JP2001348423A - Aliphatic polyester resin composition of low carboxylic acid content - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aliphatic polyester resin composition suitable for obtaining moldings such as fibers, injection moldings, sheets, and films and excellent in hydrolysis resistance. SOLUTION: Provided is an aliphatic polyester resin composition containing (A) an aliphatic polyester, wherein the carboxylic acid content is at most 0.1 mmol/g.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aliphatic polyester resin composition having excellent hydrolysis resistance, which is used for producing molded articles such as fibers, injection molded articles, sheets and films.

[0002] That is, the present invention relates to an aliphatic polyester resin composition having a small amount of carboxylic acid. For more information,
Contains aliphatic polyester (A) and has a carboxylic acid content of 0.1
The present invention relates to an aliphatic polyester resin composition of not more than mmol / g.

[0003]

2. Description of the Prior Art Aliphatic polyesters are generally recognized for their biodegradability, and are expected to be used in fibers, molded articles, sheets and films by utilizing their characteristics.

As the aliphatic polyesters known so far, there can be mentioned, for example, aliphatic polyesters having terminal hydroxyl groups (JP-A-5-310898).

[0005]

The carboxylic acid in the aliphatic polyester resin composition causes a decrease in the hydrolysis resistance of the aliphatic polyester resin composition. For example, when formed into a film, physical properties such as strength may be significantly reduced with time.

The inventors of the present invention have found that it is difficult to completely prevent unreacted raw materials from remaining during the synthesis of an aliphatic polyester and to make all the terminals hydroxyl groups. It has been found that it is difficult to reduce the amount of carboxylic acid in the product to 0.1 mmol / g or less.

The carboxylic acid in the aliphatic polyester resin composition is generally determined by dissolving the aliphatic polyester resin composition in a solvent such as chloroform and titrating with an alcoholic alkali solution. However, in this method, the mixed state of the solvent dissolving the polymer and the alcoholic alkali solution is not good. Therefore, it has been found that it is difficult to obtain a reproducible value in a region where the amount of carboxylic acid is small.

An object of the present invention is to solve the above problems of the aliphatic polyester and to provide a new and useful polyester resin composition having a small amount of carboxylic acid.

[0009]

DISCLOSURE OF THE INVENTION The present inventors aimed at providing an aliphatic polyester resin composition having excellent hydrolysis resistance. That is, the amount of carboxylic acid in the aliphatic polyester resin composition containing the aliphatic polyester (A) was 0.1 mm
The above object was achieved by controlling the amount to ol / g or less.

[0010] In order to achieve the above-mentioned object, the present inventors have proposed that the amount of carboxylic acid in the aliphatic polyester resin composition be adjusted to a polar solvent (D) having a solubility parameter of 9.5 to 14.5.
And titration with an alcoholic alkali solution to measure the amount of carboxylic acid in the aliphatic polyester resin composition.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The aliphatic polyester resin composition of the present invention is an aliphatic polyester resin composition containing an aliphatic polyester (A) and having a carboxylic acid content of 0.1 mmol / g or less.

In the present invention, the aliphatic polyester resin composition is an unreacted residue of the aliphatic polyester (A) and the raw materials of the aliphatic polyester (A) (including the additives used during the polymerization). And raw materials that are combined. That is, the present invention is a polyester resin composition produced so that the amount of residual carboxylic acid is extremely small.

In the present invention, the carboxylic acid content means unreacted aliphatic dicarboxylic acid or cyclic acid anhydride and carboxylic acid at the terminal of the polymer. In the case of a cyclic acid anhydride, it is measured as a ring-opened state.

The aliphatic polyester (A) used in the present invention
Is not particularly limited as long as it is an aliphatic polyester, for example, a number average molecular weight of 10,000 to 100,000.
0, preferably 10,000 to 80,000, and more preferably 10,000 to 60,000.

The content of the aliphatic polyester (A) is at least 90% by weight, preferably at least 95% by weight, more preferably at least 98% by weight, most preferably at least 99% by weight in the aliphatic polyester composition. It is.

