JPS62277413A - Highly stereo-regular acrylic polymer suitable for molding - Google Patents

Abstract

PURPOSE:To obtain the titled polymer having extremely high meso-chain fraction and remarkably excellent solubility, by polymerizing a clathrate compound of urea and acrylonitrile in the presence of a chain transfer agent under radiation. CONSTITUTION:A clathrate compound of urea and acrylonitrile is polymerized in the presence of a chain transfer agent (preferably mercaptan such as ethyl mercaptan) under radiation, preferably radiation of gamma ray to obtain the objective polymer. The fraction of 4-meso-chains in the acrylonitrile chain of the polymer is >=40% calculated from the <13>C MNR cyanocarbon peak intensity ratio determined in a deuterated dimethyl sulfoxide solution and the weight- average molecular weight of the polymer is <=400,000 determined by light- scattering method. Concretely, the polymer can be produced e.g. by impregnating a solution of a chain transfer agent in a mixture of acrylonitrile and urea, clathrating the composition and irradiating the clathrate compound with radiation.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention is directed to a material having an extremely high meso (m) chain fraction and excellent solubility necessary for molding into a final product. The present invention relates to a polyacrylonitrile (hereinafter abbreviated as PAN)-based polymer and a method for producing the same.

[Conventional technology]

PAN polymers are generally used in clothing fibers, ultrafiltration membranes,
It is widely used as a raw material for carbon fiber. but,
Generally used PAN polymers are obtained by redox polymerization, and their mmmm (five chain moieties of acrylonitrile) fraction is at most 8% and their crystallinity is low. Therefore, the mechanical properties of the final molded product are not fully satisfactory. Particularly in the textile field, problems such as lack of stiffness, poor repulsion, and extreme lack of dimensional stability due to heat (commonly referred to as ``thermal set'') have led to widespread use of PAN fibers in the industrial materials field. The current situation is that the potential functions of PAN are not being fully utilized.

PAN U, monomer chain is meso (m) or racemo (r)
Because it is composed of a series of polymers, it is theoretically possible to obtain a polymer with extremely high stereoregularity, which is expected to dramatically improve the mechanical properties of the final product. Polypropylene is a well-known example of a material whose properties have been successfully improved by improving its stereoregularity. As mentioned above, PAN
When a system polymer is polymerized using a redox catalyst, the probability that m is connected is approximately equal to the probability that r is connected, and the mmmm fraction is theoretically only 10% or less. Although many examples using transition metal catalysts have been reported, there are no examples in which the m-chain fraction is improved. The only method that increases the m-chain fraction is D, M, Whlta (Journal of American Chemical Society, Vol. 82).

The only known method is the so-called radiation polymerization method, which involves irradiating a clathrate compound of acrylonitrile (hereinafter abbreviated as AN) and urea with radiation such as X-rays or do not have.

In this method, the 1mmmm fraction is improved compared to the redox system, but it is only 38% at most. Moreover, its average molecular weight is as high as 500,000 or more, and it does not have the good solubility required for molding into final products, so its usage is currently extremely limited. Of course, conventional PA
Compared to N, its solubility is inferior even when compared at the same molecular weight.

[Problem that the invention seeks to solve]

The main object of the present invention is to provide a PAN polymer having a high mmmm fraction and significantly improved solubility by improving the radiation polymerization described above, and a method for producing the same.

[Means for solving problems]

That is, the polymer of the present invention has a mmmm fraction of 40 or more calculated from the 13C-positive noanocargon peak of a solution of the polymer dissolved in deuterated dimethyl sulfoxide, and which is determined by a light scattering method. It is a PAN-based polymer suitable for molding and has a weight average molecular weight of 400,000 or less.

The mmmm chain referred to in the present invention refers to a chain of five acrylonitrile monomers (pentad tuffities) all connected in a meso configuration. A specific evaluation method for the above-mentioned fraction is shown below. FIG. 1 shows 13C-r☆m of one example of the polymer of the present invention. The symbols attached to the peaks in the figure indicate pentad toughness. This peak was identified using the method of Ueda et al. (Polymer Journal).

