KR790001076B1 - Process for polymerization of acrylonitrile - Google Patents

Abstract

Acrylonitrile polymer and copolymer were manufd. in the molten state by a polymn. conducted at >120≰C under excess pressure in the presence of 3-50wt. % H2O (with respect to total monomer wt.) Thus, 0.8 parts monomer mixt. (90% acrylonitrile and 10% Meacrylate) and 0.2 parts H2O were sealed along with 1% tert-Bu2O3 catalyst and 1% polymn. inhibitor in a glass tube and polymd. at 100≰-220≰C for 20-60min. A transparent viscous polymer in predominately molten state was obtained at 130≰C- 220≰C.

Description

Polymerization Method of Acrylonitrile

The present invention relates to a novel polymerization method of acrylonitrile-based monomers, and more particularly, to acrylonitrile alone or a mixture of monomers containing the same, which is polymerized under high pressure under the presence of a small amount of water under substantially high temperature. It relates to a method for producing a polymer.

As is well known, acrylonitrile-based polymers are useful as polymers for fibers, films, and other molded articles having excellent properties, but unlike polymers such as polyamides and polyesters, they are not melted by heating. It is necessary to use organic solvents such as dimethylformamide, dimethylacetamide, dimethyl sulfoxide and ethylene carbonate, and inorganic solvents such as concentrated aqueous solution of thiocyanate, concentrated aqueous solution of zinc chloride and concentrated aqueous solution of nitric acid. For example, in the manufacture of fibers, acrylonitrile-based polymers are prepared by a water-soluble polymerization method using a large amount of water, as known from US Pat. No. 2,404,725-2,404,728 and the like. After dissolving in solvent to make spinning stock solution, it is adopted to form fiber by wet spinning method or dry spinning method. However, in this method, the process of acrylonitrile polymerization and polymer dissolving are complicated. A large amount of water is used during polymerization and washing of the resulting polymer, and the dissolution of the polymer requires a large amount of thermal energy and the loss of monomers resulting from the formation of polymerization byproducts, the necessity of removing such by-products, and the use of expensive solvents. From the standpoint of industrial productivity, such as the necessity and the need to recover and purify the solvent, Is accompanied by defects.

In addition, a solution polymerization method for polymerizing monomers in the presence of a solvent capable of dissolving the produced polymer is employed as a method of performing the polymerization process and the dissolving process of the polymer in the same process. Inevitably, the recovered solvents as well as the solvent recovery have various problems, such as the need to be highly purified to avoid adverse effects on the polymerization.

As a method for obtaining a molded article without using such a solvent, a molding method for molding an acrylonitrile polymer under high temperature and high pressure and a casting method for simultaneously performing polymerization and molding are known. Besides the defects that separate the molding process and require high pressure molding operation and long time polymerization operation, there is an inherent problem that it is difficult to manufacture fine products such as fibers because extrusion is not successful in this method.

Accordingly, the present inventors have studied a polymerization method for producing a polymer that can be extruded without polymerization at all without using a solvent to solve the above problems. As a result, monomers containing acrylonitrile alone or acrylonitrile are found. It has been found that the acrylonitrile-based polymer in a substantially molten state can be prepared by polymerizing the mixture under a certain pressure and temperature in the presence of a small amount of water.

Accordingly, a first object of the present invention is to provide a new polymerization method of acrylonitrile monomers capable of producing a polymer in a substantially molten state.

A second object of the present invention is to achieve the polymerization of acrylonitrile-based monomers and the melting of the polymers obtained from these monomers in a simple process of the day.

It is a third object of the present invention to provide a method for converting an acrylonitrile monomer into a polymer that is flowable and substantially in a molten state by a short polymerization operation.

The fourth object of the present invention is to provide an industrially advantageous acrylonitrile-based polymer that can be directly provided to molding operations such as spinning, film forming, or extrusion by energy saving, high productivity, and simplified processes. will be.

Other objects of the present invention will become apparent from the following detailed description of the invention.

The above object of the present invention as described above is based on the monomer mixture consisting of acrylonitrile alone or acrylonitrile as the main component and at least a certain other ethylenically unsaturated compound as the residual component, based on the total weight of the monomer and water, 3-50 weight It is achieved by polymerization under a pressure above the vapor pressure generated in the polymerization system under polymerization conditions at a temperature of 120 ° C. or higher in a system in which water is present in the% range, and by adopting such a polymerization method, it is substantially in a molten state and thus fluidity It was possible to obtain a homogeneous and transparent acrylonitrile-based polymer. In particular, in this method, by using an oil-soluble radical generator having a decomposition temperature of 80 ° C. or more, which has a half-life of 10 hours as the polymerization catalyst, the polymerization can be carried out uniformly and effectively while avoiding the runaway reaction, and therefore, an object of the present invention. The effect can be more satisfactorily and successfully achieved in this way. The phenomenon in which the acrylonitrile-based polymer melted under the special polymerization conditions under the pressurized heating is not yet fully understood. However, acrylonitrile-based polymers may be formed by synergy of unreacted monomers remaining in the polymerization product and water. It is speculated that the cohesion due to the -C = N group interactions between the polymer molecular chains is significantly weakened and as a result the resulting polymer is extremely easy to melt.