In the present invention, the carboxylic acid content means unreacted aliphatic dicarboxylic acid or cyclic acid anhydride, and carboxylic acid at the terminal of a polymer, and the number of equivalents is measured by a measuring method described in Examples described later. It means the value that was done.

In order not to lower the hydrolyzability of the aliphatic polyester resin composition, the amount of carboxylic acid in the aliphatic polyester resin composition must be 0.1 mmol / g or less, preferably 0.05 mmol / g or less, more preferably 0.05 mmol / g or less. Preferably
It must be 0.02 mmol or less, most preferably 0.01 mmol or less.

The aliphatic polyester (A) used in the present invention
Can be obtained by a) a method of ring-opening polymerization of a cyclic acid anhydride and a cyclic ether, a method of polycondensing a glycol with a polybasic acid (or its ester), and a method of c) a hydroxycarboxylic acid (or its ester). A method of polycondensation, and a method of ring-opening polymerization of a cyclic ester.

The cyclic acid anhydride used in the method a) includes, for example, succinic anhydride, maleic anhydride, itaconic anhydride, glutaric anhydride, adipic anhydride, citraconic anhydride and the like. In view of economy, it is preferable that succinic anhydride is the main component. Further, a small amount of a polyfunctional acid anhydride having two or more acid anhydride groups such as pyromellitic anhydride may be added. Examples of the cyclic ether include ethylene oxide, propylene oxide, cyclohexene oxide, styrene oxide, epichlorohydrin, allyl glycidyl ether, phenyl glycidyl ether, tetrahydrofuran, oxepane, 1,3-dioxolan and the like. Considering this, it is preferable to use ethylene oxide as a main component. Among these, a combination of succinic anhydride and ethylene oxide is preferable in consideration of the melting point, biodegradability, and economic efficiency of the obtained polyester. The ring-opening polymerization can be carried out using a known ring-opening polymerization catalyst by a method such as polymerization in a solvent or bulk polymerization.

Examples of the polybasic acid used in the method (b) include succinic acid, adipic acid, suberic acid, sebacic acid, azelaic acid, decanedicarboxylic acid, octadecanedicarboxylic acid, dimer acid and esters thereof. Examples of the glycol include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, decamethylene glycol and the like. It is also possible to use polyoxyalkylene glycol as a part of the glycol component, and examples thereof include polyoxyethylene glycol, polyoxypropylene glycol, polyoxytetramethylene glycol and copolymers thereof. Among these, a combination of succinic acid and ethylene glycol and / or succinic acid and 1,4-butanediol is preferable in consideration of the melting point, biodegradability, and economy of the obtained polyester. In the production of the aliphatic polyester (A), the total amount of the polybasic acid (or ester thereof) component and the glycol component may be initially mixed and reacted, or may be added in portions as the reaction proceeds. . The polycondensation reaction can be carried out by a usual transesterification method or esterification method, or a combination of the two methods. If necessary, the degree of polymerization can be increased by increasing or decreasing the pressure in the reaction vessel.

Examples of the hydroxycarboxylic acid used in the method (c) include glycolic acid, lactic acid, 3-hydroxypropionic acid, 3-hydroxy-2, 2-dimethylpropionic acid, 3-hydroxy-3-methyl-butyric acid, 4
-Hydroxybutyric acid, 5-hydroxyvaleric acid, 3-hydroxybutyric acid, 3-hydroxyvaleric acid, 4-hydroxyvaleric acid, 6-hydroxycaproic acid, citric acid, malic acid and esters thereof. As the polycondensation reaction, there is no problem by using a usual transesterification method or esterification method or a combination of both methods. If necessary, the degree of polymerization can be increased by increasing or decreasing the pressure in the reaction vessel.

Examples of the cyclic ester used in the method (d) include β-propiolactone and β-methyl-β-
And propiolactone, δ-valerolactone, ε-caprolactone, glycolide, lactide and the like. The ring-opening polymerization can be carried out using a known ring-opening polymerization catalyst by a method such as polymerization in a solvent or bulk polymerization.

