JP2534048B2 - Method for copolymerizing tetrahydrofuran and ε-caprolactone - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for copolymerizing tetrahydrofuran and ε-caprolactone.

(Prior art) Tetrahydrofuran (hereinafter referred to as THF) has been
It is known to polymerize with a cationic catalyst such as a protonic acid, a Lewis acid or an ion complex. Further, it is known that lactones are easily polymerized by a cation catalyst or an anion catalyst such as β-propiolactone and ε-caprolactone. Polymers obtained by these, that is, polytetramethylene ether glycol, polycaprolactone glycol, etc., are useful materials as soft segments of polyurethane resins and polyester resins.

(Problems to be solved by the invention) However, polytetramethylene ether glycol has a polyether as a main chain, while a ring-opening polymer of a lactone such as polycaprolactone glycol has a polyester as a main chain, and therefore has hydrolysis resistance and prevention. They have contradictory advantages and disadvantages in terms of mold resistance, heat resistance and light resistance. As a solution to complement these mutual drawbacks, a polyether polyester glycol prepared by copolymerization of THF and lactones is considered. However, since there is a large difference in the polymerizability between THF and lactones, it is difficult to copolymerize. Lewis acid as a catalyst for the copolymerization of THF and ε-caprolactone [Polymer Journal, Vol.3, No.3 389-393 (1971)]
However, it is described that the obtained polymer has a high block property of polytetrahydrofuran and poly ε-caprolactone. That is, THF and ε-caprolactone do not randomly polymerize, but become a block copolymer or a mixture of polytetramethylene ether and polycaprolactone glycol. Thus THF and ε
-Caprolactone is difficult to copolymerize due to the difference in their respective polymerization properties.

(Means for Solving the Problem) As a result of intensive studies in view of the above circumstances, the present inventors have conducted polymerization under an initiator in which Lewis acid is used in combination with a small amount of a 3- to 4-membered cyclic ether. It was found that THF and .epsilon.-caprolactone were successfully copolymerized by the above, and the present invention was completed.

In the present invention, the Lewis acid and the 3- to 4-membered cyclic ether which play a role of initiating the polymerization include boron trifluoride,
Metal or non-metal halides such as phosphorus pentafluoride, antimony pentafluoride, antimony pentachloride, aluminum chloride, ferric chloride, titanium tetrachloride, tin tetrachloride; silicon dioxide, titanium dioxide, zirconium dioxide, aluminum oxide, Further, solid acids such as heteropolyacids and solid acids in which the above halides are impregnated; complexes of boron trifluoride, antimony pentafluoride and the like with chain and cyclic ethers such as diethyl ether and tetrahydrofuran; 3 to 4 members Examples of the cyclic ether include epoxides such as ethylene oxide, propylene oxide and epichlorohydrin, and oxetanes such as oxetane, 3-methyloxetane and 3,3-bis (chloromethyl) -oxetane.

The tetrahydrofuran also includes substituted tetrahydrofuran such as 2-methyl- and 3-methyl-.

The polymerization temperature in the present invention is not limited, but it is usually preferably carried out at a temperature of 0 ° C to 70 ° C. Indeed, the appropriate polymerization temperature will be determined by the type of monomer, initiator, or molecular weight of the desired copolymer.
The same applies to the polymerization time, and although it varies depending on the polymerization system, it is approximately in the range of 1 to 15 hours.

In the present invention, it is necessary to reduce the water content of the polymerization system as much as possible in order for the copolymerization to proceed properly, and it is preferable to use a sufficiently dehydrated monomer and an initiator, and to carry out in a dry nitrogen atmosphere during the polymerization. . The polymerization reaction can also be carried out in an inert organic solvent such as benzene, toluene, xylene and ethers, but in this case as well, it is preferable to use a sufficiently dehydrated product in advance in order to avoid mixing of water.

In carrying out the copolymerization, the addition method of each component is
It is common practice to add ε-caprolactone and a cyclic ether, which is one component of the initiator, to a predetermined temperature and then add a Lewis acid. However, the addition order of the cyclic ether and the Lewis acid may be reversed. . In either addition method, the component to be added last needs to be added gradually because the copolymerization reaction is an exothermic reaction, and in some cases cooling must be performed to remove heat generation.

The copolymerization completed liquid is neutralized with an alkaline aqueous solution in order to deactivate the catalyst component, and the unreacted monomer is heated and distilled to be recovered. Then, the desired copolymer can be obtained by purification by a known method such as washing with water or adsorption. In the purification step, the use of the above-mentioned inert organic solvent facilitates the purification, which is recovered by distillation and reused.

According to the copolymerization method of the present invention, THF and ε-caprolactone are randomly polymerized, and GPC of the obtained copolymer has a single peak. This copolymer is effective as a raw material in which properties such as hydrolysis resistance, mildew resistance, heat resistance, and light resistance are improved, and the drawbacks which the polyether and polyester have when they are independent.

(Example) Next, the present invention will be described in more detail with reference to examples.
The following examples do not limit the present invention in any case. Percentages in the examples are by weight.

