JP3556785B2 - Lactone polymerization method - Google Patents

Description

【００２７】
【発明の効果】
以上詳しく説明したように、本発明によれば反応速度が速くなるため、触媒を減量でき、耐加水分解防止剤のカルボジイミドの使用量も少なくて済むため原料原単位の点で有利であり、得られるポリラクトン樹脂は色相、臭気の点で問題がなく、酸価が低く、耐加水分解性に優れ、長期保存安定性も期待でき、生分解性用途、医療用途粘着剤をはじめ、接着剤、硬化成形体材料、ポリマー可塑剤、ポリアミド樹脂改質剤、相溶化剤、塗料、アルカリ水分散性、バインダー、インキ等広範囲に利用できる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for polymerizing a lactone. According to the method of the present invention, a high-quality lactone polymer having a reduced acid value, a low acid value, and a 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, 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.). It is used for plastic clay, etc., and it is used for shaping various parts of the human body such as medical casts, splinting agents, radiation irradiation face masks, or wig molding materials to fit the human body Is widely used as an optimal material in applications other than the above.
[0002]
[Prior Art and Problems to be Solved by 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. Alternatively, a polylactone resin can be obtained by dehydrating and condensing ω-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. The method of performing ring-opening polymerization at 120 to 220 ° C. in the presence of is suitable. This is because, in the dehydration-condensation method of ω-oxycarboxylic acid, a polylactone resin having a high molecular weight and a narrow molecular weight distribution as described above cannot be practically obtained. 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. When present, it inhibits the ring opening polymerization of the lactone monomer and significantly reduces the polymerization rate. In addition, 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.
[0003]
On the other hand, a problem common to linear polyesters is that they have poor hydrolysis resistance.
In addition, 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. It is inevitable that a polymer in which -COOH remains at the molecular terminal of the lactone polymer starting from water 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. .
[0004]
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 the hydrolysis of the polyester occurs in this manner, for example, when the wig is molded using the above-described plate-like material, the plate-like material is heated and softened, and pressed against the head. Even so, there was a problem that sagging occurred and it was not possible to move for a short distance, and even if you pressed it against the head somehow, you could not work at all because it drooped. Also, when used as a medical splint, a sheet about 3 mm thick is immersed in warm water at 60-70 ° 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 reduced 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 in which the degree of polymerization has been reduced, the appearance becomes poor due to uneven thickness. 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 to the problem, and in particular, in the case of exports that require days for transportation, the number of days allowed for inventory is lost, and strict inventory management becomes impossible.
[0005]
It has also been proposed to add carbodiimide as an acid carboxylate to prevent hydrolysis of the polylactone resin (JP-A-50-160362, JP-A-59-129253, JP-A-61-241354).
[0006]
However, when a 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 problems, and as a result, by performing the polymerization reaction of lactone in the presence of purified high-purity carbodiimide, the inorganic acid or organic acid in the system and water present in trace amounts are present. By rapidly detoxifying the carboxyl groups generated at the ring-opened lactone monomer terminals, the polymerization reaction rate is greatly increased, and the hydrolysis resistance is maintained without impairing the mechanical properties of the resulting polylactone resin. The present invention was found to be greatly improved, and it was found that there was no gel substance and the problems of coloring and odor were solved, and the present invention was completed.
[0008]
That is, the present invention provides a method for polymerizing a lactone, which comprises polymerizing a lactone in the presence of an initiator, a catalyst and a carbodiimide having a purity of 95% or more of an active ingredient. Further, in the present invention, the carbodiimide has a general formula: R-(-N = C = N-) n-R '(R and R' are hydrocarbon groups having 1 to 24 carbon atoms, and R 'is the same as R. And R and R ′ may form a ring together. N is an integer of 1 or more.) To provide. The present invention also provides a method for polymerizing the lactone, wherein the carbodiimide is N, N'-bis (2,6-diisopropylphenyl) carbodiimide. The present invention also provides a method for polymerizing the lactone, wherein the carbodiimide is used in an amount of 0.05 to 2 parts by weight based on 100 parts by weight of the lactone. 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. Furthermore, 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]
BEST MODE FOR CARRYING OUT THE INVENTION
Examples of the lactone used in the present invention include methylated caprolactone such as ε-caprolactone and 4-methylcaprolactone, β-propiolactone, γ-butyrolactone, δ-valerolactone, enantholactone, and a mixture of two or more of these. 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.