Among the methods for obtaining such an aliphatic polyester (A), the method of a) ring-opening polymerization of a cyclic acid anhydride and a cyclic ether is preferred as a method which can be industrially and efficiently produced in a relatively short time. . Hereinafter, the ring-opening polymerization of a cyclic acid anhydride and a cyclic ether will be described in more detail.

It has been known that the cyclic acid anhydride such as succinic anhydride used in the present invention does not homopolymerize when used alone as an acid component. By cyclically adding cyclic ether in the presence of a polymerization catalyst to such a cyclic acid anhydride that is not homopolymerized and polymerizing, a polyester in which an acid component and an alcohol component are substantially copolymerized alternately can be produced in a short time. Can be generated.

The polymerization can be carried out by a method such as polymerization in a solvent or bulk polymerization. In polymerization in a solvent, the cyclic acid anhydride is used after being dissolved in a solvent. In bulk polymerization, the cyclic acid anhydride can be melted before use in the present invention.

The polymerization in a solvent can be carried out either batchwise or continuously. Examples of the solvent used include benzene, toluene, xylene, cyclohexane, n
-Inert solvents such as hexane, dioxane, chloroform and dichloroethane.

The polymerization catalyst is not particularly limited, and those usually used in ring-opening polymerization of polyester are used. For example, tetramethoxy zirconium, tetraethoxy zirconium, tetra-iso-propoxy zirconium, tetra-iso-butoxy zirconium, tetra-n-butoxy zirconium, tetra-t-butoxy zirconium, triethoxy aluminum, triethoxy aluminum, tri-n-propoxy aluminum, tri- iso-propoxyaluminum, tri-n-butoxyaluminum, tri-i
So-butoxyaluminum, tri-sec-butoxyaluminum, mono-sec-butoxy-di-iso-
Propoxy aluminum, ethyl acetoacetate aluminum diisopropylate, aluminum tris (ethyl acetoacetate), tetraethoxy titanium, tetra-iso-propoxy titanium, tetra-n-propoxy titanium, tetra-n-butoxy titanium, tetra-se
c-butoxytitanium, tetra-t-butoxytitanium, tri-iso-propoxygallium, tri-iso-propoxyantimony, tri-iso-butoxyantimony, trimethoxyboron, triethoxyboron, triethoxyboron
iso-propoxyboron, tri-n-propoxyboron, tri-iso-butoxyboron, tri-n-butoxyboron, tri-sec-butoxyboron, tri-t-
Butoxyboron, tri-iso-propoxygallium,
Tetramethoxygermanium, tetraethoxygermanium, tetra-iso-propoxygermanium, tetra-n-propoxygermanium, tetra-iso-butoxygermanium, tetra-n-butoxygermanium, tetra-sec-butoxygermanium, tetra-
metal alkoxides such as t-butoxygermanium; antimony pentachloride, zinc chloride, lithium bromide, tin chloride (I
V), halides such as cadmium chloride and boron trifluoride diethyl ether; trimethylaluminum, triethylaluminum, diethylaluminum chloride, ethylaluminum dichloride, tri-iso-
Alkyl aluminum such as butyl aluminum; alkyl zinc such as dimethyl zinc, diethyl zinc, diisopropyl zinc; tertiary amine such as triallylamine, triethylamine, tri-n-octylamine, benzyldimethylamine; phosphotungstic acid, phosphomolybdic acid, silica Heteropoly acids such as tungstic acid and alkali metal salts thereof; zirconium oxychloride, zirconyl octylate, zirconyl stearate, zirconium compounds such as zirconyl nitrate and the like, among which zirconyl octylate, tetraalkoxy zirconium,
Trialkoxy aluminum compounds are particularly preferred. The amount of the polymerization catalyst used is not particularly limited, but is usually 0.001 to 1 based on the total amount of the cyclic acid anhydride and the cyclic ether.
0% by weight. Regarding the method of adding the polymerization catalyst, the polymerization catalyst may be added to the cyclic acid anhydride or may be added sequentially like a cyclic ether.

