KR100205632B1 - The process for manufacturion of polyvinyl acetic acid by solution polymerization of vinyl acetic acid and polyvinyl acetic acid or polyvinyl alcohol produced thereby - Google Patents

Abstract

The present invention relates to a method for producing polyvinyl acetate, wherein a high molecular weight polyvinyl alcohol is obtained by solution polymerization of vinyl acetate using an azobisdimethylvaleronitrile which can be initiated at 25 ° C. to 60 ° C. using a methanol solvent as an initiator. A method for synthesizing polyvinyl acetate used as a precursor of is disclosed.

According to the present invention, polyvinyl acetate is synthesized at a low polymerization temperature of 25 to 60 ° C., and saponified to an alkaline aqueous solution to obtain polyvinyl alcohol having a number average polymerization degree of 100 to 7,000.

Description

Method for producing polyvinyl acetate by solution polymerization of vinyl acetate and polyvinyl acetate and polyvinyl alcohol produced thereby

The present invention relates to a method for producing poly (vinyl acetate), and more particularly, polyvinyl acetate for use as a precursor of poly (vinyl alcohol) without UV irradiation. It relates to a process for the production of solution polymerization of vinyl acetate at low temperature using only a chemical initiator.

Polyvinyl alcohol, first discovered in 1924 by Herrmann and Hanel (WO Herrmann and W. Haehnel, Federal Republic of Germany Patent 450,286 (1924)) during the saponification of polyvinyl acetate, It is a hydroxy group-containing linear crystalline polymer produced by saponifying a vinyl ester-based polymer such as vinyl acetate, and is widely used in the manufacture of aerosols, clothing fibers, industrial fibers and membranes according to its molecular weight.

In general, polyvinyl acetate is manufactured by bulk polymerization, emulsion polymerization, solution polymerization, and suspension polymerization. Since bulk polymerization has only monomer in the polymerization system, the probability of chain transfer is lower than that of other polymerization methods. Since the high molecular weight polyvinyl alcohol can be obtained, benzoyl peroxide [M. Matsumoto and M. Maeda, Kobunshi Kagaku, 12, 428 (1955)], benzoyl steroyl peroxide [A. Voss and W. Heauer, Federal Republic of Germany Patent 666,866 (1934)], disteroyl peroxide and dilauroyl peroxide [S. Molnar, J. Polym, Sci. Part A-1, 10, 2245 (1972) and difuroyl peroxide [J. W. L. Fordham, G. H. McCain, and L. E. Alexander, J. Polym, Sci, 39, 335 (1959)] have reported many studies on bulk polymerization of vinyl acetate. However, the heat of polymerization of vinyl acetate is very high compared to other vinyl monomers [S. R. Sandler and W. Karo, "Polymer Synthesis", vol. 3, pp. 197-199, Academic Press, New York, 1980], because the reaction rate rises because of this, it is difficult to obtain a high molecular weight polyvinyl alcohol effectively, it is difficult to control the viscosity is difficult to obtain a high conversion rate Have.

According to U.S. Patent No. 4,963,138, ultra high molecular weight polyvinyl alcohol having an intrinsic viscosity of more than 5 (dl / g) is obtained by completely saponifying ultra high molecular weight polyvinyl acetate obtained by initiating vinyl acetate with ultraviolet rays and bulk polymerization at various low temperatures. Synthesized, Imai et al. [K. Imai, T. Shiomi, N. Oda, and H. Otsuka, J. Polym. Sci. : Polym. Chem. Ed, 24, 3225 (1986)] prepared a high molecular weight polyvinyl alcohol from polyvinyl acetate obtained by bulk polymerizing vinyl acetate at 60 ° C. with a very small amount of azobisisobutyronitrile. Go et al. [Y. Go, S. Matsuzawa, Y. Kondo, K. Nakamura, and T. Sakamoto, Kobunshi Kagaku, 25, 55 (1968)] are obtained by bulk polymerization of vinyl trifluoride acetate with benzoylperoxy as an initiator at 60 ° C. The polyvinyl alcohol of alternating high molecular weight with the number-average degree of polymerization 7,700 and the alternating diad group content 55% was synthesize | combined by decomposing vinyl trifluoride acetate, and the dispersion etc. were carried out. , 松澤 秀 二, "第 12 回 鐵 雅 聯 合 硏 究 發表 會 講演 要旨 集 (日本)", pp. 81, 1990] was prepared from polyvinyl trifluoride acetate obtained by bulk polymerization of vinyl trifluoride acetate at 40 ° C. with azobisdimethylvaleronitrile (2,2'-azobis (2,4-dimethylvaleronitrile)) as an initiator. Polyvinyl alcohol having a high-molecular arrangement ultra high molecular weight having an average degree of polymerization of 12,600 and a content of alternating diad group of 57% was prepared. Although the method of Go et al. And acid scattering etc. can obtain polyvinyl alcohol with a very high molecular weight, it has the disadvantage that the price of vinyl trifluoride is very expensive.