In the examples, the hydroxyl value is a value measured by the pyridine-acetic anhydride method. The unreacted monomer in the polymerization solution is quantified by gas chromatography (abbreviated as GC).
The copolymerization rate (reaction rate) was determined from this quantitative value. ¹ H-NMR and ¹³ C-NMR analysis of the copolymer were performed by JEOL NMR, FX-60. Also gel permeation chromatography (GP
(To be abbreviated as C), Toyo Soda HLC was used, and the number average molecular weight and the molecular weight distribution were determined by known methods.

Example 1 Stirrer, thermometer, 72 g (1.0 mol) of dehydrated THF in a four-necked 500 cc separable flask capable of N ₂ sealing, ε-
114 g (1.0 mol) of caprolactone and boron trifluoride THF
Charge 14g of complex, and keep it at 20 ℃ in a constant temperature water bath with stirring and mixing. Then, using a dropping funnel, 11.6 g of propylene oxide was gradually added over 10 minutes.
Thereafter, the reaction was carried out at 20 ° C. for 4 hours. A small amount of sampling was performed at the stage of 4 hours, and unreacted THF and ε-caprolactone were quantified by GC.

To the remaining polymerization liquid, 300 g of a 10% sodium carbonate aqueous solution was added to stop the polymerization reaction. A distillation apparatus was attached to the reaction flask, and the temperature was raised by heating in an oil bath to distill off unreacted monomers. Next, after standing to cool, the mixture is left to stand still, the lower aqueous layer is withdrawn, 100 cc of toluene and 80 cc of water are added to the upper organic layer, and the mixture is stirred and mixed at 70 ° C., then left to stand again and the aqueous layer is withdrawn. 60 more water
Repeat the water washing operation performed by adding cc three times, and remove the toluene from the last organic layer by vacuum distillation to remove the viscous copolymer.
Obtained 105.3 g.

The copolymerization rate (reaction rate) of THF and ε-caprolactone, and the analysis result of the obtained copolymer were as follows.

Copolymerization rate (%) THF 52.9 ε-caprolactone 56.5 Copolymer yield (%) 54.9 Hydroxyl number (mgKOH / g) 49.1 Number average molecular weight [GPC] 2210 NMR analysis composition (unit mol%) [THF] 44 [ε -Caprolactone] 46 [propylene oxide] 10 The obtained GPC pattern was a single peak, not a bimodal peak as described in the above-cited document.

Comparative Example 1 Using the same reaction apparatus as in Example 1, 72 g of THF, 114 g of ε-caprolactone, and 14 g of boron trifluoride THF complex were charged, and the reaction was carried out at 20 ° C. for 4 hours. When the polymerization solution was sampled at the 4-hour stage, unreacted monomers were quantified by GC, and the polymerization rate was calculated, the THF polymerization rate was 0.
%, The polymerization rate of ε-caprolactone was 10%, and the copolymerization reaction hardly proceeded.

Example 2 Using the same reactor as in Example 1, 72 g of THF, 114 g of ε-caprolactone and 15 g of boron trifluoride diethyl ether complex were charged, and 9 g of ethylene oxide was gradually added at 25 ° C. over 10 minutes, and further 25 The reaction was carried out at ℃ for 4 hours. At the same time as sampling the polymerization reaction liquid, 300 g of a 10% sodium carbonate aqueous solution was added to stop the polymerization reaction, and the same post-treatment and purification operations as in Example 1 were performed.
The following results were obtained.

Copolymerization rate (%) THF 60.9 ε-caprolactone 57.5 Copolymer yield (%) 57.7 Hydroxyl number (mgKOH / g) 46.4 Number average molecular weight [GPC] 2380 (single peak) Example 3 Reaction similar to Example 1 Using the equipment, charged with THF 72g, ε-caprolactone 114g, propylene oxide 10g, 20
Slowly add 13 g of tin tetrachloride at 10 ° C over 10 minutes,
Further, the reaction was carried out at 20 ° C. for 4 hours. The polymerization solution was sampled and immediately added with 250 g of a 10% sodium carbonate aqueous solution to stop the polymerization reaction. Next, the unreacted monomer was distilled off, and the mixture was allowed to cool, allowed to stand still for liquid separation, and the separated lower aqueous layer was extracted. To the remaining organic layer, 100 cc of toluene was added and mixed well, 10 g of diacarite was added, and the mixture was filtered using a filter paper. The filtrate was distilled under reduced pressure, and toluene was distilled off to obtain 108 g of a copolymer.

Copolymerization rate (%) THF 56.4 ε-caprolactone 56.8 Copolymer yield (%) 55.0 Hydroxyl number (mgKOH / g) 35.2 Number average molecular weight [GPC] 3100 (single peak)

Claims (2)

(57) [Claims] 1. Tetrahydrofuran and ε characterized in that a Lewis acid and a 3- to 4-membered cyclic ether are used in combination as a catalyst.
-A method of copolymerizing caprolactone. 2. The copolymerization method according to claim 1, wherein the 3- to 4-membered cyclic ether is an epoxide or an oxetane.