JPH06287279A - Production of lactide-based graft copolymer - Google Patents

Abstract

PURPOSE:To produce the subject composition exhibiting transparency, degradability and thermoplastic properties and useful for lamination, etc., by ring-opening graft copolymerization between a lactide and a cellulose ester in the presence of an esterification catalyst. CONSTITUTION:The objective composition is prepared by ring-opening graft copolymerization between (A) a lactide and (B) a cellulose ester or a cellulose ether in the presence of (C) an esterification catalyst. In addition, e.g. a lactide containing L-lactide in an amount of >=90wt.% based on the whole lactide, a cellulose ester (e.g. cellulose acetate) having 50 to 60% esterification degree and >=100 polymerization degree and tin octanate are recommendably used respectively as the components (A), (B) and (C).

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a lactide-based graft copolymer obtained by ring-opening graft copolymerization of lactide with cellulose ester or cellulose ether. The lactide-based graft copolymer obtained by the present invention has transparency and degradability,
It has thermoplastic properties and is useful as resin for lamination, ink, film material and molding resin.

[0002]

2. Description of the Related Art Conventionally, Japanese Patent Application Laid-Open No. 59-86621 discloses a method for graft copolymerizing ε-caprolactone with a cellulose ester for a lactide-based graft copolymer. In addition, the technique of grafting lactide to cellulose is disclosed in Japanese Patent Publication No. 38402/1989.
It is proposed by the gazette.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention JP-A-59-86
In the case of the production method according to Japanese Patent No. 621, due to the nature of the graft chain consisting of ε-caprolactone, the resulting resin becomes cloudy and a resin having good transparency cannot be obtained, and furthermore, the melting point and the glass transition temperature are low. , Thermal properties are not enough. Further, in the production method of Japanese Patent Publication No. 01-38402, since the cellulose is insoluble in lactide and solvent, the ring-opening graft copolymerization initially starts as a heterogeneous reaction, the reaction progresses slowly, and the obtained copolymer is obtained. Is not transparent. Further, the reaction temperature is high, and the case where the cellulose is colored can be seen, and there is a problem that a resin having excellent transparency cannot be obtained.

[0004]

Means for Solving the Problems The inventors of the present invention have made diligent studies on such problems, and as a result, it was found that ring-opening graft copolymerization of lactide, which is a dimer of lactic acid, and cellulose ester or cellulose ether Found that a lactide-based graft copolymer having a sufficient transparency and a melting point required for a molding resin and an appropriate glass transition temperature can be obtained,
The present invention has been completed. That is, the present invention is a method for producing a lactide-based graft copolymer, which comprises subjecting lactide (A) and cellulose ester or cellulose ether (B) to ring-opening graft copolymerization in the presence of an esterification catalyst (C). Is provided.

The lactide (A) used in the present invention is a compound obtained by cyclic dimerization of lactic acid. Two L's for lactide
-L-lactide composed of lactic acid, D-lactide composed of two D-lactic acids, MES composed of L-lactic acid and D-lactic acid
O-lactide is present. L-lactide, or D
-A copolymer containing only one of the lactides is crystallized to obtain a high melting point, and a copolymer containing both L-lactide and D-lactide gives a resin having better transparency. The lactide-based graft copolymer of the present invention can realize preferable resin properties depending on the purpose by arbitrarily combining these three types of lactide.

Among them, in order to develop a high glass transition temperature of not less than 140 ° C. and not less than 40 ° C., lactide (A) contains L-lactide in 75% of the total lactide.
%, More preferably 90% or more of the total lactide in order to obtain a resin having a high melting point of 160 ° C. or higher. The cellulose ester used in the present invention is not particularly limited, but from the viewpoint of obtaining a graft copolymer having good compatibility with lactide and good transparency, the degree of esterification of the hydroxyl group in the cellulose unit is 43% to 43%. Those having a degree of polymerization of about 65 and a degree of polymerization of 100 or more are preferable, and those having a degree of esterification of 50 to 60% and a degree of polymerization of 100 or more are particularly preferably used. More specific examples are those having good compatibility with lactide, such as cellulose acetate and cellulose acetate butyrate, and among them, those having a low boiling point of an organic acid generated by a transesterification reaction, such as cellulose acetate. Particularly preferred.

When the degree of esterification of the hydroxyl group in the cellulose unit is increased, the reaction miscibility is improved and a graft copolymer having good transparency can be obtained, but a polymer having a low melting point and a glass transition point tends to be obtained. . Furthermore, ring-opening graft copolymerization of lactide is possible with cellulose ether as well as cellulose ester, and ethyl cellulose can be mentioned as a specific example. When cellulose ethers are used, those having a lower melting point and glass transition point tend to be obtained than when cellulose esters are used. Therefore, depending on the use, in order to obtain a graft copolymer having a low melting point and a low glass transition point, it is preferable to use cellulose ether or to lower the esterification degree of the hydroxyl group in the cellulose unit of the cellulose ester to less than 40%, They are each determined by the intended use of the graft copolymer.

