KR100571511B1 - Method for preparing polyvinyl alcohol having improved alternating arrangement through vinyl tecanoate polymerization - Google Patents

Abstract

In the present invention, polyvinyldecanoate (PVD) having high alternating properties for use as a precursor of polyvinyl alcohol having excellent alternating arrangement is used azobisisobutyronitrile as a chemical initiator and t-butyl alcohol as a solvent. (1) vinyl decanoate as monomer, t -butyl alcohol as solvent, and azobisisobutyin as initiator, and polymerizing with (t-butyl alcohol) and saponifying again. A polymerization step of using ronitrile, polymerizing t-butyl alcohol in a range of 0.1 to 10 moles with respect to 1 mole of vinyl decanoate to polyvinyl decanoate; And (2) a saponification step of saponifying the polymer obtained in the polymerization step with an alkali solution.

Polyvinyl alcohol, alternating arrangement, hot water resistance, vinyl decanoate

Description

Manufacturing method of polyvinyl alcohol having improved syndiotacticity through polymerizing vinyl decanoate}

The present invention relates to a method for producing polyvinyl alcohol having improved alternating arrangement through polymerization of vinyltecanoate which is a monomer. More specifically, the present invention uses azobisisobutyronitrile as a solvent as a polyvinyl decanoate (PVD) having high alternating properties for use as a precursor of polyvinyl alcohol having excellent alternating arrangement as a chemical initiator. It relates to a method of producing polyvinyl alcohol by polymerizing with t-butyl alcohol and then saponifying again.

Conventionally, polyvinyl alcohol was first manufactured by Herrmann and Hanel (Germany) of Germany using polyvinyl acetate and polymerizing it with polyvinyl acetate, followed by saponification thereof. Polyvinyl alcohol has higher strength and elastic modulus than polyamide, polyester, and polyacrylonitrile fibers, which are general fibers, and is used as various industrial materials because of its excellent adhesion, water dispersibility, alkali resistance, and chemical resistance. have. Recently, it has been used in various ways as reinforcement materials such as concrete and cement reinforcement materials and rubber and plastics, and has been researched and developed as a material having high application potential in new fields.

On the other hand, polyvinyl alcohol has two types of hybrid arrangement and alternating arrangement, the more the alternating arrangement is advantageous in physical properties. Since polyvinyl alcohol is made by saponifying a polyvinyl ester which is a precursor, the stereoregularity of polyvinyl alcohol is entirely dependent on the stereoregularity of the precursor. Therefore, in order to produce a polyvinyl alcohol containing abundant alternating groups, it is preferable to use a monomer having an ester group causing a steric hindrance so as to obtain an alternating precursor or to improve the polymerization method. In particular, it is known that the use of a monomer having an ester group causing steric hindrance has a greater effect.

Many monomers are known for synthesizing precursors for producing polyvinyl alcohol having a large number of alternating moieties, and examples thereof include polyvinyl formate, trifluoroacetate, and polyvinyl benzyl ether. Among them, vinyl pivalate is known to express the best alternating arrangement due to the steric hindrance of the t-butyl group, but there is a disadvantage that the saponification reaction is not easy. In addition, although vinyl fluoride acetate is widely used as a monomer for obtaining alternating polyvinyl alcohol, it has a problem that the price is relatively high.

It is an object of the present invention to use polyvinyl alcohol having an improved alternating arrangement through polymerization of polyvinyl decanoate having high alternating properties for use as a precursor of polyvinyl alcohol having excellent alternating arrangement using vinyl decanoate as a monomer. It is to provide a method for producing a.

Method for producing a polyvinyl alcohol having an alternating arrangement by vinyl tecanoate polymerization according to the present invention, (1) vinyl decanoate as a monomer, t -butyl alcohol as a solvent and azobisisobutyronitrile as an initiator Using, but polymerizing with t-butyl alcohol in the range of 0.1 to 10 moles per 1 mole of vinyl decanoate to polymerize with polyvinyl decanoate; And (2) a saponification step of saponifying the polymer obtained in the polymerization step with an alkali solution.

In the polymerization step, azobisisobutyronitrile is used within the range of 1.0 * 10 ⁻⁶ to 1.0 * 10 ⁻⁴ (mol / mol of VD) per mol of vinyl decanoate, and within the range of 45 to 65 ° C. It is polymerized at the polymerization temperature.

Hereinafter, the present invention will be described in detail with reference to specific examples.

Method for producing a polyvinyl alcohol having an alternating arrangement by vinyl tecanoate polymerization according to the present invention, (1) vinyl decanoate as a monomer, t -butyl alcohol as a solvent and azobisisobutyronitrile as an initiator Using, but polymerizing with t-butyl alcohol in the range of 0.1 to 10 moles per 1 mole of vinyl decanoate to polymerize with polyvinyl decanoate; And (2) a saponification step of saponifying the polymer obtained in the polymerization step with an alkali solution.

