JP2898526B2 - Method for producing ester-amide copolymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for producing an ester-amide copolymer obtained by ring-opening copolymerization of a cyclic ester and a cyclic amide.

[0002]

2. Description of the Related Art Polyesteramide which is a ring-opening copolymer of a cyclic ester represented by ε-caprolactone (hereinafter referred to as CLN) and a cyclic amide represented by ε-caprolactam (hereinafter referred to as CLM) Can change the composition ratio between the ester and the amide in the copolymer easily produced by changing the charge ratio of the monomer at the time of synthesis. When the copolymerization ratio of CLN is 70% or more, the melting point of the obtained copolymer is as low as about 60 ° C., which poses a practical problem.

Conventionally, when synthesizing an ester-amide copolymer, a polymerization initiator is added to a molten CLM, and then CLN is put into a polymerization vessel at a time to carry out polymerization.
At this time, the amount of the initiator to be added is 0.1 to the total amount of the monomers.
An appropriate amount is 5 to 2 mol%, considering the yield and the physical properties of the resulting copolymer.

[0004]

However, in the above polymerization method, the polymerization rate of CLM is lower than that of CLN.
When the amount of the initiator is small and it takes time to complete the reaction, CLN is polymerized first and the subsequent polymerization of CLM is inhibited.
As a result, the polymerization rate of CLM decreases, and the physical properties of the copolymer decrease. Therefore, it is conceivable to increase the amount of initiator to increase the copolymerization ratio of CLM.

However, when the amount of the initiator is 1 mol% or more of the total amount of the monomers, the ester-amide copolymer produced by the conventional polymerization method cannot be reduced in molecular weight to obtain a copolymer having good physical properties. That is, the copolymer has a problem that the copolymer is fragile and lacks in strength because the molecular weight of the copolymer is low and the strength cannot be maintained.

An ester-amide copolymer obtained from CLN and CLM is expected to be used as a biodegradable plastic having an aliphatic polyester structure. Processability into fibers is an important performance. However, when the amount of the initiator is increased, the molecular weight of the copolymer is reduced, so that there is a problem that it is not practical, such as difficulty in stretching when the copolymer is formed into a film or a fiber. Further, the copolymer produced by increasing the amount of the initiator has a problem that the molding method is limited because the viscosity at the time of melting is low, and the range of application as a plastic is significantly limited.

On the other hand, when the amount of the initiator is reduced to increase the molecular weight, the yield decreases with a decrease in the conversion of CLM, and only a copolymer having a low melting point and poor heat resistance can be obtained.

An object of the present invention is to provide a method for producing an ester-amide copolymer having a high molecular weight and a high amide ratio, which is excellent in physical properties such as melting point and strength in view of the above problems.

[0009]

According to the production method of the present invention, a cyclic ester and a cyclic amide are subjected to ring-opening copolymerization, and then a polybasic acid chloride is added to the obtained molten copolymer. Thus, an ester-amide copolymer having a high molecular weight by bonding copolymer molecules is obtained.

In this case, the copolymerization reaction before the addition of the polybasic acid chloride is carried out in the same manner as in the prior art, for example, when the charge ratio of the cyclic amide is high, the yield increases by increasing the amount of the initiator.
If the copolymer has a low molecular weight, a material having high physical properties cannot be obtained as it is. By adding a polybasic acid chloride to such a copolymer, a high molecular weight copolymer having a high amide ratio and excellent in physical properties and processability can be obtained.

Here, the high molecular weight is defined as G
The weight average molecular weight is 5,000 or more as measured by PC.

Further, during the polymerization reaction between the cyclic amide and the cyclic ester, the cyclic ester may be added dropwise to the cyclic amide. In this case, a copolymer having excellent physical properties and water resistance can be obtained. Therefore, a copolymer having further excellent physical properties can be obtained by adding a polybasic acid chloride.

As the above cyclic esters and cyclic amides, ε-caprolactam and ε-caprolactam are preferred because of their cost and reactivity.
The combination with caprolactone is most suitable, but a cyclic amide such as α-pyrrolidone, γ-laurolactam, and β-
Cyclic esters such as propiolactone, β-butyrolactone, δ-valerolactone, β-methyl-δ-valerolactone, and lactide may be used alone or in combination.

The ratio of ester to amide in the copolymer is preferably 40 to 80% as the copolymerization ratio of amide. If it is less than 40%, the melting point of the produced copolymer becomes low, and there is a practical problem. If it exceeds 80%, the complete biodegradability of the copolymer will be lost.

As the initiator, an alkali metal such as sodium, and its hydride, hydroxide, carbonate,
Alkali catalysts such as alkylated products, alkoxides, and N-substituted lactams are included. Among them, alkali metal alkoxides are preferable because the reaction with the cyclic amide is mild. Alkali metals have the same effect as alkali metal alkoxides, but require careful handling because they react strongly with cyclic amides.