Examples of the esterification catalyst (C) used in the present invention include metals such as tin, zinc, lead, titanium, bismuth, zirconium and germanium, and their derivatives. Particularly, the derivatives include metal organic compounds and carbonates. , Oxides and halides are preferred. Specifically, tin octoate, tin chloride, zinc chloride, lead oxide, lead carbonate, titanium chloride, alkoxy titanium, germanium oxide, and zirconium oxide are suitable as the esterification catalyst.

In the method for producing the graft copolymer of the present invention, the weight ratio (A) / lactide (A) to cellulose ester or cellulose ether (B) used is (A) /
(B) is preferably 1 or more, that is, 1 to 50 parts by weight of cellulose ester or cellulose ether (B) is added to 99 to 50 parts by weight of lactide to perform ring-opening graft copolymerization. In particular, when the weight ratio (A) / (B) of lactide (A) and cellulose ester or cellulose ether (B) is 70/30 or more, the cellulose ester or cellulose ether is easily dissolved in lactide and the reaction progresses. It is preferable because it proceeds easily. That is, it is preferable to add 1 to 30 parts by weight of cellulose ester or cellulose ether (B) to 99 to 70 parts by weight of lactide to perform ring-opening graft copolymerization.

To obtain the lactide copolymer by the method of the present invention, for example, lactide (A) and cellulose ester or cellulose ether (B) are heated or mixed with a solvent, and then a catalyst is added. The reaction temperature is preferably lower than the melting point of lactide and lower than or equal to the melting point of cellulose ester or cellulose ether, because the obtained lactide-based graft copolymer can be prevented from being colored. Below the melting point of the lactide, the reaction system is not suitable because it is difficult to be homogeneous, and above the melting point of the cellulose ester or cellulose ether, the cellulose ester or cellulose ether (B) is decomposed and coloring occurs. Specifically, the reaction temperature is preferably from the melting point of lactide to 180 ° C. or less because it can prevent coloring of the obtained lactide-based graft copolymer.

The reaction is preferably carried out in a dry inert gas atmosphere. Especially under nitrogen and argon gas atmosphere,
Alternatively, the reaction is performed in a bubbling state. At the same time, it is necessary to remove water from the lactide (A), cellulose ester or cellulose ether (B) which is a raw material, and to dry it. The reaction can be carried out under reduced pressure for the purpose of removing the organic acid generated by the transesterification reaction, the residual lactide and the solvent, and these can be carried out continuously. Further, these can be removed under reduced pressure after the reaction.

The lactide-type graft copolymer of the present invention alone has a sufficient plasticizing action and has moldability, but if necessary, after polymerization of polyester, epoxy derivative, phthalate ester, polyether, or the like, or Further good thermoplasticity can be imparted by adding it at the time of molding. Specific examples thereof include ordinary plasticizers, adipic acid type polyesters, sebacic acid type polyesters, fatty acid epoxy derivatives, diethyl phthalate, dioctyl phthalate, diphenyl phthalate, dicyclohexyl phthalate and polyethylene glycol.

If necessary, stabilizers such as phosphoric acid esters, isocyanates, carbodiimides, etc. may be added to the graft copolymer of the present invention to improve the thermal stability during molding. The lactide-based graft copolymer of the present invention is a biodegradable copolymer composed of cellulose and lactic acid, and is a versatile molding resin that is biodegradable in nature and is suitable for the global environment.

[0014]

EXAMPLES The present invention will be described more specifically by showing Examples and Comparative Examples below. All parts in the examples are by weight unless otherwise specified.

[Example 1] Cellulose acetate (degree of acetylation 55
%, Average degree of polymerization 140) 90 parts of lactide was added to 10 parts, and both were melted and mixed at 165 ° C. for 1 hour under an inert gas atmosphere, and 0.02 part of tin octoate was added as an esterification catalyst. After that, the reaction was carried out for 8 hours, and the lactide-based graft copolymer produced was taken out. A brownish transparent resin was obtained. From the result of gel permeation chromatography (hereinafter abbreviated as GPC), a graft copolymer having a molecular weight larger than that of the raw material cellulose acetate was confirmed.