This pressurized homogeneous polymerization of the present invention is a monomer mixture composed of acrylonitrile homopolymerization or acrylonitrile (preferably at least about 75% by weight) as a main component and composed of at least one other ethylenically unsaturated compound as a residual component. It is used to polymerize. Other ethylenically unsaturated compounds that can be used as copolymerization components include known unsaturated compounds copolymerizable with acrylonitrile, such as vinyl halides and vinylidene halides such as vinyl chloride, vinyl embrittlement, vinyl fluoride and vinylidene chloride; Unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid and itaconic acid and salts thereof; Acrylic acid esters such as methyl acrylate, butyl acrylate, octyl acrylate, methoxy acrylate, phenyl acrylate, cyclohexyl acrylate; Methacrylic acid esters such as acrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, methoxyethyl methacrylate, phenyl methacrylate, and cyclohexyl methacrylate; Unsaturated ketones such as methyl vinyl ketone, phenyl vinyl ketone and methyl isopropenyl ketone; Vinyl esters such as vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate and vinyl benzoate; Vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; Acryl amide and its substituted compounds; Unsaturated sulfonic acids and salts thereof such as vinylsulfonic acid, allylsulfonic acid metaallylsulfonic acid, and P-styrenesulfonic acid; styrene such as a-methylsulfonic acid and chlorostyrene and alkyl or halogen substituted compounds thereof; Allyl alcohol and its ester or ether; Basic vinyl compounds such as vinylpyridine, vinylimidazole and dimethylaminoethyl methacrylate; And vinyl compounds such as acrolein, metaacrolein, vinylidene cyanide, glycidyl methacrylate, and methacrylonitrile.

As described above, the pressure homogeneous polymerization method of the present invention using monomers is remarkably different from the conventional water-soluble suspension polymerization method, emulsion polymerization method, solution polymerization method or bulk polymerization method in that a small amount of water is present in the polymerization system. That is, unlike the bulk polymerization method which does not contain water at all in a polymerization system, or the water-soluble polymerization method or solution polymerization method in which several tens of% or more of water or a solvent exists in a polymerization system, this invention is a total amount of the monomer and water which comprise a polymerization system. 3-50% by weight, preferably 5-30% by weight and most preferably 5-20% by weight of water are used. In addition, the polymerization system needs to be maintained at a pressure higher than the vapor pressure generated under the polymerization conditions. As the polymerization temperature, a temperature of 120 ° C. or higher, preferably 130 ° C. or higher should be adopted. By satisfying such polymerization conditions, a transparent acrylonitrile polymer melt having fluidity can be obtained, but using polymerization conditions outside this range makes it difficult to achieve the objects and effects of the present invention. Moreover, it is preferable that the upper limit of polymerization temperature is 300 degrees C or less, especially 250 degrees C or less in consideration of degradation of polymer quality, such as decomposition and coloring.

The polymerization of the present invention is carried out in a closed system or using a polymerization apparatus having a suitable pressurization mechanism and maintained at a pressure above the vapor pressure (self-generating pressure) generated in the polymerization system under polymerization conditions, generally about 3 atmospheres or more. Any pressure may be employed as long as the polymerization pressure is equal to or higher than the vapor pressure. For example, the polymerization operation of the present invention can be carried out at a pressure of 100 atm or more, but at a pressure of at least 100 atm, but generally in consideration of taking the industrial operation or the produced polymer melt from the polymer and forming it into a fiber, a film or the like. It is suitable to polymerize at -50 atmospheres.

As a polymerization initiation means used in the present invention, all methods known to date, such as radical polymerization using radical generators such as organic peroxides, azo compounds and the like, direct photopolymerization by ultraviolet irradiation, or photosensitization polymerization in which a photosensitizer coexists Or polymerization by √-ray irradiation. The selection of these polymerization initiation means is determined by the polymerization conditions, the polymerization apparatus used, the use of the polymer produced, and the like. In particular, the object and effect of the present invention are decomposition temperature within 10 hours, that is, the amount of use is decomposed within 10 hours. It is satisfactorily achieved by using as an catalyst an oil-soluble radical generator whose temperature can be 80 degreeC or more, Preferably it is 100 degreeC or more. This is because the oil-soluble radical generator prevents the runaway reaction, facilitates the polymerization operation, and can easily obtain a high molecular weight polymer having a uniform molecular weight.