The amount of the initiator used is preferably 0.5 to 3 mol% based on the total amount of the raw material monomers. If it is less than 1 mol%, the conversion of the cyclic amide decreases, and if it is less than 0.5 mol%, the yield is remarkably reduced. This tendency is more remarkable when the charge ratio of the cyclic amide exceeds 30%. Further, even if an initiator exceeding 3 mol% is used, the polymerization yield is hardly improved, and the alkali content remaining in the copolymer increases, which is not preferable.

The copolymerization reaction between the cyclic ester and the cyclic amide before the addition of the polybasic acid chloride is carried out by adding an initiator to the heated and molten cyclic amide and then adding the cyclic ester. After the completion of the copolymerization reaction, the pressure inside the polymerization vessel is reduced, and excess monomers are removed.

The polymerization temperature is preferably from 120 to 200 ° C.,
In this temperature range, the polymerization reaction is preferably performed at a low temperature when the ratio of the cyclic amide is low, and at a high temperature when the ratio of the cyclic amide is high.

Examples of polybasic acid chlorides to be added include dibasic acids such as oxalic acid, succinic acid, adipic acid, phthalic acid, maleic acid and fumaric acid; tribasic acids such as citric acid and trimellitic acid; Chloride such as tetrabasic acid such as acid is exemplified. Chloride is convenient because it has good reactivity and can also serve as neutralization of the alkali remaining in the copolymer. In addition, when terephthaloyl chloride is used, a decolorization reaction of the resulting copolymer occurs at the same time.

The addition of the polybasic acid chloride is carried out after removing the excess monomer after the copolymerization reaction is completed, but the copolymer once cooled and solidified and processed into pellets or the like is melted again. It may be added later.

The addition of the polybasic acid chloride to the reaction system may be carried out directly. However, when the addition amount is very small, the volatile acid which does not affect the reaction system is used in order to prevent the reaction from proceeding unevenly. May be added as a solvent solution. Not only in this case, but after the addition of the polybasic acid chloride, the pressure is reduced again to remove volatile reaction products. As the removal of volatile reaction products proceeds, the viscosity of the molten copolymer gradually increases.

If the amount of the polybasic acid chloride is too small, there is no effect. If the amount is too large, gelation is caused, and the produced copolymer may be deteriorated due to residual acid. The range of the addition amount is preferably 0.5 to 4.0 mol% based on the total amount of the monomers. Among them, the addition of an equimolar equivalent of the initiator used is also optimal because it neutralizes the alkali. That is, when the initiator is, for example, a monovalent alkali, it is preferable to add モ ル mole amount of the initiator used in the case of dibasic acid chloride and １ ／ mole amount of the initiator used in the case of tribasic acid chloride. Most preferred.

Since the addition of the polybasic acid chloride must be performed when the copolymer is in a molten state, the addition temperature must be higher than the melting point of the copolymer. Further, in order to efficiently remove reaction products such as water, the reaction is preferably performed at a high temperature to such an extent that the copolymer does not decompose. Specifically, 100-
200 ° C. is preferred, most preferably 160-190 ° C.
It is. The reduced pressure step after the addition of the polybasic acid chloride is also performed at this temperature.

According to the above production method, an ester-amide copolymer having a high amide ratio and a high molecular weight can be obtained. That is, after the polymerization reaction between the cyclic ester and the cyclic amide is completed, a polybasic acid chloride is added to the copolymer in a molten state to cause a crosslinking reaction between the copolymer molecules, whereby a high-molecular-weight ester-amide copolymer is obtained. Obtain a polymer.

The ester-amide copolymer of the present invention has high physical properties and biodegradability. Therefore, it is useful as a material for materials such as films, foams, fibers, and non-woven fabrics, and further, with these materials, cushioning materials, packaging materials, containers, shopping bags, agricultural and forestry materials, fishing materials, outdoor goods, and sanitary goods. , Medical supplies and coating materials.

[0026]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1 17 g of CLM (manufactured by Mitsubishi Chemical) was placed in a well-dried polymerization vessel (separable flask), heated and melted at 130 ° C. in a dry N ₂ stream, and stirred as it was for 90 minutes.

While stirring, 138 mg of Na (manufactured by Wako Pure Chemical Industries, cut out from the rod-shaped reagent immediately before use and weighed in dry toluene) is added and reacted with CLM. 1 after addition
The temperature was raised to 70 ° C., and the mixture was stirred for 30 minutes.

16 ml of CLN (Placcel-M, manufactured by Daicel Chemical Co., Ltd.) was placed in a sufficiently dried syringe and charged into a polymerization vessel. The polymerization proceeds rapidly, and the viscosity becomes 10
It reached the highest in about a minute. At this time, the copolymer had turned yellow-brown.

After reacting for 1 hour from the introduction of CLN, the pressure in the reaction vessel was reduced by an oil rotary vacuum pump, and stirring was continued for 1 hour under reduced pressure to remove excess monomers together with water.

After the inside of the container is returned to normal pressure with N ₂ gas, 46
10 ml of 5 mg of succinic chloride (manufactured by Wako Pure Chemical Industries)
Was added to the reaction system and stirred.
Immediately under reduced pressure, stirring was continued, and the reaction was carried out for 60 minutes while removing volatile components such as toluene. After the inside of the container was returned to normal pressure again with N ₂ gas, the copolymer was taken out.