17, p. 1291 (1985)).

mmmm fraction is monodeuterated methyl sulfoquine DM
13C-NMR of the solution dissolved in so-d), the peak based on cy7nocargon (119-121 pprn: T
As seen in the peak identification in Figure 1, the m m m m VChli! It refers to the fraction (%) of the peak intensity of the cyano carbon peak intensity in the portion where the cyano carbon is removed, and is calculated from the integral ratio or area ratio of each peak. During measurement, in order to increase resolution and provide quantitative performance, we particularly focused on the cyanocarpine region (119-121p).
pm: TMS standard) and observed ±500 Hz around the peak. A JEOL Fourier transform NMR (FX-200) was used as an apparatus, deuterated dimethyl sulfoxide was used as a solvent, and the sample concentration was adjusted to 3 to 20 MIk%. The measurement conditions were: temperature 80°C, observation frequency @ 1000Hz, data points:
The pulse width was set to 6.5 μ5 (45°), the pulse delay time was 25 μS, the sampling time was 8.1 m, and the number of calculations was 64×10 to 64×I00.

Further, the average molecular weight of the polymer of the present invention is the weight average molecular weight determined by the following light scattering method. LS 601 manufactured by Union Giken was used as an apparatus, and special grade dimethyl sulfoxide was used as a solvent. The incident light is F(e-Ne radar)
The wavelength of the incident light is 633 nm.

The temperature is 25°C. Just in case, the measurement of differential refractive index AN/AC is done by Union Giken! ! ! RM102 differential refractometer (
λ, = 633 nm).

Generally, the solubility of PAN is influenced by the intertwined factors of mm fraction and average molecular weight. The higher the mm fraction,
Furthermore, the higher the average molecular weight, the lower the solubility. Even PAN with a mmmm fraction of about 38 fl obtained by the conventional method has significantly inferior solubility compared to PAN of the same molecule (2) with a mmmm fraction of 8 fl. The present inventors conducted extensive studies and found that PAN with a mmmm fraction of 4096 or more has extremely poor solubility when the molecular weight exceeds 400,000, and dimethylformamide (hereinafter abbreviated as DMF), a common solvent for PAN, 120
It will not dissolve unless heated for a long time above ℃, and the solvent may even change in quality during the dissolution process. Although it is apparently soluble in concentrated nitric acid and dimethyl sulfoxide (DMS), the polymer concentration range used for molding dope (here,
(10% or more), the remaining incompletely dissolved dulls and the elasticity of the solution itself will result in a dope with no stringiness at all.
Even if it is formed into fibers or membranes, only those with extremely poor mechanical strength can be obtained.

In this sense, the molecular weight of the polymer of the present invention needs to be 400,000 or less. In particular, in the polymer of the present invention, the degree of polymerization is preferably 200,000 or less from the viewpoint of producing a dope suitable for high concentration and easy molding.

The polymer of the present invention has a strong interaction between adjacent acrylonitrile monomer units due to the high mmmm fraction (Ueda et al., Polymer Journal, Vol. 17).

1233 (1985)) and at the same time intermolecular interactions (Nakajiro, Ueda et al., Journal of the Japan Institute of Textile Science, Vol. 33, T-139 (1)
977)) may also have regularity and have a high apparent degree of crystallinity. Furthermore, basic research by the present inventors has revealed that interactions between adjacent monomer units impart rigidity to molecular chains.

Therefore, when molded into fibers or the like, it is expected that a high modulus of elasticity will be imparted and that thermal dimensional stability will be improved.

In fact, the polymers of the invention have a higher melting point in the presence of water than PAN obtained by conventional redox polymerization. In addition, the present inventors have already reported Polymer Journal, Vol. 18, 27.
7 (1985), some metals specifically and selectively coordinate to the mn+mm linkage.
The polymer of the present invention, which has a high mm fraction, has the advantage that it can be developed into molded articles having completely new functions by mixing with metal ions or forming a coordination complex.

The polymer of the present invention having various advantages as described above can be produced by the following method.

That is, the most important feature of the production method of the present invention is that the urea/containing clathrate compound is irradiated with radiation in the presence of a chain transfer agent. The use of a chain transfer agent is basically aimed at suppressing an unnecessary increase in the molecular weight of the resulting polymer and improving its solubility properties, but it also serves as a secondary purpose to increase the mmmm fraction. PAN obtained by conventional radiation polymerization
It also brings about the completely unexpected effect of being able to increase

