Low-branched high-molecular polyvinyl acetate, method for its preparing and polyvinyl alcohol based on thereof

FIELD: organic chemistry, polymers.

SUBSTANCE: invention relates to low-branched high-molecular polyvinyl acetate, methods for its preparing and to polyvinyl alcohol prepared on its base. Invention describes low-branched high-molecular polyvinyl acetate prepared by aqueous-emulsion polymerization of vinyl acetate in the presence of emulsifier and initiating agent wherein complexes of alkylcobalt (III) with tridentate ligands of the general formula (I) are used as an initiating agent taken in the amount 0.04-0.2 mas. p., and the polymerization process is carried out at temperature 10-40°C. Polyvinyl acetate prepared by this method has molecular mass 850000 Da, not less, and degree of branching 0.39-0.7. Polyvinyl alcohol with the polymerization degree 6000 Da, not less, and the saponification degree 98-99.9% that is able for making high-module fibers is prepared by saponification of indicated low-branched polyvinyl acetate.

EFFECT: improved preparing method, valuable properties of product.

3 cl, 3 tbl, 10 ex

 

The invention relates to malonaselennai high molecular weight polyvinyl acetate, method thereof and polyvinyl alcohol of which is made of high-strength fibers obtained from the polyvinyl acetate.

One of the applications of polyvinyl acetate (PVA) - getting him high molecular weight polyvinyl alcohol of which is made of heavy-duty high-modulus fibers. For this purpose, as is known, the necessary PVA with high molecular weight (patents US 5310790, US 5403905). This molecular weight is difficult to achieve because of the high values of the constants of chain transfer. For example, in the reactions of chain transfer to monomer activity of vinyl acetate (VA) is 3-4 times higher than that of styrene, and when the chain transfer to polymer in 50 times. This leads to the formation of branched polyvinyl acetate, not suitable for high molecular weight polyvinyl alcohol (PVA), intended for the manufacture of high modulus fibers (PVA).

PVA is obtained by radical polymerization of BA in mass, solution, emulsion or suspension. However, the polymerization of BA in mass, and the solution is difficult to operate, so basically PVA receive in emulsion or suspension.

A method of obtaining high molecular weight PVA block or suspension polymerization of BA in the presence of a radical initiator type (A.S. CCC is no 507590, 1976). The process is carried out at the gradual introduction of the monomer into the reaction zone during the process, and as the initiator of the use oligoprobes alkanoyl-α-replaced alkanoyl General formula [-S-(CH2)n-S-O-O-C-CH-(CH2)m-S-O-O-]kwhere n=4-12, m=3-12, n+m>9, k=6-28, x=N, CH3With2H5, Br, Cl or I.

The disadvantage of this method is the technological difficulties associated with the synthesis, high process temperature (72° (C) (polymerization is carried out at the boiling reaction mixture). In addition, the resulting PVA has a high degree of branching (2,0-4,5), which has a bad effect on physico-chemical properties of PVA obtained based on it.

A method of obtaining an unbranched polyvinyl acetate (A.S. USSR №712823, 1980). The polymerization is carried out in mass in the presence of triethylborane, the initiator is used in amounts 0,019-0,296% by weight of the monomer. The disadvantage of this method is the low molecular weight PVA (MM<540000), and that the polymerization mass is difficult to operate.

The closest to this invention to the technical essence and the achieved result is a method of obtaining high molecular weight PVA-water suspension polymerization in the presence of peroxide initiators and PVA obtained in this way (AS the USSR №704946, 1979). As the initiator is in use here polymeric peroxide dibasic aliphatic acids of the General formula:

[-C-(CH2)m-C-O-O-]nm=5-16, n=5-40

or peroxide tetrazolo General formula

R-C-O-O-C-(CH2)4-C-O-O-C-R, where R=CH3With2H5With3H7With6H13With10H21.

The disadvantages of this method is the high process temperature (60-70°C) and high branching of the resulting PVA (γ=2,4-3,4), which, as mentioned above, has a bad effect on the properties of the obtained PVA, and it does not allow its use for the manufacture of high modulus fibers.

The objective of the invention is to develop a method of obtaining malonaselennai high molecular weight polyvinyl acetate, and also to get him high molecular weight polyvinyl alcohol for the manufacture of high modulus fibers.

This technical result is achieved in that in a method of producing PVA water-emulsion polymerization of vinyl acetate in the presence of emulsifier and initiator, as the initiator of use

complexes of alkylate(III) tridentate ligands of the General formula where R = alkyl from C2to C16in the amount of 0.04 to 0.2 parts by weight, and the polymerization process is carried out at a temperature of 10-40°C and pH 3.5-8.

This technical result is achieved by the fact that the resulting malonaselennai Vysokomolekulyarnye the first PVA has a molecular weight of not less than 850000 and the degree of branching of 0.39-0,7, so it can be used to obtain the PVA suitable for the manufacture of high modulus fibers.