The polymerization temperature is not particularly limited as long as it is a temperature at which the cyclic acid anhydride reacts with the cyclic ether.
° C, preferably 50 to 150 ° C, more preferably 10 ° C.
0-150 ° C. During the reaction, the pressure in the reaction vessel varies depending on the reaction temperature, the presence or absence of a solvent, and the type of solvent.However, the increase in unreacted cyclic ether due to the increase in pressure due to the sequential addition of cyclic ether increases the amount of polyether in the reaction product. It is not preferable because the ether component is increased. Therefore, the pressure in the reaction vessel is preferably from normal pressure to 5,000 kPa, and more preferably, the cyclic ether is added so as to be normal pressure to 1,500 kPa.

The cyclic ether is added in an amount of 3 to 9 per hour based on 100 parts by weight of the cyclic acid anhydride.
The amount is preferably 0 parts by weight, more preferably 5 to 50 parts by weight.

If the addition rate of the cyclic ether is lower than the lower limit of 3 parts by weight, the reaction is prolonged and the productivity is lowered, which is not industrially preferable. On the other hand, if it is higher than the upper limit of 90 parts by weight, the polyether component in the reaction product increases and only a polyester having a low melting point can be obtained.

The term "sequential addition of the cyclic ether" means that the cyclic ether is not added all at once, and may be either a method of dropping continuously or a method of intermittent addition in multiple stages. It is preferable to add continuously so that the amount of addition does not largely change over time.

In the present invention, the reaction ratio between the cyclic acid anhydride and the cyclic ether is 40/60 to 6 in terms of the molar ratio of these.
The ratio is preferably set to 0/40. Considering that the residual cyclic acid anhydride and the terminal carboxyl group of the polyester reduce the physical properties of the polyester, the ratio of 40/40 is added in order to add the cyclic ether (C) in excess. 60-4
More preferably, the ratio is 5/55.
By doing so, less than 5% of the polyester becomes a carboxyl group, and the hydrolysis resistance is improved.

If the ratio is out of the range, the unreacted monomer may increase and the yield may decrease. In the present invention, it is preferable that after the sequential addition of a predetermined amount of the cyclic ether determined in consideration of the above molar ratio, polymerization is continued at the reaction temperature to ripen. The polyester formed from the polymerization system after the aging reaction may be separated.

The polyester obtained by any of the methods (a), (b), (c) and (d) may be further increased in molecular weight by a transesterification reaction. The molecular weight may be increased by a coupling agent such as an acid anhydride, an epoxy compound, an isocyanate compound, an aldehyde compound, a phosphorus compound, a silane compound, and a metal alkoxide.

The aliphatic polyester resin composition of the present invention can be used as it is. However, if necessary, a general resin solution such as an antioxidant, a crystal nucleating agent, a filler, a lubricant, and an antistatic agent may be used. An additive may be added and used.

The aliphatic polyester resin composition of the present invention has a molecular weight retention of 0.9 or more in a hydrolysis measurement method described in Examples described later, is excellent in hydrolysis resistance, and is obtained by fiber injection molding. Suitable for obtaining molded articles such as bodies, sheets and films.

The method for measuring the amount of carboxylic acid in the aliphatic polyester resin composition according to the present invention is as follows.
It is characterized in that a polar solvent (D) of 9.5 to 14.5 is mixed and titrated with an alcoholic alkali solution.

The polar solvent (D) having a solubility parameter of 9.5 to 14.5 used in the measurement method of the present invention includes alkyl alcohol, alkyl ketone, fatty acid nitrile,
Examples of alkyl alcohols such as pyridine nitrobenzene include, for example, aliphatic saturated alcohols such as methanol, ethanol, propanol and butanol, allyl alcohol, aliphatic unsaturated alcohols such as crotyltyl alcohol, cyclopentanol,
Examples include alicyclic alcohols such as cyclohexanol, and aromatic alcohols such as benzyl alcohol and cinnamyl alcohol.

Examples of the alkyl ketone include, for example, aliphatic saturated ketones such as acetone, methyl ethyl ketone, methyl propyl ketone and dimethyl ketone, unsaturated ketones such as methyl vinyl ketone and mesityl oxide, and alicyclic ketones such as cyclobutanone and cyclopentanone. And aromatic ketones such as acetophenone and propiophenone.

As the fatty acid nitrile, for example, acetonitrile, ethyl cyanide and the like can be mentioned.