A urea/AN clathrate containing a chain transfer agent can be prepared as follows. Add a predetermined amount of chain transfer agent to A
Either dissolve or disperse in N, mix with urea that has been reprecipitated in a water/methanol system, and form a complex at low temperature, or
There is a method in which the /urea mixture is impregnated with a solution in which a chain transfer agent is dissolved or dispersed in a solvent having an extremely small chain transfer constant, such as an alcohol, and then clathrated. The chain transfer agent used in the present invention has a chain transfer constant of 5. OX1
In addition to 0-' or more, mercaptans, sulfides, hydroquinones, carbon halides, and amines, those with double bonds such as vinyl compounds and acrylic compounds are preferably used. . Chain transfer constant is 5.0
If it is less than X10, even if used in a large amount, it will not have the effect of lowering the molecular weight, nor will it have the effect of increasing the mmmm fraction. The amount of chain transfer agent used should be appropriately selected depending on its chain transfer constant, but generally for AN,
0.01 molti or more is required. Although there is no upper limit to the amount used, there is no point in using too much excess. In order to efficiently obtain the polymer of the present invention in a small amount, it is preferable to use mercaptans.
It is sufficient to use 3 molti. If about 0.01 mol% is used, the molecular weight will be approximately 300,000. Moreover, when using 01 to 3 molti, the molecular weight can be suppressed to 200,000 or less. When using a chain transfer agent with double bonds, there is a possibility of copolymerization with AN, so the resulting P
m of the acrylonitrile chain without impairing the properties of AN.
It is necessary to suppress the amount used to such an extent that it does not cause adverse effects on the mmmmmmmm ratio, and it is preferably less than 5 molar ratio to AN. Specific examples of chain transfer agents include mercaptans such as ethyl mercaptan, n-propyl mercaptan, isopropyl mercaptan, n-butyl mercaptan, and n-
Amyl mercaptan, l5O-amyl mercaptan, 3
ec-amylmercaptan, tert-amylmercaptan, n-hexylmercaptan, n-hebutylmercaptan, n-octylmercaptan1. n-dodecyl mercaptan, p-)luenethiol, etc. Sulfides include hydrogen sulfide, methyltetrasulfide, diphenyl sulfide, ethyl sulfide,
Benzyl sulfide, pennoldimethylthiocarbamoyl sulfide, butyl sulfide, tart-butyl sulfide, and hypenzoylnosulfide 9, phenyl sulfide,
disulfide, substituted nobenzoylnosulfide such as bis-p-bromobenzoyl disulfide, substituted dibenzoyl disulfide such as bis-p-bromophenyl disulfide, p-aninyyl disulfide, ethyl disulfide, p-toluoyl disulfide, p-tolyl disulfide , butyl disulfide, 8@C-butyl disulfide, tert-butyl disulfide, hexyl disulfide, methyl disulfide, naphthyl disulfide, propyl disulfide, acetyl disulfide, and the like.

Hydroquinones include hydroquinone, hydroquinone diacetate, hydroquinone noethyl ether, hydroquinone dimethyl ether, hydroquinone monopennor ether, and hydroquinone monomethyl ether. Peroxides include coumesohydroperoxide, t-butyl hydroxide, dicumyl peroxide, no-t-butyl, J-oxide, and R-Nzoi A.
//#-oxide, lauroyl-4-oxide, diacetyl-mono-oxide, dideropionyl-5-oxide, etc.

Examples of amines include tributylamine, triethylamine, trimethylamine, and tripropylamine, and examples of halogenated carbons include carbon tetrachloride and carbon tetrabromide. Further, examples of vinyl compounds include vinylpyridine and alkyl-substituted vinylpyridine, vinyl halides such as vinyl pyridine, vinylidene chloride, and vinyl bromide, and vinyl carboxylates such as vinyl formate and vinyl acetate. brewed methyl,
Ethyl acrylate, octyl acrylate, cyclohexyl acrylate, other acrylic esters and butyl methacrylate, lauryl methacrylate, other Nisder methacrylates, acrylic acid, acrylamide methacrylate, methacrylamide and N-fQ substituted acrylamide, N- Examples include substituted methacrylamide.

The ratio of urea to AN in the clathrate compound is not limited due to the use of a chain transfer agent, but in consideration of the yield of the final polymer, it is preferably 1:1 to 3:1 (molar ratio). used for. AN that does not contribute to inclusion with urea acts as a type of chain transfer agent.

X-rays or gamma rays, preferably gamma rays, are generally used as radiation sources. Generally, when the irradiation dose (irradiation weight rate X time) is increased, the irradiation dose increases by 0.5
Within the range of 5R, the molecular weight increases up to a certain amount, but beyond that amount, the molecular weight hardly changes. The mmmm fraction shows a decreasing tendency. On the other hand, when a chain transfer agent is present in the system, the molecular weight is almost constant within the above dose range, and the mmmm fraction changes only slightly.

Therefore, the irradiation dose in the present invention is not limited either.

〔Example〕

The present invention will be further explained below with reference to Examples.