In addition, the technical result is achieved by the fact that obtained by saponification of PVA PVA suitable for the manufacture of high modulus fibers and has a degree of polymerization of not less than 6000 and the degree of saponification 98-99,9%.

Comparative analysis of the prototype allows us to conclude that when carrying out emulsion polymerization of vinyl acetate using a new type of initiator complexes of alkylate(III) tridentate ligands. Thus, the proposed solution meets the criterion of "novelty".

Analysis of the known technical solutions showed that the use of complexes of alkylate(III) tridentate ligands as initiators for emulsion polymerization VA allows a process to economically and technologically suitable conditions, at low temperatures and in a single phase without the addition of components during the process. Also unexpectedly found that in the presence of complexes of alkylate(III) tridentate ligands can get malonaselennai high molecular weight PVA. Thus, the claimed technical solution meets the criterion of "substantial differences".

These complexes - alkyl{2-[(2-amino-ethyl)imino]-Penta-3-EN-4-OST}(1,2-e is Indiamen)cobalt(III) bromide (symbolic formula [RCo(acacen)(en)]Br) - synthesized by the authors according to the following method (for example, R=Et).

The synthesis is carried out in an argon atmosphere at a temperature of 15-25°with constant stirring. In the reactor sequentially injected 430 ml of methanol, to 12.3 ml (120 mmol) of acetylacetone, 10.3 ml of a 70%aqueous solution of ethylene diamine (120 mmol), 14.1 g (60 mmol) of cobalt(II) chloride uranyl, and 19.3 ml of 50%aqueous NaOH solution, 1 ml of 2%aqueous solution of PdCl2in 1 M aqueous KCl solution, 21 ml (273 mmole) of ethylbromide. Uniformly added dropwise a solution of 3.2 g NaBH4(85 mmol) in 25 ml of 5%aqueous NaOH solution for 5 hours. After the gas evolution, the reaction mixture is stirred for 1 hour. Then it is filtered, the solution is evaporated to a volume of 100 ml at a residual pressure of 10-20 mm Hg and a bath temperature of not higher than 40°C. Then add 20 g of NaBr and upon cooling, 100 ml of water and the mixture evaporated in the same way up to a volume of 100 ml Crystallization was carried out at 0°C, the precipitate is filtered off, washed with 15 ml of ice-cold water and dried in air. Then it is washed with dichloromethane (only 150-200 ml) until the disappearance of the green color wash liquid. Then dried the product on the air. The target product is a crystalline powder of red. If necessary, conduct crystallization from methanol with the addition of sodium bromide. To identify use ionoobmennoi TLC on SiO 2(plate Silufol, adjoint - a 0.1 n solution of sodium acetate in a mixture of methanol - water 4:1 by volume). The purity criteria is the presence of one of the spots on the plate, and the almost complete decolorization of the solution of the complex adding hydrochloric acid. Output and the value of the separation factor Rfshown in table 1.

During the synthesis of the complexes listed in table 1, use the following halide alkali: ethylbromide, n-butylbromide, Isopropylamine, n-milbrae, n-activated, n-celibrated, cyclohexylamine, Deut.-activated.

The structure of the complexes prove, on the basis of data1H-NMR, IR spectra and analysis products acidolysis. Spectra1H-NMR (solvent - D2O, 200 MHz, internal standard - sodium 2,2-dimethyl-2-silapentane-5-sulfonate) of the synthesized complexes alkylate similar to each other. Data for complex 1 (table 1) below (identified by the signal δ (ppm), multipletness): CH3CH2With, 0,60, t; CH3-C=N, 1,70, s; CH3WITH, 1,94, s; =CH, 4,98, s. The IR spectra of complexes 1-8 have characteristic absorption bands in the region 3100-3350 cm-1(narrow), related to the stretching vibrations of N-h

Analysis of the products of acidalia synthesized complexes 1-8 were performed using gas-liquid chromatography, TLC and tests for functional groups confirms filepriv the established structural formula. The structure of the complexes is also confirmed by elemental analysis data (table 2).

The invention is illustrated in the examples below.

PVA is produced by saponification of PVA by any known method, for example, an alkali in an environment consisting of ethyl, or propyl, or isopropyl alcohol and water at a ratio of alcohol to water is from 90:10 to 40:60, while the amount of alkali is from 0.4 to 1 mol per 1 mol of the level of vinyl acetate, and the saponification is carried out in the temperature range from 0°C to the boiling point of the solvent. As the alkali may be sodium hydroxide or potassium. Saponification of PVA is carried out until the degree of conversion 98,0 of 99.9%. In the case of branched PVA the saponification process is accompanied by the cleavage of the side chains, and the resulting PVA has a low molecular weight (low degree of polymerization).