Such oil-soluble radical generators are, for example, di-tert-butyl diperoxyphthalate, tert-butyl hydroperoxide, di-tert-butylperoxide, 2,5-dimethyl-2,5-di-tertiary Organic peroxides such as -butyl-peroxyhexane; And azo compounds such as 4-azobis-4-cyanopentanoin amide and 1-azobis-1-cyclohexanecarbonitrile.

Moreover, it is preferable that the usage-amount of a catalyst is generally 0.01-3 weight% especially 0.1-2 weight% based on the weight of a monomer or monomer mixture.

Molecular weight control of the polymer produced in the present invention is not only by changing the amount of catalyst soaking or irradiation of light or √-rays, but also known amines, alcohols, benzene-substituted compounds, chloroform, mercapto compounds, ketones, and the like. It can also be carried out by using a chain isotropic agent.

In the practice of the present invention, a method is often employed in which a polymerization retardant is added to a polymerization system in order to suppress the occurrence of a sudden polymerization reaction and to avoid a sudden abnormal pressure rise.

Pressurized homogeneous polymerization of the present invention is initiated in a mixed solution containing a monomer and a specific amount of water, and used as necessary, a catalyst and a immersion agent, while in the form of a powder or granules in the above-mentioned polymerization reaction consisting of a monomer and water. The polymerization may also be initiated by the presence of a preformed acrylonitrile-based polymer of the type (the polymer is free from any polymer produced by any polymerization method). In this case, the polymerization system at the start of the polymerization is heterogeneous, but as the polymerization proceeds, the polymerization liquid is converted into a homogeneous phase, and finally, it is possible to obtain a transparent polymer fluid in a substantially molten state. In order to improve the properties of the resulting polymer, for example, additives such as colorants, heat stabilizers, flame retardants, antistatic agents, UV stabilizers, pigments, etc. may be added to the polymerization system in an amount that does not adversely affect the pressure homogeneous polymerization of the present invention. It does not interfere at all.

In the practice of the present invention, depending on the conditions such as polymerization temperature and polymerization rate, the polymerization liquid may be a slightly turbid liquid which is not completely transparent at the beginning of the polymerization but exhibits fluidity, but at the end of the polymerization, the polymerization liquid is transparent and viscous. Since it becomes a uniform phase, the implementation of the present invention does not interfere at all even after the polymerization process.

The polymerization time in the method of the present invention varies depending on the polymerization start means, the type and amount of catalyst used, the polymerization temperature, etc., but generally a value in the range of 10 minutes-2 hours, preferably 20 minutes-1 hours . Thus, it can be said that one of the advantages of the present invention is that the pressure homogeneous polymerization of the present invention is performed within a short time. The polymerization of the present invention can be carried out either batchwise or continuously or in a combination of both.

The transparent homogeneous acrylonitrile polymerization fluid in a substantially molten state produced according to the polymerization method of the present invention can be operated as spinning, film formation, molding, etc. in a state as it is. This melt is particularly suitable for extruding directly into regions characterized by lower temperature and lower pressure in the reactor to form fibers or films. In addition, this melt contains solvents for acrylonitrile-based polymers (eg, aqueous solutions of inorganic salts such as zinc chloride and thiocyanate; inorganic solvents such as nitric acid; dimethylformamide, dimethyl-acetamide, dimethyl sulfoxide, and γ-parts). After mixing under the pressure of organic solvents such as tyrolactone, ethylene carbonate, and the like, a molded article such as fiber, film, etc. can be produced by wet spinning, dry spinning, etc. In addition, the polymer melt is heated as it is (pressure) of the polymerization system. When lowered, polymer foams can also be obtained.

In the present invention, since a value in the range of about 60-97% is adopted as a practical polymerization rate, some unreacted monomers remain in the obtained molten polymer, but such unreacted monomers may be used in a suitable method during processes such as spinning, film formation, and molding. It is recovered and reused.

As described above, according to the present invention, it is possible to greatly simplify the polymerization process and to significantly reduce the amount of water and thermal energy used, and to obtain a molded product without using it as a solvent, thereby avoiding the problem of solvent recovery and its high purity. There is an advantage that it can. In addition, according to the present invention, since the polymerization is carried out in a homogeneous system, heat transfer is easily performed, and therefore, accumulation of heat and congestion reaction in the polymerization system can be suppressed, and homogenization of the polymerization reactant can be attempted. It is also equipped with industrially advantageous features, such as showing the fluidity at the same time as polymerization, which makes the transport of the polymer very easy.