Among them, alkyl alcohols are preferred, and aromatic alcohols are most preferred.

In the aliphatic polyester resin composition / chloroform solution, chloroform is preferably used in an amount of 5 to 50 parts by weight, more preferably 10 to 20 parts by weight, based on 1 part by weight of the aliphatic polyester resin composition. Percentage.

The polar solvent (D) is preferably added in an amount of 1 to 100 parts by weight, more preferably 5 to 20 parts by weight, based on 10 parts by weight of the aliphatic polyester resin composition / chloroform solution.

Examples of the alcoholic alkali solution used for the titration include a methanolic sodium hydroxide solution, a methanolic potassium hydroxide solution, an ethanolic sodium hydroxide solution, and an ethanolic potassium hydroxide solution.

[0045]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. The parts in the examples represent parts by weight. The evaluation methods performed in the examples are as follows. (Molecular Weight) Gel Permeation Chromatograph (GP
C) Device (Tosoh Corporation high-speed GPC device HLC-802
Using 0), the number average molecular weight in terms of polystyrene was measured.

(Melting Point) The melting point was measured by a differential scanning calorimeter (SSC5200, manufactured by Seiko Instruments Inc.).

(Amount of carboxylic acid) 1 part of the aliphatic polyester resin composition is dissolved in 9 parts of chloroform. 10 parts of benzyl alcohol is added to this solution, and a few drops of a mixed ethanol solution of phenolphthalein and BTB are added as indicators. This solution was titrated with a 0.05 mol / l solution of potassium hydroxide in ethanol to determine the amount of carboxylic acid.

(Hydrolysis resistance) 4 parts of talc as a nucleating agent, 1 part of stearic acid as a lubricant, and pentaerythrityl-tetrakis [3- (3,5) as an antioxidant were added to 100 parts of the aliphatic polyester resin composition. -Di-t-butyl-
4-Hydroxyphenyl) propionate] (trade name
After kneading 0.5 part of IRGANOX 1010 (manufactured by Ciba Specialty Chemicals) using a Labo Plastomill (manufactured by Toyo Seiki Seisaku-sho, Ltd.) under a melting temperature of 130 ° C., a thickness of 0.1 to 0.2 mm was obtained. Form into a film. The hydrolyzability (moisture and heat resistance) of this film at high temperatures was measured. That is, this film was subjected to a temperature of 50 ° C. and a humidity of 9
It was left in a 0% Rh atmosphere, and the molecular weight retention after one week was calculated by the following equation. (Molecular weight retention rate) = (Number average molecular weight one week after standing) /
(Number average molecular weight before measurement) (Example 1) 86.67 parts of succinic anhydride purified by distillation in a 1-liter autoclave equipped with a high-viscosity stirrer that was sufficiently purged with nitrogen and dried (manufactured by Nippon Rika Co., Ltd.) After dehydration and drying with calcium hydride, 0.98 part of filtered zirconyl octylate (manufactured by Daiichi Kagaku Kagaku Kogyo Co., Ltd.) and 130 parts of toluene dried with molecular sieves were added, and the atmosphere was replaced with nitrogen. Then, the temperature of the autoclave was gradually raised to 130 ° C. with stirring to melt succinic anhydride,
At the same temperature, the pressure inside the autoclave is 420 to 795 kP
While maintaining at a, 55.89 parts of ethylene oxide (manufactured by Nippon Shokubai Co., Ltd.) were continuously introduced over 5 hours at an addition rate of 11.18 parts per hour. 1 after introduction of ethylene oxide
After an aging reaction at 30 ° C. for 1 hour, the system was returned to room temperature to obtain an aliphatic polyester. The number average molecular weight by GPC measurement was 50500, and the melting point by differential scanning calorimetry was 95.0 ° C. The carboxylic acid content of the aliphatic polyester resin composition (2) was 0.0042 m.
mol / g, and the molecular weight retention in wet heat resistance measurement was 0.96.

