JP3773587B2 - Purification method for organic compound monomers - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for purifying an organic compound monomer used for vapor deposition polymerization in which an organic compound monomer is evaporated to perform polymerization.
[0002]
[Prior art]
In recent years, a vapor deposition polymerization method has been proposed in which a polymer thin film is formed by evaporating an organic compound monomer of an organic compound in a vacuum and polymerizing it on a substrate.
[0003]
FIG. 6 shows an example of a general vapor deposition polymerization apparatus.
As shown in FIG. 6, this vapor deposition polymerization apparatus 101 has a processing chamber 102 capable of maintaining an airtight state, and this processing chamber 102 is connected to an external vacuum pump (not shown) or other vacuum exhaust system. A substrate 103 on which a polymer thin film is to be formed is held downward by the substrate holder 104 in the upper part of the processing chamber 102, and the substrate 103 is heated to a desired temperature on the back side of the substrate holder 104. A heater 105 is provided.
[0004]
On the other hand, an evaporation source for evaporating the organic compound monomers a and b is provided below the processing chamber 102 so as to oppose the substrate 103. The evaporation source is provided with evaporation containers 106 and 107 made of glass, for example, and heating heaters 108 and 109 and temperature sensors 110 and 111 are provided in the vicinity of the evaporation containers 106 and 107, respectively. It is configured so that the evaporation rate of the organic compound monomers a and b is always kept constant.
[0005]
A partition plate 112 is provided between the evaporation containers 106 and 107 to prevent mixing of the vapors of the organic compound monomers a and b, and above the heaters 108 and 109 for heating, A shutter 113 is provided for preventing vapor mixture of the organic compound monomers a and b.
[0006]
Conventionally, as an example of forming a polymer thin film using such an apparatus, 4,4′-diphenylmethane diisocyanate (MDI) and 4,4′-diaminodiphenylmethane (MDA) are used. A method for forming a film is known.
[0007]
[Problems to be solved by the invention]
However, such a conventional vapor deposition polymerization method has the following problems.
That is, when MDI and MDA described above are evaporated by heating to 70 ° C. and 100 ° C., respectively, in a vacuum to form a polyurea film on the substrate 103, if the vapor deposition is continued under the same temperature conditions, The film composition obtained in the initial stage of the film and the film obtained after about 12 hours are not the same in the composition ratio of the monomer of the thin film, so that stable insulating properties, piezoelectric properties, and pyroelectric properties cannot be obtained. There was a problem.
[0008]
That is, in the past, commercially available monomers of organic compounds were used for vapor deposition polymerization as they were, so the impurities contained in the monomers evaporated during the heating of the monomer, and the vapors of the impurities evaporated the monomer near the evaporation surface. This hinders the problem that a stable evaporation rate of the monomer cannot be obtained, and the composition ratio of the monomer contained in the resulting polymer thin film is different.
[0009]
In this case, if vapor deposition is continuously performed for about 24 hours, impurities are almost released, so that the composition ratio of the monomer becomes almost constant. However, in this case, the efficiency of removing impurities is poor, and the vapor deposition polymerization itself is efficient. The problem of not being able to do well occurred.
[0010]
The present invention has been made to solve the problems of the conventional technology, and provides a method for purifying an organic compound monomer capable of efficiently removing impurities contained in the organic compound monomer and stabilizing the deposition rate. It is intended to do.
[0011]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have heated the organic compound monomer at a predetermined temperature in a vacuum for a predetermined time, thereby stabilizing the evaporation rate during heating during vapor deposition polymerization. The present inventors have found that an organic compound monomer can be obtained, and have completed the present invention.
[0012]
That is, the invention described in claim 1 is a method for purifying an organic compound monomer used for vapor deposition polymerization in which a plurality of organic compound monomers are evaporated in a vacuum to perform polymerization on a substrate, and before performing the vapor deposition polymerization, for each of the plurality of organic compound monomer, evaporation rate in a vacuum chamber for removing impurities is heated for a predetermined time in each of the evaporation rate from the lower temperature in the said deposition polymerization, of the plurality of organic compound in the monomer It is characterized by removing impurities.