The method of the present invention can be advantageously carried out even at a low pressure of 50 atm or less, which is quite industrially advantageous in view of the structure of the reactor and production efficiency. Also, the polymerization process and the melting process can be performed simultaneously in one step to simplify the process. The extremely advantageous point can be seen as a big feature. Other features of the present invention include the fact that the amount of polymerized part products that reduce monomer loss is very small and that the molecular weight of the polymer obtained is uniform.

The present invention is described in more detail with reference to the following examples, but the scope of the present invention is not limited by these examples. Parts and percentages in the examples are by weight unless otherwise defined.

Example 1

A monomer mixture consisting of 90% acrylonitrile and 10% methyl acrylate, based on the weight of the monomer mixture, 1% di-tert-butyl having a decomposition temperature of 124 ° C. at a half-life of 10 hours as a catalyst. 1% of 3,5-di-tert-butyl-4-hydroxytoluene was mixed and dissolved as a peroxide and a polymerization retardant. Next, 0.8 parts of the monomer solution and 0.2 parts of water were added to a hard glass tube having an inner diameter of 5 mm and a length of 150 mm and the lower end was sealed, and the glass tube was sealed after replacing the space portion of the glass tube with nitrogen gas. The glass tube containing the obtained polymerization product was left standing in an oil bath, and the polymerization was carried out under various polymerization conditions shown in Table 1 below. As a result, in all cases where the polymerization temperature was 130-220 ° C, A polymer was obtained. The polymerization results are shown in Table 1. When the polymerization temperature was 115 ° C., only a white choke-like polymer having no fluidity (not molten) was obtained. At the polymerization temperature of 100 ° C., however, a slurry-like polymerization product was obtained.

When only the above-mentioned monomer solution (containing no water) was sealed in a glass tube and polymerized at 160 ° C. for 60 minutes, only a white choke polymer having no fluidity was obtained.

TABLE 1

Example 2

A solution of the various monomer mixtures shown in Table 2 is carried out in which 1% di-tert-butyl peroxide as a catalyst and 1% 3,5-di-tert-butyl-4-hydroxytoluene are dissolved as a polymerization retardant. The polymerization was carried out in a sealed glass tube as in Example 1. 0.2 parts of water was mixed with 0.8 parts of monomer solution. The polymerization temperature is 160 ° C., and the polymerization time is 30 minutes. All the polymerization products thus obtained were transparent aggregates showing good fluidity and were observed to be substantially molten.

On the other hand, when the above polymerization was repeated without adding any water, only the white choke polymer having no fluidity was obtained even when the monomers were combined in any proportion.

TABLE 2

Example 3

Dissolved in a monomer mixture consisting of 90% acrylonitrile and 10% methyl acrylate with 1% 3,5-di-tert-butyl-4-hydroxytoluene as a polymerization retardant and various catalysts shown in Table 3. To prepare several polymerization solutions. Next, 0.2 parts of water was mixed with 0.8 parts of a polymerization liquid and polymerized in a sealed glass tube for 30 minutes at 160 ° C., whereby a transparent polymerized animal in substantially molten state was obtained in all cases. The polymerization results are shown in Table 3. have.

TABLE 3

Example 4

A monomer mixture consisting of 90% acrylonitrile and 10% methyl acrylate was dissolved with 1% of each of the various chain transfer agents shown in Table 4 and 0.5% of di-tert-butyl peroxide as a catalyst. Next, 0.8 parts of the monomer solution and 0.2 parts of water were sealed in a hard glass tube as in Example 1, followed by polymerization in an oil bath at 150 ° C. for 60 minutes to give a substantially molten state with an appropriately controlled molecular weight. Transparent polymerized animal was obtained. The polymerization results are shown in Table 4.

TABLE 4

Example 5

The monomer mixture consisting of 90% acrylonitrile and 10% methylacrylate was dissolved in di-tert-butyl peroxide as a catalyst in the amounts shown in Table 5, respectively. Next, 0.8 parts of each monomer solution and 0.2 parts of water were sealed in a glass tube as in Example 1, and then left to polymerize in an oil bath at 160 ° C. for 30 minutes to give a transparent polymer in a substantially molten state. The polymerization results are shown in Table 5.

TABLE 5

Example 6

It was dissolved as a catalyst in 0.5% di-tert-butylperoxide in a monomer mixture consisting of 90% acrylonitrile and 10% methylacrylate. The mixing ratio of this monomer solution and water was changed as shown in Table 6. As a result of polymerization of the mixed solution at 160 ° C. for 30 minutes as in Example 1, transparent polymerized animals were obtained in a substantially molten state in any case. The polymerization results are shown in Table 6.

