JPH10139868A - Polymerization of lactone - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for polymerizing a lactone by which a polylactone resin, low in acid value and having hydrolytic resistance without problems in hue and malodor is produced. SOLUTION: This method for polymerizing a lactone comprises polymerizing the lactone in the presence of an initiator, a catalyst and a carbodiimide having >=95% purity of an active ingredient. The carbodiimide is preferably represented by the general formula R-(-N=C=N-)n R' [R and R' are each a 1-24C hydrocarbon group and may be same or different and R and R' together may form a ring; (n) is an optical integer of >=1] and especially preferably N,N'-bis(3,5- diisopropylphenyl)carbodiimide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for polymerizing lactone. According to the method of the present invention, a high-quality lactone polymer having a reduced acid value, a low acid value and an excellent hydrolysis resistance, which has a short polymerization time, has no odor, has no gel, and has an improved hue. Polylactone resins are highly likely to be left in the environment and are required to be biodegradable, such as adhesives, adhesives, cured molded materials, polymer plasticizers, polyamide resin modifiers, compatibilizers, paints, It can be widely used for alkaline water dispersible binders, inks and medical applications. In particular, since the poly-ε-caprolactone resin has high crystallinity, it has a relatively high hardness at room temperature, and has a characteristic that the crystal melting point is relatively low (50 to 60 ° C.). Used for plastic clay, etc.
In addition, it is possible to shape each part of the human body such as a medical cast, splint agent, radiation irradiation face mask, or wig molding material, and to use it as an optimal material for applications that fit the human body, other than the above Widely used for applications.

[0002]

BACKGROUND OF THE INVENTION Generally, a polylactone resin is obtained by subjecting a lactone to a ring-opening polymerization by heating and stirring at 120 to 220 ° C. in the presence of an initiator having an active hydrogen and a catalyst. Can be Or ω−
A polylactone resin can also be obtained by dehydrating and condensing oxycarboxylic acid at 120 to 220 ° C. in the presence of a catalyst.
In particular, in order to obtain a polylactone resin having a number average molecular weight of 10,000 to 200,000 and a molecular weight distribution (weight average molecular weight / number average molecular weight) of 2 or less, a small amount of glycol is used as an initiator and a catalyst is used. 12 in the presence of
A method of ring-opening polymerization at 0 to 220 ° C is suitable. This is because the dehydration-condensation method of ω-oxycarboxylic acid cannot practically obtain a polylactone resin having a high molecular weight and a narrow molecular weight distribution as described above. When water in a monomer is used as an initiator, a carboxyl group (—COOH) is generated at a terminal, which has a disadvantage that hydrolysis resistance is inferior as described later, and a carboxylic acid is contained in a polymerization system. If present, inhibits the ring opening polymerization of the lactone monomer,
The polymerization rate is significantly reduced. Further, the polylactone resin produced by the above method has a strong odor, and has a serious problem in quality such as coloring and formation of a gel.

On the other hand, a problem common to linear polyesters is that they have poor hydrolysis resistance. Also,
When it is desired to obtain a high molecular weight product having a number average molecular weight of 10,000 to 200,000, it is particularly desirable to reduce the water content in the system, but it is impossible to completely remove the water and it is impossible to completely remove the water from the water. -CO is added to the molecular end of the initiated lactone polymer.
It is unavoidable that a polymer in which OH remains is by-produced.
The remaining -COOH further promotes the common hydrolyzability of the polyester, and causes the degree of polymerization to decrease with time. For this reason, in applications such as biodegradable applications, medical casts, splint materials, and molding materials, the degree of polymerization may be reduced during storage in the form of a plate-like or rod-like material, and the material may be deteriorated so that it cannot be used. .