Emulsion polymerization is a polymerization system that can increase the polymerization degree and polymerization rate at the same time, but vinyl acetate has a much higher growth reaction rate than other vinyl monomers. J. Flory, "Principles of Polymer Chemistry", pp. 106-161, Cornell University Press, Ithaca, 1953] and it is difficult to obtain high molecular weight polyvinyl alcohol due to the branching reaction due to the high reaction rate in this polymerization system. Therefore, many special emulsion polymerizations have been attempted to obtain polyvinyl alcohol having excellent molarity. Nikolaev et al. [A. F. Nikolaev, KV Belogorodskaya, NP Kukushkina, and OA Pigulevskaya, USSR Patent, 1,016,305 (1978)] have a number average molecular weight having a small amount of branches by accepting manganese triacetylnacetonate as an initiator for low temperature emulsion polymerization. 870,000 polyvinyl acetates were synthesized, and Lanthier [R. Lanthier, U.S. Patent No. 3,303,174 (1967), prepared a polyarray having a polyarray having a number average degree of polymerization of 12,000 from polyvinyl acetate obtained by gamma irradiation emulsion polymerization of vinyl acetate at -15 ° C.

As a method for preparing polyvinyl alcohol, solution polymerization is relatively easy to control viscosity and exotherm by a solvent present in the reaction system. Conix and J. Smets, J. Polym, Sci., 10, 525 (1953)], dimethylcarbitol [K. Ito, J. Polym. Sci. Part A-1, 10, 1481 (1972), acetic acid [L. M. Minsk and E. W. Taylor, US Pat. No. 2,582,055 (1952)], acetic acid / water [S. Okamura and T. Motoyama, J. Polym. Sci, 17, 428 (1955)], dimethylformamide [C. H. Bamford, A. D. Jenkins, and R. Johnston, J. Polym. Sci., 29, 355 (1958)], benzene [W. R. Sorenson and T. W. Campbell, "Preparative Methods od Polymer Chemistry", 2nd Ed, pp. 238, Wiley Interscience, New York, 1968, alcohol system [M. Ueda and K. Kajitani, Macromol. Chem, 108, 138 (1967)] and ethylene chloride [W. R. Conn and HT Neher, J. Polym, Sci., 5, 355 (1950)] have been studied for the solution polymerization of vinyl acetate using various solvents, but this method has been studied due to the frequent chain transfer reaction to the solvent. Formation reactions and termination reactions occur frequently and are disadvantageous for obtaining high molecular weight polyvinyl alcohol.

In order to synthesize polyvinyl acetate having excellent linearity and obtain a high molecular weight polyvinyl alcohol therefrom, redox solution polymerization was attempted at low temperature [J. Furukawa and T. Tsuruta, J. Polym. Sci, 28, 227 (1958)], this method has the disadvantage of very low coloration and conversion by metal catalysts.

Sorokin et al. [A. Y. Sorokin, VA Kuznetsova, and TD Korneva, USSR Patent, 507,590 (1976), synthesized polyvinyl acetate having a number average molecular weight of 1,000,000 by solution polymerization of vinyl acetate using a diacryl peroxide oligomer as an initiator. Phosphorus high molecular weight polyvinyl alcohol was obtained, and Nakamae et al. [K. Nakamae et al. Polymer, 33, 2581 (1992)] saponified a precursor obtained by polymerizing vinyl trifluoride acetate at -78 ° C. under UV irradiation solution to prepare a highly alternating polyvinyl alcohol having a 63% alternating diad group content. Kamiake and Ueda [K. Kamiake and F. Ueda, Japanese Patent Application No. 62-064,807 (1987)], a high molecular weight polyvinyl alcohol from a high molecular weight polyvinyl acetate obtained by polymerizing vinyl acetate with an ultraviolet irradiation solution using acylphosphonate as a photoinitiator. Was prepared.