Example I A chain transfer agent in the amount shown in Table 1 was added to AN s o g, and the chain transfer agent and urea, which had been recrystallized and purified in advance in a methanol/water system, were mixed in a molar ratio of AN/urea = 1/1.5. 2 in proportion
The mixture was placed in a J volume stainless steel dewar bottle, mixed and sealed, and then allowed to stand for 7 days while being cooled to -78°C with dry ice. Next, it was irradiated with gamma rays of 10,000 curies at -78°C for 3 hours at an irradiation dose rate of 1.6 x 105 Len In-'77 hours.Then, the reaction product was washed with warm water and methanol to completely remove the urea. .

As a comparative example, the above polymerization reaction was carried out under the same conditions without adding a chain transfer agent and using acetonitrile and dimethylformamide as a chain transfer agent having a chain transfer constant of 5 and oxlo-' (60°C) or less.

The mmmm fraction and weight average molecular weight ff1Mw of the PAN polymer obtained in each example are listed in Table 1.

As is clear from Table 1 below, Experimental Examples 1 to 5 according to the present invention have higher mmmm fractions (lower MW) than Comparative Examples 1 to 3.

Example 2 AN 70,! 7, add 0.01, 0.02, 0.09, and 0.23 mol of n-butylcaptan, respectively,
Urea was added and gamma rays were irradiated in the same manner as in Example 1. However, the irradiation time was adjusted so that the irradiation dose was 5.0, 3.5, 2.8, and 1.5 Roentgen in descending order of the amount of n-butyl mercaptan added. Next, Example 1
Urea was removed in the same way. The mmmm fraction and Mw of the obtained polymer are as follows in order of decreasing amount of mercaptan added:
(1) 44.2%, 3.65X10, (2143
, 5%, 2.35X10: (3) 44.3%, 1.
83X10 @(4) 44.8%, 0.95X10
It was 5. When these PAN polymers were dissolved in a 70 weight nitric acid aqueous solution at a concentration of 15% by weight at room temperature, M
The solution with w of 0.95×10° and 1.83×105 had no undissolved matter and exhibited stringability suitable for spinning. Mw is 2.3
The solution of 5xl O5,3,65x105 had slightly poor stringiness, and the sample of Comparative Example 1 of Example 1 showed almost no stringiness.

Example 3 PAN with bottomed out mmmm fraction of 7.7% using conventional redox catalyst (MW=1.7X]O0)
and PAN with mmmm fraction of 58.6% obtained in Example 1
(MW=1.84XIO5) was used as a sample, and its melting behavior in the presence of water was measured using a DSC20 model differential scanning calorimeter manufactured by Seiko Electronic Industries, Ltd. 10. O
q and 10 μm of distilled water were placed in a sealed silver cell and sealed, and the melting curve was measured at a heating rate of 5° C./ml. The heat of fusion ΔH was calculated from the melting peak area by connecting the points on the melting curve at the melting start temperature and the melting end temperature of the melting curve with a line. The PAN of the present invention has a melting peak temperature of 189.7°C,
ΔH is 61.7mJA+, while P of the conventional method
The AN was 183.8° C. and 48.3 mJ/Da, respectively, and it was confirmed that the PAN of the present invention has good thermal stability, especially stability in the presence of water, and high crystallinity.

[Brief explanation of the drawing]

FIG. 1 is a 15C-NMR spectrum in the cyanocarbon region of PAN using DMSO-d6 as a solvent, and the assignment of stereoregularity (pentad chain) is shown in the figure. Here, m indicates meso configuration and r indicates racemo configuration.

Claims (1)

[Claims] 1. Measured in deuterated dimethyl sulfoxide solution^
The fraction of four meso chain parts among the acrylonitrile chain parts calculated from the cyano carbon peak intensity ratio of 1^3C NMR is 40% or more, and the weight average molecular weight determined by the light scattering method is 400,000 or less. A polyacrylonitrile polymer suitable for molding. 2. The polymer according to claim 1, which has a weight average molecular weight of 200,000 or less and a dissolution temperature of 115° C. or less when dissolved in dimethylformamide at a polymer concentration of 5%. 3. A method for producing a polyacrylonitrile polymer suitable for molding, which comprises polymerizing urea and an acrylonitrile clathrate compound by radiation in the presence of a chain transfer agent. 4. The manufacturing method according to claim 3, wherein the chain transfer agent is a mercaptan, a sulfide, a hydroquinone, an amine, a halogenated carbon, a vinyl compound, or an acrylic compound. 5. The manufacturing method according to claim 3, wherein the chain transfer agent is a mercaptan, and is used in an amount of 0.01 to 3 mol% based on acrylonitrile.