Example 1 (invention)

In the reactor with stirrer mixing 100 parts by weight of vinyl acetate with an aqueous phase comprising 4 parts by weight of alkylsulfonate sodium (E-30) with the length of alkyl substituent With15, of 0.1 parts by weight of the initiator complex 1 (table 1), 0,87 parts by weight KN2PO4and of 1.24 parts by weight of Na2HPO4(buffer system) and 200 parts by weight of water. The process is carried out under stirring in nitrogen atmosphere at a temperature of 20°C for 210 minutes prior to conversion 93,8%. The characteristic viscosity of the polymer solution is in benzene (35° C) 2,16 DL/g, which corresponds to the molecular mass 850000 and degree of polymerization 9880. This PVA PVA receive. PVA is produced by saponification of PVA alkali in an environment consisting of ethyl alcohol and water at a ratio of alcohol to water is from 80:20, a temperature of 30°With, the amount of sodium hydroxide is 0.7 mol per 1 mol of link VA. The degree of polymerization of the obtained PVA = 6000, the degree of saponification of 99%. The branching of the PVA γ=0,65.

Examples 2-10 (invention).

Perform analogously to example 1, with changing temperature, pH, type and concentration of emulsifiers, ingredient concentration, buffer compounds and complexes of alkylate(III) tridentate ligands with different structures. PVA is obtained by saponification of PVA as in example 1.

Example 11 (prototype)

In a three-neck flask equipped with a reflux condenser and a stirrer, placed 300 ml of stabilizer suspension (0.1% PVA solution), add 50 ml of VA, which is dissolved 0.312 g (0,67%) polymeric peroxide 1,16-hexadecacarbonyl acid. Suspension polymerization is carried out at a temperature of 60°4 hours, the conversion of 94%. The resulting polymer has a characteristic viscosity [η]=2,41 (acetone, 30° (C), the molecular weight 1187000 and branching γ=2,9.

Recipes polymerization VA and process parameters, as well as some what of waista polymers (characteristic viscosity PVA, molecular weight, degree of polymerization and the degree of branching and the degree of polymerization and a degree of saponification of PVA) are shown in table 3.

The resulting PVA characterize the degree of polymerizationand the degree of saponification.

The degree of polymerization of the PVA is calculated based on the value of the characteristic viscosity, determined in a solution of DMSO at a temperature of 30°according to the formula: [η]=kMναwhere k=1,58·10-4that α=0,84 [Afrikali and other water-Soluble polymers. - Leningrad: Khimiya, Leningrad branch, 1979, p.34].

Determination of the degree of saponification (the content of acetate groups in the polyvinyl alcohol spend allometrically according to GOST 10779-78.

A high degree of polymerization PVA (6000) suggests that it can be used to obtain high modulus fibers.

In table 3 suggests that the use of complexes of gilabert(III) tridentate ligands in emulsion polymerization of vinyl acetate allows to obtain high-molecular malonaselennai polyvinyl acetate, which can serve for the production of high molecular weight polyvinyl alcohol and high modulus fibers based on it.

Table 1

Structure, you are the od and some properties of the complexes of alkylate.
No.ROutput %Rf(TCX)Tpl.*, °
1Et660,34200
2i-Pr65**190
3n-Bu640,40190
4n-Am600,40180
5cyclo-Hex41**195
6n-Oct520,45160
7sex-Oct48**150
8 n-Cet360,47120
* - melting with decomposition

** complexes of second-alkylate decompose under the conditions of the chromatography was carried out
Table 2

The elemental composition of the complexes alkylate
No.With

Est.
With

Neid.
With

Est.
With

Neid.
N

Est.
N

Neid.
O

Est.
O

Neid.
N

Est.
N

Neid.
Br

Est.
Br

Neid.
115,9715,9235,7935,9315,1815,224,344,307,057,0021,6621,71
215,3915,4337,6237,6814,63of 14.574,184,127,31to 7.3220,8720,81
3 14,84the 14.9039,3139,2814,1114,074,034,107,567,5020,1420,12
414,3414,4040,9041,0013,6313,573,893,927,79of 7.7519,4519,41
513,8713,9242,3742,32of 13.18of 13.27of 3.77to 3.738,008,0318,8118,73
613,0013,0645,0545,0912,3712,323,533,508,398,3317,6517,68
713,0013,0645,0545,0912,3712,313,533,528,39 to 8.3417,6517,67
810,4310,5053,1253,079,929,892,832,869,569,5214,1514,17

1. A method of obtaining a high molecular weight polyvinyl acetate water emulsion polymerization of vinyl acetate in the presence of emulsifier and initiator, characterized in that as the initiator of the use complexes alkylate (III) tridentate ligands of General formula

where R is alkyl from C2to C16,

in the amount of 0.04 to 0.2 parts by weight and the polymerization process is carried out at a temperature of 10-40°C and pH 3.5-8.

2. Malonaselennai high molecular weight polyvinyl acetate with a molecular weight of not less than 850000 and degree of branching of 0.39-0,7 suitable for the synthesis of polyvinyl alcohol used for the manufacture of high modulus fibers obtained by the method according to claim 1.

3. Polyvinyl alcohol for the manufacture of high modulus fibers with a degree of polymerization of not less than 6000 and the degree of saponification 98-99,9%, obtained by saponification malonaselennai high molecular weight polyvinyl acetate paragraph is paragraph 2.



 

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