JPS6258607B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing brominated polyvinyltoluene. More specifically, the present invention relates to a method for producing brominated polyvinyltoluene by polymerizing a vinyltoluene monomer and brominating the polymer without disturbing the molecular weight distribution of the polymer. Brominated polyvinyltoluene, which has a narrow molecular weight distribution, is useful as a photosensitive resist material with high resolution and excellent dry etching resistance (Patent Application No. 1983).
-022873, patent application 1983-023764, etc.). Methods for brominating polyvinyl aromatic compounds are well known. For example, as a method for brominating polystyrene, a peroxide such as benzoyl peroxide or an azozoic acid such as azobisisobutyronitrile is used in a solvent such as carbon tetrachloride. A method of brominating polystyrene using a brominating agent such as sulfuryl bromide or N-bromosuccinimide in the presence of a catalyst such as a compound is known. However, all of these methods have the disadvantage that main chain scission of the raw material polymer occurs during bromination, and the molecular weight distribution of the produced brominated product is extremely wide compared to that of the raw material polymer. are doing. The present inventors have completed the present invention as a result of extensive research in view of this current situation. According to the present invention, a vinyltoluene monomer is polymerized in the presence of an organometallic of the general formula RM (R is selected from an alkyl, aryl or aralkyl group, and M is selected from lithium, sodium or potassium); By using a solution consisting of a polymer solution and an aqueous solution containing bromide ions as an anolyte and applying electricity using a diaphragm electrolytic cell, brominated polyvinyltoluene having almost the same molecular weight distribution as the polymer can be easily produced. Brominated polyvinyltoluene having an arbitrary bromination rate can be produced by simply changing the amount of current applied. The present invention consists of a step of polymerizing a vinyltoluene monomer and a step of brominating the polymer. Each step will be explained below. The polymerization step can be carried out by a normal anionic polymerization method. That is, the vinyl toluene monomer can be dehydrated with a suitable dehydrating agent in a vacuum or in an inert gas stream, followed by distillation and used for polymerization. The polymerization solvent may be any solvent that does not inhibit anionic polymerization and the next bromination step and has sufficient solubility for the produced polymer, such as aromatic solvents such as benzene and t-butylbenzene. Examples include type compounds. These solvents can be used as a polymerization solvent after being dehydrated and distilled in the same manner as the vinyl toluene monomer. The polymerization initiator has the general formula RM (R is selected from alkyl, aryl or aralkyl group,
M is selected from lithium, sodium or potassium. ) can be used. Examples of such organometallic compounds include butyllithium, sodium naphthalene, sodium anthracene, sodium biphenyl, phenylisopropyl potassium, α-methylstyrene tetramer potassium, and the like. The polymerization in the present invention is carried out under high vacuum or in an inert gas stream, usually with sufficient stirring of the polymerization system consisting of vinyltoluene monomer and polymerization solvent, using a vacuum burette, etc., to determine the amount of impurities in the polymerization system and This can be carried out by adding an initiator adjusted to an appropriate concentration depending on the molecular weight of the polymer to be produced. The concentration of vinyl toluene monomer is 0.5 to 20 depending on the molecular weight of the desired polymer.
Preferably, it is expressed in % by weight. There are no particular restrictions on the polymerization temperature, but it is preferably carried out at 50°C or lower. The above polymerization can be easily stopped by adding a C ₁ to C ₆ lower alcohol. The polymer solution thus obtained can be used in the bromination step, with the polymer concentration adjusted to 0.5 to 20% by weight depending on its molecular weight. Bromination of the polymer is carried out by charging a polymer solution adjusted to an appropriate concentration according to its molecular weight and an aqueous solution containing bromine ions into the anode chamber of a diaphragm electrolytic cell, and stirring to reach the desired bromine content. This can be achieved by applying the amount of electricity necessary to obtain the brominated polyvinyltoluene having the following properties. Although the present invention can be carried out using a membraneless electrolytic cell, the use of a membraneless electrolytic cell significantly reduces the bromination efficiency, which is not preferable. Although the reason for this is not clear, the brominated polyvinyltoluene obtained in the present invention is mainly brominated at the α-position of the benzene nucleus. On the other hand, it is known that such bromides easily undergo electrode reduction to the corresponding hydrocarbons. Therefore, it is thought that when the present invention is carried out using a membraneless electrolytic cell, electrolytic bromination of polyvinyltoluene and electrolytic reduction of the produced brominated polyvinyltoluene occur in parallel, resulting in a significant decrease in electrolytic bromination efficiency. It will be done. As a bromine ion source for an aqueous solution containing bromine ions, hydrobromic acid or a salt containing bromine ions can be used. Such a salt may be any salt that is soluble in water and has conductivity that allows the salt solution to undergo an electrolytic reaction, such as lithium bromide,
Metal salts such as sodium bromide, potassium bromide, iron bromide, cobalt bromide, calcium bromide, copper bromide, and ammonium bromide, tetramethylammonium bromide, tetraethylammonium bromide, tetrabutylammonium bromide, etc. Mention may be made of ammonium salts. Hydrobromic acid is preferred. The amount of bromine ions should normally be 3 equivalents or more.