That is, the present invention provides a method for preparing polyvinyl alcohol having improved alternating arrangement by solution polymerization of vinyl decanoate (CH ₃ (CH ₂ ) ₈ CO ₂ CH = CH ₂ ).

The vinyl decanoate has a structure in which a bulky side chain group (CH ₃ (CH ₂ ) ₈ CO ₂ C-) is bonded to a vinyl group. A vinyl alcohol precursor can be obtained. Since the vinyl decanoate is relatively cheap and easily saponified with alkali, it can be said that it is useful in producing polyvinyl alcohol having high alternating arrangement.

In the polymerization step of (1), vinyl decanoate as described above is used as a monomer, t -butyl alcohol is used as a solvent, and azobisisobutyronitrile is used as an initiator, but t is used for 1 mole of vinyl decanoate. It is a step of polymerizing butyl alcohol to polyvinyl decanoate within the range of 0.1 to 10 moles. Substantially, the polymerization takes place in this polymerization step, and then the polymer obtained in the polymerization step is saponified according to a conventional saponification method to obtain polyvinyl alcohol as desired. In the above, when the molar ratio of t-butyl alcohol to vinyl decanoate is less than 0.1, there may be a problem that the workability is lowered due to the increase in viscosity, on the contrary, when it exceeds 10, the number average polymerization degree and the alternating arrangement content decrease. There may be a problem.

In the polymerization step, azobisisobutyronitrile is used within the range of 1.0 * 10 ^-6 to 1.0 * 10 ^-4 moles per mole of vinyl decanoate, and is polymerized at a polymerization temperature within the range of 45 to 65 ° C. . When the azobisisobutyronitrile is used in an amount of less than 1.0 * 10 ^-6 per mole of vinyl decanoate, there may be a problem that the reaction time is too long to reduce productivity, on the contrary 1.0 * 10 ^-4 If it exceeds mole, there may be a problem that the number average polymerization degree and the alternating arrangement content is lowered. In addition, when the polymerization temperature is less than 45 ℃, there may be a problem that the polymerization hardly occurs, on the contrary, if it exceeds 65 ℃, the number average polymerization degree and the alternating diad group content of the main properties of the polyvinyl alcohol is lowered There may be a problem.

The manufacturing method of the polyvinyl alcohol fiber of this invention mentioned above is demonstrated further.

Vinyltecanoate used as a monomer in the polymerization can be commercially purchased from Aldrich, USA, etc., preferably washed with 50% by weight aqueous sodium sulfite (NaHSO ₃ ) solution, calcium chloride (CaCl ₂ After drying with a common drying agent such as), it is preferable to use the product after purification by fractional distillation. Azobisisobutyronitrile (AIBN; 2,2'-azobis (isobutyronitrile)) as an initiator is preferably used by refining by recrystallization in methanol, t -butyl alcohol may be used without further purification. The molar ratio of t-butyl alcohol to vinyl decanoate is preferably maintained at 0.1 to 10. The polymerization of vinyl decanoate is in the range of 0.1 to 10 moles of t-butyl alcohol per 1 mole of vinyl decanoate. Azobisisobutyronitrile is used within the range of 1.0 * 10 ^-6 to 1.0 * 10 ^-4 moles per mole of vinyl decanoate, and is carried out at a polymerization temperature within the range of 45 to 65 ° C. Upon completion of the polymerization under the conditions, the solvent and the unreacted monomer are removed by distillation, and then the reaction is dissolved in acetone and precipitated in methanol / water to classify pure polyvinyldecanoate.

Polyvinyl alcohol is prepared according to a conventional saponification reaction, i.e., by dissolving 3 g of polyvinyl decanoate in 300 ml of tetrahydrofuran and then saponifying at room temperature by slowly adding a sodium hydroxide / methanol / water solution. can do.

Hereinafter, preferred embodiments and comparative examples of the present invention will be described.

The following examples are intended to illustrate the invention and should not be understood as limiting the scope of the invention.

Example 1

Vinyltecanoids, which are used as monomers in polymerization, are purchased from Aldrich, United States, and contain 50% by weight of sodium sulfite (NaHSO ₃ ). The solution was washed with an aqueous solution, dried over calcium chloride, and purified by fractional distillation. Since the polymerization reaction does not occur effectively if water remains, drying with calcium chloride is carried out for a sufficient time so that the water is almost completely removed. Azobisisobutyronitrile as an initiator was used after recrystallization in methanol. t-butyl alcohol was used without further purification. After mixing vinyl decanoate and t-butyl alcohol in a 1: 1 molar ratio and stirring under a nitrogen stream, azobisisobutyronitrile was charged in an amount of 3.0 * 10 ^-4 mole per mole of vinyl decanoate. The reaction was carried out for 6 hours. After the synthesis was completed, the solvent and the unreacted monomer were distilled off, and then the reaction was dissolved in acetone and precipitated in methanol / water to obtain pure polyvinyldecanoate.

Polyvinyl alcohol was prepared by dissolving 3 g of polyvinyl decanoate in 300 ml of tetrahydrofuran according to a conventional saponification method, and then saponifying at room temperature by slowly adding a sodium hydroxide / methanol / water solution.