The effect of solvents on stereoregularity has also been studied a lot, such as Imai et al. [K. Imai, T. Shiomi, N. Oda, and H. Otsuka, J. Polym. Sci: Polym, Chem. Ed, 24, 3225 (1986); K. Imai, T, Shiomi, t. Kawanishi, and T. Jin, J. Polym, Sci. : Polym. chem, Ed, 26, 1962 (1988)] investigated the effects of solvents by adding and polymerizing solvents such as dimethylsulfoxide, methanol, and phenol with vinyl acetate, vinyl propionate and vinyl butyrate as monomers. As a result, in the case of high dipole biproton solvents such as dimethyl sulfoxide, the polymerization proceeds toward the same arrangement as the amount of solvent increases due to electrostatic attraction, and alcohol-based (methanol and phenol) solvents increase steric hindrance due to hydrogen bonding with acetyl groups. As a result, as the content increases, the polymerization proceeds toward the alternating array.

The azobisdimethylvaleronitrile having the structure shown in the following formula (a) has a relatively low onset temperature (50) compared to the existing azobisisobutyronitrile or benzoyl peroxide, which is widely used as an initiator for addition polymerization because of its structural characteristics. It has the advantage that it can cause polymerization even under the above (C) and the inventors of the present invention synthesized polyvinyl acetate which can be used as a precursor of polyvinyl alcohol from the solution polymerization of vinyl acetate using methanol as a polymerization solvent The present invention has been completed.

The present invention is 1x10 ^-5 mol to 1x10 ^-2 mol of the amount of azobisdimethylvaleronitrile as an initiator with respect to 1mol of vinyl acetate, and solution polymerization is carried out using methanol as a solvent at a polymerization temperature of 25 to 60 ℃ to acetyl group It is characterized by a method of producing various types of polyvinyl acetate having a branching degree of 0.5 to 5.0, a number average degree of polymerization of 200 to 18,000, and an alternating arrangement group content of 48 to 54%.

It is preferable to make the molar ratio of a monomer (vinyl acetate) and a solvent at the time of the said solution polymerization 9,9: 0.1-0.1: 9.9.

The azobisdimethylvalonitrile used as an initiator is a white crystalline solid, and is used as a suspension polymerization of vinyl chloride and as a modifier of various monomers such as acrylonitrile, methyl methacrylate and vinyl acetate. To lose.

Azobisdimethylvaleronitrile, a low-temperature initiator used in the present invention, initiates vinyl acetate, a monomer at low temperatures, which cannot be polymerized in general chemical addition polymerization using azobisisobutyronitrile or benzoyl peroxide due to its molecular properties. To cause polymerization.

The maximum concentration of the initiator of the present invention was 1 × 10 ⁻⁵ mol with respect to 1 mol of vinyl acetate, since the polymerization did not occur efficiently at the polymerization temperature of the present invention at lower concentrations.

In addition, the polyvinyl acetate prepared in the present invention was converted to polyvinyl alcohol having a number average polymerization degree of 100-7,000 by saponifying with an alkaline aqueous solution.

Hereinafter, specific embodiments of the present invention will be described. However, the following examples should not be construed as limiting the scope of the invention as they are for illustration only.

Example 1

Into a 200 ml four-necked flask equipped with a thermometer, nitrogen inlet, cooling tower, and anchor type stirrer, 83,2 ml (0.9 mol) of vinyl acetate and 4,05 ml (0.1 mol) of methanol were added and stirred. Pass the alkaline aqueous solution trap and the dryer light trap to pass oxygen and moisture-free nitrogen for 2 hours, remove oxygen and moisture, raise the temperature to 30 ° C of polymerization temperature, and then add azobisdimethylvaleronitrile 0.0249. Add g (1x10 ^-4 mol / mol _VAC ) and polymerize under nitrogen stream for 20 hours, precipitate the polymer in hexane, repeat dissolution and precipitation several times in benzene and hexane to remove residual monomer, and under vacuum 60 It dried at 1 degreeC for 1 day, and obtained white resinous polyvinyl acetate.

Example 2

Into the same device as Example 1, 83.2 ml (0.9 mol) of vinyl acetate and 4.05 ml (0.1 mol) of methanol were added and stirred while passing through a pyrogallol-alkali aqueous solution trap and a dryer light trap to remove oxygen and moisture. After 2 hours of hardening, oxygen and water were removed, and the temperature was raised to 50 ° C. (polymerization temperature). Then, 0.0249 g (1 × 10 ⁻⁴ mol / mol _VAC ) of azobisdimethylvaleronitrile, an initiator, was added for 4 hours under nitrogen flow. After the polymerization, the polymer solution was precipitated in hexane, and then dissolved and precipitated several times in benzene and hexane to remove residual monomer, followed by drying in vacuum at 60 ° C. for 1 day to obtain polyvinyl acetate as a white resin.