The pH of the aqueous solution is 7 or less, preferably 5 or less.
When the pH of the aqueous solution was 7 or higher, the bromination reaction did not proceed at all. Furthermore, when the bromination reaction was carried out in a membraneless electrolytic cell at pH 14, no polymer could be recovered. In order to adjust the pH of the aqueous solution, mineral acids such as sulfuric acid and phosphoric acid, or organic acids such as formic acid, acetic acid, propionic acid, p-toluenesulfonic acid, and benzenesulfonic acid can be added in addition to the above salts. . In addition, to improve the conductivity of aqueous solutions, for example, sodium fluoroborate, sodium sulfate, p
-It is also possible to add inert salts to the reaction, such as tetrabutylammonium toluenesulfonate. The supporting electrolyte concentration is not particularly limited, but it is preferably 20 to 50% by weight. The present invention can be carried out by either a batch method or a circulation method, but the ratio of the organic phase to the aqueous phase of the anolyte is 1 to 500 parts by volume per 100 parts by volume of the aqueous phase.
parts by volume, preferably 10 to 300 parts by volume. If the amount of the organic phase in the electrolytic phase increases, the resistance of the electrolytic solution will increase.On the other hand, if the amount of the organic phase is too small, the efficiency of brominating the polymer will decrease, which is not preferable. Although there are no particular limitations on the catholyte, it is usually preferable to use an aqueous solution of the above-mentioned anolyte. The electrode used in the present invention may be any material as long as it is used in ordinary electrolytic reactions and is inert to the reaction system, and the cathode may be carbon, graphite, or any inert metal such as platinum or iron. , stainless steel, lead, nickel, alloys thereof, and metals thereof coated on metal substrates such as titanium and tantalum. For example, carbon, graphite,
Examples include platinum, lead dioxide, etc., and metal substrates such as titanium and tantalum coated with platinum, lead dioxide, ruthenium oxide, etc. The diaphragm may be any membrane as long as it is resistant to this reaction system, such as glass filters, ceramic filters, asbestos filters, fluorine-based cation exchange membranes, and fluorine-based anion exchange membranes proposed by the applicant. (Special application No. 57-227443
etc.). Preferably, it is a fluorine-based anion exchange membrane. The current density when carrying out the present invention is 0.1 mA/cm ² ~
0.5A/ ^cm2 , preferably 1mA/ ^cm2 to 0.3A/ ^cm2 . The present invention is usually carried out at room temperature, but can be carried out under heating or cooling if necessary. At that time, the electrolysis temperature is preferably 100°C or lower. When brominating such a polymer, in the reaction system,
In particular, the presence of excess free bromine in the organic phase tends to cause polymer chain scission. This is observed when high molecular weight polymers are brominated or when the polymers are brominated to a high degree. Therefore, it is desirable to perform a treatment to remove free bromine. Examples of such treatment include blowing inert gas such as nitrogen and argon to the main reaction, or reducing the pressure in the system. Although this bromination reaction can be carried out without stirring, it is preferable to thoroughly mix the organic and aqueous phases to obtain the best results. According to the present invention, it is possible to polymerize a vinyltoluene monomer and bromine the polymer without isolating the polymer, and the molecular weight distribution of the brominated polyvinyltoluene produced is You can make something almost exactly the same. Furthermore, by changing the amount of current applied, brominated polyvinyltoluene having an arbitrary bromine content can be produced. The present invention provides a method for easily and simply producing brominated polyvinyltoluene with a narrow molecular weight distribution, which cannot be achieved by conventional methods, and has great industrial significance. Hereinafter, the present invention will be explained in more detail with reference to Examples. Reference example Manufacturing method of fluorine-based anion exchange membrane CF ₂ = CF ₂

The copolymer obtained by copolymerization with [Formula] is made into a film (thickness: 100
μ, SO ₃ H exchange capacity: 0.92 milliequivalents/g dry membrane), and then hydrolyzed. Next, after treatment with 2NHCl, the membrane was converted into sulfonyl chloride and then subjected to oxidation treatment to carboxylate the membrane. The thus obtained carboxylic acid film was heated at 120° C. for 24 hours in phosphorus pentachloride-phosphorus oxychloride (weight ratio 1:1.6).