Further, as in the invention according to claim 2, in the invention according to claim 1, the monomer is heated to a temperature at which the evaporation rate of the monomer is 2 × 10 ⁻⁸ g / cm ² · sec or less, and the monomer is converted into the monomer. It is also effective to remove impurities contained therein . In this case, the lower limit of the evaporation rate of the monomer is not particularly limited, but it is more effective to heat the monomer to a temperature at which the evaporation rate is higher than about 1 × 10 ⁻¹⁰ g / cm ² · sec.
Furthermore, as in the invention of claim 3, in the invention of claim 1 or 2, the film formation by vapor deposition polymerization of the plurality of organic compound monomers is the formation of a polyurea film. It is effective.
Furthermore, as in the invention according to claim 4, in the invention according to claim 3, it is also effective when the impurity in the organic compound monomer is aniline or 4-methyl-2,6-ditertiary butylphenol. is there.
On the other hand, various organic compound monomers can be used. In particular, as in the invention described in claim 5 , 4, 4′-diphenylmethane diisocyanate (MDI) and 4 It is more effective to use 4′-diaminodiphenylmethane (MDA).
[0013]
In the case of the present invention, before performing vapor deposition polymerization, a plurality of organic compound monomers (for example, MDI, MDA, etc.) are heated to remove impurities in the monomers, so that during the heating of each monomer in vapor deposition polymerization, Since vapor due to impurities is not generated and each organic compound monomer is evaporated smoothly, a stable evaporation rate of the monomer can be obtained during vapor deposition polymerization . As a result, the composition ratio of the monomers contained in the generated polymer thin film is kept constant.
In this case, each of the evaporation rate from the lower temperature in the evaporation rate vapor deposition polymerization in a vacuum, in particular, motor Nomar plurality of organic to a temperature evaporation rate is ^{2 × 10 -8 g / cm 2} · sec or less for When the compound monomer is heated, each organic compound monomer does not evaporate so much during heating, and the impurities are mainly evaporated and removed.
Further, according to the present invention, each of the plurality of organic compound monomers is heated in the vacuum tank for removing impurities to remove the impurities, so that the monomer composition is obtained by evaporating for a long time in the vapor deposition polymerization apparatus. Compared with the conventional method of stabilizing the ratio, the use efficiency of the vapor deposition polymerization apparatus can be improved.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of a method for purifying an organic compound monomer according to the present invention will be described in detail with reference to the drawings.
[0015]
FIG. 1 shows a schematic configuration of an example of a vacuum processing apparatus to which the present invention is applied.
As shown in FIG. 1, this vacuum processing apparatus 1 has a vacuum chamber 2 capable of maintaining an airtight state, and this vacuum chamber 2 is connected to an external vacuum pump (not shown) or other vacuum exhaust system via a vacuum valve 6. 7 is connected.
[0016]
A heater 3 for heating the vacuum chamber 2 is wound around the vacuum chamber 2. In this case, as shown in FIG. 1, the heater 3 is wound around the entire top, bottom, left, and right of the vacuum chamber 2 in order to perform uniform heating.
[0017]
In the vacuum chamber 2, a plurality of containers 4 for accommodating the organic compound monomer 5 can be arranged. In the present embodiment, for example, three containers 4A, 4B, and 4C are arranged, and organic compounds monomers 5A, 5B, and 5C such as MDI and MDA are accommodated in the containers 4A, 4B, and 4C. The container 4 may be either an evaporation container or a reagent bottle arranged in the vapor deposition polymerization apparatus.
[0018]
When purifying the organic compound monomer 5 using the vacuum processing apparatus 1 having such a configuration, the container 4 into which the organic compound monomer 5 is injected is placed inside the vacuum chamber 2, and the degree of vacuum of the vacuum chamber 2 is set. While adjusting to a high vacuum (about 1 × 10 ⁻³ Pa), the vacuum chamber 2 is heated by the heater 3 for a predetermined time.