Under these conditions, the polymerization temperature was carried out at 45 ° C (Example 1), 50 ° C (Example 2), 55 ° C (Example 3), 60 ° C (Example 4) and 65 ° C (Example 5).

Comparative example

Polyvinyl alcohol was prepared in the same manner as in Example 3, except that vinyl acetate was used instead of vinyl decanoate as the polymerization monomer.

The alternating arrangement group content, number average polymerization degree, and conversion rate of the polyvinyl alcohols obtained in the above Examples and Comparative Examples were measured as follows, and are shown in Table 1 below.

* Alternating diad content

In order to examine the stereoregularity of polyvinyl alcohol, a proton nuclear magnetic resonance spectrometer (NMR; nuclear magnetic resonance; measured by Varian, United States) was used. As a solvent, d-dimethyl sulfoxide (deuterium-DMSO; dimethylsulfoxide) was used. Stereoregularity analysis was obtained from the relative area ratios of alternating array (rr), hybrid array (mr), and identical array (mm) Tried peaks at 4.22, 4.43 and 4.65 ppm, respectively.

Wherein m = mm + 0.5 mr, r = rr + 0.5 mr, where m is the same array and r represents an alternating array.

* Number Average Polymerization Analysis

In order to obtain the molecular weight of polyvinyl alcohol, polyvinyl alcohol was acetylated as follows to prepare polyvinyl acetate. Acetylation of polyvinyl alcohol is as follows. 1 g of polyvinyl alcohol, 2 ml of pyridine, 20 ml of acetic anhydride and 20 ml of acetic acid were placed in a three-necked flask, and reacted for 72 hours at 100 ° C. under a nitrogen stream. The reaction was dissolved in methanol and reprecipitated in hexane. The resulting polyvinylacetate (PVAc) was dried at 60 ° C. for 24 hours under vacuum. After measuring the viscosity using this, the polyvinylacetate number average polymerization degree was calculated | required using the following formula.

[η] = 8.91 × 10 ^-3 × P _n ^0.62

Is the absolute viscosity and P _n is the number average polymerization degree.

* Conversion of monomers to polymers

Conversion rate was calculated by the following equation.

Alternating Diad Content (%) Number average polymerization degree of polyvinyl alcohol % Conversion to polymer Example 1 71.2 8,000 43.3 Example 2 69.7 6,000 43.4 Example 3 65.1 4,500 62.2 Example 4 62.7 2,800 64.1 Example 5 59.1 1,500 65.2 Comparative example 54.3 3,000 56.1

As a result of the synthesis of the above embodiments, as shown in Table 1 above, when comparing the examples with the comparative example, when the vinyl decanoate monomer is used than when the vinyl acetate is used as a monomer alternate arrangement It can be seen that the content of the diamond group is significantly increased. It can be seen that especially when the temperature is low, it has better physical properties.

It can be seen that the lower the polymerization temperature, the better the content of the alternating diad group and the number average polymerization degree, which are the main properties of the polyvinyl alcohol. However, the higher the conversion rate of the polymer is, the higher the productivity is. Therefore, it was confirmed that it is advantageous to polymerize in the direction of lower temperature when the physical properties of polyvinyl alcohol are important, and in the direction of increasing the temperature when productivity is important.

Therefore, according to the present invention, there is an effect of providing a method of producing polyvinyl alcohol having high alternating arrangement using vinyl decanoate which is relatively inexpensive and easily saponified with alkali. In addition, the polymerization and saponification process is similar to the method for producing polyvinyl alcohol, so that the mass production can be easily performed by providing a production method that can be produced in existing equipment, and the polyvinyl alcohol having high alternating arrangement with excellent physical properties. It is effective to supply enough commercially.

Although the present 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 present invention, and such modifications and modifications are within the scope of the appended claims.

Claims (3)

(1) Using vinyl decanoate as a monomer, t -butyl alcohol as a solvent, and azobisisobutyronitrile as an initiator, with t -butyl alcohol within the range of 0.1 to 10 moles per 1 mole of vinyl decanoate. A polymerization step of polymerizing with polyvinyl decanoate; And (2) a saponification step of saponifying the polymer obtained in the polymerization step with an alkali solution; Method for producing a polyvinyl alcohol having an alternating arrangement through the vinyl tecanoate polymerization, characterized in that consisting of. The method of claim 1, In the polymerization step, azobisisobutyronitrile is used within the range of 1.0 * 10 ⁻⁶ to 1.0 * 10 ⁻⁴ (mol / mol of VD) per mol of vinyl decanoate, and within the range of 45 to 65 ° C. Method for producing a polyvinyl alcohol having an alternating arrangement through the vinyl tecanoate polymerization, characterized in that the polymerization at a polymerization temperature. A polyvinyl alcohol having an alternating diad group content of 58 to 71% and a number average degree of polymerization of 1,500 to 8,000 obtained by polymerizing vinyl decanoate by the method of claim 1 or 2.