In addition, the presence of a low molecular weight polymer (lactide homopolymer) having an average molecular weight of about 20,000 was recognized, and 2% of the lactide monomer remained. As a result of differential calorimetric analysis (hereinafter abbreviated as DSC) of this lactide-based graft copolymer, the glass transition point was 51.3 ° C, and the melting point was 162.5 ° C. The glass transition point and the melting point peak in DSC are single, indicating that the compositions are mixed without phase separation.

[Example 2] Cellulose acetate (degree of acetylation 55
%, Average degree of polymerization 180) 90 parts lactide was added to 10 parts, and both were melted and mixed at 165 ° C. for 1 hour in an inert gas atmosphere, and 0.02 part tin octoate was added as an esterification catalyst. It was Thereafter, the reaction was carried out for 8 hours, and the produced lactide-based graft copolymer was taken out. A brownish transparent resin was obtained. From the results of GPC, a lactide-based graft copolymer was confirmed, and other low molecular weight polymers were also confirmed. Lactide monomer is 3.
9% remained. As a result of DSC of this graft copolymer, the glass transition point was 50.7 ° C., and the melting point was 159.5.
It was ℃. It was also shown that the compositions were mixed without phase separation.

Example 3 Cellulose acetate (Acetification degree 6
0.8%, average degree of polymerization of 360) 98 parts of lactide was added to 2 parts, and the atmosphere was replaced with an inert gas.
Both were melted and mixed for a period of time, and 0.02 part of tin octoate was added as an esterification catalyst. Thereafter, the reaction was carried out for 8 hours, and the produced lactide-based graft copolymer was taken out. A colorless transparent resin was obtained. From the result of GPC, a lactide-based graft copolymer was confirmed. Lactide homopolymer was also confirmed. 3.1% of the lactide monomer remained. As a result of DSC, the glass transition point was 51.4 ° C and the melting point was 174.5 ° C. It was also shown that the compositions were mixed without phase separation.

[Example 4] Cellulose acetate (Acetification degree: 6)
95 parts of lactide was added to 5 parts of 0.8% and an average degree of polymerization of 360), and both were melted and mixed at 165 ° C. for 1 hour. 0.02 part of tin octoate was added as an esterification catalyst, and the reaction was carried out under reduced pressure (about 10 mmHg) for 8 hours. A yellowish transparent resin was obtained. From the result of GPC, a lactide-based graft copolymer was confirmed. Lactide homopolymer was also confirmed. 3.4% of the lactide monomer remained. As a result of DSC, the glass transition point was 54.6 ° C and the melting point was 157.0 ° C. It was also shown that the compositions were mixed without phase separation.

Example 5 90 parts of lactide was added to 10 parts of cellulose acetate butyrate, and 0.02 part of tin octoate was added as an esterification catalyst to carry out the reaction. The lactide-based graft copolymer obtained was a brown, transparent resin. From the result of GPC, a lactide-based graft copolymer was confirmed. 3.1% of the lactide monomer remained. As a result of DSC, the glass transition point was 48.8 ° C,
The melting point was 144.6 ° C. It was also shown that the compositions were mixed without phase separation.

Example 6 90 parts of lactide was added to 10 parts of ethyl cellulose, and 0.02 part of tin octoate was added as an esterification catalyst to carry out the reaction. The obtained lactide-based graft copolymer was a dark brown, flexible resin. From the result of GPC, a cellulose derivative copolymerized with lactide was confirmed. 15.1 for lactide monomer
% Remained. As a result of DSC, the glass transition point was room temperature or lower.

Comparative Example 1 Cellulose acetate (degree of acetylation 55
%, Average degree of polymerization 140) 10 parts of ε-caprolactone 9
0 part was added, and both were melted and mixed at 165 ° C. for 1 hour under an inert gas atmosphere, and 0.02 part of tin octoate was added as an esterification catalyst. Thereafter, the reaction was carried out for 8 hours, and the produced composition was taken out. The resulting composition was a white opaque, brittle resin. From the results of GPC, ε-
A cellulose derivative copolymerized with caprolactone was confirmed. Epsilon-caprolactone homopolymer was also confirmed.
As a result of DSC of this composition, the glass transition point was room temperature or lower and the melting point was 53.0 ° C.

[Comparative Example 2] 90 parts of lactide was added to 10 parts of cellulose, and both were mixed in an inert gas atmosphere at 165 ° C for 1 hour, but cellulose was not compatible with lactide. 0.02 part of tin octoate was added as an esterification catalyst, and the reaction was carried out for 8 hours. Cellulose did not dissolve during the reaction and became colored brown. The composition produced was the homopolymer of polylactide only, and no lactide copolymer was produced.