As a countermeasure against these deteriorations, various methods have conventionally been taken to prevent hydrolysis of the polyester resin, such as addition of an epoxy compound as an acid catcher and addition of a phosphorus compound as a heat stabilizer. However, these compounds do not have a sufficient hydrolysis-preventing effect on polylactone resins and have little effect on the above-mentioned applications. When hydrolysis of the polyester occurs in this way, for example,
When performing the molding of a wig using the plate-like material as described above, the plate-like material is heated and softened, and even if it is pressed against the head, sagging occurs and it can be moved for a short distance. I couldn't do it, and even if I managed to push it to my head, I got drowned and couldn't work at all. In addition, when used as a medical splint, a sheet about 3 mm thick is immersed in warm water at 60 to 70 ° C to melt the crystals, and then cooled to the temperature of human skin in the air and then applied to the affected area of the human body. The work is done by winding, but when using a sheet with a low degree of polymerization, the melted sheet has insufficient melt elasticity, causing the sheet to hang down, making it difficult to wrap it around the affected part. In addition, the strength of the cured sheet is also reduced, so that cracks may occur during use. Further, in the case of a sheet having a lowered degree of polymerization, the appearance becomes poor due to uneven thickness and the like. Conventionally, troubles have been avoided by strictly controlling the inventory so that the product is used before such deterioration due to hydrolysis occurs. However, this is not an essential solution,
In particular, in the case of exports that require transportation days, there is no inventory permissible days, and strict inventory management becomes impossible.

[0005] It has also been proposed to add carbodiimide as an acid sorbent to prevent hydrolysis of the polylactone resin (JP-A-50-160362 and JP-A-59-160362).
-129253, JP-A-61-241354).

However, when carbodiimide of low purity is used, problems such as coloring and odor occur, and even if carbodiimide is added to the resin to improve the hydrolysis resistance, it cannot be used in many applications.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, the polymerization reaction of lactone is carried out in the co-presence of purified high-purity carbodiimide, whereby the inorganic acid in the system is obtained. By rapidly detoxifying the carboxyl group generated at the terminal of the lactone monomer ring-opened from water and organic acids and trace amounts of water, the polymerization reaction rate is greatly increased, and the mechanical properties of the resulting polylactone resin are improved. It has been found that the hydrolysis resistance is greatly improved without any loss, and that there is no gel and the problems of coloring and odor are eliminated, and the present invention has been completed.

That is, the present invention provides a method for polymerizing a lactone, which comprises polymerizing a lactone in the presence of a carbodiimide having a purity of 95% or more of an initiator, a catalyst and an active ingredient. In addition, the present invention relates to a compound represented by the general formula: R-(-N = C = N-) n-R '(R,
R ′ is a hydrocarbon group having 1 to 24 carbon atoms, R ′ may be the same as or different from R, and R and R ′ may form a ring together. n is an arbitrary integer of 1 or more. The present invention also provides a method for polymerizing the lactone, characterized by being a compound represented by the formula: The present invention also provides a method for polymerizing the lactone, wherein the carbodiimide is N, N'-bis (2,6-diisopropylphenyl) carbodiimide. In the present invention, the carbodiimide is added to the lactone in an amount of 100 parts by weight.
The present invention provides a method for polymerizing the lactone, wherein the method uses 0.5 to 2 parts by weight. The present invention also provides a method for polymerizing the lactone, wherein the lactone is ε-caprolactone. The present invention also provides a method for polymerizing the lactone, wherein the catalyst is a tin compound and / or a titanium compound. The present invention also provides a method for polymerizing the lactone, wherein the catalyst is a monobutyltin compound and / or a dibutyltin compound. Further, the present invention provides a method for polymerizing the lactone, wherein the catalyst is monobutyltin oxide and / or monobutyltin tris (2-ethylhexanoate). Hereinafter, the present invention will be described in detail.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The lactone used in the present invention includes methylated caprolactone such as ε-caprolactone and 4-methylcaprolactone, β-propiolactone, γ
-Butyrolactone, δ-valerolactone, enantholactone, and a mixture of two or more thereof. Among them, ε-caprolactone, which is most useful industrially, is preferably used. The lactone used in the present invention includes a polylactone-forming derivative such as oxycarboxylic acid. Specific examples include γ-oxybutyric acid and ω-oxycaproic acid.