In the above polymerization reaction, metallic sodium was used in an amount of 2 mol% of the total amount of the monomers. Further, succinic acid chloride as a chloride of polybasic acid is equimolar equivalent to the amount of metal sodium used, that is, succinic acid is divalent. The role of the sum also served.

The obtained copolymer was measured under the following apparatus and conditions.

Composition of copolymer: FT-IR (manufactured by Nicolet) Molecular weight measurement: apparatus GPC system HLC-8020
(Tosoh) Eluent Hexafluoroisocyanate (HFIP) in which 10 mM sodium trifluoroacetate is dissolved Flow rate 0.5 m / min Column GMHHR-M (Tosoh) Column temperature 40 ° C Standard sample Shodex GPC Standard PMMA (Showa Denko) Thermal characteristics: device DSC-200 (manufactured by Seiko Denshi Kogyo) Heating rate 10 ° C./min Measured in a nitrogen stream. The endothermic peak at the time of temperature rise is used as an index of the melting point. Tensile test: Apparatus UCT-10T (manufactured by Orientec) Measurement room temperature 23 ° C Humidity 61% Humidity 10mm / min Test piece JIS No. 3 piece As a result of polymerization, 91% yield and 45% amide composition, yellow A brown emulsion and elastic ester-amide copolymer was obtained. The obtained copolymer had a number average molecular weight of 3100, a weight average molecular weight of 6900, and a DSC
According to (differential scanning calorimetry), a broad endothermic peak was observed around 76 ° C. In the tensile test, the strength 1
It showed 4.4 MPa and an elastic modulus of 185 MPa.

Example 2 A polymerization reaction was carried out using the same raw materials as in Example 1 except that terephthaloyl chloride (manufactured by Wako Pure Chemical Industries, Ltd.) was used instead of succinic chloride of Example 1.

First, a polymerization reaction between CLM and CLN was carried out in the same manner as in Example 1.

Next, after the inside of the polymerization vessel was returned to normal pressure with N ₂ gas, a solution obtained by dissolving 609 mg of terephthaloyl chloride in 10 ml of toluene was added to the reaction system and stirred. Immediately under reduced pressure, stirring was continued, and the reaction was carried out for 60 minutes while removing volatile components such as toluene. After the inside of the container was returned to normal pressure again with N ₂ gas, the copolymer was taken out and its physical properties were measured in the same manner as in Example 1.

As a result of the above polymerization, a pale yellow emulsion and elastic ester-amide copolymer having a composition of 45% amide with a yield of 93% was obtained. The obtained copolymer had a number average molecular weight of 3,600 and a weight average molecular weight of 730.
0, and showed a broad endothermic peak around 76 ° C according to DSC. In the tensile test, the strength 22.
It showed 1 MPa and an elastic modulus of 195 MPa.

Compared with the succinic chloride of Example 1, when terephthaloyl chloride was used as the polybasic acid chloride,
The color of the obtained copolymer became pale and the reaction took place rapidly. Although the molecular weight was slightly higher when terephthaloyl chloride was used, an aesthetically pleasing one was obtained.

Comparative Example A copolymer was obtained in the same manner as in Example 1 except that no polybasic acid chloride was added.

The obtained copolymer was a light yellow transparent soft copolymer having a yield of 91% and an amide composition of 45%.

The copolymer has a number average molecular weight of 2
400, the weight average molecular weight was 4,500, and DSC showed a broad endothermic peak near 76 ° C. Further, in the tensile test, the strength was 12.9 MPa and the elastic modulus was 1
73 MPa.

From the results, it was found that the copolymer was clearly lower in molecular weight and considerably softer than when polybasic acid chloride was added. Further, this copolymer was different from the copolymers of Examples 1 and 2, which became milky when solidified, and remained transparent even after solidification.

Further, the strength was inferior to those of Examples 1 and 2, and the viscosity at the time of melting was so low that it was not suitable for processing.

[0045]

As described above, the method for producing the ester-amide copolymer of the present invention comprises the steps of subjecting a cyclic ester and a cyclic amide to ring-opening copolymerization and then adding a polybasic acid to the resulting molten copolymer. It is characterized by adding chloride.

Therefore, a polymer having a high molecular weight and a high amide ratio can be obtained, and as a result, an ester-amide copolymer having excellent physical properties such as melting point and strength can be obtained.

Claims (3)

(57) [Claims] 1. An ester for ring-opening copolymerizing at least one cyclic ester and at least one cyclic amide.
In the method for producing an amide copolymer, the above-mentioned cyclic ester and cyclic amide are subjected to ring-opening copolymerization, and then a polybasic acid chloride is added to the obtained copolymer in a molten state. A method for producing an amide copolymer. 2. The method for producing an ester-amide copolymer according to claim 1, wherein said cyclic amide is ε-caprolactam. 3. The method for producing an ester-amide copolymer according to claim 1, wherein said cyclic ester is ε-caprolactone.