C. Reacted for hours. After 30 minutes at 5 hPa, the product was discharged. The number average molecular weight of the obtained polylactic acid oligomer having an alcoholic hydroxyl group at both ends was 5,000.

Production Example 3 <Terminal hydroxyl group-containing aromatic polycarbonate>
An aromatic polycarbonate having a number average molecular weight of 12,000 having a phenolic hydroxyl group at the terminal was obtained in the same manner as in Production Example 1 except that the amount of bisphenol A was 2.0 g.

Example 1
20 g of bisphenol A and 80 g of L-lactide (manufactured by Musashino Chemical Laboratory) were placed in a glass polymerization tube, replaced with nitrogen gas, and then heated to 190 ° C. with stirring. When the temperature reached 190 ° C., 0.02 g of tin octylate was added. After 1 hour, after the polymerization reaction reached equilibrium, 20 g of bisphenol A diglycidyl ether (BAGE) was added and stirred for 30 minutes. After reducing the pressure to 5 hPa for 30 minutes, the pressure was returned to normal pressure using nitrogen gas, and the polymer in the glass tube was discharged and collected.

Example 2
A polymer was obtained in the same manner as in Example 1 except that 20 g of bisphenol S ethylene glycol adduct (manufactured by Konishi Chemical Co., Ltd.), 80 g of L-lactide, and 13.2 g of isophorone diisocyanate (IPDI) were used.

Example 3
40 g of the aromatic polycarbonate oligomer obtained in Production Example 1 and 60 g of L-lactide were put in a glass polymerization tube and dissolved by heating to 180 ° C. in a nitrogen stream. 0.02 g of tin octylate was added and reacted for 1 hour with stirring. After reducing the pressure to 5 hPa for 30 minutes, the pressure was returned to normal pressure using nitrogen gas, and the polymer in the glass tube was discharged and collected.

Example 4
First, 20 g of bisphenol A and 80 g of L-lactide were put in a glass polymerization tube, and heated to 190 ° C. while stirring under a nitrogen gas stream. After 10 g of BAGE was added and reacted for 30 minutes, 0.02 g of tin octylate was added. After 1 hour, after the polymerization reaction reached equilibrium, 10 g of IPDI was added and reacted for 30 minutes. After reducing the pressure to 5 hPa for 30 minutes, the pressure was returned to normal pressure using nitrogen gas, and the polymer in the glass tube was discharged and collected.

Example 5
20 g of bisphenol A and 80 g of a polylactic acid oligomer having a molecular weight of 5,000 obtained in Production Example 2 were placed in a glass polymerization tube and dissolved by heating to 180 ° C. in a nitrogen stream. After reacting for 1 hour with stirring, 17.3 g of 1,4-cyclohexane diisocyanate (CHDI) was added and reacted for 30 minutes. After reducing the pressure to 5 hPa for 30 minutes, the pressure was returned to normal pressure using nitrogen gas, and the polymer in the glass tube was discharged and collected.

Comparative Example 1
HD 10 g was used in place of bisphenol A, L-lactide 90 g, and IPDI 19 g. Polymerization was carried out in the same manner as in Example 1 to obtain a polymer.

Comparative Example 2 (Synthesis of polylactic acid)
0.07 g of HD and 100 g of L-lactide were placed in a glass polymerization tube, dissolved under heating in a nitrogen stream, 0.02 g of tin octylate was added, and the mixture was reacted at 180 ° C. for 1 hour with stirring. After reducing the pressure to 5 hPa for 30 minutes, the pressure was returned to normal pressure using nitrogen gas, and the resulting polylactic acid was discharged. When measured by GPC, the resulting polylactic acid had a weight average molecular weight of 180,000.

Comparative Example 3
20 g of the aromatic polycarbonate obtained in Production Example 3 and 80 g of L-lactide were put in a glass polymerization tube and dissolved by heating to 190 ° C. in a nitrogen stream. 0.02 g of tin octylate was added and reacted for 1 hour with stirring. After reducing the pressure to 5 hPa for 30 minutes, the pressure was returned to normal pressure using nitrogen gas, and the polymer in the glass tube was discharged and collected.

  The properties of the copolymers obtained in the examples and comparative examples are summarized in Table 1.

  As is clear from Table 1, the copolymer resin produced in each example had a Tg increased as compared with the polylactic acid produced in Comparative Examples 1 and 2 by copolymerizing a bisphenol compound. In Comparative Example 3, when a bisphenol compound having a number average molecular weight of 10,000 or more was copolymerized, the resulting resin composition was opaque and Tg was two at 56 ° C and 136 ° C. It was.

Claims (5)

A method for producing a polylactic acid-based copolymer resin containing a bisphenol-based compound (A) component and a polylactic acid (B) component, the bisphenol-based compound (A) having a number average molecular weight of 10,000 or less 1 to 50% by mass And a polylactic acid raw material compound (B ′) 99 to 50% by mass, and a method for producing a polylactic acid copolymer resin. The bisphenol compound (A) is selected from the group consisting of bisphenol A, bisphenol S ethylene glycol adduct, bisphenol A ethylene glycol adduct, and an aromatic polycarbonate oligomer or aromatic polyester oligomer having a bisphenol unit and two hydroxyl groups. The method for producing a polylactic acid copolymer resin according to claim 1, wherein the compound is a compound. The method for producing a polylactic acid copolymer resin according to claim 1 or 2, wherein the raw material compound (B ') of polylactic acid is lactide. A chain extender having two or more functional groups capable of reacting with a hydroxyl group in the molecule is reacted after the copolymerization reaction of the bisphenol compound (A) and the polylactic acid raw material compound (B '). Item 4. A method for producing a polylactic acid copolymer resin according to any one of Items 1 to 3. The polylactic acid-type copolymer resin obtained by the manufacturing method in any one of Claims 1-4.