[0024]

INDUSTRIAL APPLICABILITY The present invention provides a lactide-based graft copolymer having transparency, decomposability and thermoplastic properties, which is useful as a lamination material, an ink resin, a film material, and a molding resin. A manufacturing method can be provided.

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[Procedure amendment]

[Submission date] March 16, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

Above all, a melting point of 140 ° C. or higher and a melting point of 40
° C. In order to express the above glass transition point, lactide (A) is preferably one containing L- lactide 75% or more in the total lactide, to obtain a further 160 ° C. or more high-melting resin L- 90% of total lactide with lactide
Those including the above are preferable. The cellulose ester used in the present invention is not particularly limited, but from the viewpoint of obtaining a graft copolymer having good compatibility with lactide and good transparency, the esterification degree of the hydroxyl group in the cellulose unit is 43% to It is preferable that the degree of polymerization is about 65 and the degree of polymerization is 100 or more, and the degree of esterification is 50-60.
%, And the degree of polymerization is 100 or more is particularly preferably used. More specific examples are those having good compatibility with lactide, such as cellulose acetate and cellulose acetate butyrate, and among them, those having a low boiling point of an organic acid generated by a transesterification reaction, such as cellulose acetate. Particularly preferred.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

When the degree of esterification of the hydroxyl group in the cellulose unit is increased, the reaction miscibility is improved and a graft copolymer having good transparency can be obtained, but a polymer having a low melting point and a glass transition point tends to be obtained. . Furthermore, ring-opening graft copolymerization of lactide is possible with cellulose ether as well as cellulose ester, and ethyl cellulose can be mentioned as a specific example. When cellulose ethers are used, those having a lower melting point and glass transition point tend to be obtained than when cellulose esters are used. Therefore, depending on the application, in order to obtain a graft copolymer having a low melting point and a low glass transition point, it is preferable to use cellulose ether or to increase the degree of esterification of hydroxyl groups in the cellulose unit of cellulose ester to 40% or more, They are each determined by the intended use of the graft copolymer.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

To obtain a lactide-type copolymer by the method of the present invention, for example, lactide (A) and cellulose ester or cellulose ether (B) are heated, or a solvent such as benzene, toluene, xylene or cyclohexyl is used.
Hexane, methyl ethyl ketone, methyl isobutyl keto
After mixing with methanol, isopropyl ether, etc. , the catalyst is added. The reaction temperature of above the melting point of the lactide, the reaction temperature below the melting point of the cellulose ester or cellulose ether is desirably prevents coloration of the resulting lactide based graft copolymer. Below the melting point of the lactide, the reaction system is not suitable because it is difficult to be homogeneous, and above the melting point of the cellulose ester or cellulose ether, the cellulose ester or cellulose ether (B) is decomposed and coloring occurs. Specifically, the reaction temperature is preferably from the melting point of lactide to 180 ° C. or less because it can prevent coloring of the obtained lactide-based graft copolymer.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

Example 5 90 parts of lactide was added to 10 parts of cellulose acetate butyrate, and 0.02 part of tin octoate was added as an esterification catalyst under the same reaction conditions as in Example 1.
The reaction was carried out. The lactide-based graft copolymer obtained was a brown, transparent resin. From the result of GPC, a lactide-based graft copolymer was confirmed. 3.1% of the lactide monomer remained. As a result of DSC, the glass transition point was 48.8 ° C and the melting point was 144.6 ° C. It was also shown that the compositions were mixed without phase separation.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

[Example 6] 90 parts of lactide was added to 10 parts of ethyl cellulose, and 0.02 part of tin octoate was added as an esterification catalyst, and the reaction was carried out under the same reaction conditions as in Example 1 . . The obtained lactide-based graft copolymer was a dark brown, flexible resin. From the result of GPC, a cellulose derivative copolymerized with lactide was confirmed. 15.1% of the lactide monomer remained. As a result of DSC, the glass transition point was room temperature or lower.

Claims (5)

[Claims] 1. A process for producing a lactide-based graft copolymer, which comprises subjecting lactide (A) and a cellulose ester or cellulose ether (B) to ring-opening graft copolymerization in the presence of an esterification catalyst (C). . 2. A weight ratio (A) / of lactide (A) and cellulose ester or cellulose ether (B).
The method according to claim 1, wherein (B) is 1 or more. 3. The method according to claim 1, wherein the ring-opening graft copolymerization is carried out at a temperature not lower than the melting point of lactide and lower than the melting point of cellulose ester or cellulose ether (B). 4. The method according to claim 1, wherein the ring-opening graft copolymerization is carried out under atmospheric pressure. 5. The production method according to claim 1, wherein the cellulose ester or cellulose ether (B) is cellulose acetate and / or cellulose acetate butyrate.