The initiator used in the present invention may be any compound having an active hydrogen other than water. Preferred initiators include alcohols and glycols for producing a high molecular weight polylactone resin. In such cases, glycols are particularly preferred. For example, ethylene glycol, propylene glycol, 1,4-butanediol, 1,3-butylene glycol, diethylene glycol, neopentyl glycol, 1,6-hexanediol, 1,4-cyclohexanedimethanol and the like can be mentioned. The type and amount of the initiator are determined depending on the use of the polylactone resin to be produced.

As the catalyst of the present invention, a general ring-opening addition polymerization catalyst is used. Specifically, an inorganic base, an inorganic acid,
Examples thereof include an organic alkali metal catalyst, a tin compound, a titanium compound, an aluminum compound, a zinc compound, a molybdenum compound, and a zirconium compound. Among them, tin compounds and titanium compounds are preferably used in terms of balance between ease of handling, low toxicity, reactivity, non-coloring property, and stability. Preferably, the tin compound is specifically a stannous octylate, a monobutyltin compound such as monobutyltin oxide, monobutyltin tris (2-ethylhexanoate), dibutyltin oxide, diisobutyltin oxide, dibutyltin diacetate Specific examples of the dibutyltin compound such as di-n-butyltin dilaurate or the titanium compound include tetramethyl titanate, tetraethyl titanate, tetra n-propyl titanate, tetra-isopropyl titanate, and tetrabutyl titanate. These can be used alone or in combination. Among them, monobutyltin compounds such as monobutyltin oxide and monobutyltin tris (2-ethylhexanoate) are preferably used because mixing with high-purity carbodiimide significantly promotes the ring-opening polymerization reaction of the lactone monomer.

In the presence of carbodiimide, the reaction rate is significantly increased, so that the amount of the catalyst may be smaller than usual, and the amount of the catalyst may be 0.0001 to 100 parts by weight of the starting material used.
0.1 parts by weight, preferably 0.0002 to 0.05 parts by weight, more preferably 0.0005 to 0.02 parts by weight. When the amount of the catalyst is less than 0.0001 part by weight, the polymerization rate of the lactone monomer is low, and when it is more than 0.1 part by weight, the obtained lactone polymer may be colored, It is not preferable because thermal stability may be reduced. In the present invention, it is expected that the amount of catalyst remaining in the obtained polylactone resin is smaller than usual, the decomposition during storage is reduced accordingly, and the long-term storage stability is improved because the amount of catalyst is small as described above. Is done.

The carbodiimide used in the present invention can be produced by a known method by decarboxylation by heating an organic isocyanate in the presence of a suitable catalyst. Preferred organic isocyanates are cyclohexyl isocyanate, 2,6-diisopropylcyclohexyl isocyanate, Enyl isocyanate, tolyl isocyanate, 3,5-diisopropylphenyl isocyanate, phenylene diisocyanate, tolylene-2,4-diisocyanate, tolylene-2,6-diisocyanate, 4,4′-methylenebis (phenylisocyanate), diprolphenyl Diisocyanate, 1,3-diisopropylphenylene-
2,4-diisocyanate, 2,4,5-triisopropylphenylene-1,3-diisocyanate, 1,6-diisocyanate
Hexamethylene diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate) and the like can be mentioned. As the carbodiimide, a compound represented by the general formula R-(-N = C =
N-) nR '(R and R' are a hydrocarbon group having 1 to 24 carbon atoms, and R 'may be the same as or different from R.
And R ′ may form a ring together. n is an arbitrary integer of 1 or more. Are preferable, and specific examples thereof include N, N′-dicyclohexylcarbodiimide, N, N′-bis (2,6-diisopropylcyclohexyl) carbodiimide, and N, N′-bis (3,5-
Diisopropylphenyl) carbodiimide and the like. Among them, N, N′-dicyclohexylcarbodiimide and N, N′-bis (2,6-diisopropylphenyl) carbodiimide are suitable for the polymerization of ε-caprolactone.

[0014] The purity of the active ingredient of the carbodiimide used is preferably 95% or more. Active ingredient purity 9
At 5% or less, the resulting polylactone resin may be colored,
Odor problems occur, which is undesirable. The amount of the carbodiimide used may be smaller than that in the case of adding to the polylactone resin, and is 0.05 to 2 parts by weight per 100 parts by weight of the lactone.
Parts by weight, preferably 0.05 to 1 part by weight. If the amount of carbodiimide used is too small, the effect of preventing hydrolysis is poor due to insufficient blocking of the -COOH group. Conversely, if the amount is too large, the effect does not change and the problem of coloring recurs.