Furthermore, after washing in carbon tetrachloride, it was dried. This film shows strong carbonyl absorption at 1800 cm ^-1 in the infrared spectrum. The acid chloride membrane obtained above was immersed in dry ether, dimethylamine gas was passed through the mixture under ice cooling, and the mixture was reacted for 6 hours under cooling and for 18 hours at room temperature. It was washed with a mixed solution of 1.5% sodium bicarbonate and methanol at 80°C for 5 hours, and dried under reduced pressure overnight. A colorless and transparent film was obtained, and in its infrared spectrum, 2930 and 1420 cm
C—H absorption was observed at ^-1 and absorption due to amide carbonyl was observed at 1700 cm ^-1 . Next, sodium borohydride was dissolved in dry diglyme under an argon atmosphere, and then the membrane obtained above was immersed. A dry diglyme solution of boron trifluoride ether complex was added dropwise to the solution under ice cooling. 1700 in the infrared spectrum by reacting for 5 hours under cooling and then for 18 hours at 100℃
cm ^-1 absorption disappeared, indicating that reduction to an amine film had completely progressed. After washing the obtained membrane with methanol, it was placed in a methanol solution of methyl iodide and incubated for 60 min.
The reaction was carried out at ℃ for 44 hours. After washing the obtained membrane with methanol, it was soaked in a methanol solution of lithium chloride for 60 min.
The reaction was allowed to take place at ℃ for 24 hours. The membrane was dissolved in methanol for 60 min.
The film was heated to 0.degree. C. to obtain the desired film having quaternary ammonium chloride groups. In a staining test, the obtained membrane was colored bluish-purple with bromocresol purple and reddish-purple with cresol red, confirming the presence of anion exchange groups. The exchange capacity of the anion exchange membrane is 0.86 meq/
The dried film had an electrical resistance of 3.2 g/cm ² and a transport number of 0.86. Example 1 20 g of p-vinyltoluene monomer repeatedly dehydrated using benzophenone sodium complex under a vacuum of 10 ^-5 mmHg and 500 ml of benzene were mixed and stirred, and a hexane solution of sec-butyllithium (concentration 5.0 x 10 ^-5 mol/ml) by adding 2.6 ml to 30
After polymerizing at ℃ for 2 hours, 2 methanol was added to the reaction solution.
ml was added to stop the polymerization. of the obtained polymer
Its weight average molecular weight is 1.7 from GPC/light scattering measurements.