[0019]
In the present embodiment, the organic compound monomer 5 is heated in vacuum to remove the impurities, so that vapor due to the impurities is not generated during the heating of the monomer in the vapor deposition polymerization, and the evaporation is performed smoothly. A stable evaporation rate of the organic compound monomer 5 is obtained. As a result, the composition ratio of the monomer in the generated polymer thin film can be kept constant, and the insulation characteristics, piezoelectricity, and pyroelectric characteristics can be stabilized.
[0020]
In this case, the organic compound monomer 5 is heated to a temperature at which the evaporation rate of the monomer is 2 × 10 ⁻⁸ g / cm ² · sec or less so that the evaporation rate in vacuum is lower than the evaporation rate during vapor deposition polymerization. For example, the organic compound monomer 5 hardly evaporates at the time of heating, and the impurities are mainly evaporated and removed, so that the impurities can be efficiently removed.
[0021]
Further, according to the present embodiment, since a plurality of containers 4 can be accommodated in the vacuum chamber 2, a conventional method of stabilizing the monomer composition ratio by evaporating for a long time in the vapor deposition polymerization apparatus. Compared to the above, the use efficiency of the vapor deposition polymerization apparatus can be improved.
[0022]
【Example】
Hereinafter, examples of the method for purifying an organic compound monomer according to the present invention will be described in detail.
As shown in FIG. 1, a container 4A filled with MDI as an organic compound monomer 5A is placed inside the vacuum chamber 2, heated to 47 ° C. in a high vacuum (1 × 10 ⁻³ Pa), and left for 60 hours. The impurities were removed.
[0023]
Further, a container 4B filled with MDA as the organic compound monomer 5B is placed inside the vacuum chamber 2, heated to 60 ° C. in a high vacuum (1 × 10 ⁻³ Pa), and left for 12 hours to remove impurities. went.
[0024]
Then, these containers 4A and 4B are mounted on a general vapor deposition polymerization apparatus and evacuated to a predetermined degree of vacuum, and then the respective containers 4A and 4B are heated to 70 ° C. and 100 ° C. to obtain organic compound monomers 5A, 5B was evaporated to form a polyurea film on the substrate.
[0025]
When continuous deposition of the polyurea film was performed by such a method, the relative permittivity of the polyurea film formed immediately after the start of deposition was 4.3. Further, the relative dielectric constant of the polyurea film after 1 hour from the start of deposition is 4.0, and thereafter, a polyurea film having a relative dielectric constant of 4.0 ± 0.05 is stably obtained over 30 hours. It was.
[0026]
Next, the effect | action of a present Example is demonstrated in detail using FIGS.
FIG. 2 is a graph showing a change with time of a typical peak of a mass spectrum obtained when MDI, which is a commercially available organic compound monomer, is heated to 47 ° C. in a vacuum.
[0027]
Here, since MDI has a molecular weight of 250, curve A where m / e (m is the mass of the ion, e is the charge of the ion) = 250 represents MDI, and is added to the commercially available MDI. Since the molecular weight of 4-methyl-2,6-ditertiary butylphenol is 205, curve B with m / e = 205 is attributed to this.
[0028]
As shown in FIG. 2, it is understood that when MDI is heated to 47 ° C. in a vacuum, the curve B showing the peak intensity of the impurity component decreases with time, and the impurity component contained in the monomer is almost eliminated after about 60 hours. Is done.
[0029]
On the other hand, FIG. 3 is a graph showing a change with time of a typical peak of a mass spectrum obtained when MDA, which is a commercially available organic compound monomer, is heated to 60 ° C. in a vacuum.
[0030]
Here, since MDA has a molecular weight of 198, curve C with m / e = 198 represents MDA, but curve D with m / e = 93 represents aniline contained as an impurity in commercially available MDA. It is estimated that
[0031]
As shown in FIG. 3, when the MDA monomer is heated to 60 ° C. in a vacuum, the curve D indicating the peak intensity of the impurity component decreases with time, and the impurity component contained in the monomer is almost eliminated after about 10 hours. Understood.