The polymerization temperature is 50 to 250 ° C., preferably 100 to 220 ° C., more preferably 15 to 250 ° C.
The range is from 0 to 200 ° C. If below 50 ° C,
If the polymerization rate of the lactone monomer is low and the temperature exceeds 250 ° C., it is not preferable because the lactone polymer undergoes a thermal decomposition reaction, causing coloring and decomposed products. In the present invention, since the polymerization reaction is carried out in the coexistence of the catalyst and the carbodiimide as described above, the reaction is accelerated, so that the reaction can be carried out at a low reaction temperature. Therefore, since generation of decomposed products is suppressed, it is expected that the long-term storage stability of the obtained polylactone resin is also improved.

The number average molecular weight of the polylactone resin obtained by the polymerization method of the present invention is usually from 300 to 200,000.
It is in the range of 0. The number average molecular weight can be measured by using a known number average molecular weight measurement method, and particularly, gel permeation chromatography (GP)
The method using C) is the simplest and is preferably used.

Hereinafter, the lactone polymerization method of the present invention will be described in more detail. As the reactor in the lactone polymerization method of the present invention described above, a known reactor can be used without any problem. Specifically, a stirring blade type batch type reactor,
Examples include a semi-continuous and continuous reactor, a kneader-type mixer, a screw-type mixer such as an extruder, a static mixer-type reactor, and a reactor in which these are continuously connected.

In the polymerization method of the present invention, the amount of water contained in the raw material is 0.5% by weight or less, preferably 0.1% by weight or less.
%, More preferably 0.05% by weight or less. If the amount of water contained in the raw material exceeds 0.5% by weight, addition polymerization of the lactone monomer from water occurs, carbodiimide is consumed, and the effect of improving the hydrolysis resistance is lost, which is not preferable. . Further, in the polymerization method of the present invention, it is possible to mix any additives such as a diluting solvent and a stabilizer without any trouble.

[0019]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples.

Example 1 A 20 liter polymerization machine equipped with a stirrer, a thermometer, a nitrogen inlet tube, and a condenser was prepared.
10 kg of ε-caprolactone (0.01% moisture), 10 g of diethylene glycol as an initiator, 0.1 g of monobutyltin oxide as a catalyst and bis (2,6-diisopropylphenyl) carbodiimide (manufactured by Raschig,
Stabilizer 7000, purity 100%) (20 g) was charged, and the mixture was stirred at a temperature of 160 ° C while blowing nitrogen gas. After 6 hours, it was confirmed that the amount of ε-caprolactone monomer remaining in the system had reached 0.2 mol%, sampling was performed, and the sampled resin was subjected to GPC measurement to obtain a number average molecular weight in terms of standard polystyrene and a molecular weight distribution value ( Mw
/ Mn), acid value, MI (melt flow index),
The hue (APHA value of 30% solid content xylene solution JIS K1557) is summarized in Table 1. A nitrogen pressure of about 2 atm was applied to the polymerization machine, the polylactone resin was drawn into a strand, cooled in a water bath, and pelletized. The pellet was dried in a 40 ° C. oven for 5 hours. Using the above pellets, a film having a thickness of 100 μm was formed. The resin (200 ° C.) melted by Labo Plastomill 30C150, manufactured by Toyo Seiki Co., Ltd., is sent to a T-die molding machine, and has a width of 15 cm.
A film having a thickness of 100 μm was wound up at a tensile speed of 10 m / min. The odor of the obtained film was evaluated in four steps, the number of fish eyes in the film and the GPC measurement of the film, and the acid value (dissolved in acetone so as to have a solid content of 5% by weight and dissolved in a 0.1 N NaOH standard solution) Measurement by titration), MI (JIS K7210) and hue were measured, and the hydrolysis resistance was evaluated by comparing with the data before molding.