TABLE 6

Example 7

의 세공을 가지는 노즐이 장착되어 있다. 중합관은 가열 매체로서 에틸렌글리콜을 사용하여 155℃로 가열되도록 되어 있다. 중합을 시작할 때 중합관의 출구측으로 된 노즐세공을 밀폐시킨 다음 플런저펌프를 시동하여 단량체 용액과 물을 공급한다. 이때 중합압력이 항상 약 10-15kg/㎠(계기압력)에 유지되도록 노즐세공의 밀폐상태를 조절한다. 중합이 진행되어 용융상태의 중합체가 노즐세공으로부터 토출되는 시점에 있어서 노즐의 차단물을 제거하여 연속적이고 안정된 중합체 용융물의 토출이 이루어지게 한다.Continuous polymerization was performed using a stainless steel polymerization tube having an internal diameter of 10 mm and having a kenics mixer (manufactured by Kenics, USA) installed inside as a mixing mechanism. One end of the polymerization tube is connected to the plunger pump through a stainless steel pipe of 3mm Φ, and the other end is 0.7mm

The nozzle which has a pore of is mounted. The polymerization tube is heated to 155 ° C using ethylene glycol as the heating medium. At the start of the polymerization, the nozzle pore to the outlet side of the polymerization tube is sealed and the plunger pump is started to supply the monomer solution and water. At this time, adjust the closed state of the nozzle pore so that the polymerization pressure is always maintained at about 10-15kg / ㎠ (gauge pressure). When the polymerization proceeds and the molten polymer is discharged from the nozzle pore, the blockage of the nozzle is removed to allow continuous and stable discharge of the polymer melt.

By following this method, the monomer mixture consisting of 90% acrylonitrile and 10% methylacrylate is subjected to continuous polymerization under the following polymerization conditions.

Feed rate of monomer solution 1.6 parts / minute

0.4 parts / minute water supply

Catalyst (di-tert-butylperoxide) 1.0%

Retardant (2, 6-di-tert-butyl-4-methylphenol) 1.0%

The acrylonitrile copolymer melt was stably discharged from the nozzle pore mounted on the outlet side of the polymerization tube. The catalyst and the retarder were dissolved in the monomer solution and supplied.

Example 8

It was dissolved as catalyst in 0.5% di-tert-butylperoxide in a monomer mixture consisting of 90% acrylonitrile and 10% methylacrylate. The mixed solution was polymerized at 150 ° C. for 60 minutes in the same manner as in Example 1. As a result, in each case, a polymerized animal in a substantially molten state was obtained. The polymerization results are shown in Table 7 below.

TABLE 7

Example 9

A monomer mixture consisting of 90% acrylonitrile and 10% methylacrylate, 1% di-tert-butylperoxide as a catalyst and 0.8% benzylamine as a chain transfer agent (the percentages are relative to the weight of the monomer mixture). ) Was mixed and dissolved.

This monomer solution was then mixed with water in the proportions shown in Table 8 and then polymerized at 120 ° C. for 35 or 60 minutes in the same manner as in Example 1.

The polymerization product thus obtained became a transparent polymer with good fluidity when the monomer / water ratio was 50 / 50-90 / 10, but about 30% insoluble when the monomer / water ratio was 35/65 and 20/80 It became the semi-melt polymer which a part exists. The polymerization results are shown in Table 8.

TABLE 8

Example 10

A monomer mixture consisting of 90% acrylonitrile and 10% methylacrylate was dissolved as 0.5% or 1.0% di-tert-butylperoxide as a catalyst. Next, each monomer solution was mixed with water at a ratio of 80/20 or 65/35 (monomer / water), and then each mixed solution was polymerized in a sealed container at 150 ° C. for 60 minutes in the same manner as in Example 1 to obtain good results. A polymer melt showing fluidity was obtained.

When the polymer melt thus obtained was taken out with a normal pressure gauge under a heated state, any polymer became a good foam.

Claims (1)

Polymerization of a monomer mixture comprising acrylonitrile alone or acrylonitrile as a main component and the balance of at least one other ethylenically unsaturated compound in a system in which water within a range of 3-50% by weight relative to the total amount of monomers and water is present. A novel polymerization method for acrylonitrile-based monomers, characterized in that an acrylonitrile-based polymer in a substantially molten state is produced by polymerization at a temperature of 120 ° C or higher under a pressure equal to or higher than the vapor pressure generated in the polymerization system under conditions.