[0032]
FIG. 4 is a graph showing the relationship between the evaporation temperature of MDI and the evaporation rate.
As can be seen from FIG. 4, at the evaporation temperature of 47 ° C. of MDI in the example, the evaporation amount of MDI as a monomer is small, which is one more than the evaporation amount at 70 ° C., which is the evaporation temperature during vapor deposition polymerization. The value is more than one digit. Therefore, according to the method of this example, the impurity gas can be efficiently removed from the MDA monomer.
[0033]
FIG. 5 is a graph showing the relationship between the evaporation temperature of MDA and the evaporation rate.
As can be seen from FIG. 5, the evaporation amount of MDI as a monomer is extremely small at 60 ° C., which is the evaporation temperature of MDI in the example, and is smaller than the evaporation amount at 100 ° C., which is the evaporation temperature during vapor deposition polymerization. The value is almost two orders of magnitude smaller. Therefore, according to the method of the present embodiment, it is possible to efficiently remove the impurity gas even for MDI.
[0034]
【The invention's effect】
According to the present invention as mentioned above, the steam due to impurities during heating of the monomer in the vapor deposition polymerization does not occur, since the evaporation is carried out smoothly, it is possible to stabilize the deposition rate of that.
Thereby, the composition ratio of the monomer in the polymer thin film formed by vapor deposition polymerization can be kept constant, and there is an effect that its insulating characteristics, piezoelectricity, and pyroelectric characteristics can be stabilized.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an example of a vacuum processing apparatus to which the present invention is applied. FIG. 2 is a representative mass spectrum obtained when MDI, which is a commercially available monomer, is heated to 47 ° C. in a vacuum. [Fig. 3] A graph showing a time-dependent change of a typical peak of a mass spectrum obtained when MDA, which is a commercially available monomer, is heated to 60 ° C. in a vacuum. [Fig. 4] FIG. 5 is a graph showing the relationship between the evaporation temperature and the evaporation rate of MDI. FIG. 5 is a graph showing the relationship between the evaporation temperature and the evaporation rate of MDA. FIG. 6 is a schematic diagram showing an example of a general vapor deposition polymerization apparatus. Explanation】
DESCRIPTION OF SYMBOLS 1 ... Vacuum processing apparatus, 2 ... Vacuum tank, 3 ... Heater, 4 (4A, 4B, 4C) ... Container, 5 (5A, 5B, 5C) ... Organic compound monomer, 6 ... Vacuum valve, 7 ... Vacuum exhaust system

Claims (5)

A method for purifying an organic compound monomer used for vapor deposition polymerization in which a plurality of organic compound monomers are evaporated in a vacuum and polymerized on a substrate,
Before performing the vapor deposition polymerization, for each of the plurality of organic compound monomer, each of the evaporation predetermined time lower than consisting temperature rate during evaporation rate the vapor deposition polymerization in a vacuum in the vacuum chamber for removing impurities A method for purifying an organic compound monomer, which comprises heating and removing impurities in the plurality of organic compound monomers. 2. The organic compound monomer according to claim 1, wherein the monomer is heated to a temperature at which the evaporation rate of the monomer is 2 × 10 ⁻⁸ g / cm ² · sec or less to remove impurities contained in the monomer. Purification method. 3. The method for purifying an organic compound monomer according to claim 1, wherein the film formation by vapor deposition polymerization of the plurality of organic compound monomers is formation of a polyurea film. The method for purifying an organic compound monomer according to claim 3, wherein the impurity in the organic compound monomer is aniline or 4-methyl-2,6-ditertiary butylphenol. Organic compound monomer is 4,4'-diphenylmethane diisocyanate and (MDI), 4,4 '- diaminodiphenylmethane (MDA) organic compound monomer according to any one of claims 1 to 4, characterized in that it is Purification method.

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