Example 2 Using the same polymerization machine and the same charging composition as in Example 1, a charging operation was performed in which the addition timing of bis (2,6-diisopropylphenyl) carbodiimide was changed. In a polymerization machine, 10 kg of ε-caprolactone (water content: 0.01%), 10 g of diethylene glycol as an initiator, and 0.1 g of monobutyltin oxide as a catalyst were used.
g and heated to 160 ° C. while stirring. Five minutes after the temperature rise, bis (2,6-diisopropylphenyl) carbodiimide (manufactured by Raschig, Stabilizer 700)
(0, purity 100%) and stirred at a temperature of 160 ° C. while blowing nitrogen gas. Four hours after the temperature was raised immediately at 160 ° C., it was confirmed that the amount of the remaining ε-caprolactone monomer was 0.2 mol%. After that, it carried out similarly to Example 1. The results are shown in Table 1.

Comparative Example 1 Using the same polymerization machine as in Example 1, polymerization was carried out under the same charge composition and reaction conditions except that bis (2,6-diisopropylphenyl) carbodiimide was not added. In this system, the polymerization rate is slow,
Only 20 hours after the temperature was raised immediately at 160 ° C., the residual monomer amount reached 0.7%. The results are shown in Table 1.

COMPARATIVE EXAMPLE 2 Bis (2,6-diisopropylphenyl) carbodiimide (manufactured by Bayer AG, Stabacol, purity: 91) was used in the same polymerization machine as in Example 1.
%), Polymerization was carried out under the same charge composition and reaction conditions as in Example 1. Polymerization was started immediately after the temperature was raised to 160 ° C.
After a short time, the amount of residual monomer reached 0.4%. Table-Results
It is shown in FIG.

(Comparative Example 3) 0.2 parts by weight of bis (2,6-diisopropylphenyl) carbodiimide (stabilizer 7000, purity 100%) was blended with 100 parts by weight of the pellet obtained in Comparative Example 1. Film forming was performed under the same conditions as in Example 1. The results are shown in Table 1.

The overall evaluation of the polylactone resins obtained in the examples and comparative examples was evaluated as usable: .DELTA., Slightly inferior but usable, .DELTA.

[0026]

[Table 1]

[0027]

As described in detail above, according to the present invention, the reaction rate is increased, the amount of catalyst can be reduced, and the amount of carbodiimide used as a hydrolysis inhibitor can be reduced. Advantageously, the resulting polylactone resin has no problems in terms of hue and odor, has a low acid value, has excellent hydrolysis resistance, can be expected to have long-term storage stability, and can be used for biodegradable and medical adhesives. , Adhesives, cured molded materials, polymer plasticizers, polyamide resin modifiers, compatibilizers, paints, dispersibility in alkaline water, binders, inks, etc.

Claims (8)

[Claims] 1. A method for polymerizing a lactone, which comprises polymerizing a lactone in the presence of a carbodiimide having a purity of at least 95% of an initiator, a catalyst and an active ingredient. 2. The carbodiimide represented by the general formula R-(-N
= C = N-) n-R '(R and R' are hydrocarbon groups having 1 to 24 carbon atoms, and R 'may be the same or different from R;
R and R 'may form a ring together. n is an arbitrary integer of 1 or more. 2. The method for polymerizing a lactone according to claim 1, which is a compound represented by the formula: 3. The method according to claim 1, wherein the carbodiimide is N, N′-bis (2,6-diisopropylphenyl) carbodiimide. 4. The method for polymerizing a lactone according to claim 1, wherein 0.05 to 5 parts by weight of the carbodiimide is used based on 100 parts by weight of the lactone. 5. The method according to claim 1, wherein the lactone is ε-caprolactone. 6. The method for polymerizing lactone according to claim 1, wherein the catalyst is a tin compound and / or a titanium compound. 7. The catalyst according to claim 1, wherein the catalyst is a monobutyltin compound and / or
6. The method of claim 1, wherein the lactone is a dibutyltin compound. 8. The method according to claim 1, wherein the catalyst is monobutyltin oxide and / or monobutyltin tris (2-ethylhexanoate).