×10 ⁵ , dispersity (w/n) defined as the ratio of weight average molecular weight (w) to number average molecular weight (n)
was 1.04. 9 ml of the above polymer solution, 6 ml of benzene, and 15 ml of 8.8N hydrobromic acid were placed in the anode chamber of a diaphragm type electrolytic cell using the fluorine-based anion exchange membrane shown in the reference example as a diaphragm. As catholyte, 8.8N
30ml of hydrobromic acid was used. The electrode is a coiled platinum electrode (0.7φ×30
mm) were used. Electricity was applied at 0.3 A for 50 minutes while flowing nitrogen over the anolyte and stirring the anolyte with a stirrer tip. At that time, the terminal voltage varied from 1.5V to 2.0V. After the reaction was completed, the organic phase was poured into 100 ml of methanol to obtain 0.58 g of brominated poly(p-vinyltoluene). As a result of elemental analysis, the bromine content was 40.5%. It was found that the bromination rate per repeating unit of p-vinyltoluene calculated from this value was 1.00. Furthermore, the results of GPC measurement showed that the degree of dispersion was almost the same as that of the raw material polymer. As a result of measuring the proton nuclear magnetic resonance spectrum, the raw material poly(p)
-vinyltoluene) in addition to the peak observed for δ
A peak attributable to methylene protons with brominated methyl groups was observed around 4.5 ppm (solvent: CDCl ₃ , internal standard TMS). Example 2 sec-Butyllithium hexane solution (concentration 5.0
Polymerization was carried out in the same manner as in Example 1 except that ¹¹ ml of poly(p-vinyltoluene)
A solution was obtained. The weight average molecular weight of poly(p-vinyltoluene) was 4.2×10 ⁴ and the degree of dispersion was 1.02.
Using 15 ml of this polymer solution, bromination was carried out in the same manner as in Example 1 except that the current value was 0.5 A and the current application time was 40 minutes to obtain 0.86 g of brominated poly(p-vinyltoluene). . The terminal voltage during electrolysis is approximately
It was 6V. The bromination rate per repeating unit of p-vinyltoluene calculated from elemental analysis was found to be 1.03. As a result of GPC measurement, the degree of dispersion of the brominated poly(p-vinyltoluene) was almost the same as that of the raw material polymer. Examples 3 to 7 Electrolysis was carried out in the same manner as in Example 2, except that the poly(p-vinyltoluene) solution prepared in Example 2 was used, various aqueous solutions were used, and the amount of current was the same as in Example 2. Bromination was performed. Table 1 shows the results.
Shown below. As a result of GPC measurement, the degree of dispersion of each brominated poly(p-vinyltoluene) was almost the same as that of the raw material polymer.

[Table] Example 8 As vinyltoluene monomers, m- and p
-Mixture of vinyltoluene (m/p ratio: 60/
40) was used, but the same method as in Example 2 was used to obtain 0.59 g of brominated polyvinyltoluene. The terminal voltage during electrolysis varied from 1.8V to 2.5V.
The bromination rate per vinyltoluene unit calculated from elemental analysis was 0.92. Example 9 25 ml of the polyvinyltoluene solution prepared in Example 2 and 8.8N bromide were placed in the anode chamber of a diaphragm electrolytic cell having a ceramic filter as a diaphragm and two plate-shaped graphite electrodes (30φ x 2t) as electrodes. 25 ml of hydrogen acid and 30 ml of hydrobromic acid were placed in the cathode chamber, and electricity was applied at 0.2 A for 2.35 hours. The terminal voltage is
It changed from 28V to 16V. After electrolysis, the organic phase was poured into 200ml of methanol, and brominated poly(p-
(vinyltoluene) 0.93g was obtained. The bromination rate per vinyltoluene unit calculated from the elemental analysis value is:
It was 0.47. From the results of GPC measurement, the degree of dispersion of the brominated polyvinyltoluene was 1.08. Example 10 Polyvinyltoluene solution prepared in Example 2
Put 12.5ml of 8.7N hydrobromic acid into an electrolytic cell with a side tube, and use a coiled platinum electrode (0.7φ x 30
The electrolyte was stirred well with a magnetic stirrer using two tubes (mm), and energized at 0.5 A for 40 minutes. The terminal voltage varied from 3V to 2V. After the energization was completed, 0.52 g of brominated polyvinyltoluene was obtained in the same manner as in Example 2. The bromination rate per vinyltoluene unit calculated from elemental analysis was 0.19. As a result of GPC measurement, the degree of dispersion of the polymer was 1.06.

Claims (1)

[Claims] 1 A vinyl toluene monomer is polymerized in the presence of an organometallic compound represented by the general formula RM (R is selected from an alkyl, aryl, or aralkyl group, and M is selected from lithium, sodium, or potassium), and the polymer solution and bromide ions are polymerized. A method for producing brominated polyvinyltoluene by applying electricity in the presence of an aqueous solution.