(Example 2) 86.67 parts of succinic anhydride (manufactured by Nippon Rika Co., Ltd.) distilled and purified in a 1-liter autoclave equipped with a high-viscosity stirrer, which had been sufficiently purged with nitrogen and dried, was treated with calcium hydride. After dehydration and drying, 0.98 parts of filtered zirconyl octylate (manufactured by Daiichi Kagaku Kagaku Kogyo Co., Ltd.) and pyromellitic anhydride (reagent manufactured by Wako Pure Chemical Industries, Ltd.) were added.
20 parts and 130 parts of toluene dried with molecular sieves were added, and the atmosphere was replaced with nitrogen. Then, the temperature of the autoclave was gradually raised to 130 ° C. with stirring to melt the succinic anhydride, and the pressure inside the autoclave was increased to 42 at the same temperature.
While maintaining the pressure at 0 to 795 kPa.
89 parts (manufactured by Nippon Shokubai Co., Ltd.) were continuously introduced over 5 hours at an addition rate of 11.18 parts per hour. After introducing ethylene oxide, an aging reaction was performed at 130 ° C. for 1 hour, and then the system was returned to room temperature to obtain an aliphatic polyester. The number average molecular weight by GPC measurement was 59,800, and the melting point by differential scanning calorimetry was 95.5 ° C. The carboxylic acid content of the aliphatic polyester resin composition is 0.1.
0068 mmol / g, and the molecular weight retention in wet heat resistance measurement was 0.94.

(Comparative Example) 86.67 parts of succinic anhydride (manufactured by Nippon Rika Co., Ltd.) distilled and purified in a 1-liter autoclave equipped with a high-viscosity stirrer which was sufficiently purged with nitrogen and dried, and dehydrated with calcium hydride After drying, 0.98 part of filtered zirconyl octylate (manufactured by Daiichi Kagaku Kagaku Kogyo Co., Ltd.) and 130 parts of toluene dried with molecular sieves were added, followed by purging with nitrogen. Then, the temperature of the autoclave was gradually raised to 130 ° C. with stirring to melt the succinic anhydride, and the pressure in the autoclave was raised to 420 at the same temperature.
43.8 ethylene oxide while maintaining the pressure at ~ 795 kPa.
Seven parts (manufactured by Nippon Shokubai Co., Ltd.) were continuously introduced over 5 hours at an addition rate of 8.77 parts per hour. After introducing ethylene oxide, an aging reaction was performed at 130 ° C. for 1 hour, and then the system was returned to room temperature to obtain an aliphatic polyester. G
The number average molecular weight by PC measurement was 49500, and the melting point by differential scanning calorimetry was 95.0 ° C. The aliphatic polyester resin composition (2) has a carboxylic acid content of 0.1.
It was 24 mmol / g, and the molecular weight retention in wet heat resistance measurement was 0.81.

[0051]

EFFECT OF THE INVENTION The polyester resin composition of the present invention has good heat resistance and can be easily formed into fibers, molded articles, films and sheets, etc. having excellent biodegradability. Therefore,
The polyester resin composition obtained by the present invention can be effectively used for disposable packaging materials, daily necessities and the like.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J029 BA03 BA04 BA05 BA08 CA02 CA04 CA05 CA06 EA03 EA05 EG02 EG07 EG09 EH02 EH03 HA05 HB06 JB232 JB252 JB262 KB02

Claims (4)

[Claims] 1. An aliphatic polyester resin composition containing an aliphatic polyester (A) and having a carboxylic acid content of 0.1 mmol / g or less. 2. The polyester resin composition according to claim 1, wherein the aliphatic polyester (A) is obtained by ring-opening copolymerization of a cyclic acid anhydride (B) and a cyclic ether (C). 3. The aliphatic polyester (A) comprises an aliphatic dicarboxylic acid component having 2 to 6 carbon atoms and 2 to 6 carbon atoms.
And 4 aliphatic glycol components.
The aliphatic polyester resin composition according to claim 1. 4. A method for preparing an aliphatic polyester resin composition, comprising mixing a polar solvent (D) having a solubility parameter of 9.5 to 14.5 with a chloroform solution of the aliphatic polyester resin composition and titrating the mixture with an alcoholic alkali solution. Method for measuring the amount of carboxylic acid.