Example 3

Into the same device as Example 1, 74.0 ml (0.8 mol) of vinyl acetate and 8.1 ml (0.2 mol) of methanol were added and stirred while passing through a pyrogallol-alkali aqueous solution trap and a dryer light trap to remove oxygen and moisture. After 2 hours of hardening, oxygen and water were removed and the temperature was raised to 30 ° C. (polymerization temperature). Then, 0.0221 g (1 × 10 ⁻⁴ mol / mol _VAC ) of azobisdimethylvaleronitrile, an initiator, was added for 24 hours under a nitrogen stream. After the polymerization, the polymer solution was precipitated in hexane, and then dissolved and precipitated several times in benzene and hexane to remove residual monomer, followed by drying in vacuum at 60 ° C. for 1 day to obtain polyvinyl acetate as a white resin.

Example 4

Into the same device as Example 1, 83.2 ml (0.9 mol) of vinyl acetate and 4.05 ml (0.1 mol) of methanol were added and stirred while passing through a pyrogallol-alkali aqueous solution trap and a dryer light trap to remove oxygen and moisture. After 2 hours of hardening, oxygen and water were removed, and the temperature was raised to 30 ° C. (polymerization temperature). Then, 0.0747 g (3 × 10 ⁻⁴ mol / mol _VAC ) of azobisdimethylvaleronitrile, an initiator, was added for 16 hours under a nitrogen stream. After the polymerization, the polymer solution was precipitated in hexane, and then dissolved and precipitated several times in benzene and hexane to remove residual monomer, followed by drying in vacuum at 60 ° C. for 1 day to obtain polyvinyl acetate as a white resin.

Example 5

Into the same device as in Example 1, 87.8 ml (0.95 mol) of vinyl acetate and 2.03 ml (0.05 mol) of methanol were added to the mixture, and the mixture was stirred and passed through a pyrogallol-alkali aqueous solution trap and a dryer light trap to remove oxygen and water. 2 hours of hardening to remove oxygen and water, the temperature was raised to the polymerization temperature of 30 ℃, and added 0.0079g (3x10 ^-5 mol / mol _VAC ) of azobisdimethylbareronitrile as an initiator for 24 hours under a nitrogen stream After the polymerization, the polymer solution was precipitated in hexane, and then dissolved and precipitated several times in benzene and hexane to remove residual monomer, followed by drying in vacuum at 60 ° C. for 1 day to obtain polyvinyl acetate as a white resin.

Example 6

46.2 ml (0.5 mol) of vinyl acetate and 20.3 ml (0.5 mol) of methanol were added to the same apparatus as in Example 1, and the nitrogen was removed by passing through a pyrogallol-alkali aqueous solution trap and a dryer light trap while stirring. After 2 hours of hardening, oxygen and water were removed, and the temperature was raised to 30 ° C. (polymerization temperature), followed by adding 0.0138 g (1 × 10 ⁻⁴ mol / mol _VAC ) of azobisdimethylvaleronitrile, an initiator, for 36 hours under nitrogen stream. After the polymerization, the polymer solution was precipitated in hexane, and then dissolved and precipitated several times in benzene and hexane to remove residual monomer, followed by drying in vacuum at 60 ° C. for 1 day to obtain polyvinyl acetate as a white resin.

Example 7

Into the same device as Example 1, 83.2 ml (0.9 mol) of vinyl acetate and 4.05 ml (0.1 mol) of methanol were added and stirred while passing through a pyrogallol-alkali aqueous solution trap and a dryer light trap to remove oxygen and moisture. After passing for 2 hours, oxygen and water were removed and the temperature was raised to the polymerization temperature of 40 ° C., and then 0.0249 g (1 × 10 ⁻⁴ mol / mol _VAC ) of azobisdimethylvaleronitrile, an initiator, was added for 10 hours under nitrogen flow. After the polymerization, the polymer solution was precipitated in hexane, and then dissolved and precipitated several times in benzene and hexane to remove residual monomer, followed by drying in vacuum at 60 ° C. for 1 day to obtain polyvinyl acetate as a white resin.