[0010]
The initiator used in the present invention may be any compound having an active hydrogen other than water.Suitable initiators include alcohols and glycols, and when producing a high molecular weight polylactone resin, And glycol 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.
[0011]
As the catalyst of the present invention, a general ring-opening addition polymerization catalyst is used. Specific examples include inorganic bases, inorganic acids, organic alkali metal catalysts, tin compounds, titanium compounds, aluminum compounds, zinc compounds, molybdenum compounds, zirconium compounds, and the like. 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.
[0012]
In the presence of carbodiimide, the reaction rate is significantly increased, so the amount of the catalyst may be lower than usual. The amount of the catalyst is 0.0001 to 0.1 part by weight, preferably 0.0002 to 0.1 part by weight, per 100 parts by weight of the raw material used. 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 is colored or It is not preferable because thermal stability may be reduced. In the present invention, it is expected that the amount of the catalyst in the obtained polylactone resin is smaller than usual because the amount of the catalyst is small as described above, the decomposition during storage is also reduced, and the long-term storage stability is also improved. Is done.
[0013]
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 in the presence of a suitable catalyst. Preferred organic isocyanates include cyclohexyl isocyanate, 2,6-diisopropylcyclohexyl isocyanate, phenyl isocyanate Tolyl isocyanate, 3,5-diisopropylphenyl isocyanate, phenylene diisocyanate, tolylene-2,4-diisocyanate, tolylene-2,6-diisocyanate, 4,4′-methylenebis (phenyl isocyanate), diprolephenylene diisocyanate, 1,3-diisopropylphenylene-2,4-diisocyanate, 2,4,5-triisopropylphenylene-1,3-diisocyanate, 1,6-hexamethylene diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate) and the like. The carbodiimide has a 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 as or different from R. R and R 'may form a ring together. N is any integer of 1 or more.), And specific examples include N, N'-dicyclohexylcarbodiimide, N , N'-bis (2,6-diisopropylcyclohexyl) carbodiimide, 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]
It is preferable that the purity of the active ingredient of the carbodiimide used is 95% or more. If the purity of the active ingredient is 95% or less, the resulting polylactone resin is undesirably colored or has a problem of odor. The amount of the carbodiimide used may be smaller than when it is added to the polylactone resin, and is 0.05 to 2 parts by weight, preferably 0.05 to 1 part by weight, per 100 parts by weight of the lactone. If the amount of carbodiimide used is too small, the blocking effect of the -COOH group is not sufficient, so that the effect of preventing hydrolysis is poor. Conversely, if the amount is too large, the effect does not change, and the problem of coloring recurs.
[0015]
The polymerization temperature is from 50 to 250 ° C, preferably from 100 to 220 ° C, and more preferably from 150 to 200 ° C. When the temperature is lower than 50 ° C., the polymerization rate of the lactone monomer is low. On the other hand, when the temperature is higher than 250 ° C., a thermal decomposition reaction of the lactone polymer occurs, and the lactone polymer is preferably colored or decomposed. Absent.
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 temperature. Therefore, since the generation of decomposition products is suppressed, it is expected that the long-term storage stability of the obtained polylactone resin is also improved.
[0016]
The number average molecular weight of the polylactone resin obtained by the polymerization method of the present invention is usually in the range of 300 to 200,000.
The number average molecular weight can be measured by using a known method for measuring the number average molecular weight. In particular, a method using gel permeation chromatography (GPC) is most simply and preferably used.
[0017]
Hereinafter, the lactone polymerization method of the present invention will be described in more detail.
As the reaction device in the lactone polymerization method of the present invention described above, a known reaction device can be used without any problem.
Specifically, a stirring blade type batch type reactor, a semi-continuous and continuous type reactor, a kneader type kneader, a screw type kneader such as an extruder, a static mixer type reactor and a reactor in which these are continuously connected. And the like.
[0018]
In the polymerization method of the present invention, the amount of water contained in the raw material is preferably 0.5% by weight or less, preferably 0.1% by weight or less, and 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]
【Example】
Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto.
[0020]
(Example 1)
In a 20-liter polymerization machine equipped with a stirrer, thermometer, nitrogen inlet tube and condenser, 10 kg of ε-caprolactone (0.01% water), 10 g of diethylene glycol as an initiator, 0.1 g of monobutyltin oxide as a catalyst and bis ( 20 g of 2,6-diisopropylphenyl) carbodiimide (manufactured by Raschig, Stabilizer 7000, purity 100%) 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%, and the sample was sampled, 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), and hue (APHA value of JIS K1557 of 30% solid content xylene solution) are summarized in Table 1.
A nitrogen pressure was applied to the polymerization machine at about 2 atm, 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., was sent to a T-die molding machine to form a film having a width of 15 cm and a thickness of 100 μm, and was wound at a pulling 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 0.1N-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.
[0021]
(Example 2)
In the same polymerization machine and the same charge composition as in Example 1, a charge operation of changing the addition time of bis (2,6-diisopropylphenyl) carbodiimide was performed.
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 charged into a polymerization machine, and the temperature was raised while stirring at 160 ° C. Five minutes after the temperature rise, 20 g of bis (2,6-diisopropylphenyl) carbodiimide (manufactured by Raschig, Stabilizer 7000, purity: 100%) was charged, and the mixture was stirred at a temperature of 160 ° C. while blowing nitrogen gas. After 4 hours from immediately after the temperature was raised to 160 ° C., it was confirmed that the amount of the remaining and remaining ε-caprolactone monomer was 0.2 mol%. Thereafter, the same procedure as in Example 1 was performed. The results are shown in Table 1.
[0022]
(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 was slow, and the amount of residual monomer reached 0.7% only 20 hours after the temperature was raised immediately at 160 ° C. The results are shown in Table 1.
[0023]
(Comparative Example 2)
Using the same polymerization machine as in Example 1, but adding bis (2,6-diisopropylphenyl) carbodiimide (manufactured by Bayer, Stabacol, purity 91%), using the same charge composition and reaction conditions as in Example 1. The polymerization was carried out. In the polymerization, the amount of the residual monomer reached 0.4% after 7 minutes from immediately after the temperature was raised to 160 ° C. The results are shown in Table 1.
[0024]
(Comparative Example 3)
To 100 parts by weight of the pellet obtained in Comparative Example 1, 0.2 part by weight of bis (2,6-diisopropylphenyl) carbodiimide (Stabilizer 7000, purity 100%) was blended, and the same conditions as in Example 1 were used. Was used to form a film. The results are shown in Table 1.
[0025]
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]
【The invention's effect】
As described above in detail, according to the present invention, the reaction rate is increased, the catalyst can be reduced, and the amount of carbodiimide used as the hydrolysis inhibitor can be reduced. The polylactone resin has no problems in terms of hue and odor, has a low acid value, has excellent hydrolysis resistance, and can be expected to have long-term storage stability. It can be widely used for molding materials, polymer plasticizers, polyamide resin modifiers, compatibilizers, paints, alkaline water dispersibility, binders, inks, and the like.

Claims (8)

A method for polymerizing a lactone, wherein the lactone is polymerized in the presence of a carbodiimide having a purity of 95% or more of an initiator, a catalyst and an active ingredient. The carbodiimide has a general formula R-(-N = C = N-) n-R '(R and R' are a hydrocarbon group having 1 to 24 carbon atoms, and R 'may be the same or different from R, The method of claim 1, wherein R and R 'may form a ring together, and n is an integer of 1 or more. The method according to claim 1, wherein the carbodiimide is N, N'-bis (2,6-diisopropylphenyl) carbodiimide. The lactone polymerization method according to any one of claims 1 to 3, wherein 0.05 to 5 parts by weight of the carbodiimide is used based on 100 parts by weight of the lactone. The method according to any one of claims 1 to 4, wherein the lactone is ε-caprolactone. The lactone polymerization method according to any one of claims 1 to 5, wherein the catalyst is a tin compound and / or a titanium compound. The lactone polymerization method according to any one of claims 1 to 5, wherein the catalyst is a monobutyltin compound and / or a dibutyltin compound. The method according to any one of claims 1 to 5, wherein the catalyst is monobutyltin oxide and / or monobutyltin tris (2-ethylhexanoate).