Example 8

46.2 ml (0.5 mol) of vinyl acetate and 20.3 ml (0.5 mol) of methanol were added to the same apparatus as in Example 1, and the nitrogen was removed by passing through a pyrogallol-alkali aqueous solution trap and a dryer light trap while stirring. After 2 hours of hardening, oxygen and water were removed and the temperature was raised to 50 ° C., the polymerization temperature. Then, 0.0138 g (1 × 10 ⁻⁴ mol / mol _VAC ) of azobisdimethylvaleronitrile, an initiator, was added for 6 hours under a nitrogen stream. After the polymerization, the polymer solution was precipitated in hexane, and then dissolved and precipitated several times in benzene and hexane to remove residual monomer, followed by drying in vacuum at 60 ° C. for 1 day to obtain polyvinyl acetate as a white resin.

Example 9

37.0 ml (0.4 mol) of vinyl acetate and 24.3 ml (0.6 mol) of methanol were added to the same apparatus as in Example 1, and passed through a pyrogallol-alkali aqueous solution trap and a dryer light trap while stirring to remove nitrogen and oxygen. After 2 hours of hardening, oxygen and water were removed, and the temperature was raised to 30 ° C. (polymerization temperature), followed by 0.0111 g (1 × 10 ⁻⁴ mol / mol _VAC ) of azobisdimethylvaleronitrile, an initiator, for 40 hours under nitrogen flow. After the polymerization, the polymer solution was precipitated in hexane, and then dissolved and precipitated several times in benzene and hexane to remove residual monomer, followed by drying in vacuum at 60 ° C. for 1 day to obtain polyvinyl acetate as a white resin.

Example 10

37.0 ml (0.4 mol) of vinyl acetate and 24.3 ml (0.6 mol) of methanol were added to the same apparatus as in Example 1, and passed through a pyrogallol-alkali aqueous solution trap and a dryer light trap while stirring to remove nitrogen and oxygen. After passing for 2 hours, remove oxygen and water, raise the temperature to 50 ℃, and add 0.0333g (3x10 ^-4 mol / mol _VAC ) of initiator azobisdimethylvaleronitrile. After the polymerization, the polymer solution was precipitated in hexane, and then dissolved and precipitated several times in benzene and hexane to remove residual monomer, followed by drying in vacuum at 60 ° C. for 1 day to obtain polyvinyl acetate as a white resin.

The molarity of the polyvinyl acetate prepared in the above embodiments and the polyvinyl alcohol prepared using the same are shown in Table 1 below.

As described above, according to the present invention, a high molecular weight polyvinyl acetate may be produced in high yield at a low temperature using only a chemical initiator without UV irradiation, and thus a high molecular weight polyvinyl alcohol may be produced. .

While the invention has been described in detail only with respect to the described embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible within the technical scope of the invention, and such modifications and variations belong to the appended claims.

Claims (4)

The amount of azobisdimethylvaleronitrile, which is an initiator, to 1 mol of vinyl acetate is 1 * 10 ^-5 mol to 1 * 10 ^-2 mol, and solution polymerization is carried out using methanol as a solvent at a polymerization temperature of 25 to 60 ° C. A method for producing polyvinyl acetate by solution polymerization of vinyl acetate, comprising polyvinyl acetate having an average degree of polymerization of 200 to 18,000, alternating diad group contents of 48 to 54, and a degree of branching of 0.5 to 5.0 for acetyl groups. The method for producing polyvinyl acetate by solution polymerization of the vinyl acetate according to claim 1, wherein the molar ratio of the monomer (vinyl acetate) and the solvent during solution polymerization is 9.9: 0.1 to 0.1: 9.9. The method of claim 1, wherein a predetermined concentration of vinyl acetate and methanol are mixed and stirred in a mixer equipped with a thermometer, a nitrogen inlet, a cooling tower, and an anchor stirrer to remove oxygen and moisture by passing through a pyrogallol-alkali aqueous solution trap and a dryer light trap. Polyurethane by solution polymerization of vinyl acetate, characterized in that the oxygen and water are removed by passing through nitrogen and the temperature is raised to the polymerization temperature, and then the azobisdimethylvaleronitrile, which is an initiator, is added in a predetermined concentration, and polymerized under a stream of nitrogen. Method for producing vinyl acetate. A polyvinyl alcohol having a number average degree of polymerization of 100 to 7,000, which is prepared by saponifying a polyvinyl acetate prepared according to claim 1 with an aqueous alkaline solution.